Ultrasound can generate acoustic cavitations, which is the formation and violent collapse of micro bubbles or gas cavities within a liquid. The collapse of the cavities generates the energy for chemical and mechanical effects. The temperature and pressure generated from the collapse in water have been estimated to be over 5000 K and 2000 atm, respectively, which is high enough to dissociate water molecules into primary hydrogen radicals (H・) and hydroxyl radicals (OH・) in cavitation bubble. Hydrogen peroxide (H_2O_2) is formed by the recombination of hydroxyl radicals (OH・) during the sonolysis of aqueous solution. These facts indicate that one-step synthesizes of nanoparticles and polymer in the form of composite can be possible in aqueous solution using ultrasonic irradiation. In this work, we report a successful one-pot synthesis of Au-NPs/PPy nanocomposite by using ultrasonic irradiation. Hybrid nanocomoposite composed of gold nanoparticles (Au-NPs) and polypyrrole (PPy) was prepared by ultrasonic irradiation of aqueous HAuCl_4 and pyrrole solution in the presence of stabilizer such as poly(N-vinyl-2-pyrrolidone) (PVP).

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The formation of cavitation bubbles is the significant process for the sonochemical reactions. Pyrolysis in the cavitation bubbles and the radical-initiated reactions on the interfaces and in the bulk liquid are known to be the predominant decomposition pathways. Hydrophobic compounds, which are easily concentrated on the surface of the bubbles, are present in a higher concentration compared with in the bulk liquid. Such compounds are susceptible to the decomposition by the OH radical-initiated reaction on the interfaces between the cavitation bubbles and the bulk liquid, in addition to the pyrolytic reaction. In this work, various monocyclic aromatic compounds were irradiated by 200kHz ultrasound for 3 minutes and the relationship between their initial degradation rates and two hydrophobic parameters, LogP(water-octanol partition coefficient) and surface excess concentrations, was investigated. LogP values were found as the parameters to predict the sonolysis rates of hydrophobic compounds.

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Through the phase-separation system, lignocellulosics (western hemlock < Tsuga heterophylla > and unbleached mechanical pulps) were converted and separated to lignin-based polymers (lignophenols) and hydrolyzed carbohydrates. This system composed of phenol derivatives and a concentrated acid includes a simple stirring operation for about 60 minutes at ambient temperature in open system. To improve and control the phenolic/aqueous phase-separation reaction, the ultrasonic energy was applied to the reaction system. The ultrasonication greatly accelerated the hydrolysis of carbohydrates and the phenol grafting to native lignin to give lignophenols. The yields of ligno-p-cresols, especially from pulps, were increased dramatically at the early stage of the treatment. The resulting ligno-p-cresols had almost the same structural properties.

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Single-bubble sonoluminescence (SBSL) in aqueous sodium chrolide (NaCl), lithium chrolide (LiCl) and lithium bromide(LiBr) solutions ranging from 0 M to 5 M concentrations were studied. The SBSL intensity was increased with concentration in each solution, as expected. In LiBr solution, the intensity was higher than the other solutions. In our previous study, we found that the SBSL intensity increases in aqueous alkaline haide solutions, but we could not give any complete explanation for the result because we also have to take into account effects of increase in surface tension, viscosity, density and so on. The present result may indicate that alkali salt reduces vapor pressure in an oscillationg bubble. It is known that larger halide anions in alkali salt solutions prevent water molecules from diffusing. Therefore the vapor pressure is reduced in water and air interface. Previous SBSL studies show that the SBSL intensity increases for lower vapor pressure in the bubble. We conclude that the Br anion, which is larger than Cl anion, reduced the vapor pressure more in the bubble, and enhanced the SBSL intensity.

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Vegetable oils are produced form plants, their burning leads to a complete recyclable CO_2. The oil use as diesel fuel was limited due to its high viscosity (near 10 times of the gas oil). In order to adapt the fuel to the existing engines the vegetable oils had to be modified. The transesterification of vegetable oil with short-chain alcohols, in the presence of base- catalyst, by means of low frequency ultrasound was studied to produce clean fuel for global warming and emission of air pollutants. Rapeseed oil was converted to ethylester by transesterification with ethanol in the presence of potassium hydroxide (KOH) as catalyst. Thirty grams (0.03mol) of rapeseed oil was added 8.52g (0.18mol) of ethanol dissolved 0.03g of KOH, and mixed at 40℃ by ultrasonic irradiation at 19.5kHz or mechanical stirring at 500rpm. Fig. 1 shows the experimental set-up for ultrasonic irradiation. Samples were taken 1 mL and neutralized to add 0.1 mL of acetic acid to stop the reaction. Ethyl ester (ethyl oleate) in the samples were analyzed by gas chromatography with flame ionization detector. Fig. 2 shows the comparison of sonication and stirring. In the samples reacted at 20〜30mm, ethyl ester yield was 48〜49% by sonication and 40〜43% by mechanical stirring. The higher yield of methyl ester by sonication is assumed to result from vigorous mixing by ultrasonic vibration.

