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  • 1
    Electronic Resource
    Electronic Resource
    IR Transition Moments of 1,3-Dimethyluracil: Linear Dichroism Measurements and ab Initio Calculations (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 4998-5009 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100070a010
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic Transition Dipole Moments of the 1,N6-Ethenoadenine Chromophore (1994)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 98 (1994), S. 13460-13469 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100102a006
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  • 3
    Electronic Resource
    Electronic Resource
    Histomorphometric and removal torque analysis for TiO2hyphen;blasted titanium implants. An experimental study on dogs. (1992)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 3 (1992), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of the present study was to compare the anchorage of TiO2-blasted screw and cylindrical implants with conventionally used machine-produced screw and cylindrical implants inserted immediately in extraction sockets on dogs. 6 adult mongrel dogs had 3rd and 4th mandibular premolars extracted bilaterally and 24 commercial pure titanium implants were placed immediately in extraction sockets and covered with mucoperiosteum. Each dog had inserted 4 implants: 1 screw implant and 1 cylindrical implant blasted with titanium-dioxide-particles; 1 screw implant and 1 cylindrical implant with machine-produced (m.p.) surface (controls). After a healing period of 12 weeks, 16 implants from 4 animals were used for removal torque test, which demonstrated that significantly higher removal torque force was needed to unscrew the implants blasted with titanium-dioxide-particles, than the normal m.p. implants. The medians for the TiO2-blasted screw and cylindrical implants were 〉 150 Ncm and 10.5 Ncm, respectively, while the values for the m.p. implants were 60 Ncm and 35 Ncm, respectively. The SEM investigation demonstrated a high irregularity of the TiO2-blasted surface compared to the machined surface. The R, and R, values for surface roughness were higher for the TiO2-blasted implants than for the normal m.p. implants. Histomorphometrically, the arithmetic mean of the direct bone-implant contact fraction was 69%. There was no significant difference in direct bone-implant contact length fraction between TiO2-blasted implants and the control implants. The implants blasted with titanium-dioxide-particles in this study showed a better anchorage than implants with a machine-produced surface. The screw implants showed a better anchorage than the cylindrical implants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.1992.030205.x
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  • 4
    Electronic Resource
    Electronic Resource
    Soft tissue response to clinically contaminated and thereafter cleaned titanium surfaces (2000)
    Copenhagen : Munksgaard International Publishers
    Clinical oral implants research 11 (2000), S. 0 
    Details
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The aim of the present study was to evaluate the soft tissue response to intra-orally exposed and contaminated titanium surfaces (machined, blasted or polished) after being chemically and/or mechanically cleaned. Eight adult Sprague-Dawley rats were used for histomorphometrical and histological analyses. A total of 44 experimental abutments (26 tests and 18 controls) were inserted into abdominal skinpockets of the rats for 6 weeks. No differences regarding the soft tissue response between the different surface characteristics analysed and between test and control could be observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-0501.2000.011004370.x
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  • 5
    Electronic Resource
    Electronic Resource
    Biological effects in a chemical factory with mutagenic exposure (1988)
    Springer
    International archives of occupational and environmental health 60 (1988), S. 453-456 
    Details
    ISSN: 1432-1246
    Keywords: Ethylene oxide ; Fluctuation test ; Formaldehyde ; Piperazine ; Thioethers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eighty-five workers in a chemical plant, in which there was an increased frequency of B-lymphocyte tumours (myelomas and lymphomas) and lung cancer, did not excrete higher amounts of thioethers in urine than 48 control subjects. The chemically exposed workers had, however, a higher excretion of thioethers in urine during shift compared to an exposure-free period. The bacterial fluctuation test showed a statistically significantly increased mutagenic activity for E. coli Wp2 uvrA, but not for Salmonella TA98, in the urine of the exposed workers compared with the controls. However, no difference in excretion was found in the chemical workers between work and an exposure free-period. Further, no association of thioether or mutagen excretion with any specific chemical exposure (e.g. ethylene oxide and formaldehyde) in the plant could firmly be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381394
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  • 6
    Electronic Resource
    Electronic Resource
    Coke formation on nickel-chromium-iron alloys (1987)
    Springer
