研究者詳細 - 石川　健治

論文 - 石川　健治

分割表示 355 件中 221 - 240 件目／全件表示 >>

Bactericidal pathway of Escherichia coli in buffered saline treated with oxygen radicals 査読有り

Kobayashi, T; Iwata, N; Oh, JS; Hahizume, H; Ohta, T; Takeda, K; Ishikawa, K; Hori, M; Ito, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017年4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：Journal of Physics D: Applied Physics

Bactericidal effects of phosphate buffered saline treated with electrically neutral oxygen radicals on Escherichia coli (E. coli) are studied using an atmospheric pressure radical source and colony counting method. To clarify the bactericidal mechanism, the chemistry in phosphate buffers treated with oxygen radicals with and without saline has been quantitatively investigated using the well-established chemical reporters N,N-diethyl-p-phenylenediamine reagent and Amplex Red for residual chlorine (HClO and ClO-) and hydrogen peroxide (H2O2), respectively. From the results, we have found that the presence of chlorine in the solutions treated with oxygen radicals is the most important factor in the further chemical reactions to generate hypochlorous acid in E. coli death, and H2O2 is also linked to the bactericidal effect via an indirect chemical pathway.

DOI： 10.1088/1361-6463/aa61d7

Web of Science

Scopus

Effects of •OH and •NO radicals in the aqueous phase on H2O2 and NO2- generated in plasma-activated medium 査読有り

Kurake, N; Tanaka, H; Ishikawa, K; Takeda, K; Hashizume, H; Nakamura, K; Kajiyama, H; Kondo, T; Kikkawa, F; Mizuno, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017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：Journal of Physics D: Applied Physics

A plasma-activated medium (PAM), which means a cell-culture medium irradiated with cold atmospheric plasmas or non-equilibrium atmospheric pressure plasma (NEAPP), has shown strong antitumor effects on various kinds of cells such as gastric cancer cells, human lung adenocarcinoma cells, human breast cancer cells and so on. In order to clarify the mechanism, it is extremely important to investigate the behaviors of stable and unstable reactive oxygen nitrogen species in culture medium irradiated by NEAPP. The roles of hydroxyl radicals (•OH) and nitric oxide (•NO) were studied to understand the dominant synthetic pathways of H2O2 and in culture medium irradiated with NEAPP. In the PAM, •OH in the aqueous phase was generated predominantly by photo-dissociation. However, most of the H2O2 nor generated in the PAM did not originate from aqueous •OH and •NO. Pathways for the generation of H2O2 and are suggested based on the high concentrations of intermediates generated at the gas/aqueous-phase interface following NEAPP irradiation. On the basis of these results, the reaction model of chemical species in the culture medium is proposed.

DOI： 10.1088/1361-6463/aa5f1d

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Spatial profiles of interelectrode electron density in direct current superposed dual-frequency capacitively coupled plasmas 査読有り

Ohya, Y; Ishikawa, K; Komuro, T; Yamaguchi, T; Takeda, K; Kondo, H; Sekine, M; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 50 巻 ( 15 ) 2017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：Journal of Physics D: Applied Physics

We present experimentally determined spatial profiles of the interelectrode electron density (n e) in dual-frequency capacitively coupled plasmas in which the negative direct current (dc) bias voltage (V dc) is superposed; in the experiment, 13 MHz (P low) was applied to the lower electrode and 60 MHz (P high) to the upper electrode. The bulk n e increased substantially with increases in the external power, P high, P low, and with increases in V dc. When P low was insufficient, the bulk n e decreased as the V dc bias increased. The bulk n e increased due to its dependence on V dc, especially for |V dc| > 500 V. This may correspond to the sheath voltages (V s) of the lower electrode. The n e values in front of the upper electrode were coupled with the V dc: the V dc dependence first decreased and then increased. The dc currents (I dc) of the upper electrode were collected when a large P low was applied. The value of I dc at the threshold value of V dc ≈ V s (e.g. -500 V) increased with an increase in n e. When |V dc| exceeded the threshold, the spatial n e profile and the I dc dependence were changed relative to the electrical characteristics of the dc superposition; this led to a change in the location of the maximum n e, the width of the area of n e depletion in front of the electrodes, and a transition in the electron heating modes.

