Chemistry Commons^™

Action Potentials As Indicators Of Metabolic Perturbations For Temporal Proteomic Analysis, Aditya Reddy Kolli

Electronic Theses and Dissertations

The single largest cause of compound attrition during drug development is due to inadequate tools capable of predicting and identifying protein interactions. Several tools have been developed to explore how a compound interferes with specific pathways. However, these tools lack the potential to chronically monitor the time dependent temporal changes in complex biochemical networks, thus limiting our ability to identify possible secondary signaling pathways that could lead to potential toxicity. To overcome this, we have developed an in silico neuronal-metabolic model by coupling the membrane electrical activity to intracellular biochemical pathways that would enable us to perform non-invasive temporal proteomics. …

Multifunctional And Responsive Polyelectrolyte Nanostructures, Astha Malhotra

Electronic Theses and Dissertations

A polyelectrolyte complex is formed by mixing two oppositely charged polyelectrolytes in a solution. The electrostatic interactions between partially charged polymeric chains lead to the formation of a stable complex while avoiding the use of covalent cross linkers. Since complex formation can improve the stability of polyelectrolyte and metal ions in polyelectrolyte can provide various functionalities, PECs incorporated with metal ions are promising candidates for manufacturing stable and multifunctional structures. While the coordination of metal ions and polyelectrolytes has been extensively investigated in solutions and multilayer films, to our knowledge, no research has been performed to study the effect of …

Molecular Characterization Of Atmospheric Organic Matter In Biogenic Secondary Organic Aerosol, Ambient Aerosol And Clouds, Yunzhu Zhao

Dissertations, Master's Theses and Master's Reports - Open

Atmospheric aerosol affects the Earth’s energy budget, reduces visibility and influences human health. The organic composition of aerosol is quite complex and continuously evolves through various atmospheric processes. To gain a deeper understanding of the molecular composition of atmospheric organic matter (AOM), chamber-generated biogenic secondary organic aerosol (SOA), ambient aerosol and cloud water samples were studied. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry was used to provide detailed molecular characterization of the atmospheric samples. Due to the extremely high mass resolution and mass accuracy, thousands of individual molecular formulas were identified in all of the samples studied. Multivariate …

Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica

Dissertations, Master's Theses and Master's Reports - Open

Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …

Modeling Dynamics Of Ozone And Nitrogen Oxides At Summit, Greenland With A 1-D Process-Scale Model, Keenan Anton Murray

Dissertations, Master's Theses and Master's Reports - Open

This work presents a 1-D process scale model used to investigate the chemical dynamics and temporal variability of nitrogen oxides (NO_x) and ozone (O₃) within and above snowpack at Summit, Greenland for March-May 2009 and estimates surface exchange of NO_x between the snowpack and surface layer in April-May 2009. The model assumes the surface of snowflakes have a Liquid Like Layer (LLL) where aqueous chemistry occurs and interacts with the interstitial air of the snowpack. Model parameters and initialization are physically and chemically representative of snowpack at Summit, Greenland and model results are compared to …

Electron And Ion Spectroscopy Of Metal Hydrocarbon Complexes, Sudesh Kumari

Theses and Dissertations--Chemistry

Metal-hydrocarbon complexes were prepared in a laser-vaporization molecular beam source and studied by single-photon zero electron kinetic energy (ZEKE) and mass-analyzed threshold ionization (MATI) spectroscopy. The ionization energies and vibrational frequencies of the metal complexes were measured from the ZEKE and MATI spectra. Metal-ligand bonding and low-lying electronic states of the neutral and ionized complexes were analyzed by combining the spectroscopic measurements with quantum chemical calculations and spectral simulations.

