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51.
以两个形状杂化分子(Shape Hybrid Molecules)为目标分子, 研究了它们在气液界面上形成Langmuir膜的过程和Langmuir-Blodgett (LB)膜的聚集态结构. 杂化分子是由Wells-Dawson型磷钨氧簇(Polyoxometalates, POMs)和T8型的倍半硅氧烷簇(Polyhedral Oligosilsesquioxane, POSS), 通过对苯二甲酸有机连接链(OL)用共价键构筑的具有杂化性质和哑铃形状的簇-簇杂化分子(POM-OL-POSS). 这两种杂化分子的差别在于POSS段中, 外围有机基团的尺寸不同. 在实验中, 采用Langmuir和LB膜技术, 了解POSS外围的七个取代基变化导致的分子尺寸变化对Langmuir膜形成过程和LB膜结构的影响. 采用Langmuir技术测定了表面压-平均分子面积(π-A)等温曲线和π-A循环等温曲线, 跟踪并研究了这两个杂化分子在水表面上形成Langmuir膜的过程. 实验结果表明, 两个杂化分子都表现出良好的两亲性, 从气相变化到固相的过程中, 杂化分子经历了从分散到集中的过程. 将这些膜转移到基片上, 得到单层的LB膜, 再利用原子力显微镜(AFM)和透射电子显微镜(TEM)研究了LB膜的表面形貌和聚集态结构. 由于POM段中含有钨和钒金属, 可以直接用TEM观察聚集态结构, 发现了在气-液和液-固相转变过程中, LB膜中杂化分子的聚集态结构都呈现涨落特征, 一种凝聚态物理中由相转变导致结构涨落的重要物理现象. 本研究获得的结果能够帮助我们以及这个领域的研究者们继续优化杂化分子的结构, 进一步构筑具有有序结构的膜和本体材料. 相似文献
52.
Self‐Assembly and Compartmentalization of Nanozymes in Mesoporous Silica‐Based Nanoreactors 下载免费PDF全文
Yanyan Huang Dr. Youhui Lin Xiang Ran Prof. Dr. Jinsong Ren Prof. Dr. Xiaogang Qu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5705-5711
Herein, to mimic complex natural system, polyelectrolyte multilayer (PEM)‐coated mesoporous silica nanoreactors were used to compartmentalize two different artificial enzymes. PEMs coated on the surface of mesoporous silica could serve as a permeable membrane to control the flow of molecules. When assembling hemin on the surface of mesoporous silica, the hemin‐based mesoporous silica system possessed remarkable peroxidase‐like activity, especially at physiological pH, and could be recycled more easily than traditional graphene–hemin nanocompounds. The hope is that these new findings may pave the way for exploring novel nanoreactors to achieve compartmentalization of nanozymes and applying artificial cascade catalytic systems to mimic cell organelles or important biochemical transformations 相似文献
53.
邓小刚 《中国科学A辑(英文版)》2002,45(3):356-370
Based on the method deriving dissipative compact linear schemes (DCS), novel high-order dissipative weighted compact nonlinear schemes (DWCNS) are developed. By Fourier analysis,the dissipative and dispersive features of DWCNS are discussed. In view of the modified wave number, the DWCNS are equivalent to the fifth-order upwind biased explicit schemes in smooth regions and the interpolations at cell-edges dominate the accuracy of DWCNS. Boundary and near boundary schemes are developed and the asymptotic stabilities of DWCNS on both uniform and stretching grids are analyzed. The multi-dimensional implementations for Euler and Navier-Stokes equations are discussed. Several numerical inviscid and viscous results are given which show the good performances of the DWCNS for discontinuities capturing, high accuracy for boundary layer resolutions, good convergent rates (the root-mean-square of residuals approaching machine zero for solutions with strong shocks) and especially the damping effect on the spudous oscillations which were found in the solutions obtained by TVD and ENO schemes. 相似文献
54.
We report on the successful synthesis of silver sulfide (Ag(2)S) nanowires by a simple and mild gas-solid reaction approach. For the nanowire synthesis, a preoxidized silver substrate is exposed to an atmosphere of an O(2)/H(2)S mixture at room temperature or slightly above. The resulting Ag(2)S nanowires are phase pure with a monoclinic crystal structure and have diameters of a few tens of nanometers and lengths up to 100 mum. The influence of reaction conditions on the diameter, length, and morphology of the Ag(2)S nanowires has been studied by a number of structural and spectroscopic techniques. The nanowire growth mechanism on the Ag substrate has been discussed, which is likely characterized by continuous deposition at the tip. Additionally, we demonstrate thinning and cutting of individual Ag(2)S nanowires with electron beams and laser beams, which are potentially useful for nanowire manipulation and engineering. 相似文献
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本文假定等离子体局部压强梯度由理想磁流体高n气球模所限定,讨论了非圆截面环流器的最佳压强剖面。分析了椭圆及三角变形的效应,发现三角变形对提高稳定性很有利;q剖面对平均比压值及中心比压值都有强烈影响,而沿半径下降的q剖面对提高比压值很有利。 相似文献
58.
Zhen Yu Yuping Duan Lidong Liu Shunhua Liu Xujing Liu Xiaogang Li 《Surface and interface analysis : SIA》2009,41(5):361-365
Hot‐dipped aluminum copper with plating auxiliary KF is introduced in this work. In this study, the intermetallic layer thickness varies with dipping temperature and time in a linear relationship. The main phases are identified to be CuAl2 and K3AlF6 by means of X‐ray diffraction. The reaction equations are deduced according to the elements concentration gradient in cross section. The copper diffusion rate in liquid Al is calculated to be 1.13 × 10−12 m2/s by Fick's second law in semi‐infinite solid model, and the obtained conductivity is 1.758–1.767 × 10−2 Ω mm2/m. The results indicate that the interfacial bonding is in a good state and plating auxiliary KF aqueous solution. can significantly improve the substrate wettability. The appropriate hot‐dipping condition for the samples is 953–973 K for 4–8 s. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Xiaogang Yang Dongsheng Li Feng Fu Long Tang Jiyuan Yang Lili Wang Yaoyu Wang 《无机化学与普通化学杂志》2008,634(14):2634-2638
The reaction of ZnII nitrate with maleic acid (H2mal) / fumaric acid (H2fum) and 4,4′‐dipyridyl disulfide (4‐pds) resulted under same conditions in two distinct interpenetrated compounds, namely [Zn(4‐dps)2(H2O)2]·2Hmal ( 1 ) and [Zn(4‐dps)(fum)] ( 2 ). In 1 , Hmal anion adopts bridging mode based on hydrogen bonding, affording a 2‐fold parallel interpenetrated 3D→3D α‐Po net hydrogen‐bonded framework, in which 1D double‐stranded chains are formed, and then extended to a 3D supramolecular architecture combining second‐sphere hydrogen‐bonded interactions. For 2 , fum dianion takes on bis‐dentate bridging coordination fashion, furnishing a 2‐fold interpenetrated 2D→2D (4,4) layered coordination network, in which the tetrahedral ZnII atoms are interlinked by 4‐dps and fum. Additionally, the compound 2 shows strong fluorescence in the solid state at room temperature. 相似文献