Noncontact manipulation technique is needed in micromachine technology, biotechnology and so on. The radiation pressure of ultrasound may be used for this purpose. It is possible to trap small objects at the sound pressure nodes of a standing wave field in the medium. When the sound field is changed, the trapped particles are moved. By the way, a microbubble is trapped in a sound pressure antinode of the standing wave field. A small single-bubble was illuminated using a stroboscope and its shadow images were captured with a synchronized CCD camera settled at the opposite side of the light sources.

抄録全体を表示

Effective method for the separation of fatty acid and oil in used cooking oil or rubber seeds oil has been developed by using liquid-liquid separation after formation of ammonia salt or liquid- solid separation after the formation of metal salt. Ultrasound irradiation could be effectively utilized to produce small particle size metal soap.

抄録全体を表示

When a short-pulsed high voltage with a high repetition frequency is applied for a couple of metal electrodes in water, glow discharge plasma is generated near the gap between the electrodes. The plasma in the solution and the sonochemical hot spot have a common feature that they are high energy reaction sites generated in water having a gas/liquid interface. In this study, we compared the plasma in the solution with the sonochemical reaction sites. Decomposition of volatile solute effectively proceeded by the plasma in the aqueous solution because vaporization of the solute into the plasma does not hinder the decomposition, differing from the sonochemical hot spots. The temperature deduced from the decomposition products of tert-BuOH was about 4200 K, being close to the experimentally obtained temperature of the sonochemical hot spot. In the reductive preparation of metal nanoparticles by the plasma, the reductants for noble metal ions were generated from the added organic solutes such as surfactants or alcohols. Hydrophobic and/or surface active solutes effectively accelerated the reduction because they are accumulated in the vicinity of the gas/liquid interface, which is similar model with the sonochemical reduction of metal ions.

抄録全体を表示

Horn-type ultrasonic generators have been frequently used for processing of materials in emulsification, particle dispersion and sonochemical reactions. Cavitation plays a significant role in the processing; however, it would bring about the concern of contamination due to cavitation erosion of the horn material. Some researchers point out the occurrence of micrometer sized particle. In the present study, the formation of finer particles was studied by using optical analyzers to measure nanometer sized particles. For various input energies, particle size distribution was analyzed as well as the number densities. Formation of about 100 nm particles was detected and the number density increased with increasing the power input.

抄録全体を表示

Effect of air in gas and liquid phases on the reduction of [AuCl₄]^-, oxidation of I^-, dissociation of methylene blue (MB) in aqueous solutions by irradiation of high-frequency ultrasound (HF-US) was examined to evaluate the mechanism on the sonolysis in aqueous solutions generated by irradiation of HF-US. We found that the reduction of [AuCl₄]^- by irradiation of HF-US was significantly affected by air content in gas phase in aqueous solutions. This suggests that radical species generated from air at air/solution interface assist the [AuCl₄]^- reduction in aqueous solutions. The I^- oxidation by irradiation of HF-US was significantly affected by air content in liquid phase. This suggests that that radical species generated from air in the aqueous solution assist I^- oxidation in aqueous solutions. The dissociation of MB by irradiation of HF-US was affected by air content in both gas and liquid phases. This suggests that radical species generated from air in gas and liquid phases do not contribute to the dissociation of MB in aqueous solutions.

抄録全体を表示

Development of sonochemical reactor with high efficiency is necessary to put sonochemical process into practical use. With the intention to supply nuclei of cavitation bubble and increase cavitation amount, ultrafine bubble (UFB) whose diameter was lower than 1 μm was generated in the reactor. The reactor consisted of two vessels. One vessel contained a 488 kHz transducer to generate sonochemical reaction. Another vessel contained a 22 kHz transducer and boiling stone to generate UFB. Two vessels were connected by liquid pump and tubes. Sample was 0.1 M KI aqueous solution which was prepared using ultrapure water or high-density UFB water. High-density UFB water was produced by pressurized dissolution method. I₃^- production amount for high-density UFB water was higher than that for ultrapure water. However, UFB number in high-density UFB water rapidly reduced by ultrasound at 488 kHz. Many UFB generated by ultrasound at 22 kHz and boiling stone in ultrapure water. Ultrafine bubble sonoreactor with 488 kHz, 22 kHz and boiling stone showed additional increase in I₃^- production amount.

