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Articles 1 - 30 of 55
Full-Text Articles in Analytical Chemistry
Stability Of Paraffin-Insulated Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Maxwell H. Kwakwah
Stability Of Paraffin-Insulated Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Maxwell H. Kwakwah
Electronic Theses and Dissertations
Nitrogen-doped carbon materials can facilitate the reduction oxygen-oxygen bonds, a key step in electroreduction of both O2 (an important reaction in energy applications) and H₂O₂ (an important reaction in sensing and biosensing). Our lab previously demonstrated that thermal decomposition of urea in the presence of carbon fiber (CF) results in an N-doped carbon material that exhibits good electrocatalytic properties for H₂O₂ reduction. However, previous methods of insulating single N-doped CF via laser heating of borosilicate capillaries and epoxy to prepare ultramicroelectrodes (UMEs) seemed to adversely affect surface nitrogen contents and electrocatalytic properties. More recent work that utilized paraffin to …
Electrochemical And Electrocatalytic Properties Of Screen-Printable Carbon Inks Featuring Pyridinic Nitrogen-Containing Polymeric Binder, Albert Sam Junior
Electrochemical And Electrocatalytic Properties Of Screen-Printable Carbon Inks Featuring Pyridinic Nitrogen-Containing Polymeric Binder, Albert Sam Junior
Electronic Theses and Dissertations
Screen-printable conductive inks have been widely applied to prepare electrodes for electrochemical sensing. These inks generally consist of conductive metal or carbon particles, solvents, and polymeric binders. Low-cost, carbon-based, screen-printable conductive inks are especially popular. However, screen-printed carbon electrodes (SPCEs) must often be modified after they are printed to impart the necessary characteristics (e.g., sensitivity, selectivity, stability) for the desired application. For example, nitrogen-doping of SPCEs, especially in ways that introduce pyridinic or pyrrolic nitrogen species, can impart electrocatalytic properties towards reduction of O2, H2O2, and CO2. While our previous work done …
Kinetic Analysis Of Hydrolysis And Hydrothermal Conversion Of Methyl Cellulose To Dodecane, Joseph Olembo Were
Kinetic Analysis Of Hydrolysis And Hydrothermal Conversion Of Methyl Cellulose To Dodecane, Joseph Olembo Were
Electronic Theses and Dissertations
Environmental pollution due to emission of greenhouse gases and increasing global energy demand are some of the concerns associated Analysis with the use of fossil fuels. These concerns have triggered the exploration of sustainable and efficient methods for renewable energy production. One such method is the conversion of cellulosic biomass to hydrocarbon fuels using hydrogen bronze metals. Cellulose is the most abundant biomass globally, and thus its utilization can lead to more sustainable energy production. Previous studies have reported the conversion of cellulose to hydrocarbons at high temperatures and hydrogen pressure. This work focuses on the conversion of methyl cellulose …
A Kinetic Analysis On Hydrolysis And Hydrothermal Conversion Of Cellulose To Dodecane, Joel Nyangoka Onyancha
A Kinetic Analysis On Hydrolysis And Hydrothermal Conversion Of Cellulose To Dodecane, Joel Nyangoka Onyancha
Electronic Theses and Dissertations
Cellulose, the most abundant biomass on Earth, offers a promising pathway for alternative energy through conversion into alkane hydrocarbons. Traditional methods rely on high temperatures and high-pressure hydrogen, often derived from petroleum. In this study, we investigated the conversion of Microcrystalline Cellulose using hydrogen metal oxides (bronzes) under milder conditions. Following ASTM E3417-24 hydrolysis protocols, we employed hydrogen bronzes with toluene for product extraction. This approach enabled conversion at lower temperatures without pressurized hydrogen. Products were analyzed using Gas Chromatography Mass Spectrometer for identification and Gas Chromatography Flame Ionization Detector for quantification. Our findings revealed the formation of a possible …
Electrocatalytic Reduction Of Hydrogen Peroxide At Paraffin-Sealed Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Yakubu Gausu Mohammed
