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X-ray Analysis of the Uranium-Carbon System

Description: The following report includes an account of the X-ray structures of all he uranium-carbides together with X-ray data on the solid solubilities of these carbides with each other and with uranium and carbon.
Date: 1948
Creator: Rundle, R. E.; Wilson, A. S. & Baenziger, Norman C.
Partner: UNT Libraries Government Documents Department

The Boron-Carbon System: Final Technical Report, May 1, 1960 - April 30, 1961

Description: Abstract: The boron-carbon equilibrium diagram has been determined by X-ray, metallographic, and thermal analysis of sintered and arc-cast alloys. A single carbide having a range of solubility from approximately 9 to 20 a/o carbon and melting congruently exists in the system. The terminal solubility of carbon in boron is 0.1-0.2a/o. The freezing reaction at the composition and melting temperature of elemental boron; there is a eutectic reaction at 29a/o carbon and 2375 degrees Celcius. No allotropy of boron was observed.
Date: June 7, 1961
Creator: Elliott, Rodney P.
Partner: UNT Libraries Government Documents Department

The Boron-Carbon System: Quarterly Report No. 1, May 1, 1960 - June 31, 1960

Description: Abstract: A definitive investigation of the boron-carbon equilibrium system is being made by X-ray diffraction, metallographic, and thermal analytical techniques. Alloys are being produced by sintering pressed powder aggregates with subsequent arc melting. Alloys have been made at two atomic percent intervals up to thirty atomic per cent carbon. In the future, higher carbon compositions are to be investigated. Techniques have been worked out for the metallographic preparation of the extremely hard and friable alloys.
Date: August 5, 1960
Creator: Elliott, Rodney P. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

The Boron-Carbon System: Quarterly Report No. 2, August 1, 1960 - October 31, 1960

Description: Abstract: A definitive investigation of the boron-carbon equilibrium system is being made by X-ray diffraction, metallographic, and thermal analytical techniques. Additional baron-carbon alloys have been prepared by sintering and arc-melting compacts prepared from boron and high-purity graphite. Metallographic examinations of these alloys are in agreement with alloys previously preapred from lampblack. X-ray investigation of sintered compacts indicates that the solubility range of boron carbide extends almost to pure boron. Boron of various purities has been annealed for times up to four hours, but no structure other than beta-rhombohedral has been detected. Very high purity boron (10 ppm impurity) has been obtained for the study of allotropy and the equilibrium relationships at very dilute carbon contents.
Date: November 8, 1960
Creator: Elliott, Rodney P. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

The Boron-Carbon System: Quarterly Report No. 3, November 1, 1960 - January 31, 1961

Description: Abstract: A definitive investigation of the boron-carbon equilibrium system is being made by X-ray diffraction, metallographic, and thermal analytical techniques. On the basis of metallographic and X-ray diffraction studies it is concluded that boron carbide has a range of solubility from approximately 10 to 20 atomic per cent carbon at 1500 degrees to 2000 degrees Celsius. The melting point of the carbide-graphite eutectic has been established as 2325-2350 degrees Celsius. No reversible allotropy of the beta-rhombohedral structure has been observed. The solubility of carbon in boron is very small. The melting point of dilute carbon alloys is found to be essentially the same as that of pure boron (2040 degrees to 2050 degrees). No metallographic evidence of a three-phase reaction of dilute alloys is observed.
Date: February 6, 1961
Creator: Elliott, Rodney P.
Partner: UNT Libraries Government Documents Department

Niobium Phase Diagrams : Manuscript Report on Niobium-Carbon System

Description: Abstract: "The niobium-carbon system has been determined by X-ray and metallographic examination of sintered and arc-cast alloys. Two carbides exist: hexagonal Nb2C with a limited range of homogeneity, and cubic NbC with a solubility range from 8.25 to 10.25 weight per cent carbon. Dilute alloys freeze by eutectic reaction at 2230 C. The solubility of carbon in niobium is 0.80 at the eutectic temperature, but this decreases rapidly with temperature. Metallographic evidence indicates a peritectic reaction between melt, Nb2C, and NbC; alloys richer in carbon than NbC freeze by eutectic reaction."
Date: May 6, 1959
Creator: Elliott, Rodney P.
Partner: UNT Libraries Government Documents Department

