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831.
The photosynthetic reaction center is an efficient molecular device for the conversion of light energy to chemical energy. In a previous study, we synthesized the hydrogenase/photosystem I (PSI) complex, in which Ralstonia hydrogenase was linked to the cytoplasmic side of Synechocystis PSI, to modify PSI so that it photoproduced molecular hydrogen (H2). In that study, hydrogenase was fused with a PSI subunit, PsaE, and the resulting hydrogenase-PsaE fusion protein was self-assembled with PsaE-free PSI to give the hydrogenase/PSI complex. Although the hydrogenase/PSI complex served as a direct light-to-H2 conversion system in vitro, the activity was totally suppressed by adding physiological PSI partners, ferredoxin (Fd) and ferredoxin-NADP+-reductase (FNR). In the present study, to establish an H2 photoproduction system in which the activity is not interrupted by Fd and FNR, position 40 of PsaE from Synechocystis sp. PCC6803, corresponding to the Fd-binding site on PSI, was selected and targeted for the cross-linking with cytochrome c3 (cytc3) from Desulfovibrio vulgaris. The covalent adduct of cytc3 and PsaE was stoichiometrically assembled with PsaE-free PSI to form the cytc3/PSI complex. The NADPH production by the cytc3/PSI complex coupled with Fd and FNR decreased to approximately 20% of the original activity, whereas the H2 production by the cytc3/PSI complex coupled with hydrogenase from Desulfovibrio vulgaris was enhanced 7-fold. Consequently, in the simultaneous presence of hydrogenase, Fd, and FNR, the light-driven H2 production by the hydrogenase/cytc3/PSI complex was observed (0.30 pmol Hz/mg chlorophyll/h). These results suggest that the cytc3/PSI complex may produce H2 in vivo. 相似文献
832.
Vieira HS Takahashi JA Gunatilaka AA Boaventura MA 《Magnetic resonance in chemistry : MRC》2006,44(2):146-150
A highly rearranged novel dilactone was the single product isolated from Baeyer-Villiger oxidation of a norketone prepared from grandiflorenic acid, a natural kaurane diterpene. The complete 1H and 13C NMR assignment is presented for this novel compound that showed discrete in vitro antibacterial activity. 相似文献
833.
Tamura R Mizuta M Yabunaka S Fujimoto D Ariga T Okuhara S Ikuma N Takahashi H Tsue H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(13):3515-3527
Both induction and inhibition of "preferential enrichment", an unusual symmetry-breaking enantiomeric-resolution phenomenon observed upon simple recrystallization of a certain kind of racemic crystals from organic solvents, have been successfully achieved by controlling the mode of the polymorphic transition during crystallization with appropriate seed crystals. Such control of the polymorphic transition can be interpreted in terms of a novel phenomenon consisting of 1) the adsorption of prenucleation aggregates, 2) the heterogeneous nucleation and crystal growth of a metastable crystalline form, and 3) the subsequent polymorphic transition into the more stable form; these three processes occur on the same surface of a seed crystal. We refer to this phenomenon as an "epitaxial transition", which has been confirmed by means of in situ attenuated total reflection (ATR) FTIR spectroscopy in solution and the solid state, differential scanning calorimetry (DSC) measurements of the deposited crystals, and X-ray crystallographic analysis of the single crystals or the direct-space approach employing the Monte Carlo method with the Rietveld refinement for the structure solution from the powder X-ray diffraction data. 相似文献
834.
Hisanori Yamane Ryouji Tanimura Junichi Takahashi Masahiko Shimada 《Journal of solid state chemistry》2006,179(1):289-295
New compounds CaY2Ge3O10 and CaY2Ge4O12 were prepared by heating mixtures of CaCO3, Y2O3 and GeO2 at 1200 °C. CaY2Ge3O10 is stable at 1300 °C, while CaY2Ge4O12 decomposes into a melt and CaY2Ge3O10 at approximately 1250 °C. We obtained single crystals of CaY2Ge3O10 by cooling a sample with an initial composition of Ca:Y:Ge=1:2:8 from 1300 °C with a rate of −6 °C/h. The crystal structure of CaY2Ge3O10 was determined by single crystal X-ray diffraction. CaY2Ge3O10 crystallizes in the monoclinic space group P21/c with a=6.0906(8), b=6.8329(8), and β=109.140(3)°, Z=4, and R1=0.029 for I>2σ(I). In the structure of CaY2Ge3O10, Ca and Y atoms are situated disorderly in three 7-fold coordination sites between isolated germanate groups of triple GeO4 tetrahedra, Ge3O10. The structural formula of CaY2Ge3O10 is expressed as (Ca0.45Y0.55)(Ca0.46Y0.54)(Ca0.09Y0.91)Ge3O10. The crystal structure of CaY2Ge4O12 was analyzed by the Rietveld method for the X-ray powder diffraction pattern. CaY2Ge4O12 is isotypic with SrNa2P4O12, crystallizing in the orthorhombic space group P4/nbm, a=9.99282(6), , Z=2, Rwp=0.092, Rp=0.067. CaY2Ge4O12 contains four-membered GeO4-tetrahedra rings, Ge4O12. Eight-fold coordinated square-anitiprism sites and 6-fold octahedral sites between the layers of the Ge4O12 rings are occupied by Y atom and Ca/Y atoms, respectively The structural formula is Y(Ca0.5Y0.5)2Ge4O12. 相似文献
835.
