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Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities

Description: Trialkoxysilyl-containing monomers of the type (RO){sub 3}Si(CH{sub 2}){sub 3}C(O)OtBu (R = Me, Et) were prepared by hydrosilation of the corresponding vinylic tert-butyl esters CH{sub 3}CHCH{sub 2}C(O)OtBu. Acid- or base-catalyzed polymerization of the monomers leads to very high molecular weight polymers with relatively narrow polydispersities. The polymerization results in complete condensation of the alkoxy groups while the tert-butyl ester functionality remains fully intact. Partial or full deprotection of the tert-butyl group can easily be achieved to yield the corresponding carboxylic acid polymers. The ester and carboxylic acid functionalities of these new materials allow for their potential use in a variety of applications such as scavenging of heavy metals.
Date: July 14, 2000
Partner: UNT Libraries Government Documents Department

Polyester-based thin films with high photosensitivity

Description: A great deal of research has been done to understand the photosensitive optical response of inorganic glasses, which exhibit a permanent, photo-induced refractive index change due to the presence of optically active point defects in the glass structure. In the present work, the authors have performed a preliminary study of the intrinsic photosensitivity of a polyester containing a cinnamylindene malonate group (CPE, a photo- and thermal-crosslinkable group) for use in photonic waveguide devices. Thin films of CPE (approximately 0.5 microns thick) were spun onto fused silica substrates. Optical absorption in the thin films was evaluated both before and after exposure to UV radiation sources. It was found that the polyester exhibits two dominant UV absorption bands centered about 240 nm and 330 nm. Under exposure to 337 nm radiation (nitrogen laser) a marked bleaching of the 330 nm band was observed. This band bleaching is a direct result of the photo-induced crosslinking in the cinnamylindene malonate group. Exposure to 248 nm radiation (excimer laser), conversely, resulted in similar bleaching of the 330 nm band but was accompanied by nearly complete bleaching of the higher energy 240 nm band. Based on a Kramers-Kronig analysis of the absorption changes, refractive index changes on the order of {minus}10{sup {minus}2} are estimated. Confirmation of this calculation has been provided via ellipsometry which estimates a refractive index change at 632 nm of {minus}0.061 {+-} 0.002. Thus, the results of this investigation confirm the photosensitive potential of this type of material.
Date: February 29, 2000
Partner: UNT Libraries Government Documents Department


Description: This project has shown that the recovery of several valuable lactic acid products is both technically feasible and economically viable. One of the original objectives of this project was to recover lactic acid. However, the presence of a variety of indigenous bacteria in the wastewater stream and technical issues related to recovery and purification have resulted in the production of lactic acid esters. These esters could by hydrolyzed to lactic acid, but only with unacceptable product losses that would be economically prohibitive. The developed process is projected to produce approximately 200,000 lb per day of lactate esters from wastewater at a single factory at costs that compete with conventional solvents. The lactate esters are good solvents for polymers and resins and could replace acetone, methyl ethyl ketone, MIBK, and other polar solvents used in the polymer industry. Because of their low volatility and viscosity-lowering properties, they will be especially useful for inks for jet printers, alkyl resins, and high-solid paints. Owing to their efficiency in dissolving salts and flux as well as oils and sealants, lactate esters can be used in cleaning circuit boards and machine and engine parts. Unlike conventional solvents, lactate esters exhibit low toxicity, are biodegradable, and are not hazardous air pollutants. Another application for lactate esters is in the production of plasticizers. Severe health problems have been attributed to widely used phthalate ester plasticizers. The U.S. Department of Agriculture showed that replacement of these with inexpensive lactate esters is feasible, owing to their superior polymer compatibility properties. A very large market is projected for polymers prepared from lactic acid. These are called polylactides and are a type of polyester. Thermoplastics of this type have a variety of uses, including moldings, fibers, films, and packaging of both manufactured goods and food products. Polylactides form tough, orientable, self-supporting ...
Date: April 30, 2001
Creator: Stepan, Daniel J.; Olson, Edwin S.; Shockey, Richard E.; Stevens, Bradley G. & Gallagher, John R.
Partner: UNT Libraries Government Documents Department

Identification of subsurface microorganisms at Yucca Mountain; Third quarterly report, January 1, 1994--March 31, 1994

