Showing papers by "Hiroki Kondo published in 2013"

Effect of Indirect Nonequilibrium Atmospheric Pressure Plasma on Anti-Proliferative Activity against Chronic Chemo-Resistant Ovarian Cancer Cells In Vitro and In Vivo

Abstract: Purpose Nonequilibrium atmospheric pressure plasma (NEAPP) therapy has recently been focused on as a novel medical practice. Using cells with acquired paclitaxel/cisplatin resistance, we elucidated effects of indirect NEAPP-activated medium (NEAPP-AM) exposure on cell viability and tumor growth in vitro and in vivo. Methods Using chronic paclitaxel/cisplatin-resistant ovarian cancer cells, we applied indirect NEAPP-exposed medium to cells and xenografted tumors in a mouse model. Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in the above-mentioned EOC cells. Results We assessed the viability of NOS2 and NOS3 cells exposed to NEAPP-AM, which was prepared beforehand by irradiation with NEAPP for the indicated time. In NOS2 cells, viability decreased by approximately 30% after NEAPP-AM 120-sec treatment (P<0.01). The growth-inhibitory effects of NEAPP-AM were completely inhibited by N-acetyl cysteine treatment, while L-buthionine-[S, R]-sulfoximine, an inhibitor of the ROS scavenger used with NEAPP-AM, decreased cell viability by 85% after NEAPP-AM 60-sec treatment(P<0.05) and by 52% after 120 sec, compared to the control (P<0.01). In the murine subcutaneous tumor-formation model, NEAPP-AM injection resulted in an average inhibition of the NOS2 cell-inoculated tumor by 66% (P<0.05) and NOS2TR cell-inoculated tumor by 52% (P<0.05), as compared with the control. Conclusion We demonstrated that plasma-activated medium also had an anti-tumor effect on chemo-resistant cells in vitro and in vivo. Indirect plasma therapy is a promising treatment option for EOC and may contribute to a better patient prognosis in the future.

Aromatic C–H coupling with hindered arylboronic acids by Pd/Fe dual catalysts

Abstract: An aerobic oxidative coupling of arenes/alkenes with arylboronic acids (C–H/C–B coupling) using catalytic Pd(II)–sulfoxide–oxazoline (sox) ligand and iron–phthalocyanine (FePc) has been developed. This dual catalyst system enables the synthesis of sterically hindered heterobiaryls and styrene derivatives under air without stoichiometric co-oxidants. Additionally, this chemistry demonstrated an advance toward an enantioselective biaryl coupling through C–H functionalization.

Surface Chemical Modification of Carbon Nanowalls for Wide‐Range Control of Surface Wettability

Abstract: Carbon nanowalls (CNWs) are self-assembled, free-standing, few-layered graphenenano-structures with large surface area, and thin graphene edges. For their application to nanobiotechnology, the effects of chemisorbed species on surface wettability were investigated. The surfaces of as-grown CNWs obtained using CH4/H2 mixture were hydrophilic. After Ar atmospheric pressure plasma treatments for up to 30 s, the contact angles of water droplets on the CNWs decreased from 51° to 5°, owing to a result of oxidation only at edges and surface defects. They increased up to 147° by CF4 plasma treatment at low pressure. The wide-range control of surface wettability of CNWs was realized by post-growth plasma treatments. We also demonstrated detection of bovine serum albumin using surface-modified CNWs as electrodes.

Nucleation Control of Carbon Nanowalls Using Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition

Abstract: Carbon nanowalls (CNWs), a self-organized network of vertically standing few-layer graphenes, were synthesized by inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD) employing methane and argon mixtures. Significant interest exists in clarifying the nucleation mechanism of CNWs and controlling their nucleation. We have investigated the early growth stage of CNWs on the catalyst-free substrate and the titanium (Ti)-nanoparticle-catalyzed substrate. In the case of catalyst-free growth of CNWs, there was an induction period of 1–5 min before the onset of vertical nanographene growth and an interface layer exists between the vertical nanographenes and the surface of Si and SiO2 substrates. Meanwhile, in the case of the growth on the Ti nanoparticle-coated SiO2 substrates, the nanographenes were directly nucleated from the Ti nanoparticles without forming a base layer within 30 s, while no nucleation was observed on the SiO2 surface at this period. These results suggest the possibility of area-selective growth of CNWs by controlling the substrate biasing to suppress the nucleation selectively from the catalyst-free surface.

