Determination of molybdenum and tungsten at trace levels in rocks and minerals by solvent extraction and X-ray fluorescence spectrometry

Separation by solvent extraction followed by X-ray fluorescence spectrometry has been used for determination of molybdenum and tungsten in rocks and minerals. Samples are decomposed either by heating with a mixture of hydrofluoric acid and perchloric acid or by fusion with potassium pyrosulphate, followed by extraction of molybdenum and tungsten with N-benzoylphenylhydroxylamine in toluene from 4-5M sulphuric acid medium. The extract is collected on a mass of cellulose powder, which is dried in vacuum, mixed thoroughly and pressed into a disc for XRF measurements. The method is free from all matrix effects and needs no mathematical corrections for interelement effects. The method is suitable for determination of molybdenum and tungsten in geological materials down to ppm levels, with reasonable precision and accuracy.     

Dynamic NMR investigation of two new interconvertible diasteriomeric epimers of natural 2-benzyl-2-hydroxybenzofuranone derivative from Pterocarpus marsupium

The first example of a pair of interconvertible diastereomeric epimers 2α/2β-hydroxy-2-p-hydroxybenzyl-3(2H)-benzofuranone-7-C-β-d-glucopyranoside isolated from the heartwood of Pterocarpus marsupium is reported. The predominance of 1a over 1b was supported by dynamic exchange rates and activation parameters obtained from NMR studies. The mechanism of this unique phenomenon is thought to be operative by the formation of diketone as suggested by deuterium exchange.     

Biophysical and biochemical investigation on the binding of a manganese–cyanonitrosyl complex with DNA

The interaction of a cyanonitrosyl–manganate complex with DNA has been studied by u.v.–vis spectroscopy, circular dichroism, fluorescence and gel electrophoresis techniques. As the DNA 260 nm band remained insensitive to interaction, the interaction ratio was determined by monitoring the CN⁻→ Mn LMCT band observed at 222 nm, and the interaction ratio was found to be in the complex (D): DNA (P)=1:0.30 from the spectrophotometric titration. The above-mentioned physical measurements indicate that the binding mode is not intercalative and the cyanonitrosyl system is a groove binder.     

Radiation detection by using superheated droplets

The superheated emulsion, a radiation detector consisting of superheated droplets dispersed in a gel or a solid matrix, has been in use for some time now. It was initially designed to detect neutrons but also has been modified to detect energetic photons and heavy ions. It has been primarily used as a neutron dosimeter, but has also been used to obtain the energy spectrum for neutrons from Am–Be. The general features of the superheated emulsion detector along with newer analytic methods to obtain more precise results using it as an active device will be presented.     

Reactions of 2,2,2-trifluorodiazoethane with carbon-nitrogen and carbon-oxygen multiple bonds

2,2,2-Trifluorodiazoethane reacts with trifluoroacetonitrile in the dark at room temperature to give a 2-(2,2,2-trifluoroethyl)-4, 5-bis(trifluoromethyl)triazole, the 1,2,3-triazole structure being preferred to the 1,2,4-isomer on the basis of the ¹⁹F n.m.r. spectrum. The diazoethane reacts more slowly with trichloroacetonitrile, again forming the N-alkylated triazole even in the presence of an excess of the nitrile. No identifiable adduct resulted with acetonitrile. Hexafluoroisopropyl-ideneimine is first N-alkylated and then undergoes addition to form 1-(2,2,2-trifluoro-1-trifluoromethyl)ethyl-4,5-bis(trifluoromethyl)-?-1,2,3-triazoline, but N-methylhexafluoroisopropylideneimine failed to react. Trifluoroacetaldehyde and trichloroacetaldehyde give mixtures of the ketone (formed by insertion of the CF₃CH group into the aldehyde CH bond) and the $\text{cis}$- and $\text{trans}$-oxirans, apparently $\text{via}$ a β-hydroxydiazoalkane.     

Geometrical aspects of magnetic monopoles

The possible topological structures of elementary particles have been investigated to explore the possibility of the existence of magnetic monopoles. It is pointed out that when an elementary charged particle is depicted as an extended body such that the orientation of the internal space (internal helicity) defines the fermion number, the global conservation of this does not allow the existence of a magnetic monopole. Again it is argued that when anisotropy is introduced in the microlocal space-time depicting the internal space of hadrons, this gives rise to the internal symmetry algebra and no non-Abelian gauge fields and Higgs scalars are necessary to have a grand unified scheme of interactions. This avoids theSU ₂ and GUT monopoles. Besides, in this formalism, baryon number corresponds to the orientation or internal helicity of the composite system and the global conservation of this quantum number is found to be a consequence of Lorentz invariance. This forbids the existence of any sort of cosmological monopole in this Lorentz invariant Universe.     

Fenitrothion-induced changes in lipids of rats

The dose-dependent lipid accumulation caused by fenitrothion administration is associated with alteration of the ratio of various components of phospholipids and neutral lipids in various organs of rats up to 48 h. The concentration of triacylglycerol, phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl glycerol increased in liver, kidney and brain in treated rats whereas phosphatidyl serine was greatly reduced. High-performance liquid chromatography and gas-liquid chromatography were used for quantiative analysis of phospholipids and triacylglycerol. The changes in relative composition of various lipids by fenitrothion administration may lead to malfunctioning and alteration of biological properties.     

Polyaniline supported palladium catalyzed Suzuki-Miyaura cross-coupling of bromo- and chloroarenes in water

Polyaniline supported palladium catalysts were prepared from different palladium precursors and all the catalysts are well characterized using ICP-AES, FTIR, TGA-DTA, SEM-EDX and XPS analysis. All the catalysts were tested for Suzuki-Miyaura coupling of bromo- and chloroarenes in water and the catalyst prepared from PdCl₂ precursor was found to be the most effective catalyst. The catalyst can easily be recovered by simple filtration and reused for several cycles with almost consistent activity.