研究者詳細 - 石川　健治

論文 - 石川　健治

分割表示 417 件中 141 - 160 件目／全件表示 >>

Roles of Atomic Nitrogen/Hydrogen in GaN Film Growth by Chemically Assisted Sputtering with Dual Plasma Sources 査読有り Open Access

Tanide, A; Nakamura, S; Horikoshi, A; Takatsuji, S; Kimura, T; Kinose, K; Nadahara, S; Nishikawa, M; Ebe, A; Ishikawa, K; Oda, O; Hori, M

ACS OMEGA 5 巻 ( 41 ) 頁： 26776 - 26785 2020年10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：ACS Omega

The growth of sputtered GaN at low temperature is strongly desired to realize the dissemination of low-cost GaN high electron mobility transistor devices for next-generation communication technology. In this work, the roles of atomic nitrogen (N)/hydrogen (H) in GaN film growth on AlN/sapphire substrates by chemically assisted dual source sputtering are studied at a low growth temperature of 600 °C under a pressure of 2 Pa using vacuum ultraviolet absorption spectroscopy. The lateral growth was strongly enhanced with an appropriate H/N flux ratio of 1.9 at a GaN growth rate of ∼1 μm h-1. X-ray photoelectron spectroscopy measurements indicated that N removal from the grown GaN surface by atomic hydrogen promoted the migration of Ga. A smooth GaN surface was achieved at a suitable N/Ga supply ratio of 53 and a H/N ratio of 1.9 with the addition of 0.5% chlorine to the Ar sputtering gas.

DOI： 10.1021/acsomega.0c03865

Laser-induced-plasma-activated medium enables killing of HeLa cells 査読有り

Kurokawa Y., Takeda K., Ishikawa K., Tanaka H., Hori M.

Applied Physics Express 13 巻 ( 10 ) 2020年10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

Plasma-activated medium (PAM) is defined as a medium irradiated with non-thermal plasma; multiple in vitro and animal experiments have demonstrated that PAM exhibits anti-tumor effects against various cancers. PAM contains various reactive species that contribute to these anti-tumor effects. To increase the abundance of such reactive species, we used laser-generated plasma (LGP). We used a LGP consisting of 200 ns pulsed plasma with an electron density of approximately 7.0 × 10<sup>18</sup> cm<sup>−3</sup>, which is an extremely high electron density, exceeding those of other atmospheric pressure plasmas. We created a laser-generated-plasma-activated medium (LPAM), and treated HeLa cells with the LPAM in both the presence and absence of catalase. Both with and without catalase, the LPAM treatment yielded strong anti-cancer effects against HeLa cells. Surprisingly, we observed morphological differences between HeLa cells grown in LPAM prepared with and without catalase. These results suggested that LPAM induces the cell death through extracellular hydrogen peroxide-dependent and -independent processes.

DOI： 10.35848/1882-0786/abb68c

Adjusted multiple gases in the plasma flow induce differential antitumor potentials of plasma-activated solutions 査読有り

Nakamura, K; Yoshikawa, N; Yoshihara, M; Ikeda, Y; Higashida, A; Niwa, A; Jindo, T; Tanaka, H; Ishikawa, K; Mizuno, M; Toyokuni, S; Hori, M; Kikkawa, F; Kajiyama, H

PLASMA PROCESSES AND POLYMERS 17 巻 ( 10 ) 頁： 1900259 2020年10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：Plasma Processes and Polymers

We present a novel plasma system that can generate a plasma-activated medium by changing the proportion of reactive gases such as oxygen, nitrogen, and hydrogen in the plasma flow. The correlation between the biological activity of plasma-activated solutions prepared under multiple plasma gas-flow conditions was evaluated. Mixed nitrogen, in addition to oxygen, in the gas flow is most powerful for producing plasma-activated Ringer's lactate solution against antitumor effects on ovarian cancer cells as compared with oxygen or nitrogen alone. The antitumor effect of plasma-activated solutions is controllable by the modification of the proportion of reactive gases (especially nitrogen and oxygen gases) in the plasma flow. These results suggest that the plasma flow conditions may be one of the candidates for the specifications of the plasma-activated solutions to the therapeutic effect.