Electrocatalytic Reduction Of Hydrogen Peroxide At Paraffin-Sealed Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Yakubu Gausu Mohammed
Electronic Theses and Dissertations
Compared to unmodified carbons and even some metal materials, nitrogen-doped carbons have been found to exhibit better performance for reducing oxygen-oxygen bonds, a key step in electroreduction of both O2 (an important reaction in energy applications) and H2O2 (an important reaction in sensing and biosensing). Previous studies from our lab revealed that thermal decomposition of urea in the presence of carbon fiber (CF) results in N-doped that exhibited good electrocatalytic properties for H2O2 reduction. However, previous methods of sealing ultramicroelectrodes (UMEs) made from N-doped CF using laser heating of borosilicate capillaries and epoxy …
Electrochemiluminescence Using Pencil Graphite Electrodes And Screen-Printed Carbon Electrodes Interfaced With A Simple Imaging System, Sandra Ehigiator
Electrochemiluminescence Using Pencil Graphite Electrodes And Screen-Printed Carbon Electrodes Interfaced With A Simple Imaging System, Sandra Ehigiator
Electronic Theses and Dissertations
Electrochemiluminescence (ECL) is a phenomenon whereby electrochemical reactions generate a product that is capable of emitting light. ECL’s high sensitivity, selectivity, extremely low background, and relatively simple instrumentation make it particularly well-suited for chemical sensing and biosensing strategies. Here we report a simple ECL imaging system based on a camera interfaced with a zoom lens to compare pencil graphite electrode (PGE) and screen-printed carbon electrode (SPCE) arrays as ECL platforms. With this system, ECL signals generated from tris(2,2′- bipyridine)ruthenium(II) chloride hexahydrate ([Ru(bpy)3]2+) using co-reactant tri-n-propylamine (TPA) were linear with respect to [Ru(bpy)3]2+ concentrations from 9 to 450 μM. Detection limits …
A Low Cost, Compact Electrochemical Analyzer Based On An Open-Source Microcontroller, Michael Kofi Darko Addo
A Low Cost, Compact Electrochemical Analyzer Based On An Open-Source Microcontroller, Michael Kofi Darko Addo
Electronic Theses and Dissertations
Compared to other instruments for chemical analyses, electrochemical analyzers are relatively simple, inexpensive, easy to miniaturize and require little-to-no maintenance. However, like all commercially available instruments, commercial electrochemical analyzers like potentiostats primarily operate as black boxes with manufacturers providing little or no information about internal circuitry and programming. This practice can limit a researcher’s ability to develop new techniques or adapt an instrument for applications outside its typical use. In contrast, creators of open-source instruments release all the necessary information for reproduction of the hardware and software – minimizing such barriers to innovation in chemical analyses. Here, we report a …
Synthesis Of A Phenyl Substituted Zinc Dipyrrin Complex For The Purpose Of Analyzing Aromatic Substitutions On The Characteristics Of Compounds Of This Class, Kole Owen
Undergraduate Honors Theses
The field of photochemistry is as innovative in development as it is broad in application. However, utilization of energy from the sun’s electromagnetic radiation remains secondary to the combustion of fossil fuels for the global energy consumption. This is neither a sustainable nor renewable system, and it has contributed to a major decline in the health of our global environment as the greenhouse gases emission has led to an incline in global temperatures and ocean acidity. To develop effective ways to utilize solar energy, experimental effort is being directed towards the understanding of photosensitizers, molecules which absorb solar radiation and …
Non-Destructive Imaging Of Phytosulfokine Trafficking In Plants Using Fiber-Optic Fluorescence Microscopy, Bernard Abakah
Non-Destructive Imaging Of Phytosulfokine Trafficking In Plants Using Fiber-Optic Fluorescence Microscopy, Bernard Abakah
Electronic Theses and Dissertations
