Physical Sciences and Mathematics Commons^™

Application Of Mass Spectrometry For The Characterization Of Synthetic Oligomers And Natural Lignin, Poorya Kamali

Theses and Dissertations--Chemistry

As part of the ongoing effort to substitute finite fuel and chemical resources with renewable ones, biomass is emerging as one of the most promising sources. Biomass consists of three main components of cellulose, hemicellulose, and lignin. Traditionally, cellulose has been used extensively in pulping industry, while lignin has been considered waste and is burned to generate heat. Lignin, a complex aromatic polymer component of biomass, has the potential to be used as a source of aromatic chemicals and pharmaceutical synthons. The recalcitrant nature of lignin, the lack of effective lignin breakdown methods and analytical techniques to analyze it are …

Mass Spectrometric Analysis Of Lignin Model Compounds: Fundamental Investigations Of Ionization And Supramolecular Interactions For Lignocellulosic Biomass Applications, Kimberly Dean

Theses and Dissertations--Chemistry

Lignocellulosic biomass is pivotal for the development of renewable energy sources and materials essential to mitigate the exploitation of fossil fuels causing climate change and environmental pollution issues. The conversion of biomass into fuel requires the hydrolysis of cellulose and a biproduct of this process is the isolation of millions of tons of lignin as biorefinery waste. Lignin is a complex high molecular weight polymer whose structure remains undefined and critically limits potential industrial applications of lignocellulosic biomass. The advancement of analytical methods for structural elucidation of lignin and its ensemble of phenolic compounds is therefore essential to advance this …

Application Of Mass Spectrometry For Characterization Of Plant-Based Phenolics And Alkaloids, Masoumeh Dorrani

Theses and Dissertations--Chemistry

Plant-derived compounds have the potential to produce value-added compounds with a variety of applications. For example, the lignin part of the lignocellulosic biomass, produced in large quantities as waste from the paper and pulp industries, is a rich source of phenolics with potential applications in the renewable energy sector, pharmaceutical, and chemical industries. On the other hand, plant alkaloids are the primary source for developing plant-derived therapeutics. Unfortunately, the recalcitrant nature of plant cell walls, low extraction yields of small secondary metabolites, and the lack of effective analytical methods for a rapid and accurate identification of plant-based compounds and plant’s …

Development Of Fluorescence Based Approaches To Understand Astrocyte Biology In The Context Of Nicotine And Nicotinic Receptor Activity, Surya P. Aryal

Theses and Dissertations--Chemistry

Smoking and tobacco use (STU) is a major global health problem and worldwide more than six million people die due to tobacco related diseases each year. Although majority of smokers try to quit smoking several times in their life, traditional therapeutic approaches, which focus only on neuronal cells, have a very low success rate. Understanding the effect of nicotine on glial cells, synaptic communication and blood vasculature in the brain can provide further insights on the neurobiology of substance abuse and can potentially help to design better therapeutic approaches. Glial cells are non-excitable cells in the brain which do not …

Mass Spectrometry Method Development For The Discovery And Characterization Of Secondary Metabolites, Zachary Kelley

Theses and Dissertations--Chemistry

Secondary metabolites are organic compounds produced by an organism for reasons other than growth and development. In plants, secondary metabolites generally act as defense agents produced to deter predators and inhibit other competitive species. For humans, these compounds can often have a beneficial effect and are pursued and utilized as natural pharmaceuticals. The development of sensitive, high-throughput analytical screening methods for plant derived metabolites is crucial for natural pharmaceutical product discovery and plant metabolomic profiling. Here, metabolomic profiling methods were developed using a microfluidic capillary zone electrophoresis device and evaluated against traditional separation approaches. An alkaloid screening assay was constructed …

Plasmon Enhanced Single Molecule Fluorescence In Zero Mode Waveguides (Zmws), Abdullah Masud

Theses and Dissertations--Chemistry

Plasmonic nanostructures are an extensive research focus due to their ability to modify the photophysical properties of nearby fluorophores. Surface plasmons (SP), defined as the collective oscillation of delocalized electrons, are the fundamental characteristic primarily responsible for altering those photophysical properties. Studying fluorophores at the single-molecule level has received significant attention since more specific information can be extracted from single molecule-based studies, which otherwise could be obscured in ensemble studies. However, single-molecule studies are inherently challenging because the signal from a single molecule is usually dim, making it difficult to detect. The situation is even worse in a crowded environment …

Flavin Modification And Redox Tuning In The Bifurcating Electron Transfer Flavoprotein From Rhodopseudomonas Palustris: Two Arginines With Different Roles, Nishya Mohamed-Raseek

Theses and Dissertations--Chemistry

Electron bifurcation is considered as a third fundamental mode of energy conservation mechanism in addition to two well-known mechanisms, substrate level phosphorylation and Oxidative phosphorylation, in electron bifurcation endergonic and exergonic redox reactions are coupled. The newly discovered flavin based electron bifurcation in electron transfer flavoproteins (ETFs) helps to reduce low potential ferredoxin, which provides electrons to drive biologically demanding reactions such as atmospheric dinitrogen fixation in diazotroph and methane production in methanogens.

