Valence instability of cerium under pressure in the Kondo-like perovskite La0.1_{0.1}Ce0.4_{0.4}Sr0.5_{0.5}MnO3_3

Effect of hydrostatic pressure and magnetic field on electrical resistance of the Kondo-like perovskite manganese oxide, La$_{0.1}$Ce$_{0.4}$Sr$_{0.5}$MnO$_3$ 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 $T_{\rm C}$ $\sim$ 280 K and there is a resistance maximum, $T_{\rm max}$ at about 130 K which is correlated with an antiferromagnetic ordering of {\it cerium} with respect to the Mn-sublattice moments. Under pressure, the $T_{\rm max}$ shifts to lower temperature at a rate of d$T_{max}$/d$P$ = -162 K/GPa and disappears at a critical pressure $P_{\rm c}$ $\sim$ 0.9 GPa. Further, the coefficient, $m$ of $-logT$ term due to Kondo scattering decreases linearly with increase of pressure showing an inflection point in the vicinity of $P_{\rm c}$. These results suggest that {\it cerium} undergoes a transition from Ce$^{3+}$ state to Ce$^{4+}$/Ce$^{3+}$ mixed valence state under pressure. In contrast to pressure effect, the applied magnetic field shifts $T_{\rm max}$ 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 RCrO3_3 (R-Y, Lu, Gd, Eu, Sm): A Raman study

Raman study on a select few orthochromites, RCrO$_3$ (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$_6$ 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