Description: Bacteria isolated from ground water samples taken from 31 springs during 1993 were collected and processed according to procedures described in earlier reports. These procedures required aseptic collection of surface water samples in sterile screw-capped containers, transportation to the HRC microbiology laboratory, and culture by spread plating onto R2A medium. The isolates were further processed for identification using a gas chromatographic analysis of fatty acid methyl esters (FAME) extracted from cell membranes. This work generated a presumptive identification of 113 bacterial species distributed among 45 genera using a database obtained from Microbial ID, Inc., Newark, Delaware (MIDI). A preliminary examination of the FAME data was accomplished using cluster analysis and principal component analysis software obtained from MIDI. Typically, bacterial strains that cluster at less than 10 Euclidian distance units have fatty acid patterns consistent among members of the same species. Thus an organism obtained from one source can be recognized if it is isolated again from the same or any other source. This makes it possible to track the distribution of organisms and monitor environmental conditions or fluid transport mechanisms. Microorganisms are seldom found as monocultures in natural environments. They are more likely to be closely associated with other genera with complementary metabolic requirements. An understanding of the indigenous microorganism population is useful in understanding subtle changes in the environment. However, classification of environmental organisms using traditional methods is not ideal because differentiation of species with small variations or genera with very similar taxonomic characteristics is beyond the capabilities of traditional microbiological methods.
Date: May 1, 1994
Creator: Stetzenbach, L.D.
Partner: UNT Libraries Government Documents Department

Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

Description: Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate counterparts of similar thickness (Nafion{trademark} 111). Additionally, nitric acid separation efficiencies ({alpha}) were approximately one order of magnitude higher for the carboxylate solution cast films when compared to Nafion{trademark} 111. The second phase of our work included the generation ...
Date: September 1, 2004
Creator: Ames, R.L.
Partner: UNT Libraries Government Documents Department

Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes

Description: We are making progress on our investigation of the mechanism of olefin exchange with Os{sub 2}(C{sub 2}H{sub 4})(CO){sub 8}. We are probing this system by kinetic study of the reaction of Os{sub 2}(C{sub 2}H{sub 4})(CO){sub 8} with butyl acrylate (BA) under various pressures of ethylene.
Date: May 1, 1992
Creator: Norton, J.R.
Partner: UNT Libraries Government Documents Department

Improved histochemical methods for the examination of plastic-embedded human marrow

Description: Improved methods for processing, sectioning, and staining plastic (glycol methacrylate) embedded human marrow biopsies are described. Marrow biopsies processed by this technique were compared with biopsies processed by the conventional paraffin embedding method. The plastic-embedded marrows provide better morphology enhancing diagnostic accuracy, permit assessment of bone as well as marrow, and allow histochemical analysis of biopsy specimen. Special stains including naphtol AS-D chloroacetate esterase, periodic acid Schiff (PAS), reticulin, and iron have been modified so that they are suitable for undecalcified, two microns thick, plastic-embedded human marrow biopsies.
Date: unknown
Creator: Moosavi, H.; Lichtman, M.A.; Donnelly, J.A. & Churukian, C.J.
Partner: UNT Libraries Government Documents Department

Selective transformation of carbonyl ligands to organic molecules

Description: Studies on the carbonylation of ({eta}{sup 5}-indenyl)(L)(CO)Ru-R complexes (L = CO, PPh{sub 3}; R = CH{sub 2}OMe, CH{sub 3}) have been completed. Particularly noteworthy is that the methoxymethyl complexes readily transform to their acyl derivatives under mild conditions that leave their iron congeners inert towards CO. Surprisingly, even ({eta}{sup 5}-indenyl)(PPh{sub 3}){sub 2}Ru-CH{sub 3} carbonylates and gives ({eta}{sup 5}-indenyl)(PPh{sub 3})(CO)Ru-C(O)CH{sub 3}. Mechanistic studies on the non catalyzed'' hydrosilation of the manganese acyls (CO){sub 5}Mn-C(O)CH{sub 2}R (R = H, OCH{sub 3}, CH{sub 3}) with Et{sub 3}SiH and of cobalt acetyls (CO){sub 3}(PR{sub 3})CoC(O)CH{sub 3} with several monohydrosilanes have been completed. The cobalt acetyls cleanly give ethoxysilanes (not acetaldehyde), and the manganese acyls provide {alpha}-siloxyvinyl complexes Z-(CO){sub 5}Mn-C(OSiEt{sub 3})=CHR (R = H, CH{sub 3}, OCH{sub 3}). Carbonylation and protolytic cleavage of the latter generate pyruvoyl complexes (CO){sub 5}Mn-COCOR (R = CH{sub 3}, CH{sub 2}CH{sub 3}), formally the products of net double carbonylation'' sequences. Studies in progress are concerned with how manganese complexes as diverse as (CO){sub 5}Mn-Y (Y = C(O)R, R, BR - but not SiMe{sub 3} or Mn(CO){sub 5}) and ({eta}{sup 3}-C{sub 3}H{sub 5})Mn(CO){sub 2}L (but not CpMn(CO){sub 3} or CpMn(CO){sub 2}({eta}{sup 2}HSiR{sub 3})) function as efficient hydrosilation catalysts towards Cp(CO){sub 2}FeC(O)CH{sub 3}, for example. These reactions cleanly afford fully characterized {alpha}-siloxyethyl complexes Fp-CH(OSiR{sub 3})CH{sub 3} under conditions where typically Rh(1) hydrosilation catalysts are inactive. Several of these manganese complexes also catalytically hydrosilate organic esters, including lactones, to their ethers R-CH{sub 2}OR; these novel ester reductions occur quantitatively at room temperature and appear to be general in scope.
Date: May 12, 1992
Creator: Cutler, A.R.
Partner: UNT Libraries Government Documents Department

