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  • 1980-1984  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 25 (1982), S. 387-390 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Basierend auf nicht-isotherme thermogravimetrische Untersuchungen wurde das thermische Verhalten von Polystyrol [PS], Polymethacrylat [PMA], Polyacrylnitril [PAN], Polystyrol-co-methacrylat [P(S: MA)] (alternierend und random), Polystyrolco-acrylnitril [P(S: AN)] (alternierend) sowie eines Mischpolymeren von Styrol, Methacrylat und Acrylnitril [P(S: MA: AN)] untersucht. Die thermische Stabilität der Kopolymeren liegt zwischen denen der individuellen Homopolymeren. Die thermische Stabilität des Kopolymeren [P(S: AN)] ist höher als die der individuellen Homopolymeren. Die Werte der Aktivierungsenergie sind ebenfalls in Übereinstimmung mit dem thermischen Verhalten dieser Polymere.
    Abstract: Резюме На основе неизотерми ческих термогравиметричес ких исследований, обс уждено термическое поведен ие полистирола, полиметилакрилата, п олиакриронитрила, ко полимера полистирола и метила крилата (чередующего ся и произвольного), копол имера полистирола (чередующе- гося), и трех звенного полимера стирол-метилакрилат-акрилонитрил. Найден о, что термическая усто йчивость кополимеро в является промежуточной среди индивидуальных гомополимеров. Устой чивость трехзвенног о полимера стирол-мети лакрилатакрилонжтр ил является наиболее вы сокой по сравнению с отдельными гомополи мерами. Значения энергии активации со гласуются с термичес ким поведением исследов анных полимеров.
    Notes: Abstract The thermal behaviours of polystyrene (PS), polymethylacrylate (PMA), polyacrylonitrile (PAN), polystyrene-co-methylacrylate [P(S: MA)](alternate and random), polystyrene-co-acrylonitrile [P(S: AN)] (alternate) and a terpolymer of styrene, methylacrylate and acrylonitrile [P(S: MA: AN)] are discussed on the basis of non-isothermal thermogravimetric studies. The thermal stabilities of the copolymers have been found to be intermediate between of those of the individual homopolymers. The stability of the [P(S: AN)] copolymer is higher than those of the individual homopolymers. The activation energy values are also in accordance with the thermal behaviours of these polymers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chlorate resistant mutants of the cyanobacterium Nostoc muscorum isolated after N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) mutagenesis were found to be defective/blocked in nitrate reductase (NR). The parent strain possessed active NR in the presence of nitrogen as nitrate and only basal levels of activity in ammonia and N-free grown cultures. Addition of ammonia suppressed the NR activity in the parent strain whereas addition of L-methionine DL-sulphoximine (MSX) restored NR activity. A similar repression by ammonia, glutamine and derepression with MSX were also observed for nitrogenase synthesis. One class of mutants lacked NR activity (nar -) whereas the specific activity of NR was low in another class of mutants (nar def). Unlike the parent, the mutants synthesized nitrogenase and differentiated heterocysts in the presence of nitrate nitrogen. Uptake studies of nitrite and ammonia in mutants revealed that they possessed both nitrite reductase and glutamine synthetases (GS) at low levels, and the same level respectively in comparison with the parent.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: Available N and P ; Azolla ; Blue-green algae ; Mineralization ; Organic manures ; Rice soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pot incubation study with fresh Azolla (Azolla pinnata-India and Vietnam isolates,A. mexicana andA. filiculoides), blue-green algaAulosira sp., green manureSesbania cannabina, Azolla compost, farm yard manure and ammonium sulphate was conducted under flooded condition at CRRI, Cuttack keeping an equivalent amount of 25 ppm N through all the amendments where changes in availability of N and P, C∶N ratio and pH were recorded. Application of chemical N-fertilizer recorded a release of about 87% NH4 +−N at 10th day of flooding which gradually decreased and reached the minimum of 6% at 50 days. The C∶N ratio of the organic manures ranged between 9–10 favouring release of NH4 +−N and among theAzolla speciesA. pinnata isolates released NH4 +−N more efficiently thanA. filiculoides andA. mexicana. A. pinnata Indian isolate released maximum of 88% NH4 +−N, whereas Vietnam isolate recorded 77% at 40 days of flooding; green manure on the other hand, reached a maximum of 50% release at 50 days. The blue-green alga recorded a gradual increase and attained the maximum release of 38% at 40 days of flooding. Farmyard manure recorded a highest NH4 +−N release of 69% at 20 days of flooding and gradual decrease thereafter, whereas Azolla compost released 41% at 40 days of flooding. Soil amended with fresh organic matter achieved reduction upto a pH of 7.2 after 50 days of flooding, whereas the pH in Azolla compost and farmyard manure amendment was 〈7. The P availability increased from 20th day onwards and reached the highest values of 26 and 18 ppm in the fresh organic matter and compost amended soil respectively after 40–50 days of flooding. The cumulative release of available P was found superior in fresh Azolla incorporation.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 1982-12-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 5
    Publication Date: 1981-02-01
    Print ISSN: 0032-079X
    Electronic ISSN: 1573-5036
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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  • 6
    Publication Date: 1984-01-01
    Print ISSN: 0233-111X
    Electronic ISSN: 1521-4028
    Topics: Biology
    Published by Wiley
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