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  • Polymer and Materials Science  (3)
  • 11.55.Ds Exact S matrices  (1)
  • 1
    Electronic Resource
    Electronic Resource
    On kaonic deuterium. Quantum field-theoretic and relativistic covariant approach (2005)
    Springer
    The European physical journal 23 (2005), S. 79-111 
    Details
    ISSN: 1434-601X
    Keywords: 11.10.Ef Lagrangian and Hamiltonian approach ; 11.55.Ds Exact S matrices ; 13.75.Gx Pion-baryon interactions ; 36.10.-k Exotic atoms and molecules (containing mesons, muons, and other unusual particles)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. We study kaonic deuterium, the bound K-d state AK d. Within a quantum field-theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K-d scattering near threshold is defined by the resonances Λ(1405), Σ(1750) and a smooth elastic background, and the inelastic channels K-d → NY and K-d → NYπ, where Y = Σ±,Σ{0} and Λ{0}, where the final-state interactions play an important role. The Ericson-Weise formula for the S-wave scattering length of K-d scattering is derived. The total width of the energy level of the ground state of kaonic deuterium is estimated using the theoretical predictions of the partial widths of the two-body decays AKd → NY and experimental data on the rates of the NY pair production in the reactions K-d → NY. We obtain Γ{1s} = (630±100)eV. For the shift of the energy level of the ground state of kaonic deuterium we predict ε{1s} = (325±60)eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epja/i2004-10055-3
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  • 2
    Electronic Resource
    Electronic Resource
    Crystallinity and lateral crystallite size of different UHMW PE materials (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 863-866 
    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: Nascent high-molecular-weight (UHMW) polyethylene (PE) samples of different origins show a rather high crystallinity of about 70-75% and contain both a major portion of orthorhombic extended chain crystallites and a minor portion of triclinic crystallites. The triclinic content is greater the higher the molecular weight of the sample and the higher the activity of the used catalyser. A melting / recooling treatment results in a reduction of crystallinity by about 15-25% and disappearance of the triclinic phase. Further, an irreversible conversion of nascent orthorhombic extended chain crystallites to orthorhombic folded chain crystallites of increased lateral dimensions and crystalline perfections takes place during the melting / recooling treatment. The results are compared to those obtained for lower-molecular-weight PE samples and for high-strength / modulus PE fibers of different origins.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420332
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  • 3
    Electronic Resource
    Electronic Resource
    High-active Ziegler-Natta catalysts on polymeric supports for the manufacture of injection moulding polyethylene (1990)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 601-607 
    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: Die Immobilisierung von Ti-Mg-Ziegler-Natta-Katalysatoren auf polymeren Trägern aus linearem und vernetztem Polystyren wird beschrieben. Die Katalysatoren werden zur Homopolymerisation von Ethylene im Suspensionsproveß bei 0.84 MPa und 358 K eingesetzt. In Gegenwart von Wasserstoff als Molmassenregler wird Spritzgußpolyethylen in hoher Ausbeute erhalten. Der Einfluß verschiedener Trägerparameter auf katalytische Aktivität, Schmelzindex und Schüttdichte des Polymerisats wird untersucht.
    Notes: Polymeric supports on the base of linear and crosslinked polystyrenes have been used in this work for the immobilization of Ti-Mg Ziegler-Natta complexes. The resulting catalysts are tested in the homopolymerization of ethylene in a suspension process at 358 K and a total pressure of 0.84 MPa. By use of hydrogen for molecular weight control, injection moulding polyethylene in good yield is obtained. Influences of support parameters on a catalytic activity, melt flow index, and bulk density are studied.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1990.010411203
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  • 4
    Electronic Resource
    Electronic Resource
    Ziegler-Natta polymerization of ethylene with Ti-Mg catalysts anchored on polymeric supports (1993)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 44 (1993), S. 156-162 
    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: Unter besonderer Berücksichtigung des Spacereffektes wird die Immobilisierung von Ti-Mg-ZIEGLER-NATTA-Katalysatoren mittels polymerer Grignardverbindungen beschrieben. In Gegenwart von Wasserstoff als Molmassenregler werden die Katalysatoren zur Homopolymerisation von Ethylen bei 85°C und 6 bar eingesetzt. Die Katalysatoraktivität ist in allen Fällen um ein Mehrfaches höher, wenn eine MgCl2-Phase im Verlauf der Katalysatorsynthese auf der Trägeroberfläche ausgebildet wird. Die Aussage wird durch REM- und TEM-Aufnahmen belegt.
    Notes: The immobilization of Ti-Mg catalysts via polymeric Grignards on crosslinked polystyrenes has been achieved in the presence of methylene spacers of varying length. The resulting catalysts are tested in the homopolymerization of ethylene in a suspension process at 85°C and a total pressure of 6 bar. Hydrogen has been used as molecular weight controlling agent. The polymerization activity of the catalysts is significantly enhanced when a MgCl2 phase is generated in the course of catalyst preparation. The results are supported by SEM and TEM techniques.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1993.010440308
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