DOI： 10.1002/ppap.201900259

Small size gold nanoparticles enhance apoptosis-induced by cold atmospheric plasma via depletion of intracellular GSH and modification of oxidative stress 査読有り Open Access

Jawaid, P; Rehman, MU; Zhao, QL; Misawa, M; Ishikawa, K; Hori, M; Shimizu, T; Saitoh, J; Noguchi, K; Kondo, T

CELL DEATH DISCOVERY 6 巻 ( 1 ) 頁： 83 2020年9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：Cell Death Discovery

Gold nanoparticles (Au-NPs) have attracted attention as a promising sensitizer owing to their high atomic number (Z), and because they are considered fully multifunctional, they are preferred over other metal nanoparticles. Cold atmospheric plasma (CAP) has also recently gained attention, especially for cancer treatment, by inducing apoptosis through the formation of reactive oxygen species (ROS). In this study, the activity of different sized Au-NPs with helium-based CAP (He-CAP) was analyzed, and the underlying mechanism was investigated. Treating cells with only small Au-NPs (2 nm) significantly enhanced He-CAP-induced apoptosis. In comparison, 40 nm and 100 nm Au-NPs failed to enhance cell death. Mechanistically, the synergistic enhancement was due to 2 nm Au-NPs-induced decrease in intracellular glutathione, which led to the generation of intracellular ROS. He-CAP markedly induced ROS generation in an aqueous medium; however, treatment with He-CAP alone did not induce intracellular ROS formation. In contrast, the combined treatment significantly enhanced the intracellular formation of superoxide (O<inf>2</inf><sup>• −</sup>) and hydroxyl radical (<sup>•</sup>OH). These findings indicate the potential therapeutic use of Au-NPs in combination with CAP and further clarify the role of Au-NPs in He-CAP-aided therapies.

DOI： 10.1038/s41420-020-00314-x

酒米品種イネ栽培における低温プラズマ処理の品質への効果査読有り

水野寛子, 橋爪博司, 北野英己, 阿部明子, 湯浅元気, 堀勝, 東野里江, 榊原均, 松本省吾, 水野正明, 田中宏昌, 石川健治, 仁川進, 前島正義

応用物理学会学術講演会講演予稿集 2020.2 巻 ( 0 ) 頁： 1167 - 1167 2020年8月

Influence of temperature on etch rate of PECVD-SiN films with CF<sub>4</sub>/H<sub>2</sub> plasma 査読有り

Hsiao Shihnan, Nakane Kazuya, Ishikawa Kenji, Tsutsumi Takayoshi, Hori Masaru, Sekine Makoto

JSAP Annual Meetings Extended Abstracts 2020.2 巻 ( 0 ) 頁： 1195 - 1195 2020年8月

Numerical analysis of coaxial dielectric barrier helium discharges: three-stage mode transitions and internal bullet propagation 査読有り Open Access

Sato, Y; Ishikawa, K; Tsutsumi, T; Hori, M

APPLIED PHYSICS EXPRESS 13 巻 ( 8 ) 頁： 086001 2020年8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

He discharge in a coaxial dielectric barrier discharge (DBD) device develops in three stages: first, a Townsend-glow-type plasma spreads in the region between the electrodes; second, a plasma bullet (streamer type discharge) propagates axially and; third, the bullet transitions into a surface discharge at the dielectric surface. These mode transitions are quite different from planar type DBD, in which one discharge mode basically corresponds to one discharge pulse. From fluid-based numerical analysis, the bullet propagation is obeyed by trapping with strong electric fields induced by grounded electrode underneath the dielectric barrier and by surface charge accumulated on the dielectric surface.