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There are various types of ultrasonic wave generators being used for cleaning purposes and , by proper selection and application of using ultrasonic frequencies, outputs ,etc., fitting to the purposes, upon full understanding of the characteristic and features of respective types of ultrasonic wave generators, it beeomes possible to carry out efficient cleaning works. Behaviors of ultrasonic waves in the inside of fluids include cavitations, acculeration, etc., and these behaviors are indispensable for ultrasonic cleaning and, moreover, they are being closely eonnected with the dissolved gasses in the fluid.

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For the scale-up of sonochemical reaction to practically useful size, we investigate the effects of the reaction parameters and conditions on the sonochemical reactivity. Two reactors are used in this experiment. One is quartz bath with the size of 175×65×45mm which has 1MHz transducer. Ancther is SUS bath with the size of 220×140×200mm which can set various transducers at bottom and sidewall. Potassium Iodide (KI) and Methyl Orange (MO) solution are used to investigate the sonochemical reactivity. Acoustic pressure is also measured with the reactivity. We have found out the following effects on the sonochemical reactivity 1. Reactivity increases linearly with the concentration of oxygen in the water. 2. Reactivity does not depend on the reflect position of ultrasonic wave. Possibly reaction takes place only near the transducer and the reflector. 3. Free surface reflection is higher reactive than fixed reflector at same electric current. Also the acoustic pressure is lower and the input electric power is higher. 4. Reactivity and acoustic pressure increases linearly to the electric current, but limited to the saturation, however the electric power is not limited and keeps increasing. 5. Reactivity decreases as frequency increases at same acoustic pressure from 300kHz to 1MHz.

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The effects of ultrasound originate primarily in acoustic cavitation. The cavitation bubbles collapse violently enough to lead to interesting chemical effects, known as sonochemistry. There is a great need to relate the efficiency of sonochemical reaction to the energy of ultrasonic irradiation used to produce them. In this paper, three OH radical dosimeters, Fricke dosimeter, terephthalate dosimeter and iodide dosimeter are compared from the analytical point of view. The dosimeters based on photometry, i.e., Fricke and iodide, produced reliable and reproducible results, but the sensitivity is not enough for a special applications, such as a chemical monitoring of single bubble cavitation. The dosimeter based on fluorometry, terephthalate dosimeter, offered high sensitivity, 1.2 × 10^<11> molecules ml^<-1>. The effects of some experimental parameters in sonochemistry, i.e. solution temperature and the dissolved gas species, were evaluated with the dosimeters.

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It is very important that the researcher understand the process of development for industrial equipment. In order to understand the process, I want to show the sample of development case. During development of equipment for groundwater polluted by VOC(Volatile Organic Compound), I could not apply the ultrasound reactor. Because the size and decompose ability of reactor were so small to apply industrial scale. But the ultrasound reactor could decompose VOC safely. So I made process design as follows. First I arranged the system of separation of the VOC dissolved in groundwater to gas phase by means of evaporation and degassing in vacuum state. Second the condensate water polluted VOC was treated by ultrasound reactor and the VOC in gas phase was decompose by heat reaction. The amount of condensate water was very small such as 1% of feed water. The performance of new equipment is excellent. Polluted water of PCE, TCE ,cis-1,2-DCE ,Benzene ,etc could treat approx. 10mg/L to 0.0lmg/L without any chemicals ,new waste ,hazardous byproducts and with energy saved. The researcher has to pay attention to describe in the paper as follows items. 1. Heat and mass balance. 2. The way of scale up. 3. Energy consumption of ultrasound. 4. The impact against environment

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By using ultrasonic irradiation an artificial carbon recycling system like photosynthesis in nature was constructed. Sonication products of NaHCO_3 solution were CO_2, CO, H_2, O_2 and H_2O_2. CO_2 was thought to be produced from NaHCO_3 by a thermal reaction. CO was formed from CO_2 produced by sonochemical reduction. H_2 and H2O_2 were sonication products from water. O_2 was mainly formed from CO_2 by the direct deoxidization in a cavity. In this presentation, the formation of CO was mainly discussed. It was thought that there were two kinds of CO_2 reduction processes. One was reduction of CO_2 by H_2 which came from H_2O as shown in equation (1). The other was the direct decomposition in a cavity as shown in equation (2). In order to examine the reduction process of CO_2, the ratio of O_2 to CO was confirmed. In the case of direct decomposition such as equation (2), the ideal ratio has to be 0.5. When NaHCO_3 was used as starting material, the ratio was near 0.5. CO_2 gas was used as starting material, on the other hand, the ratio did not attain the stoichiometric value. The latter case occurred the reduction of CO_2 using by H_2 or H radicals; i.e. equation (1). 2NaHCO_3→CO_2+Na_2CO_3+H_2O CO_2+H_2→CO+H_2O…(1) 2CO_2→2CO+O_2…(2)

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Water, supercritical fluid and ionic liquid have been used as alternative media for organic solvents so far. In particular, water is the most ideal medium for electrolyses from aspects of environmental pollution, safety and operational costs. However, many organic substrates are generally water-insoluble. Recently, some research groups reported that electropolymerization of monomers like thiophene derivatives having low solubility in aqueous solutions effectively proceeded using microemulsion [1,2]. This approach is quiet interesting, but the use of surfactants as emulsifying agents results in a serious problem such as the complication of its separation from polymer materials. Meanwhile, it is well known that ultrasonic dispersion provides stable emulsion in an aqueous medium [3]. Furthermore, droplets size go up to nano scale. Therefore, a direct electron transfer between an electrode and droplets can be expected. In this work, we carried out electropolymerization of 3,4-ethylenedioxythiophene (EDOT) as a thiophene derivative from an aqueous solution emulsified by ultrasonication without any surfactant. As a result, the electropolymerization of EDOT proceeded smoothly by this method. In addition, it is found that large grains were deposited on the anode substrate.

