Synthesis and Characterization of Cluster-Derived Supported Bimetallic Catalysts (open access)

Synthesis and Characterization of Cluster-Derived Supported Bimetallic Catalysts

New procedures have been developed for synthesizing di- and tri-metallic cluster complexes. The chemical properties of the new complexes have been investigated, particularly toward the activation of molecular hydrogen. These complexes were then converted into bi- and tri-metallic nanoparticles on silica and alumina supports. These nanoparticles were characterized by electron microscopy and were then tested for their ability to produce catalytic hydrogenation of unsaturated hydrocarbons and for the preferential oxidation of CO in the presence of hydrogen. The bi- and tri-metallic nanoparticles exhibited far superior activity and selectivity as hydrogenation catalysts when compared to the individual metallic components. It was found that the addition of tin greatly improved the selectivity of the catalysts for the hydrogenation of polyolefins. The addition of iron improves the catalysts for the selective oxidation of CO by platinum in the presence of hydrogen. The observations should lead to the development of lower cost routes to molecules that can be used to produce polymers and plastics for use by the general public and for procedures to purify hydrogen for use as an alternative energy in the hydrogen economy of the future.
Date: October 10, 2008
Creator: Adams, Richard D & Amiridis, Michael D
Object Type: Report
System: The UNT Digital Library
Spatial distribution of average charge state and deposition rate in high power impulse magnetron sputtering of copper (open access)

Spatial distribution of average charge state and deposition rate in high power impulse magnetron sputtering of copper

The spatial distribution of copper ions and atoms in high power impulse magnetron sputtering (HIPIMS) discharges was determined by (i) measuring the ion current to electrostatic probes and (ii) measuring the film thickness by profilometry. A set of electrostatic and collection probes were placed at different angular positions and distances from the target surface. The angular distribution of the deposition rate and the average charge state of the copper species (including ions and neutrals) were deduced.The discharge showed a distinct transition to a high current mode dominated by copper self-sputtering when the applied voltage exceeded the threshold of 535 V. For a lower voltage, the deposition rate was very low and the average charge state was found to be less than 0.4. For higher voltage (and average power), the absolute deposition rates were much higher, but they were smaller than the corresponding direct current (DC) rates if normalized to the same average power. At the high voltage level, the spatial distribution of the average charge state showed some similarities with the distribution of the magnetic field, suggesting that the generation and motion of copper ions is affected by magnetized electrons. At higher voltage, the average charge state increases with the …
Date: May 10, 2008
Creator: Anders, Andre; Horwat, David & Anders, Andre
Object Type: Article
System: The UNT Digital Library
Measurement of the Branching Fraction, Polarization, and CP Asymmetries in B0->rho0rho0 Decay, and Implications for the CKM Angle alpha (open access)

Measurement of the Branching Fraction, Polarization, and CP Asymmetries in B0->rho0rho0 Decay, and Implications for the CKM Angle alpha

We study B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0} decays in a sample of 465 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} events collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider located at the Stanford Linear Accelerator Center (SLAC). We measure the branching fraction {Beta} = (0.92 {+-} 0.32 {+-} 0.14) x 10{sup -6} and longitudinal polarization fraction f{sub L} = 0.75{sub -0.14}{sup +0.11} {+-} 0.04, where the first uncertainty is statistical and the second is systematic. The evidence for the B{sup 0} {yields} {rho}{sup 0}{rho}{sup 0} signal has a significance of 3.1 standard deviations, including systematic uncertainties. We investigate the proper-time dependence of the longitudinal component in the decay and measure the CP-violating coefficients S{sub L}{sup 00} = (0.3 {+-} 0.7 {+-} 0.2) and C{sub L}{sup 00} = (0.2 {+-} 0.8 {+-} 0.3). They study the implication of these results for the unitarity triangle angle {alpha}.
Date: September 10, 2008
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Measurement of time dependent CP asymmetry parameters in B0 meson decays to omegaKs, etaprimeKz, and pi0Ks (open access)

Measurement of time dependent CP asymmetry parameters in B0 meson decays to omegaKs, etaprimeKz, and pi0Ks