Current research demonstrates the capacity for electron bifurcation in the Rhodopseudomonas palustris ETF (RpalETF) system. RpalETF contains two chemically identical but functionally different FADs: …

Interfaces In Lead-Free Tin Perovskite Photovoltaics: An Investigation Of Energetics, Ion Mobility, Surface Modification, And Performance, Alex Boehm

Theses and Dissertations--Chemistry

Halide perovskites have generated tremendous interest as low-cost semiconductors for optoelectronics, such as photovoltaics, lasers, and light emitting diodes due to their extraordinary optical and transport properties. Perovskite photovoltaics in particular have demonstrated a meteoric rise in power conversion efficiencies and drawn considerable interest as a next-generation solar energy technology. The rapid development has centered around lead-based derivatives, and concerns regarding the toxicity of lead has sparked interest in low toxicity and more environmentally friendly perovskite derivatives. In this regime tin (Sn) is regarded as a prominent alternative owing to the ideal bandgap and reduced toxicity exhibited by Sn-halide perovskites. …

Derivatization Of Stable, Soluble Redox-Active Organic Materials For Non-Aqueous Redox Flow Batteries, Thilini Malsha Suduwella

Theses and Dissertations--Chemistry

In screening active materials for redox flow batteries (RFBs) – in which solubility is important to raise the volumetric energy density – scientists are slave to trial and error, modifying organic molecules in an attempt to optimize (increase) solubility without compromising other important properties such as stability and redox potential. A trained chemist can often predict the trends of solubility with the structural modifications in the neutral state of the materials, but when it’s come to the charged state of the materials, it doesn’t follow the same trend as the neutral species and relative values are hard to predict. The …

Flavodoxin, The Hydrogen Atom Of Flavoproteins: A 19f Nmr Study Of Dynamics And Conformational Changes Utilizing Flavodoxin From Rhodopseudomonas Palustris, Taylor Varner

Theses and Dissertations--Chemistry

Flavodoxin is a small, highly stable protein that contain a single FMN cofactor used to transfer single electrons at low potentials. The organism Rhodopseudomonas palustris contains a long-chain flavodoxin. Long-chain flavodoxins are characterized by a 20 amino acid loop that is proposed to allow interactions with partner proteins. We plan to utilize this protein as a model to build our repertoire with protein fluorination and fluorine NMR in flavoproteins. This tool kit will then be applied to the study of a partner protein of interest that is capable of performing electron bifurcation. We have incorporated m-fluoro tyrosine into flavodoxin and …

Applications Of Drones In Atmospheric Chemistry, Travis J. Schuyler

Theses and Dissertations--Chemistry

The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. A major technical and scientific challenge is quantifying the resulting fugitive trace gas fluxes under variable meteorological conditions. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating contributions of different processes to radiative forcing. Therefore, the adverse environmental and health effects of undetected gas leaks motivates new methods of detecting, characterizing, and quantifying plumes of fugitive trace gases. Currently, there is no mobile platform able to quantify trace gases at altitudes(UASs), or drones, can be deployed on-site in …

Oleic Acid Vesicles: Formation, Mechanisms Of Reactivity, And Uses In Determination Of Terpene Activity, Laura A. Walther

Theses and Dissertations--Chemistry

This dissertation will focus on the volatile compounds released upon the burning of incense which are numerous and varied. The first part of this dissertation is the gas chromatography-mass spectral (GC-MS) analysis of burning incense collected via solid phase microextraction (SPME) with the aim of developing a library of compounds found in incense as used in the Orthodox church.

