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91.
Catalytic Chemistry of Supported Heteropolyacids and Their Applications as Solid Acids to Industrial Processes 总被引:1,自引:0,他引:1
Yuichi Kamiya Toshio Okuhara Makoto Misono Atsuyuki Miyaji Katsuyuki Tsuji Tetsuo Nakajo 《Catalysis Surveys from Asia》2008,12(2):101-113
This article reviews recent research and development of supported heteropolyacid (HPA) catalysts; focusing on the acidic and
catalytic properties. First the basic knowledge of solid HPAs is provided briefly to facilitate understanding of heterogeneous
catalysis of HPAs. Secondly, the structure as well as the physical and chemical properties of supported HPA catalysts is described.
Especially the layer structure of HPA dispersed on the surface of SiO2 and the changes in the surface acidity with the loading level of HPA are discussed. For this purpose, temperature programmed
desorption of benzonitrile devised by Okuhara and Kamiya’s group is useful. This method is capable to assess the surface acidity
of the supported HPA, which controls the catalytic activity for the reactions proceeding by surface-type catalysis. Then,
two new industrial processes developed by Showa Denko K. K. are described; (i) production of ethyl acetate from ethylene and
acetic acid and (ii) oxidation of ethylene to acetic acid. Supported HPA catalysts are utilized for both processes, which
were recently much improved by finely controlling the catalysts and reaction conditions. 相似文献
92.
Two new oxindole alkaloids, rankiniridine (1) and humanteniridine (2), having a nitrogen-carbon linkage between a humantenine-type monoterpenoid indole alkaloid and a monoterpene unit with an iridoid skeleton, were isolated from Gelsemium rankinii and Gelsemium elegans, respectively. 相似文献
93.
Two novel indole alkaloids having unusual skeletons were isolated from the aerial part of Yunnan Kopsia arborea. Kopsiyunnanine A (1) is a new class of bisindole alkaloid composed of vallesiachotamine (modified Corynanthe-type) and Aspidospermatan-type alkaloids. Kopsiyunnanine B (2) is a new Corynanthe-type oxindole alkaloid rearranged by D ring rotation. 相似文献
94.
Hirofumi Aritani Osamu Fukuda Atsuyuki Miyaji Sadao Hasegawa 《Applied Surface Science》2001,180(3-4):261-269
To obtain structural information of the molybdenum species supported on silica–alumina (SAH-1), as a unique catalyst for propene metathesis, Mo LIII-edge XANES and ESR spectroscopies were applied to characterize. The molybdenum species on SAH-1 are partly reduced to form Mo5+ ions in contact with propene even at room temperature (293 K), and the reduced ions increased with an increase in reaction temperature up to 473 K. From the results of Mo LIII-edge XANES, unique polymolybdate species with tetrahedral and octahedral structures are dominant in MoO3/SAH-1 before the reaction. After the metathesis reaction, Mo ions are partly reduced to form metathesis active species and a ratio of tetrahedral structure decreases. This unique redox behavior of Mo ions is brought about by SAH-1 support. It is suggested that the metathesis active species of MoO3/SAH-1 are not highly dispersed Mo ions in reduced state but are in poorly crystallized polymolybdate species, which can be partly reduced in contact with propene even at room temperature. 相似文献
95.
K Kogure O Okuda C Nakamura K Hayashi M Ueno 《Chemical & pharmaceutical bulletin》1999,47(8):1117-1120
To obtain information about the factors governing spontaneous inter-membrane protein transfer, we examined the effects of incorporation of various amphiphilic compounds in dimyristoylphosphatidylcholine (DMPC) liposomes on protein transfer from influenza virus-infected cells to the liposomes, and analyzed the physical properties of these liposome membranes. The incorporation of amphiphilic compounds, negatively charged dicetylphosphate (DCP), dipalmitoylphosphatidylserine (DPPS) or positively charged dimethyldipalmitoylammonium (DMDPA), into DMPC liposomal membranes enhanced protein transfer. The liposomes containing DCP, DPPS or DMDPA were unaffected by osmotic shock caused by external addition of glucose, suggesting a decrease in lipid packing in the liposomal membranes. Furthermore, calorimetric study of these liposomes showed that a phase separation occurred partially in the liposomal membranes. Accordingly, the membranes of DMPC liposomes containing DCP, DPPS and DMDPA should be distorted due to the coexistence of two phases, gel and liquid crystalline, in the membranes. Consequently, the membrane distortion could be responsible for the enhancement effects of the amphiphiles on the inter-membrane protein transfer from influenza virus-infected cells to the liposomes. 相似文献
96.
