Analytical Chemistry Commons^™

Utilizing Coal For Mesophase Pitch-Based Carbon Fiber Production: Precursors, Processes, And Progress, Christina M. Thompson

Theses and Dissertations--Chemistry

Graphitic materials possess unique properties due to the unique combination of layered crystalline structure and carbon’s low atomic weight. High performance carbon fiber is one such example, displaying exceptional strength-to-weight ratios, stiffness, and thermal and chemical resistance. These properties render high performance carbon fiber a critical structural reinforcement material in the manufacture of composites across various industries, such as for automotive and aerospace applications. However, balancing fiber performance with precursor and processing costs remains a challenge. As alternative carbonaceous feedstocks are explored, coal has gained interest for utilization in graphitic products as a relatively abundant and low-cost source of aromatic …

Valorizing Municipal Solid Waste For Sustainable Aviation Fuel And Polyhydroxyalkanoate Bioplastics: Pyrolysis And Microbial Pathways, Emon Das

Theses and Dissertations--Biosystems and Agricultural Engineering

The escalating global burden of municipal solid waste (MSW), projected to reach 3.88 billion tons annually by 2050, calls for innovative valorization strategies to mitigate environmental impacts and promote a circular bioeconomy. This thesis investigates the conversion of MSW into two high-value products: sustainable aviation fuel (SAF) and polyhydroxyalkanoate (PHA) bioplastics. Chapter one presents comprehensive physicochemical characterization and pyrolysis-GC/MS analysis of MSW feedstocks. The physicochemical results reveal that densification enhances handling and storage properties, while pyrolysis-GC/MS analysis indicates that plastic-rich MSW streams produce bio-oils with favorable hydrocarbon profiles suitable for SAF production, potentially contributing to decarbonization efforts in the aviation …

Chromatographic And Electrophoretic Analysis Of Lignin-Derived Monomers And Dimers: Extraction Method Development And Evaluation Of Cyclodextrins For Recovery, Anjam Sadik

Theses and Dissertations--Chemistry

Biorefineries play a vital role in reducing dependence on fossil fuels and addressing global warming concerns. Unfortunately, investment in biorefineries remains limited due to economic sustainability concerns. One approach to enhance the economic viability of biorefineries is by fully utilizing the potential of feedstocks, particularly lignocellulosic biomass, which is commonly used in these processes. Traditional processing methods often alter the lignin portion of biomass, making it unsuitable for further utilization. However, when retained in its native form, lignin can serve as a valuable source of chemicals that contribute to the economic sustainability of biorefineries.

The lignin-first approach, which removes lignin …

Insights Into Factors Influencing Radical Coupling Chemistry Of Monolignols During Lignification And Induced Changes In Plant Secondary Metabolism, Rachel Poornima Sutherland

Theses and Dissertations--Chemistry

Lignin is a complex aromatic biopolymer and an important constituent in plant cell walls. The process of lignin biosynthesis, known as lignification, is poorly understood and challenging to study but has important implications in a variety of fields including sustainable energy, bioengineering, and materials science and is therefore of interest to pursue. In the final stage of lignification, H-, G-, and S-monolignols are oxidized by laccase and peroxidase enzymes to generate radical species that couple to form dimers and further oligomeric species to ultimately produce the lignin polymer. Biomimetic lignin model systems utilize in vitro oxidative coupling reactions as an …

Targeted Mitigation Strategies To Reduce Secondary Emissions In Co2 Capture Systems, Keemia Abad

Theses and Dissertations--Chemistry

Global CO₂ emissions from industrial, power generation and transportation sources has led to the call for increased implementation of carbon capture strategies. The most developed of these is point source carbon capture, which refers to the process of capturing CO₂ directly from large (point) source emitters, before the CO₂ is released into the atmosphere. The challenge becomes separating CO₂ from the other components of the emitted gas, mainly nitrogen. These CO₂ capture processes typically involve the use of aqueous solutions of amines to absorb (capture) CO₂ from the gas stream, where the CO₂ and the …

Microfiltration Membrane Pore Functionalization With Primary And Quaternary Amines For Pfas Remediation: Capture, Regeneration, And Reuse, Sam Thompson, Angela Gutierrez, Jennifer Bukowski, Dibakar Bhattacharyya