The second part of this dissertation has the aim of developing a method for forming oleic acid bilayer vesicle membranes and a fluorescence spectroscopy method by which the reactivities of these vesicles can be analyzed. These reactivities include permeability, fluidity, aggregation, …

Bottom-Up Lignomics: Towards The Development Of Adduct Electrospray Ionization Mass Spectrometric Methods To Characterize And Sequence Lignin Oligomers, Shardrack O. Asare

Theses and Dissertations--Chemistry

Lignin, the second most abundant naturally occurring polymer found in plant cell wall has the potential of becoming an alternative source for the production of chemical synthons for the pharmaceuticals and other chemical industries. While much gain has been made towards the development of degradation methods to break down lignin, effective analytical methods are still required to rapidly and accurately identify the products of lignin breakdown experiments. The goal of this work was to develop mass spectrometric methods for the characterization of lignin oligomers based on the study of model lignin compounds.

Unlike peptides and oligosaccharides, lignin model compounds that …

Investigation Of Thiol-Containing Biomarkers And Their Role In The Exposome, Tracy Gastineau-Stevens

Theses and Dissertations--Chemistry

Exposomics is an emerging area of study that looks at how the environment around a person or persons affects their overall health. Biomarkers have emerged as useful tools to better understand how the exposome affects a person. In this work, we investigate two potential endogenous biomarkers, homocysteine and glutathione that have been previously implicated in a number of diseases that have been linked to environmental causes. We also investigated an environmental exposure, the fungicide Ziram, which epidemiologically has been linked to diseases. In our investigation, we utilized capillary electrophoresis and capillary electrophoresis-mass spectrometry to develop a method for homocysteine and …

Carbon Quantum Dots: Bridging The Gap Between Chemical Structure And Material Properties, Timothy J. Pillar-Little Jr.

Theses and Dissertations--Chemistry

Carbon quantum dots (CQDs) are the latest generation of carbon nanomaterials in applications where fullerenes, carbon nanotubes, and graphene are abundantly used. With several attractive properties such as tunable optical property, edge-functionalization, and defect-rich chemical structure, CQDs have the potential to revolutionize optoelectronics, electro- and photocatalysis, and biomedical applications. Chemical modifications through the addition of heteroatoms, chemical reduction, and surface passivation are found to alter the band gap, spectral position, and emission pathways of CQDs. Despite extensive studies, fundamental understanding of structure-property relationship remains unclear due to the inhomogeneity in chemical structure and a complex emission mechanism for CQDs.

This …

Catalytic Conversion Of Monosaccharides Into 5-(Hydroxymethyl)Furfural In Ionic Liquids Using Aluminum Complexes Bearing Bidentate (Aminomethyl)Phenolate Ligands, Daudi Sayialel Saang'onyo

Theses and Dissertations--Chemistry

Currently, the major sources of fuel, energy, and chemicals are nonrenewable fossil resources such as petroleum, natural gas, and coal. Additionally, petroleum is used for the production of most transportation fuels and for the production of about 95% of organic chemicals. However, the production and use of non-renewable fossil fuels are unsustainable. For economic and environmental sustainability, there is a need to search for new and/or renewable resources and technologies for energy, fuels, and chemicals production that have the potential of effectively substituting fossil resources. In this context, lignocellulosic biomass is one of the candidates that meet these requirements due …

Applications Of Cell-Derived Vesicles: From Single Molecule Studies To Drug Delivery, Faruk H. Moonschi

Theses and Dissertations--Chemistry

Single molecule studies can provide information of biological molecules which otherwise is lost in ensemble studies. A wide variety of fluorescence-based techniques are utilized for single molecule studies. While these tools have been widely applied for imaging soluble proteins, single molecule studies of transmembrane proteins are much more complicated. A primary reason for this is that, unlike membrane proteins, soluble proteins can be easily isolated from the cellular environment. One approach to isolate membrane proteins into single molecule level involves a very low label expression of the protein in cells. However, cells generate background fluorescence leading to a very low …

Enhanced Analysis Of Lignin Dehydrogenation Oligomers Via Mass Spectrometry, Amber Suzanne Bowman

Theses and Dissertations--Chemistry

Effective analytical techniques need to be developed to characterize the products of lignin degradation experiments to be able to generate renewable products from lignin. Mass spectrometry is an valuable analytical approach for lignin characterizaion, but it is hindered by lignin’s poor ionization efficiency, especially in the positive ion mode. In this work, we attempt to improve lignin’s ionization by utilizing electrospray and laser desorption mass spectrometry coupled with the addition of cations and chemical derivatives. We confronted the ionization problem from both a top-down and bottom-up analytical approach by analyzing synthesized monomers, dimers, and polymers along with natural lignin extracts …

Aqueous Photochemistry Of 2-Oxocarboxylic Acids, Alexis Eugene

Theses and Dissertations--Chemistry

Atmospheric aerosols affect climate change by altering the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosol (SOA) from gas phase precursors is relatively well understood, it does not account for the abundance of SOA observed during field measurements. Recently it has become apparent that in-aerosol aqueous chemical reactions likely provide some of the missing sources of SOA production, and many studies of aqueous phase processes are underway.

