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in subjects: "Chemical Bonds"  
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Radiation effects and metalloproteins studied by x-ray photoelectron spectroscopy

Description: X-ray photoelectron spectroscopy (XPS) is used to study the bonding structure at the iron site of cytochrome c and the bonding of rare earth ions to the phosphate oxygens of ATP. Radiation effects are studied on several amino acid and simple peptide model systems. The emission spectrum of the x-ray source is calculated from literature references. The distributions of photon energy as a function of photon frequency and as a function of take-off angle are obtained. From these distributions, the r… more
Date: July 1, 1975
Creator: Wurzbach, J.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The puzzles of surface science and recent attempts to explain them

Description: Surfaces have several unique properties that remain unexplained on the atomic level. These include (1) the unique chemical activity of rough surfaces, (2) the breaking of chemical bonds in narrow temperature ranges; and (3) the role of co-adsorption and strongly adsorbed monolayers during catalysis and tribological change (friction, lubrication). The dynamic surface restructuring model and surface structure induced variations in local density of states that have been suggested to rationalize th… more
Date: July 1, 1990
Creator: Somorjai, G.A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Hydrogen bonding in asphaltenes and coal. Quarterly report for April 1, 1979--June 30, 1979

Description: Structural analyses are reported of upgraded coal-liquids derived from catalytic hydroprocessing of a 30 to 70 blend SRC I with SRC II in a trickle bed reactor under different process conditions. The results indicate that along with the decrease in toluene insolubles, heteroatom (O,N,S) content, aromatic content and corresponding increase in aliphatic content, the hydrogen-bonded structure and phenolic OH content of the coal-liquid drastically decrease with increase in contact time and temperat… more
Date: July 16, 1979
Creator: Li, N. C.; Tewari, K. C. & Hara, T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Applications of Micellar Enzymology to Clean Coal Technology. Third Quarterly Report

Description: This project is designed to develop methods for pre-combustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid. Dibenzothio… more
Date: July 24, 1990
Creator: Walsh, Carol T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Novel catalysts for methane activation. Quarterly report No. 2, January 1, 1993--March 31, 1993

Description: The objectives of this project are to test novel fullerene based catalysts for application in methane activation. Fullerenes are a recently discovered allotrope of carbon that have been found to possess unusual properties, some of which may be ideal for methane conversion to higher hydrocarbons. The project is divided into three technical tasks. Task 1 deals with the synthesis and characterization of the fullerenes and fullerene soots, Task 2 with the testing of the catalysts, and Task 3 with t… more
Date: July 7, 1993
Creator: Hirschon, A. S.; Malhotra, R. & Wilson, R. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Mineral hydrolysis kinetics

Description: Dissolution rate laws for silicate mineral weathering can be related to kinetics of ligand-exchange reactions. This relation is being tested with an experimental/analytical/theoretical program for measuring the dissolution kinetics of orthosilicate minerals for use in ionic modeling and molecular dynamics computer simulations of solid, aqueous solution, and solid/liquid interface. To date, dissolution rate have been measured for a suite of endmember and mixed-cation orthosilicate minerals (both… more
Date: July 1, 1993
Creator: Westrich, H. R.; Cygan, R. T.; Arnold, G. W. & Casey, W. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Ductility Enhancement of Molybdenum Phase by Nano-sizedd Oxide Dispersions

Description: The present research is focused on ductility enhancement of molybdenum (Mo) alloys by adding nano-sized oxide particles to the alloy system. The research approach includes: (1) determination of microscopic mechanisms responsible for the macroscopic ductility enhancement effects through atomistic modeling of the metal-ceramic interface; (2) subsequent computer simulation-aided optimization of composition and nanoparticle size of the dispersion for improved performance; (3) synthesis and characte… more
Date: July 31, 2008
Creator: Kang, Bruce
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Electronic Structure of Heavy Element Complexes

Description: The area of study is the bonding in heavy element complexes, and the application of more sophisticated electronic structure theories. Progress is recounted in several areas: (a) technological advances and current methodologies - Relativistic effects are extremely important in gaining an understanding of the electronic structure of compounds of the actinides, transactinides, and other heavy elements. Therefore, a major part of the continual benchmarking was the proper inclusion of the appropriat… more
Date: July 25, 2000
Creator: Bursten, Bruce E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Applications of Micellar Enzymology to Clean Coal Technology. [Laccase From Polyporus Versicolor]

Description: This project is designed to develop methods for pre-combustion coal remediation by implementing recent advances in enzyme biochemistry. The novel approach of this study is incorporation of hydrophilic oxidative enzymes in reverse micelles in an organic solvent. Enzymes from commercial sources or microbial extracts are being investigated for their capacity to remove organic sulfur from coal by oxidation of the sulfur groups, splitting of C-S bonds and loss of sulfur as sulfuric acid. Dibenzothio… more
Date: July 24, 1990
Creator: Walsh, C. T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy

