Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security (NATO Science for Peace and Security Series C: Environmental Security) 940241911X, 9789402419115

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NATO Science for Peace and Security Series - C: Environmental Security

Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security

Edited by Anatolie Sidorenko Horst Hahn

AB3

Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security

NATO Science for Peace and Security Series This Series presents the results of scientific activities supported through the framework of the NATO Science for Peace and Security (SPS) Programme. The NATO SPS Programme enhances security-related civil science and technology to address emerging security challenges and their impacts on international security. It connects scientists, experts and officials from Alliance and Partner nations to work together to address common challenges. The SPS Programme provides funding and expert advice for securityrelevant activities in the form of Multi-Year Projects (MYP), Advanced Research Workshops (ARW), Advanced Training Courses (ATC), and Advanced Study Institutes (ASI). The NATO SPS Series collects the results of practical activities and meetings, including: Multi-Year Projects (MYP): Grants to collaborate on multi-year R&D and capacity building projects that result in new civil science advancements with practical application in the security and defence fields. Advanced Research Workshops: Advanced-level workshops that provide a platform for experts and scientists to share their experience and knowledge of security-related topics in order to promote follow-on activities like Multi-Year Projects. Advanced Training Courses: Designed to enable specialists in NATO countries to share their security-related expertise in one of the SPS Key Priority areas. An ATC is not intended to be lecture-driven, but to be intensive and interactive in nature. Advanced Study Institutes: High-level tutorial courses that communicate the latest developments in subjects relevant to NATO to an advanced-level audience. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series reflect the views of participants and contributors only, and do not necessarily reflect NATO views or policy. The series is published by IOS Press, Amsterdam, and Springer, Dordrecht, in partnership with the NATO SPS Programme. Sub-Series A. B. C. D. E.

Chemistry and Biology Physics and Biophysics Environmental Security Information and Communication Security Human and Societal Dynamics

http://www.nato.int/science http://www.springer.com http://www.iospress.nl

Series C: Environmental Security

Springer Springer Springer IOS Press IOS Press

Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security edited by

Anatolie Sidorenko D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia and

Horst Hahn Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany KIT-TUD Joint Research Laboratory Nanomaterials, Institute of Materials Science, TU Darmstadt, Darmstadt, Germany

Published in Cooperation with NATO Emerging Security Challenges Division

Proceedings of the NATO Advanced Research workshop on Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security Chisinau, Moldova 4–17 May 2018 ISBN 978-94-024-1911-5 (PB) ISBN 978-94-024-1908-5 (HB) ISBN 978-94-024-1909-2 (eBook) https://doi.org/10.1007/978-94-024-1909-2

Published by Springer, P.O. Box 17, 3300 AA Dordrecht, The Netherlands. www.springer.com Printed on acid-free paper

All Rights Reserved © Springer Nature B.V. 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Preface

Over the last decade, techniques of preparation and materials processing at a nanometer scale have developed rapidly and led to the invention of novel principles for a new generation of sensors and detectors, as quantum detectors, qubits, pi-junctions, spin valves, single-molecule electronic devices, SAW sensors, “artificial nose,” and chemical nano-chips. On the other hand, chemical industry, transport, and agriculture produce huge amount of dangerous waste gases and liquid substances, leading to soil, air, and water contamination. Implementation of pesticides and other dangerous chemicals in agriculture leads to strong contamination of surface and underground water sources and soil. One more modern threat, international terrorism demands scientists to make efforts toward the application of new principles and technologies to protect the society against CBRN (chemical, biological, radiological, and nuclear) threats and to develop novel effective technologies for deactivation of large contaminated areas. The main goal of the book, based on the selected reports presented at Advanced Research Workshop ( SPS.EAP.ARW.G5347, May 2019, Chisinau, Moldova), is to give an overview of the modern state of the art in the area of novel principles of functional nanostructures and detector fabrications, new technology developments for deactivation of CBRN agents, their experimental realization and their application in novel monitoring and control systems, and the technological processes for soil and water remediation, promising with respect to environmental protection and defense against CBRN terrorism. According to the main goal, the following subjects are highlited and discussed in 21 chapters of the book: • Detection of chemicals. Principles of “artificial nose” and chemical “micro-labon-a-chip” construction, surface and underground water monitoring systems, novel technological processes for pesticides destruction and deactivation are presented.

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• Detection of infrared, microwave, and terahertz radiation. Principles of novel IR, UV, and terahertz wave devices for detection of low contrast objects are considered. • Molecular electronics, printed electronics, superconducting electronics, and qubits. Major breakthroughs within the last years in experimental attempts to make quantum-coherent devices for quantum computing are related to molecular and superconductive implementations of qubits. This topic includes numerous coherent effects induced in normal and ferromagnetic metals by contact with nearby superconductors, electron, spin and heat transfer due to Andreev reflection processes, as well as anomalous properties of the Josephson current via ferromagnetic metals, leading to the development of novel sensors and switching base elements. All these topics are strongly interrelated both with respect to fundamental aspects and fabrication and implementation technologies. They address key topics in very active research fields along the borderline between nano-science, nanotechnology, superconductivity, and magnetism. The related phenomena are highly promising for application in novel functional devices, computer logics, sensing, and detection of low-concentrated chemicals, weak and extremely weak magnetic and microwave fields, and infrared and ultraviolet radiation. We believe that the book can attract the attention of researchers, engineers, Ph.D. students, and all others, who would like to gain knowledge about novel effects at nanoscale. Karlsruhe, Germany July 2019

Anatolie Sidorenko Horst Hahn

Foreword

The main goal of this book, based on the selected reports presented at NATO ARW G5347 (14–17 May 2018, Chisinau, Moldova), is to highlight the novel principles of functional nanostructures, sensors, detectors fabrication and new technology developments for detection and deactivation of CBRN agents. Novel monitoring and control systems, technological processes for soil, and air and water remediation, promising with respect to environmental protection and defence against CBRN terrorism, are presented in the book. According to the main goal, the following topics are highlighted: • Sensors and detectors – Detection of chemicals and principles of “artificial nose” and chemical “micro-lab on a chip” construction, surface and underground water monitoring systems, novel technological processes for pesticides and defoliants destruction and deactivation • Environmental protection and CBRN – Detection of infrared, microwave, X-ray and terahertz radiation and principles of novel IR-, UV- and terahertz-wave devices for detection of low contrast objects • Novel technologies – Molecular and printed electronics, superconducting electronics and qubits, leading to the development of novel sensors and switching base elements All these topics are strongly interrelated both with respect to fundamental aspects, fabrication and implementation technologies. They address key topics in very active research fields along the borderline between nanoscience, nanotechnology, superconductivity and magnetism. The related phenomena are highly promising for application in novel functional devices, computer logics, sensing and detection of low-concentrated chemicals, weak and extremely weak magnetic and microwave fields and infrared and ultraviolet radiation. The book will be useful for a broad audience of readers, including researchers, engineers, PhD graduates, students and others who would like to gain knowledge in the frontiers of functional nanostructures and sensors. The book consists of Preface, 21 Chapters and Conclusion. vii

Contents

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2

3

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Printing Technologies for Integration of Electronic Devices and Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tessy Theres Baby, Gabriel Cadilha Marques, Felix Neuper, Surya Abhishek Singaraju, Suresh Garlapati, Falk von Seggern, Robert Kruk, Subho Dasgupta, Benedikt Sykora, Ben Breitung, Parvathy Anitha Sukkurji, Uwe Bog, Ravi Kumar, Harald Fuchs, Timo Reinheimer, Morten Mikolajek, Joachim R. Binder, Michael Hirtz, Martin Ungerer, Liane Koker, Ulrich Gengenbach, Nilesha Mishra, Patric Gruber, Mehdi Tahoori, Jasmin Aghassi Hagmann, Heinz von Seggern, and Horst Hahn Development of Policy and Strategy of the Nanomaterials for Environmental Safety/Security by Radioactive/Nuclear Agents at Critical Infrastructure Facilities in Albania . . . . . . . . . . . Luan QAFMOLLA

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BORON10 Isotope Based Neutron Radiation Semiconductor Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Paata J. Kervalishvili

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Transmission of Two Measuring Signals by an Invariant Property of Three Wire Communication Lines . . . . . . . . . . . . . . . . Alexander Penin and Anatolie Sidorenko

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IR-Sensors and Detectors of Irradiation Based on Metal Folis . . . . B. B. Banduryan, M. I. Bazaleev, V. F. Klepikov, V. V. Lytvynenko, V. E. Novikov, A. A. Golubov, and A. Sidorenko

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Magnetoelectric Effect Driven by Reversible Surface Chemistry and Bulk Ion-Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. Molinari, S. Dasgupta, R. Kruk, and H. Hahn

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Contents

Antiferromagnetic-to-Ferromagnetic Transition in FeRh Thin Films with Strain Induced Nanostructure . . . . . . . . . . . . . . . . R. Witte, R. Kruk, D. Wang, R. A. Brand, and H. Hahn

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Thermally and Stress Induced Phase Transformations and Reversibility in Shape Memory Alloys . . . . . . . . . . . . . . . . . . . 105 O. Adiguzel

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The Toxic Effect of Trifluralin on Soil Microorganisms in the Presence of Fe0/PVP Nanoparticles . . . . . . . . . . . . . . . . . . . . 113 A. Sidorenko, I. Rastimesina, O. Postolachi, V. Fedorov, T. Gutul, and A. Vaseashta

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Management of Ransomware Detection and Prevention in Multilevel Environmental Monitoring Information System . . . . . . . 125 G. Margarov and E. Mitrofanova

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Organization of Assistance to Victims of a Thermal Trauma During the Pre-hospital and Hospital Stages in the Event of a Terrorist Attack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Vasyl Nagaichuk, Roman Chornopyshchuk, Andrii Povoroznyk, Mykhailo Prysyazhnyuk, Volodymyr Zelenko, and Igor Girnik

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Frequency Transducers of Gas Concentration Based on Transistor Structures with Negative Differential Resistance . . . . 161 A. V. Osadchuk and V. S. Osadchuk

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Chemical and Biological Defense in the South-Eastern European Countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 L. D. Galatchi

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Smart Surface with Ferromagnetic Properties for Eco- and Bioanalytics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 M. Pajewska-Szmyt, R. Gadzała-Kopciuch, A. Sidorenko, and Bogusław Buszewski

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Planning for Groundwater Protection: Monitoring Systems & Data Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 Konstantinos A. Papatheodorou and Konstantinos Ε. Evangelidis

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The Synergy Between Cyber and Nuclear Security. Case Study of Moldova . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Aurelian Buzdugan and A. Buzdugan

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Microbially-Mediated Decontamination of CBRN Agents on Land and Infrastructure Using Biocementation . . . . . . . . . . . . . 233 Volodymyr Ivanov and Viktor Stabnikov

Contents

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Point-Contact Sensors as an Innovative Tool in Defense Against Chemical Agents, Environment and Health Risks: A Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 G. V. Kamarchuk, А. P. Pospelov, L. V. Kamarchuk, A. V. Savytskyi, D. A. Harbuz, and V. L. Vakula

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New Method of Optical Spectroscopy for Environmental Protection and Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 Surik Khudaverdyan, Ashok Vaseashta, Mane Khachatryan, Mihail Lapkis, and Sergey Rudenko

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Smart and Connected Sensors Network for Water Contamination Monitoring and Situational Awareness . . . . . . . . . . 283 Ashok Vaseashta, Gheorghe Duca, Elena Culighin, Oleg Bogdevici, Surik Khudaverdyan, and Anatolie Sidorenko

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Processing of Superconducting and Thermoelectric Bulk Materials Via Laser Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . 297 Bekir Özçelik, G. Çetin, M. Gürsul, M. A. Torres, M. A. Madre, and A. Sotelo

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313

Chapter 1

Printing Technologies for Integration of Electronic Devices and Sensors Tessy Theres Baby, Gabriel Cadilha Marques, Felix Neuper, Surya Abhishek Singaraju, Suresh Garlapati, Falk von Seggern, Robert Kruk, Subho Dasgupta, Benedikt Sykora, Ben Breitung, Parvathy Anitha Sukkurji, Uwe Bog, Ravi Kumar, Harald Fuchs, Timo Reinheimer, Morten Mikolajek, Joachim R. Binder, Michael Hirtz, Martin Ungerer, Liane Koker, Ulrich Gengenbach, Nilesha Mishra, Patric Gruber, Mehdi Tahoori, Jasmin Aghassi Hagmann, Heinz von Seggern, and Horst Hahn Abstract Many different methods, such as screen printing, gravure, flexography, inkjet etc., have been employed to print electronic devices. Depending on the type and performance of the devices, processing is done at low or high temperature using precursor- or particle-based inks. As a result of the processing details, devices can be fabricated on flexible or non-flexible substrates, depending on their temperature stability. Furthermore, in order to reduce the operating voltage, printed devices rely on high-capacitance electrolytes rather than on dielectrics. The printing resolution and speed are two of the major challenging parameters for printed electronics. High-resolution printing produces small-size printed devices and high-integration densities with minimum materials consumption. However, most printing methods have resolutions between 20 and 50 μm. Printing resolutions close to 1 μm have also been achieved with optimized process conditions and better printing technology.

T. T. Baby · F. Neuper · S. A. Singaraju · F. von Seggern · R. Kruk · P. A. Sukkurji Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany G. C. Marques Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Chair of Dependable Nano Computing (CDNC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany S. Garlapati Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany School of Chemistry, Faculty of Science and Engineering, The University of Manchester, Manchester, UK © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_1

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The final physical dimensions of the devices pose severe limitations on their performance. For example, the channel lengths being of this dimension affect the operating frequency of the thin-film transistors (TFTs), which is inversely proportional

S. Dasgupta Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Department of Materials Engineering, Indian Institute of Science, Bangalore, India B. Sykora · H. von Seggern Institute of Materials Science, TU Darmstadt, Darmstadt, Germany B. Breitung · U. Bog · R. Kumar · M. Hirtz Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany H. Fuchs Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Department of Physics, University of Münster, Münster, Germany T. Reinheimer · M. Mikolajek · J. R. Binder Institute for Applied Materials – Energy Storage Systems (IAM-ESS), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany M. Ungerer · L. Koker · U. Gengenbach Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany N. Mishra · P. Gruber Institute for Applied Materials, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany M. Tahoori Chair of Dependable Nano Computing (CDNC), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany J. A. Hagmann Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Department of Electrical Engineering and Information Technology, Offenburg University of Applied Sciences, Offenburg, Germany H. Hahn (*) Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany KIT-TUD Joint Research Laboratory Nanomaterials, Institute of Materials Science, TU Darmstadt, Darmstadt, Germany e-mail: [email protected]

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to the square of channel length. Consequently, short channels are favorable not only for high-frequency applications but also for high-density integration. The need to reduce this dimension to substantially smaller sizes than those possible with today’s printers can be fulfilled either by developing alternative printing or stamping techniques, or alternative transistor geometries. The development of a polymer pen lithography technique allows scaling up parallel printing of a large number of devices in one step, including the successive printing of different materials. The introduction of an alternative transistor geometry, namely the vertical Field Effect Transistor (vFET), is based on the idea to use the film thickness as the channel length, instead of the lateral dimensions of the printed structure, thus reducing the channel length by orders of magnitude. The improvements in printing technologies and the possibilities offered by nanotechnological approaches can result in unprecedented opportunities for the Internet of Things (IoT) and many other applications. The vision of printing functional materials, and not only colors as in conventional paper printing, is attractive to many researchers and industries because of the added opportunities when using flexible substrates such as polymers and textiles. Additionally, the reduction of costs opens new markets. The range of processing techniques covers laterally-structured and large-area printing technologies, thermal, laser and UV-annealing, as well as bonding techniques, etc. Materials, such as conducting, semiconducting, dielectric and sensing materials, rigid and flexible substrates, protective coating, organic, inorganic and polymeric substances, energy conversion and energy storage materials constitute an enormous challenge in their integration into complex devices.

The concept of printing functional materials (semiconductors, metals, dielectrics etc.) to fabricate different electronic components for various applications has gained significant attention in academia and industry for the past few decades. The surge of interest is due to attractive features of printed materials such as low cost, large area and volume manufacturing on different types of substrates, roll-to-roll fabrication, etc. Printed electronics (PE) can play a major role in the Internet of Things (IoT), because PE can meet the requirements of large volume and inexpensive manufacturing of billions of tracking and monitoring devices, sensors etc. The field of PE is growing rapidly and quite a few products have already been developed and are now available on the market. However, there is still plenty of scope for further developments, especially in terms of processing and materials for high-performance devices. Though there are many different printing techniques available such as inkjet, screen printing, gravure printing, flexography etc., here we focus on devices fabricated by inkjet printing. Though printing technology was suggested for organic electronics some time ago, printing did not become the mainstream fabrication technique for making organic electronic devices. The main reason lies in the fact that the charge carrier mobility of solution-based organic semiconductors, the key property of semiconductor

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materials, is considerably lower than those of vacuum evaporated organic semiconductors, for which the carrier mobility values have increased by 6 orders of magnitude in the last 25 years [1, 2]. According to the Organic Electronics Association (OE-A), in the next 10 years organic semiconductors may reach their physical limits and inorganic nanomaterials may come into consideration for further performance improvements. Nanoscale inorganic materials, in the form of nanoparticles, nanowires, nanotubes, etc. can be formulated into inks that can then be printed into patterns, which determine the geometry and physical properties of the device layers. The latter may be conducting, semiconducting or dielectric layers, which may also show optoelectronic properties and thus can form a variety of electronic, optoelectronic and photovoltaic devices. In a field effect transistor (FET), the voltage applied to the gate electrode controls the charge carrier density of the semiconductor, which modulates the source-drain current. The charge carriers in the semiconductor can be either holes or electrons, depending on the utilized p-type or n-type semiconductor. Along with the semiconductor, the gating also plays a crucial role in determining the performance of these devices. Here, in the present article, we discuss oxide semiconductors and two different gating techniques for printed FETs. Furthermore, we introduce low and room temperature-processed devices that have been prepared by chemical and photonic curing methods.

1.1

Conventional and Electrolyte Gated Devices

The electric field distributions in (a) a conventional oxide and (b) an electrolytebased gate insulator induced by a positive voltage applied to the gate electrode of an n-type FET are displayed in Fig. 1.1. In a conventional dielectric, the electric field is distributed throughout the insulator [3], whereas in an electrolytic insulator the electric field is mainly concentrated at the electrode-electrolyte and electrolytesemiconductor interfaces by the formation of Helmholtz double layers. The strength of this electric field is higher than that of a conventional dielectric. As a result, higher gate capacitances (more than 1000 times) have been achieved with electrolytic

Fig. 1.1 Schematic cross-sections and illustrations of the electric field distribution inside the gate insulator when a positive gate potential is applied to an n-type FET with a conventional dielectric insulator and an electrolytic insulator

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Fig. 1.2 Representative transfer characteristics of (a) ink-jet printed zinc tin oxide (ZTO) top gate and (b) indium oxide (In2O3) in-plane gate field-effect transistors [5, 6]

insulators leading to lower operating voltages compared to conventional dielectrics [2, 4]. Moreover, electrolytes are easy to process by printing techniques and form smooth/conformal interfaces with the semiconductor, which can lead to superior electrical performances. Representative transfer characteristics of ink-jet printed zinc tin oxide (ZTO) transistors with top gate dielectrics and indium oxide (In2O3) transistors with in-plane electrolytic gates are displayed in Fig. 1.2 [5, 6]. Both ZTO and In2O3 semiconductors were printed from the respective precursor solutions and processed at 500
C and 400
C, respectively. Spin coated PMMA dielectrics and printed composite polymer electrolytes were used as gate insulators for ZTO and In2O3 based FETs, respectively. Figures of merit of those devices are listed in Table 1.1. It is clear from the table that the electrical characteristics of electrolyte-gated devices are as good as, sometimes better than, the classical dielectric-gated devices.

1.2

Room/Low Temperature Devices

The main drawback of the above-mentioned devices is the need of high processing temperatures. In order to use inexpensive flexible substrates, such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), the devices have to be processed at temperatures less than 140
C. Precursor-based inorganic functional

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Table 1.1 Figures of merit of different devices, fabricated at high temperatures, with conventional dielectric and electrolyte gating Material ZTO ZTO

T (
C) 500 500

Ion/Ioff ratio 3.2  108 6.7  105

VT (V) 7.0 1.7

μFET,sat (cm2/Vs) 7.76 4.3

ZTO In2O3

500 400

1.1  104 2  107

9.7 0.37

0.2 126

In2O3

500

3  105

0.16

63

Gate insulator SiO2 Poly(methyl methacrylate), (PMMA) Polystyrene (PS) Composite polymer electrolyte Composite polymer electrolyte

References [7] [5] [5] [6] [6]

materials always need high temperatures to process due to the decomposition of the precursor and the transformation to the oxide phase. Attempts have been made to reduce the process temperatures using different methods such as ‘sol–gel on chip’ [8] or ‘combustion synthesis’ [9] etc., however, in all these cases an unavoidable annealing routine has been involved and in most of the cases the annealing temperatures have exceeded 200
C, which is still higher than the glass transition temperatures of most of the inexpensive polymer substrates. In order to reduce the process temperature, Dasgupta et al. [10] have used crystalline In2O3 nanoparticulate inks to print the active channel and a printed electrolyte for the gating. Although the process temperature has been considerably reduced, the obtained field-effect mobility values of devices were low (0.8 cm2/Vs), which is due to poor densification of the printed films and the use of insulating surfactants to stabilize the nanoparticulate dispersions that alter electronic transport properties significantly. In order to solve the above-mentioned issue, a novel chemical curing method was used that enabled room-temperature processing of printed electrolyte-gated FETs (EGFETs) with field-effect mobility as high as 12.5 cm2/Vs [11]. In fact, according to our knowledge, this is the highest value that has been reported for a completely room temperature-processed oxide FET. The key idea behind chemical curing was chemically-controlled flocculation of printed In2O3 nanoparticle inks stabilized with electrosteric stabilization using a polymer ligand that can be cleaved and therefore ensures dense thin film formation and excellent interparticle electrical contacts. A halide compound was used as flocculation agent. A representative transfer curve of a device fabricated with this approach using an In2O3 nanoparticulate ink is shown in Fig. 1.3a. In order to demonstrate the versatility of this process, a similar approach has been followed to fabricate Cu2O based p-type FETs, which can lead to printed complementary metal oxide semiconductor (CMOS) inverters. The inverters exhibit an ideal rail-to-rail output voltage behavior with an estimated voltage gain (AV) as high as 14 at a supply voltage (VDD) of 1.25 V as can be seen in Fig. 1.3b.

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Fig. 1.3 (a) Transfer curve of In2O3 nanoparticulate FET and (b) electrical characteristics of CMOS inverter fabricated using In2O3 and Cu2O nanoparticulate inks with chemical curing method. Inset shows the circuit diagram of a CMOS inverter [11]

Table 1.2 Figures of merit of devices fabricated using UV-visible light curing and UV-laser curing techniques Technique Without curing UV-visible curing UV laser curing

Ion/Ioff ratio 1  105 2  106 1  106

SS (V/decade) 0.12 0.11 0.11

μFET,sat (cm2/Vs) 0.8 8 12

In another approach, photonic curing techniques have been used for low temperature process fabrication of devices on flexible plastic substrates using the same In2O3 nanoparticulate ink without flocculation agent [12]. The fabrication steps include printing of the heavily stabilized semiconducting nanoparticulate channel layer, followed by decomposition and removal of the stabilizer molecules or polymer ligands using high energy photons to ensure electronically superior semiconductor layers. The advantage of UV curing is the use of high energy photons for extremely short times (few seconds to minutes) that translates to high throughput processing and negligible substrate heating. Field-effect mobility (μFET) and subthreshold swing (SS) of devices fabricated with UV-visible light curing and UV laser curing are presented in Table 1.2 [12].

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Inkjet-Printed Passive Electrodes

In order to justify the name printed electronics, it makes sense to fabricate the electrodes as well using printing. By doing so, the resolution is no longer determined by external lithographic processes but by the printing process only. Using printing, it is easier to achieve complex shapes and structures. Moreover, it is less expensive and eliminates the subtractive fabrication step involved. The natural choice for printing conducting electrodes would be metal inks. Nanoparticles of silver are stabilized in an organic solvent and can be ink-jet printed. The challenge, however, is that the silver does not always exhibit a good chemical stability in combination with the semiconductor or electrolyte layer involved. Graphene inks offer higher stability at the interface and hence show more reliable electric contact. Graphene, which is a good conductor due to its zero bandgap, can be stabilized in the form of inks by coating with polymers like ethyl cellulose/nitrocellulose in organic solvents, such as cyclohexanone. Figure 1.4 show optical images of printed silver and graphene electrodes.

1.4

Vertical Field Effect Transistor (vFET)

Most of the above-mentioned devices have been fabricated using more than 10 μm channel lengths (due to the limited printing resolution) with an in-plane geometry, which limits the dynamic characteristics such as cut-off frequency, speed and over all performance. In order to resolve these issues and also to obtain high current density devices, we have, as a novel design, fabricated devices with a drastically different geometry, where the current flow is perpendicular to the plane of the substrate instead of being parallel to the substrate. Here, the channel length, i.e. the distance between source and drain electrodes, is not determined by printing resolution but by the thickness of the printed semiconducting layer, which can be controlled by the printing parameters. As channel polarization is a surface process, the material had to be constructed as a porous system filled with electrolyte. The resulting high surface areas had a positive effect on the current values. With this approach, channel lengths as low as 50 nm can be obtained and the resulting current density of a porous semiconducting channel was in the order of 106 A/cm2 [13]. Representative schematics of the in-plane and the vertical geometry as well as the Fig. 1.4 Printed (a) silver and (b) graphene passive electrodes

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Fig. 1.5 A representative schematic of (a) in-plane and (b) vertical geometry of source and drain electrodes. (c) Transfer curve of a vertical FET [13]

transfer curve of a vertical FET (vFET) are shown in Fig. 1.5. The experimental and simulation studies suggest that unlike traditional thin film transistors, the 3D bulkchannel vFET geometry allows charge accumulation in the bulk volume of the porous semiconductor materials, resulting in orders of magnitude higher on-currents than typical printed FETs. Consequently, this device type may find novel applications in all-printed power electronics useful for balancing circuits associated with energy-storage devices beyond the conventionally considered printed FETs.

1.5

Scanning Probe Lithography

As a complementary approach to the above-mentioned traditional and wellestablished printing methods, scanning probe lithography (SPL) poses an interesting route to functionalization and further miniaturization of printed electronics. Prominent techniques employed in the field are dip-pen nanolithography (DPN) [14, 15], where the tip of an atomic force microscope (AFM) is used like a quill-pen to write structures on a surface, and polymer pen lithography (PPL) [16–18], which is a hybrid technology of DPN and microcontact printing (μCP). These are maskless, room temperature processes that do not need any organic solvents or vacuum

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processing. Therefore, these techniques are well suited to process delicate inks containing sensitive compounds or biological active proteins. The multiplexing capability of SPL allows the incorporation of different compounds within the same micropattern, e.g., to present different chemical cues to the same cell in biological experiments [19, 20]. This technique can be used to construct multilayer printed transistor geometries in an integrated process by applying different layers one after another, utilizing the same stamp. Overall, SPL methods offer resolutions from the micro to nanoscale, dependent on the specific ink/ substrate system [21, 22]. In the context of printable electronics, SPL methods can principally be used in two ways: (I) as a means to deliver active materials on an already existing pre-structure that can be fabricated by other printing methods or photolithography, e.g., a passive sensor structure that is functionalized with an active material [23]. By introducing PPL like stamping methods in the above, fast parallelization of multiplexed functionalization can be achieved [24, 25]. (II) The methods can also be used to raise the resolution and thereby the performance of printed transistors. A printing resolution of 20 nm has been achieved with thiol on gold system [26]. An example of PPL-printed silver features for a transistor configuration is shown in Fig. 1.6. These features were obtained by inking a PPL stamp with a nanoparticulate silver ink, bringing the stamp into careful contact with the surface and dragging it along in the desired L and T shapes. This method can be used to fabricate massively parallel arrays (several ten thousands) of the desired structures over a square centimeter of surface. It is also possible to use the technique on flexible substrates. While the linewidth of the electrodes can be rather broad (~20 μm), the fine control gained by the AFM like SPL setup allows for very narrow electrodes, resulting, for example, in a channel length of about 5 μm and a gate distance of less than 1 μm. The height of such electrodes measured by AFM is about 100 nm. So, the switching speed of the transistor can be substantially raised by employing PPL while the printing process stays comparably uncomplicated compared to standard optical lithography.

1.6

Ring Oscillators Based on EGFETs with In2O3 Channel

One of the important applications of printed electronics are sensor systems. In such systems, the weak signals from a sensor are first amplified and then converted to digital form before being transmitted to external electronics. Voltage-controlled oscillators (VCOs) are key components of VCO-based analog-to-digital converters. Therefore, ring oscillator structures are important benchmark components to evaluate printed electronic circuits. For example, it is possible to estimate the minimum supply voltage at which a circuit can operate within an FET technology. With ring oscillator structures, it is also possible to measure the expected power consumption of circuits. Nevertheless, the most important performance metric that can be measured with ring oscillator structures is the frequency at which circuits can potentially operate.

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Fig. 1.6 Optical micrographs of (a) a printed FET structure consisting of source (S), drain (D) and gate (G) electrodes. The spacing to the gate from source/drain electrode is approx. 1 μm and the channel length approx. 5 μm. All electrodes are printed using a nanoparticulate silver ink. (b) Magnified image of regions of S, D and G is shown in (a). All scale bars equal 20 μm. (c) Scheme of the multiplexed PPL printing process

A typical ring oscillator consists of an odd number of inverters where the output of the last inverter is connected to the input of the first inverter. In traditional CMOS technology, an inverter is based on two FETs; a p-type FET connected between the supply voltage and the output of the inverter as well as an n-type FET joined between the output of the inverter and the source supply. The gates of the n- and p-type FETs are shortened and the input signal is applied to it. Therefore, the p-type FET is pulling up the output signal to the level of the supply voltage while the n-type FET is pulling down the output signal to the source supply. When logic ‘0’ is applied to the input, logic ‘1’ will be measured at the output and vice versa. However, the change

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of the output signal is rather delayed than instantaneous with respect to the input signal. This delay is known as the propagation delay time and measured as a time difference between the output and input signals at 50% signal swing. When the inverters are connected to a ring oscillator, the output of the ring oscillator starts to oscillate as soon as the supply voltage is applied to the ring oscillator. The frequency of the ring oscillator’s output signal is determined by the sum of the propagation delay time of each inverter stage inside the structure. For that reason, the propagation delay time can be considered as weighing time for the charging and discharging process of the FETs at each stage following the standard definition [27, 28]: τp ¼

1 2ð2α þ 1Þf

ð1:1Þ

where 2α + 1 is the number of stages, ‘α’ a constant and ‘f’ the frequency at which the ring oscillator oscillates. The switching resistance (Rsw) and the switching capacitance, (Csw) are used to model the propagation delay time through a RC network (τp ¼ RswCsw). Both, the switching resistance and the switching capacitance are calculated with the help of the switching current: I sw ¼ I dda  I ddq

ð1:2Þ

where Idda is the active current flowing through the ring oscillator while it is oscillating and Iddq is the quiescence current when the ring oscillator is not oscillating. The switching capacitance is therefore calculated as: C sw ¼

I sw τ V dd p

ð1:3Þ

where Vdd is the supply voltage. For calculating the switching resistance, the following formula can be used: Rsw ¼

V dd 2I sw

ð1:4Þ

The switching current can also be used to estimate the active power consumption of the ring oscillator: Pdyn ¼ I sw V dd

ð1:5Þ

while the static power dissipation is valued with the quiescence current: Pstat ¼ I ddq V dd

ð1:6Þ

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Fig. 1.7 Layout of a threestage ring oscillator [29]. The input signal Venable turns on and off the oscillation. Vdd and Vddi are the supply voltages of the ring oscillator and output buffer in form of another inverter, respectively. Vssi is the source supply of the inverter

The total power consumption is the sum of the static power dissipation and the active power consumption: Ptot ¼ Pstat þ Pdyn

ð1:7Þ

EGFETs based on In2 O3 channels enable the possibility of high performance and low voltage applications in the field of printed electronics. Because of the superior performance compared to other printed devices and the availability of predictive models, which simplifies the circuit design, EGFETs with indium oxide are chosen for designing applications [29, 30]. For that reason, the above described transistor technology will be further characterized with ring oscillator structures to estimate the achievable performance. Figure 1.7 shows the layout of a three-stage ring oscillator with resistors in the pull-up network and EGFETs in the pull-down network. Since the available p-type oxide EGFETs do not drive sufficient current in ring oscillator circuits, the p-type FETs as described for the traditional CMOS technology has been replaced by resistors here. Furthermore, the first stage of the ring oscillator is a NAND-gate instead of an inverter stage. The NAND-gate is used to turn ‘on’ and ‘off’ the oscillation of the ring oscillator to measure the active and quiescence currents. If the enable signal Venable is set to ‘logic 1’ the output signal Vout oscillates, otherwise it is constant. Also an inverter is connected to the output of the ring oscillator to avoid inducing noise from the environment during the measurement [31]. All active materials of the EGFET (channel, electrolyte and PEDOT:PSS(top gate)) are inkjet-printed. The passive structures of the EGFET as well as the resistor are based on indium tin oxide (ITO) and structured with lithography [29, 31]. The resistance value is set to 60 kΩ, the channel length and the channel width of all EGFETs is 40 μm and 400 μm respectively. The above-mentioned methodology to characterize CMOS-based ring oscillators has been adapted to printed electronics [31]. Figure 1.8a shows that the ring oscillator can operate in the kHz range. The minimum supply voltage at which the ring oscillator operates is 1.4 V (Fig. 1.8b). However, for a different channel geometry of the EGFETs (W/L ¼ 600 μm/40 μm), a minimum supply voltage of

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Fig. 1.8 (a) Output signal Vout of the ring oscillator recorded over time at a supply voltage of 1.4 V showing a frequency of approximately 1 kHz. (b) Dependency of the oscillation frequency from the supply voltage Vdd. (c) Switching capacitance Csw versus the supply voltage Vdd. (d) Switching resistance Rsw against the supply voltage. (e) Power consumption of the ring oscillator at supply voltages between 1.4 V and 1.9 V. (f) Current drawn by the ring oscillator at different supply voltage levels

0.6 V was reported in the past [31], which is the targeted voltage range for EGFET based applications [32–34]. Nevertheless, at different humidity or temperature conditions, other dependencies were also observed [31]. The frequency drops with increasing supply voltage (Fig. 1.8b), which is related to the fact that the current drawn by the circuit does not scale with the supply voltage (Fig. 1.8f) since it is limited by the resistors in the pull-up network. This evidence is also supported by the switching resistance which is nearly constant in the evaluated voltage range

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(Fig. 1.8d). At the same time, the switching capacitance (Fig. 1.8c) increases with the supply voltage, increasing the delay of each stage and therefore reducing the frequency of the ring oscillator. The power consumption (Ptot) of the ring oscillator raises from 200 μW to 300 μW at supply voltages of 1.4 V and 1.9 V respectively (Fig. 1.8e).

1.7

Electrochemical Energy Storage for Printed Electronics

In the above discussions, the printing methods and characteristics of various printed devices have been described and evaluated. Nevertheless, one important requirement for any operational device has not been discussed yet, namely the power supply. Since printing is a fast and inexpensive process, the targeted area of application for printed electronics makes it necessary to adjust the choice of energy storage according to the basic requirements in terms of capacity and potential, but as well to consider the handling of printed devices in the future. As two obvious examples, a possible utilization of printed devices is discussed for food labeling applications composed of simple printed sensors or printed energy harvesting devices, which are sensitive to pressure, temperature change or other external influences. While printed sensors on food packages are required to operate over a limited time, and then usually are disposed, energy storage devices for energy harvesting need to be usable for the long term and need to support a reversible charge and discharge process of the energy storage device. These different preconditions for only two areas of application for printed electronics make it obvious, that for each device, an adapted energy storage possibility has to be developed. Batteries are electrochemical energy storage devices, which enable the conversion of chemical energy to electrical energy. They are classified as primary and secondary batteries, depending on the option, either to recharge the system (secondary battery, accumulator) or to dispose the battery after use (primary battery). Therefore, the occurring redox reaction in these systems is either reversible or non-reversible [35]. Here, we focus on printable primary batteries that can be used in food labeling or other applications, offering high capacities and that are environment-friendly when disposed. Those devices do not require recharging, since the area of application (e.g., printed sensor on a food package) usually does not support a recharging process. The most convenient electrode materials used in Li-ion batteries are intercalation types. Many cathode materials, e.g., LiCoO2, Li(NiMnCo)O2 or Li(NiCoAl)O2 contain toxic heavy metals but show very high reversibility when cycled. The capacity of these materials amounts to 160–200 mAh/g, resulting from a redox process, which only transfers one electron per formula unit while dis/ charging [36, 37]. Besides the intercalation, two different other mechanisms are known, which give much higher capacities, but at the cost of reversibility. Conversion and alloying materials are able to give up to 10 times higher volumetric and gravimetric capacities, but the very low reversibility of the processes is one of the major issues

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that hinders the broad implementation of these materials in state-of-the-art batteries [38]. Although the problem of low reversibility cannot be overcome by printing procedures, it is not necessary for printed cells in single-use devices to show high reversibility, rendering these materials as ideal candidates for printed primary batteries. Another means to achieve larger specific capacities is to utilize all possible oxidation states of a compound through a conversion reaction in which more than one electron transfer occurs per transition metal. As the name implies, the conversion mechanism is based on a crystal structure conversion of the compound, while the redox active metal cation is reduced to its elemental state (as depicted in Eq. 1.8), where M is the redox active metal cation, X the anion, Y the charge of the metal cation and Z the charge of the anion. M yþ X z þ y Li ! M þ y z

y Li X z z

ð1:8Þ

This formula indicates that the number of transferred electrons per formula unit is increased, which directly results in an improved theoretical capacity. Two compounds studied for conversion reactions are FeF3 (713 mAh/g) [39] and Fe2O3 (1005 mAh/g) [40], which are non-toxic compounds and when paired with a lithiated anode like spinel LTO (Li4Ti5O12) [41], they represent an electrode material couple, which is non-carcinogenic (in contrast to LiCoO2) and non-toxic both being prerequisites for disposable items [42]. Figure 1.9 gives an example of the structure reformation during the conversion process for the FeF3 system. The low reversibility of this reaction could be assigned to the complex steps occurring during the conversion. In the first phase, the ions involved in the redox process have to diffuse through the host structure of FeF3, further in the second phase, the reacting atoms have to form new crystallites which will grow with ongoing reduction. All these reactions are diffusion-controlled and result in very small particle sizes due to the attempt of the system to reduce the diffusion pathways.

Fig. 1.9 Crystal structure of rutile FeF3 discharge and charge reaction pathways. Here, Li, Fe, and F atoms are represented by green, yellow and grey spheres, respectively [43]

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Another difference to common Li-ion batteries and beneficial for printed electrolyte-gated systems, e.g., ring oscillators, is the reduced operating voltage when some of those conversion systems are used. Due to the utilization of electrolytes as gating material for field effect transistors, an operating voltage of less than 2 V is needed to initiate the oscillation of the ring oscillator [31]. Higher potentials, as they occur in standard Li-Ion batteries (>3 V), would lead to a decomposition of the electrolyte and therefore are not suitable for a direct power supply of the device. Therefore, redox couples can be used for printed electronics, which otherwise would be insufficient regarding potential or reversibility. Similar to the conversion materials, alloying materials offer the possibility to achieve very high capacities at the expense of reversibility. In this case, instead of a conversion reaction, an alloying reaction takes place forming different Si/Li alloys (e.g. Li15Si4 or Li21Si5): Si þ xLiþ þ xe ! Li15 Si4 þ yLiþ þ ye ! Li21 Si5

ð1:9Þ

Silicon anodes are well known in literature, since they offer theoretical capacities around 4000 mAh/g, which is around 10 times higher than the commonly used graphite (372 mAh/g). However, the drastic volume change during the cycling process limits the usage of Si-based anode materials [44, 45]. Unfortunately, a huge capacity drop after the first cycle and a change in the discharge potential makes Si a difficult material to use for electrode purposes [46]. Since for primary batteries, only the first cycle is of importance, the advantages of the Si/Li systems can be used without addressing the disadvantages that appear during long-term cycling. Here, we explain the procedure used to fabricate Si anode battery cells with a microplotter system. A conventional battery consists of two conducting electrodes separated by an electrolyte. The ionic contact between the two electrodes is provided via an electrolyte and in turn provides the exchange medium for redox reactions within the cell. Fabrication of a printed battery starts with the preparation of passive structures. Printing can be performed on various substrates like glass, paper, ceramics or plastics. Pre-heating of substrates increases the adhesion of ink to the substrate. The ink is determined based on the complex composition of nanoparticles, solvent, binders, additives, etc. These chemicals were selected for the printing process depending on viscosity, surface tension and particle sizes. Water-based Si nanoparticle inks were prepared according to the recipe described in ref. [47]. After printing with a microplotter system , the thin films were dried overnight in a vacuum furnace at 80
C. The printed films were cut into 12 mm diameter circular disks for cell fabrication. A flow chart for the coin cell preparation is illustrated in Fig. 1.10. In order to evaluate the electrochemical performance of the microplotted Si anode samples, glass fiber separator, electrolyte and lithium counter electrode were assembled in a glove box. 1 M LiPF6 in a 1:1 (v/v) mixture of fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) was used as electrolyte in the cell. Furthermore, galvanostatic measurements were performed on a Si electrode/Li metal half cell (coin type) between 10 mV to 3 V with a specific current density

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Fig. 1.10 Flow chart of the coin cell battery preparation

Fig. 1.11 Galvanostatic lithiation profiles of a printed Si electrode for the first and second cycle. The second cycle shows a significantly higher average discharge potential, which directly results in a lower potential of a full cell

of 200 mA/g. The first results of the electrochemical characterization of the Si electrodes with water-based PVA binder are shown in Fig. 1.11.

1.8

Inkjet Printing of Dielectric Ceramic/Polymer Composite Thick Films

One of the main challenges in inkjet printing is to get homogenous topographies after drying of the inks, which is more complicated when inks with solid particles are used. The most common and undesired drying effect is the coffee stain effect [49, 50]. To prevent such drying effects, printing parameters as well as rheological properties of the ink need to be tightly controlled, especially when printing multilayer devices. For particulate inks, like ceramic inks, it is additionally important to adjust particle size and ink stability.

1 Printing Technologies for Integration of Electronic Devices and Sensors

a Powder synthesis

b Powder processing

19

c Ink development Weber number We

Ohnesorge number Oh

Ink

Rey nolds number Re

f Testing

e MIM-Capacitors

d Printing

1 cm

Fig. 1.12 Overview of the single process steps for the fabrication of fully inkjet-printed MIM-capacitors with dielectric ceramic/polymer composite thick films

Here, we discuss the fabrication of a MIM-capacitor (metal-insulator-metal) using a ceramic/polymer composite ink by means of inkjet printing. The capacitor architecture is a parallel plate capacitor with a dielectric layer consisting of a composite material with BST (Ba0.6Sr0.4TiO3) and PMMA (polymethylmethacrylate) to reach a high permittivity as well as very homogenous topographies. The metal layers are printed with commercially available nano-silver inks on flexible PET (polyethylene terephthalate) as substrate, which allows only a low sintering temperature (< 150
C) after printing. Nonetheless it is possible to get high conductivity of the Ag-electrodes as well as high permittivity of the dielectric layer. Every single process step for the fabrication of the capacitors is shown in Fig. 1.12. The BST particles are synthesized in a sol-gel process with acetic acid (Fig. 1.12a), the resulting sol is spray-dried and the received precursor is subsequently calcined at 1100
C for 2 h. The last process step for getting the ceramic dispersion is the milling of BST in a stirred media mill in butyldiglycol (Fig. 1.12b), to obtain a nanoparticle dispersion with a particle size distribution of 40–120 nm. The ceramic/polymer ink is directly made by mixing a ceramic dispersion with a polymer solution. The ceramic dispersion contains 10 vol% BST dispersed in butyldiglycol, using an alkyl phosphate as a dispersant. The polymer solution with 20 vol% PMMA in butanone needs no further processing, as PMMA shows very good solubility. By mixing of the resulting ceramic dispersion and polymer solution, inks with different volume ratios of BST/PMMA can be prepared. Best results are obtained for a volume ratio of BST/PMMA 1:1 and an overall solid volume fraction

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Fig. 1.13 (a) SEM image of a printed and dried drop produced by inkjet printing of 256 droplets with a BST/PMMA (1:1) ink. (b) Profile of the printed BST/PMMA composite structure. (c) Results from varying the drop distance during printing to get different layer thickness and thus different capacities. The permittivities of the BST/PMMA composite films are independent of the printing parameters (measured at 10 kHz) [51]

of 13%. For this formulation, the Ohnesorge number [52] is calculated using the Eq. (1.10) to verify a stable drop formation, η Oh ¼ pffiffiffiffiffiffiffiffi σρa

ð1:10Þ

where η, ρ and σ are the viscosity, density and surface tension of the suspension and a the nozzle diameter. The calculated Oh value is about 0.14 (Fig. 1.12c). Good printability of the ink is given for values between 0.1 < Oh < 1. The major benefit of the described ceramic/polymer ink system is the formation of a physical network between the particles and the polymer chains, which results in very homogenous topographies without coffee stain effect. An SEM image showing the homogeneity of the printed structure in Fig. 1.13a. Figure 1.13b exhibits a profile of a printed and dried drop with a slightly round profile, which only appears by enlarging. The used inkjet printer contains a drop-on-demand system with a printing resolution of >50 μm (Fig. 1.12d). The heated printing head has a diameter of 100 μm and prints on any substrate, which is placed on a heated plate. The first step for printing a MIM-capacitor is the printing of the bottom electrode, which is performed using a nano-silver ink and a drop distance of 135 μm to obtain a layer thickness of about 300 to 800 nm. Subsequently, the dielectric layer is printed, using the BST/PMMA (1:1) ink with various drop distances, to obtain layer thickness between 5.5 μm and 12 μm. In a final step the top electrode is printed, using another nano-silver ink. To get an acceptable conductivity with this ink, it is necessary to print two layers with a drop distance of 100 μm. The resulting top electrode has a

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layer thickness of 5 to 6 μm. After completion of the printing process, the capacitors are sintered at 120
C for 1 h. The completed capacitors have an effective area of 2  2 mm2 (Fig. 1.12e), with the layer thickness as mentioned in the previous paragraph. The bottom electrode shows a resistivity of 13–14 μΩcm and the top electrode 85–90 μΩcm. The permittivity of the dielectric layer (BST/PMMA 1:1), identified by impedance spectroscopy at 10 kHz, is 33 to 34 and thus about 10 times higher than for pure PMMA (εPMMA ~ 3). Depending on the layer thickness, the achieved capacitances are between 116 pF and 195 pF (Fig. 1.13c). By varying the drop distance during printing, the layer thickness can easily be changed without changing the permittivity of the resulting layer [53, 54]. Additionally, the reliability of the printed features is investigated (Fig. 1.12f). Successful integration of the printed capacitors to a fully inkjet-printed circuit will be discussed in the next section.

1.9

Integration of Printed Electronic Components on Foil Substrates

In this section, system integration of hybrid printed electronic systems is outlined, comprising printing and assembly of components, inspection and reliability tests. Available materials, including nanostructured materials, enclose conducting, semiconducting, dielectric, sensing ink materials, rigid and flexible substrates, protective coating materials, organic, inorganic and polymeric substances, energy conversion and energy storage materials. The range of processing techniques covers laterallystructured and large-area printing technologies, thermal, laser and UV annealing, bonding techniques, etc. This variety is, on the one hand, a big benefit, but also constitutes an enormous challenge in the integration of the different technologies and materials. Moreover, despite new developments in both nanomaterials for realizing electronic functions such as FETs [6, 10, 11, 27, 31] and high-resolution printing processes, e.g., dip-pen nanolithography [19, 21, 23], functional printing is still not up to par with silicon microelectronics. Hence, the approach has to be to combine the strengths of both technologies by augmenting printed systems by specific silicon components where necessary. This applies, e.g., to telecommunication circuits or microcontrollers, where silicon microelectronics still provide superior performance and larger integration density compared to printing approaches. One aim of our research is the development of smart flexible multi-substrate hybrid printed systems. For this reason, two integration strategies for printed systems on foil substrates are investigated (Fig. 1.14): • Intra-layer integration comprises integration of electronic devices on a foil substrate either directly by printing of functional materials onto the foil or by hybrid mounting of silicon electronic devices.

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Fig. 1.14 Schematic representation of intra- and inter-layer integration

Fig. 1.15 Assignment of specific functions to individual foil layers

• Inter-layer integration encompasses stacking printed foil substrates and creation of connections (e.g. electrical, mechanical, optical) between foil layers. This approach allows dedication of individual foil layers to different functions such as sensing, energy storage and communication. Each foil layer can be designed, fabricated and optimized with materials and technologies best suited for its purpose and ultimately connected to the other foil layers via well-defined interfaces. Figure 1.15 illustrates the assignment of different functions to individual foil layers: • Layer 1: Energy conversion and energy storage • Layer 2: Control electronics and data transmission • Layer 3: Sensors

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Additional components, such as light-emitting diodes, can also be integrated by means of printing techniques depending on the application. Such a modular architecture, based on stacked printed foil substrates, has the potential to enable numerous IoT- or Industry 4.0 applications.

1.10

Intra-Layer Integration

Intra-layer integration is investigated by ink-jet printing of conductive tracks, pads and electronic devices (e.g., resistors, capacitors, transistors) with both commercial and on - site developed nanoparticle inks on polymer foil substrates. The foil substrates applied to date are 150 mm  150 mm commercially available PET sheets with either chemically modified or nanostructured top-layers for improved printability. Besides inkjet printing, automatic mounting of complementary discrete microelectronic devices (e.g., SMT components, flip-chips, bare dies) onto foil substrates with printed features by means of conductive adhesives is being developed. Moreover, optical inspection methods are applied to validate printing processes, identify defects such as gaps or pinholes and measure geometric tolerances of printed structures. Figure 1.16a shows the optical inspection of bond pads of a transistor. The green color indicates that the dimensions are in tolerance and there are no gaps or pin holes. Hence, the technology platform for intra-layer integration consists of • a vector printing station composed of a single nozzle piezo print head mounted to a Cartesian three-axis motion system, • a station for optical inspection of printed structures by means of image processing, and • a station for mounting discrete microelectronic components composed of a camera for substrate referencing, a vacuum gripper and two pressure time adhesive dispensers (Fig. 1.16b). The fabrication programs for these process stations are automatically derived from CAD data, by means of a generator tool [55].

Fig. 1.16 (a) Automatic optical inspection and tolerance analysis of printed structures by image processing and (b) station for mounting discrete electronic components onto printed substrates

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To demonstrate the system integration of a fully inkjet printed circuit, an astable multivibrator circuit is chosen as demonstrator design. The output generated by this circuit is an oscillation. Thereby, two transistors are alternately switched on and off with time constants resulting from two RC-elements that provide voltages at each transistor gate, respectively. Once the first transistor is switched on, the second capacitor is charged until the threshold voltage of the second transistor is exceeded and vice versa. The advantages of using this circuit as a demonstrator are its simplicity and the low number of components required. The functional components of the multivibrator are six resistors, two capacitors and two transistors. In a first setup, two LEDs serve as output elements, blinking alternately with a frequency of several Hertz [56]. In this first demonstrator circuit only the conductive tracks and assembly pads are realized by vector inkjet printing and all functional elements are SMT components. During layout and simulation of this hybrid setup, the comparably low conductivity of the inkjet-printed conductive tracks is taken into account. Using commercially available silver-nanoparticles inks, values of about 0.66 Ω/mm at a linewidth of 120 μm are achieved by the vector inkjet printing process. In order to allow substrate referencing for subsequent inspection and component mounting steps, fiducials are included in the layout, printed with the silver-nanoparticle ink. This first version has been used to test and demonstrate the combination of printing functional structures and assembly of SMT components on printed conductive tracks [55]. In a second step, the circuit design is modified to enable the setup of a fully inkjetprinted circuit. The output is now a piezo buzzer. Thus, the frequency is changed to several 100 Hz and the output current is considerably reduced to below 100 μA. On the basis of these amendments, the circuit can be set up using inkjet-printed capacitors as described in earlier publications on printed MIM capacitors [54] and in-plane FETs [6, 10, 11]. The RC-elements utilize resistors of 910 kΩ, printed with a commercially available carbon ink reaching about 45 kΩ/mm at 120 μm linewidth, and capacitors with a capacitance of about 1.2 nF. The plate capacitors consist of silver electrodes and BST dielectrics [54] and have a functional size of 4  4 mm2. The room temperature printed in-plane FETs used for the demonstrator circuit design have a threshold voltage of 0.35 V, a device mobility of 12.5 cm2/Vs and a saturation current of 67 μA at a source-drain voltage of 1 V [11]. Due to the significantly higher device mobility and saturation current, the high temperature FETs [6] can also be used in the above circuit design. The information resulting from the characterization of test structures of all printed components and tracks is used to design the circuit. For a first functional validation of the design, simulations are performed in LTSpice using a first level NMOS model to describe the printed transistor. The comparatively low conductivity of the conductive paths and the capacitances at the respective frequency are taken into account by adding appropriate parasitic resistances to the LTSpice model [56]. This circuit has been fabricated by intra-layer integration using vector inkjet printing and hybrid mounting as outlined in the flow chart in Fig. 1.17. However, while in the first version outlined above only the conductive paths are printed, the

1 Printing Technologies for Integration of Electronic Devices and Sensors

25

Fig. 1.17 Flow chart for intra-layer integration of the fully printed demonstrator circuit

second version of the demonstration circuit has been fully printed, albeit on two different substrates. The conductive tracks, cross-connects, the resistors and the capacitors are printed on flexible polymer substrates (PET), while the transistors, requiring higher processing temperatures, are printed on glass substrates and were subsequently mounted onto the polymer substrate and connected by thin wires and conductive adhesives. Due to the complexity of the process chain, comprising four printing processes with three different inks, the respective post-processing steps and the final mounting step for the FETs printed on glass, the process yield of each process step multiplies unfavorably over the entire process chain [57]. Hence, measures have been taken to optimize the output both at the design and the process levels. On the design level, the modular circuit layout allows for different extension levels so that circuit testing can be done step-by-step.

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Fig. 1.18 (a) Modular circuit layout allowing step-by-step testing and (b) an experimental intralayer integrated multi-vibrator circuit on plastic foil

(Fig. 1.18a). Firstly, printed capacitors and transistors known to function well are installed first individually and then together on a PCB test board to verify functionality. Secondly, all passive components including conductive paths, resistors and capacitors are printed on a PET substrate. In place of the printed FETs, Infineon tetrodes BF2040 are mounted that emulate the printed FETs as far as possible. The crosslink dimensions in the layout are designed in such a way that they enable both assembly of SMT zero Ohm resistors as crosslinks, or, alternately, crosslink printing using three layers: conductive path, insulation, and conductive path. After every printing step, an optical inspection has been introduced to identify defective features such as gaps in conductive paths and resistors or pinholes in capacitor plates. Hence, after every step only the working circuits are further processed. After completion of intra-layer integration by the various printing processes, the final step is to integrate working transistors inkjet-printed on a glass substrate into the circuit printed on PET (Fig. 1.18b). The final aim is a circuit that is completely inkjet-printed on a single substrate.

1.11

Mechanical and Electrical Integrity of Flexible Electronics

If the benefits of electronics on flexible substrates, such as conformity to curved surfaces shall be exploited in applications, reliability of the printed features and the mounted microelectronic components under the resulting strain becomes an issue. This issue can be subdivided into • reliability of devices realized by printing techniques and • reliability of hybrid integrated microelectronic devices on foil substrates.

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Integrated sensors and electronic devices always have to face high stress and strain as they unite very different materials with very different mechanical properties. Residual stress and mechanical loading occur during the manufacturing as well as throughout the lifetime of the device. For devices on hard substrates, thermal straining is probably the most important source of mechanical loading. For devices on compliant/flexible substrates, external load leads to large strain due to a low Young’s modulus of the substrate and provides an additional kind of load, which has to be controlled. Perfect adhesion and interfaces between individual layers and structures are necessary for the functionality and integrity of the devices but lead to direct strain transfer from the substrate to the functional layer. Direct strain transfer leads to large stress in the stiff functional layers which may lead to fragmentation or delamination of the layer. Dense ceramic layers are very brittle and suddenly show crack formation. Dense metallic layers can deform plastically but are very sensitive to strain localization or stress concentrations at interfaces. It has been shown that Cu films with perfect adhesion can be stretched beyond 50% as the perfect bonding to the substrate prevents the film from strain localization. However, if the Cu film locally detaches from the substrate, the strain is localized in the detached area, leading to necking and early fracture of the film [58]. A similar scenario is given when the metallic film is embedded within brittle interlayers, where the fragmentation of the brittle layers leads to local stress concentrations and necking sites [59, 60]. Printed layers are inherently nanoporous and show different behavior as compared to dense and homogeneous films. Printed nanoparticulate Ag films show a strong effect of sintering parameters on the mechanical and electrical performance. For monotonic tensile tests, it is generally observed that printed Ag films have lower fracture strain compared to evaporated films, since the nanopores act as stress concentrators and facilitate crack nucleation [61]. With respect to fatigue resistance, the situation is not as clear. Samples which have been annealed below the decomposition temperature Td of the organic constituents have superior fatigue resistance but a higher initial electrical resistivity due to the missing formation of strong sinter necks between the particles. Annealing above Td yields lower initial resistivity due to the formation of a string nanoparticulate network but the fatigue lifetime is deteriorated due to the early formation of extrusions and cracks. Consequently, the best compromise is obtained by annealing close to Td [62]. Good electrical conductivity is obtained due to the sintering of the particle network, whereas an enhanced fatigue resistance results from constrained dislocation plasticity due to the small particle size and annihilation of dislocations at free surfaces. A specific optimization of the nanoporous microstructure of printed films can help to develop highly conductive and reliable flexible metallic electrodes. A very similar scenario is obtained when we have a look at the results of monotonic tensile tests on In2O3 films on polyimide substrates prepared by the precursor and nanoparticulate route as described in high and low temperature FET devices [6, 11]. The precursor route, due to the higher sintering temperature, yields very dense and homogeneous films. Due to the good adhesion to the polyimide substrate, the tensile strain is directly transferred to the dense and brittle In2O3 film

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Fig. 1.19 Snapshots at different total strain during tensile tests of In2O3 layers prepared by (a) precursor route and (b) nanoparticulate route. (c) Cross-section of a fully-printed BST/PMMAcapacitor with top Ag electrode

which suddenly reaches its fracture strain and shows crack formation at around 2–3% tensile strain (see Fig. 1.19a). In contrast, the In2O3 film prepared by the nanoparticulate route shows a nanoporous microstructure. Here, although the film is also strongly bound to the substrate, the strain imposed by the substrate is not directly transferred into the In2O3 material, but to a nanoparticulate network with some structural flexibility. Thus, the strain is distributed in the nanoparticulate network and less strain is introduced in the In2O3 material. This way, the fracture strain of the In2O3 material is reached for higher total strain and no cracks are observed up to more than 8% total strain (see Fig. 1.19b). In. The optimization of the nanoporous microstructure gives some potential to increase the strainability of printed inorganic materials; however, it is still limited by the inherent brittleness of the materials. A further strategy to account for individual brittle functional layers is to cross the loading and working direction of the functional layer. An example for such a vertical design is shown in Fig. 1.19c. Here, the top of a cross-section of a fully printed BST/PMMA capacitor with Ag top and bottom electrode on a PET substrate is presented for different total tensile strain. It is obvious that cracks form first in the brittle BST/PMMA layer at around 2–4% tensile strain and then grow vertically towards the top and bottom electrode. As the direction of polarization is parallel to the cracks in the BST/PMMA layer the capacitance of the capacitor is not affected at this stage. Only if the cracks penetrate into the top or bottom electrode of the capacitor at around 8%, the capacitance starts to deteriorate as the active area of the capacitor and the charge transfer within the electrodes are affected. Thereby, the failure of the device is not governed by the

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failure of the brittle part but is retarded to the failure of the more ductile part of the device. Using this scheme, failure in brittle layers cannot be avoided but the operation window of the device can be extended above the corresponding failure strain.

1.12

Reliability of Hybrid Integrated Microelectronic Devices on Foil Substrates

Reliability of discrete microelectronic components mounted on rigid substrates is a well investigated field [63]. Established mounting technologies such as soldering or conductive adhesive bonding are being transferred to hybrid integration of packaged microelectronic components or bare dies onto printed foils substrates [64]. For reliable hybrid integration of discrete components an important prerequisite is, however, that the above outlined reliability of the base wiring, the printed conductive paths and pads, is ensured. As printed pads are the interface to the mounted components crack, formation and delamination in these structures due to bending have to be avoided. A means to address this failure mode is optimization of the sintering process as addressed earlier [62]. Delamination of printed features can additionally be reduced by optimizing the interface between printed structure and substrate. Investigations of this interface indicate that a nanoporous top layer may lead to improved mechanical interlocking between printed path and substrate [65]. Function separation by additional mechanical fixing of electronic components on a printed circuit board is an established technology in SMT technology to avoid shearing off mounted components due to thermal strain [63]. A similar approach can be applied for improving reliability of SMT components or bare dies mounted on a flexible substrate. Hence a non-conductive structural adhesive is additionally dispensed in the mounting process of the SMT components in the first version of the demonstrator circuit with hybrid mounted SMT components. Ag pads were ink-jet printed onto the PET substrate with the nanostructured top-layer as outlined above. SMT resistors (type 1206) were mounted onto the substrates either by means of a conductive adhesive only or blended to improve mechanical fixation. Shear tests were performed on a with a shear speed of 200 μm/s. Figure 1.20 top shows the results of shear testing on 12 specimens of each type. The top curves show the shear testing results of 12 components mounted with the conductive adhesive only. These results (mean max. force of 22.07 N, standard deviation of 25.59%) indicate low shear strength and poor reproducibility of the bonding process. Figure 1.20 bottom illustrates the shear testing results of the same number of components, this time mounted with both the conductive adhesive and the additional structural adhesive. The mean max. shear force has increased to 30.99 N, while the standard deviation decreased to 7.28%. These results indicate a significant increase in shear strength, thus higher reliability of the bonded SMT components on the substrate and an improved reproducibility of the adhesive bonding process.

