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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of poly(vinyl alcohol) during the emulsion polymerization of vinyl acetate using poly(vinyl alcohol) as emulsifier (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 849-862 
    Details
    ISSN: 0887-624X
    Keywords: vinyl acetate ; emulsion polymerization of ; poly(vinyl alcohol) emulsifier ; poly(vinyl alcohol) ; grafting onto ; acetonitrile/water extraction ; water-soluble PVA ; water-insoluble PVA ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During the emulsion polymerization of vinyl acetate (VAc) using poly(vinyl alcohol) (PVA) as stabilizer and potassium persulfate as initiator, the VAc reacts with PVA forming PVA-graft-PVAc. When the grafted polymer reaches a critical size it becomes water-insoluble and precipitates from the aqueous phase contributing to the formation of polymer particles. Since particle formation and therefore the properties of the final latex will depend on the degree of grafting, it is important to quantify and to characterize the grafted PVA. In this work, the quantitative separation and characterization of the grafted water-insoluble PVA was carried out by a two-step selective solubilization of the PVAc latex, first with acetonitrile to separate PVAc homopolymer, followed by water to separate the water-soluble PVA from the remaining acetonitrile-insoluble material. After the separation, the water-soluble and water-insoluble PVA were characterized by Fourier Transform Infrared (FTIR) spectroscopy and 1H and 13C nuclear magnetic resonance (NMR) analyses, from which the details of the PVA-graft-PVAc structure were obtained. © 1996 John Wiley & Sons, Inc.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Symmetric branching model for the kinetics of mycelial growth (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1-10 
    Details
    ISSN: 0006-3592
    Keywords: mycelial kinetics ; symmetric branching tree ; microscopic parameters ; macroscopic parameters ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model, linking microscopic to macroscopic parameters of the kinetics of mycelial growth is presented. The model consists of two parts: (a) a microscopic description, based on the assumption that growth of a mycelium can be represented approximately by the growth of a symmetric binary tree, where the branching level (microscopic state variable) is logarithmically related to the number of tips and segments; and (b) a macroscopic description which makes use of the microscopic description in order to define the parameters related to the evolution of biomass (macroscopic state variable) as a function of time. The latter uses a distribution of arrested tips in a population of mycelia, in order to estimate the fraction of non-growing biomass in terms of a power law function with coefficient, n, of the biomass concentration. The microscopic description explains the fact that the germ tube specific growth rate of Aspergillus nidulans measured in a growth chamber, is about the double the specific growth rate of this organism, when measured in shake flasks. It predicts that the length of the hyphal growth unit of the mycelium of Geotrichum candidum would be approximately the double the germ tube length measured at the time just before the first branching event. It also allows the derivation of useful expressions for predicting macroscopic parameters, such as the maximal specific growth rate, the initial amount of biomass, and the amount of biomass before the branching process starts. Those estimates are done in terms of microscopic quantities, i.e., the amount of germinated spores, the diameters of the spores and hyphae, the average rate of tip extension, and the average internodal segment length. Estimation of coefficient n by fitting the macroscopic description to a growth curve of A. niger gives an indication on the degree of skewness of the distribution of arrested mycelia. Estimated macroscopic parameters are in relative good agreement with measured average segment length. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420102
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  • 3
    Electronic Resource
    Electronic Resource
    Dilute acid hydrolysis of wheat straw hemicellulose at moderate temperature: A simplified kinetic model (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 288-293 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat straw has been hydrolized with sulfuric acid at 34 and 90°C. The treatment at 90°C yields complete solubilization of hemicellulose to xylose and arabinose without significant amounts of furfural. The influence of acid concentration was studied and the kinetics of the acid-catalyzed hydrolysis has been modeled suggesting a two-consecutive reactions mechanism. This model is useful to explain the different behavior of the concentration of the two main sugars produced. The enhanced cellulose accessibility to enzymatic attack is also reported.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260280219
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  • 4
    Electronic Resource
    Electronic Resource
