Photosynthetic organisms such as plants produce more than 100 million tones of organic matter each year from the fixation of carbon dioxide. Biomass is solar energy stored in organic matter. The complex chemical composition of the vegetal tissues suggests various posibilities for their chemical processing. To find the best techniques is the key target in extraction technology. Among newer techniques used in extraction technology of biomass, sonication has proven to be beneficial for the yield and quality of natural products. This paper presents an insight into the mechanism of the ultrasonic enhancement of solvent extraction through the effect of ultrasound on the vegetal materials and some special reasons for employing ultrasound on extraction of biomass.

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超音波エネルギーを体の一部に集中させ、限局された部位で薬物を化学励起させる新しいTargetingも考案されている。ヘマトポルフィリン誘導体は本来光エネルギーで励起される物質で、現在臨床でこの性質を応用した癌の光化学療法がすでに実用化されているが、超音波エネルギーでも同様の励起作用があることが梅村らにより発見され、新しく音響化学療法(Sonodynamic Therapy)として注目される。ヘマトポルフィリン誘導体の超音波励起方法は超音波治療に全く新しい概念をもたらした。超音波は物理的な振動とともに物理化学変化を引き起こす性質があるため、初め毒性がない同薬物が超音波照射後Free Radicalを産生し癌殺傷効果が誘発される。さらにこの薬物の細胞親和性を利用することで特定の癌細胞を選択的に超音波で殺傷できることが注目され始めた。成人T細胞白血病細胞に超音波感受性薬物ポルフィーマナトリウムが選択的に取り込まれるため、音響化学療法で血液を処理すると白血病細胞のみが殺傷され、正常白血球は温存されることが最近の研究で明らかになった。また大腸癌の肝転移および乳癌の皮膚転移における音響化学療法の臨床有効例が学会で発表されており、本格的な臨床治験が今まさに開始されようとしている。

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Various organic compounds, such as butyric acid, dodecylbenzenesurfonic acid, chlorophenols, hydroxybenzoic acids, etc., were decomposed by ultrasonic irradiation (200kHz, 200W) from the viewpoints of wastewater treatment and to determine the reaction kinetics. The rates of degradation changed by the types of organic compounds. In the case of butyric acid, the rates of degradation were dependent on the pH of the irradiated solution: the rate was faster in the acid solution than in the neutral solution. This result was elucidated by the different hydrophobic intensity of butyric acid which was related to the proton dissociation of butyric acid. In the cases of aromatic organic compounds, the rates of degradation were also different among the compounds. The rates did not relate to the reaction rate constants. Taking into account unique reaction sites of cavitation bubbles, we discussed the relation between the physicochemical properties of organic compounds and the rates of sonochemical degradation. It was suggested that the hydrophobicity of organic compounds is one of the most important factors to determine the rates of degradation.

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Most of the organic hazardous substances dissolves readily in the organic solvents. It has been reported that the effect of ultrasonic cavitation is more intense for lower vapor pressure of the solvent. From these points of view, we tried to decompose trichloroethylene in a silicon oil, low-volatile and hydrophobic solvent, in order to find an effective treatment of hazardous substances. Trichloroethylene (10mM) was sonicated with 200 kHz in the 50mL of silicon oil. The decomposition ratio is less than 5% notwithstanding irradiation for 3 hours. Water was added to silicon oil for the formation of OH radical and the stabilization of Cl radical. However, the decomposition ratio did not improve. Trichloroethylene would be affinitive with silicon oil for its high lipophilicity, because its log Pow (Octanol/water partition coefficient) is 2.24. Therefore, trichloroethylene may be hard to vaporize and be pyrolyzed in the cavity. The organic hazardous substance may be decomposed efficiently in the organic solvents to optimize the hydrophobicity and the hydrophilicity of the solvent and the solute.

