Materials Chemistry Commons^™

Transition Metal Complexes With Reactive Trimethylsilylchalcogenolate Ligands: Precursors For The Preparation Of Ternary Nanoclusters, Chhatra Bahadur Khadka

Electronic Thesis and Dissertation Repository

The Co²⁺ and Mn²⁺ complexes (N,N´-tmeda)Co(ESiMe₃)₂ (E = S, 1a; E = Se, 1b), (3,5-Me₂C₅H₃N)₂Co(ESiMe₃)₂ (E = S, 2a; E = Se, 2b), [Li(N,N´-tmeda)]₂[(N,N´-tmeda)Mn₅(μ-ESiMe₃)₂(ESiMe₃)₄(μ₄-E)(μ₃-E)₂] (E = S, 3a; E = Se, 3b), [Li(N,N´-tmeda)]₂[Mn(SSiMe₃)₄] (4), [Li(N,N´-tmeda)]4[Mn₄(SeSiMe₃)₄(μ_{3 …}

Synthesis Of An Antimicrobial Textile Coating, William M. Morris

Chemistry and Biochemistry

A titania nanosol was synthesized and coated onto nylon/cotton blended textile substrates. The substrates were characterized via SEM for adhesion and nanoparticle formation, then subjected to antimicrobial efficacy tests. The titania nanosol was successfully coated on to textiles samples. Particles were observed to be around 2 by 3 micrometers and formed between the interstitial space of textile fibers. Although larger than typical nanoparticles, the coatings exhibited what seemed to be antimicrobial activity. Titania nanosol coated textile samples were subjected to Kirby Bauer Assay in the presence of S. aureus. The coated textile sample exhibited an inhibition of growth around its …

Polymer Nanocomposite Analysis And Optimization For Renewable Energy And Materials, Nathan Walter Henry

Doctoral Dissertations

Polymer nanocomposites are an important research interest in the area of engineering and functional materials, including the search for more environmentally materials for renewable energy and materials. The ability to analyze and optimize morphology is crucial to realizing their potential, since the distribution of materials in the composite strongly influences its properties. This dissertation presents research into three different polymer nanocomposite systems with three different applications that underscore the need to understand and control the composite morphology to succeed.

The first project details work on development of a copolymer compatibilizer to enhance the dispersion of the plant-derived biopolymer lignin in …

Electrochemistry Of Pani/Metal Composites In Basic Solutions, Tamthinhan Quy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively investigated due to its unique conductivity, which is primarily dependent on the oxidation state of the material and the solution pH. PANI is an insulator when it is oxidized, and the solution pH exceeds four. Numerous attempts to extend PANI's conductivity to neutral and alkaline environments have been unsuccessful. However, our previous study has demonstrated that PANI/Pd composite is conductive and catalytically active in a basic solution, pH ∼ 12. Therefore, the conductivity and the electrochemical properties of PANI composites including PANI/Au, PANI/Pd and PANI/Pt were evaluated in basic solutions. The fundamental studies of PANI/metal …

The Investigation Of Asphaltene-Naphithenic Acid And Asphaltene-Surface Interactions, David Tristan Heaps

Dissertations

Asphaltenes represent a ubiquitous problem in the oil industry due to their adverse effects on recovery, production, and processing equipment. These problems have affected oil companies throughout the world, resulting in significant financial losses. In order to expand the existing body of knowledge related to asphaltenes, we have examined how the presence of naphthenic acids contributes to the particle aggregation and sedimentation behavior of asphaltene suspensions as well as how the physics and chemistry of a substrate affect asphaltene adsorption/deposition.

The flocculation of asphaltenes in the presence of naphthenic acids was investigated using dynamic light scattering (DLS), near-infrared spectroscopy (NIR), …

Preparation And Characterization Of Biomimetic Hydroxyapatite-Resorbable Polymer Composites For Hard Tissue Repair, Kristopher R. Hiebner

Student Research Projects, Dissertations, and Theses - Chemistry Department

Autografts are the orthopedic “gold standard” for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide …

Spectroscopic Methods Of Process Monitoring For Safeguards Of Used Nuclear Fuel Separations, Jamie Lee Warburton

UNLV Theses, Dissertations, Professional Papers, and Capstones

To support the demonstration of a more proliferation-resistant nuclear fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. An ideal materials accountability technique for proliferation resistance should provide nondestructive, realtime, on-line information of metal and ligand concentrations in separations streams without perturbing the process. UV-Visible spectroscopy can be adapted for this precise purpose in solvent extraction-based separations.

