Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has excellent mechanical properties and bone conductivity. For dental application, TNTZ surfaces were converted to white oxidized layer by a simple heat treatment in air to achieve the formation of aesthetic surfaces. The oxidized layer formed by the heat treatment at 1000°C for 0.5 or 1 hr was whiter and joined to TNTZ substrate more strongly than that formed by the treatment at 900°C. The layer consisted of TiO2(rutile), TiNb2O7, and TiTa2O7and possessed ~30 μm in thickness for the sample heat-treated at 1000°C and ~10 μm for that heat-treated at 900°C. The surface average roughness and the wettability increased after the heat treatment. The spreading and proliferation level of mouse osteoblast-like cell (MC3T3-E1 cell) on the heat-treated sample were almost the same as those on as-prepared one. The cell spreading on TNTZ was better than those on pure titanium (CP Ti) regardless of the heat treatment for the samples. There was no deterioration in thein vitrocell compatibility of TNTZ after the oxidized layer coating by the heat treatment.
In and around Otomeyama Park, Shinjuku Ward, Tokyo Metropolis, we manually measured natural spring water flow in April 2009-January 2016 and monitored groundwater level in September 2011-May 2015. We adopted a tank model to simulate the groundwater level by using precipitation data near the park. As a result, the simulation was very reasonable with a high NSE Nash-Sutcliffe Efficiency value of 0.993. Moreover, we tried to estimate the recharge area of the spring water by using Radar-raingauge Analyzed Precipitation on the assumption that the tank model can be adapted to wide range. First, we selected five candidates for the recharge area around the park, and we got the average precipitation for each of them. Then we calculated groundwater levels by inputting the five average precipitation values into the tank model. For the calculation, the parameters of the tank model were fixed. We compared calculated and measured groundwater levels, and found the area was about 10 km 2 for which the NSE was the highest and RMSE Root Mean Squared Error was the lowest. Also, we analyzed the water quality of the spring. Observed SiO 2 concentration and electric conductivity showed only slight differences on heavy-rainfall days and sunny days. This suggests that relatively old water stored was pushed out by newly recharged water during heavy rainfall events.
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