Plants secrete peptide ligands and use receptor signaling to respond to stress and control development. Understanding these phenomena is key to improving plant health and productivity for food, fiber, and energy applications. Phytosulfokine (PSK), a sulfated peptide hormone, regulates plant cell division, growth, and stress tolerance via specific phytosulfokine receptors (PSKRs). This study uses fiber-optic fluorescence microscopy to elucidate trafficking of PSK in live plants. The microscope features two-color optics and an objective lens connected to a 1-m coherent imaging fiber mounted on either a conventional upright microscope body or 5-axis positioning system (X–Y–Z plus pitch and yaw). PSK and …
Nitrogen-Doped And Phosphorus-Doped Epoxy-Sealed Carbon Fiber Ultramicroelectrodes As Electrochemical Sensors For Detection Of Hydrogen Peroxide, Emmanuel Peprah-Yamoah
Nitrogen-Doped And Phosphorus-Doped Epoxy-Sealed Carbon Fiber Ultramicroelectrodes As Electrochemical Sensors For Detection Of Hydrogen Peroxide, Emmanuel Peprah-Yamoah
Electronic Theses and Dissertations
Ultramicroelectrodes (UMEs) are useful as probes for evaluating electroactive species in confined spaces (e.g., inside living cells) and for measuring fast electrochemical reactions. However, UME applications often require modification of the electrode surface to improve selectivity and sensitivity towards target analytes. Previous research in our group demonstrated that a simple soft nitriding method introduces surface nitrogen (N)-containing groups on carbon fiber (CF), leading to improved electroreduction of hydrogen peroxide (H2O2) on CF-UMEs. However, sensitivity for H2O2 detection using N-CF-UMEs was low compared to that for other modified UMEs. As an alternative to N-CF-UMEs, …
Nitrogen Doping Of Electrochemically Activate Carbon Screen-Printed Electrodes, Ethan Galloway
Nitrogen Doping Of Electrochemically Activate Carbon Screen-Printed Electrodes, Ethan Galloway
Undergraduate Honors Theses
Screen printed electrodes (SPEs), which are prepared by patterning conductive inks or pastes onto an insulating support (e.g., plastic film), are widely employed as sensing and biosensing platforms due to their ease of fabrication and relatively low cost. This is especially applicable to electrodes of this nature prepared with carbon-based inks (SPCEs). To date, the most successful and significant commercial application of SPEs has been as test strips for glucose meters. Despite the maturity of this technology, SPE research remains very active as improvements in sensitivity and selectivity, which often involve modifying the electrode surface, hold the key to advancing …
Facile Nitrogen-Doping Of Screen-Printed Carbon Electrodes For Detection Of Hydrogen Peroxide, Emmanuel Nkyaagye
Facile Nitrogen-Doping Of Screen-Printed Carbon Electrodes For Detection Of Hydrogen Peroxide, Emmanuel Nkyaagye
Electronic Theses and Dissertations
Screen-printed carbon electrodes (SPCEs) have garnered much attention as sensors due to their simplicity and relatively low cost. However, to impart necessary selectivity and sensitivity for specific applications, modification of the SPCE surface, which can involve time-consuming procedures or costly equipment/materials, is typically required. Here, a simple nitrogen-doping process based on NH4OH was used to modify SPCEs prepared from commercially available ink for electrochemical detection of H2O2, a common target for biosensing strategies and indicator of cell stress. XPS studies showed that NH4OH treatment of SPCEs led to a nearly 5-fold increase …
Nitrogen-Doped Carbon Fiber Ultramicroelectrodes As Electrochemical Sensors For Detection Of Hydrogen Peroxide, Eric Wornyo
Nitrogen-Doped Carbon Fiber Ultramicroelectrodes As Electrochemical Sensors For Detection Of Hydrogen Peroxide, Eric Wornyo
Electronic Theses and Dissertations
Carbon fiber ultramicroelectrodes (CF-UMEs) are commonly used as electrochemical probes and sensors due to their small size, fast response, and high signal-to-noise ratio. Surface modification strategies are often employed on CF-UMEs to improve their selectivity and sensitivity for desired applications. However, many modification methods are cumbersome and require expensive equipment. In this study, a simple approach known as soft nitriding is used to prepare nitrogen-doped CF-UMEs (N-CF-UMEs). Nitrogen groups introduced via soft nitriding act as electrocatalytic sites for the breakage of O-O bonds during the reduction of peroxides like H2O2, a common target of biosensing strategies. …
