1,203 research outputs found
Large Magnetoresistance and Jahn Teller effect in SrFeCoO
Neutron diffraction measurement on the spin glass double perovskite
SrFeCoO reveals site disorder as well as Co intermediate spin
state. In addition, multiple valence states of Fe and Co are confirmed through
M\"{o}ssbauer and X-ray photoelectron spectroscopy. The structural disorder and
multiple valence lead to competing ferromagnetic and antiferromagnetic
interactions and subsequently to a spin glass state, which is reflected in the
form of an additional -linear contribution at low temperatures in specific
heat. A clear evidence of Jahn-Teller distortion at the Co-O complex
is observed and incorporating the physics of Jahn-Teller effect, the presence
of localized magnetic moment is shown. A large, negative and anomalous
magnetoresistance of 63% at 14K in 12T applied field is observed for
SrFeCoO. The observed magnetoresistance could be explained by applying
a semi-empirical fit consisting of a negative and a positive contribution and
show that the negative magnetoresistance is due to spin scattering of carriers
by localized magnetic moments in the spin glass phase
Coarse Bifurcation Studies of Bubble Flow Microscopic Simulations
The parametric behavior of regular periodic arrays of rising bubbles is
investigated with the aid of 2-dimensional BGK Lattice-Boltzmann (LB)
simulators. The Recursive Projection Method is implemented and coupled to the
LB simulators, accelerating their convergence towards what we term coarse
steady states. Efficient stability/bifurcation analysis is performed by
computing the leading eigenvalues/eigenvectors of the coarse time stepper. Our
approach constitutes the basis for system-level analysis of processes modeled
through microscopic simulations.Comment: 4 pages, 3 figure
Organic carbon in the sediments of the lower reaches of Periar River
Sediments are indicators of the quality of water overlying them and hence, useful in the assessment of environmental pollution. Temporal and spatial variations in sediment characteristics and organic carbon content from 9 stations in the lower reaches of Periyar River an area in Cochin Backwater, India which is polluted from different sources were studied for one year during 1981. Variations in colour and texture of sediments were brought about by changes in the grain size and state of oxidation of organic matter. The colour of the sediment varied from greyish black at stations 1 and 2, brownish at station 3, black at stations 4 to 8 and reddish at station 9.
Organic carbon and sediment texture showed a direct relationship at all stations except at station 9 where organic carbon content showed an irregular pattern. Overall range of organic carbon content was between 1.19 and 29.6 mg.g super(-1). The mean organic carbon of the stations ranged between 6.8 mg.g super(-1) (station 5) and 20.8 mg.g super(-1) (station 9). On the whole temporal variations were considerable with high values at station 9 and low values at station 5. Fluctuations were more at stations 6, 7 and 8
Prospecting for scarabid specific Bacillus thuringiensis crystal toxin cry8 gene in sugarcane ecosystem of Tamil Nadu, India
In the present study, we report the occurrence of cry8 positive isolates of Bacillus thuringiensis (Bt) in selected white grub, Holotrichia serrata F. (Coleoptera: Scarabaeidae), endemic soils of sugarcane ecosystem and other places in Tamil Nadu. Out of the 66 soil samples collected and screened for white grub specific Bt, 74 isolates of the bacterium, all containing only spherical crystal toxin, were identified. PCR screening of these isolates with cry8 gene universal primer revealed six isolates to be positive. Further, the amplicon of a 370 bp band, amplified with another set of degenerate primer designed based on the conserved sequence of cry8 genes, was sequenced from four isolates. Multiple sequence alignment revealed the gene sequences to be the same for all the isolates. The present report of the availability of cry8 positive Bt isolates opens the avenue for controlling white grubs through transgenic research
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