Chemistry Commons^™

Fabrication Of Metal-Silicon Nanostructures By Reactive Laser Ablation In Liquid, Eric J. Broadhead

Theses and Dissertations

Metal-silicon nanostructures are a growing area of research due to their applications in multiple fields such as biosensing and catalysis. In addition, silicon can provide strong support effects to metal nanoparticles while being more cost effective than traditionally used supports, like titania. Traditional wet-chemical methods are capable of synthesizing metal-silicon nanostructures with a variety of composition and nanoparticle shapes, but they often require high temperatures, toxic solvents, strong reducing agents, or need capping agents added to stabilize the nanoparticles. Laser processing is an emerging technique capable of synthesizing metal-silicon composite surfaces that offers a faster, simpler, and greener synthesis route …

The Rational Synthesis Of Lanthanum Manganite Nanomaterials For Magnetic Refrigeration Applications, Caitlin Hunt

Theses and Dissertations

Refrigeration systems for the cooling of commercial and residential buildings are a major drain on energy resources and source of greenhouse gas emissions. Magnetic refrigeration, which employs the magnetocaloric effect, has the potential to mitigate the energy drain and greenhouse gas emissions for air conditioning. In order to commercialize magnetic refrigerators, a material with a high magnetic entropy change, ΔS, near room temperature which is simple and inexpensive to create is needed.¹ Current options for this solid refrigerant are either expensive, difficult to synthesize, or have a ΔS or T_c (the Curie Temperature, where ΔS is maximized) below …

Strategies For Resolution Enhancement In Liquid Chromatography, Shelby Lynn Weatherbee

Theses and Dissertations

Recent research in liquid chromatography (LC) has led to the development of new methodologies to further improve sample analysis. Non-uniform stationary phases are one such area that focuses on developments in selectivity and efficiency of stationary phases. Within this subset of stationary phases are two major focuses: two-dimensional liquid chromatography (2D-LC) and continuous stationary phase gradients that are the basis of this work.

In this work, LC simulation software was adapted to simulate chromatograms based on experimental and modeled injection profiles. This was done by measuring the injection profiles from a 2D-LC active solvent modulation valve using a variety of …

The Dmap-Catalyzed Acylation Of Alcohol -- A Mechanistic Study, Tania Veronica Alvarez Castro

Theses and Dissertations

The mechanistic studies of Acylation of Alcohols catalyzed by 4-(N,N- Dimethyl-amino)-pyridine (DMAP) has been heavily studied in the literature. This reaction has attracted considerable interest from the synthetic and mechanistic points of view in recent years. In this research, the acylation of alcohols is prepared from cyclohexanol and acetic anhydride that is catalyzed by DMAP using triethyl amine (NEt3) as the auxiliary base and dichloromethane (DCM) as solvent. The reaction and final product will be analyzed by using gas chromatography (GC) and reaction progress kinetic analysis (RPKA). The mechanistic insights obtained in the present study should be useful for understanding …

Chemical Investigation Of Avocado (Persea Americana) Seed Husk (Testa): A Waste Of Waste, Orlando A. Castillo Scheren

Theses and Dissertations

Food chemistry is a new field in the world and is currently still expanding into the types of market in which it can be tapped into. There are about 1.3 billion tons of food waste produced in 2016 in the world, and food chemistry is going to help get rid of that waste by finding new and exciting applications to the things currently considered as waste. In these products, there might be new and undiscovered drugs that can be used in the market to help treat diseases for which might not have a cure at the current moment. The avocado …

Synthesis, Characterization, And Application Of Meso-Tetraphenyl Metalloporphyrin Photocatalysts Under Visible Light, Alexis Echavarria

Theses and Dissertations

The photocatalytic activity of meso-Tetraphenyl Metalloporphyrins with different metal centers was investigated. The synthesized metalloporphyrin photocatalysts was performed and analyzed using FT-IR spectroscopy, UV-VIS spectroscopy, and powder X-Ray Diffraction analysis. The synthesized TPP crystals were determined to be tetragonal crystal structure and the structure was observed in all synthesized metalloporphyrin catalysts. The Soret (B) bands, Q bands, FT-IR functional groups were identified. Reaction progress was investigated by sampling at intervals of one hour and analysis of the samples was performed using Gas Chromatography-Mass Spectrometry. GC-MS analysis was used to identify the products of the photochemical catalytic redox reactions performed under …

