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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 3 (1893), S. 415-420 
    ISSN: 0863-1778
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1817-1827 
    ISSN: 0887-624X
    Keywords: polymer blends ; hydrogen bonding ; miscibility ; phase behavior ; equilibrium constants ; hexafluoroisopropanol groups ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dimensionless equilibrium constants describing the self-association of the hexafluoro-2-alkyl-2-propanol group have been determined from infrared spectroscopic data. Corresponding values of these equilibrium constants for a fully modified polyisoprene containing the hexafluoroisopropanol group (PHFPI) were calculated by taking into account differences in the molar volume of the model and the specific repeat unit of the polymer. Equilibrium constants describing the inter-association of PHFPI with methacrylate, acrylate, and acetoxy type carbonyl groups were obtained from spectroscopic studies of miscible PHFPI blends with poly(n-butyl methacrylate), poly(methyl acrylate), and an ethylene-co-vinyl acetate copolymer containing 70 wt% vinyl acetate. The set of equilibrium constant values were then used to calculate theoretical miscibility windows for the complete range of PHFPI blends with poly(n-alkyl methacrylate)s and four copolymers, ethylene-co-methyl methacrylate, styrene-co-methyl acrylate, ethylene-co-methyl acrylate, and ethylene-co-vinyl acetate. Experimental infrared studies confirm the general validity of the predicted miscibility windows. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1189-1193 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2039-2056 
    ISSN: 0887-624X
    Keywords: blends ; hydrogen bonding ; miscibility ; phase behavior ; equilibrium constants ; fluoropolymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical calculations of miscibility windows for binary polymer blends in which one component is an essentially alternating copolymer of tetrafluoroethylene and vinyl alcohol (FVOH) are reported. FVOH has an inherently low solubility parameter [≈ 6.2 (cal. cm-3)0.5] that is outside the range commonly encountered in miscible polymer blends and thus represents a stringent test of the predictive capabilities of an association model we have used in previous work. The application of this model requires that we determine dimensionless equilibrium constants describing the self-association of a model compound 3,4-pentafluorobutan-2-ol (PFB) at 25°C from infrared spectroscopic data. Analogous equilibrium constants for FVOH were scaled from those of PFB by taking into account differences in the molar volume of the model and the specific repeat of the copolymer (see M. M. Coleman, J. F. Graf, and P. C. Painter: Specific Interactions and the Miscibility of Polymer Blends, Technomic, Lancaster, PA, 1991). Equilibrium constants describing the inter-association of FVOH with ester type carbonyl groups were obtained from spectroscopic studies of miscible blends with poly(ethyl methacrylate). These equilibrium constant values were then used to calculate theoretical miscibility windows for the complete range of blends of FVOH with polymethacrylates, ethylene-co-methyl acrylate, styrene-co-methyl acrylate, and ethylene-co-vinyl acetate copolymers. Experimental results performed in our laboratories confirm the general validity of the predicted miscibility windows. © 1993 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1631-1632 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1635-1649 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When, in a poly-α-olefin, the probability that a given placement be isotactic depends upon the tacticity of only a finite number of immediate predecessors, the resulting diastereosequence distribution obeys the theory of Markoff chains. When this is not the case, one says that the resulting diastereosequence distribution is non-Markoffian. A special case of a Markoffian distribution is given by a simple Markof chain in which the tacticity of a given placement is assumed to be affected by only the tacticity of the immediately preceding placement. Another special case is, of course, the Bernoulli trial distribution in which the probability that a given placement be isotactic is independent of the tacticity of all other placements. A high resolution NMR spectrum can sometimes yield a quantitative determination of the concentrations of isotactic and syndiotactic placements and the concentrations of the three types of possible adjacent pairs of such placements (i.e., isotactic, syndiotactic, and heterotactic pairs). When this is the case, the spectrum can be used to determine whether or not a given diastereosequence distribution is Bernoullian. However, because the longest diastereosequences whose concentration can be measured by NMR spectroscopy involve only two placements, an NMR spectrum cannot check whether a given non-Bernoullian distribution be simple Markoffian or Markoffian in general. In fact, non-Markoffian distributions are compatible with existing NMR spectra on polymers prepared by anionic polymerizations. In this paper we work within the framework of Kac's theory of stationary statistical processes and point out some general results which are valid for both Markoffian and non-Markoffian processes. The results are applied to NMR spectroscopy and it is pointed out which calculations used to check the self-consistency of NMR data and to obtain the mean length of closed diastereosequences are valid for both Markoffian and non-Markoffian distributions.