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  • 1
    ISSN: 1432-136X
    Keywords: Key words Milk composition ; Lactation ; Calcium ; Bats ; Phyllostomatidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Growth rates of mammalian young are closely linked to the ability of the mother to provide nutrients; thus, milk composition and yield provide a direct measure of maternal investment during lactation in many mammals. We studied changes in milk composition and output throughout lactation in a free-ranging population of the omnivorous bat, Phyllostomus hastatus. Fat and dry matter of milk increased from 9 to 21% and from 21 to 35% of wet mass, respectively, throughout lactation. Energy increased from 6 to 9 kJ · g−1 wet mass, primarily due to the increase in fat concentration. Total sugar levels decreased slightly but non-significantly. Mean sugar level was 4.0% of wet mass. Protein concentration increased from 6 to 11% of wet mass at peak lactation and then decreased as pups approached weaning age. Total milk energy output until pups began to forage was 3609 kJ. Milk levels of Mg, Fe, Ca, K, and Na averaged 0.55 ± 0.26, 0.23 ± 0.2, 8.75 ± 4.17, 5.42 ± 2.11, and 9.87 ± 4.3 mg · g−1 dry matter, respectively. Of the minerals studied, calcium appears to be most limiting in this species. The high degree of variability in foraging time, milk composition and milk yield between individuals at the same stage of lactation could potentially yield high variance in reproductive success among females of this polygynous species.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0170-2041
    Keywords: γ-Lactones ; Radical additions ; Felkin-Anh model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radikaladditionen im wäßrigen Medium: Eine direkte Synthese von 5-allylsubstituierten γ-Lactonen aus Allylbromiden/Zink und γ-Oxo-carbonsäureesternNach einer von Luche publizierten Methode werden die 5-allyl-substituierten γ-Lactone 2a-2d in guten Ausbeuten aus den γ-Oxocarbonsäureestern 1a-1c und Allylbromiden/Zinkstaub im wäßrigen Medium hergestellt. Die Diastereoselektivität dieser Allylierungsreaktion wird mit der durch Lewis-Säure-induzierten Allyltrimethylsilan-Addition an chirale Aldehyde verglichen.
    Notes: Following a procedure published by Luche, 5-allyl-substituted γ-lactones 2a-2d are prepared in good yield from methyl γ-oxocarboxylates 1a-1c and allyl bromides/zinc dust in aqueous medium. The diastereoselectivity of this allylation reaction is compared to that of Lewis acid promoted additions of allyltrimethylsilane to chiral aldehydes.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: γ-Lactones, di- and tetrasubstituted ; Chelates, seven-membered ; Allylsilane additions, Lewis acid promoted ; Felkin-Anh model ; Aldehydes, chiral ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ein chelatkontolliere Weg zu di-und tetasubstituierten γ-Lactonen - Stereoselektivität von Lewis-Säre-indzierten Additionen an chirale β-Formylcarbonsäure-methylesterDie chiralen β-Formylcarbonsäure-methylester 1a-1h liefern mit Allyltrimethylsilan/TiCl4 disubstituierte und tetrasubstituierte γ-Lactone 3a-3h mit mäßigen bis exzellenten Diastereoselektivitäten. Andere Lewis-Säuren sind weniger selektiv. Die Bildung von siebengliedrigen Chelaten 1 · TiCl4 wurde in einigen Fällen NMR-spektroskopisch eindeutig nachgewiesen. Trichlormethyltitan zeigt ein ähnliches Selektivitätsmuster wie die Reagentienkombination Allylsilan/TiCl4. Die Aldehyde 1a-1d, 1g und 1h werden hauptsächlich in trans-γ-Lactone umgewandelt, während 1f unter geeigneten Bedingungen im Überschuß das cis-γ-Lacton 3f liefert. Diese Ergebnisse werden unter Berücksichtigung des Felkin-Anh-Modells und der Chelatbildung diskutiert. Außerdem werden weitere Modellreaktionen mit den einfacheren chiralen Aldehyden 5 und 7 sowie mit den Acetalen 9a/b und 11a/b vorgestellt. Diese unterstreichen die Bedeutung der Chelatkontrolle bei den Additionen an die β-Formylester 1.
    Notes: On reaction with allyltrimethylsilane/TiCl4, chiral methyl β-for-mylcarboxylates 1a-1h provide disubstituted and tetrasubstituted γ-lactones 3a-3h with moderate to excellent diastereoselectivities. Other Lewis acids are less selective. The formation of seven-membered ring chelates 1 · TiCl4 has been proven unambiguously by NMR spectroscopy in several cases. Trichloromethyltitanium displays a selectivity pattern similar to the reagen combination allylsilane/TiCl4. Aldehydes 1a-1d, 1g, and 1h give primarily trans-γ-lactones, whereas under appropriate conditions 1f affords an excess of cis-γ-lactone 3f. These results are discussed with regard to the Felkin-Anh model and to chelate formation. Model studies with simpler chiral aldehydes 5 and 7 as well as with acetals 9a/b and 11a/b are presented and discussed. They emphasize the importance of chelate control in additions to β-formyl esters 1.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
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