Digital Commons Network^™

The Effects Of Fast Secondary Electrons On Low Voltage Electron Beam Lithography, Mehdi Bolorizadeh

Doctoral Dissertations

In 1981 Prof. Sir Alec Broers suggested that the spatial limit of direct writing electron beam lithography (DWEBL) would be limited to ~10 nm by the laterally scattered fast secondary electrons (FSE) even in atomically thin resist. Experiments and simulations have been carried out to quantify the contribution of FSE to the energy deposition that results in exposure of the resist over high beam energies. One possible solution to this restriction would be to use low energy electrons.

To examine Broers' hypothesis in low voltage electron beam lithography (EBL), studies in the low energy range on the effects of FSE …

The Effect Of Mobile Phase Composition And Temperature On The Adsorption Behavior Of Tryptophan, Tarab Jamil Ahmad

Doctoral Dissertations

Single-component adsorption isotherm data were acquired by frontal analysis for tryptophan on a C₁₈-Kromasil packed column, using acetonitrile-water solutions of various compositions (2.5, 5, and 7.5% ACN + 1% ACOH). These isotherms have a complex behavior, exhibiting at least one clear inflection point at an intermediate concentration and, possibly, another such point, close to the origin. The isotherm for 2.5 % ACN has the strongest curvature. At high concentrations, all these isotherms tend toward a limit, showing that the adsorbent has a finite saturation capacity. At low concentrations, these isotherms seem to exhibit langmuirian behavior. The isotherm model …

Linear And Nonlinear Chiroptical Effects, Watheq Ahmad Al-Basheer

Doctoral Dissertations

Chiroptical effects of linear and nonlinear nature are investigated by employing a variety of spectroscopic methods, such as linear and nonlinear circular dichroism, optical rotation, vibrational Raman scattering, infrared absorption and Vibrational Circular Dichroism. (2+1) Resonance Enhanced Multiphoton Ionization Circular Dichroism (REMPICD) is a direct demonstration of the nonlinear chiroptical effects of a sample of R-(+)-3-methylcyclopentanone. Solvent effects on circular dichroism is studied for 35 common solvents, which is significantly attributed to the solute- solvent electrostatic and Van der waals interactions for CD and ORD of R3MCP. Hartree-Fock and Density Function Theoretical calculations of R3MCP CD and …

Combined Study Of Reactor And Terrestrial Antineutrinos With Kamland, Mikhail Batygov

Doctoral Dissertations

This dissertation presents a combined study of antineutrinos of terrestrial and reactor origin detected by Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND). Of special physical interest are neutrino oscillation parameters and the terrestrial antineutrino flux, the former being of a profound importance for new physics beyond the Standard Model, and the latter having significant implications for geophysics. The analysis described here uses a comprehensive likelihood model to naturally combine terrestrial and reactor antineutrino studies within a single framework. The use of this likelihood model and better event reconstruction tools allowed to obtain narrower limits for the oscillation parameters and the terrestrial …

Interference Effects Among J = 3/2+ Resonances In 19Ne System & Searching For Resonances In The Unbound 6Be Nucleus, Kyung Yuk Chae

Doctoral Dissertations

The ¹⁸F(p,α)¹⁵O reaction plays a crucial role in understanding γ-ray emission from novae. Because of the importance of understanding the ¹⁸F + p reactions, a number of studies of the A=19 isobars have been made using stable and exotic beams. The interference effects among J ^π = 3/2⁺ resonances in the ¹⁸F + p system, however, have never been measured, but they can change the S-factor by a factor of 20 at nova energies. R-matrix calculations indicate that the cross sections above the Ec.m. = 665 keV resonance are sensitive …

Single-Molecule Detection With Active Transport, David Allan Ball

Doctoral Dissertations

A glass capillary is used near the focal region of a custom-built confocal microscope to investigate the use of active transport for single-molecule detection in solution, with both one and two-photon laser excitation. The capillary tip has a diameter of several microns and is carefully aligned nearby to the sub-micron laser beam waist, collinear to the optical axis, so that a negative pressure-difference causes molecules to be drawn into the capillary, along the laser beam axis. The flow of solution, which is characterized by fluorescence correlation spectroscopy (FCS), can increase the single-molecule detection rate for slowly diffusing proteins by over …

