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U.S. Battleship Operations in World War I, 1917-1918 (open access)

U.S. Battleship Operations in World War I, 1917-1918

This dissertation is an examination of the operations of U.S. battleships in World War I. The study examines tactical cooperation between units of the U.S. Atlantic Fleet and the British Grand Fleet and relations between the two navies; the efficiency of U.S. battleships in terms of both personnel and material; and the strategic ideas of U.S. naval leaders governing the use of capital ships. The manuscript is based primarily on records of the Department of the Navy in the National Archives and Admiralty records at the Public Record Office. Also important are the private papers of principal naval leaders, located at the Library of Congress and the National Maritime Museum in Greenwich, U.K. The published memoirs of several of the participants are also utilized. The first chapter examines Anglo-American naval relations and traces diplomatic events leading to the U.S. Navy Department's decision to dispatch dreadnought battleships to European waters. The following two chapters discuss the amalgamation of Battleship Division Nine into the British Grand Fleet. Chapter IV examines the gunnery efficiency of U.S. battleships serving with the Grand Fleet. Chapter V reviews Anglo-American planning for a possible German battle cruiser raid against the Atlantic convoys. Chapter VI deals with the …
Date: October 1995
Creator: Jones, Jerry W., 1964-
System: The UNT Digital Library
Disclosure and its Perceived Impact as Mediators of the Long-Term Consequences of Child Sexual Abuse (open access)

Disclosure and its Perceived Impact as Mediators of the Long-Term Consequences of Child Sexual Abuse

The primary purpose of the present study was to investigate factors associated with childhood sexual abuse which mediate long-term effects. Of particular interest were the mediators of disclosure and its perceived impact, as well as variables related to the severity of the abuse. Also of interest were impact areas related to a history of molestation which have received little attention in the literature. Five hundred and seventy-five female undergraduates completed an extensive questionnaire with measures of family background, childhood and adult sexual experiences, health status, and psychological variables. Of these subjects, 286 reported at least one incident of child sexual abuse. It was hypothesized that those females with histories of sexual abuse who received a positive response to their disclosure of abuse would demonstrate more adaptive adult functioning as compared to those victims receiving a negative response, or those who never disclosed. Significant differences were not detected among the three groups on the outcome measures. A number of reasons were explored for why these differences may not have been detected in the present investigation. Although differences were not detected for disclosure status, significant differences were detected between females reporting a history of child sexual abuse and those reporting no abuse …
Date: October 1992
Creator: Phelan-McAuliffe, Debra
System: The UNT Digital Library
Pre-Raphaelites: The First Decadents (open access)

Pre-Raphaelites: The First Decadents

The ephemeral life of the Pre-Raphaelite Brotherhood belies the importance of an organization that grows from and transcends its originally limited aesthetic principles and circumscribed credo. The founding of the Pre-Raphaelite Brotherhood in 1848 really marks the beginning of a movement that metamorphizes into Aestheticism/Decadence. It is the purpose of this dissertation to demonstrate that, from its inception, Pre-Raphaelitism is the first English manifestation of Aestheticism/Decadence. Although the connection between Pre- Raphaelitism and the Aesthete/Decadent movement is proposed or mentioned by several writers, none has written a coherent justification for the viewing of Pre-Raphaelitism as the starting point for English Decadence This dissertation attempts to establish the primacy of Pre-Raphaelitism in the development of Aestheticism/Decadence.
Date: October 1980
Creator: Benson, Paul F.
System: The UNT Digital Library
Thermal depinning of a single superconducting vortex (open access)

