Methane production from carbon dioxide and hydrogen is known as the Sabatier reaction. However, methanation process by the Sabatier reaction requires high temperatures and high pressures. Therefore, we tried to generate methane by mechanochemical method, using ball-milling as a new methanation process. As a result of ball milling for 3 hours at room temperature, generation of methane was observed. On the other hand, carbon dioxide was consumed more than expected. As for further verification, ball-milling was carried out for 6 hours under carbon dioxide atmosphere. EDX elemental analysis of the milled powder revealed significantly increased carbon content, suggesting the reaction of LaNi5 surface with CO2 followed by the formation of carbides or carbonates of La or Ni. A unique XRD profile was observed in the milled sample, yielding broad amorphous-like peak, possibly from La, and broad peak of Ni. It was shown that ball milling may cause phase separation into La and Ni not only in hydrogen atmosphere but also in carbon dioxide atmosphere.
Up-conversion phosphors emit light with shorter wavelength than that of excitation light. This phenomenon is caused by multi-photon excitation and energy transfer in f orbital of rare earth elements. In this study, La2ZnTiO6 and La2MgTiO6 doped with different amounts of Er and Yb was synthesized by the complex gelation method and the up-conversion (UPC) emission was investigated. In addition, we investigated the difference in optimum amount of Er and Yb for UPC emission due to host crystals. Main crystal phases of the synthesized samples were identified as La2ZnTiO6 and La2MgTiO6 respectively by X-ray diffraction. Up-conversion emissions were measured using a spectrometer with a multi-channel photo detector and a diode laser emitting excitation light at 980nm. The optimum amount of Er and Yb in (La, Er, Yb)2ZnTiO6 for the up-conversion emission were 1mol% and 5mol%, respectively. On the other hand, the optimum amount of Er and Yb in (La, Er, Yb)2MgTiO6 were 2mol% and 2mol%, respectively. The optimized sample showed strong green and red emissions. As the result, it was shown that the double perovskite type oxide doped with Er and Yb showed UPC luminescence, and the optimum doping amount of Er and Yb depended on the host crystal.
We have focused on effect of rutile type TiO2 to ETL (electron transport layers) of hybrid perovskite solar cells. The rutile type TiO2 was synthesized by a hydrothermal method using a water-soluble titanium complex as a titanium source. In order to improve dispersibility, rutile type TiO2 was modified by various types of dispersants. When Triton X was used as a dispersant, dispersibility of rutile type TiO2 was improved, and FTO glass could be uniformly covered. Using this substrate, perovskite solar cell was fabricated. Energy conversion efficiency of the cell was 10.42 %.
Magnesium alloys have recently been expected as a main material for a bioresorbable vascular stent. However, the alloys have a major defect, a very poor corrosion resistance under the wet circumstance such as a body. One of the methods to give the corrosion resistance to the Mg alloys, polymer coating has been investigated. From these back grounds, we designed a new coating polymer, poly(2-methoxyethyl methacrylate¬rantrimethoxysilylplopyl methacrylate), and investigated the effect of silyl group on their biocompatibility and ability to give a corrosion resistance to the alloy. The polymer showed good compatibility with platelets and coagulation system and improved the corrosion resistance in the cell culture medium as a simulated body fluid.
Human safety is important in human-friendly robots. In this paper, we propose a new compact velocity-based mechanical safety device for human-friendly robots in order to improve the safety of humans. This safety device is attached to each of the robot’s driveshafts. The safety device stops the robot if it detects an unexpected high angular velocity in the driveshafts. The safety device works even when the robot’s computer breaks down, because it consists of only passive mechanical components without actuators, controllers, or batteries. First, we describe the features of the safety device. Next, we explain the structure and mechanism of the safety device. Third, we present the design of the safety device. Finally, we check whether the safety device achieves the necessary functions by using a 3D CAD.