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81.
Norio Sakai 《Tetrahedron letters》2006,47(8):1261-1265
A catalytic amount of ytterbium triflate (Yb(OTf)3) promotes the cyclization of an N-silylenamine with in situ generated 2-methylene-1,3-cyclohexanedione and 2-methylenecyclohexanone to produce the corresponding 2,3-disubstituted 7,8-dihydroquinolin-5-one and 5,6,7,8-tetrahydroquinolin-5-one in moderate to good yields. A one-pot conversion of 7,8-dihydroquinolin-5-one to the quinoline derivative also proceeded in good yield. 相似文献
82.
Moriya K. Yamada T. Sakai K. Yano S. Baluja S. Matsuo T. Pritz I. Vysochanskii Y. M. 《Journal of Thermal Analysis and Calorimetry》2002,70(2):321-328
Heat capacities of the Pb2xSn2(1-x)P2Se6 crystals (x=0, 0.098, 0.251, 0.402 and 1.0) were measured using an adiabatic calorimeter at temperatures between 10 and 350 K. In the
crystal of x=0, two heat capacity anomalies corresponding to the ferroelectric commensurate - intermediate incommensurate(C-IC) phase
transition temperature T
i, and the incommensurate - paraelectric (IC-N) phase transition temperature T
c, were observed at 193.24±0.10 and 220.07±0.15 K, respectively. The phase transition temperatures decreased with an increase
in Pb2+ concentration. The anomaly at Ti disappeared at x=0.251 in the mixed systems of the Pb2xSn2(1-x)P2Se6. In the crystal of Pb2P2Se6 (x=1.0), no phase transition was observed. The normal heat capacities for the mixed crystals were determined by least squares
fitting of the Debye and Einstein functions to the experimental data. The anomalous heat capacities gave the phase transition
entropies of 8.5 and 1.5 J mol-1 K-1 for x=0. The large transition entropies are consistent with an order-disorder mechanism in the ferroelectric-paraelectric phase
transitions in x=0.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
83.
Hiroyoshi Kamogawa Tsuyoshi Sakai Hirohito Sohma 《Journal of polymer science. Part A, Polymer chemistry》1988,26(5):1335-1341
Schiff base (SB) monomers of vinylbenzaldehyde with functional amines were prepared. Copolymers of SB monomers with N-vinyl-2-pyrrolidone soluble in aqueous solutions were obtained in most cases. However, p-aminobenzenesulfonamide monomer resulted in gel formation. Thus, the reaction of vinylbenzaldehyde copolymer with the sulfonamide was used instead of the copolymerization. The hydrolytic behaviors of SB monomers and copolymers to liberate respective amines were structure dependent and, for most copolymers, the rates were lower than those of the corresponding monomers. 相似文献
84.
Geometry optimizations at the UHF/6-31G* and UMP2/6-31G* levels of theory were performed to find the transition state in the interconversion between norbornadiene (N) and quadricyclane (Q) radical cations. Two transition structures, TS+·1 and TS+·2, were obtained which have C1 and C2 symmetry, respectively. Vibrational analysis at the UHF and UMP2 levels of theory and IRC calculation showed that TS+·1 is the true transition state connecting N+· and Q+·, while TS+·2 is a second order saddle point. 相似文献
85.
Sano S Takehisa T Ogawa S Yokoyama K Nagao Y 《Chemical & pharmaceutical bulletin》2002,50(9):1300-1302
Tetrasubstituted (Z)-alkenes were readily prepared through the Horner-Wadsworth-Emmons reactions of methyl 2-[bis(2,2,2-trifluoroethyl)phosphono]propionate with aryl alkyl ketones by employing Sn(OSO(2)CF(3))(2) and N-ethylpiperidine. 相似文献
86.
Yagi Kiyohito Hamada Kenji Hlrata Kazumasa Miyamoto Kazuihisa Miura Yoshiharu Akano Tohru Fukatu Kiyomi Ikuta Yoshiaki Nakamura Hiroshi K. 《Applied biochemistry and biotechnology》1994,(1):225-232
A marine green alga,Chlamydomonas sp. strain MGA161 was cultivated under illumination of red and white lights. The growth rate under red light illumination
was almost the same as that in the basic conditions under white light illumination, but red light-grown cells accumulated
almost twice as much starch as white light-grown cells. Although there was a slight decrease in carbonic anhydrase activity,
red light-illuminated cells had almost 2.3 times the fructose-l,6-diphos-phatase activity of white light-illuminated cells.
