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Anaerobic Fe(III) reduction by Shewanella putrefaciens: Analysis of the electron transport chain

Description: The goals of the project were to isolate mutants that are deficient in metal reduction, identify components of the electron transport chain that are involved in this process, and purify some of these proteins for biochemical analyses. In the 3-year period since the start of the project, we have accomplished many of these goals. We have isolated several new S. oneidensis mutants that are deficient in metal reduction, and have initiated the development of vectors for the overexpression of cytochromes and other proteins in S. oneidensis. We have also overexpressed CymA, one of the c cytochromes that are involved in metal reduction.
Date: January 20, 2004
Creator: Saffarini, Daad
Partner: UNT Libraries Government Documents Department
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Determining the mechanical constitutive properties of metals as a function of strain rate and temperature: A combined experimental and modeling approach

Description: OAK-135 Development and validation of constitutive models for polycrystalline materials subjected to high strain rate loading over a range of temperatures are needed to predict the response of engineering materials to in-service type conditions (foreign object damage, high-strain rate forging, high-speed sheet forming, deformation behavior during forming, response to extreme conditions, etc.). To account accurately for the complex effects that can occur during extreme and variable loading conditions, requires significant and detailed computational and modeling efforts. These efforts must be closely coupled with precise and targeted experimental measurements that not only verify the predictions of the models, but also provide input about the fundamental processes responsible for the macroscopic response. Achieving this coupling between modeling and experimentation is the guiding principle of this program. Specifically, this program seeks to bridge the length scale between discrete dislocation interactions with grain boundaries and continuum models for polycrystalline plasticity. Achieving this goal requires incorporating these complex dislocation-interface interactions into the well-defined behavior of single crystals. Despite the widespread study of metal plasticity, this aspect is not well understood for simple loading conditions, let alone extreme ones. Our experimental approach includes determining the high-strain rate response as a function of strain and temperature with post-mortem characterization of the microstructure, quasi-static testing of pre-deformed material, and direct observation of the dislocation behavior during reloading by using the in situ transmission electron microscope deformation technique. These experiments will provide the basis for development and validation of physically-based constitutive models, which will include dislocation-grain boundary interactions for polycrystalline systems. One aspect of the program will involve the dire ct observation of specific mechanisms of micro-plasticity, as these will indicate the boundary value problem that should be addressed. This focus on the pre-yield region in the quasi-static effort (the elasto-plastic transition) is also a tractable one from an …
Date: January 5, 2004
Creator: Robertson, I. M.; Beaudoin, A. & Lambros, J.
Partner: UNT Libraries Government Documents Department
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Termination Report. Supply Curves for Agricultural and Forestry Greenhouse Gas Emissions and their Use in Integrated Assessments: Methodology and Case Development

Description: OAK-B135 The results produced by this project include: (1) Development of econometrically estimated marginal abatement and associated production curves describing response of agricultural and forestry emissions/sink/offsets enhancements for use in integrated assessments. Curves were developed that reflected agricultural, and forestry production of traditional commodities, carbon and other greenhouse gas offsets and biofuels given signals of general commodity demand, and carbon and energy prices. This work was done jointly with Dr. Ronald Sands at PNNL. A paper from this is forthcoming as follows Gillig, D., B.A. McCarl, and R.D. Sands, ''Integrating Agricultural and Forestry GHG Mitigation Response into General Economy Frameworks: Developing a Family of Response Functions,'' Mitigation and Adaptation Strategies for Global Change, forthcoming, 2004. An additional effort was done involving dynamics and a second paper was prepared that is annex A to this report and is Gillig, D., and B.A. McCarl, ''Integrating Agricultural and Forestry Response to GHG Mitigation into General Economy Frameworks: Developing a Family of Response Functions using FASOM,'' 2004. (2) Integration of the non dynamic curves from (1) into in a version of the PNNL SGM integrated assessment model was done in cooperation with Dr. Ronald Sands at PNNL. The results were reported at the second DOE conference on sequestration in the paper listed just below and the abstract is in Annex B of this report. Sands, R.D., B.A. McCarl, and D. Gillig, ''Assessment of Terrestrial Carbon Sequestration Options within a United States Market for Greenhouse Gas Emissions Reductions,'' Presented at the Second Conference on Carbon Sequestration, Alexandria, VA, May 7, 2003. The results in their latest version show about half of the needed offsets by 2030 can be achieved through agriculture through a mix of sequestration and biofuel options. (3) Alternative agricultural sequestration estimates were developed in conjunction with personnel at Colorado State University using …
Date: January 7, 2004
Creator: McCarl, Bruce & Gillig, Dhazn
Partner: UNT Libraries Government Documents Department
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Historical and Retrospective Survey of Monitored Natural Attenuation: A Line of Inquiry Supporting Monitored Natural Attenuation and Enhanced Passive Remediation of Chlorinated Solvents