The authors present measurements of the time-dependent CP-violation parameters S and C in the decays B{sup 0} {yields} {omega}K{sub S}{sup 0}, B{sup 0} {yields} {eta}{prime}K{sup 0}, reconstructed as {eta}{prime}K{sub S}{sup 0} and {eta}{prime}K{sub L}{sup 0}, and B{sup 0} {yields} {pi}{sup 0}K{sub S}{sup 0}. The data sample corresponds to the full BABAR dataset of 467 x 10{sup 6} B{bar B} pairs produced at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the Stanford Linear Accelerator Center. The results are S{sub {omega}K{sub S}{sup 0}} = 0.55{sub -0.29}{sup +0.26} {+-} 0.02, C{sub {omega}K{sub S}{sup 0}} = -0.52{sub -0.20}{sup +0.22} {+-} 0.03, S{sub {eta}{prime}K{sup 0}} = 0.57 {+-} 0.08 {+-} 0.02, C{sub {eta}{prime}K{sup 0}} = -0.08 {+-} 0.06 {+-} 0.02, S{sub {pi}{sup 0}K{sub S}{sup 0}} = 0.55 {+-} 0.20 {+-} 0.03, and C{sub {pi}{sup 0}K{sub S}{sup 0}} = 0.13 {+-} 0.13 {+-} 0.03, where the first errors are statistical and the second systematic. These results are consistent with the previous measurements and the world average of sin2{beta} measured in B{sup 0} {yields} J/{psi}K{sub S}{sup 0}.
Date: September 10, 2008
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Walter Reed Army Medical Center (WRAMC) and Office of Management and Budget (OMB) Circular A-76: Implications for the Future (open access)

Walter Reed Army Medical Center (WRAMC) and Office of Management and Budget (OMB) Circular A-76: Implications for the Future

This report examines the issues surrounding the Walter Reed public-private competition conducted under Office of Management and Budget (OMB) Circular A- 76 and its potential impact on future Department of Defense (DOD) competitions.
Date: June 10, 2008
Creator: Bailey Grasso, Valerie
Object Type: Report
System: The UNT Digital Library
Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY (open access)

Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY

Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDHR55M and SDHH57A are relatively insensitive to pH (~;;60 and 200 s-1, respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for …
Date: November 10, 2008
Creator: Bailey, Susan; Rapson, Trevor; Johnson-Winters, Kayunta; Astashkin, Andrei; Enemark, John & Kappler, Ulrike
Object Type: Article
System: The UNT Digital Library
Horse Slaughter Prevention Bills and Issues (open access)

Horse Slaughter Prevention Bills and Issues

This report focuses on horse slaughter prevention bills and issues, and how they are implemented or enforced.
Date: December 10, 2008
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Humane Treatment of Farm Animals: Overview and Issues (open access)

Humane Treatment of Farm Animals: Overview and Issues

None
Date: December 10, 2008
Creator: Becker, Geoffrey S.
Object Type: Report
System: The UNT Digital Library
Final Report for LDRD Project 06-ERD-063 (open access)

Final Report for LDRD Project 06-ERD-063

None
Date: March 10, 2008
Creator: Beller, H R; Chakicherla, A; Coleman, M A; Esser, B K; Kane, S R; Legler, T C et al.
Object Type: Report
System: The UNT Digital Library
Mechanical Devices Readiness FY04.0402.1 (open access)

Mechanical Devices Readiness FY04.0402.1

This Advanced Design and Production Technologies (ADAPT) project funded production process and tooling improvements to meet and sustain rate production for the program mechanism assemblies. Techniques were developed to allow evaluation and rework of sealed mechanisms that will result in prevention of the scrapping of future mechanisms. Future system mechanisms will likely be smaller with tighter tolerance parts that will require improved inspection equipment and techniques. During the latter phase of this project, the ISL (Intent Stronglink) PRT (Product Realization Team) developed designs and manufacturing processes at Sandia and at multiple KCP (Kansas City Plant) vendors, to produce glass ceramic headers to replace the brazed ceramic headers in the ISL. This achievement will result in significant production costs savings (unit cost and product scrap due to leaking headers).
Date: October 10, 2008
Creator: Bender, Thomas R.
Object Type: Report
System: The UNT Digital Library
The NLO Multileg Working Group: Summary Report (open access)

The NLO Multileg Working Group: Summary Report

None
Date: April 10, 2008
Creator: Bern, Z.; Bernicot, C.; Binoth, T.; Boudjema, F.; Britto, R.; Campbell, J. et al.
Object Type: Article
System: The UNT Digital Library
A human breast cell model of pre-invasive to invasive transition (open access)

