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  • Polymer and Materials Science  (194)
  • Life and Medical Sciences  (141)
  • Wiley-Blackwell  (335)
  • 1980-1984  (335)
  • 1
    Electronic Resource
    Electronic Resource
    Polymers from renewable sources, 1. Diamines and diisocyanates containing difurylalkane moieties (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 697-707 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Furan-based diisocyanates and diamines were prepared unambiguously as potential monomers for polyurethane and polyamide production, starting from methyl furoate and furfurylamine, respectively. The syntheses were optimized and the product identity was confirmed by elemental analysis, IR and NMR spectroscopy, and also by preparation of derivatives which were similarly characterized.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850408
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  • 2
    Electronic Resource
    Electronic Resource
    Polymers from renewable sources, 2Part 1: cf.1. Kinetics and polyurethane formation from furan-based diisocynates (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 709-723 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Novel furan-based diisocyanates (2a - c) were reacted with 1-butanol and basic kinetic studies were made. The results were compared with those obtained from 4,4′-methylenediphenylene diisocyanate (1) under similar conditions. The kinetics of these model reactions were found to be complex even in the presence of added catalysts. The isocyanates 2 studied, were shown to behave as benzylic type compounds with reactivities intermediate between those of aryl and alkyl diisocyanates. Comparative studies were made on segmented copolyurethanes prepared from 1 and from a furfuryl diisocyanate 2a having structural similarity to 1. The diol components used in these studies were 1,4-butanediol and polytetrahydrofuran. The segmented co-polyurethanes prepared from the furfuryl diisocyanate can thus be derived from a single naturally occurring source material, namely furfuraldehyde. These polymers were shown by differential scanning calorimetry and dynamic mechanical analysis to possess properties comparable to analogous copolyurethanes derived from oil-based sources.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850409
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of fibrin film. II. Small-angle x-ray scattering (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 1833-1845 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of small-angle x-ray scattering have been made on bovine fibrin film, prepared by gentle compaction of coarse fibrin clots, containing 12-15% fibrin plasticized with either aqueous buffer or glycerol. Most of the experiments were made with water-plasticized films because of the better x-ray contrast. Both unligated and ligated (i.e., with α-α and λ-λ ligation by fibrinoligase, factor XIIIa) films were studied. Theoretical angular scattering profiles were calculated for a simplified model of the fibrin protofibril as a function of stretch ratio in uniaxial elongation based on an orientation distribution derived in the preceding paper. Measurements were made on unstretched films both with slit geometry and with pinhole geometry and two-dimensional position-sensitive detection. From the former, which had better resolution, the fundamental peak corresponded to a repeat spacing of 230 ± 5 Å, in agreement with early results of Stryer et al. [(1963) Nature 197, 793-794] and electron micrographs of stained fibrin, and with the half-staggered overlapping model of the protofibril. Measurements were made with pinhole geometry on film stretched up to a stretch ratio λ = 1.59 at different times after imposition of strain and after release and recovery. The changes in meridional and equatorial scattering profiles, including the more prominent appearance of a harmonic in the former, show the orientation of the protofibrils as previously deduced from birefringence and related quantitatively to stretch ratio. In addition, the original repeat spacing is gradually replaced by one of about 290 Å. The “internal” stretch ratio λx, averaging about 1.28, is independent of the macroscopic stretch ratio λ from 1.14 to 1.59. The change, which is more nearly complete for unligated film and is reversible on release and retraction of the stretched strips, is attributed to an internal transition in the fibrin monomer units, probably involving extension of either the helical connectors or the terminal nodules. The results of stress and birefringence relaxation reported in the preceding paper of this series are interpreted on this basis.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210911
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of the extent of cure on the modulus, glass transition, water absorptio, and density of an amine-cured epoxy (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 2831-2846 
    Details
    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: The modulus, density, glass transition temperature (Tg), and water absorption characteristics of an amine-cured resin [diglycidyl ether of bisphenol A (Epon 828)/diaminodiphenyl sulfone (DDS)] were studied as a function of extent of cure. The glass transition is a function of the extent of cure and reaches a maximum temperature, Tg∞, when it is completely cured; specimens with different extents of cure were formed by isothermal cure below Tg∞, for different times. After slowly cooling, the density at each extent of cure was obtained at room temperature. Moisture absorption was monitored gravimetrically at 25°C for 2 months at several humidity levels. The room temperature density and modulus decreased with increasing extent of conversion whereas the glass transition temperature and equilibrium water absorption increased. The equilibrium water absorption increased linearly with relative humidity, and the absorptivity increased linearly with specific volume. An interpretation of these anomalous results is made in terms of the nonequilibrium nature of the glassy state. The glass transition temperature increases as the extent of cure increases resulting in a material that is further from equilibrium at room temperature and therefore has more free volume and a greater propensity to absorb water.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280914
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  • 5
    Electronic Resource
    Electronic Resource
    Process for the formation of biaxially oriented films of poly(p-phenylene terephthalamide) from liquid crystalline solutions (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 2965-2985 
    Details
