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The electrochemical behavior of nickel (Ni) in different concentrations of sulfuric acid (H2SO4) was studied via cyclic voltammetry (CV) over a range of potentials (0.0 V– 3.0 V) at room temperature. The presented work displays novel experiments where external forcing by a platinum (Pt) electrode changed the proton concentration at a Ni electrode surface in order to control the frequency and magnitude of periodic oscillations produced. When studying unique phenomena such as the Ni phenomena in this thesis, efficient, durable, and inexpensive technology is always beneficial. A coupled microelectrode array sensor or CMAS which has been used for over four decades to study pitting corrosion, crevice corrosion, intergranular corrosion, galvanic corrosion, and other heterogeneous electrochemical processes were fabricated in a novel, systematic, inexpensive, and time efficient process. The presented work shows how to make the CMAS and proved that they functioned properly.

Magister Scientiae - MSc (Chemistry) / In this study, graphene oxide was synthesized by oxidizing graphite using the modified Hummer's method. The graphene oxide was characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, High Resolution Transmission Electron Microscopy, Scanning Electron Microscopy and X-Ray Diffraction for structural and morphological properties. The graphene oxide was electrochemically reduced on a carbon paste electrode followed by the in situ deposition of mercury thin films to achieve electrochemically reduced graphene oxide modified carbon paste metal film electrodes (ERGO-CP-MEs). The experimental parameters (amplitude, deposition time, deposition potential, frequency and rotation speed) were optimized, and the applicability of the modified electrode was investigated towards the simultaneous and individual determination of TI1+ and In3+ at the low concentration levels (?g L-1) in 0.1 M acetate buffer (pH 4.6) using square wave anodic stripping voltammetry (SWASV). The detection limit values for individual analysis at electrochemically reduced graphene oxide modified carbon paste mercury film electrode (ERGO-CP-HgE ) was 2.4 and 1.1 ?g L-1 for TI1+ and In3+, respectively. The detection limit values for simultaneous analysis at ERGO-CPE was 1.32 and 1.33 ?g L-1 and individual analysis was 0.975 and 1.04 ?g L-1 for TI1+ and In3+, respectively.

Today's society is currently developing lithium-ion batteries to eventually replace the use of fossil fuels. High entropy oxides is a new type of material to use as an anode in the lithium-ion battery. These high entropy oxides may consist of a few different transition metals including lithium and oxygen. In this report was (MgCoNiZn)1-xLixO synthesized with a method called Pechini with a molar fraction of x=0.35. This study compares the results from a reference study that has shown the potential of the electrochemical characteristics of (MgCoNiZn)1-xLixO for application as anode in a lithium-ion battery.  The synthesis starts with a heating step to remove all the organics in the composition. The powder consists of several structures and, therefore goes through a calcination step to dissolve all of the intermediate phases into the rock-salt structure. The structure of the powder had a lattice constant of 4,138Å. The powder was made into a slurry containing Carbon black, PVDF and NMP to later get coated by a Dr. Blade. After drying the coating the cell was then assembled with lithium as metal cathode and 1M LiPF6 in 1:1 EC/DMC as electrolyte. After the cell was assembled it, went through electrochemical properties test using a potentiostat and the cell being inside a in a climate chamber at 25°C.  7 cycles were done to plot a cyclic voltammetry graph as well as a discharge-charge test was performed. The cyclic voltammetry and discharge-charge test was run with a voltage range of 0,053 V. The discharge-charge test was run at a current density of 100 mA/g and a constant current of 42,68 mA. / Dagens samhälle genomgår en stor utveckling av litium-jon batterier för att kunna ersätta användningen av fossila bränslen. Höga entropi oxider är ny typ av material som används som anod material för litiumjonbatterier. Dessa höga entropi oxider kan bestå av en rad olika övergångsmetaller inklusive litium och syre i sammansättningen. I den här rapporten var (MgCoNiZn)1-xLixO syntetiserad med en metod som heter Pechini med ett molbråk på x=0,35. En studie har visat potentialen i dem elektrokemiska beetenden av (MgCoNiZn)1-xLixO till applicering som en anode i ett litiumjon batteri.  Syntetiseringen började med ett uppvärmningsteg för att bränna bort alla organiska föreningar. Resulterade pulvret bestod av olika strukturer, och till ett kalcinerings steg för att lösa upp mellanfaserna till NaCL-struktur. Strukturen på pulvret hade en gitter constant på 4,138 Å. Pulvret gjordes till en slurry som innehåller amorft kol, PVDF och NMP för att sedan belägga elektroden med en Dr.Blade. Efter beläggningen har fått torka monterades cellen med litium som katod och 1M LiPF6 in 1:1 EC/DMC som elektrolyt. Tester utfördes på cellen med hjälp av en potentiostat medans cellen var förvaren i en klimatkammare i 25°C.  7 stycken cykler kördes för att plotta en cyklisk voltametri graf samt en urladdning-laddning prov utfördes. Cykliska voltametrin och urladdning-laddnings prov utfördes med ett spänningsintervall på 0,05-3,0V. Urladdning-laddnings provet hade en strömtäthet på 100 mA/g och en konstant ström på 42,68 mA.