Regularization Of The Particle-Particle Interaction In The Nuclear Density Functional Theory, Piotr Jerzy Borycki

Doctoral Dissertations

In this work we show how to regularize the ultraviolet divergences appearing in the local pairing term of the energy density functional. Our approach, entirely rooted in the framework of the Density Functional Theory, is based on the regularization of local densities and currents and can be applied to various classes of energy density functionals. We demonstrated, that for the particular choice of the pairing term of energy density functional, our procedure gives the same regularization scheme to the one obtained earlier by the means of the pairing gap regularization.

We also investigated the non-unitarity of the Bogoliubov tranformation due …

Thermodynamic And Neutron Structural Studies Of Hydrocarbon Adsorption On Mgo Nanocubes, Richard E. Cook

Doctoral Dissertations

Presented is a series of thermodynamic and neutron scattering experiments used to probe the nature of the hydrocarbon - MgO (100) interaction. High-resolution volumetric isotherms are used to probe the wetting, layer transitions, heats of adsorption, two-dimensional compressibilities, and identify possible phase transitions of thin films of benzene, ethane, and n - pentane on MgO powders. Neutron diffraction experiments were used to probe the structure and identify any phase transitions within monolayer films of ethane, butane and n -pentane.

Benzene adsorption, while showing no visible layering steps, shows a shift in the shape of the isotherm for p/p_o > 0.7. …

Characterization Of Aβ Aggregates Using Hydrogen/Deuterium Exchange Mass Spectrometry, Maolian Chen

Doctoral Dissertations

The work presented in this dissertation aimed to localize the hydrogen-bonding interaction sites within Aβ aggregates associated with Alzheimer’s disease using hydrogen/deuterium exchange mass spectrometry (HDX-MS) coupled with proteolysis. Toward this end, an on-line digestion system utilizing a triaxial electrospray probe as the front end to MS was developed. Using this approach, regions of Aβ(1-40) fibrils and protofibrils that are protected from HDX have been identified. The HDX data show that the C-terminal segment 35-40 and the N-terminal segment 1-19 are highly exposed to exchange in both fibrils and protofibrils, while the internal fragment 20-34 is highly protected from exchange …

Direct Integration Of Surface Enhanced Raman Spectroscopy As A Detection Mode For Microfluidic Separations And Fluid Handling: Μfluidic-Sers, Raynella Magdalene Connatser

Doctoral Dissertations

The arena of microfluidics (µfluidics) has grown over the past decade to encompass myriad separation techniques and exploit copious detection modes. The direct integration of a vibrational spectroscopic detection technique, rich with structural information, onto a platform that is portable and potentially highly controllable such as µfluidics, could offer redress for some of the problems inherent in many of the electrophoretically driven separations carried out on said devices. Herein, this direct integration is explored, and methods of device fabrication, spectroscopic data collection conditions, analytical figures of merit of the detection technique, and separations method development results are discussed. The creation …

Management Of Requirements Changes In Sequence-Based Software Specifications, Lan Lin

Doctoral Dissertations

The sequence-based software specification method was developed to convert ordinary, or typical requirements and requirements statements into mathematically precise specifications, at an acceptable level of abstraction, for deterministic systems. In view of the iterative nature of modern software developing process, requirements, once defined, are not frozen; changes are integrated continuously that need to be accommodated and validated.

The need for managing changes of requirements in sequence-based specifications arises both as a consequence of practicing this method and as a general topic in software requirements engineering. In this research we have explored the theoretical consequences of three major requirements changes in …

The Reaction Of Telechelic Polymers At Multicomponent Interfaces: A Molecular Loop Study, James Kevin Rice

Doctoral Dissertations

The work presented in this dissertation attempts to form an understanding of the reaction parameters that govern the reaction of telechelic polymers to form multiply bound polymer chains, resulting in polymer loop formation, at both soft and hard polymeric interfaces. Both theoretical and experimental studies offer evidence that blocky copolymers, as opposed to random or alternating morphologies, are the best compatibilizers of a given polymer blend system. This has been attributed to the fact that blocky copolymers spread across the interface, with each block lying in or near the homopolymer region in which it is miscible, effectively “stitching” the interface …

