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1
Sritongkam, Pornpimol. "Electrochemical measurement of polycyclic aromatic hydrocarbons." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274039.
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Groeber, Elizabeth A. "Electrochemically generated transient gratings: The measurement of diffusion coefficients of electrochemical reaction products /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946103567997.
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Goodwin, Stefan. "Fabrication and measurement of graphene electrochemical microelectrodes." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/fabrication-and-measurement-of-graphene-electrochemical-microelectrodes(68041aff-f4b6-4562-b807-dd547ef9c002).html.
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The electrochemical properties of graphene were investigated using a novel and clean method to fabricate device structures with mechanically exfoliated graphene samples. Graphene is known as being particularly sensitive to both contaminating fabrication methods and the substrate it is placed on, with these effects being detrimental to accurate research into the fundamental properties and sensing applications of graphene. This thesis presents micron scale graphene electrodes that have not been subject to polymer contamination or micro-lithography methods. The effect of utilising atomically flat hexagonal boron nitride as a substrate material was investigated, believed to be the first example of this for graphene electrochemical measurements. Cyclic voltammetry demonstrated the expected steady-state behaviour for microelectrodes in the hemispherical diffusion regime. The reduction of IrCl62- in weak KCl electrolytes was studied to investigate the electron transfer characteristics of the graphene devices and the reproducibility of the measurements. Average values of the standard rate constant, k0 and the transfer coefficient, alpha were found to be 3.04 ± 0.78 ×10-3 cms-1 and 0.272 ± 0.024 respectively. These values differ significantly from previous similar studies, with the effect of reduced charge doping from the substrate and the potential dependence of the density of electronic states thought to account for the differences. Despite the clean fabrication methods, a relatively large variation between separate devices was found, highlighting an inherent variation in the properties of graphene samples.
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Keay, Russell Warren. "Electrochemical sensors for measurement of water pollutants." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263016.
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Lowe, Alexander M. "Estimation of electrochemical noise impedance and corrosion rates from electrochemical noise measurements." Thesis, Curtin University, 2002. http://hdl.handle.net/20.500.11937/209.
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Electrochemical noise refers to the spontaneous fluctuations in potential and current that can be observed on a corroding metal. The use of electrochemical noise for obtaining information on the corrosion process generates much interest in research fields. One important application is the measurement of corrosion rate. This can be achieved using the electrochemical noise of a pair of electrically coupled corroding metals to obtain an estimate of electrochemical impedance - an abstract quantity that reflects various aspects of the corrosion process.There are a number of problems associated with estimation of impedance information from the electrochemical noise data, particularly regarding data pre-treatment, accuracy and precision. In addition, the present methods are incomplete: current literature does not offer information regarding the phase of the impedance; and assumptions regarding symmetry of an electrode pair cannot be tested without additional measurements.The thesis addresses the above mentioned problems. Specifically,analysis of the impedance estimation process is given to determine how precision can be affected by various factors;a novel signal processing technique is described that is shown to yield a local optimum precision;the application of the proposed signal processing to time varying systems is demonstrated by use of a time varying, frequency dependent impedance estimate;a technique for recovering phase information, given certain conditions, is suggested so that Nyquist impedance diagrams can be constructed; anda technique for testing the symmetry of a coupled pair of corroding metals is described.An integral part of electrochemical noise analysis is the software used for numerical computation. The Matlab package from MathWorks inc. provides an extensible platform for electrochemical noise analysis. Matlab code is provided in Appendix A to implement much of the theory discussed in the thesis.Impedance analysis and many other electrochemical corrosion monitoring techniques are primarily used for uniform corrosion, where the corrosion patterns occur uniformly over the exposed surface. In order to map localised corrosion, where the corrosion is typically concentrated within a small area, a wire beam electrode can be used. A wire beam electrode is a surface that is divided into a matrix of mini-electrodes so that the corrosion rate at different points can be monitored. However, manual connection of each mini-electrode to the measurement device can prove cumbersome. The final chapter of this thesis describes the design and testing of specialised multiplexing hardware to automate the process.In general, the thesis shows that by careful conditioning of the electrochemical noise prior to analysis, many of the problems with the technique of impedance estimation from the electrochemical noise data can be overcome. It is shown that the electrochemical noise impedance estimation can be extended to encompass a time varying, frequency dependent quantity for studying dynamic systems; that phase information can be recovered from electrochemical noise for the purpose of constructing Nyquist impedance diagrams; and that asymmetric electrodes can be detected without requiring additional measurements.
6
Bagley, Gillian. "The measurement and the analysis of electrochemical noise." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488277.
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Newton, Hazel Victoria. "Porous platinised carbon electrodes for electrochemical glucose measurement." Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384970.
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Lowe, Alexander M. "Estimation of electrochemical noise impedance and corrosion rates from electrochemical noise measurements." Curtin University of Technology, School of Electrical and Computer Engineering, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12723.
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Electrochemical noise refers to the spontaneous fluctuations in potential and current that can be observed on a corroding metal. The use of electrochemical noise for obtaining information on the corrosion process generates much interest in research fields. One important application is the measurement of corrosion rate. This can be achieved using the electrochemical noise of a pair of electrically coupled corroding metals to obtain an estimate of electrochemical impedance - an abstract quantity that reflects various aspects of the corrosion process.There are a number of problems associated with estimation of impedance information from the electrochemical noise data, particularly regarding data pre-treatment, accuracy and precision. In addition, the present methods are incomplete: current literature does not offer information regarding the phase of the impedance; and assumptions regarding symmetry of an electrode pair cannot be tested without additional measurements.The thesis addresses the above mentioned problems. Specifically,analysis of the impedance estimation process is given to determine how precision can be affected by various factors;a novel signal processing technique is described that is shown to yield a local optimum precision;the application of the proposed signal processing to time varying systems is demonstrated by use of a time varying, frequency dependent impedance estimate;a technique for recovering phase information, given certain conditions, is suggested so that Nyquist impedance diagrams can be constructed; anda technique for testing the symmetry of a coupled pair of corroding metals is described.An integral part of electrochemical noise analysis is the software used for numerical computation. The Matlab package from MathWorks inc. provides an extensible platform for electrochemical noise analysis. Matlab code is provided in Appendix A to implement ++<br>much of the theory discussed in the thesis.Impedance analysis and many other electrochemical corrosion monitoring techniques are primarily used for uniform corrosion, where the corrosion patterns occur uniformly over the exposed surface. In order to map localised corrosion, where the corrosion is typically concentrated within a small area, a wire beam electrode can be used. A wire beam electrode is a surface that is divided into a matrix of mini-electrodes so that the corrosion rate at different points can be monitored. However, manual connection of each mini-electrode to the measurement device can prove cumbersome. The final chapter of this thesis describes the design and testing of specialised multiplexing hardware to automate the process.In general, the thesis shows that by careful conditioning of the electrochemical noise prior to analysis, many of the problems with the technique of impedance estimation from the electrochemical noise data can be overcome. It is shown that the electrochemical noise impedance estimation can be extended to encompass a time varying, frequency dependent quantity for studying dynamic systems; that phase information can be recovered from electrochemical noise for the purpose of constructing Nyquist impedance diagrams; and that asymmetric electrodes can be detected without requiring additional measurements.
9
Labonté, Germain 1960. "Electrochemical potentials in flotation systems : measurement, interpretation and applications." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63825.
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Briers, Michael Geoffrey. "Electrochemical transducers for the continuous measurement of blood gases." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314888.
