Physical Sciences and Mathematics Commons^™

Room Temperature Synthesis And Systematic Characterization Of Ultra-Small Ceria Nanoparticles, Chetak Patel

Electronic Theses and Dissertations

Cerium oxide (ceria, CeOâ‚‚) is a rare earth oxide that has attracted wide-spread research interest because of its unique properties such as high mechanical strength, oxygen ion conductivity, oxygen storage capacity and autocatalytic property. In recent years, researchers have discovered that ceria nanoparticles (NPs) are capable of protecting cells from free radical induced damage. Interestingly, it was found that nanometer size (~ 5 nm) ceria can scavenge free radicals quite efficiently, thus acting as an anti-oxidant. This phenomenon has been explained based on the autocatalytic property of ceria NPs. Several methods have been developed for the synthesis of ceria NPs …

A Preliminary Study Of A Non-Invasive Glucose Sensor Based On A Mercury Sensor, Erin Wood

Electronic Theses and Dissertations

Diabetes mellitus is a potentially lethal disease that affects 7.6 percent of American people. In the US, it is recognized as the 6th leading cause of death. Failure to control blood glucose levels (BGL) in patients with either type of diabetes can lead to other serious complications as well, such as loss of limb, blindness and other health problems. Controlling and monitoring the BGL in post-op and intensive care patients in the hospital is also vital to their health. Currently the most reliable method of monitoring BGL is through an invasive procedure which monitors the amount of glucose in blood …

Imaging And Spectroscopy Of Conducting Polymer-Fullerene Composite Materials, Daeri Tenery

Electronic Theses and Dissertations

Since the development and optical study of conjugated (conducting) polymers it has become apparent that chain conformation and aggregation at the molecular scale result in complex heterogeneous nanostructured bulk materials for which a detailed insight into morphological, spectroscopic as well as optoelectronic properties and mechanisms is overwhelmingly difficult to obtain. Nanoparticles composed of the conjugated polymer poly (MEH-PPV) and nanocomposite nanoparticles consisting of MEH-PPV doped with 1-(3-methoxycarbonylpropyl)-1-phenyl-C61 (PCBM) were prepared as model systems to study these materials at the length scale of one to a few domains. The MEH-PPV and PCBM doped nanoparticles were analyzed by single imaging/particle spectroscopy (SPS) …

Efficient Cone Beam Reconstruction For The Distorted Circle And Line Trajectory, Souleymane Konate

Electronic Theses and Dissertations

We propose an exact filtered backprojection algorithm for inversion of the cone beam data in the case when the trajectory is composed of a distorted circle and a line segment. The length of the scan is determined by the region of interest , and it is independent of the size of the object. With few geometric restrictions on the curve, we show that we have an exact reconstruction. Numerical experiments demonstrate good image quality.

Optimal Dual Frames For Erasures And Discrete Gabor Frames, Jerry Lopez

Electronic Theses and Dissertations

Since their discovery in the early 1950's, frames have emerged as an important tool in areas such as signal processing, image processing, data compression and sampling theory, just to name a few. Our purpose of this dissertation is to investigate dual frames and the ability to find dual frames which are optimal when coping with the problem of erasures in data transmission. In addition, we study a special class of frames which exhibit algebraic structure, discrete Gabor frames. Much work has been done in the study of discrete Gabor frames in Rn, but very little is known about the l2(Z) …

The Sheffer B-Type 1 Orthogonal Polynomial Sequences, Daniel Galiffa

Electronic Theses and Dissertations

In 1939, I.M. Sheffer proved that every polynomial sequence belongs to one and only one type. Sheffer extensively developed properties of the B-Type 0 polynomial sequences and determined which sets are also orthogonal. He subsequently generalized his classification method to the case of arbitrary B-Type k by constructing the generalized generating function A(t)exp[xH1(t) + · · · + xk+1Hk(t)] = ∑∞n=0 Pn(x)tn, with Hi(t) = hi,iti + hi,i+1t i+1 + · · · , h1,1 ≠ 0. Although extensive research has been done on characterizing polynomial sequences, no analysis has yet been completed on sets of type one or higher …