Thermal And Spectroscopic Investigations On Polymer-Based Nanofibers, Omosola Oriretan

Theses and Dissertations

Nanofibers of Poly (ethylene oxide), PEO, Poly (vinylpyrrolidone) PVP, Co-nanofiber of PEO-PVP and PEO nanocomposite of various Fullerene compositions were prepared by dissolving PEO, PVP and Fullerene in water. The Fullerene nanoparticles were added to the PEO solutions, the mixtures were homogenized under high power sonication. The PEO solutions, PVP solutions, the co-polymer solutions of PEO-PVP and the PEO -Fullerene solutions were centrifugally spun using Force spinning™ machine. The obtained nanofibers and the nanocomposites were subjected to FTIR analysis, Raman analysis and various heating and cooling cycles with heating and cooling rates ranging from 10C/min to 600C/min using differential scanning …

Chemical Modification And In Silico Validation Of Medicinally Privileged Molecular Scaffolds As Kras And Sars-Cov-2 Protease Inhibitors, Precious M. Okwuchukwu

Theses and Dissertations

Coronavirus disease was declared a global pandemic by WHO in March 2020, cancer is the second leading cause of death by a disease. Several scientists around the world are working relentlessly to discover an effective remedy to eradicate these deadly diseases. A natural polyphenol (magnolol) has been isolated from a tree Magnolia grandiflora (family Magnoliaceae) found on UTRGV campuses. This research is focused on design of a series of chemically modified sulfonyl derivatives based on the isolated magnolol framework and other medicinally privileged molecular scaffolds framework that can effectively bind to the COVID-19 main protease, SARS- CoV-2 3CL protease …

Total Synthesis Of Cytotoxic Mansouramycins From Amino Acids, Beatriz Gamez

Theses and Dissertations

Natural products produced by plants, animals, and microorganisms are of significant importance in chemistry for being major sources of molecular scaffolds essential for new drug discovery. Mansouramycins are cytotoxic bioactive compounds containing isoquinoline skeletons with substituents on the quinone and pyridine rings that may be difficult to synthesize. Synthetic processes exist for compounds B and D, however, there exists an absence of simple synthetic approaches to all four alkaloids.

This project aims to provide a general total synthetic pathway to Mansouramycins A—D from amino acids for possible use in cancer treatment via these isoquinolinequinones. Preliminary experimentation suggests there may be …

Polymer-Based Capacitive Gas Sensor For Machine Olfaction, Mohamed Fathy Hassan

Theses and Dissertations

Transferring human abilities and knowledge to machines has been the focus of decades of work by scientists and engineers. With the progress in computation power and algorithms such as artificial neural networks, machines have surpassed humans in complicated games like chess and the Chinese game Go. Some senses can be mimicked including touch, with pressure sensors, hearing, with microphones, and vision with charged couple device (CCD)imaging chips. Yet, relatively little progress has been made with the senses of smell and taste. Machine olfaction, the ability to detect and quantify vapors in the environment, poses a range of challenges, which if …

Development And Characterization Of Robust Methods For Field Investigations With Portable Mass Spectrometry, Ashley Rose Stelmack

Theses and Dissertations

Portable mass spectrometry (MS) has become an area of interest due to the ability to conduct chemical analyses in native environments. These instruments have the potential to increase efficiency and analytical throughput via real-time experimentation, minimizing the need for sample transportation. One drive towards the development of fieldable mass spectrometers is the potential for coupling to novel ambient ionization methods (or “ambient MS”), which can generate spectral data at ambient conditions from unprepared or minimally prepared samples of interest. Since the first introduction of the desorption electrospray ionization (DESI) technique in 2004, a myriad of novel techniques have been reported …

Measurements Of Rate Exchange Dynamics In Supercooled Ortho-Terphenyl By Single-Molecule 3d Kinetics And Green’S Functions, Harveen Kaur

Theses and Dissertations

Heterogeneity in relaxation rates is a well-established feature of supercooled liquids. It implies the existence of a rate-exchange process to restore ergodicity, but the experimental characterization of that exchange has been incomplete and controversial. This dissertation develops three-dimensional (3D) correlation functions that provide a well-defined measure of rate exchange from single-molecule measurements. This approach is demonstrated on both single-molecule dichroism measurements and atomistic simulations of molecular rotation in ortho-terphenyl.