A High-Temperature Nitrogen Plasma Etching for Preserving Smooth and Stoichiometric GaN Surface

Abstract: We report the damageless surface morphology of gallium nitride (GaN) films during argon and nitrogen plasma etching at elevated temperatures up to 600 °C. For Ar plasma bombardment at high substrate temperatures of around 600 °C, Ar+ ion bombardment dissociates Ga–N bonds by the preferential removal of nitrogen, which promotes roughness of the GaN surface by the aggregation of gallium atoms. For the N2 plasma one, the N/Ga remains stoichiometric with higher values above 0.69, and the surface is not significantly roughened, even at 600 °C. Therefore, the aggregation of metallic Ga induces surface roughening during ion-enhanced etching of GaN at elevated substrate temperatures.

Fabrication of Carbon Nanowalls on Carbon Fiber Paper for Fuel Cell Application

Abstract: Carbon nanowalls (CNWs) can be described as self-assembled, vertically standing, few-layered graphene sheet nanostructures. In order to demonstrate the usefulness of CNWs in fuel cell application, CNWs were directly grown on carbon fiber paper (CFP) using the inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD) method. Subsequently, highly dispersed platinum (Pt) nanoparticles were formed on the surface of CNWs using metal–organic chemical fluid deposition (MOCFD) employing a supercritical fluid (SCF). Moreover, a single proton exchange membrane (PEM) fuel cell unit using a Pt-supported CNW/CFP electrode was constructed, and its voltage–current characteristics were measured. This configuration ensures that all the supported Pt nanoparticles are in electrical contact with the external electrical circuit. Such a design would improve Pt utilization and potentially decrease Pt usage. Pt-supported CNWs grown on CFP will be well suited to the application in electrodes of fuel cells.

Highly Selective Etching of SiO2 over Si3N4 and Si in Capacitively Coupled Plasma Employing C5HF7 Gas

Abstract: In a dual-frequency-excited parallel plate capacitively coupled plasma employing a heptafluoro-cyclo-pentene (C5HF7) gas with addition of O2 and dilution in Ar gas, highly selective etching of SiO2 at selectivities of 40 against Si3N4 and 57 against polycrystalline Si was realized. Gas phase fluorocarbon species containing H atoms such as CxHFy (x>2) played key roles in the selective deposition of thick hydrofluorocarbon films that covered the Si3N4 and polycrystalline silicon (poly-Si) surfaces and in the selective etching of SiO2 over the photoresist, SiN, and Si.

Wavelength Dependence of Photon-Induced Interface Defects in Hydrogenated Silicon Nitride/Si Structure during Plasma Etching Processes

Abstract: The wavelength dependence of SiNx:H/Si interface defect generation caused by vacuum ultraviolet (VUV)/UV radiation from plasma etching processes was investigated. VUV radiation (λ 400 nm) had no influence on damage generation on the SiNx:H/Si structure, since the visible radiation was transmitted through upper SiNx:H film and underlying interface layer. The results revealed that UV radiation transmitted through the upper dielectrics can cause the electrical characteristics of underlying metal–oxide–semiconductor (MOS) devices to fluctuate.

Rapid measurement of substrate temperatures by frequency-domain low-coherence interferometry

Abstract: Rapid high-precision temperature monitoring systems for silicon wafers applicable even during plasma processing have been developed using frequency-domain low-coherence interferometry without a reference mirror. It was found to have a precision of 0.04 °C, a response time of 1 ms, and a large tolerance to mechanical vibrations and fiber vending when monitoring the temperature of commercial Si wafers. The performance is a substantial improvement over the previous precision of 0.11 °C measured in a few seconds using a time-domain method. It is, therefore, a powerful real-time technique to monitor rapidly varying wafer temperatures with high precision.

Low-Temperature Single-Walled Carbon Nanotube Growth from Pt Catalyst Using Alcohol Gas Source Method in High Vacuum

Abstract: The growth of single-walled carbon nanotubes (SWCNTs) was carried out on SiO2/Si substrates with Pt catalysts at 400, 450, and 700 °C using an alcohol gas source method in a high vacuum, and the grown SWCNTs were characterized by Raman spectroscopy. By optimizing the ethanol pressure, we could grow SWCNTs even at 400 and 450 °C. By reducing the growth temperature, both the diameter and diameter distribution of the SWCNTs were markedly decreased, and the diameters for most of the SNWTs grown at 400 °C were estimated to be below 1 nm from the Raman results. Transmission electron microscopy (TEM) observation showed that the reduction in SWCNT diameter was caused by the decrease in catalyst size with decreasing temperature.

