http://nopr.niscpr.res.in/handle/123456789/39840 2026-10-09T06:09:48Z http://nopr.niscpr.res.in/handle/123456789/39986 Title: The dielectric polarisation and apparent molar volume studies of ethanol, <i>tert</i>-butanol and tetrabutylammonium bromide in nonpolar solvents Authors: Patil, K J; Bhand, M D; Mhetre, B S Abstract: Dielectric constant (e), density <i>(d) </i> and refractive index <i>(n) </i> measurements at 25°C for solutions of ethanol, <i>tert-</i>butanolin carbontetrachloride and of tetrabutylammonium bromide in benzene and carbontetrachloride (1 to 30 x 10^-3 weight fraction of solute) are reported. Solute polarisations (P₂) and apparent molar volumes (φ_v) of the solute have been evaluated as a function of solute weight fraction. The variation of these parameters with concentration is explained in the case of ethanol and <i>tert</i>-butanol solutes in terms of association in the forms of dimer and higher aggregate formation in solution. The infinite dilution properties enable to calculate the dipole moments and partial volumes of the monomer in the case of alcohols. The measurements for tetrabutylammonium bromide in C₆H₆ and CCl₄ show that this solute molecule exhibits highly nonlinear behaviour in limiting concentration range. The results are explained on the basis of micellization, triple ion and ion pair formation in the studied concentration range. The values of limiting apparent volume of the salt in nonaqueous solvents are also compared with similar data reported for aqueous solutions. Page(s): 165-170 1995-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39984 Title: Near-infrared spectroscopic studies of aqueous electrolyte solutions^† Authors: Patil, K J; Patil, P R Abstract: The near-infrared difference spectra of aqueous solutions of NaCl, KCI and Bu₄NBr have been reported in the concentration range of 0.5 to 3.0 <i>m </i> at 22 ± 1°C. The combination band (n₁ + n₂ + <i>n </i>₃) of water has been mainly studied. Some measurements for the first overtone of - CH band in Bu₄NBr solutions have also been presented. The combination water band is subjected to analysis by applying McCabe and Fisher method to yield the hydration spectra which can be resolved into two components for all the salt solutions studied except for Bu₄NBr solutions. The low frequency component centered at 1200 nm is assigned to anion-water hydrogen bond, while the high frequency band at 1160 nm is assigned to non-hydrogen bonded water molecules in the hydration sphere of the cation. The hydration numbers for the salts have been calculated and compared to those obtained from other techniques. The results are explained in terms of ion-solvent interactions. The case of Bu₄NBr appears to be anomalous and has been explained on the basis of its peculiar structure stabilization properties in aqueous solutions. Page(s): 171-175 1995-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39982 Title: Chemical processing of sodium doped hexagonal Sr-ferrite: Part IV-Microstructural and magnetic studies^† Authors: Bagul, A G; Date, S K; Deshpande, C E; Minoura, H Abstract: The effects of sodium ions added before and after calcination of coprecipitated hexagonal Sr-ferrite are investigated. The values of important performance parameters, namely, energy product (BH)_max, remanence (B_r) and coercivity (_bH_c, _iH_c) are significantly improved when sodium ions are added after calcination The better magnetic properties are assigned to the improved microscopic (structural and chemical)homogeneity and sintered density. Page(s): 176-180 1995-03-01T00:00:00Z http://nopr.niscpr.res.in/handle/123456789/39980 Title: Micellar effects on the reduction of <i>p</i>-nitroso-N,N-dimethylaniline by sulphite ions Authors: Sarada, N C; Reddy, I Ajit Kumar Abstract: Micellar effects on the rate of reduction of <i>p</i>-nitroso-N,N-dimethylaniline by sulphite ions in a buffer medium of <i>p</i>H 6.5 have been investigated. A nonionic surfactant, polyoxyethylene (23) dodecanol (Brij-35, 1 x 10^-² <i>M</i>), catalyses the reaction and increases the rate by 34 times whereas the same concentration of a cationic surfactant cetyltrimethylammonium bromide (CTAB) catalyses the reduction by 11 times. Anionic surfactant sodium dodecyl sulphate (SDS) has little effect on the reduction rate. Catalytic effects have been attributed to the hydrophobic and electrostatic interactions between the substrate, reductant and micelles. Micelle-substrate binding constants have been found to be 470 and 759 <i>M^-1 </i> for CTAB and Brij-35 catalysed reactions respectively. Influence of micelles on the activation parameters of the reaction has been discussed. Page(s): 181-185 1995-03-01T00:00:00Z