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181.
182.
Yoshihiro Sagisaka Masayoshi Kamiya Minoru Matsuda Yukihiro Ohta 《Journal of Materials Processing Technology》2010,210(15):2304-2309
A femtosecond laser is a type of ultrashort-pulse laser. Femtosecond laser irradiation induces high-pressure plasma and shock waves at the surface of a target. Under some irradiation conditions, such shock waves are enough to deform the target plastically. Laser peen forming is a type of sheet metal forming using this deformation by shock waves. The author adopted laser peen forming using femtosecond laser for thin-sheet-metal bending. Generally, shock waves induced in air are much smaller than those induced in water, and thus; are unfavorable for plastic deformation. However, the shock waves induced by a femtosecond laser were enough to bend a thin sheet metal even in air. Elastic pre-bending was adopted during the process. Bending angle was increased by applying pre-bending. The effects of laser irradiation conditions on bending efficiency were investigated. The large spot diameter and high fluence improved bending efficiency. 相似文献
183.
Kamiya Noriho; Okimoto Yuko; Ding Zhen; Ohtomo Hiroko; Shimizu Masafumi; Kitayama Atsushi; Morii Hisayuki; Nagamune Teruyuki 《Protein engineering, design & selection : PEDS》2001,14(6):415-419
We have recently generated a new mutant of cytochrome b562 (cytb562)in which Met7, one of the axial heme ligands, is replaced byAla (M7A cytb562). The M7A cytb562 can bind heme and the UV-visibleabsorption spectrum is of a typical high-spin ferric heme. Toinvestigate the effect of the lack of Met7 ligation on the structuralintegrity of cytb562, thermal transition analyses of M7A cytb562were conducted. From the thermodynamic parameters obtained,it is concluded that the folding of M7A cytb562 is comparableto the apoprotein despite the presence of heme. On the otherhand, exogenous ligands such as cyanide and azide ions are readilybound to the heme iron, indicating that the axial coordinationsite is available for substrate binding. The peroxidase activityof this mutant is thus examined to evaluate new enzymatic functionat this site and M7A cytb562 was found to catalyze an oxidationreaction of aromatic substrates with hydrogen peroxide. Theseobservations demonstrate that the Met7/His102 bis-ligation tothe heme iron is crucial for the stable folding of cytb562,whereas the functional conversion of cytb562 is successfullyachieved by the loose folding together with the open coordinationsite. 相似文献
184.
A new type of analog data transmission system using a plastic fiber is proposed, where a direct intensity modulation scheme has been employed together with a differential amplifier to compensate for the transmission error caused by the optical fiber bending loss. This system was experimentally applied to transmit analog data of dimensions detected by the displacement sensor attached to the robot arm tip to the robot basement through the plastic optical fiber installed in the robot arm body 相似文献
185.
A. Suemasu K. Nakahata K. Ro T. Kamiya C. M. Fortmann I. Shimizu 《Solar Energy Materials & Solar Cells》2001,66(1-4)
Polycrystalline silicon (poly-Si) films were deposited on glass by very high-frequency (100 MHz) plasma enhanced chemical vapor deposition from a gaseous mixture of SiF4 and H2 with small amounts of SiH4. (2 2 0) oriented films prepared at small SiF4/H2 ratios (<30/40 sccm) showed intrinsic transport properties of poly-Si. However, the room temperature dark conductivity (σd) of the (4 0 0) oriented film was very high for intrinsic poly-Si, 7.2×10−4S/cm. This conductivity exhibited a T−1/4 behavior, suggesting a high defect density at the grain boundaries. It was found that in situ hydrogen plasma treatment successfully produced (4 0 0) oriented poly-Si with a reasonably low σd of 4.5×10−7S/cm and a good photoconductivity of 1.3×10−4S/cm. 相似文献
186.
Kimitoshi Sato Ji-Guang Li Hidehiro Kamiya Takamasa Ishigaki 《Journal of the American Ceramic Society》2008,91(8):2481-2487
Aggregation and dispersion behavior of nanometer and submicrometer scale TiO2 particles in aqueous suspension were investigated using three kinds of mechanical dispersion methods: ultrasonic irradiation, milling with 5-mm-diameter balls, and milling with 50 μm beads. Polyacrylic acids with molecular weights ranging from 1200 to 30 000 g/mol were used as a dispersant, and the molecular weight for each dispersion condition was optimized. Viscosities and aggregate sizes of the submicrometer powder suspensions were not appreciably changed in the ultrasonic irradiation and 5-mm-ball milling trials. In contrast, in the trials in which nanoparticle suspension was used, ultrasonic irradiation produced better results than 5-mm-ball milling. Use of ultrasonication enabled dispersion of aggregates to primary particle sizes, which was determined based on the specific surface area of the starting TiO2 powders, even for relatively high solid content suspensions of up to 15 vol%. Fifty-micrometer-bead milling was also able to disperse aggregates to the same sizes as the ultrasonic irradiation method, but 50-μm-bead milling can be used only in relatively low solid content suspensions. It was concluded that the ultrasonic dispersion method was a useful way to prepare concentrated and highly dispersed nanoparticle suspensions. 相似文献
187.
Chuanxiang Zhang Kazumichi Yanagisawa Haijun Tao Aymu Onda Tatsuo Shou Sumio Kamiya 《Catalysis Letters》2011,141(9):1311-1315
Abstract
Solvothermal one-step synthesis method was used for the preparation of ruthenium sulfide catalysts supported on the carbon black by the reaction of Ru3(CO)12 and sulfur powder with the carbon black in i-propanol. The carbon black acted as not only a supporting substrate but also a dispersing agent for ruthenium sulfide nanoparticles in the solvothermal one-step synthesis. The oxygen reduction properties of the products prepared by the solvothermal one-step synthesis were improved in comparison with those of the catalysts prepared by physically mixing the carbon black with the solvothermally prepared ruthenium sulfide powder. 相似文献188.
Heusler-type Fe2VAl thin-films were prepared on zirconia substrate by radio-frequency magnetron sputtering. The effect of deposition temperature on crystal structure and electrical properties was investigated. The degree of Heusler-type ordering in crystal structure was enhanced by the increase in deposition temperature. The enhanced Heusler-type ordering contributed to the formation of a steep density of state derived from pseudogap opening near Fermi level, resulting in large Seebeck coefficient. Since the film consisted of submicrometer-size grains, the electrical conductivity and the thermal conductivity of the film were both reduced by the grain boundary effect. The estimated thermoelectric power factor was 1.0 mW/mK2 at 350 K. 相似文献
189.
190.
Crack extension resistance in brittle polycrystals was investigated from the viewpoint of three-dimensional microcrack evolution. Even in the case of macroscopically two-dimensional cracks, inhomogeneous distribution of microscopic stress along the crack front gives rise to three-dimensional structures of extended crack surfaces. Numerical simulations of macroscopic crack extension were carried out, which showed that three-dimensional distribution of grain-by-grain thermal stress leads to a significant increase in the crack extension resistance. It was concluded that three-dimensional interpretation on the microscopic inhomogeneity is necessary for the correct comprehension of macroscopic crack extension behavior in brittle polycrystals. 相似文献