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  • 1995-1999  (2)
  • 1965-1969  (1)
  • Chemistry  (2)
  • Chemoattractant  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 11 (1998), S. 81-85 
    ISSN: 1432-2145
    Keywords: Key words Closterium ehrenbergii ; Chemoattractant ; Conjugation ; Sexual pheromone ; Protoplast-release-inducing protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In sexual reproduction of Closterium ehrenbergii, pairing with the sexual partner cells is the first process observed. A cell migration-inducing activity, specific for mating-type plus (mt+; NIES-228) cells, was detected in the culture medium of mating-type minus (mt–; NIES-229) cells. Light was necessary for production of the active substance by mt– cells and for migration of mt+ cells. The active substance was heat-labile and had an apparent molecular mass of 20 kDa, as determined by gel filtration. A protein of 20 kDa was detected in the active fraction of gel filtration after sodium dodecyl sulfate polyacrylamide gel electrophoresis. Based on these results, it is proposed that a chemotactic sexual pheromone involved in the formation of sexual pairs of cells is secreted by mt– cells of C. ehrenbergii and is proteinaceous, like other sexual pheromones secreted by Closterium species.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 35 (1995), S. 1261-1271 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This study clarifies and quantifies factors which increase the ductility of a low-molecular-weight propylene homopolymer having an intrinsic viscosity of 0.89 dl/g. The tensile behavior of homopolymer/ethylene-propylene rubber (EPR) blends was studied from the viewpoint of the associated molecular structure of EPR and its compatibility with the homopolymer. When EPR is “dissolved” in a homopolymer, the glass transition temperature (Tg) of the amorphous phase of a homopolymer was found to shift to a lower temperature, with homopolymer/EPR compatibility being subsequently evaluated using this shift, i.e., Δtg. Results show two conditions are required to improve the ductility of the low-molecular weight propylene homopolymer: ΔTg must be ≥ 3°C and ≥ 30 wt% EPR must be blended with the homopolymer.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 98 (1966), S. 58-65 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von H2O mit Al-triäthyl (Al(C2H5)3) und der Initiierungsmechanismus der Polymerisation wurden durch Anwendung von tritiiertem H2O untersucht. Beträchtliche Tritium-Anteile aus tritiiertem H2O verblieben im System Al(C2H5)3/H2O bei Zimmertemperatur. Wärmebehandlung des Systems bewirkte eine starke Abnahme des Tritium-Gehalts und einen Verlust der Katalysatoraktivität. Mit dem System Al(C2H5)3/H2O hergestellte Polymere erwiesen sich als radioaktiv. Auf Grund der Ergebnisse wurde angenommen, daß im System Al(C2H5)3/H2O acider Wasserstoff vorhanden und für die Initiierung einer kationischen Polymerisation verantwortlich ist.
    Notes: The reaction between H2O and triethylaluminum Al(Et3) as well as the initiation mechanism of the polymerization by the system AlEt3/H2O have been examined by means of tritiated water, Considerable amount of tritium from tritiated water remained in the system AlEt3/H2O prepared at room temperature. Heat treatment of the system causes both the extensive decrease of tritium content and loss of catalyst activity. Polymers of styrene and isobutyl vinyl ether prepared by the system AlEt3/H2O were found to be radioactive. These findings have been taken to assume that acid hydrogen does exist in the system AlEt3/H2O and is directly responsible for the initiation of cationic polymerization.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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