UK CARES Faculty Publications

The widespread production and use of multi-fluorinated carbon-based substances for a variety of purposes has contributed to the contamination of the global water supply in recent decades. Conventional wastewater treatment can reduce contaminants to acceptable levels, but the concen- trated retentate stream is still a burden to the environment. A selective anion-exchange membrane capable of capture and controlled release could further concentrate necessary contaminants, mak- ing their eventual degradation or long-term storage easier. To this end, commercial microfiltration membranes were modified using pore functionalization to incorporate an anion-exchange moiety within the membrane matrix. This functionalization was performed with primary and …

Amperometric Bio-Sensing Of Lactate And Oxygen Concurrently With Local Field Potentials During Status Epilepticus, Eliana Fernandes, Ana Ledo, Greg A. Gerhardt, Rui M. Barbosa

Neurology Faculty Publications

Epilepsy is a prevalent neurological disorder with a complex pathogenesis and unpredictable nature, presenting limited treatment options in >30 % of affected individuals. Neurometabolic abnormalities have been observed in epilepsy patients, suggesting a disruption in the coupling between neural activity and energy metabolism in the brain. In this study, we employed amperometric biosensors based on a modified carbon fiber microelectrode platform to directly and continuously measure lactate and oxygen dynamics in the brain extracellular space. These biosensors demonstrated high sensitivity, selectivity, and rapid response time, enabling in vivo measurements with high temporal and spatial resolution. In vivo recordings in the …

Addressing The Effects Of Counterion Size On The Properties Of Electrochemically Doped Conjugated Polymers, Kyle Baustert

Theses and Dissertations--Chemistry

Conjugated polymers (CPs) are an emerging class of materials that are attractive for many applications due to their low cost, flexibility, and ease of processing. Both chemical and electrochemical doping of CPs is done to alter important properties such as their electrical conductivities and optical absorbances. This ability to tune their properties allows for their use in devices such as organic electrochemical transistors (OECTs) for biosensing and bioelectronics, electrochromic devices for color changing windows, as well as wearable thermoelectrics to use body heat to power wearable electronics. There are several factors that can influence the properties of doped CPs including …

Effect Of Π-Conjugated Ligands And A* Site Organic Cations On The Energetic Properties And Photovoltaic Performance Of Metal Halide Perovskites, Harindi R. Atapattu

Theses and Dissertations--Chemistry

Metal halide perovskites have gained interest in optoelectronic applications such as photovoltaics, lasers, LEDs, transistors, and photodetectors due to their excellent semiconducting properties considering their low cost. Metal halide perovskite (HP) photovoltaics have rapidly increased in power conversion efficiency (PCE), which now exceeds 25%. HPs have gained attention in these applications due to their high tolerance towards defects, long charge carrier diffusion lengths, high charge carrier mobility, high optical absorption, and bandgaps that are tunable over a large range. Even though HP photovoltaic PCEs are improved these are still not commercially available due to them showing lower stability and energy …

Stability Of Organic Metal Halide Perovskites, S S M Tareq Hossain

Theses and Dissertations--Chemistry

Perovskites have emerged as a promising candidate for low-cost production of solar cells. However, the most critical barrier for commercialization of perovskite solar cells (PSCs) is the inadequate stability of the organic metal halide perovskites (OMHPs). The degradation of OMHPs is induced by light, heat, air, and electrical bias. The known degradation pathways involve the oxidation of I- and Sn2+, dissolution of perovskites by moisture, irreversible reactions with water, ion migration, and ion segregation. To improve the stability of OMHPs various methods are adopted, such as additive engineering, perovskite surface treatment, and composition engineering. Surface ligands are used on top …

Impacts Of Key Degradation Byproducts On Amine Scrubbing For Post-Combustion Carbon Capture, Thomas Jorgensen

Theses and Dissertations--Chemistry

The increasing atmospheric CO₂ concentration causes significant concern about global warming and its environmental impact. Industrial sectors, including power generation, transportation, and production factories, contribute most of the anthropogenic sources of CO₂ emissions. Researchers search for methods to mitigate these CO₂ emissions without compromising the benefits of industrial processes, including CO₂ capture, utilization, and sequestration (CCUS). Post-combustion carbon capture (PCCC) by amine scrubbing is the most technology ready CCUS, with various pilot-scale projects worldwide showing small-scale to fully operational plants. While researchers have made significant progress in amine scrubbing, they strive to improve the efficiency and …

