Chemistry Commons^™

Application Of The Entropy Concept To Thermodynamics And Life Sciences: Evolution Parallels Thermodynamics, Cellulose Hydrolysis Thermodynamics, And Ordered And Disordered Vacancies Thermodynamics, Marko Popovic

Theses and Dissertations

Entropy, first introduced in thermodynamics, is used in a wide range of fields. Chapter 1 discusses some important theoretical and practical aspects of entropy: what is entropy, is it subjective or objective, and how to properly apply it to living organisms. Chapter 2 presents applications of entropy to evolution. Chapter 3 shows how cellulosic biofuel production can be improved. Chapter 4 shows how lattice vacancies influence the thermodynamic properties of materials. To determine the nature of thermodynamic entropy, Chapters 1 and 2 describe the roots, the conceptual history of entropy, as well as its path of development and application. From …

Experimental And Computational Studies Of Rotation And Proton Tunneling In Organic Molecules And Molecular Dimers, Agapito Serrato Iii

Theses and Dissertations

An introduction to the relations of classical and quantum mechanics are presented in brief. As is an overview of the instrumentation and quantum chemical analysis performed to characterize the molecules presented in in this thesis. The pure rotational spectrum of 3,3,3-trifluoro-2(trifluoromethyl)propanoic acid, perfluorobutyric acid–formic acid dimer, and tropolone–formic acid dimer were measured using high-resolution microwave spectroscopy. The spectra have been observed using a cavity-based Fourier-transform microwave (FTMW) spectrometer and/or a chirped-pulse FTMW.

Microwave-Assisted Ring-Opening Polymerization Of Poly(Ε-Caprolactone), Nancy Obregon

Theses and Dissertations

Poly(ϵ-caprolactone) (PCL) is a biodegradable polyester notorious by its promising properties and applications in the biomedical field. In this work, microwave-assisted ringopening polymerization (ROP) of ϵ-caprolactone (ϵ-CL) was performed. Stannous octoate [Sn(Oct)2] was used as catalyst with and without an alcohol initiator. The different initiators tested were glycerol, diethylene glycol (DEG) and poly(ethylene) glycol (PEG). Aiming to establish reaction parameters, the influence of different reaction times, temperatures, and monomer:initiator:catalyst ratios were examined. It was observed that the reaction was obtained and high molecular weight PCL was achieved successfully without an initiator. However, mixed results were obtained using an initiator. Products …

Removal Of Chromium(Vi) And Chromium(Iii) Ions From Aqueous Solution Using Bio-Char Generated From Agricultural Waste Products, Diego Fernando Gonzalez

Theses and Dissertations

Heavy metals are one of the most persistent and prevalent contaminants in the aquatic environment. The removal of chromium from aqueous solution, especially in the hexavalent form is difficult. New technologies, techniques and/or new materials have been designed in order to effectively and efficiently remove chromium from the aqueous environment. The project focuses on the comparison of the effects of pH, time, temperature, binding capacity on bio-char’ generated from agricultural waste produces vs an amino modified derivative of the bio-char. Pineapple skins were dried, ground, sieved, and pyrolyzed to produce a bio-char material. The bio-char was analyzed using FTIR to …

Thermal Analytical Studies Of Azo-Tetrazolate Compounds For Htpb Based Hybrid Rocket Fuels, Muntaha Yousef

Theses and Dissertations

Azo-Tetrazolate salts and their derivatives have identical negatively conjugated nitrogen rings and two varied positively charged cations. The varied cations are Guanidinium, Aminoguanidinium, Diaminoguanidinium, Triaminoguanidinium and Ammonium. Azo-Tetrazolate salts and their derivatives were synthesized and fully characterized by multinuclear spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The thermal behavior and decomposition kinetics of Guanidinium Azo-Tetrazolate (GAT), Aminoguanidinium Azo-Tetrazolate monohydrate (AGATH), Diaminoguanidinium Azo-Tetrazolate (DAGAT), Triaminoguanidinium Azo-Tetrazolate (TAGAT)and Ammonium Azo-Tetrazolate (AZT), were investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) techniques. The kinetic and thermodynamic parameters of these energetic materials were calculated non-isothermally by DSC instrument, under various heating …

Alkyne Combustion: Experimental And Computational Studies Of Formyl Radical Production, Matthew Charles Drummer

Theses and Dissertations

The United States consumed a total of 97.4 trillion BTUs of energy in 2016 with over 80% of that energy consumption source being fossil fuel combustion. Before a combustion reactions reaches its end products, a number of intermediate products form and may react with other abundant atmospheric species to form aerosol particles and acid rain, both of which have potentially negative impacts on both human-made structures and the natural environment.

