Yellowstone Bison: Interagency Plan and Agencies' Management Need Improvement to Better Address Bison-Cattle Brucellosis Controversy (open access)

Yellowstone Bison: Interagency Plan and Agencies' Management Need Improvement to Better Address Bison-Cattle Brucellosis Controversy

A letter report issued by the Government Accountability Office with an abstract that begins "Federal and Montana state agencies have long been entangled in controversy over bison leaving Yellowstone National Park. Some of these bison, as well as elk and other wildlife, have a contagious disease called brucellosis, which can cause pregnant animals to abort. Montana livestock owners and government officials fear that if bison are allowed to leave the park, the disease could spread to cattle, potentially threatening the economic health of the state's livestock industry. To help manage this issue, three federal and two state agencies have been implementing a bison management plan that they agreed to in 2000. This report discusses (1) the progress made in implementing the bison management plan and (2) the plan's soundness and the effectiveness of the agencies' implementation of it for managing bison-related issues in and near Yellowstone National Park. GAO reviewed documentation and research on bison and brucellosis and interviewed federal and state officials and key stakeholders."
Date: March 7, 2008
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Aviation and the Environment: Initial Voluntary Airport Low Emissions Program Projects Reduce Emissions, and FAA Plans to Assess the Program's Overall Performance as Participation Increases (open access)

Aviation and the Environment: Initial Voluntary Airport Low Emissions Program Projects Reduce Emissions, and FAA Plans to Assess the Program's Overall Performance as Participation Increases

A letter report issued by the Government Accountability Office with an abstract that begins "In 2003, Congress established a program to reduce airport ground emissions at commercial service airports in areas failing to meet or maintain air quality standards. The Federal Aviation Administration (FAA) administers the Voluntary Airport Low Emissions (VALE) Program and oversees the program's two sources of funding: Airport Improvement Program (AIP) federal grants or Passenger Facility Charges (PFC), which airports can collect from passengers. Participating airports also receive credits for the emission reductions achieved through VALE projects in accordance with the law and guidance. Airports can use these credits to offset emissions resulting from development projects to comply with federal Clean Air Act requirements. GAO was asked to determine (1) how the VALE program has been implemented, including airport participation levels, types of projects, and program expenditures, and (2) the outcomes attributable to the VALE program. To do this, GAO reviewed FAA data on VALE projects for all nine participating airports; visited two of these airports; obtained information from the remaining seven participating airports and four nonparticipating airports; and interviewed officials from FAA, Environmental Protection Agency (EPA), and airport associations. FAA generally agreed with the report's findings, …
Date: November 7, 2008
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Department of Energy: New Loan Guarantee Program Should Complete Activities Necessary for Effective and Accountable Program Management (open access)

Department of Energy: New Loan Guarantee Program Should Complete Activities Necessary for Effective and Accountable Program Management

A letter report issued by the Government Accountability Office with an abstract that begins "Title XVII of the Energy Policy Act of 2005 established DOE's loan guarantee program (LGP) for innovative energy projects that should decrease air pollutants or greenhouse gases and that have a reasonable prospect of repayment. For fiscal years 2008 and 2009, Congress authorized the use of borrower fees to pay the costs of loan guarantees through Title XVII's "borrower pays" option, under which DOE will limit loan guarantees to $38.5 billion. Congress mandated that GAO review DOE's progress in implementing the LGP. GAO assessed DOE's progress in (1) issuing final regulations and (2) taking actions to help ensure that the program is managed effectively and to maintain accountability. GAO also assessed how inherent risks due to the nature of the LGP may affect DOE's ability to achieve intended program outcomes. GAO analyzed DOE's regulations, guidance, and program documents and files; reviewed Title XVII; and interviewed DOE officials."
Date: July 7, 2008
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
Federal Tort Reform Legislation: Constitutionality and Summaries of Selected Statutes (open access)

Federal Tort Reform Legislation: Constitutionality and Summaries of Selected Statutes