Description: The Department of Energy is sponsoring an initiative to facilitate efficient, effective and responsible use of Monitored Natural Attenuation (MNA) and Enhanced Passive Remediation(EPR) for chlorinated solvents. This Office of Environmental Management Alternative Project, focuses on providing scientific and policy support for MNA/EPR. A broadly representative working group of scientists supports the project along with partnerships with regulatory organizations such as the Interstate Technology Regulatory Council and the Environmental Protection Agency. The initial product of the technical working group was a summary report that articulated the conceptual approach and central scientific tenants of the project, and that identified a prioritized listing of technical targets for field research. This report documented the process in which: (1) scientific ground rules were developed, (2) lines of inquiry were identified and then critically evaluated, (3) promising applied research topics were highlighted in the various lines of inquiry, and (4) these were discussed and prioritized. The summary report will serve as a resource to guide management and decision making throughout the period of the subject MNA/EPR Alternative Project. To support and more fully document the information presented in the summary report, we are publishing a series of supplemental documents that present the full texts from the technical analyses within the various lines of inquiry. The following report - documenting our Historical and Retrospective Survey of Monitored Natural Attenuation - is one of those supplemental documents.
Date: January 7, 2004
Creator: Looney, B. B.
Partner: UNT Libraries Government Documents Department
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FY01 Phytoremediation of Chlorinated Ethenes in Southern Sector Seepline Sediments of SRS

Description: This treatability study is now in the second year of deployment for the Southern Sector Phytoremediation Project. Phytoremediation is the use of vegetation and associated media to treat contaminated soils, sediments, and groundwater. Phytoremediation is a rapidly developing technology that promises effective and safe cleanup of certain hazardous wastes. This ongoing work addresses the fate of volatile organic contaminants (VOCs) in an experiment that simulates a vegetated seepline supplied with trichloroethylene- (TCE-) and perchloroethylene- (PCE-) contaminated groundwater. The primary objective is to determine how the trees and sediments uptake groundwater TCE and PCE, biodegrade it, and/or transform it. The experimental focus of this project is the biological removal of VOCs from seepline groundwater and sediments.
Date: January 30, 2004
Creator: Brigmon, R.L.
Partner: UNT Libraries Government Documents Department
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Impact of Zeolite Transferred from Tank 19F to Tank 18F on DWPF Vitrification of Sludge Batch 3

