Apatite-type ALa 9 Si 6 O 26 (A = Li, Na, K) were prepared by solid state reaction method. The hexagonal unit cell volumes of ALa 9 Si 6 O 26 increased with increasing ionic radii of alkali metal ions, indicating that the alkali metal ions were incorporated into the apatite-type lattice. The specific surface areas of ALa 9 Si 6 O 26 were less than 1 m 2 /g. X-ray photoelectron spectroscopy measurement showed that Pt species on as-prepared catalysts were highly oxidized. Reduction temperature of Pt oxides on the catalyst for temperature-programmed reduction by H 2 was decreased by substitution of alkali metal ion at La site in the apatitetype silicate. For C 3 H 6 NOO 2 reaction, Pt/NaLa 9 Si 6 O 26 catalyst exhibited a maximum NO conversion of 42%, the highest among Pt/ALa 9 Si 6 O 26 catalysts. The temperature for maximum NO conversion over Pt/NaLa 9 Si 6 O 26 catalyst was lower than that over Pt/£-Al 2 O 3 catalyst under the same reaction condition. The temperature of 50% C 3 H 6 conversion for C 3 H 6 O 2 reaction over Pt/ALa 9 Si 6 O 26 catalysts increased in the sequence of A = K < A = Na < A = Li. In addition, C 3 H 6 oxidation activity was suppressed by presence of CO 2 and NO on the catalyst. These results suggest that the basic sites on the apatite-type support affect the catalytic activities of Pt/ALa 9 Si 6 O 26 catalysts for C 3 H 6 NOO 2 and C 3 H 6 O 2 reaction.
We have developed a system for measuring the radius of curvature of a micro spherical surface whose radius is several I 0 tm to several 1 00 jim. This measuring system can measure a spherical surface by two methods, namely a Linnik microinterferometer and a micro-collimator. In addition, this measuring system can measure a flat surface by a double-beam interferometer. Furthermore, the change of the optical system among those three measuring methods can be easily done by moving only the lens and shutter. Therefore, in this measuring system, each of the three measuring functions can be utilized without changing the setting of the workpiece. Thereby, the setting error among the three measuring methods can be eliminated, so that the measuring accuracy and the measuring reliability have been improved.
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