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  • Chemistry  (2)
  • Abscisic acid  (1)
  • 1
    ISSN: 1573-5087
    Keywords: Abscisic acid ; cytokinins ; drought ; ethylene ; gibberellins ; sunflower ; water stress ; aeroponics ; roots ; shoots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Abscisic acid (ABA), cytokinins and gibberellin-like substances (GAs) were extracted from the roots and shoots of 17-day-old sunflower seedlings which had been droughted or were unstressed. Plants were grown in an aeroponic chamber which allowed for good control over degree of water stress and easy access to roots. Following methanolic extraction of lyophilized material, cytokinins were separated from the acidic growth-regulators on a cellulose PO4 cationic exchange column. The cytokinins were analysed by paper chromatography and HPLC and the soybean hypocotyl section assay. Semipurified acidic regulators were chromatographed on SiO2 columns and HPLC and aliquots assayed with the dwarf rice cv. Tan-ginbozu bioassay for GAs. Fractions known to contain ABA were purified by sequential reverse-phase HPLC of the acid and then of the methyl ester forms followed by quantitation as Me-ABA on GLC-EC. ABA losses were measured by using an internal standard [3H]-ABA). Ethylene production was also monitored in stressed and unstressed seedlings. The effect of drought on GAs and ethylene was minimal. The ABA levels were markedly higher in droughted plants. Stressed roots had 32 times more ABA than controls. The levels of cytokinins in the shoots of droughted plants were about half those in unstressed shoots, and qualitative differences occurred in the roots. Under stress a large peak of activity was present similar to zeatin glucoside which was not present in the unstressed condition. The results are discussed in relation to drought-effects on metabolism.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Process Safety Progress 17 (1998), S. 49-60 
    ISSN: 1066-8527
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This paper reports on a comprehensive literature search and small scale experimental work on the reaction characteristics of phosphorous trichloride and water. More than 30 tests were conducted, including both closed and open test cells. The water to phosphorus trichloride molar ratio was varied from 1 to 25. When in contact, water and phosphorus trichloride will form two liquid layers with a reaction starting at the interface. The impact of variables on reaction rates including the interface surface area, layer depth, and stirring were investigated experimentally. A reaction rate model that fits all the measured data is presented. Case studies illustrating the use of this data for emergency relief systems and vent containment design are presented in reference. [1].
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The NMR. spectra of the five monomethylazulenes and of some polysubstituted azulenes, as well as those of their conjugate acids (azulenium cations), are recorded. It is shown that protonation of azulenes lacking C2v symmetry leads to a tautomeric equilibrium of two conjugate acids. The position of this tautomeric equilibrium is in essential agreement with the one previously predicted from the UV. spectra on the basis of a MO treatment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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