This report considers the constitutionality of federal tort reform legislation, such as the products liability and medical malpractice reform proposals that have been introduced for the last several Congresses. Tort law at present is almost exclusively state law rather than federal law, although, as noted in the appendix to this report, Congress has enacted a number of tort reform statutes.
Date: July 7, 2008
Creator: Cohen, Henry & Burrows, Vanessa K.
Object Type: Report
System: The UNT Digital Library
Lobbying Regulations on Non-Profit Organizations (open access)

Lobbying Regulations on Non-Profit Organizations

Public charities, religious groups, social welfare organizations, and other nonprofit organizations which are exempt from federal income taxation are not generally prohibited from engaging in all lobbying or public policy advocacy activities merely because of their tax-exempt status. There may, however, be some lobbying limitations on certain organizations, depending. This report discusses this issue at length, including related legislation, relevant passages in the Internal Revenue Code, and other regulatory information.
Date: May 7, 2008
Creator: Maskell, Jack H.
Object Type: Report
System: The UNT Digital Library
Development of backlighting sources for a Compton radiography diagnostic of Inertial Confinement Fusion targets (open access)

Development of backlighting sources for a Compton radiography diagnostic of Inertial Confinement Fusion targets

We present scaled demonstrations of backlighter sources, emitting Bremsstrahlung x-rays with photon energies above 75 keV, that we will use to record x-ray Compton radiographic snapshots of cold dense DT fuel in inertial confinement fusion implosions at the National Ignition Facility (NIF). In experiments performed at the Titan laser facility at Lawrence Livermore National Laboratory, we measured the source size and the Bremsstrahlung spectrum as a function of laser intensity and pulse length, from solid targets irradiated at 2e17-5e18 W/cm{sup 2} using 2-40 ps pulses. Using Au planar foils we achieved source sizes down to 5.5 {micro}m, and conversion efficiencies of about 1e-3 J/J into x-ray photons with energies in the 75-100 keV spectral range. We can now use these results to design NIF backlighter targets and shielding, and to predict Compton radiography performance as a function of the NIF implosion yield and associated background.
Date: May 7, 2008
Creator: Tommasini, R.; MacPhee, A.; Hey, D.; Ma, T.; Chen, C.; Izumi, N. et al.
Object Type: Article
System: The UNT Digital Library
Single shot extreme ultraviolet laser imaging of nanostructures with wavelength resolution (open access)

Single shot extreme ultraviolet laser imaging of nanostructures with wavelength resolution

We have demonstrated near-wavelength resolution microscopy in the extreme ultraviolet. Images of 50 nm diameter nanotubes were obtained with a single {approx}1 ns duration pulse from a desk-top size 46.9 nm laser. We measured the modulation transfer function of the microscope for three different numerical aperture zone plate objectives, demonstrating that 54 nm half-period structures can be resolved. The combination of near-wavelength spatial resolution and high temporal resolution opens myriad opportunities in imaging, such as the ability to directly investigate dynamics of nanoscale structures.
Date: January 7, 2008
Creator: Jones, Juanita; Brewer, Courtney A.; Brizuela, Fernando; Wachulak, Przemyslaw; Martz, Dale H.; Chao, Weilun et al.
Object Type: Article
System: The UNT Digital Library
Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado, Quality Assurance Project Plan (open access)

Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado, Quality Assurance Project Plan

The U.S. Department of Energy (DOE) is cleaning up and/or monitoring large, dilute plumes contaminated by metals, such as uranium and chromium, whose mobility and solubility change with redox status. Field-scale experiments with acetate as the electron donor have stimulated metal-reducing bacteria to effectively remove uranium [U(VI)] from groundwater at the Uranium Mill Tailings Site in Rifle, Colorado. The Pacific Northwest National Laboratory and a multidisciplinary team of national laboratory and academic collaborators has embarked on a research proposed for the Rifle site, the object of which is to gain a comprehensive and mechanistic understanding of the microbial factors and associated geochemistry controlling uranium mobility so that DOE can confidently remediate uranium plumes as well as support stewardship of uranium-contaminated sites. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the Rifle Integrated Field-Scale Subsurface Research Challenge Project.
Date: January 7, 2008
Creator: Fix, N. J.
Object Type: Report
System: The UNT Digital Library
An Aerosol Condensation Model for Sulfur Trioxide (open access)