An Electrochemical Immunoassay System For Measuring Circulating Protein Biomarkers Of Pediatric Soft Tissue Sarcoma, Ivy Antwi
Electronic Theses and Dissertations
Measurement of circulating protein biomarkers associated with disease can facilitate early detection, help guide treatment strategies and improve patient outcomes beyond current standards of care. The combination of inexpensive 3D-printed flow cells and electrochemical biosensors has recently emerged as a viable platform for low-cost, reliable biomarker measurements. Here, we report an electrochemical immunoassay system based on simple graphite electrode arrays, 3D-printed flow cells, and signal-generating magnetic bead bioconjugates for simultaneous detection of three biomarker proteins (cancer antigen 125 (CA-125), midkine (MK) and osteopontin (OPN)) associated with pediatric soft tissue sarcomas (PSTS). Magnetic bead bioconjugates are functionalized with large amounts of …
Kinetics For Enzymatic Conversion Of Biomass To Glucose, Jordan Broadwater
Kinetics For Enzymatic Conversion Of Biomass To Glucose, Jordan Broadwater
Undergraduate Honors Theses
Biofuels are a sought-after alternative for fossil fuels in today’s society. More specifically, cellulose-based biofuel is an avenue of research intending to limit waste and provide new renewable energy. Cellulose is a rigid polymer of glucose monomers that is found abundantly across different agriculture crops. However, its stability is a barrier to energy production from this source. Pretreatment followed by hydrolysis of cellulosic materials serves a potential to produce glucose to be used in biofuels in larger quantities compared to other methods. This project studied the effect microwave pretreatment and oxygenation have on hydrolysis of cellulose in Arundo Donax. Arundo …
Electrodeposition Of Hydrogen Molybdenum Tungsten Bronze Films And Electrochemical Reduction Of Carbon Dioxide., Mohammad Bajunaid
Electrodeposition Of Hydrogen Molybdenum Tungsten Bronze Films And Electrochemical Reduction Of Carbon Dioxide., Mohammad Bajunaid
Electronic Theses and Dissertations
The foremost aim for performing this study was to focus on the electrodeposition of mixed hydrogen molybdenum tungsten bronze films, which have the potential for e– transfer interactions carrying out the reduction of carbon dioxide. A yellow peroxymolybdic tungstate solution was prepared and used for the electrodeposition of hydrogen molybdenum tungsten bronze films on conductive carbon paper. Electrodeposition was carried out at -2.0 V from 20 - 120 minutes to determine the effect of deposition time on film thickness and CO2 reduction. These films were characterized by X-ray photoelectron spectroscopy. The deposited films served as a working electrode …
Theranostic Nanoparticles Folic Acid-Carbon Dots-Drug(S) For Cancer, Godwin Kweku Babanyinah
Theranostic Nanoparticles Folic Acid-Carbon Dots-Drug(S) For Cancer, Godwin Kweku Babanyinah
Electronic Theses and Dissertations
This study aims to prepare theranostic nanoparticles (NPs) that are expected to increase cancer diagnostics and therapeutic efficacy. We prepared the NPs constituting carbon dots (CDs) as an imaging agent, folic acid as a targeting agent, doxorubicin (DOX), or gemcitabine (GEM) as chemotherapy agents. The NPs include noncovalent FA-CDs-DOX, covalent CDs-FA-DOX, and covalent FA-CDs-GEM. Through ultraviolet-visible spectroscopy, fluorescence spectroscopy, and Fourier transform-infrared spectroscopy, the fabrication of these NPs was confirmed. It was discovered that the high drug loading efficiency is the noncovalent series while the high drug loading capacity is the covalent series The in-vitro pH-dependent drug release data indicate …
Heteroatom-Doped Chemical Vapor Deposition Carbon Ultramicroelectrodes, Alexis Sanwick
Heteroatom-Doped Chemical Vapor Deposition Carbon Ultramicroelectrodes, Alexis Sanwick
Undergraduate Honors Theses
