Masayoshi Takahashi

• Professor
• Professor at Tohoku University

The catalytic hydrogenation of nitrate was performed in solutions containing 20 mg/dm3\({\text{NO}}_{3}^{ - }\) using a Pd–Cu/Al2O3 catalyst (synthesized with a Cu/Pd ratio of 0.25) together with microbubbles (radii <50 μm) of 9.4–43.7 % H2 in N2. Significant enhancement of the hydrogenation rate was observed due to the application of the microbubb...

This study investigated the usefulness of oxygen nanobubble water (O2NBW) for wound repair by analyzing its effect on wound-healing process in human lung fibroblasts (WI-38 cells). The WI-38 cells were treated with 0%, 50%, and 100% O2NBW. The cell viability, reactive oxygen species (ROS) production, and wound healing following treatment were deter...

Bulk nanobubbles, measuring less than 200 nm in water, have shown their salient properties in promoting growth in various species of plants and orthodox seeds, and as potential drug-delivery carriers in medicine. Studies of recalcitrant seeds have reported markedly increased germination rates with gibberellin treatment; however, neither the mechani...

Microbubbles are very fine bubbles that shrink and collapse underwater within several minutes, leading to the generation of free radicals. Electron spin resonance spectroscopy (ESR) confirmed the generation of hydroxyl radicals under strongly acidic conditions. The drastic environmental change caused by the collapse of the microbubbles may trigger...

The effects of temperature and nanometer-sized bubbles (NBs) on a superior electric storage capacitor for anodically oxidized films of AlY10 amorphous alloys were determined at temperatures ranging from 275 to 298 K in 0.4 M H2SO4 solutions with NBs of ozone, oxygen, and carbon dioxide. The AAO specimen obtained by solution with carbon dioxide NBs...

Semiconductor cleaning is a very important process in integrated circuit manufacturing, and the removal of high dose ion implanted photoresist is a big challenge in semiconductor cleaning owing to their carbonized crust layer generated on and near the surface of the photoresist layer. Microbubbles are a promising candidate in single wafer spin clea...

We are now realizing fantastic properties of tiny bubbles; microbubble can contribute to wastewater treatment and semiconductor cleaning, and nanobubbles activate fishes and plants. Microbubbles are gas bubbles less than 50 micrometer in diameter and shrink underwater due to the rapid dissolution of the interior gas. And it has been demonstrated th...

We studied about an effect of temperature on degradation of polymers for photoresist using ozone microbubbles as an environmentally friendly cleaning technique. The dissolved ozone concentration of ozone microbubbles was decreased with the increasing temperature because the solubility of ozone gas was decreased and self-decomposition of ozone in wa...

We need to enhance the removing ability of microbubbles through the clear understanding of the functional mechanisms of microbubbles for the removal of photoresist layers. The purpose of the present study is to clarify the effect of microbubble on the surface of photoresist layers.

The existence of microbubbles in ozonized water has been shown to significantly enhance the photoresist removal rate due to an elevated dissolved ozone concentration and a direct effect of the microbubbles relating to the radical generation. Additionally, the ozone microbubble solution was able to effectively remove a high-dose ion-implanted photor...

A significant effect of microbubbles on degradation of novolak resin could not be confirmed. Microbubbles efficiently dissolved ozone in solution, enhancing dissolved ozone concentration. By using ozone microbubbles, removal rate of novolak resin was enhanced. We expect that the effect of polymer degradation by microbubbles would be made more obvio...

A remarkable feature of nanobubbles (–6 m in diameter) is their long lifetime in water. Supplying oxygen-nanobubbles (NBs) to continuously flooded paddy soil may retard the development of reductive conditions, thereby reducing the emission of methane (CH4), a potent greenhouse gas, and dissolution of arsenic, an environmental load. We tested this h...

The aims of the present study were to evaluate the bactericidal activity of a new antiseptic agent, ozone nano-bubble water (NBW3), against periodontopathogenic bacteria and to assess the cytotoxicity of NBW3 against human oral cells. The bactericidal activities of NBW3 against representative periodontopathogenic bacteria, Porphyromonas gingivalis...

A method for collapsing a microbubble includes applying stimulation to the microbubble during the gradual decrease of the its size. As a result, the microbubble floating in a solution that decreases in size due to the natural dissolution of a gas contained in the microbubble and disappears after a while, has the speed of its size decrease enhanced...

In this paper, we describe the use of ozone microbubbles in photoresist removal from silicon wafers. Ozonized water has attracted much attention as an environmental friendly cleaning method in semiconductor manufacturing. However, it would be desirable to enhance the oxidative ability of ozonized water for practical application. The existence of mi...

Free-radicals are generated by collapsing microbubbles in aqueous solutions; however, the concentration is too low to be of practical use. In this study, copper was found to enhance the generation of hydroxyl radicals from collapsing oxygen microbubbles under acidic conditions through electron-spin-resonance spectroscopy analysis. Moreover, the deg...

This study focuses on the application of microbubble collapse technique to the wastewater treatment. We have verified that collapsing air microbubbles lead to the decomposition of phenol, a common pollutant. A reduction in phenol of approximately 60% was observed during a 2-h test period when air was used as the microbubble source. We have also stu...

Hydroxyl radicals are strong oxidants in aqueous solution, reacting rapidly with a wide range of dissolved compounds. In contrast, ozone is a highly selective oxidant. Understanding the process by which ozone is transformed into hydroxyl radicals is important in the treatment of wastewater and drinking water. We use electron spin-resonance spectros...

Hydroxyl radicals are strong oxidants in aqueous solution, reacting rapidly with a wide range of dissolved compounds. In contrast, ozone is a highly selective oxidant. Understanding the process by which ozone is transformed into hydroxyl radicals is important in the treatment of wastewater and drinking water. We use electron spin-resonance spectros...

