EFFECT OF PRETREATMENT ON PT-CO/C CATHODE CATALYSTS FOR THE OXYGEN-REDUCTION REACTION (open access)

EFFECT OF PRETREATMENT ON PT-CO/C CATHODE CATALYSTS FOR THE OXYGEN-REDUCTION REACTION

Carbon supported Pt and Pt-Co electrocatalysts for the oxygen reduction reaction in low temperature fuel cells were prepared by the reduction of the metal salts with sodium borohydride and sodium formate. The effect of surface treatment with nitric acid on the carbon surface and Co on the surface of carbon prior to the deposition of Pt was studied. The catalysts where Pt was deposited on treated carbon the ORR reaction preceded more through the two electron pathway and favored peroxide production, while the fresh carbon catalysts proceeded more through the four electron pathway to complete the oxygen reduction reaction. NaCOOH reduced Pt/C catalysts showed higher activity that NaBH{sub 4} reduced Pt/C catalysts. It was determined that the Co addition has a higher impact on catalyst activity and active surface area when used with NaBH{sub 4} as reducing agent as compared to NaCOOH.
Date: January 19, 2010
Creator: Fox, E. & Colon-Mercado, H.
System: The UNT Digital Library
HCDF: A Hybrid Community Discovery Framework (open access)

HCDF: A Hybrid Community Discovery Framework

None
Date: January 19, 2010
Creator: Henderson, Keith; Eliassi-Rad, Tina; Papadimitriou, Spiros & Faloutsos, Christos
System: The UNT Digital Library
High statistics analysis using anisotropic clover lattices: (III) Baryon-baryon interactions (open access)

High statistics analysis using anisotropic clover lattices: (III) Baryon-baryon interactions

Low-energy baryon-baryon interactions are calculated in a high-statistics lattice QCD study on a single ensemble of anisotropic clover gauge-field configurations at a pion mass of m{sub {pi}} {approx} 390 MeV, a spatial volume of L{sup 3} {approx} (2.5 fm){sup 3}, and a spatial lattice spacing of b {approx} 0.123 fm. Luescher's method is used to extract nucleon-nucleon, hyperon-nucleon and hyperon-hyperon scattering phase shifts at one momentum from the one- and two-baryon ground-state energies in the lattice volume. The isospin-3/2 N{Sigma} interactions are found to be highly spin-dependent, and the interaction in the {sup 3}S{sub 1} channel is found to be strong. In contrast, the N{Lambda} interactions are found to be spin-independent, within the uncertainties of the calculation, consistent with the absence of one-pion-exchange. The only channel for which a negative energy-shift is found is {Lambda}{Lambda}, indicating that the {Lambda}{Lambda} interaction is attractive, as anticipated from model-dependent discussions regarding the H-dibaryon. The NN scattering lengths are found to be small, clearly indicating the absence of any fine-tuning in the NN-sector at this pion mass. This is consistent with our previous Lattice QCD calculation of NN interactions. The behavior of the signal-to-noise ratio in the baryon-baryon correlation functions, and in the ratio …
Date: January 19, 2010
Creator: Beane, S; Detmold, W; Lin, H; Luu, T; Orginos, K; Savage, M et al.
System: The UNT Digital Library
THE POSITIVE IMPACTS OF AMERICAN REINVESTMENT AND RECOVERY ACT (ARRA) FUNDING TO THE WASTE MANAGEMENT PROGRAM ON HANFORD'S PLATEAU REMEDIATION PROJECT (open access)

THE POSITIVE IMPACTS OF AMERICAN REINVESTMENT AND RECOVERY ACT (ARRA) FUNDING TO THE WASTE MANAGEMENT PROGRAM ON HANFORD'S PLATEAU REMEDIATION PROJECT

In April 2009, the Department of Energy (DOE) Richland Operations Office (RL) was allocated $1.6 billion (B) in ARRA funding to be applied to cleanup projects at the Hanford Site. DOE-RL selected projects to receive ARRA funding based on 3-criteria: creating/saving jobs, reducing the footprint of the Hanford Site, and reducing life-cycle costs for cleanup. They further selected projects that were currently covered under regulatory documents and existing prime contracts, which allowed work to proceed quickly. CH2M HILL Plateau Remediation Company (CHPRC) is a prime contractor to the DOE focused on the environmental cleanup of the DOE Hanford Site Central Plateau. CHPRC was slated to receive $1.36B in ARRA funding. As of January, 2010, CHPRC has awarded over $200 million (M) in subcontracts (64% to small businesses), created more that 1,100 jobs, and touched more than 2,300 lives - all in support of long-term objectives for remediation of the Central Plateau, on or ahead of schedule. ARRA funding is being used to accelerate and augment cleanup activities already underway under the baseline Plateau Remediation Contract (PRC). This paper details challenges and accomplishments using ARRA funding to meet DOE-RL objectives of creating/saving jobs, expediting cleanup, and reducing lifecycle costs for cleanup …
Date: January 19, 2010
Creator: LT, BLACKFORD
System: The UNT Digital Library
Search for muon neutrinos from Gamma-Ray Bursts with the IceCube neutrino telescope (open access)

Search for muon neutrinos from Gamma-Ray Bursts with the IceCube neutrino telescope

We present the results of searches for high-energy muon neutrinos from 41 gamma- ray bursts (GRBs) in the northern sky with the IceCube detector in its 22-string con-figuration active in 2007/2008. The searches cover both the prompt and a possible precursor emission as well as a model-independent, wide time window of -1 h to +3 haround each GRB. In contrast to previous searches with a large GRB population, we do not utilize a standard Waxman?Bahcall GRB flux for the prompt emission but calcu- late individual neutrino spectra for all 41 GRBs from the burst parameters measured by satellites. For all three time windows the best estimate for the number of signal events is zero. Therefore, we place 90percent CL upper limits on the fluence from the prompt phase of 3.7 x 10-3 erg cm-2 (72TeV - 6.5 PeV) and on the fluence from the precursor phase of 2.3 x 10-3 erg cm-2 (2.2TeV - 55TeV), where the quoted energy ranges contain 90percent of the expected signal events in the detector. The 90percent CL upper limit for the wide time window is 2.7 x 10-3 erg cm-2 (3TeV - 2.8 PeV) assuming an E-2 flux.
Date: January 19, 2010
Creator: Collaboration, IceCube & Abbasi, R.
System: The UNT Digital Library