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  • 1
    ISSN: 1420-9071
    Keywords: Pineal gland ; hypophysectomy ; N-acetyltransferase ; melatonin ; prolactin ; growth hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hypophysectomy in adult male rats greatly attenuated the nocturnal rise in both pineal N-acetyltransferase (NAT) activity and melatonin content. High nighttime levels of NAT and melatonin were not restored by treating the animals with either prolactin or growth hormone, alone or in combination. Treating intact rats with bromocriptine, which depresses circulating prolactin levels, also was without effect on pineal melatonin synthesis. It appears that neither prolactin nor growth hormone are of major importance in determining pineal melatonin production.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1254
    Keywords: 6-Methoxy-2-benzoxazolinone ; 6-MBOA ; Melatonin ; Hamster ; Natural photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Adult male hamsters bearing either a blank beeswax, 6-methoxy-2-benzoxazolinone (6-MBOA), or melatonin pellet were exposed to 8 weeks (Oct. 6–Dec. 6) of natural autumn decreasing photoperiod (〈11 h light) and temperature conditions (mean 10°C for last 4 weeks) or to a 14 h light/10 h dark (14L∶10D) photoperiod and controlled temperature (20°C). Melatonin but not 6-MBOA pellets partially prevented the combined effects of short photoperiod and cold temperatures on the testes and accessory organs. However, both 6-MBOA-and melatonin-treated hamsters maintained outdoors had significantly higher pituitary follicle stimulating hormone (FSH) values compared to their respective indoor-treated controls or to the animals kept outdoors and treated with a blank beeswax pellet. When one compares the various effects of 6-MBOA and melatonin (2 mg/month) on the reproductive system of the male hamster, 6-MBOA is not as effective as melatonin in altering reproductive responses to short photoperiod and cool temperatures at the dose administered.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4935
    Keywords: deiodinase ; thyroxine ; Swiss mouse ; pineal ; Harderian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Type II thyroxine 5′-deiodinase (5′-D) activity in both pineal and Harderian glands of the Swiss mouse was studied. Pineal 5′-D activity exhibited a nyctohemeral profile with a maximal peak value at 05.00 h, which coincides with that for pineal melatonin production. However, no rhythm of 5′-D activity in the Harderian gland could be found. In pineal gland, light at night inhibited the nocturnal increase in 5′-D activity, while isoproterenol, a β-adrenergic agonist, could not stimulate the enzyme. In the Harderian gland, neither darkness, nor light at night, or isoproterenol were capable of modifying basal values of 5′-D activity.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 44 (1993), S. 449-453 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Metastable iron-manganese alloys - new weld materials used in valve manufactureThe application of protective claddings by weld surfacing is the only possibility of effectively and economically increasing the reliability and service life of components subject to wear. In the case of exposure to adhesive and abrasive wear under high surface contact force, such as that which occurs in the sealing surface area of valves, newly developed austenitic iron-manganese weld surfacing alloys can be substituted for iron-chromium-nickel materials, as well as copper-, nickel-, and cobalt-based materials hitherto employed. These economical materials, which exhibit good working properties from a welding engineering standpoint, form an optimal load-bearing edge layer under load because of a metastable state; this layer is constantly reproduced during exposure to wear. Frictional and wear characteristics, surface structure, and corrosion resistance, as well as the closely associated service life, thus in part considerably exceed that of conventional materials.
    Notes: Das Auftragschweißen von Schutzschichten ist häufig die einzige Möglichkeit, die Zuverlässigkeit und Lebensdauer von verschleißbeanspruchten Bauteilen mit geringen Kosten wesentlich zu erhöhen. Für Beanspruchungen adhäsiven und abrasiven Verschleißes unter höchsten Flächenpressungen, wie sie z. B. im Dichtflächenbereich von Armaturen auftreten, können neu entwickelte austenitische Eisen-Manganlegierungen bisher verwendete Eisen-Chrom-Nickel-Werkstoffe sowie Kupfer-, Nickel- und Kobaltbasiswerkstoffe gut substituieren. Diese preisgünstigen, auch schweißtechnisch gut verarbeitbaren Werkstoffe bilden aufgrund eines metastabilen Zustandes unter Belastung einen optimal beanspruchungsgerechten Randschichtaufbau aus, der sich bei Verschleiß ständig reproduziert. Reibungs- und Verschleißverhalten, Oberflächenausbildung und Korrosionsbeständigkeit und die damit primär beeinflußte Standzeit übertreffen dadurch die der konventionellen Werkstoffe teilweise erheblich.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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