An Aerosol Condensation Model for Sulfur Trioxide

This document describes a model for condensation of sulfuric acid aerosol given an initial concentration and/or source of gaseous sulfur trioxide (e.g. fuming from oleum). The model includes the thermochemical effects on aerosol condensation and air parcel buoyancy. Condensation is assumed to occur heterogeneously onto a preexisting background aerosol distribution. The model development is both a revisiting of research initially presented at the Fall 2001 American Geophysical Union Meeting [1] and a further extension to provide new capabilities for current atmospheric dispersion modeling efforts [2]. Sulfuric acid is one of the most widely used of all industrial chemicals. In 1992, world consumption of sulfuric acid was 145 million metric tons, with 42.4 Mt (mega-tons) consumed in the United States [10]. In 2001, of 37.5 Mt consumed in the U.S., 74% went into producing phosphate fertilizers [11]. Another significant use is in mining industries. Lawuyi and Fingas [7] estimate that, in 1996, 68% of use was for fertilizers and 5.8% was for mining. They note that H{sub 2}SO{sub 4} use has been and should continue to be very stable. In the United States, the elimination of MTBE (methyl tertiary-butyl ether) and the use of ethanol for gasoline production are further increasing …
Date: February 7, 2008
Creator: Grant, K E
Object Type: Report
System: The UNT Digital Library
Search for B0 to K*+ K*- (open access)

Search for B0 to K*+ K*-

The authors report the results of a search for the decay B{sup 0} {yields} K*{sup +}K*{sup -} with a sample of 454 {+-} 5 million B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at the Stanford Linear Accelerator Center. They obtain an upper limit at the 90% confidence level on the branching fraction for {Beta}(B{sup 0} {yields} K*{sup +}K*{sup -}) < 2.0 x 10{sup -6}, assuming the decay is fully longitudinally polarized.
Date: August 7, 2008
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
The Effects of Various Conductive Additive and Polymeric Binder Contents on the Performance of a Lithium-ion Composite (open access)

The Effects of Various Conductive Additive and Polymeric Binder Contents on the Performance of a Lithium-ion Composite

Fundamental electrochemical methods, cell performance tests, and physical characterization tests such as electron microscopy were used to study the effects of levels of the inert materials (acetylene black (AB), a nano-conductive additive, and polyvinylidene difluoride (PVDF), a polymer binder) on the power performance of lithium-ion composite cathodes. The electronic conductivity of the AB/PVDF composites at different compositions was measured with a four-point probe direct current method. The electronic conductivity was found to increase rapidly and plateau at a AB:PVDF ratio 0.2:1 (by weight), with 0.8:1 being the highest conductivity composition. AB:PVDF compositions along the plateau of 0.2:1, 0.4:1, 0.6:1 and 0.8:1 were investigated. Electrodes of each of those compositions were fabricated with different fractions of AB/PVDF to active material. It was found that at the 0.8:1 AB:PVDF, the rate performance improved with increases in the AB/PVDF loading, whereas at the 0.2:1 AB:PVDF, the rate performance improved with decreases in the AB/PVDF loading. The impedance of electrodes made with 0.6:1 AB:PVDF was low and relatively invariant.
Date: August 7, 2008
Creator: Stevenson, Cynthia; Liu, G.; Zheng, H.; Kim, S.; Deng, Y.; Minor, A.M. et al.
Object Type: Article
System: The UNT Digital Library
A Automated Tool for Supporting FMEAs of Digital Systems (open access)

