2010 GORDON RESEARCH CONFERENCE ON MITOCHONDRIA & CHLOROPLASTS, LUCCA, ITALY, JULY 11-16, 2010 (open access)

2010 GORDON RESEARCH CONFERENCE ON MITOCHONDRIA & CHLOROPLASTS, LUCCA, ITALY, JULY 11-16, 2010

The 2010 GRC on Mitochondria & Chloroplasts will assemble an international group of molecular, structural and cellular biologists, biochemists and geneticists investigating a broad spectrum of fundamental problems related to the biology of these organelles in animal, plant and fungal cells. This field has witnessed an extraordinary expansion in recent years, fueled by the discovery of the role of mitochondria in human disease and ageing, and of the synergy of chloroplasts and mitochondria in energetic output, the identification of novel factors involved in organelle division, movement, signaling and acclimation to changing environmental conditions, and by the powerful tools of organelle proteomics. The 2010 GRC will highlight advances in the elucidation of molecular mechanisms of organelle biogenesis including regulation of genome structure, evolution and expression, organellar protein import, assembly and turnover of respiratory and photosynthetic complexes, bidirectional signaling between organelles and nucleus, organelle morphology and dynamics, and the integration of cellular metabolism. We will also explore progress in mechanisms of disease and ageing/ senescence in animals and plants. The organellar field has forged new fronts toward a global and comprehensive understanding of mitochondrial and chloroplast biology at the molecular level. Many of the molecules under study in model organisms are responsible …
Date: July 16, 2010
Creator: Barkan, Alice
Object Type: Article
System: The UNT Digital Library
Abstraction of Information From 2-  and 3-Dimensional Porflow Models Into a 1-D Goldsim Model - 11404 (open access)

Abstraction of Information From 2- and 3-Dimensional Porflow Models Into a 1-D Goldsim Model - 11404

The Savannah River National Laboratory has developed a 'hybrid' approach to Performance Assessment modeling which has been used for a number of Performance Assessments. This hybrid approach uses a multi-dimensional modeling platform (PorFlow) to develop deterministic flow fields and perform contaminant transport. The GoldSim modeling platform is used to develop the Sensitivity and Uncertainty analyses. Because these codes are performing complementary tasks, it is incumbent upon them that for the deterministic cases they produce very similar results. This paper discusses two very different waste forms, one with no engineered barriers and one with engineered barriers, each of which present different challenges to the abstraction of data. The hybrid approach to Performance Assessment modeling used at the SRNL uses a 2-D unsaturated zone (UZ) and a 3-D saturated zone (SZ) model in the PorFlow modeling platform. The UZ model consists of the waste zone and the unsaturated zoned between the waste zone and the water table. The SZ model consists of source cells beneath the waste form to the points of interest. Both models contain 'buffer' cells so that modeling domain boundaries do not adversely affect the calculation. The information pipeline between the two models is the contaminant flux. The domain …
Date: November 16, 2010
Creator: Taylor, G. & Hiergesell, R.
Object Type: Article
System: The UNT Digital Library
Activation Layer Stabilization of High Polarization Photocathodes in Sub-Optimal RF Gun Environments (open access)

Activation Layer Stabilization of High Polarization Photocathodes in Sub-Optimal RF Gun Environments

Specific activation recipes for bulk, 100 nm thick MBE grown and high polarization III-V photocathode material have been developed which mitigate the effects of exposure to background gasses. Lifetime data using four representative gasses were acquired for bulk GaAs, 100 nm unstrained GaAs and strained superlattice GaAs/GaAsP, all activated both with Cs and then Cs and Li (bi-alkali). Each photoemitter showed marked resilience improvement when activated using the bi-alkali recipe compared to the standard single alkali recipe. A dual alkali activation system at SLAC was constructed, baked and commissioned with the purpose of performing spin-polarization measurements on electrons emitted from the bi-alkali activated surfaces. An end station at SSRL was configured with the required sources for energy resolved photoemission measurements on the bi-alkali activated and CO2 dosed surfaces. The bi-alkali recipes were successfully implemented at SLAC/SSRL. Measurements at SLAC of the photoelectron spin-polarization from the modified activation surface showed no sign of a change in value compared to the standard activated material, i.e., no ill effects. Analysis of photoemission data indicates that the addition of Li to the activation layer results in a multi-layer structure. The presence of Li in the activation layer also acts as an inhibitor to CO2 …
Date: November 16, 2010
Creator: Mulhollan, Gregory A.
Object Type: Report
System: The UNT Digital Library
Adaptive and Efficient Computing for Subsurface Simulation within ParFlow (open access)

