GC-MS and GC-FTIR identification of volatile radiolytic products in water-nitrobenzene-carbon tetrachloride two phase systems

Various volatile products formed in the -radiolysis of water-nitrobenzene-carbon tetrachloride two phase systems have been identified using GC-MS and GC-FTIR systems. The conditions for the separation of the products are described in detail. It was found that product formation is dependent on the composition of the systems. In case when the volume ratio of carbon tetrachloride is higher, chlorobenzene appears to be one of the major radiolytic products. This means that substitution of the nitro group by chlorine atom occurs in the presence of water. Substitution of the nitro group and hydrogen atom by chlorine atom and/or HO free radical is also observed, depending on the composition of the mixture. Formation of phenyl isocyanate is proposed to be the result of interaction of dichlorocarbene and nitrobenzene. The mechanism of some main product formation is described briefly.This paper constitutes part of the Ph.D. thesis of M. K. SAHOO and was presented at the 9th Czecho-Slovak Spectroscopic Conference with International Participation, eské Budjovice, C.S.F.R., June 22–24, 1992.     

Infrared and Raman spectroscopies of InP/II–VI core-shell nanoparticles

We use infrared (IR) and Raman spectroscopies to investigate the optically active phonon modes in InP nanoparticles and InP/II–VI core-shell nanoparticles fabricated by similar colloidal chemistry methods. The IR transmission spectra of several InP nanoparticle samples exhibit a common absorption feature, which we assign to the Fröhlich mode. The Raman results for the same samples show transverse and longitudinal optical phonon peaks, and scattering strength in between due to surface optical (SO) modes. Infrared spectra of the InP/ZnSe core-shell nanoparticles () exhibit three absorption features, one due to the InP core, and the others associated with the ZnSe shell layer. Raman measurements (12–292 K) also show three phonon-related peaks, whose intensities vary sharply with temperature. The frequencies of the IR and Raman lines are in approximate accord with dielectric continuum theory.     

Microstructure-controlled enhancement of magnetoimpedance in nanocrystalline FeSiNbBCu alloys

Rapidly solidified amorphous Fe_68.5Si_18.5Nb₃B₉Cu₁ ribbon has been subjected to heat treatment at a temperature of 550 °C for different time periods. All the annealed ribbons show the precipitation of nanocrystalline Fe₃Si phase from the amorphous phase. The estimated crystallite size from X-ray diffraction peak analysis was in the range of 15-25 nm. While the surface studies confirm the presence of a distribution of spherical nanostructures in amorphous matrix. Both magnetoimpedance and longitudinal permeability ratios are found to increase with annealing time, and attain a maximum value for 60 min annealed ribbon and decrease on further increase in the annealing time. The enhanced magnetic properties and magnetoimpedance on suitable heat treatment is attributed to the change of magnetic parameters such as anisotropy and magnetostriction, due to change in microstructure. Analysis of permeability and impedance data taken under similar conditions suggests a strong correlation between them.     

Vitamin B6 cofactor derived chemosensor for the selective colorimetric detection of acetate anions

A novel vitamin B₆ cofactor derived anion sensor L for the selective colorimetric detection of acetate has been developed by the condensation of pyridoxal and 2-aminothiophenol. The sensor L showed a noteworthy change in the visible region of the spectrum and was detected by the ‘naked-eye’ for both acetate and fluoride anions in DMSO but selectively for acetate in DMSO/H₂O (88:12, v/v). The anion recognition ability of L was investigated by spectroscopic (UV–vis and ¹H NMR) and DFT methods.     

Synthesis of Carbazole Alkaloids by Ring‐Closing Metathesis and Ring Rearrangement–Aromatization

Aprocess for the assembly of carbazole alkaloids has been developed on the basis of ring‐closing metathesis (RCM) and ringrearrangement–aromatization (RRA) as the key steps. This method is based on allyl Grignard addition to isatin derivatives to provide smooth access to 2,2‐diallyl 3‐oxindole derivatives through a 1,2‐allyl shift. The diallyl derivatives were used as RCM precursors to afford a novel class of spirocyclopentene‐3‐oxindole derivatives, which underwent a novel RRA reaction to afford carbazole derivatives. The synthetic sequence to carbazoles was shortened by combining the RCM and RRA steps in an orthogonal tandem catalytic process. The utility of this methodology was further demonstrated by the straightforward synthesis of carbazole alkaloids, including amukonal derivative, girinimbilol, heptaphylline, and bis(2‐hydroxy‐3‐methylcarbazole).     

Exact Bianchi type V imperfect fluid solutions

It is shown that it is sufficient to solve a single first order differential equation to determine exact Bianchi type V imperfect fluid solutions of Einstein's field equations. Two exact solutions are presented in this paper. One of these two solutions corresponds to the case when the anisotropic pressure tensor is proportional to the shear tensor. This proportionality, it is shown, is a necessary but not a sufficient condition for the absence of heat flow in a Bianchi type V universe. It is also observed that the presence of heat flow necessarily introduces anisotropy in a Bianchi type V universe.