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  • Polymer and Materials Science  (18)
  • 81G20  (2)
  • 83A05  (2)
  • Composition  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Dilute solution properties of polyurethane (1991)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 597-599 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mittels Kleinwinkel-Laserlichtsreuung und viskosimetrichen Messungen wurden verdünnte Lösungen von Polyurethanfraktionen untersucht. Das Polymer wurde aus Butandiol und Hexamethylendiisocyanat hergestellt. Die Grenzviskositäten wurden über die MARK-HOUWINK-SAKURADA-Gleichung zu den Molekülmassen korreliert. Die Werte der Konstanten Km und a wurden ermittelt. Trotz des niedrigen Brechungsinkrementes von Polyurethan in Benzen konnten Molekülmassen bis herab zu 4300 gemessen werden.
    Notes: Low angle laser light scattering and viscosity studies were made on dilute solution of fractions of polyurethane prepared from butandiol and hexamethylene diisocyanate. The intrinsic viscosities were correlated to molecular weights by the MARK-HOUWINK-SAKURADA equation. The values of the constants Km and a have been determined. In spite of the low refractive index increment of polyurethane in benzene, molecular weights as low as 4300 could be measured.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1991.010421114
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  • 2
    Electronic Resource
    Electronic Resource
    Extended harmonic analysis of phase space representations for the Galilei group (1986)
    Springer
    Acta applicandae mathematicae 6 (1986), S. 19-45 
    Details
    ISSN: 1572-9036
    Keywords: 20C35 ; 81G20 ; Harmonic analysis ; stochastic quantum mechanics ; systems of covariance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The spectral resolution of phase space representations of the Galilei group is achieved by deriving all possible decompositions into irreducible representations corresponding to reproducing kernel Hilbert spaces. Spectral syntheses in terms of eigenfunction expansions, as well as in terms of continuous resolutions of the identity, are achieved. For the latter, the existence, uniqueness and other basic properties of resolution generators are established. This is shown to lead to systems of covariance related to measurements of stochastic phase space values performed with extended quantum test particles, whose proper wavefunctions are the aforementioned resolution generators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046933
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  • 3
    Electronic Resource
    Electronic Resource
    Harmonic analysis and systems of covariance for phase space representation of the poincaré group (1986)
    Springer
    Acta applicandae mathematicae 6 (1986), S. 47-62 
    Details
    ISSN: 1572-9036
    Keywords: 81M05 ; 83A05 ; Harmonic analysis ; POV measures ; relativistic stochastic phase space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Continuing some earlier work on the Galilei group, the spectral resolution of phase space representations of the Poincaré group is achieved by deriving all possible decompositions into irreducible representations corresponding to reproducing, kernel Hilbert spaces. Systems of covariance related to quantum measurements performed with extended test particles are analyzed, and questions of global unitarity discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046934
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  • 4
    Electronic Resource
    Electronic Resource
    Mathematical problems of stochastic quantum mechanics: Harmonic analysis on phase space and quantum geometry (1986)
    Springer
    Acta applicandae mathematicae 6 (1986), S. 1-18 
    Details
    ISSN: 1572-9036
    Keywords: 20C35 ; 81G20 ; 83A05 ; POV measures ; systems of covariance ; phase space representations of kinematical groups ; stochastic geometries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this paper we review the mathematical methods and problems that are specific to the programme of stochastic quantum mechanics and quantum spacetime. The physical origin of these problems is explained, and then the mathematical models are developed. Three notions emerge as central to the programme: positive operator-valued (POV) measures on a Hilbert space, reproducing kernel Hilbert spaces, and fibre bundle formulations of quantum geometries. A close connection between the first two notions is shown to exist, which provides a natural setting for introducing a fibration on the associated overcomplete family of vectors. The introduction of group covariance leads to an extended version of harmonic analysis on phase space. It also yields a theory of induced group representations, which extends the results of Mackey on imprimitivity systems for locally compact groups to the more general case of systems of covariance. Quantum geometries emerge as fibre bundles whose base spaces are manifolds of mean stochastic locations for quantum test particles (i.e., spacetime excitons) that display a phase space structure, and whose fibres and structure groups contain, respectively, the aforementioned overcomplete families of vectors and unitary group representations of phase space systems of covariance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046932
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  • 5
    Electronic Resource
    Electronic Resource
    An electron probe X-ray microanalytical study of bone mineral in osteogenesis imperfecta (1995)
    Springer
    Calcified tissue international 56 (1995), S. 118-122 
    Details
    ISSN: 1432-0827
    Keywords: Osteogenesis imperfecta ; Mineral ; Composition ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A semiquantitative electron probe X-ray microan-alytical (XRMA) technique, in conjunction with transmission electron microscopy, was used to compare the calcium to phosphorus (Ca/P) molar ratios in calcium phosphate standards of known composition, in normal bone and in bone from patients with osteogenesis imperfecta (OI). Using a modified routine processing and resin embedding schedule, the measured Ca/P molar ratio of calcium phosphates standards of known composition were found to correlate well with the Ca/P molar ratio based on their respective chemical formulae. This technique was then used to compare the Ca/P molar ratio in normal human bone and in OI bone. The Ca/P ratio values for normal bone (Ca/P=1.631) correlated well with those for chemically prepared hydroxyapatite (Ca/P=1.602), but in bone from OI patients, the Ca/P molar ratio was significantly lower (Ca/P=1.488). This study has shown that there is a lower Ca/P molar ratio in OI bone compared with normal, matched bone. This suggests that the mineral deviates from the carbanoapatite usually found in bone. Isomorphous substitutions in the carbanoapatite lattice could account for this although this study has neither proved nor disproved this. The altered bone mineral is an-other factor that could contribute to the increased fracture rate observed in OI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296342
