Behavior of the layer compression elastic modulus near, above, and below a smectic C-hexatic I critical point in binary mixtures.

We present the first study of the layer compression modulus B carried out near, above and below the Smectic C-Hexatic I critical point in racemic mixtures of methylbutyl phenyl octylbiphenyl-carboxylate (8SI) and the octyloxy biphenyl analog (8OSI), at frequencies ranging from 0.2 Hz to 2 x 10(3) Hz. The behavior of B as a function of temperature shows a progressive evolution from a first order transition in 8SI to a continuous supercritical behavior in 8OSI. The latter is characterized by an increase in B, which appears above the transition, and which is followed by a leveling off when the temperature is decreased towards the transition. It is proposed that this behavior stems from the relaxation of the hexatic domains which are frozen in the frequency range studied. For the supercritical and near-critical compounds, B exhibits a small dip near the transition temperature, which is visible in the low frequency range only, indicating that the dynamics associated with the critical point is very slow. We also report measurements in the Crystal-J phase of the pure compounds, and show that 8SI behaves mechanically as a hexatic phase and 8OSI as a soft crystal phase.

[The renin-angiotensin-aldosterone system in hypertensive patients. II. Diagnosis of primary hyperaldosteronism]. / Le système rénine-angiotensine-aldostérone chez les sujets hypertendus. II. Le diagnostic de l'hyperaldostéronisme primaire.

Twenty patients suffering from primary hyperaldosteronism were studied. Sixteen had a single adenoma of the adrenal and four had bilateral hyperplasia affecting both adrenals. Cases of primary hyperaldosteronism due to a tumour were characterised by a higher degree of hypermineralocorticism than was seen in the patients with hyperplasia. Plasma aldosterone, after acute volaemic expansion, did not fall below 13 ng/100 ml in the adenoma patients whilst it was lower in the case of hyperplasia. Adrenal phlebography is a useful tool in preoperative diagnosis.