5,214 Matching Results

Search Results

Advanced search parameters have been applied.

Oxidation of Aromatic Compounds by Bacteria

Description: From Introduction: "The material in this paper is about central paths and how bacterial enzymes manipulate and cleave the aromatic ring with the formation of hydroxylated aromatic ring with the formation
Date: 1962
Creator: Rogoff, Martin H. & Wender, Irving
Partner: UNT Libraries Government Documents Department

Relationship Between Oxidizability and Composition of Coal

Description: From Introduction: "Measurement of these differences serve to define completely the chemical nature of coal and is possible as a result of the observations contained in the report." From Scope of Investigation: "The authors have endeavored to test the truth of these observations by a study of a series of coals of widely different rank, and the present report deals with the results of this investigation."
Date: 1931
Creator: Francis, Wilfrid & Morris, H. M.
Partner: UNT Libraries Government Documents Department


Description: Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDHR55M and SDHH57A are relatively insensitive to pH (~;;60 and 200 s-1, respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for substrate binding and catalysis. The structure of SDHR55M has sulfate bound at the active site, a fact that coincides with a significant increase in the inhibitory effect of sulfate in SDHR55M. Thus, Arg-55 also appears to be involved in enabling discrimination between the substrate and product in SDH.
Date: November 10, 2008
Creator: Bailey, Susan; Rapson, Trevor; Johnson-Winters, Kayunta; Astashkin, Andrei; Enemark, John & Kappler, Ulrike
Partner: UNT Libraries Government Documents Department

A Study of Oxidation of the Oil in Two Air-and Air-Gas-Repressuring Projects

Description: Report issued by the U.S. Bureau of Mines on the oxidation levels caused from different oil recovery processes. Experiments were conducted to determine the effect of air on crude oil, and the degree of oxidation. This report includes tables, and a map.
Date: January 1937
Creator: Johnson, T. W. & Taylor, Sam S.
Partner: UNT Libraries Government Documents Department

Oxidation of Polycyclic, Aromatic, Hydrocarbons: A Review of the Literature

Description: Report discussing the literature on the oxidation of polycyclic, aromatic hydrocarbons. Information has been assembled on (1) the oxidants effective in the oxidation of such hydrocarbons, (2) the relative reactivity of the hydrocarbons, (3) the conditions under which oxidation proceeds, (4) the chemical mechanisms involved when such oxidations occur, and (5) the products formed.
Date: September 17, 1965
Creator: Tipson, R. Stuart
Partner: UNT Libraries Government Documents Department

The Oxidation of Exhaust Gases at Room Temperature

Description: Report presenting an investigation made to determine the effectiveness of various oxides and oxide mixtures in oxidizing at room temperature the exhaust gases from an internal-combustion engine for the determination of fuel-air ratio. The oxides of silver, copper, manganese, cobalt, nickel, iron, cerium, lead, bismuth, and mercury were tested individually and in various combinations.
Date: February 1945
Creator: Gerrish, Harold C.; Meem, J. Lawrence, Jr. & Tuck, Vivian C.
Partner: UNT Libraries Government Documents Department

Oxidation Characteristics of Molybdenum Disulfide and Effect of Such Oxidation on Its Role as a Solid-Film Lubricant

Description: Note presenting an investigation conducted to determine the oxidation characteristics of molybdenum disulfide and to determine the effect of such oxidation on its role as a solid-film lubricant. A coating of molybdenum disulfide serving as a high-temperature solid-film lubricant maintained low coefficient-of-friction values during its oxidation as long as an effective subfilm of the molybdenum disulfide remained.
Date: May 1949
Creator: Godfrey, Douglas & Nelson, Erva C.
Partner: UNT Libraries Government Documents Department