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  • 6
    Electronic Resource
    Electronic Resource
    A Fourier transform infrared spectroscopic and solid-state NMR study of bone mineral in osteogenesis imperfecta (2000)
    Springer
    Journal of bone and mineral metabolism 18 (2000), S. 291-296 
    Details
    ISSN: 1435-5604
    Keywords: Key words Osteogenesis imperfecta ; Mineral ; Composition ; FTIR ; 31P-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fourier transform infrared spectroscopy and 31P solid-state nuclear magnetic resonance spectroscopy were used to determine if any structural or compositional differences in osteogenesis imperfecta (OI) bone mineral could be detected that might help to explain the bone fragility observed in this disease. A previous study by Cassella et al. used an electron probe X-ray microanalytical technique to compare the calcium to phosphorus (Ca/P) molar ratios in normal bone and bone from patients with OI. It was demonstrated that bone from OI patients had a lower Ca/P molar ratio. This study demonstrated that OI bone mineral had a general hydroxyapatite structure and that isomorphous substitutions in the carbanoapatite lattice could account for the low Ca/P molar ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010645
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  • 7
    Electronic Resource
    Electronic Resource
    Morphology of nylon 6 spherulites in bulk (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1195-1204 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method of obtaining good quality ultrathin sections from nylon 6 bulk samples has been developed by using a special embedding technique and cryo-ultramicrotomy. The morphologies of nylon 6 processed by compression and injection molding and of reaction injection molded nylon 6 were studied in ultrathin sections of bulk samples by means of transmission electron microscopy. It was established that the spherulites of nylon 6 in bulk are built up from long flat ribbonlike lamellae. The thickness of the lamellae is in the range 50-60 Å. The width varies from 150 to 600 Å and depends on the type of nylon 6 and the method of processing. The length of the lamellae is relatively large approaching spherulite radii, extending often from the point of their origin up to the spherulite borders. Three or four neighboring lamellae within spherulites usually show similar orientation of their flat faces and form domains which can easily be mistaken for fibrils in light microscopy or low resolution electron microscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880522
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  • 8
    Electronic Resource
    Electronic Resource
    Black crazes  -  white crazes? (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 431-439 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The origin of the curious “inverted contrast” often observed in transmission electron micrographs of crazes in rubber-toughened thermoplastics was determined by using scanning transmission electron microscopy with X-ray fluorescence analysis. The “black crazes” seen in the micrographs contain high concentrations of osmium metal which is introduced through OsO4 used to stain the rubber phase. Treatment of stained sections with a strong oxidizing agent (NaIO4) removes a sufficient amount of osmium to reveal the commonly observed tufty craze microstructure with the expected contrast of light crazes in a darker background.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021870222
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  • 9
    Electronic Resource
    Electronic Resource
    γ Radiolysis of cellulose acetate (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 2893-2897 
    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 major degradative process in γ-irradiated cellulose acetate is chain scission. For the dry powder the Gs value (number of scissions per 100 eV of energy absorbed) was found to be 7.1. The water-swollen material was found to degrade at the higher rate of Gs = 9.45. Additions of ethanol and methanol to the water brought about reductions in Gs, whereas dissolved nitrous oxide produced an increase in Gs. The useful life of cellulose acetate reverse osmosis membranes exposed to γ radiation was estimated by observations of the water permeation rate during irradiation. Membrane breakdown occurred at 15 Mrad in pure water, but the dose to breakdown was extended to 83 Mrad in the presence of 4% methanol.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231006
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  • 10
    Electronic Resource
    Electronic Resource
    The stability of poly(ether urethane)/polydimethylsiloxane interpenetrating polymer networks (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 733-740 
    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: Interpenetrating polymer networks (IPNs) are a special type of polymer blend consisting of two polymer networks synthesized and/or cross-linked independently within each other. One potential approach for the preparation of composite materials from polymers having desirable physical characteristics obtained by modifying their surfaces with physiologically acceptable polymers involves IPN technology. An IPN based on a poly(ether urethane) and polydimethylsiloxane has been synthesized and charaterized using optical microscopy, dynamic mechanical analysis, and scanning electron microscopy. The stability of poly(ether urethane)/polydimethylsiloxane composites were studied in hydroxyl radical aqueous solutions over 30 weeks. The data suggest that these composites have good potential for biomedical applications. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550509
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