Metal nanoparticles have been a primary focus in areas of catalysis and electrocatalysis applications as a result of their large surface area-to-volume ratios. While there is an increased interest in understanding the properties and behaviors of metal nanoparticles, they can become expensive over time. Recent research has incorporated the idea of using heteroatom-doped materials as a cheaper catalytic alternative to metal nanoparticles. In this study nitrogen-doping and phosphorous-doping techniques were applied to chemical vapor-deposited carbon ultramicroelectrodes in order to study the electrocatalytic properties toward the oxygen reduction reaction and the enhanced affinity for the deposition of gold nanoparticles onto the …
Structure Elucidation Of A Pyrrolobenzodiazepine Alkaloid And A Biologically Active Polyketide Produced By Rhodococcus Sp. Mtm3w5.2 Via Two-Dimensional Nmr Spectroscopy, Garrett Johnson
Electronic Theses and Dissertations
As the battle against ever-increasing drug resistence bacteria rages on, novel and sometimes more complex natural products can be used to combat this. In this study, two-dimensional NMR techniques were utilized to collect a complete spectral data set for two natural products. The first structure, a synthesized Pyrrolobenzodiazepine alkaloid natural product was confirmed through these methods. The second, a strain of Rhodococcus, MTM3W5.2, produces a novel antibacterial molecule in broth cultures and the active compound was fractionated using a Sephedex LH-20 column. Chromatographic purification yielded a pure sample at 58.90 minutes, RT.58. HRMS data deduced an exact mass of …
Electrodeposition Of Hydrogen Molybdenum Bronze Films And Electrochemical Reduction Of Carbon Dioxide At Low Over Potentials, Sami Alharbi
Electrodeposition Of Hydrogen Molybdenum Bronze Films And Electrochemical Reduction Of Carbon Dioxide At Low Over Potentials, Sami Alharbi
Electronic Theses and Dissertations
Hydrogen molybdenum oxide, known has molybdenum bronze, is a material of interest due to catalyzing electron transfer reactions. Specifically, molybdenum bronze is an electrocatalyst toward carbon dioxide reduction. Electrochemical deposition from a peroxymolybdic acid solution is a method for preparing molybdenum bronze films. This work demonstrates reproducible electrodeposition on indium tin oxide substrates and conductive carbon paper. Film thickness depends on concentration, time and pH. After characterization by film thickness, resistance, XRD and XPS, the as deposited films served as the working electrode for electrochemical reduction of carbon dioxide in 0.1 M NaHCO3. Ion chromatography determined formate resulting …
Modification Of Chemical Vapor-Deposited Carbon Electrodes With Electrocatalytic Metal Nanoparticles Through A Soft Nitriding Technique, Enoch Amoah
Electronic Theses and Dissertations
Metal nanoparticles have been widely used for many catalytic and electrocatalytic applications due to their larger surface area-to-volume ratios and higher densities of active sites compared to bulk materials. This has resulted in much interest in understanding the electrocatalytic behavior of metal nanoparticles with respect to their structure. However, most research on this topic has employed collections of nanoparticles. Due to difficulties in controlling and characterizing particle loading and interparticle distance in nanoparticle ensembles, single nanoparticles studies have recently become a topic of great interest. In this study, a soft nitriding technique was applied to chemical vapor-deposited carbon ultramicroelectrodes (UMEs) …
Peroxide Sensing Using Nitrogen-Doped And Platinum Nanoparticle-Modified Screen-Printed Carbon Electrodes, Chidiebere Ogbu
Peroxide Sensing Using Nitrogen-Doped And Platinum Nanoparticle-Modified Screen-Printed Carbon Electrodes, Chidiebere Ogbu
Electronic Theses and Dissertations
Nitrogen-doped carbon materials have garnered much interest due to their abilities to behave as electrocatalysts for reactions important in energy production (oxygen reduction) and biosensing (hydrogen peroxide reduction). Here, we demonstrate fabrication methods and determine electrocatalytic properties of nitrogen-doped screen-printed carbon (N-SPCE) electrodes. Nitrogen doping of graphite was achieved through a simple soft-nitriding technique which was then used in lab-formulated screen-printing inks to prepare N-SPCEs. N-SPCEs displayed good electrocatalytic activity, reproducibility and long term stability towards the electrochemical reduction of hydrogen peroxide. N-SPCEs exhibited a wide linear range (20 µM to 5.3 mM), reasonable limit of detection of 2.5 µM, …
