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Elastic electron scattering from formic acid

Description: Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data. more
Date: July 31, 2006
Creator: Trevisan, Cynthia S.; Orel, Ann E. & Rescigno, Thomas N.
Partner: UNT Libraries Government Documents Department
open access

STATUS OF CHEMICAL CLEANING OF WASTE TANKS AT THE SAVANNAH RIVER SITE F TANK FARM CLOSURE PROJECT - 9114

Description: Chemical Cleaning is currently in progress for Tanks 5 and 6 at the Savannah River Site. The Chemical Cleaning process is being utilized to remove the residual waste heel remaining after completion of Mechanical Sludge Removal. This work is required to prepare the tanks for closure. Tanks 5 and 6 are 1950s vintage carbon steel waste tanks that do not meet current containment standards. These tanks are 22.9 meters (75 feet) in diameter, 7.5 meters (24.5 feet) in height, and have a capacity of 2.… more
Date: December 31, 2008
Creator: Thaxton, D; Geoff Clendenen, G; Willie Gordon, W; Samuel Fink, S & Michael Poirier, M
Partner: UNT Libraries Government Documents Department
open access

A Top to Bottom Lithospheric Study of Africa and Arabia

Description: We study the lithospheric structure of Africa, Arabia and adjacent oceanic regions with fundamental-mode surface waves over a wide period range. Including short period group velocities allows us to examine shallower features than previous studies of the whole continent. In the process, we have developed a crustal thickness map of Africa. Main features include crustal thickness increases under the West African, Congo, and Kalahari cratons. We find crustal thinning under Mesozoic and Cenozoic rif… more
Date: October 31, 2006
Creator: Pasyanos, M
Partner: UNT Libraries Government Documents Department
open access

Calcium Carbonate Storage in Amorphous Form and Its Template-Induced Crystallization

Description: Calcium carbonate crystallization in organisms often occurs through the transformation from the amorphous precursor. It is believed that the amorphous phase could be temporarily stabilized and stored, until its templated transition to the crystalline form is induced. Here we develop a bio-inspired crystallization strategy that is based on the above mechanism. Amorphous calcium carbonate (ACC) spherulitic particles are formed and stabilized on a self-assembled monolayer (SAM) of hydroxy-terminat… more
Date: August 31, 2007
Creator: Han, T Y & Aizenberg, J
Partner: UNT Libraries Government Documents Department
open access

LISSAT Analysis of a Generic Centrifuge Enrichment Plant

Description: The U.S. Department of Energy (DOE) is interested in developing tools and methods for use in designing and evaluating safeguards systems for current and future plants in the nuclear power fuel cycle. The DOE is engaging several DOE National Laboratories in efforts applied to safeguards for chemical conversion plants and gaseous centrifuge enrichment plants. As part of the development, Lawrence Livermore National Laboratory has developed an integrated safeguards system analysis tool (LISSAT). Th… more
Date: May 31, 2007
Creator: Lambert, H; Elayat, H A; O?Connell, W J; Szytel, L & Dreicer, M
Partner: UNT Libraries Government Documents Department
open access

Experimental and theoretical studies of particle generation afterlaser ablation of copper with background gas at atmosphericpressure

Description: Laser ablation has proven to be an effective method for generating nanoparticles; particles are produced in the laser induced vapor plume during the cooling stage. To understand the in-situ condensation process, a series of time resolved light scattering images were recorded and analyzed. Significant changes in the condensation rate and the shape of the condensed aerosol plume were observed in two background gases, helium and argon. The primary particle shape and size distribution were measured… more
Date: May 31, 2007
Creator: Wen, Sy-Bor; Mao, Xianglei; Greif, Ralph & Russo, Richard E.
Partner: UNT Libraries Government Documents Department
open access

ITER Shape Controller and Transport Simulations

Description: We currently use the CORSICA integrated modeling code for scenario studies for both the DIII-D and ITER experiments. In these simulations, free- or fixed-boundary equilibria are simultaneously converged with thermal evolution determined from transport models providing temperature and current density profiles. Using a combination of fixed boundary evolution followed by free-boundary calculation to determine the separatrix and coil currents. In the free-boundary calculation, we use the state-spac… more
Date: May 31, 2007
Creator: Casper, T A; Meyer, W H; Pearlstein, L D & Portone, A
Partner: UNT Libraries Government Documents Department
open access

Zeaxanthin Radical Cation Formation in Minor Light-Harvesting Complexes of Higher Plant Antenna

