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  • 1970-1974  (2)
  • 1960-1964  (2)
  • Polymer and Materials Science  (3)
  • Life and Medical Sciences  (1)
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Material
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Year
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  • 1
    Electronic Resource
    Electronic Resource
    Capacitation of boar spermatozoa: The influence of post-coital separation of the uterus and fallopian tubes (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 180 (1974), S. 597-603 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The minimum period of uterine exposure required by ejaculated boar spermatozoa as a preliminary to rapid capacitation has been determined after natural or surgical deposition of sperm samples directly into the uterine lumen. Twenty-four oestrous gilts were mated or inseminated close to the time of ovulation, and 15, 30, 45 or 60 minutes later, the Fallopian tubes were separated from the uterine cornua. The tubes were flushed at pre-arranged intervals during a second intervention, and the proportion of eggs penetrated and activated examined by phase-contrast microscopy.On the basis of 166 eggs recovered from eighteen mated gilts, a period of uterine exposure as brief as 30 minutes, when followed by a tubal residence of approximately three hours, permitted 30.3% of the eggs to be activated; this proportion increased to 51.6% and 60.5% if the tubes were isolated 45 or 60 minutes, respectively, after mating (p 〈 0.001), as did the mean number of spermatozoa associated with the eggs. When the cornua were separated from the tubes 15 minutes after semen deposition into the uterus of six animals, 11.3% of 62 eggs were fertilized during the ensuing three and one half hours, but very few spermatozoa had reached and/or attached to the eggs in this group.It is concluded that a population of boar spermatozoa potentially capable of effecting fertilization may enter the tubes within 15 to 30 minutes of mating near the time of ovulation, and that such vanguard spermatozoa can activate a proportion of the eggs within a further two to three hours. Thus, from a temporal point of view, the major components of the capacitation process in oestrous pigs are inferred to take place in the Fallopian tubes.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091800406
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of activated gas plasma treatment time on adhesive bondability of polymers (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1465-1477 
    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 bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low-density polyethylene, high-density polyethylene (two types), poly(4-methyl-1-pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength-versus-exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160615
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Emulsion copolymerization of butadiene and styrene in the presence of carbon black (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 693-709 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carbon blacks inhibit and retard free radical polymerization in bulk and solution. The mechanism of this is discussed in terms of the chemical groups present on the carbon surface. It is shown that the number of free radicals which react during the induction period (polymerization of styrene with AIBN) is much less than the number of quinone groups but of the same order of magnitude as the number of easily oxidizable groups. Inhibition by carbon black was also found in an emulsion polymerization system with cumene hydroperoxide as initiator (no reducing components). By use of highly active redox recipes, reasonable rates of polymerization were obtained at both 50°C. (sugar-iron-hydroperoxide recipe) and 5°C. (peroxide-polyamine recipe), with as much as 40 parts of black per 100 parts of monomers. In these systems, the carbon black was charged as an aqueous dispersion stabilized with Daxad 11; the latices were stable and showed evidence of association between some of the carbon black and some of the latex particles. The coagulated rubber stocks, when compounded and cured, gave properties closely similar to those of dry mixed stocks.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1962.1205716555
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  • 4
    Electronic Resource
    Electronic Resource
    Homogeneous anionic polymerization. II. Molecular weight of polystyrene initiated by lithium alkylsPresented in part at the 136th National Meeting, American Chemical Society, Division of Polymer Chemistry, Atlantic City, N. J., September 1959. (1963)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 461-474 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out on the molecular weights and their distribution for polystyrene prepared by means of ethyl and butyl lithium initiators, using benzene and tetrahydrofuran as solvents. Stringent high vacuum techniques were employed in order to minimize any destruction of initiator or termination of growing chains in these anionic polymerizations. Under these conditions, it was found that the stoichiometry corresponded to the formation of one chain from each initiator molecule. Furthermore, the molecular weight distribution could be made very narrow (M̄w/M̄n = 1.05 - 1.1) in these cases, where the initiation reaction was very rapid compared to the propagation step. In the case of the benzene systems, the initiation reaction was too slow, leading to a broadening of the molecular weight distribution, and this could be circumvented by a “seeding” technique whereby all the chain anions were pre-initiated before the main polymerization took place. The alkyl lithium initiators were found to react rapidly with THF at room temperature, but the styryl lithium apparently did not.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1963.100010140
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    Paper (German National Licenses)
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