    Heat transfer simulation in solid substrate fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 802-808 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model was developed and tested to simulate the generation and transfer of heat in solid substrate fermentation (SSF). The experimental studies were realized in a 1-L static bioreactor packed with cassava wet meal and inoculated with Aspergillus niger. A simplified pseudohomogeneous monodimensional dynamic model was used for the energy balance. Kinetic equations taking into account biomass formation (logistic), sugar consumption (with maintenance), and carbon dioxide formation were used. Model verification was achieved by comparison of calculated and experimental temperatures. Heat transfer was evaluated by the estimation of Biot and Peclet heat dimensionless numbers 5-10 and 2550-2750, respectively. It was shown that conduction through the fermentation fixed bed was the main heat transfer resistance. This model intends to reach a better understanding of transport phenomena in SSF, a fact which could be used to evaluate various alternatives for temperature control of SSF, i.e., changing air flow rates and increasing water content. Dimensionless numbers could be used as scale-up criteria of large fermentors, since in those ratios are described the operating conditions, geometry, and size of the bioreactor. It could lead to improved solid reactor systems. The model can be used as a basis for automatic control of SSF for the production of valuable metabolites in static fermentors.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350808
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  • 5
    Electronic Resource
    Electronic Resource
    An approach in mathematical modeling of an upflow packed-bed reactor for enzymatic hydrolysis of wheat straw (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 242-251 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The behavior of a packed-bed reactor for enzymatic hydrolysis of pretreated wheat straw has been described by means of a mathematical model. The flow pattern has been evaluated by residence time distribution experiments. Small deviations from ideal plug flow behavior were found using the dispersion model. The kinetic model proposed for enzymatic hydrolysis of cellulosic fraction of pretreated wheat straw has been derived from batch experimental data. Variations of enzyme concentration throughout the straw bed have been approximately described using a ramp variation of adsorbed enzyme. The final explains qualitatively the experimental results.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340213
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  • 6
    Electronic Resource
    Electronic Resource
    Sauvagine-like and corticotropin-releasing factor-like immunoreactivity in the brain of the bullfrog (Rana catesbeiana) (1988)
    Springer
    Cell & tissue research 253 (1988), S. 29-37 
    Details
    ISSN: 1432-0878
    Keywords: Sauvagine ; Corticotropin-releasing factor ; Hypothalamus ; Immunohistochemistry ; Anterior preoptic area ; Median eminence ; Pars nervosa ; Pars intermedia, of pituitary ; (Anura) Rana catesbeiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical methods were used to investigate the occurrence and distribution of sauvagine, corticotropin-releasing factor-, or urotensin I-like immunoreactivities (SVG-ir, CRF-ir, UI-ir, respectively) in the bullfrog (Rana catesbeiana) brain, using specific antisera raised against non-conjugated SVG, ovine CRF, rat/human CRF, and UI. In the hypothalamus, SVG-ir was found in the magnocellular perikarya, in the dorsal and ventral regions of the preoptic nucleus, and in the hypothalamo-hypophyseal projections to the external zone as well as the internal zone of the median eminence, to pars nervosa, and in fibres running from the pars nervosa to the pars intermedia of the pituitary. In contrast, CRF-ir was found only in parvocellular perikarya, mainly localized in the rostro-ventral part of the preoptic nucleus, with fine processes protruding through the ependyma of the third ventricle, fibre projections terminating in the anterior preoptic area and in the neuropil of the periventricular gray, and a caudal projection to the external zone of the median eminence. No CRF-ir staining was seen in the pars nervosa and pars intermedia. The use of UI-specific antisera failed to give a positive response in the frog brain. It is concluded that, in the frog brain, two anatomically different CRF-like (or SVG-like) systems co-exist, comparable to the reported co-existence of UI-ir and CRF-ir neuronal systems in fish brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221736
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  • 7
    Electronic Resource
    Electronic Resource
    N, N-Dimethylamido-trithiophosphorsäure-anhydridProfessor Rolf Appel zum 60. Geburtstage am 25. Februar 1981 gewidmet (1981)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 473 (1981), S. 51-58 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: N,N-dimethylamido trithiophosphorus acid anhydrideThe reaction between tetraphosphorustrisulfide and bis(dimethylamino)sulfane yields the title compound, which is obtained as four- (I) and six-membered (II) ring molecules. The result of an X-ray analysis of a crystal of I is reported and discussed. Reactions of the title compound with ammonia, dimethylamine, bis(dimethylamino)sulfane, and tris-n-butylphosphane are described.
