The nanoparticles of various metal such as Pt, Au, Pd, etc. can be easily by ultrasonic irradiation. This study was conducted to prepare MnO_2 nanoparticles from potassium permanganate solutions with various concentration of three different surface-active agents by ultrasound. The amount of MnO_2 and MnO_4^- ions were measured as a function of irradiation time by using the spectrophotometer. The experimental conditions of sonication were as follows; frequency 200kHz, output power 200W, bulk temperature 293K. On the basis of the results obtained, the roles of surface-active agents and H radicals were discussed in terms of the formation rate of MnO_2 and reduction rate of MnO_4^-.

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Magnetic iron oxide nanoparticles were successfully prepared by sonochemical oxidation of aqueous solution containing FeSO_4 and NaOH. Obtained particles were identified as magnetite by XRD measurement. The morphologies of the products were characterized by TEM observation. In the use of polyethylene glycol monostearate as protective agent, the dispersity of the formed nanoparticles was improved. Additionally, these nanoparticles showed narrower size distribution than that in the absence of protective agent. When sodium dodecyl sulfate was employed, sonochemical oxidation of Fe(II) slowed down probably due to its higher scavenging effects for hydroxyl radicals. We also investigated the preparation of Au/magnetite nanocomposite.

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Mn(II) ions in alkaline aqueous solution containing dioctyl sulfosuccinate (AOT) were successfully oxidized under sonication to form brown precipitate. The formed products were found to be Mn_3O_4 by XRD analyses, regardless of calcination. The oxidation of Mn(II) ions was thought to be promoted by sonochemically generated oxidizing agent, such as hydrogen peroxide or effective stirring. In conventional precipitation method, Mn_2O_3 and Mn_3O_4 were formed in the absence and presence of AOT, respectively. We evaluated their catalytic properties for ozone decomposition under high humidity at 5 degree C. The activities of sonochemically prepared Mn_3O_4 were higher than that of Ma_2O_3 by precipitation method, and almost same as that of Mn_3O_4 by precipitation method. It is known that Mn_3O_4 could easily adsorb oxygen atoms and store them up to the composition of Mn_3O_<4.26>. The reason why sonochemically prepared catalyst maintained its activity might be that the adsorbed oxygen atoms constantly desorbed even at low temperature.

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A novel acoustic dispersion method for fine diamond particles was proposed. Two samples of nanosized diamond particles were used. They had primary particle sizes of 5 nm (ND5) and 150 nm (ND150), respectively. Ultrasound disaggregation and surface modification of ND5 and ND150 were investigated. ND5 and ND150 aggregated to secondary particles of micrometer order. The surface of ND5 and ND150 was modified and the particles were disaggregated by acoustic cavitation. ND5 was disaggregated to give an average particle size of about 100 nm by ultrasound exposure with average acoustic intensities higher than 800 W/m^2. ND150 with size of 15μm was disaggregated to reach an average particle size of about 300 nm by ultrasound exposure with an average acoustic intensity higher than 2000 W/m^2. The surface of ND5 and ND150 particles was found to be modified with hydroxyl groups by acoustic cavitation. This could lead to a well dispersion of nanosized diamond particles in water.

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Hydrogen gas is one of the most important alternative energy sources and indispensable to operate fuel cells. Using conventional reforming technique of some kinds of hydrocarbons, or alcohols, it is easy to obtain hydrogen gas. In this case, however, separation of hydrogen from other byproducts is not easy. We prepared silver nanoparticles by sonochemical reduction of silver complex, molded them in the film, and tried to develop novel hydrogen selective permeation membrane. Silver-ethylenamine complex was used as precursor of colloidal silver. In the presence of polyethyleneglycol monostearate, sonochemical reduction of silver complex successfully proceeded and formed yellowish transparent solution including silver nanoparticles. Silver thin films were prepared by immobilizing them on the surface of AAO mesh by electrophoresis technique. Sonochemical immobilizations of Ag onto the AAO mesh were also carried out. We will report the property of the membrane for the selective permeation of hydrogen gas.

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Carbon nanomaterials were synthesized by ultrasonic irradiation of benzene dissolved in water. After the irradiation for 20min, the solution turned yellow, because of the formation of polymers. After 7h, a dark brown powder appeared. TEM images of this product revealed disordered lattice planes of graphite and clusterparticles of the order of 100nm in size. Therefore, it was confirmed that the product was a kind of carbon nanomaterial. Another experiment was also carried out using benzene, but it remained colorless and transparent and nothing was produced. Thus, water was found to play an important role in synthesizing carbon nanomaterials on the condition of the present experiment.

