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in subjects: "Activation Energy"  
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On the generation of H{sub 2} from formaldehyde in basic aqueous solutions

Description: The generation of H{sub 2} from formaldehyde and glyoxalate in aqueous solutions at high concentrations of hydroxide has been studied in the temperature range 21-60{degrees}C. The reaction is first order in formaldehyde and is of higher than first order in hydroxide concentration. Conversion ratio of the aldehyde to H{sub 2} increases on increasing OH{sup {minus}} concentration and on raising the temperature. It decreases on increasing aldehyde concentration due to the competition by the Canniz… more
Date: March 1, 1994
Creator: Kapoor, S.; Barnabas, F.; Jonah, C. D.; Sauer, M. C. Jr. & Meisel, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Kinetics and mechanisms of reactions involving small aromatic reactive intermediates. Annual report

Description: Phenyl (C{sub 6}H{sub 5}), phenoxy (C{sub 6}H{sub 5}O) and benzyne (C{sub 6}H{sub 4}) are fundamentally important prototype molecules. C{sub 6}H{sub 5} and C{sub 6}H{sub 5}O are also very important reactive intermediates in hydrocarbon combustion systems, particularly with regard to soot formation chemistry, as well as to the combustion chemistry of aromatic additives in gasoline. The authors proposed to study the kinetics and mechanisms of these three benchmark reactive intermediates using two… more
Date: April 1, 1994
Creator: Lin, M. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The chemistry and physics of transition metal clusters

Description: In this program the authors study the fundamental properties of isolated clusters of transition metal atoms. Experimental studies of cluster chemistry include determination of cluster structure, reactivity, and the nature of cluster-adsorbate interactions. Studies of physical properties include measurements of cluster ionization potentials and photoabsorption cross sections. Theoretical studies focus on the structure and dynamics of clusters, including isomers, phases and phase changes, interac… more
Date: June 1, 1994
Creator: Parks, E. K.; Jellinek, J.; Knickelbein, M. B. & Riley, S. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effects of two-phase flow on the deflagration of porous energetic materials

Description: Theoretical analyses are developed for the multi-phase deflagration of porous energetic solids, such as degraded nitramine propellants, that experience significant gas flow in the solid preheat region and are characterized by the presence of exothermic reactions in a bubbling melt layer at their surfaces. Relative motion between the gas and condensed phases is taken into account in both regions, and expressions for the mass burning rate and other quantities of interest, such as temperature and … more
Date: July 1, 1994
Creator: Margolis, S. B. & Williams, F. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Kinetics of the wetting of tin on air-passivated copper in the absence of a fluxing agent

Description: A specially designed ultrahigh vacuum in situ surface analysis and wetting system has been constructed to study the spreading of liquid metal solders on carefully prepared and well-characterized solid substrates. Initial studies have been completed for the spreading of pure tin solder on copper substrates in the absence of any fluxing agent. Surface chemical analysis by x-ray photoelectron spectroscopy showed the air-exposed surface to consisted of about 3 nm of Cu{sub 2}O, while the as-receive… more
Date: October 1, 1994
Creator: Peebles, D. E.; Peebles, H. C.; Ohlhausen, J. A. & Yost, F. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large scale atomistic first principles study of adsorption and surface diffusion

Description: Computer simulation of atomistic processes is an important tool in understanding the properties of condensed matter at a microscopic level. The best way to reproduce the rich variety of experimentally observed effects in the simulation is to use the quantum mechanical description of the ion-electron interactions in a solid. Such calculations although increasingly popular make high demands on the computing power available. The systems of practical interest to surface physics include at least hun… more
Date: February 1, 1994
Creator: Milman, V.; Pennycook, S. J.; Jesson, D. E.; Payne, M. C.; Stich, I. & Lee, M. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Flux creep: Its dependence on current denisty and relation to critical current densities from transport and magnetic measurements

Description: Thermally activated flux motion dominates the transport properties of HTS conductors over a large portion of the H-T phase diagram. The activation energy for this flux motion is generally a non-linear function, U(J), of the current density. We discuss methods and results of U(J) determination for HTS materials and implications for the critical current densities inferred from magnetic hysteresis measurements.
Date: May 1, 1994
Creator: Maley, M. P.; Kung, P. J.; Cho, J. H. & Willis, J. O.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fluidized-bed sorbents

Description: The objectives of this project are to identify and demonstrate methods for enhancing long-term chemical reactivity and attrition resistance of zinc oxide-based mixed metal-oxide sorbents for desulfurization of hot coal-derived gases in a high-temperature, high-pressure (HTHP) fluidized-bed reactor. In this program, regenerable ZnO-based mixed metal-oxide sorbents are being developed and tested. These include zinc ferrite, zinc titanate, and Z-SORB sorbents. The Z-SORB sorbent is a proprietary s… more
Date: October 1, 1994
Creator: Gangwal, S. K. & Gupta, R. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Novel process for depolymerization of coal to C{sub 2}-C{sub 4} hydrocarbons. Final report, 1 September 1989--31 August 1993

Description: A principal objective of this work was to study the conversion of coal to C{sub 2} {minus} C{sub 4} hydrocarbons in a two-stage reactor system. Coal was converted to liquids at 440{degrees}C in a stirred batch autoclave using tetralin as the hydrogen donor solvent. The liquids produced were separated from the unreacted coal and ash by filtration. The liquids were then fed into a second stage fixed bed reactor containing sulfided Ni-Mo/Al{sub 2}O{sub 3} and SiO{sub 2{minus}}Al{sub 2}O{sub 3} cat… more
Date: July 8, 1994
Creator: Wiser, W. H. & Oblad, A. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Temperature-dependent structure of {bold a}(10{bar 1}) superdislocations in Ni{sub 3}Al

Description: The dissociated structure of the a(101) superdislocations in Ni{sub 3}Al is predicted as a function of temperature. The temperature dependence of the relevant fault Helmholtz free energies and elastic constants are calculated within the quasiharmonic approximation using the embedded atom method, Results of these calculations are then incorporated into anisotropic elasticity theory-based calculations of the dissociation distances. The cross-slip activation enthalpy is estimated and found to decr… more
Date: December 31, 1994
Creator: Chrzan, D. C.; Foiles, S. M.; Daw, M. S. & Mills, M. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

KINETICS: A computer program to analyze chemical reaction data. Revision 2

Description: KINETICS (Version 3.2) is a copyrighted, user-friendly kinetics analysis computer program designed for reactions such-as kerogen or polymer decomposition. It can fit rate parameters to chemical reaction data (rate or cumulative reacted) measured at a series of constant temperatures, constant heating rates, or arbitrary thermal histories. The program uses two models with conversion-dependent Azrhenius parameters and two models with activation energy distributions. The discrete distribution model… more
Date: September 1, 1994
Creator: Braun, R. L. & Burnham, A. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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