Immobilization Of Electrocatalytically Active Gold Nanoparticles On Nitrogen-Doped Carbon Fiber Electrodes, Daniel Mawudoku
Immobilization Of Electrocatalytically Active Gold Nanoparticles On Nitrogen-Doped Carbon Fiber Electrodes, Daniel Mawudoku
Electronic Theses and Dissertations
Studies of single, isolated nanoparticles provide better understanding of the structure-function relationship of nanoparticles since they avoid complications like interparticle distance and nanoparticle loading that are typically associated with collections of nanoparticles distributed on electrode supports. However, interpretation of results obtained from single nanoparticle immobilization studies can be difficult to interpret since the underlying nanoelectrode platform can contribute to the measured current, or the immobilization technique can adversely affect electron transfer. Here, we immobilized ligand-free gold nanoparticles on relatively electrocatalytically inert nitrogen-doped carbon ultramicroelectrodes that were prepared via a soft nitriding method. Sizes of the particles were estimated by a …
Gas Chromatography Analysis Of Co2 Reduction Photocatalysis With Zinc Dipyrrin Complexes, Alex Day
Gas Chromatography Analysis Of Co2 Reduction Photocatalysis With Zinc Dipyrrin Complexes, Alex Day
Undergraduate Honors Theses
Bis(1,3,7,9-tetramethyl-5-mesityldipyrrinato)zinc(II) (ZnDPY) was synthesized in the lab by the McCusker group and a procedure was created to analyze its ability as a photosensitizer, a molecule that provides the energy for the reaction to occur by capturing light energy and turning it into a form that can be used by the photocatalyst. While more work is needed, preliminary steps have been made to create a process that can analyze the amount of carbon monoxide produced by a photocatalytic CO2 reduction reaction with ZnDPY as the photosensitizer. Progress has been made via the setup of a reaction apparatus, targeted gas chromatography …
Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, Esther Alorkpa
Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, Esther Alorkpa
Electronic Theses and Dissertations
A study was conducted on sol-gel synthesis of an adsorbent (phosphotungstic acid embedded in silica gel, H-PTA/SiO2) of radioactive cesium. A novelty of this work is covalent bonding of PTA to the surface of solid support that prevents leaching from the surface of the material. The sample was granulated with a binder, aluminium oxide (γ-Al2O3). Solid-state NMR and FT-IR spectroscopy were used to confirm the presence of Keggin units of PTA in the bound materials. Thermal analysis of H-PTA/SiO2 - γ-Al2O3 (50 %) showed that the water content in the …
Relative Permittivity As A Function Of Co-Solvent And Impedance Spectroscopy For Quantifying Anions In Solution, Yahya Sami Alseiha
Relative Permittivity As A Function Of Co-Solvent And Impedance Spectroscopy For Quantifying Anions In Solution, Yahya Sami Alseiha
Electronic Theses and Dissertations
This work measured relative permittivity from 15.0 to 55.0 °C of aqueous solutions containing acetone or tetrahydrofuran using a BI 870 dielectric meter. A cubic polynomial fit resulted in coefficients for calculating permittivity as a function of temperature and mole fraction. Literature values for other co-solvent system resulted in similar polynomial coefficients. Using BI 870, permittivity measurements of ionic solutions were not possible because of high conductivity. A simple method using impedance spectroscopy measured these solutions. Impedance decreases with increasing temperature and decreases with increasing ionic strength. Due to the temperature dependence of impedance, all measurements were at 25.0 °C. …
Immobilization Of Gold Nanoparticles On Nitrided Carbon Fiber Ultramicroelectrodes By Direct Reduction, George Affadu-Danful
Immobilization Of Gold Nanoparticles On Nitrided Carbon Fiber Ultramicroelectrodes By Direct Reduction, George Affadu-Danful
Electronic Theses and Dissertations