Adaptive and Efficient Computing for Subsurface Simulation within ParFlow

This project is concerned with the PF.WRF model as a means to enable more accurate predictions of wind fluctuations and subsurface storage. As developed at LLNL, PF.WRF couples a groundwater (subsurface) and surface water flow model (ParFlow) to a mesoscale atmospheric model (WRF, Weather Research and Forecasting Model). It was developed as a unique tool to address coupled water balance and wind energy questions that occur across traditionally separated research regimes of the atmosphere, land surface, and subsurface. PF.WRF is capable of simulating fluid, mass, and energy transport processes in groundwater, vadose zone, root zone, and land surface systems, including overland flow, and allows for the WRF model to both directly drive and respond to surface and subsurface hydrologic processes and conditions. The current PF.WRF model is constrained to have uniform spatial gridding below the land surface and matching areal grids with the WRF model at the land surface. There are often cases where it is advantageous for land surface, overland flow and subsurface models to have finer gridding than their atmospheric counterparts. Finer vertical discretization is also advantageous near the land surface (to properly capture feedbacks) yet many applications have a large vertical extent. However, the surface flow is …
Date: November 16, 2010
Creator: Tiedeman, H & Woodward, C S
Object Type: Report
System: The UNT Digital Library
Advanced Compton scattering light source R&D at LLNL (open access)

Advanced Compton scattering light source R&D at LLNL

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to typical 4th generation synchrotrons. Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable Mono-Energetic Gamma-Ray (MEGa-Ray) light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A new precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. Based on the success of the previous Thomson-Radiated Extreme X-rays (T-REX) Compton scattering source at LLNL, the source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include …
Date: February 16, 2010
Creator: Albert, F.; Anderson, S. G.; Anderson, G.; Betts, S. M.; Chu, T. S.; Gibson, D. J. et al.
Object Type: Article
System: The UNT Digital Library
THE AFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM (open access)

THE AFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM

In this present work, the affects of different transition metal halides (TiCl{sub 3}, VCl{sub 3}, ScCl{sub 3} and NiCl{sub 2}) on the sorption properties of the 1:1 molar ratio of LiNH{sub 2} to MgH{sub 2} are investigated. The modified mixtures were found to contain LiNH{sub 2}, MgH{sub 2} and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl{sub 3}>ScCl{sub 3}>VCl{sub 3}>NiCl{sub 2}. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. XRD and Raman spectroscopy identified the cycled material to be composed of LiH, MgH{sub 2}, Mg(NH{sub 2}){sub 2} and Mg{sub 3}N{sub 2}.
Date: December 16, 2010
Creator: Erdy, C.; Gray, J.; Lascola, R. & Anton, D.
Object Type: Article
System: The UNT Digital Library
eGY-Africa: Addressing the Digital Divide for Science in Africa (open access)

eGY-Africa: Addressing the Digital Divide for Science in Africa

Adoption of information and communication technologies and access to the Internet is expanding in Africa, but because of the rapid growth elsewhere, a Digital Divide between Africa and the rest of the world exists, and the gap is growing. In many sub-Saharan African countries, education and research sector suffers some of the worst deficiencies in access to the Internet, despite progress in development of NRENs - National Research and Education (cyber) Networks. By contrast, it is widely acknowledged in policy statements from the African Union, the UN, and others that strength in this very sector provides the key to meeting and sustaining Millennium Development Goals. Developed countries with effective cyber-capabilities proclaim the benefits to rich and poor alike arising from the Information Revolution. This is but a dream for many scientists in African institutions. As the world of science becomes increasingly Internet-dependent, so they become increasingly isolated. eGY-Africa is a bottom-up initiative by African scientists and their collaborators to try to reduce this Digital Divide by a campaign of advocacy for better institutional facilities. Four approaches are being taken. The present status of Internet services, problems, and plans are being mapped via a combination of direct measurement of Internet performance …
Date: June 16, 2010
Creator: Barton, C. E.; Amory-Mazaudier, C.; Barry, B.; Chukwuma; Cottrell, R. L.; Kalim, U. et al.
Object Type: Article
System: The UNT Digital Library
Applications of Photonuclear Physics for International Safeguards and Security (open access)

