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Tetsuya Kameyama - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Plasma Gas composition on bond strength of hydroxyapatite/titanium composite coatings prepared by rf-Plasma spraying
    Journal of The European Ceramic Society, 2005
    Co-Authors: Masahiko Inagaki, Yoshiyuki Yokogawa, Tetsuya Kameyama
    Abstract:

    Abstract The effects of Plasma Gas composition on the bond-strength of HA/Ti composite coatings were investigated. HA/Ti composite coatings were deposited on titanium substrates by a radio-frequency (rf) thermal Plasma spraying method with input powers of 10–30 kW. The ratio of the HA and Ti powders supplied into the Plasma was precisely controlled by two microfeeders so as to change the coating's composition from Ti-rich at the bottom to HA-rich at its upper layer. The bond (tensile) strength of the obtained HA/Ti composite coatings was 40–65 MPa when sprayed with Plasma Gas containing N 2 (i.e., Ar–N 2 ). On the other hand, HA/Ti composite coatings prepared with Plasma Gas containing O 2 (i.e., Ar–O 2 ) had significantly lower bond strength (under 30 MPa). XRD patterns of Ti coatings without HA showed that titanium nitride and titanium dioxide formed, respectively, on titanium deposits sprayed with Ar–N 2 and Ar–O 2 Plasma. Scanning electron microscopic (SEM) observation showed an acicular texture on the Ti deposits prepared with Ar–N 2 Plasma. SEM observations implied that, when sprayed with Ar–O 2 Plasma, a thin TiO 2 layer formed at the interfaces between the Ti splats in the deposits.

  • bond strength improvement of hydroxyapatite titanium composite coating by partial nitriding during rf thermal Plasma spraying
    Surface & Coatings Technology, 2003
    Co-Authors: Masahiko Inagaki, Yoshiyuki Yokogawa, Tetsuya Kameyama
    Abstract:

    Abstract The bond strength of Plasma-sprayed HA/Ti composite coatings on Ti substrate was significantly improved by the partial nitriding of Ti deposits in the coatings during Plasma spraying. HA/Ti composite coatings were deposited on titanium substrates by a radio-frequency thermal Plasma spraying method with RF input powers of 12–27 kW. The ratio of HA and Ti powders supplied into the Plasma was precisely controlled by two microfeeders so as to change the composition from Ti-rich to HA-rich towards the upper layer of the coating. When sprayed in Plasma Gas with 0.8% N2 added, the bond (tensile) strength of the obtained HA/Ti composite coatings sprayed at 12 kW was 41.4 MPa. On the contrary, the bond strength of coatings sprayed with pure Ar at 12 kW was 33.6 MPa regardless of the processing parameters which were almost the same except for Plasma Gas composition. When sprayed with 1.8% N2 added at 27 kW, the bond strength reached 65.3 MPa. XRD patterns of Ti coatings without HA showed that titanium nitrides formed in the titanium deposits sprayed with Plasma Gas containing N2. Scanning electron microscopic observation showed that these Ti deposits had an acicular texture.

Takehiko Hihara - One of the best experts on this subject based on the ideXlab platform.

  • Electrically conductive properties of Ag/Si composite nanoparticle assembled films prepared with a Plasma-Gas-condensation cluster source
    Japanese Journal of Applied Physics, 2014
    Co-Authors: Yuichiro Kurokawa, Takehiko Hihara
    Abstract:

    Ag1−x/Six composite nanoparticle assembled films were prepared using a Plasma–Gas-condensation cluster beam deposition apparatus. The electrical conductivity σ and Hall coefficient |RH| of Ag1−x/Six nanoparticle assembled films obey a power law of the volume fraction of Ag pAg. The marked change at around pAg = pc indicates that the percolation of Ag nanoparticles takes place at the threshold value pc. Moreover, we found that the |RH| at T = 5 K of the Ag1−x/Six nanoparticle assembled film with the closest pAg to pc is 20 times higher than that of the bulk Ag.

