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Intermolecula transfer and elimination of molecular hydrogen in thermal reactions of unsaturated organic compounds

Description: Two reactions which are important to coal liquefaction include intermolecular transfer and the elimination of two hydrogen atoms. We have designed several model reactions to probe the viability of several hydrogen transfer and elimination pathways. This report described studies on these reactions using organic model compounds.
Date: February 10, 1995
Creator: Suria, S.
Partner: UNT Libraries Government Documents Department
open access

Interactions of hydrogen with alkali promoted Ru/SiO{sub 2} catalysts: A proton NMR study

Description: Role of H spillover to the silica support was studied using chemisorption; a strongly bound component of spilled over H was found in the silica support which interfered with accurate measurements of active metal sites via volumetric strong H chemisorption. The volumetric chemisorption technique was modified so that measurement times were reduced from 12--36 h to 1 h. The active Ru surface was characterized means of changes in proton spin counts and NMR Knight shifts vs alkali loading. Na, K blo… more
Date: May 10, 1994
Creator: Ozbay, U. D.
Partner: UNT Libraries Government Documents Department
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Structural studies of conformational changes of proteins upon phosphorylation: Structures of activated CheY, CheY-N16-FliM complex, and AAA {sup +} ATPase domain of NtrC1 in both inactive and active states

Description: Protein phosphorylation is a general mechanism for signal transduction as well as regulation of cellular function. Unlike phosphorylation in eukaryotic systems that uses Ser/Thr for the sites of modification, two-component signal transduction systems, which are prevalent in bacteria, archea, and lower eukaryotes, use an aspartate as the site of phosphorylation. Two-component systems comprise a histidine kinase and a receiver domain. The conformational change of the receiver domain upon phosphor… more
Date: April 10, 2003
Creator: Lee, Seok-Yong
Partner: UNT Libraries Government Documents Department
open access

DECAY PROPERTIES OF THE E HYPERON AND E RESONANCES

Description: A sample of 2500 {Xi}{sup -} and 500 {Xi}{sup 0} hyperons, produced in {Xi}K, {Xi}K{pi}, and {Xi}K{pi}{pi} final states by K{sup -} (in H{sub 2}) at incident momenta of 1.7 to 2.7 BeV/c, has been analyzed. The data are from an exposure (K-63) of 26 events/{mu}b in the 72-inch bubble chamber; approximately 85% of the {Xi}{sup -} events and 60% of the {Xi}{sup 0} events have been analyzed. For the {Xi}, they determine the spin and decay parameters a{sub {Xi}} and {Phi}{sub {Xi}} = tan{sup -1} ({b… more
Date: September 10, 1966
Creator: Merrill, Jr., Deane W.
Partner: UNT Libraries Government Documents Department
open access

A Measurement of the Rate of Muon Capture in Hydrogen Gas andDetermination of the Proton's Induced Pseudoscalar Coupling gP

Description: This dissertation describes a measurement of the rate ofnuclear muon capture by the proton, performed by the MuCap Collaborationusing a new technique based on a time projection chamber operating inultraclean, deuterium-depleted hydrogen gas at room temperature and 1 MPapressure. The hydrogen target's low gas density of 1 percent compared toliquid hydrogen is key to avoiding uncertainties that arise from theformation of muonic molecules. The capture rate was obtained from thedifference between t… more
Date: July 10, 2007
Creator: Banks, Thomas Ira
Partner: UNT Libraries Government Documents Department
open access

Inductively coupled plasma mass spectrometry for stable isotope metabolic tracer studies of living systems

Description: This dissertation focuses on the development of methods for stable isotope metabolic tracer studies in living systems using inductively coupled plasma single and dual quadrupole mass spectrometers. Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the an… more
Date: May 10, 1999
Creator: Luong, E.
Partner: UNT Libraries Government Documents Department
open access

The Higgs boson in the Standard Model theoretical constraints and a direct search in the wh channel at the Tevatron

Description: We have presented results in two different yet strongly linked aspects of Higgs boson physics. We have learned about the importance of the Higgs boson for the fate of the Standard Model, being either only a theory limited to explaining phenomena at the electroweak scale or, if the Higgs boson lies within a mass range of 130 &lt; m<sub>H</sub> &lt; 160 GeV the SM would remain a self consistent theory up to highest energy scales O(m<sub>Pl</sub>). This could have direct implications on theories o… more
Date: September 10, 2010
Creator: Huske, Nils Kristian & (Germany)], Bielefeld Univ.
Partner: UNT Libraries Government Documents Department
open access

