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Microfabrication of an Implantable silicone Microelectrode array for an epiretinal prosthesis

Description: Millions of people suffering from diseases such as retinitis pigmentosa and macular degeneration are legally blind due to the loss of photoreceptor function. Fortunately a large percentage of the neural cells connected to the photoreceptors remain viable, and electrical stimulation of these cells has been shown to result in visual perception. These findings have generated worldwide efforts to develop a retinal prosthesis device, with the hope of restoring vision. Advances in microfabrication, i… more
Date: June 10, 2003
Creator: Maghribi, M
Partner: UNT Libraries Government Documents Department
open access

Microphysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations

Description: A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10-13 mm, whereas liquid water is more absorbing than ice from 16-25 um. However, due to strong absorption in… more
Date: June 1, 2003
Creator: Turner, David D.
Partner: UNT Libraries Government Documents Department
open access

Fabrication of Yttria stabilized zirconia thin films on poroussubstrates for fuel cell applications

Description: A process for the deposition of yttria stabilized zirconia (YSZ) films, on porous substrates, has been developed. These films have possible applications as electrolyte membranes in fuel cells. The films were deposited from colloidal suspensions through the vacuum infiltration technique. Films were deposited on both fully sintered and partially sintered substrates. A critical cracking thickness for the films was identified and strategies are presented to overcome this barrier. Green film density… more
Date: June 16, 2003
Creator: Leming, Andres
Partner: UNT Libraries Government Documents Department
open access

Adsorbate structures and catalytic reactions studied in the torrpressure range by scanning tunneling microscopy

Description: High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO {yields} 1/2 N{sub 2} + CO{sub 2}] on Rh(111) and ethylene hydrogenation [C{sub 2}H{sub 4} + H{sub 2} {yields} C{sub 2}H{sub 6}] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic… more
Date: May 23, 2003
Creator: Hwang, Kevin Shao-Lin
Partner: UNT Libraries Government Documents Department
open access

Delta Electroproduction in 12-C

Description: The Delta-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the delta mass indicating that this potential is dependent on the momentum of the delta. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the delta resonance in 12C, performed using the high energy electron beam a… more
Date: January 31, 2003
Creator: McLauchlan, Steven
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Lambda 0(b) -> Lambda +(c) pi- branching ratio

Description: The authors present a measurement of the {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +} {pi}{sup -} branching ratio in p{bar p} collisions at {radical}s = 1.96 TeV using 65 pb{sup -1} data collected by the Collider Detector at Fermilab (CDF). The measurement starts from reconstructing two decay modes: {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{sup +}{pi}{sup -}, where {Lambda}{sub c}{sup +} {yields} p K{sup -} {pi}{sup +}; and {bar B}{sup 0} {yields} D{sup +}{pi}{sup -}, where D{su… more
Date: January 1, 2003
Creator: Le, Yi
Partner: UNT Libraries Government Documents Department
open access

A measurement of forward-backward charge asymmetry of electron-positron pairs in proton-antiproton collision at 1.8 TeV

Description: The authors present a measurement of the mass dependence of the forward-backward charge asymmetry for e{sup +}e{sup -} pairs resulting from {gamma}*/Z decays with mass M{sub ee} > 40 GeV/c{sup 2}. The Run II data sample consists of 72 pb{sup -1} of data, which was collected by the CDF detector in {bar p}p collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. The measurement is compared with predictions from the Standard Model.
Date: December 1, 2003
Creator: Veramendi, Gregory Francisco
Partner: UNT Libraries Government Documents Department
open access

MINOS Calibration and NA49 Hadronic Production Studies

Description: An overview of the current status of the Main Injector Neutrino Oscillation Search (MINOS) is presented. MINOS is a long-baseline experiment with two detectors situated in North America. The near detector is based at the emission point of the NuMI beam at Fermilab, Chicago, the far detector is 735 km downstream in a disused iron mine in Soudan, Minnesota. A third detector, the calibration detector, is used to cross-calibrate these detectors by sampling different particle beams at CERN. A detail… more
Date: August 1, 2003
Creator: Morse, Robert James
Partner: UNT Libraries Government Documents Department
open access