Red light might stimulate starch accumulation by increasing the amounts of enzymes related to carbon fixation through the
phytochrome system. Cells grown under red light degraded 1.6 times as much starch and produced 1.7 times as much hydrogen
and 1.6 times as much ethanol compared with cells grown under white light during 12 h of dark anaerobic fermentation. 相似文献
87.
Numata M Asai M Kaneko K Bae AH Hasegawa T Sakurai K Shinkai S 《Journal of the American Chemical Society》2005,127(16):5875-5884
We have found that single-chain schizophyllan and curdlan (s-SPG and s-curdlan, respectively) can dissolve as-grown and cut single-walled carbon nanotubes (ag-SWNTs and c-SWNTs, respectively) in aqueous solution. The vis-NIR spectra of the composites suggest that c-SWNTs are dissolved as a bundle, whereas ag-SWNTs exist as one or only a few pieces in the tubular hollow constructed by the helical structure inherent to these beta-1,3-glucans. EDX and CLSM measurements and TEM observation established that the distribution map of these polysaccharides overlaps well with the image of SWNTs, indicating that these two components form a composite. Very interestingly, when c-SWNTs were dissolved with the aid of s-SPG or s-curdlan in water, a clear periodical structure with inclined stripes, as detected by AFM, appeared on the fibrous composite surface. Because this periodical structure has never been recognized for the composites with other water-soluble polymers, one can regard that s-SPG or s-curdlan wraps c-SWNTs constructing a helically twined structure. High-resolution TEM observation of an ag-SWNTs/s-SPG composite gave a clearer image in that two s-SPG chains twine one ag-SWNT and the helical motif is right-handed. When this sample was subjected to the AFM measurement, the composite showed the 2-3 nm height. This height implies that one piece of ag-SWNT is included in the s-SPGs helical structure. As a summary, it has been established that beta-1,3-glucans such as s-SPG and s-curdlan not only dissolve SWNTs but also create a novel superstructure on the surface. 相似文献
88.
Thermodynamically stable vesicle formation from glycolipid biosurfactant sponge phase 总被引:3,自引:0,他引:3
Imura T Yanagishita H Ohira J Sakai H Abe M Kitamoto D 《Colloids and surfaces. B, Biointerfaces》2005,43(2):115-121
Thermodynamically stable vesicle (L(alpha1)) formation from glycolipid biosurfactant sponge phase (L(3)) and its mechanism were investigated using a "natural" biocompatible mannosyl-erythritol lipid-A (MEL-A)/L-alpha-dilauroylphosphatidylcholine (DLPC) mixture by varying the composition. The trapping efficiency for calcein and turbidity measurements clearly indicated the existence of three regions: while the trapping efficiencies of the mixed MEL-A/DLPC assemblies at the compositions with X(DLPC)< or =0.1 or X(DLPC)> or =0.8 were almost zero, the mixed assemblies at the compositions with 0.1 or =0.8 were multilamellar vesicles (L(alpha)) with diameter from 2 to 10 microm. Meanwhile, dynamic light scattering (DLS) measurement revealed that the average size of the vesicles at the composition of X(DLPC)=0.3 was 633.2 nm, which is remarkably small compared to other compositions. Moreover, the mixed vesicle solution at the composition of X(DLPC)=0.3 was slightly bluish and turbid and kept its dispersion stability at 25 degrees C for more than 3 months, indicating the formation of a thermodynamically stable vesicle (L(alpha1)). These results exhibited the formation of a thermodynamically stable vesicle (L(alpha1)) with a high dispersibility from the MEL-A/DLPC mixture. The asymmetric distribution of MEL-A and DLPC in the two vesicle monolayers caused by the difference in geometrical structures is very likely to have changed their self-assembled structure from a sponge phase (L(3)) to a thermodynamically stable vesicle (L(alpha1)). 相似文献
89.
90.
We report on a spreading behavior of phospholipid membranes that arise from a lump of phospholipid (a lipid source) on topographically patterned substrates immersed in an aqueous solution. Microgrooves with well-defined shapes were prepared on Si111 surfaces by anisotropic etching in an alkaline solution. A spreading front that consists of membrane lobes and a single lipid bilayer was observed on the patterned silicon substrates by utilizing fluorescence interference contrast (FLIC) microscopy. FLIC images indicate that the membrane lobes span the microgrooves, while the underlying single lipid bilayer spread along the surface of the microgrooves. In fact, fluorescent polystyrene nanoparticles could be encapsulated in the microgrooves that were completely covered with the membrane lobes. The groove-spanning behavior of membrane lobes is discussed in terms of a balance between adhesion and bending energies of lipid bilayers. 相似文献