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Fig. 1.20 Shear tests of SMT components mounted onto printed pads on a flexible substrate (top: only conductive adhesive, bottom: conductive and additional structural adhesive)

1.13

Conclusion

All printed field effect transistors have great potential for low cost, large-area flexible electronics and displays. Here, inorganic electronic materials including conductors, semiconductors and dielectric materials that may be useful for printed electronics are briefly introduced with respect to their properties, ink preparation, and film formation by solution or printing. It is evident that printing of functional structures in principle offers a lot of flexibility in the design and practical realization of the electronic systems. In order to make printing widely accessible in more applications, many more different metallic and semiconducting materials, electrolytes, dielectric materials, and corresponding technologies are needed, requiring coordinated research efforts by materials scientists, chemists, physicists, and electronic engineers. In addition, function simulation over the entire length scale is needed to predict the performance of devices and to integrate the individual components into reliable systems. While the development of the different materials and technologies still poses major challenges, it should be mentioned that no principal barriers towards the successful implementation of all printed devices exist, and that the final success is only limited by the creativity of engineers and scientists and their ideas for novel products, which can be manufactured using printing technologies. Acknowledgements The authors appreciate the financial support by the Helmholtz Association, the Deutsche Forschungsgemeinschaft, Karlsruhe Nano Micro Facility and the Virtual Institute VI-530. Some of the authors wish to thank the Ministry of Science, Research and Arts of the state of Baden-Württemberg through the MERAGEM Doctoral Program for the financial support. Some of the authors would like to thank Klaus-Martin Reichert for software and Daniel Moser for hardware support to the system integration technology platform.

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42. Zhao Y, Liu G, Liu L, Jiang Z (2009) High-performance thin-film Li4Ti5O12 electrodes fabricated by using ink-jet printing technique and their electrochemical properties. J Solid State Electrochem 13:705 43. Momma K, Izumi F (2011) VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J Appl Crystallogr 44:1272 44. Ge M, Rong J, Fang X, Zhang A, Lu Y, Zhou C (2013) Scalable preparation of porous silicon nanoparticles and their application for lithium-ion battery anodes. Nano Res 6:174 45. Ma D, Cao Z, Hu A (2014) Si-based anode materials for li-ion batteries: a mini review. NanoMicro Lett 6:347 46. Park HW, Song J–H, Choi H, Jin JS, Lim H–T (2014) Anode performance of lithium–silicon alloy prepared by mechanical alloying for use in all-solid-state lithium secondary batteries. Jpn J Appl Phys 53:08NK02 47. Breitung B, Aguiló-Aguayo N, Bechtold T, Hahn H, Janek J, Brezesinski T (2017) Embroidered copper microwire current collector for improved cycling performance of silicon anodes in Lithium-ion batteries. Sci Rep 7:3 48. Dose WM, Piernas-Muñoz MJ, Maroni VA, Trask SE, Bloom I, Johnson CS (2018) Capacity fade in high energy silicon-graphite electrodes for lithium-ion batteries. Chem Commun 54:3586 49. Deegan RD, Bakajin O, Dupont TF, Huber G, Nagel SR, Witten TA (1997) Capillary flow as the cause of ring stains from dried liquid drops. Nature 389:827 50. Derby B, Reis N (2003) Inkjet printing of highly loaded particulate suspensions. MRS Bull 28:815 51. Mikolajek M (2018) Tintenstrahldruck organisch/anorganischer Komposite. Dissertation 52. Fromm JE (1984) Numerical calculation of the fluid dynamics of drop-on-demand jets. IBM J Res Dev 28:322 53. Mikolajek M, Reinheimer T, Muth M, Hohwieler P, Hoffmann MJ, Binder JR (2018) Control of the surface morphology of ceramic/polymer composite inks for inkjet printing. Adv Eng Mater 12:1800318 54. Mikolajek M, Friederich A, Kohler C, Rosen M, Rathjen A, Krüger K, Binder JR (2015) Direct inkjet printing of dielectric ceramic/polymer composite thick films. Adv Eng Mater 17:1294 55. Gengenbach U, Ungerer M, Aytac E, Koker L, Reichert KM, Stiller P, Hagenmeyer V (2018) An integrated workflow to automatically fabricate flexible electronics by functional printing and SMT component mounting. In: Vogel-Heuser B, Lennartson B (Hrsg) (eds) 14th IEEE international conference on automation science and engineering (IEEE CASE 2018) 56. Koker L, Ungerer M, Mikolajek M, Neuper F, Kühner T, Gengenbach U (2018) Data-driven design of an inkjet-printed electronic circuit. Organic & Printed Electronics Association (OE-A) (Hrsg.). In: Proceedings of 10th international exhibition and conference for the printed electronics industry (LOPEC 2018) 57. Cunningham JA (1990) The use and evaluation of yield models in integrated circuit manufacturing. IEEE Trans Semicond Manuf 3:60 58. Lu N, Wang X, Suo Z, Vlassak J (2007) Metal films on polymer substrates stretched beyond 50%. Appl Phys Lett 91:221909 59. Gruber PA, Arzt E, Spolenak R (2009) Brittle-to-ductile transition in ultrathin Ta/Cu film systems. J Mater Res 24:1906 60. Marx VM, Toth F, Wiesinger A, Berger J, Kirchlechner C, Cordill MJ, Fischer FD, Rammerstorfer FG, Dehm G (2015) The influence of a brittle Cr interlayer on the deformation behavior of thin Cu films on flexible substrates: experiment and model. Acta Mater 89:278 61. Kim S, Won S, Sim GD, Park I, Lee SB (2013) Tensile characteristics of metal nanoparticle films on flexible polymer substrates for printed electronics applications. Nanotechnology 24:085701 62. Kim B-J, Shin H-A-S, Lee J-H, Yang T-Y, Haas T, Gruber P, Choi I-S, Kraft O, Joo Y-C (2014) Effect of film thickness on the stretchability and fatigue resistance of Cu films on polymer substrates. J Mater Res 29:2827

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Chapter 2

Development of Policy and Strategy of the Nanomaterials for Environmental Safety/Security by Radioactive/Nuclear Agents at Critical Infrastructure Facilities in Albania Luan QAFMOLLA Abstract Albania has not a Research Reactor, Nuclear Power Plant, but use radioactive/nuclear materials and sources of the Ist–Vth category according their classification. Albanian institutions, Institute of Nuclear Physics (INP) and Radiation Protection Commission (RPC) have established a system of regulations and guidance to arrange the preparedness for response on-site area for practices with radioactive/nuclear that could necessitate intervention in emergency situation (Treatment of liquid R/W contains 226Ra, 90Sr, 238Pu, 137Cs isotopes at the Radiochemistry Department. INP, Technical Report, Tirana, 1998). The safety/security of risk assessment in facilities that utilize radioactive/nuclear material was performed considering its impact in environment, workers and public. A national legal framework was established providing among others objectives based in internationally agreed principles and national developments of policies/strategy for nanomaterials for environment safety/security by radioactive/nuclear agents at critical infrastructure facilities in Albania (Vaseashta A, Dimova-Malinovska D, Marshall J Nanostructure and advanced materials. Springer, Dordrech, 2005). Since 1998, a centralized storage facility exists for waste management and it was situated within IANP territory together with radiopharmaceutical Lab. Last decade substantial progress has been made in improving safety/security of radioactive/nuclear material worldwide, as well as in Albania. Al-Qa’ida and associated extremist groups have a wide variety of potential agents and delivery means to choose from for chemical, biological, radiological, or nuclear attacks. Terrorism groups continuously expressed interest in unleashing radiological terrorism by building and using radiological dispersal devices, known as “dirty bomb”. Materials, such as: commercial radioactive sources or enriched uranium/plutonium could fuel as crude nuclear material at such device. (Counter terrorism challenges regarding the process of critical infrastructure protection, 2011) Radioactive nuclear wastes generated from nuclear L. QAFMOLLA (*) Ex- Employee of Institute of Applied Nuclear Physics (IANP), Private Consultant, Tirana, Albania © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_2

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facilities or by radiological terrorism attack should be converted in stable forms, to be stored, disposed in safety/secure manner, in order to have as low as reasonably achievable (ALARA) environmental impact. Radiochemistry Division in institute has treated Low Level Liquid Waste generated by its Labs that contain 226Ra, 238Pu, 90 Sr, 137Cs isotopes, using nanomaterial as absorber agents like: korthpule-kaolin, Al2O3x2SiO2x2H2O clay, and Tirana Factory Bricks clay, to adsorb above ions. We performed studies in Lab scale to decrease the activity/concentration of wastes, helping the precipitation of radioactive products on PO3
3, OH
ions form, adding sorption nanoagent such as: activated coal, metal powder mixed with different types of clay. Results shown, that montmorilonity Al2[(OH)2Si14O10]xnH2O is few effective as kaolin, which has ion-exchange capacity lower as the first clays used in our Lab, and its ion-exchange velocity was higher. The radioactivity of Low Level Liquid Waste was decreased in considerably using only clays, but this method request large amount of kaolin, increasing the precipitate volume. The experiments repeated using different sorption masses, temperatures, and time (min) of the clays, to absorb 226 Ra, 238Pu, 90Sr and 137Cs. The results shown different absorption coefficients for decontamination of LLLW amounts reducing in considerable manner their volume (Chemical treatment of Radioactive /Waste, IAEA, technical report series No. 89, Vienna, 1968; Chemical precipitation processes for treatment of aqueous Radioactive /Waste, IAEA, technical report series No. 337, Vienna, 1992; Handling and treatment of radioactive aqueous Radioactive /Waste, IAEA, TEC/DOC–654, Vienna, 1992). Keywords Radioactive nuclear material · Centralized store facility · Radiopharmaceutical lab · Ion-exchange material · Absorber agent etc.

2.1 2.1.1

Introduction CBRN as Conventional Threat Agents and Ammunitions Used as Assault by Terrorism Groups

In the last decade, substantial progress has been made in improving safety & security for nuclear material worldwide, both by states’ own domestic actions and through international cooperation. Al Qaeda, ISIS, KURDS and other terrorism groups, continuously expressed interest in unleashing radiological terrorism to build and using Chemical, Bacterial, Radiological and Nuclear Dispersal Devices– CBRNDs, known as “dirty bomb” [3]. Terrorists have considered a wide range of toxic chemicals for attacks. Typical plots focus on poisoning foods or spreading the agent on surfaces to poison via skin contact, but some also include broader dissemination techniques. Sodium or potassium cyanides are white-to-pale yellow salts that can be easily used to poison food or drinks. Cyanide salts can be disseminated as a contact poison when mixed with chemicals that enhance skin penetration. Hydrogen cyanide (HCN) and cyanogens

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chloride (ClCN) are colorless-to-pale yellow liquids that will turn into a gas near room temperature. Both chemical agents need to be released at a high concentration only practical in an enclosed area to be effective, therefore, leaving the area or ventilating will significantly reduce the agent’s lethality. At high doses, cyanides cause immediate collapse aside from nausea, vomiting, palpitations, confusion, etc. Mustard is a blister agent that poses a contact and vapor hazard, its color ranges from clear to dark brown depending on purity, and it is a viscous liquid at room temperature. Initial skin contact with mustard causes mild skin irritation, while inhalation of mustard damages the lungs, causes difficulty breathing, and death by suffocation in severe cases due to water in the lungs. Sarin, tabun, and VX are nerve highly toxic military agents that disrupt a victim’s nervous system by blocking the transmission of nerve signals. Exposure to nerve agents causes pinpoint pupils, salivation, and convulsions that can lead to death. Also, some other toxic industrial chemicals agents like: chlorine, phosgene or organophosphate that while not as toxic as cyanide, mustard, or nerve agents, can be used in much larger quantities to compensate for their lower toxicity. Some eventual attacks happened abroad by small terrorism groups in metro, bus station etc., using the biological agents like: anthrax, which is a bacterium that causes symptoms appears within 1–6 days after exposure and include fever, malaise, fatigue, and shortness of breath. Botulinum toxin is produced by the bacterium Clostridium botulinum, which occurs naturally in the soil. Crude but viable methods to produce small quantities of this lethal toxin have been found in terrorist training manuals. The main symptoms usually occur 24–36 h after exposure, but onset of illness may take several days if the toxin is present in low doses. They include vomiting, abdominal pain, muscular weakness, and visual disturbance. Racine is a plant toxin that is 30 times more potent than the nerve agent VX by weight and is readily obtainable by extraction from common castor beans and victims start to show symptoms within hours to days after exposure, depending on the dosage and route of administration. Radiological and Nuclear Devices is a conventional bomb not a yield producing nuclear device, which are designed to disperse radioactive/nuclear material to cause destruction, contamination, and injury from the radiation produced by the material. Use of an RND by terrorists could result in health, environmental, and economic effects as well as political and social effects. It will cause fear, injury, and possibly lead to levels of contamination requiring costly and time consuming cleanup efforts. A variety of radioactive materials are commonly available and could be used in such “dirty bomb” including 137Cs, 90Sr and 60Co. Hospitals, universities, factories, construction companies, and laboratories are possible sources for these radioactive materials. As well, an Improvised Nuclear Device is intended to cause a yield producing nuclear explosion. This ammunition could consist of diverted nuclear weapon components, a modified nuclear weapon, or indigenous designed device. Such devices are categorized into two types: implosion and gun assembled. INDs require fissile material for instance: highly enriched uranium or plutonium to produce nuclear yield, while RDDs filled with radioactive material of 137Cs, 90Sr and 60Co. The purpose of the weapon is to contaminate the area around the dispersal agent/ conventional explosion with CBRN material, serving primarily as an area denial

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device against civilians. So far worldwide, several incidents with terrorism potential in critical infrastructure involved radioactive and nuclear materials or wastes in their repository facilities have been a target by terrorism attacks. A conventional attack on a radioactive/nuclear facility in an attempt to release large amounts of radiation, creating psychological terror is far more conceivable, and protections against this should be explored further. Suicide terrorists might also try to break into a Nuclear Power Plant and quickly build and detonate “dirty bomb”, a conventional explosive laced with radioactive material. Potential attackers may also use conventional explosives to blow up some nuclear waste, thereby spewing radioactive materials into nearby areas. Finally, experts warn that terrorists might target the pools in which nuclear reactors’ highly radioactive waste (“spent fuel”) is kept. For that reason needed to be established of a layered and integrated safety and security system to defense the critical infrastructure elements by CBRN agents. A layered safety and security system means that multiple barriers are in place to lessen the likelihood of a CBRN terror act. Added layers would frustrate terrorists’ attempts to break through the security system, and an integrated safety/security system means that adequate layers of safety and security protect every stage of a high-risk radioactive source’s lifecycle from cradle to grave. The NPP-s is built to withstand hurricanes, tornadoes, earthquakes, small plane crashes and bombing attacks. The NPP-s is designed to withstand extreme events and is among the sturdiest and most impenetrable structures on the planet.

2.2

Defense of Critical Infrastructure Elements a Target by Assault of Terrorism Groups

Critical infrastructure at the countries abroad includes those assets and services, which are essential for the country, and the disruption or destruction of which, would have a significant impact on the national security, economy, vital societal functions, health, security and protection as well as social well-being. Energy systems are of critical importance for the functioning of contemporary societies and particularly the economic system. In countries abroad, some of the most important branches of economy branches are, namely, energy supply infrastructure that generates electricity by Hydro Power Station (HPS), Thermo Power Station (TPS) or Nuclear Power Plant (NPP) etc., as well as information and communication technology. They are inseparably connected and have an interdependent impact on the functioning of all other critical infrastructure sectors. At the same time, however, due to their importance, they are simultaneously a very attractive target for various threats, due to the natural forces, technical failures and human errors. The term “infrastructure” basically focuses on the organization, or system. It refers to the area of information and telecommunication, banking and finance institution, supply water, oil and gas, transport and logistics, as well as health care, first aid system etc. The energy sector structure or the energy sector critical infrastructure is composed of following sectors:

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nuclear, hydroelectric, oil, gas and thermoelectric sector [3]. All above mentioned facilities and sectors could be potential targets for attacks by terrorist organization worldwide. To assess the risk from terrorists the capability of the evaluation of the nuclear power plants vulnerability to different kinds of threats by terrorist attack, the preparation of emergency responses are of vital importance for the safe operation of critical nuclear infrastructure and the maintenance of national security. Nuclear security for Research Reactors, Nuclear Power Plants and Associated Facilities means to simplify the process and enhance the effectiveness of nuclear security programmers’ to reduce the risk of theft of nuclear and/or other radioactive materials and sabotage by terrorists, natural disasters and human errors. Perfect safety and security system do not exist, but a security organization and plant physical protection systems should be in place to prevent unauthorized access of personnel, vehicles, and materials; ensure only authorized activities are conducted; permit only authorized handling of nuclear material; and detect and respond to unauthorized penetrations. All nuclear/radiological facilities are required to defend against a “design basis threat,” defined as determined violent external assault, attack by stealth, or deceptive actions of several terrorist groups. The entire nuclear/radioactive facility perimeter should be fenced with adjacent areas cleared to permit observation of both sides of the fenced barrier. The perimeter should be monitored both visually and electronically, by electronic alarms sensors. Entry points should be guarded and monitored; access to these facilities strictly needs to be controlled. All nuclear/radioactive facilities should have emergency plan response that contains all necessary mechanism, and to have in function nanostructures elements for CBRN defense of environmental safety and security. Outside and inside of the radioactive/nuclear facility, security cameras or other electronic provided with elements means or sensors should monitor all personnel. Access to sensitive site, for example into the “Reactor Core” area, where the fuel assembly is, should be controlled by electronically keyed or coded security doors that are monitored continuously from security computers by an unauthorized access. Security Technologies (ST) and system should be evaluated in terms of current and long-term impacts it has a very important role in creating more safety/secure facilities and precious investment in this infrastructure is a great challenge for safety/security improvements will reduce the risk of CBRN attack by terrorist groups.

2.3

Applications of Nanotechnology by Regional Projects for New Science Developments in Albania

Actually nanotechnology is one of the fastest growing areas in science and engineering. The subject arises from the convergence of electronics, physics, chemistry, biology and materials science to create new functional systems of nanoscale dimensions. Nanotechnology involves the precise manipulation and control of atoms and molecules to create novel structures with unique properties. Nanoscience and

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nanotechnology are cross-interdisciplinary areas involving materials and functional systems whose structures and components, due to their nanoscale size, exhibit unusual and/or enhanced properties. Development of new materials, especially for health care products and advanced products (electronics, solar energy systems, biotechnology) are the main objectives of R&D activities in the near future. The goal is to produce new materials, devices and systems tailored to meet the needs of a growing range of commercial, scientific, and engineering applications – opening new markets and giving dramatic benefits in product performance. The important issues are the processing and the manipulation of complex architectures on the nanoscale, as well as the fabrication of devices with new sustainable methodologies. The scientific community tries to approach the nanoscale by exploring at surfaces the structures of materials, probing their chemical and physical properties on the molecular scale, and comparing the properties of a single molecule with those of an ensemble of molecules. Our institute was involved in international and regional projects related with this topic. To coordinate and cooperate in the field of materials science the International Atomic Energy Agency (IAEA) by a Regional Project RER/8/104, has promoted among its member states participating through of such activities: (1) the use of electron accelerators and gamma sources for nanomaterial synthesis and processing; (2) the establishment of a network of analytical laboratories applying nuclear techniques for nanoproducts characterization; (3) the design and development of nanostructure-based products for health care, environmental and industrial applications. This regional project belonged to Radiation Processing Facilities and Applications, Radiation Chemistry and Analytical, Radio-analytical and Instrumental Techniques, in study of nanomaterials, surface phenomena, ceramics and polymers, which will be applied for examples in following fields: material modifications, physical and chemical mutagenesis, sterilisation, Mössbauer spectroscopy 57Co, Raman spectroscopy, X ray fluorescence and atomic absorption spectroscopy.

2.4

New Developments to Deactivate the Liquid RAD/NUC Agents Realized by Experiments in Lab Scale

In this part of paper was illustrated a nexus of technological innovations in experimental Lab scale to monitor pollution and decontamination of liquid Radioactive Nuclear agents generated by radioactive/nuclear Labs, as well as from radiological and nuclear devices organized by terrorist groups attack. Low Level Liquid Wastes are categorized as several groups according to their concentration of nuclides and chemical / physical properties. Contaminated, Low Level Liquid Waste that contain 226 Ra, 238Pu, 90Sr, 137Cs nuclides, generated by Radiochemistry Division in INP,

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Table 2.1 The characteristics of aqueous wastes contain 226Ra isotope Facilities which have generated the liquid RW containing 226Ra Institute of Veterinary Research Institute of Soils Study Radiochemistry division (INP)

Volume (m3/ year) 1.5 0.8 2.3

Concentration Bq/cm3 1.8  10 2 1.0  10 2 2.1  10 2

are collected and transported separately into 30 litter porcelain vessels, at the waste management facility situated within INP territory. These liquid wastes are treated using the evaporation, ion-exchange, co-precipitation methods and systems, in order to reduce their concentration and volume. Above mentioned nuclides, for instance the 226Ra isotope routinely was used by Radiochemistry Division and from Division of Chemistry of the Defense Ministry. Table 2.1 gives characteristics of the aqueous wastes that contain 226Ra generated by different users for 1985–1990 periods. The 226Ra isotope has high toxicity property MLC ¼ 1  10
13 Ci / litter, half life T1/2 ¼ 1628 years, alpha decay modes and particle energies 0.54 MeV (100%). Stable chemical forms of radium exist in solution as a cationic form. The common chemical properties of Ca+2, Sr+2, Ba+2 and 226Ra ions, their sorption mechanisms that possibly can occur during the treatment processes of the LLW must be created of forming strong cationic complexes or neutral compounds of low solubility or by chemical-sorption on soil minerals containing the same metals [5, 7, 8]. For that reason we have studies the clearing degree of LLW, which contain 226Ra radioisotope, by Korthpule –Kaolin and Bricks Tirana Factory clays. The experiments repeated using different sorption masses, temperatures, and time (min) of the clays, to absorb 226Ra, 238Pu, 90Sr, 137Cs, removing in this way from aqueous solution in precipitate form [9].

2.5

Theoretical Part of the Study for Treatment of LLW that Contain 226Ra by Precipitation Method

For treatment of liquid radioactive wastes with low/intermediate activity and concentration is accepted precipitation method that includes the neutralization stage of the acid solutions for removal of parts by resistible liquids. During chemical precipitation process added the chemical reagents so-called coagulators, which decrease the radioactivity/concentration of radioactive wastes. One of more suitable coagulator was phosphate which create a flocculent precipitation and was prepared by: 500 mg/ml clay; 300 mg/ml NaOH (pH ¼ 11–11.5); 206 mg/ml Na3PO4 and 106 mg/ml Ca(OH)2.

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Table 2.2 Phosphoric treatment to remove the total activity by liquid radioactive wastes No. of treatment One time One time Two time One time

Chemical form 100 mg/ ml Glina & Na3PO4 Glina & Na3PO4 Ca(OH)2&Na3PO Glina & Na3PO4

Table 2.3 The influence of the pH value to remove the 226 Ra ions

2.5.1

pH Values 6.0 6.5 7.0 8.0 10.0

Initial activity imp/min 4880 2150 2750 12,935

Final activity Imp/min 31 27 18 12

Results % 99.4 98.7 99.2 99.6

Concentration (Ci/litter) 10.6 8.9 1.8 1.2 0.15

Phosphoric Treatment

The results are shown in Table 2.2, using phosphoric precipitation procedure, in order to decrease the activity/concentration of LLW, using different kind and mixed clays. The results shown the activity was 98% - 99.6%. This method was used to treat LLLW and final activity at radioactive solution determines the existence of Ra, Cs, Sr and Pu ions. Table 2.3 shows the pH value for removed of 226Ra ions by precipitation method.

2.5.2

Metal Powder and Clay Mixed for Treatment of Low Level Liquid Waste

We carried out studies to decrease the activity/concentration of liquid radioactive wastes helping of precipitation of radioactive products in the form of PO3
3, or OH
ions, adding sorption agent as nanomaterial, such as: activated coal, metal powder mixed with different type clays. Montmorilonity, Al2[(OH)2Si14O10]. nH2O, is few effective as kaolin, which has ion-exchange capacity lower as the first clays used in our Lab. Its ion-exchange velocity is higher. The radioactivity of LLLW was decreased in considerably using only clays, but this method request large amount of kaolin, increasing the precipitate volume. The best results were taken using filled glass column with clay, increasing in this way surface of contact between clays and LLW, and time by time the column was treated by 3–5% HCl for leaching (Table 2.4).

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Table 2.4 Determination of the optimum temperature for adsorption of 226Ra by both clays Temp. 0 C 0 100 200 300 400 500

0 imp / min 763 763 763 763 763 763

Hours adsorption coefficient % 0 0 0 0 0 0

20 imp / min 138 / 384 118 / 252 112 / 216 76/ 354 80/ 368 124/ 390

Hours adsorption coefficient % 81.9 / 49,5 83.5 / 66,9 85.3 / 71,6 90 / 53,6 89.5 / 51,7 83.7 / 48,8

Table 2.5 Determination of the optimum mass for adsorption of 226Ra by both clays Mass gram 1 4 8 12 16

0 min imp/min 421/144 749/1230 1561/586 964/482 1147/1117

30 min imp/min 383/131 417/623 1031/426 769/332 1014/1009

60 min imp/min 334/105 257/203 523/218 644/200 901/857

90 min imp/min 318/79 241/114 473/126 614/135 887/824

120 min imp/min 298/70 220/88 435/115 574/128 834/726

150 min imp/min 265/59 218/80 417/84 574/101 739/687

900 min imp/min 240/33 121/56 322/50 400/70 504/430

Note: Numbers blue color in columns correspond to Tirana Bricks Factory, and also, we have study the optimum pH value to remove 226Ra, 238Pu, 90Sr, 137Cs isotope, but these values aren’t presented. We will continue to work to determine the exact parameters for this purpose and to stabilize the methodic

2.5.3

Ion – Exchange Method

The ion-exchange method was successfully used to clean LLW with concentration 10
4 Ci / litter, which method gives a high productivity for nuclides in solid materials. The mechanism of ion exchange is a reversible process, which exchange ions, between liquid and solid phases, without exchanges of radical groups, and be located in solid structure phase. Solid phase may contain ions that are able to exchange its ions with ions of liquid phase. Ion-exchange resin presents itself a great molecule indissoluble on the acid or basic solutions. When the resin is in cationic form on its composition, then the molecule will be with acid groups or cations, which contain acid groups. The cations could substitute H+ or K+ cations, which present radioactive isotope on the liquid phase, and could be in a simple or compound form at those salt groups, establishing the indissoluble salts. The reaction of cationic ion exchange can present by following forms: Csþ þ H½K ¼ Cs½K þ Hþ orRa2þ þ 2H½K ¼ Ra½K2 þ 2Hþ The isotopes of cesium and radium, which are in micro quantities at LLW, were adsorbed grossly by anion ions at solution, helping so ion-exchange reaction, between liquid and solid form [6, 7] (Table 2.5).

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Table 2.6 Determination of the optimum time (min) for adsorption of 226Ra by both clays Clay type KorthpuleKaolin Tirana Bricks Factory

2.6

0 min imp/min 691

15 min imp/min 681

30 min imp/min 617

45 min imp/min 573

60 min imp/min 561

75 min imp/min 522

90 min imp/min 489

295

220

217

204

197

189

145

Experimental Part, of Low Level Waste Treatment, Contain 226Ra by Precipitation Process

Low Level Liquid Waste containing isotopes of 226Ra were treated using the decontamination method by clays studied the cleaning degree for deactivation of the radioactive wastes generated by INP and other nuclear facilities. We used two types of the Korthpule-Kaolin and of Bricks Tirana Factory clays that contain a great quantity of Glina & Na3PO4 x Ca (OH)2 compound components. The experiments repeated using different sorption masses, temperatures, and time (min) of the clays, to absorb 226Ra, 238Pu, 90Sr, 137Cs, to determine the deactivation factor of the LLW for the following phases of study [1, 3, 5] (Table 2.6): 1. Optimum temperature of the both types of clays to adsorb of 226Ra, 238Pu, 90Sr, 137 Cs isotopes; 2. Optimum mass of the both type of clays to adsorb of 226Ra, 238Pu, 90Sr, 137Cs isotopes 3. Optimum time (minute) of the both type of clays to adsorb of 226Ra, 238Pu, 90Sr, 137 Cs isotopes

2.7

Results and Conclusions

In our simple scientific research in Lab scale were found and determined the absorption. coefficients (decontamination factor) of low level liquid wastes (LLLW) contaminated by 226Ra 238Pu, 90Sr, 137Cs isotopes, using in nanoscale materials, two types of clays: Tirana Bricks Factory and. Korthpule-Kaolin, which reduced in considerable manner the volumes of the aqueous wastes treated by Radiochemical division in INP [2, 10]. Decontamination process, in general is defined, as the removal of hazardous material from areas, where it is not wanted. Decontamination is utilized to reduce the dose that worker may receive from a component/surface, to reduce probably Chemical, Biological, Radiological and Nuclear (CBRN) agents levels. Decontamination serves to lose CBRN contaminants and fix the remaining contamination in

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place in preparation for protective, storage or disposal remained wastes. The effectiveness of the decontamination can be expressed as decontamination factor (DF), which is, the ratio of contamination level of material before decontamination to the contamination level of material after decontamination [2, 10]. So, the highest decontamination factor for Tirana Bricks Factory clay correspond in 300  C, and for Korthpule-Kaolin clay correspond in 200  C, which were the best temperatures of the clays for 226Ra, 238Pu, 90Sr, 137Cs, removing. The highest decontamination factor of Korthpule-Kaolin clay correspond for 4 gram mass of clay, which was the optimal mass of clays for 226Ra, 238Pu, 90Sr, 137Cs, removing. The highest decontamination factor of Tirana Bricks Factory and Korthpule - Kaolin clays correspond for the time 75 min, which was the best times for 226Ra, 238Pu, 90Sr, 137 Cs removing. The main challenge in our research study were efforts to establish and to develop on the future scientific directions using of nanoscale materials, devices, and systems for potential monitoring of the safety and security environment, in order to defense it from chemical, biological, radiological and nuclear agents generated by industrial, commercial or terrorism activities. The scientific study of nanoscale materials and systems is a promising field, because technological the advanced methods and technologies arise from the potential of nanoscale materials to exhibit unique properties that are attributable to their small size such as surface structure, physical characteristics, and chemical composition, which properties will serve for more new scientific research for innovation of technology [2].

References 1. Treatment of liquid R/W contains 226Ra, 90Sr, 238Pu, 137Cs isotopes at the Radiochemistry Department. INP, Technical Report, Tirana (1998) 2. Vaseashta A, Dimova-Malinovska D, Marshall J (2005) Nanostructure and advanced materials. Springer, Dordrecht 3. Čaleta D, Shemella P (2011) Counter terrorism challenges regarding the process of critical infrastructure protection,. ISBN 978-961-92860-2-9 (ICS), pp 107, 133, 187–190 4. Chemical treatment of R/W, IAEA, Technical Report Series No. 89, Vienna (1968) 5. Chemical precipitation processes for treatment of aqueous R/W, IAEA, Technical Report Series No. 337, Vienna (1992) 6. Handling and treatment of radioactive aqueous R/W, IAEA, TEC/DOC–654, Vienna (1992) 7. Poirier MR, Herman DT, Burket PR, Peters TB, Serkiz SM (2004) Testing of the in situ, mixed iron oxide (IS-MIO) alpha removal process. 2004 NTIS Reports. NTIS No: DE2004–834243/ XAB 8. Arafat HA, Aase SB, Bakel AJ, Bowers DL, Gelis AV (2002) Parametric studies on the use of in situ formed magnetite for the removal of 90Sr and actinides from tank waste at the Savannah River Site. 2002 NTIS Reports. NTIS No: DE2004–822559/XAB 9. Wilmarth WR, Mills JT, Dukes VH, Fondeur FF, Hobbs DT (2003) Permanganate treatment of Savannah River site stimulant wastes for strontium and actinide removal. 2003 NTIS Reports. NTIS No: DE2004–817621/XAB 10. Guidotti M (2013) Structured inorganic oxide-based materials for the absorption and destruction of CBRN agents. In: Advanced sensors. Springer, Dordrecht. Due Sept. 2013

Chapter 3

BORON10 Isotope Based Neutron Radiation Semiconductor Sensors Paata J. Kervalishvili

Abstract Nowadays it is highly important to have instruments for subatomic particles – neutrons monitoring with the high sensitivity that will prohibit widespread harsh environmental pollution, and with the capabilities to provide quantitative information as well as alarm functions. The development of new range of sensor materials has provided devices with enhanced selectivity and sensitivity. Elaborated physical principles of work of 10B isotopes doped semiconductor nanosensitive elements and basis of their fabrication technology determine development of high-efficient nanosensors of the new construction. It was found that Boron-containing materials mainly semiconductors are the best because of B10 isotope’s special neutron capture properties. Since neutrons are uncharged their detection depends on the secondary ionizing processes induced by the products of neutron capture reactions, most important of which is the capture by a 10 B nucleus. It was investigated: the peculiarities of the technology of laying the semiconductor Si thin films doped by 10B isotopes and studying the possibility of control of concentration and properties of Boron in Si nanostructures; parameters and main electro-physical characteristics of nanosensory elements; possibilities of their unification into sensory systems. It was found that 7Li born as result that nuclear-chemical reaction is the shallow donor in Silicon nanostructures that positively influence on sensor element’s sensitivity. Within the frame of the work it was done the comparative analysis of conditions of preparation 10B isotope contained neutron sensitive elements based on crystals of elementary Boron, Boron Carbide, Boron Nitride, and other different semiconductors included elementary ones and alloys. Keywords Semiconductor · Nanostructure · 10B isotope · Neutron sensor

P. J. Kervalishvili (*) Georgian Technical University, Tbilisi, Georgia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_3

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3.1

P. J. Kervalishvili

Introduction

The weapons of mass destruction threats are constantly evolving and have grown more complex since the end of the Cold War. On the other hand, the use of nuclear processes for production of energy, which becomes more and more popular in developed countries, requires extensive radiation monitoring, as there are always risk factors of the radiation leakage and environmental pollution in nuclear – power stations (the last case – Japan, March 2011, where 13
109 times more neutrons than initially estimated were released times higher than the forbidden zone width). Terms like “Obvious implication for human health” and “Neutron radiation is the most severe and dangerous radiation known to mankind, as it can travel great distances” are common. Even if a nuclear accident is caused by a natural catastrophe, such as tsunami, the results on neutron radiation are significant, such as the Fukushima Disaster in 2011 (Fig. 3.1a, b). Designing, developing and manufacturing neutron detectors is primarily and most widely governed by hybrid manufacturing technologies, involving gas excitation and monitoring technologies (Fig. 3.2-left) [2]. There are a variety of solid state detectors available today for measuring the neutron irradiation, especially the semiconductor detectors (Fig. 3.2-right). The main and the best sensory material for semiconductor sensors is ultra-pure Germanium (Ge) (density 2.3 gr/cm3) and Silicon (Si) (density 5.3 gr/cm3) single crystals. They work as ionization chambers except that rather than gas, the semiconductor materials such as Si or Ge are used. Whenever a radiation particle comes to the surface and later enters to the body of the sensory elements it generates a charge carrier. Then, the high voltage accelerates the free electrons, which cause them to ionize additional (non-equilibrium) electron-hole pair, which under the influence of voltage moves towards electrodes. This causes a current to be produced. The current is roughly proportional to the quantity and energy of the radiation, times higher than the forbidden zone width (it seems that additional energy is also spent on phonon oscillations). The main parameters that must be paid attention to during the selection of sensory elements and detectors are: • Registration efficiency • Spatial resolution capacity • Time parse capacity • Area of registering work • Compactness and design simplicity for usage • Reliability usage and low index values • Manufacturing technology However, as a rule, they all have complicated construction and manufacturing process with laborious and careful experimental process. They are also characterized by large dimensions and operational ability from 200 Volts up to 2000 Volts. Single Crystals of Germanium and Silicon are sufficient sensory elements for preparation of solid state detectors, but their specific resistivity is relatively low and is not adequately sufficient (about 104 Ohm.cm and 102 Ohm.cm for Si and Ge

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49

Fig. 3.1 A natural catastrophe (a) can be responsible for neutron radiation (b). [1]

respectively), thus not permitting better sensitivity. To improve the electroresistivity it is necessary to employ special techniques, such as either particular doping (special isotopes) or cryogenic operation (usually liquid nitrogen temperature is sufficiently acceptable). A particular, concentrated and targeted energy of 3.5 eV for Silicon and ~3.0 eV for Germanium has to be transmitted towards the neutron sensing element in order to generate an electron-hole pair. This energy corresponds to approximately three times the forbidden zone width (apart from spending some of the transmitted energy on phonons oscillations, the carrier pairs have to elevate in pretty higher bands to provide readable signals). However, the energy needed to create an electron-hole pair in semiconductors is ten times smaller than the one in gases. This means that detected signals from

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Fig. 3.2 Types of neutron detectors: gas detectors (a), solid state detectors (b) [2]

semiconductor-based neutron detectors are ten times higher than those received from ion detectors. Additionally to that, the dispersion of amplitude distribution is ten times less in semiconductors, suggesting that the detector has better ability to parse the energy. Unlike Hybrid-Design based detectors, semiconductor detectors are faster, offering high parse ability. It should be noted that they are sensitive to gamma radiation, thus suffering from easy radiation damage as a result. Furthermore, the detectors of ionized radiation based on GaAs and GaAlAs isolated layers with a barrier contact have a high boundary sensitivity and lower noise level, high energy resolution giving the possibility of registering weak ionized flows. The detectors fabricated on the diamond basis, which are necessarily equipped with additional amplifiers, have high reliability, offering the possibility of increased signal amplitude. The detector of high sensitivity of ionized radiation comprises of the semiconductor single-crystalline layer and galvanically isolated areas from each other, such as a micro-structural layer of weakly doped diamond [3, 4]. All these above described solid-state neutron detectors, representing the current state of the art, suffer from poor resolution, moderate to poor span, inconvenient geometries, low absolute efficiency and a lack of directional information. The need for improved neutron detection is evident since neutrons are a highly specific indicator of fissile materials. Neutron detectors fall into two categories: those suitable for detecting thermal (low-energy) neutrons, and those that directly detect and measure the energy of fast (high energy) neutrons. The appearance of new advances in nano-technology and nano-materials appears to be important for the development of neutron detectors. The development of new technologies (especially concerning studies towards their mass production) and the corresponding development of the proper microstructure and nano-structure with the required characteristics can be enhanced by the newly appearing nano-materials [5].

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51

Compared to the analogies, Boron stable isotope doped Si based na-nosensory elements and relevant devices will have higher sensitivity and resolution, small dimensions, and what is important, for their functioning will be use much smaller energy power (low voltage and current). Natural boron consists primarily of two stable isotopes, 11B (80.1%) and 10B (19.9%). In nuclear industry boron is commonly used as a neutron absorber due to the high neutron cross-section of isotope 10B. Its (n,alpha) reaction (Fig. 3.3) crosssection for thermal neutrons is about 3840 barns (for 0.025 eV neutron).[6]. There are several advantages of 10B containing materials making them useful in designing the neutron detector devices. Boron is a chemical element with two stable isotopes 10B and 11B. Both interact with neutron through elastic and inelastic scattering processes. But, 10B also interacts with neutron non-elastically – through capturing. This difference makes the total cross section of a 10B – n interaction strongly exceeding that for 11B, as well as most of isotopes of other chemical elements. For example, the total neutron cross-section of 10B, 11B, and natural B for the “room-temperature” neutron beam, i.e., with mean kinetic energy of E ~ 0.025 eV which is translates into mean velocity of v ~ 2200 m/s, equals to 3835, 0.0055, and 767 barns, respectively. Neutron cross section of 10B exhibits the monotonous energy dependence, ~1/E1/2 over the almost entire examined incident neutrons energy range 105-107 eV, what is not the case for isotopes of other elements [7, 8]. B þ nth ð0:025 eVÞ ! 4 He2þ þ 7 Li3þ þ 2:79 MeVð6%Þ 10 B þ nth ð0:025 eVÞ ! 4 He2þ þ 7 Li3þ þ 2:31 MeV þ γð0:48 MeVÞð94%Þ 10

Moreover, isotope 10B has high (n,ɑ) reaction cross-section along the entire neutron energy spectrum. The cross-sections of most other elements becomes very small at high energies as in the case of cadmium. The cross-section of 10B decreases

Fig. 3.3 10B Nuclear Fission Process [9]

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Fig. 3.4 Neutron cross section of boron for 10B[10]

monotonically with energy. For fast neutrons its cross-section is on the order of barns (Fig. 3.4). Boron as the neutron absorber has another positive property. The reaction products (after a neutron absorption), helium and lithium, are stable isotopes. Therefore there are minimal problems with decay heating of control rods or burnable absorbers used in the reactor core. Since the isotope 10B has a significantly higher neutron cross-section, the 10B depletes much more faster than 11B. Without the addition of fresh boron (19,9% of 10 B) into the primary coolant system the enrichment of 10B in Boron based material continuously decreases. In the result the enrichment of 10B at the end of the fuel cycle can be for example below 18% of 10B. This phenomenon must be considered in all the criticality calculations (e.g. shutdown margin calculations, estimated critical conditions or general core depletion calculations). One more advantage of the low atomic weight is that products of the nuclear reaction 10B – n are stable – non radioactive particles. Neutrons detection ability by any boron-containing material is determined by the higher-limit of concentration n of 10B atoms. Its values can be calculated on the basis of appropriate geometric models for atomic structures of important boron rich materials [11]. Here it is necessary underline that the product of above shown nuclear-chemical reaction – Lithium can be introduced to boron-doped p + silicon, in amounts low enough to maintain the p character of the material, or in large enough amount to counterdope it to low-resistivity n type[12, 13].

3 BORON10 Isotope Based Neutron Radiation Semiconductor Sensors

3.2

53

Results and Discussion

The ability of depositing conformal and uniform coating of 10Β is one of the key steps to the success of neutron semiconductor detectors. Since α particles are generated in the 10B (n, α) reaction, any air gap between the semiconductor and the boron layer will decrease the detector sensitivity. Our proposed semiconductor pillar platform requires completely filling of the high-aspect-ratio space between the pillars with boron. The common methods for Boron deposition are electron beam (e-beam) evaporation, sputtering, and chemical vapor deposition. E-beam evaporation of boron is the most common method to deposit boron because of its simplicity in the requirement of the boron source. Extensive investigations were performed to optimize the evaporation of boron. Since boron has a high melting point (2076  C) and sublimation point (2550  C), electron beam, rather than resistive heating, is required to supply enough energy for vaporization. Boron source targets with low purity (90% or less) or uneven heating of the boron target will cause non-uniform evaporation rates and “spiting” of materials from the evaporation target. As the e-beam evaporation is a line-of-sight method of deposition, the photo-resist pattern can easily create shadowing effects and therefore create small gaps between the vertical walls of pillars and the as-deposited boron layer. Sputtering is another method to deposit boron onto high-aspect-ratio structures. Since the sputtering action of the boron targets would generate boron clusters in randomized directions, the as-deposited boron layer is expected to be more conformal to the geometry of the substrates. However, as Boron is a poor conductor charging of the target during sputtering will occur. Therefore, a pure boron sputtering target will usually yield low deposition rates unless the boron is coated as a thin layer on a conductor. Thus, semiconducting boron carbide (B4C) or doped boron is often used as the sputtering target to deposit materials with10Β isotopes [14]. Special attention was paid to produce Si nanofilms doped by Boron for which the method of the laser plasma deposition (Fig. 3.5). [15, 16]. Laser plasma deposition method in various modifications was elaborated and used by the authors of works [14, 15] for preparation of nanofilms of different boron Fig. 3.5 Laser Plasma Deposition scheme

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Fig. 3.6 Nanosensory system completion scheme Nanosensory Film

Prototype of nanosensory element

Nanosensory system

based materials. By this method it is possible to produce desired structural and parametrical nanofilms with high effective sensory characteristics by using combination of two, mostly effective methods: physical vapour deposition (PVD) and chemical vapour deposition (CVD) processes, also vary technological temperatures. Receiving of new constructional decisions on elements and detectors created on micro and nanostructure, study and working out of the fundaments of new technological methods is one of the main goals of our project as well as development of the theoretical foundations of design and manufacturing methods of sensitive elements on the basis of semiconductor Si nanostructures enriched by isotopes for gamma and neutron radiation detectors and preparation of prototype of innovative nanosensor of a new design able to function in rude pollution environment (Fig. 3.6). Among the main goals of the works done it is necessary to underline: • Development of physical principles of work of 10B and 11B isotope doped semiconductor nanosensitive elements and the theoretical bases of their fabrication technology. • Elaboration of neutron nanosensory elements of new construction with the high resolution and sensitive capacity • To study the peculiarities of the technology of laying the semiconductor Si thin films doped by 10B isotope and their properties • Investigation of exploitation parameters and main electro-physical characteristics of nanosensory elements and development of technical version of their unification into sensor systems. • Modeling of constructional and physical parameters of sensor elements created on the basis of semiconductor Si nanostructures doped by isotope 10B, optimization of their compactness and constructional simplicity. • Carrying out the relative researches of the main parameters of a prototype of sensor elements created on the basis of semiconductor Si nanostructures doped by isotope 10B. The aim of the work can be imagined by the following scheme: The object of research was – the nanofilms fabrication using semiconductor Si doped by 10B isotopes and its basis. In order to perform the tasks of the works the experimental and modeling research methods were used. Taking into account that semiconductor nanosensory elements and devices are innovative products, it is necessary to use the original design, constructive and technological decisions. The design process is complicated and multi stages which means: drafting the sketch variant of the elements and devices; computing modeling process; which should take into account all the requirements

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which must meet the challenges of working devices. The most important are problems connecting with nanostructures and nanoscale of the device elements. Development of technological processes, the selection of exact technology operations and optimization of its parameters is one of the most pressing problems. The originality of research determine by have high sensitivity and resolution capacity, small dimensions, much smaller power consumption, low voltage and power of sensor elements and sensory devices. Thanks to high-limits of the 10B isotope content in materials, from which should be made neutron detectors, which is too high: (0.1–2.5) 1023/cm3, neutrons should be rapidly stopped in a 10B-enriched material [17]. Consequently, in all the solid-state neutron-sensors based on 10B-rich materials, working body should be a micro- or nano-layer. If we build the model of evaluation the key physical characteristics of the neutron detectors, when E, the energy released during a single act of 10B – n interaction, is spent only on the thermal generation of the electron–hole pairs, consequently, the rate of rise in the temperature in process of neutron absorption in material should be dT/dt ¼ EW/C, As for the neutron detectors’ typical operation time, apparently it can be estimated from the following relation: τ ¼ l/v, where W is the rate of releasing of the nuclear reaction products, C is the heat capacity per unit volume of the irradiated material and v is the neutrons mean velocity. If we take into account the relevant parameters in the model, the general conclusion is that 10B-isotopically enriched semiconducting modifications of elemental boron, semiconducting boron compounds, and boron-doped common semiconductor materials can serve as working bodies for thin-film, high reliable, high sensitive, and fast-acting robust solid-state electronic neutron detectors of various types. Using obtained results and relevant multipliers, engineers and designers of solidstate detectors of neutron radiation can easily recalculate parameters for devices of different designs and different values of the incident neutron flux. The elaborated technology and construction methods enable us to create a new variety of devices, which contribute to the development of the field. Certainly, these devices will have the users and some proper attention of special-purpose organizations working both in the radiation and ecological safety field (such as engineering, medicine, nuclear power installations area, and a spacecraft power systems etc.). These devices can be used successfully to fulfill the tasks, which puts the Border Guard Service and and public safety.The semiconductor nanosensory elements and the devices created on the basis of 10B doped Silicon will play an important role for monitoring of the environment. Launching new sources of neutrons in different regions of a glob stimulates activation of works related to monitoring of nuclear radiation. The need to develop a long-term strategy and coordination of research activities dedicate to security issues moved foreground. Protection from radiation and nuclear security of the population and nature is among the most actual problems which face almost all countries, which are more prone to pollution as a result of possible nuclear-radiation accidents and catastrophes, production of nuclear weapons, nuclear field testing. In the same way there is a

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danger of escalation of the situation as a result of utilization of the components of destroyed aging nuclear plants, failure of atomic submarines and nuclear weapons. For radiation safety there is need of development of sensory elements and sensory systems for instantaneous responding to variation of nuclear radiation. In order to be useful as a part of Artificial Intelligence systems, the sensors and sensory systems will be designed as a miniature instrument providing information transmission and processing about neutron radiation. In this case they often can be applied to various areas of engineering, medicine, nuclear power installations, space power systems etc., where it is necessary to work as the precise temperature measurement instrument in hazardous conditions. The need for improved neutron detection is evident since neutrons are a highly specific indicator of fissile material. Generally preparation of state-of-the-art sensory systems for radiation measuring instruments based on semiconductor and semimetal nanostructures includes test methods for modelling monitoring nuclear radiation and particle concentrations for indoor and outdoor environments and self-organization modelling. It was investigated the influence of dopant compensation on carrier mobility. The measured mobilities for majority carriers and on for minority carriers are in a good agreement with Klaassen’s model in the last solidi-fied fraction of the Silicon monocrystals. Since this part of the nanostructures contains the highest amount of p-type impurity (around 3
1017 cm-3) the agreement with Klaassen’s model shows that third group impurities such as Ga, B, etc. do not impact on the mobility in a significant different manner. To check the influence of compensation on carrier mobility it have been plotted the relative deviation of measured mobility from the calculated mobility using Klaassen’s model as a function of the compensation level Cl ¼ ([B] + [P] + [Ga])/p. It is clear that he difference between the model and the measurement increases with the compensation level. (Fig.3.7).

Fig. 3.7 Left – Relative deviation on the majority carriers mobility depending on the compensation level. Measured data by Hall Effect are compared to the mobility calculated with the Klaassen’s model. Right – Evaluation of the mobility correction term μcor depending on the compensation level

3 BORON10 Isotope Based Neutron Radiation Semiconductor Sensors

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4 3.9 3.8

p, mΩ cm

3.7 3.6 3.5 3.4 3.3 3.2 3.1 3 80

100

120

140

160

180 T, K

200

220

240

260

285

Fig. 3.8 Temperature dependence of specific resistance of Si(10B) samples in the temperature range 80–285 K

Particular interest for sensory characteristics of isotope Boron10 contain Silicon sensitive elements is connecting with its charge carriers mobility and lifetime. In order to better illumination of these properties the temperature dependence of specific resistivity in temperature range 80-285Kwas measured (Fig. 3.8) using the equipment building by GTU team. It was shown that specific resistance for this kind of samples is lying in interval 3.14–3.85 mOm.cm, which is suitable for neutron flux measurements. Coming back to the theory of the semiconductors the main parameter of the any detecting (sensory) instrument is μƮ, were μ – is mobility of carriers, Ʈ-lifetime. If we build the model of evaluation the key physical characteristics of the neutron detectors, when E, the energy released during a single act of 10B – n interaction, is spent only on the thermal generation of the electron–hole pairs, consequently, the rate of rise in the temperature in process of neutron absorption in material should be dT/dt ¼ EW/C. The strong interest in development of Smart Sensory Networks for nucle ar radiation monitoring is closely connecting with works dedicated to elaboration of novel sensory systems based on Si(B10) nanostructures (including quantum effects in quantum dots structures). In the framework of development of Si (10B) neutron sensors it was performed the work for elaboration the sensory systems with high efficiency of relevant networks. In this direction the following experimental works were performed: • Fifteen sensors were irradiated under identical conditions for various exposure times; • Neutron flux was parallel in respect to the central axis of each sensor;

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• The whole surface of each sensor was irradiated with neutrons; • All sensors were adequately treated in laboratory to be prepared for measurement; • Three different independent measurements were conducted with the sensor ID hidden; • The average of each of the three measurements was calculated for every sensor.

track density (tracks per square mm)

The measurement results are presented at the tables and figure below.

600 500 400 300 200 100 0 0

200

400

600 800 Exposure (min)

1000

1200

1400

The measurement error of each sensor was calculated as the weighted error, viz. accounting both the Poisson statistics and standard deviation. As results of the experimental works it is necessary to underline that: The sensors exhibited acceptable linear response with square of the Spearman’s correlation coefficient approximately 0.9. The irradiated sensors can be employed for measurement of neutrons in special environments and can be used satisfactory for the implementation of an environmental neutron sensing network (Fig. 3.9). The Alarm Indicator Management Loop runs continuously, and contains the parameter information for the alarm conditions. The system allows alarm categories to be set for different responder action on the basis of alarm level. LabVIEW™ also sends electronic mail notification following the paging notice. Notices include alarm level, count rate, and the time to reach the threshold parameter dose at the present count rate. Ad hoc data analysis takes place on Apple“computers using the MacOS X operating system. This is also available for Linux and Windows‚ operating systems and has objectoriented capabilities, making it very easy to use any customized plotting or analysis functions that are developed. To satisfy the requirements of the distributed sensors networking and control, a wireless sensors network infrastructure was employed. In particular, a series of ZL-01 WSN nodes were used (see Fig. 3.10, a). These specific WSN nodes have been designed in the Piraeus University of Applied Sciences for research studies [18]. For the WSN we use for the network communication the IEEE 802.15.4/ ZigBee protocol. The operating frequency band is at the free ISM band of 2.4 GHz. The wireless network may support up to 65,000 nodes in a MESA network topology. The data routing paths are not predefined and are self-defined according to

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Setup System Parameters

Low-Power mode Sleep for 15 sec

Read Wind Direction

Read RTRAM Sensor Counts Turn off Transceiver

Read Wind Speed

15 Minutes have past?

Turn on Transceiver

Receive System Parameters

Transmit Data XML Format

Significant Radiation Level?

Fig. 3.9 Flow chart of the low-power remote sensor platform logic Fig. 3.10 (a) The ZL-01 Wireless Sensors Network (WSN) node device; (b) The Atmel’s ZigBee-to-USB dongle device

the particular physical environmental constraints. This is very convenient for applications in closed areas such as in the hospital premises were there are several signal barriers from the building materials. According to the test setup, each sensor is interfaced with a ZL-O1 WSN node in order to send through the wireless network its measurements to a data concentrator. The concentrator is the Personal Area Network

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Fig. 3.11 The full topology deployment of the experiments tests setup

(PAN) Coordinator of the network and for the specific needs of the contemplated test was decided to be a ZigBee-to-USB dongle device from the Atmel Inc. (see Fig. 3.10, b). The network topology of the inter-connected sensors is illustrated in Fig. 3.11. The ZL-01 WSN nodes support all the possible ports and data buses to interface with the sensors in the field. Specifically, the UART, SPI, and I2C embedded interfaces are fully supported. According to the application scenario, every sensor sends its measurements to the ZL-01 node via the aforementioned interfaces. Next, the ZL-01 node transmits wirelessly the data packets to the PAN Coordinator. Then, the PAN Coordinator through the USB bus sends the data packets to a portable personal computer which runs Windows Operating System. A specific software application has been developed based on the LabVIEW platform for the data acquisition, processing, logging and monitoring of the captured measurements. It is possibly not clear that the sensor is/maybe placed on the upper part of the wireless device. So all the upper coverage part can be the detector, and then with optical methods (eg. camera) we can read the measurements. The wireless network consists of six units that are used aligned in both sides (two triplets). The distance between the wireless units was set to 15 cm, in order to have the best local statistics. Nuclear safety criteria were used, in terms that when the sensors’ measuring level is higher than the safety cut-off point (set by the user) the wireless networks unit is colored red (otherwise green). When it transmits the data to the computer or station via a WiFi it is coloured blue (Fig. 3.12). Each home made unit operates in and transmits in the frequency of WiFi and needs a 50 Hz power supply.

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Fig. 3.12 Nuclear radiation wireless sensor network: (a) general view; (b) measuring level is higher than the safety cut-off for all units; (c) measuring level is lower than the safety cut-off for all units; (d) measuring level is higher than the safety cut-off for one unit; (e) sensors are in the process of transmitting data to the base

The novelty of research performed was based on research of the new type of sensor elements and sensory devices with high parameters, which it is possible to use in highly sensitive systems of neutron radiation and measurement. These devices will have to unite in electronic and intellectual networks. They will be able to function in harsh environment pollution. Compared to the analogies, these nanosensory elements and sensory devices will have high sensitivity and resolution capacity, small dimensions, much smaller power consumption, low voltage and power. Using obtained modeling results and relevant multipliers, engineers and designers of solid-state detectors of neutron radiation can easily recalculate parameters for devices of different designs and different values of the incident neutron flux. The technology and construction methods which were developed enable us to create a new variety of devices, which contribute to the development of the field. The one of the important feature is possibility of adaptation of developed sensory networks in special hospitals where radiation sources are using for treatment of different diseases. Elaborated semiconductor nanosensory elements and devices are playing an important role for creation of networks for the environment monitoring.

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Conclusions

Development of new decisions for creation of high effective neutron sensors, relevant devices, systems and networks was one of the main goals of our work as well as development of the theoretical foundations of design and manufacturing methods of sensitive elements making from semiconductor nanostructures enriched by 10B isotope for neutron radiation measurements for nuclear radiation monitoring in a rude pollution environment [19, 20]. Though systematic experimental investigations of isotopic effects just are being started they already have shown a very big importance of one of promising direction of modern physics – isotopic phenomena in condensed media. Comprehensive analysis of results concerning the influence of isotopic composition on physical properties of materials shown that not only the nuclear parameters of substances (e.g. cross section of nuclear particles, nuclear-chemical reactions, etc.) but characteristics of many other physical and chemical effects are dependent of neutron number in nucleus of different atoms [21, 22] such as: chemical reactions’ kinetics (which directly or indirectly are connected with the change of the atoms electron shells’ state taking place due to nuclei’s mass and spin changes); electron affinity (15N > 14N and13 C > 12C in some chemical reactions); light-produced mass transport (laser induced); the substitution of isotope 10B with the isotope 11B leads to the growth of boron atom’s ionization potential up to 0.01 eV; and many others. Acknowledgments I express my acknowledgment to all colleagues having collaborated with me in experimental, theoretical and technological activities and contributed to the development of work partly presented in this paper.

References 1. Omoto A (2014) Japan’s nuclear R&D activities, The 15th FNCA ministerial level meeting, Sydney, Australia, November 19 2. Kervalishvili PJ (2012) Boron isotopes doped germanium and silicon based gamma and neutron radiation nanosensors. In: Book of 2nd international conference “nanotechnologies”, nano – 2012, September 19–21, Tbilisi, Georgia, p 120 3. Murty KL (2012) Chapter I: An introduction to nuclear materials: fundamentals and applications. Wiley/VCH, Berlin 4. Kervalishvili PJ (2012) Boron isotopes doped germanium and silicon based gamma and neutron radiation nanosensors. In: Book of 2nd interantional conference “nanotechnologies”, nano – 2012, September 19–21, 2012, Tbilisi, Georgia, p 120 5. Kervalishvili PJ, Yannakopoulos PH (2016) Nuclear radiation nanosensors and Nanosensory systems. In: NATO science for peace and security series B: physics, and biophysics. Springer, Dordrecht. 200p 6. Kervalishvili P (2009) Some neutron absorbing elements and devices for fast nuclear reactors regulation systems. NATO conference nuclear safety and security, Yerevan, Armenia, May 26–29

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7. Kervalishvili P, Shavelashvili S (1987) The principle of recording neutrons with the AID of sensitive boron elements. Soviet At Energ 62(5):412–414 8. https://www.nuclear-power.net/wp-content/uploads/2015/08/Boron-neutron-reaction.png (2015) 9. Japanese Society of Neutron Capture Therapy.[c/o Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, R1–13, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226–8503, JAPAN] 10. National Nuclear Data Center. “NuDat 2.1 database”. Brookhaven National Laboratory. Retrieved 23 February (2017) 11. Kervalishvili PJ (2009) Boron based neutron absorbing elements and control systems. Abstracts – NATO Advanced Research Workshop, Boron Rich Solids, Orlando, Florida, USA 12. Rauschenbach HS (2012) Solar cell array design handbook: the principles and technology of photovoltaic energy conversion. Springer Science & Business Media, New York, p 157–. ISBN 978-94-011-7915-7 13. Weinberg I, Brandhorst Jr HW (1984) U.S. Patent 4,608,452, Lithium counter doped silicon solar cell 14. Bykovskii YA, Kervalishvili P, Nikolaev IN (1993) Neutron Fluence sensor based on boron carbide. Tech Phys Lett 19(7):457–458 15. Kervalishvili P, Shalamberidze S (1993) Semiconductor material film production by laser plasma deposition. Le Vide, le Couches Minces N267:189–197 16. Kervalishvili PJ, Berberashvili TM, Chakhvashvili LA, Goderdzishvili G, Yannakopoulos P, Davaris A (2011) Nuclear radiation nanosensors and nanosensory systems. eRA-6 – The Synergy Forum, International scientific conference, Piraeus, Greece 19–24 September 17. Kervalishvili P, Karumidze G, Kalandadze G (1993) Semiconductor sensor for neutrons. Sens Actuators, A 36(1):43–45 18. Kottou S, Nikolopoulos D, Petraki E, Bhattacharyya D, Kirby PB, Berberashvili TM, Chakhvashvili LA, Kervalishvili PJ, Yannakopoulos PH (2015) Monte-Carlo modelling and experimental study of radon and progeny radiation detectors for open environment. In: Progress in clean energy, volume 1, analysis and modeling. Springer International Publishing, Cham, pp 787–803 19. Kervalishvili PJ (2015) Novel approaches to nanosensory systems development. Am J Condens Matter Phys 5(1):1–9 20. Kervalishvili P, Berberashvili T, Chakhvashvili L (2011) About some novel nanosensors and nanosensory systems. Nano 4:155–164 21. Kervalishvili P (1990) About isotopic effect at interaction of substances with oxygen. J At Energ 68(N1):36–41 22. Kervalishvili PJ (2014) About isotope effects in condensed matter. Bull Russ Acad Nat Sci N1:3–10

Chapter 4

Transmission of Two Measuring Signals by an Invariant Property of Three Wire Communication Lines Alexander Penin and Anatolie Sidorenko

Abstract The invariant relationship between the sets of load conductivity values and the corresponding values of the input currents of the two or three wire communication lines is shown. This relationship does not depend on parameters of the lines and the accuracy of measuring devices. It allows transmitting signals in the analog form of different physical sensors for monitoring technical or natural objects. Keywords Communication line · Resistive sensor · Projective transformation · Cross ratio · Projective coordinates

4.1

Introduction

Different sensors of physical values are used for monitoring technical or natural objects. For these usually remote devices, it is necessary to provide of transmission of measuring signals [1], for example, by multi-wire line [2]. At present time, methods for transmission of discrete electrical signals in binary code are used. These methods are known as the RS-485 and MicroLAN interfaces. Low noise immunity is a disadvantage of the known methods. Therefore, researches and elaborations of systems for transmitting discrete electrical signals in the analog form with improved noise immunity are important [3–5]. But, two dedicated communication lines are necessary for transfer of two signals. Point is that longitudinal and lateral resistances (conductivities) of actual lines do not allow using the common wire so as to apply the more economical three-wire lines. The theoretical researches show that invariant relationship takes place between the sets of load conductivity values and the corresponding values of the input currents of A. Penin (*) D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova A. Sidorenko D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_4

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this line with losses [6–8]. The cross ratio of four points, known in projective geometry, is this invariant relationship [9]. Therefore, the value of cross ratio (is the ratio of two proportions) does not depend on parameters of the line and an accuracy of measuring devices. These invariants are used for transmission or, more precisely, for restoration of measuring signals over the two and three wire lines.