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Hoang, Van Hung. "Electrochemical Synthesis of Novel Polyaniline-Montmorillonite Nanocomposites and Corrosion Protection of Steel." Doctoral thesis, Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700059.
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This dissertation describes a new electrochemical synthesis of novel composite materials based on montmorillonite (MMT) clay and intrinsically conducting polyaniline (PANI). PANI was successfully incorporated into MMT galleries to form PANI−MMT nanocomposites. Electropolymerization of anilinium ions which are intercalated inside the clay layers have been carried out at a constant applied potential. The synthetic conditions have been optimized taking into account the effect of concentration of aniline, magnetic stirring and potential cycling. The resulting organic-inorganic hybrid material, PANI-MMT has been characterized by various physicochemical techniques. Results of elemental analysis show that nanocomposite contains only 10 % of conducting PANI. Formation of PANI inside the clay tactoid has been confirmed by the expansion of inter layer distance of MMT as revealed by X-ray diffraction studies. Relatively lower interlayer expansion for PANI-MMT than that of anilinium-MMT indicates the higher stereoregularity in PANI-MMT which has strong influence on electrical properties of nanocomposites. Infrared spectroscopy studies reveal the presence of physicochemical interaction, probably hydrogen bonding, between clay and polyaniline. Cyclic voltammetry studies indicate that presence of electroinactive clay does not influence the electrochemical activity of PANI. Electrochromic behaviour of PANI-MMT nanocomposites have been studied using in situ UV-Vis spectroscopy which reveals that electrochromism of PANI in the composite material has been retained. One of the main technological applications of conducting polymers, particularly PANI, is in the area of corrosion protection of active metals. PANI-MMT nanocomposites synthesized using the present method and a chemically synthesized PANI which is soluble in organic solvents have been used to protect C45 steel surface against corrosion. Corrosion studies have been performed using electrochemical impedance measurements(EIM)and anodic polarization studies. Electrochemical impedance data has been analyzed using a suitable equivalent circuit. Corrosion protection of steel offered by both PANI-MMT and organically soluble PANI is evident form the increase in the value of charge transfer resistance of the coated steel surfaces. Time dependent EIM measurements reveal that charge transfer resistance gradually decreases with time, however, the values are much higher than that of uncoated surfaces. Two capacitive loops, one at higher and another at lower frequencies, observed in the Nyquist plots have been assigned to the electrical properties of coating material (in the present case, PANI-MMT or soluble PANI) and electrochemical process at the interface, respectively. An anodic shift in the corrosion potential, a decrease in the corrosion rate and a significant increase in the polarization resistance indicate a significant anti-corrosion performance of both PANI-MMT nanocomposite and organically soluble PANI deposited on the protected steel surface<br>Diese Dissertation beschreibt eine neue elektrochemische Synthese neuartiger Compositmaterialien basierend auf dem Tonmineral Montmorillonite (MMT) und intrinsisch leitfähigem Polyanilin (PANI). Die Elektropolymerisation von Aniliniumionen, welche in die Tonmineralschichten eingebaut sind, wurde bei einem konstanten Potenzial durchgeführt. Das resultierende organisch-anorganische Hybridmaterial PANI-MMT wurde mit verschiedenen physikochemischen Methoden charakterisiert. Die Ergebnisse der Elementaranalyse zeigen, dass nur 10 % des Nanocompositmaterials aus leitfähigem PANI bestehen. Die Vergrößerung des Zwischenschichtabstandes von MMT, die bei Röntgendiffraktometrieuntersuchungen beobachtet wurde, lässt auf die Bildung von PANI innerhalb der Tonmineral-Taktoide schließen. IR-spektroskopische Untersuchungen deuten auf das Vorhandensein von Wechselwirkungen physikochemischer Art, wahrscheinlich Wasserstoffbindungen zwischen dem Tonmineral und Polyanilin, hin. Untersuchungen mit zyklischer Voltammetrie zeigten, dass die Anwesenheit von elektroinaktivem Tonmineral die elektrochemische Aktivität von PANI nicht beeinflusst. Das elektrochrome Verhalten von PANI-MMT Nanocompositen wurde mit UV-Vis-Spektroskopie untersucht, wobei sich herausstellte, dass das elektrochrome Verhalten vom PANI im Compositmaterial erhalten bleibt. Eines der technologischen Hauptanwendungsgebiete von leitfähigen Polymeren, insbesondere von PANI, ist der Korrosionsschutz von aktiven Metallen. PANI-MMT Nanocomposite die mit der angegebenen Methode (elektrochemisch) synthetisiert wurden und chemisch synthetisiertes in organischen Medien lösliches PANI wurden zum Korrosionsschutz von C45 Stahl eingesetzt. Die Korrosionsuntersuchungen wurden mit Hilfe von elektrochemischen Impedanzmessungen (EIM) und anodischen Polarisationsuntersuchungen durchgeführt. Der von PANI-MMT und von in organischen Medien löslichem PANI gebotene Korrosionsschutz ist wahrscheinlich auf die Zunahme des Ladungsdurchtritts widerstandes der beschichteten Stahloberfläche zurückzuführen. Die anodische Verschiebung des Korrosionspotenzials, eine Verringerung der Korrosions-geschwindigkeit und eine deutliche Zunahme des Polarisationswiderstandes sind eindeutige Hinweise für das Antikorrosionsvermögen von PANI-MMT und auch von in organischen Medien löslichem PANI, welche auf der zu schützenden Stahloberfläche abgeschieden wurden
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Wain, Leonie Alison, and n/a. "Investigating the condition of organic coatings on metals: electrochemical evaluation techniques in a conservation context." University of Canberra. Resources, Environmental & Heritage Sciences, 2002. http://erl.canberra.edu.au./public/adt-AUC20050726.144111.
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Electrochemical techniques have potential for use in conservation, both to evaluate the
protectiveness of existing coatings on metal artefacts and to evaluate potential new conservation
coatings. Three electrochemical methods have been examined in this study for
their applicability to conservation problems. Corrosion Potential Measurement is simple
but provides only minimal information on the corrosion processes occurring in an electrochemical
system. Electrochemical Impedance Spectroscopy provides both mechanistic
and predictive information on coating performance, but the data are complex to interpret
and measurements require equipment that is at present too bulky for effective on-site use
and beyond the budget of most conservation laboratories. Electrochemical Noise Measurement
can be performed using cheap, portable instrumentation and theoretically requires
relatively simple statistical processing and interpretation, making it attractive for
conservation applications. This project looks at the development of a simple, low cost
electrochemical noise measurement system for conservation needs, and uses it to compare
Electrochemical Noise Measurement with the other two techniques.
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Edwards, Stephen John. "Measurement of halides in photographic emulsions." Thesis, University of Bedfordshire, 2003. http://hdl.handle.net/10547/622158.
