Titanium dioxide (TiO_2) is known as photocatalytic material, and it generate reactive oxygen species (ROS) according to be excited by ultraviolet rays (UV) under 380nm. Those ROS generated from TiO_2 could sterilize E coli, and have cytotoxic effect on mammalian cancer cells. Previously, we reported the generation of OH radicals from TiO_2 particles excited by ultrasonic (US) irradiation, not UV. Furthermore, the TiO_2 excited by US exhibited decompose activity on E coli and chemical substances. In this study, we report the cytotoxic effect of US in the presence of TiO_2 particles in cell culture media. To estimate the cytotoxic effect, we measured lactase dehydrogenase (LDH) activity leaked from damaged cell numbers after US irradiation. Immediately after US irradiation in the presence of TiO_2 particles, the LDH activity exhibited high, indicating TiO_2 with US irradiation caused damage on cell membrane stability. Furthermore, we confirmed the cell membrane damage by flowcytometry assay with Annexin V-FITC/Propidium iodide (PI) stain method, Annexin V-negative/PI positive cells were dominant immediately after US irradiation in the presence of TiO_2 particles.

抄録全体を表示

We recently developed a new in vitro assay system for the evaluation of bone metabolism using goldfish scale. This system can simultaneously detect the activities of both scale osteoblasts (formation cells) and osteoclasts (resorption cells) with alkaline phosphatase and tartrate-resistant acid phosphatase as markers. Using this scale in vitro assay system, in the present study, we analyzed the effect of ultrasound (US) stimulation on osteoblastic and osteoclastic activities. The osteoblastic activity significantly increased by pulsed low-density US (1MHz, 60mW/cm^2 I_<SATA>, 50% duty factor at 0.5Hz, 180 pulses) in 18 hrs of incubation at 15℃ after US treatment but not in shorter incubation periods, while the osteoclastic activity did not change in the same incubation period. To examine the mechanism of US in osteoblasts, the estrogen receptor (ER) and insulin-like growth factor-I (IGF-I) mRNA expressions in the cultured scales were analyzed by RT-PCR. ER mRNA expression was found to be higher in the US-treated scales than in the control scales in 18 hrs of incubation at 15℃ after treatment, although ER mRNA expression did not change in 3 hrs of incubation. On the other hand, IGF-I mRNA expression increased in 3 hrs of incubation at 15℃ after US treatment. Therefore, IGF-I mRNA expression was more rapid to respond to US than ER mRNA expression, and IGF-I may have an important function in the activation of osteoblasts by US treatment. We found that both osteoblastic and osteoclastic activities increased in the remaining ontogenic scales of the left side at 3 days after the removal of all scales in the right side. Using these scales, we examined the effects of US stimulation on osteoblasts and osteoclasts under the same conditions described above. In 18 hrs of incubation at 15℃ after US treatment, the osteoblastic activity increased by US treatment in the ontogenic scale as well as the normal scale. Furthermore, we indicated that the osteoclastic activity in the ontogenic scale decreased by US treatment. The conditions of osteoblasts and osteoclasts in the ontogenic scale are similar to those in the human osteoporosis, indicating that US stimulation may contribute to the cure of osteoporosis.

抄録全体を表示

Promoters responsive to sonication could be useful for efficient gene therapy since, using such a promoter, expression of a therapeutic gene could be controlled by sonication. Synthesized DNA oligomers containing binding motifs of transcription factors, AP-1, NF-kB, NF-Y and CBF-A, which are activated by oxidative stress, were randomly ligated them and linked to a TATA box sequence to construct artificial promoters. These promoters were introduced upstream of the luciferase gene to control its expression. A plasmid with such a gene cassette was transfected into HeLa cells and sonicated with 1MHz ultrasound at 1W/cm^2 and 10% duty factor for 60 sec. Transfected cells with two out of six plasmids significantly increased luciferase activities compared with each of unsonicated controls 6 h after sonication. Enhancement with clone #11 showing the highest increase turned out to be dependent on intensity and duration of sonication. Nucleotide sequence analysis indicated the promoter was 214 bp long, composed of 16 copies of transcription factor binding motifs. To improve reactivity of clone #11 to sonication, random mutations were introduced by error prone PCR. Two series of PCR reactions on clone #11 resulted in a new promoter over 4 fold more reactive to sonication.

抄録全体を表示

Stabilized microbubbles show high echogenicity and characteristic non-linear acoustic responses and also works as 'sensitizers' for HIFU therapy. Accordingly, if microbbles were selectively placed in targets inside body, targeted diagnosis and therapy would be possible. However, unfortunately, microbubbles are too large to apply tissues other than in vessels. For tumor detection and therapy, we propose the use of nano-sized liquid precursor of microbubbles, which is small enough to accumulate in tumor tissues and generate microbubbles with ultrasound pulses. We have developed emulsion based precursors containing perfluoropentane and found that microbubbles can be produced with ultrasound pulses produced with a medical ultrasound scanner (modified for this study) at negative peak pressure at about several MPa in water. The pressure threshold for the phase shift decreased with ultrasound frequency, indicating that thermal mechanisms are involved. However, wave numbers in ultrasound pulses did not affect the thresholds, thus not a simple thermal mechanism is dominant. Part of this work was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology through a grant-in-aid for the creation of innovations through business-academic public sector cooperation.