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We suggest the possibility of a continuous treatment method for gaseous organic pollutants in liquid phase. Among these pollutants, toluene was selected as hard to dissolve in water and formaldehyde as intermediate water soluble compound. In this study, sonophotocatalytic reaction system was investigated for simultaneous collection and degradation of these pollutants in a fluorocarbon (FC) / water emulsion solvent. Toluene is directly pyrolyzed inside the cavities generated by ultrasound and is also degraded by reaction on the interfaces with the OH radical generated by photocatalytic reaction. Formaldehyde reacted in water phase with H_2O_2 and the OH radicals generated by ultrasound and photocatalysis. And both organic pollutants were decomposed in high rates. It was the results show that water soluble compounds as well as hard soluble compounds can react efficiently in the different phases with this method, as it depends on characteristic of pollutant. It was demonstrated for the simultaneous degradation of toluene and formaldehyde in this study.

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Introduction Titanium dioxide in the rutile-pellet form was used as a catalyst in the ultrasonic irradiation system to generate hydroxyl radicals in order to disinfect the water. Cultivated culture of Legionella was used for the kinetically investigation of cell destruction and its mechanism. The formation of active species such as hydroxyl radical, hydrogen peroxide, superoxide and etc can be promoted during ultrasonic irradiation in the presence of TiO_2. It may be due to the concentrated energy of the exploded bubbles on the surfaces of titanium granules caused during acoustic cavitations. These reactive oxygen species (ROS) may disrupt or damage various cell or viral functions and structures. Improvement of this novel disinfection method and studying the mechanism of this system were the purposes of this investigation. Materials and methods -Preparation of Cultures Legionella pneumophila(GIFU 9888) was used in this research as the model microorganisms. Legionella were incubated on BCYE plate and transferred to BYE medium. The inoculated culture was incubated in a shaker incubator at 110 rpm for 48 hrs at 37℃. Then, the culture broth was diluted to a suitable concentration. Ten ml of the diluted broth was transferred to the bottles containing TiO_2 pellets at different concentrations. -Ultrasonic irradiation Bottles were irradiated at 36 KHz, 300 W and samples were driven at different time courses. The temperature was kept constant at 20℃ during irradiation. The irradiated samples were diluted to suitable concentrations and plated on BCYE plates. The plates were incubated for 72 hrs at 37℃. The number of colonies on the plates was counted after incubation. Results and Discussion Ultrasonic irradiation of diluted culture for 15 minutes showed 92% reduction in the number of viable cell concentration at the presence of TiO_2. The rate of disinfection was compared in the presence of TiO_2 and Al_2O_3. TiO_2 induced higher rate of cell killing compared with Al_2O_3. Also, investigating the effect of TiO_2 concentration indicated that the rate of disinfection was proportional to the concentration of TiO_2. The mechanism of cell killing was further investigated by examining the effects of OH radical scavengers such as ascorbic acid and glutathione. Lower rates of disinfection were observed in the samples containing these radical scavengers, thus indicating the primary role of OH radicals in this process.

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Many persistent organic compounds are difficult to dissolve and to be decomposed in water solvent by using the methods such as photocatalyst and so on. However, they are soluble in organic solvents and hence are possible to be decomposed in the solvents. In this study, we investigated the decomposition of chlorobenzene (CB) and Trichlorobenzene (TCB) with various concentrations in water and a couple of organic solvents by ultrasound. Ultrasonic irradiation was carried out at 20℃ in a water bath with an ultrasonic generator (Kaijo 4021, 200 kHz, 200W) under an argon atmosphere. The degradation rate of TCB in water solvent increased with concentration up to a concentration of about 0.5 mM, while it became constant above 0.5 mM. In organic solvents such as methanol, butanol and so on, the degradation rates of TCB and CB with a concentration of 2 mM was almost the same as that in water solvent for TCB and smaller than that in water solvent for CB. From these results, little effect of the organic solvents was observed on the decomposition of CB and TCB.

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The u1trasonic degradation of Bisphenol A, which is an endocrine disruptor, was investigated. The effect of the dissolved gases of argon, oxygen, air and nitrogen, was studied. In recent years, the environmental pollutants which are mainly concerned with an endocrine disruptor are a threat to society. Since these chemical contaminants are hard to be decomposed, the many new decomposing methods have been proposed. The ultrasonic irradiation method is one of them. The ultrasound was generated using a concave transducer of 500 kHz at 25℃ under various gases. Of the four dissolved gases, the highest degradation rate was obtained for oxygen. A characteristic decomposition intermediate was detected for gases containing oxygen. The intermediate was identified by GC-MS. The enhancement of the decomposition rate seems to be ascribable to the intermediate.

