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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 1887-1903 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By employing a two-stage continuous-culture system, some of the more important physiological parameters involved in cellulose biosynthesis have been evaluated with an ultimate objective of designing an optimally controlled cellulose process. The two-stage continuous-culture system was run for a period of 1350 hr with Trichoderma reesei strain MCG-77. The temperature and pH were controlled at 32°C and pH 4.5 for the first stage (growth) and 28°C and pH 3.5 for the second stage (enzyme production). Lactose was the only carbon source for the both stages. The ratio of specific uptake rate of carbon to that of nitrogen, Q(C)/Q(N), that supported good cell growth ranged from 11 to 15, and the ratio for maximum specific enzyme productivity ranged from 5 to 13. The maintenance coefficients determined for oxygen, MO, and for carbon source, MC, are 0.85 mmol O2/g biomass/hr and 0.14 mmol hexose/g biomass/hr, respectively. The yield constants determined are: YX/O = 32.3 g biomass/mol O2, YX/C = 1.1 g biomass/g C or YX/C = 0.44 g biomass/g hexose, YX/N = 12.5 g biomass/g nitrogen for the cell growth stage, and YX/N = 16.6 g biomass/g nitrogen for the enzyme production stage. Enzyme was produced only in the second stage. Volumetric and specific enzyme productivities obtained were 90 IU/liter/hr and 8 IU/g biomass/hr, respectively. The maximum specific enzyme productivity observed was 14.8 IU/g biomass/hr. The optimal dilution rate in the second stage that corresponded to the maximum enzyme productivity was 0.026 ∼ 0.028 hr-1, and the specific growth rate in the second stage that supported maximum specific enzyme productivity was equal to or slightly less than zero.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 41 (1990), S. 303-307 
    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: Influence of HCl and Cl2 on high temperature corrosion of 2 1/4Cr 1 Mo Steel in atmospheres with high oxygen pressuresThe oxidation of the 2 1/4 Cr 1 Mo steel was investigated at 773 K in oxidizing He-O2-HCl atmospheres. The addition of HCl to He-O2 atmospheres leads to accelerated oxidation rates. Below porous and cracked oxide scales condensed chlorides are formed. At low HCl pressures 0-1000 vppm the “active oxidation” is determining the corrosion process; i.e. oxidation of evaporating chlorides within the oxide scale. For higher HCl contents 1000-3000 vppm the corrosion behaviour changes to paralinear; i.e. simultaneous parabolic oxide growth and linear mass loss by chloride evaporation.
    Notes: Die Oxidation des 2 1/4Cr1Mo-Stahls in oxidierenden He-O2-HCl-Atmosphären bei 773 K wurde untersucht. Der Zusatz von HCl zu He-O2-Atmosphären führt zu stark beschleunigter Oxidation. Unter porösen und rissigen Oxidschichten bilden sich feste Chloride. Bei niedrigen HCl-Drücken 0-1000 vppm bestimmt „aktive Oxidation“ den Korrosionsprozeß; d.h. Oxidation flüchtiger Chloride innerhalb der Oxidschicht. Bei höheren HCl-Drücken 1000-3000 vppm erfolgt ein Übergang zum paralinearen Korrosionsverhalten, d.h. gleichzeitiges parabolisches Oxidwachstum und lineare Massenabnahme durch das Abdampfen von Chloriden.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 43 (1992), S. 547-557 
    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: Effects of chlorides on the oxidation of the 2¼ Cr-1 Mo steelEffects of NaCl deposited on oxide scales were investigated for the oxidation of the 2¼Cr-1 Mo steel in the temperature range 450-650 °C. The presence of NaCl causes accelerated oxidation under formation of porous and cracked Fe2O3 layers and of solid FeCl2 at the metal/oxide interface. By reaction of the chloride with the oxide scale Cl2 is formed, which penetrates into the scale and forms FeCl2 at the inner phase boundary, this is evaporating continuously and is oxidized to iron oxide upon diffusing to the surface, whereby the chlorine is set free again. An active oxidation results which is catalysed by Cl2. The rate of the accelerated oxidation is determined mainly by the evaporation and outward diffusion of gaseous FeCl2 and therefore by temperature by temperature and thickness of the oxide scale. Other parameters such as the flow velocity, the area covered with NaCl or the chlorine pressure, which is present at the outer oxide scale have less effect on the overall rate.
