993 Matching Results

Search Results

Advanced search parameters have been applied.

Development of high energy polymers systems: 6th monthly status report

Description: The major objective of the current program is the preparation of high energy hydroxyl-terminated polyester prepolymers from combinations of energetic diols and dicarboxylic acid chlorides. The initial work was based on the reactions of 4,4-dinitropimeloyl chloride (DNPCl) with 2,2,8,8-tetranitro-4,6-dioxa-1,9-nonanediol (DINOL) and 3(dinitrofluoro- ethoxy)-1,2-propanediol (REX-18). In an effort to develop a smooth and rapid polyester polymerization method, reactions between DNPCl and both DINOL and REX-18 have been carried out in THF containing pyridine. It was expected that the pyridine would act as an HCl acceptor, permitting room temperature polymerizations. This was indeed shown to be the case. In fact, when the glycol and DNPCl were dissolved in THF and pyridine added rapidly, a very exothermic reaction took place, with copious quantities of pyridine hydrochloride being precipitated. Slow addition of pyridine to the reaction mixture also resulted in an exotherm. In both cases, brown polymers were produced and they were very difficult to work-up. The next series of polymerizations will be carried out at 0{degrees}C in an effort to control the polymerizations more carefully and avoid color formation. The diacid chloride of 2-fluoro-2,2-dinitroethoxyfumaric acid has apparently been synthesized. Reactions of the acid with thionyl chloride at 50-60{degrees} for several days followed by a one-hour reflux produced a white solid. It was filtered, washed with hexane and dried in a vacuum dessicator over KOH. The powder melted at 104-106{degrees}. After it is recrystallized, it will be submitted for elemental analyses. Should it prove to be the diacid chloride, it will be reacted with DINOL and REX-18.
Date: July 9, 1969
Creator: Lawton, E.A.
Partner: UNT Libraries Government Documents Department

Low temperature carrier transport properties in isotopically controlled germanium

Description: Investigations of electronic and optical properties of semiconductors often require specimens with extremely homogeneous dopant distributions and precisely controlled net-carrier concentrations and compensation ratios. The previous difficulties in fabricating such samples are overcome as reported in this thesis by growing high-purity Ge single crystals of controlled {sup 75}Ge and {sup 70}Ge isotopic compositions, and doping these crystals by the neutron transmutation doping (NTD) technique. The resulting net-impurity concentrations and the compensation ratios are precisely determined by the thermal neutron fluence and the [{sup 74}Ge]/[{sup 70}Ge] ratios of the starting Ge materials, respectively. This method also guarantees unprecedented doping uniformity. Using such samples the authors have conducted four types of electron (hole) transport studies probing the nature of (1) free carrier scattering by neutral impurities, (2) free carrier scattering by ionized impurities, (3) low temperature hopping conduction, and (4) free carrier transport in samples close to the metal-insulator transition.
Date: December 1994
Creator: Itoh, K.
Partner: UNT Libraries Government Documents Department

New approaches to the preparation of P(alpha)MS beads as mandrels for NIF-scale target capsules

Description: We report on a new method using heated density gradient columns for preparing spherical poly({alpha} - methylstyrene) (P{alpha}MS) bead mandrels for inertial confinement fusion spherical shell targets. Using 1,2 propane diol/glycerol mixtures, stable density gradient columns for supporting P{alpha}MS beads can be prepared at temperatures as high as 150 {degrees}C. At these temperatures plasticized commercial beads become fluid and spherical, however loss of the plasticizer and very low molecular weight components of the bead due to limited solubility in the column fluid leads to surface finish problems. We also present results on P{alpha}MS beads prepared in an aqueous bath batch mode. Using these techniques beads with maximum out-of-rounds less than 5 {micro}m have been produced.
Date: October 20, 1998
Creator: Buckley, S R; Cook, R C; Fearon, E & Letts, S A
Partner: UNT Libraries Government Documents Department

Formation of Mesostructured Nanoparticles through Self-Assembly and Aerosol Process

Description: Silica nanoparticles exhibiting hexagonal, cubic, and vesicular mesostructures have been prepared using aerosol assisted, self-assembled process. This process begins with homogennous aerosol droplets containing silica source, water, ethanol, and surfactant, in which surfactant concentration is far below the critical micelle concentration (cmc). Solvent evaporation enriches silica and surfactant inducing interfacial self-assembly confined to a spherical aerosol droplet and results in formation of completely solid, ordered spherical particles with stable hexagonal, cubic, or vesicular mesostructures.
Date: May 7, 1999
Creator: Brinker, C. Jeffrey; Fan, Hongyou; Lu, Yunfeng; Rieker, Thomas; Stump, Arron & Ward, Timothy L.
Partner: UNT Libraries Government Documents Department