The first project develops non-parametric analysis of nonexponential and multidimensional kinetics. The quantification of nonexponential (dispersed) kinetics has relied on empirical functions, which yield parameters that are neither unique nor easily …

Synthesis And Design Of Novel Polymer Grafted Nanoparticles Relevant To Drug Delivery Vehicles For Biomedical Applications, Maan Abduldiyem Hassan Al-Ali

Theses and Dissertations

The modification of inorganic nanoparticles with organic polymer chains has become a significant field of study for the engineering of advanced nanocomposite materials. This dissertation presents the design, synthesis, and characterization of novel polymer grafted silica nanoparticles as new strategies to combat bacterial resistance. Described herein is the synthesis of monomers that have been graft polymerized onto silica nanoparticles that can be used as a delivery drug vehicle for biomedical applications. The polymerization of these monomers was performed via reversible addition-fragmentation chain transfer (RAFT) polymerization. The molecular design of the RAFT agents that are attached to the surfaces of the …

A Novel Analytical Method For Studying Pharmacological Treatments For Affective Disorders In Neuroscience, Shane N. Berger

Theses and Dissertations

Histamine and serotonin are important neurochemicals that maintain crucial brain functions. Both are thought to be altered in affective and neurodegenerative disorders such as depression and Parkinson’s disease. Histamine and serotonin are thought to modulate one another but the exact relationship remains unknown and this gap in knowledge makes diagnosing and treating disorders involving the transmitters difficult. The Hashemi lab studies serotonin neurochemistry to understand serotonin’s role in psychiatric disorders. However, histamine has remained an understudied neurotransmitter due to a lack of analytical tools. In 2015 and 2016, the Hashemi lab pioneered a novel detection method utilizing fast-scan cyclic voltammetry …

Aqueous Kinetics Of Α-Hydroxyhippuric Acid Derivatives Bearing Electron-Withdrawing Groups As A Function Of Ph And Buffer Catalysts, Mohamad Imad Rafie

Theses and Dissertations

It has been shown that carbinolamides are intermediates in the enzyme-catalyzed synthesis of -amidated peptides. Although carbinolamides are important intermediates in the production of these hormones and have roles in other biological venues, little attention has been given to their mechanisms of reaction in water, and, thus, it is difficult to speculate how their reaction would be enzymatically catalyzed. The purpose of the work presented here was to synthesize structural analogs of the biological intermediates and study their mechanism of breakdown in water. -Hydroxyhippuric acid, a substrate for the enzymatic system, provides an easily modified template for the study of …

Self-Supported Nanocolumnar Pt And Pt-Ni Alloy Electrocatalysts For Polymer Electrolyte Membrane Fuel Cells, Busra Ergul

Theses and Dissertations

Polymer electrolyte membrane fuel cell (PEMFC) technology has gained significant attention as an alternative power source, especially for automotive applications due to PEMFCs’ high energy conversion efficiency, low operating temperature and being environment-friendly compared to the other types of fuel cells. However, sluggish kinetics of oxygen reduction reaction (ORR) on the cathode requires a high loading of platinum (Pt), which increases the cost of the fuel cell. In addition, dissolution and agglomeration of Pt nanoparticles and oxidation of the carbon support are among the major factors that cause electrode degradation and performance loss. Therefore, it is essential to develop a …

Unbinding Of Testosterone From The Androgen Receptor And Two Bf-3 Site Mutants, Muniruzzaman Chowdhury

Theses and Dissertations

The androgen receptor (AR) can be activated by molecules binding in the steroid binding pocket. It can also be regulated allosterically by cofactors binding to the AF-2 surface site as well as by exogenous small molecules binding to the BF-3 surface site. Recent data indicated that mutations in the BF-3 site changed the amount of the endogenous steroid needed to activate the receptor, indicating that mutations of BF-3 can cause an allosteric effect. Molecular dynamics and steered molecular dynamics simulations were used to study the allosteric effect of the mutations on AR structure and the unbinding pathways of testosterone (TES) …

Nonwovens Of Ceramic Decorated Cellulose Based Fine Fibers For Leaded Water Purification, Alejandro J. Castillo

Theses and Dissertations

Fine fibers of cellulose acetate were Forcespun and used to make nonwoven mats of cellulose. Nonwovens were activated using a solution combustion synthesis which deposited iron nitride onto fibers. Cellulose and cellulose composite mats were tested as adsorbents for lead ion in water. Cellulose showed slightly higher adsorption capacities (mg/g) up to 1300 mg/g lead loading. Adsorption data were further analyzed using several isotherms, of which the Dubinin-Raduskevich gave the best fits.