Carbon Flux in Reservoir Sediments

Description: The central objective of the study was to fractionate sedimenting organic materials according to their source (allochthonous or autochthonous) and ultimately to determine the degree of biodegradability of contributions from either source with particular reference to activities at the mud-water interface.
Date: May 1973
Creator: Newton, Charles Eugene
Partner: UNT Libraries

Qualification Approval Tests on resistance products Co.`s type {open_quotes}H{close_quotes} Carbon Composition resistors (0.2 and 40 Megohm)

Description: Engineering Work Requests ESE-48 & 49 established a program for performance of Qualification Approval Tests on RPC`s 0.2 and 40 meghom Carbon Composition Resistors. This report is an accounting of these tests wherein (50) samples of each component were subjected to QA tests per drawings 8O2C250 and 802C251. Tests are explained and results tabulated.
Date: March 25, 1960
Creator: Dixon, L.W.
Partner: UNT Libraries Government Documents Department

Stability of eutectic interface during directional solidification

Description: Directional solidification of eutectic alloys shows different types of eutectic morphologies. These include lamellar, rod, oscillating and tilting modes. The growth of these morphologies occurs with a macroscopically planar interface. However, under certain conditions, the planar eutectic front becomes unstable and gives rise to a cellular or a dendritic structure. This instability leads to the cellular/dendritic structure of either a primary phase or a two-phase structure. The objective of this work is to develop a fundamental understanding of the instability of eutectic structure into cellular/dendritic structures of a single phase and of two-phases. Experimental studies have been carried out to examine the transition from a planar to two-phase cellular and dendritic structures in a ceramic system of Alumina-Zirconia (Al{sub 2}O{sub 3}-ZrO{sub 2}) and in a transparent organic system of carbon tetrabromide and hexachloroethane (CBr{sub 4}-C{sub 2}Cl{sub 6}). Several aspects of eutectic interface stability have been examined.
Date: April 23, 1996
Creator: Han, S.H.
Partner: UNT Libraries Government Documents Department

A theoretical study of a carbon lattice system for lithium intercalated carbon anodes

Description: A theoretical study was performed using computational chemistry to describe the intermolecular forces between graphite layers as well as spacing and conformation. It was found that electron correlation and a diffuse basis set were important for this calculation. In addition, the high reactivity of edge sites in lithium intercalated carbon anodes was also investigated. In this case, the reactive sites appear to strongly correlate with the relative distribution of the total atomic spin densities as well as total atomic charges. The spacing of graphite layers and lithium ion separation within an {open_quotes}approximated{close_quotes} lithium intercalated carbon anode was also investigated. The spacing of the carbon layers used in this investigation agrees most closely for that found in disordered carbon lattices.
Date: September 1, 1997
Creator: Scanlon, L.G.; Storch, D.M.; Newton, J.H. & Sandi, G.
Partner: UNT Libraries Government Documents Department

Chemical Evolution and the Origin of Life

Description: The formation of more complex carbon compounds from simple ones through the action of radiation is used in an interpretation of the original formation of such compounds on earth. The relation of plants and animals and evolution of photosynthesis is discussed in the light of the participation of sulfur compounds in the metabolism of both group.
Date: March 10, 1953
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Estimation of brassylic acid by gas chromatography-mass spectrometry