抄録全体を表示

Single bubble sonoluminescence was discovered in 1989, and the following studies on this phenomenon greatly contributed to elucidate the mechanisms of cavitation phenomena. However, several important problems of the phenomenon are still under investigation. Non-spherical behavior of a single or multi bubbles is one of the unsettled problem. As part of our studies on the safety of diagnostic ultrasound using an ultrasound contrast agent, dynamics of microbubbles of several microns in diameter have been studied using high-speed photography method. This paper introduces our observation system and a collection of high-speed photos especially focusing on non-spherical bubble behavior.

抄録全体を表示

Nanocomposites are a special class of materials originating from suitable combinations of two nanoparticles or nanosized objects in some suitable technique, resulting in materials having unique physical propaties and wide application potential in diverse areas. Meanwhile, ultrasound can generate acoustic cavitations in a liquid. The collapse of the cavities generates the energy for chemical and mechanical effects. Ultrasonic irradiation dissociates water molecules into primary hydrogen radicals (H-) and hydroxyl radicals (OH-) in cavitation bubble. Since these active species can drive reduction of metal ions and oxidative polymerization of monomers, respectively, one-pot synthesis of metal 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 Pt/polypyrrole nanocomposite by using ultrasonic irradiation. Moreover, we have demonstrated the application of this nanocomposite to size-selective nanocatalyst.

抄録全体を表示

At present, lithium cobalt oxides and lithium nickel oxides are mainly used as cathodes of lithium ion batteries. This is because these materials show very high battery performance. However, they are not suitable for large-scaled batteries such as hybrid vehicles, because they are expensive and poor in resources. We then focused on iron because it is cheaper and more abundant. Iron Phosphate (FeO_4) is one of the most interesting materials in Iron based materials so far because it shows a high discharge voltage of 3.5 volts. The theoretical capacity is 170mAh/g, which is sufficient enough compared to present materials being used as lithium ion batteries. The remarkable feature of FePO_4 is that it can be synthesized in air. Its treatment is very easy but the cycle performance shows poor. In this study, we have tried to obtain good cycle performance and improve discharge capacity of FePO_4 utilizing the sonochemical method. The sonochemical reaction was conducted under the irradiation of ultrasound power 200W and frequency 200kHz for 3hours. The crystalline phase was identified by powder X-ray diffraction. The cathode for the electrochemical characterization was made by mixing powders of the sample, acetylene black and PTFE in 70:25:5 weight ratio under Argon atmosphere. The cathode properties were measured in a galvanic cell with a nonaqueous electrolyte, a polypropylene separator and a Li metal anode. Charge/Discharge performances were evaluated at a current rate of 2C in the voltage range between 2 to 3.9 volts. The first discharge profile obtained for the sample heated at 700℃ is improved about 10% compared with a previous report's one. We could also obtain LiFePO_4 by the sonochemical method.

抄録全体を表示

New type of supersonic washer-disinfector was developed in order to clean and disinfect reusable medical instruments such as semiconductors, endoscopes and food materials in a short time. This washer has supersonic levitation function with umbrella-shape oscillators and sterilization function with ozone bubbles and silver electrolysis as described in the succeeding paper. Sterilization has been found to be easy and rapid using both ozone oxidation and silver electrolysis. E.coli JM 109 strain (10^3-10^6cells/ml) was killed in 20min either by ozone bubbling or silver electrolysis. S.cerevisiae FY24 strain descending from S288C strain (10^4cells/ml) was killed by silver electrolysis within 0.5min. Bacillus atrophaeus Nakamura1989 NBRC13721 strain descending from ATCC9372 strain (10^4cells/ml), which is most resistant to ethylene oxide gas-sterilization, was killed in 30min by ozone and in 5min by silver electrolysis. Geobacillus stearothermophilus NBRC13737 strain descending from ATCC7953 strain (4×10^4cells/ml), which is most resistant to autoclave sterilization, was killed by silver electrolysis in 5min at 40℃ and in 1 min at 60℃.

抄録全体を表示

Noble metal particles were successfully immobilized on the surface of magnetic γ-Fe_2O_3 nanoparticles by the sonochemical reduction method. Morphologies of the formed composite nanoparticles were investigated by TEM. The supported nanoparticles were single-nano size, and the sizes and the numbers of supported nanoparticles depended upon the type of stabilizer. The obtained Pd/γ-Fe_2O_3 composite nanoparticles showed catalytic, activity for Heck reaction, cross coupling of acrylic acid with iode benzene. However, in the second run of the catalyst, the composite nanoparticles did not show activity. This is probably due to the exfoliation of palladium nanoparticles from the surface of γ-Fe_2O_3.