The primary goal of this project is to understand fundamental URanium EXtraction (UREX) and Plutonium-URanium EXtraction (PUREX) reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. By …

The Tetrafluoroborate Salt Of 4-Methoxybenzyl N-2-(Dimethylamino)Ethyl-N-Nitrosocarbamate: Synthesis, Crystal Structure And Dft Calculations, Helene Hedian, Vladimir Benin

Chemistry Faculty Publications

The tetrafluoroborate salt of 4-methoxybenzyl N-2-(dimethylamino)ethyl-N-nitrosocarbamate was prepared in two steps, via the corresponding carbamate. Its crystal structure is monoclinic, space group P21/c. The unit cell dimensions are: a = 19.499(8) Å, b = 5.877(3) Å, c = 15.757(7) Å, α = 90°, β = 110.019(7)°, γ = 90°, V = 1696.5(12) Å3, Z = 4. The structure exhibits an unexpected, pseudo-gauche conformation with respect to the C2–C3 bond, due to a stabilizing hydrogen bond between the carbonyl oxygen (O1) and the hydrogen atom at the trialkylammonium center (H3n), with a distance between them of …

Investigating Interfacial Reactions Of Silver-Containing Films Using Novel Methods, Sarah Danielle Pretty

Electronic Thesis and Dissertation Repository

This thesis presents work on the mechanism and kinetics of the surface film reactions involving the conversion of aqueous species on solid surfaces, and specifically, the reactions of iodide and bromide on silver oxide on silver substrate. These reactions provide a method of immobilizing unwanted halides and are particularly suited to control of hazardous radioactive iodine. Potential applications of this research include nuclear reactor safety and post-accident radioiodine management, and the safe production and use of the medical isotope ¹³¹I.

The aqueous-solid conversion of reaction Ag₂O with X^-(aq) to form AgX on a Ag substrate …

Preparation And Characterization Of A Composite Of Gold Nanoparticles And Single-Walled Carbon Nanotubes And Its Potential For Heterogeneous Catalysis, Anne Shanahan, James Sullivan, Mary Mcnamara, Hugh Byrne

Articles

A single-walled carbon nanotube-supported gold nanoparticle composite was prepared and characterized by X-ray diffraction, scanning transmission electron microscopy/scanning electron microscopy/transmission electron microscopy, energy-dispersive X-ray analysis, atomic absorption spectroscopy, nitrogen adsorption, Raman spectroscopy, and ultraviolet-visible spectroscopy. The Au particles were found to be crystalline, with a well-defined and narrow particle-size distribution, centered around 7 nm. The activity and selectivity of the composite for solventless aerobic oxidation of a secondary alcohol were examined, and a conversion efficiency of 95% was obtained.

Wetting Properties Induced In Nano-Composite Poss-Ma Polymer Films By Atomic Layer Deposited Oxides, Kyle A. Vasquez, Anita J. Vincent-Johnson, W. Chris Hughes, Brian H. Augustine, Kyoungmi Lee, Gregory N. Parsons, Giovanna Scarel

Department of Physics and Astronomy - Faculty Scholarship

Due to their unique properties, nano-composite polyhedral oligomeric silsequioxane (POSS) copolymer films are attractive for various applications. Here we show that their natural hydrophobic character can become hydrophilic when the films are modified by a thin oxide layer, up to 8 nm thick, prepared using atomic layer deposition. A proper choice of the deposition temperature and thickness of the oxide layer are required to achieve this goal. Unlike other polymeric systems, a marked transition to a hydrophilic state is observed with oxide layers deposited at increasing temperatures up to the glass transition temperature (∼110 °C) of the POSS copolymer film. …

Electronic And Magnetic Excitations In Graphene And Magnetic Nano-Ribbons, Maher Zakaria Ahmed Selim

Electronic Thesis and Dissertation Repository

The discovery of graphene - a 2D material with superior physical properties - in 2004 was important for the intensive global research to find alternatives to three-dimensional (3D) semiconductor materials in industry. At the same time there have been exciting advances for 2D magnetic materials on the nanometer scale. The superior properties of graphene are mainly attributed to its crystal structure and its relatively short-range interactions. These properties show that natural and artificial 2D materials are promising for new applications.

In this thesis we have carried out a comprehensive investigation of the effects of the 2D lattice structures, the roles …

A Modified Surface On Titanium Deposited By A Blasting Process, Caroline O' Sullivan, Peter O'Hare, Greg Byrne, Liam O'Neill, Katie B. Ryan, Abina M. Crean

Publications

Abstract

: Hydroxyapatite (HA) coating of hard tissue implants is widely employed for its biocompatible and osteoconductive properties as well as its improved mechanical properties. Plasma technology is the principal deposition process for coating HA on bioactive metals for this application. However, thermal decomposition of HA can occur during the plasma deposition process, resulting in coating variability in terms of purity, uniformity and crystallinity, which can lead to implant failure caused by aseptic loosening. In this study, CoBlast™, a novel blasting process has been used to successfully modify a titanium (V) substrate with a HA treatment using a dopant/abrasive regime. …

Rational Design And Advanced Fabrication Of Metallic Nanostructures For Surface-Enhanced Raman Spectroscopy, Betty Cristina Galarreta