Description: The Defense Waste Processing Facility (DWPF) is planning to initiate vitrification of Sludge Batch 3 (SB3) in combination with Sludge Batch 2 (SB2) in the spring of 2004. The contents of Sludge Batch 3 will be a mixture of the heel remaining from Sludge Batch 1B, sludge from Tank 7F (containing coal, sand, and sodium oxalate), and sludge materials from Tank 18F. The sludge materials in Tank 18F contain part of a mound of zeolitic material transferred there from Tank 19F. This mound was physically broken up and transfers were made from Tank 19F to Tank 18F for vitrification into SB3. In addition, excess Pu and Am/Cm materials were transferred to Tank 51H to be processed through the DWPF as part of SB3. Additional Pu material and a Np stream from the Canyons are also planned to be added to SB3 before processing of this batch commences at DWPF. The primary objective of this task was to assess the impacts of the excess zeolite mound material in Tank 19F on the predicted glass and processing properties of interest when the zeolite becomes part of SB3. The two potential impacts of the Tank 19F zeolite mound on DWPF processing relates to (1) the samples taken for determination of the acceptability of a macrobatch of DWPF feed and (2) the achievable waste loading. The potential effects of the large size of the zeolite particles found in the Tank 19F solids, as reported in this study, are considered minimal for processing of SB3 in DWPF. Other findings about the zeolite conversion mechanism via a process of Ostwald ripening are discussed in the text and in the conclusions.
Date: January 7, 2004
Creator: Jantzen, Carol M.; Swingle, R. F. & Smith, F. G.
Partner: UNT Libraries Government Documents Department
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Energy Smart Schools -- Applied Research, Field Testing, and Technology Integration Annual Report

Description: This multi-state collaborative project will coordinate federal, state, and private sector resources and high-priority school-related energy research under a comprehensive initiative that includes tasks that increase adoption of advanced energy efficiency high-performance technologies in both renovation of existing schools and building new ones; educate and inform school administrators, architects, engineers, and manufacturers nationwide as to the energy, economic, and environmental benefits of energy efficiency technologies; and improve the learning environment for the nation's students through use of better temperature controls, improvements in air quality, and increased daylighting in schools.
Date: January 1, 2004
Creator: Burke, Kate
Partner: UNT Libraries Government Documents Department
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A Hydro-Economic Approach to Representing Water Resources Impacts in Integrated Assessment Models

Description: Grant Number DE-FG02-98ER62665 Office of Energy Research of the U.S. Department of Energy Abstract Many Integrated Assessment Models (IAM) divide the world into a small number of highly aggregated regions. Non-OECD countries are aggregated geographically into continental and multiple-continental regions or economically by development level. Current research suggests that these large scale aggregations cannot accurately represent potential water resources-related climate change impacts. In addition, IAMs do not explicitly model the flow regulation impacts of reservoir and ground water systems, the economics of water supply, or the demand for water in economic activities. Using the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT) model of the International Food Policy Research Institute (IFPRI) as a case study, this research implemented a set of methodologies to provide accurate representation of water resource climate change impacts in Integrated Assessment Models. There were also detailed examinations of key issues related to aggregated modeling including: modeling water consumption versus water withdrawals; ground and surface water interactions; development of reservoir cost curves; modeling of surface areas of aggregated reservoirs for estimating evaporation losses; and evaluating the importance of spatial scale in river basin modeling. The major findings include: - Continental or national or even large scale river basin aggregation of water supplies and demands do not accurately capture the impacts of climate change in the water and agricultural sector in IAMs. - Fortunately, there now exist gridden approaches (0.5 X 0.5 degrees) to model streamflows in a global analysis. The gridded approach to hydrologic modeling allows flexibility in aligning basin boundaries with national boundaries. This combined with GIS tools, high speed computers, and the growing availability of socio-economic gridded data bases allows assignment of demands to river basins to create hydro-economic zones that respect as much as possible both political and hydrologic integrity in …
Date: January 14, 2004
Creator: Kirshen, Paul H. & Strzepek, Kenneth, M.
Partner: UNT Libraries Government Documents Department
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LAW Radioactive Coupon CO{sub 2} Decontamination Test

