St Dominics College

Kerala, India

St Dominics College

Kerala, India

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Abraham R.,St Dominics College | Varughese K.T.,Indian Central Power Research Institute | Thomas S.,St Dominics College | Thomas S.,Mahatma Gandhi University
Macromolecular Symposia | Year: 2012

Nano crystalline powders of Barium Sodium Niobate (BNN) with the composition (Ba 3 Na 4Nb 10 O 30) have been prepared by conventional ceramic technique. XRD and SEM studies revealed that its particle size is in the nanometer range. Composites were prepared by mixing powders of BNN with polystyrene at different volume fractions of the material. Melt mixing technique was carried out in brabender plasticoder at a rotor speed of 60 rpm for composite preparation. Surface energy characteristics of the composites are measured using contact angle measurements of the composites with water and methlene iodide. The solid surface free energy is calculated from harmonic mean equations. The results are quantitatively analyzed with Girifalco-Good empirical model and provide unique insight into its properties. Various wettability parameters such as total solid surface free energy, work of adhesion, interfacial free energy and spreading coefficient are analyzed. The different parameters are calculated from the harmonic mean equation. The work of adhesion and interfacial free energy, spreading coefficient, and Girifalco-Good's interaction parameter had changed with composition. The surface properties can be controlled for a given polymer-surface pair by controlling the chemical structure, composition etc. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abraham R.,St Dominics College | Abraham R.,Mahatma Gandhi University | Selvin Thomas P.,King Fahd University of Petroleum and Minerals | Kuryan S.,Stephens College | And 3 more authors.
Journal of Applied Polymer Science | Year: 2010

Microcrystalline powders of yttrium barium copper oxide [YBa 2Cu3O7] have been prepared by conventional ceramic preparation technique. The powder belong to orthorhombic symmetry with unit cell dimensions 'a'=3.8214 Å, 'b'=3.8877 Å and 'c'=11.693 Å. XRD and SEM studies revealed that its particle size is in the micrometer range. Micro composites of polystyrene with different loading of yttrium barium copper oxide fillers were prepared by melt mixing in a brabender plasticorder at a rotor speed of 60 rpm. The lattice parameters of the constituent phases are the same in all the composites. Mechanical properties such as stress-strain behavior, Young's modulus, and tensile strength were studied as a function of filler loading. Addition of filler enhances the Young's modulus of the polymer. Because of the poor filler-matrix adhesion, tensile strength and strain at break decreases with filler loading. To explore more carefully the degree of interfacial adhesion between the two phases, the results were analyzed by using models featuring an adhesion parameter. Finally experimental results were compared with theoretical predictions. © 2010 Wiley Periodicals, Inc.

Abraham R.,St Dominics College | Abraham R.,Mahatma Gandhi University | Kuryan S.,Stephens College | Isac J.,CMS College | And 2 more authors.
Journal of Applied Polymer Science | Year: 2011

Electrical impedance measurements are carried out on high temperature superconducting ceramic Yttrium Barium Copper Oxide (YBCO)-Polystyrene (PS) composite materials, in which superconducting particles are embedded in polystyrene matrix. The results of impedance versus frequency (100 Hz-13 MHz), phase angle versus temperature for volume percentage of superconductor (0-40%) are presented. No marked transition in phase angle is observed when the material goes through the superconducting transition temperature of the filler. The dielectric constant and losses increase with increasing YBCO content. However the increase in losses is modest and the excellent dielectric properties of the composites are not adversely affected. The system conforms to Clausius-Mossotti equation. Dipole moment of YBCO particles and polarizability of the composites are calculated using the Clausius-Mossotti approaches. © 2010 Wiley Periodicals, Inc.

Rosalin A.,St Dominics College | Varughese K.T.,Indian Central Power Research Institute | Jayakumari I.,CMS College | Thakur O.P.,Solid State Physics Laboratories | Thomas S.,University Technology of MARA
Materials Research Innovations | Year: 2012

Nanocrystalline powders of barium nodium niobate have been prepared by conventional ceramic technique. The powders belonged to a tungsten bronze type structure with tetragonal symmetry and lattice constants 'a'51·24214 nm and 'c'50·39028 nm. Composites were prepared by mixing powders of barium sodium niobate Ba 3Na 4Nb 10O 30 (BNN) with polystyrene (PS) at different volume fractions of the material. The viscoelastic, tensile and dielectric properties of BNN-PS nanocomposites were investigated with special reference to the effect of filler loading, frequency and temperature. The composites showed a significant increase in storage modulus in the glassy and rubbery regions. The tan d peak temperature of the composites is shifted to the higher temperature region, and the peak intensity is lowered for all combinations. The composites showed a shift in cross-over frequency to the lower side, suggesting a delayed relaxation of the molecular chains in the presence of BNN, and this shift is found to depend on the content of BNN. The modulus enhancement is related to the volume of the added BNN as well as the volume of the constrained polymer. The study of the constrained volume of the polymer indicates that the structure of the ceramic nanocomposite possesses a strong interfacial interaction. The compatibility of the composites is observed through the Cole-Cole plots. The core shell morphology is predicted for the composite cross-section. © W. S. Maney & Son Ltd. 2012.

Ray J.G.,Environment Science Research Laboratory | George J.,St Dominics College
International Journal of Applied Environmental Sciences | Year: 2010

Lead contamination in roadside soil is a global phenomenon, but Lead accumulation in roadside herbs is least reported. Lead accumulating species are rare; the success of phytoremediation of Lead contaminated soils depends on the discovery of new Lead hyper accumulators. In this context, Lead in the shoots and roots of about nineteen tolerant roadside herbs growing in soils close to one meter margin from the tar-edge of two busy roadsides in Kerala in South India was examined. Soil and plant samples were collected for two years from different sites differing in the degree of contamination. Lead in the shoots of all plant species and also in the roots of grasses, and in the soils where the plants grew was assessed, compared and statistically analyzed. The roadside soils were found moderately Lead contaminated. All the species were found accumulating Lead in shoots or roots in significantly different amounts. Positive correlations were found between Lead in plants and that in the different soils where they grew and in some of the species, the correlations were very strong. Lead in the shoots of Pilea microphylla (L.) Liebm., and that in the roots of Cynodon dactylon (L.) Pers., was found in quantities higher than the quantity of the metal in the soil. © Research India Publications.

Sarwar H.,Gartnavel General Hospital | Mahmood-Rao S.,St Dominics College
Dental Update | Year: 2015

The removal of mandibular third molars can be complicated by injury to the inferior alveolar nerve (IAN). Coronectomy retains the tooth root; this method has been found to be preferable to extraction in the context of mandibular third molars. A failed coronectomy may cause mobilization of these roots, thereby requiring a subsequent extraction. Having undergone a previous coronectomy, extraction is then safer as the roots usually migrate away from the IAN. Computed tomography is more accurate than radiography when imaging mandibular third molars pre-operatively owing to its three-dimensional nature. Longer studies need to be conducted to evaluate the long term benefits of coronectomy.

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