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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 9 (1963), S. 495-503 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Observations on the rate of ion exchange in Dowex 50W resins are reported. These measurements were made under conditions where solid diffusion was the governing phenomenon for six pairs of ions sodium-zinc, sodium-silver, silver-aluminum, zinc-copper, zinc-aluminum, and aluminum-cerium (trivalent). The effects of temperature and of resin cross-linkage were studied with the first system. Exchange in both directions was studied for each pair except the last.Interpretation with a Fick's law model was accomplished, and diffusion coefficients were obtained for each pair. Values were greatly dependent on the direction of the exchange as well as on the particular pair.Interpretation with a Nernst-Planck model was also accomplished and diffusivities for each ion were obtained. Values were greatly influenced by the nature of the second ion except in the case of sodium. The interpretation in this case required numerical solution of the flux equations. These solutions are presented for valence ratios of 1/3 and 2/3 with diffusivity ratios of 5, 10, and 20 and for valence ratios of 3 and 3/2 with diffusivity ratios of 1/5, 1/10, and 1/20.Activation energies were found to be 4 to 6 kcal/g. mole for either model. Increasing the resin cross-linkage from 4 to 12% decreased the diffusion values by approximately 80%.The data were equally well represented with either model. In view of the simplicity of Fick's law, the use of this model is recommended for design purposes.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 568-573 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 18 (1976), S. 1669-1677 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The black yeast-like fungus Rhinocladiella mansonii NRRL Y-6272 elaborates an extracellular polysaccharide composed of N-acetyl D-glucosamine and N-acetyl D-glucosaminuronic acid residues in a 2:1 molar ratio. Production of this polymer was studied in 300 ml flasks and 20 liter fermentors. On the basis of glucose utilized, 13% conversion to polymer was obtained in four days at 25°C in medium containing yeast autolysate paste, K2HPO4, MgSO4, ZnSO4, L-asparagine or urea, and D-glucose. Nitrogen sources, aeration, agitation, temperature, and salts affected yields.The polymer in diluted fermentation broths was precipitated with ethanol in the presence of an electrolyte and collected by centrifugation. The viscosities of aqueous resolutions containing 1 and 1.5% of the polymer were 9400 cP and 21,500 cP, respectively.
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  • 4
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Xanthan gum is a heteropolysaccharide synthesized by Xanthomonas campestris NRRL B-1459 and is composed of D-glucose, D-mannose, and D-glucuronic acid, in addition to acetic and pyruvic acids. Different amounts of pyruvic acid ketal are found in various preparations which can influence the viscosities of dilute xanthan solutions. Polysaccharide production on synthetic media was studied in small-scale fermentors. Fermentation conditions were established for production of both high and low pyruvic acid gums (about 4 and 2% pyruvic acid, respectively). Low nitrogen [0.1% (NH4)2HPO4] and air (0.25 vol/liter/min) levels favor production of low pyruvate gum; increasing (NH4)2HPO4 to 0.15%, adding K2HPO4, and increasing the air flow to 1.5 vol/liter/min favored production of normal gum. Both processes gave xanthan yields of 50 to 60%, based on 2.5% initial D-glucose substrate, in two to three days. Differences in pyruvic acid content and in the quantity of gum produced under a given set of conditions were attributed to strain variability. Substrains were isolated that have desirable characteristics for production of xanthan gum; i.e., the ability to give good yields of high-pyruvate gum when grown on both complex and synthetic media.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 938-944 
    ISSN: 0006-3592
    Keywords: Polyphenol oxidase ; tyrosinase ; enzymes in organic media ; o-quinones ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic study of the activity of mushroom polyphenol oxidase in an organic system was carried out to obtain detailed enzyme kinetic data in relation to optimization of reaction conditions and substrate specificity. A simple method for consistent measurement of reaction rates in the heterogeneous enzyme/organic solvent system (consisting of immobilized polyphenol oxidase and a hydrated solution of the substrate in chloroform) was designed. The aqueous content of the system was optimized using p-cresol as the substrate. With this system, a crude extract of Agaricus bisporus was used to hydroxylate and oxidize a range of selected p-substituted phenolic substrates, yielding o-quinone products. Michaelis-Menten kinetics were used to obtain apparent KM and Vmax values with respect to each of these substrates. Results from this analysis indicated a correlation between the enzymic kinetic parameters obtained and the steric requirements of the substrates, which could be rationalized in terms of the restricted flexibility of the enzyme when it is in chloroform and also in terms of substrate and solvent hydrophobicity. In the course of the investigation UV molar absorption coefficients of several o-quinones were measured by a novel method: 1H nuclear magnetic resonance (NMR) spectroscopy was employed to determine component concentrations in reaction mixtures resulting from the transformation of phenols by polyphenol oxidase in chloroform. Thus the UV molar absorption coefficients could be obtained directly, avoiding the necessity to isolate the water-sensitive, unstable o-quinones. © 1993 John Wiley & Sons, Inc.