Almost Regular Graphs And Edge Face Colorings Of Plane Graphs, Lisa Macon

Electronic Theses and Dissertations

Regular graphs are graphs in which all vertices have the same degree. Many properties of these graphs are known. Such graphs play an important role in modeling network configurations where equipment limitations impose a restriction on the maximum number of links emanating from a node. These limitations do not enforce strict regularity, and it becomes interesting to investigate nonregular graphs that are in some sense close to regular. This dissertation explores a particular class of almost regular graphs in detail and defines generalizations on this class. A linear-time algorithm for the creation of arbitrarily large graphs of the discussed class …

Weighted Lp-Stability For Localized Infinite Matrices, Qiling Shi

Electronic Theses and Dissertations

This dissertation originates from a classical result that the lp-stability of the convolution operator associated with a summable sequence are equivalent to each other for different p . This dissertation is motivated by the recent result by C. E. Shin and Q. Sun (Journal ofFunctional Analysis, 256(2009), 2417-2439), where the lp-stability of infinite matrices in the Gohberg-Baskakov-Sjostrand class are proved to be equivalent to each other for different p. In the dissertation, for an infinite matrix having certain off-diagonal decay, its weighted lp-stability for different p are proved to be equivalent to each other and hence a result by Shin …

Analytical And Numerical Solutions Of Differentialequations Arising In Fluid Flow And Heat Transfer Problems, Erik Sweet

Electronic Theses and Dissertations

The solutions of nonlinear ordinary or partial differential equations are important in the study of fluid flow and heat transfer. In this thesis we apply the Homotopy Analysis Method (HAM) and obtain solutions for several fluid flow and heat transfer problems. In chapter 1, a brief introduction to the history of homotopies and embeddings, along with some examples, are given. The application of homotopies and an introduction to the solutions procedure of differential equations (used in the thesis) are provided. In the chapters that follow, we apply HAM to a variety of problems to highlight its use and versatility in …

Development Of Theoretical And Computational Methods For Three-Body Processes, Juan Blandon Zapata

Electronic Theses and Dissertations

This thesis discusses the development and application of theoretical and computational methods to study three-body processes. The main focus is on the calculation of three-body resonances and bound states. This broadly includes the study of Efimov states and resonances, three-body shape resonances, three-body Feshbach resonances, three-body pre-dissociated states in systems with a conical intersection, and the calculation of three-body recombination rate coefficients. The method was applied to a number of systems. A chapter of the thesis is dedicated to the related study of deriving correlation diagrams for three-body states before and after a three-body collision. More specifically, the thesis discusses …

Search, Characterization, And Properties Of Brown Dwarfs, Ramarao Tata

Electronic Theses and Dissertations

A trend in polarization as predicted by theoretical models was validated, and atmospheric dust grain sizes and projected rotational velocities for these objects were estimated. Comprehensive studies of UDs are proving to be crucial not only in our understanding of UDs but also for star and planet formation as brown dwarfs represent their lower and upper mass boundaries, respectively. Brown dwarfs (BD) were mere theoretical astrophysical objects for more than three decades (Kumar (1962)) till their first observational detection in 1995 (Rebolo et al. (1995), Nakajima et al. (1995)). These objects are intermediate in mass between stars and planets. Since …

Decoherence In Semiconductor Solid-State Quantum Computers, Diego Valente

Electronic Theses and Dissertations

In this dissertation we discuss decoherence in charge qubits formed by multiple lateral quantum dots in the framework of the spin-boson model and the Born-Markov approximation. We consider the intrinsic decoherence caused by the coupling to bulk phonon modes and electromagnetic environmental fluctuations. In the case of decoherence caused by phonon coupling, two distinct quantum dot configurations are studied and proposed as setups that mitigate its nocive effects : (i) Three quantum dots in a ring geometry with one excess electron in total and (ii) arrays of quantum dots where the computational basis states form multipole charge configurations. For the …