Free radicals are generated by the collapse of ultrasound-induced cavitation bubbles when they are forcefully compressed by dynamic stimuli. Radical generation occurs as a result of the extremely high temperatures induced by adiabatic compression during the violent collapse process. It is generally believed that extreme conditions are required for...

Free radicals are generated by the collapse of ultrasound-induced cavitation bubbles when they are forcefully compressed by dynamic stimuli. Radical generation occurs as a result of the extremely high temperatures induced by adiabatic compression during the violent collapse process. It is generally believed that extreme conditions are required for...

Microbubbles are very fine bubbles and appropriate for the investigation of the gas-water interface electrical charge, because of their long stagnation, due to slow buoyancy, in the electrophoresis cell observation area. This study investigated the zeta potential of microbubbles in aqueous solutions and revealed that the bubbles were negatively cha...

Microbubbles are very fine bubbles and appropriate for the investigation of the gas-water interface electrical charge, because of their long stagnation, due to slow buoyancy, in the electrophoresis cell observation area. This study investigated the ú potential of microbubbles in aqueous solutions and revealed that the bubbles were negatively charge...

Encapsulation of saline solution as an impurity in tetrahydrofuran clathrate hydrates grown in a stoichiometric solution with 3 wt % NaCl and the release of a saline solution during melting along with inclusion migration by hydrate recrystallization during annealing are studied using a directional growth apparatus in combination with a Mach-Zender...

The probing Fickian and non-Fickian diffusion of CO 2 in poly(methyl methacrylate) (PMMA) using in Situ Raman spectroscopy and microfocus X-ray computed tomography was discussed. It was shown that the information on sorption kinetics obtained from the Raman spectra augmented with velocity of the plasticized from obtained from X-ray CT scans can be...

Moire phase shift interferometry was used to monitor the concentration distribution of solute in the solution near the growing and melting tetrahydrofuran (THF) clathrate hydrates. During the growth of hydrate from off-stoichiometric solution, the THF concentration near the growth interface changed due to mass transport of guest molecules. During t...

Laser Raman spectroscopy, in conjunction with an optical high-pressure cell, was used to investigate the poly(methyl methacrylate)-carbon dioxide system. The Raman shifts associated with carbon dioxide molecules in the gas phase and those dissolved in the polymer were used to derive sorption kinetics of carbon dioxide and the carbon dioxide-induced...

The aim of this study is to clear the status of recreational scuba divers in Japan for promoting safety in recreational diving. A five year (from 1996 to 2001) questionnaire survey was performed of Japanese divers at the Osezaki area in Japan. The subjects of this survey included diving instructors as well as recreational divers. Based on the obtai...

Microbubble technology is now gathering much interest in industrial fields for its excellent gas-dissolving ability. This study was the first trial in using microbubbles in hydrate formation, and it has been demonstrated that a microbubble system is a promising method for hydrate formation for two reasons: (1) its excellent gas-dissolution ability...

Microbubble technology is now gathering much interest in industrial fields for its excellent gas-dissolving ability. This study was the first trial in using microbubbles in hydrate formation, and it has been demonstrated that a microbubble system is a promising method for hydrate formation for two reasons: (1) its excellent gas-dissolution ability...

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In situ interferometric observation of the process of CO2 dissolving into PMMA (polymethyl methacrylate) was carried out at high pressure and room temperature, in view of the interest to polymer foam technology. By analysing interferograms, the phase shift of a laser beam transmitted though the sample (the phase is related to the dissolved gas cont...

Water in fluid inclusions achieved a superheated condition by isochoric cooling method and the kinetic characteristic of bubble nucleation in water was investigated. The conventional study did not succeed in drawing a picture of bubble nucleation in water. The present study demonstrates that the homogeneous nucleation theory can describe the kineti...

Water in fluid inclusions achieved a superheated condition by isochoric cooling method and the kinetic characteristic of bubble nucleation in water was investigated. The conventional study did not succeed in drawing a picture of bubble nucleation in water. The present study demonstrates that the homogeneous nucleation theory can describe the kineti...

Environment-Elevated carbon dioxide (CO2) concentration is one of the most important physiological stressors with closed-circuit breathing-apparatus (CCBA). We determined the ventilatory response to CO2 during moderate exercise by measuring the relationship between (V) over dot(E) and PETCO2. Based on our findings, it is recommended that the permis...

Effects of breathing resistance while inhaling 3% carbon dioxide during steady-state exercise: Masayoshi TAKAHASHI, et al. National Institute for Resources and Environment—The purpose of the study was to determine the effects of breathing resistance on the human body while inhaling 3% carbon dioxide and to evaluate the appropriateness of self-conta...

The purpose of the study was to evaluate the influence of hyperoxia and hypercapnia on respiration and metabolism during a steady-state exercise. Thirteen healthy subjects were examined during bicycle-ergometer rides at approximately 50% VO2max under four different breathing gas conditions: 1) room air (control); 2) 40% oxygen; 3) 3% carbon dioxide...

The purpose of this study was to evaluate the safety of Self-Contained-Self-Rescuers (SCSRs) under a heavy work load. Three units, two chemical-oxygen (KO2) types and one compressed-oxygen type, were evaluated by a breathing and metabolic simulator and by a human subject. The metabolic rate in the simulator tests was equivalent to light work; the h...

We have conducted the health check of 3,554 compressed air workers and 1,821 divers, and also examined the incidence and severity of aseptic bone necrosis by using Roentgen pictures. We could classify 4,859 of 5,375 persons into four groups (A-D), based on our classification. We could also classify 4,205 of 5,375 persons that had had a bone X ray e...