Laser-induced Ramp Compression of Tantalum and Iron to Over 300 GPa: EOS and X-ray Diffraction (open access)

Laser-induced Ramp Compression of Tantalum and Iron to Over 300 GPa: EOS and X-ray Diffraction

None
Date: January 26, 2010
Creator: Eggert, J. H.; Bastea, M.; Braun, D.; Fujino, D.; Rygg, R.; Smith, R. et al.
Object Type: Article
System: The UNT Digital Library
Computational Investigation of FeS2 Surfaces and Prediction of Effects of Sulfur Environment on Stabilities (open access)

Computational Investigation of FeS2 Surfaces and Prediction of Effects of Sulfur Environment on Stabilities

Density functional theory calculations were employed to investigate the (001), (210), (III), and (110) surfaces of, F~S2' The surface free ene:gies were calculated in equilibrium with a sulfur environment using firstpnnclples based thermodynamics approach. Surfaces that feature metal atoms in their outermost layer are predicted to be higher m energy. Wlthm the studied subset of (I x I) terminations, the stoichiometric (001) surface termmated by a layer of sulfur atoms is the most stable for sulfur-lean condition. For increasingly sulfur-nch enVIronment, two structures were found to have notably lower surface energies compared to others. They have (210) and (Ill) orientation, both terminated by layers of sulfur. Interestingly, these surfaces are nonstoichiometric exhibiting an excess of sulfur atoms.
Date: January 1, 2010
Creator: Alfonso, D. R.
Object Type: Article
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
Object Type: Article
System: The UNT Digital Library
Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site (open access)

Performace of Multi-Probe Corrosion Monitoring Systems at the Hanford Site

Between 2007 and 2009, several different multi-probe corrosion monitoring systems were designed and installed in high-level nuclear waste tanks at the U.S. Department of Energy's Hanford Site in WaShington State. The probe systems are being monitored to ensure waste tanks operate in regions that minimize localized corrosion (i.e., pitting) and stress corrosion cracking. The corrosion monitoring systems have been installed in wastes with different chemistry types. An ongoing effort during the same time period has generated non-radioactive simulants that are tested in the laboratory to establish baseline corrosion monitoring system performance and characterize data to allow interpretation of readings from the multiple corrosion monitoring systems. Data collection from these monitoring systems has reached the point where the results allow comparison with the laboratory testing. This paper presents analytical results from the corrosion monitoring system development program.
Date: January 14, 2010
Creator: Carothers, K. D.; Boomer, K. D.; Anda, V. S.; Dahl, M. M. & Edgemon, G. L.
Object Type: Article
System: The UNT Digital Library
Mapping swamp timothy (Cripsis schenoides) seed productivity using spectral values and vegetation indices in managed wetlands (open access)

Mapping swamp timothy (Cripsis schenoides) seed productivity using spectral values and vegetation indices in managed wetlands

This work examines the potential to predict the seed productivity of a key wetland plant species using spectral reflectance values and spectral vegetation indices. Specifically, the seed productivity of swamp timothy (Cripsis schenoides) was investigated in two wetland ponds, managed for waterfowl habitat, in California's San Joaquin Valley. Spectral reflectance values were obtained and associated spectral vegetation indices (SVI) calculated from two sets of high resolution aerial images (May 11, 2006 and June 9, 2006) and were compared to the collected vegetation data. Vegetation data were collected and analyzed from 156 plots for total aboveground biomass, total aboveground swamp timothy biomass, and total swamp timothy seed biomass. The SVI investigated included the Simple Ratio (SR), Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), Transformed Soil Adjusted Vegetation Index (TSAVI), Modified Soil Adjusted Vegetation Index (MSAVI), and Global Environment Monitoring Index (GEMI). We evaluated the correlation of the various SVI with in situ vegetation measurements for linear, quadratic, exponential and power functions. In all cases, the June image provided better predictive capacity relative to May, a result that underscores the importance of timing imagery to coincide with more favorable vegetation maturity. The north pond with the June image using …
Date: January 15, 2010
Creator: Rahilly, Patrick; Li, Donghai; Guo, Qinghua; Zhu, Jinxia; Ortega, Ricardo; Quinn, Nigel W. T. et al.
Object Type: Article
System: The UNT Digital Library
Interferometric adaptive optics for the National Ignition Facility (open access)

Interferometric adaptive optics for the National Ignition Facility

None
Date: January 14, 2010
Creator: Baker, K.; Homoelle, D.; Stappaerts, E.; Siders, C. & Barty, C.
Object Type: Article
System: The UNT Digital Library
Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles (open access)

Site Determination and Magnetism of Mn Doping in Protein Encapsulated Iron Oxide Nanoparticles

Soft-X-ray absorption spectroscopy, soft-X-ray magnetic circular dichroism, and alternating current magnetic susceptibility were performed on 6.7 nm iron oxide nanoparticles doped with (5-33%) Mn grown inside the horse-spleen ferritin protein cages and compared to similarly protein encapsulated pure Fe-oxide and Mn-oxide nanoparticles to determine the site of the Mn dopant and to quantify the magnetic behavior with varying Mn concentration. The Mn dopant is shown to substitute preferentially as Mn{sup +2} and prefers the octahedral site in the defected spinel structure. The Mn multiplet structure for the nanoparticles is simpler than for the bulk standards, suggesting that the nanoparticle lattices are relaxed from the distortions present in the bulk. Addition of Mn is found to alter the host Fe-oxide lattice from a defected ferrimagnetic spinel structure similar to {gamma}-Fe{sub 2}O{sub 3} to an non-ferromagnetic spinel structure with a local Fe environment similar to Fe{sub 3}O{sub 4}.
Date: January 11, 2010
Creator: Pool, V.; Klem, M.; Jolley, C.; Arenholz, E. A.; Douglas, T.; Young, M. et al.
Object Type: Article
System: The UNT Digital Library
New Natural Gas Storage and Transportation Capabilities Utilizing Rapid Methane Hydrate Formation Techniques (open access)

