Chemistry Commons^™

Investigation Of Water-Molecule Complexes And Their Catalytic Effect On Important Atmospheric Reactions, Taylor Scott Cline

Theses and Dissertations

This dissertation is a collection of works that investigates issues related to environmental chemistry. The first portion of this research explores the role of water vapor on the kinetics of important atmospheric reactions. Work is presented on the self-reaction of β-hydroxyethyl peroxy radical (β-HEP) and the catalytic increase in reaction rate by water vapor. β-HEP serves as a model system for investigating the possible role of water vapor in perturbing the kinetics and product branching ratio of atmospheric reactions of other alkyl peroxy radicals. The self-reaction rate coefficient of β-HEP was investigated between 276-296 K with 1.0 × 10^15 to …

Miniaturized Electrostatic Ion Beam Trap Mass Analyzer, Junting Wang

Theses and Dissertations

The electrostatic ion beam trap (EIBT) was designed by D. Zajfman during the previous decade. This ion trap combines many properties of the Fourier-transform ion cyclotron resonance (FTICR) mass analyzer and time-of-flight (TOF) mass analyzer. There are several advantages for the electrostatic ion beam trap. First, large mass-to-charge particles in an electrostatic field could be easier to analyze. Second, there is a folded flight path, which could make the mass analyzer smaller compared to conventional TOF mass analyzer. This principle of operation of this ion trap is analogous to an optical resonator. The ions are trapped in a voltage valley …

Identification And Differentiation Of Tier 1 Bacterial Agents Using Gas Chromatography-Mass Spectrometry, Dan Li

Theses and Dissertations

A simple method was developed for detection and differentiation of five Tier 1 bacterial agents, including Bacillus anthracis, Francisella tularensis, Yersinia pestis, Burkholderia pseudomallei and Burkholderia mallei as well as their closely related near neighbors by gas chromatography-mass spectrometry (GC-MS). Generally, different classes of compounds can be used as biomarkers for biowarfare agent detection, including nucleic acids (i.e., DNA or RNA), proteins (i.e., antibodies), carbohydrates (i.e., sugars), lipopolysaccharides, lipids (i.e., fatty acids) and small molecules. One-step thermochemolysis (TCM) was developed to provide GC-MS detectable biomarker signatures, including sugars, fatty acids and small molecules. Solid phase micro-extraction (SPME) was used for …

Bacterial Spores Remain Viable After Electrospray Charging And Desolvation, Sara Nielson Pratt

Theses and Dissertations

The electrospray survivability of B. subtilis spores and E. coli was tested in atmospheric mobility experiments. E. coli did not survive electrospray charging and desolvation, but B. subtilis did. Experimental conditions ensured that any surviving bacteria were charged, desolvated, and de-agglomerated. B. subtilis was also found to survive both positive and negative electrospray and subsequent introduction into vacuum conditions. Attempts were made to measure the charge distribution of viable B. subtilis spores using electrostatic deflection. From those experiments, it was found that either the spores do not become highly charged under the electrospray conditions used or only spores in a …

Isolation, Characterization And Synthesis Of Asthma Inducing Fungal Glycolipid And Analytical Method Development For Novel Antimicrobial Peptide Mimics, Vinod Chaudhary

Theses and Dissertations

NKT cells are an important part of human immune system and recognize a specific set of antigens called glycolipids. Only a handful of "natural" NKT cell antigens are known till date. Although NKT cells play a protective role against pathogenic organisms, imbalances in NKT cell functions are implicated in many diseases including asthma. Allergic asthma, a Th2 driven inflammation of airways, is primarily caused by inhalation of environmental allergens. In the last decade, inhaled allergen Aspergillus fumigatus has been under scrutiny for the presence of NKT cell antigens that might trigger asthma. We successfully isolated, characterized and synthesized a "natural" …

Synthesis And Immunological Evaluation Of Type I, Type Ii, And Gamma Delta Nkt Cell Antigens, Brian L. Anderson

Theses and Dissertations

The purpose of the immune system is to protect our bodies from infection. One way it accomplishes this task is through the presentation of foreign pathogens to NKT cells. After an antigen is presented to the T cell receptor, activated NKT cells quickly release soluble chemical signals, termed chemokines and cytokines, that modulate the response of the immune system. Due to the immunological relevance of NKT cell activation, we developed and synthesised non-natural analogs of immunostimulatory type I, II, and gamma delta NKT cell antigens. The immunological evaluations of these analogs resulted in identification of sulfatide as a gamma delta …