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Conventional Ag/AgX electrodes, responsive to halide X, cannot be used to monitor the addition of a second halide Y since such additions result in a slow chemical conversion of the macroscopic halide coating AgX to AgY. This is a serious problem in the manufacture of photographic emulsions that frequently contain more than one silver halide. The thesis describes a new electrochemical measurement technique with the ability to make appropriate determinations in solutions of mixed halides. In the new technique (termed "clean/coat/measure"), silver electrodes were prepared "in situ" by applying square wave pulses to the electrode. First the previous halide layer was removed, then the electrode was coated in situ with a new layer of silver halide and this was used to measure the open circuit potential before the cycle was repeated. In this way the halide coating reflected the composition of the measurement solution. Existing commercial instrumentation was inappropriate for the proposed measurement sequence. Thus, a range of instrument hardware and software was designed and built by the author and used to study the influences of a multitude of parameters on the measurement performance. 1. A stable and accurate measurement system was designed and fabricated allowing the potentials of eight electrodes to be measured simultaneously in grounded solutions. Data was collected and stored on a PC using custom written software. Calibration curves for conventional silver/silver chloride, bromide and iodide electrodes were obtained over a range of concentrations and temperatures. Silver/silver halides electrodes with small surface areas (< 9 mm2) and thin halide coatings (< 1 nm thick) were studied to ensure that such electrodes performed as conventional large, thickly coated electrodes. Calibration curves showed no deterioration of response due to small surface areas and, over short time scales (< 2 min), no deterioration due to thin layers. 2. A laboratory instrument was designed and built to apply potential pulses, control a rotating disc electrode (RDE) and collect data. The system allowed both controlled potential pulses to be applied to the electrodes and open circuit potentiometric measurements to be made. Measurements of potential and current were collected at a rate of 10,000 measurements per second. The system used custom software running on a PC to control the instrumentation and to store data on the PC. Using this instrumentation a RDE was used to study the new "clean/coat/measure" pulsed technique. Results from the RDE study indicated that an electrode capable of sensing halide could be produced by this technique if an applied potential pulse with sufficient charge was applied. This minimum charge (11 x w-s C cm-2) produced a coating thickness approximately equivalent to a monolayer. The study also indicated that the technique was independent of the speed of rotation of the silver electrode and was successful over a wide range of conditions of pulse time, applied potential and cycle times for solution of potassium bromide in the range 0.001 to 0.05 M. The technique also successfully measured the addition of potassium iodide to a solution of potassium bromide while conventional thickly coated electrodes did not. 3. Two further instrumentation systems were designed and built to be used in a grounded stainless steel emulsion making vessel , one to apply controlled potential pulses and one to apply constant current pulses. Using these instruments and the conditions found for the RDE, static cylindrical electrodes in stirred solutions were investigated using both controlled potential and constant current square wave pulses of between 50 and 500 ms. Both potential step and current step techniques successfully measured the halide concentration of solutions of potassium chloride and bromide (0.001 to 0.5 M) and potassium iodide (0.0001 to 0.5 M). Both methods were also shown to be able to successfully monitor the addition of iodide to bromide and chloride solutions. With respect to future work, modifications to the instrumentation are proposed, including the replacement of the PC by an on-board microprocessor, the design of a multi-channel system and use of intelligent software to determine the optimum potential or current to apply. Areas of work required to be carried out before the system could be used in a production environment are given.
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Deva, Yashika Poorvi. "Slug flow induced corrosion studies using electrochemical noise measurements." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179513355.
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Yahyavi, Zanjani Matin, Matthias Hackert-Oschätzchen, André Martin, and Andreas Schubert. "Evaluation of On-Machine Gap Measurement Strategies in Jet-Electrochemical Machining." Universitätsbibliothek Chemnitz, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-231608.
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Jet Electrochemical Machining (Jet-ECM) is a manufacturing technique that applies a free electrolyte jet to generate the desired shapes [1]. Since the principle of the technique is the same as other techniques of Electrochemical Machining where the material removal takes place based on the anodic dissolution of workpiece, the working distance, which is the distance between nozzle’s front surface and the workpiece surface, is one important parameter of the process. The working distance affects the current density and consequently the geometry removal.
The control of the working distance can be done based on the data gathered before and during machining by surface measurement [2]. This measurement usually is done by using electrostatic probing to detect a limited amount of points of the initial workpiece surface. Since electrostatic probing is comparatively slow, laser triangulation represents an alternative technique to detect a larger amount of points before machining within significantly shorter time [3]. In addition to electrostatic probing and laser triangulation, the actual working distance can be measured during the machining process to realize constant working distance. This can be done by detecting electrical signals like the actual total current. This method can be combined with pre-machining measurement by laser triangulation in order to ensure the prevention of any collision between the nozzle and the workpiece.
In this study, on-machine metrology techniques for measuring the working gap as well as current measurements will be compared. Besides, the advantages and disadvantages of these techniques will be systematized. In further studies, the possibility of combining the techniques will be investigated to enhance Jet-ECM with more accurate measurement techniques.
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Harriman, K. "Applications of adaptive finite element methods to problems in electrochemistry." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365374.
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Mashazi, Philani Nkosinathi. "Electrochemical sensing and immunosensing using metallophthalocyanines and biomolecular modified surfaces." Thesis, Rhodes University, 2012. http://hdl.handle.net/10962/d1018248.
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The synthesis of cobalt and manganese phthalocyanine complexes bearing eight hexylthio and four amino substituents was carried out. The formation of thin films of these complexes using different modification methods was also studied. Hexylthio functionalized metallophthalocyanine complexes were immobilized onto gold electrode surfaces using the self-assembly techniques. Surface modifications using cobalt and manganese tetraamino phthalocyanine as polymers, monolayers (onto electrografted surfaces) and as carbon nanotube – metallophthalocyanine conjugates was also carried out. The new method of modifying gold electrodes with metal tetraamino phthalocyanine complexes was investigated. The modified electrode surfaces were studied for their electrocatalytic properties and as potential electrochemical sensors for the detection of hydrogen peroxide (H₂O₂). The limits of detection for the H₂O₂ were of the orders of ~10⁻⁷ M for all the modified electrodes. The modified electrodes gave very good analytical parameters; such as good sensitivity, linearity at studied concentration range and well-defined analytical peaks with increased current densities. The modification methods were reproducible, highly conducting thin films were formed and the modified electrodes were very stable. The design of electrochemical immunosensors for the detection of measles-specific antibodies was also carried out. The modified surface with measles-antigen as sensing element was accomplished using covalent immobilization for an intimate connection of the measles-antigen as a sensing layer onto an electrode surface. Two methods of detecting measles-specific antibodies were investigated and these methods were based on electrochemical impedance, i.e. label-free detection, and voltammetric method using horse-radish peroxidase (HRP) labeled antibody as a reporter. The detection of measles-specific antibodies was accomplished using both these methods. The potential applications of the designed immunosensor were evaluated in real samples (human and newborn calf serum) and the electrodes could detect the antibodies in the complex sample matrix with ease.