Measurement Of The 32S(P,D)31S Reaction And Its Astrophysical Implications, Zhanwen Ma

Doctoral Dissertations

The ³⁰P(p,γ)³¹S reaction plays a crucial role in the synthesis of heavier nuclear species, from Si to Ca, in nova outbursts on ONe White Dwarfs [26, 28, 35]. However, its rate is very uncertain as a result of the lack of spectroscopic information on the levels above proton threshold in ³¹S. The currently adopted rate of this reaction, based on statistical Hauser-Feshbach calculations [36], could have an uncertainty as much as a factor of 100 higher or lower under nova conditions [26].

To reduce these uncertainties, we have measured differential cross sections for the ³²S(p,d) …

Multiple Approaches To The Separation Of Amino Acids And Biologically-Relevant Compounds, Lance Andrew Riddle

Doctoral Dissertations

The branch of analytical chemistry known as separations has continued to grow and expand ever since its beginnings a century ago. With all the technological advances occurring to make separations a more powerful technique, the main goal continues to be the desired separation of the compounds of interest in a mixture. Although a desired separation may be achieved, there can always be room for improvement with regards to the time necessary for the separation as well as better resolution of closely-related species as well as enantiomers of the same analyte.

In this work, a variety of separation methods and variations …

Synthesis And Radiolabeling Of Potassium Trifluoroborate Benzylidene Anabaseine Derivatives, Aaron Landon Smith

Doctoral Dissertations

Anabaseine has demonstrated a high, non-selective, affinity for the α7- bungarotoxin sensitive neuronal nicotinic acetylcholine receptor binding site found in small cell lung carcinoma. The benzylidene anabaseine derivatives of anabaseine have shown a selective affinity for these binding sites. These studies suggest that radiolabeled benzylidene anabaseine derivatives could act as potential imaging agents to aid in the early detection of lung cancer.

This dissertation outlines the strategy and methods employed in the synthesis of a family of potassium trifluoroborate derivatives of benzylidene anabaseine and their subsequent halogenation. Two of the trifluoroborate salts were converted to their radiolabeled analogues for potential …

Scheduling Tasks With Precedence Constraints On Heterogeneous Distributed Computing Systems, Zhiao Shi

Doctoral Dissertations

Efficient scheduling is essential to exploit the tremendous potential of high performance computing systems. Scheduling tasks with precedence constraints is a well studied problem and a number of heuristics have been proposed.

In this thesis, we first consider the problem of scheduling task graphs in heterogeneous distributed computing systems (HDCS) where the processors have different capabilities. A novel, list scheduling-based algorithm to deal with this particular situation is proposed. The algorithm takes into account the resource scarcity when assigning the task node weights. It incorporates the average communication cost between the scheduling node and its node when computing the Earliest …

Adsorption Of Small Molecules On Mgo And Graphite, Peter Nikolaivich Yaron

Doctoral Dissertations

The physical adsorption of molecules on metal oxide surfaces has direct implications in a number of industrial applications such as; catalysis, electronics, and fuel cells to name a few. Despite the large number of adsorption studies to date, only a small number of systems can be explained with the most advanced ab initio calculations currently available.

One of the simplest metal oxide systems to study is magnesium oxide due to its simple cubic rock-salt structure. Using a patented method, nearly defect-free MgO cubes can be synthesized with a narrow size distribution exposing exclusively the (100) equilibrium crystal face. The use …

Synthesis And Characterization Of Complex Polymer Architectures, Brandon Scott Farmer

Doctoral Dissertations

Anionic polymerization based upon high vacuum technique has been used to synthesize different star polymers using varying linking techniques. In particular chlorosilanes, divinylbenzene, and polyhedral oligomeric silsesquioxane (POSS) chlorosilane derivatives were used in the synthesis of star polymers. These polymers, along with polymers synthesized by others, have been characterized by a range of methods in this work.

