17 Matching Results

Results open in a new window/tab.

Specialty Care: Heart Attack Survivors Treated by Cardiologists More Likely to Take Recommended Drugs (open access)

Specialty Care: Heart Attack Survivors Treated by Cardiologists More Likely to Take Recommended Drugs

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the potential differences in treatment patterns for health maintenance organizations (HMO) patients treated by specialists and those treated by generalist physicians, focusing on: (1) the proportion of Medicare heart attack survivors enrolled in HMOs who take cholesterol-lowering drugs, beta-blockers, and aspirin; and (2) whether Medicare heart attack survivors in HMOs regularly treated by a cardiologist are more likely to take cholesterol-lowering drugs, beta-blockers, and aspirin than those who do not have regular cardiology appointments."
Date: December 4, 1998
Creator: United States. General Accounting Office.
System: The UNT Digital Library
Linac Coherent Light Source (LCLS) Design Study Report (open access)

Linac Coherent Light Source (LCLS) Design Study Report

The Stanford Linear Accelerator Center, in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R and D facility operating in the wavelength range 1.5-15 {angstrom}. This FEL, called the ''Linac Coherent Light Source'' (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. Starting in FY 1998, the first two-thirds of the SLAC linac will be used for injection into the B factory. This leaves the last one-third free for acceleration to 15 GeV. The LCLS takes advantage of this opportunity, opening the way for the next generation of synchrotron light sources with largely proven technology and cost effective methods. This proposal is consistent with the recommendations of the Report of the Basic Energy Sciences Advisory Committee (Synchrotron Radiation Light Source Working Group, October 18-19, 1997). The report recognizes that ''fourth-generation x-ray sources...will in all likelihood be based on the free electron laser concepts. If successful, this technology could yield improvements in brightness by many orders of magnitude.'' This Design Study, the authors believe, confirms the feasibility of constructing an x-ray …
Date: December 4, 1998
Creator: Cornacchia, Massimo
System: The UNT Digital Library
Year 2000 Problem: Potential Impacts on National Infrastructures (open access)

Year 2000 Problem: Potential Impacts on National Infrastructures

The year 2000 (Y2K) computer problem poses a potential threat to the continued proper functioning of many national infrastructures. These include telecommunications, utilities, financial services, health care, transportation, government services, and military preparedness. Other sectors -- such as water, agriculture, food processing and distribution, emergency services, and small and medium sized businesses -- have also been identified as having potentially significant Y2K problems but, due to space constraints, are not discussed here. While public and private sector entities report progress toward resolving their Y2K problems, much uncertainty remains regarding which systems are most vulnerable to failures. The overall impact resulting from the Y2K problem to some degree still depends on remediation progress made in 1999.
Date: December 4, 1998
Creator: Nunno, Richard M.
System: The UNT Digital Library
Grazing Fees and Rangeland Management (open access)

Grazing Fees and Rangeland Management

The Bureau of Land Management (BLM, Department of the Interior) and the Forest Service (Department of Agriculture) manage approximately 70% of the 650 million acres of land owned by the federal government and many of these lands are classified as rangeland. Both agencies have well-established programs permitting private livestock grazing. The Administration issued new, controversial BLM rangeland management rules effective in August 1995. Supporters contended that the Administration's new rules were a step forward in sound resource management, but some believed they did not go far enough to protect rangelands and riparian areas. Many in the ranching community opposed the new rules, believing that they would ultimately reduce private livestock activity on federal lands, and increase operating costs. This report examines the debate over federal grazing management.
Date: December 4, 1998
Creator: Cody, Betsy A. & Baldwin, Pamela
System: The UNT Digital Library
Environmental Protection Agency: An Analysis of Key FY1999 Budget Issues (open access)

Environmental Protection Agency: An Analysis of Key FY1999 Budget Issues

On February 2, 1998, the President requested $7.8 billion for the Environmental Protection Agency (EPA) in FY1999. The Senate Appropriations Committee reported S. 2168 (S.Rept. 105-216) on June 12; the full Senate passed the bill on July 17. The House Committee reported H.R. 4194 (H.Rept. 105-610) on July 8, 1998; the full House passed it on July 29; and the Senate passed it on July 30 after incorporating S. 2168's provisions. During the week of October 6, the House and Senate approved the conference report, H.Rept. 105-769, which includes $7.5 billion, thus clearing the bill for the President's signature of October 21 (P.L. 105-276). The Omnibus Appropriations Act (P.L. 105-277) added $30 million more in FY1999 funds.
Date: December 4, 1998
Creator: Lee, Martin R.
System: The UNT Digital Library
Old F-Area Seepage Basin Transport Analyses in Support of a SCDHEC Mixing Zone Application (open access)

