Journal Articles

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    The measurement of electrical conductivity for the investigation of the number of water molecules present in the mixed crystals of barium copper oxalate and barium ammonium oxalate lattice have been carried out in the temperature range 30 to 450 °C. The dehydration temperature and the number of water molecules removed out of the structure at a particular temperature is estimated from the sharp increase in conductivity at these points. The almost steep increase of conductivity is attributed to the increase in the number of mobile charge carriers H+ and OH– ions generated from the escaping water molecules. The study of electrical conductivity in association with the thermal behaviour has been used to understand the mechanism of conduction. Copyright © 1995 WILEY?VCH Verlag GmbH & Co. KGaA
    (Electrical Conductivity and Thermal Dehydration Studies of Mixed Single Crystals of BaCu(C2O4)2 · 6 H2O, Ba1–xCuxC2O4 · 4 H2O and Ba1–2x(NH4)2xC2O4 · 4 H2O) Kasthuri, V.B.; Mohan Rao, P.
    1995
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    Investigation into creep behaviour of Sn-40%Pb alloy using impression creep method
    (2009) Udaya Prasanna, H.U.; Udupa, K.R.; Prabhu, K.N.
    The creep behaviour of Sn-40%Pb hypereutectic alloys cast in the molds made of different materials was investigated using impression creep technique in the temperature range from zero to 32 °C and under the punching stress of 50 MPa. The creep curves.ie, profiles of indentation depth against time are generated and steady state creep rates (SSCRs) are determined. Activation energy was calculated knowing creep rates at different temperature levels. Standard metallographic technique was used to determine the grain size of alloys which were poured into different molds. It was found that SSCR, at all the temperature levels of testing, is a function of grain size of the material. The activation energy being in the range of 10kJ/mol -12 kJ/mol, suggests that the probable creep mechanism is dislocation glide aided by vacancy diffusion. Results of the experiments are discussed.
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    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.
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    Fabrication and high-temperature structural characterization study of porous anodic alumina membranes
    (2012) Choudhari, K.S.; Sudheendra, P.; Udayashankar, N.K.
    Porous anodic alumina (PAA) membranes with highly ordered array of nanopores were prepared by twostep anodization process. Studies on structural and thermal properties and the thermal stability of the prepared PAA membranes were carried out. Investigation using scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermal analysis and infrared spectroscopy was performed on the prepared PAA membranes at room temperature and in the temperature range 600-1,400 °C. The as-prepared PAA membranes revealed the amorphous nature. Polycrystalline PAA membranes were obtained by annealing carried out at different temperatures. Annealing study confirmed that the heat treatment transformed the amorphous PAA membranes to their crystalline phases, namely, ?-alumina at about 870 °C and then to ?-alumina around 1,250 °C. © Springer Science+Business Media, LLC 2011.
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    Rapid removal of cobalt (II) from aqueous solution using cuttlefish bones; Equilibrium, kinetics, and thermodynamic study
    (2013) Sandesh, K.; Suresh Kumar, R.; JagadeeshBabu, P.E.
    The objective of this study is to assess the adsorption potential of cobalt (II) using cuttlefish bones. The bones were treated with 0.01 N HCl to enhance the heavy metal uptake. The adsorbent was characterized using scanning electron microscope and energy dispersive X-ray spectrometer. An adsorption study was conducted in a batch system to optimize process variables such as initial concentration of cobalt (II), pH, sorbent loading, particle size, process temperature, and contact time. The optimal pH was found to be 9. The kinetic data followed the pseudosecond-order kinetic model, and the equilibrium time was found to be 20 min. In the first minute of the adsorption process, 50% of the cobalt (II) was adsorbed by the cuttle bones. Adsorption isotherms were expressed by the Langmuir and Freundlich adsorption models. The Langmuir adsorption model fits the experimental data reasonably well compared with the Freundlich model. The maximum adsorption capacity of this new sorbent was found to be 76.6 mg g-1 at 40 °C. Thermodynamic parameters, including the Gibbs free energy (?Go), enthalpy (?Ho), and entropy (?So), indicated that the adsorption of cobalt (II) by cuttlefish bones was feasible and endothermic at a temperature range of 20-40 °C. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
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    LiClO4-doped plasticized chitosan and poly(ethylene glycol) blend as biodegradable polymer electrolyte for supercapacitors
    (Institute for Ionics, 2013) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.
    Biodegradable polymer electrolyte comprising the blend of chitosan (CS) and poly(ethylene glycol) (PEG) plasticized with ethylene carbonate and propylene carbonate, as host polymer, and lithium perchlorate (LiClO4), as a dopant, was prepared by solution casting technique. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. The variation of conductivity and dielectric properties has been investigated as a function of polymer blend ratio, plasticizer content and LiClO4 concentration at temperature range of 298-343 K. The DSC thermograms show two broad peaks for CS/PEG blend and increased with increase in the LiClO4 content. The maximum conductivity has been found to be 1. 1 × 10-4 S cm-1 at room temperature for 70:30 (CS/PEG) concentration. The electric modulus of the electrolyte film exhibits a long tail feature indicative of good capacitance. The activation energy of all samples was calculated using the Arrhenius plot, and it has been found to be 0. 12 to 0. 38 eV. A carbon-carbon supercapacitor has been fabricated using this electrolyte, and its electrochemical characteristics and performance have been studied. The supercapacitor showed a fairly good specific capacitance of 47 F g-1. © 2012 Springer-Verlag.