Evidence for neutrino oscillations in the Sudbury Neutrino Observatory

Description: The Sudbury Neutrino Observatory (SNO) is a large-volume heavy water Cerenkov detector designed to resolve the solar neutrino problem. SNO observes charged-current interactions with electron neutrinos, neutral-current interactions with all active neutrinos, and elastic-scattering interactions primarily with electron neutrinos with some sensitivity to other flavors. This dissertation presents an analysis of the solar neutrino flux observed in SNO in the second phase of operation, while {approx}2… more
Date: August 10, 2004
Creator: Marino, Alysia Diane
Partner: UNT Libraries Government Documents Department
open access

Measurement of the Decay B to Omega L Nu with the BaBar Detector and Determination of V_Ub

Description: We measure the branching fraction of the exclusive charmless semileptonic decay B {yields} {omega}{ell}{nu}{sub {ell}}, where {ell} is either an electron or a muon, with the charged B meson recoiling against a tag B meson decaying in the charmed semileptonic modes B {yields} D{ell}{nu}{sub {ell}} or B {yields} D*{ell}{nu}{sub {nu}}. The measurement is based on a dataset of 426.1 fb{sup -1} of e{sup +}e{sup -} collisions at a CM energy of 10.58 GeV recorded with the BABAR detector at the PEP-II … more
Date: September 10, 2010
Creator: Nagel, Martin
Partner: UNT Libraries Government Documents Department
open access

In situ vibrational spectroscopic investigation of C{sub 4} hydrocarbon selective oxidation over vanadium-phosphorus-oxide catalysts

Description: n-Butane selective oxidation over the VPO catalyst to maleic anhydride is the first and only commercialized process of light alkane selective oxidation. The mechanism of this reaction is still not well known despite over twenty years of extensive studies, which can partially be attributed to the extreme difficulties to characterize catalytic reactions real-time under typical reaction conditions. In situ spectroscopic characterization techniques such as Infrared spectroscopy and laser Raman spec… more
Date: May 10, 1999
Creator: Xue, Z.Y.
Partner: UNT Libraries Government Documents Department
open access

NMR and NQR study of the thermodynamically stable quasicrystals

Description: {sup 27}Al and {sup 61,65}Cu NMR measurements are reported for powder samples of stable AlCuFe and AlCuRu icosahedral quasicrystals and their crystalline approximants, and for a AlPdMn single grain quasicrystal. Furthermore, {sup 27}Al NQR spectra at 4.2 K have been observed in the AlCuFe and AlCuRu samples. From the quadrupole perturbed NMR spectra at different magnetic fields, and from the zero field NQR spectra, a wide distribution of local electric field gradient (EFG) tensor components and… more
Date: February 10, 1995
Creator: Shastri, A.
Partner: UNT Libraries Government Documents Department
open access

The relationship of structure to superconductivity in the Pr-Ba-Cu-O system

Description: The relation of structure to lack of superconductivity in Pr-Ba-Cu-O was systematically investigated. First, the phase equilibria of this system was studied to find the processing parameters which maximize the cation-site ordering between Pr and Ba ions. Second, a comparative study between superconducting Nd-Ba-Cu-0 and non- superconducting Pr-Ba-Cu-0 was performed by forming solid-solution Nd- Pr-Ba-Cu-0. The relation between structure and superconductivity in Nd{sub 1{minus}x}Pr{sub x}Ba{sub … more
Date: May 10, 1994
Creator: Minseo, P.
Partner: UNT Libraries Government Documents Department
open access

Fundamental studies of the plasma extraction and ion beam formation processes in inductively coupled plasma mass spectrometry

Description: The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, slumming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced. The plasma extraction pr… more
Date: February 10, 1995
Creator: Niu, Hongsen
Partner: UNT Libraries Government Documents Department
open access

Development of a new Pb-free solder: Sn-Ag-Cu

Description: With the ever increasing awareness of the toxicity of Pb, significant pressure has been put on the electronics industry to get the Pb out of solder. This work pertains to the development and characterization of an alloy which is Pb-free, yet retains the proven positive qualities of current Sn-Pb solders while enhancing the shortcomings of Sn-Pb solder. The solder studied is the Sn-4.7Ag-1.7Cu wt% alloy. By utilizing a variety of experimental techniques the alloy was characterized. The alloy has… more
Date: February 10, 1995
Creator: Miller, C. M.
Partner: UNT Libraries Government Documents Department
open access

Electrochemical and scanning probe microscopic characterization of spontaneously adsorbed organothiolate monolayers at gold

