Shigeyuki Masutani

Temperature rise during polymerization of visible light-activated composite resins.

Abstract The temperature rise was monitored during the exothermic polymerization reaction of 5 selected visible light-activated composite resins cured with 5 activator lights. In general, temperature peaks occurring at curing times of less than 31 s were higher than those peaks occurring between 31 and 60 s of cure. The speed of the exothermic reaction of visible light composite resin materials increases with increasing intensity of the light source. A higher intensity light source is more effective in curing the resins than higher temperature generated by the light source. As a variable, the resin itself, rather than the light source, had a more pronounced, effect upon the temperature rise during curing. For those visible light-cured resins that take a long time to reach their peak temperature, a prolonged exposure time is needed to achieve a proper cure.

Micro-Inactivation of Coliforms by Low-Temperature and Atmospheric-Pressure Plasma Irradiation

In this study, we report on the inactivation technique to apply the oral surgery by micro low-temperature and atmospheric-pressure plasma irradiation utilizing a capillary nozzle. Emission spectrum of the micro-plasma showed OH and O radical, which were affected inactivation of coliform. Vibration temperature of the micro-plasma with 7998 K was calculated from peak-intensity at emission due to N2 2nd positive system. Inactivation region was larger than plasma irradiation spot, and it was increasing with plasma irradiation time.

Micro-Biocidal Activity of Yeast Cells by Needle Plasma Irradiation at Atmospheric Pressure

In this study, we report on the biocidal activity technique by needle helium plasma irradiation at atmospheric pressure using borosilicate capillary nozzle to apply for the oral surgery. The diameter of needle plasma was less than 50 m, and temperature of plasma irradiated area was less than body temperature. Needle plasma showed emission due to OH and O radical. Raman spectra and methylene blue stain showed yeast cells were inactivated by needle plasma irradiation.

Application of Coaxial Ion Gun for Film Generation and Ion Implantation

A magnetized coaxial plasma gun (MCPG) is here utilized for deposition on high-melting-point metals. MCPGs have hitherto been studied mostly in the context of nuclear fusion research, for particle and magnetic helicity injection and spheromak formation. During spheromak formation, the electrode materials are ionized and mixed into the plasmoid. In this study, this ablation process by gun-current sputtering is enhanced for metallic thin-film generation. In the proposed system geometry, only ionized materials are electromagnetically accelerated by the self-Lorentz force, with ionized operating gas as a magnetized thermal plasmoid, contributing to the thin-film deposition. This reduces the impurity and non-uniformity of the deposited thin-film. Furthermore, as the ions are accelerated in a parallel direction to the injection axis, vertical implantation of the ions into the substrate surface is achieved. To test a potential application of the developed system, experiments were conducted involving the formation of a buffer layer on hard ceramics, for use in dental materials.

Argon ion laser technique for higher degree of polymerization at deep area of dental restorative resin

We have developed a technique for a higher degree of polymerization at the deep area of dental restorative resins by argon ion laser irradiation. We provide an analysis of the resin materials by Raman spectroscopy and Fourier transform infrared spectroscopy.