In-Situ Gas Phase Catalytic Properties Of Metal Nanoparticles, Luis Ono

Electronic Theses and Dissertations

Recent advances in surface science technology have opened new opportunities for atomic scale studies in the field of nanoparticle (NP) catalysis. The 2007 Nobel Prize of Chemistry awarded to Prof. G. Ertl, a pioneer in introducing surface science techniques to the field of heterogeneous catalysis, shows the importance of the field and revealed some of the fundamental processes of how chemical reactions take place at extended surfaces. However, after several decades of intense research, fundamental understanding on the factors that dominate the activity, selectivity, and stability (life-time) of nanoscale catalysts are still not well understood. This dissertation aims to explore …

Analysis And Design Of Wide-Angle Foveated Optical Systems, George Curatu

Electronic Theses and Dissertations

The development of compact imaging systems capable of transmitting high-resolution images in real-time while covering a wide field-of-view (FOV) is critical in a variety of military and civilian applications: surveillance, threat detection, target acquisition, tracking, remote operation of unmanned vehicles, etc. Recently, optical foveated imaging using liquid crystal (LC) spatial light modulators (SLM) has received considerable attention as a potential approach to reducing size and complexity in fast wide-angle lenses. The fundamental concept behind optical foveated imaging is reducing the number of elements in a fast wide-angle lens by placing a phase SLM at the pupil stop to dynamically compensate …

Optical Nonlinear Interactions In Dielectric Nano-Suspensions, Ramy El-Ganainy

Electronic Theses and Dissertations

This work is divided into two main parts. In the first part (chapters 2-7) we consider the nonlinear response of nano-particle colloidal systems. Starting from the Nernst-Planck and Smoluchowski equations, we demonstrate that in these arrangements the underlying nonlinearities as well as the nonlinear Rayleigh losses depend exponentially on optical intensity. Two different nonlinear regimes are identified depending on the refractive index contrast of the nanoparticles involved and the interesting prospect of self-induced transparency is demonstrated. Soliton stability is systematically analyzed for both 1D and 2D configurations and their propagation dynamics in the presence of Rayleigh losses is examined. We …

Gabor Domain Optical Coherence Microscopy, Supraja Murali

Electronic Theses and Dissertations

Time domain Optical Coherence Tomography (TD-OCT), first reported in 1991, makes use of the low temporal coherence properties of a NIR broadband laser to create depth sectioning of up to 2mm under the surface using optical interferometry and point to point scanning. Prior and ongoing work in OCT in the research community has concentrated on improving axial resolution through the development of broadband sources and speed of image acquisition through new techniques such as Spectral domain OCT (SD-OCT). In SD-OCT, an entire depth scan is acquired at once with a low numerical aperture (NA) objective lens focused at a fixed …

Power Scaling Of Large Mode Area Thulium Fiber Lasers In Various Spectral And Temporal Regimes, Timothy Mccomb

Electronic Theses and Dissertations

High power thulium fiber lasers are interesting for a myriad of applications due to their potential for high average output power, excellent beam quality, compactness, portability, high operating efficiency and broad, eye-safe spectral range from 1.8-2.1 microns. Currently, the majority of thulium laser research effort is being invested into scaling average output powers; however, such output powers are being scaled with no degree of control on laser system output spectrum or temporal behavior. Thulium fiber laser technology is not useful for many of its most important applications without implementation of techniques enabling tunable, narrow spectral widths with appropriate pulse durations …

Silicon Carbide And Agile Optics Based Sensors For Power Plant Gas Turbines, Laser Beam Analysis And Biomedicine, Mumtaz Sheikh