Thermal depinning of a single superconducting vortex

Thermal depinning has been studied for a single vortex trapped in a superconducting thin film in order to determine the value of the superconducting order parameter and the superfluid density when the vortex depins and starts to move around the film. For the Pb film in Pb/Al/Al{sub 2}O{sub 3}/PbBi junction having a gold line, the vortex depins from the artificial pinning site (Au line) and reproducibly moves through the same sequence of other pinning sites before it leaves the junction area of the Pb film. Values of the normalized order parameter {triangle}/{triangle}{sub o} vary from {triangle}/{triangle}{sub o}=0.20 at the first motion of the vortex to {triangle}/{triangle}{sub o}=0.16 where the vortex finally leaves the junction. Equivalently, the value of the normalized superfluid density changes from 4% to 2.5% for this sample in this same temperature interval. For the Nb film in Nb/Al/Al{sub 2}O{sub 3}/Nb junction, thermal depinning occurs when the value of {triangle}/{triangle}{sub o} is approximately 0.22 and the value of {rho}{sub s}/{rho}{sub so} is approximately 5%. These values are about 20% larger than those of a Pb sample having a gold line, but the values are really very close. For the Nb sample, grain boundaries are important pinning sites whereas, …
Date: October 1, 1995
Creator: Sok, J.
System: The UNT Digital Library
New techniques for the scientific visualization of three-dimensional multi-variate and vector fields (open access)

New techniques for the scientific visualization of three-dimensional multi-variate and vector fields

Volume rendering allows us to represent a density cloud with ideal properties (single scattering, no self-shadowing, etc.). Scientific visualization utilizes this technique by mapping an abstract variable or property in a computer simulation to a synthetic density cloud. This thesis extends volume rendering from its limitation of isotropic density clouds to anisotropic and/or noisy density clouds. Design aspects of these techniques are discussed that aid in the comprehension of scientific information. Anisotropic volume rendering is used to represent vector based quantities in scientific visualization. Velocity and vorticity in a fluid flow, electric and magnetic waves in an electromagnetic simulation, and blood flow within the body are examples of vector based information within a computer simulation or gathered from instrumentation. Understand these fields can be crucial to understanding the overall physics or physiology. Three techniques for representing three-dimensional vector fields are presented: Line Bundles, Textured Splats and Hair Splats. These techniques are aimed at providing a high-level (qualitative) overview of the flows, offering the user a substantial amount of information with a single image or animation. Non-homogenous volume rendering is used to represent multiple variables. Computer simulations can typically have over thirty variables, which describe properties whose understanding are useful to …
Date: October 1, 1995
Creator: Crawfis, R.A.
System: The UNT Digital Library
Chemical and nuclear properties of Rutherfordium (Element 104) (open access)

Chemical and nuclear properties of Rutherfordium (Element 104)

The chemical-properties of rutherfordium (Rf) and its group 4 homologs were studied by sorption on glass support surfaces coated with cobalt(II)ferrocyanide and by solvent extraction with tributylphosphate (TBP) and triisooctylamine (TIOA). The surface studies showed that the hydrolysis trend in the group 4 elements and the pseudogroup 4 element, lb, decreases in the order Rf>Zr{approx}Hf>Th. This trend was attributed to relativistic effects which predicted that Rf would be more prone to having a coordination number of 6 than 8 in most aqueous solutions due to a destabilization of the 6d{sub 5/2} shell and a stabilization of the 7p{sub l/2} shell. This hydrolysis trend was confirmed in the TBP/HBr solvent extraction studies which showed that the extraction trend decreased in the order Zr>Hf>Rf?Ti for HBr, showing that Rf and Ti did not extract as well because they hydrolyzed more easily than Zr and Hf. The TIOA/HF solvent extraction studies showed that the extraction trend for the group 4 elements decreased in the order Ti>Zr{approx}Hf>Rf, in inverse order from the trend of ionic radii Rf>Zr{approx}Hf>Ti. An attempt was made to produce {sup 263}Rf (a) via the {sup 248}Cm({sup 22}Ne, {alpha}3n) reaction employing thenoyltrifluoroacetone (TTA) solvent extraction chemistry and (b) via the {sup …
Date: October 30, 1995
Creator: Kacher, C. D.
System: The UNT Digital Library
Inductively coupled plasma spectrometry: Noise characteristics of aerosols, application of generalized standard additions method, and Mach disk as an emission source (open access)

Inductively coupled plasma spectrometry: Noise characteristics of aerosols, application of generalized standard additions method, and Mach disk as an emission source