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Park, Gee Hoon. "Determining phosphate levels in natural water using a novel electrochemical measurement device." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127729.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2020<br>Cataloged from PDF of thesis.<br>Includes bibliographical references (pages 157-177).<br>Current measurement of the phosphorus level in natural water are based on the phosphomolybdenum blue (PMB) method. In this method, the phosphate and molybdate ion form 12-molybdophosphoric acid (12-MPA) which is reduced to yield intensely coloured PMB, and its intensity is correlated with the phosphate concentration using spectrophotometry. Despite its well-established sensitivity and selectivity to the phosphate ion, commercially available in situ portable measurement devices suffer from their large footprints and limited working time. This is mainly because the wet chemistry of the PMB method requires a constant supply of liquid reagents of which volume determines the footprint and working time of the device. Such limitations of the existing methods make it difficult to access the temporal and spatial information of the phosphorus level in natural water which is crucial in the control of eutrophication.<br>In this thesis, we designed, fabricated, and evaluated two novel electrochemical phosphate detection devices that offer unique opportunities to be developed into portable, in-situ, and automated phosphate detection devices. The detection of phosphate is based on the formation of 12-MPA, wherein reagents are supplied in situ by the anodic dissolution of molybdenum (Mo). The first version of the device with two Mo electrodes in two separate chambers demonstrated that reducing the sample volume of the device reduces the time of detection and the energy consumption per measurement based on the Mo oxidation, when compared to the current state of the art (2 min and 900 mJ versus 70 min and 18 J, respectively). The second version device is improved further by simplifying the system into a single chamber with a single Mo electrode, which additionally decreases the response time to 30 s and the energy consumption to 4 mJ.<br>The experimental results with these two devices demonstrate the capability of phosphate determination (0.1 to 25 pM) in a high conductivity background solution (0.1 M NaCl), such as seawater, without significant interference from silicate ions. In addition, the second version of the device broadens its application into other types of natural water with low conductivity, and provides a promissing possibility to be further developed into an open-cell type sensor.<br>by Gee Hoon Park.<br>Ph. D.<br>Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Fang, Danjun. "ELECTROCHEMICAL MEASUREMENT OF PLASMA MEMBRANE CHOLESTEROL IN LIVE CELLS AND MOUSE TISSUES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1251945019.
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ZHU, XIAOSHAN. "NANO ELECTROCHEMICAL SENSOR AND ITS MEASUREMENT ELECTRONICS WITH A DYNAMIC TRANSDUCTION MECHANISM." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1122989975.
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IANNUCCI, LEONARDO. "Measurement techniques for microbial corrosion assessment." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2774812.
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Kim, Bruce Chang Shik. "MULTI-STEP ELECTROCHEMICAL IMPULSE GENERATOR AND POTENTIAL MONITORING SYSTEM." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275454.
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Taylor, Malcolm G. "Measurement of organic substances in the gas phase using on-line electrochemical techniques." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/12597.
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Aniline was chosen as an atmospheric pollutant which might be monitored using an electrochemical sensor. The effect of pH and of different organic solvents on electrode poisoning was investigated for the analysis of aniline by voltammetry and it was concluded that it was not possible to prevent poisoning of the electrode by the reaction products. The analysis of aniline by flow injection analysis (fia) with DC (constant potential) and pulsed (double pulse) amperometric detection also suffered from electrode poisoning and the latter had a relatively high detection limit. Secondary and tertiary substituted anilines with similar volatilities to aniline at room temperature were examined as suitable alternatives to aniline using voltammetry. Dimethyl-p-toluidine poisoned the electrode to a small extent when analysed by voltammetry. Detection of this compound by fia with pulsed amperometric detection showed improved electrode stability but was not judged suitable for long term monitoring of atmospheric samples of the amine. A satisfactory method for monitoring aniline on line was developed using fia with triple pulse amperometric detection (PAD). The PAD waveform was optimised with respect to a low detection limit and a degree of selectivity towards possible atmospheric interferents for the detection of aniline in dilute aqueous acid at a platinum electrode. A wall jet cell was designed for the analysis of aniline vapour in air which was continuously trapped in dilute acid and periodically injected into a fia system. The cell was not affected by small gas bubbles and was reasonably portable.
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Vreeland, Richard Farrington. "Expanding the Neuroanalytical Toolkit: Electrochemical Measurements of Neurotransmitters Using Poly(3,4-Ethylenedioxythiophene) Conducting Polymer Materials." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556874.
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The human brain is an extraordinarily complex organ. The process of neurotransmission gives rise to sensory experience, cognition, and decision-making. Many common diseases of the brain are incurable and their symptoms are poorly treated. To better understand the underlying molecular problems in disease states, sensitive, selective, and rapid measurements of biomolecules are needed. Given the complexity of making biological measurements in vitro or in vivo, inquiring scientists must choose measurement tools wisely. While traditional electrode materials have been used to great success, conducting polymers such as PEDOT are an excellent way to modify or improve existing measurement tools. The chemical, spatial, and temporal resolution of in vivo and in vitro measurements can be improved, all while increasing the longevity of the sensor. Compared to existing electrode materials, PEDOT is amenable to a larger variety of substrates, easier to process, inexpensive, and has excellent electrochemical behavior for the detection of neurotransmitters. We have demonstrated the utility of PEDOT by fabricating and characterizing the first device for the separation of biogenic amines, and the first device for high-throughput measurements of exocytosis from single PC12 cells. These devices will allow scientists to inexpensively and rapidly study the effects of pharmacological challenges to model systems in disease states. A PEDOT and Nafion composite polymer coating has been developed for microelectrodes, granting increased sensitivity and selectivity towards dopamine. These improvements resulted in the first in vivo electrochemical measurements of dopamine transients without administration of a reuptake inhibitor. Lastly, we have expanded the chemistry of polythiophenes by developing the synthesis of oligo-EDOT:Nafion nanoparticles. These nanoparticles are easily prepared, inexpensive, and enable quantiative spectroscopic interrogations of water content in organic solvents.
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Wilson, Jamie Robyn. "Measurement and prediction of nonlinear harmonics as a tool for dynamic characterization of electrochemical systems /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9852.
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Manning, Philip. "Investigation of the role of free radicals in biological systems using direct, real-time electrochemical measurement." Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360244.
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Coenen, Lance Gregory 1959. "MULTI-STEP COULOSTATIC IMPULSE GENERATOR AND POTENTIAL MONITORING SYSTEM." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276529.
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A Coulostatic Impulse Generator (CIG) is an electronic device that transfers electrical charge to and from a pair of electrodes inserted in plant tissue. Six discrete charge transfers can be implemented in any desired sequence. The major purpose of the CIG is to determine the electrochemical constituents of the plant apoplast electrolyte. The objective of this thesis is threefold: (1) to design, construct and test the supervisory circuitry of the CIG, (2) to design, construct and test the interface between the NEC portable computer and the CIG, (3) to generate utility software to control each circuit board in the system. To handle the extreme difference in the timing of the charge transfer (microseconds) and the subsequent plant response a three step timing sequence is employed which permits an independent range of sample times and sample numbers. Data acquired is first stored in RAM in the computer within the CIG and then transferred to the external computer. (Abstract shortened with permission of author.)
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Leopold, Sofia. "In-situ Studies of Spontaneous Potential Oscillations during Electrochemical Deposition of Copper and Cuprous Oxide." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-554-5506-9/.
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Takahashi, Masakuni. "Elucidation of the Dominant Factor in Electrochemical Materials Using Pair Distribution Function Analysis." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263748.
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京都大学<br>新制・課程博士<br>博士(人間・環境学)<br>甲第23287号<br>人博第1002号<br>京都大学大学院人間・環境学研究科相関環境学専攻<br>(主査)教授 内本 喜晴, 教授 田部 勢津久, 准教授 戸﨑 充男<br>学位規則第4条第1項該当<br>Doctor of Human and Environmental Studies<br>Kyoto University<br>DFAM
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Nuester, Jochen. "New methods in biogeochemistry the development of electrochemical tools for the measurement of dissolved and solid state compounds in natural systems /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979856728.
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Deng, Zejun. "Exploring the concepts of electrochemical blocking for single entity detection." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX059.