DOI： 10.35848/1882-0786/aba3f2

Plasma Agriculture from Laboratory to Farm: A Review 査読有り Open Access

Attri, P; Ishikawa, K; Okumura, T; Koga, K; Shiratani, M

PROCESSES 8 巻 ( 8 ) 頁： 1002 2020年8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：Processes

In recent years, non-thermal plasma (NTP) application in agriculture is rapidly increasing. Many published articles and reviews in the literature are focus on the post-harvest use of plasma in agriculture. However, the pre-harvest application of plasma still in its early stage. Therefore, in this review, we covered the effect of NTP and plasma-treated water (PTW) on seed germination and growth enhancement. Further, we will discuss the change in biochemical analysis, e.g., the variation in phytohormones, phytochemicals, and antioxidant levels of seeds after treatment with NTP and PTW. Lastly, we will address the possibility of using plasma in the actual agriculture field and prospects of this technology.

DOI： 10.3390/pr8081002

Non-thermal plasma-activated lactate solution kills U251SP glioblastoma cells in an innate reductive manner with altered metabolism 査読有り

Ishikawa, K; Hosoi, Y; Tanaka, H; Jiang, L; Toyokuni, S; Nakamura, K; Kajiyama, H; Kikkawa, F; Mizuno, M; Hori, M

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS 688 巻頁： 108414 2020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：Archives of Biochemistry and Biophysics

Ringer's lactate solution irradiated by non-thermal plasma, comprised of radicals, electrons, and ions, is defined as plasma-activated lactate (PAL). PAL exhibited antitumor effects in glioblastoma U251SP cells, which we termed PAL-specific regulated cell death. In contrast to the oxidative stress condition typical of cells incubated in plasma-activated medium (PAM), U251SP cells treated with Ringer's lactate solution or PAL exhibited changes in intracellular metabolites that were reductive in the redox state, as measured by the ratio of oxidative/reductive glutathione concentrations. In the metabolomic profiles of PAL-treated cells, the generation of acetyl-CoA increased for lipid metabolism from alanine and asparagine. PAL thus induces regulated death of U251SP glioblastoma cells in more innate microenvironments than PAM.

DOI： 10.1016/j.abb.2020.108414

<i>In situ</i> surface analysis of an ion-energy-dependent chlorination layer on GaN during cyclic etching using Ar<SUP>+</SUP> ions and Cl radicals 査読有り

Hasegawa, M; Tsutsumi, T; Tanide, A; Nakamura, S; Kondo, H; Ishikawa, K; Sekine, M; Hori, M

JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A 38 巻 ( 4 ) 頁： 042602 2020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：Journal of Vacuum Science and Technology A Vacuum Surfaces and Films

Gallium nitride (GaN) semiconductor devices must be fabricated using plasma etching with precise control of the etching depths and minimal plasma-induced damage on the atomic scale. A cyclic process comprising etchant adsorption and product removal may be suitable for this purpose but an understanding of the associated etching surface reactions is required. The present work examined the formation of a chlorinated layer based on Cl radical adsorption on a GaN surface in conjunction with Ar ion irradiation. This research employed beam experiments and in situ x-ray photoelectron spectroscopy. The results show that N atoms are preferentially desorbed during exposure to Ar ions to produce Ga-rich layers at depths of 0.8 and 1.1 nm at an Ar ion dosage on the order of 1016 cm-2 and ion energies of 116.0 and 212.6 eV, respectively. Subsequent exposure of the irradiated Ga-rich layer to Cl radicals removes some Ga atoms and produces a chlorinated layer over the GaN surface. This chlorinated layer has a thickness on the order of 1 nm following Cl radical dosages on the order of 1019 cm-2. This study of plasma-treated surfaces is expected to assist in developing means of controlling the etching depth during the atomic layer etching of GaN via Ar ion bombardment.