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The heat sterilization procedures are widely used in food industrial field. Although these procedures are convenient and effective for the sterilization of microorganisms, they sometimes spoiled products by heating or denature food materials. To solve these problems, on the other hand, the sterilization effects applied cavitation is paid attention. Such effects ascribe to the impulsive pressures due to the collapsing of the cavitation bubbles, i.e., vaporous bubble or gaseous bubble. However, it remains unclear whether such effects highly depend on the types of bubbles. In this paper, therefore, we study about the sterilization effects on the Esherichia cvii in the physiological salt solutions under the two kinds of cavitators, which consist of a nozzle of 1mm in diameter and a exponential horn vibrating at the frequency of 20kHz. Viable count of E. coli was measured by plate counting method. After treatment of cell suspension, a part of samples were withdrawn, diluted by physiological saline solution, and spread onto agar plates. After incubation for 24h at 30℃, colonies of E. coli formed are observed as shown in Fig. 1. Viabilities of E. coli were calculated from number of colonies formed, volume of cell suspension applied onto agar plates and the dilution rate. Survival rates S of E. coli were designated rates of viability after the treatment for t min versus viability at 0 time. The viability curves against the incubation time were expressed as the Arrhenius equation, where N t, k, and Dwere designated as number of viable cells, incubation time, death rate equation, and decimal reduction time (D value) which is estimated from time required for the reduction of viabilities to reduced to one tenth. Figure 2 shows the survival curves for two kinds of cavitation. The sterilization effects are clearly visible in cavitating flows and the corresponding D value remains about 900. While, for the ultrasonic cavitation (Vibratory cavi.) under the atmospheric pressure, D value decreases to around 50, suggesting remarkable sterilization effects. It is found that (1) the sterilization effect is clearly visible in the flow cavitation; (2) the sterilization intensity deeply depends upon the types of bubbles, and the vaporous bubble plays an larger role in such sterilization intensity; (3) for the ultrasonic cavitation under atmospheric pressure, Dvalue is comparable to that for heat sterilization procedures; (4) from SEM photos shown in Fig. 3, the impulsive dents and the destructive damages are clearly observed on the cell membrane of E. coli.

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Ultrasonic irradiation generates small bubbles in a liquid; these bubbles are called "cavitation bubbles". Under ambient temperature and pressure conditions, high temperatures and pressures are produced in and around the cavitation bubble, just before cavitation collapse adiabatically. Understanding of cavitation bubble temperature is very important for practical use of sonochemistry, because of chemical and physical effects on decomposition of hazardous substans, formation of nano-particle, etc. But the sonochemical phenomena such as cavitation bubble temperature, pressure and so on are not well understood. In this study, we investigated cavitation temperature through recombination of methyl radicals (・CH3) formed by the sonolysis of aqueous solutions with various alcohols. Ultrasonic irradiation was carried out at several temperatures (10℃〜40℃) in water bath with an ultrasonic generator (Kaijyo 4021, 200kHz, 1.3W/cm^2) under an argon or helium atmosphere. It was found that the concentrations of t-butyl alcohol and 2-propanol affected cavitation bubble temperature. The cavitation temperature increased and reached the maximum temperature and then decreased with increasing the concentration of alcohol. Irradiation time and vapor pressure also affected the cavitation bubble temperature. In addition, in the case of n-alcohol, the cavitation bubble temperature was also related by vapor pressure.

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Previous studies have shown that some series of liposomes, usually containing cationic lipids, are useful tools for gene introduction into cells. To investigate the effect of ultrasound (US) on liposome-mediated transfection, three types of liposomes (designated L1, L2 and L3, in the order of increasing transfection effciency) containing O,O'-ditetradecanoy1-N-(α-trimethylammonioacety1)diethanolamine chloride, dioleoylphosphatidylethanolamine, and/or cholesterol at varying ratios, were used in this study. HeLa cells were treated with liposome-DNA complexes containing luciferase genes for 2 h before sonication. Optimal US condition for the enhancement was determined to be 0.5 W/cm^2, 1 MHz continuous wave for 1 min. Luciferase expressions 24 h after the treatments were significantly increased by sonication to 2.4 fold with L1, and 1.7 fold with L2. However, with L3, which showed the highest level of expr7ession among the liposomes, luciferase expression was decreased under the same condition. Although the enhancement was not enough to directly apply the combination for the clinic, it might be possible to extend the improvement of the efficiency through elucidating the mechanism for the enhancement.

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Crystalline titania particles were prepared by hydrothermal treatment of aqueous solutions of inoganic salts. Rutile and anatase particles were obtained from chlorides (TiCl_3, TiCl_4,) and oxysulfate (TiOSO_4), respectively. Rutile particles were composed of needle-like particles and higher specific surface area (SSA) of 120m^2/g, while anatase have lower SSA of 30m^2/g. There were not a particular effect of ultrasound upon the hydrolysis reaction so far. On the other hand, iron oxide particles of 〜10nm can be prepared by oxidizing a diluted suspension of Fe(OH)_2 in alkaline solution when a suitable sonication is provided. This novel method was applied to surface modification of titanium dioxide. Transmission electron microscopy showed a successful deposition of iron oxide nanoparticle onto titania. Bleaching of methylene blue (MB) was tested for the titanialiron oxide composite particles and other reference materials. It was found that the composite particles have a dractic bleaching effect in the absence of neither UV nor visible light. This is due not to photocatalysis but to anormal absorption of MB to the composite particles. The MB bleaching of anatase-based composite was found to be higher than that of rutile-based one in spite of lower SSA. It is inferred that strong acidic points were produced around the chemical bonds of Ti-O-Fe.