Description: The objective of this test is to confirm that CO{sub 2} blasting is capable of effectively removing smearable contamination from the external surface of the Immobilized Low Activity Waste(ILAW) stainless steel container after glass pouring. The smearable contamination level limits specified in the approved test specification are: (1) 367 Bq/m{sup 2} (220 dpm/100 cm{sup 2}) alpha and 3670 Bq/m{sup 2} (2202 dpm/100 cm{sup 2}) beta-gamma (qualification limits); and (2) 100 dpm/100 cm{sup 2} alpha and 1000 dpm/100 cm{sup 2} beta-gamma (design limits). The removal of smearable contamination from radioactively contaminated coupon was demonstrated by varying the following operating parameters: Nozzle standoff distance; Blast air pressure; Pellet rate; and Nozzle travel speed. Coupons were weighed before and after blasting to determine if the CO{sub 2} blasting process removed measurable amounts of surface material from the coupons. High-speed photography was used to capture images of the pellets exiting the blast nozzle as a means of estimating pellet shape and velocity at the blast nozzle. Bleeding tests were performed to determine if fixed contamination remaining on coupons after blasting ''bleeds out'' and measures as smearable contamination under typical storage conditions and times. The bleeding tests consisted of storing blasted coupons with no detectable smearable contamination for a period of 92 days at 95 F. Coupons were removed at 23-day intervals and re-evaluated for smearable contamination. The radioactive coupon blasting tests consisted of four main subtasks: (1) Coupon preparation; (2) CO{sub 2} blasting; (3) High-speed photography; and (4) Bleeding tests.
Date: January 30, 2004
Creator: May, C.G.
Partner: UNT Libraries Government Documents Department
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A prototype data archive for the PIER 'thermal distribution systems in commercial buildings' project

Description: A prototype archive for a selection of building energy data on thermal distribution systems in commercial buildings was developed and pilot tested. While the pilot demonstrated the successful development of the data archive prototype, several questions remain about the usefulness of such an archive. Specifically, questions on the audience, frequency of use, maintenance, and updating of the archive would need to be addressed before this prototype is taken to the next level.
Date: January 1, 2004
Creator: Diamond, Rick C.; Wray, Craig P.; Smith, Brian V.; Dickerhoff, Darryl J.; Matson, Nance E. & Cox, Skylar A.
Partner: UNT Libraries Government Documents Department
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Radiological Design Summary Report for TRU Vent and Purge Process

Description: This report contains top-level requirements for the various areas of radiological protection for workers. Detailed quotations of the requirements for applicable regulatory documents can be found in the accompanying Implementation Guide. For the purposes of demonstrating compliance with these requirements, per Engineering Standard 01064, shall consider / shall evaluate indicates that the designer must examine the requirement for the design and either incorporate or provide a technical justification as to why the requirement is not incorporated. The Transuranic Vent and Purge process is not a project, but is considered a process change. This process has been performed successfully by Solid Waste on lower activity TRU drums. This summary report applies a graded approach and describes how the Transuranic Vent and Purge process meets each of the applicable radiological design criteria and requirements specified in Manual WSRC-TM-95-1, Engineering Standard Number 01064.
Date: January 20, 2004
Creator: Taus, L.B.
Partner: UNT Libraries Government Documents Department
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FY02 Final Report on Phytoremediation of Chlorinated Ethenes in Southern Sector Sediments of the Savannah River Site

Description: This final report details the operations and results of a 3-year Seepline Phytoremediation Project performed adjacent to Tims Branch, which is located in the Southern Sector of the Savannah River Site (SRS) A/M Area. Phytoremediation is a process where interactions between vegetation, associated microorganisms, and the host substrate combine to effectively degrade contaminated soils, sediments, and groundwater. Phytoremediation is a rapidly developing technology that shows promise for the effective and safe cleanup of certain hazardous wastes. It has the potential to remediate numerous volatile organic compounds (VOCs). Extensive characterization work has demonstrated that two VOCs, tetrachloroethylene (PCE) and trichloroethylene (TCE) are the major components of the VOC-contaminated groundwater that is migrating through the Southern Sector and Tims Branch seepline area (WSRC, 1999). The PCE and TCE are chlorinated ethenes (CE), and have been detected in seepline soils and ground water adjacent to the ecologically-sensitive Tims Branch seepline area.
Date: January 30, 2004
Creator: Brigmon, R..L.
Partner: UNT Libraries Government Documents Department
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Final Report for Research Conducted at The Scripps Institution of Oceanography, University of California San Diego from 2/2002 to 8/2003 for ''Aerosol and Cloud-Field Radiative Effects in the Tropical Western Pacific: Analyses and General Circulation Model Parameterizations''

