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Measurements of Non-Leptonic Weak Decays of Lambda Hypernuclei

Description: Aspects of recent measurements of the mesonic and non-mesonic partial decay rates of {sub {Lambda}}{sup 5}He, and {sub {Lambda}}{sup 12}C are discussed. We comment on what the experiments tell us about the spin-isospin structure of {Delta}S=1 weak interaction in the nuclear environment. 14 refs., 1 fig.
Date: January 1, 1991
Creator: Schumacher, Reinhard A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Exploring novel silicon-containing polymers---From preceramic polymers to conducting polymers with nonlinear optical properties

Description: Several new types of silicon-containing preceramic polymers, i.e., poly(diorganosilacetylene) and poly(diorganosilvinylene) have been synthesized with molecular weights from 10,000 to 120,000. These polymers could be thermally converted to SiC with a moderate to high char yields. Ready solubility and good processability made these types of polymers attractive in their applications to ceramics. The thermal polymerization of diethynyldiphenyl-silane, which was reported in 1968 to afford poly(diph… more
Date: October 7, 1991
Creator: Pang, Yi.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The bioenergetics of salt tolerance

Description: The aim of this project was to try to understand the adaptive mechanisms that organisms develop in order to respond to a sudden transformation in their environment to a salt shock.'' To study this problem we used a fresh water oxygenic photosynthetic cyanobacterium known as Synecoccus 6311. This organism suffers injury after this sudden exposure to high concentrations of sodium chloride equivalent to or even higher than that in sea water. Yet they are able to re-establish their photosynthetic a… more
Date: January 1, 1991
Creator: Packer, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ceramic technology for Advanced Heat Engines Project

Description: Significant accomplishments in fabricating ceramic components for advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and database and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine… more
Date: July 1, 1991
Creator: Johnson, D. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Molecular interactions in dilute supercritical mixtures: Molecular dynamics investigation

Description: We performed a series of molecular dynamics simulations aimed at investigating the nature of the microstructure around solute molecules in a supercritical solvent, in the limit of infinite dilution (no solute-solute interactions). The choice of model system (pyrene in supercritical carbon dioxide) and state conditions (5--20 moles/liter; 37{degrees}C and 75{degrees}C) was done so as to match corresponding fluorescence experiments performed at Georgia Tech. 18 refs., 3 figs.
Date: January 1, 1991
Creator: Debenedetti, P.G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches

Description: Semiempirical interatomic potentials are developed for silicon and carbon by modeling the total energy of the system using tight-binding approaches. The parameters of the models were obtained by fitting to results from accurate first-principles Local Density Functional calculations. Applications to the computation of phonons as a function of volume for diamond-structured silicon and carbon and the thermal expansions for silicon and diamond yields results which agree well with experiment. The ph… more
Date: October 25, 1991
Creator: Xu, Chunhui.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A replaceable reflective film for solar concentrators

Description: The 3M Company manufactures a silvered acrylic film called ECP-305 that is regarded as the preferred reflective film for use on stretched-membrane heliostats. However, ECP-305 will degrade in time, due to both corrosion of the silver layer and delamination at the film's silver-to-acrylic interface, and will eventually need to be replaced. 3M uses a very aggressive adhesive on this film, and once it is laminated, replacement is very difficult. The purpose of this investigation was the developmen… more
Date: September 1, 1991
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Creep of whisker-reinforced ceramics

Description: The results of high-temperature creep of various ceramic composites will be reviewed. In particular, creep results for Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} matrices reinforced with SiC whiskers will be emphasized. For a given temperature, stress and grain size, the creep rate of the Al{sub 2}O{sub 3} composite is usually lower than that of the ceramic matrix. In general, creep at low stresses occurs by grain boundary sliding accommodated by diffusion, whereas higher stresses lead to damage a… more
Date: January 1, 1991
Creator: Routbort, J.L; Goretta, K.C. (Argonne National Lab., IL (United States)); Dominguez-Rodriguez, A. & de Arellano-Lopez, A.R. (Seville Univ. (Spain))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Steroselective synthesis and application of L-( sup 15 N) amino acids