DOI： 10.1116/6.0000124

Numerical simulations of stable, high-electron-density atmospheric pressure argon plasma under pin-to-plane electrode geometry: effects of applied voltage polarity 査読有り Open Access

Sato, Y; Ishikawa, K; Tsutsumi, T; Ui, A; Akita, M; Oka, S; Hori, M

JOURNAL OF PHYSICS D-APPLIED PHYSICS 53 巻 ( 26 ) 頁： 265204 2020年6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

When applying high-voltage direct current to a pin-to-plane electrode geometry with a distance of 2 mm under atmospheric pressure in argon gas, electrical breakdown forms primary then secondary streamers. The polarity of the applied voltage affects this streamer-propagating phenomenon. Properties such as propagation speed, streamer head size, and plasma generation are parameterized at nanosecond scales by computational simulations of a self-consistent, multi-species, multierature plasma fluid modeling approach. For positive polarity on the pin electrode, streamer-head propagation speeds up and streamer head size increases with increasing applied voltages. However, local electron density at the head decreases. For negative polarity, corona-like discharges form around the pin electrode under low applied voltages, and diffusive steamers form under high applied voltages. Secondary streamers re-propagate from the pin after primary streamer propagation, forming a plasma with a high electron density of 10<sup>21</sup> m<sup>-3</sup> for the positive polarity. We show that low-voltage operations with positive polarity are useful for stable high-electron-density discharges under atmospheric pressure argon.

DOI： 10.1088/1361-6463/ab7df0

In-plane modification of hexagonal boron nitride particles via plasma in solution 査読有り Open Access

Ito, T; Goto, T; Inoue, K; Ishikawa, K; Kondo, H; Hori, M; Shimizu, Y; Hakuta, Y; Terashima, K

APPLIED PHYSICS EXPRESS 13 巻 ( 6 ) 頁： 066001 2020年6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

In-plane modification of hexagonal boron nitride (hBN) is demonstrated via plasma in solution without acid/base addition. Electron spin resonance spectroscopy clearly reveals an increase in nitrogen vacancies in the hBN plane. This could be a simple route to functionalizing the two-dimensional surface of hBN. Simultaneously, hydroxylation occurs, accompanied by an increase in the zeta potential.

DOI： 10.35848/1882-0786/ab916c

Electron spin resonance as a tool to monitor the influence of novel processing technologies on food properties 査読有り国際共著 Open Access

Barba, FJ; Roohinejad, S; Ishikawa, K; Leong, SY; Bekhit, AEA; Saraiva, JA; Lebovka, N

TRENDS IN FOOD SCIENCE & TECHNOLOGY 100 巻頁： 77 - 87 2020年6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：Trends in Food Science and Technology

Background: Nowadays, electron spin resonance (ESR) is widely used as a powerful, non-destructive and very sensitive technique for the detection of free radicals in food systems. It can be applied for the direct identification of highly reactive oxygen species, organic and inorganic paramagnetic species and screening of food for potential toxicity. Its applications cover investigating food oxidative stability and properties of irradiated foods including fruits and vegetables, meats and fishes, spices, cereal grains, and oil seeds. Scope and approach: This review aims at providing specialists in food science and industry with the fundamentals of ESR spectroscopy, typical radicals present in foods and their sources, ESR modalities, and detailed account for the use of the technology for evaluation of the physicochemical and nutritional properties of foods. Examples illustrating ESR applications for the evaluation of the effects of innovative and emerging technologies (ionizing radiation, high pressures, pulsed electric fields, cold plasma and ultrasonication) are discussed. Key findings and conclusions: ESR can be used for the identification/quantification of free radicals in foods, for spin-label oximetry, estimation of free radical scavenging, food stability, and chelating activity, with particular interest for food processed using innovative technologies, with the main advantages of its high sensitivity, specificity, and low amounts of sample needed and nowadays many types of ESR instruments are commercially available. However, due to the different nature of foods, the development of novel ESR techniques and methods of analysis specially designed to study foods is of great interest in the future.

