Cochin University of Science and Technology

About: Cochin University of Science and Technology is a education organization based out in Kochi, Kerala, India. It is known for research contribution in the topics: Thin film & Natural rubber. The organization has 5382 authors who have published 7690 publications receiving 103827 citations. The organization is also known as: CUSAT & Cochin University.

Effect of iodine doping on the bandgap of plasma polymerized aniline thin films

Abstract: Pure and iodine-doped polyaniline thin films are prepared by ac plasma polymerization technique. Doping of iodine is carried out in situ as well as by employing iodine chamber methods. The structural analyses of pure and iodine-doped polyaniline thin films are carried out by FTIR spectroscopic studies. Optical bandgaps of these films are evaluated from UV-VIS absorption studies. Direct and indirect transition energy gaps are determined from Tauc plots. The structural changes of polyaniline upon doping and the reduction of optical bandgap are explained on the basis of the results obtained from FTIR spectroscopic and UV-VIS absorption studies.

Size-dependent surface plasmon resonance in silver silica nanocomposites

Abstract: Silver silica nanocomposites were obtained by the sol-gel technique using tetraethyl orthosilicate (TEOS) and silver nitrate (AgNO(3)) as precursors. The silver nitrate concentration was varied for obtaining composites with different nanoparticle sizes. The structural and microstructural properties were determined by x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS) studies were done for determining the chemical states of silver in the silica matrix. For the lowest AgNO(3) concentration, monodispersed and spherical Ag crystallites, with an average diameter of 5 nm, were obtained. Grain growth and an increase in size distribution was observed for higher concentrations. The occurrence of surface plasmon resonance (SPR) bands and their evolution in the size range 5-10 nm is studied. For decreasing nanoparticle size, a redshift and broadening of the plasmon-related absorption peak was observed. The observed redshift and broadening of the SPR band was explained using modified Mie scattering theory.

Hydrogeochemical study of shallow carbonate aquifers, Rameswaram Island, India.

Abstract: Groundwater quality assessment has been carried out based on physicochemical parameters (pH, EC, TDS, CO3, HCO3, Cl, SO4, PO4, NO2, Ca+2, Mg+2, Na+ and K+) and metal concentration in the Rameswaram Island from 25 bore wells. The Langelier Saturation Index of the groundwater shows positive values (63% samples) with a tendency to deposit the CaCO3 in the majority of water samples. Scatter plot (Ca + Mg/HCO3) suggests carbonate weathering process, which is the main contributor of Ca2+, Mg2+ and HCO3 ions to the water. Gibbs diagram suggests rock–water interaction dominance and evaporation dominance which are responsible for the change in the quality of water in the study area. NaCl and mixed CaNaHCO3 facies are two main hydrogeochemical facies of groundwater. Mathematical calculations and graphical plots of geochemical data reveal that the groundwater of Rameswaram Island is influenced by natural weathering of rocks, anthropogenic activities and seawater intrusion due to over exploitation. Weathering and dissolution of carbonate and gypsum minerals also control the concentration of major ions (Ca+2, Mg+2, Na+ and K+) in the groundwater. The nutrient concentration of groundwater is controlled to a large extent by the fertilizers used in agricultural lands and aquaforms. Comparison of geochemical data shows that majority of the groundwater samples are suitable for drinking water and irrigation purposes.