抄録全体を表示

Effects of TiO_2 powder addition on sonochemical destruction of 1,4-dioxane in water were investigated through comparison of SiO_2 powders with similar specific surface area. Addition of TiO_2 is more effective for decomposition of 1,4-dioxane in water than is SiO_2. Contribution of photocatalytic destruction through sonoluminescence is not a dominant mechanism to for the acceleration of sonochemical reactions by adding TiO_2. Regarding sonication of TiO_2-added water in the current case, thermally excited holes will be generated. Intrinsic oxygen vacancies in TiO_2 surface will also play an important role for high decomposition efficiency by producing cavitations. Both ultrasonication energy consumed in water and destruction efficiency of 1,4-dioxane were increased by the addition of reduced TiO_2 powder.

抄録全体を表示

The effect of operating pressure on ethanol separation from mixtures of ethanol and water through ultrasonic atomization was investigated. Ultrasound of 2.4MHz was irradiated to 27mol% ethanol aqueous solution in atomization tank under reduced pressure. The mixture of produced mist, droplet and vapor was brought out with a pump and fed to the collection tank at a higher pressure. To maintain a constant operating pressure and also to bring the mixture, carrier gas was supplied to the atomization tank. Inside of the collection tank was cooled at -20 degree C to enhance the condensation. Collection of the mixture of mist, droplet and vapor was successful by pressurizing and cooling. Weight of the collected sample with ultrasonic atomization was larger than that for without atomization. The difference between with and without ultrasound corresponds to the sum of droplets and vapor occurred form liquid fountains. Ethanol concentration in the collected liquid under ultrasonic atomization was higher than that for without ultrasound. The fact suggests that formation of droplets rich in ethanol through ultrasonic atomization.

抄録全体を表示

Small angle x-ray scattering (SAXS) measurements were performed using BL15XU beamline at SPring8 in order to obtain the size distribution of ethanol-water droplets in mist generated by ultrasonic atomization. The diameter of water droplets was > 100nm which is close to the value predicted by the theory. While, the diameter of ethanol was found to be only 1nm which is 10^<-3> times less than the predicted value. The droplets produced from the ethanol-water mixture of 20mol% are found to be a mixture with diameter of 1nm and 100nm, suggesting that phase separation occurs at the droplet level.

抄録全体を表示

Separation process through ultrasonic atomization is now in practical step. This process has many merits in comparison with distillation process: i) driven under normal temperature, ii) low energy consumption, iii) high separation efficiency and iv) low CO_2 and heat exhaust. We will show new data for the optimal operating conditions of the separation process. The discussion points are 1) High atomization velocity, 2) Complete dehydration of feed fermented ethanol solution, 3) Low energy consumption. This process is consisted of atomizer with ultrasonic oscillators, demister, air pump, energy saving cooler and molecular sieve adsorbents. We investigated each elemental process properties for atomizer, demister, cooler and PSA system. In results, we obtained several key points; 1) The energy consumption was 1/10 of vaporization energy, 2) The adsorption heat of water or ethanol to adsorbents was useful for heating of draft air into atomizer, 3) The optimal adsorbents volumes corresponding to atomization scale were determined, 4) The atomization velocity was accelerated by reduce of pressure in atomizer, and collection area should be under pressed condition.

抄録全体を表示

The sonochemical efficiency of a cylindrical sonochemical reactor has been investigated as a function of frequency and liquid height. The irradiation frequencies were 45, 129, 231 and 490kHz. The liquid height was varied from 10 to 700mm. The sonochemical efficiency of the cylindrical reactor was evaluated by potassium iodide (KI) dosimetry and calorimetry. In our study, the sonochemical efficiency depended on the frequency and liquid height; further, the plots of sonochemical efficiency against liquid height exhibit one or two peaks for each frequency. The sonochemical efficiency up to the first peak increased monotonically with the logarithm of the frequency, and the liquid height for the first peak was inversely proportional to the frequency. The sonochemical efficiency of the cylindrical reactor largely varied with the period of about half wavelength with an aluminium reflector, and increased when the impedance of the transducer decreased. In the case of a free surface at 129kHz, variation in the sonochemical efficiency of the cylindrical reactor was small. From these results, the optimum frequency for a sonochemical reactor can be determined if the liquid height is specified for scale-up of the sonochemical reactor.

抄録全体を表示

Reaction control is very important in synthetic electrochemistry. In a series of the works, I have demonstrated yield, current efficiency and product selectivity controls in electrochemical syntheses using ultrasonic fields. Moreover, I have also developed environmentally-friendly electrochemical systems and electrosynthetic methods for conducting polymer films having highly-regulated structures using ultrasonic effects. This is a comprehensive report on various organic sonoelectrosynthetic systems by our group, including significant new results.

抄録全体を表示

Volatile organic compound (VOC) is one of the most common contaminants in soil and groundwater because of its toxicity and persistence. To ensure sustainable use of land and water resources, effective removal of the VOC from contaminated soil and groundwater is required. Recently, the application of sonochemical process to the degradation of chemical contaminants in solution has been explored by many workers and the significant findings have been reported. However, the exploration was mostly conducted using a lab-scale sonochemical reactor, whose volume is in the range of 50-1000mL. In order to apply the sonochemical process to the treatment of a large amount of liquid containing contaminants, it is necessary to design and develop a large-scale sonochemical reactor which can remove the contaminants from the wastewater in efficiency. We have designed and developed a large-scale treatment system for removing the VOC from a contaminant soil and liquid by ultrasonic irradiation. The large-scale treatment system includes two kinds of 100 L-scale sonochemical reactors. In our study, the sonochemical efficiency of the 100 L-scale sonochemical reactor equipped with the 500kHz transducers has been investigated by potassium iodide dosimetry and calorimetry.

