研究者詳細 - 安田　啓司

論文 - 安田　啓司

分割表示 171 件中 1 - 20 件目／全件表示 >>

Behavior of sonochemical reaction in a small pipe 査読有り

64 巻 ( 3 ) 2025年3月

Size control of Au@Pt core-shell nanoparticles for enhanced catalytic activity using ultrafine bubbles and ultrasound 査読有り

64 巻 ( 3 ) 2025年3月

Synthesis of Au@Pd core-shell nanoparticles by ultrafine bubbles and ultrasound without capping and reducing agents 査読有り

53 巻 ( 7 ) 2024年7月

Dependence of reaction on vessel position, diameter, and liquid height in the sonochemical reactor with indirect irradiation 査読有り Open Access

Yasuda, K; Yamazaki, T; Asakura, Y

JAPANESE JOURNAL OF APPLIED PHYSICS 63 巻 ( 4 ) 2024年4月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

To investigate the sonochemical reaction performance caused by the indirect irradiation at 500 kHz, the glass vessel and a KI aqueous solution were used. Both the ultrasonic power and reaction rate had maximum values at every half wavelength of ultrasound. When the vessel position was adjusted to a larger absolute value of transducer impedance, the reaction rate became higher. The reaction rate and ultrasonic power increased as the vessel position moved closer to the transducer. The reaction rate first increased as the electric power applied to the transducer increased, reached a maximum value, and then decreased. This decrease phenomenon is called quenching of the sonochemical reaction. Before the quenching occurrs, the reaction rate per unit volume almost linearly increased with ultrasonic power density. The effects of the vessel diameter and liquid height on the relationship between the reaction rate per unit volume and the ultrasonic power density were small.

DOI： 10.35848/1347-4065/ad2d09

Open Access

Web of Science

Scopus

Evaluation of solvent property of air-water interface based on the fluorescence spectra of 1,2′-dinaphthylamine in the aqueous solution of ultrafine bubbles 査読有り Open Access

Kodama, K; Hattori, S; Yasuda, K; Saitoh, T

ANALYTICAL SCIENCES 40 巻 ( 2 ) 頁： 341 - 345 2024年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Analytical Sciences

Solvent property of air–water interface was evaluated based on the fluorescence spectra of 1,2′-dinaphthylamine in water containing ultrafine bubbles (average diameter: 103 nm, standard deviation: 38 nm). Among naphthylamine derivatives whose fluorescence spectra were responsive to microscopic hydrophobicity, 1,2′-dinaphthylamine (DN) was selected because its wavelength of the maximum emission (λmax) was significantly dependent on the concentration and microenvironment of the ultrafine bubble. The λmax value of DN in water was 486 nm, while it shifted to shorter wavelength (408 nm) in the presence of 1.09 × 109 mL−1 of ultrafine bubbles. The shift of λmax value indicates that DN adsorbs on the surfaces of ultrafine bubbles and exists in hydrophobic region rather than in bulk water. By comparing with the λmax values in different solvents, the surface of ultrafine bubble was found to have similar solvent property to ethyl ether or ethyl acetate that are widely used as extracting solvents for hydrophobic organic compounds. Graphical abstract: (Figure presented.)

DOI： 10.1007/s44211-023-00454-x

ウルトラファインバブルの特性と応用招待有り査読有り

安田啓司

表面と真空 66 巻 ( 11 ) 頁： 631 - 638 2023年11月

高効率ソノリアクタの開発招待有り査読有り

安田啓司, 朝倉義幸

日本音響学会誌 79 巻 ( 11 ) 頁： 569 - 575 2023年11月

超音波霧化とウルトラファインバブルによるアミノ酸の濃縮招待有り

安田啓司

超音波TECHNO 35 巻 ( 5 ) 頁： 50 - 53 2023年9月

Characteristics of Ultrafine Bubbles (Bulk Nanobubbles) and Their Application to Particle-Related Technology ? 招待有り Open Access

