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  • Author: R.N. Sharma x
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The compressibility and collisional effects on thermal instability of a composite medium are considered. The effect of compressibility is found to be stabilizing. In contrast to the nonoscillatory modes for (Cp/g) ß > 1 in the absence of a magnetic field, Cp, ß and g being the specific heat at constant pressure, a uniform adverse temperature gradient and the acceleration due to gravity respectively, the presence of a magnetic field introduces oscillatory modes in the system. The sufficient condition for non-existence of overstability is found. The magnetic field is found to have a stabilizing effect on the system for (Cp/g) ß > 1.


A new group of bands, designated as system A, of antimony monobromide, lying in the region 5340 -4905 Å, has been photographed and completely analysed. Two characteristic continua with maxima at 5320 Å and 6500 Å have been observed. The electronic states with the recorded band systems have been tentatively assigned.


Reaction of thiophosgene or phosgene on 2′-aminonaphthanilides (2, 5) gave the corresponding 2-substituted-6-oxonaphth[2′,3′: 5,6]-1,3-oxazino[3,2-b]benzimidazoles (3) and 6-oxonaphth[1′,2′:5,6]-1,3-oxazino[3,2-b]benzimidazoles (6) respectively. The mechanism of such reactions has been studied by carrying reaction between 2′-hydroxy - anthranilide (7 a) and thiophosgene in acidic and basic media.


Reaction of N,N-dialkyl-β-aminoketones (5 and 7) with hydroxylamine hydrochloride in pyridine results in the dealkylated oximine (6). The mechanism of this N-dealkylation may be explained as due to the neighbouring group participation of the oximine formed during the reaction.