Gas phase reactions induced by OH− ion

The site of proton abstraction by OH^? ion in some 4-substituted-3,5,6-triphenyl-Δ′-cyclohexenes has been established from labelling studies. The further fragmentation mode of (M-H)^? ion depends on its structure and stereochemistry. The $\text{exo}$ and $\text{endo}$ nitro isomers exhibit stereochemical differences in the elimination of HNO₂ while the amino and cyano analogues show stereochemically controlled RDA fragmentation mode.     

Non destructive evaluation of selected polymers by multiple scattering of 662 keV gamma rays

In this paper, multiple scattering of 662 keV gamma photons from targets of Carbon, Aluminium, Iron, Copper and polymers (Polypropylene, Polycarbonate, Polymethyl methacrylate, Polytetraflouroethylene and Polyvinyl chloride) is studied experimentally. Backscattered photons are detected by a NaI(Tl) detector placed at an angle of 90° to the incident beam. The single scattered events are reconstructed analytically to extract multiple scattered photons from the measured spectra. We observe that the number of backscattered photons increases with an increase in target thickness, and saturates at a particular value of the target thickness. This saturation thickness decreases with increasing atomic number of the target. The saturation thickness of the multiple scattering is used to assign effective atomic number of polymers. The experimental results are compared with the results obtained by Monte Carlo N-particle simulation code.     

Gas phase reactions of chloride ion with aryl-substituted nitrocyclohexenes

Chloride ion chemical ionization studies of some aryl-substituted nitrocyclohexenes have demonstrated that benzylic anion formation is favoured in the gas phase. Anchimeric assistance by neighbouring phenyl groups and the effect of olefinic functions have a significant influence on the stability of the carbanions.     

Orientation dependent electrocatalysis using self-assembled molecular films

Surface orientation of self-assembled molecular films of 2,9,6,23-tetraamino cobalt phthalocyanine on gold and silver is shown to determine the nature and the products of the electrocatalytic reduction of oxygen.     

Experimental and simulated validation of the energy dependence of saturation thickness of multiple scattered gamma rays

Saturation thickness for multiple scattering gamma rays from multiple sources has been measured experimentally and simulated using the Monte Carlo N-Particle (MCNP) Code. Experimental measurements were performed using a collimated beam of gamma-rays from ⁵⁷Co, ²⁰³Hg, ¹³³Ba, ²²Na, ¹³⁷Cs, ⁶⁵Zn and ⁶⁰Co sources. The gamma rays were directed at rectangular aluminium targets of varying thickness. A NaI (Tl) scintillation detector placed at a backscattering angle of 180° was used to detect the scattered photons. The measured and calculated saturation thickness increases with increasing energy of incident gamma-rays. Experimental and simulated values are compared and are in good agreement.     

Effect of microwave radiation on hydroxy propyl methyl cellulose polymer films and HPMC/poly(vinylpyrrolidone) polymer blend films using the wide-angle X-ray technique

The changes in the microstructural parameters of microwave-irradiated hydroxy propyl methyl cellulose (HPMC) and HPMC/PVP (poly(vinylpyrrolidone)) blend films have been studied using the Wide Angle X-Ray Scattering Technique (WAXS) method. The crystal imperfection parameters, such as lattice strain (g%), the average number of unit cells ? N ? counted in a direction perpendicular to Bragg's plane (hkl), spacing of (hkl planes dhkl, crystallite size ? Ds ?, distortion width, standard deviation, stacking faults, twin faults, were computed by the whole pattern fitting method. The obtained results were quantified in terms of the radiation dosage given to the samples. X-ray analysis reveals that there is a decrease in the crystallite size with the increase in the radiation dosage. Fourier transform Infra-Red (FTIR) analysis has been also carried out for both the unirradiated and irradiated films to study the effect of microwave radiation on HPMC and HPMC/PVP polymer blend films. The scanning electron microscope study is also carried out to know the surface morphology of these blend films.     

CFD-based simulation and experimental verification of 222Rn distribution in a walk-in type calibration chamber

A walk-in type ²²²Rn calibration chamber (~ 22 m³) is established at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, India which is being used by research groups working on ²²²Rn in India and other countries as well. In recent times, computational fluid dynamics (CFD) technique is opted as an alternative approach for the prediction of ²²²Rn concentration profile in the closed domain. CFD simulations were carried out to study the transient build-up and spatial behavior of ²²²Rn concentration in the calibration chamber. Measurements were performed using active ²²²Rn measuring devices and results of the CFD predictions and direct measurements were compared. A good agreement was observed between the simulated and experimental results with deviation between the two entities being ~ 3% in the case of transient build up and ~ 8% in the case of spatial distribution of ²²²Rn concentration.