The possibility of protein release from polymeric microcapsules by means of low-power (up to a maximum of 3.2 W) high-frequency (850 kHz) ultrasound was studied. The release efficiency using these ultrasonic parameters that are close to those currently used in medical diagnostic and ultrasound treatment was compared to that achieved with a conventional 20 kHz 70 W ultrasonic probe. Microcapsules were made by polyelectrolyte multilayer assembly on 3-5 mm calcium carbonate particles with co-precipitated fluorescently labelled protein. Ultrasound induced protein release was monitored by supernatant fluorescence increase after sonication. The release efficiency is improved by the presence of gold nanoparticles in the microcapsule shell. The amount of gold nanoparticles in the shell was found to play an important role in release efficiency. The irradiation was carried out at several intensities and exposure times and evidence of microcapsule rupture after treatment was obtained by confocal and scanning electron microscopy.

This article reviews the nanomaterials that have been prepared to date by pulsed sonoelectrochemistry. The majority of nanomaterials produced by this method are pure metals such as silver, palladium, platinum, zinc, nickel and gold, but more recently the syntheses have been extended to include the preparation of nanosized metallic alloys and metal oxide semiconductors. A major advantage of this methodology is that the shape and size of the nanoparticles can be adjusted by varying the operating parameters which include ultrasonic power, current density, deposition potential and the ultrasonic vs electrochemical pulse times. Together with these, it is also possible to adjust the pH, temperature and composition of the electrolyte in the sonoelectrochemistry cell.

The intensity distribution of the ultrasonic energy is, after the frequency, the most significant parameter to characterize ultrasonic fields in any sonochemical experiment.Whereas in the case of low intensity ultrasound the measurement of intensity and its distribution is well solved, in the case of high intensity (when cavitation takes place) the measurement is much more complicated. That is why the predicting the acoustic pressure distribution within the cell is desirable.A numerical solution of the wave equation gave the distribution of intensity within the cell. The calculations together with experimental verification have shown that the whole reactor behaves like a resonator and the energy distribution depends strongly on its shape.The agreement between computational simulations and experiments allowed optimisation of the shape of the sonochemical reactor. The optimal geometry resulted in a 2 strong increase in intensity along a large part of the cell. The advantages of such optimised geometry are (i) the ultrasonic power necessary for obtaining cavitation is low, (ii) low power delivered to the system results in only weak heating; consequently no cooling is necessary and (iii) the "active volume" is large, i.e. the fraction of the reactor volume with high intensity is large and is not limited to a vicinity close to the horn tip.

As one of several types of pollutants in water, chlorinated compounds have been routinely subjected to sonochemical analysis to check the environmental applications of this technology. In this review, an extensive study of the influence of the initial concentration, ultrasonic intensity and frequency on the kinetics, degradation efficiency and mechanism has been analyzed. The sonochemical degradation follows a radical mechanism which yields a very wide range of chlorinated compounds in very low concentrations. Special attention has been paid to the mass balance comparing the results from several analytical techniques. As a conclusion, sonochemical degradation alone is not an efficient treatment to reduce the organic pollutant level in waste water.

supplied by Undatim) for further uses in sonoelectrochemical studies.