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排序方式: 共有637条查询结果,搜索用时 15 毫秒
81.
Sorimachi A Sakamoto K Sakai M Ishihara H Fukuyama T Utiyama M Liu H Wang W Tang D Dong X Quan H 《Environmental science & technology》2004,38(12):3396-3404
Laboratory and field measurements were conducted to examine dry deposition of SO2 onto Chinese loess surfaces using native soil sampled in the loess plateau, China. The field tests were employed in Beijing and Lanzhou, China, by directly measuring the dry deposition of SO2 on soil, which uses soil put on a collector as an SO2 passive sampling medium. In the laboratory, a high rate of uptake to SO2 deposition for Chinese soil surfaces due to the highly alkalinity was found. The uptake of SO2 deposition was dependent on the pH soil and relative humidity. Furthermore, we evaluated some factors that affect the measurement precision: response of SO2 uptake, repeatability, recovery factor, and variability associated with the weight and the surface coverage on the collectors. As a result, it was shown that the measurement precision was primarily related to the ratio of the SO2 deposition amount relative to the sulfur content of the original soil. This result was consistent with the field observations. The laboratory and field results indicated an excellent agreement on the SO2 uptake inherent in the results from the soil surfaces in different regions. 相似文献
82.
Investigation on fluidmechanic performance on a butterfly valve has been carried out. A practical valve model of a given thickness and a hub is used for the loss coefficient theory. A theoretical loss coefficient has been formulated from a contraction factor obtained by applying the generalized Borda mouthpiece theory.
Cavitation stages (such as cavitation inception, supercavitation inception, cavitation damage inception, choking cavitation) have been theoretically predicted from the valve loss coefficient. The cavitation prediction has been carried out by applying the free streamline theory, where the relation between the loss coefficient and the critical cavitation factor has been formulated. The results of the theoretical prediction equations agree well with the experimental results. 相似文献
83.
Saito Ken Inoue Chikara Ikegawa Jin Yamazaki Kazuhiko Goto Sota Takamura Masato Mihara Shunsuke Suzuki Shinsuke 《Metallurgical and Materials Transactions A》2020,51(9):4499-4510
Metallurgical and Materials Transactions A - In this study, we investigated the effects of the size and distribution of spheroidized cementite on the characteristics of a punched surface as well as... 相似文献
84.
Kyomoto M Moro T Konno T Takadama H Kawaguchi H Takatori Y Nakamura K Yamawaki N Ishihara K 《Journal of materials science. Materials in medicine》2007,18(9):1809-1815
Osteolysis caused by wear particles from polyethylene in the artificial hip joints is a serious issue. We have used photo-induced
radical graft polymerization to graft 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer onto the surface of cross-linked
polyethylene (CLPE-g-MPC) in order to reduce friction and wear at the bearing surface of the joint. The physical and mechanical properties of CLPE
and CLPE-g-MPC were not significantly different, expect that the friction coefficient of untreated CLPE cups was 0.0075, compared with
0.0009 for CLPE-g-MPC cup, an 88% reduction. After 3.0 × 106 cycles in the hip joint simulator test, we could not observe any wear of CLPE-g-MPC cups. We concluded that the advantage of photo-induced radical graft polymerization technique was that the grafted MPC
polymer gave a high lubricity only on the surface and has no effect on the bulk properties of the CLPE substrate. 相似文献
85.
The effects of plant and yeast cerebrosides on melanin formation were examined in B16 mouse melanoma cells. Addition of yeast cerebroside significantly reduced melanin content to the same level as that of arbutin in control cells, although there was no suppression by plant cerebrosides and bovine brain cerebroside up-regulated melanin formation. None of the bovine brain cerebrosides examined had any effect on tyrosinase activity, but yeast cerebroside reduced the contents of tyrosinase. The results of the present study clearly showed that melanin formation is regulated by several different cerebrosides via tyrosinase. In addition, the findings presented here suggest that cerebrosides containing a 9-methyl type sphingoid base, such as yeast cerebroside, may be useful as skincare products for suppressing melanin formation. 相似文献
86.