Impact of hydrogen radical-injection plasma on fabrication of microcrystalline silicon thin film for solar cells

Abstract: A plasma-enhanced chemical deposition system with hydrogen radical-injection (RI) is proposed for the fabrication of hydrogenated microcrystalline silicon (μc-Si:H) thin films. The plasma parameters and resultant growth characteristics obtained with the RI-capacitively coupled plasma (RI-CCP) system excited with 60 MHz power were compared with those obtained using a conventional CCP (C-CCP) system. The absolute density of hydrogen (H) radicals was measured by vacuum ultraviolet laser absorption spectroscopy (VUVLAS) to evaluate the effect of RI for controlling the H radical density. A higher density of H radicals was achieved with RI-CCP than with C-CCP by H RI. The crystallinity factor, preferential orientation, defect density, microstructure, and post-deposition oxidation of Si thin films deposited using C-CCP and RI-CCP were investigated. Crystallinity factor of 0.6 was realized with high deposition rate of about 2 nm/s even under a low plasma density using RI-CCP. The defect density of μc-Si:H thin films prepared using RI-CCP was lower than that in thin films prepared using C-CCP. In addition, post-deposition oxidation of the films with RI-CCP was lower than that with C-CCP. The high performance of RI-CCP for the fabrication of μc-Si:H thin films for solar cell devices is also demonstrated.

Fabrication of Graphene-Based Films Using Microwave-Plasma-Enhanced Chemical Vapor Deposition

Abstract: Microwave plasma is one of the high-density plasmas and has been extensively used for the growth of diamond and aligned carbon nanotubes for more than a decade. However, the conventional microwave plasma of the cylindrical resonant cavity type is not suitable for the synthesis of graphene. The plasma ball produced in the resonant cavity provides a number of important species as well as ions, while deposits are damaged by the excess ion bombardment since the substrate is exposed to the plasma ball. To simply control the position of the plasma ball and reduce the ion bombardment on the substrate surface, a grounded molybdenum mesh was installed over the substrate plate to realize a remote plasma configuration. As a result, the distance between the plasma ball and the copper substrate was increased, and few-layer graphene-based films were successfully synthesized in 1 min on copper substrates placed on the entire region of a substrate holder 10 cm in diameter by using conventional microwave-plasma enhanced chemical vapor deposition.

Atomic Oxygen Etching from the Top Edges of Carbon Nanowalls

Abstract: Carbon nanowalls (CNWs) consist of walls of thin graphite with thicknesses of a few tens of nanometers that stand vertically on a substrate. For modification of their structure after growth, we developed a method utilizing etching with oxygen atoms generated by an inductively coupled oxygen plasma. We found that oxygen atoms etched CNWs selectively from the top edges without etching reaction of the wall surface as the graphitic planes. This can provide a method for realizing carbon nanoelectronics by selective modification of the edges without oxidation of the graphene planes.

Supercritical Fluid Deposition of High-Density Nanoparticles of Photocatalytic TiO2 on Carbon Nanowalls

Abstract: Nanoparticles of the anatase phase of TiO2 (2.7±0.7 nm) with a high density of 1012 cm-2 were supported on the entire surface of carbon nanowalls (CNWs) by employing metal organic chemical fluid deposition in supercritical carbon dioxide at a substrate temperature of 180 °C. For decomposing methylene blue under ultraviolet irradiation, a high photocatalytic decomposition rate of 6 mg/h was obtained for 1 mg of TiO2 supported on CNWs.

Surface roughness development on ArF-photoresist studied by beam-irradiation of CF 4 plasma

Abstract: We report an observed relationship between chemical modifications and physical morphological roughness on a photoresist for ArF excimer laser photolithography in fluorocarbon plasma beam irradiation. At the very beginning period, three stages of characteristics of chemical changes occurred upon surface roughening or wrinkling of the photoresist; (1) a rapid reduction of C = O bonds, (2) gradual formation of a fluorocarbon layer, and graphitic (sp2-C) or amorphous (sp3-C) carbon layer; (3) as elapsed incubation phase, i.e. lag, where reached a steady state of chemical changes for fluorocarbon ion irradiation on the surface; finally morphological changes initiated. Those processes evolved within dose of 6 × 1015 cm−2 for ion energy of a few hundred eV.