  • Electrical Resistivity and Morphology of Sn 1− x /Si x Core–Shell Cluster Network Prepared by a Plasma-Gas-Condensation Cluster Source
    Materials Transactions, 2012
    Co-Authors: Yuichiro Kurokawa, Takehiko Hihara, Kenji Sumiyama
    Abstract:

    Sn11x/Six cluster assembled films have been prepared by a Plasma-Gas-condensation cluster beam deposition apparatus. Transmission electron microscope images indicate that individual clusters have core­shell morphology, where Sn cores are covered by Si shells. Temperature dependence of electrical resistivity exhibits a metallic behavior and a superconducting transition at low temperature for 0 0.29. These results indicate that the cluster network and/or core­shell morphology Sn11x/Six cluster assembled films changes with x. [doi:10.2320/matertrans.M2012232]

  • Face-centered cubic Ti cluster assemblies prepared by Plasma-Gas-condensation
    Materials Transactions, 2008
    Co-Authors: Naokage Tanaka, Kenji Sumiyama, Dongliang Peng, Takehiko Hihara
    Abstract:

    Ti cluster assemblies have been prepared by a Plasma-Gas-condensation cluster deposition system, where the Ar Gas flow rate (RAr) was fixed and the He Gas flow rate (RHe) was varied. The microstructure of Ti clusters has been observed by a transmission electron microscope (TEM). The mean Ti cluster size, dm, decreases with increasing RHe. Ti clusters are hexagonal close-packed (hcp) for dm > 15 nm, while they are face-centered cubic (fcc) for dm < 15 nm. The critical cluster size between the fcc and hcp phases is much larger than the theoretically predicted value and that (5–7 nm) for mechanically milled Ti powders. The fcc phase formation is attributed to the negative internal pressure in small Ti clusters. Moreover, Ti cluster assemblies have been prepared via the above-mentioned procedures with slight introduction of oxygen Gas in the deposition chamber, and investigated by high resolution TEM, electron diffraction, and optical transmittance measurements. No clear core-shell morphology is observed in the partially oxidized Ti cluster assemblies. [doi:10.2320/matertrans.MRA2007174]

  • Structural and optical properties of Ti oxide cluster-assembled films prepared by Plasma-Gas-condensation
    Thin Solid Films, 2008
    Co-Authors: Naokage Tanaka, Kenji Sumiyama, Dongliang Peng, Takehiko Hihara
    Abstract:

    Abstract Ti and Ti oxide cluster-assembled films have been prepared using a Plasma-Gas-condensation apparatus. Transmission electron microscopy and electron diffraction measurement indicates that their structures vary from a face-centered-cubic (fcc) Ti phase, via an NaCl-type TiOx phase, to an amorphous and rutile-type TiO2 mixture phase with increasing the O2 flow rate in the Ar/He Gas mixture. Cluster shapes are spherical for the fcc phase, cubic for the NaCl-type, and spherical for the amorphous and rutile-type mixture, while the cluster size monotonically decreases with increasing O2 flow rate. The Ti and Ti oxide cluster-assembled films have a sooty appearance, showing a very porous morphology in the scanning electron microscopy images. The electrical resistivity dramatically increases between RO2 = 0.065 and 0.075 sccm, while the optical transmittance spectra in the visible wavelength range rapidly increases between RO2 = 0.1 and 0.12 sccm, well reflecting the structure variations in these Ti and Ti oxide cluster-assembled films.

