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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 613 (1990), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 32 (1990), S. 680-685 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The kinetics and equilibria of cephalosporin C adsorption on different commercial adsorbents were investigated. Adsorption isotherms could be analysed according to the Brunauer, Emmett and Teller theory. For the interpretation of adsorption kinetics it was necessary to develop a more complex model comprising both a rapid and a slower step. An integrated approach combining kinetics and equilibria allowed for simulation of the experimental data and can be used as a basis for predicting technical approaches such as fluidized-bed technology.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 36 (1992), S. 604-610 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Investigations on the microbial modification of sucrose to the corresponding 3-keto-derivative were carried out with resting cells of Agrobacterium tumefaciens NCPPB 396. This highly specific oxidation to yield the 3-keto-derivative has been analysed kinetically with varying substrate and cell mass concentrations. The formation of the corresponding 3-keto-derivative depended strongly on the reaction time and the aeration rate, and was maximal at aeration rates up to 11.5 volume air/cultivation volume per minute with resting cells. The product formation increased with increasing substrate concentrations. However, the product yield was maximal at substrate concentrations below 20 g/l. Data pertaining to the production of active cell mass as well as for maximal 3-keto-derivative formation are presented in this paper. Also included are some applications for these derivatives.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 95-104 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The apparent activation energy of N-α-benzoyl-L-arginine-ethyl ester (BAEE) hydrolysis by immobilized trypsin varies with the bulk substrate concentration from its maximum value, comparable to that of the free enzyme, to considerably lower values. Thus, with a concentration change from 3 × 10-2 to 10-4 M the apparent activation energy diminishes from 9.5 to 4.5 kcal/mol. This experimental finding is interpreted to be due to Michaelis-type kinetics in a heterogeneous system, in one case reflecting the temperature dependence of the maximal enzyme reaction rate, in another case illustrating the diffusion limited overall reaction at low substrate concentrations. As a consequence it may not be feasible to operate a reaction at elevated temperatures in a high conversion range, since diffusion limitation may restrict the enhancement of the overall reaction rate. Some further data are given concerning the buffer effect on the reaction rate, which should occur due to its limitation by proton transfer in the buffer-free system.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 1201-1220 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucose oxidation by immobilized glucose oxidase (GlO) and catalase (Cat) has been investigated in batch and continuous reactions for operational studies. The macrokinetics of the process depend on coupled reaction steps and diffusion rates. The problem may be approximated by a simple pseudohomogeneous model taking into account both substrates of glucose oxidase and the intermediate reaction product H2O2. The effectiveness of both enzymes is enhanced in the coupled reaction path, the overall effectiveness nevertheless is very low. H2O2 causes the inactivation of both GlO and Cat. The rates of deactivation depend on the oxidation rates of glucose that give different quasistationary levels of H2O2 concentration. As a first approximation, the deactivation rates may be described by first-order reactions with respect to H2O2.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 2061-2081 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a previous paper, the overall or macrokinetics of the immobilized glucose oxidase-catalase system has been presented. In this paper a detailed analysis of the interaction of diffusion and reaction in this system will be presented. The mathematical treatment includes two consecutive reactions with two-substrate kinetics. Furthermore, the deactivation of both enzymes due to the intermediate product peroxide is taken into account. The predicted results suggest that the efficiency of the glucose oxidase reaction depends on the concentration ranges of the two substrates. Furthermore, the external mass-transfer rate may cause a shift from glucose limitation to oxygen limitation. The efficiency of the coupled system is always higher than that predicted for the uncoupled reaction path. The calculations show that the economics of the coupled system depend a great deal on the deactivation of the enzymes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 15 (1993), S. 139-144 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Microbial modification of the disaccharide isomaltulose to 3-keto-isomaltulose by resting cells of Agrobacterium tumefaciens was investigated with respect to kinetics and yield. After optimization of the reaction conditions, yields of about 90 % were achieved. This specific oxidation was also applied to derivates of isomaltulose (sugar alcohol, amino alcohol).
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 1 (1979), S. 451-456 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract For catalyst optimization, enzyme immobilization may be controlled in such a way that most of the protein is fixed in the outer shells of a porous particle. Calculation of the profiles of fixed enzymes predicts efficiencies similar to those found experimentally.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 1 (1979), S. 15-20 
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Waterinsoluble catalysts with high activity and homogeneous enzyme distribution show low efficiency when using low substrate concentrations, high molecular weight substrates of unbuffered systems. This paper presents an optimised.catalyst design by introducing inhomogeneous enzyme distribution throught the matrix which leads to higher efficiencies.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 177 (1977), S. 9-28 
    ISSN: 1432-0878
    Keywords: Superposition eye ; Lamina ganglionaris ; Cloeon dipterum ; Light- and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lamina ganglionaris of the superposition eye of Cloeon dipterum is composed of separate optic cartridges arranged in a hexagonal pattern. Each optic cartridge consists of one central, radially branched monopolar cell (Li) surrounded by a crown of seven retinula cell terminals and two more unilaterally branched monopolar cells (La1/La2) situated close together outside the cartridge. Projections to neighbouring cartridges have not been observed. In most cases, synaptic contacts could be seen between a presynaptic retinula cell and more than two other postsynaptic profiles, which belong to monopolar cells or sometimes to glial cells. Seven retinula cell fibers of one ommatidium pass in a bundle through the basement membrane, run into their respective cartridges without changing orientation and terminate at approximately equal levels in the lamina. Long visual fibers with endings in the medulla are not visible in the superposition eye lamina, but are present in the lateral apposition eye. The relationship between the behaviour of the animal, optic mechanisms of the superposition eye and the structure of the lamina is discussed.
    Type of Medium: Electronic Resource
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