In this dissertation, the metal complexes of mesitylene, aniline, cyclooctatetraene, benzene, ethene, and propene were studied. For each complex, different effects from metal coordination have been identified. Although metal-bis(mesitylene) sandwich complexes …

Structures And Electronic States Of Small Group 3 Metal Clusters, Lu Wu

Theses and Dissertations--Chemistry

Group 3 metal clusters are synthesized by laser vaporization in a pulsed cluster beam source and identified with laser ionization time-of-flight mass spectrometry. The adiabatic ionization energies and vibrational frequencies of these clusters are measured using mass-analyzed threshold ionization (MATI) spectroscopy. Their structures and electronic states are determined by combining the MATI spectra with quantum chemical calculations and spectral simulations. This dissertation focuses on the study of several small molecules, which include LaO₂, La₂, M₂O₂, M₃O₄, M₃C₂, and La₃C₂O, where …

Electrode And Electrolyte Additives For Lifetime Extension In Lithium-Ion Batteries, Kishore Anand Narayana

Theses and Dissertations--Chemistry

Lithium-ion batteries (LIBs) are the most commonly used type of rechargeable batteries with a global market estimated at $11 billion, which is predicted to grow to $60 billion by 2020. The global commercialization of Li-ion batteries is impeded by issues such as poor cycle life (5000 cycles achieved in some LIBs) in high energy and power density applications because of the rising internal resistance due to aging and safety concerns such as overcharge which ultimately leads to thermal runaway and explosions. A battery’s performance mainly depends on external factors such as electrode thickness and degree of compacting, and the type …

A Study Of Lignin Depolymerization By Selective Cleavage Of The Cα-Cβ Linkages In Lignin Model Compounds Via Baeyer-Villiger Oxidation & An Investigation Of The Channeling Reaction In Nitrogen-Doped Multiwalled Carbon Nanotubes (N-Mwcnts), Nikhil Dilip Patil

Theses and Dissertations--Chemistry

A STUDY OF LIGNIN DEPOLYMERIZATION BY SELECTIVE CLEAVAGE OF THE Cα-Cβ LINKAGES IN LIGNIN MODEL COMPOUNDS VIA BAEYER-VILLIGER OXIDATION

Lignin is amorphous aromatic polymer derived from plants and is a potential source of fuels and bulk chemicals. Herein, we present a survey of reagents for selective stepwise oxidation of lignin model compounds. Specifically, we have targeted the oxidative cleavage of Cα-Cβ bonds as a means to depolymerize lignin and obtain useful aromatic compounds. In this work, we prepared several lignin model compounds that possess structures, characteristic reactivity, and linkages closely related to the parent lignin polymer. We observed that selective …

Cross Photoreaction Of Pyruvic And Glyoxylic Acids In Model Aqueous Aerosols, Shasha Xia

Theses and Dissertations--Chemistry

Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. Aerosols from natural and anthropogenic sources can be primary organic aerosols (POA), which are directly emitted to the atmosphere, or secondary organic aerosols (SOA) that are formed from chemical reactions of gas-phase precursors. At variance with the well investigated formation of SOA from gas phase precursors, the chemistry of aqueous SOAs that contribute to the total SOA budget remains unknown. Field measurements have revealed that carboxylic, dicarboxylic and oxocarboxylic acids are abundant species present in SOAs. This thesis …

Salen Aluminum Compounds In The Dealkylation And Detection Of Organophosphates, Rahul R. Butala

Theses and Dissertations--Chemistry

The focus of this dissertation is the use of aluminum Schiff base compounds, Salen(^tBu)AlBr (SAB), in the dealkylation and detection of organophosphates (OPs). Three SAB compounds, Salen(^tBu)AlBr (1), Salpen(^tBu)AlBr (2), and Salophen(^tBu)AlBr (3) were used to dealkylate a variety of trialkyl OPs. These reactions lead to unique organic-soluble aluminum phosphate compounds containing six-coordinate aluminum. Examples include [salen(^tBu)AlOP(O)(OCH₃)₂]_n (4), [salen(^tBu)AlOP(O)(OCH₂CH₃)₂]_n (5), [salen(^tBu)AlOP(O)(OPh)₂]_{n …}

Methods Development In Biological Mass Spectrometry: Application In Glycoproteomics, Sanja Trajkovic

Theses and Dissertations--Chemistry

Proteomics refers to global characterization of the full set of proteins present in a biological sample. Various analytical disciplines contribute to proteomics but mass spectrometry became method of choice for analysis of complex protein samples.