DOI： 10.1016/j.tifs.2020.03.032

Dry Process FOREWORD 査読有り

Shirafuji, T; Kinoshita, K; Akatsuka, H; Eriguchi, K; Ichikawa, T; Ichiki, T; Ishijima, T; Ishikawa, K; Karahashi, K; Kurihara, K; Sekine, M

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( SJ ) 2020年6月

Characterization of a microsecond pulsed non-equilibrium atmospheric pressure Ar plasma using laser scattering and optical emission spectroscopy 査読有り

Jia, FD; Wu, Y; Min, Q; Su, MG; Takeda, K; Ishikawa, K; Kondo, H; Sekine, M; Hori, M; Zhong, ZP

PLASMA SCIENCE & TECHNOLOGY 22 巻 ( 6 ) 頁： 065404 2020年6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：Plasma Science and Technology

A non-equilibrium atmospheric pressure argon (Ar) plasma excited by microsecond pulse is studied experimentally by laser scattering and optical emission spectroscopy (OES), and theoretically by collisional-radiative (CR) model. More specifically, the electron temperature and electron density of plasma are obtained directly by the laser Thomson scattering, the gas temperature is measured by laser Raman scattering, the optical emissions of excited Ar states of plasma are measured by OES. The laser scattering results show that the electron temperature is about 1 eV which is similar to that excited by 60 Hz AC power, but the gas temperature is as low as 300 K compared to about 700 K excited by 60 Hz AC power. It is shown that the microsecond pulsed power supply, rather than nanosecond ones, is short enough to reduce the gas temperature of atmospheric pressure plasma to near room temperature. The electron temperature and electron density are also obtained by CR model based on OES, and find that the intensities of the optical emission intensity lines of 727.41, 811.73, 841.08, 842.83, 852.44 and 912.86 nm of Ar can be used to characterize the behavior of electron density and electron temperature, it is very useful to quickly estimate the activity of the atmospheric pressure Ar plasma in many applications.

DOI： 10.1088/2058-6272/ab84e2

Electronic properties and primary dissociation channels of fluoromethane compounds 査読有り

Hayashi, T; Ishikawa, K; Sekine, M; Hori, M

JAPANESE JOURNAL OF APPLIED PHYSICS 59 巻 ( SJ ) 頁： SJJE02 2020年6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

We investigated fluoromethane compounds (CF<inf>4</inf>, CF<inf>3</inf>, CHF<inf>3</inf>, CH<inf>2</inf>F<inf>2</inf>, and CH<inf>3</inf>F) to examine their electronic properties and primary dissociation channels by using computational chemistry. For the electron attachment process, it was very important to represent the observed negative mass spectrum as a function of electron energy that calculation by the MP2 method for the negative ion and subsequent calculation by the EOMCCSD method were used to more accurately estimate the ground and the first excited states of the negative ion. In the evaluation of dissociation channels through the excitation process, the structure change of the excited fragment (from pyramidal to planar) was taken into account. Evaluation of Jahn-Teller distortion for the highly symmetrical CHF<inf>3</inf> and CH<inf>3</inf>F was also very important to estimate the fragmentation process through the excitation. The calculated results after these treatments gave satisfactory representation of the experimental values. Moreover some predictions of experimentally unknown values are proposed.