This dissertation is focused on three problem areas in the performance of inductively coupled plasma (ICP) source. The noise characteristics of aerosols produced by ICP nebulizers are investigated. A laser beam is scattered by aerosol and detected by a photomultiplier tube and the noise amplitude spectrum of the scattered radiation is measured by a spectrum analyzer. Discrete frequency noise in the aerosol generated by a Meinhard nebulizer or a direct injection nebulizer is primarily caused by pulsation in the liquid flow from the pump. A Scott-type spray chamber suppresses white noise, while a conical, straight-pass spray chamber enhances white noise, relative to the noise seen from the primary aerosol. Simultaneous correction for both spectral interferences and matrix effects in ICP atomic emission spectrometry (AES) can be accomplished by using the generalized standard additions method (GSAM). Results obtained with the application of the GSAM to the Perkin-Elmer Optima 3000 ICP atomic emission spectrometer are presented. The echelle-based polychromator with segmented-array charge-coupled device detectors enables the direct, visual examination of the overlapping lines Cd (1) 228.802 nm and As (1) 228.812 nm. The slit translation capability allows a large number of data points to be sampled, therefore, the advantage of noise averaging …
Date: October 6, 1995
Creator: Shen, Luan
System: The UNT Digital Library
Search for {Sigma}{sub c} {yields} {Lambda}{sub c}{pi} using {Lambda}{sub c} {yields} {Sigma}{sub s}{pi}{pi} in 250 GeV {pi}{sup {minus}}-nucleon interactions (open access)

Search for {Sigma}{sub c} {yields} {Lambda}{sub c}{pi} using {Lambda}{sub c} {yields} {Sigma}{sub s}{pi}{pi} in 250 GeV {pi}{sup {minus}}-nucleon interactions

Combined cross section times branching fraction limits are given for {Sigma}{sub c}{sup +}{sup +} {r_arrow} {Lambda}{sub c}{sup +}{pi}{sup +} and {Sigma}{sub c}{sup 0} {r_arrow} {Lambda}{sub c}{sup +}{pi}{sup {minus}} where {Lambda}{sub c}{sup +} {r_arrow} {Sigma}{sub s}{sup {plus_minus}}{pi}{sup {plus_minus}}{pi}{sup +}. The {Lambda}{sub c}{sup +} is reconstructed with partial information on the {Sigma}{sub s}; the missing {Sigma}{sub s} momentum is established through momentum conservation imposed by a constrained fit. The data are of {pi}{sup {minus}} beam interactions at 250 GeV from Fermilab experiment E769.
Date: October 10, 1995
Creator: Passmore, D.A.
System: The UNT Digital Library
Characterization and application of microearthquake clusters to problems of scaling, fault zone dynamics, and seismic monitoring at Parkfield, California (open access)

Characterization and application of microearthquake clusters to problems of scaling, fault zone dynamics, and seismic monitoring at Parkfield, California

This document contains information about the characterization and application of microearthquake clusters and fault zone dynamics. Topics discussed include: Seismological studies; fault-zone dynamics; periodic recurrence; scaling of microearthquakes to large earthquakes; implications of fault mechanics and seismic hazards; and wave propagation and temporal changes.
Date: October 1, 1995
Creator: Nadeau, R. M.
System: The UNT Digital Library
Synthesis and characterization of nickel hydroxide powders for battery application (open access)

Synthesis and characterization of nickel hydroxide powders for battery application

The primary objective of this research was to investigate the synthesis and characterization of Ni(OH){sub 2} powders by homogeneous precipitation. Previous research of the same method showed conflicting results and complete characterization of the particle morphology was not carried out. This study has produced precipitates having a composition of 2Ni(OH){sub 2}{center_dot}Ni(HCO{sub 3}){sub 1.85}(NO{sub 3}){sub 0.15}. The XRD patterns showed peaks commonly observed for {alpha}-Ni(OH){sub 2}. The precipitates produced from low and high cation concentration solutions showed that the mean particle size and specific surface area increased with aging time. The high specific surface area measured suggested that the particle growth occurred through the aggregation of nanosized crystallites. The TEM micrographs confirmed that the particles were actually aggregates of thin films or sheets that were crumpled and intertwined together. This work also investigated the effect of dispersant on the particle morphology. The addition of dispersants did not alter the density of the particles implying that the dispersants were not incorporated into the solid phase. A general decrease in mean particle size at each aging time was observed resulting in an increase in specific surface area. The use of dispersants provided steric hindrance for the particles in the solution to aggregate, thus …
Date: October 8, 1997
Creator: Widjaja, A.
System: The UNT Digital Library
Experimental and Numerical Investigation of Shock Wave Propagation Through Complex Geometry, Gas Continuous, Two-Phase Media (open access)

