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A novel terbium(III) coordination polymer [Tb(C7H3NO4)(C6H4NO2)(H2O)] was successfully synthesized hydrothermally and characterized by single-crystal X-ray diffraction. The complex is of monoclinic, space group P21/c with a = 9.2252(11), b = 14.1477(16), c = 10.5134(12) A, β = 95.770(2)°, V = 1365.2(3) A3, Z = 4, Dc = 2.248 g·cm-3, F(000) = 880, the final R = 0.0176 and w R = 0.0411 for 2149 observed reflections with I 2σ(I). The complex is extended into a three-dimensional network structure with 24-atom rings which are composed of Tb, C and O atoms. The complex displays green fluorescence emission in the solid state at room temperature, which corresponds to 5D4 → 7F5 transition of the Tb(III) ion. 相似文献
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Wei Jin Wei-Yu Wang Yu-Lian Zhang Yong-Jian Yang Qing-Cui Chu Jian-Nong Ye 《中国化学快报》2013,24(7):636-638
A sensitive method for simultaneous determination of six phenolic whitening agents,including arbutin, phenol,resorcinol,hydroquinone,kojic acid,and salicylic acid in cosmetics has been developed using micellar electrokinetic capillary chromatography with amperometric detection(MECC-AD).Effects of several factors,such as the pH value and concentration of running buffer,potential applied to the working electrode,separation voltage,and injection time were investigated to obtain optimum conditions for separation and detection.With a 75 cm long fused-silica capillary tube,well-defined separation of six phenolic compounds was achieved in 10mmol/L SDS/40 mmol/L H3BO3-Na2B4O7 running buffer(pH 9.0).Good linear relationship was obtained for each analyte over three orders of magnitude with correlation coefficients(r2) between 0.9985 and 0.9994,and the detection limit(S/N=3) ranged from 0.04μg/mL to 0.45μg/mL The proposed method has been successfully applied for the determination of phenolic whitening agents in real cosmetic samples with satisfactory results,providing an alternative monitoring method for cosmetics safety regulation. 相似文献
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We demonstrate that meandering as well as regular spiral waves can form in a well-controlled culture layer of rat ventricle cells and that the meandering spiral wave, in particular, can generate an alternant rhythm. These observations are made possible by a newly developed, noninvasive phase contrast macro-optics that is simple but highly effective in visualizing the contractile motion of the populations of cardiac cells. 相似文献
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We propose and develop a new solid immersion lens (SIL), which is called the multilevel phase Fresnel zone plate lens (FZPL) for the near-field (evanescent wave) microscopy. The simple analysis is presented by using the scalar diffraction theory. The outstanding advantages of this FZPL are that it both focuses incident waves and produces evanescent waves. A FZPL can effectively concentrate the high angle rays important for the high resolution in comparison with the conventional SILs. The optical system equipped with the FZPL is not only simple in the assembly but also effective in making an optical head unit. 相似文献
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Hsin‐Chung Cheng Chau‐Hsiang Wang Chiung‐Fang Huang Yung‐Kang Shen Yi Lin Dong‐Yea Sheu Yi‐Han Hu 《先进技术聚合物》2010,21(9):632-639
In this study, master of the microlens arrays is fabricated using micro dispensing technology, and then electroforming technology is employed to replicate the Ni mold insert of the microlens arrays. Finally, micro hot embossing is performed to replicate the molded microlens arrays from the Ni mold insert. The resin material is used as the dispensing material, which is dropped on a glass substrate. The resin is exposed to a 380 W halogen light. It becomes convex under surface tension on the glass substrate. A master for the microlens arrays is then obtained. A 150‐nm‐thick copper layer is sputtered on the master as an electrically conducting layer. The electroforming method replicates the Ni mold insert from the master of the microlens arrays. Finally, micro hot embossing is adopted to replicate the molded microlens arrays. The micro hot embossing experiment employs optical films of polymethylmethacrylate (PMMA) and polycarbonate (PC). The processing parameters of micro hot embossing are processing temperature, embossing pressure, embossing time, and de‐molding temperature. Taguchi's method is applied to optimize the processing parameters of micro hot embossing for molded microlens arrays. An optical microscope and a surface profiler are utilized to measure the surface profile of the master, the Ni mold insert and the molded microlens arrays. AFM is employed to measure the surface roughness of the master, the Ni mold insert and the molded microlens arrays. The sag height and focal length are determined to elucidate the optical characteristics of the molded microlens arrays. Copyright © 2009 John & Sons, Ltd. 相似文献
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基于Kirchhoff理论讨论圆截面弹性螺旋杆的动力学问题.以杆中心线的Frenet坐标系为参考系,建立用欧拉角描述的弹性杆动力学方程.讨论其在端部轴向力和扭矩作用下保持的无扭转螺旋线平衡状态.在静力学和动力学领域内讨论其平衡稳定性问题.还讨论了弹性杆平衡的Lyapunov稳定性和欧拉稳定性两种不同稳定性概念之间的区别和联系.在一次近似意义下证明了螺旋杆在空间域内的欧拉稳定性条件是时域内Lyapunov稳定性的必要条件.导出了解析形式螺旋杆三维弯曲振动的固有频率,为螺旋线倾角和受扰挠性线波数的函数.
关键词:
弹性螺旋杆
Kirchhoff动力学比拟
Lyapunov稳定性
欧拉稳定性 相似文献
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Yasuo Kuga Guifu Zhang Ji-Hae Yea Akira Ishimaru 《Waves in Random and Complex Media》1998,8(3):269-281
The analytical solution for the angular correlation function of scattered waves from randomly distributed infinitely long cylinders is obtained using the second-order approximation with a modified attenuation coefficient. The approach is based on the coherent summation of the scattered waves which preserves the interference effects such as backscattering enhancement. The modification of the transport attenuation coefficient includes the contribution due to the incoherent wave. By comparing with the exact numerical simulations, we found that the correction factor is given by (1-μ¯) which also appears in the diffusion equation. The present approach gives good agreement with numerical and experimental results. 相似文献
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为扩大稀土荧光配合物的应用范围,满足水溶液中微量铬的高灵敏高选择性探测要求,制备了一种基于水分散纳米无定形水杨酸甲酯铽配合物(A-MS-Tb)的高灵敏三价铬离子荧光传感器。结果表明:在水溶液中直接反应合成的配合物A-MS-Tb为无定形的纳米沉淀,其粒子尺度在50~100 nm之间,具有与报道的配合物晶体类似的组成。该配合物在494、549、591和625 nm处呈现出强的荧光发射,归属于铽离子的5D4→7FJ(J=6,5,4,3)能级跃迁。A-MS-Tb与晶体配合物的显著差别在于其在水中的悬浮稳定性和荧光稳定性更好,这对于其作为荧光材料和离子传感器非常重要。尤其突出的是,当将三价铬离子加入到它的水悬浮溶液中后,会减弱配体与铽离子之间的配位作用,导致其绿色荧光被淬灭。据此,构建了一种高灵敏测定溶液中铬离子浓度的荧光探针,并对其分析的选择性、灵敏度和抗干扰能力进行了评价。 相似文献
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