Polarizability of the low frequency excitations in disordered solids. [Polymethylmethacrylate]

Description: An attempt to find manifestations of an electric dipole moment associated with the low-temperature thermal properties of glasses has enabled the setting of very low limits for GeO/sub 2/ and PMMA, 0.06 and 0.16 Debye respectively. Measurements of the temperature dependence of the dielectric constant and the electric field dependence of the thermal conductivity of SiO/sub 2/ in conjunction with dielectric measurements by Schickfus et al. has pinned down some of the features of a tunneling systems model. The potentials must be nearly symmetric (..delta../sub 0/>> ..delta../sub A/) and the distribution of these states, n(..delta..)/sub tun/, must be considerably more uniform than one would calculate from measurements of the specific heat of SiO/sub 2/, n(..delta..)/sub C/sub p/. (auth)
Date: October 1, 1975
Creator: Stephens, R.B.
Partner: UNT Libraries Government Documents Department

Surface modification of polymeric materials and its effect on blood compatibility

Description: The surfaces of commercially available polymeric materials have been modified through the chemical infusion process and physical vapor deposition. The surfaces of poly(methylmethacrylate) (PMMA) have been modified through a chemical infusion process by treatment of the sample with a solution containing varying amounts of titanium(IV)isopropoxide and polyvinylpyrrolidone (PVP). The surfaces of silicone rubber samples have been coated with a thin coating of titanium dioxide with an ion beam sputtering technique. The treated samples were characterized by scanning electron microscopy, optical microscopy, and neutron activation analysis. The infused samples were evaluated for blood compatibility using two biological assays: an adherence assay in which the adherence of human polymorphonuclear leukocytes to the samples was determined, and a hemolysis assay using rat blood erythrocytes to determine the hemolytic activity of the samples. Based on the results of these assays, the PMMA samples treated with PVP alone resulted in an improvement in reactivity with the blood cells. 16 refs., 4 figs.
Date: January 1, 1987
Creator: Wrobleski, D.A.; Cash, D.L.; Archuleta, T.; Barthell, B.L.; Kossowsky, R.; London, J.E. et al.
Partner: UNT Libraries Government Documents Department

Ultrastructure of unstained, hydrated proteoglycan aggregates and monomer: a new method of imaging

Description: The application of a new method for imaging delicate hydrated biological materials is reported, and the structure of isolated proteoglycan aggregates and monomer is demonstrated at better than 30 nm resolution. This new method for high resolution examination of labile hydrated biological materials, employing a wet cell and pulsed plasma x-ray source, permits short exposure times, minimal specimen damage, and sufficient radiation dosages for imaging. (ERB)
Date: January 1, 1980
Creator: Panessa, B J; Hoffman, P; Warren, J B; McCorkle, R A & Coleman, G
Partner: UNT Libraries Government Documents Department