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Cette thèse est consacrée à l'exploration des concepts de blocage électrochimique pour la détection d'une seule entité. Le blocage électrochimique est un type de mesure électrochimique mono-entité particulièrement bien adapté à la détection d'entités isolantes, notamment des entités artificielles comme des particules de polymère ou des bioparticules comme des protéines et des bactéries. La taille de ces entités s'étend de quelques nm à plusieurs microns et leur structure électronique couvre tout le spectre, de l'isolant à l'état électronique donateur acceptant unique en passant par le comportement semi-conducteur et métallique. Actuellement, la détermination précise de la taille d'une particule par blocage électrochimique reste un défi analytique, en raison de la répartition inégale du courant sur les ultra-microélectrodes disques UME (effet dit de bord). Le but de cette thèse est de développer cette méthodologie élégante et simple en un outil analytique polyvalent et quantitatif.Tout d'abord, nous décrivons l'utilisation de Hg UME hémisphérique pour détecter des particules isolantes individuelles afin de supprimer les effets de bord sur les UME de disque. L'utilisation de Hg UME hémisphérique permet des mesures simultanées de la distribution granulométrique et de la concentration des particules en suspension. À l'aide de simulations numériques, nous en déduisons la relation quantitative entre la magnitude du pas courant et la taille du cordon. La fréquence de collision mesurée pour une taille de bille donnée est ensuite convertie en concentration (en mol/L) par quantification des contributions relatives de migration et de diffusion pour chaque taille de bille. Dans nos conditions expérimentales (faible concentration d'électrolyte de support), la migration domine le flux de billes. La taille moyenne des billes de polystyrène de 0.5 et 1 μm de rayon obtenues par électrochimie et microscopie électronique à balayage (MEB) ne diffère que de -8% et -9%, respectivement. La concentration totale de billes de polystyrène de 0.5 et 1 µm de rayon obtenue par électrochimie se trouve en étroite concordance (< 10% d'erreur) avec leurs concentrations nominales (25 et 100 fM).Deuxièmement, nous étendons la stratégie du blocage électrochimique à la détection de particules électriquement conductrices. Cette stratégie, la dépression électro-catalytique, est basée sur la différence intrinsèque de cinétique de transfert électronique entre certains matériaux. Nous utilisons cette stratégie pour détecter des particules nanoplaquettes de graphène (GNP), un materiaux peu actif en electro-catalyse. En fonction du potentiel nous montrons que la collision de GNP plus ou moins bloquer cinétiquement l’oxydation de l’hydrazine sur une UME de Pt et ainsi produire un signal similaire au signal obtenu avec des particules isolantes comme des billes de polystyrène.Enfin, nous couplons l'électrochimie et la microscopie en champ clair pour élucider comment la translation et la rotation des GNPs affectent la réponse en courant. Une fois que le GNP touche la surface de Pt, le courant transitoire provient de l'augmentation instantanée de la surface électroactive du GNP<br>This dissertation is dedicated to exploring the concepts of electrochemical blocking for single entity detection. Electrochemical blocking is a type of single-entity electrochemical measurement particularly well adapted to the detection of insulating entities, including artificial entities like polymer particles or bioparticles like proteins and bacteria. The size of these entities spans between few nm to several microns and their electronic structure covers the entire spectrum from insulator to single accepting donating electronic state to semiconducting and metallic behavior. Currently, the accurate determination of the size of a particle by electrochemical blocking remains an analytical challenge, owing to the uneven current distribution on disk ultra-microelectrodes UMEs (so-called edge effect). The goal of this dissertation is to develop this elegant and straightforward methodology into a versatile and quantitative analytical tool.First, we describe the use of hemispherical Hg UME to detect individual insulating particles in order to remove the edge effects on disk UMEs. The use of hemispherical Hg UME enables simultaneous measurements of the size distribution and concentration of particles in suspension. Using numerical simulations, we deduce the quantitative relation between the magnitude of the current step and the size of the bead. The frequency of collision measured for a given size of bead is then converted into a concentration (in mol/L) by quantification of the relative contributions of migration and diffusion for each size of the bead. Under our experimental conditions (low concentration of supporting electrolyte), migration dominates the flux of bead. The average size of polystyrene beads of 0.5 and 1 μm radius obtained by electrochemistry and scanning electron microscopy (SEM) differs by only -8% and -9%, respectively. The total concentration of polystyrene beads of 0.5 and 1 μm radius obtained by electrochemistry is found in close agreement (<10% of error) with their nominal concentrations (25 and 100 fM).Second, we extend the strategy of electrochemical blocking to the detection of electrically conducting particles. This strategy, electro-catalytic depression, is based on the intrinsic difference in electron transfer kinetics between materials to detect poorly catalytic particles such as graphene nanoplatelets (GNPs). Under the potential of 0.1 V vs. Ag/AgCl, GNPs block the oxidation of hydrazine on a 5 µm radius Pt UME, producing staircase-shaped drops of current (negative steps) similar to the signal obtained with insulating particles like polystyrene beads At high potentials (> 0.1 V), where hydrazine oxidation occurs on the GNP, the kinetic difference between GNP and Pt decreases, leading to the decrease of both average and median current step size and the appearance of positive steps.Finally, we couple electrochemistry and bright-field microscopy to elucidate how the translation and rotation of GNPs affect the current response. Once the GNP touches the surface of Pt, the transient current responses come from the instantaneous increase in the electroactive surface area of GNP. Importantly, the rotation of GNP will cause changes in current transients
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HIDALGO, DIAZ DIANA CAROLINA. "Development of innovative materials used in electrochemical devices for the renewable production of hydrogen and electricity." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2588827.
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One of the most important challenges for our society is providing powerful devices for renewable energy production. Many technologies based on renewable energy sources have been developed, which represent a clean energy sources that have a much lower environmental impact than conventional energy technologies. Nowadays, many researches focus their attention on the development of renewable energy from solar, water, organic matter and biomass, which represent abundant and renewable energy sources. This research is mainly focused on the development of promising electrode materials and their potential application on emerging technologies such as artificial photosynthesis and microbial fuel cell (MFC). According to desired proprieties of functional materials, this research was focused on two main materials: (1) TiO2 for the development of electrodes for the water splitting reaction due to its demonstrated application potential as photocatalyst material and (2) carbon-based materials for the development of electrodes for MFC.
In the first part of the investigation, different TiO2 nanostructures have been studied including: synthesis, characterization and test of TiO2-based materials with the aim of improving the limiting factors of the photocatalytic reaction: charge recombination and separation/migration processes. The photo-catalytic properties of different TiO2 nanostructures were evaluated including: TiO2 nanoparticles (NPs) film, TiO2 nanotubes (NTs) and ZnO@TiO2 core-shell structures. Photo-electrochemical activity measurements and electrochemical impedance spectroscopy analysis showed an improvement in charge collection efficiency of 1D-nanostructures, related to a more efficient electron transport in the materials. The efficient application of both the TiO2 NTs and the ZnO@TiO2 core-shell photoanodes opens important perspectives, not only in the water splitting application field, but also for other photo-catalytic applications (e.g. photovoltaic cells, degradation of organic substances), due to their chemical stability, easiness of preparation and improved transport properties. Additionally, in order to improve the photo-catalytic activity of TiO2 NPs, PANI/TiO2 composite film was synthesized. PANI/TiO2 composite film was successfully applied as anode material for the PEC water splitting reaction showing a significant increase in the photocatalytic activity of TiO2 NPs composite film essentially attributed to the efficient separation of the generated electron and hole pairs. To date, no cost-effective materials system satisfies all of the technical requirements for practical hydrogen production under zero-bias conditions. For this propose, to promote the sustainability of the process, the bias require to conduct PEC water splitting reaction could be powered by MFC systems in which many efforts have been done to improve power and electricity generation as is explained below.