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We reported that membrane treatments used for ultrafiltration and microfiltration (MF) were enhanced in ultrasound field. Most of these researches were concerned with increases of permeate flux for their membrane treatment processes by the ultrasound irradiation. In the present work, hollow fiber MF membrane made of polyethylene (540VS, Mitsubishi Rayon), which had 80 mm length with 0.8 μm diameter, was used. The pore size of the hollow fiber membrane was 0.4 μm diameter and total surface area 0.01 m^2. The MF module having 140 mm hight and 100 mm width contained a bundle of 512 hollow fiber membranes and showed complete cutoff of 1 wt% of milk aqueous solution. The MF membrane module was used for incubation flow filtration using circular pump (Millipore XX80) and the filtration was operated under 60 kPa pressure. Ultrasound effect on enhanced membrane treatment process was measured under 28 kHz ultrasound (300W) onto the vicinity of hollow fiber microfiltration (MF). When the MF membrane module was placed behind ultrasound transducers on 4, 8 and 12 cm distance, the resultant permeation flux of the MF membrane was improved from the fouled membrane condition. The 28 kHz ultrasonic frequency and sound pressure emitted from the transducers was estimated with model pulse receiver (Model 5058PR) connected from immersion transducer probe (Panametrics V301). In the water bath, the probe was set on 120 mm depth with 1cm interval positions to obtain distribution of the 28 kH frequency intensity. Luminor chemi-luminescence was also determined by camera from top view of the water bath. The MF membrane permeate flux was drastically decreased by milk fouling for 30 min operation. At the filtration time for fouling, then water washing cleaning of polyethylene hollow fiber MF membranes was carried out within water bath of the sonic cleaner. In these processes, the recover efficiency of the fouled membranes was changed at different module positions. It was fond that the efficiency of ultrasound-washing was high at the 8 cm position and low at the 12 cm position. The 8 cm position was that the sound pressure was higher than that of 4 and 12 cm positions. Weakly observed in the region of 0-7 cm distance was in liminor chemi-luminescence, while the blue emission intensity was strong through the 8-12 cm behind position. These suggested that the enhanced membrane permeation was resulted mainly from high sound pressure of ultrasound. To future approach in ultrasound-membrane hybrid system, further study on mechanism of the ultrasound effect in the membrane treatment should be investigated more in future in view of standing wave and cavitation.

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An aqueous solution of dodecyl-benzenesulfonic acid sodium salt was ultrasonically atomized and liquid particles which were rich in surfactant were collected. Effects of surfactant concentration and KCl addition on the behavior of surfactant enrichment were examined. Interfacial tension was also observed at static conditions to discuss the trend of enrichment ratio in view of interfacial properties. For a mixture of the surfactant and de-ionized water, a high enrichment ratio was observed at lower concentration and the ratio dropped with increasing the surfactant concentration. Addition of KCl led to a significant enhancement of the enrichment ratio, and the ratio went through a peak on the plot against KCl concentration. The enhancement is interpreted as a result of an increase of surfactant adsorption due to charge neutralization of surfactant anions at gas-liquid interface. The salt addition lowers the cmc of the surfactant and micelles formation leads to a decrease in surfactant enrichment ratio.

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In an acoustic-gravity coupled field, particles aggregate at the equilibrium position, where the acoustic radiation force and sedimentation force are balanced. The aggregation position is determined by particle density and compressibility not by its diameter. This field is thus applicable to separation of particles based on materials. The acoustic-gravity coupled field was combined with the laminar flow perpendicular to the field; thus, flow separation of particles has become feasible. Elution profiles of polystyrene (PS) latex and PANVCMM particles were investigated using this system. PS showed two peaks at 1380 and 1600sec, while PANVCMM was eluted at 1180sec. These results indicated that PS particles were aggregated closer to the wall of the separation channel than PANVCMM particles; this was qualitatively ensured by theoretical consideration. Elution of a PS and PANVCMM mixture was also investigated. Peaks appeared at 1170, 1330 and 1610 sec. The first peak was due to PANVCMM particle elution, and the following two peaks were due to PS particles elution. The particles were separated by this separation system using acoustic-gravity coupled field and laminar flow. This novel particle separation method has potential to separate the porous particles (e.g. silica gel particle) by porosity, and will allow us to utilize this physical nature as a new particle separation parameter.

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To develop the ultrasonic non-invasive system for glucose monitoring in human body, the basic insonation effects were investigated on the mechanical force of bubbly sound field. A way was shown by means of Mason's equivalent circuit how to detect the Stress in water by a PZT sensor with a rubber baking. It was found that a Bubbly activated sound filed was generated beyond the threshold stress 0.2 M Pascal and its stress was magnified with the nonlinear waveform, apart from a sinusoidal one in weak case. Also, there appeared the 1/m sub-harmonics and their overtones. On the other hand, the same measurement was done on the sliced big's thigh meat. The corresponding waveform vs. time was complex but displayed the sub-harmonics. The resulting instantaneous maximum stress happened to be over 0.6 M Pascal.