Applications of Photonuclear Physics for International Safeguards and Security

Studies of nuclear resonance fluorescence based applications are presented. Important for these applications are data for isotopes such as {sup 239}Pu. Nuclear resonance fluorescence measurements of {sup 239}Pu were performed at the free electron laser facility at UC Santa Barbara using photons from a bremsstrahlung beam with an endpoint energies between 4.0 MeV and 5.5 MeV. Though no discrete states with significant confidence level were measured, we have excluded the region above 27(3) eV-barns, or 4-sigma, where we would expect only a small chance of false positives. Details of the measurements and the results are presented here.
Date: April 16, 2010
Creator: Johnson, M. S.; Hall, J. M.; McNabb, D. P.; McFarland, J.; Norman, E.; Bertozzi, W. et al.
Object Type: Article
System: The UNT Digital Library
Assessment of the 3410 Building Filtered Exhaust Stack Sampling Probe Location (open access)

Assessment of the 3410 Building Filtered Exhaust Stack Sampling Probe Location

Pacific Northwest National Laboratory performed several tests in the exhaust air discharge from the new 3410 Building Filtered Exhaust Stack to determine whether the air sampling probe for emissions monitoring for radionuclides is acceptable. The method followed involved adopting the results of a previously performed test series from a system with a similar configuration, followed by several tests on the actual system to verify the applicability of the previously performed tests. The qualification criteria for these types of stacks include metrics concerning 1) uniformity of air velocity, 2) sufficiently small flow angle with respect to the axis of the duct, 3) uniformity of tracer gas concentration, and 4) uniformity tracer particle concentration.
Date: July 16, 2010
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
Assessment of the 3420 Building Filtered Exhaust Stack Sampling Probe Location (open access)

Assessment of the 3420 Building Filtered Exhaust Stack Sampling Probe Location

Pacific Northwest National Laboratory performed several tests in the exhaust air discharge from the new 3420 Building Filtered Exhaust Stack to determine whether the air sampling probe for emissions monitoring for radionuclides is acceptable. The method followed involved adopting the results of a previously performed test series from a system with a similar configuration, followed by several tests on the actual system to verify the applicability of the previously performed tests. The qualification criteria for these types of stacks include metrics concerning 1) uniformity of air velocity, 2) sufficiently small flow angle with respect to the axis of the duct, 3) uniformity of tracer gas concentration, and 4) uniformity tracer particle concentration.
Date: July 16, 2010
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
Assessment of the 3430 Building Filtered Exhaust Stack Sampling Probe Location (open access)

Assessment of the 3430 Building Filtered Exhaust Stack Sampling Probe Location

Pacific Northwest National Laboratory performed a demonstration to determine the acceptable location in which to place an air sampling probe for emissions monitoring for radionuclides in the exhaust air discharge from the new 3430 Building Filtered Exhaust Stack. The method was to adopt the results of a previously performed test series for a system of similar configuration, followed by a partial test on the actual system to verify the applicability of previously performed tests. The qualification criteria included 1) a uniform air velocity, 2) an average flow angle that does not deviate from the axis of the duct by more than 20°, 3) a uniform concentration of tracer gases, and 4) a uniform concentration of tracer particles. Section 1 provides background information for the demonstration, and Section 2 describes the test strategy, including the criteria for the applicability of model results and the test matrix. Section 3 describes the flow -angle test and the velocity uniformity test, Section 4 provides the test results, and Section 5 provides the conclusions. Appendix A includes the test data sheets, and Appendix B gives applicable qualification results from the previously tested model stack. The data from the previously tested and similarly designed stack was …
Date: July 16, 2010
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
Assessment of the Proposed INTEC CPP 666 Stack Monitoring Site for Compliance with ANSI/HPS N13.1 1999 (open access)

Assessment of the Proposed INTEC CPP 666 Stack Monitoring Site for Compliance with ANSI/HPS N13.1 1999

This document reports on a series of tests to determine whether the proposed new location for air sampling probes in the CPP-666 heating, ventilation and air conditioning (HVAC) exhaust duct would meet the applicable regulatory criteria regarding the placement of an air sampling probe. Federal regulations( ) require that a sampling probe be located in the exhaust stack according to the criteria of the American National Standards Institute/Health Physical Society (ANSI/HPS) N13.1-1999, Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stack and Ducts of Nuclear Facilities. These criteria address the capability of the sampling probe to extract a sample that is representative of the effluent stream.
Date: February 16, 2010
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
Background Radiation Survey of the Radiological/Nuclear Countermeasures Test and Evaluation Center (open access)