This work explores the fates of the simplest 2-oxocarboxylic acids, glyoxylic acid (GA) and pyruvic acid (PA), …

Energetic Effects Of Hole Transporting Materials On The Performance Of Organometal Halide Perovskite Photovoltaic Cells, So Min Park

Theses and Dissertations--Chemistry

Efficient, inexpensive, lightweight and flexible solar cells are desired to help meet the world’s growing energy needs. Organometal halide perovskite (OMHP) photovoltaic (PV) cells have shown dramatic increases in solar cell efficiencies increase over the last 5 years. OMHP PV cells have attracted significant attention due to their broad absorption spectra, high electron and hole mobility, and low production cost. The interface between hole transporting layer (HTL) and perovskite thin films have a significant influence on charge transfer and overall solar cell performance. 2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenylamine)9,9’-spirobifluorene (Spiro-OMeTAD) is a small molecule largely used as HTL in perovskite solar cells. However, this material …

Heterogeneous Base Metal Catalyzed Oxidative Depolymerization Of Lignin And Lignin Model Compounds, John Adam Jennings

Theses and Dissertations--Chemistry

With the dwindling availability of petroleum, focus has shifted to renewable energy sources such as lignocellulosic biomass. Lignocellulosic biomass is composed of three main constituents, lignin, cellulose and hemicellulose. Due to the low value of cellulosic ethanol, utilization of the lignin component is necessary for the realization of an economically sustainable biorefinery model. Once depolymerized, lignin has the potential to replace petroleum-derived molecules used as bulk and specialty aromatic chemicals. Numerous lignin depolymerization strategies focus on cleavage of β-aryl ether linkages, usually at high temperatures and under reductive conditions.

Alternatively, selective benzylic oxidation strategies have recently been explored for …

Semiconductor Photocatalysis: Mechanisms, Photocatalytic Performances And Lifetime Of Redox Carriers, Ruixin Zhou

Theses and Dissertations--Chemistry

Photocatalytic reactions mediated by semiconductors such as ZnS, TiO₂, ZnO, etc. can harvest solar energy into chemical bonds, a process with important prebiotic and environmental chemistry applications. The recycling of CO₂ into organic molecules (e.g., formate, methane, and methanol) facilitated by irradiated semiconductors such as colloidal ZnS nanoparticles has been demonstrated. ZnS can also drive prebiotic reactions from the reductive tricarboxylic acid (rTCA) cycle such as the reduction of fumarate to succinate. However, the mechanism of photoreduction by ZnS of the previous reaction has not been understood. Thus, this thesis reports the mechanisms for heterogeneous photocatalytic reductions …

Mechanisms Of Heterogeneous Oxidations At Model Aerosol Interfaces By Ozone And Hydroxyl Radicals, Elizabeth A. Pillar-Little

Theses and Dissertations--Chemistry

Atmospheric aerosols play an important role in climate by scattering and absorbing radiation and by serving as cloud condensation nuclei. An aerosol’s optical or nucleation properties are driven by its chemical composition. Chemical aging of aerosols by atmospheric oxidants, such as ozone, alters the physiochemical properties of aerosol to become more hygroscopic, light absorbing, and viscous during transport. However the mechanism of these transformations is poorly understood. While ozone is a protective and beneficial atmospheric gas in the stratosphere, it is a potent greenhouse gas in the troposphere that traps heat near the Earth’s surface. It also impacts human heath …

Characterization And Application Of Hybrid Nanostructures For Enhanced Biological Imaging Using Fluorescence Microscopy Techniques, William E. Martin

Theses and Dissertations--Chemistry

Fluorescence microscopy is a powerful tool for interpreting the structure and function of biomolecules, and their interactions with one another. Understanding fundamental biological mechanisms is important to the development of improved treatments for a variety of diseases. Fluorescent tags are used to track the motion and longevity of such events, with the ability to monitor several biomolecules at once. Currently, many of these studies are conducted using bulk measurements, or several biological events at the same time, because the added light from several emitters can more easily overcome the high fluorescence background inherent to biological systems. Although important in their …

Synthesis And Development Of Zwitterionic Pei (Zpei) For Optimized Delivery Of Nucleic Acids, Joseph Raleigh Duke Iii

