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81.
The development of a new sample controlled thermal analysis technique based on a heat flux DSC is described. The performance of the system is demonstrated by studies on the decomposition of sodium bicarbonate and the oxidation of a copper impregnated carbon. The ability of the technique to study reactions which take place without a change in mass is illustrated by the curing of an epoxy resin with a polyaminoamide hardener.  相似文献   
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A mathematical model is proposed for the process of vacuum superplasticforming. The model exploits the fact that in most industrialapplications the sheet aspect ratio (thickness/sheet width)is small. After an initial consideration of some of the moregeneral properties and the literature of superplastic materials,the elastic/plastic deformation of an internally-inflated thin-walledcylinder is examined. Plates of arbitrary geometry are thenconsidered. A quasisteady model in which the sheet moves througha sequence of steady states is developed. Some simplified closed-formsolutions are examined, but for general cases a system of nonlinearpartial differential equations must be solved numerically. Anefficient and accurate semi-explicit numerical scheme is proposedand a simplified stability analysis is presented; the methodis then used to compute properties of superplastic vacuum mouldedsheets in a number of practically motivated cases.  相似文献   
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A sample of strontium nitrite has been synthesised and thermally characterised to investigate its role in the ageing of magnesium-strontium nitrate pyrotechnic compositions in the presence of water vapour. Studies by isothermal microcalorimetry show that the addition of strontium nitrite to a 50% magnesium-50% strontium nitrate composition eliminated the induction reaction normally observed in closed ampoule studies in air at 50 °C and relative humidities in the range 65-69%.  相似文献   
86.
The hydrogenolysis of neopentyl iodide on reduced Co or Pt dispersed on MgO support yields increasing amounts of 2-metylbutane and 2-methylbutenes in addition to neopentane, as the temperature is raised from 50 to 150°C. These results support the idea that a π-complexed half-reaction state is simultaneously involved in activation of the R---I bond and in the evident 1,2-methyl shift. This π-complex mechanism is the same as that first suggested almost a quarter of a century ago for neopentane isomerism during hydrogenolysis at 200°C on Pt catalysts. The present results also support the contention that similar π-complexes are responsible for analogous carbon skeleton rearrangement reactions mediated by coenzyme B12.  相似文献   
87.
The synthesis of some 2-amino-1,8-naphthyridine derivatives substituted in the 5- and/or 7-positions with trifluoromethyl is described along with their conversions to the corresponding 1,8-naphthyridin-2(1H)ones. A modified procedure for oxidizing electron-deficient heterocyclic compounds to their N-oxides is presented.  相似文献   
88.
The photochemical reaction of 1 with acrylonitrile gave the cyclobutane adducts II and III, which on treatment with base afforded a novel polycyclic structure IV. Reduction of IV with LAH followed by Eschweiler-Clarke methylation yielded the polyheterocyclic structure VI.  相似文献   
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