Old F-Area Seepage Basin Transport Analyses in Support of a SCDHEC Mixing Zone Application

This report documents the groundwater flow and transport results presented in the groundwater mixing zone application (GWMZ) for the Old F-Area Seepage Basin (OFASB) submitted to the South Carolina Department of Health and Environmental Control (SCDHEC) in March, 1997 (WSRC, 1997).
Date: December 4, 1998
Creator: Aleman, S. E.
System: The UNT Digital Library
Hindered Diffusion of Asphaltenes at Evaluated Temperature and Pressure (open access)

Hindered Diffusion of Asphaltenes at Evaluated Temperature and Pressure

During this time period, uptake experiments were performed at elevated temperatures up to 280 o C for the adsorptive diffusion of a coal asphaltene in 1- methylnaphthalene onto alumina catalyst pellets. Model simulation results showed that a mathematical model incorporating diffusion and adsorption mechanisms satisfactorily fitted the adsorptive diffusion of coal asphaltenes onto the alumina catalyst in a fairly wide temperature range of 55 o C to 280 o C. The logarithm of the adsorption constant, obtained by simulating the experimental data with the model solution, was found to be linearly dependent on temperature. As temperature increased, the value of the adsorption constant decreased. On the other hand, the effective diffusivity of the asphaltene increased with temperature. These off-setting temperature dependencies resulting from the adsorption constant and the effective diffusivity compensated at least to some extent in the uptake process.
Date: December 4, 1998
Creator: Guin, James A.; Vadlamani, Surya & Yang, Xiafeng
System: The UNT Digital Library
Effects of Aging Quartz Sand and Hanford Site Sediment with Sodium Hydroxide on Radionuclide Sorption Coefficients and Sediment Physical and Hydrologic Properties: Final Report for Subtask 2a (open access)

Effects of Aging Quartz Sand and Hanford Site Sediment with Sodium Hydroxide on Radionuclide Sorption Coefficients and Sediment Physical and Hydrologic Properties: Final Report for Subtask 2a

Column and batch experiments were conducted in fiscal year 1998 at Pacific Northwest National Laboratory to evaluate the effect of varying concentrations of NaOH on the sorptive, physical, and hydraulic properties of two media, a quartz sand and a composite subsurface sediment from the 200-East Area of the Hanford Site. The NaOH solutions were used as a simplified effluent from a low-activity glass waste form. These experiments were conducted over a limited (O-to 10-month) contact time, with respect to the 10,000-to 100,000-year scenarios described in the Immobilized Low-Activity Waste- Performance Assessment (ILAW-PA). Wheq these two solids were put in contact with the NaOH solutions, dissolution was evident by a substantial increase in dissolved Si concentrations in the leachates. Incremental increases in NaOH con- centrations, resulted in corresponding increases in Si concentrations. A number of physical and hydraulic properties also changed as the NaOH concentrations were changed. It was observed that quartz sand was less reactive than the composite sediment. Further, moisture- retention measurements were made on the quartz sand and composite sedimen$ which showed that the NaOH-treated solids retained more water than the non-NaOH-treated solids. Because the other chemical, physical, and hydraulic measurements did not change dramatically after the high-NaOH …
Date: December 4, 1998
Creator: Kaplan, DI; Ritter, JC & Parker, KE
System: The UNT Digital Library
Develop improved metal hydride technology for the storage of hydrogen. Final technical report (open access)

Develop improved metal hydride technology for the storage of hydrogen. Final technical report

The overall objective was to develop commercially viable metal hydrides capable of reversibly storing at least 3 wt.% hydrogen for use with PEM fuel cells and hydrogen fueled internal combustion engine (HICE) applications. Such alloys are expected to result in system capacities of greater than 2 wt.%, making metal hydride storage systems (MHSS`s) a practical means of supplying hydrogen for many consumer applications. ECD`s (Energy Conversion Devices, Inc.) past work on sputtered thin films of transition metal-based alloys led to the commercialization of it`s nickel/metal hydride batteries, and similar work on thin film Mg-based alloys demonstrated potential to achieve very high gravimetric and volumetric energy densities approaching 2,500 Wh/Kg and 2,500 Wh/M{sup 3} respectively. Under this 2-year cost shared project with the DOE, the authors have successfully demonstrated the feasibility of scaling up the Mg-based hydrides from thin film to bulk production without substantial loss of storage capacity. ECD made progress in alloy development by means of compositional and process modification. Processes used include Mechanical Alloying, Melt spinning and novel Gas Phase Condensation. It was showed that the same composition when prepared by melt-spinning resulted in a more homogeneous material having a higher PCT plateau pressure as compared to mechanical …
Date: December 4, 1998
Creator: Sapru, K.
System: The UNT Digital Library
Catalytic Gasification of Coal using Eutectic Salt Mixtures (open access)

