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  • Wiley-Blackwell  (261)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1029-1050 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A hollow fiber module was used as a reactor for conversion of ethanol to acetaldehyde in the presence of horse liver alcohol dehydrogenase as catalyst. Mass transport rates for NAD+, the overall acetaldehyde generation rate, catalyst effectiveness factors, and the overall order of the reaction with respect to NAD+ concentration were measured. A coupled-substrate reactor with continuous in situ regeneration of cofactor was also examined. Two substrates of opposite redox state were added simultaneously to the feed stream. NADH and acetaldehyde concentrations were monitored in the effluent stream. The cofactor recycle number, or ratio of moles of product to moles of NADH produced, exceeded 10,000 under certain conditions. While decreasing the NAD+ concentration in the feed stream decreased reactor productivity somewhat, it greatly enhanced the ratio of product formed per mole of NAD+ fed to the reactor. It is suggested that high cofactor costs in dehydrogenase reactors may be overcome with efficient in situ regeneration and secondary recovery and recycling of cofactor from the process stream.
    Additional Material: 11 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 1245-1251 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    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 14 (1963), S. 1034-1036 
    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: Radiographical investigations into the SiO2—V2O5 systemIn connection with research into the inhibiting effect of amorphous SiO2 on oil ash corrosion in gas turbines, the SiO2—V2O3 system was subjected to radiographical investigations. It was found that, at temperatures up to 1200° C, no compounds are formed between the components of this system. Nor was it possible to observe the formation of mixed crystals. However, during heat treatment, vanadium pentoxide has the effect of speeding up the crystallisation of amorphous SiO2 (Aerosil). Depending on the test conditions, one thereby obtains cristobalite or tridymite, or the disordered or polytype-structure forms of these modifications.
    Notes: Im Zusammenhang mit dem Studium der inhibitorischen Wirkung von amorphem SiO2 auf die Ölaschenkorrosion bei Gasturbinen wurden im System SiO2—V2O5 röntgenographische Untersuchungen angestellt. Dabei zeigte sich, daß zwischen den Komponenten dieses Systems bei Temperaturen bis zu 1200° C keine Verbindungsbildung eintritt. Auch die Bildung von Mischkristallen konnte nicht beobachtet werden. Vanadiumpentoxyd übt aber während einer Hitzebehandlung übt aber während einer Hitzebehandlung auf amorphes SiO2 (Aerosil) eine kristallisationsbeschleunigende Wirkung aus. Je nach den Versuchsbedingungen entstehen dabei Cristobalit oder Tridymit bzw. die fehlgeordneten oder strukturpolytypen Formen dieser Modifikationen.
    Additional Material: 2 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 339 (1997), S. 233-242 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloadditions. 26. Influence of Substituents in the Allenic ω-Position on the Thermal Behaviour of Aryl AllenecarboxylatesThe [(aryloxycarbonyl)methyl]triphenylphosphonium salts (1a and i), obtained by reaction of aryl bromoacetates with triphenylphophine, react with the acid chlorides 3 in the presence of two equivalents of triethylamine to give the phenyl-or the (1-naphthyl)-2,3-alkadienoates (4a-d and 4e-h), respectively, in the most cases accompanied by the arylalkynoates 6 and 7 and/or with the naphthyl esters 8 of the used acids. Treatment of the [(aryloxycarbonyl) methyl] triphenylphosphonium salts (1a-i) with triethylamine furnishes the phosphoranes 2a-i, which are transformed by reaction with diphenylketene into the aryl 3,3-diphenyl-2,3-butadienoates (5). Heating of the derivatives 4a-d and 5a, bearing the unsubstituted phenyl nucleus in the ester moiety, leads to destruction, while heating of the naphthyl esters 4e-h and 5i - room temperature is sufficient in some cases-induces the IMDA-reaction to give the benzo-tricycles 9a-e. Heating of the 4,4-diphenyl-2,3-butadienoates (5b-h), bearing the alkylsubstituted phenyl ring within the ester component, induces radical dimerization to give the cylobutanes 10b-h, which represent the head to tail dimers.
    Additional Material: 1 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 7 (1956), S. 82-84 
    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: Corrosion Studies Aid Light MetalsBy carefully selecting their uses and making them corrosion resistant for specific applications, magnesium, aluminium, and titanium can be made more useful to many industries.