    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 new process for making equal biaxially oriented films from liquid crystalline solutions of poly(p-phenylene terephthalamide) (PPD-T) is described. The process involves extruding solutions of PPD-T/H2SO4 through an annular die and over an oil-coated mandrel into a coagulation bath. The films were studied using wide angle X-ray diffraction (WAXS) and scanning electron microscopy (SEM). Tensile stress-strain properties were obtained on samples cut at various directions in the plane of the film. Biaxially oriented films which possess equal properties in the various directions in the plane of the film were produced. Moduli of 2.3 × 109 Pa and tensile strengths of 9.6 × 107 Pa were obtained in the plane of the film. Films with unequal biaxial orientation were also produced. These tend to have higher modulus/tensile strength in the direction of major orientation, the machine direction (up to 8.3 × 109 Pa/2.5 × 108 Pa), but become brittle in the transverse direction.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270821
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusion of cyclic hydrocarbons in benzene-swollen, divinylbenzene-crosslinked polystyrene beads (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 3841-3849 
    Details
    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: Diffusion of cyclic hydrocarbons within benzene-swollen, polystyrene-divinylbenzene gel-type beads were studied at 25°C. Solute concentrations less than 6.3 × 10-2M and volume fractions of polymer less than 0.6 were used. Diffusion coefficients were calculated assuming Fick's law diffusion, and were found to depend upon the volume fraction of polymer. The dependence suggests that the swollen polymer network acts as a physical obstruction to diffusion. Studies indicated that the solute-solvent interactions affecting diffusion were the same in the solvent-swollen polymer as in the pure benzene solvent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271018
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  • 7
    Electronic Resource
    Electronic Resource
    Time-temperature-transformation (TTT) cure diagram: Modeling the cure behavior of thermosets (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 2567-2591 
    Details
    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: The times to gelation and to vitrification for the isothermal cure of an amine-cured epoxy (Epon 828/PACM-20) have been measured on macroscopic and molecular levels by dynamic mechanical spectrometry (torsional braid analysis and Rheometrics dynamic spectrometer), infrared spectroscopy, and gel fraction experiments. The relationships between the extents of conversion at gelation and at vitrification and the isothermal cure temperature form the basis of a theoretical model of the time-temperature-transformation (TTT) cure diagram, in which the times to gelation and to vitrification during isothermal cure versus temperature are predicted. The model demonstrates that the “S” shape of the vitrification curve depends on the reaction kinetics, as well as on the physical parameters of the system, i.e., the glass transition temperatures of the uncured resin (Tg0), the fully cured resin (Tg∞), and the gel (gelTg). The bulk viscosity of a reactive system prior to gelation and/or vitrification is also described.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280810
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of isolation and culture on prostaglandin synthesis by porcine aortic endothelial and smooth muscle cells (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 110 (1982), S. 9-16 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Freshly isolated neonatal porcine aortic tissue (smooth muscle with or without endothelium present) produced ∼ 30 ng/mg wet tissue of 6-oxo-prostaglandin F1α (the stable hydrolysis product from prostacyclin) and ∼ 15 ng/mg of prostaglandin E2, as measured by radioimmunoassay after 24 h incubation in culture medium. Primary cultures of porcine endothelial and smooth muscle cells (isolated by enzymic digestion of aortic tissue) exhibited the same pattern of prostaglandin production, but absolute values were greater than for fresh tissue, particularly in the case of endothelium. Subcultures of endothelium produced smaller amounts of prostaglandins, although the pattern remained similar. In contrast, subcultures of smooth muscle cells produced a greater total amount of prostaglandins than did primary cultures, and the main product was prostaglandin E2. Experiments with [14C] prostaglandin H2 or [14C]arachidonic acid confirmed that aortic tissue, cultured endothelium, and primary cultures of aortic smooth muscle cells synthesized prostacyclin, and demonstrated that subcultured smooth muscle cells enzymically isomerised prostaglandin H2H to prostaglandin E2. Kinetic studies showed that prostaglandin production by cultured vascular cells was transiently increased by subculture or changing the growth medium, and that production per cell declined with increasing cell density. The change in pattern of prostaglandin production during culture was shown to be due to a rapid decline in the rate of prostacyclin production (which apparently began immediarely after tissue isolation), together with a more gradual rise in prostaglandin E2 production. These results indicate that the amounts and ratios of prostaglandins produced by vascular endothelial and smooth muscle cells are geatly affected by the conditions used to isolate and culture the cells; vascular cells in vivo may similarly alter their pattern of prostaglandin production in response to local cahnges in their environment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041100103
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  • 9
    Electronic Resource
    Electronic Resource
    The human c-abl oncogene in the philadelphia translocation (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 179-191 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041210421
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  • 10
    Electronic Resource
    Electronic Resource
    Comparative effects of pulsed and continuous-wave 2.8-GHz microwaves on temporally defined behavior (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 3 (1982), S. 227-235 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; pulsed-wave ; continuous-wave ; operant behavior ; DRL schedule ; rats ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effects of pulsed-(PW) and continuous-wave (CW) 2.8-GHz microwaves were compared on the performance of rodents maintained by a temporally defined schedule of positive reinforcement. The schedule involved food-pellet reinforcement of behavior according to a differential-reinforcement-of-low-rate (DRL) contingency. The rats were independently exposed to PW and to CW fields at power densities ranging from 1 to 15 mW/cm2. Alterations of normal performance were more pronounced after a 30-minute exposure to the PW field than to the CW field. The rate of emission of appropriately timed responses declined after exposure to PW at 10 and 15 mW/cm2, whereas exposure at the same power levels to the CW field did not consistently affect the rate of responding. Change in performance associated with microwave exposure was not necessarily related to a general decline in responding: in some instances, increases in overall rates of responding were observed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250030207
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