In this paper, a new application of superconducting magnetic energy storage (SMES) for diagnosis of power systems is proposed. Basic experiments for measurement of damping coefficient of power systems by use of SMES are carried out in an experimental system with a small generator, artificial transmission lines, and a small SMES. The SMES produces small power disturbances in the power system without affecting its operating conditions. The small power oscillations in the power system due to continuous power disturbances generated by SMES are observed. The relations among the damping coefficient, the power disturbances, and the power change of SMES are discussed for a one-machine infinite-bus system. The damping coefficients of the power system are obtained by investigating the oscillations due to the sinusoidal power changes of the SMES. The possibility of estimation of the steady-state power system stability by monitoring the damping coefficients of an operating power system by the use of SMES can be shown experimentally. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 40–48, 1997 相似文献
87.
We synthesized new polymers with both photocrosslinkability and biocompatibility by a random copolymerization of 4‐(4‐methoxycinnamoyl)phenyl methacrylate and 2‐methacryloyloxyethyl phosphorylcholine. These polymers were used as prepolymers to make a hydrogel by photoirradiation. Gelation began with 5 s of photoirradiation and reached an equilibrium state after 360 s of photoirradiation. The absorption maximum at 347 nm, attributed to the cinnamoyl group, disappeared with the photoirradiation time. That is, dimerization between cinnamoyl groups in the polymer proceeded and formed a hydrogel. The equilibrium water concentration of the hydrogels was more than 90%. Moreover, we succeeded in making a microshape hydrogel on glass by photoirradiation through a photomask. The window shape of the photomask was transferred to the hydrogel that was formed. We concluded that these photocrosslinkable polymers could be useful in preparing microfluidic devices for separating or immobilizing biomolecules and cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 44–50, 2007 相似文献
88.
Shimizu H Nagasaki I Matsumura K Sayo N Saito T 《Accounts of chemical research》2007,40(12):1385-1393
Examples of developments in asymmetric hydrogenation from various perspectives, in an effort to improve efficiency, are reported. Discussed in this Account are (1) the improved synthesis of BINAP ligands, (2) the design of SEGPHOS ligands for higher enantioselectivity, (3) a new protocol with fewer reaction steps to synthesize beta-aminoesters, and (4) a novel asymmetric hydrogenation mediated by a copper catalyst. 相似文献
89.
Takashi Fujikawa Hiroshi Kimura Kazuyuki Kiriyama Kazuhiko Hagiwara 《Catalysis Today》2006,111(3-4):188-193
Cosmo Oil has successfully developed a new CoMo HDS catalyst, C-606A, for production of ultra-low sulfur diesel fuels. This catalyst was prepared by an impregnation method using a solution containing Co, Mo, P, and citric acid on a HY-Al2O3. The resulting catalyst air-dried only without calcination. The HDS activity was measured with straight-run light gas oil feedstocks under industrial hydrotreating conditions. C-606A had a three times higher HDS activity compared with the conventional CoMoP/Al2O3 catalyst. Commercial operation with C-606A has successfully demonstrated high performance. This catalyst has superior activity, which enables <10-ppm sulfur content in products in a commercial hydrotreater designed to produce 500-ppm sulfur diesel fuels. 相似文献
90.
Noriaki Kurita Norihiko Fukatsu Teruo Ohashi Satoshi Miyamoto Fumiaki Sato Hiroyuki Nakai Kazuhiko Irie 《Metallurgical and Materials Transactions B》1996,27(6):929-935
We have developed a hydrogen sensor for in situ measurements of hydrogen activities in molten copper. The sensor consists of a concentration cell utilizing a proton conductor,
CaZr0.9In0.1O3-δ, as the solid electrolyte. The electromotive force (emf) of the cell was generated by both hydrogen and oxygen activity gradients
across the cell in a high-temperature region simulating the fire refining processes of copper. However, accurate hydrogen
activity in molten copper could be evaluated from the emf if oxygen activity in molten copper was determined simultaneously
by another concentration cell and if the hydrogen and the oxygen activities at the reference electrode were known. The performance
of the sensor was studied under various conditions. The observed good response and reliability of the sensor show that it
should be a powerful tool for improvement of the fire refining process of the molten copper. Theoretical treatment of the
calculation of the emf of the concentration cells using a mixed ionic conductor, i.e., protonic and oxide ionic conductor, as solid electrolytes is also discussed briefly. 相似文献