4.2

Foundation of the Transmission of Signals over a Line

In the present chapter the basic states of the obtained results are presented. Case of one load. Let us consider a two-port circuit, as a model of a wire line, in Fig. 4.1. A variable conductivity YL1 is the load of this two-port. The system of equation has the known view


I 0 ¼ Y 00 V 0  Y 10 V 1 I 1 ¼ Y 10 V 0  Y 11 V 1 ,

ð4:1Þ

where Y parameters are. Y00 ¼ y10 + y0, Y11 ¼ y10 + y1, Y10 ¼ y10. We determine the characteristic value of regime parameters for the short circuit OC SC(V SC 1 ¼ 0) and open circuit OC (I 1 ¼ 0). Then SC SC V SC 1 ¼ 0, I 1 ¼ Y 10 V 0 , I 0 ¼ Y 00 V 0 ,

V OC 1 ¼

Y 10 V , I OC 1 ¼ 0, Y 11 0

I OC 0 ¼

ΔY V : Y 11 0

ð4:2Þ ð4:3Þ

For these parameters, system (4.1) becomes as I 0 ¼ I SC 0 

Fig. 4.1 Two-port with a variable load

I SC I SC 1 V 1 , I 1 ¼ I SC  1OC V 1 : 1 V0 V1

ð4:4Þ

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

67

Fig. 4.2 Conformity of the load and input conductivities of a two-port

As the value YL1 ¼ I1/V1 is an independent quantity, we get the load straight lines in Fig. 4.2. In this case, the input conductivity or relationship YIN(YL1) has the known fractionally linear view by (4.1) and the transmission a parameters Y IN ¼

I0 a Y þ a21 ¼ 22 L1 : V 0 a12 Y L1 þ a11

Therefore, the conformity YL1 ! YIN, YL1 ! I0 is a projective transformation. This projective transformation preserves a cross ratio of four points. Then, we may determine the running regime parameter by an identical value for the various actual regime parameters (conductivities, currents) and for different sections of circuit (input and output). Let an initial regime be given by values Y 1L1 , I 10 . Then, the cross ratio has the form OC   Y 1L1  Y OC Y REF 1 REF SC L1 L1  Y L1 m11 ¼ Y OC Y Y Y  , ¼ L1 L1 L1 L1 SC Y 1L1  Y SC Y REF L1 L1  Y L1

m11 ¼

I 10  I OC I REF  I OC 0 0  0REF : 1 SC I0  I0 I 0  I SC 0

ð4:6Þ ð4:7Þ

The invariant value m1 represents a practical interest for remote load conductivity measurement or accurate transmission of resistance sensor signal YS through an unstable two-port in Fig. 4.3. In this case, the cross ratio value m11 is accepted as a transmitted analog signal, 1 m1 ¼ Y S . In a short time slot (by control generator Gen), the three samples of load SC REF conductivity are transmitted by connecting three test conductivities Y OC L1 , Y L1 , Y L1 and the information conductivity Y L1 . From (4.6), the information conductivity is precomputed by the signal YS and the unit F. In turn, the signal Y S ¼ m11 is calculated directly by the measured input currents (4.7) and the inverse unit F1.

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Fig. 4.3 System of transmission of a sensor signal by the conductivities

Fig. 4.4 Four port with variable load conductivities YL1, YL2

Case of two loads. Now, we consider a four-port circuit in Fig. 4.4. Let us give necessary relationships between the input currents and load conductivities. So, we have V1 ¼ I1/YL1, V2 ¼ I2/YL2. The family of straight lines (I1, I2, YL1) ¼ 0, (I1, I2, YL2) ¼ 0 at change of YL1, YL2 is represented by two bunches of straight lines in the system of coordinates (I1 0 I2) in Fig. 4.5. Next, we use the idea of projective coordinates of a running regime point. Let the initial or running regime correspond to the point M1, which is set by the values of the conductivities Y 1L1 , Y 1L2 and currents I 11 , I 12 . In addition, this point is defined by projective non-uniform coordinates m11 , m12 and homogeneous coordinates ξ11 , ξ12 , ξ13 which are set by the reference or coordinate triangle G1 0 G2 and a unit point SC. Similarity to (4.6), the non-uniform projective coordinate   Y 1L1  0 Y1 10 1 SC G1  ¼ 1 L1 G1 , m11 ¼ Y OC L1 Y L1 Y L1 Y L1 ¼ 1 G1 G1 Y L1  Y L1 1  Y L1 Y L1  Y L1

ð4:8Þ

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

69

Fig. 4.5 Two bunches of load straight lines with the parameters YL1, YL2

m12 ¼

Y 1L2

Y 1L2 :  Y G2 L2

In turn, the homogeneous projective coordinates ξ1, ξ2, ξ3 set the non-uniform coordinates by m1 ¼

ρξ1 ρξ ,m ¼ 2, ρξ3 2 ρξ3

where ρ is a coefficient of proportionality. The homogeneous coordinates are defined as the ratio of distances δ11 , δ12 , δ13 of SC SC the point M1 and distances δSC SC to the sides of the 1 , δ2 , δ3 of the point coordinate triangle G1 0 G2. ξ11 ¼

δ11 I 11 ¼ SC , SC I1 δ1

ρ ξ12 ¼

δ12 I 12 ¼ SC , SC I2 δ2

ρ ξ13 ¼

δ13 : δSC 3

Let us consider the input currents (I3, I4) of our four-port. We may superpose the system of coordinates (I3 0 I4) with the system of coordinates (I1 0 I2) in Fig. 4.6. Then, any point with coordinates (I1, I2) corresponds to a point with coordinates (I3, I4). In terms of geometry, a projective transformation takes place which transfers points of the plane (I1, I2) into points of the plane (I3, I4). Therefore, the reference triangle G1 0 G2, point SC, and running regime point M1 correspond to the triangle 1 G1 0 G2 , point SC, and point M , as it is shown by arrows.

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Fig. 4.6 Projective transformation of the plane (I1, I2) onto plane (I3, I4)

Next, the axes of currents I1, I2 correspond to the axes I 1 , I 2 . Also, two bunches of the straight lines (I1, I2, YL1) ¼ 0, (I1, I2, YL2) ¼ 0 correspond to two bunches of the lines (I3, I4, YL1) ¼ 0, (I3, I4, YL2) ¼ 0 with centers in the points G2 , G1 . 1 Thus, the point M is set by other currents I 13 , I 14 . Also, this point is defined by projective non-uniform and homogeneous coordinates which are set by the reference triangle G1 0 G2 and a unit point SC. 1 The property of projective transformations shows that the point M coordinates 1 are equal to the point M1 coordinates, as these points M1,M are set by the same loads Y 1L1 , Y 1L2 . Therefore, this property gives required invariant relations between the input and output currents. 1 For finding of the point M projective coordinates, it is necessary to use the equations of sides of the reference triangle. Finally, we obtain the non-uniform coordinates by the input currents m1 ¼

C11 I 3 C31 I 3

þ C12 I 4 þ 1 C I , m2 ¼ 21 3 C 31 I 3 þ C32 I 4  1

þ C 22 I 4 þ 1 : þ C 32 I 4  1

ð4:9Þ

Using running values of input currents, we find or, more precisely, restore the values of non-uniform coordinates (4.9). Then, the values of given load conductivities are calculated according to the inverse expressions YL1(m1), YL2(m2) to (4.8). Such formulated algorithm represents practical interest for the transfer of two sensing signals via a three-wire line analogously to the signal transmission via a two-port network. That permits to separate (or restore) two signals by the input currents (five pairs of the currents) of the line. In practice, the characteristic values of the input and output currents (as the vertexes of the coordinate triangles and unit points) are precalculated by testing of the line.

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

71

Fig. 4.7 System of transmission of two sensor signal

To do so, in a short time slot, the five pairs of load conductivity sets (test and SC G1 information values) are transmitted. There are the test conductivities Y OC L1 , Y L1 , Y L1 , OC SC G2 1 1 Y L2 , Y L2 , Y L2 and information conductivities Y L1 , Y L2 . Usually, the test scale G2 conductivities Y G1 L1 < 0, Y L2 < 0. Therefore, the corresponding output currents G1 SC G2 submit to terms I 1 > I 1 ,I 2 > I SC 2 . These high test values complicate the practical realization. Therefore, we will consider the easily testable transmission system [10] in Fig. 4.7.

4.3

Easily Testable System of the Transmission of Two Signals

At first, in a short time slot, the five pairs of test load conductivity sets are SC REF OC SC REF transmitted. There are the test conductivities Y OC as L1 , Y L1 , Y L1 , Y L2 , Y L2 , Y L2 shown in Tables 4.1 and 4.2. For clarity, we give the geometrical interpretation of the obtained sets similarly to Fig. 4.5.

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Table 4.1 Correspondence between the test load conductivities and output currents

Set

Load conductivities

Output currents

1 2

Y OC L1 ¼ 0

Y OC L2 ¼ 0

I OC 1 ¼ 0

Y OC L1 ¼ 0 Y SC L1 ¼ 1 Y SC L1 ¼ 1 Y REF L1

Y SC L2 ¼ 1 Y OC L2 ¼ 0 Y SC L2 ¼ 1 Y REF L2

I OC,SC 1 I SC,OC 1 I SC 1 I REF 1

3 4 5

Table 4.2 Correspondence between the test load conductivities and input currents

¼0

I OC 2 ¼ 0 I OC,SC 2 I SC,OC ¼0 2 I SC 2 I REF 2

Set

Load conductivities

Input currents

1 2

Y OC L1 ¼ 0

Y OC L2 ¼ 0

I OC 3

I OC 4

Y OC L1 ¼ 0 Y SC L1 ¼ 1 Y SC L1 ¼ 1

Y SC L2 ¼ 1 Y OC L2 ¼ 0 Y SC L2 ¼ 1

I OC,SC 3 I SC,OC 3 I SC 3

I OC,SC 4

3 4

I SC,OC 4 I SC 4

The family of straight lines (I1, I2, YL1) ¼ 0, (I1, I2, YL2) ¼ 0 for the test load conductivities is represented by two bunches of straight lines in the system of coordinates (I1 0 I2) in Fig. 4.8. Let us consider the following points. The points I SC,OC , I OC,SC are situated 1 2 SC SC REF , I determinate accordingly on the axes I1 and I2. The coordinates I 1 , I 2 and I REF 1 2 the point SC and REF. The known reference triangle G1 0 G2 with a unit point SC represents a base or initial projective coordinate system. G2 As it was told above, the currents I G1 1 , I 2 considerably exceed the currents SC SC I 1 , I 2 . Therefore, we introduce a complementary projective coordinate system as e2 with the initial unit point SC in Fig. 4.9. e1 0 G the reference triangle G e1 , G e2 correspond to the currents I SC,OC , I OC,SC . Then, we can The points G 1 2 G2 determine the scale conductivities Y G1 L1 , Y L2 using the point REF coordinates. REF REF REF At first, we introduce the homogeneous coordinate ξe1 , ξe2 , ξe3 of the point REF REF REF REF REF δe3 δREF I REF δREF I REF 1 2 1 2 e e e ξ1 ¼ SC ¼ SC , ξ2 ¼ SC ¼ SC , ξ3 ¼ SC I1 I2 δ1 δ2 δe3

ð4:10Þ

e1 0 G e2 . In particular, We are using the distances to the sides of the new triangle G e1 G e2 utilizing the equation of the straight line G I2 I1 þ G1  1 ¼ 0, G2 e Ie2 I1 G1 e I 1 ¼ I SC,OC , 1

G2 e I 2 ¼ I OC,SC , 2

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

73

Fig. 4.8 Two bunches of load straight lines with the test parameters

Fig. 4.9 Load straight lines in the initial projective coordinate system G10 G2 and complementary e1 0 G e2 coordinate systemG

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A. Penin and A. Sidorenko

we obtain 2

REF ξe3

I REF

I 1 REF G2 þ G1  1 eI 2 eI 1 δe3 : ¼ SC ¼ I SC I SC 2 1 δe3 G2 þ G1  1 eI 2 eI 1

Further, the non-uniform projective coordinates eREF m ¼ 1

REF REF ξe1 ξe2 REF e , m ¼ 2 REF REF : ξe3 ξe3

ð4:11Þ

Further, we will use also the coordinate triangle G1 0 G2 with a unit point SC. Let REF REF us introduce the homogeneous coordinate ξREF of the point REF. 1 , ξ2 , ξ3 ¼ ξREF 1

δREF δREF I REF δREF I REF REF REF 3 1 2 1 2 ¼ , ξ ¼ ¼ , ξ ¼ : 2 3 I SC I SC δSC δSC δSC 1 2 1 2 3

ð4:12Þ

We are using the distances to the sides of the triangle G1 0 G2. In particular, for the equation of the straight line G1G2 I2 I1 þ G1  1 ¼ 0, I G2 I 2 1 the coordinate 2

ξREF 3

I REF

I 1 δREF I G2 þ I G1  1 : ¼ 3SC ¼ I2SC I 1SC 2 1 δ3 G2 þ G1  1

I2

I1

Further, the non-uniform projective coordinates mREF ¼ 1

ξREF ξREF REF 1 2 , m ¼ : 2 ξREF ξREF 3 3

ð4:13Þ

Finally, by (4.10, 4.12), the interrelation of the projective coordinates in the initial and complementary coordinate system has the view

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

75

ξe1 ¼ ξ1 , ξe2 ¼ ξ2 , ξe3 ¼ ξ1 þ ξ2  ξ3 mREF ¼ 1

eREF m 1

eREF eREF m m REF 1 2 , m : ¼ 2 REF eREF eREF e þm  1 þ m 1 m 2 1 2

ð4:14Þ

On the other hand,   REF G1 ¼ Y OC Y SC mREF ¼ 1 L1 Y L1 L1 Y L1   REF G2 ¼ mREF ¼ Y OC Y SC 2 L2 Y L2 L2 Y L2

Y REF L1 , G1 Y REF L1  Y L1

ð4:15Þ

Y REF L2 :  Y G2 L2

Y REF L2

Finally, for the load current values and the known test conductivities, the scale conductivity calculator gives the required values REF Y G1 L1 ¼ Y L1

REF mREF  1 G2 1 REF m2 1 , Y ¼ Y : L2 L2 REF mREF m 1 2

ð4:16Þ

Next, we use the geometrical interpretation of the input currents I3, I4. Also, we superpose the system of coordinates (I3 0 I4) with the system of coordinates (I1 0 I2) in Fig. 4.10. f1 0 G f2 , point SC, and running regime point Therefore, the reference triangle, G M correspond to the coordinate triangle G1 0 G2 , point SC, and point M, as it shown by arrows. Next, the axes of currents I1, I2 correspond to the axes I 1 , I 2 . As it was told above, we obtain the projective transformations. Therefore, the point M coordinates are equal to the point M coordinates in the own coordinate systems. In the given case, the homogeneous coordinates are defined as the ratio of SC SC SC distances δ1 , δ2 , δ3 of the point M and distances δ1 , δ2 , δ3 of the point SC to the sides of the coordinate triangle G1 0 G2 in Fig. 4.11. To do so, we use the equations of these sides.The axis I 1 equation (as the straight line, passing through the points 0, G1 ) A01 I 4 þ B01 I 3 þ C01 ¼ 0, where SC,OC OC  I OC , A01 ¼ I SC,OC 3 3 , B01 ¼ I 4  I 4 OC SC,OC OC SC,OC C 01 ¼ I 3 I 4  I4 I3 :

The axis I 2 equation (as the straight line, passing through the points 0, G2 )

ð4:17Þ

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Fig. 4.10 Correspondence between the complementary coordinate systems for the input and output of the line

A02 I 4 þ B02 I 3 þ C02 ¼ 0,

ð4:18Þ

where OC,SC OC  I OC , A02 ¼ I OC,SC 3 , B02 ¼ I 4  I 4 3 OC,SC OC,SC C 02 ¼ I OC  I OC : 3 I4 4 I3

Also, we bring the equation of the straight line G2 G1 A12 I 4 þ B12 I 3 þ C12 ¼ 0,

ð4:19Þ

where , B12 ¼ I SC,OC  I 4OC,SC , A12 ¼ I 3OC,SC  I SC,OC 3 4 C 12 ¼ I SC,OC I OC,SC  I SC,OC I OC,SC : 3 4 4 3 The stage of preliminary testing and calculations are finished at this point. Next, the cross ratios (4.8) are accepted also as the transmitted signals YS1, YS2. Then, the information conductivities are precomputed by the units F1, F2 and (4.8)

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

77

Fig. 4.11 Input characteristics of the line as the complimentary coordinate system

Y L1 ¼

Y G1 Y G2  Y S2 L1  Y S1 , Y L2 ¼ L2 : Y S1  1 Y S2  1

ð4:20Þ

Using the input currents, we calculate the homogeneous projective coordinates ξ~1 , ξ~2 , ξ~3 for the coordinate triangle G1 0 G2 δ1 A I þ B02 I 3 þ C 02 ¼ 02SC4 , ξe1 ¼ SC A02 I 4 þ B02 I SC δ1 3 þ C 02 δ2 A I þ B01 I 3 þ C 01 ξe2 ¼ SC ¼ 01SC4 , SC A 01 I 4 þ B01 I 3 þ C 01 δ2

ð4:21Þ

δ3 A I þ B12 I 3 þ C 12 ξe3 ¼ SC ¼ 12SC4 : SC A 12 I 4 þ B12 I 3 þ C 12 δ3 In turn, the non-uniform coordinates e1 ¼ m

ξe1 ξe e2 ¼ 2 : , m e ξ3 ξe3

ð4:22Þ

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Therefore, the transmitted signals YS1, YS2 Y S1 ¼ m1 ¼

4.4

e1 m , e2  1 e1 þ m m

Y S2 ¼ m2 ¼

e2 m : e2  1 e1 þ m m

ð4:23Þ

Example

Let the four-port, as a model of the three wire line, be given in Fig. 4.12. The precalculated characteristic values of the input and output currents are shown in Tables 4.3 and 4.4. Non-uniform projective coordinates (4.8). m11 ¼ m12 ¼

Y 1L1 0:5 ¼ ¼ 0:3846, 1 G1 0:5 þ 0:8 Y L1  Y L1

Y 1L2 0:333 ¼ 0:2622: ¼ 1 G2 0:333 þ 0:9375 Y L2  Y L2

Homogeneous coordinates (4.10) of the point REF REF I REF 1:459 ¼ 0:6546, ξe1 ¼ 1SC ¼ 2:229 I1

REF I REF 1:602 ξe2 ¼ 2SC ¼ ¼ 0:608, 2:635 I2

Fig. 4.12 Four port with variable load conductivities YL1, YL2

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

79

Table 4.3 Correspondence between the test load conductivities and output currents Set 1 2 3 4 5 6 7 8

Load conductivities Y OC L1 ¼ 0 Y OC L1 ¼ 0 Y SC L1 ¼ 1 Y SC L1 ¼ 1 Y REF L1 ¼ 1 Y 1L1 ¼ 0:5 Y G1 L1 ¼ 0:8 Y 1L1

Output currents Y OC L2 ¼ 0 Y SC L2 ¼ 1 Y OC L2 ¼ 0 Y SC L2 ¼ 1 Y REF L2 ¼ 1 Y 1L2 ¼ 0:333 Y 1L2 Y G2 L2 ¼ 0:9375

I OC 1 ¼ 0

I OC 2 ¼0

I OC,SC ¼0 1 I SC,OC ¼ 2:704 1 I SC ¼ 2:229 1 I REF ¼ 1:459 1 I 11 ¼ 1:101 I G1 1 ¼ 15:11 I G2 1 ¼ 0

I 2OC,SC ¼ 3:091 I SC,OC ¼0 2 I SC 2 ¼ 2:635 I REF ¼ 1:602 2 I 12 ¼ 0:8868 I G1 2 ¼ 0 I G2 2 ¼ 15

Table 4.4 Correspondence between the test load conductivities and input currents Set 1

Load conductivities Y OC L1 ¼ 0

Y OC L2 ¼ 0

I OC 3 ¼ 2:639

I OC 4 ¼ 1:603

2

Y OC L1 ¼ 0

Y SC L2 ¼ 1

¼ 3:125 I OC,SC 3

I 4OC,SC ¼ 2:303

3

Y SC L1 ¼ 1 Y SC L1 ¼ 1 Y REF L1 ¼ 1 Y 1L1 ¼ 0:5 Y G1 L1 ¼ 0:8 Y 1L1

Y OC L2 ¼ 0 Y SC L2 ¼ 1 Y REF L2 ¼ 1 Y 1L2 ¼ 0:333 Y 1L2 Y G2 L2 ¼ 0:9375

I SC,OC ¼ 3:309 3 I SC ¼ 3:607 3 I REF ¼ 3:253 3 I 13 ¼ 3:051 I G1 3 ¼ 6:4423 I G2 3 ¼ 5

I SC,OC ¼ 1:912 4

4 5 6 7 8

2 I G2

eI REF ξe3 ¼ I2SC

2 G2

eI 2

þ

I REF 1

þ

I SC 1 G1

eI 1

G1

eI 1

Input currents

1 1

I SC 4 ¼ 2:455 I REF ¼ 2:132 4 I 14 ¼ 1:929 I G1 4 ¼ 3:333 I G2 4 ¼ 5

þ 1:459 0:0578 2:704  1 ¼ ¼ 0:0854: 2:229 0:6768 þ  1 3:091 2:704 1:602

¼ 3:091 2:635

Non-uniform projective coordinates (4.11) eREF m 1

REF REF ξe1 ξe2 0:6546 0:608 REF e2 ¼ REF ¼ ¼ REF ¼ ¼ 7:6651, m ¼ 7:1194: 0:0854 0:0854 ξe3 ξe3

Homogeneous coordinates (4.12) of the point REF. ξREF ¼ 1

I REF 1:459 1 ¼ ¼ 0:6546, 2:229 I SC 1

¼ ξREF 2

I REF 1:602 2 ¼ ¼ 0:6079, 2:635 I SC 2

80

A. Penin and A. Sidorenko 2 I

ξREF 3

¼

I G2 2 I SC 2 I G2 2

þ

I REF 1 I G1 1

1

þ

I SC 1 I G1 1

1

1:602 15 ¼ 2:635 15

þ 1:459 0:7966 15:11  1 ¼ ¼ 1:177: 0:6768 þ 2:229  1 15:11

Non-uniform projective coordinates (4.13) mREF ¼ 1

ξREF ξREF 0:6545 0:6079 REF 1 2 ¼ 0:556, m ¼ ¼ 2 REF REF ¼ 1:177 ¼ 0:5164: 1:177 ξ3 ξ3

Interrelation (4.14) of the projective coordinates mREF ¼ 1 mREF ¼ 2

eREF m 1

eREF m 7:6651 1 ¼ ¼ 0:556, REF 7:6651 þ 7:1194  1 e2  1 þm

eREF m 1

eREF m 7:1194 2 ¼ ¼ 0:5164: 13:7842 eREF þm  1 2

Scale conductivities (4.16) REF Y G1 L1 ¼ Y L1

REF Y G2 L2 ¼ Y L2

mREF  1 0:556  1 1 ¼ 0:8, ¼ 0:556 mREF 1

mREF  1 0:5161  1 2 ¼ 0:9375: ¼ 0:5161 mREF 2

Axis I 1 equation (4.17) A01 I 4 þ B01 I 3 þ C01 ¼ 0:67I 4  0:309I 3  0:2585 ¼ 0;  I OC A01 ¼ I SC,OC 3 ¼ 3:309  2:639 ¼ 0:67, 3 SC,OC B01 ¼ I OC ¼ 1:603  1:912 ¼ 0:309, 4  I4 SC,OC OC SC,OC C01 ¼ I 3 I 4  I OC ¼ 4 I3

¼ 2:639  1:912  1:603  3:309 ¼ 0:2585: Axis I 2 equation (4.18) A02 I 4 þ B02 I 3 þ C 02 ¼ 0:486I 4  0:698I 3 þ 1:0629 ¼ 0; A02 ¼ I OC,SC  I OC 3 ¼ 3:125  2:639 ¼ 0:486, 3 OC,SC B02 ¼ I OC ¼ 1:603  2:303 ¼ 0:698, 4  I4 OC,SC OC OC,SC C02 ¼ I 3 I 4  I OC ¼ 4 I3

¼ 2:639  2:303  1:603  3:125 ¼ 1:0629:

4 Transmission of Two Measuring Signals by an Invariant Property of. . .

Straight line G2 G1 equation (4.19) A12 I 4 þ B12 I 3 þ C12 ¼ 0:184I 4 þ 0:389I 3  1:639 ¼ 0;  I SC,OC ¼ 3:125  3:309 ¼ 0:184, A12 ¼ I OC,SC 3 3 B12 ¼ I SC,OC  I OC,SC ¼ 1:912  2:303 ¼ 0:389, 4 4 C12 ¼ I SC,OC I 4OC,SC  I SC,OC I OC,SC ¼ 3 4 3 ¼ 3:3091  2:303  1:912  3:125 ¼ 1:639: Information conductivities (4.20) Y G1 0:8  0:3846 L1  Y S1 ¼ 0:5, ¼ 0:3846  1 Y S1  1 Y G2  Y S2 0:9375  0:2622 ¼ L2 ¼ 0:333: ¼ 0:2622  1 Y S2  1

Y L1 ¼ Y L2

Homogeneous projective coordinates (4.21) A I þ B02 I 3 þ C 02 ¼ ξe1 ¼ 02SC4 A02 I 4 þ B02 I SC 3 þ C 02 0:486  1:929  0:698  3:051 þ 1:0629 0:1291 ¼ ¼ ¼ 0:4935, 0:486  2:455  0:698  3:607 þ 1:0629 0:2616 A I þ B01 I 3 þ C01 ¼ ξe2 ¼ 01SC4 A01 I 4 þ B01 I SC 3 þ C 01 0:67  1:929  0:309  3:051  0:2585 0:0911 ¼ ¼ ¼ 0:3353, 0:67  2:455  0:309  3:607  0:2585 0:2717 A I þ B12 I 3 þ C 12 ξe3 ¼ 12SC4 ¼ A12 I 4 þ B12 I SC 3 þ C 12 0:184  1:929 þ 0:389  3:051  1:639 0:0972 ¼ ¼ ¼ 0:4504: 0:184  2:455 þ 0:389  3:607  1:639 0:2158 Non-uniform coordinates (4.22) e1 ¼ m

ξe1 ξe 0:4935 0:3353 e2 ¼ 2 ¼ ¼ 1:0957, m ¼ 0:7444: ¼ 0:4504 0:4504 e e ξ3 ξ3

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Transmitted signals (4.23) e1 1:0957 1:0957 m ¼ ¼ ¼ 0:3846, e2  1 1:0957  0:7444  1 2:8401 e1 þ m m e2 0:7444 0:7444 m ¼ ¼ 0:2622: ¼ ¼ e2  1 1:0957  0:7444  1 2:8401 e1 þ m m

Y S1 ¼ Y S2

The given example validates the proposed method.

4.5

Conclusion

The invariant relationship between regime parameters at the input and output of a communication line takes place. The offered choice of line parameters permits to introduce projective coordinates for the easily testable transmission system. Input projective coordinates allow finding load conductivities only by the measured input currents without running determination of the transmission parameters of this line. It allows transmitting signals over a communication line. The obtained results can be a basis for carrying out applied researches and developments; in particular, results can be generalized for AC lines.

References 1. Walker K, Ramplin M (2002) US Patent 6,459,363B1 2. Aldereguia A, Richter G, Williams J (2009) US Patent 7,502,991 B2 3. Ovchinnikov V (2013) US Patent 8,446,977B2 4. Ovchinnikov V (2005) RU Patent 2 250 566 5. Ovchinnikov V (2011) RU Patent 2 435 303 6. Penin A (2016) Analysis of electrical circuits with variable load regime parameters: projective geometry method. 2nd Ed. In: Springer international publishing AG 7. Penin A, Sidorenko A (2014) Transmission of measuring signals and power supply of remote sensors. In: Bonca J, Kruchinin S (eds) Nanotechnology in the security systems. NATO science for peace and security series C. Springer, Environmental Security, p 267 8. Penin A, Sidorenko A (2016) Transmission of three resistance sensor signals over four wire line with losses. In: Bonca J, Kruchinin S (eds) Nanomaterials for security. NATO science for peace and security series a. Springer, Chemistry and Biology, p 311 9. Frank JA (1967) Schaum’s outline of theory and problems of projective geometry. McGrawHill 10. Penin A, Sidorenko A, Donu S (2017) MD Patent application s 2017 0101

Chapter 5

IR-Sensors and Detectors of Irradiation Based on Metal Folis B. B. Banduryan, M. I. Bazaleev, V. F. Klepikov, V. V. Lytvynenko, V. E. Novikov, A. A. Golubov, and A. Sidorenko

Abstract It is proposed the simultaneous methods of treatment and control of potentially dangerous objects. Those methods are based on the prophylaxis irradiation and post irradiation IR-control. Keywords Radiation processing · Plastic explosive · Viruses · Low-contrast objects · Radiation – Induced heating

5.1

Introduction

One of the reasons of the modern world vulnerability is high organization and mass character of its industrial, commodity and transport lines. Unfortunately one of the most unsafely items is mail because of the following reasons: high speed of delivery, integration into the WorldNet, the sender’s actual anonymity, and identification of the addressee. To possible minuses of this channel usage for mailing items of provocative character is their restricted carrying capacity, therefore the subject of dangerous immersions can be, as it is already known, bacteria and viruses culture or plastic explosive, that took place even before the peak of terrorist activity.

B. B. Banduryan · M. I. Bazaleev · V. F. Klepikov · V. V. Lytvynenko · V. E. Novikov Scientific and Technological Center of Electrophysics National Academy of Scisssssence of Ukrain, Kharkiv, Ukraine A. A. Golubov University of Twente, Enschede, The Netherlands A. Sidorenko (*) D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia e-mail: [email protected] © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_5

83

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Reflecting on solution of the problem of possible dangerous immersions revealing and neutralization in mail items our author’s collective has turned to existing civil and special experience. In particular, we have turned to making of sterilization sections for considerable flows of disposable medical production and to detection and identification of objects by indirect temperature-contrasting points. With reference to a problem of mail items safety by our opinion these two methods can successfully supplement each other especially while using of modern developments in nanotechnologies. For preventive bactericidal treatment of mail items it is expedient to use the method of radiative sterilization, which is widely spread all over the world for processing of medical production. The value of the absorbed dose 15–25 kGr can kill the vital activity of pathogenic microorganisms. Estimated cost of such treatment can be received proceeding from the calculation that for processing of 15 kg of envelopes it is necessary to apply electric power equal to 1 KWatt
hour. Besides the preventive treatment there is also a problem of revealing of envelopes with suspicious immersions. Here we should return to values of the sterilizing absorbed doses of ionizing radiation. It is known, that at radiation passing through the substance the part of the absorbed energy is spent for temperature increasing of irradiated object. Thus the object absorbing ability depends on its density and geometrical sizes, in particular thickness of an immersing layer.

5.2

Decontamination and Control of Postoffice Message

The processing of mail is supposed to be made as well as in case of medical production by conveyor method (Fig. 5.1). Taking into account that we initially guess homogeneity of the processed massflow objects, which are in the area of irradiation, will immerse the radiation field with equal intensity and according to this their temperature will raise on some given quantity. If in a post envelope there is a unauthorized immersion (for example the plastic explosive), the radiation field will be immersed more intensively and the temperature on an irradiation zone output will differ from a background temperature. Radiation induce heating of polymers materials determined by the formula.

Fig. 5.1 The equipments for the post-office processing and control

Radiation screen irradiated object conveyer

Zone of irradiation

IR sensors

irradiated object irradiator

5 IR-Sensors and Detectors of Irradiation Based on Metal Folis

DE

85

5

3

2

Esec

1 WIR

Ein

4 6

Fig. 5.2 Method of thermal-and-vision control/measuring 1 – source of the accelerated electrons beam; 2 – beam of the accelerated electrons; 3 – the sounding screen for definition of irradiation doses (is erected in a frontal plane of the object irradiation zone); 4 – thermovisor; 5 – the sounding screen for definition of absorbed doses; 6 – irradiation object; Ein – energy of initial electrons; ΔE – energy of electrons absorbed by the screen; Esec – energy of electrons, past through the screen; WIR – energy of Infrared radiation

ΔT ¼

DE , c

ð5:1Þ

D – absorbed dose, кGr, c – heat capacity, кDj/(кgК), E energy, which adsorbed as result of chemical reactions. The task of revealing of object with boosted temperature and fixing of more intensive absorption of a radiation field appears. One more indication of the unauthorized immersion presence can be the change of a radiation field after passing through the irradiated object. For controlling of a radiation field it is offered to use the screen that is made of a thin foil. The change of a radiation flow also will cause a change of its surface temperature. The measuring of a screen temperature and irradiated objects is offered to be made with the help of an Infrared radiometer (Fig. 5.2). The temperature Ts – of the irradiated screen surface element ΔS can be determined guessing that the main losses are the losses on radiation in an Infrared range of a radiation spectrum, the value of which is defined by a Stefan-Boltzmann law. Under the steady conditions the energy of the accelerated electrons bundle immersing by the element S is equal to energy of Infrared radiation increase WIR concerning energy of an element radiation at a temperature of an external environment, i.e. at Ts ¼ Ten.
ΔE ¼ W IR ¼ εσ T 4s  T 4en ΔS:

ð5:2Þ

Temperature Ts of the irradiated surface element ΔS is defined from the expression.

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B. B. Banduryan et al.

T s ¼ ΔE=εσΔSir þ T 4en


1=4

,

ð5:3Þ

where Ten– temperature of an external environment, (К); ΔSir ¼ ΔS=2; ε – coefficient of screen surface irradiation; σ – Stefan-Boltzmann constant, (5,67. 108 Watt/m2 К4). The time of Ten establishment transient τtr is determined as. τtr ¼ ðT s  T en Þ=ΔT v ,

ð5:4Þ

where ΔT v ¼ ΔE=Cp Δm– speed of element temperature increase ΔS, (К/sec); Cp – heat capacity of screen substance (material), (J/kg К); Δm– element mass ΔS, (kg). It is possible to estimate the spatial (linear) resolution δsp of the method proceeding from calculation of temperature gradient ∇T that appears due to a difference of temperature between the element ΔS and contiguous to it screen surface, and values of temperature sensitivity Tw and thermovisor linear resolution δsp: ∇T ¼ q=λ ¼ ΔE=λlp d,

ð5:5Þ

where q ¼ ΔE/ΔSp; λ – screen substance heat conductivity, (Watt/m К); q – heat flow density, (Watt/m2); ∇T – temperature gradient along the screen surface, (К/m); ΔSp ¼ lpd, ΔSp – element profile area ΔS on its perimeter, (m2); lp – element perimeter ΔS. For ΔS that is a quadrate with the side l under condition of ∇Tl ¼ Tw and l > δsp, δsp ¼ T w =∇T

ð5:6Þ

The value (density) of radiation energy Ein that effect on the element ΔS is determined by the measuring data of the element temperature Ts: E in ¼ T s =f ðΔS, ΔE, p1 , p2 Þ

ð5:7Þ

where f(ΔS, ΔE, p1, p2, . . .)– function (coefficient) of element radiation temperature conversion ΔS to the energy characteristics of the electrons bundle influencing on ΔS; p1, p2, . . .– functional parameters of the sounding screen pointing out on its thermal-and-physical, radiation and constructional characteristics.

5.3

Method Sensitivity Estimation

The dependence of screen element temperature increase ΔS from absorbed energy ΔE and screen irradiation coefficient ε, which is calculated by formula (2), is shown on Fig. 5.3. The ultimate value of depending on value of ε, Fig. 5.3.

5 IR-Sensors and Detectors of Irradiation Based on Metal Folis 4 ,0

lgD T э.10

87

e =0,7 e=0,15 e=0,35

4

3 ,5

(100K) 3 ,0 73K

2 ,5 (10K) 2 ,0

1 ,5 (1K) 1 ,0

0 ,5 0 ,0 0 ,0 -4

(10 вт)

D Emax =0,08вт

D Emax=0,02вт

0 ,5

1 ,0 -3

(10 вт)

1 ,5

2 ,0 -2

(10 вт)

2 ,5

3 ,0 -1

(10 вт)

3 ,5

4 ,0

lg D E .10

4

Fig. 5.3 Dependence of screen element temperature increase ΔS from the absorbed energyΔE (at Ten ¼ 300K ).). ΔEmax< (2 . 102  8 . 102) Watt/sm2 – the area of maximum values of the absorbed energy (depends on value ε of the screen), at which the screen element temperature  achieves 373 К (~100 С)

In a Fig. 5.4 the calculation data δsp of the sounding screen made of a foil with a thickness of 10 microns for various metals (Fe; Al; Cu; corrosion-proof steel 10X18H9TЛ10-4) are given. From the diagrams we can see that, for example, for maintenance of δsp  3 mm the absorbed energy lower threshold ΔEmin should be not less than (2.4 . 104  6 . 103) Watt/sm2 for the specified materials. Usage of thinner foils and alloys of iron, aluminum, copper, aluminumated polymeric (lavsan) film that have small values of a thermal conductivity λ allows to increase the resolving ability δsp up to 100 microns. The estimation of the electrons energy measuring Ein ratio error ξЕ can be made proceeding from a selection of an optimum range of screen temperature values Ten, in the limits of which the minimum value of the ratio error of temperature ξТ measuring is provided. For values Ten ¼ (310  350)К, Ten¼ 300 К, and Tw ¼0,1К, at a level of the absorbed energy ΔE¼ 5.103 Watt/sm2, the error of taking temperature ξТ is (0,2  1)%, that meets the measuring of the absorbed energy with precision of (105 . 5.105) Watt/sm2. At maintenance of stability of (electrons) absorption coefficients and radiation (Infrared radiation) of the sounding screen the estimation of the ratio error ξЕ of electrons energy measuring Ein can be made based on a selection of an optimum range of screen temperature values Ten, in the limits of which the minimum value of temperature measuring ratio error ξТ is provided. Under the above-mentioned conditions the ratio error ξЕ of electrons energy measuring Ein can be equal to ~0,5%.

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B. B. Banduryan et al.

6 lgd . 10

l

5,5 5,0

Cu

4,5

Al

-2

(10 м) 4,0

-3 3.10 м

3,5

Fe

-3

(10 м) 3,0 10Х18Н9ТЛ

2,5 -4

(10 м) 2,0

1,5 -5

(10 м) 1,0

0,5 -6

(10 м)

DEmin= 2,4 . 10 вт -4

0,0 0,0 -4

(10 вт)

0,5

1,0 -3

(10 вт)

DEmin = 6.10 вт -3

1,5

2,0 -2

(10 вт)

2,5

3,0

lg D E. 10

4

Fig. 5.4 Dependence of spatial (linear) resolution δsp of the method from the sounding screen substance (Сu; Al; Fe; alloy 10Х18Н9ТЛ). Ten ¼ 300K; screen thickness d ¼ 105 m; ΔEmin> (2.4 . 104  6 . 103) Watt/sm2 – the lower threshold of the absorbed energy value ΔEmin, at which δsp < 3.103 m

5.4

Conclusion

It is proposed the simultaneous methods of treatment and control of potentially dangerous objects. This methods are based on the prophylaxis irradiation and post irradiation IR-control. Acknowledgments The work has been supported by National Academy of Science of Ukraine, by the National Research Program of Moldova, Project 15.817.02.16F Supraconductibilitatea neuniformă ca bază a spintronicii supraconductoare, and EU SPINTECH project, Grant Agreement Nr. 810144.

References 1. Gonchar VK, Banduryan BB (2004) Control measurement devices and automatic, No 3, pp 4–10 2. Bazaleev MI, KLepikov VF, Banduryan BB (2003) Problems of atomic science and technology, No 3, pp 146–150 3. Sidorenko A, Zasavitchi E (2007) RM Patent no. 3436 of 30.11

Chapter 6

Magnetoelectric Effect Driven by Reversible Surface Chemistry and Bulk Ion-Exchange A. Molinari, S. Dasgupta, R. Kruk, and H. Hahn

Abstract Electric-field control of magnetism is presently among the most thriving research areas. However, in artificial, interface-controlled magnetoelectrics electric field is efficiently screened within a few monolayers of surface atoms, thus severely limiting the magnitude of magnetoelectric coupling. To strengthen magnetoelectric phenomenon at the interface it is proposed here to use either reversible surface chemistry or reversible bulk ion-exchange as tools to control magnetization response. The expected advantages are twofold; firstly, a complete on-and-off magnetism can be foreseen even for strong ferromagnets; secondly, the concept can go beyond the simple electrostatic charging at the surface/interface. The idea stems from supercapacitors and rechargeable batteries where reversible chargingdischarging has been demonstrated for thousands of cycles. Keywords Magnetoelectric coupling · Supercapacitors · Magnetoelectric effect · Magneto-ionics · Nanostructures

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Introduction

In recent times the idea of reversibly controlling magnetism by the application of an electric field – i. e. upon regulation of an external voltage – has attracted the interest of an ever-growing number of researchers belonging to the diverse scientific A. Molinari · S. Dasgupta · R. Kruk (*) Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany e-mail: [email protected] H. Hahn Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany KIT-TUD Joint Research Laboratory Nanomaterials, Institute of Materials Science, TU Darmstadt, Darmstadt, Germany e-mail: [email protected] © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_6

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communities [1]. From a practical perspective, the replacement of the conventional usage of a magnetic field with an electric field may bring to a substantial reduction in the power consumption of microelectronic devices for applications [2] such as memory storage, signal processing, transduction and actuation. In this respect, a powerful approach [3] consists in realizing a hybrid device composed of a magnetic electrode in contact with an electrolyte solution. The magnetoelectric effect (ME) can be realized either at the surface or within the bulk of the magnetic electrode. In the first scenario upon application of an external voltage the ions of the electrolyte migrate onto the surface of the magnetic electrode and induce the accumulation/depletion of charge carriers, akin to the charging/discharging processes of a conventional electrolytic capacitor. The change in charge carrier density can be exploited to reversibly manipulate the magnetic properties of the magnetic electrode. The complex nature of the charging/discharging processes at the electrode/electrolyte interface is still a matter of ongoing research from both fundamental and experimental perspectives. It is not straightforward to identify whether the charge carriers are accumulated via purely electrostatic (as in electric double layer (EDL) capacitors [3]) or electrochemical mechanisms (as in pseudocapacitors [5]). Recent studies [4, 6] indicate that a combination of both mechanisms may occur at oxide/ electrolyte interfaces depending on the applied voltage and operating temperature. A step further, beyond the surface charging and chemistry, can be made when one allows for the charge transfer across the interface. In such a case the ions, in a way analogous to a charging battery, can be cyclically inserted and then extracted from the functional magnetic material leading to the creation of the volume, and therefore very strong, ME or, in other words, magneto-ionic effect. Moreover, aiming at a complete on-and-off magnetic switching, reversible ion-exchange processes can be utilized as a tool to annihilate magnetism, completely, in bulk ferromagnets or to create magnetism in non-magnetic systems. In the following we describe two examples of the surface and bulk chemistry driven ME effect. The first one describes a prototypical system composed of ferromagnetic thin films (
13 nm) of La0.74Sr0.26MnO3 (LSMO) in contact with an ionic liquid (IL) electrolyte (diethylmethyl(2-methoxyethyl)ammonium bis (trifluoromethylsulfonyl)imid, DEME-TFSI). The second one presents the magneto-ionic mechanism in iron spinel γ-Fe2O3 by using 1 M LiPF6 dissolved in ethylene carbonate (EC) and diethyl carbonate (DEC) as the electrolyte.

6.2

Experimental

LSMO thin films were grown by means of magnetron sputtering at a temperature of about 650  C and an oxygen pressure of 0.018 mbar. After deposition the films were annealed in a tube furnace for 1 h at 900  C in air in order to reduce the amount of oxygen deficiencies. For the measurements of the ME effect a tuning cell (see Fig. 6.1a) was designed with the LSMO film and a high surface area carbon cloth used as working and counter electrodes, respectively. An insulating glass fiber

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Fig. 6.1 Sketch of the LSMO/IL devices (a) and example of a typical ME experiment at 323 K (b). Figure 6.1 Reprinted from Ref. [4]

infiltrated with DEME-TFSI ionic liquid was utilized as separator to avoid short circuiting between the two electrodes. The ME apparatus was realized by combining in situ cyclic voltammetry and superconducting quantum interference device (SQUID) magnetometry. Further details about the growth and characterization of LSMO thin films and the experimental setup implemented for analyzing the interfacial ME coupling can be found elsewhere [4, 6]. Single-phase spinel iron oxide (γ-Fe2O3) nanoparticles [7], were synthesized by a wet-chemical precipitation method at a temperature of 90  C. An electrochemical cell analogous to a Li-ion battery was built, with the magnetic electrode composed of γ-Fe2O3 nanoparticles, as cathode, and pure Li metal as anode, so as to have small and high mobility Li ions as the representative non-magnetic species that could be reversibly intercalated. The ME experiments were performed in a physical property measurement system (PPMS) magnetometer during galvanostatic charging/ discharging processes.

6.3

Results and Discussion

The results of a ME experiment carried out on a LSMO/IL device at room temperature are shown in Fig. 6.1b. The external voltage (black curve) applied between working and counter electrodes is linearly and repeatedly ramped in a range of about 400 mV. The current (green curve) flowing towards the LSMO working electrode is monitored and by its integration the charge (blue curve) accumulated at the interface

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Fig. 6.2 Behavior of LSMO magnetization at different temperatures for a constant charge modulation ΔQ
4 μC cm2 (a) and at a fixed temperature T
220 K as a function of increasing ΔQ (b). The plot in the bottom of (b) refers to an experiment performed by setting an initial bias voltage of Vb ¼ 1.3 V. White and grey colors indicate the regions where magnetic and charge responses are in-phase or anti-phase, respectively. Each time step in the x-axis corresponds to 500 s in (a) and 800 s in (b). Figure 6.2 adapted from Ref. [4]

can be calculated. The experiment reveals that the LSMO magnetic response (red curve) reversibly follows the charge modulation with a relative variation in magnetization of about 4%. Once the external voltage is removed, the magnetization recovers its initial value. The perspective of tuning the magnetization by application of a low power voltage can be further examined by studying the behavior of the LSMO/IL ME devices under various operating conditions. Figure 6.2a displays the behavior of the LSMO magnetization at different temperatures under application of a constant surface charge modulation ΔQ
4 μC cm2. Notably, although the applied charge is constant, the magnetic response is completely different when the temperature is varied. At 323 K the magnetization decreases (increases) upon electron (hole) doping, thus resulting in an in-phase ME response. At a lower temperature of 258 K, the charge modulation does not cause any substantial variation of the LSMO magnetization. Upon further reduction of the temperature down to 220 K the magnetization and the charge turn to anti-phase conditions.

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Fig. 6.3 Current-voltage characteristics of the charge dependence study performed at 220 K showing the transition from EDL to pseudocapacitive (PS) behavior. Figure 6.3 Adapted from Ref. [4]

Another analysis of interest consists in monitoring the magnetization at a fixed temperature upon progressive increase of the external voltage, corresponding to inducing larger and larger charge carrier doping of LSMO. Figure 6.2b shows the ME tuning results at a temperature of 220 K. Initially, for moderate charge doping, magnetization and charge are in anti-phase, in accordance with the results presented above. Nonetheless, at a certain point the magnetization reveals the onset of a splitting, which becomes more and more pronounced as the electron concentration is further increased. Such splitting is accompanied with an in-phase behavior of the magnetic and charge responses. In addition, by setting the experiment with respect to an initial bias voltage Vb ¼ 1.3 V, it is found that magnetization and charge turn immediately in-phase, similarly to the results attained in Fig. 6.2a at the high temperature of 323 K. Both temperature and charge-dependence surveys, whose interpretation has been comprehensively examined elsewhere [4], prove that the process of tuning of magnetization via electrolyte gating is not only highly reversible, but also extremely flexible, because it allows to freely manipulate the sign of the ME modulation. The analysis of the charging/discharging cycles (see Fig. 6.3) of the charge dependence study at 220 K revealed that for moderate voltages the current-voltage curves exhibited the typical features of an EDL capacitor. Upon progressive increase of the external voltage the current-voltage curves were still reversible although not anymore rectangular, thus indicating the presence of pseudocapacitive behavior. These outcomes point out that the process of surface charge carrier doping of LSMO, and so also the control of the ME effect, shifts from electrostatic to electrochemical on increasing the potential window [4]. The ME coupling phenomena were also investigated in ultrathin LSMO films [6] with a thickness of only 3 nm. In this case, owing to the enhanced surface-to-volume

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ratio of LSMO and the intrinsic interfacial nature of the ME coupling, a complete suppression and recovery of the magnetization was achieved at a maximum temperature of 235 K. The voltage switching speed of the devices was another figure of merit put to test. It was found that on/off switching of magnetism can be accomplished up to a voltage frequency of 0.1 Hz. Although the attained operating temperatures and frequencies are not yet adequate for concrete applications, there is still room for improving the performance of the ME effect, for instance by optimizing the device geometry and considering other possible electrode/electrolyte combinations. In case study of the magneto-ionic approach with γ-Fe2O3 as an intercalationfriendly and robustly ferromagnetic functional material ME measurements were done in situ in the PPMS magnetometer, while discharging (lithium insertion) and charging (lithium extraction) the electrochemical cell within the cut-off potentials between 1.1 V and 3.5 V, respectively. The experiment revealed a highly reversible variation of magnetization [7]. In fact, after completion of each charging cycle at an upper cut-off potential of 3.5 V, the measured magnetization of the delithiated sample was absolutely identical to the as-prepared magnetic electrode validating the full reversibility of the process [7]. The overall electrochemical reactions occurring at the respective electrodes during the intercalation/de-intercalation processes thus can be summarized as follows: at cathode: γ-Fe2O3 + xLi+ + xe- $ LixFe2O3; at anode: Li $ (1-x)Li + xLi+ + xe(when, x mole of Li ions are considered to be intercalated or de-intercalated). To elucidate the mechanism behind the strong response of the magnetization to the Li charging, at every critical lithiation state, the total magnetization with the charge states of the Fe ions (here, it also means Fe spin states) were correlated. The as-prepared magnetic electrode Fe2O3 was composed of Fe3+ valence state, both in the octahedral and tetrahedral sites. Upon Li-ion insertion in the magnetic lattice chemical reduction of a large fraction of the octahedral Fe3+ to Fe2+ took place. The chemical reduction of this quite large number of the octahedral Fe ions, from the high-spin Fe3+ (5 μB) to the high-spin Fe2+ (4 μB) state reduced the octahedral magnetic component which, being the stronger counterpart, considerably diminished the net magnetic moment, as shown in Fig. 6.4. Indeed, a total variation in bulk magnetism of the magnetic electrode of around 30% was recorded during cyclic intercalation-deinitercalation processes [7]. Even stronger magnetic response has been measured in judiciously chosen CuFe2O4 and ZnFe2O4 spinels reaching 50% and 70%, respectively [8].

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Fig. 6.4 Schematic representation of the rationale behind the observed intercalationdriven magnetization variation in iron oxide spinel. Each inserted lithium ion donates one electron to the octahedral iron ions resulting in a chemical reduction from Fe+3 to Fe+2 states. Alongside a decrease in the net magnetic moment results from a decrease in the octahedral spin states considering that the tetrahedral spin remain unchanged

6.4

Conclusion

Two illustrative examples of robust ME coupling were shown via application of reversible surface chemistry and bulk ionic intercalation. LSMO thin films gated by the ionic liquid featured high reliability, very strong ME coupling and quite promising charging speed characteristics. Magneto-ionic approach to realization of the reversible volume ME effect was demonstrated for Fe spinel oxides. To date, the efforts of the ME community to push the phenomenon of ME effect to the limits has led to encouraging results, which keep fostering intensive research activities. Nonetheless, the realization of a working ME device, which concurrently fulfills on/off magnetization switching, low-power consumption, reversibility, fast response and room temperature operation, remains still an open quest.

References 1. Matsukura F, Tokura Y, Ohno H (2015) Control of magnetism by electric fields. Nat Nanotechnol 10:209 2. Wood VE, Austin AE (1974) Possible applications for magnetoelectric materials. Int J Magn 5 (4):303 3. Weisheit M, Fähler S, Marty A, Souche Y, Poinsignon C, Givord D (2007) Electric field-induced modification of magnetism in thin-film ferromagnets. Science 315:349 4. Molinari A, Leufke PM, Reitz C, Dasgupta S, Witte R, Kruk R, Hahn H (2017) Hybrid supercapacitors for reversible control of magnetism. Nat Commun 8:15339 5. Conway BE (1991) Transition from “Supercapacitor” to “Battery” behavior in electrochemical energy storage. J Electrochem Soc 138:1539

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6. Molinari A, Kruk R, Hahn H (2018) Voltage-controlled on/off switching of ferromagnetism in manganite supercapacitors. Adv Mater 30:1703908 7. Dasgupta S, Das B, Knapp M, Brand RA, Ehrenberg H, Kruk R, Hahn H (2014) Intercalationdriven reversible control of magnetism in bulk ferromagnets. Adv Mater 26:4639 8. Dasgupta S, Das B, Li Q, Wang D, Baby TT, Indris S, Knapp M, Ehrenberg H, Fink K, Kruk R, Hahn H (2016) Toward on-and-off magnetism: reversible electrochemistry to control magnetic phase transitions in spinel ferrites. Adv Funct Mater 26:7507

Chapter 7

Antiferromagnetic-to-Ferromagnetic Transition in FeRh Thin Films with Strain Induced Nanostructure R. Witte, R. Kruk, D. Wang, R. A. Brand, and H. Hahn

Abstract The formation of a magnetic nanostructure is reported in FeRh thin films showing the antiferromagnetic-to-ferromagnetic (AF-to-FM) transition known from the B2 ordered equiatomic phase. The magnetic nanostructure is formed due to a certain epitaxial strain-adaption process, leading to phase separation into a ferromagnetic and a paramagnetic phase. An additional post-annealing step finally creates the high degree of chemical ordering in the cubic phase needed to establish the AFM ground state and the AF-to-FM transition, as seen by SQUID magnetometry and 57 Fe conversion electron Mössbauer spectroscopy. Keywords FeRh · Magnetic nanostructures · Conversion electron Mössbauer spectroscopy (CEMS) · Epitaxial strain

R. Witte · R. Kruk Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany D. Wang Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, EggensteinLeopoldshafen, Germany R. A. Brand Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University Duisburg-Essen, Duisburg, Germany H. Hahn (*) Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), EggensteinLeopoldshafen, Germany KIT-TUD Joint Research Laboratory Nanomaterials, Institute of Materials Science, TU Darmstadt, Darmstadt, Germany e-mail: [email protected] © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_7

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Introduction

The equiatomic and B2 ordered FeRh alloy (CsCl structure) started to attract vast scientific interest after the report of an isostructural metamagnetic transition from an antiferromagnetic (AFM) to a ferromagnetic (FM) state at about 350 K by Fallot [1, 2]. Numerous experimental approaches have focused on tailoring and modifying the occurrence of this transition by employing e.g., ternary alloying [3–5] or applied external constraints such as magnetic field [6–8], strain mediated magnetoelectric coupling [9, 10] or pressure [11–13]. In order to make the material applicable in various different contexts, the most important are magnetocaloric cooling [14, 15] and novel, innovative magnetic data storage concepts [16, 17]. Especially the latter application requires an enhanced degree of miniaturization of the structures; therefore, attempts have been made to decrease the feature size of FeRh nanostructures. FeRh nano-composites have been produced by alloying and subsequent annealing [18, 19]. The annealing of FeRh thin films on oxide substrate results in the formation of substrate-supported nanoparticles [20, 21], while the direct synthesis of FeRh nanoclusters is possible via physical [22] or chemical routes [23]. However, in all of these studies the desired AF-to-FM transition was not, or only partially observed. An alternate approach for the bottom-up synthesis of magnetic nanostructures is making use of intrinsic instabilities of the crystal lattice which can lead to the formation of nano-twinned structures in strained epitaxial films [24]. Such a nanotwinned structure has been recently reported in highly strained thin films of a chemically disordered FeRh alloy [25]. Yet the resulting martensitic structure, crystallizing in the orthorhombic space group Cmcm, behaves paramagnetically (PM) down to low temperatures. By carefully adjusting the epitaxial strain, using different W-V alloys as buffer layers, and by increasing the growth temperature to 300
C the strain adaption mechanism can be modified. Now it leads to the formation of a two-phase nanostructure, consisting of a partially B2 ordered FM phase and the PM Cmcm phase, which self-assemble laterally in the films [26]. Due to the intrinsic nature of the strain-adaption mechanism, it is possible to fine-tune the relative ratios of the two phases, with the buffer layer lattice constant, i.e. strain. However the magnetic nanostructures which were presented in this recent publication [26] showed only the presence of a FM and a PM phase, while no AF-to-FM transition was observed. This is related to the rather moderate growth temperatures used in the study which do not establish the high degree of chemical B2 order which is crucial to obtain the AF magnetic ground state [27]. Antisite defects, e.g. Fe atoms on Rh sites couple ferromagnetically to their nearest Fe neighbors along the [111] direction, effectively destroying the subtle balance between FM coupling between Fe-Rh nearest and AF coupling between Fe-Fe next nearest neighbors [28]. Yet it is exactly this balance, which is responsible for the temperature induced AF-to-FM transition.

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In the present study, we show that the AF-to-FM transition can be achieved in these nanostructures by moderately post annealing a FeRh film with perfect equiatomic composition, which is grown on a WV buffer layer (e.g. in the two-phase region). A combined structural, microscopic, magnetometric and Mössbauer spectroscopic investigation evidences the presence of the AF-to-FM transition, while the initial nanostructured character of the sample is preserved [29]. These results pave the way for a further miniaturization and down-scaling of the magnetic bit size in the novel magnetic data storage concepts based on the AF-to-F; transition, such as the antiferromagnetic memory resistor [16, 17] or thermally assisted magnetic recording [30–32].

7.2

Experimental

The 50 nm thick W-V buffer layer was co-deposited by dc-magnetron sputtering on epipolished MgO(001) single crystal substrates (SurfaceNET) with a growth rate of ~0.010 nm/s at 350
C at an Ar pressure of 0.0011 mbar. The 57FeRh thin film of 10 nm thickness was deposited at a substrate temperature of 300
C by using a Mini-electron-beam evaporator (Oxford applied research). The film was oxidation protected with a 1 nm Rh capping layer. The post annealing step was performed under high vacuum of 5108 mbar at 500
C for 90 min. The compositions of both layers were determined with energy-dispersive X-ray spectroscopy (EDX) to be equiatomic. High resolution x-ray diffraction (HRXRD) measurements were performed with a Bruker D8 four-circle diffractometer, equipped with a Goebel mirror and a 4-bounce Ge(022) monochromator resulting in CuKα radiation (0.154056 nm). 57Fe conversion electron Mössbauer spectroscopy (CEMS) was measured in a custom-built proportional counter. Scanning tunneling microscopy (STM) investigations were performed in-situ under ultra-high vacuum conditions with an OMICRON VT STM. Magnetic characterization was performed with a Quantum design MPMS3 SQUID VSM. For the measurements exceeding 400 K the Quantum design SQUID oven was applied and the furnace data was merged with the normal data at 300 K.

7.3

Results and Discussion

In the following, the sample in the as-prepared condition will be compared with the annealed state. The structural investigation with HRXRD presented in Fig. 7.1 shows the presence of several structural phases. The most intense reflection at 59
can be attributed to the (002) planes of the WV buffer layer, while the intensity maxima at 64 and 68
are assigned to the cubic B2 phase and the Cmcm phases respectively. The reflection at 31
is the (001) superstructure reflection of the B2 phase, stemming from the chemical ordered structure. However, after annealing, the

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Fig. 7.1 Influence of post-annealing on the crystalline structure. HRXRD patterns for a FeRh on a WV buffer layer, in the as prepared and annealed state, after 90 min post-annealing at 500
C. The observed reflection can be assigned to the WV buffer layer and the two FeRh phases, namely the B2 ordered and the chemically disordered Cmcm phase Fig. 7.2 Influence of postannealing on the magnetic properties. Temperature dependent magnetization curves measured in between 100 and 400 K for the as prepared and annealed state in a constant magnetic field H ¼ 50 mT respectively

sample diffraction pattern was not significantly changed, except for a small increase in area of the super-structure reflection, due to increased B2 ordering. The small change on the shoulder of the WV reflection (only visible due to the log scale of the plot) might be well due to some interface alloying or strain relaxation effects in the buffer layer. The X-ray structural analysis thus indicates that the structure, which includes also the strain-induced nanostructure, is thermally stable up to the used annealing temperature. However, the more sensitive probe for the increase of the B2-ordering in the FeRh thin film is the observed magnetic behavior, crucially depending on the concentration of Fe antisite defects, as detailed above. Temperature dependent magnetization curves are presented in Fig. 7.2. Already in the as-prepared state signs of the AF-FM transition are visible. This is evidenced by the increase of magnetization with temperature above 200 K. Yet, the transition appears smeared out and the sample shows considerable remaining magnetization at low temperature, due to the imperfect B2-ordering in the as-prepared state effectively suppressing the subtle AF order in a large volume of the sample. The post-annealing step results in an

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Fig. 7.3 RT-CEMS spectra of the two states each fitted with a single line (dashed) and a magnetic sextet (dotted). The arrows indicate the position of the second and fifth line, which drastically change their relative intensity, due to a spin reorientation

AF state at 300 K and below (the increase at temperatures below 10 K is attributed to the paramagnetic impurities in the MgO substrate [33]), while the magnetization steeply increases with temperature as expected for the AF-to-FM transition [7]. One may also note that the onset of transition is shifted to higher temperatures, which is a clear indication of the stabilization of the AF ground state at these elevated temperatures. 57 Fe CEMS provides a local spectroscopic view on the two states, the data is presented in Fig. 7.3. The as prepared film shows a spectrum which needs to be represented with at least two subcomponents, a PM singlet and a magnetic sextet. The PM singlet can be safely attributed to the Cmcm phase [25], while the magnetically split sextet shows very broad lines indicating structural but possibly also magnetic disorder. The spectrum is not unambiguously reproducible, a tentative fit is using a singlet and a magnetic sextet with Gaussian broadening, but however the most important change upon post-annealing is visible with the bare eye. The relative areas between line pairs (2 and 5) and (3 and 4) of the sextets, change drastically from one state to another, which indicates a variation of preferred orientation of the magnetic moments. For the as-prepared state, lines 2 and 5 are present (arrows), hence the ratio between (2 and 5) to (3 and 4) is about 3.4 found by fitting with a Gaussian broadened sextet. This indicates a spin arrangement between nearly random and in-plane [34]. However, in the spectrum of the post-annealed sample the lines 2 and 5 are hardly observable (again fitted with a broadened sextet yields a ratio of 0.6), pointing to a spin reorientation towards an out-of-plane orientation, due to a strong magneto-crystalline anisotropy in the AF state. This is in agreement with previous reports: Bordel et al. have shown that slightly tetragonal distorted grown FeRh film (with a c/a ¼ 0.985) possess an out-of-plane

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spin arrangement in the AF phase [35]. As a strain-induced tetragonal distortion with c/a < 1 in the B2 phase is found also in the present sample, the observed spin reorientation represents spectroscopic evidence for the occurrence of the AF state and effectiveness of the annealing procedure. The spectral area ratios of the magnetic and paramagnetic subspectra remain about constant upon annealing, supporting the claim based on HRXRD results, that the nanostructure is basically unharmed by the temperatures treatment.