A series of polyisoprene (PI) stars were synthesized from dimethylaminopropyllithium (DMAPLi) and subsequently hydrogenated to form poly (ethylene-co-propylene) (PEP) these were characterized by size exclusion chromatography (SEC) coupled with online two angle laser light scattering (TALLS). These polymers were synthesized in an attempt …

Variational And Partial Differential Equation Models For Color Image Denoising And Their Numerical Approximations Using Finite Element Methods, Miun Yoon

Masters Theses

Image processing has been a traditional engineering field, which has a broad range of applications in science, engineering and industry. Not long ago, statistical and ad hoc methods had been main tools for studying and analyzing image processing problems. In the past decade, a new approach based on variational and partial differential equation (PDE) methods has emerged as a more powerful approach. Compared with old approaches, variational and PDE methods have remarkable advantages in both theory and computation. It allows to directly handle and process visually important geometric features such as gradients, tangents and curvatures, and to model visually meaningful …

Photochemical Route To The Production Of Fullerene Allotropes, Olga Ovchinnikova

Masters Theses

A photochemical route to the formation of two C₆₀ molecules which are bridged by one and up to eighteen carbon atoms to form bucky-dumbbell shaped molecules, i.e., C₆₀ > C < C₆₀ to C₆₀ > C = C = C = C = C = C = C = C = C = C < C₆₀, etc. is described. Irradiation of C60 in solutions of chloroform and iodine (magenta color) with pulsed laser light from the frequency tripled (355 nm) Nd:YAG laser produced a dark crimson color. Matrix assisted laser desorption ionization (MALDI) negative ion mass spectroscopy was used to …

Neutron Diffraction Study Of Heavy Water Intercalation In Superconducting Deuterated Sodium Cobaltate Na0.35Coo21.4d2O, Cinzia Metallo

Masters Theses

When Na-deficient Na_xCoO₂ is intercalated with water¹ or heavy water², it becomes a superconductor. The maximum critical temperature of 4.5 K is found for the composition Na_xCoO₂yD₂O (x= 0.3 and y=1.4). In spite of its low transition temperature, several similarities with high temperature superconducting cuprates have raised interest in this compound. Nevertheless, up to now, a clear understanding of the role of water has not been achieved.

Since superconductivity appears only when water is inserted in the parent compound, the goal of this research work was to understand …

Applications Of Mass Spectrometry To Synthetic Copolymers, Elizabeth Angela Stewart

Masters Theses

Over the last decade, application of mass spectrometry has grown immensely especially in polymer characterization. The focus of this thesis is to assess and extend the applicability of matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and electrospray ionization mass spectrometry (ESI MS) in the analysis of synthetic copolymers.

Characterization of a non-ionic copolymer was attempted. The copolymer was styrene-co-maleic anhydride, which is in a class of copolymers that are used for commercial applications where low viscosity, high polarity and/or high reactivity are needed. MALDI-TOF MS was employed to obtain weight and number average molecular weight values (M_w and …

Multiple Resolution Nonparametric Classifiers, David Laurence Beck

Masters Theses

Bayesian discriminant functions provide optimal classification decision boundaries in the sense of minimizing the average error rate. An operational assumption is that the probability density functions for the individual classes are either known a priori or can be estimated from the data through the use of estimating techniques. The use of Parzen- windows is a popular and theoretically sound choice for such estimation. However, while the minimal average error rate can be achieved when combining Bayes Rule with Parzen-window density estimation, the latter is computationally costly to the point where it may lead to unacceptable run-time performance. We present the …

Petrogenesis Of Apollo 15 Olivine-Normative And Quartz-Normative Mare Basalts, Darren W. Schnare

Masters Theses

New data are presented for four Apollo 15 low-Ti mare basalts, two from the olivine-normative suite (15106, and 15555) and two from the quartz-normative suite (15475, and 15499). Previous studies have examined the relationships between these groups on the basis of whole-rock chemistry, many with analyses that may have been of insufficient sample-size, or of limited range of elements analyzed. To determine a relationship between these basalts, these samples have been analyzed for their mineral major-element and trace-element compositions by electron-microprobe and laser-ablation inductively-coupled-plasma mass-spectrometry, respectively.

