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Chemistry

Electronic Theses and Dissertations

2016

Articles 31 - 45 of 45

Full-Text Articles in Physical Sciences and Mathematics

Biophysical Characterization Of A Proline Mutant Of Neural Cadherin, Keshia S. Dykes Jan 2016

Biophysical Characterization Of A Proline Mutant Of Neural Cadherin, Keshia S. Dykes

Electronic Theses and Dissertations

Cadherins are calcium dependent glycoproteins whose homophilic interactions mediate cell-cell adhesion in solid tissues. They are comprised of an extracellular region, a transmembrane region and a cytoplasmic region. The extracellular region plays a critical role in cadherin-mediated cell adhesion, and has five tandemly repeated ectodomains (ec1-ec5), with three calcium binding sites situated in each interface between the domains. Dimerization of cadherin occurs through formation of adhesive interactions between extracellular domains of cadherins from neighboring cells. Adhesive interaction occurs at the interfaces of ec1 domains of two molecules originating from different cell surfaces. Dimerization is critically dependent on the binding of …

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Anodic Metal Dissolution In Haloaluminate Molten Salts/Ionic Liquids, Chen Wang Jan 2016

Anodic Metal Dissolution In Haloaluminate Molten Salts/Ionic Liquids, Chen Wang

Electronic Theses and Dissertations

The anodization of Aluminium was investigated in the low-melting, mixed halide molten salt system, lialbr4-naalcl4-kalcl4 (30-50-20 m/o), and in the Lewis acidic Chloroaluminate ionic liquid, aluminum chloride-1-ethyl-3-methylimidazolium chloride (alcl3-etmeimcl) using rotating disk electrode voltammetry. In both cases, at modest overpotentials, the anodization reaction proceeds under mixed kinetic/mass-transport control. However, at larger positive overpotentials and correspondingly higher anodization rates, the reaction transitions to a mass transport-limited process governed by the dissolution of a passive layer of alcl3(s) and/or albr3(s) on the electrode surface. In alcl3-etmeimcl, the passive current density scales linearly with the concentration of alcl4- in the ionic liquid. The …

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Characterization Of Charge Accommodation In Biologically Important Hydrogen-Bonded Clusters, John Thomas Kelly Jan 2016

Characterization Of Charge Accommodation In Biologically Important Hydrogen-Bonded Clusters, John Thomas Kelly

Electronic Theses and Dissertations

The underlying motivation of chemical physics and physical chemistry is to understand naturally occurring chemical and physical processes from the nanoscopic molecular level to the macroscopic condensed phase. Over the past half-century, experimentalists have developed a number of laser-based analytical techniques to bridge the gap between the bulk phase and the single molecule. Here, we look at bulk phase and gas phase clusters to compare the local hydrogen-bonded network. To better understand the role noncovalent interactions have on biologically relevant building blocks in a natural environment, we compare the microhydration of gas phase cluster ions to condensed phase spectra. The …

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Gas Exchange Of Hg Over Wetlands, Effect Of Biochar And Activated Carbon On Hg Emissions From Soil, And Seasonal Concentrations Of Hg In Rain, Divya Nallamothu Jan 2016

Gas Exchange Of Hg Over Wetlands, Effect Of Biochar And Activated Carbon On Hg Emissions From Soil, And Seasonal Concentrations Of Hg In Rain, Divya Nallamothu

Electronic Theses and Dissertations

Mercury (Hg) is a global pollutant with human-health and ecological impacts. Gaseous Hg exchange between the atmosphere and aquatic or terrestrial surfaces serves as an important, but not well understood, route for Hg to enter and exit ecosystems. To better understand the role of gaseous Hg exchange in the biogeochemical cycling of Hg, we investigated Hg0 fluxes over natural wetlands (Sky Lake) and artificial wetlands (UM Field Station) using a dynamic flux chamber and an Hg vapor analyzer based on atomic fluorescence (Chapter 1). We also examined the effect of activated carbon and biochar on Hg emissions from soils for …

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Environmentally Benign Extraction Processes In Analytical Separation Of Essential Oils, John Kiratu Jan 2016

Environmentally Benign Extraction Processes In Analytical Separation Of Essential Oils, John Kiratu

Electronic Theses and Dissertations

Supercritical fluid extraction (SFE) technology has been well received as an environmentally friendly processing technique. Over the last two decades, its use in many processing industries has tremendously advanced. This is as a result of pressure from regulating bodies aimed at reducing the wide-scale use of organic solvents due to negative environmental impacts. Supercritical carbon dioxide (SC-CO2) is considered to be environmentally benign and has been used in the development of a wide-range of alternative processes in various industries to totally or partially eliminate the use of organic solvents. Conventional processes for essential oil extraction involve steam distillation and organic …

