Physical Sciences and Mathematics Commons^™

Towards The Total Synthesis Of Thioviridamide: Thiyl Radical Approach To The Beta-Thioenamide Linkage Formation, Jung-Hoon Kang

Theses and Dissertations

We developed an approach to the β-thioenamide linkage contained in the S-(2-aminovinyl)cysteine (avCys) residue of thioviridamide.1,2 Kinetic and thermodynamic control of radical additions of thiols to ynamides were studied for the formation of β-thioenamide linkage. Thiyl radicals are electrophilic and ynamides are electron-rich alkynes. This complementary polarity of the radical and acceptor increases the likelihood of a successful radical addition reaction. Because little is known about these types of compounds (β-thioenamides), we were unsure what kinds of yields and stereoselectivities (cis vs. trans) to expect. The adduct stability is another issue to consider. Fortunately, under typical radical addition conditions, the …

Synthesis, Structure And Magnetic Properties Of Oxy-Anion Based Magnetic Solids Containing Transition Metal Oxide Nanostructures, Kulugammana Gedera Ranmohotti

All Dissertations

Inline with the focus of our research, my goal for this dissertation study is to further explore new classes of magnetic insulators exhibiting novel properties. The scope of this work is twofold: 1) the exploratory synthesis of polyanion-based mixed-framework compounds containing transition metal oxide magnetic nanostructures, and 2) the investigation of the structure/property correlation with respect to the spin couplings in confined lattices. These studies are of fundamental and technological importance regarding the long-term development of low-dimensional magnetic solids for device applications in especially information storage and quantum computing. Several interesting and significant transition metal based silicate, phosphate arsenate and …

Study On Methods Of Simultaneous Multi-Component Analysis., Jennifer Bernice Ashie

Electronic Theses and Dissertations

Many new instrumentation and different instrumental techniques have been developed to deal with increasing complexity of samples encountered. Many researchers also have coupled these instrumental techniques with chemometric algorithms to assist in the quantitative analysis of multi-component samples in the hope of alleviating the need of tedious separation and cleanup procedures. These newer chemometric procedures tend to be complex and difficult to understand and implement and are successful under different circumstances and conditions. In this study, we start from the very simple beginning and examine the factors that can present difficulties with obtaining the correct results and observe how the …

Studies Of Surfactants Effect On Riboflavin Fluorescence And Its Determination In Commercial Food Products And Vitamin Tablets., William Emmanuel Ghann

Electronic Theses and Dissertations

A simple and economical fluorometer using blue LEDs excitation sources and simple PMT detection had been built, assembled, optimized, and employed for measurement of fluorescence from riboflavin (vitamin B₂). Surfactants have been known to enhance the intensity of fluorescence of fluorescent compounds. Fluorescence analysis of riboflavin in the presence of various anionic, cationic, and nonionic surfactants was also conducted to determine if they could improve analysis. However, the surfactants employed did not seem to have any meaningful enhancement; in fact, some actually diminished the fluorescence intensity of riboflavin. The procedure was linear for riboflavin from 0.01 to 2.5 …

Towards The Design And Syntheses Of Novel Triads Comprising Single Robson-Type Macrocyclic Dicopper(Ii) Cores Flanked By Two Terminal Polypyridyl Ruthenium(Ii) Complexes., Leslie Shane Moody

Electronic Theses and Dissertations

Progress toward the syntheses of new tetranuclear bimetallic complexes of copper(II) and ruthenium(II) was realized. The designed triads comprise a central binuclear copper(II) complex with a tetraiminodiphenolate macrocyclic Robson-type compartmental ligand. In the envisioned complexes, the macrocyclic core is further functionalized by attachment of two polypyridyl ruthenium(II) complexes. A novel dibrominated dicopper(II) Robson complex was formed by the 2:2:2 condensation reaction of 4-bromo-2,6-diformylphenol and 1,3- diaminopropane with cupric chloride. Similarly, a new dibrominated dizinc(II) was synthesized from zinc tetrafluoroborate and the same diamine and dialdehyde. The new dicopper(II) complex did not heterocouple with borylated substrates under explored Suzuki reaction conditions. …

Nondestructive Evaluation Of Aircraft Composites Using Terahertz Time Domain Spectroscopy, Christopher D. Stoik