In this work, different strategies were also applied in order to improve the performance of anode materials for MFCs. The investigation of commercial carbon-based materials demonstrated that these materials, normally used for other ends are suitable electrodes for MFC and their use could reduce MFC costs and improve the energy sustainability of the process. In addition, to enhance power generation in MFC by using low-cost and commercial carbon-based materials, nitric acid activation (C-HNO3) and PANI deposition (C-PANI) were performed on commercial carbon felt (C-FELT) in order to increase the performance of MFC. Electrochemical determinations performed in batch-mode MFC reveled a strong reduction of the activation losses contribution and an important decrease of the internal resistance of the cell using C-HNO3 and C-PANI of about 2.3 and 4.4 times, respectively, with respect to C-FELT. Additionally, with the aim of solvent different MFC operational problems such as: biofouling, low surface area and large-scale MFC, an innovative three-dimensional material effectively developed and used as anode electrode. The conductive carbon-coated Berl saddles (C-SADDLES) were successfully used as anode electrode in batch-mode MFC. Electrochemical results suggested that C-SADDLES offer a low-cost solution to satisfy either electrical or bioreactor requirements, increasing the reliability of the MFC processes, and seems to be a valid candidate for scaled-up systems and for continuous mode application of MFC technology. In addition, the electrochemical performance and continuous energy production of the most promising materials obtained during this work were evaluated under continuous operation MFC in a long-term evaluation test. Remarkable results were obtained for continuous MFCs systems operated with three different anode materials: C-FELT, C-PANI and C-SADDLES. From polarization curves, the maximum power generation was obtained using C-SADDLES (102 mW•m-2) with respect to C-FELT (93 mW•m-2) and C-PANI (65 mW•m-2) after three months of operation. The highest amount of electrical energy was produced by C-PANI (1803 J) with respect to C-FELT (1664 J) and C-SADDLES (1674 J). However, it is worth to note that PANI activity was reduced during time by the operating conditions inside the anode chamber.
In order to demonstrate the wide application potential MFC, this work reports on merging heterogeneous contributions and combining the advantages from three separate fields in a system which enables the ultra-low-power monitoring of a microbial fuel cell voltage status and enables pressure monitoring features of the internal conditions of a cell. The solution is conceived to provide an efficient energy source, harvesting wastewater, integrating energy management and health monitoring capabilities to sensor nodes which are not connected to the energy grid. Finally, this work presented a general concept of the integration of both devices into a hybrid device by interfacing PEC and MFC devices (denoted as PEC-MFC), which is proposed to generate electricity and hydrogen using as external bias the potential produce by microbial fuel cell
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Koch, Reinhold [Verfasser], Andreas [Akademischer Betreuer] Jossen, Andreas [Gutachter] Jossen, and Olfa [Gutachter] Kanoun. "On-line Electrochemical Impedance Spectroscopy for Lithium-Ion Battery Systems : Estimation, Compensation and Avoidance of Measurement Deviations / Reinhold Koch ; Gutachter: Andreas Jossen, Olfa Kanoun ; Betreuer: Andreas Jossen." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1172880018/34.
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Walker, Ian A. B. L. "The measurement of human plasma catecholamines by high performance liquid chromatography and electrochemical detection : the study of sympathoadrenal responses during the induction of anaesthesia prior to surgery." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242225.
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Höckerdal, Henrik. "Electrochemical Measurements of Salivary Amylase Activity." Thesis, Linköpings universitet, Biosensorer och bioelektronik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77275.
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Stress constitutes a more and more common cause for many health disorders inmodern society. Salivary -amylase (AA), the most abundant enzyme in humanwhole saliva, has in recent years been found to be a good surrogate biomarker formonitoring stress levels in individuals. This work aims to form the foundation ofa novel approach for measuring the activity of the enzyme in saliva samples bymeans of electrochemistry. The idea is to implement several enzymes along witha starch substrate and an electron mediator in a single system. This system isthen to be coated onto a screen-printed electrode (SPE), which is used along withan electrical component, designed to give rise to a quantifiable, electrical signalwhen the starch is broken down by the AA contained in an added saliva sample.Several such enzyme systems are here qualitatively evaluated. As electron mediator,ferro-/ferricyanide is used. Two different enzymes, glucose oxidase (GOx) andpyrroloquinoline quinone dependent glucose dehydrogenase (PQQ-GDH), are testedfor making up the saccharide oxidising part of the system. Both prove themselvescapable in terms of qualitatively giving rise to an electrical signal. But, in terms ofinternal quantitative comparisons between the two, no practical experiments areperformed in this work. In some runs, the enzyme -glucosidase (AG) is used asan intermediate for breaking down the AA/starch oligosaccharide products intomonosaccharides. This to increase the system’s electrical signal output when usingGOx as oxidising agent. Regrettably, due to lack of AG enzyme, these runs do notprovide any conclusive data, and so further investigations of systems including thisenzyme are needed. Otherwise, all systems tested seem to work, and neither ofthem appear better than the others. Therefore, all of them will require furtherquantitative testing to determine which one is best to implement in the final designof the enzyme system to be applied onto the SPE.
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Lim, Wee-Lin. "Electrochemical impedance measurements of biological polyelectrolytes." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321776.
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Šťavík, Jaroslav. "Kapacitní měření na strukturách fotovoltaických solárních článků." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219523.
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The work deals with the measurement of CV characteristics of photovoltaic cells and the consequent derivation of the free / bound charge in the volume. It also discusses factors that influence these measurements.
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Chatillon, Yohann. "Méthodes électrochimiques pour la caractérisation des piles à combustibles de type PEM en empilement." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0195/document.
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La pile à combustible apparaît comme une technologie prometteuse pour la conversion énergétique à faible impact environnemental mais sa commercialisation à grande échelle nécessite de relever certains défis économiques et technologiques. Tout d'abord, pour fonctionner, la pile a besoin de systèmes (compresseurs, convertisseurs,...) parfois volumineux et coûteux en énergie. Ensuite, le prix de certains éléments constituants la pile reste élevé car ce sont des produits à haute valeur technologique utilisant des matériaux parfois très onéreux (membrane polymère, couche catalytique,...). L'optimisation du système pile à combustible et des éléments environnants n'est pas le seul défi à relever. En effet, la durabilité des assemblages membrane-électrodes (AME) constitue une barrière majeure à la commercialisation de ces systèmes pour des applications stationnaires ou dans les transports. Afin d'améliorer la durabilité de ces assemblages, il est nécessaire de bien caractériser les différents éléments les constituant et de déterminer et de quantifier les mécanismes de dégradation. Le premier chapitre de cette thèse présente une étude bibliographique sur les PEMFC et l'électrochimie fondamentale régissant le fonctionnement de ces systèmes. Le second chapitre présente les matériaux composant les différents éléments du système ainsi que les méthodes expérimentales utilisées pour caractériser les AME. Le chapitre suivant évoque l'étude et la mise en oeuvre d'une technique électrochimique de caractérisation d'un empilement, notamment la mesure de surface active des différentes cellules. Enfin, le quatrième et dernier chapitre concerne une étude du vieillissement hétérogène d'empilements de trois cellules<br>Proton exchange membrane (PEM) fuel cells are seen as a promising technology for environmentally friendly energy conversion but its wide spread commercialization need taking up several technological and economic challenges. First, to operate PEM fuel cells require sizeable and energy consuming surrounding systems (compressors, converters,...). Then, elements constituting the cell remain costly because with high technological value and using expensive materials (polymer membrane, catalyst layer,...). The optimization of the system and the surrounding elements is not the only challenge to take up. Indeed, durability of the membrane electrode assembly (MEA) constitutes the major barrier to commercialization of these systems for stationary or transport applications. In order to increase durability of the assemblies, a better understanding of the aging mechanisms is necessary. The first chapter of the thesis introduces a bibliographical study on PEMFC and the fundamental electrochemistry governing the system operation. The second chapter introduces materials composing the different system elements and experimental methods used for PEMFC characterization. The next chapter deals with a study on stack characterization, particularly the development of an electrochemical technique allowing active surface area measurement of the cells composing the stack. Finally, the last chapter deals with heterogeneous aging within PEMFC stacks
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Abdelsalam, Mamdouh Elsayed. "Development of microelectrode techniques for analytical and environmental applications." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326794.
