Physical Sciences and Mathematics Commons^™

Electrochemical Synthesis Of Nanostructured Noble Metal Films For Biosensing, Jay Kishan Bhattarai

Dissertations

Nanostructures of noble metals (Au and Ag) are of interest because of their important intrinsic properties. Noble metals by themselves are conductive, physically robust, chemically inert, and strongly bind to thiols. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties tunable by adjusting the shape and size. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for biosensing. Individual nanostructures might be easier to prepare but difficult to handle to be used as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble …

Probing The Unfolding And The Stability Of The Last Four Metal Binding Domains Of Wilson Disease Protein Using Circular Dichroism And Novel Spectroscopic Techniques, Ibtesam Yaseen Alja’Afreh

Dissertations

Wilson disease protein is a copper-transporting P_1B type ATPase. It has large N-terminal copper binding domain which is composed of six homologous sub-domains. Each of these six domains is ~72 residues and connected to one another by linking regions of various lengths. They all possess similar ferrodoxin fold, and metal-binding motif, MXCXXC.

The need of having six metal binding domains and the manner in which they are communicating with each other is not well understood. To better understand how the last four metal binding domains function, I pursued a detailed biophysical characterization of these domains. Using molecular biology I …

Ultrafast Interfacial Electron Transfer Across Molecule-Tio2 Nanocomposites: Towards Solar Cells And Two Photon Absorption, Edwin Mghanga

Dissertations

Interfacial charge transfer (ICT) across the molecule-TiO2 nanoparticle interface has gained enormous research attention for applications in dye sensitized solar cells (DSSC), photo-catalysis, water splitting and nonlinear optics. DSSCs are promising clean alternative energy sources. However, current DSSCs suffer from lower efficiencies and higher cost. Better understanding of the ICT processes in DSSCs can help solve these problems. We have used two strategies to understand ICT in the context of DSSCs. Firstly, we used a computationally validated anchor group, acetylacetonate (acac) to bind molecules to the semiconductor surface and facilitate charge separation. Secondly, we used natural dye sensitizers, …

Computational And Experimental Investigation Into Yield Behavior And Cure Rate Dependence Of Thermoset Polymers, Christopher Harold Childers

Dissertations

This dissertation is broken down into two primary sections: firstly, the development and improvement of molecular dynamics simulations of thermoset matrix polymers including their use in understanding molecular response to applied strain deformation and secondly, the discernment of a cure heating ramp rate dependence of the final molecular and macro-molecular properties of thermoset matrix polymer.

The molecular dynamics section will discuss the development of molecular dynamics simulations of thermoset epoxy/amine matrix polymers, and the implementation of this work to determine the underlying molecular level events that cause thermoset matrix polymer yield. It will report a novel method for the determination …

Tuning Responsiveness Of Polypeptide Based Block Copolymers For Drug Delivery, Ashley J. Johnson

Dissertations

The goal of this dissertation was to tune the pH response and self-assembled morphologies of amphiphilic polypeptide block copolymers for use as drug delivery vehicles. Poly(L-lysine) and poly(L-glutamtic acid) are responsive, ionizable polypeptides that undergo secondary structure transitions, from α-helix to random coil, whereby the change in conformation of the peptide chain results in changes to the global morphology of a self-assembled system. The main focus of this work was to understand how changes in the polymer composition and the local environment can lead to control over the behavior of the overall system. First, the responsive behavior of poly(L-lysine) block …

Spectroscopy And Gas-Phase Binding Of Modified Desferrioxamine B Indicator Displacement-Based Sensors, William Scott Jones

Dissertations

A coupling reaction has been used to successfully synthesize two novel probes utilizing coumarin derivatives as fluorophores. The structure, spectroscopy, and thermodynamics of these probes were characterized and studied. These probes, along with a classical probe using a N-methyl-anthranilate fluorophore, are used to take advantage of the ability of siderophores to coordinate Fe³⁺ ions which is coupled with the attractive phosphorescence properties of lanthanide ions. The use of lanthanide metals to create an indicator displacement assays is a novel application of these probes for the detection of Fe³⁺ ions. The use of Tb³⁺ ions as the indicator …

Continuous Polymer Reactor Design, David Sujay Kingsley

Dissertations

Twin screw extruders can be used as continuous polymer reactors to process polymers, which are conventionally made through batch reactors. Batch processes have certain undesirable qualities such as improper mixing and the inability to precisely control the reaction, which leads to variation between batches and potential exotherms. The work presented in this dissertation investigates the use of continuous polymer reactor designs to efficiently process renewable sourced thermoplastic polyurethanes (TPU), and prepreg epoxy matrix prepolymers.

