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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 1008-1016 
    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 efficient iterative method for solving the equations which describe the steady state of a staged countercurrent extraction process is described. The equations include the effects of backmixing, and apply to an arbitrary number of solutes, to nonlinear equilibrium relations, and to variable net phase flow rates (and thus to partially miscible solvents). The solution procedure, based on partial linearization of the equations, is related to and extends the method of Ricker et al. (1980).This solution procedure has been used, in conjunction with nonlinear regression methods, to investigate problems related to the determination of parameters by analyzing steady state data. The simultaneous determination of several parameters, including mass transfer coefficients, backmixing coefficients, and equilibrium constants, is shown to be possible. The accuracy with which the parameters can be estimated depends, however, on many factors, including the number and location of the sampling points, the intensity of the backmixing, and the extent to which equilibrium is approached in the column.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 805-811 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model of mass transport through dispersed-phase networks to be used for the sustained release of drugs or other solutes at steady rates is presented. The drug is assumed to be encapsulated within the dispersed microdomains and transported to the bulk by diffusion across the interface. A drug is released to the surroundings by diffusion through the bulk. The results show that the desired steady flux of a drug to the surroundings may be obtained given appropriate values of structural properties of the network. These properties may be manipulated easily in the fabrication of dispersed-phase networks reported previously.
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 35 (1984), S. 7-15 
    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: ESCA Untersuchungen an Stählen, gebeizt in HCl mit und ohne InhibitorzusatzEs wird berichtet über ESCA Untersuchungen (Electron Spectroscopy for Chemical Analysis) an kalt gewalzten ST 13 Stahlproben, gebeizt in HCl-Lösung mit und ohne Inhibitor-Zusatz (Dibutylthioharnstoff, DBTU). Die Ergebnisse zeigen, daß das DBTU-Molekül dissoziativ an der Metalloberfläche chemisorbiert wird. Das häufig benutzte Inhibitionsmodell, daß die Metalloberfläche durch die Inhibitormoleküle vollständig bedeckt wird und damit das Metall vor dem Angriff durch die Säure geschützt wird, kann für den Inhibitor DBTU durch unsere ESCA-Experimente nicht bestätigt werden. Die Ergebnisse sind in Übereinstimmung mit anderen Beobachtungen über die Chemisorption schwefelhaltiger Moleküle an Eisen-Oberflächen.
    Notes: ESCA experiments (Electron Spectroscopy for Chemical Analysis) on cold rolled ST 13 steel samples, etched in HCl solutions without and with inhibitor additives (dibutylthiourea, DBTU) are reported.These data showed, that DBTU is dissociatively chemisorbed at the metal surface. The frequently used assumption that the metal surface is covered by the inhibitor molecules preventing the direct attack of the acid cannot be confirmed by our ESCA results, at least for the inhibitor DBTU. The results are in agreement with previous findings on the chemisorption of sulphurous molecules on iron surfaces.
    Additional Material: 13 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 469-479 
    ISSN: 0006-3592
    Keywords: cellulase ; cellulose ; adsorption ; kinetics ; mathematical model ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two fractions of substrate in microcrystalline cellulose which differ in their adsorption capacities for the cellulases and their susceptibility to enzymatic attack have been identified. On the basis of a two-substrate hypothesis, mathematical models to describe enzyme adsorption and the kinetics of hydrolysis have been derived. A new nonequilibrium approach was chosen to predict cellulase-cellulose adsorption. A maximum binding capacity of 76 mg protein per gram substrate and a half-maximum saturation constant of 26 filter paper units (FPU) per gram substrate have been calculated, and a linear relationship of hydrolysis rate vs. adsorbed protein has been found. The fraction of substrate more easily hydrolyzed, as calculated from hydrolysis data, represents 19% of the total effective substrate concentration. This fraction is only slightly different from that of other celluloses and has been estimated to be 27% and 30% for NaOH- and H3PO4-swollen cellulose, respectively. The effective substrate concentration is equal to the maximum amount of the substrate which can be converted during exhaustive hydrolysis. This in turn is determined by the overall degradability of the substrate by the cellulases (85-90% for microcrystalline cellulose) and by the cellobiose concentration during hydrolysis. The kinetic model is based on a summation of two integrated first-order reactions with respect to the effective substrate concentration. Furthermore, it includes the principal factors influencing the reaction rates: the ratio of filter paper and β-glucosidase units per gram substrate and the initial substrate concentration. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 197 (1931), S. 257-269 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 200 (1931), S. 74-81 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 199 (1931), S. 149-164 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 217 (1934), S. 22-26 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 9
    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: An Folien (Dicke 100 pm) aus isotaktischem Polypropylen mit verschiedenen Antioxidansgehalten (0,0% bis 0,1%) wird die thermooxidative Alterunq mit der isothermen Langzeit-Differential-Thermo-Analyse (ILDTA) bis zu Temperaturen weit unter dem Kristallitschmelzbereich verfolqt und die Messwerte mit Ergebnissen aus dem Zeitstand-Zugversuch korreliert. Dabei zeigt sich, daß aus Messunqen mit der ILDTA bereits vor Einsetzen der autokatalytischen Zersetzunq sreaktion Ruckschlüsse auf die thermische Vorqeschichte der Proben und Aussagen auf das rnit einem Abfall der mechanischen Eigenschaften verbundene Ende der thermo-oxidativen Stabilität des Polymeren getroffen werden können.Weiters bietet die ILDTA die Moglichkeit, durch den direkten Zusamenhang zwischen Oxidationszeit und Antioxidansögehalt die örtliche Stabilisatorverteilung in Platten und in Folien zu bestimmen und damit Diffusionsvorqange zu verfolgen.
    Notes: Thermo-oxidative ageing processes were investigated in films (100 μm thick) made from isotactic polypropylene with different antioxidant concentrations between 0% and 0.1% using isothermal long-term differential thermal analysis (ILDTA). The end of the oven life of polypropylene coincided with the loss of mechanical properties which was confirmed by tensile tests at temperatures far below the crystallite melting range. Already prior to the beginning of autocatalytic decomposition, ILDTA experiments permits conclusions to be drawn on the thermal history of the specimens and statements made regarding the end of thermo-oxidative stability of the polymer, which is accompanied by a deterioration in the mechanical properties.In consequence of the correlation between oxidation time and antioxidant concentration the local antioxidant concentration in sheets or films can be measured by ILDTA. Thus, investigating the diffusion of an antioxidant in polypropylene using ILDTA is possible.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 109 (1976), S. 1575-1576 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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