抄録全体を表示

In this study, 430 kHz of ultrasonication which can cause pyrolysis by chemical effect and atomization by physical effect simultaneously was selected and applied to highly effective decomposition of organic pollutants in water. In order to investigate the influence of physical properties on the degradation rate, three different aldehydes, formaldehyde, acetaldehyde and benzaldehyde, were chosen as model substances. As a result, removal ratio of formaldehyde, acetaldehyde and benzaldehyde reached 21.1%, 53.0% and 100% after 120 min by only US irradiation, respectively. It means that the decomposition of hydrophobic organic compounds proceeds rapidly in liquid phase by pyrolysis inside the cavity. Also, in the case of combining the UV irradiation and the ultrasonic atomization, formaldehyde and acetaldehyde with hydrophilic property were effectively decomposed on the mist surface in gas phase, however, benzaldehyde with hydrophobicity was hardly decomposed in the same condition. From these results, it was confirmed that UV irradiation acts on decomposition of hydrophilic organic compounds which exist inside or surface of the mist effectively.

抄録全体を表示

Poly (N-Isopropylacrylamide-co-2-hydroxyethyl methacrylate) (P(NIPAM-co-HEMA)) was synthesized using ultrasonic irradiation in a mixed solvent of water and ethanol without chemical initiator. The effects of ultrasonic intensity, irradiation time and monomer molar ratio on lower critical temperature (LCST) (measurement of responsive temperature) of synthesized polymers were investigated. The LCST of the copolymer obtained at the completion of the reaction linearly increased with the copolymer composition. However, the LCST of the copolymer obtained in the early stage of the reaction was higher than that estimated by the copolymer composition. These results suggested that some parts of the polymer chain have higher NIPAM composition than overall composition because of the difference of the reactivity of the monomers. The difference in the LCST between experimental data and estimated values from copolymer composition was higher for higher NIPAM ratio of initial monomer composition.

抄録全体を表示

Both acoustic cavitation and HV pulse discharge have been investigated widely on wastewater treatment in the past. However, when these techniques are applied singly, they efficiency remains low. In this study, a novel treatment method was proposed by combing these two techniques to achieve a synergetic effect. A lab scale system was designed and experimentally tested. Rhodamine B was chosen as an organic pollutant to identify the treatment efficiency of the proposed method. Results indicated that treatment efficiency is significantly higher compared to single ultrasound or pulse discharge, suggesting a promising way for wastewater treatment.

抄録全体を表示

The high temperature and high pressure conditions at cavitation bubble collapse can influence the decay of radioactive atoms. We investigated the effect of acoustic cavitation on electron caption of ⁴⁰K. Gamma-ray spectrum from 3 M KCl aqeous solution under acoustic cavitation at 85 kHz and 90W. Some data showing the increase in the counts of the gammma-ray spectrum were obtained, however, further experiments are needed to conclude that the increase was due to the enhancement of the radioactive decay or to electric or mechanical noise.

抄録全体を表示

Acid mine drainage includes arsenic. Arsenic is toxic for human body. Therefore, it is necessary to treat arsenic in solutions with adsorbents before discharge. Recently, porous iron oxide is reported as an adsorbent of arsenic acid (As(V)) in acidic condition. Porous iron oxide is aggregate of fine maghemite(γ-Fe₂O₃) particles and it is synthesized using alkaline treatment of scorodite(FeAsO₄·2H₂O) or strengite(FePO₄·2H₂O). The porous iron oxide keeps original particle's shape and size after alkaline treatment. Thus, the material synthesized using large raw material will show good sedimentation property and large specific surface area. On the other hand, spherical is desirable figure to use the material in column. In this study, we synthesized amorphous iron phosphate dihydrate with large and spherical particle using ultrasound oxidation. The ultrasound irradiation advanced particle growth with continuous oxidation and the particle size was 1 μm for 4 h sonication. The porous iron oxide synthesized from amorphous dihydrate iron oxide showed good adsorption capacity of As(V).

抄録全体を表示

Ferrite nanoparticles, such as magnetite (Fe₃O₄), cobalt ferrite (CoFe₂O₄), manganese zinc ferrite (Mn_xZn_1-xFe₂O₄), etc., were sonochemically synthesized and their magnetic properties were investigated. For magnetite nanoparticles, XRD analyses and TEM observations showed that the synthesized particles were magnetite with ca. 20 nm in diameter. The magnetic susceptibility measurements showed that the magnetite nanoparticles have superparamagnetism with the blocking temperature of 210 K but the remnant magnetization was not zero at 300 K. This is probably because there are some relatively large nanoparticles. For cobalt ferrite nanoparticles, the coercivity was larger than that of magnetite nanoparticles to achieve the desired magnetic characteristics. The morphology, the size and the dispersion of the nanoparticles depended significantly on experimental conditions, while it means they can be controllable by the setting.