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  • 6
    ISSN: 0006-3592
    Keywords: buffer exchange ; chromatography ; flow filtration ; dialysis, counter current ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: There are three major methods for buffer exchange of proteins at industrial scale: size exclusion chromatography (SEC), tangential flow filtration (TFF), and countercurrent dialysis (CCD). In order to determine the optimal technology for a given process, a study was done to compare these technologies on a technological and economic basis. This comparison required that new mathematical models be developed which enable the common features of each unit operation to be directly compared. The new concept of a diavolume equivalent for SEC, defined as the inverse of the fractional loading, was also introduced to aid in this comparison. Variables that were examined for each unit operation included range of buffer exchange, dilution of protein solution, yield, buffer requirements, total operating time, throughput, plant space, capital, raw materials, and labor costs. It was found that TFF and CCD have a greater range of buffer exchange than SEC. TFF also provides the advantage that concentration of the protein can readily be accomplished in the same step. For processes of equal batch size and yield, TFF and CCD also provide a two- to five- fold improvement in each of the remaining variables. The major economic advantage in using TFF and CCD over SEC is the decreased plant size required for manufacturing and thus the longer term use of existing facilities. Situations where SEC (or CCD) would be favored over TFF are when protein denaturation occurs in TFF but does not occur in SEC. © 1995 John Wiley & Sons, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 56 (1997), S. 45-55 
    ISSN: 0006-3592
    Keywords: mixed mode chromatography ; high ligand densities ; minimum feedstream pre-processing ; high capacity ; aminocaproic acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mixed mode Sepharose and Perloza bead cellulose matrices were prepared using various chemistries. These matrices contained hydrophobic (aliphatic and/or aromatic) and ionic (carboxylate or alkylamine) groups. Hydrophobic amine ligands were attached to epichlorohydrin activated Sepharose (mixed mode amine matrices). Hexylamine, aminophenylpropanediol and phenylethylamine were the preferred ligands, on the basis of cost and performance. Other mixed mode matrices were produced by incomplete attachment (0-80%) of the same amine ligands to carboxylate matrices. The best results were obtained using unmodified or partially ligand-modified aminocaproic acid Sepharose and Perloza. High ligand densities were used, resulting in high capacity. Furthermore, chymosin was adsorbed at high and low ionic strengths, which reduced sample preparation requirements. Chymosin, essentially homogeneous by electrophoresis, was recovered by a small pH change. The methods described were simple, efficient, inexpensive and provided very good resolution of chymosin from a crude recombinant source. The carboxylate matrices had the best combination of capacity and regeneration properties. The performance of Sepharose and Perloza carboxylate matrices was similar, but higher capacities were found for the latter. Because it is cheaper and can be used at higher flow rates, Perloza should be better suited to large scale application. High capacity chymosin adsorption was found with carboxymethyl ion exchange matrices, but low ionic strength was essential for adsorption and the purity was inferior to that of the mixed mode matrices. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 45-55, 1997.
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  • 8
    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: Die unter Ringöffnung verlaufende Pfropfpolymerisation von Pivalolacton führt zu hochwertigen thermoplastischen Elastomeren; als Initiatoren dienen Carboxylatanionen, die sich statistisch verteilt an einem geeigneten polymeren Substrat befinden. Bei der thermoplastischen Verarbeitung kristallisieren die Poly[pivalolacton]-Segmente leicht aus; sie bilden diskontinuierliche Bereiche, die als verstärkende Vernetzungsstellen dienen und die bei 12-225°C, je nach dem durchschnittlichen Polymerisationsgrad der Pfropfsegmente (P̄n = 4-90), schmelzen. Die Bereiche sind, wie durch Transmissionselektronenmi-kroskopie festgestellt wurde, 5-100 nm groß.Poly[(äthylen-co-propylen-co-l,4-hexadien)-g-pivalolacton] (aus carboxyliertem Ausgangspolymeren hergestellt) und Poly[(äthylacrylat)-g-pivalolacton] wurden eingehend untersucht; ihre physikalischen Eigenschaften entsprechen denen der in der üblichen Art und Weise vulkanisierten und verstarkten Ausgangspolymeren. Der Einfluß von Strukturänderungen auf die Morphologie und die Eigenschaften wird erörtert.
    Notes: Ring-opening graft polymerization of pivalolactone, initiated by carboxylate anion which is randomly located on suitable polymeric substrates, affords high quality thermoplastic elastomers. When processed from the melt, poly(privalolactone) segments readily crystallize into discontinuous domains which serve as reinforcing network tiepoints and melt at 120-225°C according to the average degree of polymerization (P̄n = 4-90) of the graft segments. Transmission electron microscopy shows domain size to be 5-100 nm.Poly([ethylene-co-propylene-co-1,4-hexadiene]-g-pivalolactone) (from carboxylated base polymer) and poly([ethyl acrylate]-g-pivalolactone) were evaluated in detail and have physical properties similar to conventionally cured and reinforced base polymers. The effects of structural variables on morphology and properties are discussed.
    Additional Material: 16 Ill.
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  • 9
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 47 (1960), S. 289-306 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A set of definitions is proposed to describe uniquely the six types of orientation possible in semicrystalline polymeric films. Oriented polymer films were studied by a new x-ray diffraction technique which permits rotation of a sample about a number of independent axes yielding orientation distributions of the crystalline regions. The definitions and the method of measuring the crystallite-orientation distributions have been applied to polyethylene terephthalate films.
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