Electrical Transport during Structural Transformations of Alkali Perchlorates

852-85

Thermal Decomposition of UV-irradiated Barium Azide

571-57

Reactivity of The Ternary Pyrotechnic System Red Lead - Silicon - Ferric Oxide

The reactivity of the ternary system of red lead, silicon and ferric oxide has been studied in comparison with the binary system red lead-silicon. Results from Differential Scanning Calorimetry (DSC) in nitrogen environment and Differential Thermal Analysis (DTA) in air have been supplemented with hot stage microscopy and combustion rate studies at about 30 atmospheres pressure. The ternary mixtures show three characteristic exotherms whose relative exothermicities vary with composition. DTA showed an unusual feature of a strong single exotherm at a certain critical mass which also varies with the composition. The critical mass could be reproduced within +-1.0 mg. Hot stage microscopy of the pyrotechnic samples revealed strong surface mobility during the reaction leading to the formation of a sintered product. Self sustained combustion rates of the samples show an inhibiting effect by ferric oxide

Thermal Decomposition Mechanism of Silver Nitrobenzoates

The infra-red spectra of silver salts of 3-mono-, 3,5-di-and 2,4,6-tri-nitro-benzoic acids have been recorded at elevated temperatures in a fabricated high temperature cell. The thermogravimetry i.e. TG analysis has also been carried out. The results of this study suggest that decomposition of these salts is a two stage process i.e. decarboxylation followed by explosion

Mechanism of crystal structure transformations. Part 3. Factors affecting the anatase-rutile transformation

The particle size and crystallite size of anatase increase markedly in the region of the crystal structure transformation. The unit cell of anatase seems to expand prior to the transformation to rutile. This expansion has been attributed to a displacive transformation of the type defined by Buerger. Smaller particle size and larger surface area seem to favour the transformation. The kinetics of the transformation of anatase prepared by the hydrolysis of titanium sulphate have been studied at different temperatures and are found to be considerably different from the kinetics of the transformation of pure anatase. The transformation becomes immeasurably slow below ~695±10°C compared to ~610°C for pure anatase. An induction period is observed in the transformation of anatase obtained from sulphate hydrolysis and the duration decreases with increase in temperature. The activation energy is ~120 kcal/mole, a value higher than that for the pure anatase-rutile transformation. The results have been interpreted in terms of the relative rates of nucleation and propagation processes. The activation energy for the nucleation process seems to be much larger than for the propagation process. The kinetics of the transformation of anatase samples doped with different amounts of sulphate ion impurity have also been studied and the transformation is found to be progressively decelerated with increase in the impurity concentration. The energy of activation for the transformation appears to increase progressively with increase in impurity concentration

Pharmacognostical evaluation of root bark of <i style="">Streblus asper</i> Lour

176-180Streblus asper Lour. known as Shakhotaka in Ayurveda and Piraayan in Siddha is an important medicinal plant belonging to family Moraceae. The root bark is antipyretic, antidysentric and analgesic, and sedative. The study provides taxonomical, pharmacognostical and physicochemical details helpful in laying down standardization and pharmacopoeial parameters. The diagnostic characters are latex exudation, lenticular opening, crystals and latex cells in secondary phloem, 2-3-seriate medullary rays, and septate fibers. Physicochemical studies revealed, total moisture content (8.91%), total ash (15.00%), acid insoluble ash (5.65%), water-soluble ash (3.23%), alcohol soluble extractive value (18.05%), and water-soluble extractive value (35.83%). Ultraviolet analysis exhibited considerable variation. Preliminary organic analysis revealed carbohydrates, glycosides, phytosterols, phenolic compounds, tannins, saponin, gums and mucilage. Thin layer chromatographic studies gave 8 and 7 spots in alcohol and aqueous extracts, respectively