Experimental and Numerical Investigation of Shock Wave Propagation Through Complex Geometry, Gas Continuous, Two-Phase Media

The work presented here investigates the phenomenon of shock wave propagation in gas continuous, two-phase media. The motivation for this work stems from the need to understand blast venting consequences in the HYLIFE inertial confinement fusion (ICF) reactor. The HYLIFE concept utilizes lasers or heavy ion beams to rapidly heat and compress D-T targets injected into the center of a reactor chamber. A segmented blanket of failing molten lithium or Li{sub 2}BeF{sub 4} (Flibe) jets encircles the reactors central cavity, shielding the reactor structure from radiation damage, absorbing the fusion energy, and breeding more tritium fuel.
Date: October 1, 1993
Creator: Liu, J. Chien-Chih
System: The UNT Digital Library
Process modeling of plutonium conversion and MOX fabrication for plutonium disposition (open access)

Process modeling of plutonium conversion and MOX fabrication for plutonium disposition

Two processes are currently under consideration for the disposition of 35 MT of surplus plutonium through its conversion into fuel for power production. These processes are the ARIES process, by which plutonium metal is converted into a powdered oxide form, and MOX fuel fabrication, where the oxide powder is combined with uranium oxide powder to form ceramic fuel. This study was undertaken to determine the optimal size for both facilities, whereby the 35 MT of plutonium metal will be converted into fuel and burned for power. The bounding conditions used were a plutonium concentration of 3--7%, a burnup of 20,000--40,000 MWd/MTHM, a core fraction of 0.1 to 0.4, and the number of reactors ranging from 2--6. Using these boundary conditions, the optimal cost was found with a plutonium concentration of 7%. This resulted in an optimal throughput ranging from 2,000 to 5,000 kg Pu/year. The data showed minimal costs, resulting from throughputs in this range, at 3,840, 2,779, and 3,497 kg Pu/year, which results in a facility lifetime of 9.1, 12.6, and 10.0 years, respectively.
Date: October 1, 1998
Creator: Schwartz, K. L.
System: The UNT Digital Library
Characterization and refinement of carbide coating formation rates and dissolution kinetics in the Ta-C system (open access)

Characterization and refinement of carbide coating formation rates and dissolution kinetics in the Ta-C system

The interaction between carbide coating formation rates and dissolution kinetics in the tantalum-carbon system was investigated. The research was driven by the need to characterize carbide coating formation rates. The characterization of the carbide coating formation rates was required to engineer an optimum processing scheme for the fabrication of the ultracorrosion-resistant composite, carbon-saturated tantalum. A packed-bed carburization process was successfully engineered and employed. The packed-bed carburization process produced consistent, predictable, and repeatable carbide coatings. A digital imaging analysis measurement process for accurate and consistent measurement of carbide coating thicknesses was developed. A process for removing the chemically stable and extremely hard tantalum-carbide coatings was also developed in this work.
Date: October 1, 1996
Creator: Rodriguez, P.J.
System: The UNT Digital Library
Basalt features observed in outcrops, cores, borehole video imagery and geophysical logs, and basalt hydrogeologic study at the Idaho National Engineering Laboratory, Eastern Idaho (open access)

Basalt features observed in outcrops, cores, borehole video imagery and geophysical logs, and basalt hydrogeologic study at the Idaho National Engineering Laboratory, Eastern Idaho

A study was undertaken to examine permeable zones identified in boreholes open to the underlying basalt and to describe the vertical cross flows present in the boreholes. To understand the permeable zones in the boreholes detailed descriptions and measurements of three outcrops in the Snake River Plain, three cores at the Idaho Chemical Processing Plant (ICPP) at the INEL, and over fifty borehole TV logs from the INEL were carried out. Based on the observations made on the three outcrops an idealized basalt lava flow model was generated that used a set of nomenclature that would be standard for the basalt lava flows studied. An upper vesicular zone, a sometimes absent columnar zone, central zone, and lower vesicular zone make up the basalt lava flow model. The overall distinction between the different zones are based on the vesicle shape size, vesicularity, and fractures present. The results of the studies also indicated that the basalt lava flows at the INEL are distal to medial facies pahoehoe lava flows with close fitting contacts. The most permeable zones identified in these basalts are fractured vesiculated portions of the top of the lava flow, the columnar areas, and basalt-flow contacts in order of importance. …
Date: October 1, 1996
Creator: Bennecke, William M.
System: The UNT Digital Library
Phase Identification in Reactive Sintering of Molybdenum Disilicide Composites (open access)

