1,605 research outputs found
Valence instability of cerium under pressure in the Kondo-like perovskite LaCeSrMnO
Effect of hydrostatic pressure and magnetic field on electrical resistance of
the Kondo-like perovskite manganese oxide,
LaCeSrMnO with a ferrimagnetic ground state, have
been investigated up to 2.1 GPa and 9 T. In this compound, the Mn-moments
undergo double exchange mediated ferromagnetic ordering at
280 K and there is a resistance maximum, at about 130 K which is
correlated with an antiferromagnetic ordering of {\it cerium} with respect to
the Mn-sublattice moments. Under pressure, the shifts to lower
temperature at a rate of d/d = -162 K/GPa and disappears at a
critical pressure 0.9 GPa. Further, the coefficient, of
term due to Kondo scattering decreases linearly with increase of
pressure showing an inflection point in the vicinity of . These
results suggest that {\it cerium} undergoes a transition from Ce state
to Ce/Ce mixed valence state under pressure. In contrast to
pressure effect, the applied magnetic field shifts to higher
temperature presumably due to enhanced ferromagnetic Mn moments.Comment: to be published in Phys. Rev. B (rapid commun
Antifungal activity of ethanolic extract of Sphaeranthus indicus Linn. against Dermatophytes and Candida species
Background: Sphaeranthus indicus as an entire plant or the specific parts like roots, leaves, flowers are used for treating helminthiasis, jaundice, diabetes, dyspepsia, fever, cough, hernia, gastritis, hemorrhoids, migraine, leprosy and skin diseases. The objective of this study was to evaluate the antifungal activity of ethanolic extract of the whole plant Sphaeranthus indicus Linn. Methods: The antifungal activity of ethanolic extract of the whole plant Sphaeranthus indicus Linn was evaluated by incorporating the extract in Sabourauds dextrose agar. This property was studied in vitro using the ethanolic extract on Candida albicans, Microsporum gypseum, Trichophyton mentagrophytes and Epidermophyton floccosum by using Clotrimazole as standard drug.Results: This study revealed that the ethanolic extract of Sphaeranthus indicus is having good antifungal activity against Dermatophytes and Candida species. Conclusions: This study demonstrates the promising antifungal action of ethanolic extract of whole plant of Sphaeranthus indicus Linn. This feature can be exploited in the development of a newer antifungal agent from plant.
In vitro evaluation of antibacterial activity in ethanolic extract of whole plant Sphaeranthus indicus Linn.
Background: Sphaeranthus indicus Linn is a widely used medicinal plant in Indian traditional system of medicine against human pathogens. Alarming bacterial resistance is urging scientist to search for newer anti-microbial substances from the medicinal plants. The objective of the study was to evaluate the antibacterial activity of ethanolic extract of the whole plant Sphaeranthus indicus Linn (Asteraceae).Methods: The antibacterial activity of ethanolic extract of whole plant of Sphaeranthus indicus Linn was done against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis and Staphylococcus aureus in Mueller Hinton Agar (MHA) and compared with ciprofloxacin as standard by disc diffusion method.Results: The study revealed that there was no zone of inhibition in doses of 100 mcg, 200 mcg and 300 mcg of ethanolic whole plant extract of Sphaeranthus indicus in MHA plates compared with ciprofloxacin 30 mcg.Conclusions: Ethanolic extract of Sphaeranthus indicus does not have antibacterial activity. Further studies are needed in different extracts and parts of the plant. Simultaneous studies can be done in different places to evaluate environmental factors and regional variations
Spin-phonon coupling in multiferroic RCrO (R-Y, Lu, Gd, Eu, Sm): A Raman study
Raman study on a select few orthochromites, RCrO (R = Y, Lu, Gd, Eu and
Sm) shows that the phonon behavior at TN in compounds with magnetic R-ion (Gd
and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu).
While anomalies in most of the observed phonon frequencies in all these
compounds may result from the distortion of CrO octahedra due to size
effect and magnetostriction arising from Cr-ordering, the anomalous behavior of
their linewidths observed at TN for the compounds with only magnetic R-ion
suggests spin-phonon coupling. The presence of spin-phonon coupling and the
anomalies in the low frequency modes related to R-ion motion in orthochromites
(R = Gd and Sm) support the suggestion that the coupling between 4f-3d moments
play important role in inducing switchable electric polarization.Comment: 6 pages (two column format), 7 figures; The updated version of the
manuscript can be found at Euro. Phys. Lett. 101, 17008 (2013
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