抄録全体を表示

Nano/micro-structured conducting polymeric materials are of great importance for the significant range of applications such as sensors and energy storage. In this work, we wish to report an electropolymerization in the acoustically prepared foam to obtain polyaniline (PANI) film with microporous structure on an electrode surface. In this process, ultrasonication was used to foam the electrolyte solution containing surfactant and the foamy electrolyte was employed as soft template for the polymer growth. SEM analysis revealed that the obtained PANI film possessed a porous structure composed of a number of micropores. In addition, it was also found that the porous PANI film exhibited a good electrochemical response. Since no hard templates and cumbersome procedures are require for this synthetic method, it is advantageous in respect of environmental and economic sustainability.

抄録全体を表示

Aqueous coumarin, coumarin-3-carboxylic acid and 3-aminocoumarin were exposed by ultrasound (US) with 500 kHz at 25 W out-put. After the US exposed, fluorescence spectra were measured to evaluate the concentration of each umbellifeorne derivative in oreder to quantify amount of OH radical in the US medium. When US was exposed, the fluorescent intensity of umbelliferone at 454 nm increased with US exposure time meaning that coumarin reacted occurred with OH radical generated by US medium. In 3-aminocoumarin and coumarin-3-carboxyic acid, similar reaction occurred with OH radical. The order of amount of OH radical forward was following 3-aminocoumarin > coumarin > coumarin-3-carboxylic acid in the US condition at pH7.

抄録全体を表示

Gold nanoparticles possess the size- and shape-dependent catalytic and optical properties. Synthesis by ultrasonic cavitation needs no surfactant and reductive agents. Ultrafine bubble (UFB) which is smaller than 1 μm in diameter has high charge on the surface and long residence time. In this study, we investigated how UFB effect the synthesis of gold nanoparticles by ultrasound. Sample was 0.1 mM HAuCl₄ solution. Ultrasonic frequency and temperature were 500 kHz and 283 K, respectively. By addition of UFB, nucleus generation time was shorten, diameter of gold nanoparticles decreased and diameter distribution of spherical particles became narrow. As the UFB density became higher, dimeter of gold nanoparticles became smaller. It is thought that UFB enhances cavitation generation and UFB attached on nanoparticles prevents aggregation of nanoparticles. As the UFB density increased, fraction of plate particles decreases. This is because formation rate of plate particles is slower than that of sphere particles.

抄録全体を表示

Application of Au nanoparticles to various fields has been studied actively because of its unique characteristics different from those of bulk. However, the formation mechanism of Au nanoparticles is still unclear. If the formation mechanism of Au nanoparticles was clarified in more details and the size of Au nanoparticles was controlled more precisely, the application range of Au nanoparticles should be expanded dramatically. The reducing radicals formed in the sonolysis of solution containing Au(III) and colloidal stabilizers, etc., result in the formation of Au seed particles via reduction of Au(III). In this study, seed-mediated growth was carried out using catalysis of Au seed particles formed by the sonochemical reduction of some of Au (III) in the presence of citrate under argon atmosphere. By analyzing the number and average diameter of resulting Au nanoparticles, we discussed the mechanism of seed-mediated growth of Au seed particles. Furthermore, effects of irradiation time and pH on the Au seed growth were investigated.

抄録全体を表示

We report here on the fabrication of gold hollow microspheres using ultrasound-generated microbubbles as templates in an aqueous poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) block copolymer solution. We found that the gold hollow microspheres were not formed in a PEO-PPO block copolymer solution. On the other hand, the gold hollow microspheres were formed in a PEO-PPO block copolymer solution containing an anionic fluorosurfactant. Mechanism on the formation of gold hollow microspheres using microbubbles as templates in a PEO-PPO block copolymer solution containing an anionic fluorosurfactant was proposed as follows: (i) anionic fluorosurfactants adsorb on the surface of microbubble, (ii) PEO-PPO block copolymers adsorb on the adsorbed layer of anionic fluorosurfactants on microbubble and (iii) [AuCl₄]^- is reduced at the adsorbed layer of PEO-PPO block copolymers on microbubbles.

抄録全体を表示

Potential of high-power bath-type ultrasonic irradiator (named as US-eM) that we developed for emulsification was examined to develop the high-efficiency emulsification equipment. We found that US-eM enables to produce the emulsifier-free (EF-) dodecane-in-water (DD/W) emulsions with the treatment for 1 min. Diameter of DD droplets in EF-DD/W emulsions prepared with US-eM reached to several hundred nanometers with the treatment for 1 min. On the other hand, the diameters of DD droplets in EF-DD/W emulsions prepared by commercial available rotor-stator homogenizer, ultrasonic homogenizer and ultrasonic cleaner were several micrometers. Furthermore, the colloidal stability of EF-DD/W emulsions prepared by US-eM was higher than EF-DD/W emulsions prepared by commercial available rotor-stator homogenizer, ultrasonic homogenizer and ultrasonic cleaner.

