Sree Kerala Varma College

India

Sree Kerala Varma College

India
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Suresh R.,Cochin University of Science and Technology | Antony J.V.,Cochin University of Science and Technology | Antony J.V.,Maharajas College | Vengalil R.,Sree Kerala Varma College | And 2 more authors.
Industrial Crops and Products | Year: 2017

Partially sulfonated polystyrene (PSS), synthesized from expanded polystyrene waste (EPS), was used as a catalyst for free fatty acid (FFA) conversion in non-edible oils. Acidic and water absorbing properties of the PSS facilitated the catalytic action for the FFA conversion by esterification reaction. The reaction was done on simulated acid oil (WCO) containing oleic acid and sunflower oil, and rubber seed oil (RSO). Effects of temperature, catalyst amount and alcohol to acid molar ratio were studied. FFA conversion increased with each of these factors. The advantage of this heterogeneous catalyst is that it is efficient as commercial ion exchange resin and easily removable from the reaction mixture. PSS is found to substantially reduce the acid value of WCO and RSO from 17 to 3.2 mg KOH/g and from 28.8 to 4.8 mg KOH/g respectively at 75°C. The WCO and RSO with reduced acid value may be used as a feedstock for biodiesel production. © 2016 Elsevier B.V.


Kumar A.,Allahabad University | Singh M.K.,Allahabad University | Singh G.,Allahabad University | Sudheendran K.,Sree Kerala Varma College | Raju K.C.J.,University of Hyderabad
AIP Conference Proceedings | Year: 2016

Bi2Zn2/3-x/3Nb4/3-2x/3TixO7 (m - BZNT) with x = 0 to 0.4 were synthesized in the conventional solid state route. The dielectric constants of these ceramics at microwave frequencies are found to be increasing from 70 to 114 when x increased from 0 to 0.4. Raman scattering studies were carried out to investigate the effect of Ti4+ substitution on the dielectric properties of Bi2 (Zn2/3Nb4/3)O7 (m-BZN) ceramics. The observed Raman peaks in the m-BZNT are slightly shifted towards lower frequency in comparison to that of m-BZN clearly indicated that the Ti4+ ions are indeed occupying substitution sites in the host m - BZN. The anomalous change in intensity and full with at half maxima (FWHM) of Raman modes at 749 and 847 cm-1 suggest change in oxygen octahedral closely related to dielectric properties of m-BZNT. © 2016 Author(s).


PubMed | Indian National Institute for Interdisciplinary Science and Technology, Indian Institute of Chemical Technology, Sree Kerala Varma College, University of Illinois at Springfield and Government Medical College
Type: | Journal: Scientific reports | Year: 2015

Wrightia tinctoria is a constituent of several ayurvedic preparations against skin disorders including psoriasis and herpes, though not yet has been explored for anticancer potential. Herein, for the first time, we report the significant anticancer properties of a semi-purified fraction, DW-F5, from the dichloromethane extract of W. tinctoria leaves against malignant melanoma. DW-F5 exhibited anti-melanoma activities, preventing metastasis and angiogenesis in NOD-SCID mice, while being non-toxic in vivo. The major pathways in melanoma signaling mediated through BRAF, WNT/-catenin and Akt-NF-B converging in MITF-M, the master regulator of melanomagenesis, were inhibited by DW-F5, leading to complete abolition of MITF-M. Purification of DW-F5 led to the isolation of two cytotoxic components, one being tryptanthrin and the other being an unidentified aliphatic fraction. The overall study predicts Wrightia tinctoria as a candidate plant to be further explored for anticancer properties and DW-F5 as a forthcoming drug formulation to be evaluated as a chemotherapeutic agent against malignant melanoma.


Arun K.J.,Sree Kerala Varma College | Arun K.J.,Cochin University of Science and Technology | Jayalekshmi S.,Cochin University of Science and Technology
Photonics Letters of Poland | Year: 2015

A charge transfer complex crystal L-alaninium oxalate (LAO) is grown by slow evaporation at ambient temperature using an equimolar solution of L-alanine and oxalic acid as precursors. The third order nonlinear optical constants of the thin cleaved LAO crystal is measured by a single beam Z scan technique with and without an aperture in the far field. The crystal shows reverse saturable absorption and negative nonlinear refraction under our experimental conditions. Nonlinear optical constants are calculated from the experimental data. © 2015 Photonics Society of Poland.


Saravanan K.V.,University of Hyderabad | Saravanan K.V.,University of Aveiro | Sudheendran K.,University of Hyderabad | Sudheendran K.,Sree Kerala Varma College | Raju K.C.J.,University of Hyderabad
Electronic Materials Letters | Year: 2012

We report the fabrication and characterization of Ba0. 5Sr0. 5TiO3 (BST5) thin films on Pt/Ti/SiO2/Si substrates by RF magnetron sputtering. The x-ray diffraction (XRD) studies revealed that the BST5 films are highly oriented along (111) direction. The misfit strain in the films was about -0. 68%, which is compressive in nature. The Root Mean Square roughness (RMS roughness) measured using dynamic force microscope (DFM) was about 2. 4 nm. The low frequency (40 Hz-1MHz) dielectric properties measured using a Metal-Insulator-Metal structure show no dispersion either in dielectric constant or tan δ. The dielectric constant, loss tangent, tunability and figure of merit measured at 1MHz were about 598, 0. 008, 54% (at 200 kV/cm) and 66, respectively. Varactors of circular patch capacitor (CPC) structure were patterned on the BST5 layer using UV photolithography and metal lift off process. The microwave dielectric response of the parallel plate varactors, measured from 1. 5-10 GHz showed a tunability of ~30% (at 12 V dc bias) and a quality factor of 23. 5 (at 0 V dc bias). © 2012 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.