A human breast cell model of pre-invasive to invasive transition

A crucial step in human breast cancer progression is the acquisition of invasiveness. There is a distinct lack of human cell culture models to study the transition from pre-invasive to invasive phenotype as it may occur 'spontaneously' in vivo. To delineate molecular alterations important for this transition, we isolated human breast epithelial cell lines that showed partial loss of tissue polarity in three-dimensional reconstituted-basement membrane cultures. These cells remained non-invasive; however, unlike their non-malignant counterparts, they exhibited a high propensity to acquire invasiveness through basement membrane in culture. The genomic aberrations and gene expression profiles of the cells in this model showed a high degree of similarity to primary breast tumor profiles. The xenograft tumors formed by the cell lines in three different microenvironments in nude mice displayed metaplastic phenotypes, including squamous and basal characteristics, with invasive cells exhibiting features of higher grade tumors. To find functionally significant changes in transition from pre-invasive to invasive phenotype, we performed attribute profile clustering analysis on the list of genes differentially expressed between pre-invasive and invasive cells. We found integral membrane proteins, transcription factors, kinases, transport molecules, and chemokines to be highly represented. In addition, expression of matrix metalloproteinases MMP-9,-13,-15,-17 was up regulated …
Date: March 10, 2008
Creator: Bissell, Mina J; Rizki, Aylin; Weaver, Valerie M.; Lee, Sun-Young; Rozenberg, Gabriela I.; Chin, Koei et al.
Object Type: Article
System: The UNT Digital Library
Iraq: Oil and Gas Legislation, Revenue Sharing, and U.S. Policy (open access)

Iraq: Oil and Gas Legislation, Revenue Sharing, and U.S. Policy

This report reviews proposed legislation and contracts, analyzes the positions of various Iraqi political actors, and discusses potential implications for U.S. foreign policy goals in Iraq.
Date: December 10, 2008
Creator: Blanchard, Christopher M.
Object Type: Report
System: The UNT Digital Library
Development of ZnO:Ga as an Ultrafast Scintillator (open access)

Development of ZnO:Ga as an Ultrafast Scintillator

We report on several methods for synthesizing the ultra-fast scintillator ZnO(Ga), and measurements of the resulting products. This material has characteristics that make it an excellent alpha detector for tagging the time and direction of individual neutrons produced by t-d and d-d neutron generators (associated particle imaging). The intensity and decay time are strongly dependent on the method used for dopant incorporation. We compare samples made by diffusion of Ga metal to samples made by solid state reaction between ZnO and Ga2O3 followed by reduction in hydrogen. The latter is much more successful and has a pure, strong near-band-edge fluorescence and an ultra-fast decay time of the x-ray-excited luminescence. The luminescence increases dramatically as the temperature is reduced to 10K. We also present results of an alternate low-temperature synthesis that produces luminescent particles with a more uniform size distribution. We examine possible mechanisms for the bright near-band-edge scintillation and favor the explanation that it is due to the recombination of Ga3+ donor electrons with ionization holes trapped on H+ ion acceptors.
Date: December 10, 2008
Creator: Bourret-Courchesne, E. D.; Derenzo, S. E. & Weber, M. J.
Object Type: Article
System: The UNT Digital Library
Immigration Legislation and Issues in the 110th Congress (open access)

Immigration Legislation and Issues in the 110th Congress

This report discusses immigration-related issues that have seen legislative action or are of significant congressional interest.
Date: December 10, 2008
Creator: Bruno, Andorra
Object Type: Report
System: The UNT Digital Library
Free flow electrophoresis separation and AMS quantitation of 14C-naphthalene-protein adducts (open access)

Free flow electrophoresis separation and AMS quantitation of 14C-naphthalene-protein adducts

None
Date: October 10, 2008
Creator: Buchholz, B. A.; Haack, K. W.; Sporty, J. L.; Buckpitt, A. R. & Morin, D.
Object Type: Article
System: The UNT Digital Library
Ballast Water Management to Combat Invasive Species (open access)

Ballast Water Management to Combat Invasive Species

This report provides background on various approaches to ballast water management and reviews current ballast water management laws and programs.
Date: June 10, 2008
Creator: Buck, Eugene H.
Object Type: Report
System: The UNT Digital Library
Ballast Water Management to Combat Invasive Species (open access)