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    Effect of annealing on the structural and nonlinear optical properties of ZnO thin films under cw regime
    (2013) Nagaraja, K.K.; Pramodini, S.; Poornesh, P.; Nagaraja, H.S.
    We report on the studies of the effects of annealing on the structural and third-order nonlinear optical properties of ZnO thin films deposited on quartz substrates by the RF magnetron sputtering technique. The films were annealed in the temperature range 400-1000 °C. The third-order nonlinear optical studies were carried out using the z-scan technique under continuous wave (cw) He-Ne laser irradiation at 633 nm wavelength. The effects of annealing on the structural properties were examined using x-ray diffraction and atomic force microscopy (AFM). The (0 0 2) preferred orientation increased with increase in annealing temperature up to 800 °C. The crystalline phases of SiO2 were observed at higher annealing temperatures. The appearance of an extraneous phase was confirmed by AFM images and optical transmittance spectra. The samples exhibited nonlinear absorption and nonlinear refraction under the experimental conditions. The negative sign of the nonlinear refractive index n2 indicated that the films exhibit self-defocusing property due to thermal nonlinearity. The nonlinear refractive index n2, the nonlinear absorption coefficient ?eff and the third-order optical susceptibility ?(3) were found to be of the highest orders. The estimated value of third-order optical susceptibility ?(3) was of the order of 10-3 esu. Multiple diffraction rings were observed when the samples were exposed to the laser beam. The appearance of rings was due to the refractive index change and thermal lensing. With increase in laser intensity, the variations of the self-diffraction ring patterns were studied experimentally. The films also exhibited strong optical limiting properties under cw laser excitation, and reverse saturable absorption was the dominant process leading to the observed nonlinear behaviour. © 2013 IOP Publishing Ltd.
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    Thermo-catalytic degradation of low density polyethylene to liquid fuel over kaolin catalyst
    (Inderscience Publishers, 2014) Panda, A.K.; Singh, R.K.
    Waste low-density polyethylene samples were subjected to thermo-catalytic degradation using kaolin as catalyst in a batch reactor at temperature range of 400 to 500°C and atmospheric pressure. The quality and yield of the condensable product has been studied as a function of temperature and amount of catalyst. Both in thermal and catalytic degradation, the condensable fraction was less viscous liquid oil at low temperatures (up to 450°C), whereas with increase of temperature (from 475°C) the fraction became viscous and waxy. The recovery of condensable fraction increased from 30.8 wt.% at 400°C to 71.45% at 450°C and further increased to a maximum of 86.65wt.% at 500°C in absence of catalyst. The catalyst increased the yield of the condensable product and decreased the reaction time. The highest yield of liquid fraction at 450°C was 79.5 wt.% with 1:2 catalyst to plastics ratio. The composition of the oil obtained at optimum reaction condition was characterised by gas chromatography-mass spectroscopy (and found consisting of paraffins and olefins with mainly C10-C16 components. Fuel properties of the oil obtained by different standard methods are similar to petrochemical fuels. © 2014 Inderscience Enterprises Ltd.
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    Effect of annealing on the properties of Bi doped ZnO thin films grown by spray pyrolysis technique
    (Academic Press, 2014) Sadananda Kumar, N.; Bangera, K.V.; Shivakumar, G.K.
    The effect of annealing temperature on the structural, optical and electrical properties of transparent and conducting Bi doped ZnO (BZO) films deposited on glass substrate by spray pyrolysis technique was investigated. The BZO thin films were annealed in the temperature range from 450 °C to 550°C for 4 h in air atmosphere. The grain size of the BZO films increased with increasing annealing temperature. The annealed BZO films were electrically stable and there was a drastic change in the electrical conductivity after annealing. The films annealed at 500°C showed better conductivity and optical transmittance. © 2014 Elsevier Ltd. All rights reserved.
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    Studies on biosorption of methylene blue from aqueous solutions by powdered palm tree flower (Borassus flabellifer)
    (2014) M Kini, M.S.; Saidutta, M.B.; Ramachandra Murty, V.R.
    Biosorption experiments were carried out for the removal of methylene blue (MB) using palm tree male flower (PTMF) as the biosorbent at various pH, temperature, biosorbent, and adsorbate concentration. The optimum pH was found to be 6.0. The kinetic data were fitted in pseudofirst-order and second-order models. The equilibrium data were well-fitted in Langmuir isotherm and the maximum equilibrium capacities of the biosorbent were found to be 143.6, 153,9, 157.3 mg/g at 303, 313, and 323 K, respectively. Thermodynamic data for the adsorption system indicated spontaneous and endothermic process. The enthalpy and entropy values for adsorption were obtained as 15.06 KJ/mol and 0.129 KJ/mol K, respectively, in the temperature range of 303-323 K. A mathematical model for MB transported by molecular diffusion from the bulk of the solution to the surface of PTMF was derived and the values of liquid phase diffusivity and external mass transfer coefficient were estimated. © 2014 M. Srinivas Kini et al.