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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

Molecular Basis for Enzymatic Sulfite Oxidation -- HOW THREE CONSERVED ACTIVE SITE RESIDUES SHAPE ENZYME ACTIVITY

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 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

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

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

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. Inconel, copper, 18-8 stainless steel, Monel, and aluminum could not be made to ignite spontaneously at temperatures up to melting with the equipment available. Magnesium ignited spontaneously in either type of test at temperatures just above the melting temperature.A theory for the spontaneous ignition of metals, based on the first law of thermodynamics, is presented. Good correlation was obtained between calculated spontaneous-ignition temperatures and values measured in supersonic jet tests. There appears at the present time to be no need for concern regarding the spontaneous ignition of Inconel, the stainless steels, copper, aluminum, or magnesium for ordinary supersonic airplane or missile applications where the material temperature is kept within ordinary structural limits or at least below melting. For hypersonic applications where the material is to be melted away to absorb the heat of convection, the results of the present tests do not apply sufficiently to allow a conclusion.
Date: March 26, 1956
Creator: Hill, Paul R.; Adamson, David; Foland, Douglas H. & Bressette, Walter E.
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

An Exploration of Catalytic Chemistry on Au/Ni(111)

Description: This project explored the catalytic oxidation chemistry that can be effected on a Au/Ni(111) surface alloy. A Au/Ni(111) surface alloy is a Ni(111) surface on which less than 60% of the Ni atoms are replaced at random positions by Au atoms. The alloy is produced by vapor deposition of a small amount of Au onto Ni single crystals. The Au atoms do not result in an epitaxial Au overlayer or in the condensation of the Au into droplets. Instead, Au atoms displace and then replace Ni atoms on a Ni(111) surface, even though Au is immiscible in bulk Ni. The two dimensional structure of the clean Ni surface is preserved. This alloy is found to stabilize an adsorbed peroxo-like O2 species that is shown to be the critical reactant in the low temperature catalytic oxidation of CO and that is suspected to be the critical reactant in other oxidation reactions. This investigation revealed a new, practically important catalyst for CO oxidation that has since been patented.
Date: December 9, 2011
Creator: Ceyer, Sylvia T.
Partner: UNT Libraries Government Documents Department

Oxidation of interconnect alloys in an electric field

Description: The effect of an electric field on the oxidation of interconnect alloys was examined with a representative array of materials: an iron-base ferritic chromia former (E-brite), an iron-base ferritic chromia former with Mn and La (Crofer 22APU), a nickel-base chromia former (IN-718), and a nickelbase chromia former with Mn and La (Haynes 230). Environmental variables include temperature and oxygen partial pressure. The resulting scales were examined to determine if applied electrical current induces changes in mechanism or scale growth kinetics.
Date: October 1, 2006
Creator: Holcomb, G.R.; Alman, D.E.; Adler, T.A. & Jablonski, P.D.
Partner: UNT Libraries Government Documents Department

Integrated Biomass Gasification with Catalytic Partial Oxidation for Selective Tar Conversion

Description: Biomass gasification is a flexible and efficient way of utilizing widely available domestic renewable resources. Syngas from biomass has the potential for biofuels production, which will enhance energy security and environmental benefits. Additionally, with the successful development of low Btu fuel engines (e.g. GE Jenbacher engines), syngas from biomass can be efficiently used for power/heat co-generation. However, biomass gasification has not been widely commercialized because of a number of technical/economic issues related to gasifier design and syngas cleanup. Biomass gasification, due to its scale limitation, cannot afford to use pure oxygen as the gasification agent that used in coal gasification. Because, it uses air instead of oxygen, the biomass gasification temperature is much lower than well-understood coal gasification. The low temperature leads to a lot of tar formation and the tar can gum up the downstream equipment. Thus, the biomass gasification tar removal is a critical technology challenge for all types of biomass gasifiers. This USDA/DOE funded program (award number: DE-FG36-O8GO18085) aims to develop an advanced catalytic tar conversion system that can economically and efficiently convert tar into useful light gases (such as syngas) for downstream fuel synthesis or power generation. This program has been executed by GE Global Research in Irvine, CA, in collaboration with Professor Lanny Schmidt's group at the University of Minnesota (UoMn). Biomass gasification produces a raw syngas stream containing H2, CO, CO2, H2O, CH4 and other hydrocarbons, tars, char, and ash. Tars are defined as organic compounds that are condensable at room temperature and are assumed to be largely aromatic. Downstream units in biomass gasification such as gas engine, turbine or fuel synthesis reactors require stringent control in syngas quality, especially tar content to avoid plugging (gum) of downstream equipment. Tar- and ash-free syngas streams are a critical requirement for commercial deployment of biomass-based power/heat ...
Date: May 28, 2011
Creator: Zhang, Lingzhi; Wei, Wei; Manke, Jeff; Vazquez, Arturo; Thompson, Jeff & Thompson, Mark
Partner: UNT Libraries Government Documents Department

SOOT-CATALYZED OXIDATION OF SULFUR DIOXIDE

Description: Experimental results are reviewed which demonstrate that combustion-generated soot particles can oxidize SO{sub 2} in both the absence ('dry' mechanism) and the presence ('wet' mechanism) of liquid water. The 'wet' mechanism is much more efficient than the 'dry' one, and is applicable to situations where the aerosol particles are covered with a liquid water layer. Calculations are presented which suggest that the soot-catalyzed oxidation of SO{sub 2} can be the dominant mechanism under realistic atmospheric conditions.
Date: May 1, 1978
Creator: Chang, S.G. & Novakov, T.
Partner: UNT Libraries Government Documents Department

Bioinspired Hydrogenase Models: The Mixed-Valence Triiron Complex [Fe₃(CO)₇(μ-edt)₂] and Phosphine Derivatives [Fe₃(CO)₇−ₓ(PPh₃)ₓ(μ-edt)₂] (x = 1, 2) and [Fe₃(CO)₅(κ²‑diphosphine)(μ- edt)₂] as Proton Reduction Catalysts

Description: This article describes the preparation and structural characterization of the mixed-valence triiron complexes.
Date: July 15, 2013
Creator: Rahaman, Ahibur; Ghosh, Shishir; Unwin, David G.; Basak-Modi, Sucharita; Holt, Katherine B.; Kabir, Shariff E. et al.
Partner: UNT College of Arts and Sciences