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  • Chemistry  (321)
  • Cell & Developmental Biology  (24)
  • Humans
  • Wiley-Blackwell  (345)
  • 1980-1984
  • 1975-1979  (345)
  • 1970-1974
  • 1940-1944
  • 1977  (345)
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  • Wiley-Blackwell  (345)
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  • 1980-1984
  • 1975-1979  (345)
  • 1970-1974
  • 1940-1944
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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 489-502 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Physical and in vivo (burned rat model) evaluations as wound coverings were performed for 1) a freeze-dried collagen/poly (∊-caprolactone) (PCL) film laminate, 2) a freeze-dried PCL “foam”/PCL film laminate, and 3) a heat-dried collagen/PCL film laminate. Porcine skin and cadaver skin were also evalulated in vivo for the purpose of comparison. Water-vapor transmission rates and Young's moduli were measured. The degrees of adherence of the coverings to the wound were measured. Grafts which became significantly adherent (〉150 dyne/cm2) to the wound within 1 day were most successful in promoting the formation of a viable tissue bed which appeared ready to accept further grafting. The force required to remove the PCL foam laminate from a full-thickness excision wound was found to increase from 170 dyne/cm2 on the first day postgraft to 1500 dyne/cm2 by the tenth day. The force required to remove freeze-dried collagen laminate remained constant at 200 dyne/cm2 over the 10 day test period. For the heat-dried collagen laminate, a force of only 50 dyne/cm2 was required on day 1, increasing to 200 dyne/cm2 on day 6. Insensible water-loss rates of animals grafted with the laminates were found to be similar to those from animals with human cadaver skin grafts and less than that from animals with porcine skin grafts. When moistened, the laminates prepared using the freeze-dried materials were flexible and somewhat transparent permitting observation of the wound.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 15 (1977), S. 399-405 
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1015-1031 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An electron microscope study of collagen fibrils from fixed tail tendons of rats has revealed that from some time shortly after birth until maturity, the fibril diameters have a bimodal distribution. The “two” types of fibril are indistinguishable in both transverse and longitudinal section. Unfixed specimens of eight-week-old-tail tendon showed a similar bimodal distribution of diameters though the positions of the peak values compared to fixed specimens of an eight-week-old-tail tendon were shifted upwards by about 30%. It has also been shown quantitatively that the polar collagen fibrils are directed randomly “up” and “down” with respect to their neighbors. Whilst it has been suggested by others that anastomosis is a feature of collagen structure, the results presented here do not support this hypothesis. Fibrillar units ∼ 140 Å in diameter have been observed and the possibilities that these are elastic fibers or the breakdown products of collagen fibrils have been considered.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 2487-2489 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2963-2978 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: From a comparison of the photo-and γ-irradiation-initiated oxidations of monofilaments and films, polypropylene oxidation rates and product ratios were found to be independent of sample morphology and orientation. Filament sensitivity to photo-oxidation was, however, drastically affected by extrusion and draw conditions, photosensitivity increasing with increasing draw speed and decreasing draw temperature. Draw effects were minimized by the exclusion of oxygen, indicating that free radicals produced by backbone cleavage during draw react with oxygen to give chromophoric oxidation products. The most important product detectable after drawing was probably the polypropylene hydroperoxide. A phenolic antioxidant reduced hydroperoxide formation, although sufficient hydroperoxide was still produced to accelerate photodegradation as compared with a similarly stabilized undrawn filament. Melt oxidation within the extruder was concluded to be much more important than thermal oxidation of the extruded filament as it cooled on the spinline.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 3099-3109 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of six Hytrel/PVC blends were prepared by solution blending Hytrel in methylene chloride and PVC in tetrahydrofuran. The samples were subsequently prepared in sheet form by hot pressing at 170°C. Physical and mechanical properties of the homopolymers and the blends were investigated. The copolyester homopolymer is a partly crystalline elastomeric material. The level of crystallinity was measured by x-ray diffraction and the sensitivity of this level to heat treatments and quenching determined by DSC. A Morgan pulse propagation meter was used to measure sonic velocity and, indirectly, acoustic impedance of the blends. Dynamic mechanical studies indicated that blends containing 25%-50% by weight of Hytrel were completely compatible in the sense that a single glass transition was observed; but as the Hytrel level was increased to 60% and 65%, a shoulder became apparent on the low-temperature side of the glass transition peak. At 80% Hytrel, two peaks were observed, indicating incompatibility. The glass transition temperatures of these blends were found to decrease linearly with added Hytrel.