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Coordination chemistry of two heavy metals: I, Ligand preferences in lead(II) complexation, toward the development of therapeutic agents for lead poisoning: II, Plutonium solubility and speciation relevant to the environment

Description: The coordination chemistry and solution behavior of the toxic ions lead(II) and plutonium(IV, V, VI) have been investigated. The ligand pK{sub a}s and ligand-lead(II) stability constants of one hydroxamic acid and four thiohydroaxamic acids were determined. Solution thermodynamic results indicate that thiohydroxamic acids are more acidic and slightly better lead chelators than hydroxamates, e.g., N-methylthioaceto-hydroxamic acid, pK{sub a} = 5.94, log{beta}{sub 120} = 10.92; acetohydroxamic ac… more
Date: November 1, 1993
Creator: Neu, M. P.
Partner: UNT Libraries Government Documents Department
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Aging effects on the microstructure, surface characteristics and wettability of Cu pretinned with Sn-Pb solders

Description: This study investigates effects of aging in air and argon at 170 C on Cu coupons which were pretinned with 75Sn-25Pb, 8Sn-92Pb, and 5Sn-95Pb solders. Coatings were applied using electroplating or hot dipping techniques. The coating thickness was controlled between 3 to 3{mu}m and the specimens were aged for 0 hours, 2 hours, 24 hours and 2 weeks. Wetting balance tests were used to evaluate the wettability of the test specimens. Microstructural development was evaluated using X-ray diffraction, … more
Date: November 1, 1993
Creator: Linch, H. S.
Partner: UNT Libraries Government Documents Department
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Population Differentiation in Tree-Ring Growth Response of White Fir (Abies Concolor) to Climate: Implications for Predicting Forest Responses to Climate Change

Description: Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four… more
Date: October 1, 1993
Creator: Jensen, D. B.
Partner: UNT Libraries Government Documents Department
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Synthesis and characterization of novel ternary and quaternary reduced molybdenum oxides

Description: This thesis is divided into 8 sections: synthesis and characterization (char.) of Ba{sub 3}Mo{sub 18}O{sub 28} (an oligomer with four traps edge-sharing Mo octahedra); synthesis and char. of K{sub x}M{sub y}Mo{sub 14}O{sub 22} (M=Sn, Pb, Sr) (oligomers with three traps edge-sharing Mo octahedra); synthesis and char. of K{sub 0.19}Ba{sub 3.81}Mo{sub 22}O{sub 34} (an oligomer with five traps edge-sharing Mo octahedra); synthesis and char. of Ti{sub 0.31}Fe{sub 1.69}Mo{sub 4}O{sub 7} (a material c… more
Date: July 1, 1993
Creator: Schimek, G. L.
Partner: UNT Libraries Government Documents Department
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Gas phase thermochemistry of organogermanium compounds

Description: A variety of silyl- and alkyl-germylene precursors have been synthesized and subsequently pyrolyzed in the gas phase. Arrhenius parameters were obtained employing a pulsed-stirred flow reactor for these unimolecular decompositions. These precursors are divided into two major categories by mechanism of germylene extrusion: {alpha}-elimination precursors and germylacetylenes. The extrusion of germylenes from germylacetylene precursors is of primary interest. A mechanism is proposed employing a ge… more
Date: December 7, 1993
Creator: Engel, J. P.
Partner: UNT Libraries Government Documents Department
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Microstructural development and mechanical behavior of eutectic bismuth-tin and eutectic indium-tin in response to high temperature deformation

Description: The mechanical behavior and microstructure of eutectic Bi-Sn and In-Sn solders were studied in parallel in order to better understand high temperature deformation of these alloys. Bi-Sn solder joints were made with Cu substrates, and In-Sn joints were made with either Cu or Ni substrates. The as-cast microstructure of Bi-Sn is complex regular, with the two eutectic phases interconnected in complicated patterns. The as-cast microstructure of In-Sn depends on the substrate. In-Sn on Cu has a non-… more
Date: November 1, 1993
Creator: Goldstein, J. L. F.
Partner: UNT Libraries Government Documents Department
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Effect of snails (Elimia clavaeformis) on phosphorus cycling in stream periphyton and leaf detritus communities

Description: In this study, the author examined the effect of grazing on phosphorus cycling in stream periphyton and leaf detritus communities using the snail Elimia clavaeformis. Phosphorus cycling fluxes and turnover rates were measured in a laboratory and in a natural stream, respectively, using radioactive tracer techniques.
Date: October 1, 1993
Creator: Jay, E. A.
Partner: UNT Libraries Government Documents Department
open access

Infrared diode laser studies of the products from the reaction CH{sub 2}({tilde X}{sup 3}B{sub 1}) + O{sub 2} and from the near-UV photolysis of CH{sub 3}NCS