Binding Energies And Solvation Of Organic Molecular Ions, Reactions Of Transition Metal Ions With, And Plasma Discharge Ionization Of Molecular Clusters, Isaac Kwame Attah

Theses and Dissertations

In this dissertation, different approaches have been employed to address the quest of understanding the formation and growth mechanisms of carbon-containing molecular ions with relevance to astrochemistry. Ion mobility mass spectrometry and DFT computations were used to investigate how a second nitrogen in the pyrimidine ring will affect the formation of a covalent bond between the benzene radical cation and the neutral pyrimidine molecule, after it was shown that a stable covalent adduct can be formed between benzene radical cation and the neutral pyridine. Evidence for the formation of a more stable covalent adduct between the benzene radical cation and …

Kinetics Of Atmospheric Reactions Of Biogenic Volatile Organic Compounds: Measurement Of The Rate Constant Ofthujone + Cl· At 296 K And Calculation Ofthe Equilibrium Constant For The Ho2ch2ch2o2· H2o Complex, Marie Coy Killian

Theses and Dissertations

Biogenic volatile organic compounds (VOCs) react with Cl and OH radicals and the resulting radicals combine with oxygen to form peroxy radicals RO2. Organic peroxy radicals can then react with NO to form NO2, a precursor of tropospheric ozone. The work presented here explored the initial reaction between Cl and thujone, a VOC emitted by Great Basin sagebrush. The rate constant for the reaction of thujone + Cl at 296 K was measured with the method of relative rates with FTIR for detection of reactants. LEDs were used to photolyze Cl2 to generate Cl in the reaction cell. Thujone was …

Formation Mechanisms And Photocatalytic Properties Of Zno-Based Nanomaterials, Natalie Herring

Theses and Dissertations

Zinc Oxide (ZnO) is one of the most extensively studied semiconductors because of its unique properties, namely, its wide band gap (3.37 eV) and high excitation binding energy (60 meV). These properties make ZnO a promising material for uses in a broad range of applications including sensors, catalysis and optoelectronic devices. The presented research covers a broad spectrum of these interesting nanomaterials, from their synthesis and characterization to their use as photocatalyts. A new synthetic approach for producing morphology controlled ZnO nanostructures was developed using microwave irradiation (MWI). The rapid decomposition of zinc acetate in the presence of a mixture …

Graphene-Based Semiconductor And Metallic Nanostructured Materials, Abdallah Zedan

Theses and Dissertations

Exciting periods of scientific research are often associated with discoveries of novel materials. Such period was brought about by the successful preparation of graphene which is a 2D allotrope of carbon with remarkable electronic, optical and mechanical properties. Functional graphene-based nanocomposites have great promise for applications in various fields such as energy conversion, opteoelectronics, solar cells, sensing, catalysis and biomedicine. Herein, microwave and laser-assisted synthetic approaches were developed for decorating graphene with various semiconductor, metallic or magnetic nanostructures of controlled size and shape. We developed a scalable microwave irradiation method for the synthesis of graphene decorated with CdSe nanocrystals of …

Facile Synthesis And Improved Pore Structure Characterization Of Mesoporous Γ-Alumina Catalyst Supports With Tunable Pore Size, Baiyu Huang

Theses and Dissertations

Mesoporous γ-alumina is the most extensively used catalysts support in a wide range of catalytic processes. The usefulness of γ-alumina relies on its favorable combination of physical, textural, thermal, and chemical properties. Pore structure properties are among the most important properties, since high surface area and large pore volume enable higher loading of active catalytic phases, while design of pore size and pore size distribution is critical to optimize pore diffusional transport and product selectivity. In addition, accurate determination of surface area (SA), pore volume (PV) and pore size distribution (PSD) of porous supports, catalysts, and nanomaterials is vital to …

Part I: An Artificial Neural Network Model Of Tuberculosis Patient Data, Part Ii: A Dft Computational Model Of Metal Hydrides, William Orson Griffin

Theses and Dissertations

PART I -- The data of tuberculosis patients and a control group were analyzed with the artificial neural network in order to find genetic factors which inhibit and promote the patient to developing drug resistant tuberculosis. The data came from populations in Kyrgyzstan containing genetic and physical records as well as the type of tuberculosis they had contracted. Three models based on the data were developed: first, a model which differentiates TB from control patients, second, a model which differentiates both TB and control patients, and finally, a model which distinguishes infiltrative from chronic type tuberculosis. Factors which influenced the …