Low-Temperature, Vapor-Phase Oxidation of Fuel-Rich Hydrocarbon Mixtures

Description: Note presenting a study of the vapor-phase oxidation of methylcyclohexane in a flow system in the temperature range of 300 to 400 degrees Celsius under the conditions of 0.1 the stoichiometric amount of oxygen, a contact time of 8 seconds, and a spiral Pyrex reactor 10.5 inches long with an inside diameter of 3/32 inch. The yields of acids, aldehydes, ketones, hydrogen peroxide, organic peroxides, olefin, water, and unreacted hydrocarbon were determined in the products.
Date: January 1958
Creator: House, William T. & Orchin, Milton
Partner: UNT Libraries Government Documents Department

High-temperature oxidation and ignition of metals

Description: "A study of the high-temperature oxidation of several aircraft construction materials was undertaken to assess the possibility of ignition under high-temperature flight conditions.Tests have been made both in open and closed jets, and, in addition, the burning of metals has been observed under static conditions in a pressurized vessel containing either air, oxygen, or nitrogen. When heated in an atmosphere of oxygen or when heated and plunged into a supersonic airstream, titanium, iron, carbon steel, and common alloys such as 4130 were found to have spontaneous-ignition temperatures in the solid phase (below melting) and they melted rapidly while burning" (p. 1).
Date: March 26, 1956
Creator: Hill, Paul R.; Adamson, David; Foland, Douglas H. & Bressette, Walter E.
Partner: UNT Libraries Government Documents Department

Development and Evaluation of High-Temperature Tungsten Alloys : Quarterly Report No. 3, April 1, 1960 - June 30, 1960

Description: Abstract: "High-tungsten alloys were prepared by powder metallurgy techniques. Excellent strength and ductility at room temperature were found in the W-Ni-Mo-Ry system and in W-Ni-Fe alloys containing platinum and/or ruthenium. The effects of prolonged annealing at 1600 F on room-temperature properties were studied; W-Ni-Fe-Pt-Ru alloys were least affected by this treatment. Oxidation rates for most alloys at 2000 F were 2 to 4 times that of unalloyed tungsten; an exception was a W-Ni-Mo-Ru alloy which oxidized at 1/5 the rate of tungsten. Slip casting techniques and induction-sintering of loosely compacted powders were used to produce compacts of W-Ni-Fe materials having section thicknesses of 1 to 2 inches."
Date: August 10, 1960
Creator: Holtz, F. C. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

Development and Evaluation of High-Temperature Tungsten Alloys : Summary Report

Description: Abstract: "Tungsten-rich alloys, developed for use at temperatures up to 2000F, exhibit ductility, fabricability and joinability not found in commercially-available materials. An envelope type of microstructure was produced in compositions containing at least 90 wt% tungsten by liquid-phase sintering of cold-pressed powders in hydrogen. At room temperature the alloys could be rolled extensively, and tensile elongations up to 25% were noted. Strength properties of a W-Ni-Fe base were improved by small quaternary additions. The ultimate tensile strength of a 90W-4.8Ni-3.2Fe-2Ru alloy was 46,700 psi at 2000F, compared to 30,000 - 35,000 psi for unalloyed tungsten or W-Ni-Fe; the 100-hour stress-rupture strength at 1600F was 15,000 psi. Excellent joints were produced by spot welding and localized induction heating. The oxidation resistance of unprotected 90 wt% tungsten compositions was not significantly affected by alloying."
Date: November 12, 1959
Creator: Holtz, F. C. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

Development and Evaluation of High-Temperature Tungsten Alloys : Quarterly Report No. 1, October 1, 1959 - December 31, 1959

Description: Abstract: "High-tungsten alloys were prepared by powder metallurgy techniques. Room-temperature strength properties were determined for W-Ni-Fe compositions with quaternary additions of Cr, Pd, and Ru; tungsten levels ranged from 80 to 94 wt%. Small (1-3 wt%) ruthenium additions were the most effective in improving strength. The oxidation resistance of a number of tungsten-base alloys was measured at 2000F. Quaternary W-Ni-Fe base alloys containing Al, Ru, Ti, and Zr were the most oxidation resistant, having values similar to unalloyed tungsten. Oxidation protection of a 90W-6Ni-4Fe material was accomplished by a fused coating of AMS 4775; the composite was tested for 482 hours in air at 2000F without damage to the base alloy."
Date: January 20, 1960
Creator: Holtz, F. C. & Van Thyne, R. J.
Partner: UNT Libraries Government Documents Department

