Sciencia Acta Xaveriana

21 - 34

Authors: A. Lourdusamy

The t-pebbling number, ft(G), of a connected graph G, is the smallest positive integer such that from every placement of ft(G) pebbles, t pebbles can be moved to a specified target vertex by a sequence of pebbling moves, each move taking two pebbles off a vertex and placing one on an adjacent vertex. We say a graph G satisfies the odd 2t–pebbling property if, for any arrangement of pebbles with at least 2ft (G) – r + 1 pebbles, where r is the number of vertices with an odd number of pebbles in the arrangement, it is possible to put 2t pebbles on any target vertex using pebbling moves. We study the odd 2t-pebbling property of graphs.

71 - 74

Authors: C. Sanjeeviraja, J.T. Anandhi, V. Anslin Ferby, A. Moses Ezhil Raj

Lanthanum Aluminum Oxide nanoparticles have been synthesized by an auto-combustion method for different oxidant to fuel (O/F) ratios (0.5, 1.0 and 1.5). Lanthanum nitrate and Aluminum nitrate were used as oxidants, Citric acid as fuel and Ammonia as buffer to adjust the pH of the solution. Crystallinity and crystalline phases of the prepared samples were analyzed using X-ray diffraction and the reflection planes (100), (110), (111), (200), (210), (211), (220), and (300) revealed the rhombohedral phase as comparable to the JCPDS standards (Card No. 85-0848). FTIR spectra again confirmed the single phase formation of compound by the noticeable metal-oxygen (AlO6 octahedra) ligand formation band in the lower frequency region at about 665 cm-1. In the higher frequency region, the band appeared at 440 cm-1 was assigned to the La-O coordination of the samples. Optical measurement revealed absorption in the low wavelength region that corresponds to the optical absorption edge, 4.95eV, 4.77eV, 4.88eV respectively for the LaAlO3 samples prepared for three different F/O ratios.

81 - 86

Authors: J. Madhavan, S. Arulmozhi

Optical absorption of 2-Amino 5-Chloro Benzophenone (2A5CB) single crystal has been measured and its direct band gap was found. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the nonlinearity of 2A5CB has been investigated by Kurtz and powder technique. Thus optical characterization of 2A5CB reveals the various application oriented properties of the material.

91 - 98

Authors: C.Krishnan, S.G.Rejith

In this work we evaluate structural and optical properties of Zn-Doped CuO nanoparticles grown by microwave assisted solvothermal method. The formation of Zn-Doped CuO nanoparticles were confirmed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-Visible spectroscopy. The average particle size have been found to be about 40 to 80 nm , The SEM image showed that the prepared product consists of spherical nanoparticles with narrow size distribution. The UV-Visible spectrum of Zn doped-CuO nanoparticles shows a strong blue shift compared to that of bulk and also shows the band edgeabsorption peak and is found to be at 350 nm. The obtained band gap value is 2.65 eV for Zn-Doped CuO nanoparticles.

103 - 110

Authors: Alphy Pius Stanly, John Xavier S, Selvakumar M.S, Prem Anand D

Green synthesis of nanoparticles is an emerging branch of nanotechnology. The characterization and sensing application of microwave synthesized and silver nanoparticles are reported in this work. The formation of silver nanoparticles was verified by UV-Vis spectroscopy and characterized by TEM and XRD analyses. The silver nanoparticles were used to detect Hg2+ ions colorimetrically by visible color change in aqueous medium. At higher pH value the deprotonated second 2+ions thereby inducing AgNP aggregation. The prepared silver nanoparticles were successful in sensing of mercury (II) ion even in a very low concentration of the order of 10-10 mol L-1 with high selectivity and sensitivity over K+, Mg2+, Mn2+, Na+, Fe3+, Zn2+, Ni2+, Co2+ and Ba2+ ions.