Physical Sciences and Mathematics Commons^™

Neutron Study Of Structured Polymers At Interfaces, Thusitha Etampawala

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This work focuses on interfacial structure and dynamics of structured polymers in thin films and in solutions using neutron techniques accompanied by atomic force microscopy. We probed polymers with a common theme that were highly segregated either because of presence of ionic groups or topological constraints. In these polymers the interfacial regions often define their function in different applications such as clean energy, printing adhesions and drug delivery systems. Thin film studies include systems of polystyrene/sulfonated polystyrene, a rigid sulfonated polyphenylene and polystyrene three-arm stars/linear polystyrene. The first two systems include ionic components and the last exhibits topological constraints. Polystyrene …

Exploratory Synthesis Of New Iron(Ii,Iii)-Containing Polyanion Framework Solids Of Electrochemical And Magnetic Interest, Liurukara Sanjeewa

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The studies demonstrated in this dissertation were primarily focused on the synthesis, structure and property characterizations of iron(II,III) containing framework solids. The scope of this research is threefold: 1) explore new iron(II, III)-containing open framework structures in hopes of creating new materials, useful in the areas of both Li- and Na-ion battery applications; 2) synthesis and characterization of low-dimensional magnetic nanostructures exhibiting novel magnetic properties due to confined magnetic lattices; and 3) conduct structure/property correlation studies to identify the origins of any unusual physical phenomena associated with these new compounds.

In the syntheses of new compounds, molten salt fluxes were …

The Fabrication And Study Of Silver Nanoparticle Structures, Aubrie Pfirman

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Nanotechnology and the synthesis of nanoparticle systems are attractive in part because of interesting, tunable optical and electrical properties that are not observed with bulk material. Silver nanoparticles (Ag NPs) interact with visible light more efficiently than any other system due to the excitation of plasmon resonances, which are the collective oscillations of the free electron density. These collective oscillations produce an enhanced local electromagnetic (EM) field: this field is responsible for highly-utilized phenomena such as surface enhanced Raman scattering (SERS), enhanced fluorescence, surface enhanced infrared absorption (SEIRA), and many others. Many experiments have been conducted to optimize and tailor …

Molecular Dynamics Simulations Using Advanced Sampling And Polarizable Force Fields, Tugba Kucukkal

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Molecular dynamics (MD) simulations were carried out for aqueous dipeptides, water over self-assembled monolayer (SAM) surfaces, and the nicotinic acetylcholine receptor (nAChR) ion channel. The main goal is to use advanced methods to increase the accuracy of molecular dynamics simulations while seeking solutions to problems relevant to chemistry, biophysics and materials science. In addition, activation energies of several cyclodimerization reactions were studied quantum mechanically. The simulations of the aqueous dipeptides and SAM surfaces involve modeling and detailed analysis of interfacial water, which is of interest to a range of fields from biology to materials science. For example, water has a …

Bond-Centric Modifications To Bond-Order Potentials And Ab-Initio Evaluation Of Nanostructured Materials Properties, Jaewoong Hur

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An improvement to the AIREBO potential for hydrocarbons is presented in which contribu-tions to the bond order are determined by the local bonding environment around the bond, rather than the average of the environments around the two constituent atoms. This bond-centric approach decreases the errors by ∼80% in the fullerene-type systems for which the original approach leads to the most severe errors. With the newly developed and parameterized method, energy errors are less than 0.7eV for a collection of hydrocarbon molecules not used in the fitting. This modified AIREBO potential is expected to be more useful not only for the …

Analyses Of Multivitamins In Nutraceuticals By Reverse Phase Hplc With Dad, Elsd And Ms, Hsiang-Chi Huang

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ABSTRACT
Vitamins are essential to human beings and support long-term healthy lifestyle. They exist widely in food, but in small amount. Hence, dietary supplements and fortified food products are more and more popular in the nutritional markets. According to the Infant Formula Act of 1980, the range of each of the nutrients should fall within a specific range or above the required minimum, so there is an increasing interest of accurate measurement of vitamins, particularly the B-group vitamins. However, traditional methods for vitamin B analyses are time-consuming and often in poor accuracy. As a result, rapid and reliable analytical methods …

Hydrothermal Chemistry, Crystal Structures, And Spectroscopy Of Novel Fluorides And Borates, Christopher Underwood

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This dissertation is a two-part manuscript highlighting the utilities of the hydrothermal method for exploring phase space, then extending that to the targeted growth of potentially useful materials. Chapters 3 - 5 discuss the synthesis of Group 4 fluorides and oxyfluorides. The study of this class of compounds in regards to their single crystal structures is a rich, but neglected area. Among the Group 4 metals, compounds based on Zr and Ti have been extensively studied, while those based on Th and Hf are sparsely reported and those based on Ce(IV) are nearly completely neglected. Using the hydrothermal method, many …

Hydrothermal Crystal Growth Of Metal Borates For Optical Applications, Carla Heyward

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Crystals are the heart of the development of advance technology. Their existence is the essential foundation in the electronic field and without it there would be little to no progress in a variety of industries including the military, medical, and technology fields. The discovery of a variety of new materials with unique properties has contributed significantly to the rapidly advancing solid state laser field. Progress in the crystal growth methods has allowed the growth of crystals once plagued by difficulties as well as the growth of materials that generate coherent light in spectral regions where efficient laser sources are unavailable. …

Bombardment Of Graphite And Amorphous Carbon Surfaces Using Molecular Dynamics Simulations: Toward A More Realistic Experimental Model, Marcel Fallet

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Molecular dynamics (MD) simulations are a useful computational tool in fields such as fusion research. Small but vital portions of fusion reactors are essential to their correct operation and longevity. Using the reactive bond order (REBO) and adaptive intermolecular REBO potentials, it is possible to model carbon-based systems, such as graphite diverter plates, under simulated bombardment. The degradation of these plates due to random bombardments from plasma can eventually incur costly shut downs. To gain a better understanding of the atomic-level dynamics that occur when a graphite and amorphous carbon surface undergo energetic, serial bombardment by atoms such as hydrogen, …

Synthesis And Characterization Of Chromophores And Semiconducting Polymers Incorporating A 1,4-Fluorenylene Scaffold, Brynna Laughlin

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Research on conjugated chromophores and polymers has been a lucrative and highly active area for over a quarter-century. These pursuits have been driven by the unique properties of conjugated systems that allow their application in myriad fields including photonics (e.g. non-linear optics), and especially optoelectronics (e.g. organic light emitting diodes (OLEDs) and photovoltaic (PV) cells). Despite the years of dedicated research, there is still much work to be done in developing better materials for these types of applications. The full range of available molecular architecture and functionalization that are yet to be explored is still an untapped well of research. …