Yasuda, K

KONA POWDER AND PARTICLE JOURNAL 41 巻 ( 0 ) 頁： 183 - 196 2023年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益財団法人ホソカワ粉体工学振興財団

Ultrafine bubbles (bulk nanobubbles), small bubbles with a diameter of less than 1 μm, have attracted academic and industrial attention because of their numerous advantages, including their chemical-free nature and extraordinarily long lifetime. The long lifetime is related to the much higher Brownian motion velocity compared to buoyancy. The reason why ultrafine bubbles can endure under stable conditions is still unclear, even though their inside is highly pressured. They have several characteristics, such as pH-dependent surface charge and reduced friction. They are also closely related to ultrasound. Ultrafine bubbles are generated and removed by selecting the ultrasonic frequency. Reaction and separation using ultrasonic cavitation and atomization, respectively, are enhanced by ultrafine bubbles. They can produce hollow nanoparticles, enhance adsorption on activated carbon, and clean solid surfaces. This review discusses the fundamental and ultrasonic characteristics of ultrafine bubbles and their application in particle-related technology, encompassing fine particle synthesis, adsorption, desorption, extraction, cleaning, and prevention of fouling.

DOI： 10.14356/kona.2024004

液中プラズマ法によるナノグラフェン合成に及ぼす超音波の影響招待有り

安田啓司, 長谷川健太, 近藤博基, 堀勝

超音波TECHNO 34 巻 ( 5 ) 頁： 42 - 46 2022年10月

ウルトラファインバブルのソノケミストリーへの応用招待有り

Bulletin of the Japan Society of Sonochemistry 16 巻 ( 2 ) 頁： 26 - 34 2022年9月

ファインバブルの特徴招待有り

安田啓司

粉体技術 14 巻 ( 8 ) 頁： 597 - 601 2022年8月

Enrichment of amino acids from its aqueous solution by ultrasonic atomization and ultrafine bubbles 査読有り Open Access

Yasuda, K; Hamada, K; Asakura, Y

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( SG ) 頁： SG10321 - SG10325 2022年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

The enrichment characteristics of amino acids by ultrasonic atomization were investigated. Samples were aqueous solutions of L-phenylalanine and L-tyrosine. The ratio of amino acid concentration in the mist to that in the solution was defined as the enrichment factor. As the flow rate of carrier gas became higher, the collection mass of mist increased and the enrichment factor decreased. The enrichment factor depended on the solution pH. The enrichment factor increased with decreasing amino acid concentration in the solution and enhanced by the addition of ultrafine bubbles.

DOI： 10.35848/1347-4065/ac43e5

Web of Science

Scopus

ウルトラファインバブルによる超音波合成した金ナノ粒子の粒子径制御招待有り

安田啓司

超音波TECHNO 34 巻 ( 3 ) 頁： 83 - 87 2022年6月

Study on the efficiency of a transducer for sonochemistry by calorimetry 査読有り

Y. Asakura and K. Yasuda

Japanese Journal of Applied Physics 61 巻頁： GS1032 2022年5月

Curcumin-Loaded Liposome Preparation in Ultrasound Environment under Pressurized Carbon Dioxide 査読有り Open Access

Wahyudiono; He, JY; Hu, X; Machmudah, S; Yasuda, K; Takami, S; Kanda, H; Goto, M

FOODS 11 巻 ( 10 ) 頁： 1469 2022年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Foods

Curcumin-loaded liposomes were prepared using a supercritical carbon dioxide (SCCO2 )– ultrasound environment system. The experiments were performed at temperatures of 40–70◦C and pressures of 10–25 MPa in a batch system with ultrasonication for 60 min. Transmission electron microscopy (TEM) images revealed liposome products with spherical morphologies and diameters of <100 nm. Dynamic light scattering (DLS) analysis indicated that the curcumin-loaded liposome nanosuspension exhibited good stability. Changing the operating conditions influenced the amount of liposome-encapsulated curcumin; as the operating temperature or pressure increased, the diameter of the liposome products and the amount of liposome-encapsulated curcumin increased and decreased, respectively. Herein, we described an innovative and practical organic-solvent-free method for generating liposomes from phospholipids.