DOI： 10.1088/1361-6463/aa60f7

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Scopus

酸素ラジカル照射された馬肉水抽出液のESR測定査読有り

北田悠人, 林利哉, 石川健治, 堀勝, 伊藤昌文

応用物理学会学術講演会講演予稿集 2017.1 巻 ( 0 ) 頁： 1802 - 1802 2017年3月

マルチプレックスCARSによるプラズマと細胞の相互作用の観察査読有り

古田凌, 石川健治, 橋爪博司, 田中宏昌, 竹田圭吾, 太田貴之, 近藤博基, 伊藤昌文, 関根誠, 堀勝

応用物理学会学術講演会講演予稿集 2017.1 巻 ( 0 ) 頁： 1801 - 1801 2017年3月

Behavior of absolute densities of atomic oxygen in the gas phase near an object surface in an AC-excited atmospheric pressure He plasma jet 査読有り

Takeda, K; Kumakura, T; Ishikawa, K; Tanaka, H; Sekine, M; Hori, M

APPLIED PHYSICS EXPRESS 10 巻 ( 3 ) 2017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：Applied Physics Express

The quantitative behavior of atomic oxygen in the gas phase near a Cu wire surface in an AC-excited atmospheric pressure He plasma jet in open air was measured using time-resolved vacuum ultraviolet absorption spectroscopy. The atomic oxygen density had a peak at a distance between the plasma source and the Cu wire, and the peak position moved away from the source with an increase in the gas flow rate. The behavior is considered to be dependent on the plasma density and the influence of ambient air. The results are important for supplying atomic oxygen to samples for plasma jet treatment in the atmosphere.

DOI： 10.7567/APEX.10.036201

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Fabrication of superconductor-ferromagnet-insulator-superconductor Josephson junctions with critical current uniformity applicable to integrated circuits

Ito Hiroshi, Taniguchi Soya, Ishikawa Kouta, Akaike Hiroyuki, Fujimaki Akira

APPLIED PHYSICS EXPRESS 10 巻 ( 3 ) 2017年3月

Characteristics of optical emissions of arc plasma processing for high-rate synthesis of highly crystalline single-walled carbon nanotubes 査読有り

Ando, A; Takeda, K; Ohta, T; Ito, M; Hiramatsu, M; Ishikawa, K; Kondo, H; Sekine, M; Suzuki, T; Inoue, S; Ando, Y; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 3 ) 2017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：Japanese Journal of Applied Physics

Single-walled carbon nanotubes (SWNTs) were synthesized with a high growth rate using an arc plasma employing carbon electrodes with a Ni-Y mixture catalyst. However, the mechanism of growth of highly crystalline SWNTs has not been clarified. Reactions between carbon and catalyst are considered to be one of the crucial factors in SWNT growth. Optical emission spectroscopy (OES) provides the information about the species in the plasma. C2, Ni, and Y emissions in the arc plasma at different currents were measured to investigate the relationship between active species in the arc plasma and the SWNTsynthesis. On the basis of OES results, it was found that the balance between catalytic metal atoms and C2 radical emissions indicated the crystallinity ratio of SWNTs in thin graphitic or amorphous carbon layers. These results are useful for controlling the growth of SWNTs employing arc plasmas.

DOI： 10.7567/JJAP.56.035101

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Scopus

Investigation of effects of ion energies on both plasma-induced damage and surface morphologies and optimization of high-temperature Cl2 plasma etching of GaN 査読有り

Liu, ZC; Pan, JL; Asano, A; Ishikawa, K; Takeda, K; Kondo, H; Oda, O; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 2 ) 2017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：Japanese Journal of Applied Physics

The minimization of plasma-induced damage (PID) in plasma etching is important for the precise and smooth removal of a depth of approximately 7 nm of GaN films to fabricate gate-recess GaN-based normally-off power electronic devices. We have systematically studied the photoluminescence (PL) properties and surface morphologies of GaN films exposed to Cl2 plasma at 400°C, focusing on their dependences on etch time and ion energy. It is noticeable that PL degradation saturated at etch times of more than 2 min, while surface roughness increased continuously with etch time. Variations of surface roughness with bias voltage were negligible. PID was successfully suppressed by reducing bias voltage, leading to the decrease in incident ion energy on the surface, and thus the near-band-edge emission (NBE) intensity as a PL property was increased to 98.8% of the initial value.

