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排序方式: 共有1092条查询结果,搜索用时 265 毫秒
71.
Hiromi Yamashita Yo Fujii Yuichi Ichihashi Shu Gou Zhang Keita Ikeue Dal Ryung Park Keiko Koyano Takashi Tatsumi Masakazu Anpo 《Catalysis Today》1998,45(1-4):221-227
Highly dispersed titanium oxide catalysts have been prepared within zeolite cavities as well as in the zeolite framework and utilized as photocatalysts for the reduction of CO2 with H2O to produce CH4 and CH3OH at 328 K. In situ photoluminescence, ESR, diffuse reflectance absorption and XAFS investigations indicate that the titanium oxide species are highly dispersed within the zeolite cavities and framework and exist in tetrahedral coordination. The charge transfer excited state of the highly dispersed titanium oxide species play a significant role in the reduction of CO2 with H2O with a high selectivity for the formation of CH3OH, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity to produce CH4, being similar to reactions on the powdered TiO2 catalysts. Ti-mesoporous molecular sieves exhibit high photocatalytic reactivity for the formation of CH3OH, its reactivity being much higher than the powdered TiO2 catalysts. The addition of Pt onto the highly dispersed titanium oxide catalysts promotes the charge separation which leads to an increase in the formation of CH4 in place of CH3OH formation. 相似文献
72.
Sachiro Kakinoki Makoto Kitamura Mitsuhiro Yuge Masakazu Furuta Masahito Oka Yoshiaki Hirano Kenji Kono Isao Kaetsu 《Polymer Bulletin》2007,58(2):393-400
Summary Poly(proline) and random copolypeptide composed of Pro and Ala residues were synthesized, and their solution properties and
molecular conformation were investigated. Aqueous solutions of the polypeptide were irradiated with γ-rays above the transition
temperature. It was shown that the transition temperature of the aqueous solution of the copolypeptide is influenced by Ala-residue
content and γ-ray irradiation. 相似文献
73.
Medical screws are a common mass-produced implantable medical component made of Titanium. To machine the threads of these types of components, thread whirling with carbide tools is typically used. However, tool wear and low cutting speed limit the productivity and increase the manufacturing cost of such medical parts. In this study, a direct motor driven thread whirling unit for an advanced Swiss-type CNC lathe was developed and it was used with advanced tool materials such as low binder content Cubic boron nitride (CBN) and Polycrystalline diamond (PCD) to find a cost-effective and more productive alternative to carbide tools. 相似文献
74.
Nanoparticles were prepared by the thermosensitive aggregation of the elastin model polypeptide, (GVGVP)251, and gamma-ray crosslinking. Three different heating processes, “slow heating,” “fast heating,” and “heat shock,” were used
for the aggregation of the peptide, followed by gamma-ray crosslinking. Only the “heat shock” process successfully yielded
stable nanoparticles with diameters of less than ca. 150 nm and a narrow size distribution. Circular dichroism (CD) spectrometry
showed that this polypeptide formed a type-II β-turn structure when the temperature was increased to above the cloudy point
in the case of the “heat shock” process; suggesting that this structure might contribute to stable nanoparticle formation
by gamma-rays. CD spectrometry also suggested that this structure would be affected during the formation of stable crosslinked
particles. 相似文献
75.
In this study, we used the minute gas–liquid interfaces around CO2/NH3 microbubbles as new reaction fields where the crystal nucleation progresses and developed a crystallization technique to control the polymorphism of calcium carbonate (CaCO3). In the regions around the gas–liquid interfaces of CO2/NH3 microbubbles, Ca2+ and CO32− ion concentrations can be adjusted because of the characteristic of the electric charge on the bubble surface and the decrease in CO2 concentration based on unit bubble caused by minimization of bubble size, and because of the pH difference between local pH at the gas–liquid interface and overall pH in the bulk liquid caused by mixing of NH3 with CO2; hence, the polymorph change of CaCO3 is expected to occur. CaCO3 was crystallized at 298 K by a semi-batch type reaction in which CO2/NH3/N2 bubbles were continuously supplied to an aqueous Ca(NO3)2 solution using a self-supporting bubble generator. The solution pH during crystallization was maintained at a constant level of 6.9–12.0 by adding HNO3 and NH4OH solution. The average bubble size (dbbl) was varied in the range of 40–1000 μm by controlling the N2 flow rate, and the molar ratio of CO2/NH3 (αCO2/NH3) was set at a specified value of 0.20–1.00 at a constant CO2 flow rate. The following results were obtained by varying solution pH, dbbl, and αCO2/NH3: at a constant dbbl of 40 μm and αCO2/NH3 of 0.20, vaterite and calcite were major products at a solution pH lower than 9.0 and at a solution pH greater than 11.0, respectively, while aragonite was crystallized predominantly in the solution pH range of 9.7–10.5; at a constant solution pH of 9.7 the crystallization of aragonite was accelerated remarkably with a decrease in αCO2/NH3 and dbbl. 相似文献
76.