7.4

Conclusion

The fabrication of a self-assembled magnetic nanostructure was presented, that features the AF-to-FM transition known from the B2 ordered FeRh bulk alloy. The method thus displays an elegant and controlled way to down-scale the magnetic bit size for applications in several novel data storage concepts [16, 17, 30–32] based on the AF-to-FM transition. These findings are especially remarkable as the previous reports in the literature dealing with nanometer-sized structures suffer from uncompleted transition, or low temperature FM phases [19, 22, 23, 36]. The transition temperature itself may be readily adjusted to more application suitable temperatures by the well-known tailoring approaches using e.g. ternary alloying with Co or Pd [3, 5].

References 1. Fallot M (1938) Ann Phys 10:291 2. Fallot M, Horcart R (1939) Rev Sci 77:498 3. Walter PHL (1964) J Appl Phys 35:938 4. Kouvel JS (1966) J Appl Phys 37:1257 5. Barua R, Jiménez-Villacorta F, Lewis LH (2013) Appl Phys Lett 103:102407 6. McKinnon JB, Melville D, Lee EW (1970) J Phys C Solid State Phys 3:S46 7. Maat S, Thiele J-U, Fullerton EE (2005) Phys Rev B 72:214432 8. Ohtake K, Mitsui Y, Takahashi K, Onodera R, Kimura S, Watanabe K, Koyama K (2014) IEEE Trans Magn 50:1001404 9. Cherifi RO, Ivanovskaya V, Phillips LC, Zobelli A, Infante IC, Jacquet E, Garcia V, Fusil S, Briddon PR, Guiblin N, Mougin A, Ünal AA, Kronast F, Valencia S, Dkhil B, Barthélémy A, Bibes M (2014) Nat Mater 13:345 10. Fina I, Quintana A, Padilla-Pantoja J, Marti X, Macià F, Sanchez F, Foerster M, Aballe L, Fontcuberta J, Sort J (2017) ACS Appl Mater Interfaces 9(18):15577–15582 11. Wayne R (1968) Phys Rev 170:523 12. Kamenev K, Arnold Z, Kamarád J, Baranov NV (1997) J Alloys Compd 252:1 13. Stern-Taulats E, Planes A, Lloveras P, Barrio M, Tamarit J-L, Pramanick S, Majumdar S, Frontera C, Mañosa L (2014) Phys Rev B 89:214105 14. Liu J, Gottschall T, Skokov KP, Moore JD, Gutfleisch O (2012) Nat Mater 11:620 15. Liu Y, Phillips LC, Mattana R, Bibes M, Barthélémy A, Dkhil B (2016) Nat Commun 7:11614

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16. Marti X, Fina I, Frontera C, Liu J, Wadley P, He Q, Paull RJ, Clarkson JD, Kudrnovský J, Turek I, Kuneš J, Yi D, Chu J-H, Nelson CT, You L, Arenholz E, Salahuddin S, Fontcuberta J, Jungwirth T, Ramesh R (2014) Nat Mater 13:367 17. Moriyama T, Matsuzaki N, Kim K-J, Suzuki I, Taniyama T, Ono T (2015) Appl Phys Lett 107:122403 18. Barua R, Jiang X, Jimenez-Villacorta F, Shield JE, Heiman D, Lewis LH (2013) J Appl Phys 113:23910 19. Kaeswurm B, Jimenez-Villacorta F, Bennett SP, Heiman D, Lewis LH (2014) J Magn Magn Mater 354:284 20. Ayoub JP, Gatel C, Roucau C, Casanove MJ (2011) J Cryst Growth 314:336 21. Loving M, Jimenez-Villacorta F, Kaeswurm B, Arena DA, Marrows CH, Lewis LH (2013) J Phys D Appl Phys 46:162002 22. Dupuis V, Robert A, Hillion A, Khadra G, Blanc N, Le Roy D, Tournus F, Albin C, Boisron O, Tamion A (2016) Beilstein J Nanotechnol 7:1850 23. Ko HYY, Suzuki T, Phuoc NN, Cao J (2008) J Appl Phys 103:07D508 24. Kauffmann-Weiss S, Gruner ME, Backen A, Schultz L, Entel P, Fähler S (2011) Phys Rev Lett 107:206105 25. Witte R, Kruk R, Gruner ME, Brand RA, Wang D, Schlabach S, Beck A, Provenzano V, Pentcheva R, Wende H, Hahn H (2016) Phys Rev B 93:104416 26. Witte R, Kruk R, Molinari A, Wang D, Schlabach S, Brand RA, Provenzano V, Hahn H (2017) J Phys D Appl Phys 50:25007 27. Staunton JB, Banerjee R, Dias M d S, Deak A, Szunyogh L (2014) Phys Rev B 89(54427) 28. Kudrnovský J, Drchal V, Turek I (2015) Phys Rev B 91:14435 29. Witte R (2016) Strain Adaption in Epitaxial Fe-Rh Nanostructures, Dissertation, Technische Universität Darmstadt 30. Thiele J-U, Maat S, Fullerton EE (2003) Appl Phys Lett 82:2859 31. Jia Z, Misra RDK (2011) Mater Technol 26:200 32. Lounis L, Spezzani C, Delaunay R, Fortuna F, Obstbaum M, Günther S, Back CH, Popescu H, Vidal F, Sacchi M (2016) J Phys D Appl Phys 49:205003 33. Orna J, Morellón L, Algarabel PA, De Teresa JM, Fernández-Pacheco A, Simón G, Magen C, Pardo JA, Ibarra MR (2010) Adv Sci Technol 67:82 34. Gütlich P, Bill E, Trautwein AX (2011) Mössbauer spectroscopy and transition metal chemistry. Springer Berlin Heidelberg, Berlin 35. Bordel C, Juraszek J, Cooke DW, Baldasseroni C, Mankovsky S, Minár J, Ebert H, Moyerman S, Fullerton EE, Hellman F (2012) Phys Rev Lett 109:117201 36. Barua R, McDonald I, Jiménez-Villacorta F, Heiman D, Lewis LH (2016) J Alloys Compd 689:1044

Chapter 8

Thermally and Stress Induced Phase Transformations and Reversibility in Shape Memory Alloys O. Adiguzel

Abstract Shape memory alloys take place in class of functional materials due to the sensitivity to the external conditions and memory behavior and shape changes are governed by successive thermally and stress induced martensitic transformations in crystallographic level. Shape memory effect is performed on cooling by means of thermal induced martensitic transformation and stressing in the low temperature product phase region by means of stress induced martensitic transformation. Following these processes, shape memory materials cycle between original and deformed shapes on heating and cooling, by means of reverse and forward thermal induced transformations. Mechanical memory is performed only mechanically in a constant temperature in the parent phase region, on stressing and releasing. This behavior is called superelasticity, which exhibits classical elastic material behavior, but stressing and releasing paths follow different paths in stress-strain diagrams. The hysteresis loop refers to the energy dissipation, and these alloys are mainly used as deformation absorbent materials in the buildings, due to the absorbance of strain energy during any disaster or earthquake. Thermal induced martensite occurs as twinned martensites by means of lattice invariant shears on close packed planes of parent structure, and the twinned martensites turn into detwinned structures with deformation by means of stress induced transformation. In the superelasticity, ordered parent phase structures turn into detwinned structure by means of stress induced transformation, and crystal structure cycles between these structures on stressing and releasing. Copper based alloys exhibit this property in metastable beta-phase region, which has bcc based structures at high temperature parent phase field. Crystallographic studies; x-ray and electron diffraction studies performed two copper based CuZnAl and CuAlMn alloys reveal that diffraction profiles exhibit super lattice reflections, and crystal structures change with long term aging in martensitic condition. This result refers to the rearrangement of atoms in diffusive manner.

O. Adiguzel (*) Department of Physics, Firat University, Elazig, Turkey e-mail: oadiguzel@firat.edu.tr © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_8

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Keywords Shape memory effect · Thermal memory · Martensitic Transformations · Reversibility · Thermoelasticity · Superelasticity · Twinning and detwinning

8.1

Introduction

Shape memory alloys take place in a class of functional materials with dual characters and stimulus response to the external condition like variation of temperature and mechanically deformation. These alloys are used as shape memory devices in many fields such as medicine, pharmacy, bioengineering, metallurgy and many engineering fields. These alloys return to a previously defined shape upon heating after deformation in low temperature martensitic condition, and cycle between the deformed and original shapes on cooling and heating, respectively. With these cycling properties, shape memory alloys are stimulus-responsive, thermo-responsive materials to response to a particular stimulus, such as heat. The devices made of shape memory alloys are able to respond to a particular stimulus by means of altering their physical shape and properties. Therefore, these alloys can be used as actuator and sensor against fire and other external effects [1–3]. The choice of material as well as actuator and sensor to combine it with the host structure is very essential to develop main materials and structures. Shape memory effect is linked with a solid state transformation called martensitic transformation, in atomic or crystallographic level, and comprises a reversible transition from product martensite to parent austenitic phase. Shape memory effect is activated successive thermomechanical processes, cooling below a critical temperature, martensite finish temperature and deformation in elastic strain limits in the product martensitic condition. With these processes, shape memory effect is governed by two successive thermal and stress induced martensitic transformations. Martensitic transformations are first order lattice-distorting phase transformations and evaluated by the structural changes in microscopic scale. These transformations occur in different ways and in a few steps basically. Thermal induced martensitic transformation occurs on cooling as martensite variants with cooperative movement of atoms by means of lattice invariant shears on {110} – type planes of austenite matrix which is basal plane of martensite. Thermal induced martensite occurs as twinned martensite, and twinned structures turn into detwinned martensite by means of stress induced martensitic transformation on stressing in martensitic state. Following these processes, the detwinned structure turns into the ordered parent phase structure by means of reverse martensite-austenite transformation on heating, and crystal structure cycles between detwinned and ordered parent phase structures, in reversible shape memory effect, on cooling and heating.

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Fig. 8.1 Crystallographic processes and schematic illustration of twinning and detwinning and returning back to parent phase structure on heating [1]

The twinning and detwinning processes are essential as well as martensitic transformation in reversible shape memory effect [1, 2]. The basic twinning and detwinning processes are crystallographically illustrated in Fig. 8.1 [1]. As seen from this figure; the ordered parent phase turns into twinned martensite thermally, and the twinned martensites turn into the detwinned martensites in stressinduced manner. Following these processes, shape memory effect is performed thermally on heating and cooling. Twinned martensitic structures turn into ordered parent phase structure by means of reverse martensite-austenite transformation, and crystal structure of materials cycle between ordered parent phase and detwinned martensitic structures on heating and cooling, in reversible shape memory effect. Therefore, advance and reverse transformations are called thermoelastic phase transformations and this behavior can be called thermoelasticity. The other characteristic exhibited by shape memory alloys is superelasticity (SE), which is performed by mechanical stress. Shape memory alloys can be deformed just over austenite finish temperature, and recover the original shape on releasing the stress in superelastic manner. Superelastic materials are deformed in the parent phase region and, shape recovery is carried out instantly and simultaneously upon releasing the applied stress. This property exhibits rubber like behavior or classical elastic material behavior. Complete shape recovery is observed upon unloading. Superelasticity is also result of martensitic transformation; stress induced martensitic transformation, which is induced by applying external stress only in mechanical manner, and ordered parent austenite phase structures turn into the fully detwinned martensite [2]. Superelasticity is performed in non-linear way, unlike normal elastic materials and exhibits rubber like behavior. Loading and unloading paths in stress-strain diagram are different in superelasticity, and hysteresis loop refers to the energy dissipation. Deformation at different temperature exhibits different behavior beyond shape memory effect and superelasticity [4]. The hysteresis loop refers to the absorption of strain energy and these alloys are mainly used as deformation absorbent materials in damping devices and buildings, due to the absorbance of strain energy during any disaster or earthquake. This hysteresis is one of the available characteristics for potential dissipative applications [5].

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A'

A

B B

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C

[100]

Fig. 8.2 (a) Stacking of (110)β planes viewed from [001]β direction, (b) Atomic configuration on first and second layers of (110)β plane in DO3 – type structures, (c) inhomogeneous shear and formation of layered structures, stacking sequences of half 18R or M18R unit cell in direction z

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A [011] (a)

B (b)

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(c)

The potential applications of shape memory alloys (SMA) in damping devices for civil structures, like buildings and bridges, to smooth out the oscillations produced by earthquakes and winds has been a subject of increasing interest in recent years. The superelasticity and the hysteresis cycle associated to the martensitic transformation in shape memory alloys are used to dissipate the energy of oscillations [5, 6]. With these properties, shape memory alloys with successive thermally and stress induced martensitic transformations are potential candidates for highly effective, nonstandard mechanical damping systems [6]. Copper based alloys exhibit this property in metastable β-phase region, which has B2 or DO3 –type ordered structures at high temperature, and these structures martensitically turn into layered complex structures with lattice twinning process, on cooling, by means of thermal induced transformation. Martensitic transformations occur mainly in two steps these alloys. First one is Bain distortion, and second one is lattice invariant shear. Bain distortion consists of expansion along the -type axes, Bain axes; and compressions in the and -type directions, perpendicular to Bain Axes [7]. Lattice invariant shears occur with cooperative movement of atoms in two opposite directions, -type directions on the {110}-type close packet plans of austenite matrix, and this movement is confined interatomic distances. The lattice invariant shears occur, in two opposite directions, -type directions on the {110}-type basal planes and this type of shear can be called as {110} – type mode and has 24 variants in self-accommodating manner [8, 9]. These lattice invariant shears are not uniform in copper alloys and give rise to the formation of unusual complex layered structures called long period layered structures such as 3R, 9R or 18R depending on the stacking sequences on the close-packed planes of the ordered lattice. Formation of these layered structures is schematically illustrated in Fig. 8.2. The complicated long-period stacking ordered structures mentioned above can be described by different unit cells. All of these martensite phases are longperiod stacking ordered structures that is the underlying lattice is formed by stacks of close-packed planes.

8 Thermally and Stress Induced Phase Transformations and Reversibility. . .

8.2

109

Experimental

Two copper based ternary CuZnAl and CuAlMn shape memory alloys were selected for investigation with following nominal compositions by weight: Cu-26.1% Zn-4% Al and Cu-%11Al-%6Mn. The martensitic transformation temperatures of these alloys are over the room temperature and both alloys are fully martensitic at room temperature. Powder specimens for x-ray examination were prepared by filling the alloys. Specimens for TEM examination were also prepared from 3 mm diameter discs and thinned down mechanically to 0.3 mm thickness. The quenched disc-shaped TEM specimens were electropolished and examined in a JEOL 200CX electron microscope operated at 160 kV. All of the specimens obtained from these alloys were heated in evacuated quartz tubes in the β-phase field (15 min at 830
C for CuZnAl alloy and 20 min at 700
C for the CuAlMn alloy) for homogenization and quenched in iced-brine to retain the β-phase. These specimens were also given different postquench heat treatments and aged at room temperature. X-ray diffraction profiles were taken from the quenched specimens using Cu-Kα radiation with wavelength 1.5418 Å.

8.3

Results and Discussion

An electron micrograph taken from the quenched specimen of CuZnAl Alloy, and electron diffraction patterns taken from CuZnAl and CuAlMn alloys are shown in Fig. 8.3a, b and c, respectively. An x-ray powder diffractograms taken from the quenched CuAlMn alloy sample is shown in Fig. 8.4. As seen from this figure, the

Fig. 8.3 (a) An electron micrograph showing the fine martensite structure in CuZnAl Alloy ( 90 k), and electron diffraction patterns taken from (b) CuZnAl and (c) CuAlMn alloys

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→ intensity

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Fig. 8.4 An x-ray powder diffractograms taken from the quenched CuAlMn alloy samples

main characteristics martensite in copper-based β-phase alloys are the prevalence of groups of essentially parallel-sided plates. Electron diffraction patterns and x-ray diffractograms reveal that both alloys exhibit superlattice reflections and have the ordered structure in the martensitic condition. Powder specimens were aged at room temperature in along term interval and a series of x-ray powder diffractograms and electron diffraction patterns were taken from both CuZnAl and CuAlMn alloy samples in a large time interval and compared with each other. It has been observed that electron diffraction patterns exhibit similar characteristics, but some changes occur at the reflected angles on the x- ray diffractograms and peak intensities with aging duration. These changes occur as rearrangement or redistribution of atoms in the material, and attribute to new transitions in diffusive manner [7, 8, 10]. This is the result of another transition, like precipitation and order-disorder transition as well as crystal imperfections, which affect the quality of shape memory and give rise to the formation of memory loses [11]. Crystal defects and crystal imperfections cause to the stacking faults on martensite basal plane. The ordered structure or super lattice structure is essential for the shape memory quality, and homogenization and releasing the external effect is obtained by ageing at β- phase field for adequate duration. On the other hand, post-quench ageing and service processes in devices affect the shape memory quality, and give rise shape memory losses. These kinds of results lead to the martensite stabilization in the disordering and diffusive manner. Although martensitic transformation has displacive character, martensite stabilization is a diffusion controlled phenomena, and this result leads to redistribution of atoms on the lattices sites. Stabilization is important factor and causes to memory losses, and changes in main characteristics of the material; such as, transformation temperatures, diffraction angles and peak intensities.

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Fig. 8.5 Atomic configuration of the (110) plane of DO3 – type ordered β-matrix (a) before and (b) after hexagonal distortion, (c) principal basal plane axes of the 18R structure

Martensitic phase in copper-based β-phase alloys is based the {110}β -type planes of parent phase. These planes have a rectangular shape in parent phase, and they are subjected to hexagonal distortion by undergoing a hexagon. This process is schematically illustrated in Fig. 8.5. In particular, some of successive peak pairs have moved toward each other. It is interesting that miller indices of these plane pairs provide a special relation [7]. This result can be attributed to a relation between interplane distances of these plane pairs and rearrangement of atoms on the basal plane. In these changes, atom sizes play important role. The different sizes of atomic sites lead to a distortion of the close-packed plane from an exact hexagon and thus a more close-packed layered structure may be expected. In the disordered case, atom sizes can be taken nearly equal, and martensite basal plane becomes an ideal hexagon. Metastable phases of copper-based shape memory alloys are very sensitive to the ageing effects, and any heat treatment can change the relative stability of both martensite and parent phases [10, 11]. Martensite stabilization is closely related to the disordering and crystal defects like vacancies in martensitic state, as well as pinning. Structural ordering is one of the important factors for the formation of martensite, while atom sizes have important effect on the formation of ordered structures [12–15].

8.4

Conclusion

It can be concluded from the above results that the copper-based shape memory alloys are very sensitive to the ageing treatments. The reflection angles and intensities of x-ray diffraction peaks changes with the ageing time in martensitic condition. These changes lead to the martensite stabilization in the redistribution or disordering

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manner, and stabilization proceeds by a diffusion-controlled process. These changes can be a measure of the ordering degree in martensite. The martensite stabilization is a diffusion controlled phenomena and leads to redistribution of atoms on the lattices sites, although martensitic transformation has displacive character. The basal plane of martensite turns into a hexagon by means of Bain distortion with martensite formation on which atom sizes have important effect. In case the atoms occupying the lattice sites have the same size, the basal plane of martensite becomes regular hexagon; otherwise the deviations occur from the hexagon arrangement of the atoms. All of these effects give raise the increase in the complexity of crystal structure.

References 1. Liu Y (2001) Detwinning process and its anisotropy in shape memory alloys. Smart Mater Proc SPIE 4234:82 2. Sun L, Huang WM, Ding Z, Zhao Y, Wang CC, Purnawali H, Tang C (2012) Stimulusresponsive shape memory materials: a review. Mater Des 33:577 3. Huang WM et al (2010) Shape memory materials. Mater Today 13:54 4. Adiguzel O (2017) Thermoelastic and pseudoelastic characterization of shape memory alloys. Int J Mater Sci Eng 5:95 5. de Castro Bubani F, Sade M, Lovey F (2012) Improvements in the mechanical properties of the 18R $ 6R high-hysteresis martensitic transformation by nanoprecipitates in CuZnAl alloys. Mater Sci Eng A 543:88 6. de Castro Bubani F, Lovey F, Sade M, Cetlin P (2016) Numerical simulations of the pseudoelastic effect in CuZnAl shape-memory single crystals considering two successive martensitic transitions. Smart Mater Struct 25(1) 7. Adiguzel O (2013) Phase transitions and microstructural processes in shape memory alloys. Mater Sci Forum 762:483 8. Adiguzel O (2012) Martensitic transformation and microstructural characteristics in copper based shape memory alloys. Key Eng Mater 510–511:105 9. Casati R et al (2014) Thermal cycling of stress-induced martensite forhigh-performance shape memory effect. Scr Mater 80:13 10. Li Z, Gong S, Wang MP (2008) Macroscopic shape change of Cu13Zn15Al shape memory alloy on successive heating. J Alloys Compd 452:307 11. Adiguzel O (2007) Smart materials and the influence of atom sizes on martensite microstructures in copper-based shape memory alloys. J Mater Process Technol 185:120 12. Guo YF et al (2007) Mechanisms of martensitic phase transformations in body-centered cubic structural metals and alloys: molecular dynamics simulations. Acta Mater 55:6634 13. Aydogdu A, Aydogdu Y, Adiguzel O (2004) Long-term ageing behaviour of martensite in shape memory Cu–Al–Ni alloys. J Mater Process Technol 153–154:164 14. Sade M, Pelegrina JL, Yawny A, Lovey FC (2015) Diffusive phenomena and pseudoelasticity in Cu–Al–Be single crystals. J Alloys Compd 622:309 15. Kustov S, Corr M, Pons J, Cesari E, Van Humbeeck J (2006) Thermodynamic reversibility and irreversibility of the reverse transformation in stabilized Cu-Zn-Al martensite. Mater Sci Eng A 438–440:768

Chapter 9

The Toxic Effect of Trifluralin on Soil Microorganisms in the Presence of Fe0/PVP Nanoparticles A. Sidorenko, I. Rastimesina, O. Postolachi, V. Fedorov, T. Gutul, and A. Vaseashta

Abstract Nanoparticles Nano zero-valent iron (nZVI) Fe0/PVP were prepared by chemical reduction from a ferrous salt-solution in the presence of PVP used as a stabilizer. The resulting nanoparticles were characterized by X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission microscopy (TEM), and FT-IR–spectroscopy. Aqueous colloidal sollution of prepared nanoparticles was used in biotest. The results show that Fe0/PVP nanoparticles can act as both stimulants and inhibitors of mycelial growth. The stimulating effect of Fe0/PVP was observed on three out of five micromycete strains, namely 1LD, 5D and 8D. The growth of the strains Alternaria sp. 4D and P. viride was significantly suppressed in the presence of solution of Fe0/PVP nanoparticles (the inhibition activity was 26.88% and 13.91%, respectively). At the same time, Fe0/PVP nanoparticles stimulated the formation and maturation of micromycetes’ spores. Keywords Nanozero-valent iron (nZVI) · Poly-N-vinylpyrrolidone · Biotest · Trifluralin · Alternaria · P. viride Streptomyces sp.

A. Sidorenko D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia I. Rastimesina · O. Postolachi Institute of Microbiology and Biotechnology, Chisinau, Republic of Moldova V. Fedorov · T. Gutul (*) Institute of Electronic Engineering and Nanotechnologies ‘D.Ghitu’, Chisinau, Republic of Moldova A. Vaseashta International Clean Water Institute, Manassas, VA, USA NJCU – A State University of New Jersey, Jersey City, NJ, USA D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_9

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Introduction

The applications of nanotechnology, especially for metal-based engineered nanomaterials, have been constantly increasing over the past decades [1–3]. An important property of nanomaterials is their larger surface area, which provides their increased reactivity. Nanoparticles (NPs) have a unique ability to remediate toxic environments and provide a healthy substrate for microbial activity thus speeding up the process of environment clean-up [3, 4]. A wide variety of nanomaterials, such as zeolites, metal oxides, carbon nanotubes and fibers, several noble metals and titanium dioxide, have been studied for in situ decontamination techniques [2]. However, nanomaterials remain in the center of intense research because of their unknown environmental risks and effects on living organisms [1, 5, 6]. Some of them, such as NPs of Ag and Au and oxides of Al, Ti, Si and Zn, have a harmful effect on the cells of microorganisms [1, 5, 7, 8]. Among metal-based engineered nanomaterials, iron NPs are, probably, the most commonly used for bioremediation of a broad spectrum of pollutants, including halogenated organic chemicals, polycyclic aromatic hydrocarbons, pesticides, and heavy metals [2, 3, 6, 9]. Iron NPs have a large surface and exhibit high chemical activity; they are significantly superior to iron particles commonly used for the degradation of pollutants [4, 9]. Iron NPs applied for in-situ subsurface remediation have a high potential for migration in the environment and are likely to interact not only with pollutant chemicals, but also with living organisms [10, 11]. Iron-based NPs are expected to be non-toxic, due to using a Fe atom in several pathways of cell metabolism and, therefore, a low iron toxicity [8]. However, there is a series of studies that prove the toxic action of iron NPs on different microorganisms, particularly Escherichia coli [5, 12, 13], Staphylococcus aureus [13], Dehalococcoides spp. [5], Pseudomonas putida [2, 12], Pseudomonas stutzeri [6], Bacillus subtilis var. niger, Pseudomonas fluorescens [14], Pseudomonas aeruginosa [15], Erwinia amylovora, Xanthomonas oryzae, Bacillus cereus [16], and, in some cases, on the compositional structure and functional capacity of the soil microbial community [17, 18]. In all cases, the concentration and size of NPs played an important role. Only one experiment on the direct effects of nano zero-valent iron (nZVI) on fungi strain of Aspergillus versicolor, in addition to our studies [19], has been published [14]. The authors have shown that, even the treatment of the fungal culture with a relatively high concentration of nZVI has a zero effect on viability. Regarding indirect effects of iron NPs, there are reports that demonstrate that the adverse effects of Fe3O4 NPs on the soil bacterial community were altered by arbuscular mycorrhizal fungi [18]. There is scarce information in the specialized literature concerning the interaction between iron NPs and streptomycetes; however, the existing data confirm the resistance of streptomycetes to the action of iron NPs. The growth inhibition of streptomycetes was observed, while no bactericidal effect was detected

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[16, 19]. However, in other cases, the growth of streptomycetes was stimulated in the presence of iron NPs [19, 20]. Summarizing the above, the purpose of our study was to determine the effect of fluorinated dinitroaniline herbicide trifluralin and zero-valent iron NPs on the growth of micromycetes and streptomycetes strains.

9.2

Experimental

Iron(II) sulfate (
99.7%) or a saturated iron(III) chloride solution (
99.0%), polyN-vinylpyrrolidone (PVP, MW: 8000), and sodium borohydride were purchased from Sigma-Aldrich. Trifluralin (
99.9%) was purchased from Sigma-Aldrich. Deionized water was used in the experiment. All chemicals were used as received without further purification.

9.2.1

Synthesis of Fe0/PVP nanoparticles

Nano ZVI/polyvinylpyrrolidone (Feo/PVP) NPs were prepared using iron(II) sulfate or iron(III) chloride by the chemical reduction method in accordance with the modified synthesis procedure described in [21, 22]. Synthesis was conducted at 25  C in an argon atmosphere under stirring for 4 h; during synthesis, a calculated amount of polyelectrolyte—PVP—was introduced. The resulting black powder was separated from the mother solution, washed with ethanol, and dried at 100  C.

9.2.2

Methods

The resulting material was studied by FTIR spectroscopy using a PerkinElmer Spectrum 100 FT-IR spectrometer in a spectral range of 650–4000 Spectral range was about 400–4000 cm1. The samples were prepared in KBr for recording in a range of 400–4000 cm1. The X-ray diffraction analysis was carried out on a Empyrean Panalitical diffractometer using CuKα radiation at λ ¼ 1.93604 Å at an accelerating voltage of 45 kV and a current of 40 mA in a range of 2θ ¼ 10 –80 at room temperature. Scanning electron microscope (SEM) images were recorded with a Quanta 200 electronic microscope (SEM) operating at 30 kV with secondary and backscattering electrons in a high vacuum mode and a Jeol JEM-2100F transmission electron microscope (TEM).

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9.2.2.1

Test Culture

The cultures used for the test were isolated from soil long-term polluted with obsolete pesticides (trifluralin and DDTs). Soil samples were collected nearby the destroyed storehouse for pesticides and organic fertilizers, in the central part of the Republic of Moldova, Chisinau municipality. All the cultures belonged to laboratory collection of Institute of Microbiology and Biotechnology. Six strains of streptomycetes, namely, Streptomyces sp. 0112, Streptomyces sp. 0212, Streptomyces sp. 0312, Streptomyces sp. 0412, Streptomyces sp. 0512, and Streptomyces sp. 0612, and five strains of micromycetes, namely, 1LD, Alternaria sp. 4D, 5D, 8D, and Penicillium viride were used.

9.2.2.2

Agar Plug Diffusion Method

To determine the inhibition activity (IA) of the iron NPs and trifluralin, the agar plugs diffusion method was used. Agar plugs from fresh lawn cultures of streptomycetes and micromycetes were prepared with sterile cork borer. The agar plugs were then aseptically transferred to plates with a Czapek-Dox agar medium and incubated at 27  2  C. There were four experimental options: option 1, control (Czapek-Dox agar medium, pH of 7.0–7.2 for streptomycetes and 5.0 for micromycetes); option 2, a Czapek medium + a solution of Fe0/PVP NPs; option 3, a Czapek medium + a solution of trifluralin; and option 4, a Czapek medium + a mixed solutions of Fe0/ PVP NPs and trifluralin. Plates were prepared in triplicate for each treatment. Trifluralin (α,α,α–trifluoro–2–6-dinitro–N–N–dipropyl–p–toluidine), which is a pre-emergent herbicide belonging to the dinitroaniline chemical family, was used as a solution in acetone at a concentration of 100 mg/L. A colloidal aqueous solution of Fe0/PVP NPs was used in a concentration of 100 mg/L.The mixture of solutions of Fe0/PVP NPs and trifluralin was incubated for 1 h before use. The diameter of growth zones for the streptomycetes and micromycetes strains was measured after 7 days of mycelial growth. Inhibition activity (%) of each treatment was calculated in percent of inhibition of growth compared with the negative control (0%) according to the method proposed by Pandey et al. (1982) [23, 24].

9.3

Results and Discussion

The morphology and sizes of the Feo/PVP NPs are shown in Fig. 9.1. The micrographs show that the NPs are spherical and have sizes of 8–10 nm. The spread in size is characteristic of the formation of NPs by synthesis without ultrasonic processing. Since the NPs exhibit a high surface energy, they undergo a rapid interparticle

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Fig. 9.1 TEM micrograph image of the morphology of Feo/PVP NPs

Fig. 9.2 SEM micrograph image of the morphology of Feo/PVP NPs at different magnifications

interaction, coarsening, and then aggregation in solution. It is evident from the microphotographs that the resulting NPs are agglomerated into larger entities with a size of 25–35 nm. Figure 9.2 shows SEM data, where iron NPs form a laced architecture composed of regular fragments owing to the magnetic attraction of the nanoparticles to each other. These chain structures are formed involving PVP, which is a unique polymer, which exhibits, in addition to reducing properties, the ability to form a nanostructure [25]. The diffraction pattern of the Fe /PVP NPs has a diffraction maximum at 2θ ¼ 44.8 ; the particle size calculated by the Debye– Scherrer formula is 8 nm, which corresponds to the size of Fe and indicates the absence of iron oxides, which confirms the size determined by TEM [26]. The interactions of PVP with iron NPs was studied by FTIR spectroscopy. Analysis of the spectra of the Feo/PVP NP samples suggests that polymer can be coordinated through a chelating interaction between the oxygen atoms of the PVP ring and the iron atoms and between the nitrogen atoms, as described for silver NPs [27].

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50 38.71

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Fig. 9.3 Effect of trifluralin, Fe0/PVP NPs, and the mixed solution of trifluralin and Fe0/PVP NPs on the growth of micromycetes

The observed shift in the absorption region of the C¼O bond from 1664 cm1 for the pure polymer to 1694 and 1735 cm1 is characteristic of the bond and the formation of a C¼O–Me bond [28]. In the absorption region of 500–600 cm-1, the spectrum exhibits a peak at 580 cm responsible for the Fe-O bond, which is apparently attributed to FeO(OH) formed on the surface of Fe0/PVP nanoparticles during synthesis. Various substances added to the culture medium for the cultivation of microorganisms can both stimulate their growth and inhibit it. Stimulation of growth can be expressed by an increase in the biomass of a microorganism grown in a liquid nutrient medium, an increase in the number of colony forming units (CFUs) or in the size of a colony of microorganism grown on a solid nutrient medium. On the contrary, the inhibitory effect of the substance can be expressed by a decrease in biomass accumulation, a decrease in the amount of CFUs, and a reduction in size of the microorganism colony. In the case of mycelial fungi or streptomycetes, the following relationship was observed: the smaller the diameter of the colony grown on a solid nutrient medium amended with the test substance compared with the diameter of the colony in the control version, the higher the value of the IA and the more sensitive the strain to the action of the substance. Conversely, the larger the diameter of the colony, the lower the IA value and the more resistant the strain to the action of the substance. The IA values, which characterized the susceptibility of fungal strains to the trifluralin, Fe0/PVP NPs, and the mixed solution, are shown in Fig. 9.3. The 1LD strain did not react to the presence of magnetite NPs in the culture medium; that is, the diameter of the growth zones was at the control level. The magnetite NPs had a weak inhibitory effect on fungal strains Alternaria sp. 4D and 5D, and the growth of micromycetes 8D and P. viride was even stimulated. Each fungal strain had an individual reaction to the solution of iron NPs added to the culture medium. Comparison of the IA values, which were positive for two out of five micromycetes and negative for three of them, suggests that Fe0/PVP NPs could be both growth inhibitors and stimulants of mycelial fungi.

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Fig. 9.4 The effect of trifluralin, Fe0/PVP NPs and the mixed solution of trifluralin and Fe0/PVP NPs on growth of streptomycetes

The solution of Fe0/PVP NPs had a strong inhibitory effect on the cultures of micromycetes Alternaria sp. 4D and P. viride (IA of 26.88 and 13.91%, respectively). The stimulating effect of Fe0/PVP NPs on the growth of mycelial fungi was gentler compared with IA; the IA was within 1.6% and  3.1%. It was visually clear and microscopically confirmed that Fe0/PVP NPs stimulated the formation and maturation of spores of micromycetes. This effect occurred regardless of the level of micromycetes’ sensibility or IA values. The inhibitory effect of the trifluralin solution, expressed by an increase in the IA value, was observed in all strains of micromycetes. The most sensitive strain to the inhibitory action of trifluralin was Alternaria sp. 4D (IA 38.7%); the IA values of other four strains varied in a range of 5.06–7.95%. Preliminary incubation of a mixture of trifluralin and Fe0/PVP NP solutions for 1 h reduced the inhibitory effect of trifluralin: for Alternaria sp. 4D, by 1.3 times; for strain 5D, by 4.3 times; and for three other micromycetes, by 1.7–2.2 times. Incubation of trifluralin with Fe0/PVP NP solution reduced the pesticide toxicity for micromycetes, even in the case when strain had a high sensitivity to Fe0 NPs. Thus, in all versions of the experiment, when a mixture of trifluralin and NPs was added, the same phenomenon was observed, namely, the negative effect of trifluralin was reduced. The susceptibility of the streptomycetes to the Fe0/PVP NPs, trifluralin, and the mixture of solutions of Fe0/PVP NPs and trifluralin, expressed as a percentage of the control, is shown in Fig. 9.4. The Fe0/PVP NPs did not have a toxic effect on the studied streptomyces. Susceptibility of the strains varied depending on the individual peculiarities of each strain. In most cases, except for the Streptomyces sp. 0312 strain, the growth stimulation was recorded. The Streptomyces sp. 0212 and Streptomyces sp. 0512 strains grew most actively, by 5.48 and 6.56%, respectively, above the control value.

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It should be noted that the presence of Fe0/PVP NPs in the medium did not affect the growth activity of the Streptomyces sp. 0312 strain. Although streptomyces strains were isolated from the soil long-term polluted with pesticides, they were found to be sensitive to the increased concentration of trifluralin. Of the six studied streptomycetes, four strains showed a decrease in the growth activity in the presence of trifluralin compared with the control. The most visible inhibition of growth was forund for the Streptomyces sp. 0612 strain (9.09%). Exceptions were provided by Streptomyces sp. 0112 and Streptomyces sp. 0212; their growth activity was stimulated in the presence of trifluralin by 2.12 and 2.74%, respectively. Mixing of trifluralin and Fe0/PVP NP solutions led to a decrease in the negative effect of trifluralin. Thus, the growth activity of the Streptomyces sp. 0112 and Streptomyces sp. 0212 strains increased compared to the version in which only trifluralin was added. The sensitivity of strain Streptomyces sp. 0312 returned to the control values. Although the negative effect of trifluralin on Streptomyces sp. 0412, Streptomyces sp. 0512, and Streptomyces sp. 0612 was not completely reduced, the toxicity of the pesticide was diminished. Iron is an essential microelement for cell growth and vital activity of microorganisms. Iron is involved in a large number of cellular processes; it acts as a cofactor of a large number of enzymes; it is required for oxygen transport, nitrogen fixation, ATP generation, and DNA synthesis. Because of low bioavailability of iron in nature, the microorganisms have developed a system with a high iron affinity, which is based on the synthesis of siderophores. Iron in high concentrations is toxic; therefore, the intracellular iron level in microorganisms is strictly regulated by iron assimilation systems [29]. At present, remediation of polluted soil and groundwater with iron-based NPs represents a faster, cheaper, and potentially more effective treatment option than the currently available ex situ and in situ methods. The direct application of large amounts of iron-based NPs to soils for remediation purposes raises specific concerns about potential consequences on soil microbial communities and their key functions for soil fertility and biodegradation of pollutants [30, 31]. Because microorganisms are especially sensitive to environmental changes, the structure and abundance of the microorganism community can be shifted in response to foreign nanomaterials [20]. Fe0 and Fe3O4-based NPs are oxidized in biological media. Recent nanotoxicological studies have reported that this oxidation can be responsible for their toxicity toward environmental bacteria. The cytotoxic effects are directly associated with this oxidation and the generation of an oxidative stress, as demonstrated using a mutant strain of E. coli completely devoid of superoxide dismutase activity. This stress results from the generation of reactive oxygen species (ROS) through the Fenton reaction (Fe2+ + H2O2 ! Fe3+ + OH + OH) during the oxidation of Fe0 NPs to magnetite (Fe32+/3+O4) and lepidocrocite (γFe3+OOH) [32]. In our experiments, the addition of iron NPs to a streptomycete culture medium, in most cases, led to the growth stimulation of microorganisms. The previously mentioned cytotoxic effect induced by magnetite NPs was observed only at Streptomyces sp. 0512 and Streptomyces sp. 0612. These results correlate with our

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previous results and with the published data showing that streptomycetes are resistant to iron NPs. Thus, He et al. (2011) [20] showed that the introduction of iron oxide magnetic NPs in soil can potentially stimulate some bacterial growth (especially of Actinobacteria, such as Duganella, Streptomycetaceae or Nocardioides) and change the soil bacterial community structure, although bacterial abundance does not change. The research of Barzan et al. (2014) [16] showed a higher resistance of Streptomyces to Fe0 NPs compared with Gram-negative bacteria; growth inhibition was observed, while no bactericidal effect was detected. Resistance of streptomycetes can be attributed to the presence of a thick (20–80 nm) peptidoglycan layer in the cell walls of gram-positive bacteria, which makes them more resistant to NPs [16]. Definitely, peptidoglycans containing mucopeptides, glycopeptides, and mureins are the structural elements of almost all bacterial cell walls. Their domination in the cell wall of some gram-positive bacteria is substantial; however, it seems to be less in gram-negative bacteria. It was speculated that this discrepancy in membrane structure can lead to their different absorption abilities onto Fe0 NPs. Hence, it was shown that there is an association between the cell wall architectures and the sensitivity to Fe0 NPs, which suggests that either membrane disruption or differential membrane permeability plays a role in the cytotoxicity of Fe0 NPs [11]. Moreover, there are data showing that iron metabolism is strictly regulated in Streptomyces species by a family of pleiotropic transcriptional regulators, which are referred to as DmdR. These regulators sense intracellular iron levels and control the expression of gene encoding for several iron-containing enzymes, oxidative stress response systems, and siderophore biosynthesis clusters, such as desferrioxamine [33]. In our experiments, mixing the solutions of iron NPs and trifluralin resulted in a reduction in the trifluralin toxicity. This fact suggests that iron NPs is as effective as bulk Fe materials in the reactions of successive reduction of nitro groups in dinitroaniline herbicides [34, 35].

9.4

Conclusion

Using XRD, SEM, and TEM, it was shown that iron nanoparticles with a core size of 8.0–10.0 nm are formed during the synthesis; the nanoparticles are agglomerated into aggregates with a pronounced chain structure with a length of up to 20 nm; they are bound by magnetic interaction. The stabilization of entire structure is provided by an iron oxid layer with a thickness of about 10–12 nm. The decrease in the inhibitory effect of trifluralin on soil microorganisms Alternaria sp. 4D and P. viride is attributed to the effect of reductive degradation of Fe0/PVP nanoparticles. However, Fe0/PVP have a stimulating effect on the formation and maturation of micromycetes’ spores.

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References 1. McKee MS, Filser J (2016) Impacts of metal-based engineered nanomaterials on soil communities. Environ Sci Nano 3:506 2. Ortega-Calvo J-J, Jimenez-Sanchez C, Pratarolo P, Pullin H, Scott TB, Thompson IP (2016) Tactic response of bacteria to zero-valent iron nanoparticles. Environ Pollut 213:438–445 3. Sherry Davis A, Prakash P, Thamaraiselvi K (2017) Nanobioremediation technologies for sustainable environment. Bioremediation and Sustainable Technologies for Cleaner Environment Springer Int Pub 13 4. Zhang W-x (2003) Nanoscale iron particles for environmental remediation. Nanopart Res 5(3/4):323–332 5. Auffan M, Rose J, Wiesner MR, Bottero J-Y (2009) Chemical stability of metallic nanoparticles: a parameter controlling their potential cellular toxicity in vitro. Environ Pollut 157(4):1127–1133 6. Saccà ML, Fajardo C, Martinez-Gomariz M, Costa G, Nande M, Martin M, Pant AB (2014) Molecular stress responses to Nano-sized zero-Valent Iron (nZVI) particles in the soil bacterium Pseudomonas stutzeri. PLoS One 9(2):e89677 7. Gordon T, Perlstein B, Houbara O, Felner I, Banin E, Margel S (2011) Synthesis and characterization of zinc/iron oxide composite nanoparticles and their antibacterial properties. Colloids Surf A Physicochem Eng Asp 374(1–3):1–8 8. Kiran GS, Nishanth LA, Priyadharshini S, Anitha K, Selvin J (2014) Effect of Fe nanoparticle on growth and glycolipid biosurfactant production under solid state culture by marine Nocardiopsissp. MSA13A. BMC Biotechnol 14(1) 9. Fang G, Si Y, Tian C, Zhang G, Zhou D (2012) Degradation of 2,4-D in soils by Fe3O4 nanoparticles combined with stimulating indigenous microbes. Environ Sci Pollut Res 19(3):784–793 10. Ševců A, El-Temsah YS, Joner EJ, Černík M (2011) Oxidative stress induced in microorganisms by zero-valent Iron nanoparticles. Microbes Environ 26(4):271–281 11. Xie Y, Dong H, Zeng G, Lin T, Jiang Z, Zhang C, Deng J, Zhang L, Zhang Y (2017) The interactions between nanoscale zero-valent iron and microbes in the subsurface environment: a review. J Hazard Mater 321:390–407 12. Chaithawiwat K, Vangnai A, McEvoy JM, Pruess B, Krajangpan S, Khan E (2016) Impact of nanoscale zero valent iron on bacteria is growth phase dependent. Chemosphere 144:352–359 13. Darwish MSA, Nguyen NHA, Sevcu A, Stibor I (2015) Functionalized magnetic nanoparticles and their effect on Escherichia coli and Staphylococcus aureus. J Nanomater 16(1):89 14. Diao M, Yao M (2009) Use of zero-valent iron nanoparticles in inactivating microbes. Water Res 43(20):5243–5251 15. Kafayati ME, Raheb J, Angazi MT, Alizadeh S, Bardania H (2013) The effect of magnetic Fe3O4 nanoparticles on the growth of genetically manipulated bacterium, Pseudomonas aeruginosa (PTSOX4). Iran J Biotechnol 11(1):41–46 16. Barzan E, Mehrabian S, Irian S (2014) Antimicrobial and Genotoxicity effects of zero-valent Iron nanoparticles. Jundishapur J Microbiol 7(5) 17. Pawlett M, Ritz K, Dorey RA, Rocks S, Ramsden J, Harris JA (2013) The impact of zero-valent iron nanoparticles upon soil microbial communities is context dependent. Environ Sci Pollut Res 20(2):1041–1049 18. Cao J, Feng Y, Lin X, Wang J (2016) Arbuscular mycorrhizal fungi alleviate the negative effects of iron oxide nanoparticles on bacterial community in rhizospheric soils. Front Environ Sci 4:10 19. Postolachi O, Rastimesina I, Vorona V, Mamaliga V, Streapan N, Gutul T (2017) Sensitivity of fungal and streptomycete strains to trifluralin and magnetite nanoparticles. Proceeding book of International Symposium “The environment and the industry”, SIMI: 290 20. He S, Feng Y, Ren H, Zhang Y, Gu N, Lin X (2011) The impact of iron oxide magnetic nanoparticles on the soil bacterial community. J Soils Sediments 11:1408

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21. Gutul T, Rastimesina I, Postolachi O, Nicorici A, Dvornikov D, Petrenco P (2015) Synthesis and biological application of magnetite nanoparticles. Moldavian J Phys Sci 14(3–4):177 22. Xia X, Zeng J, Oetjen LK, Xia Y (2012) Quantative analysis of the role played by poly(vinylpyrrolidone) in seed-mediated growth of ag nanocrystals. J Am Chem Soc 1:134 23. Pandey DK, Tripathi NN, Tripathi RD, Dixit SN (1982) Fungitoxic and phytotoxic properties of the essential oil of Hyptis suaveolens. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz 89(6):344 24. Islam MR, Jeong YT, Ryu YJ, Song CH, Lee YS (2009) Isolation, identification and optimal culture conditions of Streptomyces albidoflavus C247 producing antifungal agents against Rhizoctonia solani AG2-2. Mycobiology 37(2):114 25. Koczkur K, Mourdikoudis S, Polavarapu L, Skrabalak S (2015) Polyvinylpyrrolidone (PVP) in nanoparticle synthesis. Dalton Trans 1:3 26. ICSD Database, Version 1.2.0 (2003) 50567 XRD 27. Hoppe CE, Lazzari M, Pardiñas-Blanco I, López-Quintela MA (2006) One-step synthesis of gold and silver hydrosols using poly(-vinyl-2-pyrrolidone) as a reducing agent. Langmuir 22(16):7027–7034 28. Adiguzel O (2017) Thermoelastic and Pseudoelastic characterization of shape memory alloys. Int J Materials Sci Eng 5(3):95–101 29. Flores FJ, Rincón J, Martín JF (2003) Characterization of the iron-regulated desA promoter of Streptomyces pilosus as a system for controlled gene expression in actinomycetes. Microb Cell Factories 2(1):5 30. Hjorth R, Coutris C, Nguyen NHA, Sevcu A, Gallego-Urrea JA, Baun A, Joner EJ (2017) Ecotoxicity testing and environmental risk assessment of iron nanomaterials for sub-surface remediation – recommendations from the FP7 project NanoRem. Chemosphere 182:525–531 31. Simonin M, Richaume A (2015) Impact of engineered nanoparticles on the activity, abundance, and diversity of soil microbial communities: a review. Environ Sci Pollut Res 22(18):13710–13723 32. Auffan M, Achouak W, Rose J, Chanerac C, Waite DT, Masion A, Woicik J, Wiesner MR, Bottero JY (2008) Relation between the redox state of ironbased nanoparticles and their cytotoxicity towards Escherichia coli. Environ Sci Technol 42(17):6730 33. Flores FJ, Barreiro C, Coque JJR, Martín JF (2005) Functional analysis of two divalent metaldependent regulatory genes dmdR1 and dmdR2 in Streptomyces coelicolor and proteome changes in deletion mutants. FEBS J 272(3):725–735 34. Klupinski TP, Chin YP (2003) Abiotic degradation of trifluralin by Fe(II): kinetics and transformation pathways. Environ Sci Technol 37(7):1311 35. Wang S, Arnold WA (2003) Abiotic reduction of dinitroaniline herbicides. Water Res 37(17):4191–4201

Chapter 10

Management of Ransomware Detection and Prevention in Multilevel Environmental Monitoring Information System G. Margarov and E. Mitrofanova

Abstract Modern multilevel environmental monitoring systems are usually built on the basis of information infrastructure consisting of multiple servers and endpoints. Endpoints recently become targets for ransomware attacks. The nature and main principles of ransomware are presented. The main recommendations for detection and prevention of ransomware attacks are considered. Keywords Environmental monitoring · Defense management · Ransomware · Endpoint

10.1

Introduction

Modern multilevel environmental monitoring systems are usually built on the basis of information infrastructure consisting of multiple servers and workstations. Given the importance of the human factor in information security, the weakest link of such an infrastructure are workstations or in other words endpoints that have recently more and more often become targets for ransomware attacks [1, 2]. In this regard, the research of such attacks and the management of protection against them becomes an urgent problem for information security and management specialists. In recent years, there has been a significant growth in both the variety and frequency of ransomware attacks, which has reached more than 4000 attacks per day [3]. However, it may be expected that in the foreseeable future the variety of Ransomware attacks may decrease against the backdrop of a significant increase in their thoughtfulness and sophistication. As a result, information security risks can

G. Margarov (*) Information Security and Software Development Department, National Polytechnic University of Armenia, Yerevan, Armenia E. Mitrofanova Department of Personnel Management, State University of Management, Moscow, Russia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_10

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become more significant, especially for critical infrastructures, such as environmental monitoring systems. Broadly speaking ransomware is a type of malware that blocks access to the data on the attacked computer or threatens to publish or delete them until a ransom is paid. In fact, the number of such attacks around the world is actively growing, as for malicious users it can be a simple enough but effective way of receiving money, given that it is possible to purchase means of ransomware attacks implementation on the darknet market without special professional skills [4]. In addition to financial losses, ransomware attacks can prevent environmental monitoring and cause irreparable ecological harm. Existing ransomware attacks can be categorized into two main groups [5]: • extortion attack, which blocks data through encryption, • leakware attack, which threatens to publish exfiltrated data from attacked computer. In the case of extortion attack on the victim’s computer, most of the working files (for example, all files with the most common extensions) are encrypted. At the same time, the attacked computer remains operational, but almost all user files become inaccessible. Instruction and a key for decrypting files the attacker promises to send for a reward, which is usually not so high. Leakware (also called Doxware) is an attack that threatens to publish information stolen from the attacked computer rather than deny the victim’s access to it. In this case, malware exfiltrates sensitive data and the attacker threatens to publish the victim’s data unless a ransom is paid. In other words, the difference between the two groups of attacks is as follows. In the extortion attack, the victim loses real access to his own valuable information and has to pay to get it back, whereas with the Leakware attack, the victim retains access to information, but the attacker threatens to publish it [6]. In the last case, the victim as a rule must pay a large enough ransom not only for the fact that his valuable information were not published, but also for the fact that the successful attack was not made public, which in its turn could damage the victim’s reputation.

10.2

General Principles of Ransomware

To manage the detection and prevention of ransomware attacks, it is very important in the beginning to look at how the attacks themselves are carried out. Wherein it is important to note that not all ransomware tools (software) work in exactly the same way, especially at the initial stages of the attack, but in every malware attack, downloading and installing malware is the defining first step. Analysis shows that most attacks are carried out in the following fixed sequence: • Malware delivery to hosting server. In some way, an attacker provokes a potential victim to download specially prepared malware or it is delivered through

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vulnerabilities in the software of a hosting server or potential victim’s computer. Most often for targeted delivery of malware phishing and social engineering methods are used. Download of malware from hosting server to target computer. When the web page is loaded again from the hosting server where malware is hosted, a background exchange of information starts, during which malware is transferred (installed) to the victim’s computer. Malware execution and compromising of target computer. During the execution of malware on the victim’s computer, it finds and exploit a corresponding vulnerability in the software to achieve the goal. Encryption of files on target computer. Once the victim’s computer is compromised, the corresponding user files are encrypted, and malware sends an encryption key as well as the necessary information about the victim’s computer and hosting server to the attacker’s server. User notification and countdown activation. At the final stage of the attack, the attacker’s server sends a pre-prepared message to the victim, which contains information that the user files are encrypted, as well as instructions on what to do (pay the ransom) to obtain the decryption key. To amplify and emphasize urgency, the message can include a counter that counts down the time until the user files are irretrievably destroyed.

Generally speaking ransomware by its nature is a type of financial fraud, and accordingly attackers are just profiteers who are generally very far from cyber espionage. Nevertheless, ransomware attacks can cause serious damage to critical infrastructures and, in particular, to environmental monitoring information systems.

10.3

Ransomware Detection

It’s decisive to manage ransomware detection as quickly as possible to have time to prevent an attack that is actually capable of encrypting user files within minutes. Therefore, real-time ransomware detection on victim’s computer and hosting server is recommended to implement in accordance with the following steps that are crucial: • Implementing vulnerability scans and asset discovery. Detailed knowledge of what is happening at any time in the information system, including local and cloud assets, is essential in order to understand the scope of any security incident. Since the goal of a ransomware attack is to steal most valuable assets (user data) the availability of an updated and reliable asset inventory to provide the systems security team with everything they need in the event of an attack is very important. Besides, periodic vulnerability assessments are critical, because when new vulnerabilities and exploits are discovered, vulnerable assets can be corrected or reconfigured to address these risks.

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• Performing intrusion detection. Despite the fact that ransomware is difficult to detect in advance, with a good intrusion detection system, the attack can be detected quickly enough to prevent its successful termination. An intrusion detection system can detect some signature behaviors of a ransomware attack in the initial stages, for example disabling firewall or antivirus software, running unauthorized or unexpected network scans, sending data via a covert channel, updating an audit policy and so on. • Enabling file integrity monitoring. Main part of malware, including ransomware, run some system processes and gain direct access to system files, which in most cases is not part of the normal system operations. In this case, the file integrity monitoring technology can generate a warning signal at any time when a critical system file is updated, modified or moved. This of course cannot prevent the beginning of the file encryption process, but it can prevent further spread of the ransomware attack by allowing to quickly isolate and quarantine the compromised system. • Implementing security automation and harmonic integration. Rapid operational response is a critical success factor in any type of emergency, including malware attacks. The faster it will be possible to detect and respond to a potential ransomware attack the greater the likelihood of preventing a large damage. In most cases, protection against cyber-attacks is essentially a certain patch on the management system, which, unfortunately, makes it difficult to respond quickly and in a coordinated manner in the event of attacks. Wherein modern innovations in security automation and management have significantly improved the response to threats and incidents, ensuring the joint coordinated functioning of various security tools that can be effectively incorporated into a single management platform [7]. This approach can essentially provide immediate disconnection of network access and isolation of endpoints as soon as ransomware activities are detected at the level of hosting server. • Managing log monitoring and analysis. One of the important intermediate goals of any attacker is hidden inside system logs, access and activity logs, application logs, etc. At the same time, the problem of detecting the access of the attacker to these logs is rather complicated due to the sheer volume and endless variety of these logs, which makes it necessary to automate the correlation of events, for example, within the framework of the Security Information and Event Management (SIEM) technology [8], to analyze these logs and warning of the beginning of a ransomware attack, which in turn will allow stop its spread. • Combining updated threat intelligence with security monitoring. Most experienced attackers who conduct ransomware attacks tend to rely on a welldesigned holistic ecosystem and are constantly evolving their methods. In turn, security analysts carefully researching their development, innovation and infrastructure, which allows proactive developing management methods (for example, events correlation rules) and tools for detecting the latest ransomware attacks. Continuous threat intelligence updates can help to stay ahead of emerging threats [9].

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Ransomware Prevention

Research of the principles of ransomware attack and compilation of best practices made it possible to formulate basic recommendations on the management of ransomware attacks prevention by the following sequence of actions: • Conducting regularly security trainings for end users. Most ransomware attacks continue to be based on the ignorance and inexperience of end users who are not suspecting anything and are not hesitating to click on a link or open a file received from an unknown source. In this situation, the most reasonable and effective solution can be regular security trainings for end users, especially on modern methods of phishing and social engineering. In essence, these methods, which are often used to organize ransomware attacks, will become unsuitable if users learn to be more skeptical of what they see or receive via the Internet, and also to analyze and think through their actions well. • Organizing effective backup and recovery procedures. It is obvious that with a ransomware attack, when a user runs the risk of losing all his significant data, if he does not pay the ransom, an operative and safe backup of all data is a reasonable way out of the dangerous situation [10]. Such a copy allows the user to confidently ignore the ransom request to obtain the decryption key and simply restore the data from the backup. In this case, of course, there will be certain time costs for restoration, but the ransom will not be paid and, most important, the attacker will understand that his attack was unsuccessful. Unfortunately, not all end users regularly perform backups or check recovery procedures. Modern procedures and tools for data backup are another important point of regular security trainings for end users. • Establishing proper preventive actions practices for endpoints. Ransomware and other malware attacks are mainly based on the use of software vulnerabilities and unsafe configurations at endpoints. In contrast to large-scale network attacks, such as Distributed Denial of Service (DDoS), ransomware purposefully attacks endpoints, because it is there that basically contains large amounts of user data, for which it is easiest to get a ransom. In this regard, the best protection against ransomware attacks is simply to improve information security at endpoints by complying with all security management rules. In particular, the timely update of the operating system and applications with the installation of all the latest patches is one of the most effective ways to protect against modern ransomware attacks. In addition, it makes sense to disable macros on MS Office applications, and also to delete all unnecessary software. • Implementing continuous vulnerability assessment. When modern ransomware executing on the endpoint, it finds and exploit the latest vulnerabilities to achieve the goal. In this regard, regular and continuous vulnerability assessment scanning will reveal the vulnerabilities of applications, OS and network, which will allow immediately direct efforts to neutralize the

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vulnerabilities to prevent future ransomware or other malware attacks. Special vulnerability scanning tools allow to regularly check if the endpoint is at risk. Given that such tools are usually constantly receives vulnerabilities updates, the user can be sure that on the endpoint has identified all the latest known vulnerabilities. • Filtering incoming and especially outgoing connections to block unwanted ones. At the first stages of the ransomware attack, the victim’s infected computer initiates a connection to the attacker’s server. Therefore, if block such connections at the gateway of the endpoint, then the ransomware attack is actually violated before it starts executing. To implement such a blocking can be used for example, IP addresses and domains from the crowd-sourced computer-security platform Open Threat Exchange (OTX) [11]. In addition, for user control can be recommending to setting up an alert when initiating such connections.

10.5

Conclusion

Strict adherence to the above given safety management rules and recommendations can provide in most cases defense of multilevel environmental monitoring information system not only against ransomware attacks, but also many other modern security threats.

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9. Yaqoob I, Ahmed E, ur Rehman MH, Ahmed AIA, Al-garadi MA, Imran M, Guizani M (2017) The rise of ransomware and emerging security challenges in the internet of things. Comput Netw 129(Part 2):444–458 10. Thomas JE, Galligher GC (2018) Improving backup system evaluations in information security risk assessments to combat ransomware. Comp Inf Sci 11(1):14–25 11. Sauerwein C, Sillaber C, Mussmann A, Breu R (2017) Threat intelligence sharing platforms: an exploratory study of software vendors and research perspectives. In: Proceedings of 13th International Conference on Wirtschaftsinformatik (WI 2017), St. Gallen, pp 837–851

Chapter 11

Organization of Assistance to Victims of a Thermal Trauma During the Pre-hospital and Hospital Stages in the Event of a Terrorist Attack Vasyl Nagaichuk, Roman Chornopyshchuk, Andrii Povoroznyk, Mykhailo Prysyazhnyuk, Volodymyr Zelenko, and Igor Girnik

Abstract The thesis provides a brief overview of international publications on thermal trauma resulting after terrorist acts in peacetime, newly developed and improved already known technologies of treatment of critical and supercritical burn patients introduced in the practice of the burn center and on the basis of which an algorithm for assisting patients with burns in the pre-hospital and hospital stages was developed. Keywords Terrorist act · Burns · Combined trauma · Inhalation injury · Neutralization of the thermal factor · Hyperbaric oxygen therapy · Early surgical treatment · Biogalvanization

11.1

Introduction

Over the last 15–20 years terrorist attacks around the world have increased significantly, which has led to an increase in traumatic injuries, among which burns range from 5–8% to 50% or more according to different authors [1–4]. The main factors of global terrorism directed against civilians are explosions and fires [5–7]. From 1968 to 2004 there were 19,828 terrorist attacks in the world, of which 7401 were human casualties. A total of 86,568 injured and 25,408 (29.4%) of deaths was registered [8]. V. Nagaichuk · R. Chornopyshchuk (*) Department of General Surgery, National Pirogov Memorial Medical University, Vinnytsya, Ukraine Regional Clinical Hospital named after M.I. Pirogov, Burns center, Vinnytsya, Ukraine A. Povoroznyk · M. Prysyazhnyuk · V. Zelenko · I. Girnik Regional Clinical Hospital named after M.I. Pirogov, Burns center, Vinnytsya, Ukraine © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_11

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One of the most massive and high profile terrorist attacks took place in the United States on September 11, 2001 when suicide bombers completely destroyed the World Trade Center buildings (New York) and partly destroyed the Pentagon complex (Washington DC) with commercial planes. According to literary sources, only 28% of the victims had isolated thermal injuries to the skin. The majority of victims (2/3 of the total number of the hospitalized) had burns combined with other types of traumatic injuries. At the beginning of the XXI century massive terrorist attacks swept through Southeast Asia: 2002 – Bali Island, 2003–2004 – Jakarta, 2005 – Bali Island. In recent years (2015–2017) terrorist attacks have increased in Iraq, Israel, Egypt, Afghanistan, and intensified in Europe (Germany, France, Belgium, Russia, Ukraine) [9]. In Ukraine the risk of terrorist threats exists not only on a global basis, but also on the part of illegal armed groups operating in its eastern regions. Over the past 3 years more than 5800 terrorist attacks in peaceful territories have been recorded in Ukraine and each year they are becoming more cynical and brutal [10]. In Vinnytsya in the period from 11.09.2002 to 20.05.2003 there were also three explosions in route taxis. About 30 passengers were injured. Twenty-five victims were hospitalized. Two patients died, including one child. The purpose of the thesis is to improve the provision of assistance to victims of a thermal trauma at the pre-hospital and hospital stages.