Description: Previous work on intact thylakoid membranes showed that transient formation of a zeaxanthin radical cation was correlated with regulation of photosynthetic light-harvesting via energy-dependent quenching. A molecular mechanism for such quenching was proposed to involve charge transfer within a chlorophyll-zeaxanthin heterodimer. Using near infrared (880-1100 nm) transient absorption spectroscopy, we demonstrate that carotenoid (mainly zeaxanthin) radical cation generation occurs solely in isola… more
Date: January 31, 2008
Creator: Avenson, Thomas H.; Ahn, Tae Kyu; Zigmantas, Donatas; Niyogi, Krishna K.; Li, Zhirong; Ballottari, Matteo et al.
Partner: UNT Libraries Government Documents Department
open access

Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emulsion of targets at the National Ignition Facility (NIF)

Description: The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 69 feet. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accurac… more
Date: August 31, 2007
Creator: Robert M. Malone, Brent C. Frogget, Morris I. Kaufman, Thomas W. Tunnell, Robert L. Guyton, Imants P. Reinbachs, Phillip W. Watts, et al.
Partner: UNT Libraries Government Documents Department
open access

Leakage of CO2 from geologic storage: Role of secondary accumulation at shallow depth

Description: Geologic storage of CO2 can be a viable technology forreducing atmospheric emissions of greenhouse gases only if it can bedemonstrated that leakage from proposed storage reservoirs and associatedhazards are small or can be mitigated. Risk assessment must evaluatepotential leakage scenarios and develop a rational, mechanisticunderstanding of CO2 behavior during leakage. Flow of CO2 may be subjectto positive feedbacks that could amplify leakage risks and hazards,placing a premium on identifying a… more
Date: May 31, 2007
Creator: Pruess, K.
Partner: UNT Libraries Government Documents Department
open access

Mercuric Iodide Photocell Technology for Room Temperature Readout of Scintillators

Description: Mercuric iodide (HgI2) is a well known material for the direct detection of gamma rays; however, the largest volume achievable is limited by thickness of the detector, which needs to be a small fraction of the average trapping length for electrons. We are reporting here preliminary results in using HgI2 crystals to fabricate photocells used in the readout of various scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Preliminary nu… more
Date: August 31, 2007
Creator: al., Warnick Kernan et
Partner: UNT Libraries Government Documents Department
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Comparison between S/1 and R/1 tests and damage density vs. fluence (rho(phi)) results for unconditioned and sub-nanosecond laser-conditioned KD2PO4 crystals

Description: We present S/1 and R/1 test results on unconditioned and 355 nm (3{omega}), 500 ps laser conditioned DKDP. We find up to {approx}2.5X improvement in fluence in the S/1 performance after 3{omega}, 500 ps conditioning to 5 J/cm{sup 2}. For the first time, we observe a shift to higher fluences in the R/1 results for DKDP at 3{omega}, 7 ns due to 500 ps laser conditioning. The S/1 results are compared to {rho}({phi}) results previously measured on the same DKDP crystal [1]. A consistent behavior in… more
Date: October 31, 2007
Creator: Adams, J. J.; Jarboe, J.; Feit, M. & Hackel, R.
Partner: UNT Libraries Government Documents Department
open access

The morphologies of breast cancer cell lines in three-dimensionalassays correlate with their profiles of gene expression

Description: 3D cell cultures are rapidly becoming the method of choice for the physiologically relevant modeling of many aspects of non-malignant and malignant cell behavior ex vivo. Nevertheless, only a limited number of distinct cell types have been evaluated in this assay to date. Here we report the first large scale comparison of the transcriptional profiles and 3D cell culture phenotypes of a substantial panel of human breast cancer cell lines. Each cell line adopts a colony morphology of one of four … more
Date: January 31, 2007
Creator: Kenny, Paraic A.; Lee, Genee Y.; Myers, Connie A.; Neve, RichardM.; Semeiks, Jeremy R.; Spellman, Paul T. et al.
Partner: UNT Libraries Government Documents Department
open access

Reliable and Repeatable Characterization of Optical Streak Cameras

Description: Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help dete… more
Date: October 31, 2008
Creator: Michael Charest Jr., Peter Torres III, Christopher Silbernagel, and Daniel Kalantar
Partner: UNT Libraries Government Documents Department
open access

Causes of Ocean Surface temperature Changes in Atlantic andPacific Topical Cyclogenesis Regions

Description: Previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity. We use climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions. The observed SST increases in these regions range from 0.32 to 0.67 C over the 20th century. The 22 climate models examined here suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system, e… more
Date: January 31, 2006
Creator: Santer, B. D.; Wigley, T. M. L.; Gleckler, P. J.; Bonfils, C.; Wehner, M. F.; AchutaRao, K. et al.
Partner: UNT Libraries Government Documents Department
open access