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This paper reports the mechanical effect produced in the pig's thigh meat and human finger by the ultrasonic insonation. When the pig's thigh meat is compressed by an increasing weight and vice versa, ultrasound insonation yielded the strain wave with the differently depressed waveform with respect to the positive and negative amplitudes. This suggested the non-reversible deformation and the stress-strain hysteresis. This phenomenon is analogous to the parasitic oscillation in the metal plate with micro-cracks. In case of intense sound insonation, the sample showed the existence of spike-like stress. This effect was computed with the RPNNP equation for a single bubble motion. The result coincided with the experimental event and manifested that the repulsive force via the liquid from the bubble approached the 10 M Pa for the incident sound with a pressure amplitude of 100 k Pa.

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The effect of ultrasonic irradiation and gamma-ray radiation on the inactivation of microorganisms is strongly associated with free radicals which generated from water molecule. In this aspect, it is considered that the both effects are seemed to be similar in terms of the radical contribution, especially at a range around 200 kHz for sonication condition. However, in case of ultrasound, the shock wave also contributes for microbial disruption of cell components including cell membrane or genic compound, which is lead to cell death. In this study, we compared the effect of ultrasound and gamma-ray considering the indication of cell membrane permeability and nucleic acid. After each sonication and gamma radiation, the amount of nucleic acid was measured by using BACTANA[○!R] (an automatic microbial analyzer based on flow cytometry) in addition to colony counting. It is observed that the nucleic acid synthesis significantly increased within the cells before entering the logarithmic phase of their growth. Moreover, it was found that the pattern of increasing amount of nucleic acid following with the growth of the cells was different between sonication and gamma-ray radiation. In case of sonication, increasing rate hardly change depending on the sonication time. On the other hand, it was decreased with increasing intensity of gamma-ray radiation. It seems that the damage on survival cell remain after gamma-ray radiation and it takes long time to repair and growth of the cell.

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Computer simulations of bubble oscillations in liquid water irradiated with ultrasound are performed under the experimental condition of single-bubble sonochemistry [1]. The model used in the present computer simulations are described in Refs. [2-6]. 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 calculated number of OH radicals dissolving into the surrounding liquid from the interior of the bubble agrees sufficiently with the experimental data. OH radicals created inside a bubble at the end of the bubble collapse gradually dissolve into the surrounding liquid during the contraction phase of an ultrasonic wave although one third of the total amount of OH radicals that dissolve into the liquid in one acoustic cycle dissolve in 0.1 μs at around the end of the collapse. The main oxidant which dissolves into the liquid is not OH radical but O atom which is created by the dissociation of oxygen molecules and water vapor molecules inside a collapsing bubble. It is suggested that the main oxidant in sonochemical reactions for a multibubble system in water in which oxygen is dissolved as in the case of air is not OH radical but O atom in contrast to the widely used assumption that OH radical is the main oxidant.

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1. INTRODUCTION We reported an ethanol separation phenomenon into atomized mist by irradiation of ultrasound from under the surface of solution [1-2]. The separation mechanism has still been unclear. In this report, we discuss the effect of heat transfer in gas phase after atomization. 2. EXPERIMENTAL In this report, we used 15 kinds of pure materials. The other procedure of experiment was according to the previous paper [2]. The temperatures of the gas phase at the inlet and the outlet of air flow were accurately measured. 3. RESULTS AND DISCUSSION The relationship between the boiling points of the pure materials and the atomization rate are plotted in figure 1. The results can be separated in two types: that of the polarity group ○; and that of the non-polarity group ●. Atomization rate increased with decreasing boiling point. The bounding energy between molecules of the polarity group is stronger than that between molecules of the other group. As shown in figure 2, which horizontal axis indicates the products of the atomization rate of the pure materials and latent heat, whose vertical axis indicates the heat decrease of the introduced air at the inlet and outlet of the experimental atomization apparatus. This result indicates that the temperature decrease is high at a high atomization rate, If the atomized mist is completely vaporized in the gas phase, namely, the atomized liquid changed its phase to the vaporized gas, both the latent heat of atomized mist and the enthalpy decrease in the introduced air should be equal. The oscillation energy of ultrasonic atomization was 15J/s-16J/s. The enthalpy unbalance in figure 2 suggests that the vaporization of atomized liquid into the introduced air is not completely at the molecular level. The insufficiency of the enthalpy decrease of the introduced air for atomization means that all bound inter-molecules in the atomized liquid must not be cut, parts of the bound molecules may be kept as a sol of the atomized liquid. Sol formation in the gas phase is the reason for the insufficiency of the enthalpy decrease in the gas phase. Figure 1 also suggests that the sol formation in atomization is caused by the polarity group retaining more bound inter-molecules than the non-polarity group. Moreover, in the case that the aerosol radius is less than ten nano meter, Thomson-Gibb' effect will be larger. The vapor pressure of target substance on aerosol will exponentially increase.