  • Formation and magnetic properties of the fcc-FeN compound clusters prepared by Plasma-Gas-condensation
    Journal of Alloys and Compounds, 2004
    Co-Authors: Dongliang Peng, Takehiko Hihara, Kenji Sumiyama
    Abstract:

    Abstract The compound FeN clusters with cluster sizes of d=8–25 nm were synthesized using a Plasma-Gas-condensation (PGC) cluster deposition apparatus with changing the nitrogen Gas flow rate RN2, and their crystal structures and magnetic properties were investigated. The fcc single-phase FeN clusters which have a tetrahedron shape are obtained, and their lattice parameter is a=0.428 nm, being close to that (a=0.433 nm) of ZnS-type FeN films but clearly different from that (a=0.457 nm) of NaCl-type FeN films. The magnetic measurement results indicate that the present ZnS-type FeN clusters are non-magnetic. The characteristic cusp at Tf=8 K on the zero field cooling (ZFC) thermomagnetic curve is attributed to superparamagnetic behavior of Fe-oxide layer crystallites formed on the FeN cluster surfaces.

Kenji Sumiyama - One of the best experts on this subject based on the ideXlab platform.

  • Electrical Resistivity and Morphology of Sn 1− x /Si x Core–Shell Cluster Network Prepared by a Plasma-Gas-Condensation Cluster Source
    Materials Transactions, 2012
    Co-Authors: Yuichiro Kurokawa, Takehiko Hihara, Kenji Sumiyama
    Abstract:

    Sn11x/Six cluster assembled films have been prepared by a Plasma-Gas-condensation cluster beam deposition apparatus. Transmission electron microscope images indicate that individual clusters have core­shell morphology, where Sn cores are covered by Si shells. Temperature dependence of electrical resistivity exhibits a metallic behavior and a superconducting transition at low temperature for 0 0.29. These results indicate that the cluster network and/or core­shell morphology Sn11x/Six cluster assembled films changes with x. [doi:10.2320/matertrans.M2012232]

  • Face-centered cubic Ti cluster assemblies prepared by Plasma-Gas-condensation
    Materials Transactions, 2008
    Co-Authors: Naokage Tanaka, Kenji Sumiyama, Dongliang Peng, Takehiko Hihara
    Abstract:

    Ti cluster assemblies have been prepared by a Plasma-Gas-condensation cluster deposition system, where the Ar Gas flow rate (RAr) was fixed and the He Gas flow rate (RHe) was varied. The microstructure of Ti clusters has been observed by a transmission electron microscope (TEM). The mean Ti cluster size, dm, decreases with increasing RHe. Ti clusters are hexagonal close-packed (hcp) for dm > 15 nm, while they are face-centered cubic (fcc) for dm < 15 nm. The critical cluster size between the fcc and hcp phases is much larger than the theoretically predicted value and that (5–7 nm) for mechanically milled Ti powders. The fcc phase formation is attributed to the negative internal pressure in small Ti clusters. Moreover, Ti cluster assemblies have been prepared via the above-mentioned procedures with slight introduction of oxygen Gas in the deposition chamber, and investigated by high resolution TEM, electron diffraction, and optical transmittance measurements. No clear core-shell morphology is observed in the partially oxidized Ti cluster assemblies. [doi:10.2320/matertrans.MRA2007174]

  • Structural and optical properties of Ti oxide cluster-assembled films prepared by Plasma-Gas-condensation
    Thin Solid Films, 2008
    Co-Authors: Naokage Tanaka, Kenji Sumiyama, Dongliang Peng, Takehiko Hihara
    Abstract:

    Abstract Ti and Ti oxide cluster-assembled films have been prepared using a Plasma-Gas-condensation apparatus. Transmission electron microscopy and electron diffraction measurement indicates that their structures vary from a face-centered-cubic (fcc) Ti phase, via an NaCl-type TiOx phase, to an amorphous and rutile-type TiO2 mixture phase with increasing the O2 flow rate in the Ar/He Gas mixture. Cluster shapes are spherical for the fcc phase, cubic for the NaCl-type, and spherical for the amorphous and rutile-type mixture, while the cluster size monotonically decreases with increasing O2 flow rate. The Ti and Ti oxide cluster-assembled films have a sooty appearance, showing a very porous morphology in the scanning electron microscopy images. The electrical resistivity dramatically increases between RO2 = 0.065 and 0.075 sccm, while the optical transmittance spectra in the visible wavelength range rapidly increases between RO2 = 0.1 and 0.12 sccm, well reflecting the structure variations in these Ti and Ti oxide cluster-assembled films.