Solar-collector materials exposure to the IPH site environment. Final report

Description: In-situ environmental exposure tests were conducted at nine proposed intermediate-temperature Industrial Process Heat (IPH) sites. Three types of reflector materials were evaluated for survivability at the nine sites: second-surface silvered glass, aluminized acrylic FEK-244 film on aluminum substrate, and Alzak (electropolished aluminum) on aluminum substrate. Black chrome absorber material and low-iron float glass were evaluated for thermal, photochemical, and environmental degradation. The reflector specimens were monitored for decreases in specular and hemispherical reflectance due to soil buildup. The absorber material was evaluated for changes in solar absorptivity and emissivity, and the float glass was monitored for changes in transmissivity. Surface and subsurface defects on all materials were examined microscopically and, where deemed of note, were documented photographically.
Date: January 1, 1982
Creator: Morris, V.L.
Partner: UNT Libraries Government Documents Department

Solar-collector-materials exposure to the IPH site environment. Volume 1. Final report

Description: In-situ environmental exposure tests were conducted at nine proposed intermediate-temperature Industrial Process Heat (IPH) sites. Three types of reflector materials were evaluated for survivability at the nine sites: second-surface silvered glass, aluminized acrylic FEK-244 film on aluminumsubstrate and Alzak (electropolished aluminum) on aluminium substrate. Black chrome absorber material and low-iron float glass were evaluated for thermal, photochemical, and environmental degradation. The reflector specimens were monitored for decreases in specular and hemispherical reflectance due to soil buildup. The absorber material was evaluated for changes in solar absorptivity and emissivity, and the float glass was monitored for changes in transmissivity. Surface and subsurface defects on all materials were examined microscopically and, where deemed of note, were documented photographically.
Date: January 1, 1982
Creator: Morris, V.L.
Partner: UNT Libraries Government Documents Department

Temperature and shock testing of lithium-organic electrolyte cells. [Li/LiAsF/sub 6/ + LiBF/sub 4/ in methyl formate/V/sub 2/O/sub 5/, Honeywell G2655, performance from -40/sup 0/ to +70/sup 0/C, shock levels up to 17,000 g's]

Description: Honeywell G2655 lithium cells were tested over the temperature range -40/sup 0/ to +70/sup 0/C and subjected to shock levels up to 17,000 g's. Output at -40/sup 0/C was approximately 50 percent of that at +25/sup 0/C, while at +70/sup 0/C the output was 150 percent that at +25/sup 0/C. Shock had no noticeable effect on performance. 99 figures, 6 tables. (auth)
Date: January 1, 1976
Creator: Levy, S.C.
Partner: UNT Libraries Government Documents Department

Performance testing of the Acurex solar-collector Model 3001-03

Description: Results are summarized of tests conducted at the Collector Module Test Facility on an Acurex Model 3001-03 Parabolic Trough Concentrating Solar Collector. Test temperaure range was 100/sup 0/C to 300/sup 0/C. Tests were conducted with the collector axis oriented east-west and again with the collector axis oriented north-south. Three collectors were tested: one using polished aluminum mirrors, one using glass mirrors, and another using an aluminized acrylic film mirror.
Date: March 1, 1982
Creator: Dudley, V.E. & Workhoven, R.M.
Partner: UNT Libraries Government Documents Department

Alternate materials of construction for geothermal applications. Progress report No. 18, January-March 1979

Description: Progress in a program to develop non-metallic materials for use in geothermal processes is described. To date, several high temperature polymer and polymer concrete systems were formulated, laboratory and field tests were performed in brine, flashing brine, and steam at temperatures up to 260/sup 0/C (500/sup 0/F), and economic studies were started. Laboratory data for exposure times > 2 years are available. Results are also available from field exposures of up to 24 months in five geothermal environments. Good durability is indicated. Testing at five of these sites is continuing and plans to initiate tests at other sites are being implemented. Work was also started to develop materials for use in high temperature seals for well drilling, logging and energy extraction processes.
Date: August 1, 1979
Creator: Steinberg, M. & Kukacka, L.E.
Partner: UNT Libraries Government Documents Department

Investigation of test methods, material properties, and processes for solar cell encapsulants. Seventh annual report

Description: The goal of the program is to identify and evaluate encapsulation materials and processes for the protection of silicon solar cells for service in a terrestrial environment. Aging and degradation studies were performed including: thermal aging, sunlamp exposures, aging in controlled environment reactors and outdoor photothermal aging devices, and metal catalyzed degradation. Other tests addressed water absorption, primers and adhesives, soiling experiments, and corrosion protection. (LEW)
Date: January 1, 1983
Creator: Willis, P.B.
Partner: UNT Libraries Government Documents Department

