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81.
Thermal decomposition of titanium(IV) tetra-tert-butoxide (TTB) in inert organic solvents at 573 K yielded microcrystalline anatase (titanium(IV) oxide, TiO2) powders with a crystallite size of ca. 9 nm and a surface area of <100 m2 g-1. Primary and secondary alkoxides of titanium(IV), however, were not decomposed under similar conditions, indicating that the thermal stability of C-O bonds in the alkoxides was a decisive factor for their decomposition. The TiO2 prepared from TTB by this manner was thermally stable upon calcination in air and retained high surface area of ca. 100 m2 g-1 even after calcination at 823 K. The as-prepared TiO2 powders, without calcination, exhibited much higher rate of carbon dioxide formation than any other active photocatalysts such as Degussa P-25 and Ishihara ST-01 in the photocatalytic mineralization of acetic acid in aerated aqueous solutions. The higher activity of the present TiO2 photocatalysts is attributed to both high crystallinity and large surface of the present product. The calcination of the as-prepared TiO2 in air reduced the photocatalytic activity, but it was still higher than the other commercially available TiO2's. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
82.
α-Tocopherol was reacted with methyl linoleateperoxyl radicals at 37°C. The peroxyl radicals were generated by the reaction of methyl linoleate with a free radical initiator, 2,2′-azobis(2,4-dimethylvaleronitrile). The primary products of α-tocopherol with methyl linoleate-peroxyl radicals were isolated by reversephase and normal-phase high performance liquid chromatography (HPLC), and their structures were characterized by ultraviolet (UV), infrared (IR),1H and13C nuclear magnetic resonance (NMR) and mass spectrometry (MS). There were four stereoisomers of methyl 13-(8a-peroxy-α-tocopherone)-9(Z),11(E)-octadecadienoate and four stereoisomers of methyl9-(8a-peroxy-α-tocopherone)-10(E),12(Z)-octadecadienoate.  相似文献   
83.
We have discovered a series of lithium-containing oxides that immediately react with ambient carbon dioxide (CO2) up to 700°C. The products react and return reversibly to the oxides at a temperatures higher than about 700°C. The absorption capacity surpasses that of other CO2 absorbents by a factor of 10. Utilizing these absorbents, the possibility of a CO2 separation system that operates at around 500°C is proposed. It is generally believed that a CO2 separation process operable at temperatures higher than 500°C has the special benefit of a small energy penalty. Moreover, the absorption also proceeds at ambient temperature in the atmospheric environment. This property offers the possibility of many other applications, such as air cleaners or cartridges. Therefore, we think these materials have the potential to make a valuable contribution to the realization of CO2 emission control.  相似文献   
84.
Silver-palladium alloy films were made by a thick-film technique using several metal powders prepared by the spray-pyrolysis method. Two types of powders were used: silver-palladium alloy powders (15 mol % Pd and 30 mol % Pd) and mixtures of silver and palladium powders. The fired films were about 2–3 m in thickness. The alloy particles sintered uniformly in firing, whereas, in the case of the powder mixtures, the alloying of silver and palladium particles caused uneven particle growth and large voids were formed in the fired films. For this reason the films made from the alloy powders had better conductive properties than those made from the powder mixtures. The resistivities of the films made from the alloy powders were close to the intrinsic value for silver-palladium alloys. Further, the oxidation of palladium during heating in air was significantly suppressed in the alloy powders when the palladium content was lower than 30 mol % in accordance with thermodynamic considerations.  相似文献   
85.
T. Arai  Y. Maeda  T. Kato 《CIRP Annals》2006,55(1):7-10
Parameter tuning of force control to achieve operations efficiently in robotic assembly is essential but time-consuming. In this paper, an optimal set of parameters for damping control is computed, which can reduce the cycle time of an assembly operation. The proposed method is formulated as a nonlinear optimization using a dynamic simulator based on 3D geometric model of assembled parts. The method is applied to clutch assembly for practical use. The results verify how the operations can be sped up using the obtained parameters. The proposed method enables users to introduce force control agilely.  相似文献   
86.