Ballast Water Management to Combat Invasive Species

This report provides background on various approaches to ballast water management and reviews current ballast water management laws and programs.
Date: June 10, 2008
Creator: Buck, Eugene H.
Object Type: Report
System: The UNT Digital Library
VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific (open access)

VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific

The VERtical Transport In the Global Ocean (VERTIGO) study examined particle sources and fluxes through the ocean's 'twilight zone' (defined here as depths below the euphotic zone to 1000 m). Interdisciplinary process studies were conducted at contrasting sites off Hawaii (ALOHA) and in the NW Pacific (K2) during 3 week occupations in 2004 and 2005, respectively. We examine in this overview paper the contrasting physical, chemical and biological settings and how these conditions impact the source characteristics of the sinking material and the transport efficiency through the twilight zone. A major finding in VERTIGO is the considerably lower transfer efficiency (T{sub eff}) of particulate organic carbon (POC), POC flux 500/150 m, at ALOHA (20%) vs. K2 (50%). This efficiency is higher in the diatom-dominated setting at K2 where silica-rich particles dominate the flux at the end of a diatom bloom, and where zooplankton and their pellets are larger. At K2, the drawdown of macronutrients is used to assess export and suggests that shallow remineralization above our 150 m trap is significant, especially for N relative to Si. We explore here also surface export ratios (POC flux/primary production) and possible reasons why this ratio is higher at K2, especially during the …
Date: June 10, 2008
Creator: Buesseler, K. O.; Trull, T. W.; Steinberg, D. K.; Silver, M. W.; Siegel, D. A.; Saitoh, S. I. et al.
Object Type: Article
System: The UNT Digital Library
Abortion Services and Military Medical Facilities (open access)

Abortion Services and Military Medical Facilities

In 1993, President Clinton modified the military policy on providing abortions at military medical facilities. Under the change directed by the President, military medical facilities were allowed to perform abortions if paid for entirely with non-Department of Defense (DOD) funds (i.e., privately funded). Over the last three decades, the availability of abortion services at military medical facilities has been subjected to numerous changes and interpretations.
Date: July 10, 2008
Creator: Burelli, David F.
Object Type: Report
System: The UNT Digital Library
Abortion Services and Military Medical Facilities (open access)

Abortion Services and Military Medical Facilities

The purpose of this report is to describe and discuss the provisions for providing abortion services to military personnel, their dependents, and other military health care beneficiaries at military medical facilities. The report describes the history of these provisions, with particular emphasis on legislative actions. Finally, this report discusses a number of proposals to modify the law, as well as other related legislative and administrative actions.
Date: July 10, 2008
Creator: Burrelli, David F.
Object Type: Report
System: The UNT Digital Library
Food Price Inflation: Causes and Impacts (open access)

Food Price Inflation: Causes and Impacts

This report discusses multiple factors that attribute to rising food prices in the United States of America.
Date: April 10, 2008
Creator: Capehart, Tom & Richardson, Joe
Object Type: Report
System: The UNT Digital Library
Constitutional Issues Relating to Proposals for Foreclosure Moratorium Legislation That Affects Existing Mortgages (open access)

Constitutional Issues Relating to Proposals for Foreclosure Moratorium Legislation That Affects Existing Mortgages

This report begins with an overview of Congress's authority pursuant to the Commerce and Bankruptcy Clauses to pass laws pertaining to foreclosures, and a review of Contract Clause, Substantive Due Process, and Takings Clause jurisprudence.
Date: June 10, 2008
Creator: Carpenter, David H.
Object Type: Report
System: The UNT Digital Library
Financial Institution Insolvency: Federal Authority over Fannie Mae, Freddie Mac, and Depository Institutions (open access)

Financial Institution Insolvency: Federal Authority over Fannie Mae, Freddie Mac, and Depository Institutions

This report provides an overview of the U.S. credit crunch and its effect on Fannie, Freddie, Banks, and Thrifts. The report discusses the Federal Deposit Insurance Corporation (FDIC) and insolvent banks and thrifts.
Date: September 10, 2008
Creator: Carpenter, David H. & Murphy, M. M.
Object Type: Report
System: The UNT Digital Library