Thermal effects on parallel resonance energy of whistler mode wave

In this short communication, we have evaluated the effect of thermal velocity of the plasma particles on the energy of resonantly interacting energetic electrons with the propagating whistler mode waves as a function of wave frequency and L-value for the normal and disturbed magnetospheric conditions. During the disturbed conditions when the magnetosphere is depleted in electron density, the resonance energy of the electron enhances by an order of magnitude at higher latitudes, whereas the effect is small at low latitudes. An attempt is made to explain the enhanced wave activity observed during magnetic storm periods.     

Electrical conduction in copper vanadate

A.C. and d.c. electrical conductivities, thermoelectric power and dielectric constant of copper vanadate (CuV₂O₆) have been measured in the temperature range 300–1000 K in order to discuss the electrical conduction in the compound. The extrinsic conduction, which takes place below 500 K, has been explained by small polaron hopping mechanism while intrinsic conduction, which takes place above 500 K, has been explained by large polaron band mechanism in view of the values of activation energy and charge carrier mobility in the temperature ranges 300–500 K and 500–1000 K.     

Competitive Self and Induced Aggregation of Calix[4]arene Ethers and Their Interaction with Pinacyanol Chloride and Methylene Blue in Nonaqueous Media

Long chain calix[4]arene ethers have been examined for aggregation in nonaqueous solvents by using UV-vis molecular absorbance spectroscopy. It has been observed that tetraalkylated (alkyl = hexadecyl and octadecyl, respectively) calix[4]arene ethers tend to aggregate in chloroform and tetrahydrofuran, possibly via π–π stacking interactions of the phenyl moieties, and the aggregation process appears to be facilitated by the alkyl chains. The analogous dialkylated compounds do not show any self-aggregation, plausibly due to strong hydrogen bonding between the –OH and the –O– of calix aryl ether which seems to disrupt the aggregation process. Addition of the anionic surfactant sodium dodecylsulfate (SDS) appears to hinder the aggregation process in nonpolar chloroform but the same surfactant facilitates aggregation in the polar tetrahydrofuran. The cationic surfactant (cetyltrimethyl ammonium bromide) and the nonionic surfactant (Brij-35) have no effect on this aggregation process. Unexpectedly, SDS induces aggregation of dialkylated calix[4]arene ethers in chloroform. It has been observed that the aggregated form of the tetraalkylated calix[4]arene ethers tend to increase the dimerization efficiency of cationic dyes (pinacyanol chloride and methylene blue) in chloroform.     

A nonlinear model for footings on granular bed–stone column reinforced earth beds

In the present study, an attempt has been made to model and analyze a combined footing supporting column, which is to be constructed on very soft soil. In view of small bearing capacity and very large deflections, foundations are constructed after improving the original ground. Here, the ground has been improved by providing the stone columns in the soft soil and on top of this improved ground; a granular fill layer has been placed just below the footing. The footing has been modeled as a beam having finite flexural rigidity. Granular fill layer, soft soil and stone columns have been represented by Pasternak shear layer, Kelvin–Voigt body and the Winkler springs, respectively. Nonlinear behavior of these has been considered by means of hyperbolic constitutive relationships. Governing differential equations for response of the system have been derived and presented in non-dimensional form. These equations have been solved using appropriate boundary conditions by means of an iterative Gauss Elimination technique.     

Ruthenium(III)-catalyzed and uncatalyzed kinetic studies on the oxidation of sulfanilic acid by chloramine-T in perchloric acid medium: a mechanistic approach

The kinetics of the oxidation of sulfanilic acid (SAA) by sodium N-chloro-p-toluenesulfonamide (CAT) in the presence and absence of ruthenium(III) chloride have been investigated at 303 K in perchloric acid medium. The reaction shows a first-order dependence on [CAT]_o and a non-linear dependence on both [SAA]_o and [HClO₄] for both the ruthenium(III)-catalyzed and uncatalyzed reactions. The order with respect to [Ru^III] is unity. The effects of added p-toluenesulfonamide, halide, ionic strength, and dielectric constant have been studied. Activation parameters have been evaluated. The rate of the reaction increases in the D₂O medium. The stoichiometry of the reaction was found to be 1:1 and the oxidation product of SAA was identified as N-hydroxyaminobenzene-4-sulfonic acid. The ruthenium(III)-catalyzed reactions are about four-fold faster than the uncatalyzed reactions. The protonated conjugate acid (CH₃C₆H₄SO₂NH₂Cl⁺) is postulated as the reactive oxidizing species in both the cases.     

Optically responsive switchable ionic liquid for internally-referenced fluorescence monitoring and visual determination of carbon dioxide

Modulation in the local viscosity and polarity within a reversible carbamate ionic liquid system forms the basis for the fluorescence excimer-based estimation of CO(2). Inherently self-referencing, the photonic response to CO(2) recognition shows excellent sensitivity and complete reversibility, making possible a striking visual display discernible to the naked eye.     

Dynamic viscosity versus probe-reported microviscosity of aqueous mixtures of poly(ethylene glycol)

Correlation between the dynamic viscosity (η) and the microviscosity of a hybrid green medium constituted of water and poly(ethylene glycol) (PEG) of average molar mass (200, 400, and 600) g · mol^?1, respectively, is explored over the temperatures range (10 to 90) °C across the complete composition regime. The microviscosity is obtained using a fluorescence probe 1,3-bis-(1-pyrenyl)propane (BPP), which is manifested through the ratio of the monomer-to-intramolecular excimer intensities (I_M/I_E). Aqueous PEG mixtures are observed to behave similar to Newtonian fluids as the temperature dependence of dynamic viscosity follows Arrhenius-type behavior. Surprisingly, a simple and convenient linear dependence of ln η with wt% PEG of the mixture is established. The BPP I_M/I_E is observed, in general, to increase with the bulk dynamic viscosity of the mixture having >10 wt% PEG suggesting a good correlation between the bulk dynamic viscosity and BPP-reported microviscosity when the viscosity of the aqueous PEG mixture is relatively high.