New Natural Gas Storage and Transportation Capabilities Utilizing Rapid Methane Hydrate Formation Techniques

Natural gas (methane as the major component) is a vital fossil fuel for the United States and around the world. One of the problems with some of this natural gas is that it is in remote areas where there is little or no local use for the gas. Nearly 50 percent worldwide natural gas reserves of ~6,254.4 trillion ft3 (tcf) is considered as stranded gas, with 36 percent or ~86 tcf of the U.S natural gas reserves totaling ~239 tcf, as stranded gas [1] [2]. The worldwide total does not include the new estimates by U.S. Geological Survey of 1,669 tcf of natural gas north of the Arctic Circle, [3] and the U.S. ~200,000 tcf of natural gas or methane hydrates, most of which are stranded gas reserves. Domestically and globally there is a need for newer and more economic storage, transportation and processing capabilities to deliver the natural gas to markets. In order to bring this resource to market, one of several expensive methods must be used: 1. Construction and operation of a natural gas pipeline 2. Construction of a storage and compression facility to compress the natural gas (CNG) at 3,000 to 3,600 psi, increasing its energy density …
Date: January 1, 2010
Creator: Brown, T. D.; Taylor, C. E. & Bernardo, M.
Object Type: Article
System: The UNT Digital Library
Rapid Gas Hydrate Formation Processes: Will They Work? (open access)

Rapid Gas Hydrate Formation Processes: Will They Work?

Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with instrumentation to study rapid and continuous hydrate formation. The cells ranged in size from 100 mL for screening studies to proof-of-concept studies with NETL’s 15-Liter Hydrate Cell. Results from this work demonstrate that the rapid and continuous formation of methane hydrate is possible at predetermined temperatures and pressures within the stability zone of a Methane Hydrate Stability Curve (see Figure 1).
Date: January 1, 2010
Creator: Brown, T. D.; Taylor, C. E. & Bernardo, M. P.
Object Type: Article
System: The UNT Digital Library
Information technology and decision support tools for stakeholder-driven river basin salinity management (open access)

Information technology and decision support tools for stakeholder-driven river basin salinity management

Innovative strategies for effective basin-scale salinity management have been developed in the Hunter River Basin of Australia and more recently in the San Joaquin River Basin of California. In both instances web-based stakeholder information dissemination has been a key to achieving a high level of stakeholder involvement and the formulation of effective decision support salinity management tools. A common element to implementation of salinity management strategies in both river basins has been the concept of river assimilative capacity for controlling export salt loading and the potential for trading of the right to discharge salt load to the river - the Hunter River in Australia and the San Joaquin River in California. Both rivers provide basin drainage and the means of exporting salt to the ocean. The paper compares and contrasts the use of monitoring, modeling and information dissemination in the two basins to achieve environmental compliance and sustain irrigated agriculture in an equitable and socially and politically acceptable manner.
Date: January 1, 2010
Creator: Quinn, Nigel W. T.; Cozad, Daniel B. & Lee, Gene
Object Type: Article
System: The UNT Digital Library
Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat (open access)

Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and …
Date: January 12, 2010
Creator: Hadley, Odelle L.; C.E., Corrigan; T. W., Kirchstetter; Cliff, S. S. & Ramanathan, V.
Object Type: Article
System: The UNT Digital Library
Anticipating the unintended consequences of security dynamics. (open access)

Anticipating the unintended consequences of security dynamics.

In a globalized world, dramatic changes within any one nation causes ripple or even tsunamic effects within neighbor nations and nations geographically far removed. Multinational interventions to prevent or mitigate detrimental changes can easily cause secondary unintended consequences more detrimental and enduring than the feared change instigating the intervention. This LDRD research developed the foundations for a flexible geopolitical and socioeconomic simulation capability that focuses on the dynamic national security implications of natural and man-made trauma for a nation-state and the states linked to it through trade or treaty. The model developed contains a database for simulating all 229 recognized nation-states and sovereignties with the detail of 30 economic sectors including consumers and natural resources. The model explicitly simulates the interactions among the countries and their governments. Decisions among governments and populations is based on expectation formation. In the simulation model, failed expectations are used as a key metric for tension across states, among ethnic groups, and between population factions. This document provides the foundational documentation for the model.
Date: January 1, 2010
Creator: Backus, George A.; Overfelt, James Robert; Malczynski, Leonard A.; Saltiel, David H. & Moulton, Simon Paul
Object Type: Report
System: The UNT Digital Library
On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone (open access)

On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the …
Date: January 10, 2010
Creator: Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager, Joel W., III & Ritchie, Robert O.
Object Type: Article
System: The UNT Digital Library
Health Effects from Advanced Combustion and Fuel Technologies (open access)

Health Effects from Advanced Combustion and Fuel Technologies

This document requires a separate file for the figures. It is for DOE's Office of Vehicle Technologies Annual Report
Date: January 1, 2010
Creator: Barone, Teresa L.; Parks, James E., Jr.; Lewis, Samuel Arthur, Sr. & Connatser, Raynella M.
Object Type: Report
System: The UNT Digital Library