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Functional Effects Of Calcium Regulation Of Thin Filaments At Single Particle Resolution, Christopher Solis-Ocampo Jan 2016

Functional Effects Of Calcium Regulation Of Thin Filaments At Single Particle Resolution, Christopher Solis-Ocampo

Electronic Theses and Dissertations

Heart disease is the leading cause of death in the United States. Understanding heart function at the molecular level is critical for developing of more effective treatments. In the cardiac muscle, the thin filament is composed by troponin (Tn), tropomyosin (Tm), and F-actin. It provides Ca2+-dependent regulation of contraction by modulating myosin attachment and force generation in a cooperative scheme. However, this mechanism remains unclear. To understand thin filament activation, we studied the binding and functional properties of Tn and Tm to F-actin at single particle resolution by employing fluorescence image colocalization, in vitro motility assays, and Förster resonance energy …

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Degradation Of Hexachlorobenzene, Pentachlorophenol And Pentachloroanisole Using Activated Magnesium In An Acidified Ethanol/Ethyl Lactate Cosolvent System, Amel Garbou Jan 2016

Degradation Of Hexachlorobenzene, Pentachlorophenol And Pentachloroanisole Using Activated Magnesium In An Acidified Ethanol/Ethyl Lactate Cosolvent System, Amel Garbou

Electronic Theses and Dissertations

For many centuries, chemists have dedicated many labor-intensive hours to improving the quality of life for mankind by developing synthetic methods for the production of compounds which fulfill the needs and meet the demands of society. However, the innovation of such compounds has frequently come at the cost of detrimental side-effects that do not always present themselves until many years, or even decades, following their initial application. Many compounds in this category come in the form of globally-distributed halogenated molecules which are toxic to many living organisms, susceptible to bioaccumulation and resistant to biodegradation processes. Such compounds are classified as …

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Mechanistic Studies Of The Structure-Photostability Relationship Of Organic Conjugated Polymers, Logan Paul Sanow Jan 2016

Mechanistic Studies Of The Structure-Photostability Relationship Of Organic Conjugated Polymers, Logan Paul Sanow

Electronic Theses and Dissertations

Organic Conjugated polymers (CPs) are a subject of intense research for their application in organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), solid-state dye lasing, biological imaging and sensing, chemical sensing and remote sensing. CPs are key materials in the quest for more sustainable forms of renewable energy, making electronics more versatile and light weight, and increasing the functionality of everyday materials. For these applications and others that use CPs as the photoactive material, one of their main drawbacks is their susceptibility to photodegradation. Photodegradation occurs when the material is exposed to light leading to irreversible changes in the materials, …

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Investigation Of Neural And Epithelial Cadherin Monomer Properties Using A Molecular Dynamics Approach, Lianyi Fan Jan 2016

Investigation Of Neural And Epithelial Cadherin Monomer Properties Using A Molecular Dynamics Approach, Lianyi Fan

Electronic Theses and Dissertations

Neural and epithelial cadherin are adhesion proteins intensely studied by our lab. Although the sequence, structure, and conformation are similar for the two cadherins, there are several physical properties that differ: dimerization affinity, dimerization kinetics, intermediate structure, and critical residues for dimerization. In the presence of calcium, cadherins are in equilibrium between monomeric and dimeric states, and the scope of this thesis focuses on monomeric cadherin. These molecular dynamics evaluations are based on the testing of specific hypotheses regarding the intramolecular interactions of neural and epithelial cadherin. We particularly focus on interactions involving critical residues at the N-terminus of the …

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Synthesis And Characterization Of Anhydrous Proton Conducting Polymer Electrolytes For Fuel Cell Applications, Buddika Mayomi Liyanage Jan 2016

Synthesis And Characterization Of Anhydrous Proton Conducting Polymer Electrolytes For Fuel Cell Applications, Buddika Mayomi Liyanage

Electronic Theses and Dissertations

Anhydrous H+ ion conducting and high temperature capability of polymer electrolytes are being investigated for use in applications such as batteries, fuel cells, electro chromic windows and light emitting devices. Fuel cells are efficient electrochemical energy conversion devices; they can generate greener energy from chemical fuels. The polymer electrolyte membrane is heart of most fuel cell designs separating the oxidant and fuel chambers and providing the medium to conduct H+ ions between the anode and the cathode. Our goal is to understand the molecular level details of anhydrous H+ conductivity through the synthesis and characterization of polymer electrolytes based on …