DOI： 10.7567/JJAP.56.026502

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Scopus

Absolute density of precursor SiH3 radicals and H atoms in H2-diluted SiH4 gas plasma for deposition of microcrystalline silicon films 査読有り

Abe, Y; Ishikawa, K; Takeda, K; Tsutsumi, T; Fukushima, A; Kondo, H; Sekine, M; Hori, M

APPLIED PHYSICS LETTERS 110 巻 ( 4 ) 2017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：Applied Physics Letters

Microcrystalline hydrogenated silicon films were produced at a high deposition rate of about 2 nm/s by using a capacitively coupled plasma under a practical pressure of around 1 kPa. The SiH4 source gas was almost fully dissociated when highly diluted with H2 gas, and the dominant species in the gas phase were found to be SiH3 radicals, which are film-growth precursors, and H atoms. The absolute density of these species was measured as the partial pressure of SiH4 gas was varied. With the increasing SiH4 gas flow rate, the SiH3 radical density, which was on the order of 1012 cm-3, increased linearly, while the H-atom density remained constant at about 1012 cm-3. The film growth mechanism was described in terms of precursors, based on the measured flux of SiH3 radicals and H atoms, and the relative fraction of higher-order radicals.

DOI： 10.1063/1.4974821

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Thermal Cyclic Atomic-Level Etching of Nitride Films: A Novel Way for Atomic-Scale Nanofabrication 査読有り

Shinoda, K; Miyoshi, N; Kobayashi, H; Kurihara, M; Izawa, M; Ishikawa, K; Hori, M

ATOMIC LAYER DEPOSITION APPLICATIONS 13 80 巻 ( 3 ) 頁： 3 - 14 2017年

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

A highly selective, rapid thermal-cyclic atomic-level etching (ALE) process for SiNx films has been developed. The first step of this process is exposing SiNx to hydrofluorocarbon plasma to form an (NH4)2SiF6 layer on the SiNx surface. The second step is rapid thermal annealing with infrared (IR) irradiation to decompose and sublimate the (NH4)2SiF6 layer. Etching of SiNx was observed after the (NH4)2SiF6 layer was removed by thermal annealing. Cyclic etching tests were carried out by repeated plasma exposure and IR irradiation. It was found that the cyclic process is self-limiting because etching depth depends only on the cycle number and not on the plasma exposure time. A high selectivity over SiC2 and poly Si was confirmed. This paper reviews the novel isotropic ALE for nitride films focusing on the surface reaction mechanism investigated by x-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). Isotropic ALE of TiN was also demonstrated using the same approach.

DOI： 10.1149/08003.0003ecst

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Scopus

TIME EVOLUTION OF REACTIVE OXYGEN NITROGEN SPECIES IN PLASMA-ACTIVATED ESSENTIAL MEDIA AND WATER 査読有り

Brubaker, T; Ishikawa, K; Takeda, K; Hashizume, H; Tanaka, H; Kondo, H; Sekine, M; Hori, M

2017 IEEE INTERNATIONAL CONFERENCE ON PLASMA SCIENCE (ICOPS) 頁： . 2017年

Thermally enhanced formation of photon-induced damage on GaN films in Cl<inf>2</inf> plasma 査読有り

Liu Z., Asano A., Imamura M., Ishikawa K., Takeda K., Kondo H., Oda O., Sekine M., Hori M.