Proposal of a semiconductor ring laser gyroscope 总被引:1,自引:0,他引:1
Taguchi Kozo Fukushima Kaname Ishitani Atsuyuki Ikeda Masahiro 《Optical and Quantum Electronics》1999,31(12):1219-1226
We proposed a novel optical inertial rotation sensor using a semiconductor ring laser (SRL). The frequency difference between the two counter propagating oscillation frequencies was automatically generated in a mechanically rotated SRL, which consisted of a pig-tailed laser diode amplifier module. And the Sagnac frequency shift could be detected at the first time as a beat note by the terminal voltage change of the SRL without branching the circulating optical power. These experimental results verify that an SRL operates as an optical inertial rotation sensor based on the Sagnac effect. 相似文献
97.
Kentaro Wada Noriyuki Kogure Mariko Kitajima Hiromitsu Takayama 《Tetrahedron letters》2019,60(2):187-190
The shortest asymmetric total synthesis of lycopodine (3) and the first asymmetric total synthesis of flabelliformine (4) were accomplished by a strategy that features a cascade cyclization of linear substrate (5) to construct tetracyclic structure (6). 相似文献
98.
A simplified method for estimating the soil thrust exerted by a tracked vehicle is proposed. The relationship between the soil shear torque curve (shear torque-deformation curve) obtained from ring shear test and the thrust curve (soil thrust-slip ratio curve) of a tracked vehicle is analyzed and it is shown that there is a transformation law between these curves. A simplified analytical method for estimating the soil thrust exerted by a tracked vehicle is developed by using the above-mentioned transformation law. Soil thrust can be estimated by using the soil shear torque curve, shear ring and vehicle parameters. It is experimentally confirmed that the soil thrust can be easily estimated by using the proposed method. 相似文献
99.
Masao Doyama Yoshiaki Kogure Toshikazu Kurihara Ryuichiro Oshima 《Applied Surface Science》2006,252(9):3126-3131
Immediate and near-future plans for transmission positron microscopes being built at KEK, Tsukuba, Japan, are described. The characteristic feature of this project is remolding a commercial electron microscope to a positron microscope. A point source of electrons kept at a negative high voltage is changed to a point source of positrons kept at a high positive voltage. Positional resolution of transmission microscopes should be theoretically the same as electron microscopes. Positron microscopes utilizing trapping of positrons have always positional ambiguity due to the diffusion of positrons. 相似文献
100.
Sasaki K Kogure K Chaki S Nakamura Y Moriguchi R Hamada H Danev R Nagayama K Futaki S Harashima H 《Analytical and bioanalytical chemistry》2008,391(8):2717-2727
We previously reported that transferrin (Tf)-modified liposomes (Tf-L) additionally modified with a cholesterylated pH-sensitive
fusogenic peptide (Chol-GALA) can release an encapsulated aqueous phase marker to cytosol via endosomal membrane fusion. However,
further obstacles need to be overcome to bring the Tf-L to the level of a viral-like gene delivery system. In this study,
we developed a novel packaging method to encapsulate condensed plasmid DNA into PEgylated Tf-L (Tf-PEG-L) to form a core–shell-type
nanoparticle. The most difficult challenge was to provide a mechanism of escape for the condensed core from endosome to cytosol
in the presence of polyethylene glycol (PEG). We hypothesized that a membrane-introduced Chol-GALA and a PEgylated GALA would
interact synergistically to induce membrane fusion between liposome and endosome. By simultaneously incorporating Chol-GALA
into the membrane of Tf-PEG-L and GALA at tips of PEG chains, a condensed core was released into cytosol, and transfection
acitivty increased 100-fold. We concluded that topological control was responsible for the synergistic effect of GALA derivatives
introduced on Tf-PEG-L.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Kentaro Sasaki and Kentaro Kogure contributed equally to this work. 相似文献