Description: The main focus of this work is to estimate Brassylic Acid (BA) using gas chromatography-mass spectrometry (GC-MS). BA is a product obtained from the oxidative cleavage of Erucic Acid (EA). BA has various applications for making nylons and high performance polymers. BA is a 13 carbon compound with two carboxylic acid functional groups at the terminal end. BA has a long hydrocarbon chain that makes the molecule less sensitive to some of the characterization techniques. Although BA can be characterized by NMR, both the starting material (EA) and products BA and nonanoic acid (NA) have peaks at similar {delta}, ppm values. Hence it becomes difficult for the quick estimation of BA during its synthesis.
Date: October 29, 2010
Creator: Mohammed J. Nasrullah, Erica N. Pfarr, Pooja Thapliyal, Nicholas S. Dusek, Kristofer L. Schiele, Christy Gallagher-Lein, and James A. Bahr
Partner: UNT Libraries Government Documents Department

HIGH INTENSITY LIGHT SOURCES (Part II of Thesis)

Description: A stable carbon arc operated in controlled atmosphere is described. The arc was designed to serve as a light source during lifetime studies of the B/sup 2/ SIGMA state of the CN molecule. The CN radiation from the plasma of the arc was investigated and found to have a brightness temperature of 5500 icient laborato K at lambda 3883 A. This is considerably higher than an estimate of the value required for lifetime measurements. The stability of the carbon arc under various conditions is discussed. For successful lifetime measurements, the light source employed must have a high brightness temperature (intensity). A method for the determination of the brightness temperature of a light source at a specific wave length is described. The method was used for determining the brightness temperatures of some available light sources. Sodium, thallium, and mercury discharge lamps, a medium-pressure mercury arc lamp, and the carbon arc were studied. (auth)
Date: October 1, 1958
Creator: Worden, E.F. Jr.
Partner: UNT Libraries Government Documents Department

Degradation of Complex Carbon Compounds by Marine Actinomycetes

Description: The purpose of this paper is to present a comparative study of marine bacteria, molds and actinomycetes in regard to their ability to degrade certain pure and mixed complex compounds possibly occurring in the lagoon waste traps of the Texas Gulf Coast. This comparison was made using a differential oxygen uptake as the index of specific compound utilization.
Date: August 1959
Creator: Willingham, Charles Allen
Partner: UNT Libraries

Inelastic neutron studies of the low energy phonon excitations in the RENi{sub 2}B{sub 2}C superconductors (RE=Lu,Y,Ho,Er)

Description: We studied the low-energy phonon excitations for wavevectors close to the Fermi surface nesting vector {xi}{sub m} = 0.55 a vector. We find that above T{sub c} the frequencies of the {Delta}{sub 4} [{zeta}00] lowest-lying optical and acoustic phonon modes decrease with decreasing temperature, for {xi} close to {xi}{sub m}, and there is a shift of intensity from the upper to the lower mode, an effect characteristic of coupled modes. From approximately 120K down to temperatures in the vicinity of T{sub c}, only a single unresolved peak is observed. Below Tc the phonon spectra of the Y and Lu compounds change dramatically: it consists of a sharp peak at approximately 4.5 meV with a weak shoulder at the higher energy side. No such sharp peak was observed below T{sub c} in the Ho and Er compounds.
Date: August 1, 1997
Creator: Bullock, M.; Stassis, C.; Zarestky, J.; Goldman, A.; Canfield, P.; Shirane, G. et al.
Partner: UNT Libraries Government Documents Department

The genome of Methylobacillus flagellatus, the molecular basis forobligate methylotrophy, and the polyphyletic origin ofmethylotrophy