抄録全体を表示

Various types of gaseous pollutants exist in indoor spaces. Many researchers have carried out extensive studies about ozone and photocatalytic techniques using titanium dioxide (TiO_2) for removal of gaseous pollutants. Although this technique can effectively decompose organic gaseous pollutants, such as volatile organic compounds (VOCs), to CO and CO_2, it has some problems of the appropriate humidity to obtain high removal ratio and generation of considerable soluble intermediates as by-products. Ultrasonic atomization is a very useful technique to produce fine liquid particles of a diameter range below 10μm. In this study, TiO_2 powder was contained in a fine water mist as a suspension by ultrasonic atomization to obtain both effects of photocatalysis and effective capture of water-soluble decomposition intermediates. This ultrasonic mist including photocatalyst was named "UMP". Photocatalitic degradation and mineralization rate of toluene which is a model VOC gas was investigated to clarify the effectiveness of UMP method and the optimal condition of TiO_2 amount in the water.

抄録全体を表示

Numerical simulations of chemical reactions in a pulsating air bubble have been performed for various ultrasonic frequencies and pressure amplitudes in order to study the influence of ultrasonic frequency on sonochemical reactions. Below the threshold acoustic amplitude for cavitation, there is a range of the acoustic amplitude optimum for oxidants production, which corresponds to the optimum bubble temperature [K.Yasui et al., J.Chem.Phys. 119, 346 (2003)]. The range becomes wider and shifts toward higher acoustic amplitude as the ultrasonic frequency increases. The rate of oxidants production at the optimum acoustic amplitude increases as the ultrasonic frequency increases up to around 300kHz because it is proportional to the number of the bubble collapses per second. At 1MHz, however, the rate is lower than that at 300kHz due to the smaller ambient bubble radius than that at 300kHz. It may result in the optimum ultrasonic frequency of around 300kHz for the oxidants production reported in many experiments. According to the present numerical calculations, however, the optimum condition for the oxidants production by a bubble is at 20kHz when the pressure amplitude is larger than about 3 bar. It may be realized using pulsed ultrasound or in strongly degassed water as the continuum ultrasound is strongly attenuated by cavitation bubbles.

抄録全体を表示

In the sonochemical reaction field, radicals are produced by a thermal effect inside or near the cavitational implosion. According to numerical simulation of chemical reactions in the acoustic cavitation field, several kinds of active chemical species are created inside a collapsing babble. Yasui et.al proposed the calculated results that the oxidants produced by a bubble are not only OH radical but also oxygen atom. So far, however, no one can observe oxygen atom directly. Cvetanovic et.al was reported that ethylene and acrolein (acetyl aldehyde) are produced when cyclopentene reacts to oxygen atoms. In this report, cyclopentene is sonicated as probe for indicating the generation of oxygen atom. Sonolysis of cyclopentene was carried out with a 200kHz and 200W at 25℃. Acrolein and ethylene were obtained under sonication with another products. Oxygen atoms in their triplet ground state dissolve into the solvent resulted in producing acrolein. Acrolein might be produced at the bubble surface by oxygen atoms in their singlet excited states. Cyclopentene present near the bubble surface can also undergo thermal decomposition to produce hydrocarbons and carbon monoxide.

抄録全体を表示

Anodic oxidation of titanium metals in nitric acid was subjected to ultrasonic vibration. Products were found to be titanium dioxide particles with poor crystallinity. Light brown color of the product suggested that nitrogen from nitric group could be dissolved in the lattice. Application of a 28kHz ultrasound resulted in highly aligned pore with 30nm diameter at the nitric acid concentration of 1mol/L; while no porous structure was observed without sonication at the same concentration. Crystalline phase after calcined at 400℃ was rutile for the non-sonicated but anatase for the sonicated specimen. Ultrasonication during the anodic oxidation suppressed formation of the rutile microcrystals.

抄録全体を表示

The nanoparticles of various metals can be easily prepared by ultrasonic irradiation. This study was conducted to discuss the mechanism for the reduction of KMnO_4 and the preparation of MnO_2 nanoparticles. We investigated the effects of various alcohols and their concentrations on the reduction of KMnO_4 solution and preparation of MnO_2 nanoparticles. The amounts of KMnO_4 and MnO_2 at various irradiation times were measured by using the spectrophotometer. The ultrasonic irradiation conditions were as follows; frequency 200kHz, output power 6.88W, solution temperature 293K. From the results obtained, we found that the reduction of KMnO_4 and preparation of MnO_2 nanoparticles depended upon the concentrations of alcohols. In addition, the reduction and the preparation were assumed to be affected by hydrogen peroxide and/or the radicals of the alcohols.