Description: OAK-B135 Final report from the University of California San Diego for an ongoing research project that was moved to Brookhaven National Laboratory where proposed work will be completed. The research uses measurements made by the Atmospheric Radiation Measurement (ARM) Program to quantify the effects of aerosols and clouds on the Earth's energy balance in the climatically important Tropical Western Pacific.
Date: January 27, 2004
Creator: Vogelmann, A. M.
Partner: UNT Libraries Government Documents Department
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Identification of Actin-Binding Proteins from Maize Pollen

Description: Specific Aims--The goal of this project was to gain an understanding of how actin filament organization and dynamics are controlled in flowering plants. Specifically, we proposed to identify unique proteins with novel functions by investigating biochemical strategies for the isolation and characterization of actin-binding proteins (ABPs). In particular, our hunt was designed to identify capping proteins and nucleation factors. The specific aims included: (1) to use F-actin affinity chromatography (FAAC) as a general strategy to isolate pollen ABPs (2) to produce polyclonal antisera and perform subcellular localization in pollen tubes (3) to isolate cDNA clones for the most promising ABPs (4) to further purify and characterize ABP interactions with actin in vitro. Summary of Progress By employing affinity chromatography on F-actin or DNase I columns, we have identified at least two novel ABPs from pollen, PrABP80 (gelsolin-like) and ZmABP30, We have also cloned and expressed recombinant protein, as well as generated polyclonal antisera, for 6 interesting ABPs from Arabidopsis (fimbrin AtFIM1, capping protein a/b (AtCP), adenylyl cyclase-associated protein (AtCAP), AtCapG & AtVLN1). We performed quantitative analyses of the biochemical properties for two of these previously uncharacterized ABPs (fimbrin and capping protein). Our studies provide the first evidence for fimbrin activity in plants, demonstrate the existence of barbed-end capping factors and a gelsolin-like severing activity, and provide the quantitative data necessary to establish and test models of F-actin organization and dynamics in plant cells.
Date: January 13, 2004
Creator: Staiger, C.J.
Partner: UNT Libraries Government Documents Department
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A Fundamental Study of Laser-Induced Breakdown Spectroscopy Using Fiber Optics for Remote Measurements Of Trace Metals

Description: Develop a fiber-optic imaging probe for microanalysis of solid samples; Design a time-resolved plasma imaging system to measure the development of the LIBS signal; Setup a laboratory system capable of timing two lasers independently, for optimizing and characterizing dual-pulse LIBS; Compare the development of laser-induced plasmas generated with a single laser pulse to the development of laser-induced plasmas generated with a pre-ablation spark prior to sample ablation; Examine the effect of sample matrix on the LIBS signals of elements in different sample matrices; Investigate the effect of excitation wavelength of the ablation beam in pre-ablation spark dual-pulse LIBS experiments; Determine the effect of the physical properties of the sample on the mass of materials ablated.
Date: January 20, 2004
Creator: Goode, Scott & Angel, S. Michael
Partner: UNT Libraries Government Documents Department
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Dissolution of Highly Enriched Uranium from the Idaho National Engineering and Environmental Laboratory