抄録全体を表示

Food rot and quality deterioration are caused by fungi and bacteria. Sterilization by general methods is difficult since spore-forming bacteria are resistant to drying, high temperature, and chemicals. Ultrasonic cavitation has been drawing attention because it has bactericidal effect and does not emit hazardous substances during the sterilization of food. In this study, we examined the inactivation of spores and vegetative cells of Bacillus subtilis, which is a kind of spore-forming bacteria, using different ultrasonic frequencies. These experiments used acoustic power of 10 W and frequencies of 0.02, 0.4, 1.0, 2.3, 3.4 and 4.4 MHz. We investigated sound power density as a condition necessary for the inactivation of B. subtilis spores.

抄録全体を表示

Selenium (Se(IV), Se(VI)) and arsenic (As(III), As(V)) are toxicity for human body. Therefore, it is necessary to remove these ions from solutions to adsorbents before discharge. To remove selenium and arsenic, oxidation treatment is important. Because Se(VI) and As(V) are lower toxicity than Se(IV) and As(III), respectively. It is well known that the ratio of As removal using iron hydroxide is much higher for As(V) than that for As(III). Therefore, it is crucial to efficiently oxidize As(III) to As(V). On other hand, the main removal method of Se is adsorption of Se(IV) reduced from Se(VI) onto Fe(OH)₃. There are only few reports to treat Se by oxidation method. Therefore, oxidation of Se(IV) using ultrasound irradiation and adsorption of Se(VI) using synthesized maghemite (γ-Fe₂O₃) were studied. We also studied oxidation of As(III) using ultrasound irradiation. Oxidation ratio of As(III) to As(V) showed 100 % for 60 min irradiation. However, oxidation ratio of Se(IV) to Se(VI) showed only 4 % for 60 min irradiation. Finally, we evaluated adsorption capacity of synthesized maghemite. It could adsorb 99.4 % of Se(VI) in the solution (10 ppm, pH 2.0).

抄録全体を表示

Silver nanowires transparent conductive films are expected as a material to replace indium tin oxide films. Silver nanowires are mainly synthesized by the polyol method, which used protective agents to achieve an anisotropic crystal growth. However, protective agents decrease conductivity of the films because they cover the surface of nanowires. In this study, we have conveniently synthesized needle-shaped silver carboxylates by ultrasound irradiation, and then obtained silver nanowires transparent conductive films by spray coating them on substrates and exposing them to gas-phase hydrazine. Silver carboxylates were synthesized by ultrasound irradiation to mixture that contains silver(I) oxide, acetic acid, propionic acid, and ethanol. These carboxylates were put onto a glass substrate, and then reduced by exposure to hydrazine gas (vaporized hydrazine monohydrate). The obtained samples were characterized by FE-SEM, XRD, TG-DTA, four-probe method, and UV-Vis. Silver oxide completely reacted and silver carboxylates produced after 1 h of ultrasound irradiation (44.13 kHz). The aspect ratio of the particles was improved by shortening the reaction time. And ultrasound irradiation (1.062 MHz) precipitated only unreacted silver oxide and promoted particle growth. Using the prepared precursor, we successfully fabricated silver nanowire transparent conductive films with high performance.

抄録全体を表示

By ISO, “ultrafine bubbles (UFBs)” are defined as bubbles which diameter is less than 1 μm. UFBs are usually produced with a few kinds of special techniques which use continuous liquid flow by a mechanical pump. To compact or to produce small amount of UFB containing water, however, it is difficult by those UFB generation methods. Therefore, in this study, a novel generation technology of UFBs was developed. UFBs were produced batchwise by using ultrasonic irradiation into a bottled water. The number density of UFBs in water depended on dissolved gas concentration, ultrasonic irradiation time, stationary wave and height of liquid. By a correlation of experimental results, a semi-theoretical equation was proposed. The generation of UFBs in water was promoted by solubility change by pressure fluctuation due to ultrasonic wave. Moreover, it was confirmed that no contamination derived from cavitation erosion of an ultrasonic transducer.

抄録全体を表示

Advanced oxidation processes (AOPs) were widely investigated to solve environmental pollution caused by organic pollutants. In this study, we focused on photocatalytic degradation under ultrasonic irradiation without the light source. Because by the US irradiation, photocatalyst can work under dark condition. Zinc oxide (ZnO) which is cheaper than TiO₂ was chosen as the photocatalyst in this study. On the other hand, two types of aldehydes with different physical properties, benzaldehyde and formaldehyde, were chosen as model organic poluutants in water to investigate those reactivity under US irradiation. In case of US/ZnO condition, removal ratio of benzaldehyde was remarkably improved like US/TiO₂ condition. However, it only confirmed in the early stages of the degradation. From this result, it was thought that the reaction by US/ZnO can be dependent on pH of the solution and the degradation products.