The overall goal of this research is to highlight the modularity of twin screw extruders as continuous polymer reactors to synthesize the relevant polymers. Chapter I …

Investigation Of Glassy State Molecular Motions In Thermoset Polymers, Jianwei Tu

Dissertations

This dissertation presents the investigation of the glassy state molecular motions in isomeric thermoset epoxies by means of solid-state deuterium (²H) NMR spectroscopy technique. The network structure of crosslinked epoxies was altered through monomer isomerism; specifically, diglycidyl ether of bisphenol A (DGEBA) was cured with isomeric amine curatives, i.e., the meta-substituted diaminodiphenylsulfone (33DDS) and para-substituted diaminodiphenylsulfone (44DDS). The use of structural isomerism provided a path way for altering macroscopic material properties while maintaining identical chemical composition within the crosslinked networks.

The effects of structural isomerism on the glassy state molecular motions were studied using solid-state ²H …

Molecular Probes For The Detection Of Zn2+ And Fe3+ Ions, Erendra Manandhar

Dissertations

A number of molecular probes have been designed and synthesized for the detection of Zn²⁺ and Fe³⁺ ions. Two types of functional groups have been incorporated into the molecular scaffolds to utilize different fluorescent mechanisms. The first class of receptors contains a pyrene moiety. These molecular probes use the excimer mechanism for the detection of Zn²⁺ ion. The probes work well in an organic solvent with a detection limit of 20 nM (one ppb). Alternatives are made to make them water soluble, but this proved to be difficult. An interesting ion-induced self-assembly system will also be discussed. …

Utilization Of Aqueous Raft Prepared Copolymers To Improve Anticancer Drug Efficacy, Andrew Christopher Holley

Dissertations

The advent of controlled radical polymerization (CRP) techniques, along with advancements in facile conjugation chemistry, now allow synthetic tailoring of precise, polymeric architectures necessary for drug/gene delivery. Reversible addition- fragmentation chain transfer (RAFT) polymerization and its aqueous counterpart (aRAFT) afford quantitative control over key synthetic parameters including block length, microstructure, and placement of structo-pendent and structo-terminal functionality for conjugation of active agents and targeting moieties. The relevance of water-soluble and amphiphilic (co)polymers synthesized by RAFT for in vitro delivery of therapeutics in biological fluids is an especially attractive feature. In many cases, polymerization, binding, conjugation, …

Enzyme, Cosolvent, And Substrate Interactions In Ple Hydrolysis Reactions And Evaluation Of The Stability Of An Unnatural Glutathione Analogue, Maureen Elizabeth Smith

Dissertations

Prochiral diester malonates have been hydrolyzed in the presence of Pig Liver Esterase (PLE). Several of the diesters produced the respective half-ester in moderate to high enantioselectivity. A series of cosolvent assays were performed to evaluate the ability of the cosolvent to influence the enantioselective outcome of the hydrolysis reactions. Ethanol produced the largest changes in enantioselectivity of all solvents evaluated. The isoenzymes of PLE were also evaluated and provided very different enantioselective outcomes than that of crude PLE. A series of NMR titrations was performed to explore the interactions between the substrates and ethanol cosolvents.

Improvements to our previously …

New Methods And Strategies For Orthogonal Oligosaccharide Synthesis, Scott James Hasty

Dissertations

Although scientists have been able to isolate certain classes of naturally occurring carbohydrates, the overall availability of pure natural isolates remains inadequate. As a result, chemical synthesis has been employed to access complex carbohydrates. Unfortunately, traditional oligosaccharide synthesis often requires laborious protecting-group manipulations that results in lower yields. Expeditious strategies effectively shorten the task of oligosaccharide assembly by minimizing the need for protecting-group manipulations between glycosylation steps, or even purification of the intermediates. Additionally, prediction of the stereoselective outcome of the coupling reaction between two sugar units is a major obstacle facing carbohydrate chemists. It is well known that 1,2-trans …

Design And Synthesis Of Chelating Compounds And Solid-Supported Chelators For Metal Depleted Solutions, Surendra Dawadi

Dissertations

Metals are essential to life, yet they can be toxic for biological systems when present in excessive amounts. The major source of metal overload in humans is diet; and in some cases, intravenous feeding. Thus the removal of toxic metal ions from contaminated clinical products such as total parenteral nutrition (TPN) solutions, and drinking and waste water is extremely important. The use of chelating resins, which are polymeric solids containing covalently immobilized chelating compounds, for the selective removal of metal ions from contaminated solutions has been conceptualized long ago. Herein, the design and synthesis of metal specific chelating compounds and …

