Change in the room temperature magnetic property of ZnO upon Mn doping

We present in this paper the changes in the room temperature magnetic property of ZnO on Mn doping prepared using solvo-thermal process. The zero field cooled (ZFC) and field cooled (FC) magnetisation of undoped ZnO showed bifurcation and magnetic hysteresis at room temperature. Upon Mn doping the magnetic hysteresis at room temperature and the bifurcation in ZFC-FC magnetization vanishes. The results seem to indicate that undoped ZnO is ferromagnetic while on the other hand the Mn doped ZnO is not a ferromagnetic system. We observe that on addition of Mn atoms the system shows antiferromagnetism with very giant magnetic moments.Comment: 5 figure

Hydrogenation of olefins by polymer-bound palladium(II) Schiff base catalyst

Chloromethylated poly(styrene-divinylbenzene) was modified into coordinating Schiff base bearing ligand which was subsequently complexed with palladium chloride and activated by using sodium borohydride. The polymer-supported palladium complex and activated catalyst were characterized by various techniques such as elemental analysis, X-ray photoelectron spectroscopy, atomic absorption spectroscopy, IR, far IR spectral studies, SEM and thermogravimetric analysis. Surface area measurements by BET method and swelling studies with different solvents for the catalyst were also carried out. Catalytic activity towards hydrogenation of 1-hexene, 1-heptene, 1-octene, cyclohexene, norbornadiene (nbd) and 1,5-cyclooctadiene (1,5-cod) was assessed. The influence of variation in temperature, pressure, concentration of the catalyst as well as the substrate and the nature of the solvent on the rate of the reaction was studied for a few olefins. Recycling ability of the catalyst was also evaluated. © 2009 Elsevier B.V. All rights reserved

Studies on Population Dynamics and Seasonal Abundance of Zooplankton Community in Doddavoderahallilake, Bangalore

The present study was undertaken to investigate the zooplankton diversity in Doddavoderahallilake through different months during the period of January 2010 to December 2010. The sample consists of moderate biodiversity of total zooplankton with 15 species belonging to four taxonomic groups. Out of 15 species 9 belonged to Rotifera, 4 to copepod, 1 to cladocera, and 1 to Ostracoda. Rotiferan species have showed a high magnitude of biodiversity in comparative to other zooplankton subgroups. The percentage dominance of Rotifers were 45.05%. The values of number of zooplankton species indicating the pattern of bio diversity have exhibited a different dominating trend of its major subgroups as given rotifera>copepoda>cladocera>Ostracoda. The present study aims at providing a preliminary knowledge on the productivity and diversity of zooplanktons which can be utilized during the formulation of management measures to improve the productivity of the lake