Flow of cholesteric liquid crystals—I: Flow along the helical axis

It is shown that the essential features of Helfrich’s permeation model for flow along the helical axis of a cholesteric liquid crystal can be derived approximately on the basis of the Ericksen-Leslie theory.     

Ab initio molecular orbital calculations on ion pair-water complexes of metal halides and oxides

Ab initio MO calculations are performed on a series of ion-molecular and ion pair-molecular complexes of H₂O + MX (MX = LiF, LiCl, NaCl, BeO and MgO) systems. BSSE-corrected stabilization energies, optimized geometrical parameters, internal force constants and harmonic vibrational frequencies have been evaluated for all the structures of interest. The trends observed in the geometrical parameters and other properties calculated for the mono-hydrated contact ion pair complexes parallel those computed for the complexes of the individual ions. The bifurcated structures are found to be saddle points with an imaginary frequency corresponding to the rocking mode of water molecules. The solventshared ion pair complexes have high interaction energies. Trends in the internal force constant and harmonic frequency values are discussed in terms of ion-molecular and ion-pair molecular interactions.     

Coordination and organometallic chemistry of cyclophosphazenes and polyphosphazenes

This review describes the chemistry of cyclophosphazene and polyphosphazene ligand systems and their transition and organometallic complexes. The structures of the ligands and the complexes are discussed.     

Substoichiometric determination of selenium with potassium ethyl xanthate

A substoichiometric radiochemical method has been developed for the determination of selenium with potassium ethyl xanthate. The selenium ethyl xanthate complex formed was extracted into chloroform from borate buffer at pH 5. The effect of foreign ions on the extraction was studied. Microgram quantities of selenium could be conveniently determined with a fair degree of accuracy. The method has been successfully applied for the determination of selenium content in food stuffs such as Jaggery and Wheat powder.     

Comparative substoichiometric extraction and quantification of mercury in geological water samples with potassium salts of ethyl,propyl, butyl,pentyl and benzyl xanthates

The relative extent of extraction of mercury with potassium salts of ethyl, propyl, butyl, pentyl and benzyl xanthates has been studied employing a sensitive and rapid substoichiometric radiochemical method. The effect of pH on the extractability of mercury xanthate complexes into chloroform was investigated. Buffer solutions of pH 12, 11, 10, 9 and 5.5 were found to be suitable media for the maximum extraction of mercury as ethyl, propyl, butyl, pentyl and benzyl xanthate complexes, respectively. The procedures developed were utilized for the determination of mercury content in standard solutions and geological water samples collected in eight parts of Chittoor district of Andhra Pradesh.     

Substoichiometric radiochemical determination of antimony with potassium ethyl xanthate

A rapid and sensitive substoichiometric radiochemical method has been developed for the determination of microgram amounts of antimony employing potassium ethylxanthate as a reagent and chloroform as an extractant from sulfuric acid medium. The effect of associated ions on the extraction was studied. The method developed was successfully applied to determine the antimony content in standard solutions and synthetic mixture with an average error ±2.07%