    Notes: Bei der Reaktion zwischen Tetraphosphortrisulfid und Bis(dimethylamino)-sulfan entsteht die Titelverbindung, die in Form vier- (I) und sechsgliedriger (II) ringförmiger Moleküle anfällt. Das Ergebnis der Röntgenstrukturanalyse eines Kristalls von I wird mitgeteilt und diskutiert. Die Reaktionen der Titelverbindung mit Ammoniak, Dimethylamin, Bis(dimethylamino)-sulfan und Tris-n-butylphosphan sind beschrieben.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19814730206
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  • 8
    Electronic Resource
    Electronic Resource
    Über die Spaltung von P—S—P-Brücken mit Bis(dimethylamino)sulfanFrau Professor Margot Becke-Goehring zum 60. Geburtstage gewidmet (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 406 (1974), S. 161-166 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Cleavage of P—S—P Bridges by Bis(dimethylamino)sulfaneThe reactions of perthio diphenylphosphinic anhydride and perthio phenylphosphonic anhydride with bis(dimethylamino)sulfane are investigated. Reaction products I and V were further reacted with tris(dimethylamino) phosphine and dimethylamine.
    Notes: Die Reaktionen von Perthio-diphenylphosphinsäureanhydrid und Perthio-phenylphosphonsäureanhydrid mit Bis(dimethylamino)sulfan werden untersucht. Die Reaktionsprodukte I und V wurden weiter mit Tris(dimethylamino)phosphin und Dimethylamin umgesetzt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744060206
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  • 9
    Electronic Resource
    Electronic Resource
    Sulfenamides as ligands in transition metal chemistry Pentacarbonyl(Sulfenamide)Chromium(0) ComplexesProfessor Ekkehard Fluck zum 60. Geburtstag am 27. Februar 1991 gewidmet (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 592 (1991), S. 7-16 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sulfenamide als Liganden in der Übergangsmetall-Chemie. Pentacarbonyl(Sulfenamid)-Chrom(0)-KomplexeDie Komplexe Cr(CO)5(R′SNR2) [R′ = CH3; NR2 = N(CH3)2, N(C4H8)O; R′ = C6H5; NR2 = N(CH3)2, N(C4H4)O, N(CH2—C6H5)2, N(C6H11)2] werden durch Reaktionen der Sulfenamide mit Cr(CO)5 · THF hergestellt und mittels analytischer und spektrometrischer Methoden charakterisiert. Die IR-, 1H-NMR-, UV-VIS- bzw. Massenspektra deuten auf eine Koordination via Schwefelatom hin. Die aus IR- und UV-VIS-Daten erhaltenen π-Akzeptoreigenschaften der Sulfenamide in den Komplexen werden mit denen anderer divalenter Schwefel-Verbindungen verglichen.
    Notes: The complexes Cr(CO)5(R′SNR2) [R′ = CH3; NR2 = N(CH3)2, N(C4H8)O. R′ = C6H5; NR2 = N(CH3)2, N(C4H4)O, N(CH2—C6H5)2, N(C6H11)2] have been prepared by reaction of the sulfenamides with Cr(CO)5 · THF and characterized by analytical and spectroscopic methods. The IR, 1H-NMR, UV-VIS, and mass spectra of the complexes support the coordination of the sulfenamide via the sulfur atom. π-acceptor abilities of sulfenamides in the prepared coordination compounds, determined from IR and UV-VIS data, were compared with those of other divalent sulfur conpounds.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915920102
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  • 10
    Electronic Resource
    Electronic Resource
    Enzymatic synthesis of a CCK-8 tripeptide fragment in organic media (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 700-708 
    Details
    ISSN: 0006-3592
    Keywords: α-chymotrypsin ; organic media ; tripeptide synthesis ; CCK-8 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The enzymatic synthesis of the tripeptide derivative Z-Gly-Trp-Met-OEt is reported. This tripeptide is a fragment of the cholecystokinin C-terminal octapeptide CCK-8. Studies on the α-chymotrypsin catalyzed coupling reaction between Z-Gly-Trp-R1 and Met-R2 have focused on low water content media, using deposited enzyme on inert supports such as Celite and polyamide. The effect of additives (polar organic solvents), the acyl-donor ester structure, the C-α protecting group of the nucleophile, enzyme loading, and substrate concentration were tested. The best reaction medium found was acetonitrile containing buffer (0.5%, v/v) and triethylamine (0.5%, v/v) using the enzyme deposited on Celite as catalyst (8 mg of α-chymotrypsin/g of Celite). A reaction yield of 81% was obtained with Z-Gly-Trp-OCam as acyl donor, at an initial concentration of 80 mM. The tripeptide synthesis was scaled up to the production of 2 g of pure tripeptide with an overall yield of 71%, including reaction and purification steps. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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