4-Oxatricyclo[5.2.1.0(2,6)]decan-10-one and 4-oxatricyclo[5.2.1.0(2,6)]dec-8-en-10-one. Experimental and DFT investigations of the pi-selectivities.

Ab initio MO and experimental pi-selectivities of hydride additions to 4-oxatricyclo[5.2.1.0(2,6)]decan-10-one and 4-oxatricyclo[5.2.1.0(2,6)]dec-8-en-10-one are described. The interactions of sigma(C1-C2) and sigma(C6-C7) with pi(C=O), on one hand, and those of sigma(C1-C9) and sigma(C7-C8) with pi(C=O), on the other hand, support anti-selectivities for both. This is in full accordance with the experiments. The arguments that are based on electrostatic interactions and electron donation from the ring oxygen do not apply.     

Fenugreek mucilage as a flocculating agent for sewage treatment

The use of fenugreek mucilage, a natural polysaccharide and a direct food additive, as a flocculating agent for removal of suspended and dissolved solids from sewage effluent has been reported. A flocculation study has been done by the standard jar test method. The percent removal of suspended solid (SS) and dissolved solid (TDS) was determined by varying the polymer dose, pH and contact time. X-ray diffraction patterns of the solid waste material of mucilage and flocs (so obtained after treatment) were used to suggest the incorporation of the crystalline waste material in the mucilage. The optimal mucilage concentration was found to be 0.16 mg/l. The suitable pH range for maximum solid removal (SS and TDS) was alkaline and the time required for treatment was 1-3 h.     

Determination of H2 and D2 content in metals and alloys using hot vacuum extraction

A hot vacuum extraction technique for the determination of hydrogen in metal and alloy samples has been standardised. After measuring the total pressure of the evolved gases, individual hydrogen and deuterium intensities are measured using an on-line quadrupole mass spectrometer. Synthetic mixtures of H₂ and D₂, in known concentrations, have been analysed by QMS and an analytical expression correlating the measured [D₂]/[HD] intensity ratio with the mole fraction of deuterium in the synthetic mixture has been arrived at. The precision and accuracy in the measurement of hydrogen is about 10% at 50 ppmw level.     

Synthesis of Pharmaceutical Intermediates by Toluene Benzylation over Heteropoly Acids on Different Support

Selective formation of pharmaceutical intermediates like diphenylmethane, dimethyl- diphenylmethane, benzyl toluene and benzoic acid by liquid phase, toluene benzylation with benzyl chloride as a benzylating agent, was systematically studied over plane clay (K-10, montmorillonite), plane H-Beta, plane MFI structured titanosilicate (TS-1) and heteropoly acids [HPA, namely dodeca-tungstophosphoric acid [H3PO4.12WO3.xH2O] (TPA), dodeca-molybdo phosphoric acid ammonium salt hydrate [H12Mo12N3O40P aq] (DMAA), sodium tungstate hydrated purified [Na12WO4.2H2O] (STH)] supported on clay, H-beta and TS-1. The 20%TPA/Clay, 30%TPA/H-Beta and 30%TPA/TS-l, were observed to be the best catalyst samples over plane clay, plane H-Beta and plane TS-1. The catalyst samples are compared with respect to benzyl chloride conversion and selectivities for diphenylmethane, dimethyl-diphenylmethane, benzyl toluene and benzoic acid. The reaction follows the pseudo-first order rate power law model. The apparent rate constants are calculated and compared with the reported ones.     

Linear and Nonlinear Analyses of the Onset of Buoyancy-Induced Instability in an Unbounded Porous Medium Saturated by Miscible Fluids

This study analyzes the stability of an initially sharp interface between two miscible fluids in a porous medium. Linear stability equations are first derived using the similarity variable of the basic state, and then transformed into a system of ordinary differential equations using a spectral expansion with and without quasi-steady-state approximation (QSSA). These transformed equations are solved using the eigenanalysis and initial value problem approach. The initial growth rate analysis shows that initially the system is unconditionally stable. The stability characteristics obtained under the present QSSA are quantitatively same as those obtained without the QSSA. To support these theoretical results, numerical simulations are conducted using the Fourier-spectral method. The results of theoretical linear stability analyses and the numerical simulations validate to each other.     

Microwave Assisted FriedläNder Condensation Catalyzed by Clay

Clay catalyzed Friedländer condensation of 2-amino arylaldehyde or ketone with carbonyl compounds containing α-methylene group has been achieved in solvent free condition under microwave irradiation to give polycyclic quinoline derivatives.     

Persistent luminescence in Ca8Zn(SiO4)4Cl2:Eu2+

A new persistent, green emission is reported for europium activated Calcium Zinc Chlorosilicate (CZCS). The phosphor was prepared by the solid state reaction and characterized using XRD, PL and TL techniques. The decay was characterized by admixture of two exponential components with decay constants 20.2 and 101 s.