Description: Since the capability to purify uranium (U) was terminated at the Idaho National Engineering and Environmental Laboratory (INEEL) in the early 1990's, excess highly enriched uranium (HEU) from the cleanout of uranium trioxide (UO3) production equipment will be shipped to the Savannah River Site (SRS) for disposition. The excess material will be dissolved in Phase I of HB-Line, purified by solvent extraction, and blended with normal U to an enrichment which can be used to fabricate fuel for Tennessee Valley Authority (TVA) reactors. The proposed HB-Line processing strategy is to dissolve up to 3 kg of material per 18 L dissolver batch. To demonstrate the proposed processing strategy, two samples of the HEU were shipped to the Savannah River Technology Center (SRTC). The material was used in a series of small-scale experiments in which prototypical amounts were dissolved to characterize the offgas and measure the dissolution time under varying process conditions. Complete dissolution of the U was obtained in 15-30 min for experiments performed at 23-60 degrees Celsius. The HEU was dissolved in 3.5M HNO3 using the solids to liquid ratio proposed for use in HB-Line. The experiment performed at 23 degrees Celsius demonstrated that rapid heat generation during the dissolution is not a concern.
Date: January 14, 2004
Creator: Rudisill, T.S.
Partner: UNT Libraries Government Documents Department
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Gas Generation Testing of Neptunium Oxide at Elevated Temperature

Description: Elevated temperature gas generation tests have been conducted using neptunium dioxide produced on a laboratory scale using the HB-Line Phase II flowsheet. These tests were performed to determine what effect elevated temperatures would have on the neptunium dioxide in comparison to neptunium dioxide tested at ambient temperature. The headspace gas compositions following storage at elevated temperatures associated with normal conditions of transport (NCT) have been measured. These test results show an increase in hydrogen generation rate at elevated temperature and significant removal of oxygen from the headspace gas. The elevated temperature gas generation tests described in this report involved heating small test vessels containing neptunium dioxide and measuring the headspace gas pressure and composition at the end of the test period. Four samples were used in these tests to evaluate the impact of process variables on the gas generation rate. Two samples were calcined to 600 degrees Celsius and two were calcined to 650 degrees Celsius. Each test vessel contained approximately 9.5 g of neptunium dioxide. Following exposure to 75 per cent relative humidity (RH) for five days, these samples were loaded in air and then heated to between 105 and 115 degrees Celsius for about one month. At the conclusion of the test period, the headspace gas of each container was analyzed using a micro-gas chromatograph installed in the glovebox where the experiments were conducted. The pressure, volume, and composition data for the headspace gas samples were used to calculate average H2 generation rates.
Date: January 30, 2004
Creator: Duffey, JM
Partner: UNT Libraries Government Documents Department
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Investigation of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities

Description: Some of the major difficulties encountered in the effort to achieve nuclear fusion by means of inertial confinement arise from the unstable behavior of the interface between the shell material and the nuclear fuel which develops upon implosion of the shell by direct or indirect laser drive. The fluid flows that develop (termed the Rayleigh-Taylor (RT) and the Richtmyer-Meshkov (RM) instabilities) cause the gassified shell material to mix with the nuclear fuel, causing a reduction in energy yield or no ignition altogether. The present research program addresses the Rayleigh-Taylor and the Richtmyer-Meshkov instabilities with extensive laboratory and computational experiments. In the past year, three new activities have been initiated: a new shock tube experiment, involving the impulsive acceleration of a test gas-filled soap bubble, diagnosed with planar Mie scattering or planar induced fluorescence; a Rayleigh-Taylor experiment based on the use of a magnetorheological (MR) fluid to fix the initial shape of the interface between the MR fluid and water; and a series of computer calculations using the Raptor code (made available by Lawrence Livermore National Laboratory) to design and simulate the shock tube experiments.
Date: January 14, 2004
Creator: Bonazza, Riccardo; Anderson, Mark & Smith, Leslie
Partner: UNT Libraries Government Documents Department
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Modification to the Monte N-Particle (MCNP) Visual Editor (MCNPVised) to read in Computer Aided Design (CAD) files

Description: Monte Carlo N-Particle Transport Code (MCNP) (Reference 1) is the code of choice for doing complex neutron/photon/electron transport calculations for the nuclear industry and research institutions. The Visual Editor for Monte Carlo N-Particle (References 2 to 11) is recognized internationally as the best code for visually creating and graphically displaying input files for MCNP. The work performed in this grant enhanced the capabilities of the MCNP Visual Editor to allow it to read in a 2D Computer Aided Design (CAD) file, allowing the user to modify and view the 2D CAD file and then electronically generate a valid MCNP input geometry with a user specified axial extent.
Date: January 29, 2004
Creator: Schwarz, Randy A. Carter, Leeland L.
Partner: UNT Libraries Government Documents Department
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TDNA Monthly Office Manager's Report: January 2004