Investigation of some lanthanide carbon, nitrogen, chalcogen, and halogen systems at elevated temperatures. Progress report, February 1, 1973--January 31, 1974

Description: Progress is reported on studies of the thermodynamic characterizations of the sublimation and vaporization reactions of YbF/sub 2/ and UbF/sub 3/, and preparation phase studies of mixed halides of europium, ytterbium chloride, and lanthanide(III) fluorides. (DHM)
Date: January 1, 1974
Creator: Eick, H A; Luke, H; Biefeld, C G; Biefeld, R M; Clink, B L & Richards, J T
Partner: UNT Libraries Government Documents Department

Survey study of low-expanding high-melting, mixed oxides

Description: Approximately 40 mixed oxide materials were prepared and characterized primarily as to their thermal expansion and meltingpoint behavior. Of particular interest were those materials which were stable, had melting points in excess of 1,400 deg C, and had low thermal expansions. (auth)
Date: February 14, 1974
Creator: Holcombe, C.E.; Morrow, M.K.; Smith, D.D. & Carpenter, D.A.
Partner: UNT Libraries Government Documents Department

Synthesis and characterization of templated ion exchange resins for the selective complexation of actinide ions. 1998 annual progress report

Description: 'The purpose of this research is to develop polymeric extractants for the selective complexation of uranyl ions (and subsequently other actinyl and actinide ions) from aqueous solutions (lakes, streams, waste tanks and body fluids). Selectivity for a specific actinide ion is obtained by providing polymers with cavities lined with complexing ligands so arranged as to match the charge, coordination number, coordination geometry, and size of the actinide metal ion. These cavity-containing polymers will be produced using a specific actinide ion (or surrogate) as a template around which monomeric complexing ligands will be polymerized. The polymers will provide useful sequestering agents for removing actinide ions from wastes and will form the basis for a variety of analytical techniques for actinide determinations.'
Date: June 1, 1998
Creator: Murray, G. M. & Uy, O. M.
Partner: UNT Libraries Government Documents Department

Hindered Diphenoquinones: Diradicals of Oxygen

Description: Attempts were made to prepare a diphenoquinone having substituents in 2,2'-positions in order to prevent the planarity of the molecule and get a diradical of oxygen. The 2,2'-dimethyl-5,5'-di-t-butyldiphenoquinone was prepared and was shown to be in equilibrium with a small amount of diradical. This compound slowly polymerizes.
Date: July 10, 1956
Creator: Bourdon, Jean & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Tandem metal-mediated synthesis

Description: This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). Boronic acids RB(OH){sub 2} are currently of interest for applications involving molecular recognition such as amine and sugar sensors and selective transport of biomolecules. They have also been shown to be powerful enzyme inhibitors and alpha-aminoboronic acids (ABAs) are particularly selective inhibitors of serine proteases. Unfortunately, current multistep synthetic routes to the latter compounds do not allow for the incorporation of a wide variety of organic substituents R that may lead to new, more selective enzyme inhibitors. In this work the author describes several direct routes to ABAs based on metal-catalyzed addition of diboron compounds to imines and nitriles. Several other applications of diboron additions to heteroatom-containing unsaturated organics are also described.
Date: December 31, 1998
Creator: Baker, R.T.
Partner: UNT Libraries Government Documents Department

Heavy oil upgrading. Semi annual report {number_sign}2, April 1--September 30, 1996

Description: For the period April 1 to September 30, 1996, research efforts were focused on the synthesis and characterization of large quantities of Metal Substituted Aluminophosphate Molecular Sieves Catalysts of type 36 structure (MeAPO-36) for use in the upgrading of petroleum residuum. So far the authors have succeeded in synthesizing catalysts samples containing magnesium, zinc, cobalt and manganese in the frameworks of the respective molecular sieve. Preliminary characterization studies done by Infrared Spectroscopy demonstrated that these materials contains the Bronsted acid sites that they proposed will be active centers in the Mild Hydrocracking Process. Recently, a range of interesting aluminosilicates mesoporous materials was synthesized by Mobil R and D. These materials, known as MCM-41 type materials, contain ultra large pore unidimensional channels ranging from 20 angstrom to 100 angstrom and therefore have tremendous potential for Resid upgrading since their acid strengths are milder than zeolite. To broaden the scope of the project, MCM 41 was synthesized in the laboratory according to published procedures and the structure was confirmed by XRD. In addition, an ultra large pore high silica zeolite, UTD-1, containing a 14 angstrom tetrahedral atom pore opening was recently synthesized by Researchers at Texas A and M University. Like MCM-41, this material also has tremendous potential for Resid Upgrading since the pores are capable of accommodating larger organic molecules. The authors are currently characterizing samples of this zeolite that they intend to use in conjunction with the MeAPOs to form composite catalysts for use in resid upgrading.
Date: December 31, 1996
Partner: UNT Libraries Government Documents Department