Mass spectrometry allows for high throughput analysis of the proteome but, moreover, it has the ability to acquire higher-order information such as post-translational modifications (PTM). Glycosylation is the most abundant PTM on eukaryotic proteins.

This dissertation will focus on method development for structural proteomics that will be utilized to explain the glycoproteome of obligate intracellular protozoan parasite Toxoplasma gondii as a model system.

Optimization of …

Laser Spectroscopy Of Radicals Containing Group Iiia And Va Elements, Robert A. Grimminger

Theses and Dissertations--Chemistry

Radicals are interesting to study because of importance in so many processes such as semiconductor growth or stellar evolution. Laser induced fluorescence (LIF) and wavelength resolved emission spectra of jet cooled HPS, HAsO, AsD₂, H₂PS, and F₂BO have been measured using the pulsed discharge jet technique.

Several bands in the à ¹A′′ − X̃ ¹A′ transition of HPS were observed and assigned with the help of ab initio calculations. The ab initio geometries showed that HPS does not follow Walsh’s predictions for the angle change upon electronic excitation; Walsh predicts an increase …

Nuclear Structure In Transitional Regions: Studies Of ¹³²,¹³⁴Xe And Lifetimes In The Stable Zr Nuclei With The (N,N′Γ) Reaction, Erin Elizabeth Peters

Theses and Dissertations--Chemistry

Nuclei at closed shells tend to be spherical and are well-described by the shell model, while those between closed shells are deformed and better described by collective models. The nuclei which are in transitional regions between spherical and deformed may be studied to gain insight into the nature of this transition. The stable isotopes of zirconium and xenon span such transitional regions and are the subject of this dissertation. Gamma-ray spectroscopy following inelastic neutron scattering has been performed on the stable isotopes of Zr as well as ^132,134Xe at the University of Kentucky Accelerator Laboratory. Level lifetimes have been …

Applications Of Gas Chromatography/Mass Spectrometry And Capillary Electrophoresis For The Analysis Of Lignocellulosic Biomass Pretreatment, Dawn M. Kato

Theses and Dissertations--Chemistry

The focus of this dissertation centers on the development and applications of gas chromatography/mass spectrometry and capillary electrophoresis methodologies to quantify monomeric compositions of the β-O-4 linkages in lignin. Pretreatment is a required step in the utilization of lignocellulosic biomass for biofuels. Lignin is the target of pretreatment because it hinders the accessibility of enzymes and chemicals to cellulose. The effects of pretreatment are commonly assessed utilizing enzymatic saccharification and lignin assays. However, these techniques do not elucidate the effects of pretreatment on the monomeric make up of lignin.

The overarching hypothesis of this dissertation is that changes in individual …

Temperature-Dependent Tunable Photoluminescence Properties Of Carbon Nanodots Derived From Polyethylene Glycol, Sin Hea Yeom

Theses and Dissertations--Chemistry

Fluorescent carbon dots (C-dots) are well known for their low cell-cytotoxicity, biocompatibility, low preparation cost, excitation dependent photoluminescence, and excellent photostability. Typically, raw C-dots have low quantum efficiency and thus researchers have been utilizing biocompatible polymers such as polyethylene glycol (PEG) as a passivation agent in order to increase fluorescence signal. In this work, we report fluorescent self-passivated carbon nanodots (CNDs) synthesized from PEG by using it as a carbon source as well as a passivating agent. Importantly, the addition of graphene quantum dots (GQDs) during the synthesis of self-passivated CNDs can tune photoluminescence property. The results of bioimaging and …

Addressing Public Health Risks Of Persistent Pollutants Through Nutritional Modulation And Biomimetic Nanocomposite Remediation Platforms, Bradley J. Newsome

Theses and Dissertations--Chemistry

Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation …

Wetlands And Greenhouse Gas Fluxes: Causes And Effects Of Climate Change – A Meta-Analysis, Robert E. Ventura

Pomona Senior Theses

Climate change is one of the largest problems facing this generation. Anthropogenically caused increases of greenhouse gas emissions is a significant culprit to this problem. Although the obvious problems such as cars, industry, and urbanism garnish a significant amount of the criticism, natural sources such as wetlands are also beginning to contribute to this issue. This is becoming increasingly significant as wetlands shift from being sinks of greenhouse gases to becoming sources as various anthropogenic impacts, including global warming itself, begin to affect the health of the wetlands. The aim of this project is to look at four common types …