    Notes: Durch sorgfältige Auslese der Verwendungsmöglichkeiten und Entwicklung der Korrosionsfestigkeit für spezielle Anwendungsarten können Magnesium, Aluminium und Titan für viele Industriezweige von erhöhtem Nutzen sein.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 879-888 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The steady state, nonlinear diffusion equations which describe reactions in constrained enzyme solutions are of great interest in many biological and engineering applications. As in other types of nonlinear differential equations, exact analytical solutions do not exist except in some simplified cases. In this paper, a general procedure is presented for solving numerically for the substrate concentration profile and effectiveness factor utilizing the transformation method suggested by Na and Na. Design correlations for enzyme solutions constrained within spherical membranes are included. The use of a unique definition of the Thiele Modulus in these charts permits the clear illustration of the effects of substrate concentration and external mass transfer resistances on the overall effectiveness factor for the catalyst particle.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 210 (1933), S. 100-104 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An den chemisch reinen Metallen Eisen, Nickel, Kupfer wird unter dem Einfluß der rollenden Reibung in trockener Luft bei Zimmertemperatur die Bildung von Oxyden beobachtet.
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  • 8
    ISSN: 0947-6539
    Keywords: asymmetric catalysis ; metallocenes ; polymerizations ; molecular modeling ; reaction mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the discovery of stereorigid bridged metallocenes, soluble catalysts became available for the stereospecific polymerization of α-olefins. A relatively simple mechanism was used to explain the stereospecificity, primarily in terms of the catalyst symmetry. In this paper we demonstrate that the simple rule of thumb that C2-symmetric catalysts produce isotactic and Cs-symmetric catalysts syndiotactic polypropylene is too narrow. The introduction of one methyl group at the Cp ring in the [{iPr(CpFlu)}ZrCl2]/ MAO system (Flu = fluorenyl, MAO = methylalumoxan) reduces the Cs symmetry to C1, and the resulting catalyst produces hemiisotactic polypropylene. The analogous catalyst with a bulkier tert-butyl group at the Cp ring gives isotactic polypropylene. When the C2 symmetry of [{Me2Si(Ind)2}ZrCl2] (Ind = indenyl) is reduced to C1, a metallocene can be obtained that produces atactic polypropylene. We have broken away from the symmetry-based model and developed a universal model, which accurately describes the experimental microstructures of the polymers by considering the four lowestenergy conformers of the metallocene species coordinating to prochiral propene (Rre, Sre, Ssi, and Rsi) and the positional changes that the polymer chain undergoes during insertion. The relative energy levels of the four diastereomers can be determined by molecular modeling calculations; these energy gradations, in particular the size of the energy gaps, are decisive in determining the stereospecificity. Also, the model permits the stereoerrors to be classified and explained. Through this model the stereosequence of a polymer chain can be calculated and predicted.
    Additional Material: 17 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 684-689 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The cylic undecapeptides cyclosporin (Csp) A, CspD and dihydro CspC (HCspC) were analyzed by high-performance liquid chromatography/thermospray-mass spectrometry (HPLC/TSP-MS) on line with 1-2 pmol injected on column. Mass spectra were characterized by signals corresponding to the [M + H]+ ion as well as fragment ions derived from he loss of 112 (CspA and CspD) or 44, 114 and 114+44 (HCspC) mass units from the parent ion. The same qualitative profile was observed for negative-ion acquisition where the ions were formed by proton abstraction. The application of the technique to the characterization of CspA and its major hydroxylated and dealkylated metabolites in human blood samples is presented.
    Additional Material: 8 Ill.
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  • 10
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This paper deals with the application of a plug flow reactor in connection with quantitative gelpermeation-chromatographical analysis to the polymerization of ethylene catalysed by the soluble Ziegler-Natta-system (C5H5)2 Ti(R)Cl/Al(C2H5)Cl2 (with R = ethyl or higher alkyl).By this method unambiguous kinetic detail is accessible particulary during the formation of the oligomers. So an alkyl transfer between the Al- and the Ti-component and an influence of the chain length on the propagation rate were determined.In the case of (C2H5)2Ti(n-C6H13)Cl the insertion step of one ethylene requires 95 msec in toluene at a temperature of 10°C and a concentration of ethylene of 0,22 mole/1.
    Notes: Es wird die Anwendung des Strömungsrohres in Kombination mit quantitativer gelchromatographischer Analyse auf die Äthylenpolymerisation mit dem löslichen Ziegler-Natta-System (C5H5)2 Ti(R)Cl/Al(C2H5)Cl2 (mit R = Äthyl oder höhere Homologe) als eine Meßmethode beschrieben, die gerade im Oligomerenbereich eindeutige kinetische Aussagen ermöglicht. Sie erbrachte die Aufklärung einer Alkylübertragungsreaktion zwischen der Al- und der Ti-Komponente sowie eine Kettenlängenabhängigkeit der Polymerisationsgeschwindigkeit.Die Dauer eines Äthyleninsertionsschrittes bei (C5H5)2 Ti(n-C6H13)Cl konnte in Toluol bei 10°C und 0,22 mol/l Äthylenkonzentration gemessen werden: sie beträgt 95 msec.
    Additional Material: 6 Ill.
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