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It is well known that cavitation effect of ultrasound is applicable to disinfection of the wastewater. Moreover, the combination of ultrasound and other techniques is interesting to develop efficient disinfection system. To do this, detail study on the growth activity of microorganisms treated by ultrasonic irradiation should be important. However the colony counting and the turbidity measurements of the growth medium are insufficient to evaluate the quantitative and qualitative change of microbial growth. In this study, to evaluate the growth activity of the yeast cells, calorimetric analysis was carried out in addition to the colony counting. Using a heat conduction type multiplex calorimeter equipped with 24 calorimetric units the heat evolution on the growing of treated yeast cells was detected in the form of growth thermograms. It can provide not only the quantitative information for the microbial growth activity but also the characteristic features about the bactericidal and bacteriostatic effect due to the chemical or physical action to microorganisms. It was shown that the longer irradiation time, the more peak shift toward a longer incubation time, which means bactericidal effect of ultrasound. On the other hand, growth rate constant of yeast was decreased according to increase of the concentration of NaClO.

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Volume dependence of chemical effect has been investigated for laboratory scale reaction vessel. However, for sonochemical reactor designed for practical usages, few studies have been carried out. In this work, we constructed the cylinder type sonochemical reaction vessel whose volume was in 1 dm^3 order and investigated the effect of liquid height and liquid surface on the chemical effects of the ultrasound. The height of the reactor was 150 cm and the inner diameter was 7 cm. The Langevin type transducer provided from Honda Electronics Co. Ltd. was attached at the bottom face. The driving frequency was 128.9 kHz and the driving voltage was ca. 200V. A moving reflector can be attached the other side of the surface. The chemical effect was estimated by the concentration of I_3^- produced from the sonochemical oxidation of the aqueous solution of the potassium iodide. At the liquid height below about 25 cm, the concentration of I_3^- strongly depended on the liquid height in related with the standing wave condition. The concentration of I_3^- produced by the sonochmical oxidation for the reaction vessel without reflector was larger than that with reflector. We took the photograph of luminol fluorescence induced by the ultrasound with and without reflector. The contrast corresponding to the node and anti-node of the standing wave was observed. The contrast for the reaction vessel with the reflector was stronger than that without the reflector. The brightness of photograph without the reflector was higher than that with the reflector. The vibration of the liquid surface was observed for the reaction vessel without the reflector. This vibration may affect the standing wave condition and thus gives the different results with or without reflector. When the liquid height was higher than 40 cm, no distinct difference was observed with ant without the reflector.

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Computer simulations of bubble oscillations in liquid water irradiated with ultrasound are performed for various acoustic amplitudes and various ambient pressures. The model used in the present computer simulations are described in Refs.[1-4]. In the computer simulations, effect of non-equilibrium evaporation and condensation of water vapor at the bubble wall and that of chemical reactions of gases and vapor inside a bubble are taken into account. The computer simulations are performed under the experimental conditions described in Refs.[5,6]. The ambient bubble radii are assumed to be the ones theoretically calculated in Ref.[7]. The oxidants such as OH radicals, O radicals, H_2O_2 molecules, and O_3 molecules are created from water vapor inside a heated bubble when a bubble collapses strongly. They are dispersed into the liquid and solutes are oxidized by the oxidants, which is called sonochemical reactions. The computer simulations have revealed that there exists the optimum bubble temperature, which is about 5,500 K, for the production of the oxidants inside an air bubble because at higher bubble temperature the oxidants are strongly consumed inside a bubble by oxidizing nitrogen. For an oxygen bubble, on the other hand, the amount of the oxidants created inside a bubble increases as the bubble temperature at the collapse increases because nitrogen is absent.

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The studies for sonochemical reactor with dual-transducer have been conducted in recent years. The aim of these studies is to gain synergism which exceeds the effects of individual frequencies with superposition of dual-frequency. However the mechanism and conditions to do it are still unclear. In this study, the effect of dual frequency sonication on sonochemical reaction rate is examined. The production yield of I_3^- in aqueous solution of 0.1 M KI under sonication is used as a measurement of the sonochemical effects. To irradiate the solution with dual-frequency ultrasonic waves, the transducer for standing wave in frequency range of 24.1 kHz to 1170.0 kHz and the horn-type transducer (20 kHz) were used. We found that there is the synergetic effect at the frequency of the standing wave under 100 kHz and not in the range of 100 kHz to 500 kHz. We will discuss influence of harmonics and liquid flow on the synergetic effect.

