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Kerala, India

Viji Z.,Nss College | Paulsamy,Kongunadu Arts and Science College
Research Journal of Pharmaceutical, Biological and Chemical Sciences | Year: 2015

The aim of this study is to evaluate the total phenolics,flavonoids,and tannin content and determine antioxidant activity of different fractions of P. tuberosa extracts. Antioxidant potential of petroleumether, chloroform, acetone, methanol and hot water extracts by using FRAP, metal chelating, phosphomolybdenum and free radical scavenging by using DPPH• and ABTS•+ were determined by using standard protocols with slight modifications. Quantification assays were carried out for the determination of phenols by Folin-ciocalteu method, tannins by using polyvinylpyrrolidine (PVPP) and flavonoids by aluminum chloride colorimetric method. Higher amount of phenols were found in acetone extract that is why itshows higher antioxidant activity. In ABTS+ assay higher scavenging activity of the tuber was observed in methanolic extract(9328.44±1923.77μmoles TE/g extract). In the present study the chloroform fraction was found to be more potent hydroxyl radical scavenger, with an IC50 value of 119.59μg/ml compared to other extracts.Acetone extract showed good antioxidant potential using FRAP(1796.67±146.21mmolesFeII/mg, metal chelating (112.78 ± 3.7512.78mg EDTA/gmextract, phosphomolybdenum (15.52 g AA/100g extract).). The total phenolic and tannin content was found to be higher in acetone extracts of tuber (443.87mg GAE/g and290.41mgGAE/g. The present results suggests that acetone extracts of P. tuberosa has significant antioxidant activity that it is effective against free radical mediated diseases and may be considered as natural source of antioxidant.

Marega C.,University of Padua | Causin V.,University of Padua | Saini R.,University of Padua | Marigo A.,University of Padua | And 3 more authors.
Journal of Physical Chemistry B | Year: 2012

The interfacial area between the matrix and the filler is a key parameter which shapes the performance of polymer-based composites and nanocomposites, even though it is difficult to quantify. A very easy SAXS method, based on the Porod equation, is proposed for measuring the specific surface area of nanofillers embedded in a polymer matrix. In order to assess its reliability, this approach was applied to natural rubber- or styrene butadiene-based samples containing different types of montmorillonite clay. A wide range of specific surfaces was detected. SAXS data were compared to complementary X-ray diffraction and TEM information, obtaining a good agreement. Interpretation of the tensile properties by theoretical models and comparison with the literature corroborated the validity of the specific surface area measurement. The possibility to quantify this feature of composites allows the rational design of such materials to be improved. © 2012 American Chemical Society.

Wilson R.,Mahatma Gandhi University | Plivelic T.S.,Lund University | Ramya P.,University of Mysore | Ranganathaiah C.,University of Mysore | And 3 more authors.
Industrial and Engineering Chemistry Research | Year: 2011

Poly(ethylene-co-vinyl acetate)/organically modified clay nanocomposites were prepared using different clay loadings and by varying the amount of organic modifier. The morphology of the nanocomposites was investigated using small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SAXS results displayed intercalation of polymeric chains between the silicate layers in all the cases. The interlayer distance varies slightly between the series. TEM images showed a better dispersion of the clay platelets at lower loading for both series of samples. The pervaporation performances of membranes were analyzed using a chloroform/acetone mixture. Membranes displayed high selectivity. The influence of feed composition on pervaporation was analyzed. The nanoclay content and the influence of free volume on pervaporation performance were also investigated in detail. A drop in selectivity and an increase in permeation rate were observed at higher clay loadings. © 2011 American Chemical Society.

Praveen V.N.,Nss College | Vijayan N.,National Physical Laboratory India | Mahadevan C.K.,Physics Research Center
Optik | Year: 2012

Pure and urea added zinc tris(thiourea)sulphate (ZTS) single crystals were grown by the solvent evaporation method from aqueous solutions. The grown crystals were characterized by X-ray powder diffraction, Fourier transform infrared, second harmonic generation and density measurements. The observed results show that the small amount of urea molecules were incorporated in the crystalline matrix of ZTS crystals. Dielectric measurements were carried out along a-, b- and c-directions of the grown crystals at various temperatures by the conventional parallel plate capacitor method with a fixed frequency of 1 kHz. The present study shows that the dielectric parameters (viz. dielectric constant, dielectric loss and a.c. conductivity) increases with the increase in temperature for all the grown crystals. Activation energies were also determined. © 2011 Elsevier GmbH.

Uma Maheswari A.,Amrita University | Saravana Kumar S.,Nss College | Sivakumar M.,Amrita University
Journal of Nanoscience and Nanotechnology | Year: 2013

In this work, the influence of different alkaline mineralizers on structural and optical properties of zirconia nanoparticles synthesized by chemical co-precipitation technique using zirconium oxychloride octahydrate (ZrOCl2 ·8H2O) as precursor is studied. The mineralizers used for the synthesis of nanoparticles are NaOH and NH 4OH. X-ray diffraction, Fourier Transform Infrared (FTIR) spectroscopy, UV-visible absorption spectroscopy and Photoluminescence (PL) spectroscopy were used for characterizing the nanoparticles. Structural analysis of the sample synthesized using NaOH shows monoclinic phase as predominant one, however when NH4OH is used the major phases are cubic and tetragonal. The difference is attributed to the number of hydroxyl ions produced and their rate of release during the reaction process. The presence of these phases in both samples is further confirmed by vibrational bands of FT-IR spectra. Also, the low energy bands due to the presence of defects in nanoparticles are also explicitly observed in the photoluminescence spectra. Further the defects lead to a red shift in the band gap of ZrO2 which is observed when the samples are subjected to UV-absorption spectroscopy analysis. It has been demonstrated that zirconia nanoparticles with desired structural properties can be synthesized by changing the type of mineralizer without the necessity of doping. Copyright © 2013 American Scientific Publishers All rights reserved.

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