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Acetone and various benzaldehyde substituted with methyl, chioro, methoxy and hydroxyl groups were reacted with amine-silica gel (230-400 mesh) under ultrasonic irradiation(Sus-4005C, 50W, 40kHz) for 2h to give the corresponding aldol condensation products: compound 3 and 4. From 4-methylbenzaldehyde with acetone gave 4-(4-methylphenyl)-4-hydroxy-2-butanone and 4-(4-methylphenyl)-3-buten-2-one, respectively. In the case of ultrasonic irradiation, the compound 4 was mainly produced. On the other hand, compound 3 was predominantly produced under no ultrasonic irradiation. Phenolic aldehyde and acetone were reacted with amine-SiO_2 under ultrasonic irradiation to give the corresponding aldol condensation products without any byproduct which was produced by the reaction of phenolic hydroxy group. This method is a good way to obtain the mild and selective aldol condensation products from the starting materials very susceptible to strong base.

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Due to recent drastic advances in the technologies of diagnostic ultrasound scanner and microbubble contrast agent, the performance and functions of ultrasound scanner seems to be high enough for real-time 2D or 3D monitoring of microscopic phenomena. As a fundamental study for applying ultrasound scanner in such monitoring purposes, we observed sonochemical reaction fields with 7.5 MHz ultrasound probe. By using chemiluminescence (CL) intensity of luminol induced by 1 MHz ultrasound as a measure, sonochemical reaction fields were observed by changing acoustic intensity. It was found that at acoustic intensities higher than the threshold for CL, bubbles with diameter about several micrometers and several ten micrometers were observed. At an acoustic intensity slightly lower than threshold for CL, bubbles with diameters in the same range as above were also observed. Our results indicated the presence of quasi-threshold for sonochemical reactions at which microbubbles are induced but the numbers are too small for reactions.

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Ultrasound was irradiated to a micro channel (1D) and to a thin layer (2D), with their characteristic lengths in the order of a few hundred microns. The flow in the channel and in the thin layer was observed as video images by using a microscope and the occurrences of cavitation phenomena in microspace was confirmed. Furthermore, the resultant sonochemical effects in the microspace were quantified using fluorescent probe as a function of ultrasound power density. The threshold value for the cavitation and their sonochemical efficiencies to produce OH radicals were compared with a conventional sonochemical reactor (3D).

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Many types of interesting flows were observed when the water contained in a microspace, such as a microchannel of a few hundred micrometer width and depth, was irradiated by ultrasound at frequency in the range from 20kHz to 1MHz and intensity of several hundred of milliwatts per square centimeter. If a bubble exists in the microchannel, microstreaming of different mode and strength were observed depending on the size of bubble, input power and ultrasonic frequencies. Several hundred of yeast cells, added as tracer, were effectively collected around the oscillating bubble of about 100μm in diameter. When the bubble size was as small as about 10μm, a violent circulating microstreaming was observed around the bubble. In this case, the yeast cells were carried in streaming orbits and the cells might be damaged by the collision and the strong shearing stress at the boundary layer of the bubble. Some interesting types of flows were observed in microchannel even in the case without bubbles. Periodic gathering of yeast cells in the direction of channel was one of the typical flow in a microchannel. On the other hand, yeast cells could be accumulated at the center part of the channel by the circulating flow from the side wall to the center.

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Investigations show that continuous ultrasound irradiation produces enhanced mass transport in electrochemical systems. No detailed work, however, has been undertaken in the evaluation of the effect of ultrasound on homogeneous electron transfer reactions in the electrode / solution interface because the electrochemical reactions always associate with the diffusion controlled processes. Electrochemical AC impedance spectroscopy is useful to study the kinetics at the interfaces and to distinguish between the various mechanisms which regulate the charge transfer based on a Randles equivalent circuit of electrolytic cell. The impedance experiment results in the present study indicated that there are two frequency regions, as at high and low, which can be used to distinguish the change in faradic impedance (charge transfer resistance) from the Cole-Cole plot for electrochemical reactions. In a stationary solution, a straight line was observed at low frequencies corresponding to the linear diffusion process electrochemical species, known as the Warburg impedance. This component, however, was disappeared under the ultrasound irradiation, and a semi-circle related to the faradic charge-transfer behavior was observed in spectrum. This phenomenon indicated that stronger ultrasound perturbations produced a limited thin diffusion layer so that the bulk concentration and surface concentration of electrochemical species did not differ appreciably. As a result, the Warburg element was omitted from the Randles equivalent circuit. As the width of the semi-circle giving the rate constant in the the heterogeneous charge-transfer process, AC impedance provided the necessary information in heterogeneous electron transfer rate constants for electroactive species during sonication. The charge transfer processes of an reversible electrochemical system (1 mM Fe(CN)_6^<3-> in 0.1 M KCl), a quasi- reversible system (1 mM Fe(CN)_6^<3-> + SDS in 0.1 M KCl) and an irreversible system (1 mM ascorbic acid in 0.1 M KCl) were examined with the proposed method. Ultrasound provided little effect on the reversible electrochemical system, but greatly enhanced the charge transfer rate constant for irreversible reaction in the process of electrochemical oxidation of ascorbic acid.