Vehicle control system and vehicle control method

Abstract: A vehicle control system and method is applied to a vehicle including: a continuously variable transmission for changing a speed ratio continuously that is disposed between an input shaft and an output shaft; a geared transmission that is disposed parallel to the continuously variable transmission, and that is adapted to establish a speed ratio that cannot be established by the continuously variable transmission; and a friction clutch that is brought into engagement to switch a torque transmission route from a route including the geared transmission to a route including the continuously variable transmission. The vehicle control system is configured to start a speed change operation of the continuously variable transmission before a commencement of clutch-to-clutch shifting between the friction clutches when switching the torque transmission route from the route including the geared transmission to the route including the continuously variable transmission.

Control device for vehicle transmission

Abstract: A control device for a vehicle transmission having the following provided in parallel between an input shaft to which torque is inputted from a drive-power source of a vehicle and an output shaft for outputting torque to an output member: a first transmission path equipped with a first shifting mechanism capable of continuously changing a gear ratio, and a second transmission path equipped with a second shifting mechanism in which the set gear ratio is different than that of the first shifting mechanism. Furthermore, power is transmitted between the input shaft and the output shaft via the first transmission path or the second transmission path. Herein, the control device for the vehicle transmission is equipped with: an execution means for executing a switching shift for switching the path for transmitting power between the first transmission path and the second transmission path by engaging a prescribed clutch mechanism; and a setting means for setting a switching gear ratio zone defining the gear ratio range of the first shifting mechanism in a manner such that the difference in rotations between the engaging members of the engaging clutch mechanisms is at or below a prescribed value when executing the switching shift. Furthermore, the control device is configured so as not to execute the switching shift when a gear ratio outside of the switching gear ratio zone is set in the first shifting mechanism.

A Development of Atmospheric Pressure Plasma Equipment and Its Applications for Treatment of Ag Films Formed from Nano-Particle Ink

Abstract: We have developed an equipment of atmospheric pressure plasma with two microwave guide antennas, which have a discharge line with 41 slots The antennas are set against a stage with a heater in a process chamber A process gas, which is a 1 % H2 gas diluted by Ar gas and its flow rate is 20 standard litter per minute (slm), flows into the micro-wave guide and goes to a process chamber through each slots A micro-wave is introduced to the micro-wave guide and the atmospheric pressure plasma grows at each slots We obtained the electron density of 1×1015 cm−3 and the H radical density of 1×10−16 cm−3 at the slot on the condition of a 10 GHz, 15 kWatt, pulsed micro-wave with 25 pulsed voltage, 4 kHz pulsed frequency, and a duty ratio of 016 We applied this system to improve the quality of the spin-coated Ag firm formed from Ag nano-particle ink This Ag film showed a resistivity of 32 μΩ cm after annealing on the condition of 180 °C for 30 minutes recommended by the maker (The bulk resistivity of Ag is 16 μΩ cm) In order to make the annealing time shorter, we studied the effect of atmospheric plasma treatment of Ag film We obtained the Ag film of the 57 μΩ cm resistivity after the atmospheric pressure plasma treatment under 180 °C for 5 min

Surface loss probability of H radicals on silicon thin films in SiH 4 /H 2 plasma

Abstract: The surface loss probability of H radicals was investigated in SiH4/H2 plasma using vacuum ultraviolet resonance absorption spectroscopy. The surface loss probability was calculated from the decay curve of the H radical density in the plasma afterglow and increased with the SiH4 flow rate. Silicon thin films deposited on the chamber wall were analyzed to investigate the relation between the surface loss probability and the surface condition. The surface reaction of H radicals is influenced by deposition precursors, such as SiH3 radicals. The density of H radicals significantly decreased with heating of the chamber wall up to 473 K. The surface loss probability of H radicals was estimated to be ca. 1 at 473 K. Quantitative measurements of the surface loss probability of H radicals in SiH4/H2 plasma are expected to be particularly important for understanding the surface reactions that occur during the deposition of silicon thin films.

