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61.
Prof. Dr. Yoshihiko Yamamoto Kei-ichiro Nishimura Dr. Shota Mori Dr. Masatoshi Shibuya 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(20):5586-5589
In the presence of a cationic Ru catalyst, 1,6-diynes bearing a terminal styryl moiety underwent [2+2+2] cyclization to produce dehydrobiphenylenes fused with a five-membered ring. Although the cycloadducts were unstable toward purification, their one-pot iodine-mediated ring expansion successfully afforded unprecedented bridged ketone products containing a benzo-fused bicyclo[3.2.1] framework. 相似文献
62.
We summarized our recent optical studies on semiconductor nanoparticle (NP) based hybrid nanostructures: isolated CdSe NPs on Au substrates, close-packed CdSe NP monolayers on Au substrates, and close-packed monolayers of mixed CdSe/Au NPs. Luminescence properties of semiconductor-metal hybrid nanostructures were studied by space-resolved optical imaging spectroscopy and time-resolved luminescence spectroscopy. The luminescence spectra and dynamics of isolated and assembled NPs depend on the local environments. We discuss exciton-plasmon interactions in semiconductor-metal hybrid nanostructures. 相似文献
63.
We report the first observation of trions (charged excitons), three-particle bound states consisting of one electron and two holes, in hole-doped carbon nanotubes at room temperature. When p-type dopants are added to carbon nanotube solutions, the photoluminescence and absorption peaks of the trions appear far below the E11 bright exciton peak, regardless of the dopant species. The unexpectedly large energy separation between the bright excitons and the trions is attributed to the strong electron-hole exchange interaction in carbon nanotubes. 相似文献
64.
We study the effects of noise intensity fluctuations on the stationary and dynamical properties of an overdamped Langevin model with a bistable potential and external periodical driving force. We calculated the stationary distributions, mean-first passage time (MFPT) and the spectral amplification factor using a complete set expansion (CSE) technique. We found resonant activation (RA) and stochastic resonance (SR) phenomena in the system under investigation. Moreover, the strength of RA and SR phenomena exhibit non-monotonic behavior and their trade-off relation as a function of the squared variation coefficient of the noise intensity process. The reliability of CSE is verified with Monte Carlo simulations. 相似文献
65.
Kitajima K Yoshikawa T Seo Y Ohno Y Yano Y Miki A Kanda T Kanata N Azuma T Sugimura K 《Magnetic resonance imaging》2011,29(4):579-583
Budd-Chiari syndrome (BCS) is a rare disorder caused by the obstruction of hepatic venous outflow, leading to sinusoidal congestion, ischemic injury to liver cells and portal hypertension. Long-term survival largely depends on whether hepatocellular carcinoma occurs. A recently available liver-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA), reportedly has high diagnostic capability for detection of malignant liver tumors. However, there has been no report of the sue of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for BCS. We present a case of chronic BCS who underwent both gadopentetate dimeglumine (Gd-DTPA) and Gd-EOB-DTPA-enhanced MRI. Hepatic congestion and edema were seen as slightly hypointense areas on Gd-EOB-DTPA-enhanced hepatobiliary-phase images, although these areas were observed as slightly hyperintense on previously obtained Gd-DTPA-enhanced delayed-phase image. Reduced uptake of Gd-EOB-DTPA by hepatocytes in the region of congestion or edema may account for this difference, which should be recognized in image interpretations. 相似文献
66.
Yoshihiko Yamaura 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(18):7168-7183
The present paper shows Hölder continuity of discrete Morse flows to a regularized Alt–Caffarelli variational functional generating free boundaries; the continuity is uniform with respect to the discrete Morse flows and the regularizations. The uniformity enables to construct Morse flows to the Alt–Caffarelli functional, which shall be dealt with in another paper. 相似文献
67.
Yoko Aomura Yoshihiko KobayashiYuzuru Miyazawa Hideharu Shimizu 《Journal of chromatography. A》2010,1217(11):1838-1844
Rapid analysis of trace permanent gas impurities in high purity ammonia gas for the microelectronics industry is described, using a gas chromatograph equipped with a phtoionization detector. Our system incorporates a reactive precolumn in combination with the analytical column to remove the ammonia matrix peak that otherwise would complicate the measurements due to baseline fluctuations and loss of analytes. The performance of 21 precolumn candidate materials was evaluated. Copper sulfate pentahydrate (CuSO4·5H2O) was shown to selectively react with ammonia at room temperature and atmospheric column pressures, without affecting the hydrogen, oxygen, nitrogen, methane or carbon monoxide peak areas. To prevent loss of trace carbon dioxide, an additional boron trioxide reactant layer was inserted above the copper sulfate pentahydrate bed in the reactive precolumn. Using the combined materials, calibration curves for carbon dioxide proved to be equivalent in both ammonia and helium matrix gases. These curves were equivalent in both matrix gases. The quantitative performance of the system was also evaluated. Peak repeatabilities, based on eight injections, were in the range of 4.1–8.2% relative standard deviation; and detection limits were 6.9 ppb for H2, 1.8 ppb for O2, 1.6 ppb for N2, 6.4 ppb for CH4, 13 ppb for CO, and 5.4 ppb for CO2. 相似文献
68.
T. Oishi M. Goto Y. Pihosh A. Kasahara M. Tosa 《Applied Physics A: Materials Science & Processing》2005,81(3):507-510
A microdot pattern of multiple organic molecules was prepared. Fluorescent molecules, which absorb visible light, were added to a commercial ultraviolet photopolymerization polymer solution and the polymer solution was polymerized by irradiating with nanosecond pulsed visible laser light. The size and the shape of the polymerized dots differed with the irradiation condition and the kind of the added molecules. Based on these results, a microdot pattern of multiple organic molecules was prepared by repeating a micropatterning process with the molecules. PACS 82.50.Hp; 81.65.Cf; 81.05.Lg 相似文献
69.
Yoshihiko Konno 《Journal of multivariate analysis》2007,98(2):295-316
In this paper the problem of estimating a covariance matrix parametrized by an irreducible symmetric cone in a decision-theoretic set-up is considered. By making use of some results developed in a theory of finite-dimensional Euclidean simple Jordan algebras, Bartlett's decomposition and an unbiased risk estimate formula for a general family of Wishart distributions on the irreducible symmetric cone are derived; these results lead to an extension of Stein's general technique for derivation of minimax estimators for a real normal covariance matrix. Specification of the results to the multivariate normal models with covariances which are parametrized by complex, quaternion, and Lorentz types gives minimax estimators for each model. 相似文献
70.
Yoshihiko Yamamoto Hideyuki Takagishi Kenji Itoh 《Journal of the American Chemical Society》2002,124(1):28-29
In the presence of 10 mol % Cp*Ru(cod)Cl, 1,6-diynes with a tertiary center at 4-position reacted with various isothiocyanates at their C=S double bond to afford bicyclic (2H)-thiopyranimines in 35-88% yields. The (2H)-thiopyran structure was unequivocally determined by X-ray analysis. The cycloaddition of carbon disulfide with a diyne similarly gave the expected bicyclic dithiopyrone in 50% yield. 相似文献