抄録全体を表示

Carbon nano-materials were synthesized by ultrasonic irradiation at 200kHz in distilled water under the atmospheres of acetylene with and without the addition of various rare gases. The produced materials with time were different depending on the gas species. HPLC and UV-Visible spectrum analyses revealed that many kinds of water soluble materials were temporally synthesized and decomposed depending on the gases. The quantities of the intermediates were also different depending on the gas content. In all the cases, insoluble soot was obtained after sonication time in the order of several hours, although the time needed for easy separation from water changed in the broader range depending on the gases. The color of the insoluble soot was yellowed brown for He, but almost black for Xe. TEM images of these products revealed that particles in the order of 100nm size were coagulated, parts of which was carbon graphite clarified by TEM electron diffraction pattern. HPLC peak and UV-Visible spectra of the extracted materials in toluene from the produced soot were different from the spectrum of C_<60> and C_<70>.

抄録全体を表示

We have carried out a surveillance study on the application of ultrasonic processes in industry, especially in the field of pharmaceutical processes, biotechnology, biomass and food industry. The surveillance study consisted of the three parts; the patent surveillance for 20 years using World Patent Index database, the literature surveillance using JST Plus database for 11 years, and the series of interviews with 6 private companies in Japan. In the patent surveillance, 932 patents on sonoprocessing have been found in relation to the pharmaceutical processes. 517 and 327 patents have been found in the biotechnology and the food industry, respectively. The surveillance study shows that the innovative design of sonochemical reactors and the rationale for the scale up of laboratory ultrasonic experiments are necessary for the industrial sonoprocessing. This involves the reduction in energy consumption through the design of reactors incorporating appropriate ultrasonic emitters.

抄録全体を表示

The influence of pH on the degradation of hydrazine with a concentration of 0.1mmol/L was investigated under the stirring (300rpm) and ultrasonic irradiation conditions (200kHz, 200W) in the pH range of 1 to 9. It was found that the hydrazine degradation depended greatly upon pH under the ultrasonic irradiation condition, while it did not take place over the whole pH range under the stirring condition. Although it has been known that OH radicals and hydrogen peroxide are sonochemically formed from water, it was considered that the OH radicals played an important role of the hydrazine degradation, but not hydrogen peroxide. The pH dependence of the hydrazine degradation was discussed in terms of the relationship between the chemical structure and the basic dissociation constants of hydrazine.

抄録全体を表示

The cavitation bubble of the high temperature and pressure is needed for the decomposition of organic contaminant. In general, a high intensity ultrasonic generator is needed to generate such cavitation bubble, and a lot of electric energy requires for the decomposition. Therefore, practical use is difficult. In this study, the decomposition of methyl orange was investigated as an organic contaminant using a low intensity ultrasonic cleaner. In addition, the effect of CCl_4 additive on the rate reaction of decomposition was investigated.

抄録全体を表示

In this study, aqueous solutions of STS and 3 kinds of linear alkyl benzene sodium sulfonate (LAS) were adjusted to 100-1000mM. After that, these samples (STS, LAS C_8, LAS C_<10>, LAS C_<12>) were irradiated by 200kHz ultrasound (W=8.4W) under argon atmosphere. Because of their involatile and amphiphilic properties, LAS accumulates at the gas-liquid interface of cavitation bubbles but doesn't go into the bubbles. These properties are used for analysis of the reaction at the interface of cavitation bubbles. Analysis of their concentrations and SO_4^<2-> concentrations was performed by HPLC and IC. Surface excess concentrations were also measured. The degradation rate increases with increasing of the surface excess value, but after the local maximal value, it tends to decrease. It shows that there is the limit of surfactant's accumulation on the interface of cavitation bubbles.

抄録全体を表示

High performance liquid chromatography (HPLC) coupled with triple pulsed amperometric detection (TPAD) was developed for the determination of trace carbohydrates with high precision and sensitivities. The method was applied for the determination of the degradation products in hydrolysis reaction of disaccharides. The disaccharide sucrose can be hydrolyzed to the two monosaccharides, glucose and fructose with ratio of 1:1 in strong acidic condition. This reaction was not identified in a basic media (0.1M NaOH solution). Under ultrasound irradiation with the frequency of 45KHz, however, sucrose was rapidly decomposed even in a basic media. Results form HPLC analysis indicated that sucrose was decomposed into glucose and fructose under the ultrasonic irradiation, but the latter product yielded higher fraction in the mixture. It thus supposed that the produced glucose was further isomerizes to fructose under the ultrasonic irradiation. Although the mechanism of sucrose isomerization is speculative, evidence shows that glucose was converted into fructose as a function of ultrasound irradiation time.

