Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
19 results
Search Results
Item Molecular interactions in glycylglycine-mncl2 aqueous solutions at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) k(2009) Santosh, M.S.; Bhat, D.K.; Bhat, A.S.The viscosities, ultrasonic velocities, densities, and refractive indices of glycylglycine and MnCl2in water have been studied at different temperatures and concentrations. Excess thermodynamic parameters such as adiabatic compressibility (?ad), apparent molar volume (?V), apparent molar compressibility (?K),intermolecular free length (Lf), specific acoustic impedance (Z), relative association (RA), and salvation number (Sn) have been calculated. The variations in apparent molar volume were confirmed by Scaled particle theory, and the changes in apparent molar compressibilities were interpreted using the Kirkwood model. The variations in apparent molar volumes were fitted with Masson's equation. The viscosity data have been fitted using the Jones-Dole empirical equation. The molecular relaxation of MnCl2and glycylglycine in water gives an idea about solute-solute interactions. The interactions also suggest the formation of H-bonding in the system. The tructure forming tendency of the solute has also been indicated by the solvation number. Copyright& copy; 2009 American Chemical Society.Item Electrical and magnetic properties of chitosan-magnetite nanocomposites(2010) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.Magnetite powders in nanometer size have been synthesized by the hydrothermal process. Various magnetic films of chitosan and the synthesized magnetite nanopowders containing different concentrations of the latter were prepared by ultrasonication route. The X-ray diffraction (XRD) studies and the transmission electron microscopy (TEM) images showed that the synthesized magnetite particles had 80 nm dimensions. The band gap of the composites was evaluated using the UV-visible Spectroscopy. The influence of magnetite content on the magnetic properties of the composite showed a decrease in the saturation magnetization with the decrease in the magnetic content. The effect of magnetite content on the dielectric properties of the polymer film at different frequencies from 0.01 to 105 Hz was studied using an electrochemical impedance spectroscopy. The possible mechanism for the observed electrical properties of the composite films was discussed. © 2010 Elsevier B.V. All rights reserved.Item Ultrasonic velocities, densities, and viscosities of glycylglycine and CoCl2 in aqueous and aqueous ethanol systems at different temperatures(2010) Santosh, M.S.; Bhat, D.K.; Bhatt, A.S.Ultrasonic velocity (u), density (?), and viscosity (?) have been measured for glycylglycine and CoCl2 in aqueous and aqueous ethanol systems at T = (288.15 to 318.15) K. Using the experimental values, the adiabatic compressibility (?s), molar hydration number (nH), apparent molar compressibility (KS?), apparent molar volume (V?), limiting apparent molar compressibility (KS ?{symbol}0), limiting apparent molar volume (V?{symbol}0), their constants (SK, SV), viscosity coefficients of A and B parameters of Jones-Dole equation, relative viscosity (?r), and excess Gibbs free energy of activation (? G* E) were calculated and the results of all these parameters have been discussed in terms of solute-solvent and solute-solute interactions. © 2010 Elsevier Ltd. All rights reserved.Item Physico-chemical, acoustic and excess properties of glycylglycine-MnCl2 in aqueous ethanol mixtures at different temperatures(2010) Santosh, M.S.; Bhatt, A.S.; Bhat, D.K.Volumetric, acoustic, refractometric, excess and deviation properties of glycylglycine-MnCl2 in aqueous ethanol mixtures have been reported at T = (288.15 to 318.15) K. Redlich-Kister equation was used to fit the derivate properties. The experimental data of the constituent binaries were analyzed to discuss the nature and strengths of intermolecular interactions. The interdependence of Lf and u has been evolved from Eyring and Kincaid model. The variations in specific acoustic impedance revealed that hydrogen bonding was predominant in the studied binary mixtures. Solvation number indicated structure-breaking tendency of the solute and weakening of local solvent structure. © 2010 Elsevier B.V. All rights reserved.Item Volumetric, refractometric, and excess properties of glycylglycine in aqueous FeCl2 solution at temperatures T = (288.15 to 318.15) K(2010) Santosh, M.S.; Bhat, D.K.; Bhatt, A.S.Densities and refractive indices have been measured for glycylglycine in aqueous FeCl2 solution as a function of concentration at T = (288.15 to 318.15) K. The apparent molar volumes and partial molar volumes were obtained from these density data. The limited partial molar expansivities have been calculated from the temperature dependence of the partial molar volume. The molar refractions were calculated from the experimental refractive index values for the studied mixture. The excess volumes and molar refractions were also calculated. The results are discussed in terms of molecular interactions. © 2010 American Chemical Society.Item Volumetric and ultrasonic investigation of glycylglycine in aqueous FeCl3 solutions(2010) Santosh, M.S.; Bhat, D.K.; Bhat, A.S.Viscosity, ultrasonic velocity and density measurements have been carried out for glycylglycine in aqueous FeCl3 solution as a function of molality at T=288.15 K, 298.15 K and 308.15 K. The experimental data have been used to derive properties such as isentropic compressibility (? S ), change in isentropic compressibility (?? S ), relative change in isentropic compressibility (?? S /? 