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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study on mixed-function oxygenase (MFO) systems was carried out on four echinoderm species: the asteroidsAsterias rubens andMarthasterias glacialis, a holothurianHolothuria forskali and an echinoidEchinus esculentus. Cytochromes P-450 andb 5 and the MFO system-associated NADH-ferricyanide reductases NADH-cytochromec reductase, NADPH-cytochromec reductase and benzo(a)pyrene (BP) hydroxylase activities were present in microsomal fractions of pyloric caeca ofA rubens andM. glacialis and in the haemal plexus ofH. forskali. In contrast, cytochrome P-450 and BP hydroxylase activity were not detectable in the gonads ofE. esculentus. The tissue and subcellular distribution of the MFO system was studied inA. rubens. MFO system components were found in the stomachs and gonads, although detection of cytochrome P-450 in the latter tissue was difficult. Sex-related differences were not significant. The contents of the MFO system components and BP hydroxylase activities were highest in the microsomal (100 000 ×g) fractions, but MFO system components were also found in the mitochondrial (12 000 ×g) and cytosolic fractions. The BP hydroxylase activity in pyloric caeca microsomes ofA. rubens was NADPH-dependent and was inhibited by several agents known to be inhibitors of vertebrate cytochromes P-450. In the former respect, the characteristics of the MFO system were more like those of vertebrates and crustaceans than that of molluscs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 24 (1989), S. 87-95 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Für ein verallgemeinertes Newtonsches Fluid ist die Viskosität η* von der Scherrate $$\dot \gamma *$$ abhängig. Statt nun eine bestimmte Abhängigkeit anzunehmen, wie dies für rheologische Modelle geschieht, wird die Viskosität als Taylor-Reihe in Bezug auf $$\dot \gamma *$$ entwickelt. Ausgehend von dieser Entwicklung wird eine reguläre Störungsrechnung durchgeführt. Dies schließt den Effekt der Reibungswärme ein. Die Grundströmung ist die Strömung eines Newtonschen Fluides. Terme höherer Ordnung berücksichtigen den Einfluß des nicht-Newtonschen Fluidverhaltens. — Die asymptotischen Ergebnisse stimmen gut mit denen spezifischer rheologischer Modelle (power law, Ellis) überein. — Mit der gleichen asymptotischen Methode kann auch der Einfluß der Temperaturabhängigkeit der Stoffwerte erfaßt werden. Damit kann dann der Einfluß sowohl der Scherraten- als auch der Temperaturabhängigkeit auf eine allgemeine Weise für verallgemeinerte Newtonsche Fluide formuliert werden.
    Notes: Abstract For a generalized Newtonian fluid the viscosity η* varies with the shear rate $$\dot \gamma *$$ . Instead of assuming a certain dependence like rheological models do, the viscosity is expanded in a Taylor serie with respect to $$\dot \gamma *$$ . Based on this expansion a perturbation approach to laminar pipe flow withq w = const. and viscous heating included is formulated. The basic flow (zero order solution) is that of a Newtonian fluid. Higher order terms successively account for the influence of a non-Newtonian fluid. — The asymptotic results compare reasonably well with those of specific rheological models like power law or Ellis model. — The influence of temperature dependent properties (including the viscosity) can be accounted for by the same kind of asymptotic approach. The influence of shear rate as well as temperature dependence thus can be combined in general results valid for all generalized Newtonian fluids.
    Type of Medium: Electronic Resource
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  • 3
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    Berlin : Periodicals Archive Online (PAO)
    Deutsche Zeitschrift für Philosophie. 36:5 (1988) 476 
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  • 4
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    Berlin : Periodicals Archive Online (PAO)
    Deutsche Zeitschrift für Philosophie. 30:11 (1982) 1391 
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  • 5
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    Oxford : Periodicals Archive Online (PAO)
    German history. 13:1 (1995) 131 
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  • 6
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    Oxford : Periodicals Archive Online (PAO)
    German history. 13:1 (1995) 131 
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 18 (1984), S. 25-35 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird die laminare Strömung an der ebenen Platte konstanter Wandtemperatur bei mäßigen Geschwindigkeiten unter Berücksichtigung variabler Stoffwerte behandelt. Die Stoffgesetze werden in der Umgebung des Bezugszustandes (be-vorzugt der Anströmzustand, aber auch Wandzustand möglich) in Taylor-Reihen entwickelt, deren Koeffizienten wie die PrandtlZahl dimensionslose Stoffkennzahlen sind, die jedoch nicht spezifiziert werden. Wandschubspannung und Wärmeübergang lassen sich für beliebige Stoffgesetze als Potenzreihe des Parameters ε=(Tw−T∞)/T∞ universell angeben. Für alle Stoffe wird gezeigt, wie bei der Methode der Stoffverhältnisse die Exponenten und bei der Methode der Referenz-Temperatur die ReferenzTemperatur von den Stoffgesetzen abhängen. Damit sind diese beiden genannten Methoden keine empirischen Methoden mehr.