  • Formation and magnetic properties of the fcc-FeN compound clusters prepared by Plasma-Gas-condensation
    Journal of Alloys and Compounds, 2004
    Co-Authors: Dongliang Peng, Takehiko Hihara, Kenji Sumiyama
    Abstract:

    Abstract The compound FeN clusters with cluster sizes of d=8–25 nm were synthesized using a Plasma-Gas-condensation (PGC) cluster deposition apparatus with changing the nitrogen Gas flow rate RN2, and their crystal structures and magnetic properties were investigated. The fcc single-phase FeN clusters which have a tetrahedron shape are obtained, and their lattice parameter is a=0.428 nm, being close to that (a=0.433 nm) of ZnS-type FeN films but clearly different from that (a=0.457 nm) of NaCl-type FeN films. The magnetic measurement results indicate that the present ZnS-type FeN clusters are non-magnetic. The characteristic cusp at Tf=8 K on the zero field cooling (ZFC) thermomagnetic curve is attributed to superparamagnetic behavior of Fe-oxide layer crystallites formed on the FeN cluster surfaces.

  • Electron transport properties in Nb and NbN cluster-assembled films produced by a Plasma–Gas–condensation cluster source
    Journal of Applied Physics, 2003
    Co-Authors: Takehiko Hihara, Dongliang Peng, Y. Yamada, M. Katoh, Kenji Sumiyama
    Abstract:

    Nb and NbN cluster-assembled films were produced by a Plasma–Gas–condensation cluster deposition apparatus and examined by transmission electron microscopy, electrical resistivity, and ultraviolet photoemission spectroscopy. The electron diffraction patterns of the Nb and NbN clusters displayed body-centered-cubic and NaCl-type diffraction rings, respectively. The electrical sheet resistance, R□, of both Nb and NbN cluster-assembled films, however, showed no superconductivity down to 2 K. We found a linear relation in the log R□ versus T−1/4 plot for the Nb cluster assembly, suggesting an electron localization effect. For the NbN cluster-assembly, on the other hand, R□ showed a semiconductor type temperature dependence, which is consistent with the valence electron spectra.

Masahiko Inagaki - One of the best experts on this subject based on the ideXlab platform.

  • Effects of Plasma Gas composition on bond strength of hydroxyapatite/titanium composite coatings prepared by rf-Plasma spraying
    Journal of The European Ceramic Society, 2005
    Co-Authors: Masahiko Inagaki, Yoshiyuki Yokogawa, Tetsuya Kameyama
    Abstract:

    Abstract The effects of Plasma Gas composition on the bond-strength of HA/Ti composite coatings were investigated. HA/Ti composite coatings were deposited on titanium substrates by a radio-frequency (rf) thermal Plasma spraying method with input powers of 10–30 kW. The ratio of the HA and Ti powders supplied into the Plasma was precisely controlled by two microfeeders so as to change the coating's composition from Ti-rich at the bottom to HA-rich at its upper layer. The bond (tensile) strength of the obtained HA/Ti composite coatings was 40–65 MPa when sprayed with Plasma Gas containing N 2 (i.e., Ar–N 2 ). On the other hand, HA/Ti composite coatings prepared with Plasma Gas containing O 2 (i.e., Ar–O 2 ) had significantly lower bond strength (under 30 MPa). XRD patterns of Ti coatings without HA showed that titanium nitride and titanium dioxide formed, respectively, on titanium deposits sprayed with Ar–N 2 and Ar–O 2 Plasma. Scanning electron microscopic (SEM) observation showed an acicular texture on the Ti deposits prepared with Ar–N 2 Plasma. SEM observations implied that, when sprayed with Ar–O 2 Plasma, a thin TiO 2 layer formed at the interfaces between the Ti splats in the deposits.