Improved Synthesis, Separation, Transition Metal Coordination And Reaction Chemistry Of A New Binucleating Tetraphosphine Ligand, Ekaterina Kalachnikova

LSU Doctoral Dissertations

The first chapter of this dissertation involves discussion of alkene hydration and oxidative cleavage reactions catalyzed by late transition metal complexes. Previously reported results are summarized here. Mechanistic aspects of alkene hydration catalyzed by late transition metal complexes are also explained. The second part of Chapter 1 focuses on motivation for using bimetallic nickel phosphine complexes as possible catalytic precursors for alkene hydration. Chapter 2 describes studies into alkene hydration in the presence of catalytic amounts of dinickel phosphine complexes based on linear tetraphosphine ligand, PEt2CH2CH2(Ph)PCH2P(Ph)CH2CH2PEt2, et,ph-P4. Under conditions tested no alcohol products were detected. However we have observed formation …

Matrices From Vegetable Oils, Cashew Nut Shell Liquid, And Other Relevant Systems For Biocomposite Applications, Rafael Quirino, Thomas Garrison, Michael Kessler

Chemistry: Faculty Publications (1990-2023)

The partial replacement of petroleum-derived plastics and composites by novel bio-based materials from inexpensive, renewable, natural resources has the potential to greatly impact the plastics, coatings, and composites industries. Natural starting materials are usually abundant and renewable on a time scale many orders of magnitude smaller than petroleum. These characteristics, in combination with good mechanical properties, make the design of bio-based composites an interesting strategy for lowering the environmental impact of the plastics and composites industries while maintaining economical competitiveness. The present review will focus on the progress made over the last decade in the development of a select group …

Investigation Of Fluids Flow Behavior In Nano-Scale Channels By Using Optic Imaging System, Qihua Wu

Doctoral Dissertations

"Tight gas and shale gas reservoirs are characterized to have small pores with diameters in nanometer (nm) range. The physics of fluid flow in nanopores is poorly understood. Knowing the fluid flow behavior in the nano-range channels is of major importance for stimulation design, gas production optimization and calculations of the relative permeability of gas in tight shale gas systems. In this work, a lab-on-chip approach for direct visualization of the fluid flow behavior in nano-scale channels was developed using an advanced epi-fluorescence microscopy method combined with a nano-fluidic chip. The nanofluidic chips with different dimensions were designed and fabricated. …

Manufacturing Of Vegetable Oils-Based Epoxy And Composites For Structural Applications, Rongpeng Wang

Doctoral Dissertations

"Epoxidized vegetable oil (EVO) is one of the largest industrial applications of vegetable oils (VOs) and is widely used as a plasticizer and as a synthetic intermediate for polyol or unsaturated polyester. However, the utility of EVO as monomer for high performance epoxy thermoset polymer is limited by its reactivity and by the resulting physical properties. Herein, VO-based epoxy monomers, i.e., glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS) or linseed oil (EGL), have been synthesized and were benchmarked against commercial available diglycidyl ether of bisphenol A (DGEBA) and also epoxidized soybean oil (ESO) controls. EGS and …

Synthesis And Properties Of Transition-Metal Arsenide Nanostructures: From Superparamagnetism To Superconductivity, Prachi Desai

Doctoral Dissertations

"This dissertation study focuses on developing new protocols for synthesis of nanostructured transition-metal pnictides including superconducting LiFeAs and studying their structure- property relationship. Nanostructured materials are known to differ in properties compared to their bulk counterparts owing to enhanced surface area and increased packing efficiency in devices. Synthetic chemistry skills and nanofabrication techniques like wet chemistry, electrodeposition, solvothermal, hydrothermal and lithography, are extremely useful for creating nanostructures of these functional materials. This is a challenging task simply because maintaining the phase composition same as that of the bulk material along with achieving nanostructures (nanoparticles, nanowires, nanopillars etc.) simultaneously is not …

