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Boron Nitride Dispersed Nanocomposites with High Thermal Shock Resistance
Kusunose, T.,Sekino, T.,Choa, Y.H.,Nakayama, T.,Niihara, K. The Korean Powder Metallurgy Institute 2001 한국분말재료학회지 (KPMI) Vol.8 No.3
The microstructure and mechanical properties of $Si_3N_4/BN $nanocomposites synthesized by chemical processing were investigated. The nanocomposites containing 15 vol% hexagonal BN (h-BN) were fabricated by hot-pressing $\alpha-Si_3N_4$powders covered with turbostratic BN (t-BN). The t-BN coating on $\alpha-Si_3N_4$particles was prepared by heating $\alpha-Si_3N_4$ particles covered with a mixture of boric acid and urea in hydrogen gas. TEM observations of this nanocomposite revealed that nano-sized h-BN particles were homogeneously dispersed within $Si_3N_4$grains as well as at grain boundaries. The strength and thermal shock resistance were significantly improved in comparison with the $Si_3N_4/BN$ microcomposites.
Yoshihide Kanno,Tetsuya Ohira,Yoshihiro Harada,Shinsuke Koshita,Takahisa Ogawa,Hiroaki Kusunose,Yoshiki Koike,Taku Yamagata,Toshitaka Sakai,Kaori Masu,Keisuke Yonamine,Kazuaki Miyamoto,Megumi Tanaka,T 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.3
Background/Aims: The aim of this study was to evaluate the safety of sedation with propofol as an alternative to benzodiazepinedrugs in outpatient endoscopy. Methods: In this prospective study, examinees who underwent outpatient endoscopy under propofol sedation and submitted a nextdayquestionnaire with providing informed consent were evaluated. Periprocedural acute responses, late adverse events within 24hours, and examinee satisfaction were evaluated. Results: Among the 4,122 patients who received propofol in the 17,978 outpatient-based endoscopic examinations performedbetween November 2016 and March 2018, 2,305 eligible examinees (esophagogastroduodenoscopy for 1,340, endoscopicultrasonography for 945, and total colonoscopy for 20) were enrolled, and their responses to a questionnaire were analyzed. Themean propofol dose was 69.6±24.4 mg (range, 20–200 mg). Diazepam, midazolam, and/or pentazocine in combination withpropofol was administered to 146 examinees. Mild oxygen desaturation was observed in 59 examinees (2.6%); and mild bradycardia,in 2 (0.09%). Other severe reactions or late events did not occur. After eliminating 181 invalid responses, 97.7% (2,065/2,124) of thepatients desired propofol sedation in future examinations. Conclusions: Propofol sedation was found to be safe-without severe adverse events or accidents-for outpatient endoscopy on thebasis of the patients’ next-day self-evaluation. Given the high satisfaction level, propofol sedation might be an ideal tool for painlessendoscopic screening.
Choa Y.H.,Kim B.H.,Jeong Y.K.,Chae K.W.,T.Nakayama,T. Kusunose,T.Sekino,K. Niibara 한국분말야금학회 2001 한국분말재료학회지 (KPMI) Vol.8 No.3
MgO based nanocomposite powder including ferromagnetic iron particle dispersions, which can be available for the magnetic and catalytic applications, was fabricated by the spray pyrolysis process using ultra-sonic atomizer and reduction processes. Liquid source was prepared from iron (Fe)-nitrate, as a source of Fe nano-dispersion, and magnesium (Mg)-nitrate, as a source of MgO materials, with pure water solvent. After the chamber were heated to given temperatures (500~), the mist of liquid droplets generated by ultrasonic atomizer carried into the chamber by a carrier gas of air, and the ist was decomposed into Fe-oxide and MgO nano-powder. The obtained powders were reduced by hydrogen atmosphere at 600~. The reduction behavior was investigated by thermal gravity and hygrometry. After reduction, the aggregated sub-micron Fe/MgO powders were obtained, and each aggregated powder composed of nano-sized Fe/MgO materials. By the difference of the chamber temperature, the particle size of Fe and MgO was changed in a few 10 nm levels. Also, the nano-porous Fe-MgO sub-micron powders were obtained. Through this preparation process and the evaluation of phase and microstructure, it was concluded that the Fe/MgO nanocomposite powders with high surface area and the higher coercive force were successfully fabricated.