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Kim, Joon Hong. "Electrochemical measurements and thermodynamic properties of alkali fullerides." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/NQ42745.pdf.
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Kim, Joon Hong. "Electrochemical measurements and thermodynamic properties of alkali fullerides /." *McMaster only, 1997.
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House, Stephen D. "Quantitation of mass spectral measurements of electrochemical products /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu148777621079316.
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Kolliopoulos, Athanasios. "Development of novel electrochemical measurements for water quality." Thesis, Manchester Metropolitan University, 2014. http://e-space.mmu.ac.uk/578168/.
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This thesis reports the development of novel electrochemical methods applied for the quantification of important analytes in the field of water quality. Chapter 1 of this thesis focuses on the analytical methodologies used and the current requirements for low cost, environmental friendly and portable analytical tools into the field of water quality. In this chapter it is described how the analytical methodologies based on the use of screen-printed electrochemical sensors meets these requirements and why the development of such methodologies is the main purpose of this thesis. Chapter 2 overviews the relevant fundamental electrochemical concepts with which this thesis is concerned. Chapter 3 gives a synopsis of the electrode materials as well as screen-printing upon which this thesis is based upon with a detailed overview not only of the screen-printing process, but also its current applications within the field of electrochemistry with particular attention paid towards the development of novel screen-printed electrode sensors applied into the field of water quality. Chapter 4 describes the generic experimental methods used in this thesis. It gives details of the electrode materials, chemicals and real samples used in this thesis. Additionally it describes the screen-printing process on which the production of the in-door carbon based screen-printed sensors was based. Chapter 5 reports the first examples of using electrochemical sensors for the target analytes selenium (IV), antimony (III) phenol and chlorophenols within drinking water; simplification of these analytical protocols is demonstrated through the production of screen-printed sensors. Chapter 6 describes the development of screen-printed graphite sensors for the novel detection of dissolved phosphorus within environmental samples through the electrochemical adaption of a colorimetric protocol. The electroanalytical protocol for the detection of dissolved phosphorus, a key parameter of eutrophication, was independently verified with ion chromatography and inductively coupled - plasma atomic emission spectroscopy. Finally, Chapter 7 reports the first example of sensing cyclohexylamine and morpholine commonly used in industrial water as corrosion inhibitors for steam condensate treatment via indirect electrochemical protocol using screen-printed sensors. This is the first time that screen-printed sensors are applied into the detection of water treatment chemicals.
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Robin, Serge. "Etude de la turbulence parietale par la methode electrochimique." Paris 6, 1987. http://www.theses.fr/1987PA066606.
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Les courants limites de diffusion sont mesures sur des microelectrodes inserees dans la paroi d'un canal rectangulaire lisse assurant les conditions d'un ecoulement turbulent bidimensionnel bien etabli. On utilise la technique de dorure par masquage pour obtenir des capteurs electrochimiques a contours bien definis
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Appusamy, Boopathy Harish, and Pavan Kumar Bonthala. "Electrochemical etching and anodizing as key stages of surface treatment of aluminium foil for electrolytic capacitor industry : Application of Electro Chemical Impedance Spectroscopy as non-destructive characterization of etched anode foil with an anodized dielectric oxide layer." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Produktutveckling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-37858.
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In the initial stage, the sample preparation was done by using the techniques of Anodic etching and anodic forming processes where a repeated trial and error method of sample preparation headed towards making out a suitable sample set for characterization. After this step, the set of 2 different industrial samples were introduced and anodic oxide forming process was carried out in different electrolytes. In the sample preparations, 4 different electrolytes were used 15% wt. Ammonium Adiphate, 1.5% wt. Ammonium Phosphate, 7% wt. Boric acid and 15% Penta Borate at different stages for performing the anodic oxide forming process. Minimum forming voltages of 20V to a maximum of 100V was employed in the sample preparation and to overcome the waiting time in forming the etched samples a higher current of 0.5A was used. After the samples preparation, Electrochemical Impedance spectroscopy was used as a tool for characterising the various groups of samples and for observing the micro structures of various samples, they were fractured and the observed on the cross section by SEM. After the analysis of the etched samples was made, an attempt to compare the results of the data of these samples to that of the 2 set of industrial samples was made and found that the resultant data wasn’t stable enough to characterize since huge scattering were occurring and whereby the simulation of the CPE circuit for the chosen circuit in the analysis was not possible. Under the analysis, a randomly chosen industrial sample was also used and the resultant data was utilised in understanding the response of the system to different electrolytes.<br>Sammanfattning Avhandlingsarbetet har genomförts på KEMET AB i samarbete med yttekniklaboratoriet vid JTH i syfte att karakterisera den etsade anodiska aluminiumfolien som grundprov med anodisering och etsning för ytbehandling. I inledningsskedet gjordes provberedningen med användning av teknikerna för anodisk etsning och anodbildande processer där en upprepad provnings- och felmetod för provberedning ledde ut mot att utarbeta en lämplig provuppsättning med avseende på karakterisering. Efter detta steg infördes uppsättningen av 2 olika industriella prover och anodoxidbildande process utfördes i olika elektrolyter. I provpreparaten användes 4 olika elektrolyter 15 % vikt Ammoniumadiphat, 1,5 vikt% Ammoniumfosfat, 7 vikt% Borsyra och 15 % Penta-borat vid olika steg för utförande av anodoxidbildningsförfarandet. Minimala formningsspänningar på 20V till ett maximum av 100V användes i provframställningen och för att övervinna väntetiden vid bildning av de etsade proven användes en högre ström av 0,5A. Efter provberedningen användes elektrokemisk impedansspektroskopi som ett verktyg för att karakterisera de olika grupperna av prover och för att observera mikrostrukturerna i olika prover, de bröts och de observerades i tvärsnittet av SEM. Efter att analysen av de etsade proverna gjordes ett försök att jämföra resultaten av data från dessa prover till den för de två uppsättningarna av industriella prover. Det är konstaterat att de resulterande data inte var stabila nog att karakterisera eftersom stor spridning inträffade och varigenom simuleringen av CPE-kretsen för den valda kretsen i analysen inte var möjlig. Under analysen användes också ett slumpmässigt valt industriellt prov och de resulterande data användes för att förstå systemets respons till olika elektrolyter.
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Grunhagen, Thijs. "Nutrient transport into intervertebral discs; modelling and electrochemical measurements." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525248.
