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121.
The first successful Pd-catalyzed intramolecular ipso-Friedel-Crafts allylic alkylation of phenols, which provided a new access to spiro[4.5]cyclohexadienones, is described. The present method could be applied to catalytic enantioselective construction of an all-carbon quaternary spirocenter. 相似文献
122.
Zirconium oxide is active for photoreduction of gaseous carbon dioxide to carbon monoxide with hydrogen. A stable surface
species arises under the photoreduction of CO2 on zirconium oxide, and it is identified as surface formate by infrared spectroscopy. Adsorbed CO2 is converted to formate by photoreaction with hydrogen. The surface formate is a true reaction intermediate since CO is formed
by the photoreaction of formate and CO2; surface formate works as a reductant of carbon dioxide to yield carbon monoxide. The dependence on the wavelength of irradiation
light shows that a bulk ZrO2 is not a photoactive species. When ZrO2 adsorbs CO2 a new band appears in photoluminescence excitation spectrum. The photoactive species in the reaction that CO2+H2 yields HCOO− is presumably formed by the adsorption of CO2 on ZrO2 surface. Hydrogen molecules play a role to supply an atomic hydrogen. Therefore, methane molecules can also be used as a
reductant of carbon dioxide. 相似文献
123.
Yoshiumi Kohno Saeko Asai Masashi Shibata Choji Fukuhara Yasuhisa Maeda Yasumasa Tomita Kenkichiro Kobayashi 《Journal of Physics and Chemistry of Solids》2014
β-carotene and annatto extract are typical carotenoids used as safe colorants for foods. However, the instability against irradiation limits their wide use. The improvement of stability was investigated by the intercalation of dye into the interlayer space of the anion-exchangeable clay, hydrotalcite. A hydrophobic environment was constructed in the interlayer space of the hydrotalcite by its modification with anionic surfactants (dodecyl sulfate and dodecylbenzene sulfonate). The lipophilic β-carotene and annatto dye were successfully incorporated into the organo-modified hydrotalcite, and the incorporated dyes exhibited improved photostability under visible irradiation from a 100 W halogen lamp (190 klux) in the air. The effect of the stabilization on the anionic annatto dye was higher by the incorporation in the modified hydrotalcite than that in the modified cation exchangeable clay, suggesting that the polarity of the clay sheet had some influence on the stabilization of the incorporated dye. The stabilization effect of β-carotene was not so significant as that of the annatto dye, because sufficient intercalation of non-polar β-carotene might require stronger hydrophobic environment. The π–π interaction between the β-carotene and the benzene ring of dodecylbenzene sulfonate was found to contribute to the stability enhancement. 相似文献
124.
Formal synthesis of soybean phytoalexin glyceollin I 总被引:1,自引:0,他引:1
Glyceollins are well-known phytoalexins isolated from soybean (Glycine max). An efficient three-step synthesis was developed for the preparation of the key intermediate in Khupse’s glyceollin I synthesis. Claisen rearrangement-cyclization cascade reaction and Suzuki–Miyaura cross coupling were key steps in this method. 相似文献
125.
Takahashi O Kohno Y Saito K Nishio M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(3):756-762
Ab initio MO calculations were carried out to examine the conformational energies of various benzylic compounds C(6)H(5)CH(2)XR (X=O, CH(2), CO, S, SO, SO(2); R=CH(3), C(2)H(5), iC(3)H(7), tC(4)H(9)) at the MP2/6-311G(d,p)//MP2/6-31G(d) level. Rotamers with R/Ph in gauche relationship are generally more stable than the R/Ph anti rotamers. In these stable geometries, the interatomic distance in the interaction of alpha- or beta-CH in the alkyl group and the ipso-carbon atom of the phenyl ring is short. The computational results are consistent with experimental data from supersonic molecular jet spectroscopy on 3-n-propyltoluene and NMR and crystallographic data on structurally related ketones, sulfoxides, and sulfones. In view of this, the alkyl/phenyl-congested conformation of these compounds has been suggested to be a general phenomenon, rather than an exception. The attractive CH/pi interaction has been suggested to be a dominant factor in determining the conformation of simple aralkyl compounds. 相似文献
126.