Chemistry And Thermochemistry Of Selected Fatty Acids Using Correlation Gas Chromatography, Joe A. Wilson

Dissertations

Correlation gas chromatography (c-GC) is a special application of the gas chromatography technique and is used for the evaluation of both vaporization enthalpy and vapor pressures of organic compounds. Its use in measuring vaporization enthalpies has been extensively documented. This method is useful for measurements of both liquids and solids. For substances that are solids, since each analyte is dilutely adsorbed on the condensed phase of the gas chromatographic column, it is not crystalline. The vapor pressure that it exhibits behaves as an excellent model of the sub-cooled liquid as demonstrated by various thermochemical cycles. Thermochemical measurements are important to …

Nanoporous Gold Characterization, Structural Modification And Use As A Solid Support For Biomolecule Immobilization, Abeera Sharma

Dissertations

Nanoporous gold (NPG) has immense technological applications owing to a plethora of properties like large surface area to volume ratio, plasmonic properties, stable gold-thiolate bond formation and a wide range of pore sizes. The surface morphology of nanoporous gold has been altered previously by dealloying and thermal annealing to increase/decrease the pore size and change the surface area. We provide a novel electrochemical annealing technique for post dealloying modification wherein electrochemical sweep cycles in different electrolytes at positive potentials leads to a subsequent increase in pore sizes of nanoporous gold as studied using scanning electron microscopy. Tailoring the surface of …

Biophysical Characterization Of The First Four Metal-Binding Domains Of Human Wilson Disease Protein, Alia V.H. Hinz

Dissertations

Wilson disease protein (WLNP) is a P_1b-type ATPase crucial for maintaining copper homeostasis in humans. Mutations in this protein result in the autosomal recessive disorder Wilson disease, a condition characterized by copper accumulation in the liver and brain. WLNP provides copper for incorporation into cuproproteins and exports excess copper into the bile for excretion. There are six metal-binding domains (MBDs) in WLNP, found within the first 650 amino acids of this 1,465 amino acid protein. Though each MBD has a different amino acid sequence, all MBDs possess a similar ferredoxin fold with a conserved hydrophobic core and a …

Nanocarbon Immobilized Membrane For Separation And Analysis, Madhuleena Bhadra

Dissertations

Membrane processes classically cover a wide range of applications associated with various aspects of separation and purification. Over the last few years, membrane based processes have received much interest due to their compact and modular architecture, low energy consumption and cost effective separation. With the development of diverse nanomaterials which can serve as nanosorbents, or provide specific morphology for selective solute transport, recent years have witnessed the emergence of nanocarbon based membranes that can address some of the limitations of conventional membrane processes and make feasible the next generation of breakthroughs.

The objective of this research is the exploration of …

Biogeochemistry Of Trace Elements In The Mixing Zone Of The Mississippi And Atchafalaya Rivers And Chemical Distributions As Affected By The Deepwater Horizon Blowout, Dongjoo Joung

Dissertations

Selected trace elements (TEs), dissolved organic carbon, and nutrients were studied in Louisiana Shelf waters including the Mississippi (MR) and Atchafalaya (AR) River plumes during periods of high, intermediate, and low river discharges. Seasonal variations in TEs were observed at low salinity, reflecting seasonal changes in the river water endmembers. Shelf surface water dissolved Mo, Cs, U, Ni, and Cu showed conservative behavior with minor scattering in some high salinity waters. Based on associated mixing experiments, nutrient and chlorophyll distributions, as well as surface-bottom concentration contrasts, the non-conservative behavior of TEs was variously related to colloidal flocculation (Fe, Cr), biological …

Synthesis, Characterization And Potential Applications Of Palladium And Ruthenium Nanostructures, Clara Patrice Adams

Dissertations

Controlling the size and shape of metal nanostructures is important for tuning the intrinsic chemical and physical properties of materials, and consequently their potential technological applications. Modulating the morphology of metal nanostructures is essential to understanding the structure-function relationship (for example, optical, magnetic, catalytic, and electronic properties) under various environmental conditions. Our work describes the development of new procedures for the synthesis of well-defined isotropic and anisotropic nanoparticles consisting of palladium (Pd) and ruthenium (Ru). Characterization of the nanostructures was carried out using transmission electron microscopy (TEM), high resolution-TEM (HRTEM), powder x-ray diffraction (XRD), selected area electron diffraction (SAED) and …