Theses and Dissertations

Terahertz (THz) time domain spectroscopy (TDS) was assessed as a nondestructive evaluation technique for aircraft composites. Material properties of glass fiber composite were measured using both transmission and reflection configuration. The interaction of THz with a glass fiber composite was then analyzed, including the effects of scattering, absorption, and the index of refraction, as well as effective medium approximations. THz TDS, in both transmission and reflection configuration, was used to study composite damage, including voids, delaminations, mechanical damage, and heat damage. Measurement of the material properties on samples with localized heat damage showed that burning did not change the refractive …

Synthesis And Evaluation Of Structural Analogs Of Escherichia Coli Lipid A For Application Towards Cd14-Targeting Glycotherapeutics, Aileen Fay Galos Bongat

Dissertations

Lipid A is a glucosamine-based phospholipid that anchors carbohydrate molecules to the outer membrane of most Gram-negative bacteria. During severe infection, this amphiphilic macromolecule invoke a strong and acute pro-inflammatory response that leads to sepsis and ultimately to septic shock, organ failure and death. Thus, following the convention that the best antidote is often a derivative of the parent agonistic molecule, researchers have actively pursued the idea of creating an analog of Lipid A that can block the cellular receptor for this molecule and thereby arrest the cascade of events that lead to sepsis. Consequently, we became interested in creating …

Preparation Of Carboxylic Acid Functionalized Glycopolymers Through Raft And Post-Polymerization Modification For Biomedical Application, Husnu Alp Alidedeoglu

Dissertations

The primary theme of this dissertation involves the synthesis of well-defined primary amine functionalized polymers, subsequent modification of the polymers to produce novel carboxylic acid functionalized glycopolymers and surface polymerization of these systems utilizing controlled polymerization techniques. Additionally, the synthesis of new water-based allylic copolymer latexes is described. Carbohydrates are natural polymers which possess unlimited structural variations. They carry a huge density of information, and play major roles in recognition events and complex biological operations. For example, hyaluronic acid (HA), an anionic glycosaminoglycan, provides lubricating and cushioning properties in the extracellular matrix and has been found to be involved in …

Photopolymerization And Characterization Of Thiol-Enes And Thiourethanes, Qin Li

Dissertations

Compared to conventional acrylic monomer systems, thiol-ene photopolymerization, an efficient click process leading to the formation of dense and uniform molecular networks, has several distinct advantages including relative insensitivity to oxygen inhibition, high monomer conversion and low shrinkage. Although there has been a revival of interest in thiol-enes in the past 6 years, the structure-property relationship of these networks has not been explored in detail. For future applications, thiol-enes with higher shelf-life stability and glass transition temperatures need to be used. Sulfur containing urethanes, thiourethanes and dithiourethanes are a class of widely used materials due to their distinct properties such …

Adsorption Of Propane On The Magnesium Oxide (100) Surface And Synthesis Of Anodized Aluminum Oxide, Michael John Felty

Doctoral Dissertations

This work is divided into two parts: the adsorption of propane on the magnesium oxide (100) surface and the synthesis of anodized aluminum oxide. The adsorption properties of propane on the MgO (100) surface were investigated using high-resolution volumetric isotherm techniques and a computational study was accomplished using Materials Studio. From the adsorption work, the two-dimensional isothermal compressibility, the isosteric heat of adsorption, the differential enthalpy, and the differential entropy of adsorption can be calculated. Three distinct layers of propane were observed to form on the MgO (100) surface and it was determined that a phase transition occurs at 162 …

Molecular Hydrogen Adsorbed On Mgo (100) Surfaces: A Thermodynamic Study, Lillian Ruth Frazier

Doctoral Dissertations

The thermodynamics of molecular hydrogen adsorbed on MgO (100) surfaces has been examined using high resolution volumetric adsorption isotherm techniques. These studies were undertaken using highly perfect, narrow size distributed MgO nanocubes with essentially single (100) facet exposure and extremely high chemical purity. A narrowly spaced (in temperature) series of isotherms were performed between the temperatures of ~7K and the triple point (13.8 K) using H₂ and D₂ gas.