Akihiro Suzuki Takafumi Kohno Toshio Kunugi 《Journal of Polymer Science.Polymer Physics》1998,36(10):1731-1738
A zone-drawing and zone-annealing treatment was applied to poly(p-phenylene sulfide) fibers in order to improve their mechanical properties. The zone-drawing (ZD) was carried out at a drawing temperature of 90°C under an applied tension of 5.5 MPa, and the zone-annealing (ZA) was carried out at an annealing temperature of 220°C under 138.0 MPa. The differential scanning calorimetry (DSC) thermogram of the ZD fiber had a broad exothermic transition (Tc = 110°C) attributed to cold-crystallization and a melting endotherm peaking at 286°C. The Tc of the ZD fiber was lower than that (Tc = 128°C) of the undrawn fiber. In the temperature dependence of storage modulus (E′) for the ZD fiber, the E′ values decreased with increasing temperature, but increased slightly in the temperature range of 90–100°C, and decreased again. The slight increase in E′ was attributable to the additional increase in the crosslink density of the network, which was caused by strain-induced crystallization during measurement. The resulting ZA fiber had a draw ratio of 6.0, a degree of crystallinity of 38%, a tensile modulus of 8 GPa, and a tensile strength of 0.7 GPa. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1731–1738, 1998 相似文献
127.
128.
A novel numerical scheme is developed by coupling the level set method with the adaptive mesh refinement in order to analyse moving interfaces economically and accurately. The finite element method (FEM) is used to discretize the governing equations with the generalized simplified marker and cell (GSMAC) scheme, and the cubic interpolated pseudo‐particle (CIP) method is applied to the reinitialization of the level set function. The present adaptive mesh refinement is implemented in the quadrangular grid systems and easily embedded in the FEM‐based algorithm. For the judgement on renewal of mesh, the level set function is adopted as an indicator, and the threshold is set at the boundary of the smoothing band. With this criterion, the variation of physical properties and the jump quantity on the free surface can be calculated accurately enough, while the computation cost is largely reduced as a whole. In order to prove the validity of the present scheme, two‐dimensional numerical simulation is carried out in collapse of a water column, oscillation and movement of a drop under zero gravity. As a result, its effectiveness and usefulness are clearly shown qualitatively and quantitatively. Among them, the movement of a drop due to the Marangoni effect is first simulated efficiently with the present scheme. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
129.
Adrien Danel Nicolas Cabuil Thierry Lardin Dominique Despois Marc Veillerot Charles Geoffroy Motoyuki Yamagami Hiroshi Kohno 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
The issues related to the matching between the 3 modes of Total-reflection X-Ray Fluorescence available on the latest generation of commercial equipment: Direct-Total-reflection X-Ray Fluorescence, Sweeping-Total-reflection X-Ray Fluorescence and Vapor Phase Decomposition-Total-reflection X-Ray Fluorescence, are discussed for quantitative analysis of metallic contamination on Si wafers. Direct-Total-reflection X-Ray Fluorescence and Sweeping-Total-reflection X-Ray Fluorescence agrees very well (+/− 20% for light elements, transition metals and heavy metals), but due to a poor surface coverage with Direct-Total-reflection X-Ray Fluorescence, the matching is correct on a whole wafer only for uniform contaminations. Vapor Phase Decomposition-Total-reflection X-Ray Fluorescence might agree with other Total-reflection X-Ray Fluorescence modes only if the collection of contaminants following the oxide decomposition step is 100% completed. This is not achieved for 2 situations: noble metals which plate on bare Si, and solid particles partially digested during the Vapor Phase Decomposition and collection protocol. Furthermore, even if the collection of contaminants is well completed, quantification after Vapor Phase Decomposition depends on the shape of the dried residues and the Total-reflection X-Ray Fluorescence incident angle. With the incident angle selected to maximize the signal to noise ratio for ultra trace applications, i.e. about 0.5 times the Si critical angle, an increase of the quantification by a factor up to 10 is often seen after Vapor Phase Decomposition because of particle-like shape of the metals against film-like shape for the initial distribution. Taking into account advantages and drawbacks of each Total-reflection X-Ray Fluorescence mode, a proposal for the use of Total-reflection X-Ray Fluorescence in advanced Integrated Circuit manufacturing is given and illustrated by practical results from a R&D pilot line and a mass production plant. 相似文献
130.
E′ centers in quartz irradiated by alpha-rays (He+-beam), neutrons, and those produced by gamma-irradiation after crushing as well as in gamma-irradiated silica glass were investigated using cw/pulsed electron spin resonance. Lineshape of E′ centers produced by alpha-rays was similar to that of centers produced by neutrons but different from that of centers produced by gamma-irradiation in silica glass. E′ centers in crushed quartz were localized in amorphous region presumably around dislocations. The obtained phase relaxation times,T 2, are 6.5±0.4 μs (by neutrons), 7.3±0.2 μs (by crushing and gamma-rays) and 18.5±02. μs (in glass) and are compared with the linewidths and the ratios of homogeneous to inhomogeneous broadening obtained from the microwave power dependence. 相似文献