Electronic Theses and Dissertations

Proposed are novel sensors for extreme environment power plants, laser beam analysis and biomedicine. A hybrid wireless-wired extreme environment temperature sensor using a thick single-crystal Silicon Carbide (SiC) chip embedded inside a sintered SiC probe design is investigated and experimentally demonstrated. The sensor probe employs the SiC chip as a Fabry-Perot (FP) interferometer to measure the change in refractive index and thickness of SiC with temperature. A novel temperature sensing method that combines wavelength-tuned signal processing for coarse measurements and classical FP etalon peak shift for fine measurements is proposed and demonstrated. This method gives direct unambiguous temperature measurements with …

Synthesis Of Biocompatible Antioixidant Polymer Coated Cerium Oxide Nanoparticles, Its Oxidase Like Behavior And Cellular Uptake, Atul Asati

Electronic Theses and Dissertations

Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant …

Development Of Novel Dart Tofms Analytical Techniques For The Identification Of Organic Contamination On Spaceflight-Related Substrates And Aqueous Media, Kathleen Loftin

Electronic Theses and Dissertations

Organic contamination on spaceflight hardware is an ongoing concern for spaceflight safety. In addition, for the goal of analyzing for possible evidence of extra-terrestrial life, it is necessary to consider the presence of terrestrial contamination. This paper will introduce and evaluate a new method using a direct analysis real time (DART) ionization source paired with a high resolution time of flight mass spectrometer (TOFMS) for the determination of organic contamination involved in spaceflight hardware and ground support materials. This novel analytical technique has significant advantages over current methodologies. Materials analyzed in this study were historically considered as probable contaminants in …

Nanofiltration Membrane Pilot Studies For Disinfection By-Product Control, Eric J. Lynne

Electronic Theses and Dissertations

Watertown, South Dakota currently uses conventional softening to treat ground water to remove hardness, iron and manganese, and natural organic matter. The distribution system has experienced elevated concentrations of disinfection by-products, which will require additional treatment to comply with future limits set by the Stage 2 Disinfectant/Disinfection By-Products Rule. A nanofiltration membrane system has been proposed to remove additional natural organic matter from the softened water. Removing the natural organic material disinfection by-product precursors should reduce the concentration of disinfection by-products. The use of nanofiltration membranes has been previously documented to reject total organic carbon, while allowing desirable levels of …

Design And Fabrication Of Space Variant Micro Optical Elements, Pradeep Srinivasan

Electronic Theses and Dissertations

A wide range of applications currently utilize conventional optical elements to individually transform the phase, polarization, and spectral transmission/reflection of the incident radiation to realize the desired system level function. The material properties and the feasibility of fabrication primarily impact the device and system functionality that can be realized. With the advancement in micro/nano patterning, growth, deposition and etching technology, devices with novel and multiplexed optical functionalities have become feasible. As a result, it has become possible to engineer the device response in the near and far field by controlling the phase, polarization or spectral response at the micro scale. …

Search And Delivery Techniques In Peer-To-Peer Networks, Tai Do

Electronic Theses and Dissertations

The presence of millions of interconnected personal computing devices has given rise to a new class of decentralized networking applications, which are loosely labeled as peer-to-peer (P2P) applications. These P2P applications leverage resources such as processing cycles, storage, content, and network bandwidth available to the user devices, which are also known as peers. A number of current systems - SETI@home, Napster, BitTorrent, and Pastry - are examples of these emerging P2P systems. To fully realize the potential of the peer-to-peer technology, there is a need to define and provide a set of core competencies, serving as the basic services upon …

Attacks On Difficult Instances Of Graph Isomorphism: Sequential And Parallel Algorithms, Greg Tener

Electronic Theses and Dissertations

The graph isomorphism problem has received a great deal of attention on both theoretical and practical fronts. However, a polynomial algorithm for the problem has yet to be found. Even so, the best of the existing algorithms perform well in practice; so well that it is challenging to find hard instances for them. The most efficient algorithms, for determining if a pair of graphs are isomorphic, are based on the individualization-refinement paradigm, pioneered by Brendan McKay in 1981 with his algorithm nauty. Nauty and various improved descendants of nauty, such as bliss and saucy, solve the graph isomorphism problem by …

