Large magnetic entropy change and prediction of magnetoresistance using a magnetic field in La0.5Sm0.1Sr0.4Mn0.975In0.025O3.

A detailed study of the structural, magnetic, magnetocaloric and electrical effect properties in polycrystalline manganite La0.5Sm0.1Sr0.4Mn0.975In0.025O3 is presented. The X-ray diffraction pattern is consistent with a rhombohedral structure with R3̄c space group. Experimental results revealed that our compound prepared via a sol-gel method exhibits a continuous (second-order) ferromagnetic (FM) to paramagnetic (PM) phase transition around the Curie temperature (T C = 300 K). In addition, the magnetic entropy change was found to reach 5.25 J kg-1 K-1 under an applied magnetic field of 5 T, corresponding to a relative cooling power (RCP) of 236 J kg-1. We have fitted the experimental data of resistivity using a typical numerical method (Gauss function). The simulation values such as maximum resistivity (ρ max) and metal-semiconductor transition temperature (T M-Sc), calculated from this function, showed a perfect agreement with the experimental data. The shifts of these parameters as a function of magnetic field for our sample have been interpreted. The obtained values of ß and γ, determined by analyzing the Arrott plots, are found to be T C = 298.66 ± 0.64 K, ß = 0.325 ± 0.001 and γ = 1.25 ± 0.01. The critical isotherm M (T C, µ 0 H) gives δ = 4.81 ± 0.01. These critical exponent values are found to be consistent and comparable to those predicted by the three-dimensional Ising model with short-range interaction. Thus, the Widom scaling law is fulfilled.

[Tuberculosis in hemodialysis patients in Tunisia]. / Tuberculose des patients hémodialysés en Tunisie.

BACKGROUND: Because of the immunity depression, patients with chronic renal failure undergoing haemodialysis are at increased risk for developing infections, Mycobacterium tuberculosis (MTb) in particular. OBJECTIVE: To evaluate, in a prospective longitudinal study over 36 months period, the frequency of Tb among these patients and underline the diagnostic difficulties. PATIENTS AND METHODS: Sixty dialysis patients were interested. The Tb assessment comprised: a questionnaire, a meticulous clinical examination, a chest X-ray, a tuberculin skin testing, as well as MT bacilli screening in biological fluids. RESULTS: Tb was seen in six among dialysis patients(10%), this rate represents 15 times the general population tuberculosis incidence in our country (23/100,000). Tb has occurred early compared to the beginning of the haemodialysis. The Tb localizations were: 4 cases of extra-pulmonary tuberculosis (3 peritoneal and one ganglionic) and only 2 cases of pleuro-pulmonary localization. The positive diagnosis represents a real problem: no bacteriological confirmation in all patients and only in one, the histological diagnosis was obtained. CONCLUSION: There was a high rate of tuberculosis in our study. The prognosis appears to be closely related to therapeutic precocity, thus specific chemotherapy started sometimes without diagnostic confirmation.

[Beware of yeast septicemia in intensive care medicine]. / Alerte aux septicémies à levures en réanimation polyvalente.

A retrospective study of 24 cases of systemic candidosis observed in a polyvalent intensive care unit over a 6.5 yr period (1987-1993) led to some constatations: an increasingly high incidence of this type of septicaemia (up to 27.5% of all septicaemias), large responsibility of skin saprophytes Candida ( > 62% vs 21% from intestinal Candida albicans), frequent diagnostic difficulties, and a fatal outcome in 7/24 patients (mainly from severe causal illness). In order to improve the prognosis, a more systematic and often empirical resort to fungicidal agents could be justified whenever patients with very severe surgical or medical conditions develop a protracted fever of unclear origin.