Ultrasonic atomization of distilled water.

Experimental data on ultrasonic atomization of distilled water in a frequency range from 5 to 50 kHz are presented. A good agreement was found with the predictions of Rajan and Pandit [Ultrasonics 39, 235-255 (2001)] for the atomized primary drop size as a function of frequency. The correlation of atomization drop size for different frequencies is useful when producing nanoparticles, spray drying of suspensions, and covering of surfaces using different liquid products. Determining the displacement amplitude threshold for atomization at different frequencies is valuable in designing ultrasonic atomization systems. It is essential to measure the displacement amplitude of the atomizing surface rather that power applied to the transducer because the former is absolute while the latter depends on the efficiency of the transducer and other design parameters. As previous predictions for atomization threshold proved inaccurate, an empirical expression is proposed (based on the authors' measurements) to predict the amplitude atomization threshold for the studied frequency range.

Electrochemistry in the presence of convective flow generated by acoustic streaming from a focused ultrasonic source.

Limiting currents for the reduction of hexacyanoferrate-(III), i(lim), in aqueous solutions have been recorded in the presence of convective flow generated by a focused acoustic source with its main axis placed normal to the surface of a circular Au electrode embedded in a coplanar Teflon shroud. The results obtained could be fitted to a formula of the type -i(lim) = a(Uz(ss))b, where Uz(ss) is the axial velocity of the fluid along the center line of the lens evaluated at the focal point using computer simulation routines developed by Kamakura and co-workers (Kamakura, T.; Matsuda, K; Kumamoto, Y.; Breazeale, M. A. J. Acoust. Soc. Am. 1995, 97, 2740-2746). The fit yielded a value of b approximately 0.5 in agreement with that of rotating disk and impinging jet electrodes.

Radiation absorbed dose estimates at the cellular level for some electron-emitting radionuclides for radioimmunotherapy.

Calculation of the radiation dose at the cellular level is given for several radionuclides that appear promising for radioimmunotherapy using the radiation dose distribution from a point source. The radionuclides have half-lives in the 1-3 day range and have electron ranges up to several hundred micrometers. The investigation emphasizes the physical considerations in radionuclide choice for the radiolabeling of monoclonal antibodies or antibody fragments.