Protein Structure Recognition: From Eigenvector Analysis to Structural Threading Method

Description: In this work, they try to understand the protein folding problem using pair-wise hydrophobic interaction as the dominant interaction for the protein folding process. They found a strong correlation between amino acid sequences and the corresponding native structure of the protein. Some applications of this correlation were discussed in this dissertation include the domain partition and a new structural threading method as well as the performance of this method in the CASP5 competition. In the f… more
Date: December 12, 2003
Creator: Cao, Haibo
Partner: UNT Libraries Government Documents Department
open access

Anisotropy in CdSe quantum rods

Description: The size-dependent optical and electronic properties of semiconductor nanocrystals have drawn much attention in the past decade, and have been very well understood for spherical ones. The advent of the synthetic methods to make rod-like CdSe nanocrystals with wurtzite structure has offered us a new opportunity to study their properties as functions of their shape. This dissertation includes three main parts: synthesis of CdSe nanorods with tightly controlled widths and lengths, their optical an… more
Date: September 1, 2003
Creator: Li, Liang-shi
Partner: UNT Libraries Government Documents Department
open access

Nitrogen doped zinc oxide thin film

Description: To summarize, polycrystalline ZnO thin films were grown by reactive sputtering. Nitrogen was introduced into the films by reactive sputtering in an NO{sub 2} plasma or by N{sup +} implantation. All ZnO films grown show n-type conductivity. In unintentionally doped ZnO films, the n-type conductivities are attributed to Zn{sub i}, a native shallow donor. In NO{sub 2}-grown ZnO films, the n-type conductivity is attributed to (N{sub 2}){sub O}, a shallow double donor. In NO{sub 2}-grown ZnO films, … more
Date: December 15, 2003
Creator: Li, Sonny X.
Partner: UNT Libraries Government Documents Department
open access

Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

Description: Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and p… more
Date: December 12, 2003
Creator: Kim, Chang-Hwan
Partner: UNT Libraries Government Documents Department
open access

Three-body Forces in Photoreactions on 3He

Description: We have measured the three-body photobreakup of {sup 3}He with the tagged photon beam and the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility, in the photon energy range between 0.35 GeV and 1.55 GeV. This measurement constitutes a wide-ranging survey of two- and three-body processes in the gamma{sup 3}He {yields} ppn reaction channel, thanks to the high statistics and large kinematic coverage obtained with the CLAS. Total and partially integr… more
Date: February 1, 2003
Creator: Niccolai, Silvia
Partner: UNT Libraries Government Documents Department
open access

Organogermanium Chemistry: Germacyclobutanes and digermane Additions to Acetylenes

Description: This dissertation comprises two main research projects. The first project, presented in Chapter 1, involves the synthesis and thermochemistry of germacyclobutanes (germetanes). Four new germetanes (spirodigermetane, diallylgermetane, dichlorogermetane, and germacyclobutane) have been synthesized using a modified di-Grignard synthesis. Diallylgermetane is shown to be a useful starting material for obtaining other germetanes, particularly the parent germetane, germacyclobutane. The gas-phase ther… more
Date: December 12, 2003
Creator: Chubb, Andrew Michael
Partner: UNT Libraries Government Documents Department
open access

Thermal Properties of Starch From New Corn Lines as Impacted by Environment and During Line Development

Description: The objectives of this research were to further characterize exotic by adapted corn inbreds by studying the impact of environment on their starch thermal properties, and investigating the development of starch thermal properties during kernel maturation by using differential scanning calorimetry (DSC). A method to expedite identification of unusual starch thermal traits was investigated by examining five corn kernels at a time, instead of one kernel, which the previous screening methods used. C… more
Date: December 12, 2003
Creator: Lenihan, Elizabeth M.
Partner: UNT Libraries Government Documents Department
open access

Organic Light-Emitting Devices (OLEDS) and Their Optically Detected Magnetic Resonance (ODMR)

