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901.
902.
Yong Zhao Xianliang Sheng Jin Zhai Lei Jiang Chunhe Yang Zhongwei Sun Yongfang Li Daoben Zhu 《Chemphyschem》2007,8(6):856-861
Titanium dioxide (TiO(2)) photoelectrodes with micro/nano hierarchical branched inner channels have been prepared by an electrohydrodynamic (EHD) technique and assembled to form dye-sensitized solar cells (DSSCs). Excellent penetration of ionic-liquid electrolytes and enhanced light harvesting in the longer wavelength region are realized within the composite-structure electrode, thus a better fill factor (ff) of 75.3 % and higher conversion efficiency (eta) of 7.1 % are obtained for viscous ionic-liquid electrolytes compared to pure nanostructured films. Hierarchical branched channels in the photoanodes can efficiently improve the transport properties of redox-active species in viscous electrolytes, which is demonstrated by electrical impedance spectroscopy (EIS). The incident monochromatic photon-to-electron conversion efficiency (IPCE) shows that enhanced light scattering in the composite film is of benefit for light harvesting and thus for solar energy conversion efficiency. 相似文献
903.
A series of novel borates, MM'4(BO3)3 (M = Li, M' = Sr; M = Na, M' = Sr, Ba), have been successfully synthesized by standard solid-state reaction. The crystal structures have been determined from powder X-ray diffraction data. They crystallize in the cubic space group Iad with large lattice parameters: a = 14.95066(5) A for LiSr4(BO3)3, a = 15.14629(6) A for NaSr4(BO3)3, and a = 15.80719(8) A for NaBa4(BO3)3. The structure was built up from 64 small cubic grids, in which the M' atoms took up the corner angle and the BO3 triangles or MO6 cubic octahedra filled in the interspaces. The isolated [BO3]3- anionic groups are perpendicular to each other, distributed along three 100 directions. The anisotropic polarizations were counteracting, forming an isotropic crystal. Sr and Ba atoms were found to be completely soluble in the solid solution NaSr(4-)xBax(BO3)3 (0 < or = x < or = 4). The photoluminescence of samples doped with the ions Eu2+ and Eu3+ was studied, and effective yellow and red emission was detected, respectively. The results are consistent with the crystallographic study. The DTA and TGA curves of them show that they are chemically stable and congruent melting compounds. 相似文献
904.
Piezoelectric diffuse reflectance spectroelectrochemistry (PDRSEC), a new technique of diffuse reflectance spectroelectrochemistry (DRSEC) in combination with electrochemical quartz crystal microbalance (EQCM), was developed to study the electrochemical copolymerization of aniline and o-anthranilic acid in 1.0 mol l(-1) HClO4 and the properties of these copolymers. The DRSEC using an integral sphere was proven to possess a higher optical sensitivity at the unpolished piezoelectric quartz crystal electrodes used than the mirror reflectance spectroelectrochemistry mode. The copolymers grown from the copolymerization bath of different molar fractions of o-anthranilic acid (F1, relative to the total amount of the two monomers) showed intermediate properties between those of the homopolymers, which varied gradually with F1. The swelling/dissolution behavior of the copolymers vs solution pH was traced via the EQCM frequency and resistance signals, and its large dependence on F1 was found and discussed. In a HAc-NaAc buffer solution at pH 5.6, the amount of adsorbed lysozyme was found to be positively correlated with F1, via an EQCM impedance investigation, demonstrating the feasibility of using poly(aniline-co-o-anthranilic acid) as a load-adjustable immobilization matrix for cationic proteins. The novel PDRSEC method proposed is highly recommended for surface electrochemistry studies at relatively rough electrodes. 相似文献
905.
The performance of single-drop microextraction (SDME), coupled with gas chromatography/mass spectrometry, was assessed for the determination of tributyltin compounds in water and solid samples. Experimental parameters impacting the performance of SDME, such as microextraction solvent and sampling and stirring time, were investigated. Analytical results obtained by SDME were compared with those generated by conventional solid phase microextraction (SPME) and liquid-liquid extraction (LLE) for the determination of TBT in PACS-2 sediment certified reference material (CRM). 相似文献
906.
907.
908.
A New Asterosaponin from the Starfish Culcita novaeguineae 总被引:1,自引:0,他引:1
HaiFengTANG YangHuaYI LingLI PengSUN DaZhengZHOU BaoShuLIU 《中国化学快报》2005,16(5):619-622
A new asterosaponin named novaeguinoside A, along with a known saponin, asteronyl pentaglycoside sulfate, was isolated from the starfish Culcita novaeguineae. The new compound was identitied to be sodium 6α-O-{β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-[β-D-quinovopyranosyl}-5α-pregn-9(11)-en-20-one-3β-yl-sulfate by extensive spectral analysis and chemical evidence. 相似文献
909.
910.
Rogelio P. Frutos Isabelle Gallou Diana Reeves Yibo Xu Dhileepkumar Krishnamurthy Chris H. Senanayake 《Tetrahedron letters》2005,46(48):8369-8372
Expedient and practical new methodology for the synthesis of substituted imidazoles was developed to provide a rapid access to a variety of 2-substituted, 1,2-disubstituted and 1,2,4-trisubstituted imidazoles by the direct CuCl-mediated reaction of nitriles with α-amino acetals in an intermolecular as well as intramolecular fashion. 相似文献