Description: Along with methane, methanol and methylated amines representimportant biogenic atmospheric constituents, thus not only methanotrophs,but also non-methanotrophic methylotrophs play a significant role inglobal carbon cycling. The complete genome of a model obligate methanoland methylamine utilizer, Methylobacillus flagellatus (strain KT) wassequenced. The genome is represented by a single circular chromosome ofapproximately 3 Mb pairs, potentially encoding a total of 2,766 proteins.Based on genome analysis as well as the results from previous genetic andmutational analyses, methylotrophy is enabled by methanol- andmethylamine dehydrogenases, the tetrahydromethanopterin-linkedformaldehyde oxidation pathway, the assimilatory and dissimilatorybranches of the ribulose monophosphate cycle, and by formatedehydrogenases. Some of the methylotrophy genes are present in more thanone (identical or non-identical) copy. The obligate dependence on singlecarbon compounds appears to be due to the incomplete tricarboxylic acidcycle, as no genes potentially encoding alpha ketoglutarate, malate orsuccinate dehydrogenases are identifiable. The genome of M. flagellatuswas compared, in terms of methylotrophy functions, to the previouslysequenced genomes of three methylotrophs: Methylobacterium extorquens(Alphaproteobacterium, 7 Mbp), Methylibium petroleophilum(Betaproteobacterium, 4 Mbp), and Methylococcus capsulatus(Gammaproteobacterium, 3.3 Mbp). Strikingly, metabolically and/orphylogenetically, methylotrophy functions in M. flagellatus were moresimilar to the ones in M. capsulatus and M. extorquens than to the onesin the more closely related M. petroleophilum, providing the firstgenomic evidence for the polyphyletic origin of methylotrophy inBetaproteobacteria.
Date: January 8, 2007
Creator: Chistoserdova, Ludmila; Lapidus, Alla; Han, Cliff; Goodwin,Lynne; Saunders, Liz; Brettin, Tom et al.
Partner: UNT Libraries Government Documents Department

LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

Description: This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.
Date: October 1, 2008
Creator: Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M. & Stanis, Ronald J.
Partner: UNT Libraries Government Documents Department

HYDROLYSIS OF URANIUM CARBIDES BETWEEN 25 AND 100 . II. AS-CAST ALLOYS CONTAINING 2 TO 10 WT % CARBON

Description: Reactions with water of as-cast uranium-carbon alloys containing 2to 10 wt% carbon (UC/sub 0.4/ to UC/sub 2.2/) were investigated by using gas- chromatography for analysis of the gaseous products. Uranium metal-uranium monocarbide alloys yielded 2 moles of free hydrogen per mole of free metal, in addition to methane, small quantities of higher molecular weight gaseous hydrocarbons, and a solid, hydrous, tetravalent uranium oxide. The gaseous producte contained all the carbon originally present in the alloy. Uranium dicarbide (UC/sub 1.86/; this combined-C/U atom ratio was the maximum which could be obtained) yielded a mixture of 38 hydrocarbons (methane, 15 vol%; ethane, 28%: C/sub 3/- to C/sub 8/-alkanes, 7%; alkenes, 8%; alkynes, 0.6%; and widentified unsaturates, 1%), free hydrogen (40 vol%), a water-insoluble wax, and a solid, hydrous, tetravalent uranium oxide. Forty% of the combined carbon was found in the gas and 25% in the wax. The gaseous products from the hydrolysis of both UC and UC/sub 1.86/ were not affected by changes in the reaction temperature between 25 and 99 deg . The composition of the gases evolved at 80 deg from as-cast alioys with compositions between UC and UC/sub 1.86/ varied linearly with the combined-C/U atom ratio of the alloy; however, the amounts of methane produced were lower than expected from the UC concentrations in the alloys. (auth)
Date: January 21, 1963
Creator: Bradley, M.J. & Ferris, L.M.
Partner: UNT Libraries Government Documents Department

Universal Bronsted-Evans-Polanyi Relations for C-C, C-O, C-N, N-O, N-N, and O-O Dissociation Reactions

Description: It is shown that for all the essential bond forming and bond breaking reactions on metal surfaces, the reactivity of the metal surface correlates linearly with the reaction energy in a single universal relation. Such correlations provide an easy way of establishing trends in reactivity among the different transition metals.
Date: October 27, 2010
Creator: Wang, Shengguang
Partner: UNT Libraries Government Documents Department