Rambabu A.,University of Hyderabad | Sudheendran K.,Sree Kerala Varma College | James Raju K.C.,University of Hyderabad
Journal of Materials Science: Materials in Electronics | Year: 2013

Thin films of SBTi (SrBi4Ti4O15) were deposited on fused silica substrates by rf-magnetron sputtering at substrate temperatures from 600 to 725 C. The effect of substrate temperature on preferential orientation, microstructure, Raman scattering characteristics and microwave dielectric properties of SBTi thin films were investigated. Microwave dielectric properties were investigated using the Split Post Dielectric Resonator (SPDR) technique. As the substrate temperature increases, the preferential orientation changes from (119) to (0010). Films deposited at 700 C exhibits less lattice distortion. It exhibits a dielectric constant about 110 and loss tangent about 0.06 at 10 GHz. It is seen from the Raman analysis that the films deposited at higher temperatures orients more towards c-axis which releases the torsional vibration mode involving TiO6 octahedra with a higher oscillator strength resulting in larger values of dielectric constant and dielectric loss for those films. © 2013 Springer Science+Business Media New York.


Haripadmam P.C.,Indian Institute of Space Science and Technology | Kavitha M.K.,Indian Institute of Space Science and Technology | John H.,Indian Institute of Space Science and Technology | Krishnan B.,Sree Kerala Varma College | Gopinath P.,Indian Institute of Space Science and Technology
Applied Physics Letters | Year: 2012

In the present work, we have investigated the optical limiting property of zinc oxide (ZnO) nanotop colloids and nanocomposite films of polymer-ZnO nanotops, using Z-scan technique. ZnO nanotops are prepared using two different capping agents. Films of polymethyl methacrylate-ZnO nanotop composite are fabricated for two concentrations of ZnO using spin coating technique. On exposing the nanocolloids to a pulsed nanosecond laser, the two photon absorption coefficient is enhanced with increase in applied fluence and particle size. The efficiency of limiting is found to be enhanced for the composite films, opening a way towards optoelectronic device fabrication. © 2012 American Institute of Physics.


Kooriyattil S.,Sree Kerala Varma College
Recent Patents on Materials Science | Year: 2014

Multiferroic materials which display the coexistence of ferromagnetism (FM) and ferroelectric (FE) polarization have drawn considerable attention due to their fundamental physical characteristics and potentially wide applications including tunable microwave devices. In a multiferroic material system, due to the mutual coupling of the ferroelectric and ferromagnetic order, an applied magnetic field can alter the dielectric polarization and an applied electric field can alter the magnetic polarization. This gives an additional degree of freedom to the designer for developing voltage tunable devices. There are some patented technologies which demonstrate the importance and development of multiferroic thin films for voltage tunable devices. This manuscript presents an analysis of the present and future of the mutiferroic materials- based technology for microwave applications. It also gives an extensive summary of recent patents and other relevant articles published in this field. © 2014 Bentham Science Publishers.


Alomari A.,Alabama A&M University | Batra A.K.,Alabama A&M University | Arun K.J.,Sree Kerala Varma College
Optik | Year: 2016

In this study, the pristine and La2O3-embedded poly vinylidene fluoride/trifluoroethylene [P(VDF-TrFE)] thick films were fabricated via solution casting technique and optical and dielectric properties investigated. P(VDF-TrFE)] is a potential candidate for electromechanical and acoustic sensors, actuators, energy harvesting and nonvolatile memory applications. Infrared vibrational spectroscopy (Raman) revealed enhancement of β-phase in the composite films. At room temperature, in the ultraviolet-visible range both the absorption and the optical bandgap (Eg) increased in nanocomposite films. Dielectric properties for nanocomposite films have been measured as a function of frequency in the range of 1 kHz to 1 MHz and temperature in the range from 20 °C to 80 °C. The dielectric results show increase in real and imaginary part of dielectric constant with temperature and volume fraction of La2O3 nanoparticles dispersed. The ac and dc activation energies were found to decrease with increase in volume fraction of nanoparticles following Arrhenius relationship. Thus, showing the conduction was thermally activated. © 2016 Elsevier GmbH


Kooriyattil S.,University of Puerto Rico at San Juan | Kooriyattil S.,Sree Kerala Varma College | Katiyar R.K.,University of Puerto Rico at San Juan | Pavunny S.P.,University of Puerto Rico at San Juan | And 2 more authors.
Applied Physics Letters | Year: 2014

We report a remarkable photovoltaic effect in pulsed laser deposited multiferroic aurivillius phase Bi5FeTi3O15 (BFTO) thin films sandwiched between ZnO:Al transparent conductive oxide top electrode and SrRuO3 bottom electrode fabricated on amorphous fused silica substrates. The structural and micro structural properties of these films were analysed by X-ray diffraction and atomic force microscopy techniques. The films were showing a photo sensitive ferroelectric behaviour with a notable apparent polarization in the range of 10-15 μC/cm 2. These films also exhibited a switchable photo-response and this parameter was observed to be sensitive to polarisation field and the polarization direction. The device shows a large ON/OFF photo current ratio with an open circuit voltage of 0.14 V. The photo response at zero bias of this BFTO based heterostructures showed rapid increase to a saturation value of 6 μA at zero bias. © 2014 AIP Publishing LLC.

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