抄録全体を表示

The effects of I^- ions on the yield of OH radicals and H₂ formed in the sonolysis of water were investigated under Ar. It was confirmed that the yield of I₃^- and H₂ decreased with increasing KI concentration. It was suggested that the generated OH radicals not only recombined but also reacted with halide ions. It was suggested that sonochemical reaction of hydrogen peroxide with I^- ions was affected by pH solution’s. For comparison, aqueous HI solution and aqueous NaCl solution we’re also investigated. The behavior of OH radicals during aqueous solution affected by the presence of halide ions.

抄録全体を表示

Multi-bubble sonoluminescence spectra from Ar-saturated water with 2 mM alcohol (methanol, ethanol, 1-propanol, and 1-butanol) acting as radical scavengers were measured over 257-540 nm for different durations. 10 W of acoustic power was used (measured by calorimetry) at an ultrasonic frequency of 410 kHz. Addition of alcohol to the water dampened the multi-bubble sonoluminescence intensity. The sonoluminescence (continuum emission and OH radical emission) intensity decreased with increasing irradiation time. The decreasing rate of sonoluminescence was enhanced when more hydrophobic 1-butanol was added. In addition, when Ar-saturated water containing more hydrophobic 1-butanol was sonicated, larger amounts of gaseous products were generated. When less hydrophobic methanol was used instead of 1-butanol, not only decreasing rate of sonoluminescence, but generation of gaseous products were depressed. In conclusion, the decrease in sonoluminescence intensity with increasing irradiation time was attributed to the degradation products of alcohols, and depends upon the hydrophobicity of the added alcohols.

抄録全体を表示

Efficient and control release of Nicotine is essential in treatments for neurodegenerative diseases. So, 0.1 wt% of Nicotine loaded biocompatible cellulose hydrogels were prepared using phase-inversion method and exposed to ultrasounds (US) at different US powers (10W and 30W), and frequencies (23 kHz, 43 kHz and 96 kHz). Then, released Nicotine concentrations were studied using UV-Vis spectra to observe the effectiveness of US on Nicotine release. US frequency of 43 kHz at 30 W shows the highest Nicotine release from the hydrogels prepared from solution contains 0.1 wt% Nicotine and 0.9 wt % of cellulose.

抄録全体を表示

Bubbles of less than 1 μm in diameter are called ultrafine bubbles (UFB). When ultrasound was irradiated to ultrapure water in a vessel, the change of number density of UFB with irradiation time was investigated in ultrasonic frequency at 22, 43, 129, 488 kHz and 1 MHz. The number density of UFB exponentially increased with irradiation time. The number density of UFB increased with decreasing frequency. The mean and mode diameters of UFB after ultrasonic irradiation for 5 minutes to ultrapure water were 100 - 120 nm and 90 - 100 nm, respectively. Furthermore, when ultrasound was irradiated to water containing high-concentration UFB, the change of number density of UFB with irradiation time was investigated. The number density of UFB decreased exponentially with irradiation time. The number density of UFB decreased with increasing frequency. Therefore, it was clear that generation and reduction of UFB occurred simultaneously by ultrasonic irradiation to water.

抄録全体を表示

Magnetite and other iron-based materials are now expected for advanced medical applications. In a wet-chemical synthesis of magnetic particles, ultrasound is very useful to reduce the process time, to control the nucleation, and to control oxidation from Fe²⁺ to Fe³⁺. At a glance, the last term should be enhanced by ultrasonication. However, it is not always the case. If the initial precipitate of Fe(OH)₂ is dissolved effectively by the ultrasound, more Fe²⁺ ions are supplied to the system, and consequent product of magnetite (Fe₃O₄) involves more amount of Fe²⁺. It should be indicated that chemical formula of Fe₃O₄ is somewhat misunderstanding because it has non-stoichiometry from Fe₃O₄ (= FeO-Fe₂O₃) to γ-Fe₂O₃, which are not distinguished by a usual XRD (x-ray diffraction) measurement.

抄録全体を表示

Metal nanoparticles have been applied and researched in various fields (catalysts, sensors, cancer treatments). Although the particle size and shape of metal nanoparticles formed have been investigated in details, the number of reports on investigating the nucleation and growth processes of metal nanoparticles is still limited. In this study, we discussed the nucleation and growth processes of gold and palladium nanoparticles by using a standing wave sonication system with 200 kHz ultrasound. In addition, we tried to synthesize size- and shape- controlled gold and palladium nanoparticles as a function of various experimental parameters of organic and inorganic additives.