Renewable Resource-Based Magnetic Nanocomposites For Removal And Recovery Of Phosphorous From Contaminated Waters, Sunil Kumar Ramasahayam

Theses and Dissertations

Water pollution by dissolved phosphorous (P) is a serious water related issue being faced by mankind during the past two decades. Several technologies already exist to remove P from contaminated water but each has its own drawbacks. This project provides a novel microwave assisted synthesis of reduced iron oxide containing renewable resource-based media for P removal from contaminated waters. It provides a fast, easy, and economical way to produce reduced iron oxide nanocomposites without requiring the need for hydrogen or inert gas during the transformation. A wide range of other metal/ carbon nanocomposites can also be synthesized using this technology …

Resorcinarene-Based Cavitands: From Structural Design And Synthesis To Separations Applications, Na Li

Theses and Dissertations

Resorcinarenes are cyclic tetramers that are synthesized by the condensation of resorcinol and various aldehydes. The upper and lower rims can be modified with substituents that provide specific selectivity and other chemical features. In this work, resorcinarene-based macrocyclic ligands with specific selectivities have been designed, synthesized and applied to chiral amine discrimination and transition metal ion separations.These resorcinarenes fall into two categories. In the first type, the upper rims of resorcinarenes were modified with amino acid groups, including chiral alanine groups. The lower rims were modified with --CH3, or --C11H23 groups. The structures were studied by nuclear magnetic resonance (NMR), …

Metallization Of Dna And Dna Origami Using A Pd Seeding Method, Yanli Geng

Theses and Dissertations

In this dissertation, I developed a Pd seeding method in association with electroless plating, to successfully metallize both lambda DNA and DNA origami templates on different surfaces. On mica surfaces, this method offered a fast, simple process, and the ability to obtain a relatively high yield of metallized DNA nanostructures. When using lambda DNA as the templates, I studied the effect of Pd(II) activation time on the seed height and density, and an optimal activation time between 10 and 30 min was obtained. Based on the Pd seeds formed on DNA, as well as a Pd electroless plating solution, continuous …

New Bimetallic Iridium Cluster Carbonyl Complexes, Mingwei Chen

Theses and Dissertations

Platinum group metal derived bimetallic clusters have been used as precursors to nanoscale catalysts which have been proven to be more effective than their monometallic counterparts. Iridium is a platinum group metal and its applications in catalysis continue to grow. To take advantages of synergies between mixed-metals, we modified iridium clusters with other metal ligands like tin, germanium, and group IB (gold, silver, copper) etc. and obtained a fairly large amount of new iridium derived bimetallic clusters which could be precursors to catalysts with superior properties than that available nowadays. The reaction of Ir4(CO)12 with Ph3SnOH in the presence of …

Instrument And Method Development For Single-Cell Classification Using Fluorescence Imaging Multivariate Optical Computing, Joseph Swanstrom

Theses and Dissertations

Multivariate optical computing (MOC) is an all-optical approach of predictive spectroscopy that utilizes multivariate calibration and spectral pattern recognition techniques while operating in a simple filter photometer instrument, removing the need for expensive instrumentation and post-processing of spectral data. This is accomplished with specially designed interference filters called multivariate optical elements (MOEs). MOC can provide analytical solutions for applications requiring low cost, rugged, and simple to operate instrumentation for use in remote and hazardous environments such as open ocean waters. These instrument specifications are central for developing a method for classifying phytoplankton in their natural environment. Phytoplankton are photosynthetic single …

Structural And Photoluminescent Characterization Of Substituted A3mo4f (A = Sr, Ba, Ca; M = Al, Ga, In, Si And Ge), Robert Lenwood Green

Theses and Dissertations

In this dissertation, the structure and photoluminescent properties of A3MO4F-type materials (A = Sr, Ba, Ca; M =Al, Ga, In, Si, Ge) are studied as potential phosphors for compact fluorescent lamps (CFLs) and phosphor converted light emitting diode (pc LED) lights. Chapter 1 outlines background information of the evolution of lighting technology as well as detailing the synthesis, structural characterization and photoluminescence measurements. Chapter 2 focuses on the changes that the Sr3AlO4F structure undergoes as a result of exposure to a 5% H2/95% Ar atmosphere. High-resolution neutron powder diffraction is used to probe for minute structural changes. Chapter 3 is …

Biomaterial-Induced Osteogenesis Of Mesenchymal Stem Cells By Surface Roughness And Functionalization, Pongkwan Sitasuwan

