Speciation in aqueous solutions of nitric acid.

In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs.

Effect of ultrasonic frequency on the mechanism of formic acid sonolysis.

The kinetics and mechanism of formic acid sonochemical degradation were studied at ultrasonic frequencies of 20, 200, and 607 kHz under argon atmosphere. Total yield of HCOOH sonochemical degradation increases approximately 6-8-fold when the frequency increased from 20 to 200 or to 607 kHz. At low ultrasonic frequencies, HCOOH degradation has been attributed to oxidation with OH(•) radicals from water sonolysis and to the HCOOH decarboxylation occurring at the cavitation bubble-liquid interface.

Nitric acid: modeling osmotic coefficients and acid-base dissociation using the BIMSA theory.

This work is aimed at a description of the thermodynamic properties of highly concentrated aqueous solutions of nitric acid salts at 25 °C within the binding mean spherical approximation (BIMSA) theory. The predictive capability of this model was examined. First, Raman spectroscopy was used to study the proportion of associated nitric acid as a function of concentration.

[Cardiac resynchronization in congestive heart failure: role of Doppler echocardiography in patient selection].

Cardiac echodoppler is an efficient tool to analyse cardiac mechanic loop. Diastolic and systolic desynchronisation criteria are analysed. It should allow a more efficient selection of patients who could take benefit of resynchronization therapy, but also to choose resynchronization system, to program optimal atrioventricular delay, interventricular delay and to evaluate resynchronization efficiency.

[Resynchronization of the failing heart by pacing].

Cardiac pacing has been proposed for patients with advanced heart failure refractory to optimal drug treatment and having conduction disorders to resynchronize mechanical activity of the heart. Activation asynchronism as caused by bundle branch block results in alteration of systolic function and arrhythmias. A too short or too long atrio-ventricular delay can also affect diastolic ventricular filling.