11.2

Research Materials and Methods

Over the years 2008–2017 241 patients with deep burns constituting 31–90% of a total body surface area were treated in the burn center of the Vinnytsya Pirogov Regional Clinical Hospital. One hundred fifteen (47.7%) victims died. If the main factor of the terrorist attack is a fire, the victims receive burns of various areas and depths caused by the flames, which in an enclosed space are complicated by airway burns and inhalation poisoning by highly toxic combustion products of modern decorative materials. If the factor of a terrorist attack is an explosive device, the main trauma of victims is the traumatic soft tissue damage with fractured bones penetrating into the cavities and causing internal injuries, brain contusions, which are complicated by burns of the skin. High voltage electrical burn injuries received on the rooftop of railway carriages and produced by contact with a power source of 25–27 thousand volts are sufficiently similar to the injuries sustained during terrorist attacks. As a rule, such victims receive burns of 60–90% of a total body surface area from the flame of an electric arc, as well as the burning of their own clothes. Over the past 10 years 11 male patients who were injured with high-voltage electrocution on the rooftop of railway carriages had 50–90% burns of a total body surface area and were treated in the burn center. There were 6 adults and 5 children. One patient had an industrial injury, 2 patients were “train surfers”, 3 patients wanted

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to take a selfie and the cause of the injuries of 5 patients, which they received between 1 and 3 a.m., could not be determined.

11.3

Results and Discussion

In recent years, taking into account the tendency to increase of the number of patients with supercritical burns, high mortality rates of severely injured victims, significantly limited funding for the treatment of patients, the professional staff of the burn center began to develop new and improve already known technologies of treating patients with burns. At the burn center a new direction in medicine has been started, in particular in Combustiology. It is the so-called “biogalvanization”, which implies the use of a low-intensity current without any external power supplies with a diagnostic, therapeutic and rehabilitation purpose. The principle of the method is to use two electrodes (donor and electron receiver) connected by a conductor through a measuring device. The electrodes applied to biological tissues generate the microcurrent in an interelectrode space due to the contact difference of the electrode potentials, which has similar characteristics to the membrane potentials and has diagnostic and therapeutic properties (Fig. 11.1). The change of the terms “cooling of burn wounds“to “rapid neutralization of the traumatic effect of exogenous and endogenous lesion factors with the use of room temperature water” has been studied and pathogenetically grounded and its technology has been worked out. Applying this method of helping patients with burns since 1987, we came to the conclusion in 2000 that both burns and cooling are equally harmful to the body. And if they act simultaneously, the severity of the injury increases. We suggest introducing a new term – “rapid neutralization of traumatic effects of exogenous and endogenous lesion factors “. With what? Ordinary well water or tap room temperature water.

Fig. 11.1 VITA-01-M is an electronic device of a new generation, which operates without traditional external current sources and provides biodiagnostics, biocorrection and biophorexis of medicinal substances

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By an exogenous traumatic factor we understand thermal, chemical, electrical, light and beam factors, which at the moment of contact with the skin form the primary eschar. After the contact of the traumatic factor with the skin, a zone of paranecrosis is formed under the necrosis the temperature in which increases to +60–70  C and this is an endogenous factor of the lesion. Protein coagulates at +43–45  C only with prolonged exposure, in which there is a secondary deepening of the wound, which can last for several days. Nowadays, there is no problem for combustiologists to treat superficial burns, even burns of 60–90% of a total body surface area. At the same time, deep burns of more than 30% of a total body surface area are not compatible with life in most cases until today. If the superficial burns are at a depth of several millimeters (to the skin appendages), deep burns are at a depth of a few centimeters (from the skin appendages, which died, to the bones). Thus, it is not by chance that today the prognosis of life expectancy is determined not by the area of burns, but by the mass of dead tissues. It is becoming apparent that with the same body surface area of deep burns, the mass of dead tissues and the severity of the course of burn disease increase proportionally to the depth of the wound leaving no chances for life. That is why it is so important after neutralizing the exogenous factor to proceed immediately to neutralizing the traumatic effect of the endogenous lesion factor and prevent secondary deepening of the wound and an increase in the mass of dead tissues. If the neutralization of the exogenous lesion factor by room temperature water takes 10–15 min, the neutralization of the traumatic effect of the endogenous lesion factor takes from 6–8 h to days and more. The criterion for neutralization cessation is a stable disappearance of pain in the wound and a cool wound surface by touch. It is advisable to carry out the neutralization of burns to 50% of a total body surface area using the application method (Fig. 11.2); for more than 50% of a total body surface area it is advisable to use a bath with water (Fig. 11.3).

Fig. 11.2 Neutralization of exogenous and endogenous lesion factors with the application method

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Fig. 11.3 Neutralization of an endogenous lesion factor with ordinary water in the bath

The issue of sterile or not sterile water. If you compare the bacterial cultures from the well or tap water and the skin of a person, this question will disappear by itself. In addition, after a burn is received the wound is protected by its own biological coating, burn necrosis, which begins to peel away from the wound on the 14–19th day from the moment of injury. Therefore, the efforts of people who provide assistance to victims of burns, along with neutralization, should be focused on the prevention or minimization of the effects of severe thermal trauma through infusion and drug therapy. An early surgical necrectomy at the stage of burn shock (2–3 days after injury) with the postoperative closure of wounds with xenoderm grafts has been pathogenetically substantiated and introduced into the practice of burn center (Fig. 11.4). Necrectomy with minimal bleeding for deep burns during the period of burn shock with the formation of drainage openings and the subsequent hyperbaric oxygen therapy for wounds with the use of low-intensity current without any external power sources. Patient K., 25 years old, medical card number 22891, sustained burns of 40% of a total body surface area by flames of ІІb – ІІІ stage (Figs. 11.5 and 11.6). Necrectomy with minimal bleeding with surgical drainage of the wound was performed (Figs. 11.7 and 11.8). Twelve days after the injury the exarticulation of the right upper limb was performed (Fig. 11.9). Twenty days after the injury granulating wounds are closed with mesh autodermic grafts with a 1: 4 perforation ratio (Fig. 11.10). The wounds fully healed after 60 days following the trauma, however, spontaneous

138 Fig. 11.4 Patient D., 73 years old, 2 days after early surgical necrectomy and closure of postoperative wounds with xenoderm grafts

Fig. 11.5 Day 3 after the injury. Wounds under burn necrosis. Posterior view

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Fig. 11.6 Day 3 after the injury. Wounds under burn necrosis. Anterior view

Fig. 11.7 Day 9 after the injury. Appearance of the wound after necrectomy with minimal bleeding with surgical wound drainage. Exposed necrotizing capsule of the right shoulder joint. Posterior view

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Fig. 11.8 Day 9 after the injury. Appearance of the wound after necrectomy with minimal bleeding with surgical wound drainage. Exposed necrotizing capsule of the right shoulder joint. Anterior view

Fig. 11.9 Day 17 after the injury. Five days after right upper extremity exarticulation. Remnants of burn necrosis associated with granulating wound tissues

pneumothorax came on. A Bülau drain was applied (Fig. 11.11), the lung was expanded and the patient was discharged from the hospital on day 90 after full recovery (Figs. 11.12 and 11.13). The technology of extrafascial necrectomy for widespread deep burns with skin surface regeneration by micro auto grafts and a subsequent hyperbaric oxygen therapy treatment with the use of low-intensity current without any external power sources (Patent of Ukraine for invention No. 97741) was improved and implemented in the practice of the burn center.

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Fig. 11.10 Day 20 after the injury. Granulating trunk wounds and their closure with mesh autodermic grafts with a 1: 4 perforation ratio Fig. 11.11 Day 60 after the injury. A spontaneous pneumothorax through the rupture of damaged intercostal muscles. A Bülau drain was applied .

Patient B., 2 years 9 months, medical card number 7746, sustained burns of 50% of a total body surface area by flames of ІІb – ІІІ stage (Fig. 11.14). Extrafascial necrectomy (Fig. 11.15) with the postoperative closure of wounds with xenoderm grafts was performed on the first day of the injury (Fig. 11.16). On day 6 after the injury the lower half of the lateral and posterior surfaces of the trunk was closed with mesh xenoderm grafts with a 1: 4 perforation ratio, into the

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Fig. 11.12 Day 90 after the injury. Patient K. prior to hospital discharge. Side view

Fig. 11.13 Day 90 after the injury. Patient K. prior to hospital discharge. Posterior view

cells of which micro auto skin grafts with an area of 4 mm2 were implanted (Fig. 11.17). On day 7 after the injury a similar operation was performed on the upper half of the lateral and posterior surfaces of the trunk (Fig. 11.18). The

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Fig. 11.14 Hospitalization in the burn center after 8 hours following the injury

Fig. 11.15 21 hours after the injury, early extrafascial necrectomy is performed in the region of the posterior and lateral trunk surfaces

development of epithelialization around micro auto skin grafts contributed to the healing of the wounds of the rear and lateral surfaces of the trunk up to 20 days after injury (Fig. 11.19). The development of epithelialization around micro auto skin grafts contributed to the wound healing of the lateral and posterior surfaces of the trunk up to 20 days after the injury (Fig. 11.19).

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Fig. 11.16 Day 5 after the injury, wounds under lyophilised xenoderm grafts

Fig. 11.17 Day 6 after the injury. Wound reconstructive surgery of the lower half of the posterior and lateral trunk surfaces with mesh xenoderm grafts 1: 4. Microautodermoplasty

At other sites of wounds their closure was carried out both with xenoderm grafts and autodermal grafts. Seven operations were performed in 20 days. On day 28 wounds nearly healed (Fig. 11.20). On day 28 the patient was allowed to sit up (Fig. 11.21), on day 30 the patient was allowed to walk as the wounds fully healed (Fig. 11.22). The patient was discharged on day 33 and sent to health-resort treatment at the “Avangard” sanatorium, Nemyriv (Fig. 11.23). The technology of repairing soft tissue defects with the hyperbaric oxygen therapy with the use of low intensity current without external power sources has been developed in the burn center. Patient V., 28 years old, was admitted to the center on the fifth day after a traffic accident with the diagnosis of polytrauma, extensive torn ragged wound of the lower leg with an open comminuted fracture of the bones. A closed transverse fracture of the upper third of the left thigh. An open

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Fig. 11.18 Day 7 after the injury. Microautodermoplasty of the upper half of the posterior and lateral trunk surfaces

Fig. 11.19 Day 20 after the injury. Micro auto skin grafts were repeatedly transplanted onto the residual granulating wounds of the posterior and lateral trunk surfaces

fracture of the left olecranon. A closed fracture of the left shoulder (Figs. 11.24 and 11.25). On day 2 following the hospitalization necrectomy and wound revision were performed (Fig. 11.26). On day 7 following the hospitalization reduction and immobilization of the femur and the tibia with the external fixation devices were performed (Figs. 11.27 and 11.28). During 48 days wound treatment was conducted under a biological coating as a hyperbaric oxygen therapy with the use of low-intensity current without any external power sources (Fig. 11.29). The soft tissue defect of was marked by granulation (Fig. 11.30). The final skin grafting was performed and the patient was discharged on the 69th day after the hospitalization (Fig. 11.31).

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Fig. 11.20 Day 28 after the injury. Wounds under micro auto skin grafts practically healed

Fig. 11.21 Day 28 after the injury. The patient is allowed to sit up

Newly developed and improved already known technologies of treatment of patients with thermal trauma were implemented in the practice of the burn center and allowed us to save the lives of the patients with most severe burn injuries who had not survived before. Patient G., 35 years old, medical card number 13162, was hospitalized in the burn center 15 min after the injury with the diagnosis of burn disease, burn shock of stage IV. The patient sustained burns of 80% of a total body surface area by flames of ІІb – ІІІ stage. The patient reported that alcohol was spilt on them in the amount of 3 kg caught fire. The sportswear manufactured in China fused and burned on the victim. After being hospitalized, the patient underwent rapid

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Fig. 11.22 Day 30 after the injury. Wounds are completely healed Fig. 11.23 The patient is allowed to walk on day 30 with the hospital discharge 3 days after

neutralization of traumatic effects of exogenous and endogenous lesion factors in a bath with water, whose initial temperature was +20  C, and a terminal temperature was +27  C. Local treatment of the patient with the hyperbaric oxygen therapy under a polyvinyl chloride film (Figs. 11.32 and 11.33). Infusion therapy according to Parkland formula. On day 2 after the injury the patient was operated by a surgical

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Fig. 11.24 The patient is transferred to the burn center on day 5 after the accident. Appearance of wounds upon hospitalization, medial surface

Fig. 11.25 The patient is transferred to the burn center on the fifth day after an accident. Appearance of wounds during hospitalization, lateral surface

Fig. 11.26 On day 2 following the hospitalization necrectomy and wound revision were performed

team (Fig. 11.34). Early necrectomy and closure of postoperative wounds with lyophilized xenoderm grafts were performed (Fig. 11.35). In the process of treatment the patient underwent biogalvanization and biophoresis of medicinal substances (Fig. 11.36).

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Fig. 11.27 Roentgenography of the left femur with the external fixation devices on day 7 following hospitalization

Fig. 11.28 Reduction and immobilization of the femur and the tibia with the external fixation devices were performed on day 7 following hospitalization

Fig. 11.29 Treatment of wounds under the biological cover

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Fig. 11.30 Granulating wounds of the left tibia

Fig. 11.31 Complete healing of the wound on day 69 following hospitalization

Fig. 11.32 Patient G. on the dressing station seven hours after the injury

On day 14 after the injury deep granulating wounds were formed (Fig. 11.37). The patient was operated. Early necrectomy and autodermoplastics were performed. On day 54 after the injury the wound healing process finished completely

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Fig. 11.33 Patient G., local wound treatment with hyperbaric oxygen therapy under a PVC film

Fig. 11.34 The surgical team performs early surgical necrectomy with wound closure with lyophilized xenoderm grafts. Day 2 after the injury

(Figs. 11.38 and 11.39). Long-term results after a number of health-resort treatment procedures in 2 years (Figs. 11.40 and 11.41). On the basis of developed and improved technologies for the treatment of patients with burns an algorithm for providing assistance to the patients with burns at the pre-hospital and hospital stages was created. Thermal burns: I. Hospital stage (place of the injury, midwife center, dispensary): cardiopulmonary resuscitation is to be performed (on indications); burn sites are to be immersed in water or treated with a stream of water; clothes from the victim are to be removed; neutralization of the traumatic effect of the endogenous

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Fig. 11.35 Wounds under lyophilized xenoderm grafts. Day 3 after the injury

Fig. 11.36 Day 8 after the injury. Biogalvanization and biophoresis of medicinal substances were carried out

lesion factor with ordinary water or in a bath with +26  С temperature water (90% burns of a total body surface area) is to be carried on; wet-to-dry dressings on the affected parts of the body with furacilinum, betadine or water are to be applied; transportation of the victim to the CDH, burn unit or burn center is to be organized.

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Fig. 11.37 Day 14 after the injury, deep granulating wounds

Fig. 11.38 Day 54 after the injury. The patient prior to hospital discharge. Anterior view

II. Hospital stage is the qualified care (CDH, city hospital): cardiopulmonary resuscitation is to be performed (on indications); burn sites are to be immersed in water or treated with a stream of water; clothes from the victim are to be removed; neutralization of the traumatic effect of the endogenous lesion factor

154 Fig. 11.39 Day 54 after the injury. The patient prior to hospital discharge. Posterior view

Fig. 11.40 The patient after health-resort treatment 2 years after the injury. Anterior view

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Fig. 11.41 The patient after health-resort treatment 2 years after the injury. Posterior view

with ordinary water with the application method or in a bath with +26  С or more temperature water (for 60% burns or more of a total body surface area) to the complete disappearance of pain and normalization of the internal tissue temperature is to be carried on; a PVC film to close the wound at the end of neutralization is applied; central or peripheral venous catheterization is to be performed; intravenous fluid infusion of crystalloid solutions and the following groups of drugs is performed: cardiovascular, anticoagulants, antiplatelet agents, antihypoxants, antioxidants, inhibitors of proteolysis, hepatoprotectors, membrane protectors, vasoprotectors, anti-inflammatory drugs, etc.; oxygen therapy with extensive burns is to be performed; transportation of the victim to the burn unit or burn center in consultation with the head of the unit/center is to be organized. III. Hospital stage is the qualified care (burn unit / center): artificial respiration and indirect cardiac massage are to be carried out (on indications); burn sites are to be immersed in water or treated with a stream of water; clothes from the victim are to be removed; neutralization of the traumatic effect of the endogenous lesion factor with ordinary water with the application method or in a bath with +26  С temperature water for more than 60% burns of a total body surface area to the complete disappearance of pain and normalization of the internal tissue temperature is to be carried on; a PVC film to close the wound at the end of neutralization is to be applied; central or peripheral venous catheterization is to be performed; intravenous infusion of crystalloid solutions and the following groups of drugs is performed: cardiovascular, anticoagulants, antiplatelet agents, antihypoxants, antioxidants, inhibitors of proteolysis, hepatoprotectors, membrane protectors, vasoprotectors, anti-inflammatory drugs, etc.; oxygen therapy for extensive burns is to be performed; early surgical dermatome

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necrectomy to punctate bleeding spots is to be performed (day 2–3 after the injury) with the postoperative closure of wounds with lyophilized xenoderm grafts; postoperative hyperbaric oxygen therapy for patients with burn injuries under a PVC film with the use of low-intensity current without any external power sources is to be performed; barotherapy; magnetotherapy and others. Electrical burns: I. Hospital stage (place of the injury, midwife center, dispensary): it is important to reverse the action of an electric current; cardiopulmonary resuscitation is to be performed (on indications); clothes from the victim are to be removed; full body massage is to be done; wet-to-dry dressings on the affected parts of the body with furacilinum, betadine or decasanum are to be applied; analginum 50% – 2.0; dimedrolum 1% – 2.0; Sibazon 0.5% – 2 are to be administered intramuscularly; transportation of the victim to the CDH, burn unit or burn center is to be organized. II. Hospital stage is the qualified medical aid (CDH, city hospital): artificial respiration and indirect cardiac massage are to be carried out (on indications); defibrillation of the heart, tracheal intubation or tracheostomy are to be performed (on indications); clothes from the victim are to be removed; wetto-dry dressings on the affected parts of the body with furacilinum, betadine or decasanum are to be applied; central or peripheral venous catheterization is to be performed; intravenous fluid infusion of crystalloid solutions and the following groups of drugs is performed: cardiovascular, anticoagulants, antiplatelet agents, antihypoxants, antioxidants, inhibitors of proteolysis, hepatoprotectors, membrane protectors, vasoprotectors, anti-inflammatory drugs, etc.; surgical revision of injured muscles resulting after high-voltage burns is to be performed; cardiovascular, respiratory, central nervous systems, renal functions, blood and urine counts are to be monitored round the clock; transportation of the victim to the burn unit or burn center in consultation with the head of the unit/center is to be organized. III. Hospital stage is the qualified care (burn unit / center): artificial respiration and indirect cardiac massage are to be carried out (on indications); defibrillation of the heart, tracheal intubation or tracheostomy are to be performed (on indications); clothes from the victim are to be removed; central or peripheral venous catheterization is to be performed; wet-to-dry dressings on the affected parts of the body with furacilinum, betadine or decasanum are to be applied; analginum 50% – 2.0; dimedrolum 1% – 2.0; Sibazon 0.5% – 2 are to be administered intramuscularly (on indications); intravenous fluid infusion of crystalloid solutions and the above mentioned groups of drugs is to be performed; surgical revision of injured muscles resulting after high-voltage burns is to be performed; cardiovascular, respiratory, central nervous systems, renal functions, blood and urine counts are to be monitored round the clock; reconstruction and restoration operations are to be performed (on indications); early surgical necrectomy with the postoperative closure of wounds with

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lyophilized xenoderm grafts is to be performed; amputation-necrectomy of mummified limbs at different stages is to be performed; barotherapy (on indications); magnetotherapy etc. Chemical burns: I. Hospital stage (place of the injury, midwife center, dispensary): cardiopulmonary resuscitation is to be performed (on indications); clothes from the victim are to be removed; burn sites are to be treated with a stream of water to the complete disappearance of pain; aseptic bandages with 3–4% solution of sodium bicarbonate are to be applied after acid burns; aseptic bandages with 3–4% solution of citric or acetic acid are to be applied after alkali burns; aseptic bandages with 20% sugar solution are to be applied after lime burns; aseptic bandages with a 3–5% solution of sodium bicarbonate are to be applied after metal salt burns (silver nitrate, copper sulphate, zinc chloride); analginum 50% – 2.0; dimedrolum 1% – 2.0; Sibazon 0.5% – 2 are to be administered intramuscularly; transportation of the victim to the CDH, burn unit or burn center is to be organized. II. Hospital stage is the qualified medical aid (CDH, city hospital): artificial respiration and indirect cardiac massage are to be carried out (on indications); clothes from the victim are to be removed; burn sites are to be treated with a stream of water to the complete disappearance of pain; aseptic bandages with 3–4% solution of sodium bicarbonate are to be applied after acid burns; aseptic bandages with 3–4% solution of citric or acetic acid are to be applied after alkali burns; aseptic bandages with 20% sugar solution are to be applied after lime burns; aseptic bandages with a 3–5% solution of sodium bicarbonate are to be applied after metal salt burns (silver nitrate, copper sulphate, zinc chloride); analginum 50% – 2.0; dimedrolum 1% – 2.0; Sibazon 0.5% – 2 are to be administered intramuscularly; central or peripheral venous catheterization is to be performed; intravenous fluid infusion of crystalloid solutions and the following groups of drugs is performed: cardiovascular, anticoagulants, antiplatelet agents, antihypoxants, antioxidants, inhibitors of proteolysis, hepatoprotectors, membrane protectors, vasoprotectors, anti-inflammatory drugs, etc. (on indications); transportation of the victim to the burn unit or burn center in consultation with the head of the unit/center is to be organized. III. Hospital stage is the qualified care (burn unit / center): artificial respiration and indirect cardiac massage are to be carried out (on indications); clothes from the victim are to be removed; burn sites are to be treated with a stream of water to the complete disappearance of pain; aseptic bandages with 3–4% solution of sodium bicarbonate are to be applied after acid burns; aseptic bandages with 3–4% solution of citric or acetic acid are to be applied after alkali burns; aseptic bandages with 20% sugar solution are to be applied after lime burns; aseptic bandages with a 3–5% solution of sodium bicarbonate are to be applied after metal salt burns (silver nitrate, copper sulphate, zinc chloride); analginum 50% – 2.0; dimedrolum 1% – 2.0; Sibazon 0.5% – 2 are to be administered intramuscularly; central or peripheral venous catheterization is to be performed;

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Table 11.1 Mortality rate (years 1984–1989 and 2012–2017) Years 1984/2012 1985/2013 1986/2014 1987/2015 1988/2016 1989/2017 Total In average In average (adults + children)

Mortality rate in Region Adults 31/20 28/14 32/27 30/23 30/15 28/11 179/110 29,8/18,3 43,0/20,6

Children 15/5 18/1 11/1 11/3 12/3 12/1 79/14 13,2/2,3

intravenous fluid infusion of crystalloid solutions and the above mentioned groups of drugs is performed (on indications); early surgical dermatome necrectomy to punctate bleeding spots is to be performed (day 2–3 after the injury) with the postoperative closure of wounds with lyophilized xenoderm grafts; postoperative treatment of patients with burn injuries with hyperbaric oxygen therapy under a PVC film with the use of a low intensity current without external power sources; barotherapy; magnetotherapy and others. Due to the developed and improved technologies of treatment, the mortality rate of patients with burns in the region was reduced by 2.1 times over the past 6 years (2012–2017) compared with 1984–1989 with minimum financial security of the unit: the rate in adults was reduced by 1.6 times, in children it was reduced by 5.6 times (Table 11.1).

11.4

Conclusion

1. Thermal factor is an integral etiological component of a combined trauma during terrorist attacks. 2. An efficient organization and algorithm for helping patients with burns obtained during collective and mass traumas are the key to successful treatment. 3. The use of sophisticated explosive devices with a more potent traumatic effect requires further improvement of the algorithms for providing assistance to victims of terrorist attacks at the pre-hospital and hospital stages. 4. The development of new and improvement of known technologies for the treatment of severely injured patients with combined lesions has made it possible, with minimum financial security, to save lives of the categories of patients who had not survived before. Finding new and improving the known technologies for treating patients with burns can contribute to a positive outcome, which is the prospect of further research.

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References 1. Weissman O, Israeli H, Rosengard H et al (2013) Examining disaster planning models for largescale burn incidents – a theoretical plane crash into a high-rise building. Burns 39(8):1571–1576 2. Haik J, Tessone A, Givon A et al (2006) Terror-inflicted thermal injury: A retrospective analysis of burns in the Israeli-Palestinian conflict between the years 1997 and 2003. J Trauma 61 (6):1501–1505 3. Peleg K, Liran A, Tessone A et al (2008) Do burns increase the severity of terror injuries? J Burn Care Res 29(6):887–892 4. Yurt RW, Bessey PQ, Bauer GJ et al (2005) Regional burn center’s response to a disaster: September 11, 2001, and the days beyond. J Burn Care Rehabil 26(2):117–124 5. Yurt RW, Bessey PQ, Alden NE et al (2006) Burn-injured patients in a disaster: September 11th revisited. Burn Care Res 27(5):635–641 6. Marti M, Parron M, Baudraxler F et al (2006) Blast injuries from Madrid terrorist bombing attacks on March 11, 2004. Emerg Radiol 13(3):113–122 7. Mayo A, Kluger Y (2006) Terrorist bombing. World J Emerg Surg 13(1). Article № 33 8. Bogen KT, Jones ED (2006) Risks of mortality and morbidity from worldwide terrorism: 1968–2004. Risk Anal 26(1):45–59 9. Chim H, Yew WS, Song C (2007) Managing burn victims of suicide bombing attacks: outcomes, lessons learnt, and changes made from three attacks in Indonesia. Crit Care 11(1). Article № R15 10. Koval L. Features of Ukrainian Terrorism. http://www.ukurier.gov.ua/uk/articles/osoblivostiterorizmu-po-ukrayinskomu/p/

Chapter 12

Frequency Transducers of Gas Concentration Based on Transistor Structures with Negative Differential Resistance A. V. Osadchuk and V. S. Osadchuk

Abstract The paper presents the results of studies on the creation of frequency microelectronic transducers of gas concentration based on autogenerator transistor devices. In the proposed devices, the gas concentration is converted into a frequency output signal. Such a conversion allows to remote all disadvantages of analog gas sensors: low output voltage (millivolts), low sensitivity, parasitic influence of measuring channels on each other, instability in operation, need for amplifying devices and analog-digital transducers by subsequent processing of measurable information. The analysis of operation of an autogenerator in the quasilinear mode was carried out. This autogenerator is the main element of frequency transducers. The conditions for self-excitation and its main characteristics were determined. The physical mechanism of operation of resistive gas sensors is considered. It is shown that oxide semiconductors under the action of a gas change the surface electric conductivity. This effect underlies the construction of gas-resistive sensors, which are used as primary transducers of gas concentration in frequency devices. Elements of the theory of near-surface charge in semiconductors of the type ZnO2, SnO2 are also considered. On the basis of the solution of the Poisson equation, analytical expressions for the surface resistance of hole and electronic semiconductors are obtained. The theoretical dependence of the surface resistance for metal oxides on the methane concentration is calculated. Schemes of frequency microelectronic transducers of gas concentration based on transistor structures with negative resistance are proposed and studied. In the falling section of the current-voltage characteristics, the operating point of the device is selected, which ensures the self-excitation of the transducer self-oscillator. The energy losses in the oscillatory circuit of the autogenerator are replenished by negative resistance. A method for calculating current-voltage characteristics, output impedance, transformation functions, and sensitivity of devices are proposed. The A. V. Osadchuk (*) · V. S. Osadchuk Radioengineering Department, Vinnytsia National Technical University, Vinnytsia, Ukraine © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_12

161

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calculations are based on mathematical models of transducers, which follow from the Kirchhoff equations. Equations are compiled on the basis of nonlinear equivalent circuits of frequency devices. The microelectronic frequency transducer of gas concentration works in the oscillation mode of the oscillator because of proper selecting a constant voltage of the power supply. The gas sensitive resistor is included in the positive feedback loop of the autogenerator. When the concentration of gas affected on the gas sensitive resistor, so. its resistance decreases, which leads to a change in the equivalent capacitance of the oscillator circuit of the self-oscillator, and this in turn changes the generation frequency. The sensitivity of the frequency transducers was 10–800 Hz/ppm in the range of gas concentration changes from 0 to 5∙103 ppm. Keywords Radiomeasuring transducer gas concentration · MEMS sensor · Frequency output signal · Negative resistance

12.1

Introduction

The problems of monitoring and measuring the concentration and composition of the gas environment for preventing explosions and preserving people’s lives are vital. Measurement and control of the gaseous medium is necessary at military objects facilities, in cockpits of aircraft and spacecraft, tanks, submarine compartments, military depots and so on. In civilian life such objects are metro, airports, trams, trolleybuses, cinemas, trains, gas stations, etc. The current level of development of information and measurement technology is characterized by a wide variety of methods for converting the values of gas concentration into an electrical signal. Representation of measurement information in the analog form of voltage or current leads to the need to use analog-digital converters, whose cost, with high requirements for accuracy, can be compared with the cost of a microcomputer. In addition, analog-digital converters require additional costs associated with ensuring the protection of the system from interference, creates a number of restrictions on the use of traditional measuring converters compatible with digital information processing tools. The use of a frequency signal as an informative parameter of primary transducers is characterized by high noise immunity, simplicity and high accuracy of conversion to digital code, and also by the convenience of switching in multi-channel measuring systems [1]. One of the new scientific directions for creating frequency transducers for gas concentration is the use of reactive properties of semiconductor elements with negative resistance. This makes it possible to convert the concentration of gas into a frequency output signal that provides high noise immunity, and, consequently, high accuracy of measuring the gas concentration [1–3]. Frequency transducers of gas concentration possess high sensitivity to measured parameters, low mass, dimensions, information, constructive and technological compatibility with

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microelectronic information processing facilities, which provides their advantage over existing gas concentration sensors [4–6]. Thus, it is necessary to develop frequency transducers of gas based on transistor structures with negative differential resistance, which allows to fully use the integrated technology for the manufacture of instruments for measuring the concentration of gases.

12.2

Theoretical and Experimental Research of Frequency Gas Concentration Transducers

The circuit of a microelectronic gas concentration sensor with a frequency output is shown in Fig. 12.1. The proposed scheme of a microelectronic gas concentration sensor is built on a transistor structure of three bipolar transistors on a single crystal HFA3046. The scheme on electrodes of the collector-emitter of the bipolar transistor VT3 and the base-emitter of the bipolar transistor VT2 have a volt-ampere characteristic with a declining area corresponding to the appearance of a negative differential resistance. The operating point of the autogenerator from direct current is selected on the falling area of the volt-ampere characteristics. The oscillating system of the autogenerator (Fig. 12.1) consists of the capacitance existing on the collector-emitter VT3 electrodes, capacitance C1 as well as the external inductance L1. The resistances R1-R3 provide the mode of operation of transistors VT1, VT2 and VT3 from direct current. The microelectronic gas concentration sensor operates as follows. The choice of a constant voltage source U1 is achieved by generating electrical oscillations of the auto generator. With the subsequent action of the gas concentration on the gas-sensitive resistor R2, its resistance changes, which results in the change in the equivalent capacity of the oscillatory circuit of the auto generator, which in turn changes the generation frequency. The transformation function and the sensitivity of a microelectronic gas concentration sensor are determined on the basis of an equivalent circuit, given in Fig. 12.2.

Fig. 12.1 Electrical circuit of the gas sensor with frequency output

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Fig. 12.2 Equivalent circuit of microelectronic gas concentration sensor

In the scheme (Fig. 12.2), the total inductance L includes the external inductance and inductance of the circuit leads, the capacitance Cekv includes the external capacitance C1 and internal capacitance of bipolar transistors VT1, VT2 and VT3. Resistance R contains the load resistance of the circuit and the resistance of the leads of the circuit. The equivalent scheme of the gas concentration sensor (Fig. 12.2) is described by the Kirchhoff equations. U 1 ¼ RiT þ L

diT þ U, dt

iT ¼ Cekv

dU þ I ðU Þ, dt

ð12:1Þ

of which the condition of the equilibrium operation of the circuit is determined. In the state of equilibrium circuits (U0, iT0) the currents and voltages in the circuit do not change, therefore diT =dtjiT ¼iT0 ¼ 0,

dU=dtjU¼U 0 ¼ 0:

ð12:2Þ

From condition (12.2) are determined U 1 ¼ iT0 R  U 0 ¼ 0,

iT0  I ðU 0 Þ ¼ 0:

ð12:3Þ

The state of the scheme in accordance with (3) is realized at the intersection point of the falling section of the volt-ampere characteristic and the load line I ðU 0 Þ ¼ ðU 1  U 0 Þ=R,

ð12:4Þ

which corresponds to the state of equilibrium of the investigated circuit. Dynamic mode of operation of the circuit is described by a differential equation of the second power, in which the variable voltage at the output of the circuit depends on the time. Its solution consists of two parts, which describe the periodic process whose amplitude increases in exponential law. The conditions for the occurrence of sinusoidal oscillations in the system are determined by inequalities.


 1=Rg C ekv þ R=L < 0,


 1=LC ekv R=Rg þ 1 > 0,

ð12:5Þ

where Rg is differential resistance at the operating point of the circuit; R is loss of resistance in the oscillatory system; Cekv is equivalent capacity of the oscillatory

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system; L is inductance of the oscillatory system. The resonant frequency, which depends on the change in gas concentration, is a sensor transformation function. It is determined on the basis of the zero reactive component of the complete input resistance of the circuit (Fig. 12.2) and has the form " #1=2 R2g C ekv ðC Þ 1 F ðC Þ ¼ : 1 L 2πRg Cekv ðCÞ

ð12:6Þ

The sensitivity of the frequency sensor of the gas is determined on the basis of expression (12.6) and is described by the equation

F

SCp

qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi   g dC ekv ðC Þ R C ekv ðC Þ  1 L dC 1 1 þ ¼ 2 2 πR2g C ekv ðC Þ

dCekv ðC Þ dC qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi: R2g C ekv ðC Þ πL 1 L

ð12:7Þ

In Fig. 12.3, the transformation function is given, that is the dependence of the resonance frequency on the concentration of gas C. As can be seen from the graph, the transformation function has a nonlinear character. Figure 12.4 presents the dependence of sensitivity of the sensor on the change in gas concentration. The analysis of the graph shows that the highest sensitivity of the device lies in the range of 100–200 ppm and is 110 Hz/ppm, and in the range from 500 to 1500 ppm is 65 Hz/ppm, the least sensitivity is 61 Hz/ppm in the range zone 1500–2500 ppm. To improve the sensitivity of the frequency transducer of the gas, the scheme of the autogenerator of the gas concentration converter is proposed, which is shown in Fig. 12.5. The scheme of the frequency converter of the concentration of gas with a concentration sensitive combustible gases MEMS resistive element of the MiCS 6814 consists of a bipolar and field two-gate transistor. The oscillatory circuit of

Fig. 12.3 Dependence of the frequency of generations on the concentration of gas

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Fig. 12.4 Dependence of sensitivity on gas concentration

Fig. 12.5 Circuit of frequency transducer of gas concentration

the device is realized on the basis of the inductance L1, capacitance C2 and capacitance on the collector-drain electrodes of the bipolar and field transistors VT1 and VT2, the supply of which is carried out by sources of the constant voltage U1 and U2 [7, 8]. To study the properties of the frequency transducer of gas concentration it is necessary to develop a mathematical model, which enables to obtain the dependence of active and reactive components of the output impedance of the transducer on gas concentration, analytic expression of the transfer function and sensitivity [10, 11]. The calculations parameters of the frequency transducer were performed using the equivalent circuits of bipolar transistor and MOSFET (Fig. 12.6). It is necessary to calculate the impedance on electrodes collector and drain of bipolar and MOS field-effect transistor VT1 and VT2 using equivalent circuit (Fig. 12.7) to determine the main parameters, describing the frequency transducer of gas concentration operation [9, 12]. Figure 12.7 shows the equivalent circuit of the frequency transducer of gas concentration for alternating current, transformed into more convenient for calculations. Volt-ampere characteristic of the transistor structure, on the basis of which the frequency converter of the gas concentration is created, has a negative resistance region (Fig. 12.8).

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Frequency Transducers of Gas Concentration Based on Transistor. . .

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Fig. 12.6 Equivalent circuit of transducer of gas concentration

The negative resistance compensates the losses in the tuned of oscillator, which is formed by the equivalent capacity of the electrodes collector-drain bipolar transistor VT1 and MOSFET VT2, and by external inductance [10–13]. The equivalent circuit (Fig. 12.6) uses symbols: R1 – resistance of MEMS resistive element MiCS 6814, sensitive to concentration of combustible gases; R2, R3, R5 – bulk resistances of emitter, collector and base of bipolar transistor VT1 respectively; R6, R15, R8 and R14– bulk resistances of source, drain, first and second gate of MOS transistors VT2 respectively; R7 – bulk resistance of gate-source of MOS transistor VT2; R8 – bulk resistance of gate of MOS transistor VT2; R9, R11 та R12 – bulk resistances of drain-source of MOS transistor VT2; R10 – resistance of substrate of MOS transistor VT2; R13 – resistance of gate-drain of MOS transistor VT2; R15 – resistance of p-n junction drain of MOS transistor VT2; C1 – capacity of capacitor C1; C2 – capacity of capacitor C2; C3 – capacity of MEMS resistive element MiCS 6814, sensitive to concentration of combustible gases; C4 – capacity between external term of base and collector of bipolar transistor VT1; C5, C6 – capacities of junctions base-collector and base-emitter of transistor VT1 respectively; C7 – capacity of substrate-source of MOS transistor VT2; C8 and C9 – capacities of substrate-drain of MOS transistor VT2; C10, C12and C11 – capacities

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Fig. 12.7 Transformed equivalent AC circuit of transducer of gas concentration

Fig. 12.8 Experimental static VAC frequency converter of gas concentration

of gate-drain of MOS transistor VT2; C13 – capacity between first and second gates MOS transistors VT2; L1 – external inductance. The following symbols are used to the transformed equivalent circuit (Fig. 12.7):

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169

R21 ωC 3 R1 j  j ; Z 2 ¼ R2 ; Z 3 ¼  ; 2 2 2 2 2 2 ωC 1 þ ω R1 C 3 1 þ ω R1 C 3 6 j j ; Z5 ¼  ; Z 6 ¼ R3 ; Z 7 ¼ jωL1 ; Z 8 ¼ R5 ; Z4 ¼  ωC 4 ωC 5 R27 ωC 12 j R7 ; Z 12 ¼  j ; Z 9 ¼ R6 ; Z 10 ¼ R9 ; Z 11 ¼  ωC 11 1 þ ω2 R27 C 212 1 þ ω2 R27 C 212 ; j j j ; Z 15 ¼  ; Z 16 ¼ R10 ; Z 17 ¼  ; Z 13 ¼ R8 ; Z 14 ¼  ωC7 ωC 8 ωC9 R213 ωC 10 R13 Z 18 ¼ R11 ; Z 19 ¼ R15 ; Z 20 ¼ R12 ; Z 21 ¼ j ; 2 2 2 1 þ ω R13 C 10 1 þ ω2 R213 C 210 j j j ; Z 23 ¼ R14 ; Z 24 ¼  ; Z 25 ¼  , Z 22 ¼  ωC13 ωC2 ωC 1

Z1 ¼

In order to receive the components of impedance, we have to solve the Kirchhoff’s system of equation for AC, obtained for the equivalent circuit shown in Fig. 12.7, using circuit node 0 as a basic (1): 8 0 ¼ ϕ1 ðy18 þ y19  y21 Þ  ϕ2 y19 þ ϕ7 y18 ; > > > > > I 8  I 5 ¼ ϕ1 y19  ϕ2 ðy19 þ y20 þ y17 þ y15 Þ þ ϕ3 y17 þ ϕ5 y15 ; > > > > > I 8 ¼ ϕ2 y17 þ ϕ3 ðy16  y17 Þ þ ϕ4 y16 ; > > > > > > I 6  I 1 ¼ ϕ2 y16  ϕ4 ðy16 þ y14 þ y12 þ y11 Þ þ ϕ5 y14 þ ϕ6 y12 þ ϕ7 y11 ; > > > > > I 5  I 4  I 6 ¼ ϕ2 y15 þ ϕ4 y14  ϕ5 ðy15  y13  y14 Þ þ ϕ6 y13 ; > > > < I þ I ¼ ϕ y þ ϕ y  ϕ ðy þ y þ y þ y Þ þ ϕ y þ ϕ y ; 4 8 4 12 5 13 6 13 12 10 9 7 13 8 9 ð12:8Þ > 0 ¼ ϕ1 y18 þ ϕ4 y11 þ ϕ6 y13  ϕ7 ðy10 þ y11 þ y2 þ y18 Þ þ U вих y2 > > > > > > I 2 þ I 3 ¼ ϕ6 y9  ϕ8 ð y9 þ y 4 Þ þ ϕ9 y4 ; > > > > ðI 2 þ I 1 Þ ¼ ϕ8 y4  ϕ9 ðy4 þ y7 þ y5 Þ þ ϕ11 y5 þ ϕ10 y7 ; > > > > > 0 ¼ ϕ9 y7 þ ϕ11 y6  ϕ10 ðy8 þ y7 þ y6 Þ; > > > > > > I 1  I 3  U вих y3 ¼ ϕ9 y5  ϕ11 ðy6 þ y5 þ y3 Þ þ ϕ10 y6 ; > > : U вих ðy3 þ y2 þ y1 Þ ¼ ϕ7 y2 þ ϕ11 y3 , where conductivity of the circuit branches are determined by the equations y1 ¼ 1=ðZ 24 þ Z 7 Þ; y2 ¼ 1=Z 13 ; y3 ¼ 1=Z 6 ; y4 ¼ 1=Z 3 ; y5 ¼ 1=Z 5 ; y6 ¼ 1=Z 4 ; y7 ¼ 1=Z 2 ; y8 ¼ 1=ðZ 25 þ Z 1 Þ; y9 ¼ 1=ðZ 8 þ Z 9 Þ; y10 ¼ 1=Z 12 ; y11 ¼ 1=Z 11 ; y12 ¼ 1=Z 10 ; y13 ¼ ðZ 16 þ Z 14 Þ=ðZ 16 Z 14 Þ; y14 ¼ 1=Z 15 ; y15 ¼ 1=Z 17 ; Y 16 ¼ 1=Z 18 ; y17 ¼ 1=Z 20 ; y18 ¼ 1=Z 22 ; y19 ¼ 1=Z 21 ;

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y20 ¼ 1=Z 19 ; y21 ¼ 1=Z 23 : Using the system of Eq. (12.8), active and reactive component of the impedance have been calculated in the software package MATLAB 7.11 [14]. Calculated and experimental dependences on the gas concentration are shown in Figs. 12.9 and 12.10, respectively. Graphs in Figs. 12.9 and 12.10 show that active and reactive impedance components increased with increasing gas concentration. Experimental dependencies of an active and reactive component of the impedance on the supply voltage U1 are shown in Figs. 12.11 and 12.12, respectively. The experimental dependencies of oscillation frequency of transducer of gas concentration on supply voltage U1and control voltage U2 are presented in Figs. 12.13 and 12.14 respectively. Figure 12.14 shows the optimal mode of the transducer’s operation by which the oscillation frequency depends linearly on the supply voltage. Such mode of the Fig. 12.9 Theoretical and experimental dependencies of active component of the impedance on gas concentration

Fig. 12.10 Theoretical and experimental dependencies of reactive component of the impedance on gas concentration

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171

Fig. 12.11 Experimental dependencies of active component of the impedance on the supply voltage of transducer

Fig. 12.12 Experimental dependencies of reactive component of the impedance on the supply voltage of transducer

transducer’s operation corresponds a voltage control 4,5. . .5 V. One can see in Fig. 12.14 that the oscillator has a stable oscillation within the range from 5 to 3 V and oscillation mode of the transducer of gas concentration must be selected within this range. The experimental and theoretical dependencies of oscillation frequencies of the transducer on the concentration of propane (С3H8) are presented in Fig. 12.15. At increasing of gas concentration the oscillation frequency is raised and the dependence of oscillation frequency on gas concentration change is more in range within from 1 to 2000 ppm. The theoretical values agree with experimental data to within better than 5%. The dependence of oscillation frequency on gas concentration (transfer function) is determined by the circuit reverse current in accordance with the equivalent circuit

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Fig. 12.13 Experimental dependencies of oscillation frequency on the supply voltage of transducer of gas concentration

F,kHz 2400 2000 1 - U2 = 3 V 2 - U2 = 3,5 V 3 - U2 = 4 V 4 - U2 = 4,5 V 5 - U2 = 5 V

1600 1

1200

2 3 800 4

5

400 1 1

1,4

1,8

2,2

2,6

3

3,4

3,8 U1,V

Fig. 12.14 Experimental dependencies of oscillation frequency on the control voltage of transducer of gas concentration

(Fig. 12.7) [15]. The transfer function of radio measuring transducer is described by formula (12.9) pffiffiffiqffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
 2 2 2 1 2 L1 C4 L1 C 4 þ R1 ðCÞC 3 þ R1 ðC ÞC 3 C 4 þ A F¼ , 2 L1 C3 C 4 R1 ðCÞ

ð12:9Þ

where qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi A ¼ L21 C 24 þ 2L1 C 23 C 4 R21 ðC Þ  2L1 C 24 C 3 R21 ðC Þ þ R41 ðC ÞC 43 þ D þ R41 ðC ÞC 23 C 24 ; B ¼ 2L1 C 24 C 3 R21 ðC Þ; D ¼ 2R41 ðCÞC 33 C 4 ; C – concentration of gas (ppm).

12

Frequency Transducers of Gas Concentration Based on Transistor. . .

Fig. 12.15 Theoretical and experimental dependencies of oscillation frequency of transducer on propane (С3H8) concentration change

F,kHz 1750

173

1

1500 1250 1000

2 3 exper. theor.

750

1 - U1 = 1 V 2 - U1 = 1,5 V 3 - U1 = 2,5 V U2 = 6 V

500 250 0 0

1000 2000 3000 4000 5000 6000 7000 8000 9000 C,ppm

The sensitivity of the measuring transducer of gas concentration with MEMS resistive element MiCS 6814, sensitive to concentration of combustible gases has been calculated using Eq. (12.9):          ∂R1 ðC Þ ∂R1 ðC Þ ∂R1 ðCÞ 1 pffiffiffi 1 2 2R1 ðC ÞC 23 4L1 R1 ðCÞ þ 2R1 ðC ÞC 3 C 4 þ  4 2 ∂C ∂C ∂C       ∂R1 ðC Þ ∂R1 ðC Þ ∂R1 ðC Þ C 4 C 23  4L1 R1 ðC ÞC24 C 3 þ 4R31 ðC ÞC 43 þ 8R31 ðE ÞC 33 C 4 þ ∂C ∂C ∂C  qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi  
pffiffiffiffiffiffi pffiffiffiffiffiffi ∂R1 ðC Þ 1 pffiffiffi L1 C 4 D2 þ D1 2 = D1 = þ4R31 ðC ÞC 23 C 24  2 ∂C   qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 
pffiffiffiffiffiffi ∂R1 ðCÞ
= L1 C4 C 3 R21 ðCÞ ,  L1 C 4 D2 þ D1 ∂C SFC ¼

ð12:10Þ where D1 ¼ L21 C24 þ 2L1 C 4 C 23 R21 ðC Þ  2L1 C 24 C 3 R21 ðCÞ þ R41 ðCÞC 43 þ 2R41 ðCÞC 33 C 4 þ 4 R1 ðCÞC 23 C 24 ; D2 ¼ L1 C 4 þ R21 ðC ÞC23 þ R21 ðC ÞC4 C3 . Figure 12.16 shows the dependence of the sensitivity of the frequency transducer on gas concentration. The graphs in Fig. 12.16 illustrate that the transducer of gas concentration with MEMS resistive element MiCS 6814 has maximum sensitivity for supply voltage 1 V and control voltage 6 V. The sensitivity is significantly reduced by increasing the concentration of propane. It changes from 175 to 48 Hz/ppm in the range 1500–7000 ppm. Let’s test of design model for adequacy by formula [16]. δм ¼

xM  xe  100 %, xe

ð12:11Þ

174 Fig. 12.16 The sensitivity of the transducer on gas concentration

A. V. Osadchuk and V. S. Osadchuk S2c , Hz/ppm 700 600

1 - U1 = 1 V 2 - U1 = 1,5 V 3 - U1 = 2,5 V U2 = 6 V

1 500 400

2

300

3

200 100 0

Fig. 12.17 Dependence of deviations of theoretical model on experimental values of gas concentration

0

1000 2000 3000 4000 5000 6000 7000 8000 C,ppm

δM, % 5.5 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0

0

1000 2000 3000 4000 5000 6000 7000 8000 9000 C,ppm

where xM – current value of the model; xe – current experimental value of the parameter. Figure 12.17 shows the dependence of deviations of theoretical model on experimental values of gas concentration. As it is visible (Fig. 12.17), the divergence of experimental and theoretical data is 5%. The dependencies of oscillator frequency of transducer of gas concentration on temperature, are presented in Fig. 12.18. One can see that oscillator frequency raises with increasing temperature. The optimal voltage control is 3 V, where there is the slightest change in the oscillation frequency in the range from 20 to 60  C. The construction of the frequency transducer of gas concentration in the form of an integrated circuit requires the use of a film technology for the manufacture of a

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Frequency Transducers of Gas Concentration Based on Transistor. . .

Fig. 12.18 Dependencies of oscillation frequency of the transducer of gas concentration on temperature

175

F,kHz 1800 1 - U2 = 6 V 2 - U2 = 5 V 3 - U2 = 4 V 4 - U2 = 3 V U1 = 2 V

1600 1400 1200

1

1000

2

800

3

600

4

400 200 20

30

40

50

60

70

80

90 T, C

Fig. 12.19 Electrical circuitry of the transducer on the basis of two bipolar transistors with active inductance

passive inductive element in the form of a spiral, but its quality factor is of little importance, and secondly, its dimensions at frequencies up to 106 Hz are incompatible with the dimensions of the integrated circuit of the transducer. Therefore, to solve this problem, it is suggested to use the inductive character of the impedance of a bipolar transistor with an RC circuit, which is easily implemented in the form of an integrated circuit [7]. Thus, the scheme of the frequency transducer of gas concentrations with an active inductive element is shown in Fig. 12.19. Bipolar transistors VT1, VT2 and VT3 realize the electric oscillation generator in which the oscillatory circuit is formed by the capacitive component of the impedance at the collectorcollector electrodes of the bipolar transistors VT1 and VT2 and the inductive component of the impedance at the electrodes of the emitter-collector of the bipolar transistor VT3. Thus, such a transducer circuit is fully realized in the form of an integrated circuit. The main parameters of the frequency transducer are the function of the conversion, that is, the dependence of the generation frequency on the change in the gas concentration and the equation of sensitivity. The transformation function is determined on the basis of an equivalent circuit (Fig. 12.20) with the calculation of the impedance on the electrodes of the collectorcollector VT1 and VT2 of the frequency transducer. An equivalent scheme

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Fig. 12.20 Equivalent circuit of a frequency transducer based on two bipolar transistors with active inductance

(Fig. 12.20) is converted into more convenient for conducting calculations (Fig. 12.21). The Kirchhoff equation system for AC has the form 9 > > > > > > > > > > > > > > > > 0 ¼ ðZ 18 þ Z 19 þ Z 17 Þi4  Z 19 i3 þ Z 18 i5 þ Z 17 i9  Z 17 I 9 þ Z 17 I 7 , > > > > 0 ¼ ðZ 15 þ Z 16 þ Z 18 þ Z 20 þ Z C Þi5  ðZ 15 þ Z 16 Þi9 þ Z 18 i4 þ Z 20 i3 þ Z C i1  Z 16 I 8  Z 16 I 7 , > > > > > 0 ¼ ðZ 4 þ Z 5 þ Z 6 þ Z 7 þ Z 8 þ Z 10 þ Z 12 þ Z 14 þ Z R3 Þi6 þ Z R3 i2  Z 6 i9 þ Z 4 i11 þ Z 4 I 1  > > > > = Z I  ðZ þ Z þ Z þ Z Þi  Z I  Z I  Z I  Z I þ Z i  Z i , U_ out ¼ ðZ C þ Z R5 Þi1  Z R5 i3 þ Z C i5 , U_ out ¼ ðZ R3 þ Z R4 Þi2 þ Z R3 i6 þ Z R4 i7 , 0 ¼ ðZ R5 þ Z 20 þ Z 19 þ Z 21 Þi3  Z R5 i1 þ Z 20 i5  Z 19 i4 þ Z 21 i9 ,

4 3

5

7

8

10

10

5 2

5 3

10 5

10 4

12 8

14 7

0 ¼ ðZ 9 þ Z 13 þ Z 14 þ Z R4 Þi7 þ Z R4 i2  Z 14 i6 þ Z 13 i8  Z 9 i10 , 0 ¼ ðZ 11 þ Z 12 þ Z 13 Þi8 þ Z 11 i10 þ Z 13 i7 þ Z 12 i6  Z 11 I 6 þ Z 11 I 4 , 0 ¼ ðZ R1 þ Z 1 þ Z 2 þ Z 6 þ Z 15 þ Z 16 þ Z 17 þ Z 21 Þi9  Z 1 i10  Z 6 i6 þ þZ 2 i11  ðZ 15 þ Z 16 Þi5 þ Z 17 i4 þ Z 21 i3 þ Z 16 I 8 þ Z 16 I 7  Z 17 I 9 þ Z 17 I 7 , 0 ¼ ðZ 1 þ Z 3 þ Z 5 þ Z 7 þ Z 8 þ Z 10 þ Z 11 þ Z 9 þ Z R2 þ Z RГ Þi10  Z 1 i9 þ Z 3 i11  ðZ 5 þ þZ 7 þ Z 8 þ Z 10 Þi6 þ Z 5 I 2 þ Z 5 I 3 þ Z 10 I 5 þ Z 10 I 4  Z 11 I 6 þ Z 11 I 4 þ Z 11 i8  Z 9 i7 , 0 ¼ ðZ 2 þ Z 3 þ Z 4 Þi11 þ Z 2 i9 þ Z 4 i6 þ Z 3 i10 þ Z 4 I 1  Z 4 I 3 ,

> > > > > > > > > > > > > > > > > > > > > > > > > > > > > ;

ð12:12Þ

where

12

Frequency Transducers of Gas Concentration Based on Transistor. . .

177

Fig. 12.21 Transformed nonlinear equivalent circuit of a frequency transducer based on two bipolar transistors with active inductance

ZR1 ¼ R1, Z 1 ¼ R0b1 þ jωLb1 , Z2 ¼  j/(ωCbx1), Z3 ¼ Rb1, Z4 ¼  j/(ωCbc1), Z5 ¼  j/(ωCbe1), Z 6 ¼ Rc1 þ R0c1 þ jωLc1 , Z 7 ¼ Re1 þ R0e1 þ jωLe1 , Z 8 ¼ Re2 þ R0e2 þ jωLe2 , Z 9 ¼ Rc2 þ R0c2 þ jωLc2 , Z10 ¼  j/(ωCbe2), Z11 ¼  j/ (ωCbc2), Z12 ¼ Rb2, Z13 ¼  j/(ωCbx2), Z 14 ¼ R0b2 þ jωLb2 , Z 15 ¼ Re3 þ R0e3 þ jωLe3 , Z16 ¼  j/(ωCbe3), Z17 ¼  j/(ωCbc3), Z18 ¼ Rb3, Z19 ¼  j/(ωCbx3), Z 20 ¼ R0b3 þ jωLb3 , Z 21 ¼ Rc3 þ R0c3 þ jωLc3 , ZR2 ¼ R2, ZR3 ¼ R3, ZR4 ¼ R4, ZR5 ¼ R5, Z C ¼ j=ðωCÞ, Z RG ¼ RΣ =1 þ ω2 R2Σ C 2HG  jR2Σ ωC HG =1 þ ω2 R2Σ C 2HG , RΣ ¼ RG  RHG/RG + RHG. The system of equations (12) is solved on a personal computer with using the package of applications Matlab 7.11, which allowed to obtain the value of the impedance, the active component of which has a negative value, and the reactive is capacitive character. In Fig. 12.22 the theoretical and experimental dependence of the active component on the supply voltage at different values of the control voltage is given. An increase in the supply voltage of more than 9 V (U2¼ 3.5 V) leads to a lower dependence of the active resistance from U1, and in the area from 9 to 11 V has almost linear dependence. Figure 12.23 shows the theoretical and experimental dependence of the reactive component of the impedance from the supply voltage. As it is seen from the graph that with increasing U1 from 8.5 to 12.5 V (U2¼ 4 V), the reactive component increases to a greater extent than from 12.5 to 14 V.

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Fig. 12.22 Theoretical and experimental dependence of the active component of the impedance of the supply voltage

R(–), Om 12000

theor. exper.

10000 8000 6000 1

2

3

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2000 0

2

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1-U2 = 2 V 2-U2 = 2,5 V 3-U2 = 3 V 4-U2 = 3,5 V 5-U2 = 4 V 6-U2 = 4,5 V

16

18 T, C

In Fig. 12.24 the dependence of the generation frequency on the supply voltage at different voltage control is presented. From the graphs presented, it is seen that increasing control voltage increases the frequency region of generation. Experimental dependence of the generation frequency on the voltage of control at different voltage supply is shown in Fig. 12.25. At a power supply of 5.5 V, the dependence is almost linear. Therefore, the 5.5 V value for the supply voltage is optimal. Figure 12.26 shows the dependence of the generation frequency on the concentration of gas. As you can see from the graph, the best dependence on the transformation function can be obtained if the supply voltage is equal to 5.5 V. As a gas sensitive element, the resistive sensor of the firm Figaro (Japan) was used. Figures 12.27 and 12.28 show the dependencies of the generation frequency on the propane gas concentrations, which were removed using sensors of the ACHE production type in Ukraine and the UST firm (Germany). The dependence of the generation frequency on the gas concentrations is determined by the feedback loop according to the equivalent circuit (Fig. 12.21). The transformation function is described by the expression vffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi u uA1 þ A2 þ 4R2 CC bx1 RG ðC Þ2 C 2 Cbx2 ðC bx1 þ C bx2 Þ t HG 1 5 1 F¼ , 2 2 2π 2R5 CC bx1 RG ðCÞ C2HG C bx2

ð12:13Þ

where A1 ¼ RG ðC Þ2 C bx2 C 2HG þ R25 C HG C bx1 C bx2 þ Cbx1 RG ðC Þ2 C 2HG  R25 CCbx1 Cbx2 : The sensitivity of the transducer is determined on the basis of expression (12.13) and is described by the equation

12

Frequency Transducers of Gas Concentration Based on Transistor. . .

Fig. 12.23 Theoretical and experimental dependence of the reactive component of the impedance from the supply voltage U1

179

X, Om 4500 4000

1-U2 = 2 V 2-U2 = 2,5 V 3-U2 = 3 V 4-U2 = 3,5 V 5-U2 = 4 V 6-U2 = 4,5 V

1

3500 3000

2

2500

3

2000

4

1500

5

1000 500

Fig. 12.24 Experimental dependence of generation frequency on voltage U1 at various voltage control

6

theor. exper. 2

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6

8

10

12

14

16

18 U1, V

14

16

18 U1, V

F, Hz × 105 16 1-U2 = 2,5 V 2-U2 = 3 V 3-U2 = 3,5 V 4-U2 = 4 V 5-U2 = 4,5 V

14 12

5

4

10 3

8 2 6 1

4 2

2

4

6

8

10

12

180 Fig. 12.25 Experimental dependence of generation frequency on voltage of control U2 at different power supply voltages

A. V. Osadchuk and V. S. Osadchuk F, Hz × 105

11

1-U1 = 4,5 V 2-U1 = 5 V 3-U1 = 5,5 V

10 9 8 7 6

1

5

2

4

3

3 2

Fig. 12.26 Theoretical and experimental dependence of the generation frequency on the concentrations of methane gas

2

2.5

F, Hz × 105 11 CH4 10 9

3

3.5 U2, V

U1 = 6 V U1 = 5,5 V

8 7

U1 = 5 V

6 5 theor. exper.

4 3

2

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 C, ppm

12

Frequency Transducers of Gas Concentration Based on Transistor. . .

Fig. 12.27 Theoretical and experimental dependences of the frequency of generations on the concentrations of propane (a sensitive element of the company ACHE, Ukraine) at different voltage levels

181

F, Hz × 105 4.5 U1 = 6 V

4

U1 = 5,5 V

3.5 3

U1 = 5 V

2.5 2 C3H8 theor. exper.

1.5 1

Fig. 12.28 Theoretical and experimental dependences of the frequency of generations on the concentrations of propane (a sensory element of the firm UST, Germany) at different voltage levels

0

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 C,ppm

F, Hz × 105 9 C3H8

8

theor. exper.

7

U1 = 6 V U1 = 5,5 V

6

U1 = 5 V

5 4 3

0

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 C,ppm

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Fig. 12.29 Dependence of sensitivity on gas concentration

    ∂RG ðCÞ ∂RHG ðCÞ 2Cbx2 C 2HG RG ðC Þ þ 2C bx1 C2HG RG ðC Þ þ ∂C ∂C     ∂RG ðC Þ ∂RG ðCÞ 1 þ 2Cbx1 C 2HG RG ðCÞ þ þ ð2B1 ð2C bx2 C2HG RG ðC Þ 2 ∂C ∂C    pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 ∂RG ðCÞ 2 2 þ8B2  = B1 þ 4B2 =ðR5 CC bx1 C bx2 C HG RG ðC Þ  ∂C 1 0 vffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi1 qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ∂RG ðC Þ u 2 2B1 þ B1 þ 4B2 u B þ B21 þ 4B2 C 1 ∂C t C C=B π  @ A , R25 CC bx1 C bx2 C2HG RG ðC Þ2 R25 CC bx1 C bx2 C2HG RG ðC Þ3 A

SFC ¼

1 pffiffiffi 2 8



ð12:14Þ where B1 ¼ RG ðCÞ2 Cbx2 C 2HG þ R25 C HG C bx1 Cbx2 þ C bx1 RG ðC Þ2 C 2HG  R25 CC bx1 C bx2 , B2 ¼ R25 ðCbx1 þ C bx2 ÞCbx1 C bx2 C2HG CRG ðC Þ2 : The graph of the sensitivity dependence on the concentration of gas is shown in Fig. 12.29. According to the schedule, the highest sensitivity of the device ranges from 100 to 300 ppm and has a value of 500 Hz/ppm, and at values of concentration from 300 to 1000 ppm it assumes a value of 260 Hz/ppm. The range from 1000 to 5000 ppm is 115 Hz/ppm.

