Porous titania was prepared on titanium substrate in various electrolytes such as HNO_3, H_2SO_4, and NH_4F under ultrasonication. Nano/microstructure of titania can be widely controlled by anion species, temperature, electric condition, and ultrasonication. It is inferred in general that ultrasound decrease the thickness of barrier film and apt to form anatase phase.

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The effects of ultrasonic parameters in high frequency ultrasonic atomization system on ethanol enrichment from ethanol-water mixture were investigated. Ethanol enrichments on different concentrations of ethanol-water feed mixtures were conducted in a continuous feed system operating at variable frequency and input power as reported in the previous work. An empirical determination of cavitation intensity in feed solutions sonicated was performed by measuring the amount of iodine liberated from the oxidation of potassium iodide solution. The ethanol concentrations in condensates were dependent on the ultrasonic frequency and the input power. The cavitation intensity in the feed solution was influenced by feed ethanol concentration and ultrasonic frequency. Especially in low feed concentration, the cavitation intensity was significant. This result suggests that cavitation plays an important role in ultrasonic enrichment of ethanol.

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The hot spots that high pressures and temperatures generated during the bubble collapse process, especially in acoustic cavitation, directly related to the physical and chemical reactions. It is very evident that the bubble cloud plays an important role in such reactions and the collapse of bubble clouds under asymmetrical conditions, in particular near a rigid wall or between two walls, is very important. We study the behavior of such bubble clouds in the limited space between solid boundary surfaces for various concentarations C and separation distances S, by means of high-speed motion pictures. The vibratory horn ring was immerged to 5mm of submerged depth in a glass container with an ethanol aqueous solution of 50 cc and drived at resonent frequency of 20 kHz by means of a 700 W amplifier, the corresponding amplitude is 124 μm peak to peak. The bubble cloud observed with time intervals of 1 μs, which is short compared with the 50 μs period of the oscillation by the magnetostrictive driver. The bubble cloud grows and collapses as a single bubble. The maximum diameter of the bubble cloud is relatively large in the range of ,S<0.2mm, for S>1.0mm, the maximum diameter remains a constant. The number of the bubble clouds increases with S in spite of C and the bubble cloud shows nonlinear pulsations in the process.

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The hot spots that high pressures and temperatures generate during the bubble collapse process, especially in acoustic cavitation, directly related to the physical and chemical reactions, hi this study, to investigate the possibility of realization for the sake production process, we investigate the MB effects on the composition of sake. The fragrance ingredient in sake is affected by the activities of the hot spot and/or shock waves, resulting in the decompositions and the synthsis of the fragrance ingredient. The ethyl acetate and the ethyl caproate activated to are decreasing by hydrolysis, while the isoamyl acetate is activated by increasing in the dehydration. There are many point which must be clarified, i.e., the oxidation of isoamyl alcohol by affecting the dissolved gas in the solutions.

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Ashokkumar et al. [J. Am. Chem. Soc. 129, 2250 (2007)] reported that the intensity of the broad-band noise in acoustic cavitation noise from a low concentration surfactant (SDS) solution is much weaker than that from pure water. In the present study, numerical simulations of acoustic cavitation noise have been performed in order to study the mechanism of the much weaker broad-band noise from aqueous surfactant solution. The results of the numerical simulations have indicated that bubbles are shape stable in a low concentration aqueous surfactant solution due to smaller ambient radius of bubbles than that in pure water. It results in the much weaker broad-band noise because there is much less temporal fluctuation in the number of bubbles which is the origin of the broad-band noise. In other words, in a low concentration surfactant solution stable cavitation dominates, while in pure water transient cavitation dominates. Transient cavitation causes the temporal fluctuations in the number of bubbles resulting in the intense broad-band noise.

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Intense orange Na^* emission was observed in different spatial locations from blue emission during multibubble Sonoluminescence in sulfuric acid. The color change from blue to orange observed along the streamer in the filamentous structure of a bubble cloud. By stroboscopic observation, the Na^* emission seemed to occur when a large bubble ejected tiny bubbles toward a pressure node after bubble coalescence around a pressure antinode. The intensity of Na^* emission in sulfuric acid increased at lower frequency in contrast to the water case. Comparing a high resolution Na^* spectrum of sulfuric acid with water, the full width at half maximum of the spectra were almost the same, except for something superimposed in water case. The estimations of the temperature and pressure inside the Na^* emission bubbles in sulfuric acid at 28 kHz and 150 kHz were 1900 K and 100 atm and 2200 K and 150 atm, respectively.

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Sonoluminescence spectra from Ar-saturated KC1 solutions were measured at the frequencies of 147.9 kHz and 1.029 MHz in the temperature range of 15-40℃. Spectra of K atom emission showed that the spectral lines at 147.9 kHz were broadened asymmetrically to the red side, but the line width at 1.029 MHz was narrower than that at 147.9 kHz. To examine the effect of water vapor, the temperature of solution was changed in the range from 15 to 40℃. The result indicated that the spectral shape was hardly dependent on amount of water vapor and final temperature in collapsing bubbles. Effects of dissolve gas were also studied. The results for Xe-saturated solution suggested that the spectrum indicated two components, unshifted narrow line, and shifted broadened line. The spectral line of K atom emission from He-saturated solution was broadened symmetrically. These results were consistent with the results of spectroscopy in gas phase.

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