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When the ultrasound irradiates into water, the hydric and hydroxyl radicals genrerated. It has been reported that many sonochemical reactions are attributed to these radicals. In order to apply sonochemical reaction effectively, the estimation of hydroxyl radical reaction rate is important. In this study, the generation rate of hydroxyl radical in water is simply modeled and the simulation of sonochemical reaction is done. By fitting simulation results into experimental data, the generation rate constant of hydroxyl radical from water is estimated. Methyl orange aqueous solution, which is decomposed by hydroxyl radical, is used as sample. From the results of analysis, the hydroxyl radical concentration in solution approaches a steady value in the early stage of reaction. The steady value of hydroxyl radical concentration depends upon methyl orange concentration. It is considered that the model must be taken into account the reation between hydrogen peroxide and solute.

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Single sonoluminescing bubble dynamics in high concentrated aqueous alkaline halide solutions is studied using a high speed framing camera. We observed high intensity single bubble sonoluminescence(SBSL) from an unstable bubble under higher acoustic pressure and concentration. In this condition, we got a photograph of bubbles split into a main sonoluminesing bubble and some daughter bubbles using a high speed framing camera. It is known that an unstable bubble comes from split daughter bubbles under lower acoustic pressure, but we got that under higher one. It is a new interesting phenomenon. The dynamics of a single sonoluminescing bubble in concentrated aqueous NaCl and KCl solutions under the range of 0.5 mol/l to 5 mol/l below saturation is studied using a high-speed framing camera. The luminescence intensity increased for higher acoustic pressures and higher concentrations, as expected, but remarkable increase was observed when the pressure was so high that the bubble motion became unstable. In this mode of dynamics, the bubble was splitting into a main sonoluminescing one and some daughter ones, as observed with the camera. Such unstable behavior is characteristic of the bubble dynamics around the lower sonoluminescience threshold for acoustic pressure, but our finding suggests that for dense aqueous solutions there exists another regime where the bubble is unstable but more luminous.

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Carbon dioxide (CO_2), carbon monoxide (CO) and hydrogen (H_2) were evolved from a sodium hydrogencarbonate (NaHCO_3) solution by sonolysis. In liquid phase, hydrogen peroxide (H_2O_2) was also detected. The higher concentration of NaHCO_3 was applied, the higher yield of CO_2 was observed in early stage of sonication. In the case of H_2, however, the yield decreased with increasing concentration. The yield of CO had the maximum value of concentration. The reaction paths are follows; 2NaHCO_3 → CO_2 + Na_2CO_3 + H_2O …(1) H_2O → ・H + ・OH …(2) ・H + ・OH → H_2O …(2)-1 ・H + ・H → H_2 …(2)-2 ・OH + ・OH → H_2O_2 …(2)-3 CO_2 + H_2 → CO + H_2O …(3)

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Various phenolic compounds and polyphenols were produced using ultrasonication in the hydroxylation reaction. In the aqueous solution, ultrasonication was useful for producing hydroxyl radical from water. Hydroxylation was also known in the production via epoxy compound. In the method via epoxy compounds high pressure or strong acidic conditions are necessary. Various monophenols substituted with alkyl and methoxy groups were reacted with hydroxyl radicals producing under ultrasonic irradiation(Sus-4005C, 50W, 40kHz and Kaijo, 200kHz) for 12-24h to give the corresponding polyphenolic compounds. When no irradiation of ultrasound was done in this reaction, no reaction was found. The effect of irradiation of ultrasound accelerated the hydroxylation of phenolic compounds. In the case of using cupric acetate in acetic acid, acetoxylation was also accelerated under ultrasonication. [chemical formula][chemical formula][chemical formula]

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In an aqueous solution, ultrasonic irradiation is known to produce hydrogen peroxide which oxidizes thiols to disulfides. By utilizing the reaction, we designed novel functional molecules with ultrasound-induced structural changes. Two functional molecules, 1 and 2, were prepared by introducing alkyl thiol moieties into diaminoacridine and diaminopyridine, which were known as DNA intercalators. [chemical formula][chemical formula] By ultrasonic irradiation for several hours under alkaline condition, linear functional molecules were converted into cyclic ones with intramolecular disulfide bond. Such structural changes were confirmed by ^1H-NMR method. Chemical shifts of α-protons to thiol groups shifted to downfield and multiplicity changed from double doublet to triplet. These functional molecules have the potential for cancer treatment. After intercalation into DNA and successive ultrasonic irradiation, functional molecules can be expected to form irreversible complexes, which may cause damages on DNA duplication.