Due to enhanced properties such as large surface area-to-volume ratio, metal nanoparticles are often employed as catalysts for various applications. However, most studies involving nanoparticle catalysts have been conducted on collections of particles rather than single nanoparticles. Results obtained for ensemble systems can be difficult to interpret due to variations in particle loading and interparticle distance, which are often challenging to control and characterize. In this study, two immobilization strategies for incorporating gold nanoparticles (AuNPs) on carbon fiber ultramicroelectrodes (UMEs) were compared with the goal of extending these techniques to nanoelectrodes for studies of single AuNPs. Both layer-by-layer deposition of …
Comparing Laser Assisted Pulling And Chemical Vapor Deposition Methods In The Fabrication Of Carbon Ultramicro- And Nanoelectrodes, Theophilus Neequaye
Comparing Laser Assisted Pulling And Chemical Vapor Deposition Methods In The Fabrication Of Carbon Ultramicro- And Nanoelectrodes, Theophilus Neequaye
Electronic Theses and Dissertations
Ultramicroelectrodes (UMEs) (limiting dimensions <~25 μm) and nanoelectrodes (<~100 nm) exhibit enhanced electrochemical properties compared to macroscopic electrodes. Their small sizes and enhanced properties make them well-suited for various interesting and important applications such as measuring redox-active species in nonaqueous solvents, studying intermediates of fast electrochemical reactions, and investigating electrochemical and electrocatalytic properties of single nanoparticles. While UMEs are commercially available, nanoelectrode fabrication is still largely confined to research labs. Various methods for constructing nanoelectrodes have been reported and continue to be developed, but most require considerable expertise, and comparisons between different fabrication processes are lacking. In this work, a comparison of laser-assisted pulling and chemical vapor deposition (CVD) methods of electrode fabrication is made with the aim of optimizing production of carbon nanoelectrodes for single nanoparticle electrochemical measurements. By examining effects of pulling parameters, post-pulling treatments, and CVD processing, electrodes as small as ~50 nm were successfully produced.
Hydrolysis Of Cellulose And Biomass Using Blue Molybdenum, Farouk Awudu
Hydrolysis Of Cellulose And Biomass Using Blue Molybdenum, Farouk Awudu
Electronic Theses and Dissertations
Hydrolysis of cellulosic biomass is an important and ongoing subject of research due to generating precursors for biofuel synthesis. This work involves hydrolysis of microcrystalline cellulose and Arundo donax to glucose. Methods for acid hydrolysis include the use of sulfuric acid, phosphomolybdic acid, blue molybdenum using low concentrations at 40-100 °C. For comparison purposes, enzymatic hydrolysis was also carried out using cellulase. Products were quantified by measuring total organic carbon and reducible sugars using dinitrosalicylic acid. Use of phosphomolybdic acid, blue molybdenum and sulfuric acid even at 6.0 M did not increase the amount of glucose compared to using water …
3d-Printed Fluidic Devices And Incorporated Graphite Electrodes For Electrochemical Immunoassay Of Biomarker Proteins, Abdulhameed Alabdulwaheed
3d-Printed Fluidic Devices And Incorporated Graphite Electrodes For Electrochemical Immunoassay Of Biomarker Proteins, Abdulhameed Alabdulwaheed
Electronic Theses and Dissertations
Biomarkers are measurable indicators of health status or disease state that can be used for diagnosis and may help guide patient treatment strategies. Enzyme-linked immunosorbent assays (ELISA) and other many clinical techniques currently used for measuring biomarker proteins lack sensitivity, demand high analysis cost, are often not well-suited for measuring multiple biomarkers in a single sample, and require long analysis times. Here, we demonstrate simple, low-cost 3D-printed flow-through devices with integrated electrodes modified with gold nanoparticles (AuNPs) for electrochemical immunoassays of S100B, a biomarker protein related to conditions like skin cancer and brain injuries. Flow-through devices are fabricated from photocurable-resin …