A Automated Tool for Supporting FMEAs of Digital Systems

Although designs of digital systems can be very different from each other, they typically use many of the same types of generic digital components. Determining the impacts of the failure modes of these generic components on a digital system can be used to support development of a reliability model of the system. A novel approach was proposed for such a purpose by decomposing the system into a level of the generic digital components and propagating failure modes to the system level, which generally is time-consuming and difficult to implement. To overcome the associated issues of implementing the proposed FMEA approach, an automated tool for a digital feedwater control system (DFWCS) has been developed in this study. The automated FMEA tool is in nature a simulation platform developed by using or recreating the original source code of the different module software interfaced by input and output variables that represent physical signals exchanged between modules, the system, and the controlled process. For any given failure mode, its impacts on associated signals are determined first and the variables that correspond to these signals are modified accordingly by the simulation. Criteria are also developed, as part of the simulation platform, to determine whether the …
Date: September 7, 2008
Creator: Yue, M.; Chu, T. L.; Martinez-Guridi, G. & Lehner, J.
Object Type: Article
System: The UNT Digital Library
B, D and K Decays (open access)

B, D and K Decays

The present report documents the results of Working Group 2: B, D and K decays, of the workshop on Flavor in the Era of the LHC, held at CERN from November 2005 through March 2007. With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavor physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC. The aim of Working Group 2 was twofold: on one hand, to provide a coherent, up-to-date picture of the status of flavor physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP …
Date: March 7, 2008
Creator: Artuso, M.; Asner, D. M.; Ball, P.; Baracchini, E.; Bell, G.; Beneke, M. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of CP-Violating Asymmetries in the B0->K+K-Ks Dalitz Plot (open access)

Measurement of CP-Violating Asymmetries in the B0->K+K-Ks Dalitz Plot

The authors present a preliminary measurement of CP-violation parameters in the decay B{sup 0} {yields} K{sup +}K{sup -}K{sub S}{sup 0}, using approximately 465 million B{bar B} events collected by the BABAR detector at SLAC. Reconstructing the neutral kaon as K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -} or K{sub S}{sup 0} {yields} {pi}{sup 0}{pi}{sup 0}, they analyze the Dalitz plot distribution and measure fractions to intermediate states. They extract CP parameters from the asymmetries in amplitudes and phases between B{sup 0} and {bar B}{sup 0} decays across the Dalitz plot. From a fit to the whole Dalitz plot, they measure {beta}{sub eff} = 0.44 {+-} 0.07 {+-} 0.02, A{sub CP} = 0.03 {+-} 0.07 {+-} 0.02, where the first uncertainties are statistical and the second ones are systematic. For decays to {phi}K{sub S}{sup 0}, they measure {beta}{sub eff} = 0.13 {+-} 0.13 {+-} 0.02, A{sub CP} = 0.14 {+-} 0.19 {+-} 0.02. For decays to f{sub 0}K{sub S}{sup 0}, they measure {beta}{sub eff} = 0.15 {+-} 0.13 {+-} 0.03, A{sub CP} = 0.01 {+-} 0.26 {+-} 0.07. From a fit to the region of the Dalitz plot with m{sub K{sup +}K{sup -}} > 1.1 GeV/c{sup 2}, they measure {beta}{sub eff} = …
Date: August 7, 2008
Creator: Kim, H
Object Type: Article
System: The UNT Digital Library
Physical Sciences 2007 Science & Technology Highlights (open access)