A minimum of five, and in some cases seven, discrete adsorption steps are clearly observed in each isotherm trace. Analysis of these data indicate that the monolayer film forms …

New Carbon-Carbon Bond Forming Reactions Mediated By Boron And Transition Metal Halides, Travis R. Quick

Doctoral Dissertations

This dissertation summarizes the recent use of boron and transition metal halides to form new carbon-carbon bonds. Several novel reactions have been discovered. These include the haloallylation of aryl aldehydes with boron trihalide; alkyne-aldehyde couplings mediated by boron trihalide to give either (Z,Z)-1,5-dihaloalkenes or (Z,E)-1,5- dihaloalkenes; dehydroxylation of benzylic alcohols and in situ generated benzylic alcohol salts with iron(III) chloride and triethylsilane to afford diarylmethanes; and, the alkenylation of allylic, benzylic, and propargylic alcohols with phenylacetylenes and titanium(IV) halide. The results of these studies strongly imply a cationic mechanism. The reaction methodology of the research described herein can be characterized …

The Relationship Betweeen Dynamic And Chemical Factors On The Morphology In Aot-Water-Polymer Systems, Jolanta Elzbieta Marszalek

Dissertations

Photopolymerization of reverse microemulsion demonstrates strong influences from dynamical and chemical factors on morphology of formed polymer systems. Upon polymerization the clear microemulsion with nanoscale structures transforms into opaque films with larger aggregates that scatter light. Studied here were microemulsions based on acrylate and on thiol-ene chemistries. The difference in the two reaction mechanisms results in the phase separation occurring at different stages of the material formation. Consequently, the morphology of the material demonstrates distinct dissimilarities in the two systems. In addition, the chemical structure of the monomers promotes these morphological differences. When the microemulsion is composed of acrylate and …

Synthesis Of A Dirhodium Tetraphosphine Catalyst And The Effect Of Various H2/Co Ratios On The Catalyst, Christina Joanne Sweeney

Honors Theses

No abstract provided.

Investigation Of The Interactions Of Cationic Polyelectrolytes With Anionic Surfactants: Effects Of Polymer, Surfactant And Solution Properties, Lisa Renee Huisinga

Dissertations

The intent of this research is to explore and understand the effects that a range of polymer, surfactant and solution parameters have on the interaction of oppositely-charged polymers and surfactants. Cationic polysaccharides were chosen for this research because they are known to interact with anionic surfactants, and they offer a wide range of adjustable polymer properties, including molecular weight, charge substitution, and backbone structure. Cationic poly(vinylpyridinium hydrochloride) polymers were chosen for these studies because they provide the opportunity to explore the effects of charge position on the interaction of cationic polymers with anionic surfactants and how this influences the mechanism …

Dispersion States And Surface Characteristics Of Physically Blended Polyhedral Oligomeric Silsesquioxane/Polymer Hybrid Nanocomposites, Rahul Misra

Dissertations

Control of dispersion and segregation states of nanostructured additives is one of the biggest challenges in realizing the optimum potential of high-performance hybrid polymer nanocomposites. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, with their hybrid organic-inorganic nature and flexible functionalization with a variety of organic substituents, yield possibilities to control dispersion and tune compatibility in a wide range of polymer systems. The overall goal of this research is to investigate the fundamental parameters that influence the dispersion and segregation states of POSS nanostructured chemicals and to understand chain dynamics and conformations in physically blended POSS hybrid polymer nanocomposites (HPNC's). Multiple structural …

Examination Of An Aloe Vera Galacturonate Polysaccharide Capable Of In Situ Gelation For The Controlled Release Of Protein Therapeutics, Shawn David Mcconaughy

Dissertations

A therapeutic delivery platform has been investigated with the ultimate goal of designing a sustained protein release matrix utilizing an in-situ gelling, acidic polysaccharide derived from the Aloe vera plant. The Aloe vera polysaccharide (AvP) has been examined in order to determine how chemical composition, structure, molecular weight and solution behavior affect gelation and protein/peptide delivery. Correlations are drawn between structural characteristics and solution behavior in order to determine the impact of polymer conformation and solvation on gel formation under conditions designed to simulate nasal applications. Steady state and dynamic rheology, classic and dynamic light scattering, zeta potential, pulse field …

Synthesis, Propagation Kinetics, And Characterization Of D,L-Lactide-Based Polyols And Polyurethanes Therefrom, Scott Joseph Moravek

Dissertations

In order to expand the usefulness of degradable polyesters, degradable polyurethanes were synthesized using a mixed polyol system including poly(D,L-lactideco- glycolide) (PLGA), a well-known degradable polyester. Two isocyanate systems, methyl 2,6-diisocyantocaproate (LDI) and dicyclohexylmethane-4,4'- diisocyanate(Hi2MDI), were studied in order to achieve optimal physical and thermal properties of the thermoplastic polyurethane (TPU) while maintaining degradablity. The LDI based systems had excellent physical properties as well as thermal properties that may make them suitable for biomedical devices. The H12MDI based TPUs also had excellent physical properties as well as a higher melting temperature. The aforementioned TPUs were synthesized in small batches. Another …

