Browsing by Author "Santosh, M.S."

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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.
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.
Application of Prigogine-Flory-Patterson theory to volumetric, ultrasonic, and compressibility parameters of (glycylglycine + CuCl2) in aqueous ethanol mixtures
(2011) Santosh, M.S.; Krishna, Bhat, D.
The molar volume and compressibility of (glycylglycine + CuCl2) in aqueous ethanol mixtures have been obtained at four different temperatures T = (288.15 to 318.15) K from ultrasonic velocity and density measurements. Excess molar volumes were found to be negative throughout the composition range indicating notable changes in hydrogen bonding and electrostatic interactions. Using the Prigogine-Flory-Patterson theory, quantitative estimation of different contributions, i.e. interactional, free volume, and P effect to VE have been obtained. The molar isentropic compressibility has been computed using the ultrasonic velocity and excess volume data. The trends in ?SE are affected by the size of the molecule leading to negative contributions. In order to compare the theoretical values of ultrasonic velocity, the equations of Nomoto and Junjie were used and found to predict the experimental data very well. 2011 Elsevier Ltd. All rights reserved.
Application of Prigogine-Flory-Patterson theory to volumetric, ultrasonic, and compressibility parameters of (glycylglycine + CuCl2) in aqueous ethanol mixtures
(2011) Santosh, M.S.; Bhat, D.K.
The molar volume and compressibility of (glycylglycine + CuCl2) in aqueous ethanol mixtures have been obtained at four different temperatures T = (288.15 to 318.15) K from ultrasonic velocity and density measurements. Excess molar volumes were found to be negative throughout the composition range indicating notable changes in hydrogen bonding and electrostatic interactions. Using the Prigogine-Flory-Patterson theory, quantitative estimation of different contributions, i.e. interactional, free volume, and P effect to VE have been obtained. The molar isentropic compressibility has been computed using the ultrasonic velocity and excess volume data. The trends in ?SE are affected by the size of the molecule leading to negative contributions. In order to compare the theoretical values of ultrasonic velocity, the equations of Nomoto and Junjie were used and found to predict the experimental data very well. © 2011 Elsevier Ltd. All rights reserved.
Chitosan/NiO nanocomposites: A potential new dielectric material
(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.; Tai, C.-W.
The study of electrochemical behavior of organic-inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 10-2 S cm -1 is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol-1. 2011 The Royal Society of Chemistry.
Chitosan/NiO nanocomposites: A potential new dielectric material
(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.; Tai, C.-W.
The study of electrochemical behavior of organic-inorganic nanocomposite materials remains a major challenge for application in energy storage devices. Here, new composite materials of chitosan and NiO nanoparticles have been fabricated. The NiO nanoparticles are well characterized by infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The electrical properties of the films are studied by impedance spectroscopy at different temperatures; and thereby permittivity, electric modulus and conductivity data are obtained. By studying the variations in permittivity and electric modulus spectra with respect to applied frequency signal and temperature, the ionic conductivity of the material is investigated. The Correlated Barrier Hopping model is employed to understand the conduction mechanism. An admirable conductivity of 1.4 × 10-2 S cm -1 is obtained for a nanocomposite with 4 wt% NiO content. The activation energies of the composite films decrease with increase in NiO content, from 16.5 to 4.8 kJ mol-1. © 2011 The Royal Society of Chemistry.
Crystallinity, conductivity, and magnetic properties of PVDF-Fe 3O4 composite films
(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.
The formation of Fe3O4 nanoparticles by hydrothermal process has been studied. X-ray Diffraction measurements were carried out to distinguish between the phases formed during the synthesis. Using the synthesized Fe3O4 nanoparticles, poly(vinyledene fluoride)-Fe3O4 composite films were prepared by spin coating method. Scanning electron microscopy of the composite films showed the presence of Fe3O4 nanoparticles in the form of aggregates on the surface and inside of the porous polymer matrix. Differential Scanning calorimetry revealed that the crystallinity of PVDF decreased with the addition of Fe3O4. The conductitivity of the composite films was strongly influenced by the Fe3O4 content; conductivity increased with increase in Fe3O4 content. Vibration sample magnetometry results revealed the ferromagnetic behavior of the synthesized iron oxide nanoparticles with a Ms value of 74.50 emu/g. Also the presence of Fe3O4 nanoparticles rendered the composite films magnetic. 2010 Wiley Periodicals, Inc.
Crystallinity, conductivity, and magnetic properties of PVDF-Fe 3O4 composite films
(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.
The formation of Fe3O4 nanoparticles by hydrothermal process has been studied. X-ray Diffraction measurements were carried out to distinguish between the phases formed during the synthesis. Using the synthesized Fe3O4 nanoparticles, poly(vinyledene fluoride)-Fe3O4 composite films were prepared by spin coating method. Scanning electron microscopy of the composite films showed the presence of Fe3O4 nanoparticles in the form of aggregates on the surface and inside of the porous polymer matrix. Differential Scanning calorimetry revealed that the crystallinity of PVDF decreased with the addition of Fe3O4. The conductitivity of the composite films was strongly influenced by the Fe3O4 content; conductivity increased with increase in Fe3O4 content. Vibration sample magnetometry results revealed the ferromagnetic behavior of the synthesized iron oxide nanoparticles with a Ms value of 74.50 emu/g. Also the presence of Fe3O4 nanoparticles rendered the composite films magnetic. © 2010 Wiley Periodicals, Inc.
Electrical and magnetic properties of chitosan-magnetite nanocomposites
(2010) Bhatt, A.S.; Krishna, Bhat, D.; 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.
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.
Electrochemical properties of chitosan-Co3O4 nanocomposite films
(2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.
