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61.
Toshihiko Ueki Matsumi Doe Yoshiki Morimoto Takamasa Kinoshita Rika Tanaka Kazuo Yoshihara 《Journal of heterocyclic chemistry》2001,38(1):165-172
Hyperolactones A ( 1 ) and C ( 3 ) have been synthesized starting from (S)‐malic acid by a straightforward route. The unique spirolactone skeleton was efficiently constructed by one‐pot reaction as a key step. The absolute stereochemistry of hyperolactones was unambiguously established by this synthesis. 相似文献
62.
63.
Teppei Yoshioka Md Zahangir Alam Tomonari Ogata Takamasa Nonaka Seiji Kurihara 《Liquid crystals》2004,31(9):1285-1291
Several chiral azobenzene compounds having different chiral substituents were synthesized. A cholesteric phase was induced by mixing each chiral azobenzene compound with a host non-chiral nematic liquid crystal (E44). The helical twisting power (HTP) as well as the change in HTP by trans-cis photoisomerization of the chiral azobenzene compound was dependent on the structure of the chiral substituents. A compensated nematic phase was induced by combination of E44, a chiral azobenzene compound and a non-photochromic chiral compound. Reversible switching between the compensated nematic phase and cholesteric phase was brought about by trans-cis photoisomerization of the chiral azobenzene compound in the liquid crystalline systems. An azobenzene compound substituted with a menthyl group showed the highest efficiency as the trigger for the switching; this efficiency was related to the compactness of the chiral group substituted within the azobenzene core moiety. 相似文献
64.
Measurement of diameter of metal cylinders using a sinusoidally vibrating interference pattern 总被引:1,自引:0,他引:1
A method for measuring external diameters of metal cylinders is proposed in which a sinusoidally vibrating interference pattern (SVIP) of 100-μm period is used as an exact scale. Lights from the end-points of a metal cylinder are extracted with a spatial filtering in an imaging system to form a cross-sectional image of the metal cylinder. On the image a sinusoidally phase-modulated signal owing to the SVIP is detected with a CCD image sensor to measure the phases of the SVIP at the two end-points of the cylinder. The coordinates of the two end-points are obtained from the phases at the two end-points, the phase distribution of the SVIP, and the coordinates of the pixels of the CCD image sensor. Metal cylinder diameters of 7.99, 8.00, and 9.00 mm are measured along their length directions with an error less than 1 μm. 相似文献
65.
Spectroscopic measurements of excited particles in a N2 gas RF plasma-assisted carbon laser ablation
M.A. Bratescu N. Sakura D. Yamaoka Y. Sakai H. Sugawara Y. Suda 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1083-1088
In this work, we investigated a carbon plasma plume produced by laser ablation of a graphite target in a nitrogen gas environment. The spatial distributions of C and N atoms were measured by time-resolved absorption spectroscopy. The spatial distributions of the relative densities of CN radicals, C2, and C3 molecules were measured using time-resolved emission spectroscopy. We determined that nitrogen gas produced an increase in carbon atom and molecule densities in the ablation plume. It was observed that the addition of RF plasma to the plume increased the CN radicals and C atom densities, and decreased the C2 and C3 molecule densities. The RF plasma changed the evolution of various fractional species of C, N, CN, C2, and C3 in the ablation plume. The chemical reactions with and without RF plasma were explained using the evolution and density of the fractional species of C, N, CN, C2, and C3in the plume. PACS 52.38.Mf; 42.62.Fi; 33.20.-t; 81.05.Uw 相似文献
66.
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68.
Kouji Kuramochi Ryo Takeuchi Masaharu Takemura Kengo Sakaguchi Susumu Kobayashi Fumio Sugawara 《Tetrahedron》2006,62(34):8006-8015
Synthesis of plakevulin A and structure-activity relationships of its related compounds against DNA polymerases is described. We have achieved a total synthesis and revised the structure of plakevulin A. Several analogues including untenone A, manzamenone A, and optically active plakevulin A, were prepared and tested with an enzyme inhibition assay for mammalian DNA polymerases. The effect of the methyl ester moiety, and the substituents at the 1- and 4-positions of plakevulin A on DNA polymerase activities are discussed. 相似文献
69.
In this paper the horizontal layer of clear ice sticking to the substrate is melted by comparatively short wave radiation similar to solar radiation for the purpose of removing ice from the surface of the material subject to atmospheric icing. The radiating source used for melting is 300 wattages halogen lamps whose color temperature is 3200K at 100 voltages. From the present investigation, a typical phenomenon of backmelting is observed clearly and it can be found that the predicted results including the melting rate of upper and lower layers which are melted by radiant energy impinged on or penetrated the ice layer are in good agreement with the experimental results.