抄録全体を表示

Recently, methods for delivery of peptide and RNA to target cells are widely studied for cell research and drug delivery strategies. However, the delivery methods sometimes have problems such as cytotoxicity and ineffective delivery. In some methods, target molecules tend to be trapped in endosome and degraded by lysosome when introduced to cells. In this study, ultrasound-dependent peptide / nanoparticle delivery method was developed. We developed a molecular conjugate of a cell-penetrating peptide, a sonosensitizer and a functional peptide / nanoparticle. This molecule was trapped in endosome when cells were incubated with the molecule. However, we succeeded in cytoplasmic delivery of the molecule that escape from endosome by ultrasound irradiation.

抄録全体を表示

The inactivation of microorganisms in water using ultrasonic has been extensively studied. One of the factors responsible for inactivation is the destruction of microorganisms by ultrasonic waves. We have reported that the main factor for the destruction phenomenon is the mechanical resonance of the microorganisms themselves.
In this study, microcapsules having equal size and wide particle size similar to that of algae were substituted as samples, and experiments were conducted with constant physical properties other than particle size. We irradiated the microcapsules with ultrasonic waves of different frequencies, and examined the effect of particle diameter and ultrasonic frequency on the destruction phenomenon.

抄録全体を表示

Sonochemiluminescence (SCL) from aqueous solution of lucigenin (Luc²⁺) has been studied with using aliphatic amines, such as ethylamine, propylamine, dipropylamine, tripropylamine and trimethylamine (TEA) as coreactant. It is found that strong SCL was observed from oxygen saturated alkaline solution containing Luc²⁺ when small amount TEA was added into the solution. A possible pathway for Luc²⁺ SCL reaction is discussed. In the ultrasonic field, TEA can adsorb onto the cavitation bubble/solution interface where TEA is oxidized by OH• to form TEA•⁺ and subsequently produce a highly reducing TEA• from the deprotonation reaction of the TEA•⁺. TEA• is suggested to initiate the reduction reactions of Luc²⁺ and O₂ and lead to the generation of Luc•⁺ and O₂•^-, respectively. The radical-radical coupling reaction between Luc•⁺ and O₂•^- is expected to initiate the light emission.

抄録全体を表示

Electrochemiluminescence (ECL) of [Ru(bpy)₃]²⁺ using lidocaine as coreactant has been studied upon ultrasound irradiation. ECL signal is detected at +1.2 V (vs. Ag/AgCl) at pH 9.0, which is confirmed by the generation excite state of [Ru(bpy)₃]²⁺ through homogeneous electron transfer process between [Ru(bpy)₃]³⁺ and lidocaine oxidative intermediate radicals at the electrode surface. At pH 11.0, however, two of specific ECL peaks are exhibited at +1.2 V and +1.5 V, respectively, indicating the different reaction route for ECL generation. Under the irradiation by 430 kHz ultrasound, the ECL intensity at +1.2 V increased with the decreasing of ECL intensity at +1.5 V. The ECL at +1.5 V is supposed to be generated between [Ru(bpy)₃]³⁺ and the intermediate species from the electrochemical decomposition of lidocaine. Because relatively low ECL intensity at +1.5 V was measured under ultrasound irradiation, the generation of intermediate radical of lidocaine by chemical reaction to hydroxyl radical was proposed.

抄録全体を表示

we have observed an orange emission during multi-bubbles sonoluminescence (MBSL) measurements in Kr saturated water at 1 MHz. The orange emission was observed only with the transducer, which has a partly peeled ground electrode by cavitation erosion. We confirmed the electric fields leaking from the damaged surface of the transducer. The spectrum of the orange emission showed a broad component, whose intensity gradually increased towards the near-infrared region with peaks at about 710 and 810 nm. The results of spectral measurements suggest that the origin of the emission is vibration-rotation transitions of water molecules. The charge induction by the electric fields leaked from the transducer and the charged droplet model are plausible explanation of the emission mechanism.

抄録全体を表示

The mechanism of electrochemical reduction of copper (II) ion on glassy carbon has been investigated under the influence of power ultrasound (20 kHz), using voltammetry and electrochemical impedance spectroscopy (EIS). The experiments were conducted with a sonoelectrochemical cell, placing an ultrasound probe directly above the working electrode. Ultrasound was found to have a significant effect on the electrodeposition rate of copper especially in hydrogen co-deposition potential range. It is suggested that the ultrasound plays an important role in ensuring mass transport, and suppressing hydrogen evolution at the electrode surface. The kinetic parameters of the copper electrodeposition reaction obtained by Tafel plot and EIS measurement lead to the conclusion that ultrasound promotes the electron transfer process arising from both thermal effect and surface activation effect by ultrasonic cavitation.

抄録全体を表示

Sonochemical degradation mechanism of organic solvent is still unclear because of a complicated relation between the degradation compounds and the condition of the cavitation bubbles although some investigations in terms of this issue have been reported. In this study, we performed the sonolysis of n-dodecane, iso-dodecane, and decahydronaphthalene as a model compounds of lubricating oil to investigated the degradation mechanisms by the cavitation phenomena. The degradation products were analized with HS-GCMS and ESR especially for radical compounds.

