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  • Author: R. Prasad, x
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Abstract

On the basis of previous experimental results by many workers on the structures of CdI2 polytypes, it has been suggested that the growth of various polytypes and the distribution of the various types of stacking faults (deformation, intrinsic faults or a combination of these two) can be immediately known based on the ratio of hexagonal to cubic layers of the structure.

The formation and composition of thorium arsenates obtained by the interaction of thorium nitrate and different alkali arsenates (meta, pyro and ortho) at specific pH levels 7.2, 8.3 and 11.1 have been studied by employing electrometric techniques involving amperometric, pH, potentiometric and conductometric titrations. The results provide cogent evidence for the formation of three thorium arsenates having the molecular formulae ThO2·2 As2O5, ThO2·As2O5 and 3 ThO2·2 As2O5 in the vicinity of pH 4.2, 4.9 and 5.6 respectively. Analytical investigations of the compounds have also been carried out which substantiate the results of electrometric study.

Measurements of the magnetic susceptibility of a powdered sample of VTe in the temperature range 90 - 700 K, and of the a.c. electrical conductivity (σ), thermoelectric power (θ) and dielectric constant (ε′) of pressed pellets of the compound in the temperature range 300 -1100 K are reported. The compound is found to be antiferromagnetic with Neel temperature 420 ± 5 K. The effective paramagnetic moment and paramagnetic Curie temperature are found to be 1.6 μB and - 250 K, respectively. The dependence of σ, θ and ε′ on temperature shows no anomaly at the Neel temperature and is indicative of the metallic nature of the compound.

Abstract

Structural-geometrical schemes for the creation of structural series for cadmium iodide polytypes have been worked out based on layer-transposition mechanism. The existence of all the cadmium iodide polytypic series have been accounted for. The occurrence of polytypic structural series has remained inexplicable so far based on the layer transposition mechanism; the present study therefore lends direct support to Jagodzinski's layer-transposition mechanism.

Reaction of 2-cinnamoyl-1-hydroxycarbazoles 2a - d, with phenacyl bromide, mercuric acetate and H2O2/NaOH under different reaction conditions yielded 2-benzoyl-3-styryl-furo[2,3-a]carbazoles 3a-d, 2-benzylidene-furo[2,3-a]carbazol-3(10H)-ones 4a - d and 3-hydroxy-2-phenylpyrano- [2,3-a]carbazol-4(11H)-ones 5a - d, respectively.

The lipid composition of beech (Fagus sylvatica) seeds is reported in the present study. Triacylglycerols (94.8% ) were found to be the major component in the oil followed by sterols (0.9% ) diacylglycerols (0.8% ), phospholipids (0.7% ), free fatty acids (0.5% ) and monoacylglycerols (0.3% ) in minor quantities. The composition of molecular species of triacylglycerols was analyzed by GC on the basis of chain length and C-57 was found to be the major species followed by C-55, C-59, C-53 and C-61. The sterol fraction constituted β-sitosterol and stigmasterol with 89.3 and 10.7% respectively. Phosphatidylinositol and phosphatidylethanolamine were the two phospholipids with 55 and 45% present in the phospholipid fraction of the beech seed oil. Oleic, linoleic and palmitic acids were found to be the major fatty acids in all the acyl lipid classes with small variations in quantities.