Background Radiation Survey of the Radiological/Nuclear Countermeasures Test and Evaluation Center

In preparation for operations at the Radiological/Nuclear Countermeasures Test and Evaluation Complex (Rad/NucCTEC), the Department of Homeland Security Domestic Nuclear Detection Office (DHS/DNDO) requested that personnel from the Remote Sensing Laboratory (RSL) conduct a survey of the present radiological conditions at the facility. The measurements consist of the exposure rate from a high-pressure ion chamber (HPIC), high-resolution spectra from a high-purity germanium (HPGe) system in an in situ configuration, and low-resolution spectra from a sodium iodide (NaI) detector in a radiation detection backpack. Measurements with these systems were collected at discrete locations within the facility. Measurements were also collected by carrying the VECTOR backpack throughout the complex to generate a map of the entire area. The area was also to be surveyed with the Kiwi (an array of eight-2-inch x 4-inch x 16-inch NaI detectors) from the Aerial Measuring Systems; however, conflicts with test preparation activities at the site prevented this from being accomplished.
Date: September 16, 2010
Creator: Okada, Colin
Object Type: Report
System: The UNT Digital Library
Band Collapse and the Quantum Hall Effect in Graphene (open access)

Band Collapse and the Quantum Hall Effect in Graphene

The recent Quantum Hall experiments in graphene have confirmed the theoretically well-understood picture of the quantum Hall (QH) conductance in fermion systems with continuum Dirac spectrum. In this paper we take into account the lattice, and perform an exact diagonalization of the Landau problem on the hexagonal lattice. At very large magnetic fields the Dirac argument fails completely and the Hall conductance, given by the number of edge states present in the gaps of the spectrum, is dominated by lattice effects. As the field is lowered, the experimentally observed situation is recovered through a phenomenon which we call band collapse. As a corollary, for low magnetic field, graphene will exhibit two qualitatively different QHE's: at low filling, the QHE will be dominated by the 'relativistic' Dirac spectrum and the Hall conductance will be odd-integer; above a certain filling, the QHE will be dominated by a non-relativistic spectrum, and the Hall conductance will span all integers, even and odd.
Date: March 16, 2010
Creator: Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.; Chen, Han-Dong; /Illinois U., Urbana et al.
Object Type: Article
System: The UNT Digital Library
Broadband Infrared Heterodyne Spectrometer: Final Report (open access)

Broadband Infrared Heterodyne Spectrometer: Final Report

This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.
Date: December 16, 2010
Creator: Stevens, C G; Cunningham, C T & Tringe, J W
Object Type: Report
System: The UNT Digital Library
Bulk Data Movement for Climate Dataset: Efficient Data Transfer Management with Dynamic Transfer Adjustment (open access)

Bulk Data Movement for Climate Dataset: Efficient Data Transfer Management with Dynamic Transfer Adjustment

Many scientific applications and experiments, such as high energy and nuclear physics, astrophysics, climate observation and modeling, combustion, nano-scale material sciences, and computational biology, generate extreme volumes of data with a large number of files. These data sources are distributed among national and international data repositories, and are shared by large numbers of geographically distributed scientists. A large portion of data is frequently accessed, and a large volume of data is moved from one place to another for analysis and storage. One challenging issue in such efforts is the limited network capacity for moving large datasets to explore and manage. The Bulk Data Mover (BDM), a data transfer management tool in the Earth System Grid (ESG) community, has been managing the massive dataset transfers efficiently with the pre-configured transfer properties in the environment where the network bandwidth is limited. Dynamic transfer adjustment was studied to enhance the BDM to handle significant end-to-end performance changes in the dynamic network environment as well as to control the data transfers for the desired transfer performance. We describe the results from the BDM transfer management for the climate datasets. We also describe the transfer estimation model and results from the dynamic transfer adjustment.
Date: July 16, 2010
Creator: Sim, Alexander; Balman, Mehmet; Williams, Dean; Shoshani, Arie & Natarajan, Vijaya
Object Type: Report
System: The UNT Digital Library
Capture and Sequestration of CO2 at the Boise White Paper Mill (open access)