Hypercrosslinked polymeric foams prepared by Friedel-Crafts polycondensation

Description: Porous materials are widely used in industry and government for chemical separations, processing and monitoring, environmental cleanup and remediation, energy efficiency, and conservation. Porous materials used in these applications include: foams, filters, membranes, absorbents, ion exchange resins, molecular sieves, zeolites, catalyst supports, sensors, and electrodes. Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability and processing. A novel process for preparing hypercross linked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons such as benzene, biphenyl, mterphenyl, diphenylmethane, and polystyrene, with p-dichloroxylene as the crosslinking agent. After drying the gels, the resulting foams are robust and rigid; densities range from 0.3 to 0.g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and crosslinking agent along with the level of crosslinking, the pore size and distribution along with total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6{Angstrom} to 250{Angstrom}. Further evidence of this has been confirmed by high resolution TEM.
Date: December 31, 1995
Creator: Steckle, W.P. Jr.; Mitchell, M.A. & Apen, P.G.
Partner: UNT Libraries Government Documents Department

Composition for detecting uranyl

Description: The present invention relates to an indicator composition for use in spectrophotometric detection of a substance in a solution, and a method for making the composition. Useful indicators are sensitive to the particular substance being measured, but are unaffected by the fluid and other chemical species that may be present in the fluid. Optical indicators are used to measure the uranium concentration of process solutions in facilities for extracting uranium from ores, production of nuclear fuels, and reprocessing of irradiated fuels. The composition comprises an organohalide covalently bonded to an indicator for the substance, in such a manner that the product is itself an indicator that provides increased spectral resolution for detecting the substance. The indicator is preferably arsenazo III and the organohalide is preferably cyanuric chloride. These form a composition that is ideally suited for detecting uranyl.
Date: January 1, 1994
Creator: Baylor, L.C. & Stephens, S.M.
Partner: UNT Libraries Government Documents Department

Synthesis of novel precursors for PMN powders and the thin films obtained from them

Description: Sol-gel processing has been widely used in the preparation of lead zirconate titanate (PZT) thin films. The authors have applied this methodology to the formation of lead magnesium niobate (PMN) spin-cast deposited thin films. Since there is a limited number of soluble, commercially available compounds, the authors have recently synthesized a series of novel metal alkoxides for use as precursors for generation of PMN thin films and powders. The process for generation of the perovskite phase of these PMN powders and films are reported.
Date: March 1, 1995
Creator: Boyle, T.J.; Dimos, D.B. & Moore, G.J.
Partner: UNT Libraries Government Documents Department

Technology and economic assessment of lactic acid production and uses

Description: Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}50,000 tons/yr) used in a wide range of food-processing and industrial applications. Potentially, it can become a very large-volume, commodity-chemical intermediate produced from carbohydrates for feedstocks of biodegradable polymers, oxygenated chemicals, environmentally friendly ``green`` solvents, and other intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from fermentation broths and its conversion to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. Development and deployment of novel separations technologies, such as electrodialysis with bipolar membranes, extractive and catalytic distillations, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The emerging technologies can use environmentally sound lactic acid processes to produce environmentally useful products, with attractive process economics. These technology advances and recent product and process commercialization strategies are reviewed and assessed.
Date: March 1996
Creator: Datta, R. & Tsai, S. P.
Partner: UNT Libraries Government Documents Department

New aminating reagents forthe synthesis of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB) and other insensitive energetic materials

Description: We are investigating the amination of electrophilic aromatic systems through the use of Vicarious Nucleophilic Substitution (VNS) chemistry. This research has led to a new synthesis of 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) and 1,3-diamino-2,4,6-trinitrobenzene (DATB) which uses 2,4,6-trinitroaniline (picramide) or 1,3,5-trinitrobenzene as starting materials. We also describe the development of a new class of VNS aminating reagents based on quarternary hydrazinium halides. 1,1,1-Trimethylhydrazinium iodide (TMHI), available from the methylation of the surplus propellant uns-dimethylhydrazine (UDMH), was used in a new synthesis of TATB. The advantages, scope and limitations of the VNS approach to the synthesis of TATB and other amino-substituted nitroarenes are discussed.
Date: September 19, 1995
Creator: Pagoria, P.F.; Mitchell, A.R. & Schmidt, R.D.
Partner: UNT Libraries Government Documents Department

Preconversion catalytic deoxygenation of phenolic functional groups. July 1 - September 30, 1996