Shinya Higashimoto Kohei Okada Tomoki Morisugi Masashi Azuma Hiroyoshi Ohue Tae-Ho Kim Masaya Matsuoka Masakazu Anpo 《Topics in Catalysis》2010,53(7-10):578-583
The photocatalytic oxidation of benzyl alcohol into benzaldehyde proceeded with high conversion and selectivity on a TiO2 photocatalyst by O2 under visible light irradiation. Surface complex formed by the interaction of benzyl alcohol with the Ti sites and/or surface OH groups of TiO2 play an important role in the absorption of visible light and unique selective photocatalytic reaction. 相似文献
77.
Tomoharu Suzuki Shigeru Oshio Mari Iwata Hisayo Saburi Takashi Odagiri Tadashi Udagawa Isamu Sugawara Masakazu Umezawa Ken Takeda 《Particle and fibre toxicology》2010,7(1):1-8
Background
Epidemiological studies suggest that inhalation of carbonaceous particulate matter from biomass combustion increases susceptibility to bacterial pneumonia. In vitro studies report that phagocytosis of carbon black by alveolar macrophages (AM) impairs killing of Streptococcus pneumoniae. We have previously reported high levels of black carbon in AM from biomass smoke-exposed children and adults. We therefore aimed to use a mouse model to test the hypothesis that high levels of carbon loading of AM in vivo increases susceptibility to pneumococcal pneumonia.Methods
Female outbred mice were treated with either intranasal phosphate buffered saline (PBS) or ultrafine carbon black (UF-CB in PBS; 500 μg on day 1 and day 4), and then infected with S. pneumoniae strain D39 on day 5. Survival was assessed over 72 h. The effect of UF-CB on AM carbon loading, airway inflammation, and a urinary marker of pulmonary oxidative stress was assessed in uninfected animals.Results
Instillation of UF-CB in mice resulted a pattern of AM carbon loading similar to that of biomass-smoke exposed humans. In uninfected animals, UF-CB treated animals had increased urinary 8-oxodG (P = 0.055), and an increased airway neutrophil differential count (P < 0.01). All PBS-treated mice died within 72 h after infection with S. pneumoniae, whereas morbidity and mortality after infection was reduced in UF-CB treated animals (median survival 48 h vs. 30 h, P < 0.001). At 24 hr post-infection, UF-CB treated mice had lower lung and the blood S. pneumoniae colony forming unit counts, and lower airway levels of keratinocyte-derived chemokine/growth-related oncogene (KC/GRO), and interferon gamma.Conclusion
Acute high level loading of AM with ultrafine carbon black particles per se does not increase the susceptibility of mice to pneumococcal infection in vivo. 相似文献78.
Masao Kubo Takashi Matsubara Satoshi Shimizu Hiroshi Sato 《Artificial Life and Robotics》2010,15(2):207-211
In this article, a new localization approach for a team of robots that use the emergent properties of their formation is proposed.
Synchronized behavior sometimes generates spin-off effects that include geometric patterns. The question then arises as to
whether it is possible to use these patterns for something important for robots. In this article, Takayama’s control strategy,
which is a target enclosure formation, is discussed. A simple and useful expansion of Monte Carlo localization by the emergent
pattern is proposed. The proposed algorithms are confirmed through a series of computer simulations. 相似文献
79.
W. Shin T. Nakashima M. Nishibori T. Itoh N. Izu I. Matsubara Y. Nakagawa A. Yamamoto H. Obara 《Journal of Electronic Materials》2011,40(5):817-822
The performance of a microcombustor thermoelectric generator device based on a thermopile using p-type Bi0.3Sb1.7Te3 (BST) and n-type Pt films has been investigated. The BST films were prepared by two different methods—pulsed laser deposition (PLD) and
sputter deposition—on Si3N4/SiO2 multilayers on Si substrate. The ceramic catalyst combustor was patterned on the thermopile end on a thin membrane fabricated
by back-side bulk etching of the silicon substrate. At 138°C the thermoelectric power factors of the PLD and sputter-deposited
films were 3.6 × 10−3 W/mK2 and 0.22 × 10−3 W/mK2, respectively. The power from the generator with the sputter-deposited film was 0.343 μW, which was superior to that of the device with the PLD film, which provided 0.1 μW, for combustion of a 200 sccm flow of 3 v/v% hydrogen in air. 相似文献
80.
The urban heat island mitigation effect of conversion from asphalt-covered parking areas to grass-covered ones is estimated by observation and calculation. The mean surface temperature in a parking lot is calculated from a thermal image captured by an infrared camera. The sensible heat flux in each parking space is calculated based on the surface heat budget. The reduction in the sensible heat flux is estimated to be approximately 100-150 W m−2 during the day and approximately 50 W m−2 during the night, in comparison with an asphalt surface. The air temperature reduction by the spread of grass-covered parking areas is calculated to be about 0.1 °C. Furthermore, consideration is given to the appearance of the parking lot, the growth of grass, the effects of the weight of a car and the heat radiated from its engine, the costs of construction and maintenance, etc. 相似文献