In an effort to counteract the consequences of fossil fuel combustion, scientists are interested in understanding the reaction mechanisms of hydrocarbon combustion reactions to understand which intermediate products form and …

Creation And Use Of Software For Analysis Of Kinetic Proteomic Experiments, Bradley C. Naylor

Theses and Dissertations

In this dissertation, I will review the history and general strategies for performing kinetic proteomics. I will then demonstrate that I have published an open source, user-friendly program for other scientists to use to perform kinetic proteomics data analysis, as well as publishing a novel discovery of key ribosomal subunits being replaced within the lifetime of the ribosome, which was discovered through use of kinetic proteomics. Finally, I will discuss work that is ongoing to improve my software tool for use in human subjects, and work being done to combine kinetic proteomics with other global analysis methods to make novel …

Improving Fallout Characterization By Using Multivariate Techniques To Determine Composition, Christopher R. Pitkins

Theses and Dissertations

Multivariate statistical techniques have been applied in order to un-mix nuclear fallout debris chemical data. This information is critical to characterization of fallout particle formation following a nuclear detonation. Understanding the correlation between environmental precursors and actinide concentrations in post-detonation nuclear fallout material aids in understanding the physical and chemical processes that alter nuclear device signatures in the fireball. This research examines 123 nuclear fallout samples from a historical nuclear test. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used to collect chemical compositions of the fallout samples. Principal component analysis (PCA) is applied in order to examine …

Contribution Of Bulky <&Alpha>,<&Beta>-Dehydroamino Acids To The Proteolytic Stability Andenhanced Folding Of <&Beta>-Hairpins And Progress Towards The Total Synthesis Of Yaku<'>Amide A, Ankur Jalan

Theses and Dissertations

This dissertation primarily covers the impact of bulky ,-dehydroamino acids on the proteolytic stability and enhanced folding of -hairpins. It partly describes the progress towards the total synthesis of yakuamide A, a potent anticancer peptide with an IC50 value of 14 ng/mL against leukemia cells. Proteins and peptides are a very attractive source of potential medicinal agents as they can target various protein“protein interactions that are implicated in several diseases and disorders. The global sales of peptide drugs in 2013 were estimated to be about $28 billion and are constantly rising at an appreciable rate. However, peptide drugs have a …

Preparation Of Polymeric Materials From Bio-Renewable Sources, Jason Douglas Smith

Theses and Dissertations

The focus of this project was to develop methodologies for the preparation of novel polymeric materials from bio-renewable sources. In order to complete this task we needed (a) unfettered access to bio-based materials and ways to convert them to value needed chemicals, as well as, (b) reaction protocols that would allow greater diversity during the synthesis of polymeric compounds so as to affect the properties of these materials.

Our research group has a background in converting plant-based materials like cellulose into value added chemicals employing catalytic reactions. The polymerization of these monomers was then conducted utilizing the Baylis-Hillman reaction. The …

Semi-Synthesis Of A Novel Library Of Alkaloids As Potential Selective Analgesics, Brittany M. Gallagher

Theses and Dissertations

Semi-synthetic compounds are an important part of the therapeutic drug discovery process. The goals of the project were to synthesize different generations of matrine analogues in order to gain many opportunities to manipulate the core structure. The long-term goal was, by manipulating the structure, the possibility to increase the biological activity of the original compound while also decreasing the toxicity. The first-generation matrine analogue allows for a synthesis similar to the Striker reaction producing aminonitriles. An alkyne coupling reaction was also possible with the modification, producing propargyl-amines. Both of the reactions resulted in the addition of a triple bond substituent …

Investigation Of The Spatial Dependence Of Carrier Dynamics In Semiconductor Optoelectronic Devices, Bobby G. Barker Jr.

Theses and Dissertations

Optoelectronic devices, such as solar cells and photodetectors, rely on separating and transporting charge through semiconductors that have excess electron-hole pairs created by photon absorption. This talk will focus of several different semiconductor materials of various dimensionality, such as lead halide perovskites, wide bandgap SiC, graphene, semiconductor nanowires (NWs), and quantum dots (QDs).