A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA)

Description: Consider the linear system Ax = b, where A is a large, sparse, real, symmetric, and positive definite matrix and b is a known vector. Solving this system for unknown vector x using a smoothed aggregation multigrid (SA) algorithm requires a characterization of the algebraically smooth error, meaning error that is poorly attenuated by the algorithm's relaxation process. For relaxation processes that are typically used in practice, algebraically smooth error corresponds to the near-nullspace of A.… more
Date: May 31, 2007
Creator: Brezina, M; Manteuffel, T; McCormick, S; Ruge, J; Sanders, G & Vassilevski, P S
Partner: UNT Libraries Government Documents Department
open access

Michrochannel plate for position sensitive alpha particle detection

Description: This paper will describe the use of a microchannel plate (MCP) as the associated particle detector on a sealed tube neutron generator. The generator produces neutrons and associated alpha particles for use as a probe to locate and identify hidden explosives in associated particle imaging (API). The MCP measures the position in two dimensions and precise timing of the incident alpha particle, information which is then used to calculate the emission time and direction of the corresponding neutron… more
Date: August 31, 2007
Creator: Tinsley, Paul Hurley and James
Partner: UNT Libraries Government Documents Department
open access

Electromigration-induced plasticity and texture in Cu interconnects

Description: Plastic deformation has been observed in damascene Cu interconnect test structures during an in-situ electromigration experiment and before the onset of visible microstructural damage (ie. voiding) using a synchrotron technique of white beam X-ray microdiffraction. We show here that the extent of this electromigration-induced plasticity is dependent on the texture of the Cu grains in the line. In lines with strong <111> textures, the extent of plastic deformation is found to be relatively… more
Date: October 31, 2007
Creator: Source, Advanced Light; Tamura, Nobumichi; Budiman, A. S.; Hau-Riege, C.S.; Besser, P. R.; Marathe, A. et al.
Partner: UNT Libraries Government Documents Department
open access

H(curl) Auxiliary Mesh Preconditioning

Description: This paper analyzes a two-level preconditioning scheme for H(curl) bilinear forms. The scheme utilizes an auxiliary problem on a related mesh that is more amenable for constructing optimal order multigrid methods. More specifically, we analyze the case when the auxiliary mesh only approximately covers the original domain. The latter assumption is important since it allows for easy construction of nested multilevel spaces on regular auxiliary meshes. Numerical experiments in both two and three s… more
Date: August 31, 2006
Creator: Kolev, T V; Pasciak, J E & Vassilevski, P S
Partner: UNT Libraries Government Documents Department
open access

RADIATION HEAT TRANSFER ENVIRONMENT IN FIRE AND FURNACE TESTS OF RADIOACTIVE MATERIALS PAKCAGES

Description: The Hypothetical Accident Conditions (HAC) sequential test of radioactive materials packages includes a thermal test to confirm the ability of the package to withstand a transportation fire event. The test specified by the regulations (10 CFR 71) consists of a 30 minute, all engulfing, hydrocarbon fuel fire, with an average flame temperature of at least 800 C. The requirements specify an average emissivity for the fire of at least 0.9, which implies an essentially black radiation environment. A… more
Date: December 31, 2008
Creator: Smith, A
Partner: UNT Libraries Government Documents Department
open access

Publication and Protection of Sensitive Site Information in a Grid Infrastructure

Description: In order to create a successful grid infrastructure, sites and resource providers must be able to publish information about their underlying resources and services. This information makes it easier for users and virtual organizations to make intelligent decisions about resource selection and scheduling, and can be used by the grid infrastructure for accounting and troubleshooting services. However, such an outbound stream may include data deemed sensitive by a resource-providing site, exposing … more
Date: March 31, 2008
Creator: Cholia, Shreyas; Cholia, Shreyas & Porter, R. Jefferson
Partner: UNT Libraries Government Documents Department
open access

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

Description: We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle su… more
Date: May 31, 2007
Creator: Duffin, Andrew M. & Saykally, Richard J.
Partner: UNT Libraries Government Documents Department
open access

PRIME VALUE METHOD TO PRIORITIZE RISK HANDLING STRATEGIES

Description: Funding for implementing risk handling strategies typically is allocated according to either the risk-averse approach (the worst risk first) or the cost-effective approach (the greatest risk reduction per implementation dollar first). This paper introduces a prime value approach in which risk handling strategies are prioritized according to how nearly they meet the goals of the organization that disburses funds for risk handling. The prime value approach factors in the importance of the project… more
Date: October 31, 2007
Creator: Noller, D
Partner: UNT Libraries Government Documents Department
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