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Correlation between the number of cavitation bubbles and sonochemical reaction in an ultrasonic standing wave field at various contents of dissolved air is studied experimentally with light scattering by cavitation bubbles and absorbance with iodine liberation from KI aqueous solution by ultrasonic irradiation. When a thin light sheet finer than half of wavelength of sound is introduced into the cavitation bubbles at an antinode of sound pressure, the scattered light intensity oscillates. The peak-to-peak light intensity corresponds to the number of the bubbles which contribute to the sonochemical reaction because the radius for oscillating bubbles at pressure antinode is restrictive in a certain range due to the shape instability and the action of Bjerknes force that expels from antinode bubbles larger than the resonant size. It is shown that, as the air content varies, the tendency in the peak-to-peak intensity is in good agreement with the tendency for the yield in the sonochemical reaction of the liberation of iodine from a KI solution under the irradiation of ultrasound.

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We had succeeded in developing the experimental setup to keep a stable sonoluminescence for several tens of hours, which enabled us to analyze the reaction product from the single bubble quantitatively. In this work, to elucidate chemical effect from the single bubble we analyze the produced amounts of nitrate and nitrite ions from both in water and in aqueous solution of NaBr. In the case of water, the concentrations of two ions increase linearly with irradiation time. The formation rate for nitrate ion was 2.3×10^<-8>mol/(l・h), while nitrate was 2.4×10^<-8>mol/(l・h). The concentration ratio of nitrate and nitrite ions was 1:1 within experimental errors. The number of nitrite ions are 7.1×10^6per cycle, which is comparable to the value (3.7×10^6per cycle) reported by Suslick. In the case of aqueous solution of NaBr, the amounts of nitrate and nitrite ions increase with increasing the concentration of NaBr, but ratio of nitrate and nitrite ions is kept 1:1, which is the same as that without NaBr. This suggests that the addition of NaBr does not affect reaction mechanism.

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マルチバブルソノルミネッセンスの測定は数十kHzの低周波ではよく行われるが、MHz程度ではキャビテーションが起こりにくいことから測定例は少ない。我々は1MHzの超音波による純水およびルミノール溶液からのソノルミネッセンスを観測した。光学的DC計測、パルス計測の結果について報告する。

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The droplet diameter distribution and concentration characteristics in ultrasonic atomization were experimentally studied. The samples were aqueous solutions of methanol, ethanol and 1-propanol. The diameter distribution of atomized droplet showed the normal one, and the median diameter and standard deviation were expressed by means of the ultrasonic condition and the liquid properties. The concentration characteristic in ultrasonic atomization was analyzed by using the model of shell and core of the atomized droplet, where the former and latter consist of solute and solution, respectively. The surface solute amount in droplet multiplied by the molecular volume increased with increasing content of solute in bulk liquid and was independent of alcohol kinds. The liquid flow rate and the solute molar fraction in accompanied liquid were estimated from the diameter distribution and the surface solute amount.

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The degradation of methyl orange in water was kinetically investigated using sonolysis and photocatalysis, employed either separately or simultaneously, with titania coated silica-gel particles as photocatalysts. The photocatalytic degradation rate of methyl orange was dependent on the particle size of photocatalysts; smaller catalyst particles around 5μm exhibited 5 times larger activity than the porous particles around 1-5mm. The degradation rates by sonolysis were negligible at 49kHz and increased to the order of the photocatalysis with the sonication at 178kHz. Simultaneous irradiation of ultrasound and UV light for photocatalysis increased the degradation rate about to the sum of the individual processes but the significant synergistic enhancement was not observed.

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Environmental problems arise from the pollution of ground water and soil by propyzamide 3,5-dichloro-N-(3-methyl-1-butyn-3-yl)benzamide, which is a popular herbicide. To decompose propyzamide aqueous solutions containing propyzamide and TiO_2 particles was irradiated by light. The photocatalytic decomposition was accelerated when the solution temperature and pH were high. The temperature dependence was due to the adsorption processes of propyzamide on the TiO_2 particles. The decomposition was further promoted by addition of H_2O_2 because of its effective electron-trapping and generated ・OH which was available to decompose propyzamide. Although no propyzamide was detected in the solution after the irradiation time of about 20 minutes, the decomposed intermediate compounds still remained. In order to mineralize completely propyzamide, simultaneous irradiation by light and ultrasonic waves was carried out. The hybrid effect of the irradiation by light and ultrasonic waves in conjunction with H_2O_2 was first confirmed to achieve the complete mineralization of propyzamide.