Description: Monthly report written by the Texas Daily Newspaper Association's (TDNA's) office manager, Darla Thompson, to Phil Berkebile providing a summary of revenues and account balances, programs, meetings, and other activities in the office during the previous month.
Date: January 30, 2004
Creator: Thompson, Darla
Partner: UNT Libraries Special Collections
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TDNA Monthly Office Manager's Report: December 2003

Description: Monthly report written by the Texas Daily Newspaper Association's (TDNA's) office manager, Darla Thompson, to Phil Berkebile providing a summary of revenues and account balances, programs, meetings, and other activities in the office during the previous month.
Date: January 6, 2004
Creator: Thompson, Darla
Partner: UNT Libraries Special Collections
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Physics study of the TRADE : TRIGA accelerator driven experiment.

Description: This report deals with the validation of an ADS dynamic behavior through the TRADE program. We first describe the motivations behind the TRADE project. This includes the types of ADS experiments to be performed and their necessity, beam trips issues, representativity of the experiment, and steps to be taken in the validation procedure. Then we perform the characterization of the TRADE core using deterministic methods. The general core description is given. A number of results related to the core criticality and modeling with different geometries are presented. Finally we report the experimental results of the recent critical measurements including the control rod calibration, determination of the critical configurations and fluxes in the core.
Date: January 13, 2004
Creator: Naberejnev, D.; Imel, G.; Palmiotti, G. & Salvatores, M.
Partner: UNT Libraries Government Documents Department
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Integrated Field, Laboratory, and Modeling Studies to Determine the Effects of Linked Microbial and Physical Spatial Heterogeneity on Engineered Vadose Zone Bioremediation

Description: While numerous techniques exist for remediation of contaminant plumes in groundwater or near the soil surface, remediation methods in the deep vadose zone are less established due to complex transport dynamics and sparse microbial populations. There is a lack of knowledge on how physical and hydrologic features of the vadose zone control microbial growth and colonization in response to nutrient delivery during bioremediation. Yet pollution in the vadose zone poses a serious threat to the groundwater resources lying deeper in the sediment. While the contaminants may be slowly degraded by native microbial communities, microbial degradation rates rarely keep pace with the spread of the pollutant. It is crucial to increase indigenous microbial degradation in the vadose zone to combat groundwater contamination.
Date: January 26, 2004
Creator: Brokman, Fred; Selker, John & Rockhold, Mark
Partner: UNT Libraries Government Documents Department
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FY03 DNAPL Characterization of the A-14 Outfall

Description: Residual dense non-aqueous phase liquid (DNAPL) contamination continues to be one of the most challenging remediation and characterization problems at SRS and sites around the world. Chlorinated solvents were usually released as DNAPLs to/the subsurface where they move in an unstable fashion driven by gravitational and,capillary forces. They are often retained in small discrete blobs in fine grain materials in the vadose zone and contaminate ground water by slow continuous release through dissolution and diffusion. Locating these small sources is a difficult but crucial part of remediating a contaminated site. Several methods have been developed to locate subsurface DNAPL but nearly all are intrusive and can only identify DNAPL in close proximity to the access hole. Minimally invasive geophysical methods to locate residual DNAPL have been proposed and developed but few methods are capable of the spatial resolution required. Complex resistivity measurements sensitive to DNAPL (perchloroethylene) interactions with clay (smectite) have recently been shown to have promise in laboratory experiments. Based on these laboratory results, field tests of the complex resistivity technique were performed at the A-014 outfall.
Date: January 14, 2004
Creator: Riha, BD
Partner: UNT Libraries Government Documents Department
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