Phase Identification in Reactive Sintering of Molybdenum Disilicide Composites

Molybdenum disilicide has been predominantly used for furnace heating elements, but recently there has been interest in its use for high temperature structural applications. The reason for this increased interest stems from its desirable characteristics which are a high melting point, relatively low density, good oxidation resistance, relatively good thermal conductivity and electronically conductive. The melting point of MoSi{sub 2} is approximately 2030{degrees}C as compared to a melting point of 1340{degrees}C for the Ni-based superalloys. This could potentially give MoSi{sub 2} a big advantage over the Ni-based superalloys in turbine applications because the operating temperature can be increased resulting in an increase in turbine efficiency and reduced emissions. The relatively low density (6.25g/cm{sup 3}) compared to the Ni-based superalloys (8.9 g/cm{sup 3}) is an important advantage in turbine applications because of the need for low weight. Good oxidation resistance stems from the ability of MoSi{sub 2} to form a protective SiO{sub 2} surface layer when exposed to oxygen. Another advantageous feature of MoSi{sub 2} is its thermal conductivity which is superior to Ni-based superalloys at low temperatures and comparable to the Ni-based superalloys at high temperatures. This allows heat to be dissipated at a rate better than ceramics and comparable …
Date: October 1, 1996
Creator: Alba, Jose, Jr.
System: The UNT Digital Library
Heavy ion beam propagation through a gas-filled chamber for inertial confinement fusion (open access)

Heavy ion beam propagation through a gas-filled chamber for inertial confinement fusion

The work presented here evaluates the dynamics of a beam of heavy ions propagating through a chamber filled with gas. The motivation for this research stems from the possibility of using heavy ion beams as a driver in inertial confinement fusion reactors for the purpose of generating electricity. Such a study is important in determining the constraints on the beam which limit its focus to the small radius necessary for the ignition of thermonuclear microexplosions which are the source of fusion energy. Nuclear fusion is the process of combining light nuclei to form heavier ones. One possible fusion reaction combines two isotopes of hydrogen, deuterium and tritium, to form an alpha particle and a neutron, with an accompanying release of {approximately}17.6 MeV of energy. Generating electricity from fusion requires that we create such reactions in an efficient and controlled fashion, and harness the resulting energy. In the inertial confinement fusion (ICF) approach to energy production, a small spherical target, a few millimeters in radius, of deuterium and tritium fuel is compressed so that the density and temperature of the fuel are high enough, {approximately}200 g/cm{sup 3} and {approximately}20 keV, that a substantial number of fusion reactions occur; the pellet microexplosion …
Date: October 1, 1996
Creator: Barboza, Nigel Oswald
System: The UNT Digital Library
Response of the D0 calorimeter to cosmic ray muons (open access)

Response of the D0 calorimeter to cosmic ray muons

The D0 Detector at the Fermi National Accelerator Laboratory is a large multi-purpose detector facility designed for the study of proton-antiproton collision products at the center-of-mass energy of 2 TeV. It consists of an inner tracking volume, hermetic uranium/liquid argon sampling calorimetry, and an outer 4{pi} muon detector. In preparation for our first collider run, the collaboration organized a Cosmic Ray Commissioning Run, which took place from February - May of 1991. This thesis is a detailed study of the response of the central calorimeter to cosmic ray muons as extracted from data collected during this run.
Date: October 1, 1992
Creator: Kotcher, J.
System: The UNT Digital Library
Improved resins and novel materials and methods for solid phase extraction and high performance liquid chromatography (open access)

Improved resins and novel materials and methods for solid phase extraction and high performance liquid chromatography