Electronic Thesis and Dissertation Repository

One of the main challenges in analytical science and technology is to develop devices that provide unambiguously the chemical nature of the material of interest with the minimum intrusiveness, the smallest amount of analyte, and the shortest acquisition time. Among the promising methods for such purpose, optical spectroscopy such as surface-enhanced Raman scattering is considered a suitable option. This spectroscopic technique takes advantage of the interaction between an optical field and metallic nanostructures to magnify the electromagnetic field in the vicinity of the nanostructure, resulting in an amplified signal of the vibrational fingerprints of the adsorbed molecules onto the metallic …

Understanding Molecular Chemistry Of Nanocrystals And Nanostructures: Precursor, Ligand, And Surface Chemistry, Weon-Kyu Koh

Publicly Accessible Penn Dissertations

The aim of this dissertation is to understand the molecular chemistry of nanomaterials and to correlate their structures to their functions. The first part of this dissertation explores how we can use precursor chemistry to develop a synthetic approach to novel structures of nanomaterials. There will be a demonstration of morphology control in lead chalcogenide nanocrystals following an investigation of the precursor chemistry which gives valuable information on precursor decomposition during the crystal growth. At the same time, there will be a discussion about how we can understand structure-dependent properties of nanomaterials using advanced spectroscopic techniques. Well-established synthetic approaches discussed …

X-Ray Photoelectron Spectroscopy Studies On The Oxidation Processes Of Nickel, Chromium And Their Alloys, Bradley P. Payne

Electronic Thesis and Dissertation Repository

The reaction of polycrystalline Ni metal surfaces with low pressures (~ 130 Pa) of O₂ gas or H₂O vapour produced thin defective nickel oxide films containing both Ni²⁺ and Ni³⁺ species at 25^oC and 300^oC. Exposure of Ni metal samples to H₂O vapour resulted in a much slower reaction rate when compared to similar doses of O₂ gas. This difference was attributed to a slower place exchange with a surface hydroxyl (OH (ads)) intermediate compared to that of an adsorbed oxygen atom (O (ads)). This OH (ads) species …

Effect Of Au Content On Microstructural Evolution Of Snagcu Solder Joints That Undergo Isothermal Aging And Reliability Testing, Patrick J. Hyland

Master's Theses

Electronics, especially, printed circuit boards (PCBs) are a widespread technology. Metal coatings or “surface finishes” are often added to PCB board pads and component leads during manufacturing to improve their performance. Electroplated nickel/gold over copper is a popular surface finish for printed circuit boards and component leads. The presence of gold in solder joints, however, is known to have detrimental effects referred to as gold embrittlement. It is generally understood that tin-lead solder joints with less than 3 weight percent (wt%) of gold will not experience reliability issues. The acceptable level of gold in lead-free solder joints, however, is less …

Vapor Liquid Solid Growths Of Germanium And Gallium Antimonide Nanowires, Ralph Alvarez, Esmeralda Arreola, Michael Oye, Meyya Meyyappan

STAR Program Research Presentations

Determining the optimal growth parameters for germanium (Ge) and gallium antimonide (GaSb) nanowires is the focus of this research. Given the fact that nano materials behave differently from their bulk counterparts we are researching some variables that influence nanowire diameter and length such as temperature, ramp rate, gas flow rate, and catalyst particle size. Based on the nano material size which is typically a few 10s of nanometers wide, these nano materials can be engineered to take advantage of their optical properties. Specifically the infrared (IR) response of Ge and GaSb nanowires are directly controllable based on their geometry. Fine …

Effects Of Ambient Gases On Icf Target Capsules, Bryan Chambers, Steve Letts, Michael Stadermann

STAR Program Research Presentations

We researched how the chemical and physical properties of a plasma polymer fuel capsule change as they are exposed to ambient gases. The fuel capsules contain the deuterium fuel inside them, they serve as the outer shell for the fuel and act as a ablator for the process. If they are reactive or diffusive with the atmosphere this can change their mass and effect the outcome of the fusion shots performed at the National Ignition Facility where High Powered Lasers are incident upon a gold hohlraum containing a capsule. We discovered that nitrogen and water vapor diffuse into the material …

Single-Step Biofriendly Synthesis Of Surface Modifiable, Near-Spherical Gold Nanoparticles For Applications In Biological Detection And Catalysis, Vivek D. Badwaik

Masters Theses & Specialist Projects

There is an increased interest in understanding the toxicity and rational design of gold nanoparticles (GNPs) for biomedical applications in recent years. Such efforts warrant reliable, viable, and biofriendly synthetic methodology for GNPs with homogeneous sizes and shapes, particularly sizes above 30 nm, which is currently challenging. In the present study, an environmentally benign, biofriendly, singlestep/ single-phase synthetic method using dextrose as a reducing and capping agent in a buffered aqueous solution at moderate temperature is introduced. The resulting GNPs are near-spherical, stable, catalytically active, place exchangeable, and water-soluble within the size range of 10-120 nm. The added advantage of …