Papers by Keyword: Laser Ablation Method

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Authors: Ei Yamamoto, Nobuhiro Kato, Arata Isai, Hiroaki Nishikawa, Yoshiya Hashimoto, Kazushi Yoshikawa, Shigeki Hontsu
Abstract: Once tooth decay reaches to the inside of dentin, the damage remains permanently. Therefore, the restoration of dentin is important in dental treatment. In the present study, we newly proposed a tooth restoration technique with intraoral laser ablation method. A thin layer of a-tricalcium phosphate (a-TCP) was deposited on dentin surface in the atmosphere by ablation phenomenon using an Er:YAG (Erbium: Yttrium-Aluminium-Garnet) laser irradiated to the target of a-TCP. Then, the deposited layer was hydrolyzed by dripping pure water on its surface in order to create hydroxyapatite (HAp) coating. Interface structure between the HAp coating and dentin surface was observed by a scanning electron microscope. Electron micrographs showed that the HAp layer of 10-20 mm in thickness was formed on the dentin surface. Moreover, dentinal tubules were sealed with the HAp particles. These results indicate that our newly proposed technique is useful for the treatment of dentin cavities.
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Authors: Akihiro Yamada, Hideki Ohashi, Yoshikado Shinzo
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Authors: Sayuki Sawa, Shinzo Yoshikado
Abstract: Planar-type thin film Bi-Mn-Co-doped ZnO varistors were fabricated on a silica glass substrate or a sintered alumina substrate using a visible light (532 nm) pulsed laser ablation method. The deposited thin films were annealed at 800°C or 900°C in air. For the thin films deposited on alumina substrates and then annealed, the contents of Bi and Mn decreased compared with those of the as-deposited films. Voltage-current (V-I) characteristics of the thin-film varistor fabricated on the alumina substrates and annealed showed nonlinearity. The nonlinearity index α was approximately 10 for the thin film deposited on the alumina substrate and annealed at 800°C in air using a target of ZnO doped with 2.5 mol% Bi2O3, 0.5 mol% MnO2 and 0.2 mol% Co3O4. Moreover, the current density of 20 A/cm3 was relatively high for safety use.
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