Capture and Sequestration of CO2 at the Boise White Paper Mill

This report documents the efforts taken to develop a preliminary design for the first commercial-scale CO2 capture and sequestration (CCS) project associated with biomass power integrated into a pulp and paper operation. The Boise Wallula paper mill is located near the township of Wallula in Southeastern Washington State. Infrastructure at the paper mill will be upgraded such that current steam needs and a significant portion of the current mill electric power are supplied from a 100% biomass power source. A new biomass power system will be constructed with an integrated amine-based CO2 capture plant to capture approximately 550,000 tons of CO2 per year for geologic sequestration. A customized version of Fluor Corporation’s Econamine Plus™ carbon capture technology will be designed to accommodate the specific chemical composition of exhaust gases from the biomass boiler. Due to the use of biomass for fuel, employing CCS technology represents a unique opportunity to generate a net negative carbon emissions footprint, which on an equivalent emissions reduction basis is 1.8X greater than from equivalent fossil fuel sources (SPATH and MANN, 2004). Furthermore, the proposed project will offset a significant amount of current natural gas use at the mill, equating to an additional 200,000 tons of …
Date: June 16, 2010
Creator: McGrail, B. P.; Freeman, C. J.; Beeman, G. H.; Sullivan, E. C.; Wurstner, S. K.; Brown, C. F. et al.
Object Type: Report
System: The UNT Digital Library
Carbon Capture and Sequestration (via Enhanced Oil Recovery) from a Hydrogen Production Facility in an Oil Refinery (open access)

Carbon Capture and Sequestration (via Enhanced Oil Recovery) from a Hydrogen Production Facility in an Oil Refinery

The project proposed a commercial demonstration of advanced technologies that would capture and sequester CO2 emissions from an existing hydrogen production facility in an oil refinery into underground formations in combination with Enhanced Oil Recovery (EOR). The project is led by Praxair, Inc., with other project participants: BP Products North America Inc., Denbury Onshore, LLC (Denbury), and Gulf Coast Carbon Center (GCCC) at the Bureau of Economic Geology of The University of Texas at Austin. The project is located at the BP Refinery at Texas City, Texas. Praxair owns and operates a large hydrogen production facility within the refinery. As part of the project, Praxair would construct a CO2 capture and compression facility. The project aimed at demonstrating a novel vacuum pressure swing adsorption (VPSA) based technology to remove CO2 from the Steam Methane Reformers (SMR) process gas. The captured CO2 would be purified using refrigerated partial condensation separation (i.e., cold box). Denbury would purchase the CO2 from the project and inject the CO2 as part of its independent commercial EOR projects. The Gulf Coast Carbon Center at the Bureau of Economic Geology, a unit of University of Texas at Austin, would manage the research monitoring, verification and accounting (MVA) …
Date: June 16, 2010
Creator: Mehlman, Stewart
Object Type: Report
System: The UNT Digital Library
Charmed Hadron Physics at BABAR (open access)

Charmed Hadron Physics at BABAR

We present a study of the D{sup +}{pi}{sup -}, D{sup 0}{pi}{sup +}, and D*{sup +}{pi}{sup -} systems in inclusive e{sup +}e{sup -} {yields} c{bar c} interactions in a search for new excited D meson states. We use a dataset, consisting of {approx}454 fb{sup -1}, collected at center-of-mass energies near 10.58 GeV by the BABAR detector at the SLAC PEP-II asymmetric-energy collider. We observe, for the first time, candidates for the radial excitations of the D{sup 0}, D*{sup 0}, and D*{sup +}, as well as the L = 2 excited states of the D{sup 0} and D{sup +}, where L is the orbital angular momentum of the quarks.
Date: December 16, 2010
Creator: Benitez, Jose
Object Type: Article
System: The UNT Digital Library
Commercial Buildings Partnership Projects - Metered Data Format and Delivery (open access)

Commercial Buildings Partnership Projects - Metered Data Format and Delivery

A number of the Commercial Building Partnership Projects (CBPs) will require metering, monitoring, data analysis and verification of savings after the retrofits are complete. Although monitoring and verification (M&V) agents are free to use any metering and monitoring devices that they chose, the data they collect should be reported to Pacific Northwest National Laboratory (PNNL) in a standard format. PNNL will store the data collected in its CBP database for further use by PNNL and U.S. Department of Energy. This document describes the data storage process and the deliver format of the data from the M&V agents.
Date: November 16, 2010
Creator: Katipamula, Srinivas
Object Type: Report
System: The UNT Digital Library
Comparison of EXAFS Foil Spectra from Around the World (open access)

