Thermal behaviour of chromium (III) perchlorate hexahydrate

Thermal behaviour of intimate mixtures of chromium(III) oxide and lithium¹, potassium², rubidium³, cesium³ and thallium(I)⁴ perchlorates revealed that chromium(III) oxide not only catalyses the decomposition by lowering the decomposition temperatures of the pure metal perchlorates but also chemically interacts resulting in the formation of metal dichromate. The oxidation of chromium(III) into the hexavalent state is attributed to the abstraction of oxygen from the perchlorate moiety during the decomposition. In this context, it was thought interesting to study the thermal behaviour of chromium(III) perchlorate and to identify the decomposition products in order to find out whether chromium(III) is oxidized into chromium(VI) by the perchlorate group. Except for a report⁵ on the preparation of chromium(III) perchlorate with different molecules of water of hydration no work seems to have been carried out on the thermal decomposition of this compound. In the present study, the decomposition characteristics are followed by TG and DTA techniques and the decomposition products have been examined by chemical analysis, X-ray powder diffraction patterns and infrared spectral measurements.     

Preparation and Characterisation of a New Thallium(I) Uranate(VI), Tl4UO5

A new thallium(I) uranate(VI) of composition Tl₄UO₅ was isolated and characterised by X-ray, i. r. and chemical analyses. The compound dissociated into thallium(I) oxide and Tl₂UO₄ on heating to 230°C and its subsequent thermal behaviour depended on the volatilisation and oxidation characteristics of the thallium(I) oxide released.     

Development and validation of a HPLC method for quantification of rivastigmine in rat urine and identification of a novel metabolite in urine by LC‐MS/MS

A sensitive, specific and accurate HPLC method for the quantification of rivastigmine (RSM) in rat urine was developed and validated. The method involves the simple liquid–liquid extraction of RSM and pyridostigmine as an internal standard (IS) from rat urine with tertiary methyl butyl ether. The chromatographic separation of RSM and IS was achieved with 20 mm ammonium acetate buffer (pH 6.5) and acetonitrile (65:35, v/v) delivered at flow‐rate of 1 mL/min on a Kromasil KR‐100. The method was in linear range from 50 to 5000 ng/mL. The validation was done as per FDA guidelines and the results met the acceptance criteria. The method was successfully applied for the quantification of RSM in rat urine. Besides method validation, we have identified two metabolites of RSM in urine. Both the metabolites were characterized by HPLC‐PDA and LC‐MS/MS and it was found that one metabolite is novel. Copyright © 2010 John Wiley & Sons, Ltd.     

Spectral and electrochemical studies on oxoisothiocyanatobis(pyrrolidinyldithiocarbamato)molybdenum(V)

The complex, oxoisothiocyanatobis(pyrrolidinyldithiocarbamato)molybdenum(V), MoO(NCS) (pyrroldtc)₂ was prepared. The IR spectra of the complex suggest that the thiocyanate group is attached through nitrogen and the presence of MoO³⁺ moiety. The voltammograms of the complex in acetonitrile exhibited a pronounced cathodic wave at ?0.23 V vs S.C.E. which was attributed to Mo(V)/Mo(IV) couple. The magnetic, epr and electrochemical studies indicate that the compound is mononuclear and molybdenum is in +5 oxidation state.     

Oxidimetric determination of sulphides

Hypoiodite oxidises sulphides much more rapidly than does iodate under comparable experimental conditions. A procedure is reported for the determination of soluble and insoluble sulphides by oxidation to sulphate with hypoiodite. This is an improvement over Bethge's iodate method.     

Interface balance laws,phase growth and nucleation conditions for multiphase solids with inhomogeneous surface stress

In this paper, the thermodynamic configurational force associated with a moving interface is used to derive the conditions for phase growth and nucleation in bodies with multiple diffusing species and arbitrary surface stress at the phase interface. First, the mass, momentum and energy balances are derived on the evolving phase interface. The thermodynamic conditions that result from free energy inequality at the interface are derived leading to the analytical form of the configurational force for bodies subject to mechanical loads, heat and multiple diffusing species. The derived second law condition naturally extends the Eshelby energy–momentum tensor to include species diffusion terms. The above second law restriction is then used to derive the condition for the growth of new phases in a body undergoing finite deformation subject to inhomogeneous as well as anisotropic interface stress, and multiple diffusing species. The growth conditions are derived in both current and reference configurations. The statistical temperature-dependent growth velocity is next derived using the Boltzmann distribution. The derived finite deformation form of growth requirement is simplified to obtain the small deformation diffusive void growth condition. Next, a general, finite deformation, arbitrary surface stress form of phase nucleation condition is derived by considering uncertainty in growth of a small nucleus. The probability of nucleation is shown to naturally depend on a theoretical estimate of critical volumetric energy density, which is directly related to the surface stress. The classical nucleation theory is shown to result from a simplified special case of the general criterion. As an application of the developed theory, the classical Blech electromigration experiment is simulated to estimate the critical energy density corresponding to the onset of electromigration voids at Al–TiN interface.     

Zygo interferometer for measuring refractive index of liquids and its application for heavy water analysis

The Zygo interferometer for measuring refractive index of liquids such as heavy water is presented. The accuracy of measurement in the refractive index of liquids is found to be ±0.0002 in the Zygo interferometer. An application of Zygo interferometer for heavy water analysis is also presented. The interferometer is found to be useful for determining the percentage purity of heavy water with an accuracy of ±5% in the purity range of 0–100%.