抄録全体を表示

Sonolysis of cationic surfactant, alkylbenzene ammonium salt (BAC) with different carbon chain length was investigated to analyze the reaction at the interface of cavitation bubbles. BACs accumulate at the gas-liquid interface of cavitation bubbles but do not go into the bubbles because of their involatile and amphiphilic properties. We also compared the sonochemical degradation rate of cation surfactant with that of anion surfactant previously reported.The surface potential of cavitaion bubbles was discussed on the basis of relation between initial surfactant concentration and thier critical micelle concentration.

抄録全体を表示

Cavitation bubbles are formed when ultrasound is irradiated in a liquid. When the bubbles are adiabatically collapsed, the inside of the bubbles becomes high temperature and high pressure, and OH radicals are generated by degradation of water. By using OH radicals and high temperature and high pressure bubbles, the degradation of various organic compounds such as aromatic compounds has been reported. In organic acids, the sonochemical degradation of butyric acid, which is a malodorous substance, has been reported. In this study, we investigated to analyze the sonochemical degradation behavior of various organic acids with different alkyl chain length. It was confirmed that the rates of sonochemical degradation of organic acids increased with increasing carbon number of organic acids up to C9 (sodium caprate).

抄録全体を表示

Ultrasound has been found to be an attractive advanced oxidation technology for the degradation of hazardous organic compounds in water. The ultrasonic degradation of methylene blue as a model hazardous organic compound was carried out in the absence and presence of dimethyl sulfoxide (DMSO) as a radical scavenger for various frequencies and temperatures, and the effects of DMSO addition on the degradation rate constant estimated by assuming first-order kinetics were investigated. The degradation of methylene blue mainly proceeds via oxidation reaction with hydroxyl radicals, but also proceeds via a direct pyrolysis reaction. Also, the apparent degradation rate constant increased with increasing temperature both in the absence and presence of DMSO. The effects of degradation mechanism of activation energy was investigated, and the activation energy of hydroxyl degradation was higher than that of pyrolysis.

抄録全体を表示

When water under air atmosphere is irradiated with high intensity ultrasound, cavitation is generated. When the bubbles are adiabatically collapsed, the inside of the bubbles becomes high temperature and high pressure, where nitrogen is oxidized to form nitrite and nitrate ions. In this study, analyses of nitrite and nitrate ions were performed to discuss the chemical effects of such high temperature and high pressure condition during collapsing bubbles. In addition, the results were compared with the yield of hydrogen peroxide formed in the sonolysis of water. We investigated the effects of types of dissolved gases such as mixtures of air and argon, and mixtures of air and carbon dioxide on the formation of nitrite ions, nitrate ions and hydrogen peroxide by ultrasound cavitation. It was confirmed that the amount of nitrite and nitrate ions formed increased in the presence of argon, but decreased in the presence of carbon dioxide. It was clear that dissolved gas of argon and carbon dioxide in water affected the condition of collapsing bubbles.

抄録全体を表示

In previous paper, we demonstrated the rate of sono-oxidation increased with the introduction of a small amount of CO₂. In this presentation, we report influences of concentration of KI and sonication time on the rate of sono-oxidation in a CO₂-Ar atmosphere. Sonication was performed using an ultrasonic irradiator (shinka, 200 kHz, 100 W) for 25 ℃. The rate of sono-oxidation was evaluated by potassium iodide (0.01 M KI) dosimetry using UV-Vis spectrophotometer (JASCO V-650, measuring wavelength is 355 nm). The rate difference between with and without CO₂ in an Ar atmosphere indicates Improvement index, which means the ratio of absorbance in a CO₂-Ar atmosphere to that in Ar atmosphere. The Improvement index increased with decreasing KI concentration. Maximum Improvement index was recorded about 9 times at 0.01 M after 30 min sonication. Influence of sonication time on Improvement index, on the other hand, we got about 40 times at 0.01 M after 1.5 hours sonication.

抄録全体を表示

The deposition of amyloid fibrils is associated with the pathology of more than 30 disorders. α-Synuclein (α-syn) consisting of a 140-residue is an intrinsically disordered protein that is linked to Parkinson’s disease neuropathologically. Recently, Cremers et al. reported that polyphosphate (polyP) accelerated the amyloid fibrillation of several amyloidogenic proteins, though the mechanism of polyP-induced amyloid fibrillation is not well understood. In this study, we investigated the effects of polyPs with different chain lengths on the amyloid fibrillation of α-syn under the ultrasonication. We found that the fibrillation of α-syn was significantly accelerated depending on the chain length and concentration of polyPs. Intriguingly, long-chain polyPs revealed the two optimum concentrations for the fibrillation; low and high concentrations. These promoting effects for the fibrillation were interpreted by the charge interaction with the protein and the salting-out effects of polyP under the ultrasonication. These results suggest an important role of biopolymer on amyloid fibrillation in vivo.