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Catharanthine is derived from the Catharanthus roseus plant and is an analog to ibogaine, a drug that reduces opioid and alcohol withdrawal symptoms and decreases drug self-administration in both animals and humans. Catharanthine has promise to be an alternative pharmacological treatment for addiction without the adverse side effects associated with ibogaine. The objective of this study was to evaluate catharanthine’s effects on dopamine (DA) transmission in the mesolimbic DA system as well as determine its effects on both ethanol withdrawal induced anxiety and drug-seeking behaviors in mice. We hypothesized that catharanthine would inhibit evoked DA release in the nucleus accumbens (NAc) while also reducing anxiety and drug seeking behaviors in mice. We found that superfusion of catharanthine (1-100 µM) to mouse brain slices significantly inhibits evoked DA release in the NAc of the striatum in a dose dependent manner, while also slowing DA reuptake through inhibition of the dopamine transporter (DAT), measured using fast-scan cyclic voltammetry (FSCV). We also found that intraperitoneal administration of catharanthine in live mice significantly increases extracellular DA, measured via microdialysis with electrochemical detection. Catharanthine inhibition of evoked DA release was significantly reduced by the non-selective nAChR antagonist mecamylamine, the α4 nAChR antagonist dihydro-β-erythroidine hydrobromide (DhβE) and the α6 nAChR antagonist α-conotoxin MII, suggesting that catharanthine inhibits α4 and α6 nAChRs in the NAc. Iontophoresis and in-vivo data indicates that catharanthine slows DA reuptake and increases extracellular DA in the NAc through partial inhibition of DATs. Catharanthine also blocked increases in anxiety-like behavior during ethanol withdrawal in mice in the elevated plus maze. Lastly, preliminary data suggests that catharanthine increases both water and ethanol drinking in a 24-hour two-bottle choice drinking paradigm, which was contrary to our hypothesis.

Despite the increasing number of electrochemical and photoelectrochemical biosensors reported in the research literature, few have achieved success outside of a laboratory setting. This can partly be attributed to accessibility issues with commercially available readout instruments. Consequently, low-cost and portable readout instruments have been developed by researchers, but these devices fail to address other key compatibility and accessibility challenges. Much like the commercial systems, these devices are not natively compatible with multiplexed signal assays consisting of two or more working electrodes, cannot control optical excitation sources for photoelectrochemical biosensing, nor can they interface with auxiliary instruments such as heaters and electromagnets. To this end, we have developed a low-cost smartphone-operated electrochemical and photoelectrochemical readout system for point-of-care biosensing. Our readout system can perform standard voltammetric techniques and is capable of synchronously controlling an optical excitation source to support photoelectrochemical biosensing. This device is compatible with standard three-electrode assays as well as dual signal assays with two working electrodes. We have also created a portable sample heater that can be controlled by this readout system to facilitate on-site sample heating and have also integrated a portable electromagnet to perform away-from-lab magnetic manipulation. / Thesis / Master of Applied Science (MASc) / Early and prompt detection of disease biomarkers is crucial in order to develop effective disease management strategies. Unfortunately, many gold-standard diagnostic techniques for infectious diseases, cancers, heart diseases, among other conditions prove to be time-consuming, costly, and reliant on trained professionals in a laboratory setting. Electrochemical and photoelectrochemical detection are two sensing modalities that show promising potential for point-of-care applications, as they are easily miniaturized, inexpensive, and can be used to detect both the presence of and the amount of analyte present. However, up until now, these sensing modalities have mostly been confined to research settings. To expedite the commercialization of such sensors and to facilitate their translation to point-of-care diagnostics, we have developed a low-cost smartphone-operated electrochemical and photoelectrochemical readout system. Through the integration of peripheral instruments including a sample heater, electromagnet, and optical excitation source, this system is compatible with a number of different biosensors.

This dissertation describes the electrochemical behavior of nickel and iron that was studied in different acid solutions via linear sweep voltammetry, cyclic voltammetry, and potentiostatic measurements over a range of temperatures at specific potential ranges. The presented work displays novel experiments where a nickel electrode was heated locally with an inductive heating system, and a platinum (Pt) electrode was used to change the proton concentration at iron and nickel electrode surfaces to control the periodic oscillations (frequency and amplitude) produced and to gain a greater understanding of the systems (kinetics), oscillatory processes, and corrosion processes. Temperature pulse voltammetry, linear sweep voltammetry, and cyclic voltammetry were used for temperature calibration at different heating conditions. Several other metal systems (bismuth, lead, zinc, and silver) also produce periodic oscillations as corrosion occurs; however, creating these with pure metal electrodes is very expensive. In this work, metal systems were created via electrodeposition by using inexpensive, efficient, coupled microelectrode array sensors (CMASs) as a substrate. CMASs are integrated devices with multiple electrodes that are connected externally in a circuit in which all of the electrodes have the same amount of potential applied or current passing through them. CMASs have been used for many years to study different forms of corrosion (crevice corrosion, pitting corrosion, intergranular corrosion, and galvanic corrosion), and they are beneficial because they can simulate single electrodes of the same size. The presented work also demonstrates how to construct CMASs and shows that the unique phenomena of periodic oscillations that can be created and studied by using coated and bare copper CMASs. Furthermore, these systems can be controlled by implementing external forcing with a Pt electrode at the CMAS surface. The data from the single Ni electrode experiments and CMAS experiments were analyzed by using the Nonlinear Time-Series Analysis approach.

No description available.

No description available.