Dielectric constants,molar polarizations,and refractive indices for 2-butoxyethanol + hexane and +heptane at 30° and 40°C

Static dielectric constants and refractive indices of 2-butoxyethanol-n-hexane and-n-heptane mixtures were measured at 30 and 40°C and the various dielectric excess functionsviz. dielectric constants, molar polarizations, and orientation polarizations were evaluated. The excess dielectric constants and molar polarizations were found to be unsymmetrical and negative over the entire range of mole fraction. The trend in the variation of excess orientation polarization has shown three characteristic regions. The excess functions were smoothed through a variable degree polynomial. The results show the dominance of dipole-dipole interactions in the butoxyethanol deficient regions and weak specific interactions with unlike alkane molecules at higher butoxyethanol mole fractions.     

A single domain grain model for the low-field constricted hysteresis loops of some basaltic rocks

Basaltic rocks contain magnetic grains oriented randomly in a nonmagnetic matrix. Experimental studies of low-field hysteresis of such rocks have shown partially and totally constricted hysteresis loops for some specimens. A possible origin of these constricted loops on the basis of interacting single domain behaviour is suggested.     

Indirect electronic transitions in alkali halate crystals-II (sodium bromate and iodate) crystals

In the case of NaClO₃ and KClO₃ crystals, analysis of the long wavelength tail of their fundamental absorption revealed the active participation of the internal vibrations of the chlorate ion (Part I). In order to test the validity of the above interpretation the absorption spectra of two more halates with different anions namely sodium bromate and sodium iodate are analysed in a manner similar to that given in Part I. It is found that the principle internal vibrations of bromate and iodate ions are involved in the indirect transitions. The variation of indirect band gap with temperature is found to be ?2·5 × 10^?4 eV/K and ?2·9 × 10^?4 eV/K for sodium bromate and sodium iodate respectively.     

Biocompatibility of gold nanoparticles and their endocytotic fate inside the cellular compartment: a microscopic overview

Macrophages are one of the principal immune effector cells that play essential roles as secretory, phagocytic, and antigen-presenting cells in the immune system. In this study, we address the issue of cytotoxicity and immunogenic effects of gold nanoparticles on RAW264.7 macrophage cells. The cytotoxicity of gold nanoparticles has been correlated with a detailed study of their endocytotic uptake using various microscopy tools such as atomic force microscopy (AFM), confocal-laser-scanning microscopy (CFLSM), and transmission electron microscopy (TEM). Our findings suggest that Au(0) nanoparticles are not cytotoxic, reduce the production of reactive oxygen and nitrite species, and do not elicit secretion of proinflammatory cytokines TNF-alpha and IL1-beta, making them suitable candidates for nanomedicine. AFM measurements suggest that gold nanoparticles are internalized inside the cell via a mechanism involving pinocytosis, while CFLSM and TEM studies indicate their internalization in lysosomal bodies arranged in perinuclear fashion. Our studies thus underline the noncytotoxic, nonimmunogenic, and biocompatible properties of gold nanoparticles with the potential for application in nanoimmunology, nanomedicine, and nanobiotechnology.     

Competitive Diels-Alder reactions: cyclopentadiene and phospholes with butadiene

Diene-dienophile competing Diels-Alder reaction pathways of cyclopentadiene, 1H-, 2H- and 3H-phospholes with butadiene were explored at the B3LYP level using 6-31G(d) and 6-311+G(d,p) basis sets, and at the CCSD(T)/6-31G(d)//B3LYP/6-31G(d) level. Activation barriers show that cyclopentadiene favors a diene rather than a dienophile conformation. Pathways 1 and 2 (A and B) corresponding to butadiene as the diene and dienophile are predicted to be highly competitive in the case of 1H-phosphole. Secondary orbital interactions and the preferable bispericyclic nature of transition states are responsible for the stability of endo transition states. The study indicates that some of the transition states are bispericyclic and most of them are highly asynchronous. The reactions require a lower activation energy when the conversion of weak C=P to C-P occurs in the case of 2H- and 3H-phospholes. The high stability of the products resulting via path 1 can be attributed to the less strain in the bicyclo[4.3.0]nonadiene skeleton compared to the norbornene derivatives obtained from path 2. Activation and reaction energy values for these Diels-Alder reaction pathways are compared with the values reported for the [4+2] cyclodimerizations of each of the reactants to examine the likelihood of cyclodimerizations along these pathways.     

Some neutral current effects in an SU(3)×U(1) gauge model

The anomalous magnetic moment of muon is calculated in anSU(3)×U(1) gauge model proposed by Gupta and Mani. We find the contribution due to the intermediate gauge bosons to be of the same order of magnitude as in Weinberg. Salam model. The deep-inelastic structure functions are also analysed in the same model and inequalities for the structure functions are obtained in the light-cone algebra approach.     

Impurity mediated mechanism of photorefractive effect in BaTiO3: A combination of sangster and piezoelectric effects

An impurity mediated mechanism of photorefractive effect in BaTiO₃ is proposed. The photoinduced changes in the relative concentration of Fe³⁺ in BaTiO₃ results in an electro-optic coupling through a combination of the Sangster and piezoelectric effects. This is based on the examination of the extensive results on the EPR of Fe³⁺ in the BaTiO₃ lattice. This model explains the improved photorefractive behavior of BaTiO₃ on doping with Co²⁺.     

Radiation stabilization of U5+ in CaO matrix and its thermal stability: Electron paramagnetic resonance and thermally stimulated luminescence studies

Electron paramagnetic resonance (EPR) evidence is presented for the radiation stabilization of pentavalent uranium in CaO matrix. From the theoretical predictions ofg value for U⁵⁺ in axial symmetries, it was concluded that U⁵⁺ at Ca²⁺ site is associated with a second neighbour charge compensating Ca²⁺ vacancy. EPR measurements also revealed the presence of Mn²⁺, Mn⁴⁺ and Cu²⁺ impurities in the samples. The thermal stability of U⁵⁺ was investigated using EPR and thermally stimulated luminescence (TSL) techniques. The TSL and EPR studies on gamma irradiated uranium doped calcium oxide samples had shown that the intense glow peak at 540 K is associated with the reduction in the intensity of EPR signal of U⁵⁺ ion around this temperature. This peak is associated with the process U⁵⁺+hole→U^6+*→U⁶⁺+hv. The activation energy for this process was determined to be 1.4eV.