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 853-865 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method to estimate the oxygen transfer coefficient (KLa) from the experimental dynamic response data is presented. Employing a linear model which allows for gas phase, diffusion film, and oxygen electrode dynamics, the first moment of the response curve is simply related to the sum of the model parameters. Two separate experiments are used to characterize the measurement dynamics and to measure the unknown KLa parameter. The simple calculation procedure involves only measuring the area above the response curves.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 319-326 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dual enzyme sequential reactions that decompose arginine to ammonia were investigated experimentally to determine appropriate rate equations and to test predictions of optimal distribution of the two enzymes (arginase and urease) immobilized in a packed-bed reactor.The kinetics of this system were experimentally found to be of the kind that calls for a bang-band control with a well-defined switching point between the two immobilized enzyme catalysts. At low values of reactor residence time, the optimum switching point is shown to approach a limiting position which depends on the kinetic order of the second reaction. In the higher ranges of residence time, the switching point moves into the latter half of the reactor, but exceptions to this generalization are found when Michaelis-Menten kinetics are applicable to both reactions. For the special circumstance where the two reactions are of zero and first order, respectively, the optimal distribution of the two catalysts is independent of the first rate constant. The experimental results are, in general, consistent with these expectations, and secondary deviations are discussed. A suboptimal policy alternative is also treated analytically and tested by experiment.
    Additional Material: 14 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 679-685 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of pyrite oxidation in aqueous ferric chloride was determined for two distinct solid particle systems: industrial grade pyrite and coal particles containing pyrite. The oxidation rate for the pyrite particle system was found to increase significantly with increasing temperature (40° to 100°C), ferric chloride concentration (0.1 and 1.0 M), and pyrite loading (2 to 20 g/l); the rate decreased with increasing particle size (-325 to 140 mesh). Agitation did not have a significant effect, and a kinetic model was developed and fit to the experimental data.For the coal particle system used in this study, the most important variable was particle size. The oxidation rate of pyrite in coal smaller than 325 mesh was much greater than in larger coal particles. The effect of temperature (80° to 100°C) on the oxidation of pyrite in coal was not significant, nor was the effect of pretreatment with 0.1N hydrochloric acid. Approximately half of the detected ferric iron reduction was attributable to pyrite oxidation; the balance arises from other coal reactions.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 57 (1977), S. 111-122 
    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: By using pure samples of compounds of the homologous series of epoxide resins consisting of bisphenol A and epichlorhydrin (obtained by preparative gel chromatography) calibration curves have been established for the quantitative determination of the homologs in the gelchromatograms of the epoxide resins.From well resolved gelchromatograms of resins formed by various molar ratios of the starting materials also the molecular weight distributions have been determined.Epoxide resins with very small amounts of by-products show molecular weight distributions according to Flory's theory. Epoxide resins with larger amounts of not completely epoxidized products on the other hand show deviations from the theoretical distributions.
    Notes: Mit Hilfe der durch präparative Gelchromatographie erhaltenen reinen Glieder der homologen Reihe der Epoxidharze aus Bisphenol A und Epichlorhydrin wurden Eichkurven für die quantitative Bestimmung der einzelnen Homologen in den Gelchromatogrammen der Harze aufgestellt.Aus den erhaltenen, gut aufgelösten Gelchromatogrammen von Epoxidharzen, die mit verschiedenen Molverhältnissen der Ausgangsprodukte gebildet werden, wurden deren Molekulargewichtsverteilungen ermittelt.Bei Epoxidharzen mit sehr wenig Nebenprodukten stimmen die experimentell gefundenen Molekulargewichtsverteilungen gut mit den nach Flory theoretisch berechneten überein. Dagegen zeigen Epoxidharze mit einem höheren Gehalt an nicht vollständig epoxidierten Produkten erwartungsgemäß größere Abweichungen von den theoretischen Werten.
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