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In order to examine the synergistic effects of combining sonolysis and photocatalysis, sonophotocatalysis of oxalic acid was performed. Oxalic acid can be decomposed by not only sonolysis but also by photocatalysis using TiO_2 powdered photocatalyst in an Ar atmosphere. As the products of sonophotocatalysis, carbon dioxide, carbon monoxide, and hydrogen were obtained in the gas phase. In the case of photocatalysis, CO was hardly detected. In the case of sonophotocatalysis, the yield of CO_2 increased about 14 times larger than that in the case of photocatalysis. The yield was twice larger than the sum of yields of photocatalysis and sonolysis. Thus, synergistic effect was observed in an Ar atmosphere. In this synergistic effect, hydrogen peroxide produced from solvent (H_2O) by sonolysis was thought to be played an important role. It is known that a photocatalytic reaction accelerates by addition of H_2O_2. Active oxygen species were produced in the process of decomposition of H_2O_2 by photocatalysis and they attacked to reactants. In the case of sonophotocatalysis, H_2O_2 also participated in the process of decomposition of oxalic acid. (Sonolysis of solvent) 2H_2O→H_2+H_2O_2 (Photocatalysis) 2H_2O_2→2H_2O+O_2 In order to confirm of role of H_2O_2, pre-irradiation of sonic waves was performed. The accumulation of H_2O_2 in the solution was observed during sonolysis and then the improvement of the rate of CO_2 production under sonophotocatalysis was confirmed.

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Model compounds (benzoic acid or phenol: 1.25×10^<-6> mol/l) as organic pollutants of water were added to the aqueous solution contained titanium dioxide (0.1〜0.8g) and hydrogen peroxide (0.0423 mol/l). The solution was continuously stirred during degradation treatments (1〜4days) by means of a magnetic stirrer in the dark place. At the end of reaction, sodium hydrogen sulfite was added to the mixture to reduce the excess hydrogen peroxide. The remained phenol was extracted from the reaction mixture with ethyl acetate. The extracts were analyzed by FID-GC. For remained benzoic acid and both oxidation products, an aliquot of the reaction mixture was evaporated to dryness under a nitrogen gas and esterified with 15% BF_3/n-butanol at 100℃ for 60 min. The derivatives were analyzed by FID-GC and GC/MS. Each of substrates were decreased with treatment times, the remained amounts of them after 4 days treatment were about 40%. The results of oxidative reaction confirmed cleavage and hydroxylation of the aromatic rings. When benzoic acid was used as a model compound, the major oxidation products (about 20%) consist of aliphatic C_2-C_4 α,ω-dicarboxylic acids, C_4 unsaturated dicarboxylic acids (maleic and fumaric) and hydroxy benzoic acids. While, in the case of phenol, was little. In addition, when ultrasound (40kHz) was simultaneously irradiated (1〜10 hr) into the solution, the rates of the disappearance of each substrates was exponentially accelerated. On the other hand, amounts of the degradation products were less rather than without ultrasonic irradiation.

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Irradiation of TiO_2 particles under ultraviolet light has been known to be a source of OH radicals in the disinfection or oxidizing systems. However, a new system was devised in this study for production of OH radicals by replacing UV with ultrasonic system (US). Formation of OH radicals was investigated in a TiO_2/US system to study the mechanism of formation of OH radicals as well as enhancement of cavitation effect in the ultrasonic system. Formation of OH radicals in the irradiating solution was studied by the reaction of OH radicals with salicylate. 2,3-dihydroxybenzoicacid (2,3-DHBA) and 2,5-dihydroxybenzoicacid (2,5-DHBA) can be formed during this reaction and they can be measured by HPLC with an electro chemical detector (HPLC-ECD; Eicom). Formation of DHBAs could be detected during the irradiation of salicylate solution under ultrasonic system and in the presence of TiO_2. It was seen that the concentration of DHBAs was increased within 20 minutes irradiation and then decreased in spite of high concentration of salicylate. It was likely due to the oxidation and degradation of DHBA in the ultrasonic system. Therefore, for investigating the oxidation of DHBA in the presence of salicylate, more salicylate was added after 20 minutes reaction to the irradiating mixture consecutively. The concentration of DHBA was increased for three times by the addition of salicylate concentration in the solution. Enhancement of cavitation energy was also investigated by the addition of various gases (Ar, O2, N2) into irradiation solution. The ratio of the specific heats at constant pressure and constant volume (Cp/Cv) of the gas and vapor inside the cavity is known to be one of the most crucial parameters that determine the final temperature inside cavitation bubbles. Monoatomic gases, such as argon has a high value of Cp/Cv, while diatomic gases, such as N_2, O_2 have a lower values. Therefore, addition of argon to the irradiating solution induced higher concentration of OH radicals due to higher cavitation energy. Our results indicated that the addition of O_2 and N_2 gases at the same conditions resulted lower oxidation power. Finally, the competitive oxidation of salicylate and DHBAs in the irradiating solutions was more investigated in this research to develop a more descriptive mechanism of generation of hydroxyl radicals.