In centerless grinding, it is difficult to optimize the grinding conditions for minimizing the workpiece roundness error because of the high number of process parameters such as center height angle, blade angle, and stock removal rate. We had previously proposed a function for evaluating grinding conditions, i.e., the waviness decrease rate, in order to automatically select the optimum process parameters. In order to build a closed-loop control system for the process parameters, however, it is necessary to find a practical way to determine the waviness decrease rate. In this paper, the relationship between the waviness decrease rate and the dynamic components of the grinding force was investigated analytically. It was found that the frequency characteristics of the waviness decrease rate show a similar tendency to those of the grinding force. A grinding force measurement system was built and experiments for measuring the frequency characteristics of the grinding force were carried out. As a result, it was confirmed that the waviness decrease rate can be determined by measuring the frequency characteristics of the grinding force.  相似文献   
87.
Robotic fish are nowadays developed for various types of research, such as bio-inspiredrobotics, biomimetics and animal behavior studies. In the context of our research on the social interactions of the zebrafish Danio Rerio, we developed a miniature robotic fish lure for direct underwater interaction with the living fish. This remotely controlled and waterproof device has a total length of 7.5 cm with the same size ratio as zebrafish and is able to beat its tail with different frequencies and amplitudes, while following the group of living animals using a mobile robot moving outside water that is coupled with the robotic lure using magnets. The robotic lure is also equipped with a rechargeable battery and can be used autonomously underwater for experiments of up to 1 h. We performed experiments with the robot moving inside an aquarium with living fish to analyze its impact on the zebrafish behavior. We found that the beating rate of the tail increased the attractiveness of the lure among the zebrafish shoal. We also demonstrated that the lure could influence a collective decision of the zebrafish shoal, the swimming direction, when moving with a constant linear speed inside a circular corridor. This new robotic fish design and the experimental results are promising for the field of fish–robot interaction.  相似文献   
88.
An upflow anaerobic sludge bed (UASB)-submerged aerated biofilter (SAB) system that treats effluents from a jeans factory was evaluated. The 210-day operational period was divided into three phases (PI, PII and PIII), each with a different hydraulic retention time (HRT in h) and organic loading rate (OLR in kg COD/m3.d). In PI, the best performance was achieved using the UASB (HRT 24, OLR 1.3) with COD and color removal efficiencies of 59 and 64%, respectively; the corresponding values were 77 and 86% for the final effluent. In PII, the efficiencies were 50 and 55% using the UASB (HRT 16, OLR 1.2), respectively, and 69 and 81% for the final system effluent, respectively. In PIII, the UASB (HRT 12 and ORL 3.2) showed the poorest performance; the efficiencies decreased to 48 and 50%, respectively. The same phenomenon occurred in the system with corresponding efficiencies decreasing to 69 and 61%. Throughout the experiment, the system removal efficiencies were between 57 and 88% for nitrogen and between 14 and 63% for sulfate. The final effluent showed relatively non-toxicity or moderate toxicity using Daphnia magna as an indicator. Therefore, the overall results showed that the use of a sequential anaerobic-aerobic system is promising for treatment of textile industrial wastewater.  相似文献   
89.
We have investigated the relation between the crystal structure and superconductivity in La1.9Bi0.1CuO4+ , in which the phase separation observed in La2CuO4+ is suppressed. A phase diagram in theT– plane is given for La1.9Bi0.1CuO4+ with excess oxygen. For very small values, the crystal structure is orthorhombic, and an orthorhombic-tetragonal phase transition occurs markedly at 0.03 in the measured temperature range between 13 and 293 K. Superconductivity is observed in the range of 0.04<<0.11. This is clear evidence thathigh-T c superconductivity also appears in the tetragonal phase.  相似文献   
90.
Methanation reactivity was studied for the surface carbon deposited from CO2 on the surface of Rh-bearing activated magnetite. The most active material (Rh=0.83 wt %) for methanation was prepared by the impregnation method at 60°C and showed 98% conversion at 300°C. The surface carbon was composed of elemental carbon (-carbon) and polymerized carbon (-carbon), the proportion being dependent on the density of carbon deposited. In temperature-programmed surface reaction, the extent of conversion of the - and -carbon to CH4 was 0.34 (-carbon) and 0.53 (-carbon), respectively, and the total conversion was 0.87. This result indicates that not only elemental carbon but polymerized carbon (-carbon) could be converted to CH4 on the Rh-bearing activated (-carbon) magnetite, whereas -carbon is not hydrogenated on activated magnetite.  相似文献   
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