The results of Chapter 2 demonstrate the dependence of the perovskite/hole transport layer on carrier transport of perovskite films for solar cells. Efficient charge separation at the interfaces of the perovskite with the carrier transport layers is crucial for perovskite solar cells to achieve high power conversion …

Biosensing And Catalysis Applications Of Nanoporous Gold (Npg) And Platinum-Speckled Nanoporous Gold (Npg-Pt) Electrodes, Christopher J. Freeman

Theses and Dissertations

The importance of porous materials has risen substantially in the last few decades due to their ability to reduce the size and cost of bioanalytical devices and fuel cells. First, this work aims to describe the fabrication of nanoporous gold (NPG) electrodes that are resistant to electrode passivation due to fibrinogen biofouling in redox solutions. The effect on potentiometric and voltammetric experiments was seen as a deviation from ideal behavior on planar gold electrodes, whereas NPG electrodes were consistently behaving in a Nernstian fashion at low concentrations of ferri-ferrocyanide (£100 mM). An improvement in electrode behavior on NPG electrodes versus …

Synthesis And Characterization Of Magnetic Cabides And Oxides Nanomaterials, Hei Man Tsui

Theses and Dissertations

The design and development of nanoparticles is of great interest in the current energy and electronic industry. However, based on the current materials available the production cost can be high with insignificant magnetic and mechanical properties. Specifically, rare-earth magnetic materials composed of neodymium and samarium are known for their high magnetic performance, however, due to the cost of development there is a need to develop a versatile and cost effective material. Alternatively, cobalt carbide nanomaterials have shown to be a promising alternative for rare-earth free magnets as they exhibit comparable properties as hexaferrite magnetic materials. The primary goal of this …

5-Ht2b Receptor-Mediated Cardiac Valvulopathy, Pallavi Nistala

Theses and Dissertations

5-HT_2B receptor agonism causes cardiac valvulopathy, a condition characterized by thickening of the heart valves and as a result, regurgitation of blood within the heart. The anti-obesity drug fenfluramine, which was originally prescribed as an anorectic, was withdrawn from the market due to causing cardiac valvulopathy. Fenfluramine, after metabolism by N-dealkylation, produces the metabolite norfenfluramine, which acts as a more potent valvulopathogen. The same was seen with MDMA (ecstasy), a popular drug of abuse, which is metabolized by N-dealkylation to produce MDA, a more potent valvulopathogen. Glennon and co-workers. studied a series of 2,5-dimethoxy-4- substituted phenylisopropylamines (DOX type) hallucinogens …

Mechanistic Studies Of Proton-Coupled Electron Transfer Reactions Involving Antioxidants, Kejie Meng

Theses and Dissertations

The objective of the research was to investigate proton-coupled electron transfer (PCET) reactions involving antioxidants to gain insight into the detailed mechanisms of glutathione (GSH), Trolox, and α-tocopherol (α-TOH). PCET reactions are complex redox reactions that transfer electrons and protons sequentially or in concert. These reactions are ubiquitous in natural or artificial processes that produce electrochemical energy that is extractable as electricity or as chemical fuels of high energy content. Examples of processes based on PCET are photosynthesis, respiration, nitrogen fixation, carbon dioxide reduction, redox fuel cells, and artificial photosynthesis. Antioxidants were selected as a PCET model to understand the …

Gas-Phase Studies Of Nucleophilic Substitution Reactions: Halogenating And Dehalogenating Aromatic Heterocycles, Leah L. Donham

Theses and Dissertations

Halogenated heterocycles are common in pharmaceutical and natural products and there is a need to develop a better understanding of processes used to synthesize them. Although the halogenation of simple aromatic molecules is well understood, the mechanisms behind the halogenation of aromatic heterocycles have been more problematic to elucidate because multiple pathways are possible. Recently, new, radical-based mechanisms have been proposed for heterocycle halogenation. In this study, we examine and test the viability of possible nucleophilic substitution, S_N2@X, mechanisms in the halogenation of anions derived from the deprotonation of aromatic heterocycles. All the experiments were done in a …

Iron Transport Machinery: A Potential Therapeutic Target In Escherichia Coli, Clorissa L. Washington – Hughes