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Perfluorooctane sulfonate (PFOS: C_8F_<17>SO_3^-) and perfluorooctanoic acid (PFOA: C_7F_<15>COO^-) are wildely used in a variety of applications, including polymer additives, lubricants, fire retardants and suppressants, pesticides and surfactants. Furthermore, these compounds are metabolically and photochemically inert, resisting both biotic and abiotic degradation. As a consequence, they have been detected in wildlife, such as fish, birds, and mammals, from urban and remote areas around the world. Recent studies have characterized trace levels of the compounds in the serum of non-occupationally exposed human. In this study, we investigated the decomposition of PFOS and PFOA in aqueous solutions by sonochemical action based on the rates, products and possible mechanisms of the sonochemical degradations. We proposed the possible mechanisms on the basis of the ions detected by ESI/MS and ion chromatography. The formation of PFOA during the PFOS degradation may be due to oxidation followed by dissociation of the SO_3^- group, and the dissociated SO_3^- group will be oxidized to SO_4^<2-> by sonication. The generated PFOA would undergo shortening of the perfluoro-carbon chain caused by the repetition of the COOH dissociation and the oxidation of the generated ions or radicals of the perfluoro-carbon. The formation of CF_3(CF_2)_6SO_3^- and CF_3(CF_2)_5SO_3^- from PFOS would be due to the reaction at the CF_3 group in PFOS. However, there are no examples for the sonochemical reaction of the trifluoromethyl group, and the detailed mechanism is not clear at this stage.

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Sonochemical degradation of p-chlorophenol, bisphenol A and p-n-octylphenol was performed, while it was compared with electrolytic degradation. Under the condition where the sonolysis of p-chlorophenol was almost the same rate as the electrolysis, bisphenol A was decomposed much faster by the sonolysis, in contrast to the faster degradation of p-n-octylphenol by the electrolysis. The ultrasound was irradiated with a concave transducer at 500 kHz and 25℃ liquid temperature under argon. The preliminary experiments clarified that in our ultrasonic irradiation system the degradation rate of p-chlorophenol at 500 kHz was slightly faster than that at 250 kHz. The rates were faster in the following order of ambient gas: air, oxygen and argon. The rate in 25℃ solution was faster than that in 5℃ solution. The electrolysis was performed using platinum electrodes for both anode and cathode at the constant current of 10 mA. The rate of electrolysis increased with the current as expected. On the other hand, sonochemical reactions depend on many experimental parameters. Therefore, the obtained order of the degradation rates between the sonolysis and electrolysis should not be always valid. The molecular approach to the degradation mechanism should resolve the complexity of our results.

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Synthesis of oxindol and 3-oxo-tetrahydroisoquinoline derivatives has attracted much attention of synthetic organic chemists due to their biological activities. On the other hand, we have shown that anodic generation of carbocations at the α-position to the sulfur atom by using an innovative electrolytic system, and these intermediates were successfully trapped by fluoride ions to give various fluorinated compounds. Since anodic oxidation of sulfides has been applied for efficient partial fluorination reactions via the fluoride ion mediated Pummerer type mechanism, we became to be interested in determining whether the electrolytic approach using a fluoride ion mediator might also provide an effective pathway to intramolecular carbon-carbon formation. The starting materials 1 used in this work were prepared from α-phenylthioacetyl chloride and the corresponding amines in THF or CH_2Cl_2 in the presence of Et_3N or K_2CO_3 (Scheme 1). Constant current electrolysis was carried out in acetonitrile containing Et_3N・HF as both a supporting electrolyte and mediator in an undivided cell equipped with platinum plates (2 x 2 cm^2) as an anode and cathode. In the case of electrolysis under ultrasonic irradiation, ultrasonic horn was set vertically 1.5 cm apart from the working electrode (Fig. 1). Electrooxidation of α-(phenylthio)acetamides using a fluoride ion mediator lead to an intramolecular cyclization i.e. C-C bond formation to give the corresponding oxindol and 3-oxo-terahydroisoquindine derivatives. In these cases, a considerable amount of α-fluorinated compounds 3 were formed as by-products, therefore, the yields of cyclic compounds were not satisfactory. However, in the presence of ultrasonic irradiation, the cyclization reactions were accelerated greatly and the desired cyclic compounds 2 were obtained in good yields [Table 1]. The effects of ultrasonic irradiation on the product selectivity and yields were studied in detail [Fig. 2] and the reaction mechanism was proposed. In summary, ultrasonic irradiation can accelerate the fluoride ion mediated anodic cyclization of sulfides to give the desired cyclic products, oxindol and 3-oxo-terahydroisoquindine derivatives in good yields. The local heating effect by ultrasonic irradiation seems to be more advantageous than usual heating. Thus, the electro-synthetic method using ultrasound is considered to be an effective and clean organic synthetic approach.