Description: Time-resolved soft x-ray photoelectron spectroscopy is used to probe the non-steady-state evolution of the valence band electronic structure of laser heated ultra-thin (50 nm) metal foils and bulk semiconductors. Single-shot soft x-ray laser induced time-of-flight photoelectron spectroscopy with picosecond time resolution was used in combination with optical measurements of the disassembly dynamics that have shown the existence of a metastable liquid phase in fs-laser heated metal foils persist… more
Date: July 28, 2005
Creator: Nelson, A J; Dunn, J; Widmann, K; Ao, T; Ping, Y; Hunter, J et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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EXAFS studies of sodium silicate glasses containing dissolved actinides

Description: Sodium silicate glasses containing dissolved Th, U, Np, and Pu have been studied using the EXAFS technique. Th/sup 4 +/, U/sup 4 +/, Np/sup 4 +/, and Pu/sup 4 +/ ions in the silicate glasses are 8-fold coordinated to oxygen neighbors. The higher valent U/sup 6 +/ and Np/sup 5 +/ ions have complex local symmetries. The U/sup 6 +/ ions appear in a uranyl configuration with 2 oxygen atoms at 1.85A and 4 at 2.25A from the U ion. The Np/sup 5 +/ local symmetry is more complex and difficult to determ… more
Date: July 1, 1984
Creator: Knapp, G. S.; Veal, B. W.; Paulikas, A. P.; Mitchell, A. W.; Lam, D. J. & Klippert, T. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Temperature dependence of soliton diffusion in trans-polyacetylene

Description: The temperature dependence of 1-D diffusion rate of solitons in transpolyacetylene is determined by time-domain analysis of ESR measurements. The diffusion rate appears to obey a simple power law. Monte Carlo simulation of 1-D diffusion process in impure chains indicates that overall diffusion can be much slower than that without traps.
Date: July 1, 1997
Creator: Tang, J.; Norris, J. R. & Isoya, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Binding of hydrocarbons and other extremely weak ligands to transition metal complexes that coordinate hydrogen: Investigation of cis-interactions and delocalized bonding involving sigma bonds

Description: This is the final report of a three-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). At the forefront of chemistry are efforts to catalytically transform the inert C-H bonds in alkanes to more useful products using metal compounds. The goal is to observe binding and cleavage of alkane C-H bonds on metals or to use related silane Si-H bonding as models, analogous to the discovery of hydrogen (H{sub 2}) binding to metals. Studies of th… more
Date: July 1, 1997
Creator: Kubas, G.J.; Eckert, J. & Luo, X.L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Energies of organic compounds

Description: The studies included hydrolysis of ketals, hydration of alkenes, barrier to rotation about C-O bonds in esters and acids, hydrolysis of lactones, reduction of ketones, non-bonded interactions, and enthalpies of vaporization of ketones, ketals, and other compounds.
Date: July 1, 1995
Creator: Wiberg, K.B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Polymerization of bis(triethoxysilyl)ethenes. The impact of substitution geometry on the formation of ethenyl- and vinylidene-bridged polysilsesquioxanes

Description: Preparation of organically-bridged polysilsesquioxanes has been achieved by polymerizing organic monomers with two or more trialkoxysilyl groups per monomer repeat unit. The nature of the organic bridging group has been shown to strongly impact the final properties (surface area, pore size, and thermal stability) of the end product. For example, rigid arylene bridging groups have been shown to give rise to materials with high surface areas with a relatively large contribution from micropores (<… more
Date: July 1, 1998
Creator: Carpenter, J. P.; Yamanaka, S. A.; McClain, M. D.; Loy, D. A.; Greaves, J. & Shea, K. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Tribological Properties of Self-assembled Monolayers on Au, SiOx and Si Surfaces

Description: Using interracial force microscopy (IFM), the tribological properties of self-assembled monolayer (SAM) on Si surfaces produced by a new chemical strategy are investigated and compared to those of classical SAM systems, which include alkanethiols on Au and alkylsilanes on SiO{sub x}. The new SAM films are prepared by depositing n-alkyl chains with OH-terminations onto Cl-terminated Si substrates. The chemical nature of the actual lubricating molecules, n-dodecyl, is kept constant in all three t… more
Date: July 20, 2000
Creator: Kim, Hyun I.; Boiadjiev, V.; Houston, Jack E.; Zhu, X. -Y & Kiely, J .D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nanohardness and Chemical Bonding of Boron Nitride Films

Description: Boron-nitride (BN) films are deposited by the reactive sputter deposition of fully dense, boron targets utilizing a planar magnetron source and an argon-nitrogen working gas mixture. Near-edge x-ray absorption fine structure analysis reveals distinguishing features of chemical bonding within the boron is photoabsorption cross-section. The hardness of the BN film surface is measured using nanoindentation. The sputter deposition conditions as well as the post-deposition treatments of annealing an… more
Date: July 8, 1998
Creator: Jankowski, Alan Frederic
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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