Digital Commons Network^™

The Dawn Of New Quantum Dots: Synthesis And Characterization Of Ge1-Xsnx Nanocrystals For Tunable Bandgaps., Richard J. Esteves

Theses and Dissertations

Ge_1-xSn_x alloys are among a small class of benign semiconductors with composition tunable bandgaps in the near-infrared spectrum. As the amount of Sn is increased the band energy decreases and a transition from indirect to direct band structure occurs. Hence, they are prime candidates for fabrication of Si-compatible electronic and photonic devices, field effect transistors, and novel charge storage device applications. Success has been achieved with the growth of Ge_1-xSn_x thin film alloys with Sn compositions up to 34%. However, the synthesis of nanocrystalline alloys has proven difficult due to larger discrepancies (~14%) in …

The Development Of Bicyclic Peptide Library Scaffolds And The Discovery Of Biostable Ligands Using Mrna Display, David E. Hacker

Theses and Dissertations

Peptides are a promising class of therapeutic candidates due to their high specificity and affinity for cellular protein targets. However, peptides are susceptible to protease degradation and are typically not cell-permeable. In efforts to design more effective peptide drug discovery systems, investigators have discovered that incorporation of non-canonical amino acids (ncAAs) and macrocyclization overcome these limitations, making peptides more drug-like.

In this work, we exploit the promiscuity of wild-type aminoacyl-tRNA synthetases (aaRSs) to ‘mischarge’ ncAAs onto tRNA and ribosomally incorporate them into peptides using a cell-free translation system. We have demonstrated the ability to incorporate five ncAAs into a single …

Probing Allosteric, Partial Inhibition Of Thrombin Using Novel Anticoagulants, Stephen S. Verespy Iii

Theses and Dissertations

Thrombin is the key protease that regulates hemostasis; the delicate balance between procoagulation and anticoagulation of blood. In clotting disorders, like deep vein thrombosis or pulmonary embolism, procoagulation is up-regulated, but propagation of clotting can be inhibited with drugs targeting the proteases involved, like thrombin. Such drugs however, have serious side effects (e.g., excessive bleeding) and some require monitoring during the course of treatment. The reason for these side effects is the mechanism by which the drugs’ act. The two major mechanisms are direct orthosteric and indirect allosteric inhibition, which will completely abolish the protease’s activity. Herein we sought an …

Versatile Synthesis Of Transition Metal Phosphides: Emerging Front-Runners For Affordable Catalysis, April C. Mattei

Theses and Dissertations

Transition metal phosphide materials have found themselves at the forefront of research revolving around energy applications. Due to the vast range of properties possessed by marginally different phase compositions, binary and ternary metal phosphides are utilized as catalysts, semi-conductors and magnetocaloric materials along with many others. These attractive properties, which are highly phase dependent, call for a versatile and cost effective synthesis route for various phosphide materials without sacrificing properties important at the nanoscale such as particle size and morphology.

The primary focus outlined in the work of this dissertation pertains to a versatile wet chemical synthesis capable of producing …

Fabricating Superhydrophobic And Superoleophobic Surfaces With Multiscale Roughness Using Airbrush And Electrospray, Karam N. Almilaji

Theses and Dissertations

Examples of superhydrophobic surfaces found in nature such as self-cleaning property of lotus leaf and walking on water ability of water strider have led to an extensive investigation in this area over the past few decades. When a water droplet rests on a textured surface, it may either form a liquid-solid-vapor composite interface by which the liquid droplet partially sits on air pockets or it may wet the surface in which the water replaces the trapped air depending on the surface roughness and the surface chemistry. Super water repellent surfaces have numerous applications in our daily life such as drag …

Continuous Stationary Phase Gradients For Planar And Column Chromatography, Veeren Dewoolkar

Theses and Dissertations

Surfaces that exhibit a gradual change in their chemical and/or physical properties are termed as surface gradients. Based on the changes in properties they are classified either as physical or chemical gradients. Chemical gradients show variations in properties like polarity, charge, functionality concentration and have found potential applications in fields of biology, physics, biosensing, catalysis and separation science. In this dissertation, surface gradients have been prepared using controlled rate infusion (CRI).

CRI is a simple method in which a surface gradient is formed by carrying out the infusion of organoalkoxysilane in a time-dependent fashion using a set infusion rate. Depending …

Fabrication Of Multifunctional Nanostructured Porous Materials, Ahmed A. Farghaly

Theses and Dissertations

Nanostructured porous materials generally, and nanoporous noble metals specifically, have received considerable attention due to their superior chemical and physical properties over nanoparticles and bulk counterparts. This dissertation work aims to develop well-established strategies for the preparation of multifunctional nanostructured porous materials based on the combination of inorganic-chemistry, organic-chemistry and electrochemistry. The preparation strategies involved one or more of the following processes: sol-gel synthesis, co-electrodeposition, metal ions reduction, electropolymerization and dealloying or chemical etching. The study did not stop at the preparation limits but extended to investigate the reaction mechanism behind the formation of these multifunctional nanoporous structures in order …

Interactions Of The Naphthalene Radical Cation With Polar And Unsaturated Molecules In The Gas Phase, Sean P. Platt

Theses and Dissertations

Characterizing the interactions of solvent molecules with ions is fundamental in understanding the thermodynamics of solution chemistry. These interactions are difficult to observe directly in solution because the number of solvent molecules far exceed that of ions. This lend the gas phase to be the ideal medium in the study ion-solvent interactions on a molecular level. Ionized polycyclic aromatic hydrocarbon (PAH) molecules can readily form hydrogen bonds with neutral solvent molecules in aqueous and interstellar medium. Previous research has been done for stepwise solvation of small molecules such as benzene⁺, pyridine, and phenylacetylene. The similarity in these results …