DOI： 10.3390/foods11101469

超音波照射によるウルトラファインバブルの発生と消滅招待有り

安田啓司, 朝倉義幸

混相流 36 巻 ( 1 ) 頁： 12 - 19 2022年3月

Frequency and power dependence of ultrasonic degassing 査読有り Open Access

Asakura, Y; Yasuda, K

ULTRASONICS SONOCHEMISTRY 82 巻頁： 105890 - 1058908 2022年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Ultrasonics Sonochemistry

We investigated the time variation of ultrasonic degassing for air-saturated water and degassed water with a sample volume of 100 mL at frequencies of 22, 43, 129, 209, 305, 400, 514, 1018, and 1960 kHz and ultrasonic power of 15 W. Ultrasonic degassing was evaluated by dissolved oxygen concentration. Ultrasonic degassing was also investigated at a frequency of 1018 kHz and ultrasonic powers of 5, 10, 15, and 20 W. The dissolved oxygen concentration varied with the ultrasonic irradiation time and became constant after prolonged ultrasonic irradiation. The constant dissolved oxygen concentration value depended on the frequency and ultrasonic power but not the initial dissolved oxygen concentration. The degassing rate at 101.3 kPa was higher in the frequency range of 200 kHz to 1 MHz. The frequency dependence of the degassing rate was almost the same as that of the sonochemical efficiency obtained by the potassium iodide (KI) method. Ultrasonic degassing in the frequency range of 22–1960 kHz was also investigated under reduced pressure of 5 kPa. Degassing was accelerated when ultrasonic irradiation was applied under reduced pressure. However, under a reduced pressure of 5 kPa, the lower the frequencies, the higher is the degassing rate. The sonochemical reaction rate was examined by the KI method for varying dissolved air concentrations before ultrasonic irradiation. Cavitation did not occur when the initial dissolved oxygen concentration was less than 2 mg·L−1. Therefore, the lower limit of ultrasonic degassing under 101.3 kPa equals 2 mg·L−1 dissolved oxygen concentration. A model equation for the time variation of dissolved oxygen concentration due to ultrasonic irradiation was developed, and the degassing mechanism was discussed.

DOI： 10.1016/j.ultsonch.2021.105890

Frequency and power dependence of the sonochemical reaction 査読有り Open Access

Asakura, Y; Yasuda, K

ULTRASONICS SONOCHEMISTRY 81 巻頁： 105858 - 1058587 2021年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Ultrasonics Sonochemistry

The dependence of the sonochemical reaction on ultrasonic intensity was studied over a wide frequency range of 22–1960 kHz and sample volume range of 25–200 mL. The effect of a stainless steel reflector set on the water surface was also considered. Experiments were carried out by direct ultrasonic irradiation of a sample in a vessel. The potassium iodide (KI) method was used to evaluate the sonochemical reaction in terms of efficiency and reaction rate, and calorimetry was used to determine ultrasonic power. A quenching phenomenon, where the reaction rate decreased despite an increasing ultrasonic power, was observed at all frequencies and sample volumes, which indicated the existence of a maximum reaction rate. The maximum reaction rate increased with the frequency, except at 1960 kHz, and with the sample volume. The ultrasonic power at which quenching occurred increased with the frequency and sample volume. Sudden quenching occurred without the reflector, whereas gradual quenching occurred with the reflector. Based on the results, ultrasonic power density (i.e., ultrasonic power divided by the sample volume) can be used to estimate the ultrasonic power at which quenching occurs for various sample volumes.

DOI： 10.1016/j.ultsonch.2021.105858

超音波によるウルトラファインバブルの生成・消滅と高純度な金ナノ粒子の合成招待有り

安田啓司

化学工業 72 巻 ( 7 ) 頁： 441 - 446 2021年7月

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