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In our previous work, we have reported that the electropolymerization of an immiscible monomer, such as 3,4-ethylenedioxythiophene (EDOT), proceeded very smoothly in acoustically emulsified solutions. In this study, we investigate the details of the reaction mechanism in order to apply this methodology to polymer and organic syntheses. It was found that the emulsions prepared by acoustic emulsification in aqueous solutions containing 1.0M Li_2SO_4, 1.0M LiNO_3 and 1.0M LiClO_4 respectively, were quite stable even after standing for 60min. In addition, these emulsions have the characteristic of giving narrow droplet size distributions in the manometer range. Above facts suggest that the characters of emulsion prepared by acoustic emulsification were not influenced by the electrolyte species. On the other hand, the polymerization of acoustically emulsified EDOT hardly occurred in 1.0M Li_2SO_4 and 1.0M LiNO_3 aqueous solutions. In sharp contrast, the polymerization proceeded very smoothly in 1.0M LiClO_4 aqueous solution. It is well-known that LiClO_4 is relatively soluble in an organic medium. LiClO_4 dissolved in the droplets should play the role of the supporting electrolyte and contribute to the formation of an electric bilayer inside the droplets. It can be consider that the very smooth polymerization of EDOT in an aqueous medium was ascribed to the formation of nanometer-size monomer droplets by acoustic emulsification and formation of electric bilayer inside the droplets by supporting electrolyte dissolved in droplets.

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We have proposed a concept of 'Sonofunctional Molecules', which develop new functionalities by ultrasonic irradiation. As a first sonofunctional molecule, compound 1 was prepared by introducing alkyl thiol moieties into a diaminoacridine moiety which was known as a DNA intercalator. Compound 1 has the potential for cancer treatment. After intercalation into DNA and successive ultrasonic irradiation, compound 1 can be expected to form irreversible complexes with DNA, which may cause damages on DNA duplication. In the preliminary experiments, after ultrasonic irradiation for several hours in an aqueous i-PrOH, it was confirmed that 1 was oxidized and converted into cyclic structure by the formation of intramolecular disulfide bond. In this study, the binding ability of compound 1 to DNA was examined by means of UV spectroscopy. The typical experimental procedure is as follows. DNA (from Salmon Testes, Sigma) and 1 were dissolved into water-i-PrOH-CH_2Cl_2, and irradiated by 200 kHz ultrasound (Kaijo Model 4021) for 24 hours at 25℃(Fig.1). After the reaction solution was washed with CH_2Cl_2 and its pH was adjusted to 10.0 ±0.5, UV spectra of water layer were measured. As shown in Fig.2, compound 1 was solubilized into the water layer, although 1 had no solubility into water. Moreover, the solubility was doubly enhanced by ultrasonic irradiation. On the other hand, derivatives 2 and 3 showed no ultrasonic enhancement in solubility into water (Figures 3 and 4). These results clearly indicate that the sonofunctional molecule 1 is bound to DNA by ultrasonic irradiation and terminal thiol groups take an important function in the binding.

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We have investigated the effects of combined use of ultrasonic irradiation with NaClO on the growth of yeast cells and compared this effects with that of NaClO or ultrasound irradiation only. It has reported that the inactivation of yeast cells by ultrasonic irradiation. In this study, the growth activites about the bactericidal and bacteriostatic effect of the chemicals on the microbial cells. It was shown that ultrasonic irradiation (27.5kHz, 77W) had synergistic effect on inactivation of yeast cells by NaClO suggesting that ultrasonic irradiation would cause the membrane damage on yeast cells increasing permeability of the chemicals. However, when the processing order was changed, we did not obtain the synergistic effect in the bactericidal effect. In the sterilization of the microorganism, we found that the bactericidal effect is different when the processing order is changed.

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The ultrasonic inactivation method has been paid attention because it does not generate poisonous substance and heat. However the inactivation mechanism is complex and has not been clarified yet. The purpose of this study is to clarify the mechanism of the ultrasonic inactivation. The inactivation experiments were carried out by using E.coli and S.mutans with the different ultrasonic power at 500kHz and 10℃. In the case of the E.coli, change in the inactivation rate was observed at high ultrasonic power. However in the case of S.mutans, such change was not observed. The inactivation rate is proportional to the ultrasonic power as for both E.coli and S.mutans. The inactivation experiments with addition of the radical trap agent (t-butanol) were carried out. Then the inactivation rate decreased greatly. The above results indicate that the ultrasonic inactivation mechanism consists of two or more mechanisms and the main mechanism is inactivation of microorganism by the effect of OH radical.

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