Comparison of EXAFS Foil Spectra from Around the World

The EXAFS spectra of Cu and Pd foil from many different beamlines and synchrotrons are compared to address the dependence of the amplitude reduction factor (S{sub 0}{sup 2}) on beamline specific parameters. Even though S{sub 0}{sup 2} is the same parameter as the EXAFS coordination number, the value for S{sub 0}{sup 2} is given little attention, and is often unreported. The S{sub 0}{sup 2} often differs for the same material due to beamline and sample attributes, such that no importance is given to S{sub 0}{sup 2}-values within a general range of 0.7 to 1.1. EXAFS beamlines have evolved such that it should now be feasible to use standard S{sub 0}{sup 2} values for all EXAFS measurements of a specific elemental environment. This would allow for the determination of the imaginary energy (Ei) to account for broadening of the EXAFS signal rather than folding these errors into an effective S{sub 0}{sup 2}-value. To test this concept, we model 11 Cu-foil and 6 Pd-foil EXAFS spectra from around the world to compare the difference in S{sub 0}{sup 2}- and Ei-values.
Date: July 16, 2010
Creator: Kelly, S. D.; Bare, S. R.; Greenlay, N.; Azevedo, G.; Balasubramanian, M.; Barton, D. et al.
Object Type: Article
System: The UNT Digital Library
Comparison of Leading Parallel NAS File Systems on Commodity Hardware (open access)

Comparison of Leading Parallel NAS File Systems on Commodity Hardware

None
Date: September 16, 2010
Creator: Fitzgerald, K; Gary, M; Hedges, R M & Stearman, D M
Object Type: Article
System: The UNT Digital Library
Comparison of the oxidation state of Fe in comet 81P/Wild 2 and chondritic-porous interplanetary dust particles (open access)

Comparison of the oxidation state of Fe in comet 81P/Wild 2 and chondritic-porous interplanetary dust particles

The fragile structure of chondritic-porous interplanetary dust particles (CP-IDPs) and their minimal parent-body alteration have led researchers to believe these particles originate in comets rather than asteroids where aqueous and thermal alterations have occurred. The solar elemental abundances and atmospheric entry speed of CP-IDPs also suggest a cometary origin. With the return of the Stardust samples from Jupiter-family comet 81P/Wild 2, this hypothesis can be tested. We have measured the Fe oxidation state of 15 CP-IDPs and 194 Stardust fragments using a synchrotron-based x-ray microprobe. We analyzed {approx}300 ng of Wild 2 material - three orders of magnitude more material than other analyses comparing Wild 2 and CP-IDPs. The Fe oxidation state of these two samples of material are > 2{sigma} different: the CP-IDPs are more oxidized than the Wild 2 grains. We conclude that comet Wild 2 contains material that formed at a lower oxygen fugacity than the parent-body, or parent bodies, of CP-IDPs. If all Jupiter-family comets are similar, they do not appear to be consistent with the origin of CP-IDPs. However, comets that formed from a different mix of nebular material and are more oxidized than Wild 2 could be the source of CP-IDPs.
Date: July 16, 2010
Creator: Ogliore, Ryan C.; Butterworth, Anna L.; Fakra, Sirine C.; Gainsforth, Zack; Marcus, Matthew A. & Westphal, Andrew J.
Object Type: Article
System: The UNT Digital Library
A Comparison of Two Thermal Insulation and Structural Materials for Use in Type B Packagings (open access)

A Comparison of Two Thermal Insulation and Structural Materials for Use in Type B Packagings

This paper presents the summary of design features and test results of two Type B Shipping Package prototype configurations comprising different insulating materials developed by the Savannah River National Laboratory (SRNL) for the Department of Energy. The materials evaluated, a closed-cell polyurethane foam and a vacuformed ceramic fiber material, were selected to provide adequate structural protection to the package containment vessel during Normal Conditions of Transport (NCT) and Hypothetical Accident Condition (HAC) events and to provide thermal protection during the HAC fire. Polyurethane foam has been used in shipping package designs for many years because of the stiffness it provides to the structure and because of the thermal protection it provides during fire scenarios. This comparison describes how ceramic fiber material offers an alternative to the polyurethane foam in a specific overpack design. Because of the high operating temperature ({approx}2,300 F) of the ceramic material, it allows for contents with higher heat loads to be shipped than is possible with polyurethane foam. Methods of manufacturing and design considerations using the two materials will be addressed.
Date: July 16, 2010
Creator: Blanton, P. & Eberl, K.
Object Type: Article
System: The UNT Digital Library