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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematische Annalen 94 (1925), S. 97-100 
    ISSN: 1432-1807
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Cell suspensions of uptake-hydrogenase-deficient (hup -) mutants of a wild-type (B10S) and a nifHDK deletion strain of Rhodobacter capsulatus were used comparatively to characterize the conventional, Mo-containing and the alternative, “iron-only” nitrogenase of this organism by determining the H2 production and acetylene reduction activities under argon and dinitrogen atmospheres. A comparison with the corresponding hup + strains revealed that the hup - mutation did not affect the nitrogenase activity and specificity within the acetylene-reduction assay, but caused a significant increase in H2 production, which was more prominent in the case of the ΔnifHDK strain. The ΔnifHDK hup - cells, grown in Mo-depleted medium and, thus, expressing the alternative nitrogenase system, were more than ten times less active in the acetylene-reduction assay but exhibited H2 production rates equivalent to about 60% of the rates obtained with B10S hup - cells after growth in a medium containing 10 μM MoO- 4. When these conditions were applied, the B10S strain only expressed the Mo nitrogenase. Under an argon atmosphere containing about 5.5% (v/v) acetylene and under a dinitrogen atmosphere, ΔnifHDK hup - cells produced H2 at even higher rates than B10S hup - cells. The implications of our findings on a possible biotechnological H2 production and on the mechanism of nitrogenase catalysis are considered.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 17 (1949), S. 403-417 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Zusammenfassung Zur Berechnung der Strömung einer kompressiblen Flüssigkeit mit der Geschwindigkeit $$\mathfrak{v}$$ kann man von der entsprechenden Geschwindigkeit $$\mathfrak{B}$$ der inkompressiblen Strömung ausgehen und in erster Näherung $$\mathfrak{v}/v_\infty = (\mathfrak{B}/V_\infty )\sqrt { {{\varrho _\infty } \mathord{\left/ {\vphantom {{\varrho _\infty } \varrho }} \right. \kern-\nulldelimiterspace} \varrho }} $$ setzen. Eine zweite Näherung ergibt sich aus dem Felde von Quellen und Wirbeln, die bei der ersten Näherung vernachlässigt sind. Die zur Berechnung dieses Feldes nötige Integration über die ganze Strömungsebene kann wesentlich vereinfacht werden, indem man entweder in einer Ebene, in welcher der umströmte Rand ein Kreis ist, die Belegung der Quellen und Wirbel durch trigonometrische Polynome ausdrückt, deren Felder leicht anzugeben sind, oder indem man das Flächenintegral auf ein Rand-integral zurückführt. Nach der ersten Methode wurde die Strömung um einen Kreiszylinder, nach der zweiten die um Ellipsen und Flügelprofile berechnet. Um für die Praxis die immerhin ziemlich umständliche Berechnung der zweiten Näherung zu ersparen, wurde auf Grund der berechneten Korrekturen eine praktische Rechenformel zur Abschätzung dieser Korrektur angegeben [Gleichung (84)], welche die berechneten Werte gut wiedergibt.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 27 (1993), S. 6-19 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-2313
    Keywords: Nickel ; Schiff base complexes ; synthesis ; crystal structure ; hydrogenase ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Green Bis-(2-iminoisopropyl-thiophenolato)nickel(II) and other Similar NiII ComplexesThe compounds [NiII(iitp)2] 1 (iitp = 2-iminoisopropyl-thiophenolate), [Ni2II(imptp)2] · 2 CH3OH 2, a dinuclear compound with an Ni—Ni distance of 276 pm, and [PPh4] · [NiII(imptp)(SCN)] 3 (imptp = 2-(2-iminopentane-4-on)-thiophenolate) have been prepared by the reaction of nickel(II)-acetate-tetrahydrate with 2-iminoisopropyl-thiophenole and 2-(2-iminopentane-4-on)-thiophenole in methanol, respectively. They have been characterized by single-crystal X-ray structure analysis and other physical methods. The redox behaviour of 1-3 has been studied in detail (chemically as well as by cyclovoltammetry and ESR spectroscopy). Particularly interesting are the electronic properties of 1 and its reduction with NaBH4 and the following reaction of the product with O2. The complexes are model compounds for some Ni-containing enzymes. For details of the crystal structure determination see “Inhaltsübersicht”.
    Notes: Die Verbindungen [NiII(iitp)2] 1 (iitp = 2-Iminoisopropyl-thiophenolat), [Ni2II(imptp)2] · 2 CH3OH 2, eine Zweikernverbindung mit einem Ni—Ni-Abstand von 276 pm und [PPh4][NiII(imptp)(SCN)] 3 (imptp = 2-(2-Iminopentan-4-on)-thiophenolat) wurden durch Umsetzung von Nickel(II)-acetat-tetrahydrat mit 2-Iminoisopropyl-thiophenol bzw. 2-(2-Iminopentan-4-on)-thiophenol in Methanol dargestellt und durch Einkristallstrukturanalyse und andere physikalische Methoden charakterisiert. Das Redoxverhalten der Verbindungen 1-3 wurde mittels elektrochemischer, chemischer und spektroskopischer Methoden untersucht. Bemerkenswert sind die elektronischen Eigenschaften der grünen Verbindung 1, sowie ihre Reduktion mit NaBH4 und die darauffolgende Umsetzung des Reaktionsproduktes mit O2. Die Verbindungen besitzen Modellcharakter für einige Ni-haltige Enzyme.1: C2/c, a = 1298,3(2); b = 695,7(1); c = 1958,7(3) pm; β = 103,92(1)°; V = 1717,4(5) · 106 pm3; R = 0,035 für 1230 unabhängige Reflexe (Fo 〉 4σ(Fo)), Z = 4.2: P1, a = 947,9(2); b = 1229,5(3); c = 1254,7(3) pm; α = 67,28(2), β = 74,63(2), γ = 81,18(2)°; V = 1298,4(5) · 106 pm3; R = 0,082 für 3655 unabhängige Reflexe (Fo 〉 4σ(Fo)), Z = 2.3: P21, a = 1119,3(2); b = 2389,7(4); c = 1245,8(2) pm; β = 102,52(1)°; V = 3253,0(9) · 106 pm3; R = 0,051 für 4218 unabhängige Reflexe (Fo 〉 4σ(Fo)), Z = 4.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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