Part I: In-Situ Fluorometric Quantification Of Microalgal Neutral Lipids Part Ii: Thermal Degradation Behavior Of Investment Casting Polymer Patterns, Hongfang Zhao

Doctoral Dissertations

"Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents …

Semiconductor Nanocrystals For Novel Optical Applications, Jong-Sik Moon

Doctoral Dissertations

“Inspired by the promise of enhanced spectral response, photorefractive polymeric composites photosensitized with semiconductor nanocrystals have emerged as an important class of materials. Here, we report on the photosensitization of photorefractive polymeric composites at visible wavelengths through the inclusion of narrow band-gap semiconductor nanocrystals composed of PbS. Through this approach, internal diffraction efficiencies in excess of 82%, two-beam-coupling gain coefficients in excess of 211 cm^-1, and response times 34 ms have been observed, representing some of the best figures-of-merit reported on this class of materials. In addition to providing efficient photosensitization, however, extensive studies of these hybrid composites …

A Molecular-Level Approach For Characterizing Water-Insoluble Components Of Ambient Organic Aerosol Particulates Using Ultrahigh-Resolution Mass Spectrometry, A. S. Willoughby, A. S. Wozniak, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions. The effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and therefore the associated properties and the impacts they have. Many studies have addressed the watersoluble fraction of organic aerosols and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of …

Aerogels As Diverse Nanomaterials, Abhishek N. Bang

Doctoral Dissertations

"Aerogels are 3-D light-weight nanoporous materials pursued for their low thermal conductivity, low dielectric constant and high acoustic attenuation. Those exceptional macroscopic properties of aerogels are dependent on the chemical nature of nanoparticles, complex hierarchical solid skeletal framework and porosity. Also, the free space can become host for functional guests such as pharmaceuticals. In chapter I, we investigated randomly mesoporous bio-compatible polymer-crosslinked dysprosia aerogels as drug delivery vehicles and demonstrated storage and release of drugs under physiological conditions. Comparative study with ordered and randomly mesoporous silica showed high drug uptake and slower release rate for random nanostructures (silica or dysprosia) …

Retrievals Of Carbonyl Fluoride (Cof₂) From Ace-Fts And Mipas Spectra And Their Comparison With Slimcat Ctm Calculations, Jeremy Harrison, Shaomin Cai, Anu Dudhia, Martyn Chipperfield, Chris Boone, Peter Bernath

Chemistry & Biochemistry Faculty Publications

The majority of fluorine in the atmosphere has resulted from the anthropogenic emission of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Most tropospheric fluorine is present in its emitted 'organic' form due to the molecules having long lifetimes. At the top of the stratosphere most of the fluorine is present as the 'inorganic' product HF, which, due to its extreme stability, is an almost permanent reservoir of stratospheric fluorine. The second most abundant stratospheric 'inorganic' fluorine reservoir is carbonyl fluoride (COF₂). The major sources of COF₂ are from the atmospheric degradation of CFC-12 (CCl₂F₂), which is now banned under the …

Graphite Aerogels And The Formation Mechanism Of Unusual Micron-Sized Rod And Helical Structures, Clarissa Ann Wisner

Doctoral Dissertations

"Pyrolysis at 800 ºC under argon has shown that polyimide (PI), polyacrylonitrile (PAN), polydicyclopentadiene (DCPD) and polybenzoxazine (PBO) aerogels are all viable alternatives to traditional resorcinol-formaldehyde (RF) aerogels as precursors to amorphous carbon aerogels. Subsequent high temperature pyrolysis at 2300 ºC of such carbon aerogels under helium has shown that amorphous carbon from PI and PBO yields the highest degree of graphitization, whereas from RF aerogels yields the lowest.

Those two types of graphite aerogels include also a high concentration of micron-size columnar and helical (screw-like) structures, whose formation is favored by macroporosity and high nitrogen retention in the 800 …

Beam-Energy Dependence Of Charge Separation Along The Magnetic Field In Au + Au Collisions At Rhic, L. Adamczyk, J. K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev, A. Banerjee, D. R. Beavis, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, H. Bichsel, M. Zyzak, Et Al., Star Collaboration

Physics Faculty Publications

Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with …