Flexible Dye-Sensitized Solar Cells: A Study Of Photoanode And Counter Electrode Materials, Brishty Deb Choudhury

Theses and Dissertations

Compare to flat devices based on rigid substrates, fiber-shaped dye sensitized solar cells hold advantages of smaller size, light weight, facile fabrication, flexibility, and low cost, thus a promising direction for applications such as wearable electronic devices. Due to their unique photovoltaic properties, nanostructured morphologies of TiO2 on flexible substrate have been studied extensively in the recent years for applications in dye sensitized solar cells (DSSCs). Micro-structured electrode materials with high surface area can facilitate rapid charge transport and thus improve the light-to-current conversion efficiency. In the first part of this work the nano-tree morphology of the TiO2 photoanode material …

Effect Of Electron Demand On Sensing Behavior Of Carbazolopyridinophanes, Grace Abban

Theses and Dissertations

Hydrazine (HZ), monomethylhydrazine (MMH), and 1,1-dimethylhydrazine (UDMH) are widely used as high energy rocket propellants in bipropellant rocket engines. However, hydrazine and its derivatives are highly flammable and carcinogenic. Currently, hydrazine sensors used for detection are irreversible which makes them costly. Two proposed carbazolopyridinophanes containing intramolecular hydrogen bonds were synthesized to detect hydrazine as real-time reversible sensors. However, their thresholds for detection (100 and 25 ppb for CPand 22OMeCPrespectively) were above the regulatory limit of 10 ppbdue to background fluorescence. It was established that the quenching of carbazole in the presence of the CP system has a direct correlation to …

The Development Of A New Entry Point Into Enantiomerically Enriched Sulfinyl Derivatives, Jessica Shaw

Theses and Dissertations

Optical probes may be used as reliable tools for detecting and imagining the inside of cells for medical diagnostics. Among available options, the use of thiol probes is of interest as thiols are present in nearly all cells and their levels are tightly regulated, thus any variation is associated with disease. A proper thiol bioimaging probe must have a thiol cleavage group/reactive group and a fluorophore. It is found that novel sulfinate aryl ester (phenoxysulfinate esters) probes selectively cleave thiols at physiological pH and show much promise as effective tools for bioimaging.

In this context, the synthesis of the related …

Guar Gum Based Hydrogel Matrices As Low-Cost Biomaterials For Bone Tissue Engineering, Anil Parameswaran Thankam

Theses and Dissertations

Hydrogels have existed for more than half a century, and today they have many applications including tissue engineering. We have synthesized hydrogel scaffolds based on low cost and biodegradable polymer like hydroxypropyl guar (HPG) and applying them for bone tissue engineering. We have fabricated hydrogel matrices without any toxic chemical crosslinker to avoid possible toxicity in fabrication. We followed two methods of fabrication for HPG based hydrogels. One is via physical crosslinking, by simply mixing poly(vinyl alcohol) (PVA) with HPG and the other one is grafting poly(vinyl caprolactam) (PNVCL) on HPG via radical polymerization. For the first method, we developed …

Disinfection Byproduct Drivers Of Cytotoxicity In Drinking Water And Swimming Pools, Joshua M. Allen

Theses and Dissertations

Water disinfection was cited as the greatest public health achievement of the 20th Century. By inactivating pathogens, disinfection has significantly reduced waterborne diseases in drinking water and swimming pools. However, chemical disinfection has also raised a public health issue: the potential for cancer induction, reproductive and developmental effects, and asthma-related risks associated with exposure to chemical disinfection byproducts (DBPs), which are formed by the reaction of disinfectants with organic matter (natural or anthropogenic), bromide, and iodide. In the U.S., four trihalomethanes (THMs) and five haloacetic acids (HAAs) are currently regulated in drinking water, although no DBPs are regulated in pools, …

The Rotational Spectrum Of 1,1-Diiodoethane, Michael Joseph Carrillo

Theses and Dissertations

The first chapter of this thesis introduces the basic theory of rotational spectroscopy. This includes the theory of a rigid rotor, centrifugal distortion, and hyperfine effects. The theory behind diatomic systems is explained first, and then expanded to the asymmetric top system. The second chapter encompasses a brief overview on the development of microwave spectroscopy and discusses the instruments that were utilized during this study, namely the cavity-based and chirped-pulse Fourier transform microwave spectrometers. Chapter three describes the quantum chemical calculation methods and basis sets that were applied throughout this study. Chapter four discusses the progress of data analysis of …