Reactions of the title meso forms, (1R,2S)-1,2-di(2-furyl)-1,2-di(3-guaiazulenyl)ethane (1) and (1R,2S)-1,2-di(3-guaiazulenyl)-1,2-di(2-thienyl)ethane (2), with a two molar amount of TCNE in benzene at 25 °C for 5 h (for 1) and 48 h (for 2) under oxygen give new compounds, 2,2,3,3-tetracyano-4-(2-furyl)-8-isopropyl-6-methyl-1,4-dihydrocyclohepta[c,d]azulene (3) and 2,2,3,3-tetracyano-8-isopropyl-6-methyl-4-(2-thienyl)-1,4-dihydrocyclohepta[c,d]azulene (4), respectively, in 74 and 21% isolated yields. Comparative studies on the above reactions as well as the spectroscopic properties of the unique products 3 and 4, possessing interesting molecular structures, are reported and, further, a plausible reaction pathway for the formation of these products is described. 相似文献
836.
Usui K Hiratsuka A Shiseki K Maruo Y Matsushima T Takahashi K Unuma Y Sakairi K Namatame I Ogawa Y Yokoyama K 《Electrophoresis》2006,27(18):3635-3642
We developed a polymeric 2-DE chip system. The chip consisted of an IEF region, an SDS-PAGE region, a valveless connection port, and a sample introduction port. A "junction structure" as a valveless connection port, which allowed separating and connecting the first- and second-dimensional gels, was fabricated between their regions. A "solution inlet" as a sample introduction port was fabricated to perform the liquid and sample introductions without solution leakage. Simultaneous sample monitoring was performed using the on-chip detection system. The performances of the system were demonstrated using commercially available proteins as a standard specimen and tissue-extracted proteins as the real samples. All procedures were employed without any movement of relocation part. This new 2-D separation system realized improved labor-intensive operations and a reduced experimental time. 相似文献
837.
Crystal orientation of poly(ethylene 2, 6-naphthalate) (PEN) ultrathin films was investigated by the combination of reflection-absorption infrared spectroscopy (RAIR) and grazing incidence X-ray diffraction (GIXD) techniques. It is concluded that the main-chain of PEN molecule in ultrathin film is prone to alignment parallel to the substrate when compared with thicker films. During the formation of α form crystalline, the naphthalene ring, the CO group in molecular chain of PEN as well as the b axis in crystalline tend to take orientation more parallel to the substrate due to the surface-induced effect. However, such an anisotropic structure could not be observed in the bulk PEN. 相似文献
838.
Yuning Liu Takéo Takahashi Marius Tucsnak 《Journal of Mathematical Fluid Mechanics》2012,14(1):177-195
In this paper we study a mathematical model for the dynamics of vesicle membranes in a 3D incompressible viscous fluid. The
system is in the Eulerian formulation, involving the coupling of the incompressible Navier–Stokes system with a phase field
equation. This equation models the vesicle deformations under external flow fields. We prove the local in time existence and
uniqueness of strong solutions. Moreover, we show that, given T > 0, for initial data which are small (in terms of T), these solutions are defined on [0, T] (almost global existence). 相似文献
839.
Keigo?MatsudaEmail author Ryo?Onishi Keiko?Takahashi 《Flow, Turbulence and Combustion》2017,98(1):327-340
This study investigates the influence of gravitational settling of droplets on turbulent clustering and the radar reflectivity factor. A three-dimensional direct numerical simulation (DNS) of particle-laden isotropic turbulence is performed to obtain turbulent droplet clustering data. The turbulent clustering data are then used to calculate the power spectrum of droplet number density fluctuations. The results show that the gravitational settling modulates the power spectrum more significantly as the settling becomes larger. The gravitational settling weakens the intensity of clustering at large wavenumbers for St≤1, whereas it significantly enlarges the intensity for St>1. The dependence on the Taylor-microscale-based Reynolds number is also investigated to discuss the contribution of large-scale eddies to the settling influence. The results show that large-scale eddies modulate the small scale clustering structure of large St droplets. The increment of radar reflectivity factor due to turbulent clustering is estimated from the power spectrum for the case of St=1.0. The result shows that the influence of gravitational settling on the radar reflectivity factor can be significant for the case of large settling velocity droplets. 相似文献
840.
Ryo Onishi Hiromitsu Fuchigami Keigo Matsuda Keiko Takahashi 《Flow, Turbulence and Combustion》2016,97(4):1111-1125
This paper reports on the development of a numerical weather simulation model combined with a detailed spectral-bin cloud microphysics model that can explicitly consider the droplet motion and droplet-atmosphere interactions of sea spray. Sea spray is composed of liquid droplets ejected from the sea surface into the evaporation layer, where it enhances heat as well as momentum exchanges between the atmosphere and the sea. In our study, we analyzed the results of idealized 3D simulations to investigate the impact of sea spray on latent heat exchanges and their consequent impact on boundary layer cloud development. The results show that sea spray enhances the latent heat flux by up to 62 % for the surveyed 10m-height velocities, which ranged from 12 to 42 m/s. They also show that sea spray moistening significantly enhances boundary layer cloud development. 相似文献