Description: We have developed two general approaches to the stereoselective synthesis of {sup 15}N- and {sup 13}C-labeled amino acids. First, labeled serine, biosynthesized using the methylotrophic bacterium M. extorquens AM1, serves as a chiral precursor for the synthesis of other amino acids. For example, pyridoxal phosphate enzymes can be used for the conversion of L-({alpha}-{sup 15}N)serine to L-({alpha}-{sup 15}N)tyrosine, L-({alpha}-{sup 15}N)tryptophan, and L-({alpha}-{sup 15}N)cysteine. In the sec… more
Date: January 1, 1991
Creator: Unkefer, C.J. (Los Alamos National Lab., NM (United States)) & Lodwig, S.N. (Centralia Coll., WA (United States). Div. of Science)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Weldon Spring quarry construction staging area and water treatment plant site remedial action characterization report for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

Description: The quarry construction staging area (QCSA) and water treatment plant (WTP) are located in the areas that border the western edge of the Weldon Spring quarry (WSQ). These facilities were constructed to support bulk waste removal from the WSQ. This area was contaminated with U-238, Ra-226, and Th-230 and was remediated prior to construction in order to allow release of the area for use without radiological restrictions. This report documents the methods of characterization, the remediation activ… more
Date: September 1, 1991
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Reactivity of Young Chars via Energetic Distribution Measurements

Description: In this report, we present some preliminary work performed on the effect of CO{sub 2} partial pressure on temperature programmed desorption spectra from CO{sub 2}-oxidized chars. The following was accomplished during the reporting period: Temperature programmed desorption (TPD) experiments were conducted on oxidized resin and Wyodak coal char samples gasified under varying different CO{sub 2} partial pressures. The following observations were made: CO{sub 2} partial pressure can be an important… more
Date: January 1, 1991
Creator: Calo, J. M.; Zhang, L. H.; Rachel, W. G. & Lilly, W. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Engineering considerations of the advanced free electron laser facility

Description: The Advanced Free-Electron Laser (AFEL) is being built at Los Alamos inside a large laboratory building. In addition to cost and available space considerations, several engineering issues affected the design of the AFEL and its facility. The 1300-MHz, 20-MeV electron linac required extensive radiation shielding and a short rf-waveguide run. Free-Electron Lasers (FEL) and photocathode-drive laser optics required a clean, constant temperature environment. New environmental, health, and safety (ES… more
Date: January 1, 1991
Creator: Meier, K.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The carbon isotopic composition of atmospheric methane and its sources and trends; distribution of source fluxes and their contribution to the increasing concentration

Description: The goal of isotopic studies of atmospheric methane is the determination of the relative fluxes of the various sources of different isotopic composition. Because of the large number of generic anthropogenic source types it is not possible to determine their relative strengths based on carbon-13 data alone. However, by combining sources of similar isotopic composition (as well as similar origin), and utilizing results from other studies it is possible to calculate some important features of the … more
Date: January 1, 1991
Creator: Stevens, C.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Quantitative nondestructive density determinations of very low-density carbon foams

Description: The carbon density and the carbon distribution in low-density foams that were manufactured by a modified salt-replica process were determined by bulk measurements of weight and volume and by x-ray computed tomography (CT). When determining the carbon density, both methods yielded similar results, however, the high spatial resolution of CT was found to yield nondestructive quantitative information on the carbon distribution that was not available from bulk measurements. The highest and lowest fo… more
Date: January 1, 1991
Creator: Moddeman, W. E.; Kramer, D. P.; Firsich, D. W.; Trainer, P. D.; Back, P. S.; Smith, S. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Composition of phytoplankton communities and their contribution to secondary productivity in Carolina Bays on the Savannah River Plant

Description: The overall goal of the this three year project is to determine the importance of phytoplankton (microscopic algae) as a component of the food chain base in SRS cardine bays. To summarize specific year three results: Total phytoplankton abundance in Flamingo bay was greatest during early spring 1989, declined during spring and summer, but increased again during early fall. Most of this phytoplankton density was composed of genus Chlamydomonas sp. Ellenton bay demonstrated a similar decline in p… more
Date: August 1, 1991
Creator: Williams, J.B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Simulation of the carbon cycle in the ocean

Description: A dual carbon-nitrogen biological model of the upper ocean has been developed, which has successfully allowed predictions of fluxes of carbon between atmosphere and the deep ocean to made. Regarding studying the carbon cycle in the ocean, the modelling has highlighted the need for a good understanding of the interactions between the carbon and nitrogen cycles, and also the importance of zooplankton grazing and levels of overwintering biological stocks. Problems have been encountered with the ac… more
Date: September 16, 1991
Creator: Fasham, M.J.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Corrosion of SiC and oxide-composite ceramics by a simulated steam-reformer atmosphere