Description: Absolute yields of CO, CO{sub 2}, and H{sub 2}CO formed in reaction of triplet methylene ({tilde X} {sup 3}B{sub 1} {triple_bond} CH{sub 2}) with O{sub 2} were determined using a flash kinetic spectrometer. CH{sub 2} radicals were generated by excimer laser photolysis of ketene and product formation was monitored by time-resolved infrared diode laser absorption. Reaction was carried out in a static gas cell at room temperature at 1--25 torr. Measured product yields were CO, 0.34 {plus_minus} 0.… more
Date: December 1, 1993
Creator: Alvarez, R. A.
Partner: UNT Libraries Government Documents Department
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Chemically modified polymeric resins for solid-phase extraction and group separation prior to analysis by liquid or gas chromatography

Description: Polystyrene divinylbenzene was modified by acetyl, sulfonic acid, and quaternary ammonium groups. A resin functionalized with an acetyl group was impregnated in a PTFE membrane and used to extract and concentrate phenolic compounds from aqueous samples. The acetyl group created a surface easily wetted, making it an efficient adsorbent for polar compounds in water. The membrane stabilized the resin bed. Partially sulfonated high surface area resins are used to extract and group separate an aqueo… more
Date: July 1, 1993
Creator: Schmidt, L. W.
Partner: UNT Libraries Government Documents Department
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Ion-assisted laser deposition of intermediate layers for YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin film growth on polycrystalline and amorphous substrates

Description: The growth of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) high-temperature superconductor thin films has largely been limited to deposition on single-crystal substrates to date. In order to expand the range of potential applications, growth on polycrystalline and amorphous substrates is desirable. In particular, the deposition of YBCO thin films with high critical current densities on polycrystalline metal alloys would allow the manufacture of superconducting tapes. However, it is shown that it … more
Date: November 1, 1993
Creator: Reade, R. P.
Partner: UNT Libraries Government Documents Department
open access

A transient, quadratic nodal method for triangular-Z geometry

Description: Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challengi… more
Date: June 1, 1993
Creator: DeLorey, T. F.
Partner: UNT Libraries Government Documents Department
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Optimization of separation and detection schemes for DNA with pulsed field slab gel and capillary electrophoresis

Description: The purpose of the Human Genome Project is outlined followed by a discussion of electrophoresis in slab gels and capillaries and its application to deoxyribonucleic acid (DNA). Techniques used to modify electroosmotic flow in capillaries are addressed. Several separation and detection schemes for DNA via gel and capillary electrophoresis are described. Emphasis is placed on the elucidation of DNA fragment size in real time and shortening separation times to approximate real time monitoring. The… more
Date: July 1, 1993
Creator: McGregor, D. A.
Partner: UNT Libraries Government Documents Department
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Properties of W + jet events in proton-antiproton collisions at 1.8 TeV

Description: W boson + QCD Jet events, produced in 1.8 TeV proton-antiproton collisions and measured by the Collider Detector at Fermilab (CDF), were used to measure the center-of-mass production angle of the W + jet system, and were also used to place limits on the production of excited quark states. The center-of-mass production angular distribution agrees well with leading order and next-to-leading order QCD predictions. Excited quark states were searched for in the reaction q + g {yields} q* {yields} q … more
Date: November 22, 1993
Creator: Drucker, R. B.
Partner: UNT Libraries Government Documents Department
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Modern integral equation techniques for quantum reactive scattering theory

Description: Rigorous calculations of cross sections and rate constants for elementary gas phase chemical reactions are performed for comparison with experiment, to ensure that our picture of the chemical reaction is complete. We focus on the H/D+H{sub 2} {yields} H{sub 2}/DH + H reaction, and use the time independent integral equation technique in quantum reactive scattering theory. We examine the sensitivity of H+H{sub 2} state resolved integral cross sections {sigma}{sub v{prime}j{prime},vj}(E) for the t… more
Date: November 1, 1993
Creator: Auerbach, S. M.
Partner: UNT Libraries Government Documents Department
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Investigation of the phase equilibria and phase transformations associated with the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor

Description: The solid solution region and reaction kinetics of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) superconductor were examined as a function of temperature and oxygen partial pressure. Crystallization studies from the glassy and molten states were undertaken to determine the phase transformation and kinetics associated with the formation of 2212 and other competing phases. Crystallization of nominal 2212 glasses was found to proceed in two steps with the formation of Bi{sub 2}Sr{sub 2{minus}x… more
Date: December 9, 1993
Creator: Holesinger, T.
Partner: UNT Libraries Government Documents Department
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Optical field ionization of atoms and ions using ultrashort laser pulses

Description: This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He{sup +2}, Ne{sup +2} and Ar{sup +2}. The ion yields for He{sup +l}, Ne{sup +l} and Ar{sup +l} agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of t… more
Date: December 1, 1993
Creator: Fittinghoff, D. N.
Partner: UNT Libraries Government Documents Department
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A measurement of the ({tau}) polarization at the Z resonance with the DELPHI detector at LEP