High H Radical Density Produced by 1-m-Long Atmospheric Pressure Microwave Plasma System

Abstract: We have developed an atmospheric pressure microwave plasma system with a microwave antenna consisting of two microwave guides, which have a discharge line with 41 slots The antenna is set against a movable stage with a heater in a process chamber The process gas used is a 1% H2 gas diluted by Ar gas We clarified various characteristics, such as gas temperature, electron density, and hydrogen radical density, using this system, and found that the gas temperature is about 1000 K, the electron density is 1×1015 cm-3, and the H radical density is 1×1016 cm-3 at the slot under the condition of a 10 GHz, 15 kW, pulsed microwave with a pulsed voltage of 25, a pulsed frequency of 4 kHz, and a duty ratio of 016

Method of manufacturing non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery

Abstract: There is provided a method of manufacturing a non-aqueous electrolyte secondary battery equipped with a wound electrode body that is formed by laminating and winding a positive electrode, a negative electrode, and a separator. This method includes preparing the wound electrode body including an uncoated portion of positive electrode active material layers and an uncoated portion of negative electrode active material layers, and not forming the positive electrode active material layers on at least a surface of a positive electrode current collector on a winding outer peripheral side thereof in a region that includes at least an outermost periphery of the positive electrode; structuring the secondary battery by accommodating the wound electrode body in a battery case; and subjecting the secondary battery to an aging treatment in which the secondary battery is retained within a temperature range that is equal to or higher than 60° C.

Controller for vehicle transmission

Abstract: A controller for a vehicle transmission in which a first transmission path including a first transmission mechanism that is able to continuously change its speed ratio and a second transmission path including a second transmission mechanism having a set speed ratio different from that of the first transmission mechanism are provided in parallel with each other between an input shaft to which torque is input from a driving force source of a vehicle and an output shaft that outputs torque to an output member, the vehicle transmission carrying out transmission of power between the input shaft and the output shaft via one of the first transmission path and the second transmission path, includes: performing means for carrying out a change shift for changing a path of the transmission of power between the first transmission path and the second transmission path by engaging a predetermined clutch mechanism; and setting means for setting a change speed ratio region that defines a range of a speed ratio of the first transmission mechanism such that a rotation speed difference between engagement members of the clutch mechanism, which are engaged with each other in carrying out the change shift, is smaller than or equal to a predetermined value. When a speed ratio outside the change speed ratio region is set in the first transmission mechanism, the change shift is not carried out.

Manufacturing device and manufacturing method of group iii nitride semiconductor device; and manufacturing method of semiconductor wafer

Abstract: PROBLEM TO BE SOLVED: To provide a manufacturing device and manufacturing method of a group III nitride semiconductor device and a manufacturing method of a semiconductor wafer which are suitable for mass production and can grow the group III nitride semiconductor device under low temperature as comparison with the prior art.SOLUTION: A manufacturing device 1000 includes: a showerhead electrode 1100; a susceptor 1200 for supporting a growth substrate; a first gas supply pipe 1300; and a second gas supply pipe 1420. The first gas supply pipe 1300 has at least one or more first gas ejection ports and supplies an organic metal gas containing a group III metal as a first gas. A second gas supply pipe 1420 supplies a gas containing a nitride gas as a second gas. The showerhead electrode 1100 is arranged at a position further than the first gas ejection port of the first gas supply pipe 1300 when viewed from the susceptor 1200.

Development of High-Density Nitrogen Radical Source for Low Mosaicity and High Rate Growth of InGaN Films in Molecular Beam Epitaxy

Abstract: A high-density radical source (HDRS) was developed by optimizing the antenna structure and introducing an external magnetic field to plasma. Nitrogen radical generation by the HDRS at a density of 2.3 ×1012 atoms cm-3, which was one order higher than that for the conventional radical source (CRS), was achieved. The HDRS- and CRS-assisted InGaN growth in molecular beam epitaxy (MBE) was carried out. For the HDRS case, a diffraction peak in the X-ray rocking curve of the grown InGaN films showed a narrower peak, which width below 600 arcsec even with a high growth rate of 1.4 µm/h for InGaN. MBE with the assistance of HDRS has a great potential in the growth of nitride films with a lower mosaicity and a higher growth rate.

Etching Enhancement Followed by Nitridation on Low-kSiOCH Film in Ar/C5F10O Plasma

Abstract: The etching rates of low-dielectric-constant (low-k), porous SiOCH (p-SiOCH) films were increased by nitrogen-added Ar/C5F10O plasma etching in dual-frequency (60 MHz/2 MHz)-excited parallel plate capacitively coupled plasma. Previously, perfluoropropyl vinyl ether [C5F10O] provided a very high density of CF3+ ions [Nagai et al.: Jpn. J. Appl. Phys. 45 (2006) 7100]. Surface nitridation on the p-SiOCH surface exposed to Ar/N2 plasma led to the etching of larger amounts of p-SiOCH in Ar/C5F10O plasma, which depended on the formation of bonds such as =C(sp2)=N(sp2)– and –C(sp)≡N(sp).