Systematic Postsynthetic Modification Of Nanoporous Organic Frameworks And Their Performance Evaluation For Selective Co2 Capture, Timur Islamoglu

Theses and Dissertations

Porous organic polymers (POPs) with high physicochemical stability have attracted significant attention from the scientific community as promising platforms for small gas separation adsorbents. Although POPs have amorphous morphology in general, with the help of organic chemistry toolbox, ultrahigh surface area materials can be synthesized. In particular, nitrogen-rich POPs have been studied intensively due to their enhanced framework-CO₂ interactions. Postsynthetic modification (PSM) of POPs has been instrumental for incorporating different functional groups into the pores of POPs which would increase the CO₂ capture properties. We have shown that functionalizing the surface of POPs with nitro and amine groups …

Sol-Gel Assembly Of Metal Nanostructures Into Metallic Gel Frameworks And Their Applications, Xiaonan Gao

Theses and Dissertations

The advent of nanoscience and nanotechnology has sparked many research forefronts in the creation of materials with control over size, shape, composition, and surface properties.^1,2 However, for most of the applications, nanoscale materials need to be assembled into functional nanostructures that exhibit useful and controllable physical properties. Therefore, numerous efforts on the assembly of nanoparticles (NPs) using organic ligands, polymers and polyelectrolytes have been reported.^3,4 However, the interactions between NPs are mediated by intervening ligands, which are detrimental to charge transport and limit the thermal stability. Hence, developing a new method to produce solid …

Measurement Of Rare Earth And Uranium Elements Using Laser-Induced Breakdown Spectroscopy (Libs) In An Aerosol System For Nuclear Safeguards Applications, Ammon N. Williams

Theses and Dissertations

The primary objective of this research is to develop an applied technology and provide an assessment for remotely measuring and analyzing the real time or near real time concentrations of used nuclear fuel (UNF) elements in electrorefiners (ER). Here, Laser-Induced Breakdown Spectroscopy (LIBS) in UNF pyroprocessing facilities was investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the …

Laser Vaporization Controlled Condensation And Laser Irradiation In Solution For The Synthesis Of Supported Nanoparticle Catalysts, Vitaly Kisurin Mr.

Theses and Dissertations

Solid catalyst supports of SiOx-RGO (Reduced Graphene Oxide) and UiO-67 (Universitet i Oslo) have been successfully synthesized and were loaded with palladium nanoparticles to test for a series of heterogeneous reactions. The SiOx/RGO catalysts were synthesized through laser ablation of silicon and graphite oxide micron powder and UiO-67 metal-organic framework (MOF) was synthesized through mixing of precursors with DMF/HCl solution and washing the resultant powder from impurities. The SiOx/RGO supports were later impregnated with palladium precursors which were then subject to Microwave Irradiation (MWI). The UiO-67 framework was impregnated with palladium precursors and was irradiated with pulsed Nd:YAG 532 nm …

Drying Methods For The Fabrication Of Polymer Foam Material, Dalton Echard

Theses and Dissertations

This is a report on the study of the drying of nanoporous polymer foam material fabricated by photolithogtaphic methods. Three drying methods were employed, which were air drying, supercritical drying and freeze drying. After fabrication and drying, physical properties of the polymer foams were measured. These measurements included density of the material, Young’s modulus, surface area, and the shape of the skeletal particles. The measurements determined the effect of the polymer concentration and the effect of drying methods. It was determined that polymer concentration had a much larger effect on the properties of the materials than the drying method.

Non-Conventional Approaches To Syntheses Of Ferromagnetic Nanomaterials, Dustin M. Clifford

Theses and Dissertations

The work of this dissertation is centered on two non-conventional synthetic approaches to ferromagnetic nanomaterials: high-throughput experimentation (HTE) (polyol process) and continuous flow (CF) synthesis (aqueous reduction and the polyol process). HTE was performed to investigate phase control between Fe_xCo_1-x and Co_3-xFe_xO_y. Exploration of synthesis limitations based on magnetic properties was achieved by reproducing M_s=210 emu/g. Morphological control of Fe_xCo_1-x alloy was achieved by formation of linear chains using an H_ext. The final study of the Fe_xCo_1-x chains used DoE to …

Electronic Structure And Stability Of Ligated Superatoms And Bimetallic Clusters, William H. Blades

Theses and Dissertations

Quantum confinement in small metal clusters leads to a bunching of states into electronic shells reminiscent of shells in atoms. The addition of ligands can tune the valence electron count and electron distribution in metal clusters. A combined experimental and theoretical study of the reactivity of methanol with Al_nI_m⁻ clusters reveals that ligands can enhance the stability of clusters. In some cases the electronegative ligand may perturb the charge density of the metallic core generating active sites that can lead to the etching of the cluster. Also, an investigation is conducted to understand how the bonding …

Chemometric Curve Resolution For Quantitative Liquid Chromatographic Analysis, Daniel W. Cook

Theses and Dissertations

In chemical analyses, it is crucial to distinguish between chemical species. This is often accomplished via chromatographic separations. These separations are often pushed to their limits in terms of the number of analytes that can be sufficiently resolved from one another, particularly when a quantitative analysis of these compounds is needed. Very often, complicated methods or new technology is required to provide adequate separation of samples arising from a variety of fields such as metabolomics, environmental science, food analysis, etc.

An often overlooked means for improving analysis is the use of chemometric data analysis techniques. Particularly, the use of chemometric …