Chlorophyll photochemistry in condensed media: triplet state quenching and electron transfer to quinone in cellulose acetate films

Description: Chlorophyll a was incorporated into cellulose acetate films and the triplet decay and electron transfer to p-benzoquinone in aqueous solution was studied using laser flash photolysis and ESR. The triplet was found to decay by first order kinetics with the same rate constant regardless of chlorophyll concentration, but the yield was concentration dependent. This is due to quenching at the ground and/or singlet state levels. In the presence of quinone, the triplet is quenched and, when the quinone is in an aqueous solution in contact with the film, chlorophyll cation radical (C./sup +/) as well as the semiquinone anion radical (Q./sup -/) can be observed. The C./sup +/ decays by second order kinetics with a rate constant of 1.5 x 10/sup 6/ M/sup -1/ sec/sup -1/. Although triplet conversion to radicals is slightly lower in the films as compared to homogeneous solutions (approx. 3 times), the lifetimes of the radicals are greatly increased (approx. 10/sup 3/ times).
Date: January 1, 1979
Creator: Cheddar, G.; Castelli, F. & Tollin, G.
Partner: UNT Libraries Government Documents Department

Cerenkov radiators for photodiodes

Description: Several materials have been examined for use as Cerenkov converters in front of photodiodes in an effort to find a gamma detector system that has more sensitivity than a Compton detector but makes little sacrifice in bandwidth. Suprasil (fused silica) and UVT Lucite (acrylic) were 10-100 times more sensitive than a Compton detector and provided almost the same bandwidth. Barium fluoride provided almost 1000 times the sensitivity, but with a factor of 3 or 4 reduction in bandwidth. Relative sensitivities are strongly dependent on beam composition; the Cerenkov package is less sensitive to a pure ..gamma..-ray beam than to a ..gamma..-electron shower beam. Hence, beam composition must be considered in any application of these detectors.
Date: January 1, 1982
Creator: Toevs, J.W.; Young, C.S.; Zagarino, P.A. & Seno, R.D.
Partner: UNT Libraries Government Documents Department

The morphology of emulsion polymerized latex particles

Description: Under monomer starved feed conditions, emulsion polymerization of perdeuterated methyl methacrylate and styrene in the presence of preformed polymethylmethacrylate latexes resulted in particles with a core-shell morphology, as determined by small-angle neutron scattering (SANS) analysis for a hollow sphere. The locus of polymerization of the added deuterated monomer is therefore at the particle surface. In similar measurements a statistical copolymer of styrene and methyl methacrylate was used as seed particles for further polymerization of trideuteromethyl methacrylate. The resulting polymer latex was again shown to have a core-shell morphological structre as determined by SANS. SANS experiments were also undertaken on polystyrene latexes polymerized by equilibrium swelling methods, with deuterated polymer forming the first or second step. The experiments covered a molecular weight range of 6 x 10/sup 4/ < M < 6 x 10/sup 6/ g/mol. For M > 10/sup 6/ the molecular weights are consistent with the experimental errors, indicating that the deuterium labeled molecules are randomly distributed in the latex. These results led to the finding that the polymer chains were constrained in the latex particles by factors of 2 to 4 from the relaxed coil dimensions. For M < 10/sup 6/ g/mol SANS gave zero angle scattering intensities much higher than expected on the basis of a random distribution of labeled molecules. Several models were examined, including the possible development of core-shell structures at lower molecular weights. 25 refs., 6 figs., 3 tabs.
Date: November 1, 1987
Creator: Wignall, G. D.; Ramakrishnan, V. R.; Linne, M. A.; Klein, A.; Sperling, L. H.; Wai, M. P. et al.
Partner: UNT Libraries Government Documents Department

Recovery of acid-degraded tributyl phosphate by solvent extraction

Description: During nuclear fuel reprocessing the organic solvent becomes loaded with various acidic degradation products, which can be effectively removed through solvent extraction. Studies have been made with a small bench-scale solvent extraction system to optimize such parameters as pH of aqueous phase, phase ratio, residence time, flow rates, and temperature. The necessary decontamination factors have been obtained for various degradation products during continuous solvent extraction in one stage, with the aqueous phase being recycled. The aqueous phase contains compounds that can be degraded to gases to minimize waste disposal problems.
Date: January 1, 1981
Creator: Young, G.C. & Holladay, D.W.
Partner: UNT Libraries Government Documents Department