Theses and Dissertations

Iron metabolism is an integral part of life for most organisms. Despite its essentiality, iron can also become toxic. There are many aspects to maintaining iron balance within the cell. The aim of this work is to provide insight into the function of several components involved in bacterial iron homeostasis. This work is significant for the development of novel antibiotics for treating resistant or pathogenic bacteria. Herein, it is shown that nickel can disrupt normal bacterial iron metabolism and that bacterial resistance can be affected by expression of iron acquisition genes. Once iron is obtained by the cell, it can …

Block Copolymer Control Of Nanoscale Porous Materials, Amrita Sarkar

Theses and Dissertations

The controlled fabrications of porous materials are crucial for a wide variety of uses spanning the gamut from energy applications to filtration. Despite decades of developments based upon block copolymer self-assembly there remain numerous limitations to achieve simple ends such as fully-tunable nanomaterials or well-defined macroscopic forms. For example, fundamental studies of nanostructure-performance relationships need systematic series of nanomaterials to identify the separate effects of wall and pore dimensions. Such precision control is impossible under the constraints of equilibrating systems. Persistent Micelle Templating (PMT) is rather based on kinetic control and enables robust and independent tuning of each feature. However, …

Hydrothermal Synthesis: A Gateway To Metastable Crystals With Unusual Properties, Justin B. Felder

Theses and Dissertations

Research into crystalline matter has long been of interest to humanity, both in order to advance our society by creating new technologically useful materials and in order to better understand to nature of the properties we depend on for so much of our existing technology. In recent decades, solution-based crystal growth syntheses including hydrothermal and molten flux techniques have risen to the forefront of solid-state chemistry as superior methods of synthesizing new materials as single crystals ripe for structure determination and property measurements.

This work seeks to educate readers on recent advances in the hydrothermal realm of crystal growth: namely …

Electrochemical Methods To Study Real-Time In Vivo Neurochemistry, Aya Abdalla

Theses and Dissertations

Serotonin neurotransmission has multiple facets that are challenging to characterize, due to the lack of analytical tools that can measure serotonin in the brain. In addition, the mechanisms of serotonin modulation by other neurotransmitters, such as histamine, are not well understood. These limitations make the study and treatment of disorders in which serotonin is implicated problematic. This dissertation presents novel electrochemical methods, in addition to the well-established serotonin fast-scan cyclic voltammetry (FSCV), to better understand the dynamics of serotonin and histamine neurotransmission in vivo. In Chapter 1, a method, known as fast-scan controlled adsorption voltammetry, was optimized to selectively and …

Catalytic Oxidation Of Methane Over Alumina Supported Palladium Oxides, Jacqueline Michelle Mcguire

Theses and Dissertations

The objectives of this research include development and characterization of alumina supported palladium oxide catalysts for low temperature catalytic oxidation of methane. The catalysts were prepared by various methods and then characterized and screened to select the best catalyst for further studies. A 5% (wt/wt) Pd/y-AhCb catalyst prepared by an improved vortex-assisted incipient wetness method showed the best activity of 94% (mol/mol) methane conversion at 325 °C. The active surface species was found to be PdO and Pd native oxides (PdNtv) as confirmed by X-ray Photoelectron Spectroscopy and activity studies. The y-AhCb support played an integral role in the formation …

Antibiotic Effects Of Dimethyl Sulfoxide And Synthetic Polyphenols On E. Coli Cells, Camila Cardenas

Theses and Dissertations

There is increasing interest in polyphenols due to their potential medicinal and antibiotic applications. Naturally occurring polyphenols, such as curcumin, have garnered tremendous attention. However, synthetic polyphenols commonly used in biochemistry experiments have not been sufficiently explored. The purpose of this study is to determine the effect of dimethyl sulfoxide on the cellular uptake of synthetic polyphenols. Three synthetic polyphenols (Phenol Red, Congo Red, and Bromophenol Blue) were tested for their antibiotic properties and compared to the antibiotic activity of curcumin. Our results show that phenol red does not interact with the bacterial membrane even in the presence of 30% …

Laser Synthesis Of Nanomaterials Incorporated Within High Surface Area Materials: Applications For Heterogeneous Catalysis, Water Treatment, And Photothermal Energy Conversion, Julian A. Bobb

Theses and Dissertations

Chemical methods are generally used for the synthesis of active nanoparticles (metals, semi-metals, metal oxides, and etc) supported on high surface area materials. Chemical methods involve using strong solvents, harmful gases (H₂ & CO), and high temperature techniques such as high boiling solvents, calcination and pyrolysis. The main drawbacks of using this approach, is the prevalence of chemical agents on nanomaterials which tends to negate its applications. Alternatively, photochemical and photothermal methods are widely being considered for the synthesis and design of nanomaterials.