Impact Of Common Face Mask Regeneration Processes On The Structure, Morphology And Aerosol Filtration Efficiency Of Porous Flat Sheet Polysulfone Membranes Fabricated Via Nonsolvent-Induced Phase Separation (Nips), Ebuka A. Ogbuoji, Anastasia Myers, Amber Haycraft, Isabel Escobar

UK CARES Faculty Publications

The potential of flat sheet polymeric membranes as a sustainable solution for reusable facemask filters was investigated by analyzing the effect of common face mask regeneration processes on polysulfone (PSf) membranes’ structure, morphology, and aerosol filtration efficiency. The impact of regeneration processes, such as isopropanol (IPA), detergent and bleach washes, and ultraviolet light exposure, was for the first time compared between surgical masks, N95 masks and flat sheet PSf membranes. The PSf membranes were fabricated via non- solvent induced phase separation (NIPS), and demonstrated a higher particulate filtration efficiency (99.06 ± 1.38%) for PM0.3 i.e., particulate matter of 0.3 μm …

Equine In Vivo Metabolite Profiling Of The Selective Androgen Receptor Modulator Lgd-3303 For Doping Control, Malin Nilsson Broberg, Heather Knych, Ulf Bondesson, Curt Pettersson, Börje Tidstedt, Scott Stanley, Mario Thevis, Mikael Hedeland

UK CARES Faculty Publications

LGD-3303 is a Selective Androgen Receptor Modulator (SARM) that is prohibited in both equine and human sports due to its anabolic properties. The aim of this study was to investigate the equine in vivo metabolite profile of LGD-3303 and identify drug metabolites that can be suitable as new and improved analytical targets for equine doping control. This was performed by an oral administration of 0.05 mg⋅kg 1 LGD-3303 to horses, where blood and urine samples were collected up to 96 h after administration. The in vivo samples consisting of plasma, urine and hydrolyzed urine were analyzed utilizing ultra-high performance liquid …

Long-Term Monitoring Of Clodronate In Equine Hair Using Liquid Chromatography-Tandem Mass Spectrometry, Heather K. Knych, D. S. Mckemie, S. Yim, S. D. Stanley, R. M. Arthur

UK CARES Faculty Publications

Given the potential for long-term inhibition of bone remodeling/healing and detrimental effects to horses in training, bisphosphonates are tightly regulated in horseracing. Hair has proven to be an effective matrix for detection of drug administration to horses and has been particularly effective in detecting drugs for a long period of time post administration. Thus, hair may prove to be a useful matrix for detection of administration of this class of drugs. The objective of the current study was to develop an assay and assess the usefulness of hair as a matrix for long-term detection of clodronate to horses. Seven horses …

The Kappa Opioid Receptor Agonist 16-Bromo Salvinorin A Has Anti-Cocaine Effects Without Significant Effects On Locomotion, Food Reward, Learning And Memory, Or Anxiety And Depressive-Like Behaviors, Ross Van De Wetering, Amy Ewald, Susan Welsh, Lindsay Kornberger, Samuel E. Williamson, Bryan D. Mcelroy, Eduardo R. Butelman, Thomas E. Prisinzano, Bronwyn M. Kivell

Markey Cancer Center Faculty Publications

Kappa opioid receptor (KOR) agonists have preclinical antipsychostimulant effects; however, adverse side effects have limited their therapeutic development. In this preclinical study, conducted in Sprague Dawley rats, B6-SJL mice, and non-human primates (NHPs), we evaluated the G-protein-biased analogue of salvinorin A (SalA), 16-bromo salvinorin A (16-BrSalA), for its anticocaine effects, side effects, and activation of cellular signaling pathways. 16-BrSalA dose-dependently decreased the cocaine-primed reinstatement of drug-seeking behavior in a KOR-dependent manner. It also decreased cocaine-induced hyperactivity, but had no effect on responding for cocaine on a progressive ratio schedule. Compared to SalA, 16-BrSalA had an improved side effect profile, with …

Investigating Visinin-Like Protein 1 And Ubiquitinated Visinin-Like Protein 1 As Mild Traumatic Brain Injury Biomarkers, Yueming Wu

Theses and Dissertations--Chemistry

Traumatic brain injury (TBI) continues to be a significant cause of morbidity and mortality worldwide. Despite significant progress in understanding the complex pathophysiology of TBI, the underlying mechanisms remain poorly understood. The primary brain damage is acute and irreversible. However, secondary brain injuries often develop gradually over months to years, creating an opportunity for critical therapeutic interventions. In the past decade, research on TBI biomarkers has seen significant progress. This progress has been driven by the diverse nature of TBI pathologies and the challenges they present for evaluation, management, and prognosis. TBI biomarker proteins resulting from axonal, neuronal, or glial …