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We have proposed a method to fabricate fiber probes for near-field optical microscopy based on electroless plating under ultrasonic irradiation. The method involves four steps: (A) chemically etching a high GeO_2 doped silica fiber in a buffered HF solution with a volume ratio of 40%NH_4F : 50%HF : H_2O= 10:1:1, (B, C) the surface activation by immersing in 1.0 g/dm^3-SnCl_2 and 5.0 mg/dm^3-PdCl_2 aqueous solutions, respectively, (D) electroless nickel plating under ultrasonic irradiation. Using 1MHz-PZT plate as the ultrasonic generator for this method, we succeeded in fabricating a near-field optical probe having a submicron-sized tip protruding from a nickel film with reproducibility.

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Electrodeposition of copper on a stainless steel cathode was performed by applying the voltage as pulse waves of various frequencies. The pulse electro-deposition method was confirmed to be effective for getting flat and smooth surface of the copper film. Increasing the frequency of the pulse wave applied, the decreasing in the roughness of the surface was observed. The more decrease in the surface roughness was obtained by combining ultrasound agitation to the pulse electro-deposition. The sonication effect on the reduction in the surface roughness can be explained by the decrease in the thickness of the diffusion layer of copper ions near the electrode.

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We prepared Au/γ-Fe_2O_3 composite nanomaterials by sonochemically reducing Au(III) ions employing no stabilizer in the aqueous solution to form stable Au nanoparticles and allowing them to attach onto the surface of γ-Fe_2O_3 particles. Size of the formed Au nanoparticle depended on the initial concentration of Au(III) ions. The number of the Au nanoparticles, supported on each γ-Fe_2O_3 particle was controlled by changing the relative amounts of Au(III) ions and γ-Fe_2O_3 particles. The composite nanomaterials exhibited a high affinity with glutathione, a tripeptide with mercapto group so that separation and manipulation of glutathione in aqueous solutions could be performed by application of external magnetic field. Because the surfaces of the Au nanoparticles were not shielded by any stabilizers, or naked, sonochemically prepared Au/γ-Fe_2O_3 composite nanomaterials seemed to show stronger affinity to the glutathione than those by the radiochemical method.

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It is known that nano-size metal particles have different character and functions from bulk-size metal. With irradiation ultrasound to aqueous solution of noble metal and transition metal cations, metal cations were reduced to metal nanoparticles. We have suggested three different reduction pathways of metal ions under sonication: (i) reduction by H atoms, (ii)reduction by secondary reducing radicals formed by hydrogen abstraction from organic additive with OH radicals and H atoms, (iii)reduction by radicals formed from pyrolysis of the interfacial region between cavitation bubbles and the bulk solution. In this investigation, the solution composed of Fe particles, K_2PtCl_4 solution, and PEG or SDS was sonicated for 2 hours. Products were Fe-Pt bimetallic particles. They have as high hydrogenation catalyst activity as Pt particles

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Fe_3O_4 nano particles were synthesized at a variety of initial [Fe^<2+>] (0.001〜0.1M) with ultrasonic treatment. Two types of sonication were used in this work; a traveling wave type reactor and a standing wave type reactor. At initial [Fe^<2+>]=0.01M, it took 12h to complete the reaction by mechanical stirring. On the other hand, it took only 1h by ultrasonic irradiation. We found that using ultrasonic irradiation effectively reduced the reaction time. Particle sizes synthesized by traveling wave were reduced by increasing the output power of ultrasonic. The cavities were thought to be nucleation sites, and the number of cavities was increased with an increase in the output power. Therefore, in the traveling wave process, it was possible to control particle sizes by changing output power. In the standing wave process, it was possible to synthesize Fe_3O_4 at initial [Fe^<2+>]=0.001M. This was possible by neither mechanical stirring nor traveling wave process. In the traveling wave process, intensive macroscopic streaming by direct stream made a decrease of super saturation and nucleation was inhibited. In the standing wave field, on the contrary, because the whole solution had moderate microscopic streaming, super saturation was not decreased and nucleation was issued. Therefore, the standing wave process was appropriated to a low concentration ([Fe^<2+>]=0.001M) reaction. However, particles size distribution by the standing wave process in the high concentration ([Fe^<2+>]=0.01〜0.1M) was larger. Therefore, the traveling wave process was better suited for high concentration because particle size distribution was smaller. We must select the reaction process depending on the purpose.