Size-Dependent Interactions Of Metal Nanoparticles With Fluorophores And Semiconductors, Liyana A. Wajira Ariyadasa

Dissertations

In recent years, nanoscale metallic particles have gained considerable interest due to their potential applications in advanced technology. Despite such interest, synthetic procedures that produce gram-scale, well-defined metallic nanoparticles with controlled size and shape, especially with diameters less than 5 nm remains a challenge. Our work has focused on developing synthetic procedures that produce well-defined platinum and palladium metal nanoparticles in the 1-5 nm size range. Thioether ligands were used as stabilizers and resulted in metal nanoparticles with controlled size. The nanoparticles were characterized using transmission electron microscopy (TEM), x-ray diffraction (XRD), selected area electron diffraction (SAED), x-ray photoelectron spectroscopy …

Fundamental Studies Of Protein Ionization For Improved Analysis By Electrospray Ionization Mass Spectrometry And Related Methods, Kevin A. Douglass

Dissertations

Mass spectrometry (MS) is an analytical technique in which a sample is converted to gas-phase ions that are subsequently separated and detected. It offers great speed, selectivity, and sensitivity during analysis, characteristics which have enabled it to become a leading method for the study of proteins. The applications of MS for these biologically significant macromolecules range from accurately determining identity and sequence to shedding light on post-translational modifications and protein-molecule interactions. As a first step towards analysis by MS, gas-phase protein ions must be formed. A common method for ionization is electrospray ionization (ESI), where a liquid sample including the …

Nanocarbons As Charge Carriers In Organic Solar Cells, Xinbo C. Lau

Dissertations

Organic photovoltaics (OPV) are an alternate to conventional silicon and thin film solar cells. They have several advantages such as simple fabrication, low material cost, light weight, and the ability to cover large areas. Typical OPV are based on bulk heterojunction structure consisting of a blend of an electron-donating semiconductor polymer and an electron-accepting molecule. Various approaches have been pursued to improve the performance of OPV: low bandgap polymers, new electron acceptors, processing additives, and tandem cell architecture.

Nanocarbons possess unique physical and chemical properties that can contribute to the enhancement of OPV performance, such as charge carrier mobility, thermal …

Investigating The Biochemical And Catalytic Properties Of Nitrile Hydratases, Salette Martinez

Dissertations

Chemical and pharmaceutical industries make extensive use of amide compounds for the manufacture of commodity chemicals (e.g., acrylamide) and drug intermediates (e.g., nicotinamide). Production of amide compounds is typically achieved by the hydration of nitrile compounds under acidic or basic conditions, high temperatures, and copper catalysts. However, the use of such chemical methods leads to the generation of unwanted by-products and toxic wastes, in addition to low product yields and high production costs. An alternative route for amide production is the use of a natural catalyst, for example nitrile hydratases (NHase, E.C. 4.2.1.84). NHase is a metalloenzyme that efficiently converts …

Polyaminocarboxylic Acids As Potential Candidates For Trivalent Actinide/Lanthanide Separations, Daniel Stephen Kissel

Dissertations

Nuclear energy, which has historically been considered an alternative energy solution in the United States, is regaining support as an efficient means of energy production. The viability of nuclear energy for the future, however, will remain suspect until issues involving the waste created are fully addressed in the next generation of advanced nuclear fuel cycles. The TALSPEAK process, developed at Oak Ridge National Laboratory, is a classic solvent extraction technique that employs a series of analytical separations in an effort to remove radioactive contaminants from spent nuclear fuel (SNF) and recover uranium in high purity. This separation utilizes a polyaminocarboxylic …

Investigation Of Chicago Air Pollution And Meteorological Influence On Pollution Development: Physical Measurements And Multivariate Statistical Analyses, Katrina Lyn Binaku

Dissertations

The goal of this project was to evaluate air pollutants and meteorology in Chicago, Illinois during summers 2010, 2011, and 2012. Sixty-six collection days of air pollutant and meteorological data were completed at the Loyola University Chicago sampling station atop Mertz Hall. Trace gases, nitrogen oxides and ozone, as well as the water-soluble fraction of aerosol material were the air pollutants of focus in this study. Data analysis showed that chloride, nitrate, sulfate, and oxalate were the most frequently quantified water-soluble ions in aerosol samples, followed by acetate, formate, potassium, phosphate, calcium, and magnesium ions. Ionic ratios showed that stationary …