Stability analysis of the Rayleigh–Bénard convection for a fluid with temperature and pressure dependent viscosity

The classical problem of thermal-convection involving the classical Navier–Stokes fluid with a constant or temperature dependent viscosity, within the context of the Oberbeck–Boussinesq approximation, is one of the most intensely studied problems in fluid mechanics. In this paper, we study thermal-convection in a fluid with a viscosity that depends on both the temperature and pressure, within the context of a generalization of the Oberbeck–Boussinesq approximation. Assuming that the viscosity is an analytic function of the temperature and pressure we study the linear as well as the non-linear stability of the problem of Rayleigh–Bénard convection. We show that the principle of exchange of stability holds and the Rayleigh numbers for the linear and non-linear stability coincide.     

Recognition of aromatic amino acids and proteins with p‐sulfonatocalix[4]arene – A luminescence and theoretical approach

The host–guest interaction of p‐sulfonatocalix[4]arene (p‐SC4) with aromatic amino acids (AAs) and two proteins has been studied using UV–Vis absorption, fluorescence, and theoretical methods. Spectral studies supported by binding constant and calculated binding energy (BE) values show that p‐SC4 binds more strongly with tyrosine compared with other AAs. The application of Bader's theory of atoms in molecule shows the involvement of various types of noncovalent interactions in the formation of the host–guest complexes. Both tyrosine and histidine have strong electrostatic interaction with the sulfonato group and other two AAs have dominant π?π interaction with the aromatic rings of calixarene. In addition, the role of C?H···O, C?H···π and lone pair···π (lp···π) interactions in the stabilization of p‐SC4‐AA complexes has also been realized from the atoms in molecule analysis. The electron density at the bond critical points varies with the calculated BEs and trend in BEs is in good agreement with the experimental binding constant values. The work has been extended to the binding of p‐SC4 with proteins, bovine serum albumin and ovalbumin. Ovalbumin exhibits stronger binding with p‐SC4 than bovine serum albumin. Copyright © 2012 John Wiley & Sons, Ltd.     

Studies on zirconium nitride films deposited by reactive magnetron sputtering

This paper deals with the preparation of Zirconium Nitride films by DC reactive magnetron sputtering. Films were deposited on silicon substrates at room temperature. Nitrogen partial pressure was varied from 4 × 10⁻⁵ to 10 × 10⁻⁵ m bar and the effect on the structural, electrical, optical properties of the films was systematically studied. The films formed at a nitrogen pressure of 6 × 10⁻⁵ mbar showed low electrical resistivity of 1.726 × 10⁻³ Ω.cm. The deposited films were found to be crystalline with refractive index and extinction coefficient 1.95 and 0.4352 respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)