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  • Electronic Resource  (2)
  • 1995-1999  (1)
  • 1990-1994  (1)
  • 1985-1989
  • Key words Corticosterone  (1)
  • Polymer and Materials Science  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 169 (1999), S. 303-310 
    ISSN: 1432-136X
    Keywords: Key words Corticosterone ; Testosterone ; Food-stress ; Nest-bound chicks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this study we examined hormonal responses of Black-legged Kittiwake (Rissatridactyla) chicks to experimental variations in energy content and nutritional quality (low or high lipid to protein ratio, LPR) of their food. Starting at the age of 10 days, chicks were fed either high or low LPR fish at 30, 50, 70 and 100% of ad libitum energy intake. After 20 days of treatment, chicks were exposed to a standardized acute handling and restraint stress protocol, where a baseline sample was taken immediately after taking a chick from the nest, and three additional blood samples were taken at intervals up to 50 min. Testosterone and corticosterone titres in plasma were measured via radioimmunoassay. We found that baseline testosterone levels were not significantly affected by the experimental treatments. Food-restricted chicks had elevated baseline and acute stress-induced levels of corticosterone compared to chicks fed ad libitum. An elevation of circulating levels of corticosterone in energetically stressed individuals was further magnified by low nutritional quality of food. Baseline and acute stress-induced corticosterone levels of chicks were negatively correlated with their fat reserves. We conclude that the physiological condition of Black-legged Kittiwake chicks can be assessed reliably by measuring circulating levels of corticosterone. We discuss short- and long-term effects of elevated corticosterone secretion in food-stressed nest-bound chicks.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 43 (1992), S. 327-330 
    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 physikalischen Eigenschaften von Polymercompositen, die durch Mischung des kristallinen, bioabbaubaren und bioverträglichen Polymers Poly-D( - )(3-hydroxybutyrat) (PHB) mit nichtkristallinem, ataktischen Poly(epichlorhydrin) (PECH) erhalten wurden, werden untersucht. Die durch Eindampfen von Lösungen hergestellten PHB/PECH-Mischungen wurden mit Hilfe von thermomechanischen, röntgenographischen und viskolastischen Messungen sowie durch ihr Festigkeits- und Dehnungsverhalten charakterisiert. Aus den Ergebnissen wurde geschlossen, daß die kristallinen Bereiche des PHB die Rolle von Vernetzungen spielen, während das zwischen den kristallinen Bereichen befindliche amorphe PECH als Weichmacher wirkt. Ein einfacher dynamischer Verlustmodul, der der Glasübergangstemperatur entspricht, weist auf die Mischbarkeit des kristallinen PHB mit dem amorphen PECH hin.
    Notes: Physical properties of a new polymer blend obtained by mixing poly-D( - )(3-hydroxybutyrate) (PHB), a crystalline polymer with interesting properties of biodegradability and biocompatibility, with uncrystallizable atactic poly(epichlorohydrin) (PECH) were studied. PHB/PECH blends, obtained by casting solution, were analysed by thermomechanical and X-ray analysis, viscoelastic measurements, and on the basis of strength and elongation measurements. It was concluded that the crystalline region of PHB plays an important role of crosslinks, and amorphous PECH filled between the crystalline regions plays a role of plasticizer. A single dynamic loss modulus, corresponding to the glass transition temperature, implies the miscibility between crystalline PHB and amorphous PECH.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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