Description: Organic Light-Emitting Devices (OLEDs), both small molecular and polymeric have been studied extensively since the first efficient small molecule OLED was reported by Tang and VanSlyke in 1987. Burroughes' report on conjugated polymer-based OLEDs led to another track in OLED development. These developments have resulted in full color, highly efficient (up to {approx} 20% external efficiency 60 lm/W power efficiency for green emitters), and highly bright (> 140,000 Cd/m{sup 2} DC, {approx}2,0… more
Date: December 12, 2003
Creator: Li, Gang
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

Description: In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals… more
Date: December 12, 2003
Creator: Foteinopoulou, Stavroula
Partner: UNT Libraries Government Documents Department
open access

Quantification of Soil Physical Properties by Using X-Ray Computerized Tomography (CT) and Standard Laboratory (STD) Methods

Description: The implementation of x-ray computerized tomography (CT) on agricultural soils has been used in this research to quantify soil physical properties to be compared with standard laboratory (STD) methods. The overall research objective was to more accurately quantify soil physical properties for long-term management systems. Two field studies were conducted at Iowa State University's Northeast Research and Demonstration Farm near Nashua, IA using two different soil management strategies. The first… more
Date: December 12, 2003
Creator: Sanchez, Maria Ambert
Partner: UNT Libraries Government Documents Department
open access

Homogeneous Precipitation of Nickel Hydroxide Powders

Description: Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with urea precipitation method. Model predictions on Ni{sup 2+} precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility pr… more
Date: December 12, 2003
Creator: Mavis, Bora
Partner: UNT Libraries Government Documents Department
open access

Development of Modeling and Simulation for Magnetic Particle Inspection Using Finite Elements

Description: Magnetic particle inspection (MPI) is a widely used nondestructive inspection method for aerospace applications essentially limited to experiment-based approaches. The analysis of MPI characteristics that affect sensitivity and reliability contributes not only reductions in inspection design cost and time but also improvement of analysis of experimental data. Magnetic particles are easily attracted toward a high magnetic field gradient. Selection of a magnetic field source, which produces a mag… more
Date: May 31, 2003
Creator: Lee, Jun-Youl
Partner: UNT Libraries Government Documents Department
open access

Mechanistic Study of Oxygen Atom Transfer Catalyzed by Rhenium Compounds

Description: Two ionic and one neutral methyl(oxo)rhenium(V) compounds were synthesized and structurally characterized. They were compared in reactivity towards the ligands triphenylphosphane, pyridines, pyridine N-oxides. Assistance from Broensted bases was found on ligand displacement of ionic rhenium compounds as well as nucleophile assistance on oxidation of all compounds. From the kinetic data, crystal structures, and an analysis of the intermediates, a structural formula of PicH{sup +}3{sup -} and mec… more
Date: August 5, 2003
Creator: Shan, Xiaopeng
Partner: UNT Libraries Government Documents Department
open access

Compact D-D/D-T neutron generators and their applications

Description: Neutron generators based on the {sup 2}H(d,n){sup 3}He and {sup 3}H(d,n){sup 4}He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large su… more
Date: May 1, 2003
Creator: Lou, Tak Pui
Partner: UNT Libraries Government Documents Department
open access

Ultrafast infrared studies of complex ligand rearrangements in solution

Description: The complete description of a chemical reaction in solution depends upon an understanding of the reactive molecule as well as its interactions with the surrounding solvent molecules. Using ultrafast infrared spectroscopy it is possible to observe both the solute-solvent interactions and the rearrangement steps which determine the overall course of a chemical reaction. The topics addressed in these studies focus on reaction mechanisms which require the rearrangement of complex ligands and the sp… more
Date: Spring 2003
Creator: Payne, Christine K.
Partner: UNT Libraries Government Documents Department
open access

Development of high Sensitivity Materials for Applications in Magneto-Mechanical Torque Sensor

Description: The Matteucci effect, which mainly manifests itself as the change of magnetization of a material with torsional stress, is currently of great technological interest because of the search for magnetic torque sensors. Magnetic torque sensors are important to future improvements of automobiles and industrial robots. It is well known that the magnetic state of a material depends on both the external magnetic field and external stress which causes strain and change in magnetization of the material. … more
Date: August 5, 2003
Creator: Shen, Yuping
Partner: UNT Libraries Government Documents Department
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