For these studies, the active nanomaterials incorporated within high surface area materials were prepared by the …

Determination Of Local Elastic Modulus Of Soft Biomaterial Samples Using Afm Force Mapping, Faieza Saad Ejweada Bodowara

Theses and Dissertations

Conventional methods of mechanical testing cannot measure properties of soft materials at the nanoscale. In fields such as tissue engineering, it is important to distinguish the bulk elastic modulus from the surface elastic modulus and to characterize the spatial distribution of material with non-uniform stiffness. One of the important new methods of testing is the force mapping using the atomic force microscope. The existing force mapping approaches often suffer from omitting important effects that might result in artifacts. The most important effects include taking into account sample’s adhesion and viscoelasticity and considering more realistic probe shapes. In this work, we …

Crystallomagnetic Studies Of First And Third Row Transition Metal Containing Oxides Grown Via The Molten Flux Method, Timothy Ferreira

Theses and Dissertations

The primary objective of this dissertation is to inform about the single crystal growth of complex first and third row transition metal oxides via molten flux methods. Particular focus is given to complex oxides that contain transition metals with unpaired electrons. This fundamental research is motivated by a singular question: What can a critical analysis of chemical structure elucidate about magnetic order in oxide materials? Throughout the eight chapters of this dissertation, including an introductory chapter, this structure-property relationship will be investigated. These seven chapters will be organized into three parts, each corresponding to the general structure type of the …

Tailoring Polybenzimidazole Membranes For Enhanced Performance In Electrochemical Devices, Andrew T. Pingitore

Theses and Dissertations

After approximately 15 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120-180 OC due to the physical and chemical robustness of PBI membranes. These higher temperatures improve the electrode kinetics and conductivity of the MEAs, simplify the water and thermal management of the systems, and significantly increase their tolerance to fuel impurities. Membranes cast by a newly developed polyphosphoric acid (PPA) Process possessed excellent mechanical properties, higher phosphoric acid …

Dually Modified Transmembrane Proteoglycan Tβriii/Betaglycan In Cell Signaling And Cancer, Laura M. Jenkins

Theses and Dissertations

During tumor progression, cancer cells undergo a number of alterations to evade tumor inhibitory mechanisms, proliferate, invade surrounding tissues and metastasize to distant sites. These properties reflect changes in their cell signaling pathways that, in normal cells, control aberrant cell proliferation, motility, and survival. Over the past few decades, hyperactive Wnt/β-catenin signaling has been linked to the formation of multiple cancers, including malignant ovarian cancer, making identification of molecules regulating Wnt/β-catenin signaling crucial to the development of early detection methods and cancer treatment strategies. Proteoglycans, which regulate transmission of cellular signals, are implicated in the pathophysiology of diseases, including cancer, …

Investigation Of Gold(Iii) Complexes With Hiv-Ncp7 And Models, James Beaton

Theses and Dissertations

The medicinal uses of gold date as far back as 2500 B.C. in China. In modern times, gold has been used in the treatment of a number of different human diseases including rheumatoid arthritis, cancer, and viral infections. This dissertation will focus on the development of gold complexes for the purpose of selective inhibition of HIV NCp7, a 55 amino acid zinc finger protein with two Cys₃His zinc binding domains.

NCp7 is involved in a number of viral life cycle processes including activation of reverse transcription, integration, DNA recognition, RNA packaging, and formation of the viral envelope. The …

Correlation Of Aqueous Solubility And Anti-Cancer Activity Of Novel Triazolium And Imidazolium Salts, Jared J. Bies

Theses and Dissertations

Novel triazolium, imidazolium, and benzimidazolium salts are known to possess anti-cancer properties and have potential as cancer therapeutics. This thesis describes the aqueous solubility and the differential activity of N,AT-bis-substituted-l,2,4-triazolium bromide salts and N/N'-bis(naphthylmethyl)imidazolium bromide salts against MDA-MB-468 breast cancer cells and PC-3 prostate carcinomas. Using a microscale technique, the partition coefficient (log P) of each salt was determined. The log P value was explored to determine the bioavailability of each derivative.