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1241-1249 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acoustic resonance densitometry (ARD) is reported as a method suitable not only for precise investigations into changes of specific gravity in bioreactor media but also as a technique able to provide an accurate wide range and direct determination of cellular mass in fermentation processes. It is further shown that this method can replace present optical procedures, minimizing dilution errors and operator involvement and is suitable for development as an on-line biomass monitoring system.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 1773-1788 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcohol dehydrogenase has been covalently attached to the surfaces of nylon stir rods. Several rod types have been evaluated in terms of their mixing efficiency and enzyme loading. Fluorometric monitoring of the rate of conversion of NAD to NADH serves as a measure of the reaction rate under varying conditions. The rate of reaction of the enzyme stir rods has been evaluated in terms of RPM, buffer concentration, NAD reagent concentration, and pH. The rate of reaction is seen to reach a plateau at higher stir rates, indicating a lack of diffusional hindrances. The reaction rate also begins to level off at phosphate buffer concentration of 0.1M to 0.15M. Saturating conditions are reached at an NAD concentration of 2.5mM. The optimum pH is found to be 9.0. The Stability of the covalent bond between the enzyme and the nylon has been assessed by comparing the bond strength to the energies of various disruptive forces to which the enzyme is exposed. Centrifugal, drag, and shear forces are shown to be insufficient to cause rupture of the bond. The stability to the immobilized enzyme preparation has been investigated under varying conditions of immobilization and use. No effect on activity loss was found for rotation rate or for continuous versus intermittent use. It was found that enhanced stability occurred for hydrolytic cleavage of the nylon, using nitric acid, as compared to nonhydrolytic cleavage. Hydrolytic cleavage also led to some degree of adsorption of the enzyme to the surface of the nylon. Thus, the possibility of increased stability to multipoint attachment of the enzyme is discussed. Possible cause of activity loss are discussed, as well as the extension of the enzyme stir rod to use in scale model reactor studies.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 1379-1384 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acoustic resonance densitometry (ARD) provides a highly reproducible and stable method for on-line measurement of culture biomass density. The technique provides a direct determination of changes in relative density of culture medium and cell mass. At cell concentrations higher than 106 cells mL-1this method can replace cell counts and provide a continuous measure of total cell mass. In cultures of hybridomas or U937 human lymphoma cells, the ARD value correlates well with cell number except when the average cell size changes during culture. It is argued that cell mass determined by ARD rather than cell number should be used as the basis for measurements of specific biological activity.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 994-1002 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Interpenetrating polymer networks (IPNs) of poly(ethylene oxide) (PEO) and a polyether substituted polysiloxane were synthesized containing variations of PEO content (35 and 65% dry network weight) and PEO systematically varied from low to high molecular weight (2,000, 8,000, and 20,000). Biocompatibility was assessed by measureing 111In platelet deposition in a baboon femoral ex vivo shunt. Mass transfer analysis revealed that platelet transport to PEO/polysiloxane surfaces was kinetically limited and correlated with both PEO content and molecular weight. Differences in material performance were noted particularly after the initial 30 min blood contact period. In mid and high PEO molecular weight networks (8,000 and 20,000), reduced platelet deposition was noted with increased PEO content. In materials of high PEO content (65%), mid and high PEO molecular weight samples had significantly lower levels of platelet adsorption than PDMS (60 min; p〈 0.05) or networks of low PEO molecular weight, coded 2K-65 (30 and 60 min; p 〈 0.05). The lowest level of platelet deposition was noted on 20K-65 networks, less than one platelet per 1,000 μm2.
    Additional Material: 9 Ill.
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