Nomenclature av monochromatic absorption coefficient - A transmission (= q r + {hi}/qro) - cp specific heat - Ebv monochromatic emissive power - hD mass transfer coefficient - hi initial thickness of ice layer - hm thickness of substrate - Li latent heat of melting - Lw latent heat of evaporation or condensation - heat flux absorbed at surface of substrate - qr0 radiant heat flux impinged onto ice or free surface - q r + {y} forward radiant heat flux - q r – {y} backward radiant heat flux - S1 thickness of upper melt layer - S2 thickness of lower melt layer - S'2 distance from free surface to bottom surface of ice layer - t time - T temperature - T1 temperature of air-water or air-ice interface - T2 temperature of substrate surface - T3 temperature of back side surface of substrate - Tb temperature of radiating source - Ti temperature in ice layer - Tw1 temperature in upper melt layer - Tw2 temperature in lower melt layer - T environmental temperature - Ww saturated vapor concentration at free surface - Wt8 vapor concentration at environment - y distance from free or ice surface - y grid size of water or ice - ym grid size of substrate Greek symbols heat transfer coefficient - spectral absorptivity - t total absorptivity - i thermal diffusivity of ice - m thermal diffusivity of substrate - w thermal diffusivity of water - i thermal conductivity of ice - m thermal conductivity of substrate - w thermal conductivity of water - wavelength - av densitiy of air-vapor mixture - i density of ice - Stefan-Boltzman constant 相似文献
Aufschmelzen einer waagerechten Klareisschicht durch Strahlung
Zusammenfassung Eine waagerechte Klareisschicht, die auf einer Unterlage aufgefroren war, wurde durch kurzwellige Strahlung, Ähnlich der Sonnenstrahlung, zum Schmelzen gebracht, um die Entfernung von Eis nach atmosphÄrischer Vereisung zu untersuchen. Die Strahlungsquelle war eine 300 Watt-Halogenlampe mit einer Farbtemperatur von 3200 Kelvin bei 100 Volt. Als typische Erscheinung wurde ein Rückseiten-Schmelzen gefunden, im übrigen sind die vorausberechneten Schmelzraten an der Ober- und der Unterseite durch aufgenommene oder durchgelassene Strahlungsenergie in guter übereinstimmung mit den Messungen.
Nomenclature av monochromatic absorption coefficient - A transmission (= q r + {hi}/qro) - cp specific heat - Ebv monochromatic emissive power - hD mass transfer coefficient - hi initial thickness of ice layer - hm thickness of substrate - Li latent heat of melting - Lw latent heat of evaporation or condensation - heat flux absorbed at surface of substrate - qr0 radiant heat flux impinged onto ice or free surface - q r + {y} forward radiant heat flux - q r – {y} backward radiant heat flux - S1 thickness of upper melt layer - S2 thickness of lower melt layer - S'2 distance from free surface to bottom surface of ice layer - t time - T temperature - T1 temperature of air-water or air-ice interface - T2 temperature of substrate surface - T3 temperature of back side surface of substrate - Tb temperature of radiating source - Ti temperature in ice layer - Tw1 temperature in upper melt layer - Tw2 temperature in lower melt layer - T environmental temperature - Ww saturated vapor concentration at free surface - Wt8 vapor concentration at environment - y distance from free or ice surface - y grid size of water or ice - ym grid size of substrate Greek symbols heat transfer coefficient - spectral absorptivity - t total absorptivity - i thermal diffusivity of ice - m thermal diffusivity of substrate - w thermal diffusivity of water - i thermal conductivity of ice - m thermal conductivity of substrate - w thermal conductivity of water - wavelength - av densitiy of air-vapor mixture - i density of ice - Stefan-Boltzman constant 相似文献
70.
An analytical study is reported of melting of a snow layer in an aqueous solution. A diffusion-controlled analytical model was proposed to the melting under an ideal condition that an aqueous solution was instantaneously filled up by a snow layer at the same temperature as the solution. The analytical results gave a qualitative prediction of the experimental results of the melting of snow layers suddenly immersed in a calcium chloride aqueous solution. The temperature in a melting system decreased rapidly during the melting process. The melting was complete within a few seconds, which denoted a thermodynamic equilibrium. When the initial temperatureT i and the initial porosity of snow ? i were the same, the initial concentrationC mi in the solution strongly affected both the decrease in temperature in the melting system and the melting mass per unit volume of snowM. WhenC mi andT i were the same, the maximum melting mass per unit volume of snowM max was not largely affected by snow particle diameters. A figure was presented for the relationM max?T i,C mi, and ? i , and also a relationship was presented to easily predict the non-dimensional maximum melting massM max * . 相似文献