Catalytic Gasification of Coal using Eutectic Salt Mixtures

The objectives of this study are to: identify appropriate eutectic salt mixture catalysts for coal gasification; assess agglomeration tendency of catalyzed coal; evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; evaluate the recovery, regeneration and recycle of the spent catalysts; and conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process. A review of the collected literature was carried out. The catalysts which have been used for gasification can be roughly classified under the following five groups: alkali metal salts; alkaline earth metal oxides and salts; mineral substances or ash in coal; transition metals and their oxides and salts; and eutectic salt mixtures. Studies involving the use of gasification catalysts have been conducted. However, most of the studies focused on the application of individual catalysts. Only two publications have reported the study of gasification of coal char in CO2 and steam catalyzed by eutectic salt mixture catalysts. By using the eutectic mixtures of salts that show good activity as individual compounds, the gasification temperature can be reduced possibly with still better …
Date: December 4, 1998
Creator: Sheth, Atul; Agrawal, Pradeep & Yeboah, Yaw D.
System: The UNT Digital Library
Residues From Coal Comversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagensesis (open access)

Residues From Coal Comversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagensesis

The goals of the project are two-fold: 1) to upgrade semi-quantitative X-ray diffraction(QXRD) methods presently used in analyzing complex coal combustion by-product (CCB)systems, with the quantitative Rietveld method, and 2) to apply this method to a set of by-product materials that have been disposed or utilized for a long period (5 years or more) in contact with the natural environment, to further study the nature of CCB diagenesis. The project is organized into three tasks to accomplish these two goals: 1) thorough characterization of a set of previously analyzed disposed by-product materials, 2) development of a set of CCB specific protocols for Rietveld QXRD, and 3) characterization of an additional set of disposed CCB materials, including application of the protocols for Rietveld QXRD developed in Task 2.
Date: December 4, 1998
Creator: McCarthy, Gregory J.
System: The UNT Digital Library
Surface Modified Coals for Enhanced Catalyst Dispersion and Liquefaction (open access)

Surface Modified Coals for Enhanced Catalyst Dispersion and Liquefaction

The aim of this study is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on to the coal. During this reporting period, the effects of dodecyl dimethyl ethyl ammonium bromide (DDAB) (a cationic surfactant), sodium dodecyl sulfate (SDS) (an anionic surfactant), Triton X-100 (a neutral surfactant), and ferrous sulfate (as a catalyst precursor) on the coal surface charge at various pH values were determined. The results of the zeta potential measurements suggest that ferrous sulfate as catalyst precursor creates a distinctly different condition on the coal surface compared to that of molybdenum as reported in the previous progress reports. The effects of the adsorption of the surfactants also varied distinctly with the type of surfactant. With the adsorption of DDAB, the cationic surfactant, the surface charge was more positive. The opposite effect was observed for the SDS, the anionic surfactant. The coals treated with Triton X-100, the neutral surfactant, also showed an overall negative surface charge density. The adsorption of the catalyst precursor (ferrous sulfate) resulted in a net negative charge on the coal surface.
Date: December 4, 1998
Creator: Yeboah, Yaw D.
System: The UNT Digital Library
Surface Modified Coals for Enhanced Catalyst Dispersion and Liquefaction (open access)

Surface Modified Coals for Enhanced Catalyst Dispersion and Liquefaction

The aim of this study is to enhance catalyst loading and dispersion in coal for improved liquefaction by preadsorption of surfactants and catalysts on to the coal. During this reporting period, liquefaction experiments were conducted with the raw coal and catalyst loaded samples. Pretreatment of the coal and catalyst-loaded samples were done using the surfactants presented in previous reports. Liquefaction samples were tested using 6.6 g of solvent, 3.3 g coal, 6.9 MPa ambient hydrogen pressure, 425 0 C and 30 minutes. The liquid and solid products were removed from the reactor using tetrahydrofuran (THF). Coal conversions were calculated based on THF and heptane solubility. The results showed that in the absence of a catalyst, 33.8% heptane solubles was obtained with the parent coal compared to 27.8% and 27.3% with the SDS and DDAB surfactants. The presence of molybdenum, as expected, resulted in enhanced heptane solubles with or without surfactants. In the absence of surfactants, 50% heptane solubles was obtained compared to 40-47% with surfactants. Thus, it appears that pretreatment, unexpectedly, had a negative effect on liquefaction activity. It is unclear if the observed differences in results are significant. Clearly, additional experiments are needed before any firm deductions and conclusions …
Date: December 4, 1998
Creator: Yeboah, Yaw D.
System: The UNT Digital Library
Ion Chromatography Analysis of Dibutyl Phosphoric Acid (open access)