Physical Sciences 2007 Science & Technology Highlights

The Physical Sciences Directorate applies frontier physics and technology to grand challenges in national security. Our highly integrated and multidisciplinary research program involves collaborations throughout Lawrence Livermore National Laboratory, the National Nuclear Security Administration, the Department of Energy, and with academic and industrial partners. The Directorate has a budget of approximately $150 million, and a staff of approximately 350 employees. Our scientists provide expertise in condensed matter and high-pressure physics, plasma physics, high-energy-density science, fusion energy science and technology, nuclear and particle physics, accelerator physics, radiation detection, optical science, biotechnology, and astrophysics. This document highlights the outstanding research and development activities in the Physical Sciences Directorate that made news in 2007. It also summarizes the awards and recognition received by members of the Directorate in 2007.
Date: April 7, 2008
Creator: Hazi, A U
Object Type: Report
System: The UNT Digital Library
Final Technical Report (open access)

Final Technical Report

P. fluorescens PfO-1 is a soil bacterium isolated by this laboratory from sandy loam soil (4). Because of the importance of adhesion for persistence in natural environments, we utilized adherence to sand as an assay to screen a library of PfO-1 mutants for defects in adhesion. Three adhesion defective mutants, PfO-5, PfO-10, and PfO-15 were recovered. PfO-5 and PfO-10 had different insertions in the same gene, which we called adnA, and also showed motility defects (3). PfO-15 was motile, but was hyper-flagellated. The insertion was in a different gene, adnB, which shows similarity to mot genes involved in flagella functions (Strain and Levy, unpublished). These early studies demonstrated the important but separable requirements for flagella and motility in adherence. In a field study, the adnA mutant PfO-5 was less able to persist than the wildtype PfO-1 and did not spread as fast or as far from the point of inoculation as did PfO-1 (7), linking adhesion and soil fitness. DNA sequencing revealed that AdnA shares 82% identity with the flagella regulator FleQ from P. aeruginosa (3). FleQ is required for adhesion of P. aeruginosa to respiratory mucin, which is important for pathogenesis (1, 2). Using a gene fusion approach, seven …
Date: July 7, 2008
Creator: Stuart B. Levy, M.D.
Object Type: Report
System: The UNT Digital Library
The Utilization of Spin Polarized Photoelectron Spectroscopy as a Probe of Electron Correlation with an Ultimate Goal of Pu (open access)

The Utilization of Spin Polarized Photoelectron Spectroscopy as a Probe of Electron Correlation with an Ultimate Goal of Pu

We are developing the technique of spin-polarized photoelectron spectroscopy as a probe of electron correlation with the ultimate goal of resolving the Pu electronic structure controversy. Over the last several years, we have demonstrated the utility of spin polarized photoelectron spectroscopy for determining the fine details of the electronic structure in complex systems such as those shown in this report.
Date: February 7, 2008
Creator: Tobin, J G; Yu, S W; Chung, B W; Morton, S A; Komesu, T & Waddill, G D
Object Type: Article
System: The UNT Digital Library
Final Technical Report on STTR Project DE-FG02-04ER86191 Hydrogen Cryostat for Muon Beam Cooling (open access)

Final Technical Report on STTR Project DE-FG02-04ER86191 Hydrogen Cryostat for Muon Beam Cooling

The project was to develop cryostat designs that could be used for muon beam cooling channels where hydrogen would circulate through refrigerators and the beam-cooling channel to simultaneously refrigerate 1) high-temperature-superconductor (HTS) magnet coils, 2) cold copper RF cavities, and 3) the hydrogen that is heated by the muon beam. In an application where a large amount of hydrogen is naturally present because it is the optimum ionization cooling material, it was reasonable to explore its use with HTS magnets and cold, but not superconducting, RF cavities. In this project we developed computer programs for simulations and analysis and conducted experimental programs to examine the parameters and technological limitations of the materials and designs of Helical Cooling Channel (HCC) components (magnet conductor, RF cavities, absorber windows, heat transport, energy absorber, and refrigerant).The project showed that although a hydrogen cryostat is not the optimum solution for muon ionization cooling channels, the studies of the cooling channel components that define the cryostat requirements led to fundamental advances. In particular, two new lines of promising development were opened up, regarding very high field HTS magnets and the HS concept, that have led to new proposals and funded projects.
Date: May 7, 2008
Creator: Johnson, Rolland P.
Object Type: Report
System: The UNT Digital Library
Quantifying uncertainties of a Soil-Foundation Structure-Interaction System under Seismic Excitation (open access)