DOI： 10.35848/1347-4065/ab7e3f

Synthesis of isolated carbon nanowalls via high-voltage nanosecond pulses in conjunction with CH<sub>4</sub>/H<sub>2</sub> plasma enhanced chemical vapor deposition 査読有り

Ichikawa, T; Shimizu, N; Ishikawa, K; Hiramatsu, M; Hori, M

CARBON 161 巻頁： 403 - 412 2020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：Carbon

Carbon nanowalls (CNWs) are vertically standing, interconnecting flake- or wall-like collections of graphene sheets. In the present work, this material was synthesized by applying precisely controlled high-voltage nanosecond pulses to a substrate using an inductor energy storage circuit in a radical-injection plasma-enhanced chemical vapor deposition system, employing a CH<inf>4</inf>/H<inf>2</inf> plasma. The resulting interconnected networks had a low density of CNWs with large average wall-to-wall distances. During the application of short-period pulses, the entire substrate surface was uniformly activated, thus enhancing the adsorption of carbon precursors and preventing CNW nucleation. As a result, an amorphous carbon film covered the surface of the substrate and a low CNW density was obtained with average wall-to-wall distances greater than 700 nm. On the basis of these results, the growth mechanism of CNWs was modeled.

DOI： 10.1016/j.carbon.2020.01.064

Gas-phase and film analysis of hydrogenated amorphous carbon films: Effect of ion bombardment energy flux on sp<SUP>2</SUP> carbon structures 査読有り

Sugiura, H; Ohashi, Y; Ishikawa, K; Kondo, H; Kato, T; Kaneko, T; Takeda, K; Tsutsumi, T; Hayashi, T; Sekine, M; Hori, M

DIAMOND AND RELATED MATERIALS 104 巻 2020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：Diamond and Related Materials

Hydrogenated amorphous carbon (a-C:H) films comprise nanoclustering graphites (nc-G), fused aromatic rings (nR), and olefinic chain clusters (nC) of sp<sup>2</sup>-bonded carbons in an sp<sup>3</sup> matrix. In this study, the sp<sup>2</sup> composition of the nc-G, nR and nC in a-C:H films is found to be determined by the ion bombardment energy flux (Γ<inf>Ei</inf>), which can be estimated as the product of ion bombardment energy and ion flux onto the deposited surface, in plasma-enhanced chemical vapor deposition using a plasma mixture of H<inf>2</inf> and CH<inf>4</inf> gases with the H radical injection method. The sp<sup>2</sup> composition is analyzed using Raman spectroscopy and near-edge X-ray absorption structure spectroscopy. a-C:H becomes increasingly graphitized with increasing Γ<inf>Ei</inf>. The precise control of the sp<sup>2</sup> C structure composition can be achieved by controlling the very-high-frequency input power and radio frequency input bias power via the ion flux and ion bombardment energy.

DOI： 10.1016/j.diamond.2019.107651

In-Liquid Plasma Synthesis of Nanographene with a Mixture of Methanol and 1-Butanol 査読有り

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

CHEMNANOMAT 6 巻 ( 4 ) 頁： 604 - 609 2020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：Chemnanomat

Nanometer-size graphene sheets (nanographene) were synthesized by the in-liquid plasma method employing a mixture of alcohols. Pure methanol in-liquid plasma was found to not synthesize any nanographene. Pure ethanol synthesized nanographene with high crystallinity. Highly crystalline nanographene with a narrow full width-half maximum of the Raman scattering G-band (FWHM<inf>G</inf>) was obtained by mixing 1-butanol with methanol. This is due to the formation of carbon ring structures being inhibited by the addition of methanol. The ratio of added methanol determined the nanographene crystallinity and yield under a trade-off relationship, allowing the crystallinity and nanographene yield to be controlled by controlling the ratio. Gas chromatography-mass spectrometric analysis of by-products in the liquids’ supernatant showed that the crystallinity of the synthesized nanographene correlated with the ratio of carbon over oxygen of the alcohol precursors (C/O), i. e., the amount of hydroxyl groups in the liquids, and hence controlling the C/O ratio can be used to control the graphene crystallinity in the in-liquid plasma synthesis.

DOI： 10.1002/cnma.201900676

計算科学による新規エッチングガスの探索査読有り

林俊雄, 関根誠, 堀勝, 石川健治

応用物理学会学術講演会講演予稿集 2020.1 巻 ( 0 ) 頁： 1585 - 1585 2020年2月

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21