Theses and Dissertations

For tissue engineering and regenerative medicine, it is important to understand factors directing the stem cell fate, including self-renewal, proliferation, differentiation, and apoptosis. Bone marrow derived mesenchymal stem cells (BMSCs) have the potential to differentiate into osteoblasts, chondrocytes, adipocytes, and smooth muscle cells. Specifically, in the field of bone tissue engineering, BMSCs are commonly used for in vitro osteogenesis studies. However the mechanisms and signaling pathways that these cells recognize material surface and utilize to differentiate are still unclear. This dissertation focuses on investigating the effect of surface nanotopography and functionalization on the promotion of osteogenic differentiation of BMSCs. Surface …

Renewable Bio-Based Polymers And Degradable Functional Polymers, Kejian Yao

Theses and Dissertations

In this dissertation, polymers derived from renewable bio-based resources and degradable functional polymers with stimuli-responsive properties by various polymerization techniques were investigated. The properties of these polymeric materials were characterized and discussed.

In Chapter 1, the overall background and recent development of renewable bio-based polymers as well as degradable stimuli-responsive polymers was introduced. Major research objectives of my doctoral work were described.

The first section of the dissertation, on the preparation of renewable bio-based polymers was provided from Chapter 2 to Chapter 4. In Chapter 2, the preparation of novel polymers derived from renewable gum rosin by atom transfer radical …

New Ruthenium And Osmium Carbonyl Cluster Complexes With Main Group Bridging Ligands Having Unusual Structures And Bonding, Yuwei Kan

Theses and Dissertations

The reaction of IrRu3(CO)13(µ-H), 2.1 with HSnPh3 in hexane solvent at reflux has provided the new mixed metal cluster compounds Ir2Ru2(CO)11(SnPh3)(µ-H)3, 2.2 and IrRu3(CO)11(SnPh3)3(µ-H)¬4, 2.3 containing SnPh3 ligands. Compound 2.2 which was obtained in low yield (3%) contains a closed cluster having two iridium and two ruthenium atoms, one SnPh3 ligand and three bridging hydride ligands. Compound 2.3 has a butterfly structure for the four metal atoms with three SnPh3 ligands and four bridging hydride ligands around the periphery of the cluster. When compound 2.3 was heated to 97 oC for 30min, IrRu3(CO)9(μ-η2-C6H5)(μ4-SnPh)2(μ-SnPh2), 2.4 was formed by cleavage of phenyl …

Study Of Porous, Crystalline Supramolecular Boronates, Vincenzo Michael Disantis

Theses and Dissertations

Porous materials with the ability to selectively absorb volatile organic compounds are of high interest for applications in sensing, sequestration and separations. Utilizing the covalent yet reversible boronate ester bonds between boronic acids and diols in conjunction with dative boron-nitrogen coordination bonds has allowed for the discovery of a new class of porous materials. Preliminary results show the ability to obtain porous, crystalline supramolecular boronate networks from the coordination of diamine linkers with boronate diester backbones. Further exploration of porous, crystalline supramolecular boronates has revealed the discovery of a porous crystalline coordination polymer that exhibits reversible, selective guest adsorption properties …

Preparation And Characterization Of Palladium Catalysts, Michael J. Anderson

Theses and Dissertations

There is a critical need for improved combustion-oxidation catalysts to reduce emissions of toxic volatile organic compounds (VOCs) emitted from exhaust gas of gasoline combustion in automotive vehicles. Materials and systems currently available, such as the three way catalytic converter (TWC), have low activity below 400 °C in the catalytic process. Palladium catalysts were prepared by alternative methods including: preparation by wet impregnation or incipient wetness, drying by room temperature or air-oven, and support choice between silica and alumina. These catalysts were prepared to meet the demand for low temperature oxidation. Results indicated a 5% increase in percent dispersion of …

Thermal Infrared Imaging: Instrumentation And Method Development, Wayne O'Brien

Theses and Dissertations

A recently development thermal infrared camera system was improved by designing new components to downsize physical aspect and improve the instrument's performance. A new thermal infrared light source was developed and characterized. It is designed from a custom-made Macor backpiece that holds an alumina screw. High resistance wire is coiled around the screw. The coiled wire is covered with an alumina coating. Most light sources have a spectral emissivity similar to that of a blackbody emitter. This source has a spectral irradiance profile that is not similar to a blackbody source. Thus, the lamp has an improved efficiency in the …

Programmable Polymers Preparation Optimization And Applications On Solute Templates, Yinyan He