抄録全体を表示

Corn cellulose powder (CCP) was produced from corn powder by chemical treatment and bleaching process. CCP was stirred in distilled water over night and exposed to ultrasound (US) 30min with 23kHz, 96kHz, 141kHz, 500kHz consecutively. After the US was exposed at different frequencies, distribution of CCP were measured and particle size of CCP grew smaller along with increasing frequency. TEM images and FT-IR spectra showed that the hydrogen bond between cellulose molecules were destructed by ultrasound. These results indicated that ultrasound is effective in cellulose dispersion in water medium.

抄録全体を表示

We have so far developed novel and facile synthesis methods of noble metal nanoparticles and metal clusters such as gold and silver. By using ultrasonic irradiation technique, we could synthesize gold and silver clusters with benzenethiol derivatives and characterize photochemical properties of as-prepared clusters. Moreover, we have synthesized stable AuNPs by a simple ultrasonic irradiation in water/alcohol binary solutions without additive stabilizer agents. Methanol, ethanol, and 1-propanol are used as solvents. The average particle diameter of as-prepared AuNPs was 36±10 nm for water/methanol system (methanol: 25 vol%), 56±17 nm for water/ethanol system (ethanol:35 vol%), and 24±7 nm for water/1-propanol system (1-propanol: 35 vol%). The present results indicate that the hydrophobicity of 1-propanol is higher, because the side chain of 1-propanol is longer than those in the other alcohols. Thus, it can be concluded that the dispersion of AuNPs is enhanced and their aggregation and growth are suppressed.

抄録全体を表示

Parkinson disease (PD) is a neurogenerative disease that is at increased risk of developing for people aged 60 or over. As a histopathological manifestation, α-synuclein (α-syn) composed of 140-amino acid residues is known to accumulate as amyloid aggregates in the brain, but the aggregation mechanism is not fully understood. In vitro experiments have shown that it takes usually several days to induce the fibrillation of α-syn in physiological buffer solutions. The protein molecules proceed in a prolonged nucleation reaction followed by elongation of the nuclei, in which the protein is in supersaturation beyond the solubility limit. Agitation like shaking and stirring with a rotator accelerates amyloid fibrillation, and strong ultrasonic irradiation more effectively promotes the process. At present, technological development is in progress for the early diagnosis in which amyloid nuclei in the spinal fluid obtained from PD patients are amplified under ultrasonic irradiation conditions. For the growth of amyloid nuclei by sonication, it is important to combine the most suitable conditions of sonication and solutions such as protein concentrations, pH, and salt concentrations. In this study, we investigated solution conditions that accelerate amyloid nuclei of α-syn under the fixed conditions of ultrasonic irradiation.

抄録全体を表示

Size-controlled polymer nanoparticles are useful materials in various applications. In this work, we have successfully synthesized polymer nanoparticles which reflect precisely the size of monomer droplets formed by tandem acoustic emulsification. This synthetic method involves sequential ultrasonic irradiation (20 kHz→500 kHz→1.6 MHz→2.4 MHz→5 MHz) for acoustic emulsification of a water-insoluble monomer in an aqueous medium without any surfactants, followed by emulsion polymerization in the obtained solution.
Among the nanoparticles, hollow particles are particularly attractive materials due to their unique structure. Therefore, we also tried to prepare polymer hollow particles to demonstrate a further application of tandem acoustic emulsification. In this process, the acoustic emulsification is used to produce fluorous solvent droplets which are templates for polymer capsule synthesis. TEM-EDS analysis revealed that the core of the obtained polymer capsules filled with a fluorous solvent. Furthermore, by heating treatment, the core solvent could be removed, and consequently size-controlled polymer hollow nanoparticles were obtained.

抄録全体を表示

In this study, the viscoelasticity equipment with ultrasound device and water bath was developed. For the ultrasound effect on cellulose hydrogels, the rheometer equipped with the ultrasonic system was tested. Cellulose hydrogel was prepared from cotton by phase inversion process. Cellulose hydrogel were exposed to 23kHz, 43kHz, 141kHz of the US with output power of 40W at 25℃ for 5min, and then US was stopped. By irradiating the 23kHz or 43kHz US storage moduli G’ decreased significantly. It was observed that the values of G’ and G” were returned to the original value after the US was stopped. This behavior was seen in the second and third cycles when the US repeated exposed. Under the US irradiation, there was tendency that the cross points of G’ and G “ (tan 1δ = 1 ) were shifted toward low strain range.

抄録全体を表示