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  • 1975-1979  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 8 (1975), S. 15-26 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a étudié la sensibilité explosive des perchlorates de méthylammonium par ATD TG, spectrométrie de masse et expériences de retard à l'explosion. La température de décomposition de ces composés augmentedans l'ordre suivant: CH3NH3CIO4〉(CH3)2NH2ClO4〉 〉(CH3)3NHClO4. L'énergie d'activation suit un ordre inverse indiquant une augmentation de la stabilité des composés avec le degré de substitution. L'étude par spectrométrie de masse permet en plus de conclure que l'augmentation de la substitution entraîne une réactivité plus grande. On propose une explication de ce comportement. Il semble que le retard à l'explosion soit en corrélation avec la décomposition thermique et la sensibilité d'impact.
    Abstract: Zusammenfassung Die Explosionsempfindlichkeit von Methylammoniumperchlorat wurde durch DTA, TG und Massenspektrometrie, sowie durch Explosionsverzögerungsversuche untersucht. Die Zersetzungstemperatur der Verbindungen nimmt in der Reihenfolge CH3NH3ClO4 〉(CH3)2NH2ClO4 〉(CH3)3NHClO4 zu. Die Aktivierungsenergiezunahme verläuft entgegengesetzt, was dafür spricht, daß die Stabilität mit steigender Substitution wächst. Die massenspektrometrische Prüfung hingegen zeigt zunehmende Reaktivität mit steigender Substitution. Eine mögliche Erklärung der experimentellen Ergebnisse wurde gegeben. Es scheint, daß die Explosionsverzögerung mit der thermischen Zersetzung und Stoßempfindlichkeit in Zusammenhang ist.
    Notes: Abstract The explosive sensitivity of methylammonium perchlorates has been investigated by differential thermal analysis, thermogravimetric analysis, mass spectrometry and explosion delay experiments. The decomposition temperature of these compounds increases in the order CH3NH3ClO4〉(CH3)2NH2ClO4〉(CH3)3NHClO4. The activation energy shows the reverse order, indicating thereby that the stability increases with increasing substitution. Mass spectrometric investigation, however, suggests an increasing reactivity with increasing substitution. A possible explanation for such behaviour is proposed. It appears that explosion delay is correlated with thermal decomposition and impact sensitivity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Antonie van Leeuwenhoek 42 (1976), S. 471-482 
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An NADP+-specific isocitrate dehydrogenase has been purified and characterized from Rhizobium meliloti. The enzyme showed Mn++ or Mg++ requirement. The apparent Km values were 2.00×10-5 m and 1.51×10-5 m for dl-isocitrate and NADP+, respectively. The enzyme was inhibited by ATP, to a lesser extent by ADP and AMP. α-Ketoglutarate also inhibited the enzyme activity. Oxalacetate and glyoxylate together inhibited the enzyme activity. The inhibition was competitive. Studies with thiol inhibitors suggested that the enzyme contained a sulfhydryl group at or near the active site. The enzyme has an approximate molecular weight of 60 000. Fluorescence studies suggested that the enzyme contained tryptophan
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 7 (1975), S. 587-592 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a étudié la décomposition thermique du perchlorate de méthylammonium (PMA) en conditions isothermes et anisothermes. L'analyse thermique différentielle des perchlorates de méthylammonium a montré, en plus du phénomène exothermique dû à la décomposition, un second pic exothermique à 408°C, observé pour la première fois. L'analyse chimique et le spectre infrarouge du résidu de décomposition ont établi la présence de NH4ClO4. Les résultats s'expliquent bien par le transfert d'un groupe méthyle accompagné d'un transfert de proton lors du processus de décomposition.
    Abstract: Zusammenfassung Die thermische Zersetzung von Methylammonium-Perchlorat (MAP) wurde unter isothermen Bedingungen untersucht. Die DTA zeigte neben der exothermen Spitze für die Zersetzung noch eine weitere bei 408°, über die noch nie berichtet wurde. Die Analyse des Zersetzungsrückstandes ergab NH4ClO4. Diese Ergebnisse wurden durch einen zusätzlich zur Protonenübergabe ablaufenden Methylgruppentransfer erklärt.
    Notes: Abstract The thermal decomposition of methylammonium perchlorate (MAP) has been studied under isothermal and non-isothermal conditions. Differential thermal analysis of MAP showed, in addition to the exotherm due to decomposition, another exotherm at 408° which was observed for the first time. Chemical analysis and the infrared spectrum of the residue left behind after the decomposition proved it to contain NH4ClO4. The results have been explained on the basis of a methyl group transfer in addition to proton transfer in the decomposition process.
    Type of Medium: Electronic Resource
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