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71.
Zhao-Rang H Feng-Qi L Bai Y Li-Li C Xin-Yi T 《Journal of colloid and interface science》2002,251(2):447-451
The flowing nature and rheological properties of polymethyl methacrylate latex systems in a coaxial cylinder viscometer were studied on the basis of laminar shear flow model and rheological experimental data. The physical meaning of laminar viscosity (eta(i,j)) and zero shear viscosity (eta(0)) were described. We assumed that laminar shear flows depended on position and shear time, so microrheological parameters were the function of position and shear time. eta(i,j) was the viscosity of any shear sheet i between two neighboring laminar shear flows at time t; j was denoted as j=t/Deltat; and Deltat was the interacting time of two particles or two laminar shear flows. tau(i,j) and gamma(i,j) were shear stress and shear rate of any shear sheet i at j moment. According to Newton regulation tau(i,j)=eta(i,j)gamma(i,j), apparent viscosity eta(a) should be a statistically mean value of j shear sheets laminar viscosity at j moment, i.e., eta(a)= summation operator(i=j)eta(i,j)gamma(i,j)/ summation operator(i=j)gamma(i,j). eta(0) was defined as shear viscosity between a laminar shear flow and a still fluid surface, i.e., eta(0)=(tau(i,j)/gamma(i,j))(j-i-->0). These new ideas described above may be helpful in the study of the micromechanisms of latex particle systems and worthy of more research. 相似文献
72.
From the changes in energy band, density of state (DOS) and electronic structure calculated by the DFT/B3LYP method, the conductivity of carbon doped boron‐nitride nanotube (BNNT), which is formed by C‐C bond substituting B‐N bond, was discussed. The results indicate that the substitution will strengthen the conductivity of the tube, and its semi‐conductivity might be adjusted by controlling the substitution. 相似文献
73.
Catalytic oxidation of alcohols with polymer-supported ruthenium complex under mild conditions 总被引:1,自引:0,他引:1
Qiao-xiang Kang Ju-jie Luo Yan-bin Bai Zhi-wang Yang Zi-qiang Lei 《Journal of organometallic chemistry》2005,690(26):6309-6313
Polymer-supported ruthenium-containing complex PS–Phen–Ru was synthesized (where PS = chloromethyl polystyrene resin, Phen = 1,10-phenanthroline) and was characterized by FT-IR, ICP, and XPS. The supported complex was used to catalyze the oxidation of primary aliphatic alcohols as well as aromatic alcohols in the presence of iodosylbenzene. The oxidations were carried out in acetonitrile solution, affording the corresponding aldehydes or ketones in high substrate conversion and high selectivities under mild reaction conditions. The catalyst can be easily prepared and can be recycled. 相似文献
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75.
Li BS Kang SZ Cheuk KK Wan L Ling L Bai C Tang BZ 《Langmuir : the ACS journal of surfaces and colloids》2004,20(18):7598-7603
In the present work, we investigated self-assembling of a poly(phenylacetylene) carrying L-valine pendants (PPA-Val) in a water/methanol solution, upon evaporation of the solution on mica, and on the water surface. With intercalation of a fluorescence probe of Ru(phen)2(dppx)2+ (phen = 1,10-phenanthroline, dppx=7,8-dimethyldipyridophenazine) into the hydrophobic cavities associated by the PPA-Val chains, their helical structures were directly detected in solution with an in situ fluorescence microscope. Helical aggregates were observed with AFM upon evaporation of the solvents, suggesting that the helical structures in the solution are the building blocks of the helical aggregates. Self-assembling structures of PPA-Val on the water surface were, however, very different from that formed upon evaporation of its THF solution on the mica surface. The polymer chains associated into a monolayer of extended fibers on the water surface, whereas superhelical fibers formed on the mica surface. Water molecules play a critical role in inducing the polymer to form diverse morphological structures in its bulk solution and on its surface. In solution, the isotropic hydrophobic effect drove the polymer chains to form superhelical aggregates, while on the water surface, the hydrophobic effect concentrated mainly on the lateral part of the polymer, thus giving a monolayer of extended fibers. 相似文献
76.
以Mg(NO3)2,Ca(NO3)2,Eu(NO3)3,Bi(NO3)3和Si(OC2H5)4为反应物,采用溶胶-凝胶法,在比较低的温度,首次合成0.701molMgO-0.175molCaO-1.25molSiO2:0.06molEu^3+,0.002molBi^3+(加入Li^+作为电荷补偿剂)发光体,得到了最佳合成条件,研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程,探讨了发光体在不同激光 相似文献
77.
长链脂肪酸LB膜的X射线衍射研究 总被引:4,自引:0,他引:4
利用Langmuir-Blodgett技术制备了硬脂酸、花生酸及其混合酸的多层LB膜。用低角X射线衍射研究了它们的周期结构,硬脂酸和花生酸的LB膜在2θ=0.8°~23°的范围内分别出现13个和12个布拉格衍射峰,由此计算了它们的等同周期。用模型计算了它们衍射峰的强度,得到了与实验一致的衍射强度奇偶起伏的结果。在混合酸的LB膜中,可以观察到等同周期随混合比变化的规律。 相似文献
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80.
The sequence-specific recognitions between DNA and proteins are playing important roles in many biological functions. The double-stranded DNA microarrays (dsDNA microarrays) can be used to study the sequence-specific recognitions between DNAs and proteins in highly parallel way. In this paper, two different elongation processes in forming dsDNA from the immobilized oligonucleotides have been compared in order to optimize the fabrication of dsDNA microarrays: (1) elongation from the hairpins formed by the self-hybridized oligonucleatides spotted on a glass; (2) elongation from the complementary primers hybridized on the spotted oligonucleatides. The results suggested that the dsDNA probes density produced by the hybridized-primer extension was about four times lower than those by the self-hybridized hairpins. Meanwhile, in order to reduce the cost of dsDNA microarrays, we have replaced the Klenow DNA polymerase with Taq DNA polymerase, and optimized the reaction conditions of on-chip elongation. Our experiements showed that the elongation temperature of 50 °C and the Mg2+ concentration of 2.5 mM are the optimized conditions in elongation with Taq DNA polymerase. A dsDNA microarray has been successfully constructed with the above method to detect NF-kB protein. 相似文献