抄録全体を表示

In order to elucidate frequency effect on sonochemical reactions, sonolysis of BrCCl_3 was examined at different frequencies. Cl_3CCCl_3 was formed in larger amounts at lower frequency than at higher frequency. In the presence of a radical scavenger TEMPO, the yield of the Cl_3CCCl_3 did not decrease at any frequencies. The result indicates that the CCl_3 radical is not released from the cavity, that is the site of the Cl_3CCCl_3 formation is inside the cavity. Frequency profile of H_2O_2 formation was different from that of Cl_3CCCl_3. H_2O_2 formation was effective at higher frequency. This suggests that sonolysis of BrCCl_3 occurs at lower frequency, while sonolysis of H_2O at higher frequency. Sonolysis of BrCCl_3 with 1-octene was also examined. Br,CCl_3-adduct of 1-octene was more effectively produced at 298kHz than other examined frequencies. The result in the presence of 1-octene and TEMPO indicates that the Br,CCl_3-adduct formation proceeds by a chain mechanism in the bulk medium.

抄録全体を表示

Various ketones were reacted with TiCl_4 and Zn under ultrasonication to give the corresponding coupling dimmers. Ketones were substituted with methoxy, hydroxy, acetoxy and bromine on the benzene ring. Using ultrasonication, the reaction time and yield of the reductive coupling reaction were changed better. Typical reaction was as follows. Substituted acetophenones(2.84mmol) were dissolved in THF. The solution was added with TiCl_4(4.60mmol) and Zn(9.07mmol) in THF at 0℃ and the reaction mixture was ultrasonicated under argon. The reaction mixture was added by sodium hydrogencarbonate and solution and extracted with ethyl acetate. The ethyl acetate extracts were concentrated in vacuo and the concentrated solution was chromatographed over silica gel, eluted with hexane-ethyl acetate, to give the corresponding dimer in good yield. In this reaction, various pinacols were produced concomitantly with pinacolones which were rearranged with acid catalysis, TiCl_4. All structural determination of these products was done using NMR, IR, MS and X-ray analysis. The reaction with or without ultrasonication was extremely different in the reaction time. 4'-Hydroxy or 4'-methoxyacetophenone were reacted very easily with ultrasonication to give the corresponding substituted pinacols. Pinacols substituted with phenols were easily synthesized using ultrasonication.

抄録全体を表示

The mechanism of ultrasonic degradation is still obscure, but it is well accepted that cavitation bubbles are mainly responsible for the degradation. The intense shear field generated by the collapse of the cavitation bubbles induces chain scission. Most of investigations on ultrasonic degradation have been carried out at low ultrasonic frequency around 20kHz. In this work, the ultrasonic degradation of methyl cellulose in aqueous solution was studied at two frequencies (20kHz and 500kHz) at the constant calorimetric power (20W) and temperature (25℃). The time variation of the average molecular weights and the molecular distribution were determined by Gel Permeation Chromatography (GPC). The mass average molecular weights (M_w) decreases with sonication time. The large lowering of M_w was observed at the frequency 500kHz. The degradation rate was suppressed by the addition of t-BuOH which act as a radical scavenger. The ultrasonic degradation rate coefficient k_d was estimated and compared with the results of other water-soluble polymers. The order of k_d value were PEO > Dextran 〓 Pullulan > MC. We will discuss on the frequency effects on the ultrasonic degradation.

抄録全体を表示

In ultrasonic atomization of ethanol water solution, it was confirmed that the enrichment of the ethanol in the droplets. It is thought that droplets with high concentration of the ethanol are generated by making the ethanol molecules localization on the solution surface. In this study, the temperature and concentration of ethanol solution were changed, and surface excess was estimated from the measured surface tension. The influence of the surface excess on the ethanol concentration rate by ultrasonic atomization was investigated.

抄録全体を表示

In order to clarify the effect of sonication to vesicle solution, we performed two series of experiments. Ultrasound frequency we used was 480kHz in both experiments. In the first experiment, we measured fluorescence decay of pyrene dissolved in the aqueous solution of didodecyldimethylammonium bromide (DDAB) under ultrasonic irradiation. It was found that fluorescence decay was promoted by ultrasonic irradiation. Mechanism of quenching by bromine generated from the bromide ion which was the counter ion of DDAB was suggested. It was shown that the suggested mechanism did not contradict with the experiment with additional bromine and quantitative evaluation of the chemical effect by potassium iodide (KI) dosimetry. In the second experiment, we prepared aqueous solution of dilauroyl phosphatidylcholine (DLPC) and homogenized vesicle size by using extruder. Then, we performed ultrasonic irradiation and analyzed the size distribution by dynamic light scattering (DLS). Decrease of size to a diameter around 100nm was observed up to three hours, and substantial increase of size was observed afterwards.

抄録全体を表示

We have developed a novel electrolysis system using acoustic emulsification. This new system involves the generation of a carbocation by electrolysis of substrate, and then its reaction with nucleophiles in situ. In this system, although the oxidation potential of nucleophile is lower than that of substrate, the substrate was selectively oxidized to give the corresponding cation intermediate because carbon nucleophile was trapped in electrochemically inactive droplets. Subsequently, the intermediate reacted with carbon nucleophile at the droplet interfaces. For instance, anodic substitution reaction of N-(methoxycarbonyl)pyrrolidine with allyltrimethylsilane was accomplished in 62% yield.