  • bond strength improvement of hydroxyapatite titanium composite coating by partial nitriding during rf thermal Plasma spraying
    Surface & Coatings Technology, 2003
    Co-Authors: Masahiko Inagaki, Yoshiyuki Yokogawa, Tetsuya Kameyama
    Abstract:

    Abstract The bond strength of Plasma-sprayed HA/Ti composite coatings on Ti substrate was significantly improved by the partial nitriding of Ti deposits in the coatings during Plasma spraying. HA/Ti composite coatings were deposited on titanium substrates by a radio-frequency thermal Plasma spraying method with RF input powers of 12–27 kW. The ratio of HA and Ti powders supplied into the Plasma was precisely controlled by two microfeeders so as to change the composition from Ti-rich to HA-rich towards the upper layer of the coating. When sprayed in Plasma Gas with 0.8% N2 added, the bond (tensile) strength of the obtained HA/Ti composite coatings sprayed at 12 kW was 41.4 MPa. On the contrary, the bond strength of coatings sprayed with pure Ar at 12 kW was 33.6 MPa regardless of the processing parameters which were almost the same except for Plasma Gas composition. When sprayed with 1.8% N2 added at 27 kW, the bond strength reached 65.3 MPa. XRD patterns of Ti coatings without HA showed that titanium nitrides formed in the titanium deposits sprayed with Plasma Gas containing N2. Scanning electron microscopic observation showed that these Ti deposits had an acicular texture.

Jue Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Correction: Cold Plasma Gas loaded microbubbles as a novel ultrasound contrast agent.
    Nanoscale, 2019
    Co-Authors: Feihong Dong, Jiabin Zhang, Kaile Wang, Zhengxin Liu, Jinsong Guo, Jue Zhang
    Abstract:

    Correction for ‘Cold Plasma Gas loaded microbubbles as a novel ultrasound contrast agent’ by Feihong Dong et al., Nanoscale, 2019, 11, 1123–1130.

  • Cold Plasma Gas loaded microbubbles as a novel ultrasound contrast agent.
    Nanoscale, 2019
    Co-Authors: Feihong Dong, Jiabin Zhang, Kaile Wang, Zhengxin Liu, Jinsong Guo, Jue Zhang
    Abstract:

    Nowadays, cold atmospheric Plasma (CAP) that contains lots of active free radicals has tremendous potential applications in biomedical engineering, and target delivery of a controllable dose of Plasma Gas is highly desired in clinical use. In this conceptual study, we developed a novel microbubble loaded by Plasma Gas and proposed an ultrasound-triggered strategy for the ultrasound-triggered release of free radicals from the microbubbles. The Plasma microbubbles (PMBs) were fabricated by mixing Plasma Gas in the core of the surfactant microbubbles by a modified emulsification process. The resulting PMBs with an average size of 2.54 ± 2.28 μm were successfully fabricated using the proposed approach and the experimental result showed that PMBs exhibited a satisfactory ability to meet the requirement of ultrasound contrast-enhanced imaging. Furthermore, we depicted that ultrasound induced PMB destruction to release the Plasma Gas and PMBs with ultrasound stimulation could significantly improve the concentration of nitric oxide and hydrogen peroxide compared with the control group. In addition, Dil acting as a model drug was loaded into the PMBs and an in vitro cell experiment showed that Dil and Plasma Gas could be released from PMBs and internalized by PIEC cells with ultrasound mediation. Our experimental results showed that ultrasound induced PMB destruction could successfully release many active free radicals in Plasma Gas, including nitric oxide and hydrogen peroxide. The developed novel microbubbles demonstrated the technical potential of Plasma Gas loaded MBs for disease diagnostics and therapy with ultrasound imaging guidance.