    Journal of materials science 22 (1987), S. 4518-4522 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Coke formation during the steam cracking of propane has been studied on foils of nickel and of a series of nickel-chromium-iron alloys with a nickel content between 8 and 74wt%. The experiments were carried out at 810 and 850° C in a tubular flow reactor. Coke deposition was measured on prereduced foils using a microbalance. After an initial period the rates of coke deposition on the alloy foils tend to approach a common value independent of the nickel content. On the pure nickel foils a substantially higher rate of coke formation was observed. The results can be explained in terms of the surface composition of the foils as measured by Auger electron spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01132055
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  • 7
    Electronic Resource
    Electronic Resource
    Pyrolysis of methane in the presence of hydrogen (1995)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 18 (1995), S. 349-358 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of methane pyrolysis were studied in a tubular flow reactor in the temperature range 1200 to 1500°C at atmospheric pressure. To avoid excessive carbon formation the reaction time was short and the methane feed was diluted with hydrogen. Ethene, ethyne, benzene and hydrogen were the main gaseous products. Ethane was observed as a product at very low conversions of methane. More than 90% selectivity was obtained for C2 products. The ratio of ethyne to ethene increased with increasing temperature. The yield of C2 products is limited by gas-phase equilibrium at lower temperatures. Formation of carbon was strongly depressed by hydrogen at higher temperatures. The maximum yield of ethyne was found to increase from about 10% to about 50% when the temperature was increased from 1200 to 1500°C, with hydrogen dilution H2: CH4 = 2: 1. A mechanistic reaction model was used to simulate the pyrolysis of methane at the actual conditions. A sensitivity analysis was performed to evaluate the elementary reactions which influence the formation and consumption of the species in the model system.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270180510
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  • 8
    Electronic Resource
    Electronic Resource
    A theoretical investigation of the solution N(7) H ↔ N(9) H tautomerism of adenine (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 56 (1995), S. 113-122 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometries of the two most important tautomeric forms of adenine and the corresponding methyladenines are investigated by means of quantum chemical calculations at different level of sophistication, ranging from semiempirical methods to correlation corrected ab initio methods at second-order Møller-Plesset perturbation theory level (MP2). The relative stability of the N(7)H ↔ N(9)H tautomeric forms of adenine are investigated with highly correlation corrected methods, MP3 and MP4. The relative stability is also corrected for solvent interactions and compared with experimental information. N(9)H-adenine is predicted to be the most stable tautomer in both vacuum and in solution. The relative stability is predicted to be between 24.5 and 35.0 kJ/mol in vacuum depending on computation method. In water solution N(7)H-adenine is stabilized more by the solvent, and the corresponding relative energies were found to be between 4.9 and 10.2 kJ/mol. We also found that correlation effects are essential to describe the ground state geometry with a high accuracy. The geometries predicted by semiempirical methods and ab initio calculations without correlation correction show large deviations in some parts of the molecule compared to the MP2 results as well as compared with experimental geometries. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560560712
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  • 9
    Electronic Resource
    Electronic Resource
    CO hydrogenation over supported cobalt catalysts: FTIR and gravimetric studiesDedicated to Professor Dr. Manfred Baerns on the occasion of his 60th birthday (1995)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 18 (1995), S. 125-131 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogenation of CO over supported cobalt catalysts has been studied using in situ FTIR spectroscopy and gravimetry at P = 6 bar, T = 473-723 K and H2/CO = 2-3. On both silica- and alumina-supported catalysts IR absorption bands corresponding to linearly adsorbed CO on metallic cobalt were observed. On alumina an additional pair of bands at lower frequencies was attributed to bridge-bonded CO. Absorption bands corresponding to adsorbed hydrocarbons (3050-2700 cm-1) and to oxygen containing species (1800-1200 cm-1) were found to correspond to adsorbed products or unreactive species. The gravimetric studies showed a significant difference between the supports. On the silica-supported catalyst the weight uptake decreased with increasing temperature (473-573 K). The weight increase during reaction was attributed to adsorbed hydrocarbon reaction products. On the alumina-supported catalyst the weight uptake increased with increasing temperature, and there was also a significant weight increase with the support alone. Most of the weight uptake can be attributed to the formation of stable formate and carbonate species on the alumina support. At 723 K the deposits formed were stable in H2, and the shape of the curves indicated different mechanisms for deposition of material. In particular the Co/Al2O3 sample showed a very high and linear rate of weight gain, which was an order of magnitude higher than for the other samples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270180207
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