Description: The polarization of {tau} leptons produced in the reaction e{sup +}e{sup {minus}} {yields} {tau}{sup +}{tau}{sup {minus}} near the peak of the Z{degree} resonance has been measured using a sample of 24904 {tau}{sup +}{tau}{sup {minus}} events, with an estimated background of 1.5%. We have selected 4562 {tau} {yields} e{nu}{bar {nu}} 2218 {tau} {yields} {pi}{nu} and 5133 {tau} {yields} {rho}{nu} candidates. The mean value obtained is P{sub {tau}} = {minus}0.176 {plus_minus} 0.029. This correspon… more
Date: July 1, 1993
Creator: Wong Chan, A.
Partner: UNT Libraries Government Documents Department
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Laser-material interactions: A study of laser energy coupling with solids

Description: This study of laser-light interactions with solid materials ranges from low-temperature heating to explosive, plasma-forming reactions. Contained are four works concerning laser-energy coupling: laser (i) heating and (ii) melting monitored using a mirage effect technique, (iii) the mechanical stress-power generated during high-powered laser ablation, and (iv) plasma-shielding. First, a photothermal deflection (PTD) technique is presented for monitoring heat transfer during modulated laser heati… more
Date: November 1, 1993
Creator: Shannon, M. A.
Partner: UNT Libraries Government Documents Department
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The Effect of surface morphology on the friction of Electrogalvanized sheet steel in forming processes

Description: The effect in the drawbead simulator test were evaluated for a set of commercially coated steels and a set of laboratory coated steels with underlying surfaces produced by laser textured, shot blast, and electro-discharge textured rolls. In general, surfaces with higher roughness (R{sub a} parameter) measured lower friction in the DBS tests. The requisite roughness amplitude necessary for low friction was moderated somewhat by having a more closely spaced roughness as described by the median wa… more
Date: December 1, 1993
Creator: Skarpelos, P. N.
Partner: UNT Libraries Government Documents Department
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Plasma enhanced chemical vapor deposition of ZrO{sub 2} thin films

Description: Amorphous ZrO{sub 2} thin films were deposited in an inductively coupled PECVD system using a Zr {beta}-diketonate, Zr(C{sub 11}H{sub 19}O{sub 2}){sub 4}, as the precursor. The deposits were air annealed at 900C for 5 min to get pure, single phase, oriented, polycrystalline {alpha}-ZrO{sub 2}. Feasibility of using 2 different types of reactors was investigated. The inductively heated horizontal reactor depositions at 600C had a lower deposition rate and the films were non-uniform in thickness w… more
Date: December 9, 1993
Creator: Saravanan, Kolandaivelu
Partner: UNT Libraries Government Documents Department
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Interstitially stabilized phases in the zirconium-nickel system

Description: Addition of nonmetal interstitial atoms to Zr-Ni compounds has resulted in several new phases. A single-crystal x-ray study was carried out for Zr{sub 3}NiO. Zr{sub 4}Ni{sub 2}O is a high- temperature phase, forming in samples annealed at 1250 C. Huekel band calculations led to prediction and confirmation of additional phases in more electron rich systems. Other phases studied by XRD are Zr{sub 6}Ni{sub 4}Ti{sub 2}O{sub 0.6}, Nb{sub 6}Ni{sub 6}O, and Nb{sub 6}Ni{sub 4}Ta{sub 2}O{sub 2}. Phases … more
Date: July 1, 1993
Creator: MacKay, R. A.
Partner: UNT Libraries Government Documents Department
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Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

Description: This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Enviro… more
Date: October 1, 1993
Creator: Lindley, R. A.
Partner: UNT Libraries Government Documents Department
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Elastic scattering of pions from tritium and {sup 3}He in the backward hemisphere in the region of the {Delta}{sub 33}(1232) resonance

Description: Several experiments have measured nominally-charge-symmetric scattering of pions from tritium ({sup 3}H) and {sup 3}He. These experiments have covered incident pion energies from 142 MeV to 295 MeV and scattering angles up to 110{degrees} in the laboratory. The results have been used to study charge-symmetry breaking and nuclear scattering systematics. In the work I have extended these measurements to angles near 180{degrees} for pion energies of 142 MeV, 180 MeV, 220 MeV, and 256 MeV, which br… more
Date: November 1, 1993
Creator: Matthews, S. K.
Partner: UNT Libraries Government Documents Department
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Polarized light scattering as a probe for changes in chromosome structure

Description: Measurements and calculations of polarized light scattering are applied to chromosomes. Calculations of the Mueller matrix, which completely describes how the polarization state of light is altered upon scattering, are developed for helical structures related to that of chromosomes. Measurements of the Mueller matrix are presented for octopus sperm heads, and dinoflagellates. Comparisons of theory and experiment are made. A working theory of polarized light scattering from helices is developed.… more
Date: October 1, 1993
Creator: Shapiro, D. B.
Partner: UNT Libraries Government Documents Department
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