抄録全体を表示

The silver nano particles have been prepared by the reducing compound and the sonochemical irradiation of an aqueous solution of silver nitrate and polyvinylpyrrolidone. The silver nano particles were characterized using technique such as transmission electron microscopy, X-ray diffraction absorption spectroscopy, particle size analyzer by the dynamic light scattering. By the ultrasonic irradiation the absorbed spectra were shifted to lower wavelength, the distributions of the particles were sharper than the case without the ultrasonic irradiation.

抄録全体を表示

Single-walled carbon nanotubes were dispersed by tip-type sonication for 20, 120 and 180 min in the presence of surfactant. The diameter distributions of the three dispersions were compared by absorption spectra, indicating that absorbance of the larger diameters relatively decreased as the time of tip-sonication became longer. That is, the amount of larger diameters gradually decreased as compared with that of smaller ones according to the sonication time.

抄録全体を表示

High frequency ultrasound was applied to an emulsion to enhance the separation of emulsions into oil and water. The emulsion sample was prepared with mixing a mixture of dodecane, water and Span 80 as a surfactant. Volumetric ratio of water to oil was 1.5 and water in oil type emulsion was formed. Ultrasound of 2.4MHz was irradiated from the bottom of a cylindrical reservoir to the emulsion of 100cm^3. Emulsion separation was successfully enhanced by the ultrasonic irradiation. A layer of dodecane, continuous phase, appeared after a pretreatment for the turbidity analysis. A part of the layer was taken out and the absorbance at 800nm was measured to determine the degree of separation. Under applied power of 11W, time for the separation is about one fourth of the time for gravity settling. The time for the separation depends on input power to the ultrasonic transducer. With increasing the power, the separation improves. Volume of the emulsion was also varied at constant power input. The separation enhances with decreasing the emulsion volume. Thus, the power input per volume is an operating parameter for the separation.

抄録全体を表示

We have found a new removal method of humic acid from water by utilizing ultrasonic irradiation in the previous works. By the method, where ultrasound with a frequency of 200kHz is directly applied to water containing a very small amount of humic acid and then the treated water is held at a constant temperature, humic acid is precipitated in water, and its concentration dramatically decreases. (The brown aqueous solution of humic acid is decolorized as the precipitation of humic acid occurs.) In this study, to verify the validity of this method, experiments on ultrasonic treatment of humic acid solutions were performed under various conditions. The results obtained show that decrease in humic acid concentration in water is affected by the operating conditions such as ultrasonic irradiation power and ultrasonic reaction atmosphere. When the formation of OH radical in water is above 5.0×10^<-5>M during ultrasonic irradiation, humic acid is precipitated and its concentration in water decreases to blow 20% in the holding process.

抄録全体を表示

The sonolysis of organic materials was performed in an organic solvent. The evolution rates of CO and CO_2 from oxalic acid in acetic acid are similar to those in an aqueous solution. It is well known that water is a useful solvent for sonochemical reactions because the reactions proceed in this solvent. Furthermore, this solvent changes to active species under sonolysis and those species accelerate the reaction. For example, H_2O_2 and active radicals produced during sonication from water (solvent) attack to reactants. On the other hand, almost all organic solvents are inactive under ultrasonic irradiation. In fact, small amounts of products are obtained from acetic acid. Acetic acid, however, had been reported as an active solvent. Now we try a sonochemical organic reaction, such as degradation of oxalic acid, in acetic acid. As the results, higher evolution rates of CO and CO_2, which were sonolytical products from oxalic acid, were obtained in distilled acetic acid. Although rapid reaction was observed in the early stage of the reaction, the yields decreased sharply with sonication time because of changing dissolved gas suddenly. In other words, higher amount of gaseous products expelled Ar (original atmosphere) from the solvent under sonication. We would examine to maintain the higher reaction rate during all the period of sonolysis.

抄録全体を表示

Iron is expected as a positive electrode material because of its large Clarke number. In this reason, we have been interesting in iron based materials and been studying. In this time we focused on Fe_3PO_7. The theoretical capacity as cathode is 777mAh/g. Its large capacity is very attractive to compare to present materials being used as lithium ion batteries (LiCoO_2: 274mAh/g, LiMn_2O_4: 148mAh/g). The literature shows that Fe_3PO_7 was prepared by the two-step solid-state reaction. At first stoichiometric amounts of Fe_2O_3 and (NH_4)_2HPO_4 powders are mixed and heated 950 degrees Celsius for 12hour to synthesize FePO_4. Fe_2O_3 and FePO_4 are mixed and preheated 950 degrees Celsius for 12hour and finally heated at 1050 degrees Celsius and finally Fe_3PO_7 is prepared. Fe_3PO_7 requires a lot of time and high sintered temperature. To improve these problems, we have been studying about an easily synthesis method of Fe_3PO_7. In this study, we used the sonochemical method and try to obtain Fe_3PO_7 by one step reaction.