Synthesis, Characterization, And Application Of Ag Nanostructures, Stephen Hudson

All Dissertations

Noble metal nanoparticles (NPs) have been used for many centuries; however their properties were not truly scrutinized until Michael Farady's investigations in the 1850's. Advances in the field of nanotechnology over the last three decades have enabled insights into the properties of materials as their dimensions are reduced to the nanoscale. The repercussions of these insights are seen in many modern applications.
In this dissertation, properties of novel nanostructures based on Ag NPs are presented and discussed. The exceptional optical properties of Ag NPs stem from the collective oscillations of the conduction electrons known as plasmon resonances. The excitation of …

Evaluation Of Electron Donor Materials Used To Create Subsurface Permeable Reactive Barriers For Enhanced Reductive Dechlorination Of Chlorinated Ethenes, Elizabeth S. Semkiw

Dissertations

Chlorinated ethenes (CEs) are widespread ground water contaminants, apparently due to their extensive migration from numerous contamination source points. In this study, a long-term field investigation and aquifer microcosm experiments were combined to evaluate the effectiveness of electron donor materials used to create and maintain subsurface permeable reactive barriers (PRBs) for the enhanced in-situ biodegradation of CEs. The laboratory component includes the first side-by-side comparison of electron donor materials dairy whey, lactate syrup, and Hydrogen Release Compound® (HRC), in which dechlorination rates, fermentation product distributions, and H₂ production were monitored as measures of substrate efficiency. Field study allowed the …

Switch On And Switch Off Nanosensors For The Detection Of Nerve Gas Agents, Shankar Varaganti

Dissertations

The central hypothesis of this research is the development of novel nanosensors by a bottom-up approach for the detection of nerve gas agents. The nanosensor assembly consists of four main parts; nanoparticles (N), Monomer (M), Complex (C) and Receptor (R). Two novel Ru (II)-bipyridyl and zinc complexes with tryptophan receptors either in 4,4' or 5,5' position of the bipyridyl ring have been synthesized and characterized by using ¹H NMR, ¹³C NMR, mass spectrometry and absorption spectroscopy. Silica nanoparticles or quantum dots are used as a platform for the nanosensors. Highly conjugated stilbene type compounds are used as monomers. …

Fabrication And Optical Properties Of Noble Metal Nanostructures, Mark Kinnan

All Dissertations

Experimental and theoretical results are presented in Chapters 2, 3, and 4 on the effects of dielectric medium, particle size, and interparticle distance, respectively, on plasmon coupling in two-dimensional arrays of silver nanoparticles. The arrays were fabricated via the self-assembly of single crystal particles from c.a. 46 nm to 287 nm on PVP-modified glass substrates. Spin-coated poly(methylmethacrylate) layers were used to immobilize the particles and prevent their surface aggregation. Varying the thickness of the PMMA layer made it possible to change the average dielectric medium between the particles. UV-Visible spectra of different arrays were compared to the corresponding electron microscope …

Fluorescent Conjugated Polymer Dots For Single Molecule Imaging And Sensing Applications, Changfeng Wu

All Dissertations

While single molecule imaging and sensing hold the promise of providing unprecedented detail about cellular processes, many advanced applications are limited by the lack of appropriate fluorescence probes. In many cases, currently available fluorescent labels are not sufficiently bright and photostable to overcome the background associated with various autofluorescence and scattering processes. This dissertation describes research efforts focused on the development of a novel class of fluorescent nanoparticles called conjugated polymers dots (CPdots) for single molecule fluorescence detection. The CPdots contain highly fluorescent π-conjugated polymers that have been refined over the last decades as the active material in polymer light-emitting …

Novel Lactide Derived Polymers; Synthesis, Properties And Applications, Dahlia Haynes

All Dissertations

This dissertation primarily encompasses the synthesis, characterization, properties and discussion of applications for lactide derived polymers. The methodology focuses on altering polylactide's (PLA's) dynamic and physical properties increasing its broad market utility in both traditional and non-traditional applications. The fundamentals of this work include understanding and enhancing the polymer chemistry and materials related processes through the use of copolymerization, fluorination, composite chemistry and materials science.
The first chapter discusses the important of this research with emphasis on current world issues that focuses on the feasibility of renewable resources and sustainability implementation. Modification of renewable resource materials like lactic acid is …