0), apparent molar compressibility, volume and their limiting apparent molar quantities along with the constants S K, S V and viscosity B-coefficient. The obtained thermodynamic properties have been discussed in terms of molecular interactions. © 2010 Springer Science+Business Media, LLC.Item Excess molar volumes, viscosity deviations and isentropic compressibility changes in glycylglycine-NiCl2 aqueous ethanol mixtures(2010) Santosh, M.S.; Bhat, D.K.The densities, viscosities and ultrasonic velocities for glycylglycine-NiCl2 in aqueous ethanol mixtures have been studied in the temperature range 288.15-318.15K. The excess molar volumes, viscosity deviations and changes in isentropic compressibility for the binary mixtures have been calculated and discussed in terms of hydrogen bonding and structure-breaking effect. The computed results are fitted to the Redlich-Kister polynomial. The results clearly indicate that there is a strong association in the mixtures studied. © 2010 Elsevier B.V.Item Refractive indices and isentropic compressibilities of glycylglycine- FeCl2 in aqueous ethanol mixtures(2010) Santosh, M.S.; Bhat, D.K.The density and refractive index studies have been carried out for glycylglycine-FeCl2 in aqueous ethanol mixtures at four different temperatures in the range T = (288.15 to 318.15) K. A comparative study of the refractive indices obtained experimentally and those calculated by means of Gladstone-Dale and Lorentz-Lorenz relation has been made. Among them, the Gladstone-Dale equation afforded similar values to those obtained experimentally. Isentropic compressibilities, -S, and excess molar isentropic compressibilities, KS,mE, were estimated using the Kirkwood model. Using the Redlich-Kister type equations, excess partial molar isentropic compressibilities, KS,iE, were also obtained. The observed negative values of KS,2E in the water-rich region are due to the structural disorderliness. As infinitely dilute water is hydrogen-bonded to ethanol and glycylglycine, the variation of strength of interaction is not sensed by KS,1E,?. © 2010 American Chemical Society.Item Acoustical and compressibility parameters of glycylglycine-FeCl3 in aqueous ethanol mixture at T = (293.15, 303.15, and 313.15) K(2010) Santosh, M.S.; Bhat, D.K.Ultrasonic velocity measurement is a reliable procedure that allows quick and easy determination of solvent concentrations in mixtures. This paper presents data of ultrasonic velocities and isentropic compressibilities of (glycylglcyine-FeCl3) in aqueous ethanol mixture at T = (293.15, 303.15, and 313.15) K. Various acoustical parameters were calculated, because of their importance in the study of specific molecular interactions. A less-compressible phase of the fluid and a closer packing of molecules is observed with changes in the intermolecular free length. Quantitative investigation suggests that the mixing of ethanol with an aqueous glycylglycine-FeCl3 solution causes the rupture of hydrogen bonds, with increasing S and Lf values (where the former represents the change in isentropic compressibility and the latter represents the intermolecular free length). Theoretically computed values of isentropic compressibility in the studied mixture using different models indicate the superiority of the very complex procedure. © 2010 American Chemical Society.Item Molar volume, compressibility and excess properties of glycylglycine in aqueous NiCl2 solutions(2010) Santosh, M.S.; Bhat, D.K.Volumetric and acoustical parameters are reported for glycylglycine in aqueous NiCl2 solution at T=(288.15-318.15)K. The apparent molar volumes and isentropic compressibilities were calculated from the experimental data of ultrasonic velocity and density. Together with these, excess isentropic compressibility (?SE), excess free volume (VfE), excess intermolecular free length (LfE) and deviations of ultrasonic velocity (?u) were obtained. The results are interpreted in terms of molecular interactions. The results show that the cation and anion play a significant role in influencing the behavior of glycylglycine in aqueous solutions. These effects were also attributed to the doubly charged behavior of glycylglycine and to the formation of physically bonded ion-pairs between charged groups of glycylglycine and cation and anion of the electrolyte. © 2010 Elsevier B.V.