12

Frequency Transducers of Gas Concentration Based on Transistor. . .

12.3

183

Conclusion

The possibility of direct conversion of gas concentration into a frequency signal based on autogenerator transducers constructed on transistor structures with negative differential resistance is shown. Proposed and investigated transducers of gas concentration with a negative differential resistance on the basis of three bipolar transistors, bipolar and two-gate MOSFET transistors, two bipolar transistors with active inductive element of the oscillatory circuit. The analytical dependences of the transformation function and the sensitivity equation of the frequency transducers of gas concentration are obtained. Theoretical and experimental investigations have shown that the sensitivity of sensors are from 100 Hz/ppm to 600 Hz/ppm.

References 1. Microelectronic sensors of physical quantities. Edited Z.Yu. Hotra. In 3 volumes. – Lvov: League-Press, 2003. Vol.2 2. Novitsky PV, Knoring VG, Gutnikov VS (1970) Digital devices with frequency sensors. Energy, Leningrad 3. Gan K-J, Liang D-S, Hsiao C-C, Tsai C-S, Chen Y-H (2005) Investigation of MOS-NDR Voltage Controlled Ring Oscillator Fabricated by CMOS Process. In: 2005 IEEE Conference on Electron Devices and Solid-State Circuits, pp. 825–827. https://doi.org/10.1109/EDSSC. 2005.1635405 4. Gan K-J, Chun K-Y, Yeh W-K (2015) Design of Dynamic Frequency Divider using Negative Differential Resistance Circuit. Int J Rec Innov Trends Comp Commun 3(8):5224–5228 5. Núñez J, Avedillo MJ, Quintana JM (2012) Bifurcation diagrams in MOS-NDR frequency divider circuits. In: 2012 19th IEEE International Conference on Electronics, Circuits, and Systems (ICECS 2012), Seville, pp. 480–483. https://doi.org/10.1109/ICECS.2012.6463558 6. Liang DS, Gan KJ, Chun KY (2010) Frequency divider design using the Λ-type negativedifferential-resistance circuit. In: 2010 53rd IEEE International Midwest Symposium on Circuits and Systems, Seattle, WA, pp. 969–972. https://doi.org/10.1109/MWSCAS.2010. 5548795 7. Osadchuk AV, Osadchuk VS (2015) Radiomeasuring Microelectronic Transducers of Physical Quantities. In: 2015 Proceedings of the International Siberian Conference on Control and Communications (SIBCON). 21–23 May 2015. Omsk. 978-1-4799-7103-9/15. https://doi. org/10.1109/SIBCON.2015.7147167 8. Osadchuk VS, Osadchuk OV (1999) Reactive properties of transistors and transistor circuits. UNIVERSUM-Vinnitsa, Vinnitsa 9. Vikulin IM, Stafeev VI (1990) Physics of semiconductor devices. Moscow: radio and. Communication 10. Osadchuk VS, Osadchuk AV, Yushchenko YA (2008), Radiomeasuring thermal flowmeter of gas on the basis of transistor structure with negative resistance. Elektronika ir Elektrotechnika. Kaunas: Technologija. №8(84). pp. 89–93 11. Osadchuk VS, Osadchuk AV (2011) The magneticreactive effect in transistors for construction transducers of magnetic field. Elektronika ir Elektrotechnika. Kaunas: Technologija. №3(109). pp.119–122

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12. Andrzej Smolarz OV, Osadchuk DP, Dudnyk RV, Krynochkin WW, Iskakova A (2013) Mathematical model of radiation interaction with gas. In: Procceeding of SPIE 8698, optical fibers and their applications 2012, 86980U; https://doi.org/10.1117/12.2019734 13. Osadchuk O, Osadchuk V, Osadchuk I (2016) The generator of superhigh frequencies on the basis silicon germanium heterojunction bipolar transistors. In: 2016 13th International Conference on Modern Problems of Radio Engineering, Telecommunications and Computer Science (TCSET), Lviv, pp. 336–338. https://doi.org/10.1109/TCSET.2016.7452051 14. Dyakonov VP (2010) Matlab R2006/2007/2008. Simulink 5/6/7. Basics of application. Moskow, Solon 15. Kayatskas AA (1988) Basics of electronics. Executive. wk., Moskow 16. Mirsky GY (1986) Electronic measurements. Radio and Communication, Moscow

Chapter 13

Chemical and Biological Defense in the South-Eastern European Countries L. D. Galatchi

Abstract In terms of preventing or reducing the mass disaster caused by chemical and biological warfare agents, establishing an efficient chemical and biological defense system is vital. South-East European countries are located in the “hot region” where some of the neighboring countries have had a chemical and biological weapons production program or do not comply with the international treaties related to the prohibition of chemical and biological weapons. On the other hand, setting up the chemical and biological defense is difficult and requires excessive expenditure, which causes a large economic hardship. The formation of a chemical and biological defense system in the South-East European countries would prevent the chemical and biological weapons threat in this region, and in addition, would be able to make a contribution to global security. Keywords South-Eastern Europe · Chemical-biological weapons · Threat · Security system · Defense

13.1

Introduction

Chemical and biological (CB) weapons (CBWs) are weapons of mass destruction (WMD) that have similar and different damaging effects. Generally, these weapons are easily produced, but chemical weapons (CWs) have immediate effects, contrary to biological weapons (BWs) [1]. Defense issues against WMD are rather complex and need a huge contribution of money and resources. Serious work would require highly qualified specialists in various fields, expensive protective and monitoring equipment, complicated and extensive laboratory research, and international support and collaboration over a long period of time (Fig. 13.1). The existence of unexplained environmental, mass casualties and unnatural disease outbreaks are the main indicators of a CB attack (Fig. 13.2). L. D. Galatchi (*) Department of Natural Sciences, Ovidius University of Constanta, Constanta, Romania © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_13

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Requirements

highly qualified specialists in various fields

expensive protective and monitoring equipment

complicated and extensive laboratory research

international support and collaboration over a long period of time

Fig. 13.1 General requirements for defense work against WMD

Indicators

the existence of unexplained environmental and mass casualties

unnatural disease outbreaks

Fig. 13.2 Main indicators of a CB attack

Sources of CB threats

military issues

acts of terrorism

industrial accidents

Fig. 13.3 Sources of threats from CB agents

The threat from CB agents should not only be considered as a military issue, but also as an act of terrorism. In addition, industrial accidents may be included in this dangerous situation (Fig. 13.3). Therefore, it should be noted that environment and civilians may also be exposed to these agents. There is an increasing amount of concern over the possibility of terrorist use of biological agents, including bacteria, viruses, and toxins, in recent times [2]. Finally, the terrorist events in the last decade intensified the interest in CB terrorism and the necessity of multilateral cooperation regarding a CB defense (CBD) policy. Because the use of biological agents is not always initially evident (contrary to chemical agents), the outbreak of diseases on different species may provide the first indication of an attack [3]. Although at least 25 nations are currently suspected of possessing or attempting to acquire WMD, it may be probable that any of them would launch a military action with these weapons against South-East

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Fig. 13.4 Map of SEE countries [6]

European (SEE) countries (Fig. 13.4), including Greece, Bulgaria and especially Romania and Turkey (which are actively involved in NATO operations) [4, 5]. Thus, collaboration between the SEE countries against CB terrorism has to be taken into consideration with great effort.

13.2

Experimental

In the event involving such CB agents, effective management has to include a rapid and coordinated response from local, state, and military foundations. Related issues in disasters caused by CB assault may be assessed in the covering preparedness, which includes the education and training of emergency personnel in disaster planning, public education, the deployment of specialized rescue teams, and stockpiling of appropriate antidotes and vaccines (Fig. 13.5). Rapid response to such attacks involves timely administration of antidotes or vaccines and antibiotics. Establishing the CBD against a CB threat (CBT) is vital for preventing and reducing environmental and mass disaster. Therefore, environmental and medical

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Covering preparedness

education and training of emergency personnel in disaster planning

public education

deployment of specialized rescue teams

Stockpiling of appropriate antidotes and vaccines

Fig. 13.5 The covering preparedness in disasters caused by CB assault

Basics of a CBD against a CBT

environmental and medical preparedness response plan

Fig. 13.6 Basics of a CBD against a CBT, for preventing and reducing mass disaster

preparedness, and a response plan must be developed in advance by the environmentalists, and biological, chemical, and medical nuclear (NBC) experts (Fig. 13.6).

13.3

Results and Discussion

The current capabilities of SEE countries to respond to CB incidents must be expanded and developed to meet the nowadays challenges. To effectively cope with these agents, these countries must address their emergency environmental, public health, and medical issues during preparedness and response activities (Fig. 13.7). To ensure that SEE countries are appropriately prepared for an attack with CBWs, a Defense Act against WMD must be established and a special budget must be funded by the governments to conduct training programs and exercises for environmental, pre-hospital, medical, and civil defense personnel as determined by the authorities of each government. Each country should carry a responsibility in this Defense System and this assignment should be explained in this official Act in detail. It is essential that this collaboration be conducted in parallel with the national response plans. Issues of special interest to CB incidents consist of command and control, scene assessment, environmental and medical stockpile, triage, decontamination, population evacuation, patient treatment, and evacuation, and these issues should be addressed in detail. Appropriate instructional methods for public education include community seminars, delivery of publications, presentations on radio

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Fig. 13.7 Preparing for CB incidents in SEE countries

and television, multimedia products, and internet services etc. A specialized response team must be established and should consist of people from each country who are skilled in area isolation, agent detection and identification, environment and patient decontamination, and medical support. Periodic meetings and trainings

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should be developed with the members who will be the first responded for mass casualty incidents [2]. These meetings should be used to create a shared understanding of the different cultures between environmental and health care, public safety, and law enforcement organizations. They also should provide the opportunity to build a mutual action in the developing of a defense for the potential chaotic status of an environmental and mass casualty incident [7]. In terms of laboratory preparedness and response improvement, a laboratory response network should be created for the detection and diagnosis of casualties based on laboratory capacity and the degree of risk. Establishing the CBD against CBT is vital for preventing environmental and mass disaster. Despite the difficulties at setting up the CBD, the required protective measures should be taken at the international level as soon as possible. Although no accurate protective measures against a biological attack can be put into practice because of the characteristics and variability of BWs, all of the required measures must have been put into practice in terms of minimizing the catastrophic effects of CBWs. The main threats occur on humans. Prophylactic and immunization precautions like a vaccination program and establishing the warning-reporting system on epidemiological investigation would constitute the most important dimension of biological defense. In addition to these measures, international disarmament and inspection regimens may prevent the production and dissemination of CBWs and also CW attacks (Fig. 13.8). In a disaster, especially with mass casualties, hospitals may receive more patients than they can handle. If the incident results from CB exposure, the community may also need to protect itself by designating some hospitals as opened to victims because CB casualties may need specific and sophisticated hospitals with specific medical applications like decontamination and antidote administration. In addition, CB casualties can also contaminate the environment and other unaffected people unless these casualties are decontaminated and triaged for treatment priorities in specific departments of hospitals.

vaccination program

The most important dimension of biological defense on humans

establishing the warning-reporting system on epidemiological investigation international disarmament

inspection regimens

Fig. 13.8 The most important dimension of biological defense on humans

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environmental and medical rescue team reference laboratories SEE CB Advisory Committee of experts center of stockpiling environmental impact and disease surveillance system

Fig. 13.9 Crucial initial steps based on the recommendations of the SEE CB Advisory Committee of experts

In the case of a chemical attack, an immediate response is significant in terms of reducing death and injury. Accordingly, environmental and medical care and management of chemical injuries are different from those involved in biological casualties from BW. Against the CBT, regional collaboration and cooperation is more needed as opposed to an international large-scale arena. Collaboration between SEE countries against this threat would be able to provide security in this region and could prevent CB terrorism effectively. How should this be done at the level of collaboration? First of all, there would be a necessity for the establishment of a SEE CB Advisory Committee consisting of CB experts who are able to create a common BC defense policy and prepare the operational plans that provide security within the SEE region. According to the recommendations and orders of this committee, crucial initial steps might be taken as soon as possible, which would include training and establishing an environmental and medical rescue team, reference laboratories, a center of stockpiling, an environmental impact and disease surveillance system etc. (Fig. 13.9). Training of environmental and medical personnel who will be in charge of a mission against CBT on the environmental and medical preparedness and response to a CB attack must be held with the highest priority by the SEE countries and must be realized through courses or similar activities to be organized. In this connection, a BC institute established in any SEE country as a training and educational center, would be able to contribute to the development of a CBD system in the region [5]. In the case of a CB assault on any SEE country, an environmental and medical rescue team that can be mobilized within a short time will be needed to reduce the destructive effects of a CB attack. The team should consist of the most experienced environmentalists and medical and paramedical personnel for decontamination and first aid, medical management and treatment, and these people should be tasked in

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the environmental, respectively medical BC Defense Departments of SEE countries. These teams must have capabilities concerning joint operational movement in cooperation with one another. Owing to the importance of the detection and identification of CBWs, it would be necessary to establish a reference laboratory in any available place of this region. The laboratory should be designed and equipped with enough experienced personnel and sophisticated instruments to accomplish analysis and identification of CB agents completely. Laboratories will play an important role in providing rapid identification of the agent involved, which will influence the type of treatment. In the covering of BC defense for humans, prophylactic and protective measures, including a vaccination program to ensure the antidote and antibiotic stockpiles and provide protective equipment etc., might be taken by SEE countries with each other’s cooperation. Because of their high costs, centers of stockpiling, including protective equipment and medical materials related to a CBD system may be set up in this region. This would be an attempt not only to prevent extra expenditures, but also to obviate the economic burden on the SEE countries. On the other hand, protective equipment (used both for environment or human protection) that has completed its shelf life could be used in training activities and exercises. To overcome and control epidemiological disease outbreak caused by particularly rough states or terrorists, surveillance and reporting system must have been constituted in the SEE region by state and local environmental and health organizations. Therefore, a biological attack performed covertly and deliberately will be uncovered as quickly as possible, and at the same time, environmental and medical response can be launched effectively. With CBD established among SEE countries, not only will the safety of this region be provided, but also the other regions close to it. Through the setting up of the CBD of the SEE region, there will be a requirement to choose and determine the strategic provinces in this region for the strongest CBD possible. In particular, true determination of the provinces in the SEE countries is significant in terms of a center for stockpiling location and rescue teams established.

13.4

Conclusion

A well-established CBD system in the SEE countries would provide security not only in the South-East region of Europe, but also in the other neighboring countries. This attempt, at the same time, can prevent and reduce excessive CBD expenditure and, possibly, the extra burden on the economical budget of many countries. Taking into consideration that the threat will never disappear, environmental and medical services must maintain their ability to manage large-scale CB attacks that require continual training and awareness.

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193

References 1. Galatchi LD (2006) Environmental risk assessment. In: Linkov F, LaPorte R (eds) Scientific networking and the global health network super-course, NATO security through science series: information and communication security, Vol. 5. IOS Press, Amsterdam/Berlin/Oxford/ Tokyo/Washington, DC, pp 151–157 2. Galatchi LD (2009) Global environmental change and the international efforts concerning environmental conservation. In: Liotta PH, Mouat DA, Kepner WG, Lancaster JM (eds) Environmental change and human security: recognizing and acting on hazard impacts. Springer, Dordrecht, pp 103–115 3. Antipov AL, Trufaniv AI (2010) Model of the adaptive hierarchical information security system. In: Trufanov A, Rossodivita A, Guidotti M (eds) Pandemics and bioterrorism, Science series – E: human and societal Dinamics, Vol. 62. IOS Press, Washington, DC, pp 171–177 4. Galatchi LD (2007) Developing highly effective environmental security policies for a sustainable development of the future. Case study: Romania. In: Hull RN, Barbu C-H, Goncharova N (eds) Strategies to Enhance Environmental Security in Transition Countries, Science series – C: environmental security. Springer, Dordrecht, pp 27–34 5. Galatchi LD (2006) The Romanian national accidental and intentional polluted water management system. In: Dura G, Kambourova V, Simeonova F (eds) Management of intentional and accidental water pollution, Science series – C: environmental security, Vol. 11. Springer, Dordrecht, pp 181–184 6. http://www.theodora.com/maps, 25.03.2018 7. Talshinsky R, Azmi R, Adlas R, Kedars U, Bakanidze S, Linn S, Rossodivita A, Shishani K, Busmane M, Grabauskas V, Jankauskas D, Mireckas V, Obrikis R, Sliaupa S, Strakuviene S, Vaitkaitis D, Zukauskas G, Galatchi LD, Puchkina N, Shubnikov E, Trufanov A, Ghannem H, Ozden YI, Onale AE, Gudzenko N, Ledoshchuk B, Vynograd N, Dorman J, LaPorte R, Linkov F, Noji E, Powell J, Rumm P, Tseytlin E, Volz C (2006) Constructing a NATO SuperCourse. In: Linkov F, LaPorte R (eds) Scientific Networking and the Global Health Network Super-Course, NATO Security through Science Series: Information and Communication Security, Vol. 5. IOS Press, Amsterdam/Berlin/Oxford/Tokyo/Washington, DC, pp 12–27

Chapter 14

Smart Surface with Ferromagnetic Properties for Eco- and Bioanalytics M. Pajewska-Szmyt, R. Gadzała-Kopciuch, A. Sidorenko, and Bogusław Buszewski

Abstract This chapter provides a brief overview of the literature about the use of magnetic particles. Particularly for eco- and bioanalytics as a sorbents to sample preparation, which can be applied to wide variety of target compounds from complex organic matrices. There are many ways to synthesize magnetic nanoparticles e.g. co-precipitation, sol-gel, microemulsion or sonochemical reactions. It is very important to stabilize these particles by immobilization of the layer on the magnetic core. Furthermore, it is possible to performed a lot of modification e.g. attached of functional groups onto the surface or imprinting the compound molecule. This made the magnetic nanoparticle as a selective and specific tool for analytical applications. This materials have a lot of advantages such as simple synthesis and possibility of reusing, however it is also some disadvantages e.g. necessity to synthesize monodispersive nanoparticles. Nonetheless the popularity of the magnetic materials have an increasing trend in various application. Keywords Ferromagnetic materials · Magnetic nanoparticles · Magnetic molecular imprinted polymers · Sample preparation

M. Pajewska-Szmyt · R. Gadzała-Kopciuch · B. Buszewski (*) Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Toruń, Poland Interdisciplinary Centre for Modern Technologies, Nicolaus Copernicus University, Toruń, Poland e-mail: [email protected] A. Sidorenko D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_14

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Introduction

The development of science and the constant insufficiency of the obtained answers lead to challenges undertaken by researchers in order to isolate and determine biologically active compounds (potential markers or precursors of cancer) on increasingly lower levels of concentration. Their isolation from matrices of complex composition (proteins, fats and other co-existing compounds) and those characterized by high heterogeneousness (biological samples: tissues, blood plasma, urine) requires application of selective and specific methods of sample preparation by extraction and chromatographic techniques [1–4]. Application such materials packing for solid phase extraction or/and preparation as well as flash chromatography possess number of advantage. However, the stage of purifying of the obtained extracts from these complex matrices and enrichment of the analyte have the greatest influence on obtaining reliable and conclusive final results. It is of utmost importance, particularly in the case of such sensitive technique as the mass spectrometry where enrichment of analyte which is only in trace amounts and removing the interference substances coming from the matrix is a crucial step for determination of selected compounds. Removing co-existing compounds from the sample and isolation of analytes requires the application of an effective extraction process. High efficiency of analyte purification and satisfactory recovery values of the isolated and enriched analytes can be obtained by using a new selective sorbents [1]. While observing the trends in the field of sample preparation methods (Fig. 14.1), one can notice a clear predominance of articles devoted to search for unique adsorbents such as polymers or magnetic polymers with imprinted molecules, nanotubes or/and nanoparticles.

Fig. 14.1 Evolutions of the articles published in magnetic sorbents field. The results were obtained from Scopus (www.scopus.com) search (May, 31st, 2017) using terms magnetic sorbent

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Magnetism

Magnetism is a phenomenon caused by movement of electrically charged molecules, and the magnetic dipole created by spinning, electrically charged molecule is known as magneton. Magnetons are clustered in groups in ferromagnetic materials. Magnetized areas in ferromagnetic materials are called magnetic domains and they determine the magnetic properties of a given material. If the dimensions of the ferromagnetic material is reduced below the critical value, the creation of such magnetic domain is disadvantageous. However, reduction of their size leads to formation of superparamagnetic particles (ranging in size from 1 to 30 nm) (Fig. 14.2) [2–5]. The group of elements which display ferromagnetic properties contains metals i.e. Fe, Co or Ni. Placing a solution/suspension containing magnetic particles near a magnetic field enables their isolation from the solution. The magnetic properties of a given material are connected with, among other things, the size and shape of the particles/molecules, therefore, it regards materials in nano scale. It is desirable to obtain particles which have large surface area and display superparamagnetic properties. Thanks to it, they are susceptible to the action of the magnetic field, however, this phenomenon is not durable, as it ceases when the external/outer magnetic field is removed [6].

14.3

Obtaining Materials with Magnetic Properties and Their Modifications

Iron oxide Fe3O4 and γ-Fe2O3 is a widely used ferromagnetic material. It owes such great interest not only to its magnetic properties but also to low toxicity and simplicity of its synthesis (Fig. 14.3). Currently, in order to obtain magnetic

Fig. 14.2 Multi and single domain particle

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Fig. 14.3 Scheme of synthesis of magnetic molecular imprinted polymers

Table 14.1 Methods of synthesis of magnetic nanoparticles co-precipitation

Sol-gel

Microemulsion

Thermal decomposition Sonochemical reactions Flow injection synthesis

Chemical reaction occuring in alkaline environment through stechiometric reaction of iron II and III salts. Fe2+ + 2Fe3+ +8OH - > Fe3O4 + 4H2O The obtained Fe3O4 (in surrounding conditions) may be oxidized to γ-Fe2O3, which is also a ferromagnetic material. Nanometric „sol” particles placed in solution are subjected to hydroxylation and condensation. The unlimited polymerisation leads to creation a 3-dimensional network of metal oxide dominated by wet gel. Microemulsion is a thermodynamically stable system consisting of at least 3 components, including two non-mixable ones (usually water and oil) and a surfactant. Each drop is a nanoreactor of a kind, in which the processes of nucleationcan take place, as well as particle growth in the environment Decomposition of organic iron precursors in higher temperature e.g. Fe (CO)5 and oxidation lead to formation of monodispersive particles of γ-Fe2O3. By using ultrasounds of high intensity, the volatile organometalic compounds of iron precursor Fe(CO)5, which are located inside cavitational bubbles, disintegrate in the presence of a stabilizer forming iron coloids. In a capillary reactor, in the conditions of laminar flow, a continuous or segmented mixing of reagents takes place.

nanoparticles, the synthesis is performed through: co-precipitation, sol-gel, microemulsions, sonochemical reactions, electrospray synthesis, thermal decomposition (Table 14.1) [6–8]. Regardless of the choice of nanoparticles synthesis, it is crucial to ensure that monodispersive particles are obtained, as the size of the synthesized particles, as well as their shape, are closely linked to their magnetic properties. They are also affected

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Fig. 14.4 Possible protection materials (PEG- polyethylene glicol; PVA-polyvinyl alcohol; PLA-polyethylene glycol; PAA-polyacrylic acid; PMMA- polymethylmethacrylate)

by structural defects and contamination. However, co-precipitation is most frequently used dues to its low cost, short time of the synthesis and the fact that it is the least harmful to the environment [7]. Because the obtained particles aggregate, they must be separated from each other (agglomeration effect). For this reason, they are usually coated with such materials as: silica, carbon, polymers or precious metals (Fig. 14.4). Additionally, particularly with application for biological samples, the obtained ferromagnetic particles may be appropriately functionalized by attaching specific functional groups or imprinting the determined particle (template) or its fragment in the obtained material [9] (Fig. 14.5). In order to avoid aggregation of the obtained magnetic particles, oxidation by oxygen, or erosion caused by alkali and acids, their stabilization must be ensured [7]. This can be performed in two ways. In the first method, an organic or inorganic „crust” is placed only after the synthesis of magnetic particles is completed. The process can be also performed during the conducted synthesis „in situ”. The immobilization of the cover/layer on the magnetic core is caused by chemical or/and physical interactions (van der Waals, Coulomb’s) [5, 10]. At this stage it is important that the cover stabilize the particles and that the surface was easily modified, by intruding functional groups onto the surface thus making the magnetic particle a selective and specific tool for isolating and purifying selected analytes from biological and environmental samples. Hydrophobic and hydrophilic groups can be attached to the NPs surface, which can be used, e.g. for enriching and isolating proteins. The modification can be also performed by attaching appropriate oligonucleotides (isolation of nucleic acids) as well as the antibodies (Fig. 14.6). The magnetic particle can be also modified by „imprinting” the compound molecule in

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Fig. 14.5 Scheme of the reaction of MIP creation

Fig. 14.6 Possible modifications on nanoparticle surface for analysis: 1. Oligonucleotide 2. Hydrophobic compounds 3. Affinity ligands 4. Antibody 5. Imprinted molecule

whole, thus providing a spherical niche, or its characteristic fragment (Fig. 14.5) using the same lock-and-key model. Thanks to such modifications, even analytes which do not possess natural magnetic properties can be isolated from the sample by using magnetic nanoparticles [10]. Magnetic nanoparticles can be also introduced into carbon nanotubes. Discovered in 1991, nanotubes, thanks to their properties, are an interesting solution as sorbents. Unfortunately, their poor solubility in water and the difficulty connected with their recovery from complex matrices limits their application. However, the possibility of modification solves this problem as the solubility is improved by introduction of

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hydroxyl, carbonyl or carboxyl groups. Introduction of magnetic particles allows to isolate them, in a simple manner, from rich matrices [11]. An interesting solution is also the Fe@Fe2O3 structure described as core-shell nanowires, where the core is metallic iron and iron (III) serves as the shell [12].

14.4

Application for Analysis

Thanks to the specific interactions between the receptor on the surface of magnetic particle and the analyte contained in the sample, it is possible to isolate it from the matrix of rich composition. Thanks to the use of magnetic separation, isolation of, for example, biological nanoparticles such as proteins can become simpler and less time-consuming than in the case of traditional methods (Table 14.2). Magnetic sorbents also enable to omit such stages as filtration or centrifugation [13–15]. In this procedure, magnetic particles can be added to the sample, the analyte is adsorbed on the surface of the sorbent or interacts with functional groups immobilized on the nanoparticle. Next, by using a magnet, the sorbent together with the analyte are removed from the sample solution. In order to perform the determination, the analyte must be desorbed by using an appropriate eluent [16] (Figs. 14.7 and 14.8). The above table presents only a small selection of the possible ways of synthesis and applications of in analytics of biological and environmental samples. The scope of applications of magnetic nanoparticles in isolating biologically active compounds from complex samples, particularly biological ones, is very wide with a growing trend, which is clearly confirmed by the number of articles which have appeared in recent years in this respect (Fig. 14.1 and Table 14.3). It must be emphasized that there are other possibilities of application of magnetic materials, which have been successfully implemented in biomedical research (application of magnetic resonance imaging – MRI) [29, 30], as well as searching for new pharmaceutics, which, thanks to their unique form, quickly and effectively reach their destination [31, 32]. Table 14.2 Advantages and disadvantages of magnetic nanoparticle Advantages Simple synthesis Economy Reduction of sample preparation time Contrary to the classical SPE, sorbent need not be packed into the column Possibility of surface modification Wide range of applications (from simple ions to complex biomolecules e.g. DNA) Possibility of re-using Possibility of recycling

Disadvantages Tendency for aggregation (when there is no covering layer) Necessity to sythesize monodispersive nanoparticles Chemical activity of the particles can lead to a loss of magnetic properties.

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Fig. 14.7 Extraction procedure with magnetic particles Fig. 14.8 Example of properties of magnetic sorbents

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a

Core@Shell@Modyfication

Fe3O4@ZrO2

Fe3O4@ BSA-MIP Fe3O4@ LIZ-MIP Magnetic polymer beads modify by the ligand of 2- mercapto-1-methylimidazole Fe3O4@Ol (oleate coated Fe3O4)

Fe3O4@ GO/chm-MIP Fe3O4@SiO2@C18

Typesa Fe3O4@PPy Fe3O4@SiO2 Fe3O4@SiO2@ LDH Fe3O4@SiO2@ TiO2 ME-MION (microemuslsion-magnetic iron oxide nanoparticle)

Commercial product

Water-in-oil microemlsion method Co-precipitation method

Preparation of magnetic materials Solvothermal method

Table 14.3 Examples of magnetic particles applications

Polychlorinated biphenyls (PCBs no.28,52,101,118,138,153,180) Cr(III)

Fluoxetine Organochlorine pesticides (OCBs) Polychlorinated biphenyls (PCBs) Bovine serum albumin (BSA) Lysozyme (Lyz) Immunoglobulin G (IgG)

Target Phthalic acid esters (PAEs) Nucleic acid Proteins Cd(II), Cr (III), Mn(II), cu II) Phosphate

Environmental water sediment human serum urine

Juices

Bovine serum Chicken egg white Human plasma

Water Cow milk

Sample Water E. coli – Environmental waters Wastewater

[28]

[27]

[24] [25] [26]

[22] [23]

References [17] [18] [19] [20] [21]

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Summary

Undoubtedly, the application of magnetic nanoparticles in analytical procedure contributes to an effective and efficient isolation of analytes from complex matrices. Thanks to the possibility of modification of these materials, it is possible to obtain highly selective and specific sorbents which can be used in environmental and biological analyses. Therefore, further improvement in the methods of synthesis of these magnetic materials as well as ways of modification and functionalizing of the surfaces, will result in increasingly efficacious stages of sample preparation, which, in turn, in respect to a smaller amount of substances co-existing in the extract, will lead to a favorable increase of the sensitivity of the applied chromatographic techniques combined, for instance, with mass spectrometry.

References 1. Buszewski B, Szultka M, Gadzała-Kopciuch R (2012) Sorbent Chemistry, Evolution, In: Pawliszyn J (eds) Comprehensive Sampling and Sample Preparation. Analytical Techniques for Scientists Vol. 2. Chapter 2.12, Amsterdam 2. Kwaśniewska K, Gadzała-Kopciuch R, Buszewski B (2015) Magnetic molecular imprinted polymers as a tool for isolation and purification of biological samples. Open Chem 13:1228 3. Akbarzadeh A, Samiei M, Davaran S (2012) Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine. Nanoscale Res Lett 7:144 4. Mohammed L, Gomaa GL, Ragab P, Zhu J (2017) Magnetic nanoparticles for environmental and biomedical applications: A review. Particuology 30:1 5. Borlido L, Azeredo AM, Roque ACA, Aires-Barros MR (2013) Magnetic separations in biotechnology. Biotechnol Adv 31:1374 6. Figuerola A, Di Corato R, Manna L, Pellegriono T (2010) From iron oxide nanoparticles towards advanced iron-based inorganic materials designed for biomedical applications. Pharmacol Res 62:126 7. Laurent S, Forge D, Port M, Robic C, Vander Elst L, Muller RN (2008) Magnetic iron oxide nanoparticles: synthesis, stabilization, vectorization, physicochemical characterizations, and biological applications. Chem Rev 108:2064 8. Faraji M, Yamini Y, Rezaee M (2010) Magnetic nanoparticles synthesis, stabilization, functionalization, characterization, and applications. J Iran Chem Soc 7:1 9. Lu AH, Salabas EL, Schuth F (2007) Magnetic nanoparticles: synthesis, protection, functionalization, and application. Angew Chem Int Ed 46:1222 10. He J, Huang M, Wang D, Zhang Z, Li G (2014) Magnetic separation techniques in sample preparation for biological analysis: a review. J Pharm Biomed Anal 101:84 11. Herrero-Latorre C, Barciela-Garcia J, Garcia-Martin S, Pena-Grecente RM, Otarola-Jimenez J (2015) Magnetic solid-phase extraction using carbon nanotubes as sorbents: a review. Anal Chim Acta 892:10 12. Li F, Cai C, Cheng J, Zhou H, Ding K, Zhang L (2015) Extraction of endocrine disrupting phenols with iron-ferric oxide core-shell nanowires on graphene oxide nanosheets, followed by their determination by HPLC. Microchim Acta 182:2503 13. Lu L, Wang X, Xiong C, Yao L (2015) Recent advances in biological detection with magnetic nanoparticles as a useful tool. Sci China Chem 58:793

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14. Zhao M, Xie Y, Deng C, Zhang X (2014) Recent advances in the application of core-shell structured magnetic materials for the separation and enrichment of proteins and peptides. J Chromatogr A 1357:182 15. Ríos Á, Zougagh M (2016) Recent advances in magnetic nanomaterials for improving analytical processes. Trends Anal Chem 84:72 16. Giakisikli G, Anthemidis AN (2013) Magnetic materials as sorbents for metal/metalloid preconcentration and/or separation. A review. Anal Chim Acta 789:1 17. Zhao H, Huang M, Wu J, Wang L, He H (2016) Preparation of Fe3O4@PPy magnetic nanoparticles as solid-phase extraction sorbents for preconcentration and separation of phthalic acid esters in water by gas chromatography-mass spectrometry. J Chromatogr B 1011:33 18. Ma C, Li C, He N, Wang F, Ma N, Zhang L, Lu Z, Ali Z, Xi Z, Li X, Liang G, Liu H, Deng Y, Xu L, Wang Z (2012) Preparation and Characterization of Monodisperse Core–Shell Fe3O4@SiO2 Microspheres and Its Application for Magnetic Separation of Nucleic Acids from E. coli BL21. J Biomed Nanotechnol 8:1000 19. Shao M, Ning F, Zhao J, Wei M, Evans DG, Duan X (2012) Preparation of Fe3O4@SiO2@layered double hydroxide core-shell microspheres for magnetic separation of proteins. J Am Chem Soc 134:1071 20. Zhang N, Peng H, Hu B (2012) Light-induced pH change and its application to solid phase extraction of trace heavy metals by high-magnetization Fe3O4@SiO2@TiO2 nanoparticles followed by inductively coupled plasma mass spectrometry detection. Talanta 94:278 21. Lakshmanan R, Okoli C, Boutonnet M, Jaras S, Rajarao GK, Environ J (2014) Microemulsion prepared magnetic nanoparticles for phosphate removal: Time efficient studies. Chem Eng 2:185 22. Barati A, Kazemi E, Dadfarnia S, Shabani AMH (2017) Synthesis/characterization of molecular imprinted polymer based on magnetic chitosan/graphene oxide for selective separation/ preconcentration of fluoxetine from environmental and biological samples. J Ind Eng Chem 46:212 23. Synaridou ME, Sakkas VA, Stalikas CD, Albanis TA (2014) Evaluation of magnetic nanoparticles to serve as solid-phase extraction sorbents for the determination of endocrine disruptors in milk samples by gas chromatography mass spectrometry. J Chromatogr A 1348:71 24. Gai QQ, Qu F, Zhang T, Zhang YK (2011) The preparation of bovine serum albumin surfaceimprinted superparamagnetic polymer with the assistance of basic functional monomer and its application for protein separation. J Chromatogr A 1218:3489 25. Gai QQ, Qu F, Liu ZJ, Dai RJ, Zhang YK (2010) Superparamagnetic lysozyme surfaceimprinted polymer prepared by atom transfer radical polymerization and its application for protein separation. J Chromatogr A 1217:5035 26. Lin Z, Zhang Y, Li C, Qian H (2013) Purification antibody by thiophilic magnetic sorbent modified with 2-mercapto-1-methylimidazol. Colloids Surf B Biointerfaces 108:72 27. Pérez RA, Albero B, Tadeo JL, Sánchez-Brunete C (2015) Oleate functionalized magnetic nanoparticles as sorbent for the analysis of polychlorinated biphenyls in juices. Microchim Acta 183:157 28. Wu YW, Zhang J, Liu JF, Chen L, Deng ZL, Han MX, Wei XS, Yu AM, Zhang HL (2012) Fe3O4@ZrO2 nanoparticles magnetic solid phase extraction coupled with flame atomic absorption spectrometry for chromium(III) speciation in environmental and biological samples. App Surf Sci 258:6772 29. Kim EH, Ahn Y, Lee HS (2007) Biomedical applications of superparamagnetic iron oxide nanoparticles encapsulated within chitosan. J Alloys Compd 434–435:633 30. Hee Kim E, Lee HS, Kwak BK, Kim BK (2005) Synthesis of ferrofluid with magnetic nanoparticles by sonochemical method for MRI contrast agent. J Magn Magn Mater 289:328 31. Prabha G, Raj V (2016) Preparation and characterization of polymer nanocomposites coated magnetic nanoparticles for drug delivery applications. J Magn Magn Mater 408:26 32. Mr. Wahajuddin, Arora S (2012) Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers. Int J Nanomedicine 7:3445

Chapter 15

Planning for Groundwater Protection: Monitoring Systems & Data Requirements Konstantinos A. Papatheodorou and Konstantinos Ε. Evangelidis

Abstract Contemporary IC Technologies and the development of advanced sensor systems provide the means to monitor groundwater resources and to provide early warning, in line to the respective EU principles and existing research. Groundwater monitoring effectiveness depends on the operational characteristics/ specs of the groundwater monitoring system (GMS), as these are related to the actual risks groundwater faces over the monitored area. Groundwater aquifer systems are themselves very complex and moreover, they are affected by numerous natural and anthropogenic factors; so, defining the types, the magnitude, the spatial location and/or extend of such threats for any area, in relation to the respective groundwater regime, is a demanding task. Unfortunately, there’s a limited, indirect access to the subsurface domain where changes to groundwater quantitative and qualitative characteristics take place. Thus, there has to be an integration of information related to numerous parameters affecting groundwater, which can lead to a consistent interpretation of the hydrogeologic regime over the study area and to building a respective conceptual hydrologic model. In this way, groundwater monitoring can be tailored to the specific local conditions, threats and risks and thus, it can become most efficient. There’s of course a level of uncertainty in any conceptual model due to justifiable assumptions and/or generalizations which can be reduced during the GMS calibration phase, where actual measurements are used to calibrate the conceptual model and adapt/tailor it to local hydrogeologic conditions thus optimizing it. An example of the required parameters necessary for building a conceptual hydrogeologic model for monitoring, managing and protecting groundwater in an area, is presented and discussed. It includes information regarding the groundwater recharge zones and hydrogeologic basins, vulnerability assessment from surface pollution, land use and pressures from non point and point sources of potential contamination. Remote Sensing and geomatics technologies have been used to integrate this information and to visualize the outputs. K. A. Papatheodorou (*) · K. Ε. Evangelidis Technological Educational Institute of Kentriki Makedonia, Serres, Greece e-mail: [email protected] © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_15

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Keywords Groundwater monitoring · Groundwater vulnerability · Hydrogeologic conceptual models

15.1

Introduction

Environmental resources are under a gradually growing pressure due to climate change and to the continuously increasing demand with overexploitation and pollution among the main hazards [1]. One of the most important environmental resources is groundwater (GW) which is a key component for sustainable development. Deterioration of groundwater quantity and/or quality, has also an additional impact on related surface water and terrestrial ecosystems [2]. For those reasons, the preservation of this natural resource through protection and management is absolutely essential. Contemporary IC Technologies and the development of advanced sensor systems provide the means to monitor groundwater resources and to provide early warning, in line to the respective EU principles and existing research [3]. Sensor development, installation, and maintenance costs impose decisive restrictions in installing, operating and maintaining monitoring systems [4]. The reduction of these costs can therefore play an important role in promoting the use of such systems thus improving the operational capacity of societies to protect and manage groundwater resources [5]. Pressures and Risks on groundwater are related to the dynamic balance between consumption and resource availability which is also affected by climate change, and contamination/pollution from either natural or anthropogenic sources. Having said that, it is important to note that Climate Change negatively affects both sides of this balance by imposing conditions for an increased demand for consumption while at the same time it causes a significant reduction of resource availability. As it is therefore evident, an understanding of the nature of the impact that may result from a pressure, and the identification of methods to monitor or assess the relationship between pressure and the respective impact, is absolutely necessary. The assessment of whether a pressure on a groundwater body is significant, must be based on good scientific knowledge of the pressures within the hydrogeological basin [6], together with understanding the parameters and interactions defining the groundwater regime (water flow, chemical transfer, and biological functioning of the water body within the hydrogeological basin). In any case, for a “Pressure” to cause an impact there has to be Vulnerability of groundwater resources coupled with insufficient Capacity to reduce the Risk. So, the question/challenge that emerges is “how can we improve our capacity to reduce the risk or how can we reduce Vulnerability and/or Exposure in order to reduce the risks groundwater faces. Monitoring systems can greatly help towards achieving these goals but their efficiency strongly dependents on knowing “what”, “where”, “when” and “how” any parameter is going to be monitored. Since groundwater related properties and

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pressures are highly location dependent, the sound scientific knowledge of the impact which may result from a pressure, taking into consideration the existing geological and hydrogeological conditions, is absolutely essential to develop a conceptual model representing the groundwater regime in the area and to understand the respective uncertainties. In this way, a cost efficient groundwater monitoring system can be developed and maintained, leading in turn, to the efficient management and protection of the resource [7–9].

15.2

EU Groundwater Protection & Management Policies & Environmental Data Management

EU current policies and standing regulations define at large the necessary steps to be taken towards sustainable groundwater management both from a scientific and from a technical aspect. Problems identified regarding the up-to-date implementation of the respective EU policies, include the lack of Harmonization, lack of sufficient data at “decision making scales” and the lack of spatially registered information [3]. Harmonization of methodologies is a key issue and a consensus among scientists activated in this scientific field is necessary in line with standing EU regulations. The EU policies regarding Water Protection and Management are based on a set of Principles (Fig. 15.1):

Fig. 15.1 EU Principles regarding (Ground) Water protection and Management

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Based on those Principles, the EU Commission has issued numerous Directives, a list of which is shown below (Table 15.1), covering a number of essential issues related to groundwater (GW) protection and management. Most if not all of the Directives have already been incorporated into the National Law of the EU Member States. GW related issues, have been consolidated into the Water Framework Directive –WFD which covers a number of different steps for achieving sustainability of the resource. Based on the above, Member States should, by the end of 2006, establish monitoring networks aiming at providing an overview of the chemical and quantitative status of GW; River basin management plans completed by 2009. These aim at investigating the pressures and impact of human activities on GW, economic analyses of water use, protection programmes, monitoring of remediation measures where applicable. European Environment Agency (EEA) identified and examined the most important adverse effects of human intervention on the quality and the availability of GW [10], a number of factors imposing pressures on groundwater quality and quantity. According to this report (“Groundwater quality and quantity in Europe”), physical and chemical parameters defined as indicators to assess the pressures on GW, include nitrates, pesticides, chloride, pH-value, alkalinity, electrical conductivity, GW abstraction and human interventions in the hydrologic cycle. As was shown in the same report [10], many of the problems affecting GW quality and quantity are common across Europe so these can better be addressed at a European level. A serious problem towards that end, more intense in Cross Border Areas (CBA), is the heterogeneity of data acquired and used. This problem blocks cooperation, restricts competence sharing and slows down overall progress. An additional problem identified was related to the monitoring strategies and methods adopted or adapted to “domestic” needs. Various countries had applied different monitoring systems and more importantly, different methods; a fact which led to investigating different aspects and to acquiring different types of data, incompatible between different countries even in respect to the same environmental parameters, thus making comparison among data from different locations, extremely difficult. Another reported issue, related to the data provided, was their low level of reliability since in most cases, no additional information (type of the sampling sites, their status, hydro-geological regime, exact location etc) was available. Having said that, efficient environmental resource management, attempts to balance between needs and resource availability so it must be based on well documented decisions. Environmental problems usually present a high spatial variability so, effectiveness of actions towards a sustainable resource management & protection strongly depends on spatial information availability, reliability and accuracy [11]. The EU has responded to this challenge by developing policies which aim at developed Policies aiming at ensuring: “that data is handled in a consistent and transparent manner and; that data providers having agreed to share, are assured that their data are properly handled, disseminated and acknowledged following pre-defined similar rules and principles in all countries and stakeholders” (EEA Data Policy, 2013).

Birds Directive 79/409/ EEC

Drinking Water Directive 98/83/EEC

Major Accidents (Seveso) Directive 96/82/EC

Environment Impact Assessment 85/337/EEC

Sewage Sludge Directive 86/278/ EEC

Legislative, administrative or fiscal instruments

Negotiated environmental programmes

Emission controls, abstraction controls

Major accidents (Seveso) directive 96/82/EC

Codes of good practice, demand management

Recreation and restoration of wetland areas

EU Supplementary measures (Controls, codes of good practices, funding research etc)

Bathing Water Directive 76/160/EEC

EU Legislative Measures (Directives) Urban Wastewater Treatment Directive 91/271/EEC

Efficiency and reuse measures

Environmental Liability Directive 2004/35/ CE

Table 15.1 EU policies related to GW, classified as “Legislative” and Supplementary measures

Desalination plants

Plant Protection Products Directive 91/414/EEC

Construction projects, rehabilitation projects

Nitrates Directive 91/676/EEC

Artificial recharge of aquifers

Habitats Directive 92/43/ EEC

Educational projects, research, demonstration

Integrated Pollution Prevention Control 96/61/ EEC

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An important step towards achieving this goal is the existing Infrastructure for Spatial Information in the European Community (INSPIRE) Directive (Directive 2007/2/EC). For the implementation of the INSPIRE Directive, the European Commission (EC) has also released the (EC) No 1205/2008 Regulation of the third of December 2008 and its supportive documents (INSPIRE Metadata Implementing Rules: Technical Guidelines based on EN ISO 19115 and EN ISO 19119 06.11.2013). The European Environment Agency (EEA) also supports the operation of Environmental Data Centres which can host data, provided that these follow certain criteria concerning data structures and formats. As it therefore seems, the necessary respective Legislation exists and sets the legal framework for water protection and management including data management, sharing and dissemination. One of the remaining issues towards the efficient resource protection and management is the law enforcement. Among other targets, law enforcement aims at removing “profit” as a parameters of misuse of the resource or threatening its status by poorly applying methods and technologies to protect it [12]. Interpreting the “polluter pays” principle for instance, indicates that it has a twofold role: (i) to remove the motivation created by “profit” (since the polluter will have to pay for the damage) and (ii) to lift the burden from the rest of the tax payers (who are not responsible for the damage) and remediate the resource at the expense of the polluter. In order to indicate the polluter beyond reasonable doubt, a very efficient monitoring network, based on sound knowledge of the groundwater regime, is needed. Land Use Legislation, especially regarding the installation of various activities can play a very important PREVENTIVE role and the same stands for legislation regarding the exploration, exploitation and management of the resource which may even be more important.

15.3

Groundwater Monitoring for Protection & Management

Efficient ground (and surface) water protection within the framework set by EU policies can be achieved through the development and use of Ground Water Information Systems (GWIS), which are capable of providing real time information regarding water physical, chemical and dynamic parameters. Taking into consideration the EU Commission set principles regarding Water Management & Protection as set out in numerous Directives and “Communication by the Commission” documents, an indicative list of GWIS actions would include: • Continuously monitor groundwater quantity and quality related parameters. • Determine (near “real time”) current status and estimate future trends. • Provide Early warning in case of exceeding set thresholds of measured or forecasted parameters.

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• Provide Early Detection of pollution/contamination, indicate pollution source, take remediation measures at the source. • Monitor remediation measure performance and calibrate them. • Provide support to regulate demand and balance consumption to availability. • Support decisions for legislation and law enforcement (i.e. “polluter pays” principle, etc). • Support decisions regarding groundwater protection & management, Land Development and Land Use. Various approaches have been proposed and used to design and develop such systems taking always into consideration the existing geological conditions, the monitoring targets and the costs for system development, operation and maintenance [11, 13a,b, 14–17]. As far as the “Informatics” part is concerned, available technologies provide low cost or even for free solutions, when using Open Source tools. For instance, such a system (Fig. 15.2) can be based exclusively on Interoperable Platforms of the Open Source Geospatial Foundation and on Open Standards of the Open Geospatial Consortium (OGC). The web interface can be based on Javascript and its OpenLayers using GeoExt geospatial libraries. This kind of structure ensures that the outputs comply to Open Standards which fully meet the dissemination requirements of the water quality assessment parameters for policy implementation, decision making, enforcement, communication and public awareness. Data acquisition can be benefited by using new technologies (Cloud GIS) for Collaborative Mapping and the free access to Remote Sensing data from “Landsat 8” and “Sentinel” satellites (Fig. 15.2), in order to compress and minimize time needed to collect reliable data from large areas. Surface and groundwater data can be combined through Geographical Information Systems in order to assess surface/groundwater interactions and to control the impact of surface water quality to GW quality [18]. As is therefore evident, such a Ground Water Information System (GWIS) can provide outputs which can support decisions and law enforcement, communication/dissemination to raise awareness. Efficient development of a GWIS requires a multi-disciplinary approach, which covers the development of the Conceptual Model (provision of sound scientific knowledge), the development of (custom if necessary) sensors, and the development of the Information & the Communication Systems (infrastructure). Since in the long term, the main costs of these systems are related to sensor purchase, installation and maintenance, the number of sensors installed and their specifications define at large the total costs and the feasibility to develop, install and maintain such a system. At present, groundwater monitoring is being done using one of two main directions: (i) in-situ measurements using stand-alone equipment and (ii) real-time monitoring. The first option is costly, time consuming and labor since it involves a lot of field work. There’s also a high potential of equipment being damaged because of their use in difficult conditions (inside boreholes, pipes etc).

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Fig. 15.2 Schematic representation of a Ground Water Information/Monitoring System based on interoperable platforms of the Open Source Geospatial Foundation and on Open Standards of the Open Geospatial Consortium (OGC). The GWIS incorporates Geo-informatics Technologies to manage Geospatial information and Cloud based services to support collaborative mapping and information sharing

Real-Time monitoring on the other hand can provide the information needed (provided that it measures the correct parameters in the right location) but it is inflexible (one the sensors are install they remain in place for their entire operational period and very costly due to the cost of sensors, the sensor maintenance costs and their low life-span [19]. For these reasons, many attempts to install and maintain such a system have failed and these systems, after an operational period, have been abandoned due to the lack of funding maintenance and/or sensor replacement. The solution to this problem is the development of a new sensor generation which will incorporate a number of properties: low purchase cost (affordability), minimal dimensions (to fit in narrow spaces); modular design (to be expandable in measuring at the same location additional parameters); flexible installation (to be transferred in another location if necessary); uninterruptible communication; longevity; and of course these sensors must provide at least the expected level of sensitivity, accuracy, precision, repeatability, selectivity, durability and have minimal maintenance

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requirements. Obviously, these requirements pose a challenge to the sensor development Research and Industry. Early warnings for contamination depend on triggering alarms when specified threshold of monitored parameters are exceeded. Taking into consideration that triggering an alarm for water contamination has a great impact on social life and on any anthropogenic activity, such a decision must be based on absolutely reliable information and should not rely on measured values of the monitored parameters only. Information leading to decisions must take into consideration the interaction of the values of more parameters related to a potential contamination or pollution because monitoring upper and lower thresholds of specific parameters is not enough to trigger an early warning. For instance, an increase in Cloride ion concentrations and Conductivity values could indicate sea water intrusion but these changes could also be attributed to different causes. This information combined with a respective increase in Na and sulfates (SO4) with a HCO3 decrease at the same time, is signaling a sea water intrusion and can be used to trigger and alarm [20, 21]. It is therefore obvious that an in depth knowledge of all aspects related to groundwater hydrology, hydrochemistry and hydraulics for the area under investigation must be consider and incorporated into the monitoring system, in order to support decision making. This task can only be implemented through the development of a conceptual model that will identify all involved parameters as well as their interactions, which define the groundwater status, the potential threats and their impacts.

15.4

Conceptual Modeling for Groundwater Protection & Management

In general, the number of sensors installed and their specifications define the main costs and thus the feasibility to develop, install and maintain a GroundWater Monitoring System (GWIS). In order to minimize the cost of such a GWIS the least possible number of sensors should be used but at the same time, a number of questions arise. Answering those questions, defines the system’s operational specifications, including sensor specifications, their location and spatial coverage, and at large, the GWIS potential to protect groundwater and support management related decisions: • Which are the Ground Water monitoring targets? • Which is the required “resolution” and the one provided by the GWIS? (ie. does it allow for detecting/monitoring a specific point source? . . .a plume, etc). • Are the appropriate aquifers being monitored at the appropriate locations n order to detect at an early stage any potential problem? • Are the appropriate parameters being measured to an adequate degree of accuracy, consistency and reliability?

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• Does the monitoring network provide a coherent and comprehensive overview of the groundwater status within a river basin/ hydrogeological basin / groundwater body? • Does the system collect sufficient data to indicate seasonal and mid-term variations and to estimate trends? • Does the system permit for trend analysis (does it include groundwater flow/ hydraulic models?) Based on the answers, some basic considerations [22, 23] regarding the requirements for setting up such a program are related to: • Compliance of the GWIS operational specs and outputs to the existing legislation. • GWIS efficiency, which in turn requires to take into consideration: – the aquifer (flow) system characteristics (recharge, flow conditions, available reserves, boundary conditions, spatial extend and other parameters related to understanding all the processes/interactions between surface and groundwater. – Groundwater physical, chemical and dynamic Properties; because an understanding of the connection between the aquifer material and the physicochemical parameters of groundwater as well as the relationship between groundwater hydraulic heads, is necessary. – The groundwater Vulnerability against any potential Hazard, in order to identify the kind/type and level of potential threats and Risks. – The Pressures which exist including the kind and magnitude of problems they may cause. In respect to anthropogenic hazards, this means that for any activity the information needed includes any kind of used substances and any kind of products, by-products and wastes produced by any activity or installation. – the Risks groundwater faces to identify the type and level of potential damage. Only the well documented knowledge of all this information can lead to justified decisions regarding “why”, “what”, “where” and “when” to monitor and in turn lead to planning “how to” set-up an efficient monitoring system with all its components. Understanding all these parameters which are related to the groundwater flow system, its dynamic, physical and chemical parameters as well as their potential temporal variations and their interaction with aquifer media, with surface water bodies and terrestrial eco-systems, constitutes the groundwater Conceptual Model of the area, which is essential for developing an efficient GWIS. A Conceptual Model is always dynamic, evolving and improving with time as new data are obtained; and the model is continuously refined in an iterative way. The Conceptual Model must also include water quality information and pressure assessment. In essence, the model should include the nature of the aquifer system, both in terms of quantity and quality, and the potential consequences of pressures taking always into consideration the existing legislation regarding any of its components (Fig. 15.3). Groundwater conditions are actually related to a balance between availability (groundwater recharge), consumption (groundwater exploitation) and potential threats against it quality (vulnerability and pollution/contamination risks). Any of

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Fig. 15.3 A schematic representation of the required parameters to develop a Groundwater Conceptual Model (GCM). Scope of the GSM is to help understand the linkage between the existing hydro-geological conditions and the existing threats for groundwater quantity and quality, in order to balance the preservation of the resource with its uses in a sustainable way

the three components (recharge-exploitation-vulnerability), require a list of data and information related to various parameters, a non-exhaustive list of which includes [22, 23]: • Recharge – Geologic and Hydro-geologic maps – Tectonic maps (to investigate recharge through rock formations) – Remote Sensing analysis for tectonic mapping, – Stratigraphy from bore-logs (aquifer media, aquifer potential, flow conditions, strata thickness, aquicludes etc) • Extraction/Exploitation – Borings/water wells: location; data regarding the physical-chemical-dynamic properties of groundwater in each location; – Demand & Consumption (including temporal variations) • Vulnerability & Risk Assessment (Potentially Hazardous to GW installations/ activities: – Vulnerability: Litho-Stratigraphy/Geological structure (lithological cross sections from borings; type of formations; thickness; sequence, permeability etc) Aquifer systems: Hydrogeological parameters (hydraulic conductivity, permeability, groundwater levels, groundwater flow direction etc) Recharge conditions (recharge status including recharge zones, direct percolation from surface etc)

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Fig. 15.4 A indicative «list» of required data for building a Groundwater Conceptual Model (GCM)

– Risk: Point sources: land use/activities (location, type, chemicals used for processing, products, by-products, wastes, type of produced potential contaminants, protection measures taken, demand for groundwater consumption etc). All required information is per activity and (if) any temporal variations should also be considered. Non point sources: types of activities (ie. agriculture, rivers, lakes); Demand each source (ie. agriculture: cultivated area, types of crops, crop demand for agro-chemicals throughout the year, crop demand for consumption etc.; rivers: permeability of surface formations along the stream bed in the entire watershed and especially downstream from various point sources; lakes: the same etc). The multitude of parameters needed is indicative of the difficulty to collect the respective data, since there are specific constrains set by location and time (Fig. 15.4). For instance, water level data can be compared if they have been collected during the same hydrologic year; chemical analyses data can be compared only when collected from the same sampling point or in the case of different sampling points, during the same period. As is evident, there may be various resources of data, and this fact imposes a series of concerns regarding data quality (accuracy, reliability, completeness, currency/timeliness and since they may be coming from different sources, consistency). To overcome this issue and in order to gradually increase the number of scientists following harmonized approaches, a strategy including the development of technical guidance based on best practice cases leading to a common understanding of the entire spectrum of actions towards groundwater protection and management, and the development of open standards for ground water monitoring are essential.

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219

Conclusions

A review of the conditions required to develop an efficient groundwater monitoring system have been presented and discussed. The development of a groundwater monitoring program requires a multi-disciplinary approach, which covers the development of the Conceptual Model, the development of (custom if necessary) sensors, and the development of the Information & the Communication Systems (infrastructure). Groundwater Conceptual Model (GCM) development, is a decisive stage in compiling a groundwater monitoring program since it justifies the reasons for monitoring, it defines “what”, “where” and “when” to monitor and moreover, it sets the operational requirements for “how” any parameter should be monitored. It also requires a multi-disciplinary approach which may involve geologists, hydrogeologists, hydro-chemists, chemical engineers, geo-informatics (remote sensing and GIS) experts, hydraulic engineers and more. The respective geo-database must contain all parameters related to groundwater/aquifer physical, chemical and dynamic parameters as well as their inter-relations. Accurate, precise, consistent, timely and as complete as possible information is precious in all stages of the monitoring system development because it can greatly improve the conceptual model accuracy and overall, the monitoring program efficiency. Sharing information and data can greatly improve the capacity to develop efficient systems but harmonization of both methodologies and data is absolutely necessary. The existing framework set by the INSPIRE Directive can greatly help towards that scope but consensus among the scientific community is also required. A Strategy to achieve these goals, should include: • Harmonization of approaches/methods used. • Competencies sharing to build capacity of researchers. Exchanging experiences, broadens the ideas, offers more potential solutions and saves time and effort. Harmonization of methodological approaches is the key to sharing competencies. It requires a common understanding of the problem and great efforts for achieving consensus. • Develop technical guidance based on best practice cases, so that gradually, the “user” base following harmonized approaches will grow; • Develop open standards for ground water monitoring; • Develop efficient and more affordable monitoring systems; • Systematically assess Vulnerability and pollution Risk. This is an essential step. Planning for protection absolutely requires a sound knowledge of vulnerability and Risk. • Develop a common understanding of the entire spectrum of actions towards groundwater protection and management. This common understanding should apply to the monitoring programme development team and to the stakeholders including the Administration and the rest of the “stakeholders”, who include the

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Industry, Water Companies, farming companies and farmers and of course the rest of the public; • Raising awareness is another, very effective preventive measure. Creating aware and conscious citizens is like transporting them from the side of the problem to the side of the solution; they become a part of the solution. Web based technologies (portals with near real-time information about the status of the resource, the problems, solutions applied etc) can greatly help towards this scope.