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Gold And Silver Alloy Nanoparticles: Synthesis, Characterization And Atomic Structure, Chanaka Kapila Kumara Jan 2016

Gold And Silver Alloy Nanoparticles: Synthesis, Characterization And Atomic Structure, Chanaka Kapila Kumara

Electronic Theses and Dissertations

Nanotechnology is an emerging field of science with applications in digital electronics, medicine, catalysis and energy. Gold nanoparticles are nanomaterials that have less than 100 nm at least in one dimension. The composition and the structure/geometry of the nanoparticles determine the chemical properties and reactivity. Modern research focus on method development in atomically monodisperse nanoparticle synthesis. This dissertation describes the method development for synthesis and isolation of atomically precise gold and gold-silver alloy nanoparticles and their comprehensive characterization and atomic structure investigation. Chapter one offers an introduction to the synthesis and isolation methods. These nanoparticles can be represented in the …

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Ice Concentration Linked With Extractive Stirrer (Icecles), Nujud Omar Maslamani Jan 2016

Ice Concentration Linked With Extractive Stirrer (Icecles), Nujud Omar Maslamani

Electronic Theses and Dissertations

Clean water is very important for human health. Therefore, drinking water contamination is a significant research concern, especially with the increasing global population. Some contaminants, such as pesticides, can cause health effects even at low levels. Therefore, trace and ultratrace analysis of contaminants in drinking water is essential. Ultratrace analysis typically requires highly effective sample preparation methods and/or highly sensitive instruments. There are currently advanced sample preparations techniques available to analytical chemists that may allow trace analysis of certain analytes. These include liquid-liquid extraction (LLE), solid phase extraction (SPE), solid phase micro extraction (SPME), and stir bar sorpitive extraction (SBSE). …

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Use Of Extraction Technologies In Food Safety Studies, Changling Qiu Jan 2016

Use Of Extraction Technologies In Food Safety Studies, Changling Qiu

Electronic Theses and Dissertations

Food safety has become a top concern in our society. The public in general is increasingly concerned about the safety of the food products they consume every day as more and more food contamination incidents and widespread recalls arise. It is necessary to trace any presence and/or the concentration levels of contaminants, pesticides, herbicides, or other harmful substances in food samples. Sample preparation is a crucial step in a food analytical method, as it takes up most of the total analysis time, contributing highly to the total cost of analysis and greatly influencing the results of the analysis. Traditional extraction …

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Raft Polymerization Of Ph-Responsive, Diblock Copolymers For Nucleic Acid Delivery Vehicles, Annie Katherine Mcclellan Jan 2016

Raft Polymerization Of Ph-Responsive, Diblock Copolymers For Nucleic Acid Delivery Vehicles, Annie Katherine Mcclellan

Electronic Theses and Dissertations

Since the development of gene therapy, a variety of non-viral nucleic acid delivery vehicles have been prepared and studied for their transfection efficiencies. Recently, polymeric gene delivery vehicles have gained popularity for their low immunogenicity and high transfection efficiency. With the advent of controlled radical polymerization (CRP) and more specifically reversible addition-fragmentation chain transfer (RAFT) polymerization, it is now possible to develop well-defined polymers with predicted molecular weights and architectures. The work presented here focuses on the RAFT polymerization of a family of amphiphilic, cationic copolymers to be utilized for nucleic acid delivery. These copolymers are composed of a stabilizing …

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Robust Nickel Catalysts Supported By Biaryl-Bridged Pyridyl-N-Heterocyclic Carbenes For Carbon Dioxide Reduction To Value-Added Products, Hunter Allen Dulaney Jan 2016

Robust Nickel Catalysts Supported By Biaryl-Bridged Pyridyl-N-Heterocyclic Carbenes For Carbon Dioxide Reduction To Value-Added Products, Hunter Allen Dulaney

Electronic Theses and Dissertations

Carbon dioxide is a greenhouse gas, but also represents a readily accessible C1 feedstock for conversion to solar fuels and value-added chemicals. However, CO2 is relatively inert and very negative voltages or strong chemical reductants are comfor its conversion. An additional challenge lies in achieving these reactions in water where aqueous protons are utilized selectively for CO2 reduction rather than hydrogen generation. Our strategy for CO2 reduction involves the design of new homogeneous catalysts with tunable geometries and polyaromatic frameworks with increased delocalization to lower overpotentials for catalysis. We report a family of biaryl-bridged pyridyl-N-heterocyclic carbene-based ligands and their corresponding …

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