抄録全体を表示

Ultrasound (US) is widely used in polymer technologies, since sonication effect leads to improve the polymerization reaction. In the present work, we applied US effect in the hydrolysis of titanium tetra-isopropoxide (TTIP) to prepare the titanium dioxide (TiO_2). So, the preparation of anatase-TiO_2 powders by sol-gel process of TTIP was carried out under 28 kHz frequency US irradiation. During the sol-gel process was proceeded, cyclopentane carboxylic acid (CPCA) was added as template into the solution in order to imprint the molecule to the TiO_2 powder. The imprint efficiency of the TiO_2 powder was evaluated by re-binding CPCA substrate in gaseous phase. It was found that the binding amount of CPCA by US imprinted TiO_2 was higher than that of TiO_2 powder prepared without US.

抄録全体を表示

When an ultrasound is irradiated to the liquid, the micro bubble which is called cavitation bubble is formed. It is thought that the state of bubble becomes thousands of temperature and hundreds of pressures when this bubble collapses. Various chemical effects are induced by the hot and high pressure field. In this study, the bubble temperature estimated as the basic research of sonochemistry. Since it is difficult to measure bubble temperature directly, indirect method with a reaction kinetics was used for estimating the temperature by the generation ratio of the hydrocarbons which are produced by the methyl radical recombination. To prepare t-butanol solutions (2-30mM) 60ml of water is degassed with argon gas in the sonication cell. After the degassing, t-butanol was added into the water. These samples were irradiated by ultrasound of 200kHz and the solution temperature was kept at 20℃. The reaction products were analyzed by a gas chromatography. After the sonication, in solution with concentration 2 to 12mM, the bubble temperature became a constant or maximum value in the range from 5 to 20 minutes. It was found that the relation between each t-butanol concentration and the maximum bubble temperature was in the good linear relation. Extrapolating the linear part of a maximum temperature to 0mM, the temperature becomes about 4200K.

抄録全体を表示

The formation of H_2O_2 was studied with ultrasound irradiation in the presence of TiO_2 or Al_2O_3 particles. The effect of varying the temperature of cavitation bubbles in aqueous solutions of two rare gases (Ar, Xe or mixture of Xe and Ne (Xe:Ne=3:7)) on the formation of H_2O_2 were estimated. The very high temperatures (several thousand K) of collapsing gas bubbles lead to the thermal dissociation of water molecules into OH radicals, and the reaction of two OH radicals causes the formation of H_2O_2 consequently. After 60 min sonication with 25〜36kHz ultrasound the highest concentration of H_2O_2 (612μM) was observed when Xe was saturated in the solution. While the increased concentration of H_2O_2 after 60 min sonication was lower (135μM) in the solution saturated with Ar or mixture of Xe and Ne. The difference in the increased concentration of H_2O_2 was not significant between Ar and mixture of Xe and Ne. These results suggest that the threshold for the formation of cavitation bubbles seems to be the lowest in the solution saturated with Xe and to be the important factor for the formation of H_2O_2 during the sonication in the presence of TiO_2 or Al_2O_3, respectively.

抄録全体を表示

We introduce tiny air bubbles including micrometer-sized ones produced by method of atomization into aqueous luminol solution under 141kHz sonication in order to investigate the enhancement of sonochemical reaction rate by introduction of tiny bubbles through the intensity measurement of sonochemiluminescence(SCL). It is shown that the introduction of tiny bubbles under sonication accomplishes the large SCL intensity compared to the cases of sonication only and, liquid flow under sonication. Therefore, the present method of introduction of tiny bubbles is effective for enhancement of sonochemical reaction rate.

抄録全体を表示

In recent years, there has been a great deal of attention paid to problems relating to nonlinear acoustics in ultrasound fields. In this study, an alternative method is proposed for the determination of the acoustic harmonic components using the voltammetric electrode as an acoustic probe. The electrochemical reduction current of 1mM ferricyanide in KCl supporting electrolyte increased significantly in the presence of ultrasound irradiation due to an extremely enhanced mass transport. Under the ultrasound irradiation, the transient response and the a.c. components of the current were measured with digital oscilloscope, and the data was then analyzed by fast Fourier transform (FFT). Several harmonic components, 2f_0, 3f_0 and 4f_0 were observed in FFT spectrum besides the fundamental frequency. Although the detailed mechanism for sound response at the electrode has not been very clear, the electrode seems to be available for sensing the tiny acoustic pressure oscillation with high sensitivity in aqueous solution. It thus facilitated for in situ monitoring the noise generations in ultrasonic fields. Evidence shows that the harmonic components depended strongly on the experimental parameters, such as output power, the exit of cavitational bubbles or other microparticles, the distance separating from the ultrasonic source or the reflection of waves from boundaries. These effects were examined in the present study.

抄録全体を表示

Multibubble sonoluminescence spectra from argon-saturated aqueous solution of NaCl were measured at the frequency of 137.5kHz for the ultrasonic powers ranging from 2.1 to 16.2W. Na-atom emission line near 589nm observed were broadened and asymmetric towards red zone. The line intensity and half-peak width changed at different ultrasonic powers. The addition of ethanol caused rapid quenching and line broadening effects. The results suggested the Na-atom emission occurs inside bubbles.

抄録全体を表示