References 1. United Nations World Water Assessment Programme Special Report (2009): Climate Change and Water: An Overview from the World Water Development report 3: Water in a changing World. Published by the United Nations World Water Assessment Programme. Programme Office for Global Water Assessment, Division of Water Sciences, UNESCO, 06134 Colombella, Perugia, Italy 2. European Commission, Directorate-General for the Environment (2008) Groundwater protection in Europe. The new groundwater directive – consolidating the EU regulatory framework. Information Centre (BU9 0/11) B-1049 Brussels. ISBN 978–92–79-09817-8; DOI https://doi. org/10.2779/84304. © European Communities, 2008 [http://bookshop.europa.eu] 3. Papatheodorou K, Evangelidis K, Ntouros K (2017) Geomatics Technologies for Environmental Protection and resource management. J Environ Prot Ecol 18(1):168–180 4. Raich J (2013) Review of sensors to monitor water quality. ERNCIP thematic area. Chemical & Biological Risks in the Water Sector. Deliverable D1-Task 1. CETaqua-Water Technology Center, AgbarGroup, https://erncip-project.jrc.ec.europa.eu/documents/review-sensors-moni tor-water-quality 5. Lambrou TP, Anastasiou CC, Panayiotou CG, Polycarpou MM (2014) A low-cost sensor network for real-time monitoring and contamination detection in drinking water distribution systems. IEEE Sensors J 14(8) 6. EU Commission (2000) Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal L 327, 22/12/2000 P. 0001–0073 7. Lukjana A, Swasdib S, Chalermyanonta T (2016) Importance of alternative conceptual model for sustainable groundwater management of the Hat Yai Basin, Thailand. 12th International Conference on Hydroinformatics, HIC 2016. Elsevier ScienceDirect, Procedia Engineering 154 (2016):308–316 8. Spijker J, Lieste R, Zijp M, de Nijs T (2010) Conceptual models for the water framework directive and the groundwater directive. Report 607300015/2010. RIVM, Postbus 1, 3720 BA Bilthoven, Tel 030–2749111, http://www.rivm.nl/ 9. Kupfersberger H, Pulido-Velazquez M, Wachniew P (2011) Conceptual models and first simulations, Deliverable D5.2, Project: Groundwater and Dependent Ecosystems: New Scientific and Technological Basis for Assessing Climate Change and Land-use Impacts on Groundwater- GENESIS www.thegenesisproject.eu 10. Scheidleder A, Grath J Winkler G, Stark U, Koreimann C, Gmeier C, Nixon S, Casillas J, Gravesen P, Leonard J, Elvira M (1999) Groundwater quality and quantity in Europe. Report prepared under the supervision of the European Environment Agency. http://www.eea.europa. eu/publications/groundwater07012000 11. Papatheodorou K, Evangelidis K (2008) Ground water information system: a digital tool for groundwater resources protection and management. 4th International Environmental

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Conference of the Balkan Environmental Association (BENA), “Life Quality and Capacity Building in the frame of a Safe Environment”, Katerini, Greece 12. EU Commission (2004) DIRECTIVE 2004/35/CE OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 21 April 2004 on environmental liability with regard to the prevention and remedying of environmental damage. https://eur-lex.europa.eu/legal-content/ EN/TXT/PDF/ ?uri¼CELEX:32004L0035&from¼EN 13. (a). ENVIRONMENTAL AGENCY UK: Environment agency framework for groundwater resources. Conceptual and Numerical Modelling. R&D Technical Report W214, 2001; (b). ENVIRONMENTAL AGENCY UK: Guide to good practice for the development of conceptual models and the selection and application of mathematical models of contaminant transport processes in the subsurface NC/99/38/2, 2001 14. Aller L, Bennett TW, Hackett G, Petty RJ, Lehr JH, Sedoris H, Nielsen DM, Denne JE (1991) Handbook of suggested practices for the design and installation of ground-water monitoring wells. Environmental Monitoring Systems Laboratory Office of Research and Development U.S. Environmental Protection Agency Las Vegas, Nevada 89193–3478 15. William Page G (1987) Planning for groundwater protection. Department of Urban Planning and Center for Great Lakes Studies University of Wisconsin-Milwaukee Milwaukee, Wisconsin 16. Louisiana Department of Environmental Quality and Louisiana Department of Transportation and Development (2000) Construction of Geotechnical Boreholes and Groundwater Monitoring Systems. Louisiana Department of Transportation and Development, Water Resources Section, December 2000 17. Singhal N, Samaranayake R, Gunasekera HD, and Islam J (2009) Groundwater Monitoring. ENVIRONMENTAL MONITORING – Vol. II – Groundwater Monitoring 18. European Commission (2007) Common Implementation Strategy for the Water Framework Directive (2000/60/EC). Guidance Document No.15, Guidance on Groundwater Monitoring. Office for Official Publications of the European Communities, 2007. ISBN 92-79-04558-X; ISSN 1725-1087 19. Anumalla S, Ramamurthy B, Gosselin DC, Burbach M (2007) Ground Water Monitoring using Smart Sensors. CSE Conference and Workshop Papers. 69. http://digitalcommons.unl.edu/ cseconfwork/69 20. Sudaryanto and Wilda Naily (2018) Ratio of Major Ions in Groundwater to Determine Saltwater Intrusion in Coastal Areas. IOP Conf. Ser.: Earth Environ. Sci. 118 012021 http://iopscience. iop.org/article/10.1088/1755-1315/118/1/012021/meta 21. Alfarrah N, Walraevens K (2018) Groundwater overexploitation and seawater intrusion in coastal areas of arid and semi-arid regions. Water 10:143. https://doi.org/10.3390/w10020143 22. European Commission (2004) Groundwater risk assessment – Technical report on groundwater risk assessment issues as discussed at the workshop of 28th January 2004–12 October 20041 23. World Meteorological Organization (2013) Planning of water quality monitoring systems. Chair, Publications Board World Meteorological Organization (WMO). ISBN 978–92–6311113-5

Chapter 16

The Synergy Between Cyber and Nuclear Security. Case Study of Moldova Aurelian Buzdugan and A. Buzdugan

Abstract Cyber security is recognized as an intrinsic part of the nuclear security due to the numerous embedded computers used in the civil nuclear domain in systems such as physical security, industrial control systems or material accountancy databases. In present these domains have developed however separate regulatory frameworks. This has led to the situation where the cybersecurity related assessment for the nuclear and radiological (NR) has become an additional function of the regulatory authorities in the NR domain. This is also the case of Republic of Moldova. We will discuss in this paper the regulation which specifies the minimum cyber security requirements across the public institutions [1], which includes as well civil NR operators. We will reflect the current state of cyber security in the nuclear and radiological domain from the legislative and technical perspective. We believe the approval of these requirements will lead to an increased level of cyber security at a national level, as well as will facilitate the NR regulation process in terms of cyber security aspects. The minimum cyber security requirements will also provide clear technical guidance for all entities, including the ones from the nuclear and radiological domain, in order to apply these controls within their infrastructure. In addition, the document contains requirements for security testing, design basis threat and inclusion of cyber security requirements in all processes in the organization. We will also refer to the approved Regulation on Physical Security on Nuclear and Radiological Activity [2], which takes into account the increasing cyber security role upon designing, maintenance, inspection and authorization processes of a physical security system for the NR operators.

A. Buzdugan (*) National Nuclear Security Support Center, Technical University of Moldova, Chisinau, Republic of Moldova A. Buzdugan National Nuclear Security Support Center, Technical University of Moldova, Chisinau, Republic of Moldova Technical University of Moldova, Chisinau, Republic of Moldova © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_16

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Keywords Moldovan regulatory framework · Minimum cyber security requirements · Nuclear security

16.1

Introduction

The cyber security domain has a rapid development trend nowadays, being a subject undertaken both at national and at international level. The number of computerized systems in our society and in the public institutions has a high and continuous rate of growth, which combined with the numerous vulnerabilities, both known and unknown, create the premises for the development of new risks coming from the cyber space for practically any domain. Nuclear security, which should be an intrinsic part of the national security is not an exception, where computer technologies are part of the core systems, such as physical security systems, accountancy of NR materials, radioactive waste and associated equipment, specific national databases for NR objectives or for the Regulatory Authorities’(RA) [3]. This is one of the current areas on which we think a cyber-attack could have an imminent impact, but there are as well indirect systems from which an attacker could retrieve more information regarding NR objects, either use it for pivoting to networks of other institutions. Therefore, transparent definition of minimum cyber security requirements for computer systems is one of the baseline regulation via which countries try to ensure that all institutions would follow clear criteria to protect the systems and data contained within. We will refer in this paper to the Moldovan Minimum Cyber Security Requirements Regulation [1] (further MSR). We believe this Regulation would complement the Moldovan Regulation on Physical Security for NR Entities [2]. MSR could also facilitate the authorization or inspection processes as the requirements for IT systems would be clearly listed. On the other side, such a regulation would mean additional work for the institutions that are in charge of maintaining it up to date, as technical requirements need to be updated regularly in line with the threat assessments. Nevertheless, the cyber security component, as part of the nuclear security, has motivated member states to adjust their legal frameworks and include cyber security as part of regulations for various domains, including the nuclear one. However, developing countries have often not yet clarified the responsibilities and interaction at the national level in domains such as nuclear or cyber. This has also led to the situation where international recommendations on cyber security coming from other domains such as NR or healthcare are not always taken into account when developing the cyber security national legislation. This paper will reflect upon the status of cyber security and NR domain from the legislative perspective in Republic of Moldova. We will describe the current cyber security state and we will make an outline of the reflection in NR domain by evaluating the progresses in the legislation. We will also present the relevant

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components of the adopted Regulation on Physical Security on Nuclear and Radiological Activity, which acknowledges and mentions cyber security as intrinsic part of the physical security systems. We will also talk about the cyber security initiative to establish minimum computer security requirements for public authorities, including NR operators and RA. In conclusion, we will assess the current legal frameworks and we will propose certain recommendation for future development.

16.2

Current Status of Cyber Security in Republic of Moldova

Republic of Moldova is continuously developing and updating the national cyber security framework and defining the responsibilities and roles at the national level. This paper is an extension of the first analysis discussed at the 2015 IAEA Computer Security Conference and presented briefly at the third International Conference of Health Technology Management [4], where we also stated about the benefits of having a cyber-security policy and the positive effects of a high-level policy. The Moldovan Government has approved the National Cyber Security Program for years 2016–2020 [5], which describes the measures to ensure the cyber security of systems. One of objectives of this strategy is capacity building for cyber defense and the education, lifelong learning and training in cyber security. These also refer to the critical infrastructures from NR domain, and will be supported by the following actions listed in the program: • definition of the responsible institutions and developing defense capacity; • establishment of a cyber security research and training center; • update of the cyber security curricula; • awareness raising about the cyber security risks; • definition of professional competencies for computer security practitioners from public and private sector and • conducting workshops and training sessions for critical infrastructures staff. These actions are tackling the cyber security risks from both the technological aspect, by ensuring that there are appropriate tools and systems in place to ensure the security, as well as the human resource development aspect, which includes raising user awareness concerning cyber risks. It is necessary to have a global approach in ensuring cyber security – fact, which we believe is enough reflected in the national program. The objectives and actions proposed will guide the authorities in adjusting their work programs as well as focus their efforts and resources in strengthening cyber security by meeting the baseline criteria set by the Regulation on Minimum Cyber Security Requirements. This would have an impact on both the public as well as the private sector. Without regards to the view of these actions, the effects will not be instant - as the security culture, both in cyber and nuclear domain is overall low at

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the implementation level. Besides, by focusing on the user awareness, research and education in this area, the actions should have both a short and long-term effect. Due to the importance of this subject there is already a visible result worth mentioning the opening in October 2016 of the Cyber Security Laboratory within the Technical University of Moldova [6] in cooperation with the S.E. Center of Special Telecommunications, which is the technical operator of the Government, as well as the Computer Emergency Response Team provider for public authorities. This success was possible with external assistance from NATO “Science for Peace and Security” Program, US Embassy in Moldova and Estonian Embassy in Moldova. We would also like to mention that the Moldovan Parliament approved the Law on Informational Security Concept [7]. This document will serve as the baseline for the Strategy for Information Security to be developed by the Government, as well as for the Action Plan on the national level that will ensure the concepts described in the Law are being accomplished. This document underlines without doubts the interest of the State to protect the critical infrastructures, which include as well the NR operators of level I and II. The nuclear security domain is also in a continuous improvement process. In February 2013 within the Technical University of Moldova was established the National Nuclear Security Support Center with the support of the IAEA Nuclear Security Office and Swedish Radiation Safety Authority (SSM). The Centre has the objectives to teach young specialists and train other staff from relevant organizations, provide technical support as well as conduct research in this field. During 2017 was upgraded the Curriculum of Master program in “Nuclear Security and Radiation Safety”. The new Curriculum contains additional lectures on nuclear security, safety, safeguards, guaranties and non-proliferation. This also reflects the progressive interconnection with the cyber security domain. In this matter, the Center has received technical assistance form SSM. Another achievement in the NR domain, which includes cyber security aspects, is the approval (after 3 years of promotion of the draft) of the above-mentioned Regulation on Physical Security on Nuclear and Radiological Activity. The requirements for the authorization process of NR operators concerning physical security now contains the cyber security component as part of the physical security systems [2]. We will list here only the aspects that refer to both NR and cyber security, in the context of physical security systems. The base of this regulation was the provision of the Law 132 [8] about one of the authorization process conditions on physical security that includes cyber-security of the NR objects. The regulation is also in line with IAEA requirements and recommendations [9, 10] and describes the following: • cyber security role upon the establishment of a physical security system; • information security requirements as well as technical requirements for software and hardware used in these physical security systems; • the development of operator’s cyber security plan as distinct plan or as part of the physical or nuclear security of the operator’s assets;

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• responsibility of the operator to define the defense in depth security controls and levels of cyber security, based on a risk assessment in order to assure a high level of physical and nuclear security; • the requirement to report to relevant authorities upon – any attempt to extract information related to the physical security; – any cyber or physical attack that could lead to the shut down or alteration of one or more computers in charge of physical and nuclear security of the objective or NR materials; – any hybrid attack (cyber and physical) on the core computers; – NR material theft; – any other violation of the physical security system. • information management requirement to secure the information regarding the physical security of the nuclear and/or radiological objective as well as nuclear material data classified as “restricted” or higher, in relation to the category of the objective; • assuring the confidentiality of data regarding the physical security systems, NR installations and protected NR materials as a responsibility of the operator; • requirement to establish adequate security controls to assure the confidentiality of data regarding the physical security during the use, transportation or storage of NR materials in dependence of its category; • requirement to restrict access to data that might compromise the physical security systems of the objective, NR installations or materials; • requirement to treat as secret or confidential data any potential vulnerability information of the physical security systems; • inclusion of cyber security procedures in the physical security system, as well as protect the characteristics of confidentiality, integrity and availability of electronic databases or cyber systems and processes that might negatively influence upon the physical security system of the objective or protected materials; • identification of assets and systems, including IT ones, that are vital for the installation and object. This process has to be performed by the authorized operator together with experts in this field upon the implementation of the physical nuclear security system. This example of Regulation shows how cyber security slowly merges with other domains other than IT, as well as the importance of the definition of responsibilities such cases. In the context of cyber security, where the knowledge is specific and insights from the system have to be known when describing such parameters, it is necessary to have clear requirements that can be implemented by an operator and upon which a system can be audited against. It is also necessary to update the legislation continuously and the implementation should be sustained by adequate rigorous authorization processes and inspections. Without that, there is a low probability that the operators will implement sufficient security controls to deter the current threats. In spite of that, we appreciate, that the approved regulation is

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generally in line with IAEA recommendations and good practices and establishes the cyber security requirements towards the physical security systems, or systems that contain data related to it. We believe this regulation is a progressive step in the Moldovan NR legislation, and it is necessary to continue the cross-domain cooperation between cyber and other domains, in order to develop further policies and regulations to improve the security posture according to the current threat landscape.

16.3

Minimum Requirements on Cyber Security for Public Authorities

The approved Regulation on Minimum Security Requirements to Ensure Cyber Security of IT Systems [1] describes a variety of computer security topics and defines requirements for development and usage of IT systems. This is similar to an organizational policy for minimum security requirements of computer systems however at a national level. In general, the definition of requirements or regulations can be performance based, when these are described at a high level on what needs to be achieved, or prescriptive, when more technical details are listed. There is no best solution in this case as it depends on the maturity of the security culture, the resources an organization has, as well as the motivation to implement certain controls. Therefore it is not always easy to find the right approach and commonly this is a mix of the two types of requirements. These concepts are often used in the NR legal framework, however are applicable for other complementary domains such as cyber security. The MSR was developed by combining both the prescriptive and performance based approach and contains a list of security controls at the administrative as well as technical level that have to be implemented by all state institutions. The MSR applies including to NR operators of category I and II as well as the RA. The document defines the systems that should meet these requirements and introduces a mandatory system for information security management for the constituency. It also differentiates the controls based on the risk level, contains base security and advanced security requirements. This approach is welcome for institutions that have only basic IT systems with a low criticality and assessed risks, in order to avoid having control implemented only for compliance and not for ensuring the security level. The MSR also helps the users to categorize the systems to a risk category by looking at the following factors: availability of the system, type of information processed and importance of these systems within the organization. It includes as well the security requirements for usage of information systems, such as password complexity, connection to the Internet or email use policy, requirement to create backups or conditions for outsourcing the management of these systems. A parallel can be drawn to the IAEA NSS 17 [10], since similar recommendations can be found in this document, such as creating of a security policy enforced by the management

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or having a responsible officer for cyber security. Furthermore, such proposals on minimum-security controls or best practices are nowadays described by most of the domains as finance, healthcare or education. It can be assumed that the implementation of MSR will increase the level of cyber security for public authorities, which includes as well the operators of category I and II. Having written guidance on what type of controls have to be implemented and for which type of systems also aids the practitioners and auditors. On the other side, some of the prescriptive requirements could create issues in understanding and implementing them, as well as the technical requirements could become outdated in a short period of time due to the constantly changing threat landscape and mitigation solutions to be implemented. In countries where the level of security culture is still low, each new requirement is perceived as a necessity of more resources and knowledge on the implementer side. However, having a national regulation on such requirements will mobilize the institutions in identifying and prioritizing the resources in ensuring an adequate level of cyber security by the implementation of basic security controls. One aspect that we believe it is necessary to take into account with regards to prescriptive requirements is that besides the facilitation of the audit process, it could reduce the scope of such a regulation to a compliance check rather than looking at the goal of raising the level of security. Nonetheless, the MSR will help IT system administrators in creating a checklist for assessing the existing controls or those that need to be implemented. It is also welcoming the fact that these security requirements were enforced from a high level and will ensure that minimum security controls are implemented in the public authorities, including the NR operators of level I and II. Moreover, this will also reflect upon the private sector as this national guidance could be taken as a reference, or most probably used as a requirement for the procurement of IT systems description. We would like to mention, that there are signs of the MSR being followed, and mainly by the approval of the Ministry of Economy and Infrastructure of internal cyber security policy, the identification of systems and their criticality as well as the appointing of the responsible security office by the senior management [11]. These are the first steps in the elaboration of a cyber security program in any organization. Such a system for information security management, commonly referred by ISO27001 standard, is a good starting point in identifying the resources that are critical to the organization and ensuring that existing processes are documented, followed and can be auditable if needed. Most of the security programs, if not all, start from defining at the policy level the goals of the organization in terms of cyber security, which is followed by procedures and technical guidance in order to fulfill the high-level policy. Overall, we believe such regulations and actions will help towards the creation of a computer security baseline within public authorities, which would considerably improve the overall defense and resilience against cyber incidents on a national level.

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The legal framework in cyber and nuclear security is being updated continuously in the last years, due to the importance of the subjects as well as the high level of potential threats to the states. According to the new requirements in Republic of Moldova, each operator in NR domain is responsible to protects its digital assets including network, from cyber-attacks. The updated terms in the Moldovan legal frameworks regarding cyber security and NR are appreciated by us as an important step forward in further development on necessary legislative and sub-legislative background for better implementation in practice. Among the shortcomings of the normative framework, it is necessary to mentions that there is no National Concept or Strategy on Nuclear Security (or, e.g. more complex Strategy on CBRN, with containing a separate Chapter on Nuclear Security). Such strategy, followed by an Action Plan should identify short-terms and long-terms objectives, responsible authority/organizations and necessary financial support. The lack of qualified human resource is another unsolved subject that could lead to the low implementation of the discussed regulations. This issue is however a global one, as such niche areas require specialists that have a knowledge of both domains – cyber and nuclear. On the other hand, the National Cyber Security Program could support the training and development of human resources in cyber security for public authorities, which would have a positive effect on the high-risk domains as well such as the NR domain. This would be a long-term action because the operators as well as RA would need to take actions (identification of human and financial resources) to align with the requirements. The new Cyber Security Program and Regulation on Minimum Cyber Security Requirements is an advance in the process of securing critical systems and information in terms of computer security. The actions are expected to have a general security improvement for public authorities, also operators that use NR data or materials. The approval of a regulation at a high level and its development on a risk-based approach are good practices in establishing security regimes, however it is not always easy to find the balance between too technical and general regulations. The requirement definition process is tedious since it requires a deep knowledge and experience in IT security - too detailed requirements could be hard to implement and could become outdated in a short period, where general ones could leave space for interpretation. Therefore, good practices in developing requirements should be taken into account as well as possible past experiences from other states. The role of academic or specialized organizations (in other terms Technical and Scientific Support Organizations) is important in such cases to cover the knowledge and experience gaps and provide specialized support such as contracting experts or organizations that have the required skill in applied cyber security in niche fields as the NR one.

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The NR domain in Republic of Moldova is one relevant example where cooperation between different specialized organizations on a national level is needed, due to the specific knowledge. In order to raise security awareness and level of the nuclear security culture, it is necessary to develop cooperation frameworks by consulting experts from other areas including cyber. Another reason to promote this cooperation is the limited number of national experts in these fields. Indisputable, the implementation of the cyber security requirements will require exchange of knowledge with international experts, in order to ensure correct understanding of requirements for specific field as NR. As a recommendation, the IAEA NSS [3, 9, 10] help the operators in implementing them, as it recommends guidance on defining security controls at different levels, as well as technical and administrative controls. It also helps in understanding the role of computer security for industrial control systems or physical security and safety, as well as offers a good starting point to develop security policies within the organization.

References 1. Government Decision no. 201 from 28.03.2017 - On minimum-security requirements for ensuring cyber security of IT systems, hardware and software. Official Monitor of the Republic of Moldova no. 109–118 from 07.04.2017 2. Government Decision no. 1268 from 23.11.2016 - On Regulation on physical security on nuclear and radiological activity. Official Monitor of the Republic of Moldova no. 415, 29 November 2016 3. IAEA NSS no. 13: Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities (INFCIRC/225/Revision 5), Vienna (2011) 4. Buzdugan A (2016) Role of Cyber Security along with Nuclear and Radiological Safety in Medicine. Book of Abstracts. 3-rd International Conference of Health Technology Management. Ed. in Chief Victor Sontea, Chisinau, Pontos (Europress), p. 102. ISBN 978-9975-51774-4 5. Government Decision no. 811 from 29.10.2015 – On National Cyber Security Program of Republic of Moldova for 2016–2020, Official Monitor of the Republic of Moldova, no. 306– 310 from 13.11.2015 6. Establishment of the cyber security laboratory, Chisinau, Moldova (2016), http://cts.md/ro/ noutate/s-lansat-primul-laborator-de-cercetare-si-instruire-domeniul-securitatii-cibernetice 7. Law no 299 from 21.12.2017 – On information security concept. Official Monitor of the Republic of Moldova, no. 48–57 from 16.02.2018 8. Law no. 132 from 08 June 2012 (update on 2016 & 2017) – On safe deployment of nuclear and radiological activity. Official Monitor of the Republic of Moldova, no. 229–233 from 02.11.2012 9. IAEA NSS no. 17: Computer Security at Nuclear Facilities, Vienna (2011) 10. IAEA NSS no. 23-G: Security of Nuclear Information, Vienna (2015) 11. Order no. 402 of the Ministry of Economy and Infrastructure On the approval of internal cyber security policy (2017). http://mei.gov.md/ro/content/ordinul-nr402-din-28122017-cu-privirela-aprobarea-politicii-interne-privind-securitatea-1

Chapter 17

Microbially-Mediated Decontamination of CBRN Agents on Land and Infrastructure Using Biocementation Volodymyr Ivanov and Viktor Stabnikov

Abstract Physical, and chemical decontamination of CBRN-polluted land and infrastructure must be carried out following the military actions, industrial accidents, or terrorist attacks. This can be done by adsorption, chelation, ion exchange, degradation, or immobilization of CBRN agents and due to the coating or clogging of upper layer of soil or debris material. Biotechnological decontamination of land and infrastructure, as well as dust and leaching control of soil and demolition debris is an innovative approach, which is more acceptable in some cases than any other methods of decontamination due to its environmental safety, lower cost, and deep penetration of decontamination solution in soil. Dispersion of CBRN agents in environment with dust or leachate from the soil or debris surfaces can be decreased using such bioprocesses as microbially mediated ion exchange, adsorption, aggregation, chelation, precipitation, clogging of the pores, biocementation, biocoating, bioimmobilization, biochemical oxidation and degradation. Major processes of decontamination are as follows: (1) biocementation/biocoating of surface due to formation of calcium carbonate activated by enzyme urease hydrolyzing urea; (2) immobilization of CBRN agents due to formation of calcium carbonate during aerobic microbial degradation of calcium formate or acetate; (3) enzymatic or microbially-mediated formation of calcium phosphate biocement. Experiments with biocementation showed that more than 95% of chemical or bacteriological pollutants can be fixed in upper soil layer and do not dispersed in environment with dust or surface water flow. These technologies are feasible in the field conditions. However, a problem of this technology is brittleness of biocement, which can be solved using nanostructure composition of biocement with elastic nanocomponent modeling natural bone or other organic biominerals. Keywords CBRN agents · Microbially-mediated decontamination · Microbiallyinduced calcium carbonate precipitation · Dust control · Soil erosion control V. Ivanov (*) · V. Stabnikov Advanced Research Lab and Department of Biotechnology and Microbiology, National University of Food Technologies, Kyiv, Ukraine e-mail: [email protected] © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_17

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Decontamination of CBRN-polluted land and infrastructure (e.g. buildings, equipment, highways, etc.) must be carried out following the military actions, industrial accidents, or terrorist attacks. Pollutants can be dispersed to environment from soil or debris surfaces, so their physical or chemical immobilization will prevent pollution of air, food, surface water and groundwater [1]. To diminish negative effects to human health and environment, soil and demolition debris surfaces must be treated to remove, inactivate, or immobilize chemical, biological, radioactive and nuclear pollutants. This can be done using either mechanical methods such as washing, coating, or clogging of upper layer of soil or chemical and physico-chemical treatments such as adsorption, chelation, ion exchange, degradation, precipitation or immobilization of CBRN agents [2]. Biotechnological decontamination of land and infrastructure as well as the dust and leaching control of soil and demolition debris using biocementation method is an innovative approach. It is more acceptable in some cases than any other methods of decontamination due to environmental safety, lower cost, and deep penetration of the decontamination solution into soil or demolition debris [3, 4]. However, microbial decontamination could be usually slower and more sensitive to environmental conditions, especially to temperature and pH, than physical, chemical or physicochemical methods of decontamination. Biodecontamination of soil and demolition debris could be due to biogeochemical oxidation, reduction, transformation of toxic substances, and immobilization of substances or pathogens on soil or debris surfaces [3]. Last approach - immobilization of CBRN agents - is the fastest one among other biotechnological decontamination methods due to fast formation on insoluble compounds with CBRN agents. Most studied at present technology is widely called “MICP”, it is abbreviation of “microbially-mediated calcite precipitation”. This is actually scientifically incorrect term because not only calcite is produced during MICP and it is not just simply precipitation process because pure chemical precipitation did not produce cementing effect on the soil particles [5]. Roughly, MICP can be described by the following equation: CaCl2 þ ðNH2 Þ2 CO þ 2 H2 O þ urease  producting bacteria ! CaCO3 # þ2NH4 Cl

ð17:1Þ Usually, major mineral is calcite (Fig. 17.1) but depending on the conditions of biocementation there may be also vaterite or aragonite. It was shown that MICP co-precipitated radionuclides 90Sr, 60Co and metal contaminants such as Cd and this can be used to prevent their dispersion in environment [6, 7]. MICP captured up to 95% of the 1 mM Sr added to soil [8]. It is because strontium carbonate precipitated under same conditions as calcium carbonate [9].

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Fig. 17.1 Crystals of calcite produced during MICP

Dust is also a carrying agent for soil–associated pollutants such as chemicals, viruses and microorganisms [10, 11]. So, release of the polluted dust in atmosphere can cause deposition of these pollutants to ecosystem located downwind and negatively affect human health and environment. Runoff from the surface of soil or debris contaminated with CBRN agents causes pollution of natural water bodies and has strong negative impacts on human health, economy and ecology. Different chemical fixators of CBRN agents can protect atmosphere, surface water, and groundwater after radiation dispersal devise attack [12, 13]. However, treatments with chemical reagents have not been used in large scale because of their high cost and potential environmental hazard. Microbial aggregation of soil particles and crusting of soil surface could be more cost-effective approach because it is a common soil bioprocess in nature. It is known that MICP can be used for suppression of dust release to atmosphere [14–18] and soil pollutants release to water bodies [17]. The aim of this paper was to analyze and compare the microbiological methods for decontamination of CBRN agents on land and infrastructure.

17.2

Experimental

Microorganisms. The following isolated and identified bacterial strains have been used in research: Bacillus sp. VS1 (close but not identical to Sporosarcina pasteurii) see Fig. 17.2, Yaniella sp. VS8 (close but not identical to the representatives of Micrococcus genus), and Bacillus ginsengi strain VSA1. Bacillus sp. VS1 was used for conventional MICP, Yaniella sp. VS8 was used for biosafe MICP using killed cells of bacteria with remaining urease activity. Bacillus ginsengi strain VSA1 was used for aerobic oxidation of calcium acetate and production of calcium carbonate aggregating soil particles. Cultivation of bacteria have been done in the shaking flasks, as well as 5 L or 50 L fermenters with automatic

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Fig. 17.2 Pure culture of Bacillus sp. VS1. Red color shows hydrolysis of urease

control. Enumeration of colony-forming units (COU) was done using conventional microbiological methods on solid medium. Salt additions. 1 M solution of calcium chloride and 1.5 M solution of urea have been used for urease-dependent MICP, and 0.5 M solution of calcium acetate have been used for biocementation due to aerobic biooxidation of acetate. Methods of treatment. The horizontal surfaces were treated by spaying of the mixture of bacterial suspension and salt. Needed volume of solution for one treatment by spraying (Vp) was calculated using following equation: Vp ¼ Hp A P

ð17:2Þ

where Hp is the thickness of the biocemented layer of soil; A is the area of the treated plot, m; Hp is height of the treated soil, m; P is soil porosity. The thickness of the bioaggregated/biocemented layer (Hp) should be about 10 mm for bioaggregation of soil particles and about 20 mm to make a soil crust. Total volume of solution (Vt) and number of treatments (N ¼ Vt/Vp) can be calculated using following experimental data: the content of calcium carbonate in soil/sand (C, % w/w) should be about 2% (w/w) for the soil particles aggregation to prevent dust release, 10% (w/w) for the formation of soil crust, and about 20% (w/w) for hydro-insulation of soil layer to prevent dispersion of pollutants to surface water and groundwater. Chemical analyses. Analysis of heavy metals have been performed using standard methods for examination of water and wastewater [19]. The filtrate was analyzed using the inductively coupled plasma (ICP OES) emission spectrometer Optima 2000 DV (Perkin-Elmer, Inc., Shelton, USA). Two replicates were analyzed for each sample and the average value was reported.

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Results and Discussion

Microorganisms can decontaminate surfaces producing different structures in/on soil surface [20]: – bioaggregation of soil particles is an increase of the aggregates of the soil particles due to microbially-mediated formation of insoluble minerals, biopolymers or microbial biofilms. Effect of bioaggregation could be used to control water and wing erosion of soil; – biocrusting of soil is formation of mineral crust or photosynthetic biofilm near soil surface by microorganisms, so that erosion, dust emission, and water infiltration will be reduced. The thickness of the mineral biocemented crust can be up to several mm [21]; – bioclogging of soil or the cracks in concrete is the filling of the micropores, microchannels, microcracks by microbially produced minerals or biopolymers so that hydraulic conductivity of soil will be significantly reduced; – biocementation of soil is the binding of the particles to form strong crust and increase significantly strength of soil; – biocoating of concrete surface contaminated with CBRN agents can be performed using conventional MICP [22]. It will decrease the release of these agents to environment from construction debris; – bioencapsulation of soft clayey soil [23] can stop release of the CBRN agents due to formation of strong shell around a piece of soft clay; – bioremediation of polluted soil is removal of the pollutants from soil or immobilization of the pollutants in soil to diminish the release of the pollutants from soil to air, water, human, plants and animals. Bioaggregation of Soil Particles In our experiments [15], after MICP treatment of sand surface with the quantity just 15.6 g Ca/m2, the release of sand dust and its artificial pollutants to atmosphere decreased in comparison with control by 99.8% for dust itself, 92.7% for phenantherene, 94.4% for led nitrate, and 99.8% for bacterial cells of Bacillus megaterium. This immobilization of dust and dust pollutants was due to bioaggregation of the fine sand particles. The sizes of 90% of the sand dust particles increased from 29 μm in control to 181 μm after MICP bioaggregation. So, MICP bioaggregation of soil particles could be effective ad environmentally friendly way to fix SBRN agents on soil surface. Bioaggregation treatment of the soil surface could be useful method to prevent the dispersion of dust and the dust-associated chemical and bacteriological pollutants in water, air and soil [15]. Biocrusting of Soil We tested two technologies for the formation of almost water impermeable soil crust: (1) conventional urease-dependent MICP by spraying of bacterial suspension with addition of calcium chloride and urea [21]; (2) formation of carbonate minerals by spraying of bacterial suspension with addition of calcium acetate following by aerobic oxidation of acetate [22, 23]. In last case biomineralization was due to the following biochemical reaction:

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Fig. 17.3 Spray biocementation of sand with bacterial suspension and salts

Fig. 17.4 Crust on the surface of the treated sand

CaðCH3 COOÞ2 þ 4 O2 ! CaCO3 # þ3 CO2 " þ3 H2 O

ð17:3Þ

In case of conventional MICP [21], after six sequential batch treatments with suspension of urease-producing bacteria and solutions of urea and calcium salt, the permeability of sand was reduced from 5x104 to 2x107 m/s (Fig. 17.3). The module of rupture of the upper crust layer (Fig. 17.4) was 35.9 MPa. This value is comparable to that of limestone. Therefore, the crust layer has not only low permeability to provide an impervious layer but also adequate and stable strength. The calcium contents in the crust and in the sand below the crust were 20–21% and 2–4% (w/w), respectively. Quantity of precipitated calcium after six treatments was 1.5 kg of Ca per m2 of sand surface for the case of MICP in the bulk of sand. In other experiments, with the treatment using dead but urease active bacterial cells the hydraulic conductivity of sand was decreased from 5∙104 m/s to 8∙109 m/s [23]. In case of mineralization due to aerobic biooxidation of calcium acetate (Fig. 17.5) [22, 23], four sprayings decreased hydraulic conductivity from 5  10–4 to 3  10–6 m/s. Major portion of calcium bicarbonate is concentrated in upper 2 cm depth layer.

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Fig. 17.5 Crystals of calcium carbonate after aerobic oxidation of calcium acetate with the imprints of bacterial cells. There are visible the places of bacterial cells inside calcium carbonate

Biocrusting could be stronger way of decontamination of CBRN agents on land and infrastructure than bioagregation but it will require higher dosage of calcium salt for the formation of strong crust. Bioclogging and Biocementation of Soil Bioclogging is performed using grouting, which is a process to fill the soil voids with fluid grout and control water flow in soil. Such common grouts as solutions or suspensions of sodium silicate, ultrafine cement, acrylates, acrylamides, and polyurethanes can block the release of CBRN agents from polluted soil but they have such disadvantages as high viscosity and low depth of penetration in soil, and often high cost and toxicity. Bioclogging or biogrouting is performed either using formation of microbial biopolymers but it is slow process or microbially-induced precipitation of inorganic compounds in situ for water flow control [24]. Biocementation also can be used to block the release of CBRN agents from polluted soil but its major function is to strengthen porous materials or fractured concrete. Conventional cement cannot be used in many cases due to high viscosity of cement paste. Dry biocement can be dissolved and as solution of low viscosity can be sprayed over, injected in, or percolated through the porous material for its strengthening. Sand (Figs. 17.6a and 17.7) and gravel can be bound using MICP (Fig. 17.6b). Average of unconfined compressive strength (Y, MPa) of biocemented sand depends on the content (%, w/w) of precipitated CaCO3 (X) by the following equation [5]: Y ¼ 0:15X if X < 20%

ð17:4Þ

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Fig. 17.6 The layers of biocemented sand (a) and gravel (b)

Fig. 17.7 A cube of 1 m3 of biocemented sand

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Fig. 17.8 A sample of the clogged basalt rock with 4 fissures

Fig. 17.9 Connection between MICP coating and concrete surface

Maximum of hydraulic conductivity (kmax, ms-1) of biocemented sand depends on the content (%, w/w) of precipitated CaCO3 (X) by the following equation [20]: lg kmax ¼ 4  0:1X if X < 20

ð17:5Þ

So, only the quantity of precipitated calcium carbonate will determine the protective properties of bioclogging/biocementation. However, a problem of this technology is brittleness of biocement, which probably can be solved using nanostructure composition of biocement with elastic nanocomponent modeling natural bone or other organic biominerals. Due to low viscosity the solution of biocement can penetrate in the cracks of several microns width (Fig. 17.8). Biocoating Biocoating of concrete surface (Figs. 17.9 and 17.10) contaminated with CBRN agents can be performed using conventional MICP. It will decrease the

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Fig. 17.10 Concrete surface coated using MICP

release of these agents to environmental from construction debris. MICP biocoating could be cheaper, more sustainable, environmentally friendly, and more aesthetical than any other types of the concrete surface coating. Other materials such as wood, plastic, glass, clay can be also coated with the calcium carbonate layer using MICP biotechnology.

17.4

Conclusion

It can be concluded from the above results that the microbial biocementation can be used to decontaminate CBRN agents on land or construction debris using bioaggregation of fine particles, formation of the mineral crust on surface, bioclogging of micropores, microchannels and microcracks, biocementation of porous or granulated materials, biocoating of concrete surface, direct precipitation of CBRN agents during MICP. These effects decrease the release of CBRN agents to environment from polluted surfaces of land or construction debris. So, biocement should be tested in the field for decontamination of CBRN agents on land and debris.

References 1. Koren H, Bisesi MS (2016) Handbook of environmental health, fourth edition, volume II pollutant interactions in air, water, and soil. CRC Press, Boca Raton 2. Nygren M (ed) (2016) 12th International Symposium on Protection against Chemical and Biological Warfare Agents. Stockholm

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3. Ivanov V, Stabnikov V (2017) Bioremediation and biodesaturation of soil. In: Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 223–234 4. Ivanov V (2015) Environmental microbiology for engineers, 2nd edn. CRC Press/Taylor & Francis Group, Boca Raton 5. Ivanov V, Stabnikov V (2017) Biocementation and biocements. In: Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 109–132 6. Fujita F, Redden GD, Ingram JC, Cortez MM, Ferris FG, Smith RW (2004) Strontium incorporation into calcite generated by bacterial ureolysis. Geochim Cosmochim Acta 68:3261–3270 7. Mitchell AC, Ferris FG (2005) The coprecipitation of Sr into calcite precipitates induced by bacterial ureolysis in artificial groundwater: temperature and kinetic dependence. Geochim Cosmochim Acta 69:4199–4210 8. Warren LA, Maurice PA, Parmar N, Ferris FG (2001) Microbially mediated calcium carbonate precipitation: implications for interpreting calcite precipitation and for solid-phase capture of inorganic contaminants. Geomicrobiol J 18:93–115 9. Anderson S, Appanna VD (1994) Microbial formation of crystalline strontium carbonate. FEMS Microbiol Lett 116:43–48 10. Falkovich AH, Schkolnik G, Ganor E, Rudich Y (2004) Adsorption of organic compounds pertinent to urban environments onto mineral dust particles. J Geophys Res 109:D02208 11. Raisi L, Lazaridis M, Katsivela E (2010) Relationship between air-borne microbial and particulate matter concentrations in the ambient air at a Mediterranean site. Global NEST J 12:84–91 12. Cordesman AH (2002) Terrorism, asymmetric warfare, and weapons of mass destruction: defending the U.S. homeland. Praeger Publishers, Westport 13. Parra RR, Medina VF, Conca JL (2009) The use of fixatives for response to a radiation dispersal devise attack – a review of the current (2009) state-of-the-art. J Environ Radioactivity 100:923–934 14. Bang S, Min SH, Bang SS (2011) Application of microbiologically induced soil stabilization technique for dust suppression. Int J Geo-Eng 3:27–37 15. Stabnikov V, Chu J, Myo AN, Ivanov V (2013) Immobilization of sand dust and associated pollutants using bioaggregation. Water Air Soil Pollut 224:1631 16. Chen F, Deng C, Song W, Zhang D, Al-Misned FA, Mortuza MG, Gadd GM, Pan X (2016) Biostabilization of desert sands using bacterially induced calcite precipitation. Geomicrobiol J 33(3–4):243–249 17. Ivanov V, Stabnikov V (2017) Soil surface biotreatment. In: Ivanov V, Stabnikov V (eds) Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 179–197 18. Wang Z, Zhang N, Ding J, Lu C, Jin Y (2018) Experimental study on wind erosion resistance and strength of sands treated with microbial-induced calcium carbonate precipitation. Advances in Materials Science and Engineering, Article ID 3463298. https://doi.org/10.1155/2018/ 3463298 19. APHA (2012) Standard method 3120 B, Inductively Coupled Plasma (ICP) method. In: Standard Methods for the Examination of Water and Wastewater, 22 ed., American Public Health Association, Washington, DC, pp 3–46 20. Ivanov V, Stabnikov V (2017) Biotechnological improvement of construction ground and construction materials. In: Ivanov V, Stabnikov V (eds) Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 91–107 21. Stabnikov V, Chu J, Naeimi M, Ivanov V (2011) Formation of water-impermeable crust on sand surface using biocement. Cem Concr Res 41:1143–1149

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22. Ivanov V, Stabnikov V (2017) Biocoating of surfaces. In: Ivanov V, Stabnikov V (eds) Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 198–222 23. Stabnikov V, Ivanov V, Chu J (2016) Sealing of sand using spraying and percolating biogrouts for the construction of model aquaculture pond in arid desert. International Aquatic Research 8 (3):207–216. https://doi.org/10.1007/s40071-016-0136-z1-10 24. Ivanov V, Stabnikov V (2017) Bioclogging and biogrouts. In: Ivanov V, Stabnikov V (eds) Construction biotechnology: biogeochemistry, microbiology and biotechnology of construction materials and processes. Springer, Singapore, pp 139–178

Chapter 18

Point-Contact Sensors as an Innovative Tool in Defense Against Chemical Agents, Environment and Health Risks: A Review G. V. Kamarchuk, А. P. Pospelov, L. V. Kamarchuk, A. V. Savytskyi, D. A. Harbuz, and V. L. Vakula

Abstract The review covers the most recent results and advancements in pointcontact nanosensors. Fundamentals of Yanson point contacts that determine their spectroscopic and sensor behaviour are considered. A special attention is paid to the basic properties of these nanoobjects which are responsible for their ability to demonstrate the point-contact gas-sensitive effect and excellent sensor performance. Classification of point contacts into homo- and heterocontacts and peculiarities of their electric characteristics are described. The technological principles of Yanson point-contact spectroscopy used for designing various types of point-contact sensors are discussed. The innovative approaches in sensor engineering which are evident from the peculiar properties of point-contact sensors are presented. The point-contact method of sensor spectral analysis of complex gas mixtures which does not require detection of separate components, and selective analysis of gaseous and liquid media through conductance registration in dynamic regime are introduced. Prospects for application of point-contact sensors for security, environmental and health issues are discussed.

G. V. Kamarchuk (*) · A. V. Savytskyi · V. L. Vakula Department of Spectroscopy of Molecular Systems and Nanostructured Materials, B. Verkin Institute for Low Temperature Physics and Engineering, Kharkiv, Ukraine e-mail: [email protected] А. P. Pospelov · D. A. Harbuz Department of Physical Chemistry, National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, Ukraine L. V. Kamarchuk Pediatrics Department, SI “Institute for Children and Adolescents Health Care” of NAMS of Ukraine, Kharkiv, Ukraine Department of Fundamental Medicine, V. Karazin Kharkiv National University, Kharkiv, Ukraine © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_18

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Keywords Yanson point-contact spectroscopy · Point-contact sensors · Dendrite · Gas detection · Electronic transport in quantum wires · Cyclic switchover effect · Electrochemical synthesis · CBRNE agents · Helicobacter pylori · Breath test

18.1

Introduction

The development of sensory devices has been one of the most dynamic activities in recent years. Among the key priority fields, the sensor research includes defence against Chemical, Biological, Radiological, and Nuclear (CBRN) agents, CounterTerrorism and Environmental Security issues [1, 2]. The importance of these fields is due to the ability of many CBRN agents, even in small quantities, to significantly affect the personal security of people and the stability and international prosperity in general. The problems of ecological security are, in many cases, either directly related to CBRN agents or detectable through them. For example, environmental pollution caused by various industrial emissions brings multi-faceted security threats. The pollutants may include substances which, even in minute quantities, can be very hazardous to people’s health. The substances emitted into the atmosphere in large quantities, in addition to being harmful to living creatures, disrupt ecosystem balance. This leads to climate change which, in turn, can result in global upheavals. To prevent the emergence of ecological security threats and global health risks it is necessary to efficiently detect and control CBRN agents at the level of small and ultra-small concentrations. CBRN and explosives agents are usually constituents of complex mixtures of various origin, including environmental compounds. Detailed analysis of these substances is difficult and even more challenging due to mutual interaction of their components. At the moment, there are different methods and technologies for detection and analysis of these materials. A wide range of techniques for analyzing gas, liquid and solid materials is currently being employed. Mass-spectrometry, gas chromatography-mass spectrometry, X-ray systems, infrared and luminescence spectroscopy, ion mobility spectrometry are at the forefront [3–10]. Even though these conventional techniques yield adequate results, they are hampered by a number of restrictive disadvantages, being costly, sophisticated and bulky. The necessity of collecting and pre-processing samples for some of the techniques, as well as the need of highly skilled personnel to provide technical maintenance, hinder their widespread use in everyday practice. Therefore simple and inexpensive technologies allowing real time analysis with no preliminary selection and processing of samples are desirable for analysis of explosives and CBRN materials. Specifically designed sensors have become available in the last decade. Simple devices based on novel technologies have proven to be inexpensive, easy-to-use and reliable alternatives in the analysis of gas and liquid media [11–18]. Sensor technologies can be widely used in various fields such as public health and forensic medicine, food industry, control of environmental risks and infection agents, etc. The portability of devices and their simplicity are a basic requirement for promptly

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supplying them to as many people as possible. This is very important for early detection of an emerging security threat and its subsequent removal. One of the promising trends in sensor design is development of sensors based on various nanoobjects [19]. Application of nanoobject technologies yields new invaluable opportunities to considerably improve the sensor techniques. For example, introduction of Yanson point contacts into sensor technique leads to the conception of new nanosensors which are free of the typical disadvantages of conventional sensors [11]. The use of a wide range of materials for synthesis of point-contact nanostructures guarantees unique metrological characteristics of sensor devices based on such nanostructures. The distinctive feature of point-contact sensors is the advanced know-how of the Yanson point-contact spectroscopy [20] and original areas in sensorics which have no analogues in the world [11]. This will ensure development of innovative quantum technologies operating at the cutting edge of detection limit of sensitive devices. Combination of the unique fundamental properties of point contacts, advanced functional materials and novel technologies will allow one to create new devices with excellent and unprecedented characteristics [21–26]. The aim of this review is to present point-contact sensors as a new type of modern transducers, describe the principles of their operation and demonstrate their potential in solving the CBRN-, environment- and health-related problems.

18.2

Yanson Point-Contact Spectroscopy: General Correlations Essential for Point-Contact Gas-Sensitive Effect and Sensor Operation

Fundamentals of Yanson point contacts that determine their spectroscopic behavior and are essential for the development of point-contact sensors have been discovered in the framework of Yanson point-contact spectroscopy [20, 27–29]. Here, we briefly present the main physical peculiarities which are responsible for the spectroscopic and sensitive properties of point contacts. The main correlation which determines the differences in behaviour of Yanson point contacts and ordinary electrical contacts is the correlation between the contact diameter and the mean free path of electrons in the contact area. A Yanson point contact is usually defined as a contact of small size created between two bulk metallic electrodes touching each other on a small area [29]. Several theoretical models are used to describe the properties of point contacts. One of them is the model of orifice in an infinitely thin partition which separates two metallic halfspaces and is impenetrable for electrons [28, 30] (Fig. 18.1a). The orifice can have various shapes: for example, a circle, an ellipse, or a rectangle. In the case of a circular orifice, the characteristic dimension of the point contact is its diameter d. If the surface of contacting electrodes is covered with a rather thick dielectric layer, the point contact created in this way can be described within the model of long

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Fig. 18.1 Theoretical models of Yanson point contacts. (a) Model of a point contact in the form of a circular aperture in an infinitely thin and impenetrable for electrons screen separating two metallic half-spaces. d – point contact diameter, Z – axis of symmetry perpendicular to the aperture plane. (b) Long cylindrical metallic channel with the length L

cylindrical metallic channel with the length L >> d [31] (Fig. 18.1b). It should be noted that, in principle, variation of the contact shape has no impact on the nature of the physical processes inside the contact and does not lead to any qualitative change of the results of the Yanson point-contact spectroscopy [29]. As a consequence, the current-voltage characteristics (IVC) of a point contact do not depend qualitatively on geometric parameters of the object. Yanson point contacts have direct conductivity, that is they do not contain tunneling barriers and their size is smaller than or close to the mean free paths of charge carriers, d Λ. In the thermal regime, the small values of inelastic mean free paths of phonons determine the deviation of the phonon system from equilibrium. The gas of excitations in the contact becomes nonequilibrium, which causes variation in the effective temperature of the material in the constriction area. As a result, an essential Joule heating of the metal and temperature increase in the point contact take place upon rise of the applied voltage [37, 38]. The thermal regime can be considered as determining the conditions which lead to the transition from the contact behaviour to conventional behaviour of bulk materials. There are several basic properties of Yanson point contacts which are responsible for their ability to display the point-contact gas-sensitive effect and to a great extent determine their excellent performance. One of the main peculiarities of Yanson point contacts is the original current state. It is characterized by an electrons distribution which is essentially different from that of a homogeneous conductor. As it was shown by Kulik et al. [28], the electric field is concentrated in the constriction area which covers a space with a characteristic dimension of the order of d in the point contact. This can be related to the potential distribution. The electric potential φ(r) can be described in the ballistic regime by the equation [28]: V φðzÞ ¼ 2

rffiffiffiffiffiffiffiffiffiffiffiffiffi!1 a2 sign z 1þ 2 z

and in the point r of the contact area it approaches its constant value V/2 at a distance of the order of the orifice radius a according to the law ~a2/r2 (Fig. 18.2). Here z is the coordinate measured from the centre of the point contact along Z-axis of the contact, V is the voltage applied to the contact. A similar situation is observed in the diffusive regime [29, 36, 39]. This means that when electrons flow through the contact, they are accelerated by the strong electric field in the constriction area over a distance of ~d and get an excess energy of eV. As a result, electron states with a nonequilibrium energy distribution function are formed in the contact area [28]. The potential distribution in Yanson point contacts is of great importance for understanding the operation of point-contact sensors. Let us consider a point contact Fig. 18.2 Distribution of the potential (eV) along Z-axis of the point contact of diameter d ¼ 2a. (Data are taken from [40])

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in the long channel model [29, 31]. A current flowing in a contact channel of diameter d delivers a voltage bias which drops over a distance equal to the channel length (Fig. 18.2). This means that the resistance of this small area determines the resistance of the entire “bulk electrode – point contact – bulk electrode” system. As a consequence, the interaction of the bulk electrodes forming the point contact and current-feeding wires with the surrounding gas yields a negligible contribution to the point contact resistance and is not registered. The reaction between the gas and the point contact constriction area determined by the point-contact conductive crosssection only contributes to noticeable resistance variation of the whole structure. With Ångström- or nanometer-sized point contacts, one atom of gas may be enough to react with the material in the constriction area and induce measurable changes in the electric conductivity of the contact. This yields an incomparably high sensitivity to the point-contact sensitive element. Thus, the lowest detection limit at the level of a gas molecule is achievable for point-contact sensors. As a consequence, the bulk structure «electrode – point contact – electrode» permits creation of a wide range of nanostructured tools made with point contacts [20, 29] without using expensive equipment which is often necessary for other nanostructured devices. This circumstance establishes a solid background for the creation of supersensitive point-contact gas nanosensors [11, 24, 26], as well as for prospective new research and developments for point contacts operating in liquid media [33, 41]. Taking into account the experimental conditions when measuring the pointcontact sensor response to the gas action, the current density in the contact reaches a colossal value of  107 A/cm2 [40]. Such a level of current density would destroy a conventional homogeneous or nanostructured conductor. Homogeneous metals melt at current densities of 102–103 A/cm2. A point contact could hardly retain its structure at this high current density if its behaviour was that of bulk material. It could be destroyed under the experimental conditions even earlier because of softening of the conductive material at current densities less than 102 A/cm2. Yet the bulk electrodes effectively remove excessive heat from point-contact samples [20] allowing them to keep their mechanical stability for a long period. Electric current distribution in the Yanson point contact depends on the ratio of electron mean free path l to the point contact diameter d. In the pure limit (ballistic regime), the current distribution is uniform, while in the diffusive and thermal regimes with a small mean free path the current is concentrated near the aperture edges [36, 42, 43]. The lower the l-to-d ratio, the more pronounced the effect. Adsorption of gas atoms on the surface of the point-contact channel causes a decrease in the electron mean free path in the contact. As a result, the current density in the superficial layer of the point-contact material can significantly exceed the high current density observed in the ballistic regime at liquid helium temperatures (109– 1010 А/cm2 [35]) with a uniform distribution of current lines across the whole contact. Thus a decrease in the electron mean free path favours heat release in this part of the contact as well as transfer of energy to the adsorbed atoms, which can now desorb more easily. In this connection it should be emphasized that electron system in the point contact exists in a non-equilibrium state in the absence of lattice heating effects [28, 29]. The possibility of separating the thermal and nonlinear current

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effects in point contacts is their distinctive feature, which homogeneous conductors and other nanostructured sensors do not possess. In the case of a homogeneous conductor, the processes of electron inelastic scattering, which are responsible for the electric resistance in a conductor, and energy relaxation processes are combined and occur uniformly in the whole volume of the sample. As a result, a homogeneous sample melts before the electron gas is able to gain an excess energy of the lattice vibrations level. The short relaxation time of a point contact sensor is presumably associated with the high current density [40, 44]. The current flow through the contact causes scattering of charge carriers at defect sites which appear in the adsorption area. Thus, the decrease in the carrier mean free path promotes a heat discharge leading to an effective molecular desorption and fast signal relaxation to the equilibrium state. The specific voltage distribution in the Yanson point contact is an important prerequisite for this nanoobject to be used and studied as a new type of electrochemical nanoelectrode element. A Yanson point contact can serve as a nanostructured instrument to control chemical processes on the nanoscale level thanks to the voltage distribution in the narrow part of the contact since the conductivity channel of a point contact immersed in electrolyte transforms into a gapless electrochemical electrode system [33, 45, 46]. This is a new type of electrochemical electrode system which allows electrochemical synthesis of a broad spectrum of structures, samples, and functional materials and creates the necessary conditions for efficient operation of supersensitive and selective point-contact quantum sensors. In contrast to the traditional electrochemical electrode system composed of at least two separate electrodes with no direct channel of electron conductivity, the gapless electrode system is a monolithic conductor with the potential distributed monotonously along the longitudinal axis. A macroscopic model of the gapless electrode system can be presented by any metal wire immersed into electrolyte [47]. The main condition for its successful operation is creation of a potential drop at the opposite ends of the sample which is high enough to start the electrochemical processes. This can easily be accomplished on the nanoscale level in a Yanson point contact thanks to the unique potential distribution distinctive to this nanoobject. The ability of point contact to concentrate electric field and keep its key parameters under a super high current density is combined with an oppositely directed electrochemical activity located at the ends of the point contact conductivity channel. The electric field concentration and monotonous change of the potential along the point-contact channel create conditions when the reductive processes can proceed on the side of the negative pole of the electric energy source and the oxidative ones can go on the side of the positive pole. To realize these processes it is necessary that the potential difference across the point contact channel is higher than the decomposition voltage of the electrode system which in this case consists of electrodes arising at the opposite ends of the point-contact conductivity channel [41]. Spatial approach of the controlled electrode processes at a distance of the order of nanometer units, realized in the gapless electrode system, is practically unattainable for the already known thin-layered electrochemical cells [48]. This fact allows observing new nanodimensional effects using the gapless electrode system. One of such findings

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is the new cyclic electrochemical effect, or cyclic switchover effect [46]. Combination of the cyclic switchover effect with the quantum structural and electronic characteristics of the point contact during electrochemical synthesis allows developing a new method for manufacture of nanoobjects down to the size of a single atom [33]. Such an approach could be used in industrial manufacture of pointcontact sensors with extremely small sizes showing drastic improvement of their metrological parameters. Thus, using transport phenomena in the point contacts immersed into electrolyte, one can both ensure control of the nanostructure production process with the necessary parameters and capture the signal of response to the action of the substance dissolved in the liquid medium [33]. In addition, the probability distribution of dendrite nanostructures with a specific range of resistance range and crosssections during the point-contact synthesis depends essentially on the electrolyte composition. This opens up wide prospects for the design of high performance nanostructured quantum point-contact sensitive elements [49].

18.3

Architecture of Point-Contact Sensors

18.3.1 Point Homocontacts and Heterocontacts According to the nature of electrical properties of materials used to produce Yanson point contacts, these nanoobjects can be classified into two groups, namely, homocontacts and heterocontacts. A homocontact is a contact of small size created between two bulk metallic electrodes made of the same material. A point contact formed between two electrodes made of different metals is called a heterocontact. The two groups of point contacts are characterized by the properties of Yanson point contacts described in Sect. 18.2, that is reveal both spectral and gas-sensitive aspects. At the same time, heterocontacts exhibit some peculiar properties which distinguish them from homocontacts. The partial contributions of each metal to the heterocontact spectrum depend strongly on the ratio of their electronic parameters – the Fermi momentum pF and velocity υF [50]. In the pure limit, the relative intensity of the electron-phonon interaction (EPI) spectrum of one of the ‘banks-electrodes’ is higher for a smaller electron Fermi velocity – it is proportional to the time of flight of electron through the heterocontact. The heterocontact resistance is a sum of the contributions of the two ‘bankselectrodes’. This is due to the fact that the lower the velocity of electron in the heterocontact area, the higher the probability of its scattering on phonons. A deviation of the heterocontact volume composed of one of the electrodes towards values above or below half of the volume of the contact area leads to a difference in the efficient volumes in which phonons are generated in each of the metals and thus to a difference in their contributions to the resulting heterocontact spectrum. As a rule, a change in the shape and symmetry of the heterocontact during

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its formation is accompanied by a change in its resistance. The possibility of producing symmetrical samples largely depends on the production method. Another difference between heterocontacts and homocontacts is that because of the different Fermi momenta of the metals forming the heterocontact the processes of reflection and refraction of electron trajectories at the metal interface start playing an important role. A difference in the conduction band widths of the metals in contact results in an internal potential barrier at the heterocontact interface. As a consequence, there is a limitation for electrons to go from one metal to the other and only scattering at h angles exceeding some minimum value θmin [51], i  1=2 θmin ¼ 2 arcsin v2F1  v2F2 =vF1 , can take place in the heterocontact. Also some phonons may be excluded from the EPI process. This leads not only to a change in the partial contributions of the contacting metals, but also to a resulting heterocontact EPI spectrum which is different from the sum of contributing spectra [20]. These properties of heterocontacts can be successfully used to create heterocontact-based sensors. They make it possible to technologically implement to the existing advantages of this new class of ultra-sensitive elements. Usage of the sample materials, which are able to efficiently adsorb gas components and vary their own resistive properties during the process, is quite reasonable for the production of sensors. Developing heterocontact-based sensors, one can select a pair of electrodes in which one of them ensures a favourable regime of current flow with large electron mean free paths, while the other is responsible for the sensor performance. Thus, there is a possibility for a huge variety of compounds to be used as sensitive materials. Even the most common metals may demonstrate high sensitivity to different gases and be prospective for these novel transformers [40]. High selectivity of point heterocontact sensors can be a result of the special combination of various conductive materials tuned to a desired group of analyte molecules. For example, in point heterocontacts it is possible to apply carbon nanotubes blended with different types of sensory polymers. This is confirmed by Au/SWNT point heterocontacts, in which SWNT interaction with gases of different nature (oxidizing or reducing) dominates the device functionality, and such point heterocontact sensors demonstrate selective response inherited from SWNTs [44]. This fact also indicated that the gas-sensitive properties of heterocontacts are associated with their spectroscopic characteristics.

18.3.2 Elements of the Technology for Producing PointContact Sensors Production of point contacts and the point contact sensors with desired characteristics as a new class of super-sensitive elements for monitoring of gas and liquid media is based on strict fulfilment of the entire set of technologic requirements, which include a high purity of the material the contacts are made of, mechanical, thermal,

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chemical and/or electrochemical processing of electrodes that are going to be in contact. Therefore, according to the above tasks the necessary conditions and requirements were studied and the methods of production of appropriate point contacts have been developed in the framework of Yanson point-contact spectroscopy and point-contact gas-sensitive effect studies [11, 20, 29]. The developed principles were used to manufacture prototypes of mechanical devices with piezoelectric drives, mechanisms of twisting or micro-shifting of electrodes [52, 53]. Point contacts obtained with the help of these miniature devices are open to action of the probed gas. The point contacts produced using the technology “know how” of the Yanson point-contact spectroscopy demonstrate stable electric resistance in equilibrium state before the main experiments, or after the relaxation period following the interruption of the external agent influence. In the case of production of point contact sensors, it is possible to realize a unique scheme involving a nanosized sensitive element based on the ordinary bulk (macroscopic) electrodes. As a result, an ultra-sensitive device can be produced within a technique traditionally and reliably tested in the Yanson point-contact spectroscopy and needing no additional, complicated, costly equipment and components. Moreover, rather high signals allow one to use simple techniques for registration. The growth of the contact response to the repeated gas exposure makes it possible to use a simple multimeter for registration purposes. This clearly demonstrates the opportunities provided by the creation of portable devices based on point-contact sensors. Consider now some of the methods of producing Yanson point contacts used in point-contact sensors. The various methods of contacts creation involving pressure are usually based on pressing of the electrodes with a certain force. Let us consider the “needle-anvil” type [20, 29] of point contact as an example of the device. For this case, one of the electrodes is made in a form of the needle with its tip radius of about 1 μm, while the other is provided with a well polished plate at its working part (Fig. 18.3a). The electrode surfaces are coated usually by the oxide layer. The Fig. 18.3 Methods of point contacts creation. (a) Needle-anvil technique. (b) Chubov displacement technique. (c) Break junction technique. (d) Dendrite point contact

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manufacturing practice of point-contacts demonstrates that their electrical resistance depends significantly on their composition and thickness. The oxide has an important function in the process of mechanical stabilization of the direct metallic contact. The “needle-anvil” contact is formed when the oxide is pressed out of the area of the highest concentration of mechanical tension between the electrodes. It is worth mentioning that the substantial thickness of the insulating layer on the electrode surface requires a substantial pressing effort to create the contacts. On the other hand, if the process of point-contact production using the “needle-anvil” technique is accompanied by significant efforts applied to press the electrodes together, it may cause plastic deformations of the material in the contact area. The deformation, in its turn, greatly affects the quality of the obtained point contacts. To avoid this, the power of the electrode pressing should be decreased. However it is necessary to take into account that excessive decrease of the pressing power leads to mechanical instability of the contacts. A big amount of statistically processed experimental data allows one to assert that the most efficient and the least laborious method of the point-contacts production is that based on the Chubov displacement technique [54]. According to this method, point contacts are produced between bulk metallic electrodes of high purity by making them touch each other and then shifting one electrode with respect to another (Fig. 18.3b). Development of the technique and its adaptation to various conditions has allowed producing great numbers of samples in a short period of time, significantly intensifying the the research process. The distinctive feature of the Chubov displacement technique for creating contacts between bulk electrodes is to abandon the idea of punching a hole in the oxide layer and instead extrude the layer by sliding the electrodes. Practical results demonstrate that sliding electrodes ensure the most efficient elimination of the oxide from the area of the metallic contact. Compared to “needle-anvil” contacts, this technique creates significantly smaller deformations in the metallic layers below the surface. In this case, the metal in the contact is virtually indistinguishable from that in the depth of the electrodes. The pressing-type contacts are created with the help of special devices for microdisplacements of electrodes [52]. These devices ensure precise regulation of the pressing force between the electrodes during their mutual displacement, as well as a smaller metal lattice distortion in the area of contact creation. A better mechanical stability is achieved by attaching one of the electrodes to a wire damper. The electrodes used to produce point contacts, can be shaped as a prism or a cylinder with a linear size of about 5–15 mm and a cross-section being 0.5–2 mm. Chemical sensors of all types undergo changes caused by irreversible processes occurring in the surface layers of the sensitive element during its interaction with the analyzed gas. This effect leads to a drift of sensor parameters and a poor reproducibility of results due to a shorter durability of sensor operation. The lifetime of the sensitive element decreases and it should be replaced in time. Therefore, to ensure correct measurements, only fresh, active surfaces must be used in each of the repeated tests of the gas medium. The Chubov displacement technique solves the problem [54]. It allows an easy and fast creation [29, 44] of many various point contacts in a wide range of resistance to choose the necessary sample for further use.

