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  • Gamma rays:bursts  (1)
  • Polymer and Materials Science  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 231 (1995), S. 271-276 
    ISSN: 1572-946X
    Keywords: Gamma rays:bursts ; Gamma rays:high energy ; Air showers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation (≥ 50 TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each burst are presented for seven GRBs located with zenith anglesθ 〈 20°. A 4.3σ excess over background was observed between 10 and 20 minutes following the onset of a GRB on 11 May 1991. The confidence level that this is due to a real effect and not a background fluctuation is 99.8%. If this effect is real then cosmological models are excluded for this burst because of absorption of UHE gamma rays by the intergalactic radiation fields.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 533-541 
    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 initial rates of ethylene polymerization initiated by 13 chelating tertiary diamine:n-butyllithium complexes were determined under a standard set of conditions. Complexes of the cyclic diamines 1,2-dipyrrolidinoethane, sparteine, and 1,2-dipiperidinoethane resulted in higher polymerization rates and larger ultimate polymer yields than did complexes of acyclic diamines such as N,N,N′,N′-tetramethylethylenediamine. The rates of polymerization and also the polymer yields were also strongly affected by the length of the chain segment connecting the two amino groups in the diamine. Two carbon segments were superior to three carbon segments which were better than one or four carbon segments. The decomposition rate of n-butyllithium was also strongly accelerated by the presence of many of these diamines.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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