Description: To achieve higher process efficiency by using pressurized reactants and/or heat transfer fluids, the US DOE is promoting development of high-pressure heat exchanger systems under cost-sharing agreements with industrial contractors. The steam reformer would contain more than 600 tubes. Because the combination of high temperature and pressure differential of 12.7 kg/cm{sup 2} (180 psig) across the tube wall is too severe for metallic tubes, ceramic materials are being considered for reformer tube… more
Date: September 1, 1991
Creator: Federer, J.I.; Kim, H.E. & Moorhead, A.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Study of the corrosion rate behavior of ion implanted Fe-based alloys

Description: We report on some studies we have made of the time evolution of the corrosion behavior of ion implanted samples of pure iron, medium carbon steel, and 18-8 Cr-Ni stainless steel. Ti, Cr, Ni, Cu, Mo and Yb were implanted at mean ion energies near 100 keV and at doses up to 1 {times} 10{sup 17} cm{sup {minus}2} using a Mevva metal ion implantation facility. A novel feature of this experiment was the simultaneous implantation with several different implanted species. The implanted samples were imm… more
Date: June 1, 1991
Creator: Weiping, Cai; Wei, Tian; Wu Run (Wuhan Iron and Steel Univ., HB (China)); Godechot, X. & Brown, I. (Lawrence Berkeley Lab., CA (United States))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dispersion aspects of silicon carbide gelcasting

Description: The principal objective of this research was to increase the solid loading of silicon carbide (SiC) powder, in an appropriate liquid medium, to a level that is useful for gelcasting technology. A number of factors that determine the maximum concentration of silicon carbide that can be incorporated into a pourable ceramic suspension have been identified. The pH of the system is the most critical processing parameter. Its proper adjustment (pH 11 to 13) allows SiC concentrations exceeding 50%, ba… more
Date: September 1, 1991
Creator: Bleier, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A novel process for methanol synthesis

Description: A bench-scale reactor is being used to conduct studies of the conversion of synthesis gas to methanol by a novel process. During the last quarter, we provided evidence for a two step reaction in series as against the direct hydrogenation of CO. We believe that the carbonylation reaction takes place in the liquid phase adjacent to the solid catalyst surface while the hydrogenolysis reaction is restricted to the surface of Cu-chromite. A non-equilibrium film model was proposed to explain the unex… more
Date: January 1, 1991
Creator: Tierney, J.W. & Wender, I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Binding and catalytic reduction of NO by transition metal aluminosilicates

Description: The objective of this research is to provide the scientific understanding of processes that actively and selectively reduce NO in dilute exhaust streams, as well as in concentrated streams, to N{sub 2}. Experimental studies of NO chemistry in transition metal-containing aluminosilicate catalysts are being carried out with the aim of determining the chemical rules for NO reduction on non-precious metals. The catalyst supports chosen for this investigation are A and Y zeolites, mordenite, and mon… more
Date: September 1, 1991
Creator: Klier, Kamil; Herman, Richard G. & Hou, Shaolie
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Minimum detectable activities of contamination control survey equipment

Description: The Instrumentation External Dosimetry (I ED) Section of the Health Physics Department at the Pacific Northwest Laboratory (PNL) has performed a series of tests to determine the ability of portable survey instruments used at Hanford to detect radioactive contamination at levels required by DOE 5480.11. This semi-empirical study combines instrumental, statistical, and human factors as necessary to derive operational detection limits. These threshold detection values have been compared to existin… more
Date: August 1, 1991
Creator: Goles, R. W.; Baumann, B. L. & Johnson, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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In-Home Performance of Exempt Pellet Stoves in Medford, Oregon.

Description: Pellet stoves that are considered exempt'' operate at an air-to-fuel ratio in excess of 35:1. They therefore qualify for exemption from the emissions certification process. A primary goal of this project was to determine how a sample of such stoves, operated in homes, would perform compared to their certified cousins,'' which were evaluated the previous year. In-home performance data documenting emissions from exempt stoves and net delivered efficiencies was particularly desired. This project e… more
Date: July 5, 1991
Creator: Barnett, Stockton G. & Fields, Paula G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Pion-induced scattering above the 3,3 resonance

Description: Results of Gluaber model calculations of elastic, inelastic, single- and double-charge exchange reactions from light nuclei of pions having energy of 300 to 1200 MeV are presented. Experimental {pi}N phase shifts including {ell}=0 through 5 were used in the calculation. 25 refs., 6 figs.
Date: January 1, 1991
Creator: Oset, E. (Valencia Univ. (Spain)) & Strottman, D. (Los Alamos National Lab., NM (United States))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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