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This technique also provides realization of the concept of using a point contact as a consumable sensitive element with fast replacement. The Chubov displacement technique is the basis for the formation of a new technology for fast and reliable creation of necessary point contact sensors anywhere at any time using the same point contact device. Such a sensor device will therefore have no time limitation of its work. Besides the pressing technique for production of point-contacts, there also exists the so-called break-junction method [55]. Instead of pressing together two electrodes one of them gets broken (Fig. 18.3c). To create a point contact by this method, the electrode should be appropriately prepared. Usually, the sample of the investigated metal or alloy is prepared in the form of a wire of small diameter. Then a notch is made in it. It is the narrow part of the notch where the contact with a controllable size (down to a single atom) is created by stretching the electrode. The notch should meet some essential requirements. It should be small enough, but not to much in order to preserve its mechanical strength. The mechanical notching causes plastic deformation of the material of the wire. The defects which thus appear should be eliminated by annealing. This operation is performed in a vacuum or a noble gas with the sample heated up to the temperature about half of its melting point. The process of sample annealing lasts for a few hours. After it, wires with the notches are purified by means of the chemical processing in the appropriate solution. The purified samples are attached to the substrate by a special glue. The latter operation has certain peculiarities and is very important. The quality of the attachment of the wire to the substrate and the precise actions of the researcher determine the result of the further experiment. After the glue solidifies, the sample is put into a special gear, which permits a smooth breaking of the wire by means of bending the substrate in the notch area. The wire diameter at the notch is gradually decreased until the necessary value is achieved. The process is interrupted when the necessary electrical resistance of the point-contact is obtained. The change in the substrate curvature value leads to reversible changes in the point-contact diameter and resistance. Among the most promising point contacts for creating quantum sensitive elements are dendrite point contacts (Fig. 18.3d). They are formed between two electrodes in an electrolyte solution with current flowing through the electrochemical system until direct electron conductivity is obtained [11, 33]. The crucial difference between dendrite point contacts and the other types of point contacts is that as the contact is being formed there is no mechanical influence of the researcher on the movement of the electrodes. The researcher only sets the parameters of dendrite growth and waits for a contact with a direct electron conductivity to appear. The process can be stopped at any moment once a contact with the desirable size and parameters is obtained. This allows production of atom-resolved dendrite contacts [33]. Dendrite contacts are characterized by a perfect crystalline structure formed during their growth as well as by quantum properties. In the process of formation of a dendrite point contact in a liquid medium a qualitatively new physical object emerges on the basis of the conductivity channel of a point contact immersed in liquid [33]. This is a new type of electrochemical electrode system – a gapless electrochemical electrode system. As we have already mentioned, such point

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contacts possess unique fundamental properties and provide rich opportunities for various applications, since the original characteristics of the nanoscale conductivity channel of a point contact, revealed by the Yanson point-contact spectroscopy, are combined with the oppositely directed processes of electrochemical activity at the contact ends, which comply with the laws of physical chemistry and have been studied thoroughly on bulk objects. The gapless electrochemical electrode system based on dendrite point contact can operate at superhigh current densities and a significant voltage drop over short nanometer distances [11] which are not accessible for any of the known modern electrochemical cells [48]. This generates new possibilities of acquiring new fundamental knowledge and developing advanced innovative applications. Among the new fundamental effects already discovered with the help of point-contact nanostructured gapless electrochemical electrode system, we would like to mention these: (i) first observation and measurement of the decomposition voltage of the electrochemical electrode system, which determines the onset energy of electrochemical reaction [56] and (ii) discovery of a new cyclic electrochemical effect [33], which displays the quantum nature of dendrite point contacts. These original fundamental properties of dendrite point contacts open the door for developing novel sensor technologies which have no analogue for the time being.

18.4

New Methods in Sensor Research and Development Based on Point-Contact Sensors

Point-contact sensitive elements are a new type of modern transducers. It should be noted that the basic properties of point contacts discovered in the Yanson pointcontact spectroscopy [20, 29] determine the differences between conventional sensors and nanosensors and point contact sensitive elements, which are able to work as a spectroscopic and quantum sensory tool [11]. The superior performance of pointcontact sensors provides many possibilities to develop new sensitive devices for analysis of gases, liquids and complex gas mixtures based on new original approaches in point-contact sensorics. Here we demonstrate two examples of innovative approach in sensor engineering which had been unknown for conductive sensors prior to discovery of the point-contact gas-sensitive effect.

18.4.1 Point-Contact Sensor Spectral Analysis of Complex Gas Mixtures The unique possibilities provided by the nature of Yanson point contacts allow direct formation and control of electrical properties of surface atoms. This has lead to the discovery of an original effect manifested by point-contact sensors in a complex

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R, kΩ

1,0 0,9 0,8 0,7 0,6

PHC Au-SWNT R0=754.3 Ω

0,5

breath gas 0,4 0,3 0

100

200

300

400

500

t, sec Fig. 18.4 Complex response of Au/SWNT point heterocontact to the action of human breath gas. Arrow marks the onset of the gas action. Vertical dashed and dotted lines show the duration of exposure

gaseous medium. For example, under the action of multicomponent mixture of human breath gas Au/SWNT point heterocontacts generate a complex spectrumlike response (Fig. 18.4). As a result of the influence of this gaseous medium the temporal dependence of electric conductivity of point heterocontacts has the form of a point-contact spectrum obtained in the Yanson point-contact spectroscopy. The response curve is characterized by several maxima and minima which arise during the relaxation period, that is after the breath gas stops acting on the point heterocontact. This behaviour can be caused by selective desorption of the components of the gaseous medium occurring during the relaxation of the point-contacts transducer. The complex response curve of point contact sensors upon the action of human breath gas looks like an original variety of point contact gas spectrum. The complex nature of response curves of point homocontacts was first observed in Ref. [57]. The obtained results made it possible to develop a new efficient approach to analyzing complex molecular systems using point-contact sensor devices which has no analogue [11, 24]. It is based on employment of the spectral principles of analysis, which allow operating with integral characteristics of the system and do not require identification of single components of the studied medium. What does a spectroscopic approach mean? To explain this it should be noted that point contacts are nanostructure objects that demonstrate quantum behaviour in their physicalchemical properties [32, 33]. It is these peculiarities of point contacts which are

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used for analysis of response curves of point-contact sensors. Indeed, the quantum physical system can be characterized by a set of energy states that correspond to local minima in the total energy of the system and characterize the ground state with the highest stability. Possessing a relevant tool, one can record this set of energy states and obtain basic information about parameters and properties of the system. One of the original peculiarities of the point contacts regarding their electric conductivity is the effect of conductivity quantization, which makes this nanostructure a relevant and efficient instrument to investigate quantum effects and their applications [33, 58, 59]. Let us consider an example from the Yanson point-contact spectroscopy of solids [20]. In bulk materials, physical states and properties of atoms can be described using vibration spectra. One of the basic characteristics recorded in the experiments is the density of phonon states. Phonons are quasiparticles which are used for description of vibration states of atoms in quantum mechanics. The Yanson point-contact spectroscopy allows direct determination of the density of phonon states, i.e. energy distribution of phonons in a solid state material. Thus, registration of the point-contact spectrum provides some basic information about the energy states of the components of the physical system. Breath gas is a highly complex system [60] with a large amount of equilibrium and nonequilibrium dynamic interactions among the constituents. The components of such a rich gas mixture form in that way a certain breath profile, reflecting specific organism dysfunctions and metabolic disturbances. The analysis of breath can be performed through its profile containing information about the adsorption energies of the components of the gas mixture which can be considered to be in quasiequilibrium state at the moment of measurement. Due to the quantum nature of their electric properties, point contacts are able to record fine variations of superficial states of the point contact conductivity channel which are caused by adsorption of an external agent. The registration procedure is performed with the highest possible resolution of one conductivity quantum which is equal to addition of one atom to the point-contact channel [33]. This makes it possible to record spectrum-like response signals of point-contact sensors. This original property of point contacts can be easily explained using some basic physical principles of the Yanson point-contact spectroscopy [20]. Responses of point-contact sensors to the action of breath gas of different patients are quite distinctive because of the variation in composition and physicochemical state of the gas mixture under analysis [24]. At the same time, it should be noted that for a specific person the results are reproducible over a short period of time which is sufficient for 3–5 cycles of measurement. The point-contact spectrum of breath profile provides the possibility for directly analyzing this gas mixture without determining its specific constituents. The spectroscopic approach offers a wide choice for the development of an unlimited spectrum of novel methods of noninvasive diagnostics because the knowledge of energetic parameters of any physical system is a key factor for determination and prediction of its properties. Relaxation time describes an integrated energy value of the adsorbed ingredients of the exhaled gas of the patient and is an important parameter for analysis of the metabolic profile.

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The effectiveness of the point-contact spectroscopic concept of sensor analysis through complex gas mixture profile registration has successfully been demonstrated by the first evidence for detection of the virulent strains of Helicobacter pylori infection in the real-time mode [24]. As it is shown in the Yanson point-contact spectroscopy [20, 29], the energy range covered by the point-contact spectrum characterizes the physical state of the material and determines a number of its key physical quantities, for example, the Debye temperature [61]. Energy parameters of point-contact spectra allow distinguishing materials one from another. In the case of breath gas investigated by point contact sensors, relaxation time as an integrated energy value of the adsorbed ingredients of the exhaled gas of the patient determines the length of the point-contact spectrum of breath profile. Due to its energy origin, relaxation time is a parameter which corresponds to a certain breath profile of the patient. As different strains of H. pylori have various biochemical properties, and therefore, volatile products of their vital activity emitted to the breath gas also vary, point-contact sensors are able to distinguish them through point-contact breath spectra and relaxation times in the framework of the spectroscopic approach to breath analysis. World Health Organization recognizes Helicobacter pylori infection as the primary causing factor in the development of peptic ulcer disease, gastric cancer, and gastric mucosa-associated lymphoid tissue (MALT) lymphoma [62, 63]. It is the toxigenic strains of Helicobacter pylori which are responsible for the appearance of the above diseases; while non-toxigenic strains can cause a disease in a very limited amount of cases [64, 65]. This means that the real-time detection of the virulent strains of Helicobacter pylori by point-contact sensors can be a basis for designing a breakthrough screening technology that will be able to significantly decrease the prevalence of Helicobacter pylori and the associated diseases all over the world. The above example demonstrates the broad prospects for applying the point-contact spectroscopy concept to the analysis of complex molecular systems and for developing point-contact sensory devices for security purposes.

18.4.2 Selective Analysis of Gaseous and Liquid Media Through Conductance Registration in Dynamic Regime The method of selective sensor analysis of gaseous and liquid media is based on quantum properties of Yanson point contracts and their ability to undergo fundamental transformations in electrochemical solutions. It is based on the characterization of the energy of interaction of point-contact structures with gas and liquid media through quantum conductivity parameters of point contacts. When the point contact conductivity channel is immersed into electrolyte (Fig. 18.3d), a qualitatively new physical object appears, the so-called gapless electrochemical electrode system [45]. It differs fundamentally [41, 45] from the existing electrochemical systems.

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The gapless electrochemical electrode system manifests itself with both point contact properties [20, 29] and electrochemical element characteristics [47]. Thus, the specific surface properties of the gapless electrochemical electrode system are accompanied by the original characteristics of the point-contact conductivity channel. The ability of Yanson point contact to concentrate electric field and to keep its identity under a super high current density is combined with an opposite directed electrochemical activity located at the ends of the point-contact conductivity channel. The electric field concentration [28] and a monotonous change of the potential along the point contact channel [47] create conditions when the reductive processes can proceed on the side of the negative pole of the electric energy source and the oxidative ones can go on the side of the positive pole. To realize these processes it is necessary that the potential difference across the point contact channel is higher than the decomposition voltage of the electrode system which in this case consists of electrodes arising at the opposite ends of the point contact conductivity channel [41]. The nature of the point-contact based gapless electrochemical electrode system allows observing the cyclic switchover effect [33]. It consists in a spontaneous formation of a dendrite point contacts in the electric field. When current flows through the needle-electrolyte-anvil system, dendrites start growing in the electrode-active areas of the needle surface with the highest density of electric field lines. If current continues to flow, a cyclic process develops in the system after some hundred milliseconds to several minutes: the point contact resistance varies with time when going through the stages of growth, reduction, and stabilization. The stages are repeated many times, accounting for the cyclic changes in the physical and chemical properties of the object. The cyclic changes recurrence is automatic with no external influence. The variations of the interelectrode voltage during self oscillations of the resistance show up as clearly visible steps in the dependence R(t). It was shown [33, 41] that the dendrite growth has a quantized nature governed by the quantum shell effect [58, 66]. The point contact response signal upon the action of the analyzed gas is caused by the influence of the absorbed molecules perturbing the electrical transport properties of the conductivity channel. Electrochemical processes on the surface of the gapless electrochemical electrode system may proceed simultaneously with the adsorption phenomena. This allows proposing a new selective approach in the field of sensor technology [49] which exploits the principle of quantum analysis of gaseous and liquid media in dynamic regime, and have no analogues among the existing sensor devices. The characteristic feature of a point contact is that it is a nanostructure whose quantum electronic state can be controlled very precisely through its resistance properties [33, 41]. The probability distribution of dendrite nanostructures with specific resistance range and cross-sections during point contact synthesis depends essentially on the electrolyte composition [33]. The last condition opens up wide prospects for the design of high performance nanostructured quantum point contact sensitive elements. A pointcontact size is close to that of the molecules of gaseous media and it can be produced in an easy high-technology process. These factors are the main prerequisites for a successful development of the new innovative tools of defence against CBRNE

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agents that can be useful in addressing counter-terrorism and environmental security issues. One can easily understand this selectivity process considering the quantum nature of the shell effect which is clearly demonstrated in conductivity histograms [33]. Each metastable state of a dendrite point contact can be attributed to electron conductance quantization and electronic shell effect and is characterized by a certain energy which can be evidenced by the conductivity (resistance) dependence on time. In fact, the shell effect is due to energy distribution of particles in a quantum system. A quantum physical system can be characterized by a set of energy states that correspond to a local minimum in the total energy of the system. For example, quantized particles in a quantum system have energies that group into bunches of degenerate or close-lying levels, called shells [67]. The case of a shell with a definite set of completely filled energy states corresponds to a local minimum in the total energy of the system and characterizes the ground state with highest stability. Possessing a relevant tool one can record this set of energy states and obtain basic information about parameters and properties of the system. One of the original peculiarities of the point contacts in their electric conductivity is the conductivity quantization. Cross-sectional diameters of metallic channels of point contacts have direct correlation with their electrical transport properties [33, 58, 68]. The conductance G variations in a dendrite point-contact structure account for the states of enhanced stability corresponding to certain point contact diameters [33]. The plateaus in the stepped dependence G(t) (t stands for time) correspond to the metastable states of the contact. Each stable state changes to another by jumps of resistance (conductance), which produce stepped regions in the curve indicating a quantization effect. The minima and the maxima in the conductance of a growing dendrite point contact are reproduced in many cycles of the self-oscillatory process. The staircase shape of the curve and the cyclic character of the process allow determining the point contact dimension easily through conductance measurement [33]. As a result, such a nanostructure is a relevant and efficient instrument for selective detection of external agents through conductance registration in dynamic regime. As an example, the histograms for several gas agents are illustrated in Fig. 18.5. The positions of the conductance maxima in the histograms, which correspond to the most probable metastable states, relate to specific cross sections of dendrite point contacts grown in the self-oscillatory process. The histogram maximum corresponds to the most probable point contact under the conditions of the experiment. As one can see from the data presented in Fig. 18.5, histograms obtained for dendrite point contacts synthesized in different gas media are fundamentally distinctive. It means that the presented method is absolutely selective and gases under investigations can be reliably determined using such a point-contact quantum detector. Moreover, quantum point-contact sensor is able to differentiate even among noble gases. The extremely high sensitivity of the method and the quantum detector’s high resolution are determined by the ability to easily record a change in electric conductivity of a point contact down to one conductance quantum. For instance, interaction of an atom-sized contact with only one molecule of gas results in a resistivity change as high as at least 12.9/n kΩ, n being the number of atoms in the contact. Such a value is

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Fig. 18.5 Conductance histograms of dendrite copper point contacts grown in the drop of bi-distilled water under the gas action. (a) Dendrite point contacts in argon medium. (b) Dendrite point contacts in argon (80%) + CO2 (20%) medium. (c) Dendrite point contacts in ambient air. G – conductance, G0 – conductance quantum, n – number of counts

easily registered by the most ordinary measuring instruments. As a result, the quantum point-contact sensor response to the gas medium exposure is always stronger than that of any other homogeneous equally small nanosensor because the latter cannot operate in the quantum registration mode under super high current density. This means that less complicated and cheaper equipment is needed to register the response signal of a quantum point contact. The larger transducers are a priori far less sensitive than the quantum point-contact sensors. Thus, gas molecules diffusing into the electrocrystallization area affect the form and behaviour of the conductance histograms obtained from the stepped conductivity dependences R(t) of the dendrite point-contact system formed cyclically in the controlled gas medium. The high sensitivity of quantized electrical conductivity to the condition of the interphase boundary makes it possible for the growing dendrite point contacts to detect gases diffusing into electrolyte. Prototypes for quantum differential detectors of gas and liquid media can therefore operate efficiently on this principle. Variation of materials for dendrite point-contact creation through the cyclic switchover effect offers unlimited possibilities for design of analyzers with a wide range of operation.

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Prospects for Application of Point-Contact Sensors for Security, Environment and Health Issues

The advanced results on manufacture of nanoobjects with a given atom-sized ability using quantum properties of dendrite point contacts [33] and employment of the point-contact sensors for development of innovative noninvasive methods of medical diagnostics [24] have laid the solid background for the development of principally new technologies and devices for real-time detection of CBRN and explosive agents. In addition to the quantum mechanism for analyzing liquid and gaseous media discussed above, the quantum shell effect, which controls the process of synthesis of a dendrite point contact, gives a new possibility of increasing the list of substances which are detectable by quantum point-contact sensors. It is known that the shell effect reveals itself in quantum fermionic systems [58, 66, 67]. One of its manifestations is the increased stability of certain isotopes. The shell effect consists of electronic and atomic effects directly observed in dendrite point contacts (see Fig. 7 in [33]). This makes a dendrite point contact an ultrafine instrument for controlling the investigated substances. The almost complete selectivity of the method for quantum detection of liquid and gaseous media means there are no visible obstacles to identifying isotopes with quantum point-contact detectors thus completing the search for efficient tools against all CBRN and explosive agents. This idea will no doubt be realized in the near future, since even a minor variation in the electronic structure and isotope mass will lead to a change in the shell effect parameters which can easily be detected. Point contact as the basic structure element of a gas-sensitive matrix is characterized by an unprecedented high sensitivity to alien ingredients of the ambient air [24]. This is determined by its nature. The diameter of the conductivity channel of a point contact is comparable with that of atoms of the contact’s electrode material. This results in the ability of a single molecule added to the analyzed media to cause a specific shift of electron density of the point-contact conductivity channel whatever the nature of the interaction forces. The shift, in turn, is accompanied by a sharp and significant change in point contact’s electric resistance. It was shown earlier that point contacts are highly sensitive to a number of substances, including popular markers of explosives such as various nitrogen compounds (nitrogen oxides, ammonia) (see, for example, Ref. [40, 44]. This indicates that the point-contact structure can be used to detect quite a number of instruments of terrorist attacks (trotyl, dynamite, RDX). However the concept of detecting specific markers can hardly be called efficient, especially in the context of the ever-growing panoply of substances used by terrorists. A more promising approach would be to use the concept of finding gas media profile corresponding to risk factors’ conditions. A point-contact gas-sensitive matrix [69] is composed of a few hundreds of conductivity channels of various lengths and diameters. It displays a specific multiparameter response to the action of minute quantities of any gaseous analyte [24, 57]. This response can be considered as the background concentration and

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energy profile of the monitored medium. By connecting the device to an artificial neural network it is possible to organize a programmed learning process and perform a permanent registration of the background gas profile followed by selective identification of trace quantities of the unknown target product [70]. Appearance in the complex gas medium registered as the background of a new alien component deforms noticeably its concentration and energy profile. This will allow one to mark the multiparameter response of the point-contact sensor as a risk profile and take prompt action. A quantum point-contact sensor device has an ultrahigh resolution and is able to register on a molecular level the complex interactions in multicomponent gas and liquid media [11]. This allows one to successfully use it for solving a number of global ecological and social problems that threaten the survival of mankind. One of them is the problem of climate change which can lead to worsening of the food situation in the world and incite armed conflicts aimed at redistribution of resources. To avert this, an efficient control of the earth’s climate needs to be organized. A successful control and prediction of climate change is only possible under the condition of quick and continuous detection of greenhouse gases concentration in the atmosphere. The quantum selective point-contact detector of gas and liquid media is a portable device which is able to be a basic element of a simple and inexpensive technology for controlling the above problems. The results already obtained suggest good prospects for the proposed method of high-precision detection of carbon dioxide (see Fig. 18.5). There exist all necessary preconditions for the creation of highly efficient quantum point-contact detectors of methane, nitrogen oxide, aqueous vapour and any other gas important for the control over climate change [49]. It should be noted that the quantum detector under consideration provides a complex analysis of not only main greenhouse gases, but also their precursors. This results in a higher reliability and credibility of the registered trends and a significantly enhanced predictive capability of the monitoring. The simplicity of construction of the point-contact sensor device and its low cost will allow a global multi-position impact monitoring of the environment to quickly detect areas of chemical pollution in potentially dangerous regions of intense anthropogenic influence. The high reliability and sensitivity of detection are guaranteed by a continuous quantitative and qualitative control of the atmosphere condition. A selective analysis of the gas mixture exhaled by a human provides solution for many social problems connected with uncontrollable spread of infections, poor diagnosis of dangerous diseases and various kinds of terrorist threats. In the recent years, the importance of these problems has increased with growing flows of migrants. Point-contact quantum sensors can become the basis for development of innovative technologies aimed at averting global threats which arise from spread of infections across the world. For example, the recently obtained state-of-the-art results [24] have already become a prerequisite for the development of an advanced low-cost breakthrough technology for detecting Helicobacter pylori and its carcinogenic strains. The importance of this work comes from the fact that Helicobacter pylori is the most widespread infection in the world. The infection rate of human

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population amounts to 100% in many developing countries. Such rates can lead to a global spread of the infection as a result of mass migration from developing countries caused by armed conflicts, poverty, unemployment and other social problems. Taking into account that the carcinogenic strains of Helicobacter pylori cause many dangerous diseases, the spread of the infection can lead to an uncontrollable growth of such diseases as peptic ulcer disease, gastric cancer, and gastric MALT lymphoma. This may become a very dangerous global process, since stomach cancer, for example, is already ranked second in the top lethal cancer diseases after lung cancer. The high danger of Helicobacter pylori is also due to the fact that the diseases mentioned above, as well as some others related to its persistence, arise a long time (up to 20 years) after the infection. Therefore, a logical solution to the global problems caused by this bacterium is to promptly detect and eradicate it. This needs efficient and low-cost noninvasive screening tests to be done, which allow one to quickly and reliably diagnose the carcinogenic strains of Helicobacter pylori in the real-time mode [24]. Presently, none of the existing methods for detecting Helicobacter pylori can pretend to be used as a screening method because of the rather high cost of the examination. Moreover, none of the known tests is able to detect the carcinogenic strains of the bacteria in the real-time mode. At the moment tests used for the detection of the virulence factors are complex, timeconsuming, and costly; the procedure is mostly invasive and requires biopsy sampling with the further growth of pure cultures in bacteriological laboratory, and, finally, genome analysis. Therefore this multistep diagnostic process currently is used mainly for scientific purposes, not in practical healthcare. Thanks to the unique properties of point-contact sensors [11] and an innovative method of noninvasive detection of carcinogenic strains of Helicobacter pylori in the real-time mode [24] there is the possibility of developing real-time breath tests to detect cytotoxic strains of Helicobacter pylori infection. The point-contact sensor based real-time breath test will become the core of a screening technology which, thanks to its simplicity and low cost, will be affordable and thus suitable for screening examination of wide sections of population even in countries of low socio-economic development. This will provide solution to the problem of spread of Helicobacter pylori and avert the elevated occurrence of diseases caused by the bacteria.

18.6

Conclusions

We discussed the most recent results and advancements in point-contact nanosensors. To understand the general distinctions in properties of point-contact sensors and their sensor analogues the fundamentals of Yanson point contacts that determine their spectroscopic and sensor behaviour were considered. A special attention was paid to the basic properties of these nanoobjects which are responsible for their ability to demonstrate the point-contact gas-sensitive effect and excellent sensor performance. Classification of point contacts into homo- and heterocontacts

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and peculiarities of their electric characteristics were described. This view demonstrated the advantages of point heterocontact sensors. In particular, when developing heterocontact-based sensors, one can select a pair of electrodes in which one of them ensures a favourable regime of current flow with large electron mean free paths while the other is responsible for the sensor performance. The technological principles of Yanson point-contact spectroscopy used for designing various types of point-contact sensors were discussed. They allow creating a wide range of nanostructured tools exploiting point contacts based on bulk materials using simple and reliable equipment. The innovative approaches in sensor engineering which are evident from the peculiar properties of point-contact sensors were presented. They were unknown for conductive sensors before the discovery of the point-contact gas-sensitive effect. Among the new areas in sensorics one should note the point-contact method for sensor spectral analysis of complex gas mixtures which does not require detection of separate components, and selective analysis of gaseous and liquid media through conductance registration in dynamic regime. The methods and technology proposed are based on characterization of the energy of interaction of point-contact structures with gas and liquid media through quantum conductivity parameters of point contacts. Due to the quantum nature of their electric properties point contacts are able to record tiny variations of superficial states of the point contact conductivity channel caused by adsorption of an external agent. The registration procedure is performed with the highest possible resolution of one conductivity quantum which is equal to addition of one atom to the point-contact channel. The quantum approach gives a wide choice for development of an unlimited spectrum of novel methods and devices because knowledge of the energy parameters of any physical system is a key factor for determination and prognosis of its properties. Energy parameters of pointcontact sensor response allow distinguishing materials one from another or analyzing complex gas mixture through its profile without determination of separate components of the gas medium. Finally, prospects for application of point-contact sensors for security, environment and health issues were discussed. Point-contact quantum detectors can become a basic element of a simple and inexpensive technology for successful control of CBRN and explosive agents, defence against terrorism, and prediction of climate change and environmental monitoring as well as a global multi-position impact monitoring of the environment to quickly detect areas of chemical pollution in potentially dangerous regions of intense anthropogenic influence.

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50. Shekhter RI, Kulik IO (1983) Phonon spectroscopy in heterocontacts. Sov J Low Temp Phys 9:22 51. Baranger HU, MacDonald AH, Leavens CR (1985) Heterocontact effects in point-contact electron-phonon spectroscopy of the alkali metals. Phys Rev B 31:6197 52. Bobrov NL, Rybal’chenko LF, Khotkevich AV, Chubov PN, Yanson IK (1991) Patent No. 1631626 (USSR) Device for creation of a cooled point contact between metal electrodes. Published in B. I. vol 8, p 168 53. Fisun VV, Khotkevich AV, Morlok SV, Konopatskyi BL, Alexandrov YL, Kamarchuk GV (2008) New method of making point contacts. Low Temp Phys 34:161 54. Chubov PN, Yanson IK, Akimenko AI (1982) Electron-phonon interaction in aluminum point contacts. Fizika Nizkikh Temp 8:64 55. Muller CJ, van Ruitenbeek JM, de Jongh LJ (1992) Experimental observation of the transition from weak link to tunnel junction. Physica C 191:485 56. Kamarchuk GV, Pospelov AP, Savitskiy AV, Koval LV (2014) Nonlinear cyclical transport phenomena in copper point contacts. Low Temp Phys 40:937 57. Kushch IG, Korenev NM, Kamarchuk LV, Pospelov AP, Alexandrov YL, Kamarchuk GV (2011) Chapter 7: sensors for breath analysis: an advance approach to express diagnostics and monitoring of human diseases. In: Khajibaev A, Mikhalovsky S (eds) Biodefence. NATO science for peace and security series a: chemistry and biology. Springer, Amsterdam, pp 63–75 58. Yanson AI, Yanson IK, van Ruitenbeek JM (1999) Observation of shell structure in sodium nanowires. Nature 400:144 59. Mares AI, van Ruitenbeek JM (2005) Observation of shell effects in nanowires for the noble metals Cu, Ag and Au. Phys Rev B 72:205402 60. de Lacy Costello B, Amann A, Al-Kateb H, Flynn C, Filipiak W, Khalid T, Osborne D, Ratcliffe NM (2014) A review of the volatiles from the healthy human body. J Breath Res 8:014001 61. Kamarchuk GV, Khotkevich AV, Bagatsky VM, Ivanov VG, Molinié P, Leblanc A, Faulques EC (2001) Direct determination of Debye temperature and electron-phonon interaction in 1T-VSe2. Phys Rev B 63:073107 62. Malfertheiner P, Megraud F, O’Morain CA, Atherton J, Axon AT, Bazzoli F, Gensini GF, Gisbert JP, Graham DY, Rokkas T, El-Omar EM, Kuipers EJ (2012) Management of Helicobacter pylori infection – the Maastricht IV/ florence consensus report. Gut 61(5):646–664 63. IARC Working Group Experts (2014) Helicobacter pylori eradication as a strategy for preventing gastric cancer. International Agency for Research on Cancer. IARC Working Group reports, no. 8. Lyon, 181 pp. Available at: http://www.iarc.fr/en/publications/ pdfsonline/wrk/wrk8/index.php 64. Blaser MJ (1997) Not all Helicobacter pylori strains are created equal: should all be eliminated? Lancet 349:1020 65. Wroblewski LE, Peek RM Jr, Wilson KT (2010) Helicobacter pylori and gastric cancer: factors that modulate disease risk. Clin Microbiol Rev 23:713 66. Yanson AI, Yanson IK, van Ruitenbeek JM (2000) Supershell structure in alkali metal nanowires. Phys Rev Lett 84:5832 67. Martin TP (1996) Shells of atoms. Phys Rep 273:199 68. Obermair C, Kuhn H, Schimmel T (2011) Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires. Beilstein J Nanotechnol 2:740 69. Golovko SA, Gudimenko VA, Klimkin AS, Pletnev AM, Vakula VL, Zaika AS, Kamarchuk LV, Kushch IG, Pospelov AP, Kravchenko AV, Kamarchuk GV (2016) Development of criteria for analysis of point-contact sensor characteristics in complex gas media. Univ J Mater Sci 4:32 70. Ved MV, Sakhnenko MD, Shtefan VV, Lyon SB, Oleinyk SV, Bilyi LM (2008) Computer modeling of the nonchromate treatment of aluminum alloys by neural networks. Mater Sci 44:216

Chapter 19

New Method of Optical Spectroscopy for Environmental Protection and Safety Surik Khudaverdyan, Ashok Vaseashta, Mane Khachatryan, Mihail Lapkis, and Sergey Rudenko

Abstract The photoelectronic processes in p+ -n-p+ structures are studied for this investigation. The regularities of the width change of the adjacent barriers subject to the external voltage and the concentration of impurities in the base are revealed. The relations between these changes and the selective photo-sensitivity of the structure are shown. The possibilities of the effective registration of individual wavelengths from the integral radiation flux and the possibilities of the determination of the intensity and the length of these waves are analyzed. The necessity to develop a structure which will be used for the creation of a cheap, fast-acting system of optical analysis fit for use in the field is shown. The capabilities of the spectral selective sensitivity of the investigated photodetector structures are studied via obtaining the spectra of three LEDs (blue, green and red). The problems encountered are revealed and the solutions are suggested. The comparative analysis of the selective sensitivity and of the complexity of the production technology of the investigated photodetectors and that of the existing multilayer semiconductor photodetectors with active cascade-like layers is carried out. The possibility to carry out the optical spectral analysis by the investigated structures without the use of high-accuracy mechanical devices, light filters, prisms and diffraction gratings, and the possibility to apply the investigated photodetectors for the creation of multi-purpose spectrophotometers

S. Khudaverdyan (*) National Polytechnic University of Armenia, Yerevan, Armenia A. Vaseashta International Clean Water Institute, Manassas, VA, USA NJCU – A State University of New Jersey, Jersey City, NJ, USA D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova M. Khachatryan National Polytechnic University of Armenia, Yerevan, Armenia RD Alfa Microelectronics, Riga, Latvia M. Lapkis · S. Rudenko RD Alfa Microelectronics, Riga, Latvia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_19

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and monitoring systems which will be used for obtaining the information on the investigated medium and for solving the important security problems via conducting identification processes are studied. Keywords Distribution spectrum · Environmental security · Optical spectroscopy · Spectral analysis

19.1

Introduction

Over the last decade, the demand for sensors which enable the remote analysis of the conditions of the environment has considerably increased. The sensors help to obtain the information on the composition of the environment under study and to solve the important identification issues from the security point [1–3]. The optical analyzers used for the research nowadays require light filters, prisms, diffraction gratings, and high-accuracy mechanical devices [4–6]. It increases the cost of research and reduces the reliability and the speed. The need to substitute these analyzers led the researchers to the development of semiconductor structures with new functional features. There is research done in the sphere of multicolored photoreceivers [7–15] which are based on multi-layered structures or a series of active cascade-like layers with different base widths. The different penetration depths of separate waves ensure different degrees of photoconductivity. The mathematical treatment of the measurement results gives information on the spectral distribution of the intensity. However, for high-accuracy registration, these structures require the identity of the absorption conditions and the creation of nano-accurate multi-layer structures. The sophisticated production technology and the absence of the possibility to control the spectral sensitivity by external voltage make it difficult to create and to use such structures. Thus, the creation of a semiconductor spectral analyzer that eliminates the above stated deficiencies becomes an urgent task. The analyzers will be used for the remote analysis where low-cost, fast-acting devices with high spectral sensitivity are required. The analyzers will be fit for use in the field.

19.2

Object Under Study

The p+(PtSi)
n(Si)
p+(Si) silicon structure (Fig. 19.1) is studied. The structure can be made in the technological cycle of the production of the integrated circuit. The n-base is occupied by the depleted layers of the oppositely-directed barriers (Fig. 19.1). The point of contact xm of the depleted layers is created in the energy band diagram of the structure. Here, the potential energy of the electron has minimum value. It depends on the polarity of the external voltage and moves towards the surface of the light absorption, when the near-surface contact is forward-biased and the rear contact is reverse-biased (Fig. 19.1).

Idiff.

Idiff.

Diffusion of electrons

hυ

Idr2

n

Idr1

p+

ϕ2

ϕ1 Area of the

ϕp-n

driftage

ϕSil

Diffusion of electrons

p+

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Ohmic contacts

New Method of Optical Spectroscopy for Environmental Protection and Safety Ohmic contacts

19

SiO2

EF2

EF1 ΔF 0

xm

d

x

Fig. 19.1 p+
n
p+ structure and directions of currents

The environments the most efficient for radiation absorption are the depleted layers. In the conditions of the reverse-biased rear barrier, the photocurrent is conditioned mainly by that barrier. The waves have different penetration depths, depending on their length and intensity. The shift of xm towards the surface (towards “0” in Fig. 19.1) expands the depleted layer of the rear barrier and increases the number of the absorbed waves in it. The high-conductivity thin layer of the left surface p+ and the incident voltage, on him, can be ignored. It will make it possible to take the point “0” as the surface, and to calculate the photocurrent which will contain the information on the intensity and the length of the absorbed waves. It can be obtained by means of an appropriate algorithm for which the mathematical expression connecting xm, voltage V, absorption coefficient α and wave intensity F0(λ) is used [16]. X I Ph i, j

i,j

¼ Sq

X i, j

  e
αi d F 0 ðλi Þ 1
2eαi xmj þ 1 þ αi w

ð19:1Þ

where (i ¼ 1,2,3,. . .) changes with the change of the radiation wavelength in the integral flux, (j ¼ 1,2,3,. . .) changes with the change of bias voltage, F0(λi) is the total flux of the photons of the incident wave with the length λi and w is the width of the range of the diffusion current generation. Taking that the base is occupied by the depleted layers of the barriers (Fig. 19.1), the potential distribution of xm in it is determined by the field potential V and the density of the space charges Nd creating that field [16], xm ¼

d ε0 εðΔφ þ qV Þ
, 2 q2 N d d

ð19:2Þ

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Fig. 19.2 The dependence of the distance between the bottom of the conductivity band and the Fermi level on the impurity density

0.33

∆F, eV

0.32

0.31 0.3 0.29

0.28 0.27 0.26

Nd, cm-3

0.25 0

2E+14

4E+14

6E+14

8E+14

1E+15

ϕSil, eV 0.58 0.57 0.56 0.55 0.54 0.53 0.52

Nd, cm-3

0.51 0

2E+14

4E+14

6E+14

8E+14

1E+15

Fig. 19.3 The dependence of the potential energy level created by PtSi on the impurity density

where Δφ ¼ φ2
φ1, Nd is the donor density, ε is the dielectric permittivity of the substance, ε0 is the dielectric permittivity of vacuum, q is the electron charge, d is the base width. With the help of (19.1) and (19.2), as well as ΔF ¼ kT ln Nc/nn [17], the dependences xm(V ), xm(Nd), φp
n(Nd), φsil(Nd), d(Nd), ΔF(Nd) were studied (Figs. 19.2, 19.3, 19.4, 19.5, 19.6, 19.7, and 19.8), and the structural parameters of the contact of the potential barriers in the point xm were determined. When the impurity density is increased, the decrease in the distance between the Fermi level and the bottom of the conductivity band takes place faster at the lower densities than at the higher densities (Fig. 19.2). The height of the silicide barrier created by n
Si and Pt (Fig. 19.1) φ1 ¼ 0.84 eV [17]. The difference between that height and ΔF will give the dependence of the potential energy level on the impurity density, based on different impurity densities in the base (Fig. 19.3).

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0.7

275

ϕp-n, eV

0.69 0.68 0.67 0.66

0.65 0.64

Nd, cm-3

0.63 0

2E+14

4E+14

6E+14

8E+14

1E+15

Fig. 19.4 The dependence of the potential energy level of the p-n junction on the impurity density

Fig. 19.5 The dependence of the base width on the impurity density

d, eV

0.0006 0.0005 0.0004 0.0003 0.0002 0.0001

Nd, cm-3

0 0

2E+14

4E+14

6E+14

8E+14

1E+15

0.001 0.0008 0.0006 0.0004 0.0002 -5

-4 1E+14

-3 2E+14

-2

-1

0 0

5E+14

7E+14

1E+15

Fig. 19.6 The dependence of the minimum point of the potential energy of the electron in the base on the external voltage, at different impurity densities

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Fig. 19.7 The dependence of the minimum point of the potential energy of the electron in the base on the impurity density, at different external voltages

Fxd3,5

Fxm1,6

F, quantum/cm2.s 1.2E+14 1E+14 8E+13 6E+13 4E+13 2E+13 0 430

450

470

490 λ, nm

Fig. 19.8 The dependence of the residual intensity of the absorbed radiation in the point xm on the wavelength, when the base widths are 3.5 and 1.6 μk

φsil ¼ φ1
ΔF ¼ φ1
kTlnN c =nn

ð19:3Þ

The height of the potential barrier of the n
p junction is determined by the expression [17]. φp
n ¼

pp nn kT ln ¼ 0, 76 eV q ni

ð19:4Þ

and it grows according to the logarithmic law based on the impurity density in the base (Fig. 19.4). In (19.4), kT/q is the thermal potential and, at 300 K it is 0.026 V, nn

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277

is the electron density in the base, pp is the hole density in the rear p+ region, ni is the density of the free charges in the pure semiconductor. For Si at 300 K it makes 1, 6  1010 cm
3. The dependence of the height of the potential barrier of the n
p junction on the impurity density is shown in Fig. 19.4. The difference between Figs. 19.3 and 19.4 will give us the dependence of Δφ ¼ φ2
φ1 of the expression (19.2) on the impurity density. It is a constant value and is equal to 0.19 eV. Based on the conditions of the contact of the potential barriers in the base, and using the expression which determines the width of individual barriers,

dp
n

sffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2EE 0 φp
n , ¼ q2 N d

dPtSi

rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2EE 0 φSil ¼ q2 N d

ð19:5Þ

we will get the dependence of the base width (d ¼ dp
n + dPtSi) on the impurity density (Fig. 19.5). Thus, by choosing the height of the oppositely-directed potential barriers (Figs. 19.3 and 19.4), we can determine the base width as a technological parameter (Fig. 19.5). The algorithm of the selection of individual waves from the integral radiation flux supposes the absorption depth of the given wave of the order of xm [18]. Therefore, the change of xm, which depends on the external bias voltage (when the impurity density is constant, Fig. 19.6) and the impurity density in the base (when the voltage is constant, Fig. 19.7) is important. As seen from Figs. 19.6 and 19.7, at the negative values of the voltage, the surface potential barrier is reverse-biased, and xm increases with the negative increase of the voltage. The dependence in Fig. 19.6 is linear. The bigger slope and the more active change of the widths of the barriers (one at the expense of another) occur in the base at the relatively smaller values of the impurity densities. In the absence of the bias voltage, the lower the impurity density in the base, the bigger the widths of the oppositely-directed potential barriers and the base width making their sum. Figure 19.8 shows the dependence of the residual intensity of the absorbed radiation in the point xm on the wavelength, when the base widths are 3.5 and 1.6 μk. The spectral dependence of the solar radiation intensity was used [19]. As seen from the Figure, at the point xm, when the base width d ¼ 1.6 μk (Pic.1), the wavelengths up to 450 nm are almost completely absorbed (the residual intensity is low). At the bigger values of xm (e.g. when d ¼ 3.5 μk), the longer waves are also involved into the absorption range (Fig. 19.8). As follows from the above described radiation absorption regularities and the structural regularities of the photodetector, the bigger the xm, i.e. the wider the base, the closer the residual intensity wave that reached xm to single-valued. However, to obtain a wide base, it is necessary to carry out a long-term, high temperature deposition of the epitaxial layer. In the meantime, the self-diffusion may take

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place from the rear p+ layer, which will bring to the decrease of the sharpness of the potential barrier. It will decrease the accuracy of the selective sensitivity. Therefore, the shorter the epitaxial deposition, the higher the determination accuracy of the wavelengths and of their intensities. In that case, the base will be relatively narrow and the number of the residual intensity waves that reached xm may be more than one. Therefore, it is important to get wider bases by means of lowtemperature epitaxy. It is also important to obtain low temperature silicide. For that, the technological processes described in [20] were used to obtain the samples.

19.3

Experimental Results

In the test samples (Fig. 19.9), the impurity density in the base is taken as Nd ¼ 9.1014 cm
3, the p+ platform is doped with boron and has the impurity density of 1.1018 cm
3. The impurity are ionized at room temperature, and they determine the densities of the main charge carriers nn and pp in the corresponding ranges. The density of the silicon self-charges ni ¼ 1, 6.1010 cm
3, the density of states in the conductivity band is 2,8.1019 cm
3, the height of the PtSi silicide barrier created by Pt φ1 ¼ 0, 84 eV . The distance between the Fermi level and the bottom of the conductivity band in the base is ΔF ¼ 0, 27 eV . Thus, the height of the surface potential barrier by (19.3) φsil ¼ 0,84–0,27 ¼ 0,57 eV. The height of the potential barrier of the p-n junction by (19.4) φp
n ¼ 0, 76 eV. Thus, the difference between the oppositely-directed potential barriers is Δφ ¼ φp
n
φSil ¼ 0, 76
0, 57 ¼ 0, 19 eV. Fig. 19.9 Structure of the photodetector

Substrate KDB 0,01 (100) 1.1019cm-3 Epitaxial Layer KEF 5 (100) d=2 ± 0,2 μk, 9 .1014 cm-3 p+ Layer, Rs = 100-120 Om/# SiO2 Oxide Layer n+ Protective Layer p+ Protective Layer Pt-Si TiW Al

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Fig. 19.10 The experimental spectral dependences of LEDs: 1-LL-304BC4B-B4-IGD (InGaN), 2-L-53GC (GaP), 3-L-813SRC-J14 (AlGaInP)

Having the above stated data, the dielectric permittivities of silicon and of vacuum ε ¼ 12 and ε0 ¼ 8.86.10
14 F/cm, the impurity density in the base and the electron charge, and taking into account that the resistance of the base is much bigger than that of the edge layers, it can be admitted that the space charges of the barriers are located in the base and their widths can be determined by (19.5): d p
n ¼ 0, 917 μ k,

dPtSi ¼ 1 μ k

The base width of the structure d ¼ 2  0.2 μk (Figs. 19.2 and 19.9) and the total width of the potential barriers is 1.917 μk. Therefore, the base is almost completely occupied by the oppositely-directed barriers. The external voltage falls mainly onto the potential barriers in the base and the position of the point of their contact xm Fig. 19.1) can be controlled by external voltage. Figures 19.10 and 19.11 show the spectral dependences of the intensity of the photodetectors under study at the absorption of the radiation coming from the LEDs of the following brands: Figure 19.10 shows the reference and experimental spectral dependences of the intensities of the absorbed radiations in the investigated photodetectors. The radiation sources are LEDs of the following brands: L-813SRC-J14 (AlGaInP), 153GC (GaP), LL-304B-B4-GD (InGaN). The technical data of the peaks of the spectral curves are correspondingly on λmax ¼ 660 nm, λmax ¼ 565 nm and λmax ¼ 462 nm. It is obvious that the compared spectra are very close to one another. The deviation is 10–30 nm. The selective sensitivity of the investigated structures extends from the UV region of the spectrum up to the nearest IR region. It is known, that this part of the spectrum is used for the detection of hazardous substances in the environment. Thus, the investigated photodetectors, with the help of an appropriate algorithm, claim to replace the existing spectrophotometers suggesting better prices and smaller sizes.

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Fig. 19.11 The rated data on the spectral dependences of LEDs: 1-LL-304BC4BB4-IGD (InGaN), 2-L53GC (GaP), 3-L-813SRCJ14 (AlGaInP)

19.4

Conclusion

1. Experimental samples have been studied. It has been shown that it is possible to obtain the spectral selective sensitivity by changing the potential barriers in the base one at the expense by external voltage. 2. With the help of the developed algorithm, the spectral distributions of the intensities of blue, green and red LEDs have been obtained. These distributions replicate the reference distributions with the approximation of 10–30 nm. 3. High accuracy can be achieved if there is a structure in which the point of the contact of the barriers coincides with the penetration depth of the most deeply penetrated radiation wave.

References 1. Peng J, Hongbo X, He Z, Zheming W (2009) Design of a water environment monitoring system based on wireless sensor networks. Sensors 9:6411–6434 2. Normatov PI, Armstrong R, Normatov IS, Narzulloev N (2015) Monitoring extreme water factors and studying the anthropogenic load of industrial objects on water quality in the Zeravshan River basin. Russ Meteorol Hydrol 40(5):347–354 3. http://augsignals.com/products-services/water-quality-monitoring/ 4. Pshinko GN, Kobets SA, Puzyrnayain LN (2013) Concentration of U(VI) on a complexing sorbent for its determination by the spectrophotometric method. J Water Chem Technol 35 (4):145–151 5. https://people.phys.ethz.chandrealu/ASSP10_Presentations/Optical%20Spectroscopy%20Tech niques%20-%20Runar%20Sandnes.pdf 6. http://www.dissercat.com/content/razrabotka-i-primenenie-distantsionnykhspektrometricheskikh-metodov-issledovaniya-prirodnyk 7. Kautzsch Th (2013) Photo cell devices and methods for spectrometric applications. Patent US 20130285187 A1 8. Kautzsch Th (2014) Photodetector with controllable Spectral response. Patent US 8916873 B2

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9. Kautzsch Th (2012) Photocell devices and methods for spectroscopic applications. Patent DE 102013207801 A1 10. Jan Ch, Daniel P, Man ST, Univ N (2005) Photodetector with controllable spectral response. Patent US 8916873 B2 11. Nataša G (2007) A novel type of tri-colour light-emitting-diode-based spectrometric detector for low-budget flow-injection analysis. Sensors 7:166–184 12. Elif ÇS, David SF, Mutlu G, Ekmel Ö, Mesut S, Selim MÜ (2014) Improved selectivity from a wavelength addressable device for wireless stimulation of neural tissue. Front Neuroeng 2014:1–12. https://doi.org/10.3389/fneng.2014.00005 13. Nader MK, Fereydoon N (2004) Filterless Si-based ultraviolet-selective photodetectors. Spire Corp. for Stennis Space Center, Mississippi, Refer to SSC-00072 14. Vanyushin IV, Gergel VA, Zimoglyad VA, Tishin Yu I (2005) Adjusting the spectral response of silicon photodiodes by additional dopant implantation. Russ Microelectron 34(3):155–159 15. Gergel VA, Lependin AV, Tishin YI et al (2006) Boron distribution profiling in asymmetrical n+-p silicon photodiodes and new creation concept of selectively sensitive photoelements for megapixel color photoreceivers. Proc SPIE 6260:61–64 16. Khudaverdyan SK, Dokholyan JG, Khudaverdyan AS, Grigoryan KH (2007) Spectrophotometric filterless photo-detector. J Phys D Appl Phys 24:7669–7674 17. Sze S (1981) Physics of semiconductor devices, 2nd edn. Wiley-Interscience, New York, p 450 18. Khudaverdyan SK, Khachatryan MG, Khudaverdyan DS, Tsaturyan SH, Ashok V (2013) New model of spectral analysis of integral flux of radiation, NATO science for peace and security series B: physics and biophysics. Springer, Dordrecht, pp 261–269 19. http://rredc.nrel.gov/solar/spectra/am0/wehrli1985.new.html 20. Komarov F, Milchanin O, Kovalyova T, Solovjov J, Turtsevich A, Karwat (2011) Low temperature formation of platinum silicide for SHottky diodes contact layer Cz. 9th international conference “Interaction of radiation with solids”, September 20–22, 2011, Minsk, Belarus, pp 365–367

Chapter 20

Smart and Connected Sensors Network for Water Contamination Monitoring and Situational Awareness Ashok Vaseashta, Gheorghe Duca, Elena Culighin, Oleg Bogdevici, Surik Khudaverdyan, and Anatolie Sidorenko

Abstract The objective of this investigation is to develop a smart and connected prototype of sensors network for monitoring contaminants in surface and underground water sources globally in real-time. Several prototypes were developed using commercial off the shelf (COTS) sensors that capture data which is communicated to a central command and control center where the data is synthesized and analyzed for an actionable response. We present here prototypes capable of spatially monitoring surface and ground waterborne contaminants in real-time, termed as “Contamination Identification and Level Monitoring Electronic Display Systems (CILM-EDS) prototype. We also present a concept under development using unmanned aerial vehicle (UAV) equipped with hyperspectral imagers and Laser-induced Breakdown Spectroscopy (LIBS), as an innovative platform to monitor and provide enhanced

A. Vaseashta (*) International Clean Water Institute, Manassas, VA, USA NJCU – A State University of New Jersey, Jersey City, NJ, USA D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova e-mail: [email protected]; [email protected] G. Duca Institute of Chemistry, Chisinau, Republic of Moldova E. Culighin · O. Bogdevici Institute of Chemistry, Chisinau, Republic of Moldova D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova S. Khudaverdyan National Polytechnic University of Armenia, Yerevan, Armenia A. Sidorenko D. Ghitu Institute of Electronic Engineering and Nanotechnologies, Chisinau, Moldova I.S. Turgenev Orel State University, Orel, Russia © Springer Nature B.V. 2020 A. Sidorenko, H. Hahn (eds.), Functional Nanostructures and Sensors for CBRN Defence and Environmental Safety and Security, NATO Science for Peace and Security Series C: Environmental Security, https://doi.org/10.1007/978-94-024-1909-2_20

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situational awareness in support of safety and security. The new UAV sensor platform (UAVSP) under development, has airborne COTS technology to capture relevant information from surface waters at several otherwise inaccessible Domains of Interest (DOI). Keywords Water · Contamination · Smart and connected systems · Safety · Security · Monitoring

20.1

Introduction

Water is fundamentally essential to sustaining life. Water exists in abundance as over 71% of the Earth’s surface is covered with water and the oceans hold about 96.5% of water on the Earth. Water is also present in the air as vapor, rivers and lakes, icecaps and glaciers, and in ground as soil moisture and aquifers. Yet, it is estimated that worldwide, approximately 1.2 billion (may in fact be close to 3 billion) people lack access to clean drinking water [1]. The global population has grown from 1 billion in 1800 to 7.7 billion in 2018. Increase in global population and exponential increase in transportation, technology, and manufacturing, production and processing of materials creating proportionate increase in waste disposal, has led to significant stress on water quality – set by universally accepted values [2]. Furthermore, as per United Nations (UN), humanity has reached a significant demographic milestone, where over 60% of people will live in big cities by 2030 than in the countryside. The growth rate is particularly rapid in many of the so-called megacities, viz. cities with more than ten million inhabitants. The megacities listed by the UN is currently at around 35 with a total population of around 280 million. All these factors pose a significant challenge in maintaining adequate yet acceptable water quality in various support sectors that are indispensable to sustaining modern urban living. The demand for clean water extends far beyond residential and municipal needs. High volumes of high purity water are critical for most industries and laboratories. The high volume of clean water, required for several manufacturing processes, can make businesses unsustainable in areas with limited water availability. As such, most industries have stringent requirements to control wastewater discharge in the environment. As industries grow, clean water will become even more scarce and critical to meeting increasing industrial production demands. By a survey conducted by the International Council for Science, environmental experts ranked freshwater scarcity as a twenty-first century issue second only to global warming [3]. Globally adequate and clean supply of water has tremendous socio-political and geo-political consequences [4]. The socio-political consequences include reduced productivity and loss of life due to illness, social impact on education, and general well-being, since geo-political consequences often result in regional conflicts. There are numerous national and cross-border conflicts arising due to the growing crisis of global freshwater scarcity. Many of the earth’s freshwater ecosystems are being critically being depleted and used unsustainably to support growing residential and

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industrial demands; thereby increasing ecological destabilization, creating a greater regional divide thus directly impacting current political, economic and social landscapes. From security standpoint, drinking water distribution systems are mostly above ground, exposed and hence are vulnerable to sabotage by intentional introduction of contaminants by adversaries and non-state actors. Such contaminations generally are accomplished with classic and non-traditional agents (NTAs), chemical and biological agents, toxic industrial chemicals (TICs) and/or toxic industrial materials (TIMs). Water supplies contain several contaminants including metals (As, Hg, Cr, Pb, etc.), organic compounds (TCE, acetone, household degreasers, halogenated organics, etc.), pesticides and compounds that do not readily decompose in water. Additional complications arise due to presence of residual pharmaceuticals present in water supply since most filtration systems are not designed to filter such contaminants. This is a major concern, especially in developing countries. In fact, most municipality filtration systems treat and isolate only common contaminants and are not equipped to treat volatile organic compounds, pesticides, pharmaceuticals, and TICs and TIMs. In view of the above scenario, it is important to use the latest state-of-the-art technological advances for monitoring and detection of contaminants in water sources. Since composition of contaminants varies from region to region, it is technologically and economically beneficial to develop a remediation strategy that is specific to that region [4] and removes only those contaminants that are present. Additionally, it is important to have a system-of-systems approach to capture contamination awareness from geographically dispersed sites using network of sensors capable of gathering information in a real-time from a large geographical area. Based on our previous capabilities, we present here several platforms, including a Global Positioning System (GPS)/Geographical Information System (GIS) based Contamination Identification and Level Monitoring Electronic Display Systems (CILM-EDS) prototype, that were developed in part using a NATO – Science for Peace funded activity to monitoring water contaminants at three different locations. Additionally, we describe a new unmanned aerial vehicle (UAV) based platform, currently under development and capable of providing required data rapidly and from locations that may otherwise be inaccessible. The UAV technology is rapidly growing, especially with respect to its capabilities, such as enhanced communication and onboard sensor platforms. Albeit, UAS as a disruptive technology is not the focus of this investigation, the research program is being developed broadly to recognize the need for and impact of technology, especially as it is uniquely applied within a Multi-sensor UAV – sensor platform (UASP) configuration. Notwithstanding, we recognize the broader social and political context within which UAS technology is deployed, which is recognized within the context of UAS Integration from a policy standpoint, although a detailed discussion is beyond the scope of this specific investigation of monitoring contaminants in surface and underground water supplies.

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Background Work

We have conducted several investigations to monitor, sense, detect and identify several air-borne [5] and water-borne [6–8] contaminants using several different methodologies. We conducted monitoring of Aral Sea in early 1990s. Simultaneously, we conducted a study of pollution monitoring in Bangkok, Thailand, Los Angeles, CA, and Charleston, WV [9]. We monitored many pollutants, such as PM2.5, PM10, VOCs, CO, SO2 and O3 through data obtained by a network of sensors which was superimposed on data as received from Satellites. The data from the gas sensors monitoring air pollutants was uploaded in real-time via Personal Digital Assistant (PDA) to the air quality monitoring server as concentration values. The data is then compared with the satellite data and air dispersion modeling for air pollution over the area under investigation; and to assist national policymakers in establishing pollution awareness policies and priorities. Moderate Resolution Imaging Spectroradiometer (MODIS) was used to monitor forest fire and biomass burning occurrence in Thailand. To understand the air quality conditions, the MODIS aerosol product was used to identify the status of air quality by monitoring the ambient Aerosol Optical Thickness (AOT). Daily Level 2 data was produced at the spatial resolution of a 10  10 km2 (at nadir) pixel array. The product was generated in and distributed by the Level 1 and Atmosphere Archive and Distribution System (LAADS). The SCanning Imaging Absorption SpectroMeter for Atmospheric ChartographY (SCIMACHY) was used to determine the global troposphere NO2 column. Broad spectral and fine spatial resolution allows the estimation of NO2 emissions. SCIMACHY was launched on Environmental Satellite (ENVISAT) observing nadir and limb viewing with spatial resolution 60  30 km2. The data obtained from these satellites sensors and measurements conducted on ground using the gas sensors was used for numerical modelling and to identify the correlation of the air quality levels, as shown in Fig. 20.1.

Fig. 20.1 GIS and remote sensing techniques are employed to determine the affected areas [9]

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This investigation provided background and Segway into some of the desired capabilities for the current approach, viz. smart and connected monitoring platforms.

20.3

Current Methodology

As a part of a North Atlantic Treaty Organization (NATO) Science for Peace and Security project, the proposed activity was to use advanced (Nano) technology and other advanced technology-based sensor platforms to monitor inadvertent and intentional, chemical-biological-radiological-nuclear (CBRN) contamination in water supplies using a stand-alone prototype. In support of the activity, we developed a GPS/GIS based CILM-EDS prototype to spatially monitor contaminants and water levels, for areas that are prone to slash-floods and tsunamis. The research under this program was focused on five distinct, yet unifying areas of the project, viz. sensing and detection of; • Metals (As, Hg, Cr, Pb, etc.), • Pathogenic agents (bacteria, virus, proteins, cryptosporidium etc.), • Organic compounds (TCE, acetone, degreasers, halogenated organics, etc.), • Pharmaceuticals (including antibiotics; steroids, estrogens, pain medicine), • Pesticide run-off, and • Compounds with large shelf-life in water. These sensors are intended to be capable of identifying multiple agents simultaneously in quantities comparable to minimum allowable contamination levels in drinking water, as shown in Fig. 20.2a. The unit required a careful selection of GIS/GPS protocol to provide accurate geographical location of sensors, user-

Fig. 20.2 (a) Distributed sensor system using remote, wireless data transmission and data gathering, (b) Artist’s rendition of CILM-EDS unit

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friendly software, and accurate sensors so that they provide accurate representation of their environment and are reliable, highly sensitive and have high specificity. An artist’s rendition of platform is shown in Fig. 20.2b. Another aspect of the project was centered on monitoring chemical contaminants in groundwater bodies of the Prut river basin. For this investigation, monitoring wells are sampled by several field trials. The results of the chemical analysis are used for the preliminary identification, characterization and classification of groundwater bodies to analyze water quality in acquirers in the Republic of Moldova to implement the EU Water Framework Directive Requirements. The results of groundwater monitoring are used for: 1. Assessment of quantitative and chemical status of all groundwater bodies; 2. Estimating groundwater flow direction and flow rate in transboundary; 3. Assessment of long-term trends in pollutant concentrations caused by both natural and anthropogenic factors; 4. Determining the chemical status of groundwater bodies that are at risk of failing to meet WFD environmental objectives; 5. Detecting upward trends in pollutant concentrations due to either natural or human impacted causes or defining starting points for trend reversal; 6. Assisting design and evaluating the effectiveness of measure program; and 7. Demonstrating compliance with drinking water protection areas (DWPA) and other protected area objectives, e.g. Natura2000, Habitats, etc. Groundwater directive lists substances for which EU-wide standards for groundwater already exist (Table 20.1). Evaluation of groundwater quality was conducted based on a comparison of the parameters’ measured values with respective national standards for potable water (sanitary norms) and for water used for irrigation. Groundwater status refers to both the quantity and chemical quality of groundwater. Contaminants levels in groundwater are used as the main measure of quantitative status. To achieve good groundwater quantitative status, the available groundwater resource should not show signs of depletion and the ecological quality objectives for groundwater-dependent surface waters should be met. Groundwater chemical status can be measured by determining the principal chemical composition and the concentration of pollutants in the groundwater body. This is usually done by reference to threshold concentrations and the EU and U.S. EPA water quality standards, and the environmental objectives associated surface waters or terrestrial Table 20.1 E.U. – wide standards for groundwater Name of pollutant Nitrate Active ingredients in pesticides including their relevant metabolites, degradation and reaction products

Quality standard 50 mg/l 0.1 μg/l 0.5 μg/la (total)

a ‘Total’ means the sum of all individual pesticides, including their relevant metabolites, degradation and reaction products

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Table 20.2 Results of the groundwater chemical analyses Parameters pH Hardness Calcium Magnesium Sodium Chlorine Sulfate Hydrocabonate Nitrates Conductivity Solid residue Pesticides Polychlorbiphenil Polyaromatic hydrocarbons

Units Unit pH mg-eqv/l mg/l

μSm/cm mg/l mcg/l mcg/l

Determined value 7.89 8.58 132.01 24.18 194.69 43.10 286.10 558.15 36.68 1215 914.9