Nycthemeral changes in plasma cortisol levels in preruminant calves with different milk proteins

International audienc

Daily metabolism and hepatic balance studies of plasma cortisol and aldosterone in the preruminant calf

International audienc

Prolactin receptor levels on lymphocytes vary with menstrual cycle in women

Prolactin exerts effects on the immune system, potentiating T-cell growth in response to various stimuli. These effects are felt to be mediated by specific receptors present on lymphocytes for prolactin. While the presence of prolactin receptors (PRLRs) on lymphocytes is well accepted, potential fluctuations in these receptor levels in individuals have not been studied. Here we present evidence that lymphocyte prolactin levels vary throughout the menstrual cycle in females. Lymphocyte PRLR levels varied up to 10-fold as determined by radioreceptor assay on the different days of the menstrual cycle. A semi-quan-titative PCR technique was used to measure message levels, and these generally correlated with radioreceptor results. We conclude that lymphocyte PRLR levels vary throughout the menstrual cycle and that these variations are due at least in part to variations in PRLR mRNA levels. \ua9 1994 S. Karger AG, Basel

Effect of Temperature on Structure and Electronic Properties of Nanometric Spinel-Type Cobalt Oxides

International audienceTemperature is shown to have a huge influence on the electronic properties of nanometric spinel-type cobalt oxides precipitated at low temperature in alkaline media. The initial phase, with formula HxLiyCo3−δO4, contains hydrogen, lithium, cobalt vacancies, and a mixed valence Co4+/Co3+ within the structure, leading to an electronic conductivity higher than that of stoichiometric Co3O4. Its structural evolution under thermal treatment was studied by X-ray diffraction and chemical analysis, which reveal modifications in structure and compositions, involving water release, increase of the Co/O atomic ratio, and modification of the Co4+/Co3+ ratio. The RT to 300 °C range is particularly interesting as a single-phase domain and the materials obtained in this temperature range were investigated by chemical analysis, electronic conductivity and specific surface area measurements. Upon increasing temperature, the enhancement of the Co4+/Co3+ ratio, together with cationic redistribution in the spinel framework, results in an improvement of the electronic conductivity (more than 2 orders of magnitude for materials heated above 150 °C). Finally, the systematic thermal study of electronic conductivity and specific surface area of the materials allows to determine an optimal heat-treatment temperature leading to an optimized active electrode material for electrochemical energy storage applications, especially in supercapacitors. Such a solid state chemistry approach combining many material characterization techniques to reach a complete knowledge of the material is quite rare in the literature concerning oxides for supercapacitors