Quantifying uncertainties of a Soil-Foundation Structure-Interaction System under Seismic Excitation

We applied a spectrum of uncertainty quantification (UQ) techniques to the study of a two-dimensional soil-foundation-structure-interaction (2DSFSI) system (obtained from Professor Conte at UCSD) subjected to earthquake excitation. In the process we varied 19 uncertain parameters describing material properties of the structure and the soil. We present in detail the results for the different stages of our UQ analyses.
Date: April 7, 2008
Creator: Tong, C
Object Type: Report
System: The UNT Digital Library
Regulation of in situ to invasive breast carcinoma transition (open access)

Regulation of in situ to invasive breast carcinoma transition

The transition of ductal carcinoma in situ (DCIS) to invasive carcinoma is a key event in breast tumor progression that is poorly understood. Comparative molecular analysis of tumor epithelial cells from in situ and invasive tumors has failed to identify consistent tumor stage-specific differences. However, the myoepithelial cell layer, present only in DCIS, is a key distinguishing and diagnostic feature. To determine the contribution of non-epithelial cells to tumor progression, we analyzed the role of myoepithelial cells and fibroblasts in the progression of in situ carcinomas using a xenograft model of human DCIS. Progression to invasion was promoted by fibroblasts, but inhibited by normal myoepithelial cells. The invasive tumor cells from these progressed lesions formed DCIS rather than invasive cancers when re-injected into naive mice. Molecular profiles of myoepithelial and epithelial cells isolated from primary normal and cancerous human breast tissue samples corroborated findings obtained in the xenograft model. These results provide the proof of principle that breast tumor progression could occur in the absence of additional genetic alterations and that tumor growth and progression could be controlled by replacement of normal myoepithelial inhibitory signals.
Date: May 7, 2008
Creator: Polyak, Kornelia; Hu, Min; Yao, Jun; Carroll, Danielle K.; Weremowicz, Stanislawa; Chen, Haiyan et al.
Object Type: Article
System: The UNT Digital Library
Progress and Design Status of the ITER MSE Diagnostic (open access)

Progress and Design Status of the ITER MSE Diagnostic

The Motional Stark Effect (MSE) diagnostic will be essential for the study of advanced scenarios on ITER and its design is currently underway. In order meet the ITER MSE diagnostic design requirements, two approaches for the measurement are under consideration. The first is based on standard polarimeter techniques to measure the polarization of the emitted light, whereas the second measures the Stark splitting from which |B| can be inferred, where |B| is the magnitude of the total magnetic field. The baseline design of the optical system is centered on the first approach. Emphasis in this case is placed on minimizing the polarization aberrations of the optical relay system. Motivation for the second method results from concern that the optical properties of the plasma-facing mirror, particularly its diattenuation and retardance, will degrade with plasma exposure. The second approach, while less sensitive to aberrations induced by plasma exposure effects, requires greater optical throughput in order to measure the complete Stark spectrum. We have developed optimized designs for both techniques and will present a comparison of them and discuss the associated design trade-offs.
Date: May 7, 2008
Creator: Makowski, M A; Allen, S L; Holcomb, C T; Lerner, S; Morris, K & Wong, N
Object Type: Article
System: The UNT Digital Library
Radiographic Capabilities of the MERCURY Monte Carlo Code (open access)