Chitosan-Co3O4 composite films have been prepared by solution casting method. The obtained films have been characterised by XRD and FESEM. The electrical properties of the films are examined by impedance spectroscopy in the temperature range 303-343 K. The impedance plot of the films pronounces the role of temperature in charge-transfer resistance of the composite. Frequency as well as temperature dependencies of dielectric constant and dielectric loss exhibit the general trend followed by carrier dominated dielectrics. Electric modulus parameters give an insight on the ionic conductivity and relaxation phenomena of the composite films. The dielectric parameters along with modulus data have been exploited to discuss the conduction mechanism in the material. The minimum activation energy of 3.9 kJ mol -1 and maximum room temperature conductivity of 1.94 10 -2 S cm-1 were found for composite film with 8% Co 3O4 content. 2011 Elsevier B.V. All rights reserved.
Electrochemical properties of chitosan-Co3O4 nanocomposite films
(Elsevier B.V., 2011) Bhatt, A.S.; Bhat, D.K.; Santosh, M.S.
Chitosan-Co3O4 composite films have been prepared by solution casting method. The obtained films have been characterised by XRD and FESEM. The electrical properties of the films are examined by impedance spectroscopy in the temperature range 303-343 K. The impedance plot of the films pronounces the role of temperature in charge-transfer resistance of the composite. Frequency as well as temperature dependencies of dielectric constant and dielectric loss exhibit the general trend followed by carrier dominated dielectrics. Electric modulus parameters give an insight on the ionic conductivity and relaxation phenomena of the composite films. The dielectric parameters along with modulus data have been exploited to discuss the conduction mechanism in the material. The minimum activation energy of 3.9 kJ mol -1 and maximum room temperature conductivity of 1.94 × 10 -2 S cm-1 were found for composite film with 8% Co 3O4 content. © 2011 Elsevier B.V. All rights reserved.
Excess and deviation properties of {(glycylglycine + ZnCl2) in aqueous methanol} mixtures
(2011) Santosh, M.S.; Krishna, Bhat, D.
The excess molar volumes (VE), viscosity deviations (??), deviations in isentropic compressibility (?? S) and excess molar refractivity (?RmE) for {(glycylglycine + ZnCl2) in aqueous methanol} mixture have been calculated from the experimental values. The bridging water molecules bend the chains into stable open ring structures together with intermolecular hydrogen bonding and interstitial accommodation leading to negative VE values. The positive ?? values indicate a structure breaking effect of aqueous glycylglycine-ZnCl2 upon contact with methanol molecules. It is also noted that chelation of zinc to glycylglycinate is through carboxylic group and not the amino group. The negative ??S values suggest the formation of an open ring structure lowering the entropy of the solution. Due to weak interaction between solute and solvent, the molecular structure of individual molecule does not change significantly and leads to negative ?RmE values. Finally, the results have lead to a good understanding of the thermodynamics properties of the studied liquid mixture. 2010 Elsevier Ltd. All rights reserved.
Excess and deviation properties of {(glycylglycine + ZnCl2) in aqueous methanol} mixtures
(2011) Santosh, M.S.; Bhat, D.K.
The excess molar volumes (VE), viscosity deviations (??), deviations in isentropic compressibility (?? S) and excess molar refractivity (?RmE) for {(glycylglycine + ZnCl2) in aqueous methanol} mixture have been calculated from the experimental values. The bridging water molecules bend the chains into stable open ring structures together with intermolecular hydrogen bonding and interstitial accommodation leading to negative VE values. The positive ?? values indicate a structure breaking effect of aqueous glycylglycine-ZnCl2 upon contact with methanol molecules. It is also noted that chelation of zinc to glycylglycinate is through carboxylic group and not the amino group. The negative ??S values suggest the formation of an open ring structure lowering the entropy of the solution. Due to weak interaction between solute and solvent, the molecular structure of individual molecule does not change significantly and leads to negative ?RmE values. Finally, the results have lead to a good understanding of the thermodynamics properties of the studied liquid mixture. © 2010 Elsevier Ltd. All rights reserved.
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.
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.
Microwave-assisted synthesis and magnetic studies of cobalt oxide nanoparticles
(2011) Bhatt, A.S.; Bhat, D.K.; Tai, C.-W.; Santosh, M.S.
An efficient microwave-assisted route has been used to synthesize nanoparticles of cobalt oxide. The particles were well characterized by transmission electron microscopy (TEM) which showed that the average diameter of the particles is around 6 nm. X-ray diffraction (XRD) studies further confirmed the formation of the spinel Co3O4. Purity of the products was detected by Fourier transform infrared spectroscopy (FTIR) combined with thermal gravimetric analysis (TG/DTG). The magnetic measurements revealed a small hysteresis loop at room temperature indicating a weak ferromagnetic nature of the synthesized Co3O4 nanoparticles. The magnetic moment of the particles was measured to be 4.27 ?eff. 2010 Elsevier B.V. All rights reserved.
Microwave-assisted synthesis and magnetic studies of cobalt oxide nanoparticles
(2011) Bhatt, A.S.; Bhat, D.K.; Tai, C.-W.; Santosh, M.S.
An efficient microwave-assisted route has been used to synthesize nanoparticles of cobalt oxide. The particles were well characterized by transmission electron microscopy (TEM) which showed that the average diameter of the particles is around 6 nm. X-ray diffraction (XRD) studies further confirmed the formation of the spinel Co3O4. Purity of the products was detected by Fourier transform infrared spectroscopy (FTIR) combined with thermal gravimetric analysis (TG/DTG). The magnetic measurements revealed a small hysteresis loop at room temperature indicating a weak ferromagnetic nature of the synthesized Co3O4 nanoparticles. The magnetic moment of the particles was measured to be 4.27 ?eff. © 2010 Elsevier B.V. All rights reserved.
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.
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.