Spin Quantum Dynamics In Molecular Magnets, John Henderson

Electronic Theses and Dissertations

Molecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are single-molecule magnets (SMMs) and antiferromagnetic (AFM) molecular wheels in which the spin state of the molecule is known to behave quantum mechanically at low temperatures. In previous experiments the dynamics …

On The Application Of Locality To Network Intrusion Detection: Working-Set Analysis Of Real And Synthetic Network Server Traffic, Robert Lee

Electronic Theses and Dissertations

Keeping computer networks safe from attack requires ever-increasing vigilance. Our work on applying locality to network intrusion detection is presented in this dissertation. Network servers that allow connections from both the internal network and the Internet are vulnerable to attack from all sides. Analysis of the behavior of incoming connections for properties of locality can be used to create a normal profile for such network servers. Intrusions can then be detected due to their abnormal behavior. Data was collected from a typical network server both under normal conditions and under specific attacks. Experiments show that connections to the server do …

Analysis And Treatment Of Emerging Polar Contaminants, Daniel E. Connors

Electronic Theses and Dissertations

Two major classes of polar compounds have recently become a major focus as sources of contamination of water systems. Pharmaceuticals and personal care products (PPCPs) enter water through wastewater streams, and many of these compounds survive current wastewater treatment processes. High production volume chemicals (HPVCs), defined as chemicals produced in excess of one million pounds per year have numerous entries into surface and drinking waters due to their ubiquity. The commonality between many of these compounds is their polarity, which makes them water-soluble.

While both PPCPs and HPVCs have been entering into the environment for decades, advances in analyte detection …

Gold Nanoparticles: Synthesis, Property Study And Applcications For Biomolecular Detection And Photothermal Therapy, Xiong Liu

Electronic Theses and Dissertations

This dissertation presents a systematic study on gold nanoparticles: from their chemical synthesis, modification of surface functionalities, optical properties studies with emphasis on the absorption and scattering properties, to applications of gold nanoparticles in biomolecular detection, imaging and photothermal therapy. In chapter 2, we studied the kinetics of gold nanoparticle growth under Brust-Shiffrin reaction conditions. In chapter 3, we further examined the reaction mechanism and growth kinetics of gold nanoparticles using oleylamine as both a reducing reagent and particle growth passivation ligand. From these two projects, important understanding was revealed on gold nanoparticle formation and growth mechanism. Chapter 4 describes …

Standing Waves Of Spatially Discrete Fitzhugh-Nagumo Equations, Joseph Segal

Electronic Theses and Dissertations

We study a system of spatially discrete FitzHugh-Nagumo equations, which are nonlinear differential-difference equations on an infinite one-dimensional lattice. These equations are used as a model of impulse propagation in nerve cells. We employ McKean's caricature of the cubic as our nonlinearity, which allows us to reduce the nonlinear problem into a linear inhomogeneous problem. We find exact solutions for standing waves, which are steady states of the system. We derive formulas for all 1-pulse solutions. We determine the range of parameter values that allow for the existence of standing waves. We use numerical methods to demonstrate the stability of …

Tunable Terahertz Detectors Based On Plasmon Exciation In Two Dimensional Electron Gasses In Ingaas/Inp And Algan/Gan Hemt, Himanshu Saxena

Electronic Theses and Dissertations

The observation of voltage-tunable plasmon resonances in the terahertz range in two dimensional electron gas (2-deg) of a high electron mobility transistor (HEMT) fabricated from the InGaAs/InP and AlGaN/GaN materials systems is reported. The devices were fabricated from a commercial HEMT wafer by depositing source and drain contacts using standard photolithography process and a semi-transparent gate contact that consisted of a 0.5 [micro]m period transmission grating formed by electron-beam lithography. Narrow-band resonant absorption of THz radiation was observed in transmission in the frequency range 10-100 cm-1. The resonance frequency depends on the gate voltage-tuned sheet-charge density of the 2deg. The …