Japanese Journal of Applied Physics 56 巻 ( 9 ) 2017年

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

Deep ultraviolet (UV) photons emitted from Cl2 plasmas become a critical cause of degradation in both photoluminescence (PL) properties and surface stoichiometry as a result of plasma-induced damage on GaN films in Cl2 plasma etching at high temperatures. The damages were formed thermally by photon-irradiations of plasma UV emissions with wavelengths of >258-306 nm from Cl2 plasma at temperatures greater than 500 °C. The damage were observed with a depth of approximately 3.2 nm. The PL property degraded by the UV emission-induced damage at an early period of plasma etching and reached a constant value.

DOI： 10.7567/JJAP.56.096501

Scopus

Nationwide epidemiological survey of idiopathic sudden sensorineural hearing loss in Japan. 査読有り

Kitoh R, Nishio SY, Ogawa K, Kanzaki S, Hato N, Sone M, Fukuda S, Hara A, Ikezono T, Ishikawa K, Iwasaki S, Kaga K, Kakehata S, Matsubara A, Matsunaga T, Murata T, Naito Y, Nakagawa T, Nishizaki K, Noguchi Y, Sano H, Sato H, Suzuki M, Shojaku H, Takahashi H, Takeda H, Tono T, Yamashita H, Yamasoba T, Usami SI

Acta oto-laryngologica 137 巻 ( sup565 ) 頁： S8 - S16 2017年

Formation of a SiOF reaction intermixing layer on SiO2 etching using C4F6/O2/Ar plasmas 査読有り

Yoshinobu Ohya, Maju Tomura, Kenji Ishikawa, Makoto Sekine, and Masaru Hori

Journal of Vacuum Science and Technology A Letters 34 巻 ( 4 ) 頁： 040602 2016年5月

Effects of nitrogen on apoptosis and changes in gene expression in human lymphoma U937 cells exposed to argon-cold atmospheric pressure plasma 査読有り

Yoshiaki Tabuchi, Hidefumi Uchiyama, Qing-li Zhao, Tatsuya Yunoki, Qabor Andocs, Nobuyuki Nojima, Keigo Takeda, Kenji Ishikawa, Masaru Hori and Takashi Kondo

International Journal of Molecular Medicine 37 巻頁： 1706-1714 2016年5月

Red Blood Cell Coagulation Induced by Low-temperature Plasma Treatment 査読有り

Kenji Miyamoto, Sanae Ikehara, Hikaru Takei, Yoshihiro Akimoto, Hajime Sakakita, Kenji Ishikawa, Masashi Ueda, Jun-ichiro Ikeda, Masahiro Yamagishi, Jaeho Kim, Takashi Yamaguchi, Hayao Nakanishi, Nobuyuki Shimizu, Masaru Hori, and Yuzuru Ikehara

Archives of Biochemistry and Biophysics 2016年4月

Hierarchical regrowth of flowerlike nanographene sheets on oxygen-plasma-treated carbon nanowalls

Hironao Shimoeda, Hiroki Kondo, Kenji Ishikawa, Mineo Hiramatsu, Makoto Sekine, and Masaru Hori

Appl. Phys. Express 7 巻頁： 046201 2016年3月

Effects of Radical Species on Structural and Electronic Properties of Amorphous Carbon Films Deposited by Radical-injection Plasma-enhanced Chemical Vapor Deposition 査読有り

Lingyun Jia, Hirotsugu Sugiura, Hiroki Kondo, Keigo Takeda, Kenji Ishikawa, Osamu Oda, Makoto Sekine, Mineo Hiramatsu, Masaru Hori

Plasma Process Polym. 2016年2月

Cell survival of glioblastoma grown in medium containing hydrogen peroxide and/or nitrite, or in plasma-activated medium 査読有り

Naoyuki Kurake, Hiromasa Tanaka, Kenji Ishikawa, Takashi Kondo, Keigo Takeda, Hiroki Kondo, Makoto Sekine, Kae Nakamura, Hiroaki Kajiyama, Fumitaka Kikkawa, Masaaki Mizuno, Masaru Hori

Archives of Biochemistry and Biophysics 2016年1月

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