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CO_2 was added to the water in an Ar atmosphere and ultrasonic irradiation was carried out. CO and H_2 were produced from CO_2 and water, respectively. Detectable amount of H_2O_2 O_as also observed. H2O_2 was used for oxidation of the reactant in the solution. On the other hand, H_2 was possible to be consumed for deoxidizing from CO_2 as shown in equation (1). The reduction of CO_2, however, may occur directly in cavitation babbles as shown in equation (2). In order to examine the role of H_2 in the reaction system, sonochemical reactions were performed in H_2 or H_2-Ar atmosphere. CO_2+H_2→CO+H_2O・・・(1) 2CO_2→2CO+O_2・・・(2) CO and CH_4 were formed in a pure H_2 atmosphere under ultrasonication. The production of CH_4 was very interesting. The yield of CO increased with irradiation time, while the yield of CH_4 saturated after the initial production. This behavior was observed over 80% H_2-Ar atmosphere. Other management factors of ultrasonication were also examined. The yield of CO increased with the amount of addition of CO_2, although the yield of CH_4 seldom changed. The yield of CO was influenced with reaction temperature, but that of CH_4 was fixed. This fact showed the yield of CH_4 did not depend on temperature. Thus, it was seen that CH_4 yield in H_2 atmosphere was hardly influenced experimental conditions.

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Degradation of 2,4-dicholophenol, p-tert-butylphenol, and benzophenone was performed by the three methods; electrolysis, photo-irradiated electrolysis and sono-irradiated electrolysis. 2,4-dicholophenol was dissolved in water. p-tert-butylphenol was dissolved in aqueous 30 vol% methanol solution and benzophenone was dissolved in aqueous 50 vol% ethanol solutions since these substance are scarcely soluble in water. The sono-irradiated electrolysis decomposed 2,4-dicholophenol and p-tert-butylphenol faster than the other methods, but these methods were of similar decomposition rate for benzophenone. The effctiveness of sono-irradiated electrolysis decreased in the order of 2,4-dicholophenol, p-tert-butylphenol and benzophenone. Cavitation effects rather than stirring effects of the ultrasounds probably played an important role in the sono- irradiated electrolysis.

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Orgarnc matter dissolved in water was decomposed by pyrolysis and reaction with OH radicals generated in the cavities formed by ultrasound. In general, hydmphobic olgarnc pollutanis are thought to be decomposed by sonolytic reactions more than hydrophilic organic pollutants. When the hydrophobic oigarnc pollutants are decomposed in water, their hydrophilic organic intennediates could remain longer. Therefore, we tried to enhance the sonolytic degradation of hydrophilic organic pollutants by combining ultrasound with TiO_2 photocatalytic reaction, and investigated the effects of the photocatalyst amount and frequencies by ultrasound on their decomposition ratios. Benzaldehyde and formaldehyde were selected as model pollutants due to their hydrophobicity and hydrophiiicity, respectively. Remarkable enhancement of decomposition ratios of hydrophilic organic pollutants and interaction between ultrasound and photocatalytic reaction was observed independently of the frequency. Moreover, an effective decomposition was obtained with lower photocatalyst amounts than when using only in photocatalytic reactions.

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The solvent cleaning is hard to remove PCB from porous material such as wood and paper. The use of powerful ultrasound in the cleaning of surfaces of manufactured objects is well known. Recently, it has been reported that the membrane cleaning process was enhanced by the ultrasonic irradiation. In this study, the removal performance of chlorinated organic compounds from porous material by ultrasonic irradiation is experimentally examined. Wood chip impregnated with o-dichlorobenzene was used as the sample. The removal rate for ultrasonic irradiation was much higher than that for shaking. The removal ratio depended hardly on the ultrasonic frequency and temperature, but was strongly controlled by the ultrasonic intensity. In order to investigate the behavior of liquid exchange in pore, the Stefan tube was used. The effects of diameter and depth of pore on the behavior of o-dichlorobenzene removal were small. However, when the position of tube top was set at the maximum of particle velocity by ultrasound, the amount of o-dichlorobenzene removal was high. The effect of kind of dissolved gas in solvent was small. From these results, it is considered that o-dichlorobenzene in pore is removed from the sample mainly by the longitudinal vibration near sample surface.

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There are many toxic compounds in the environment. It has already reported that various compounds, such as benzene, chlorobenzene(CB), chlorophenols(CP), chloroform, are decomposed by ultrasonic irradiation. It is important to investigate the effects of sonolytic products of them on the environmental microorganisms. In this study, the growth activity of yeast cells or E-coli cells in the growth media containing those compounds was measured by calorimetric analysis. Calorimetric analysis can provide not only the quantitative information for the microbial growth activity but also the characteristic features about the bactericidal and bacteriostatic effect of the chemicals on the microbial cells. The g(t) curves obtained from yeast cells or E-coli cells showed that chlorobenzene and o-chlorophenol did not affect the cell growths significantly. In addition, 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.

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