    Notes: Der Einfluß von auf die Zunderschichten aufgebrachten NaCl-Ablagerungen auf die Oxidation des 2¼ Cr-1 Mo-Stahls wurde bei 450 °C-650 °C untersucht. Die Anwesenheit von NaCl führt zu stark beschleunigter Oxidation unter Bildung poröser und rissiger Fe2O3-Schichten, sowie von festem FeCl2 an der Metall/Oxid-Grenzfläche. Durch Reaktion des Chlorids mit der Zunderschicht entsteht Cl2, das in die Schicht eindringt und an der inneren Phasengrenze FeCl2 bildet, dieses verdampft stetig und wird dann bei der Diffusion zur Oberfläche zu Eisenoxiden oxidiert, wobei das Chlor wieder freigesetzt wird. Es resultiert eine durch Cl2 katalysierte “aktive Oxidation”. Die Geschwindigkeit der beschleunigten Oxidation wird im wesentlichen bestimmt durch die Verdampfung und Auswärtsdiffusion des gasförmigen FeCl2 und damit durch Temperatur und Oxidschichtdicke. Andere Parameter, wie die Strömungsgeschwindigkeit, die mit NaCl bedeckte Fläche oder der Cl2-Druck, der sich und der äußeren Oxidoberfläche einstellt, haben einen geringeren Einfluß auf die Gesamtreaktionsgeschwindigkeit.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 44 (1993), S. 41-47 
    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: Effects of sodium chloride on the oxidation of high alloy Cr- and Cr-Ni-steelsThe effects on the oxidation were investigated of solid NaCl deposits on the oxide scales of the technical steels X10 CrMoV 12 1, X15 CrNiSi 20 12 and X10 CrNiSi 25 20 at 700°C. Independent of the alloy composition the presence of NaCl(s) initiated a markedly accelerated Fe2O3 growth on the surface of preoxidized samples, under formation of voluminous, nonprotective layers. Below these scales on the metallic matrix in all cases chloride was detected. The oxides grow according to the mechanism of active oxidation in which chlorine plays a catalytic role. The presence of the chloride at the oxide/metal interface reduces the adhesion of the oxide scale and leads to spalling upon cooling to room temperature. The effects observed are independent of the alloy composition, however, the thickness of the oxide scale is decisive which means the diffusion distance for the gaseous iron chloride.
    Notes: Untersucht wurde der Einfluß fester NaCl-Ablagerungen auf der Zunderschicht auf die Oxidation der technischen Stähle X10 CrMoV 12 1, X15 CrNiSi 20 12 und X10 CrNiSi 25 20 bei 700°C. Unabhängig von der Legierungszusammensetzung löste die Anwesenheit von NaCl(s) auf der Oberfläche voroxidierter Proben stark beschleunigtes Wachstum von Fe2O3 aus, unter Bildung voluminöser, nicht-schützender Schichten. Unterhalb dieser Zunderschichten, auf der metallischen Matrix, wurde in allen Fällen Chlorid festgestellt. Das Oxidwachstum erfolgt nach dem Mechanismus der “aktiven Oxidation”, in dem das Chlor eine katalytische Rolle spielt. Die Anwesenheit des Chlorids an der Metall/Oxid-Grenzfläche setzt die Haftung der Zunderschicht herab und führt zum Abplatzen bei Abkühlen auf Raumtemperatur. Die beobachteten Effekte sind unabhängig von der Legierungszusammensetzung, ausschlaggebend ist vielmehr die Dicke der Oxidschicht und damit der Diffusionsweg des gasförmigen Eisenchlorids.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1043-1045 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 47 (1961), S. 228-229 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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