Solid-phase extraction (SPE) has grown to be one of the most widely used methods for isolation and preconcentration of a vast range of compounds from aqueous solutions. By modifying polymeric SPE resins with chelating functional groups, the selective uptake of metals was accomplished. The resin, along with adsorbed metals, was vaporized in the ICP and detection of the metals was then possible using either mass or emission spectroscopy. Drug analyses in biological fluids have received heightened attention as drug testing is on the increase both in sports and in the work environment. By using a direct-injection technique, biological fluids can be injected directly into the liquid chromatographic system with no pretreatment. A new surfactant, a sulfonated form of Brij-30 (Brij-S) is shown to prevent the uptake of serum proteins on commercial HPLC columns by forming a thin coating on the silica C18 surface. Excellent separations of eight or more drugs with a wide range of retention times were obtained. The separations had sharper peaks and lower retention times than similar separations performed with the surfactant sodium dodecylsulfate (SDS). Quantitative recovery of a number of drugs with limits of detection near 1 ppm with a 5 {micro}l injection volume were obtained. …
Date: October 8, 1997
Creator: Freeze, R.
System: The UNT Digital Library
Nonlinear response of superconductors to alternating fields and currents (open access)

Nonlinear response of superconductors to alternating fields and currents

This report discusses the following topics on superconductivity: nonlinearities in hard superconductors such as surface impedance of a type II superconductimg half space and harmonic generation and intermodulation due to alternating transport currents; and nonlinearities in superconducting weak links such as harmonic generation by a long Josephson Junction in a superconducting slab.
Date: October 8, 1997
Creator: McDonald, J.
System: The UNT Digital Library
Equilibrium vortex motion in two- and three-dimensional superconductors studied with a dc SQUID (open access)

Equilibrium vortex motion in two- and three-dimensional superconductors studied with a dc SQUID

The equilibrium motion of vortices in two- and three-dimensional superconductors has been studied with a dc Superconducting QUantum Interference Device (SQUID). This technique has the advantage of probing the system in a non-invasive manner as well as providing dynamic information over many decades in frequency. Through measurements of the spectral density of magnetic flux noise, S{sub {Phi}}({omega}), as a function of temperature and applied magnetic field, the effects of proton and heavy ion irradiation on flux noise in crystals of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} have been measured and compared with the effects on the critical current, J{sub c}. Both proton and heavy ion irradiation proved effective at reducing S{sub {Phi}}({omega}), with proton irradiation having a larger effect. Measurement of S{sub {Phi}}({omega}) due to the equilibrium Kosterlitz-Thouless-Berezinskii transition in two-dimensional Josephson Junction Arrays (JJAs) was studied as a function of temperature for three different arrays and using three different sensors. S{sub {Phi}} is shown to obey dynamic scaling over as many as five decades in frequency, and estimates are made for the dynamic critical exponent z. An analytic theory for the high- and low-frequency behavior of S{sub {Phi}}({omega}) is presented and compared to the measured data, with the result that the …
Date: October 1, 1997
Creator: Shaw, T.J.
System: The UNT Digital Library
Microstructure-strength relationships of heavily deformed magnesium-lithium composites containing steel fibers (open access)

Microstructure-strength relationships of heavily deformed magnesium-lithium composites containing steel fibers

The successful development of deformation-processed metal-metal composites (DMMC) offers the potential for ductile, high-strength structural materials with high-temperature stability. An infiltration casting process was used to permeate steel wool preforms with molten magnesium-lithium (Mg-Li) alloys. The selected matrix alloys were hexagonal close packed (HCP) Mg-4wt%Li or body centered cubic (BCC) Mg-12wt%Li; the low carbon steel wool fibers were predominantly BCC ferrite. These cast HCP/BCC and BCC/BCC composites were deformed by rolling or by extrusion and swaging. Mechanical properties, microstructure, and texture development of the composites were characterized at various levels of deformation. The HCP/BCC composites had limited formability at temperatures up to 400 C while the BCC/BCC composites had excellent formability during sheet rolling at room temperature but limited formability during swaging at room temperature. The tensile strengths of these HCP/BCC and BCC/BCC composite materials increased moderately with deformation, though less than predicted from rule of mixtures (ROM) calculations. The microstructure was characterized to correlate the filament size to the deformation strain and mechanical properties of the composite material. Stereological measurements of the filament size were used to adjust ROM calculations to reflect the actual deformation strain in the fibers. However, the experimental strengths of these composite materials were still …
Date: October 8, 1997
Creator: Jensen, J.
System: The UNT Digital Library
Direct methods for dynamic monitoring of secretions from single cells by capillary electrophoresis and microscopy with laser-induced native fluorescence detection (open access)