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Allcock, Bryan W. "Hydrogen concentration measurements using a gel-filled electrochemical probe." Thesis, Cranfield University, 1993. http://dspace.lib.cranfield.ac.uk/handle/1826/12140.
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A novel gel-filled electrochemical hydrogen probe was developed and used to measure hydrogen concentrations in carbon-manganese steels. The results were compared with those from an electrochemical permeation technique and a volumetric method. The probe was used to determine the distribution of hydrogen in 5mm steel plates cathodically charged on one side to represent the wall of a pipe or pressure vessel used in hydrogen service. The concentration measurements obtained by the three techniques were in good agreement with each other and with those predicted from diffusion equations and this permitted the precise boundary conditions on the charged metal surface to be determined. Surface reaction kinetics were investigated to model the hydrogen distribution and these were solved using solutions to Fick's diffusion equations. After long charging times the hydrogen concentration on the efflux surface of the plate approached that on the influx side, indicating that an almost uniform hydrogen distribution had been established. Rather than rapid loss of hydrogen from the free surface, as had been assumed previously, it was clear that there was a large resistance to hydrogen transport across the metal/air interface. Microstructural damage was examined both optically and using the scanning electron microscope. Separate investigations were carried out to help understand the effect that reversible and irreversible trapping had on the diffusion of hydrogen through the steel.
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Bai, Seoung-Jai. "Nanoscale probes for electrochemical measurements on single cells and organelles /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Scott, Timothy Anthony 1963. "Determining the extent of specific adsorption at a solid metal electrode utilizing differential capacitance measurements." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277097.
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The Hurwitz-Parsons method of analysis is employed utilizing a spreadsheet application on an IBM-AT. It is designed to calculate the extent of specific adsorption of an inorganic anion or neutral organic molecule at a solid electrode without knowledge of the point of zero charge. Up to eight bulk adsorbate concentrations represented by differential capacitance versus potential curves may be input. The curves can contain up to 100 points. Output is in units of moles/cm2 and is provided at 10 potentials for each bulk adsorbate concentration. A detailed overview and a formula list of the application are provided. A brief overview of the theories associated with the electrochemical double layer and a related literature review are included.
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Hajjaji, Hamza. "Nanosondes fluorescentes pour l'exploration des pressions et des températures dans les films lubrifiants." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0076/document.
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L’objectif de ce travail est d’utiliser les nanoparticules (NPs) de nanosondes fluorescentes de température en particulier dans les films lubrifiants. Le développement de ces nanosondes nécessite la détermination de leurs sensibilités thermiques afin de pouvoir sélectionner les NPs les plus prometteuses. Pour atteindre cet objectif, nous avons présenté deux méthodes d’élaboration utilisées pour la synthèse des nanostructures à base de SiC-3C, la méthode d’anodisation électrochimique et la méthode d’attaque chimique. Dans le premier cas, les analyses FTIR,RAMAN et MET des NPs finales ont montré que la nature chimique de ces NPs est majoritairement formée de carbone graphitique. L’étude détaillée de la photoluminescence de ces NPs a montré que le processus d’émission dépend de la chimie de surface des NPs, du milieu de dispersion et de sa viscosité, de la concentration des suspensions et de la température du milieu. Pour la deuxième famille de NP de SiC, les analyses cohérentes MET, DLS et PL ont montrées une taille moyenne de 1.8 nm de diamètre avec une dispersion de ±0.5nm. Le rendement quantique externe de ces NPs est de l’ordre de 4%. Les NPs dispersées dans l’éthanol, n’ont pas montré une dépendance à la température exploitable pour notre application. Par contre, les NPs de SiC produites par cette voie, étant donné la distribution en taille resserrée et le rendement quantique « honorable » pour un matériau à gap indirect, sont prometteuses pour des applications comme luminophores en particulier pour la biologie grâce à la non toxicité du SiC. Dans le cas des NPs de Si, nous avons également étudié deux types différents de NPs. Il s’agit de : (i) NPs obtenues par anodisation électrochimique et fonctionnalisées par des groupements alkyls (décène, 1-octadécène). Nous avons mis en évidence pour la première fois une très importante variation de l’énergie d’émission dEg/dT avec la température de type red-shift entre 300 et 400K. Les mesures de(T) conduisent à une sensibilité thermique de 0.75%/°C tout à fait intéressante par rapport aux NPs II-VI. De plus il a été montré que la durée de vie mesurée n’est pas fonction de la concentration. (ii) NPs obtenue par voie humide et fonctionnalisées par le n-butyl. Pour ce type de NPs nous avons mis pour la première fois en évidence un comportement de type blue-shift pour dEg/dT de l’ordre de -0.75 meV/K dans le squalane. Pour ces NPs, la sensibilité thermique pour la durée de vie de 0.2%°C est inférieure à celle des NPs de type (i) mais largement supérieure à celle des NPs de CdSe de 4 nm (0.08%/°C). La quantification de cette la sensibilité à la température par la position du pic d’émission dEg/dT et de la durée de vie nous permet d’envisager la conception de nanosondes de température basée sur les NPs de Si avec comme recommandations l’utilisation de NPs obtenues par anodisation électrochimique et de la durée de vie comme indicateur des variations en température<br>The goal of this study is the use of Si and SiC nanoparticles (NPs) as fluorescent temperature nanoprobes particularly in lubricating films. The development of these nanoprobes requires the determination of their thermal sensitivity in order to select the best prospects NPs. To achieve this goal, we presented two preparation methods used for the synthesis of 3C-SiC based nanostructures : (i) anodic etching method and (ii) chemical etching method. In the first case, the FTIR, Raman and TEM analysis of final NPs showed that the chemical nature of these NPs is formed predominantly of graphitic carbon. The detailed photoluminescence study of these NPs showed that the emission process depends on the surface chemistry of the NPs, the dispersion medium and its viscosity, the suspension concentration and temperature of the environment.. In the second case, coherent TEM, DLS and PL analyzes showed an average size of 1.8 nm in diameter with a dispersion of ±0.5 nm. The external quantum efficiency of these NPs is 4%. NPs dispersed in ethanol, did not show an exploitable fluorescence dependence on temperature for our application. On the other hand, 3C-SiC NPs produced by this way, given the narrow size distribution and the reasonably high quantum yield for an indirect bandgap material, are promising for applications such as luminophores in particular in the biology field thanks to nontoxicity of SiC. In the case of Si we studied also two different types of NPs. (i) NPs obtained by anodic etching and functionalized by alkyl groups (decene, octadecene). We have demonstrated for the first time an important red-shift in the emission energy dEg/dT with temperature from 300 to 400K. The PL lifetime measurement(T) lead to a thermal sensitivity of 0.75% /°C very interesting compared to II-VI NPs. Furthermore it has been shown that t is not depending on the concentration. (ii) NPs obtained by wet-chemical process and functionalized with n-butyl. For this type of NPs we have identified for the first time a blue-shift behavior of dEg dT in the order of -0.75 meV/K in squalane. The thermal sensitivity for the PL lifetime of these NPs is 0.2%/°C, which is lower than that of NPs obtained by anodic etching method, but much greater than that of CdSe NPs with 4 nm of diameter (0.08%/°C). Quantification of the temperature sensitivity by the position of emission peak dEg/dT and the PL lifetime dτ/dT allows us to consider the realization of temperature nanoprobes based on Si NPs with recommendations to use Si NPs obtained by anodic etching method and PL lifetime as an indicator of temperature changes