V Durairaj | PubMed Health

PubMed2005

Colossal magnetoresistance by avoiding a ferromagnetic state in the Mott system Ca3Ru2O7.

Transport and magnetic studies of Ca3Ru2O7 for temperatures ranging from 0.4 to 56 K and magnetic fields B up to 45 T lead to strikingly different behavior when the field is applied along the different crystal axes. A ferromagnetic (FM) state with full spin polarization is achieved for the B//a axis, but colossal magnetoresistance is realized only for the B//b axis. For the B//c axis, Shubnikov-de Haas oscillations are observed and followed by a less resistive state than that for B//a. Hence, in contrast with standard colossal magnetoresistive materials, the FM phase is the least favorable for electron hopping. These properties together with highly unusual spin-charge-lattice coupling near the Mott transition (48 K) are driven by the orbital degrees of freedom.

Journal Article↗

PubMedDate not supplied

Adrenal cortical function and reserve in lepromatous leprosy.

22 chronic Lepromatous Leprosy patients of over 10 years duration, 17 non-reactional and 5 in reactional state who have not taken steroids as part of treatment were selected for the study. Serum cortisol was estimated by Radio-immuno-assay. Samples for basal values were collected at 8.00 A.M. Stimulated values were estimated in samples collected 8 hours after ACTH gel 40 units IM or 2 hours after 0.15 unit/kg BW Plain Insulin I.V. Basal cortisol values are: Normal controls 123.06 +/- 57.33 ng/ml. Non-reactional: 100.47 +/- 30.33 ng/ml; Reactional 141.4 +/- 43.15 ng/ml. Stimulated values are: Normal controls: 207.6 +/- 72.57 ng/ml. Non-reactional: 175.33 +/- 57.07 ng/ml, Reactional: 230 +/- 40.92 ng/ml. Basal serum cortisol in the non-reactional state is slightly lower than in normals but not statistically significant (P greater than 0.1). The basal cortisol in reactional subjects is slightly higher than in normals but not significant statistically (P greater than 0.05). The percentage rise over the basal value after stimulation test is found to be significantly low in both the reactional and non reactional states (P greater than 0.05) and also there is no statistically significant difference between these two groups (p greater than 0.5). Hence it is concluded that the Adrenal cortical reserve is low both in the non-reactional and reactional states of Lepromatous Leprosy.

Adrenal Cortex↗