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921.
Q. Ren D. Xu Y.T. Chow Z.H. Lü C.B. Ma G.H. Zhang H.P. Chan P.L. Chu 《Applied Physics A: Materials Science & Processing》2003,76(2):183-186
Composite thin films of PbTiO3 nanocrystals and high-transparency PEKc polymer for applications in electro-optical devices were prepared using the spin
coating technique. The size of the PbTiO3 nanocrystals was estimated to be 30–40 nm using a transmission electron microscope. The transmission technique, a simple
method for measuring the electro-optic coefficients of poled composite polymer films was developed. The electro-optic coefficient
γ33 of poled PbTiO3/PEKc composite polymer films was measured to be 18.34 pm V-1 at 633 nm under room temperature. The index at 633 nm and the dielectric constant at 100 kHz under room temperature were
determined to be 1.65248 and 7.32, respectively. The figure of merit F2=n7γ2/ε was estimated to be 1546, showing very good electro-optical properties.
Received: 5 February 2002 / Accepted: 12 March 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: +852/2788-7791, E-mail: eeytc@cityu.edu.hk 相似文献
922.
Stereoselectivity of nitrile oxide cycloadditions to chiral allylic fluorides: experiment and theory
Prakesch M Grée D Grée R Carter J Washington I Houk KN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(22):5664-5672
The cycloadditions of nitrile oxides with new and previously studied allylic fluorides were examined. The 1,3-dipolar cycloaddition reactions were also investigated theoretically with density functional theory (B3LYP) based transition-state modelling. The predictions provided reasonable agreement with experiment, indicating that both steric and electronic effects have important influences on the stereoselectivities of these reactions. 相似文献
923.
The crystal structure of a streptomycin binding RNA aptamer displays a novel bipartite fold able to clamp the antibiotic. In view of the recent findings that metabolites directly control mRNA translation, we might expect that similar structures exist in natural RNAs. 相似文献
924.
925.
Scarpellini M Neves A Hörner R Bortoluzzi AJ Szpoganics B Zucco C Nome Silva RA Drago V Mangrich AS Ortiz WA Passos WA de Oliveira MC Terenzi H 《Inorganic chemistry》2003,42(25):8353-8365
The tridentate Schiff base [(2-(imidazol-4-yl)ethyl)(1-methylimidazol-2-yl)methyl)imine (HISMIMI) and its reduced form HISMIMA were synthesized and characterized, as well their mononuclear cis-dihalo copper(II) complexes 1 and 2, respectively. In addition, the dinuclear [CuII(mu-OH)2CuII](2+) complexes (3) and (4) obtained from complexes 1 and 2, respectively, were also isolated and characterized by several physicochemical techniques, including magnetochemistry, electrochemistry, and EPR and UV-vis spectroscopies. The crystal structures of 1 and 2 were determined by X-ray crystallography and revealed two neutral complexes with their tridentate chelate ligands meridionally coordinated. Completing the coordination spheres of the square-pyramidal structures, a chloride ion occupies the apical position and another is bonded in the basal plane. In addition, complexes 1 and 2 were investigated by infrared, electronic, and EPR spectroscopies, cyclic voltammetry, and potentiometric equilibrium studies. The hydrolytic activity on phosphate diester cleavage of 1 and 2 was investigated utilizing 2,4-BDNPP as substrate. These experiments were carried out at 50 degrees C, and the data treatment was based on the Michaelis-Menten approach, giving the following kinetic parameters (complex 1/complex 2): vmax (mol L(-1) s(-1))=16.4x10(-9)/7.02x10(-9); KM (mol L(-1))=17.3x10(-3)/3.03x10(-3); kcat (s(-1))=3.28x10(-4)/1.40x10(-4). Complex 1 effectively promoted the hydrolytic cleavage of double-strand plasmid DNA under anaerobic and aerobic conditions, with a rate constant of 0.28 h(-1) for the decrease of form I, which represents about a 10(7) rate increase compared with the estimated uncatalyzed rate of hydrolysis. 相似文献
926.
A simple and sensitive high-performance liquid chromatography method is developed for the simultaneous determination of (3,4-dihydroxyphenyl)-lactic acid (Dhpl) and protocatechuic aldehyde (Pal) in rat serum after oral administration of Radix Salviae miltiorrhizae extract. Serum samples are acidified with hydrochloric acid and extracted with ethyl acetate. Analysis of the extract is performed on a reversed-phase column and a mobile phase of 0.02% phosphoric acid-acetonitrile (91:9, v/v) with UV detection at 280 nm. Standard curves are linear in the range of 1.47-456.96 microg/mL for Dhpl and 0.124-7.936 microg/mL for Pal. For both regression coefficients, r(2) is greater than 0.993. Mean recovery is determined to be 75.23% and 84.06%, respectively, by analyzing serum standard containing 7.14, 57.12, and 228.48 microg/mL of Dhpl and 0.124, 0.992, and 3.968 microg/mL of Pal. The intraday precision (relative standard deviation) ranges from 3.91% to 12.03% at concentrations of 1.43, 57.12, and 228.48 microg/mL for Dhpl and 3.79% to 8.12% at concentrations of 0.124, 0.992, and 3.968 microg/mL for Pal. The interday precision (relative standard deviation) ranges from 5.06% to 9.93% for Dhpl and 3.05% to 10.00% for Pal, respectively, at the same three concentrations. This validated assay is applied to the determination of Dhpl and Pal concentrations and used to take a limited view of the pharmacokinetic profile in rat serum after oral administration of Radix Salviae miltiorrhizae extract. 相似文献
927.
Zhihua Ren 《Journal of Mathematical Analysis and Applications》2003,284(1):118-126
In this paper we study smooth classification of hyperbolic vector fields based on their linear approximations only and obtain the following. On Rn, n?5, with only two kinds of exceptions, any two hyperbolic vector fields with generic nonlinear parts and where Ai are n×n matrices, are C1 conjugate to each other if and only if A1 and A2 are strictly similar, and they are C1 orbitally equivalent if and only if A1 and A2 are similar. 相似文献
928.
929.
The energy loss of slow ions during grazing scattering from a LiF(100) surface as a function of the projectile atomic number Z1 is observed to show oscillations similar to those occurring in metals. A model of stopping of ions in an electron gas where screening is calculated from density functional theory reproduces well the experimental data. The same model gives good agreement with the energy loss obtained in transmission experiments performed with H and He projectiles. Analysis of these results allows us to gain new insights in the stopping of slow ions in ionic crystals. 相似文献
930.
利用XRD技术测试了镀锌钝化膜结合界面的残余应力,同时通过电解抛光法检测了其厚度方向残余应力的分布规律,分析了残余应力对镀锌钝化膜结合强度的影响. 试验结果表明,镀锌钝化膜的残余应力均表现为压应力,并随着基体表面残余应力的增大而减小;钝化膜在2—10μm厚度方向的残应力为-274.5—-428.3MPa,其应力为梯度分布;镀锌钝化膜与基体的界面结合强度与其残余应力成反比,减小薄膜残余应力,有利于提高镀锌钝化膜与基体的结合强度.
关键词:
X射线衍射法(XRD)
镀锌钝化膜
结合强度
残余应力 相似文献