Hard and Soft

Description: The purpose of this investigation is to explore the possibilities of manipulating clay in three distinct ways to effectively show that clay objects were at one time moist and pliable. The techniques used are faceting while wet, manipulating a variety of additions, applying different glazing techniques, and three separate firing methods. In addressing the problem, the following concerns were considered: (a) Which of the pieces made best expresses my aesthetic concerns? (b) Which firing method, oxidation, reduction or atmospheric, best illustrates these concerns? (c) Which glazing technique was most successful? In an attempt to explore and solve these problems, a series of twenty pieces were produced. A visual record of slides showing individual pieces were made to demonstrate the differences and similarities between firing methods.
Date: December 2000
Creator: Gray, J. Christensen
Partner: UNT Libraries

Oxidation behavior and microstructural decomposition of Ti-6Al-4V and Ti-6Al-4V-1B sheet

Description: This article conducts a direct comparison between the oxidation behavior of Ti-6Al-4V and Ti-6Al-4V + 1B to elucidate whether the addition of boron to Ti-^Al-4V impacts the oxidation behavior.
Date: August 1, 2016
Creator: Brice, David. A.; Samimi, P.; Ghamarian, I.; Liu, Yue; Brice, R. M.; Reidy, Richard F. et al.
Partner: UNT College of Engineering

A method for the analysis of compounds containing boron, carbon, and hydrogen

Description: Report presenting a method for analyzing each of the elements, boron, carbon, and hydrogen from the quantitative analysis of a single sample of an organoboron compound. The method is helpful for the analysis of volatile hydrocarbons and polynuclear aromatic compounds.
Date: March 3, 1955
Creator: Allen, Harrison, Jr. & Tannenbaum, Stanley
Partner: UNT Libraries Government Documents Department

Final Technical Report - Commercially Important Carbohydrate Diacids - Building Blocks from Renewable Carbohydrates

Description: The primary objective of this project was to develop oxidation methods appropriate for the conversion of agriculturally derived simple sugars to their corresponding diacids (aldaric acids) for use as biobased chemical building blocks for new biodegradable polymers and other materials. Principal target diacids were D-glucaric, meso-xylaric, D-mannaric and L-arabinaric acid, each to be prepared by nitric acid oxidation of the naturally occurring precursor carbohydrates (monosaccharides) D-glucose, D-xylose, D-mannose and L-arabinose, respectively, all from hydrolysis of naturally abundant plant polysaccharides. These conversions were to be designed for scale up to a level suitable for transfer first to a pilot plant scale, and then to an industrial plant scale. The core of the project involved a comprehensive study of the title oxidation employing a computer controlled reactor. The plan of action involved defining experimental parameters to allow for control of the oxidations with considerable precision and reproducibility. The prototype oxidations were typically run using ca. 0.75 molar amounts of carbohydrate, with a goal of eventually doubling the reaction size when appropriate reaction parameters were established. During the course of the funding period for this grant, the fundamentals of reaction control were established for oxidation of D-glucose, a critical component of the project given the exothermic character of the reaction. The reactions were monitored using a reliable GC/MS protocol. The glucose to glucaric acid conversion represented the most important and potentially highest value conversion. During the grant period we were able to establish one workable system to carry out the glucose to glucaric acid conversion, but were not able to optimize the process or establish a protocol that was satisfactory for a scale up to a pilot plant scale. However, the work carried out showed the possibility that with appropriate innovation and continued effort, a prototype for a successful pilot plant scale operation ...
Date: January 7, 2009
Creator: Kiely, Donald E.
Partner: UNT Libraries Government Documents Department