Synthesis And Characterization Of Biodegradable Polyurethanes For Biomedical Application, Changhong Zhang

All Dissertations

This dissertation constitutes the studies about the biomedical materials research of novel polyurethanes. These elastic and degradable polyurethanes exhibited the potential for drug delivery, scaffold fabrication by novel ink-jet printing technology or other biomedical applications. This dissertation includes two parts about two different types of polyurethanes.
In the first part of this dissertation, we studied a polyurethane that was synthesized from methylene di-p-phenyl-diisocyanate (MDI), polycaprolactone diol (PCL-diol) and N, N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES). MDI, PCL-diol and BES were polymerized into polyurethane and served as the hard segment, soft segment and chain extender respectively. The effects of the chain extender BES …

Heats Of Solvation Of Organic Liquids In Room Temperature Ionic Liquids, Paula Jeanette Beach

Masters Theses

Ionic liquids are of potential use in industry as reusable, non-polluting solvents. Their thermochemical properties need to be known to facilitate planning of processes and experiments using these solvents. Two ionic liquids: 1-Butyl-3-methylimidazolium hexafluorophosphate ([C4mim]PF6 or [bmim]PF6) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim]NTf2) were studied using a calorimeter. Various organic liquids were introduced into the solvents and their heats of solution were measured and tabulated. Potential effects of certain functional groups such as alcohol, amine, carboxylic acid, ketone, and aldehyde were examined as well as aromatics versus chains and saturated rings.

Analysis Of Chemical Bonding In Clusters By Means Of The Adaptive Natural Density Partitioning, Dmitry Yu Zubarev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Models of chemical bonding are essential for contemporary chemistry. Even the explosive development of the computational resources including, both hardware and software, cannot eliminate necessity of compact, intuitive, and efficient methods of representing chemically relevant information. The Lewis model of chemical bonding, which was proposed eleven years before the formulation of quantum theory and preserves its pivotal role in chemical education and research for more than ninety years, is a vivid example of such a tool. As chemistry shifts to the nanoscale, it is becoming obvious that a certain shift of the paradigms of chemical bonding is inescapable. For example, …

Pulse-Laser Infrared Photothermal Spectrometry Of Condensed-Phase Aerosols Based On Photothermal Deflection Spectroscopy, Oluwatosin Olubunmi Dada

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The research reported in this dissertation is aimed at development of photothermal deflection detector that is consistent with constraints imposed by aerosols sampling and analysis. The main objectives of this project are: 1) the design and evaluation of initial apparatus prototypes and 2) a test of the prototype apparatus with surrogate substances using conventional mid-infrared gas lasers.

Experimental evaluation of reduced size photothermal apparatus is first performed with gaseous samples. Analysis of trichlorofluoromethane (CFC-11) and ethanol vapors is performed with both conventional large apparatus and the prototype small apparatus. Comparison studies in terms of photothermal signal from both apparatuses are …

Synthetic Complexes Of Relevance To Ni(Ii)-Containing Enzymes, Katarzyna Rudzka

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The work outlined herein presents an investigation of synthetic model complexes of relevance to the active sites of Ni(II)-containing enzymes, particularly urease, glyoxalase I, and acireductone dioxygenase. The research focuses on studying the structural and reactivity features of nickel complexes with biologically relevant substrates. The anion of acetohydroxamic acid is a well-known inhibitor of urease enzymes, including those isolated from Klebsiella aerogenes and Bacillus pasteurii. A precursor to the acetohydroxamate coordination in ureases is proposed to be an interaction between Ni(II) and acetohydroxamic acid. By using a novel supporting chelate ligand capable of secondary hydrogen bonding interactions a novel …

Sources And Source Processes Of Organic Nitrogen Aerosols In The Atmosphere, Mark E. Erupe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The research in this dissertation explored the sources and chemistry of organic nitrogen aerosols in the atmosphere. Two approaches were employed: field measurements and laboratory experiments. In order to characterize atmospheric aerosol, two ambient studies were conducted in Cache Valley in Northern Utah during strong winter inversions of 2004 and 2005. The economy of this region is heavily dependent on agriculture. There is also a fast growing urban population. Urban and agricultural emissions, aided by the valley geography and meteorology, led to high concentrations of fine particles that often exceeded the national ambient air quality standards. Aerosol composition was dominated …