Development Of An Effective Au:Pd Bimetallic Heterogeneous Catalyst For Oxidative Lignin Depolymerization To Low Molecular Weight Aromatics, Gayan P. Karunasinghe

Theses and Dissertations--Chemistry

The principal concept behind biorefining involves the transformation of lignocellulosic biomass into valuable products and energy resources. Historically, biorefinery strategies for lignocellulosic biomass have primarily focused on improving the conversion of cellulose into ethanol, often neglecting the underutilized lignin component. Lignin consists of phenolic subunits, from which it follows that value-added products can be obtained from lignin depolymerization. Unfortunately, lignin utilization is particularly challenging due to its high structural irregularity and recalcitrance. The goal of this study was to develop an AuPd/Li-Al layered double hydroxide (LDH) bimetallic catalyst for efficient lignin depolymerization, resulting in the production of high-value aromatic compounds. …

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 …

The Application Of Photoelectron Spectroscopies In Analyzing The Impact Of Interfacial Energetics On Perovskite Solar Cells, Tuo Liu

Theses and Dissertations--Chemistry

In recent years, organic-inorganic metal halide perovskites (HP) have garnered tremendous attention in photovoltaic research. This attention is attributed to their low cost and excellent optoelectronic properties, including large absorption coefficients, tunable bandgaps, long charge-carrier diffusion lengths, and low densities of deep trap states. Inverted p-i-n architecture perovskite solar cells (PSCs) are of intense interest and are generally regarded as more amenable to low-temperature solution processing. Nevertheless, the development of inverted PSCs is lagging the conventional architecture devices. Imperfect energy level alignments and charge carrier recombination, especially at the interface between perovskite and electron transport layers (ETLs), are two main …

Building Tools For Improved Modulation Of The Human Gabaa Receptor, A Central Nervous System Target For The Treatment Of Anxiety, Garrett Edward Zinck

Theses and Dissertations--Pharmacy

In the U.S., anxiety is recognized as an increasing range of mentally and physically debilitating psychiatric health disorders with significant economic repercussions. Over the last 20 years, several novel anti-anxiety therapies have entered the drug development pipeline, but none have made it to market.

The work in this dissertation focused on structurally modifying valerenic acid (VA), a structurally unique carboxylated sesquiterpene acid found in Valeriana officinalis. VA is putatively reported to have allosteric modulatory activity of the human GABA_A receptor, a ligand-gated ion channel responsible for attenuating neurotransmissions. Structural modeling of VA’s GABA_A receptor interaction suggests that …

Investigating The Physical Stability Of Amorphous Pharmaceutical Formulations, Travis W. Jarrells

Theses and Dissertations--Pharmacy

Amorphous formulations, including amorphous solid dispersions (ASDs), consisting of the active pharmaceutical ingredient (API) intimately mixed in a polymeric matrix, are an attractive formulation approach to improve drug delivery, dissolution, and solubility. However, an amorphous API in an ASD is in a higher energy state compared to the crystalline drug and results in most ASDs being inherently unstable. The polymer helps to stabilize the amorphous drug against crystallization such that the resulting homogenous mixture maintains its solubility advantage relative to the crystalline form. One challenge of ASDs is that the presence of impurities including crystals or residual solvent, variations in …

A Study Of The Analysis Of Hemp-Derived Oil Products: Development Of A Method For The Analysis Of Phytocannabinoids In Medicinal Products, Erin Johnson

Theses and Dissertations--Pharmacology and Nutritional Sciences

Human interactions with cannabis have a history spanning millennia as a source of fiber, food, and medicine. The plant came across Asia, Europe, and Africa with the movements of people and travelers eventually coming to the Americas with European explorers. In colonizing North America, cannabis fiber was key to the production of canvas and ropes for ships. Although fiber was the driver for cannabis production in the United States, medicinal uses were prevalent and propelled the eventual regulations. The Pure Food and Drug Act of 1906 mandated accurate labeling on drugs such as cannabis followed by the Marihuana Tax Act …

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 …

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 …

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 …

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 …

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 …

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: …

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 …

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 …