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Sonochemical polymerization induced by applying ultrasound to benzene derivatives has been studied. Irradiating ultrasound to o-dichlorobenzene with solid particles such as zinc, its chloride, or nitrate produced various nanoparticles. In the case of using zinc nitrate, solid needle-like particles were obtained, when zinc metal and zinc nitrate were co-doped, hollow needle-like (tubular) particles were obtained. It is bound from the diffraction pattern that tubular particle has a polycrystalline structure, which could not be identified up to now. EDS analysis showed that the tubular particle contained Zinc element. When the particles were produced, Zinc element might be attracted inside or outside of the tubular particle. Various irradiation time and content of solid particles were tried, there might exist optimum parameter that increase a ratio of tubular particles respectively. In this research, the best parameter of the synthesis was; Irradiation time = 5 minutes Zinc: Zinc nitrate = 0.37wt%: 0.37wt% for o-dichlorobenzene.

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General factors to characterize a starting solution for wet-chemical synthesis are solvent species, solute species (reagent), and their ratio (= concentration). No other factors than these three are scarcely noticed. Here we focus our attention to the forth factor, the "age" (standing time after preparation) of it. It is well-known that monodispersed spherical particles can be prepared by controlled hydrolysis of metal alkoxides (what is called Stober method). Although the precise control can be made by adjusting temperature, concentration, and pH, there may be an unexpected change of the particle size or an undesirable degradation of monodispersibility due to an unknown reason. In this research we introduce the new parameter, the age of starting solution, into an optimized synthesis of spherical particles. In addition, soft sonication (weak irradiation of ultrasonic vibration) is proposed for more efficient aging. In the synthesis of spherical silica with starting solutions of different age, we demonstrate the following effects of aging on the precipitation behavior; (1) increase of the incubation period for precipitation, (2) increase of the final particle size, and (3) improvement of the monodispersibility. The increment of the final particle size as a function of aging time is twice larger in the case of soft sonication than in the case of normal aging. We assume from these results that a starting solution, especially that including an organic solvent with low dielectric constant, may be inhomogeneous at microscopic level just after the preparation. In the present case, the as-prepared solution of tetraethylorthosilicate (TEOS) and ethanol may involve some clusters, which may cause unfavorable nucleation to degrade the monodispersibility. It is inferred that those "clusters" can be broken or dispersed by aging for days or weeks. Reduction of the aging period by soft sonication would be due to high frequency (〜tens of kHz) and small amplitude (〜nm) of the vibration.

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Mechanism of ultrasound-mediated transfection has not yet been completely elucidated, though, it is considered that mechanical stress generated with inertial cavitation may be playing a pivotal role and that cells may uptake DNA while cell membrane is repaired after disruption by the stress, resulting in transfection. Since cell membrane is the first and possibly the most important barrier for establishing the transfection, we examined effects of known membrane modifiers such as a local anesthetic, lidocaine, and different temperatures on the transfection. We observed the effect of lidocaine (0.01, 0.1 or 1.0 mM) and different temperatures (7, 20, 37, 42 or 44 ℃) on USMGT (1 MHz, 3.6 W/cm^2 (I_<SATA>) and 20 s exposure) in the presence of Levovist (10 mg/ml). At 20 h after sonication, transfection efficiency was evaluated by luciferase assay. Membrane fluidity was examined by fluorescence polarization measurement. Cavitational activity was measured by ESR spin trapping with 5,5-dimethyl-1-pyrroline N-oxide. The number of cells transfected with the GFP gene was counted under a fluorescence microscope. Lidocaine (1 mM) and heat (42-44℃) significantly increased luciferase expression approximately 18-fold and 19-fold higher than Levovist only. Both treatments were shown to increase membrane fluidity; in addition, heat enhanced a cavitational effect. It was confirmed by an experiment using the GFP gene that increase in luciferase expression was due to the increase in number of cells. These results indicated that not only strengthening cavitation occurrence but facilitating modification of cell membrane are useful for enhancing transfction efficiency that has been pointed out to be modest in the case of the one by ultrasound.

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