Description: Most industrial processes require the use hydrocarbon based solvents that have been shown to hurt the environment. Chlorine radicals from chlorine based hydrocarbons are considered to be a major factor in the depletion of the stratospheric ozone levels. Because of the health and environmental problems these solvents cause, there is renewed interest in water soluble organometallic complexes that can be used as catalysts in the industrially important reactions. Recently, the investigators completed an extensive study on the synthesis, characterization, and reactivity of a series of nickel trimers bridged by bis(diphenylphosphino)methane (dppm) ligands. They were able to synthesize the nickel trimers by two routes. The first route involves the synthesis of a nickel dimer Ni(CNCH{sub 3}){sub 3}({mu}CNCH{sub 3}) This dimer is then reacted with NiI{sub 2}, or CH{sub 2}I{sub 2}, to form a trimer with capping isocyanide and two terminal isocyanides, and then the terminal isocyanides are replaced with a third dppm (Scheme 1). The second procedure for the synthesis is the conproportionation of 2 equivalents of Ni(COD)2 (COD=1,5-cyclooctadiene) with 1 equivalent of NiI{sub 2} in the presence of dppm.
Date: December 31, 1996
Creator: Kubiak, C.P.
Partner: UNT Libraries Government Documents Department

Laboratory robotics -- An automated tool for preparing ion chromatography calibration standards

Description: This paper describes the use of a laboratory robot as an automated tool for preparing multi-level calibration standards for On-Line Ion Chromatography (IC) Systems. The robot is designed for preparation of up to six levels of standards, with each level containing up to eleven ionic species in aqueous solution. The robot is required to add the standards` constituents as both a liquid and solid additions and to keep a record of exactly what goes into making up every standard. Utilizing a laboratory robot to prepare calibration standards provides significant benefits to the testing environment. These benefits include: accurate and precise calibration standards in individually capped containers with preparation traceability; automated and unattended multi-specie preparation for both anion and cation analytical channels; the ability to free up a test operator from a repetitive routine and re-apply those efforts to test operations; The robot uses a single channel IC to analyze each prepared standard for specie content and concentration. Those results are later used as a measure of quality control. System requirements and configurations, robotic operations, manpower requirements, analytical verification, accuracy and precision of prepared solutions, and robotic downtime are discussed in detail.
Date: April 1, 1995
Creator: Chadwick, J.L.
Partner: UNT Libraries Government Documents Department

Wet processing of palladium for use in the tritium facility at Westinghouse, Savannah River, SC. Preparation of palladium using the Mound Muddy Water process

Description: Palladium used at Savannah River for tritium storage is currently obtained from a commercial source. In order to better understand the processes involved in preparing this material, Savannah River is supporting investigations into the chemical reactions used to synthesize this material and into the conditions necessary to produce palladium powder that meets their specifications. This better understanding may help to guarantee a continued reliable source for this material in the future. As part of this evaluation, a work-for-others contract between Westinghouse Savannah River Company and the Ames Laboratory Metallurgy and Ceramics Program was initiated. During FY98, the process for producing palladium powder developed in 1986 by Dan Grove of Mound Applied Technologies (USDOE) was studied to understand the processing conditions that lead to changes in morphology in the final product. This report details the results of this study of the Mound Muddy Water process, along with the results of a round-robin analysis of well-characterized palladium samples that was performed by Savannah River and Ames Laboratory. The Mound Muddy Water process is comprised of three basic wet chemical processes, palladium dissolution, neutralization, and precipitation, with a number of filtration steps to remove unwanted impurity precipitates.
Date: November 10, 1998
Creator: Baldwin, D.P. & Zamzow, D.S.
Partner: UNT Libraries Government Documents Department

Preparation of oligonucleotide arrays for hybridization studies: Final report, 2/15/92-5/4/96

Description: We have developed several novel ways to prepare DNA. In each, the deprotection step in each synthesis cycle is accomplished with light. The group we developed for this process is dimethoxybenzoin (DMB) which, when attached to acidic functionalities, is readily removed with long wavelength (350nm) UV irradiation that will not damage the DNA bases.
Date: December 31, 1996
Creator: Pirrung, M.C.
Partner: UNT Libraries Government Documents Department

BioFacts: Fueling a stronger economy, Thermochemical conversion of biomass

Description: A primary mission of the US DOE is to stimulate the development, acceptance, and use of transportation fuels made from plants and wastes called biomass. Through the National Renewable Energy Laboratory (NREL), Doe is developing and array of biomass conversion technologies that can be easily integrated into existing fuel production and distribution systems. The variety of technology options being developed should enable individual fuel producers to select and implement the most cost-effective biomass conversion process suited to their individual needs. Current DOE biofuels research focuses on the separate and tandem uses of biochemical and thermochemical conversion processes. This overview specifically addresses NREL`s thermochemical conversion technologies, which are largely based on existing refining processes.
Date: December 1, 1994
Partner: UNT Libraries Government Documents Department