Theses and Dissertations--Chemistry

Gene therapy holds promise for the treatment a wide range of diseases ranging from cystic fibrosis to cardiovascular disease to cancer. The need for safe and efficient gene delivery methods remains the primary barrier to human gene therapy. Non-viral vector materials, including polymers, can be designed to be biocompatible and non-immunogenic, but lack the efficiency to be clinically relevant. Gene therapy awaits the development of new materials that are both safe and efficient. Here, we have synthesized a series of modified zwitterionic polymers based on the common transfecting agent polyethylenimine (PEI). Using a variety of biochemical and biophysical methods we …

Application Of High-Resolution Accurate Mass (Hram) Mass Spectrometry For Analysis Of Lignin Model Compounds And The Post-Pretreatment Products, Fan Huang

Theses and Dissertations--Chemistry

Lignin, one of main components in the woody cell walls, is a complex heterogeneous biopolymer, which provides structural support and transportation of water in plants. It is highly recalcitrant to degradation (both chemically and environmentally) and protects cellulose from being degraded/hydrolyzed. Due to the structural complexity of native lignin, complete characterization and elucidation of lignin’s structure remains very challenging. The overarching goal of this work is to develop mass spectrometry based analytical methods to contribute to a better understanding of lignin structures.

This dissertation will focus on the development and application of High-Resolution Accurate-Mass (HRAM) Mass Spectrometry (MS) as main …

Epigenetic Modifications To Cytosine And Alzheimer’S Disease: A Quantitative Analysis Of Post-Mortem Tissue, Elizabeth M. Ellison

Theses and Dissertations--Chemistry

Alzheimer’s disease (AD) is the most common form of dementia and the sixth leading cause of death in the United States, with no therapeutic option to slow or halt disease progression. Development of two characteristic pathologic lesions, amyloid beta plaques and neurofibrillary tangles, in the brain are associated with synaptic dysfunction and neuron loss leading to memory impairment and cognitive decline. Although mutations in genes involved in amyloid beta processing are linked to increased plaque formation in the inherited familial form of AD, the more common idiopathic form, termed sporadic AD, develops in the absence of gene mutations. In contrast, …

The Optimization Of The Synthesis And Characterization Of Vapor-Liquid-Solid Grown Zno Nanowires, Silas R. Fiefhaus

Theses and Dissertations--Chemistry

ZnO nanowires are a promising material with great semiconductor properties. ZnO nanowires were prepared by carbothermal reduction and vapor-liquid-solid growth mechanism. Altering a variety of parameters ranging from mole to mole ratio of ZnO to C all the way to gas flow rate was examined. The nanowires were then characterized and their morphology examined under a SEM to observe what effect the parameter had on the morphology of the nanowires. From the experiments and the parameters tested it was observed that in order to produce the highest quality straight nanowires one should use a mole to mole ratio of ZnO …

The Development Of Colorimetric Assays To Determine The Identity And Frequency Of Specific Nucleobases In Dna Oligomers, Elizabeth Marie Thomas

Theses and Dissertations--Chemistry

Colorimetric methods combined with color-changing chemical probes are widely used as simple yet effective tools for identifying and quantifying a wide variety of molecules in solution. For nucleic acids (DNA and RNA), perhaps the most commonly used colorimetric probe is potassium permanganate, which can be used to identify single-stranded pyrimidines (thymine and cytosine) in polymers. Unfortunately, permanganate is not an effective probe for identifying purines (adenine and guanine), especially in the presence of the more reactive pyrimidines. Therefore, robust methods for discriminating between the purines remain elusive, thereby creating a barrier toward developing more complex colorimetric applications. In this dissertation, …

Towards An Understanding Of Pharmacologically Induced Intracellular Changes In Nicotinic Acetylcholine Receptors: A Fluorescence Microscopy Approach, Ashley M. Loe

Theses and Dissertations--Chemistry

Upregulation of nicotinic acetylcholine receptors (nAChRs) is a well-documented response to chronic nicotine exposure. Nicotinic acetylcholine receptors are pentameric ligand-gated ion channels consisting of alpha (α2-10) and beta (β2-4) subunits. Nicotine, an agonist of nAChRs, alters trafficking and assembly of some subtypes of nAChRs, leading to an increase in expression of high sensitivity receptors on the plasma membrane. These physiological changes in nAChRs are believed to contribute to nicotine addiction, although the mechanism of these processes has not been resolved. Recently, many studies have converged on the idea that nicotine induces upregulation by an intracellular mechanism. In this dissertation, expression …