Ion Chromatography Analysis of Dibutyl Phosphoric Acid

Analysis of dibutyl phosphate (DBP), a degradation product of tributyl phosphate (TBP), has long been a problem analysis by Ion Chromatography at the Savannah River Site. Due to the presence of UO{sub 2}{sup +2} and high NO{sub 3}{sup {minus}1} concentrations, inadequate recovery and separation of DBP on the chromatographic column had rendered the analysis undependable and very inconsistent, thus causing high uncertainties in the data. The method presented here by the Savannah River Technology Center (SRTC)/Analytical Development Section (ADS) addresses the sample preparation problems encountered when analyzing for DBP in the presence of uranium and nitrate. The data presented reflects the improvements made to decrease data uncertainty and increase data accuracy and precision.
Date: December 4, 1998
Creator: Ray, R.J.
System: The UNT Digital Library
Criticality Safety Envelope for Receipt, Handling, and Storage of Transuranic Waste (open access)

Criticality Safety Envelope for Receipt, Handling, and Storage of Transuranic Waste

Current criticality safety limits for Solid Waste Management Facility (SWMF) Transuranic (TRU) Waste Storage Pads are based on analysis of systems where mass is the only independent parameter and all other parameters are assumed at their most reactive values (Ref. 1). These limits result in administrative controls (i.e., limit stacking of containers, coordination of drums for culvert storage based on individual drum fissile inventories, and mass limits for accumulation of polyethylene boxes in culverts) which can only be met by redundant SWMF administrative controls. These analyses did not credit the nature of the waste generator process that would provide bounding limits on the other parameters (i.e. less than optimal moderation and configurations within packages (containers)). They also did not indicate the margin of safety associated with operating to these mass limits. However, by crediting the waste generator processes (and maintaining such process assumptions via controls in the criteria for waste acceptance) sufficient margin of safety can be demonstrated to justify continued SWMF TRU pad operation with fewer administrative controls than specified in the Double Contingency analysis (DCA) (Ref. 1).
Date: December 4, 1998
Creator: Vincent, A.M.
System: The UNT Digital Library
Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis (open access)

Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

The goals of the project are two-fold: 1) to upgrade semi-quantitative X-ray diffraction(QXRD) methods presently used in analyzing complex coal combustion by-product (CCB)systems, with the quantitative Rietveld method, and 2) to apply this method to a set of by-product materials that have been disposed or utilized for a long period (5 years or more) in contact with the natural environment, to further study the nature of CCB diagenesis. The project is organized into three tasks to accomplish these two goals: 1) thorough characterization of a set of previously analyzed disposed by-product materials, 2) development of a set of CCB specific protocols for Rietveld QXRD, and 3) characterization of an additional set of disposed CCB materials, including application of the protocols for Rietveld QXRD developed in Task 2.
Date: December 4, 1998
Creator: McCarthy, Gregory J.
System: The UNT Digital Library
Nondestructive NMR technique for moisture determination in radioactive materials. (open access)

Nondestructive NMR technique for moisture determination in radioactive materials.

This progress report focuses on experimental and computational studies used to evaluate nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) for detecting, quantifying, and monitoring hydrogen and other magnetically active nuclei ({sup 3}H, {sup 3}He, {sup 239}Pu, {sup 241}Pu) in Spent nuclear fuels and packaging materials. The detection of moisture by using a toroid cavity NMR imager has been demonstrated in SiO{sub 2} and UO{sub 2} systems. The total moisture was quantified by means of {sup 1}H NMR detection of H{sub 2}O with a sensitivity of 100 ppm. In addition, an MRI technique that was used to determine the moisture distribution also enabled investigators to discriminate between bulk and stationary water sorbed on the particles. This imaging feature is unavailable in any other nondestructive assay (NDA) technique. Following the initial success of this program, the NMR detector volume was scaled up from the original design by a factor of 2000. The capacity of this detector exceeds the size specified by DOE-STD-3013-96.
Date: December 4, 1998
Creator: Aumeier, S.; Gerald, R. E., II; Growney, E.; Nunez, L. & Kaminski, M.
System: The UNT Digital Library