Protein Co-Assembly And Its Application In Enzyme Engineering, Libo Zhang

Theses and Dissertations

Enzymes, as highly efficient biocatalysts, have been researched extensively in both academia and industry because of their distinct advantages including high substrate specificity, high regio- and stereoselectivity, environmentally benign process, etc. Though enzyme catalysis has been scaled up for commercial processes in the pharmaceutical, food and beverage and detergent industries, technical barriers associated with enzyme implementation persist, i.e., low catalytic efficiency at non-natural environment, exhausting product separations, high cost of certain enzymes, etc. Moreover, currently most industrial enzymes are used in single-step reactions; however, multistep and multienzyme catalysis with optimal efficiency could greatly expand its potential for synthetic applications to …

Exploratory Molten Flux Crystal Growth Of Complex Uranium Oxides, Christian A. Juillerat

Theses and Dissertations

While the use of nuclear technology has proven useful for energy generation and for military use, the proper disposal and storage of the resulting nuclear waste requires serious attention to ensure radioactive species are indefinitely sequestered to protect the biosphere. There are several classifications of nuclear waste such as spent nuclear fuel (from industrial power plants), low level waste (slightly contaminated trash), and high level waste (HLW) which is in the form of a sludge, precipitated salt, or liquid. Each of these requires a different approach to processing and storage. Of these, HLW requires the most attention because it is …

Hydrogen Peroxide And Antioxidant Enzymes Moderate Interaction Of The Carbon And Oxygen Cycles At The Redoxcline, Fan Wang

Theses and Dissertations

Hydrogen peroxide is a reduced form of dioxygen produced in natural waters from a manifold of abiotic and biological processes. Hydrogen peroxide is highly redox active and it often serves to initiate the formation of reactive oxygen species in the environment. It typically exists in natural waters at concentrations ranging from as low as ~ 1 nanomolar in “blue water” marine environments to as high as 10 micromolar near actively effluxing sediments. It has the potential to cause significant toxicity in aquatic organisms, which have evolved a collection of antioxidant enzymes including peroxidase, catalase, and superoxide dismutase. Work in this …

Rapid Vertical Flow Assay On Aunp Plasmonic Paper For Sers-Based Point Of Need Diagnostics, Richard Frimpong

Theses and Dissertations

SERS based immunoassays for point-of-care diagnostics is a promising tool to facilitate biomarker detection for early disease diagnosis and control. The technique is based on a sandwiched system in which antigen is first captured by a selective substrate and then labeled by an extrinsic Raman label (ERL). Here, we report on the use of gold nanoparticle modified filter paper as a novel capture membrane in a vertical flow format. This vertical flow configuration affords reproducible flow of sample and label through the capture substrate to overcome diffusion limited kinetics and significantly reduced assay time. The filter paper was selected due …

Adsorption Behavior Of Chemically / Charged Modified Antibodies On Gold Nanoparticles, Samuel Okyem

Theses and Dissertations

Gold nanoparticles (AuNPs) have been exploited in the various domains of science such as drug delivery, bio-sensing, immunoassays and environmental sensors, due to their optical properties and intriguing surface chemistry. Different scientific procedures have been used to effectively immobilize antibodies onto AuNPs. Although acceptable outcomes have been achieved in the immobilization of antibodies onto AuNPs, the sensitivity of these immobilized antibodies to target antigen or binding sites is limited due to improper orientation of the antibodies. Also, the possibility of nanoparticle aggregation when exposed to proteins limits its biomedical applicability.

There is some evidence that the surface charge of antibodies …

Investigating The Reversibility Of Protein Adsorption On Gold Nanoparticles And The Role Of Free Thiol, Awosiji Olatunde Awotunde

Theses and Dissertations

Protein-gold nanoparticle (AuNP) bioconjugates have many potential applications in nanomedicine. A thorough understanding of the interaction between the protein and AuNP is critical to engineering these functional bioconjugates with desirable properties. In this work, we investigate the role of free thiols presented by the protein on the stability of the protein-AuNP conjugate. Human serum albumin (HSA) was modified with 2-iminothiolane (Traut’s reagent) to introduce additional thiols on the protein surface, and three variants of HSA were synthesized to present 1, 5, and 20 free thiols by controlling the molar excess of the chemical modifier. Protein exchange studies on AuNPs were …