Theses and Dissertations

Programmable polymer is a type of stimuli-responsive polymer which can keep their induced properties after removal of the stimulu, as well as programmable polymers maintain the general properties as stimuli-responsive polymers, such as recognize and respond to the stimulus. The previous reported solvent Caryl-Nimide bonds based programmable polymers (SPP-1) can freely rotate and change the carboxylic acid recognition group orientation in response to templates. Solvent templates were used in the SPP-1. One potential application for SPPs is using their recognition and memory properties for the identification and separation of mixture solutions of various analytes. In my first project, I wanted …

Functional Block Copolymers For Applications In Advanced Materials, Energy Storage, And Lithography, Christopher George Hardy

Theses and Dissertations

Block copolymers spontaneously self-assembly into a wide variety of ordered nanostructures on the length scale of 5 - 100 nm due to the thermodynamic immiscibility between the covalently linked, chemically distinct polymer chains. Incorporating desirable functional groups into block copolymer systems can lead to confinement of the functional group to a specific domain upon microphase separation of the block copolymer. The resulting materials display desirable characteristics of the functional group in a well-ordered nanostructure. Such systems have been utilized in a wide variety of applications including catalysis, ceramic materials, and membranes. This dissertation is focused on the synthesis, characterization, self-assembly …

Development And Figures Of Merit Of Microextraction And Ultra-Performance Liquid Chromatography For Forensic Characterization Of Dye Profiles On Trace Acrylic, Nylon, Polyester, And Cotton Textile Fibers, Scott James Hoy

Theses and Dissertations

Methodology for the microextraction of basic dyes on acrylic, acid dyes on nylon, disperse dyes on polyester, and reactive dyes, direct dyes, and indigo on cotton textile fibers is reported. Although these processes are destructive to the fiber evidence, the ability to analyze dye extracts from sub-millimeter fiber lengths of single fibers, coupled with detection limits in the hundred picogram range by ultra-performance liquid chromatography (UPLC) with both diode array detection (DAD) and tandem mass spectrometry (MS-MS) makes routine forensic characterization feasible.

Microextraction, followed by UPLC, can often distinguish similar fibers containing different, but similar, dyes with the combination of …

Design And Synthesis Of Polymer-Based Advanced Nanomaterials Using Raft Polymerization And Click Reaction, Junting Li

Theses and Dissertations

This research focuses on exploring new synthetic approaches to prepare polymer-based advanced nanomaterials using highly efficient chemical tools, such as reversible addition-fragmentation chain transfer (RAFT) polymerization and click reactions.

In the first project, novel synthetic routes to produce fullerene-based polymers were designed. First, mono-alkynyl functionalized fullerene was prepared starting with pristine fullerene (C₆₀). Methyl methacrylate and 6-azido hexyl methacrylate were then randomly copolymerized via RAFT polymerization with well-controlled molecular weights and copolymer compositions. Finally, the two moieties were covalently assembled into a series of well-defined side-chain fullerene polymers (SFP's) via the copper-catalyzed click reaction. The TGA and UV-vis …

Polybenzimidazole Membranes With Enhanced Mechanical Properties For Extended Lifetime Electrochemical Applications, Max Molleo

Theses and Dissertations

After approximately 20 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). Commerical PBI MEAs can operate reliably for over two years at elevated temperatures of 120-180°C due to the physical and chemical robustness of PBI membranes. Recently, the Department of Energy has issued a target of 40,000-80,000 hours for stationary (i.e. combined heat and power, back-up power) polymer electrolyte membrane / proton exchange membrane (PEM) fuel cells. It is known through observation that over time, PBI membranes at 180°C creep in a direction perpendicular to compressive forces, thus …

Iridium-Ruthenium/Osmium-Gold Cluster Complexes: Unique Structures And Properties, Qiang Zhang

Theses and Dissertations

Chapter Two

The first Ir-Ru cluster complex was synthesized was the electron-rich, anionic, planar cluster complex [PPN][IrRu6(CO)23], 2.5, (PPN=Bis(triphenylphophoranylidene)-ammonium) which obtained from the reaction of [PPN][IrRu3(CO)13] with one equivalent ruthenium carbonyl (Ru3(CO)12) at 66 oC (THF reflux) for 12h. Compound 2.5 could also be synthesized by using the mono-Iridium compound [PPN][Ir(CO)4] reacts with two equivalent of ruthenium carbonyl. In compound 2.5, all seven metal atoms lie in a plane (max deviation = 0.043(1) Å) with the iridium atom in the center circumscribed by a hexagonal ring of six ruthenium atoms. The anion 2.5 contains 104 valence electrons while both the …