Direct methods for dynamic monitoring of secretions from single cells by capillary electrophoresis and microscopy with laser-induced native fluorescence detection

Microscale separation and detection methods for real-time monitoring of dynamic cellular processes (e.g., secretion) by capillary electrophoresis (CE) and microscopic imaging were developed. Ultraviolet laser-induced native fluorescence (LINF) provides simple, sensitive and direct detection of neurotransmitters and proteins without any derivatization. An on-column CE-LINF protocol for quantification of the release from single cell was demonstrated. Quantitative measurements of both the amount of insulin released from and the amount remaining in the cell ({beta}TC3) were achieved simultaneously. Secretion of catecholamines (norepinephrine (NE) and epinephrine (E)) from individual bovine adrenal chromaffin cells was determined using the on-column CE-LINF. Direct visualization of the secretion process of individual bovine adrenal chromaffin cells was achieved by LINF imaging microscopy with high temporal and spatial resolution. The secretion of serotonin from individual leech Retzius neurons was directly characterized by LINF microscopy with high spatial resolution.
Date: October 8, 1997
Creator: Tong, W.
System: The UNT Digital Library
Development and application of thin-layer spectroelectrochemical techniques for the study of organosulfur monolayers adsorbed at gold (open access)

Development and application of thin-layer spectroelectrochemical techniques for the study of organosulfur monolayers adsorbed at gold

A main research interest is the characterization of monolayers formed by the spontaneous adsorption of organosulfur compounds at gold. This dissertation describes the development and application of long optical pathlength thin-layer spectroelectrochemistry in an attempt to address key issues regarding the reactivity of surface-immobilized molecules. The first section of this introductory chapter briefly describes the general approach to the preparation and characterization of these films. The last section provides an overview of the main principles and advantages of thin-layer spectroelectrochemistry for studying surface-adsorbed species. The body of this dissertation is divided into four chapters. Chapter 2 consists of a paper describing the design, construction, and characterization of a cuvette-based LOPTLC. Chapter 3 is a paper which examines the reductive desorption process using thin-layer spectroelectrochemistry to monitor and identify the desorption product. Chapter 4 is a paper describing the characterization of monolayers functionalized with a catechol terminal group which serves as a redox transformable coordination site for metal ion binding. Chapter 5 discusses the application of thin-layer spectroelectrochemistry to acid-base reactivity studies of surface-immobilized molecules. The final section provides some general conclusions and a prospectus for future studies. These chapters have been processed separately for inclusion on the data base. This …
Date: October 8, 1997
Creator: Simmons, N.
System: The UNT Digital Library
Simulational studies of epitaxial semiconductor superlattices: Quantum dynamical phenomena in ac and dc electric fields (open access)

Simulational studies of epitaxial semiconductor superlattices: Quantum dynamical phenomena in ac and dc electric fields

Using high-accuracy numerical methods the author investigates the dynamics of independent electrons in both ideal and realistic superlattices subject to arbitrary ac and/or dc electric fields. For a variety of superlattice potentials, optically excited initial wave packets, and combinations of ac and dc electric fields, he numerically solves the time-dependent Schroedinger equation. In the case of ideal periodic superlattice potentials, he investigates a long list of dynamical phenomena involving multiple miniband transitions and time-dependent electric fields. These include acceleration effects associated with interminiband transitions in strong fields, Zener resonances between minibands, dynamic localization with ac fields, increased single-miniband transport with an auxiliary resonant ac field, and enhanced or suppressed interminiband probability exchange using an auxiliary ac field. For all of the cases studied, the resulting time-dependent wave function is analyzed by projecting the data onto convenient orthonormal bases. This allows a detailed comparison with approximately analytic treatments. In an effort to explain the rapid decay of experimentally measured Bloch oscillation (BO) signals the author incorporates a one-dimensional representation of interface roughness (IR) into their superlattice potential. He shows that as a result of IR, the electron dynamics can be characterized in terms of many discrete, incommensurate frequencies near the Block …
Date: October 8, 1997
Creator: Reynolds, J.
System: The UNT Digital Library