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  • 1
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrogenase regulation ; Glutamine synthetase ; Methionine suofoximine ; Rhodospirillaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methionine sulfoximine (MSX), an irreversible inhibitor of glutamine synthetase of Rhodopseudomonas palustris restored nitrogenase activity to cells in which nitrogenase had been completely inhibited by ammonia switch-off. After addition of MSX, there was a lag period before nitrogenase activity was fully restored. During this lag, glutamine synthetase activity progressively decreased, and near the time of its complete inhibition, nitrogenase activity resumed. Nitrogenase switch-off by ammonia thus required active glutamine synthetase. Glutamine itself caused nitrogenase inhibition whose reversal by MSX depended on the relative ratio of MSX to glutamine. Unlike ammonia, glutamine inhibited nitrogenase under conditions where glutamine synthetase activity was absent. This indicates that glutamine is the effector molecule in nitrogenase switch-off, for instance by interacting with the enzymatic system for Fe protein inactivation. The effects of glutamine and MSX were also dependent on the culture age. Possible explanation for this and for the competitive effects are a common binding site within the regulatory apparatus for nitrogenase, or, in part, within a common transport system. Some observations with MSX were extended to Rhodopseudomonas capsulata and agreed with those in R. palustris.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Nitrogenase regulation ; Glutamine synthetase ; Ammonia switch-off ; Rhodopseudomonas palustris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogenase activity in Rhodopseudomonas palustris is subject to a rapid switch-off in response to exogenous ammonia. When cells were grown on limiting nitrogen and eventually became nitrogen deficient, nitrogenase synthesis was fully derepressed but the enzyme was insensitive to ammonia. The transformation of ammonia-sensitive to ammonia-insensitive cells was a slow, but fully reversible process. The switch-off effect in ammonia-sensitive cells paralleled changes in the adenylylation state of glutamine synthetase. Ammonia-insensitive cells, however, showed similar changes in glutamine synthetase activity although nitrogenase activity was unaffected. We conclude that nitrogenase regulation and adenylylation of glutamine synthetase are independent processes, at least under conditions of nitrogen deficiency.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 306-313 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Structure of the Pentabromocarbonate Anion [CBr5⊖]n - On the Oxidation of En-aminesOxidation of enamines 5 with tetrabromomethane yields stable crystalline pentabromocarbonates 6, which may easily be converted into the corresponding perchlorates 7. From the pentabromocarbonates, tetrabromomethane cannot be extracted either by organic solvents or by heating in vacuo; with silver nitrate, however, silver bromide can be precipitated from tetraphenylphosphonium pentabromocarbonate (9). If labelled 9 - prepared from tetraphenylphosphonium [82Br]bromide and tetrabromomethane - is treated with silver nitrate, all the activity is found in the silver bromide precipitate. This is clear evidence against a trigonal bipyramidal structure of the pentabromocarbonate anion CBr5⊖]n.
    Notes: Bei der Oxidation von Enaminen 5 mit Tetrabrommethan entstehen stabile kristalline Pentabromocarbonate 6, die sich leicht in die entsprechenden Perchlorate 7 überführen lassen. Aus den Pentabromocarbonaten kann Tetrabrommethan weder durch Extraktion mit organischen Solventien noch durch Erhitzen i. Vak. abgespalten werden, mit Silbernitrat kann jedoch aus Tetraphenylphosphonium-pentabromocarbonat (9)Silberbromid ausgefällt werden. Bei der Umsetzung von markiertem 9 - dargestellt aus [82Br] Tetraphenylphosphoniumbromid und Tetrabrommethan - mit Silbernitrat findet man die Gesamtaktivität im Silberbromid-Niederschlag. Dies spricht gegen die Struktur einer trigonalen Bipyramide für das CBr5⊖]n-Anion.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 648-650 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 878-887 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work we present an extension of the statistical associating fluid theory (SAFT) developed for associating fluids by applying this extension to polymer solutions and blends. The polymer molecule is modeled as a flexible chain made of bonded spherical segments. These segments interact with the Lennard-Jones potential. The extension of SAFT is compared with molecular simulation results for polymer solutions and blends. Since the same force model is used in the simulation and theory, this comparison is a strong test of the assumptions made in deriving the theory. Results are presented for pure polymers of up to 50 segments long, polymer solutions of a polymer 20 segments long dissolved in its own monomer, and blends of polymers of 25 segments each. The theory produces results that are in better agreement with simulation results than the Flory-Huggins theory for the systems studied.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 275-276 
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Capillary ; Splitless injection ; Theoretical basis for reconcetration by solvent effects ; Guidelines for an effective solvent effect, in literature citation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 20 (1969), S. 578-583 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Cathodic corrosion of lead in the soilCathodic corrosion of lead in the soil can be expected in exceptional cases only. The corrosion found on a particular lead cable could be simulated in the laboratory. It could be confirmed, that  -  probably by decomposition of primary lead hydride  -  metallic lead is deposited below layers of Ca and Mg compounds already at potentials below -1,7 V. A special switching method was developed to account for breakthrough polarisation.
    Notes: Kathodische Korrosion von Blei im Boden ist grundsätzlich nur in Ausnahmefällen zu erwarten. Diese an einem Kabel gefundene Korrosion wurde im Laboratorium nachgebildet. Hierbei konnte bestätigt werden, daß unter Deckschichten aus Calcium- und Magnesiumverbindungen bei Potentialen schon unter -1,7 V metallisches, Blei abgeschieden wurde, wahrscheinlich durch Zersetzung von primär entstandenem Bleihydrid. Für derartige Untersuchungen wurde eine spezielle Schaltmethode entwickelt, bei welcher auch die Durchtrittspolarisation berücksichtigt wird.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 13 (1967), S. 608-611 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 1070-1074 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An equation using only easily determined physical properties of particles has been developed for calculating the slip velocity of nonspherical particulate solids falling in fluid media in the intermediate flow range where neither the Stokes nor Newton law applies. The variation in Reynolds numbers covered by this work ranged from 12 to 460. Slip velocities calculated from the equation differed from experimental data by an average deviation of only 3.7% when solids of a wide range of diameters (156 to 1,247 microns), densities (71 to 475 lb./cu. ft.), surface shape factors (0.40 to 0.97), and gases of a wide density range (0.01 to 0.31 lb./cu. ft.) were utilized. Thirty-eight different gas-solid systems were studied.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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