    Notes: Abstract The laminar two-dimensional flow along a flat plate of constant temperature at low velocity is investigated where the temperature dependence of the fluid properties is taken into account. The functions describing the temperature dependence of the fluid properties are expanded as Taylor series at the reference state (preferred free-stream state, but wall state also possible), whose coefficients are dimensionless fluid properties like the Prandtl number, but are not specified for particular fluids. Shear stress and heat flux at the wall are given for arbitrary temperature dependence of the fluid properties as universal power series of the parameter ε=(Tw−T∞)/T∞. For all fluids it is shown, how the exponents in the propertyratio method and the reference temperature in the referencetemperature method depend on the fluid properties. Hence, these two methods are not empirical ones any more.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 20 (1986), S. 47-57 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird der Einfluß temperaturabhängiger Stoffwerte auf laminare Grenzschichtströmungen am Beispiel der Keilströmungen (Falkner-Skan) betrachtet. Für die RandbedingungenT w= konst und qw= konst wird eine asymptotische Entwicklung für kleine Wärmeübergänge vorgenommen. Lineare Abweichungen von der Grundlösung für konstante Stoffwerte können in Form einer Korrektur geschrieben werden, wie sie in der Literatur als Stoffwertverhältnis-Ansatz bekannt ist. Diese bisher empirische Methode ist damit zu einer theoretischen Methode geworden.
    Notes: Abstract The influence of temperature dependent fluid properties on laminar boundary layer flows is examined for wedge flows (Falkner-Skan). An asymptotic expansion for small heat transfer rates is applied under the boundary conditionsT w= const andq w=const. Linear deviations from the zero order solution (constant properties) can be given in a form known as the property ratio method. As a consequence this method is no longer an empirical one.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 19 (1985), S. 19-30 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Es wird zunächst die laminare natürliche Konvektionsströmung in der Nähe eines ebenen Staupunktes und für die senkrechte Platte betrachtet. Die Stoffgesetze werden in der Umgebung des Bezugszustandes T∞ (Umgebungstemperatur) in Taylor-Reihen entwickelt, deren Koeffizienten dimensionslose Stoffkennzahlen — wie die Prandtl-Zahl — sind, die als freie Parameter in die Rechnung eingehen. Wandschubspannung und Wärmeübergang lassen sich für beliebige Stoffgesetze als Potenzreihe eines Parametersε universell angeben. Der Entwicklungsparameterε ist dabei ein Maß für die Stärke der Wärmeübertragung. Ein Vergleich mit der Methode der Stoffwertverhältnisse ermöglicht die Bestimmung der dort vorkommenden Exponenten für alle Stoffe, ohne daß auf empirische Daten zurückgegriffen werden muß. Aus den Ergebnissen wird dann eine nicht-rationale Näherungsbeziehung für beliebige zylindrische Körper gewonnen.
    Notes: Abstract First the free convection laminar flow near a plane stagnation point and at the vertical flat plate is investigated. The functions describing the temperature dependence of the fluid properties are expanded as Taylor series at the reference state T∞ (ambient temperature) whose coefficients are dimensionless fluid properties like the Prandtl number, but are not specified for particular fluids. Shear stress and heat flux at the wall are given for arbitrary temperature dependence of the fluid properties as universal power series of a parameterε. This perturbation parameterε describes the strength of heat transfer. Comparison with the property-ratio method shows how the exponents in that method depend on the fluid properties without any need of empirical information. From these results a non-rational approximation for arbitrary cylindrical bodies is developed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 34 (1998), S. 9-18 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A fully developed laminar Poiseuille flow subject to constant heat flux across the wall is analysed with respect to its stability behavior by applying a weakly nonlinear stability theory. It is based on an expansion of the disturbance control equations with respect to a perturbation parameter ε. This parameter is the small initial amplitude of the fundamental wave. This fundamental wave which is the solution of the linear (Orr-Sommerfeld) first order equation triggers all higher order effects with respect to ε. Heat transfer is accounted for asymptotically through an expansion with respect to a small heat transfer parameter ε T . Both perturbation parameters, ε and ε T , are linked by the assumption ε T =O(ε2) by which a certain distinguished limit is assumed. The results for a fluid with temperature dependent viscosity show that heat transfer effects in the nonlinear range continue to act in the same way as in the initial linear range.
    Type of Medium: Electronic Resource
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