The trace-element compositions of the main silicate phases, olivine, pyroxene, and plagioclase, are consistent …

Development Of Novel Synthetic Methods Utilizing Organometallic Reagents And Total Synthesis Of Eupomatilone 2, Chunlan Chen

Masters Theses

This dissertation summarizes the development of novel synthetic methods involving organometallic reagents and their application in the total synthesis of the natural product eupomatilone 2. These newly discovered reactions include the palladium-catalyzed cross-coupling of allyl acetates with organosiloxanes and the diastereoselective synthesis of cis- and trans-a-methylene-y-lactones utilizing Baylis-Hillman adducts as precursors. Another important aspect of the research is the application of some of the methods in total synthesis of eupomatilone 2.

The new synthetic methodologies involving organometallic reagents developed in this dissertation are important transformations in modern organic synthesis. Mild reaction conditions, tolerance of various organic functional groups, and high …

Four-Dimensional Mvct Imaging And Spatial Translation Of Helical Tomotherapy Dose Distributions Using Sinogram Modification, Samuel Scott Outten

Masters Theses

Helical tomotherapy systems have the unique attribute of using sinograms as a machine input and a machine output. These sinograms have well understood properties that may allow for operational changes that simplify and/or improve radiation treatment.

In the first part of this work, the detector array output sinogram of an MVCT imaging study is used to produce images of an object at different locations along a pattern of motion and the multi-leaf collimator (MLC) control sinogram is used to translate dose distributions in space. A temporal re-binning algorithm was written that divided the MVCT sinogram projections into positional bins that …

Origin And Tectonic Evolution Of The Southern Appalachian Neoacadin Crystalline Core: Evidence From The Geology Of The Gilreath 7.5-Minute Quadrangle, North Carolina, Crystal Gayle Wilson

Masters Theses

Detailed geologic mapping of the Gilreath 7.5-minute quadrangle recognizes the northernmost continuation of the Brindle Creek fault, a terrane boundary that separates Neoproterozic-Ordovician metasedimentary and metavolcanic rocks of the western Tugaloo terrane (western Inner Piedmont) from Silurian-Devonian metasedimentary rocks and Devonian-Mississippian anatectic granitoids of the Cat Square terrane (eastern Inner Piedmont). The Brindle Creek fault is folded in the study area and exposes the Ordovician Brooks Crossroads Granite in a reentrant. Low high-field strength element concentrations and a flatter rare earth element patterns typical of western Inner Piedmont granitoids, support a footwall setting for the Brooks Crossroads Granite.

New geochemical …

Cross Sections Fall 2006, Department Of Physics And Astronomy

Cross Sections

No abstract provided.

Potential Subsurface Structures And Hydrocarbon Reservoirs In The Southern Appalachian Basin Beneath The Cumberland Plateau And Eastern Highland Rim, Tennessee, Kentucky, And Southwestern Virginia, Jonathan Charles Evenick

Doctoral Dissertations

Oil and gas exploration in the southern Appalachian basin is typically concentrated around areas with historically proven reserves and very limited prospecting is conducted elsewhere in the region. To remove possible correlation problems and promote regional prospecting a standardized picking methodology was established in geophysical logs for the Middle Ordovician carbonate lithofacies (Nashville-Stones River Groups). This methodology was then used to correlate the units across Cumberland Plateau of Tennessee, Kentucky, and Virginia, from the Nashville-Jessamine domes to the Clinchport-Whiteoak Mountain thrust in the Valley and Ridge. The same lithofacies may extend in Ohio, Pennsylvania, and New York, suggesting a standardized …

Solute Transport And U(Vi) Reactivity In Natural Heterogeneous Sediments, Melanie A. Mays

Doctoral Dissertations

The primary goal of this research was to determine the relationship between sedimentary geology and solute transport parameters. The overall hypothesis was that the transport of reactive and nonreactive solutes can be predicted using observable sedimentary depositional characteristics. The objective was to test this hypothesis by performing a variety of quantitative transport experiments in intact layered sediment samples. In this study, I used natural materials to explore 1) how mineralogical composition influenced the fate and transport of uranium(VI), 2) the relationship between heterogeneous sedimentary layering and preference for direction of flow, and 3) the mechanisms of solute transport in a …