Description: This dissertation presented several results which add to the general knowledge base regarding organothiolates monolayer spontaneously adsorbed at gold films. Common to the body of this work is the use of voltammetric reductive resorption and variants of scanning probe microscopy to gain insight into the nature of the monolayer formation process as well as the resulting interface. The most significant result from this work is the success of using friction force microscopy to discriminate the end… more
Date: December 10, 1999
Creator: Wong, Sze-Shun Season
Partner: UNT Libraries Government Documents Department
open access

Unique applications of solvent removal in inductively coupled plasma mass spectrometry

Description: Inductively coupled plasma mass spectrometry (ICP-MS) is the technique of choice for rapid, high precision, semiquantitative elemental and isotopic analysis for over 70 elements. Less than 20 years after the first mass spectrum was obtained by ICP-MS, this technique has applications in clinical chemistry, geochemistry, the semiconductor industry, the nuclear industry, environmental chemistry, and forensic chemistry. The determination of many elements, though, by ICP-MS is complicated by spectra… more
Date: January 10, 1997
Creator: Minnich, M.
Partner: UNT Libraries Government Documents Department
open access

Fast methods for analysis of neurotransmitters from single cell and monitoring their releases in central nervous system by capillary electrophoresis, fluorescence microscopy and luminescence imaging

Description: Fast methods for separation and detection of important neurotransmitters and the releases in central nervous system (CNS) were developed. Enzyme based immunoassay combined with capillary electrophoresis was used to analyze the contents of amino acid neurotransmitters from single neuron cells. The release of amino acid neurotransmitters from neuron cultures was monitored by laser induced fluorescence imaging method. The release and signal transduction of adenosine triphosphate (ATP) in CNS was s… more
Date: December 10, 1999
Creator: Wang, Ziqiang
Partner: UNT Libraries Government Documents Department
open access

A semi-experimental nodal synthesis method for the on-line reconstruction of three-dimensional neutron flux-shapes and reactivity. Final report

Description: The safety and optimal performance of large, commercial, light-water reactors require the knowledge at all time of the neutron-flux distribution in the core. In principle, this information can be obtained by solving the time-dependent neutron diffusion equations. However, this approach is complicated and very expensive. Sufficiently accurate, real-time calculations (time scale of approximately one second) are not yet possible on desktop computers, even with fast-running, nodal kinetics codes. A… more
Date: December 10, 1991
Creator: Jacqmin, Robert P.
Partner: UNT Libraries Government Documents Department
open access

Characterization of electrical resistivity as a function of temperature in the Mo-Si-B system

Description: Measurements of electrical resistivity as a function of temperature from 25 to 1,500 C were conducted on polycrystalline samples in the Mo-Si-B system. Single phase, or nearly single phase, samples were prepared for the following phases: Mo{sub 3}Si, Mo{sub 5}SiB{sub 2}, Mo{sub 5}Si{sub 3}B{sub x}, MoB, MoSi{sub 2}, and Mo{sub 5}Si{sub 3}. Thesis materials all exhibit resistivity values within a narrow range(4--22 x 10{sup {minus}7}{Omega}-m), and the low magnitude suggests these materials are … more
Date: December 10, 1999
Creator: Beckman, Sarah E.
Partner: UNT Libraries Government Documents Department
open access

Dalitz Analysis of D0 to K0(S) Pi+ Pi- and Measurement of the CKM Angle Gamma in Charged B+- Decays to D(*) K+- Decays

Description: Despite more than thirty years having elapsed since the discovery of CP violation, our understanding about the source and the nature of this phenomenon is still very limited. In the standard model of particle physics, CP violation is due to the presence of an non-irreducible weak phase in the Cabibbo-Kabayashi-Maskawa(CKM) matrix. Up to now, all the experimental results are in good agreement with the standard model. However, it is important for us to over-constrain the CKM quark-mixing matrix a… more
Date: July 10, 2007
Creator: Lau, Yan-Pan
Partner: UNT Libraries Government Documents Department
open access

Measurement of CP Violation in B0 to Phi K0, and of Branching Fraction and CP Violation in B0 to F0(980) K0(S)

Description: The authors measure the time-dependent CP asymmetry parameters in B{sup 0} {yields} K{sup +}K{sup -}K{sup 0} based on a data sample of approximately 277 million B-meson pairs recorded at the {Upsilon}(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct two-body B{sup 0} decays to {phi}(1020)K{sub s}{sup 0} and {phi}(1020)K{sub L}{sup 0}. Using a time-dependent maximum-likelihood fit, they measure sin2{beta}{sub eff}({phi}K{sup 0}) = 0.48 {+-} 0.28 {+-} … more
Date: March 10, 2008
Creator: Kutter, Paul E.
Partner: UNT Libraries Government Documents Department
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