Radiographic Capabilities of the MERCURY Monte Carlo Code

MERCURY is a modern, parallel, general-purpose Monte Carlo code being developed at the Lawrence Livermore National Laboratory. Recently, a radiographic capability has been added. MERCURY can create a source of diagnostic, virtual particles that are aimed at pixels in an image tally. This new feature is compared to the radiography code, HADES, for verification and timing. Comparisons for accuracy were made using the French Test Object and for timing were made by tracking through an unstructured mesh. In addition, self consistency tests were run in MERCURY for the British Test Object and scattering test problem. MERCURY and HADES were found to agree to the precision of the input data. HADES appears to run around eight times faster than the MERCURY in the timing study. Profiling the MERCURY code has turned up several differences in the algorithms which account for this. These differences will be addressed in a future release of MERCURY.
Date: April 7, 2008
Creator: McKinley, M. Scott & Schach von Wittenau, Alexis E.
Object Type: Article
System: The UNT Digital Library
PARAMETRIC EFFECTS OF ANTI-FOAM COMPOSITION, SIMULANT PROPERTIES AND NOBLE METALS ON THE GAS HOLDUP AND RELEASE OF A NON-NEWTONIAN WASTE SLURRY SIMULANT (open access)

PARAMETRIC EFFECTS OF ANTI-FOAM COMPOSITION, SIMULANT PROPERTIES AND NOBLE METALS ON THE GAS HOLDUP AND RELEASE OF A NON-NEWTONIAN WASTE SLURRY SIMULANT

Gas holdup tests were performed in bench-scale and small-scale mechanically-agitated mixing systems at the Savannah River National Laboratory (SRNL) for a simulant of waste from the Hanford Tank 241-AZ-101. These featured additions of DOW Corning Q2-3183A anti-foam agent. Results indicated that this anti-foam agent (AFA) increased gas holdup in the waste simulant by about a factor of four and, counter-intuitively, that the holdup increased as the non-newtonian simulant shear strength decreased (apparent viscosity decreased). Such results raised the potential of increased flammable gas retention in Hanford Waste Treatment and Immobilization Plant (WTP) vessels mixed by air sparging and pulse-jet mixers (PJMs) during a Design Basis Event (DBE). Additional testing was performed to determine the effects of simulant properties, composition of alternate AFAs, and presence of trace noble metals. Key results are that: (1) Increased gas holdup resulting from addition of Q2-3183A is due to a decrease in surface tension that supports small bubbles which have low rise velocities. (2) Dow Corning 1520-US AFA shows it to be a viable replacement to Dow Corning Q2-3183A AFA. This alternative AFA, however, requires significantly higher dosage for the same anti-foam function. (3) Addition of noble metals to the AZ-101 waste simulant does not …
Date: August 7, 2008
Creator: Guerrero, H; Charles Crawford, C & Mark Fowley, M
Object Type: Article
System: The UNT Digital Library
SPECTRAL IDENTIFICATION OF AN ANCIENT SUPERNOVA USING LIGHT ECHOES IN THE LMC (open access)

SPECTRAL IDENTIFICATION OF AN ANCIENT SUPERNOVA USING LIGHT ECHOES IN THE LMC

We report the successful identification of the type of the supernova responsible for the supernova remnant SNR 0509-675 in the Large Magellanic Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to classify outbursts associated with centuries-old remnants provides a new window into several aspects of supernova research and is likely to be successful in providing new constraints on additional LMC supernovae as well as their historical counterparts in the Milky Way Galaxy (MWG). The combined spectrum of echo light from SNR 0509-675 shows broad emission and absorption lines consistent with a supernova (SN) spectrum. We create a spectral library consisting of 26 SNe Ia and 6 SN Ib/c that are time-integrated, dust-scattered by LMC dust, and reddened by the LMC and MWG. We fit these SN templates to the observed light echo spectrum using {chi}{sup 2} minimization as well as correlation techniques, and we find that overluminous 91T-like SNe Ia with {Delta}m{sub 15} < 0.9 match the observed spectrum best.
Date: February 7, 2008
Creator: Rest, A.; Matheson, T.; Blondin, S.; Bergmann, M.; Welch, D. L.; Suntzeff, N. B. et al.
Object Type: Article
System: The UNT Digital Library