A fluorogenic 1,3-dipolar cycloaddition reaction of 3-azidocoumarins and acetylenes

Copper(I)-catalyzed 1,3-dipolar cycloaddition reaction of nonfluorescent 3-azidocoumarins and terminal alkynes afforded intense fluorescent 1,2,3-triazole products. The mild condition of this reaction allowed us to construct a large library of pure fluorescent coumarin dyes. Since both azide and alkyne are quite inert to biological systems, this reaction has potential in bioconjugation and bioimaging applications. [reaction: see text]     

SiOx纳米管的制备及其发光特性

Amorphous SiOx nanotubes with homogeneous diameters were fabricated in large-scale on silicon substrate by thermal evaporation method, with liquid gallium as medium. The average diameter of tubes is about 80 nm and the length is more than 10 1m, with small ratio between the inner and outer diameter of the tube. The silicon element in the substrate and the residual oxygen element in reaction chamber were first dissolved into liquid Ga. Then the SiOx precipitated from the surface of gallium droplet, forming the nanotube structure with Ga droplet being the center. The room temperature photoluminescence measurements under excitation at 260 nm show that the SiOx nanotubes has a strong blue emission at 453 nm with two shoulders at 410 and 480 nm respectively, which may be related to oxygen defects. The preparation method improved the traditional complicated method and also provided a new way to fabricate SiOx nanotubes in large quantity.     

An ionothermal synthetic approach to porous polyoxometalate-based metal-organic frameworks

Pretty porous POMs: Ionothermal synthesis was applied to prepare porous POM-based open frameworks. The structural integrity remains unchanged until 300?°C; most importantly, the bulky tetrabutylammonium cations within their nanosized channels can be replaced by transition-metal ions through a cation-exchange process, and subsequent gas adsorption measurements confirm their permanent porosity.     

加速溶剂萃取–液相色谱法测定五灵脂药材中原儿茶酸的含量

建立了五灵脂中原儿茶酸含量的测定方法。利用加速溶剂萃取仪(ASE),以75%乙醇水溶液提取样品中的待测物,用Diamosil C18(4.6 mm×250 mm,5.0μm)色谱柱在梯度洗脱条件下分离待测物,外标法定量。原儿茶酸的线性范围为0.1~10.0 mg/L,相关系数r=0.9998。方法的回收率为83%~107%,测定结果的相对标准偏差为4.6%~10.5%,方法的定量限为1.0 mg/kg。该方法操作简便、快速,提取效率高,适用于检测和分析五灵脂中原儿茶酸的含量。     

Urea-based polyacetylenes as an optical sensor for fluoride ions

Novel acetylenes carrying urea groups, 1-(4-ethynylphenyl)-3-(4-nitrophenyl) urea (1), 1-(4-propargyl)-3-(4-nitrophenyl) urea (2), were synthesized and polymerized with rhodium catalyst. Polymers [poly(1) and poly(2)] with moderate molecular weights were obtained in good yields. The anion sensing ability of poly(1) and poly(2) was estimated using the tetra-n-butylammonium (TBA) salts of a series of anions in DMF. Upon the addition of F-, the color of the DMF solution of poly(1) and poly(2) immediately turned to a different color, while the color of solution changed slightly upon addition of Cl-, HSO4-, Br-, and NO3-, indicating the F- sensing ability of poly(1) and poly(2). The 1H-NMR titrations of poly(1) revealed that the colorimetric response of poly(1) was triggered by the urea/F- interaction through the hydrogen bonding and/or deprotonation process. The absorption spectra titration and Hill plot analysis were carried out to measure the F- binding ability, and the Hill coefficient in the poly(1)/F- complexation was found to be 5.8. This result clearly indicated that this binding mode between poly(1) and F- was based on a positive homotropic allosterism.     

Compounds with inhibitory activity on peristalsis from the seeds of Holarrhena antidysenterica

Eight compounds were isolated from the seeds of Holarrhena antidysenterica Wall.ex A.DC. On the basis of physico-chemical properties and spectroscopic data, holarrhenanan (1) was identified as a new compound, compounds 2–3 were isolated from H. antidysenterica for the first time, and five known compounds were also obtained. Inhibitory effects of some compounds and extracts to the intestinal peristalsis were evaluated. Results showed that the extracts and compounds 4, 6 exhibited remarkable inhibitory effects with tension inhibition rate of 32.77, 32.77% and amplitude inhibition rate of 59.51, 55.98%, respectively on the vitro rabbit intestinal peristalsis.     

基于饱依丁-汤姆逊模型的软岩损伤蠕变模型

为更加准确地描述深部软岩的蠕变全过程,以饱依丁-汤姆逊模型为基础,将损伤变量引入到蠕变方程中,并构造了可描述加速蠕变阶段的模型元件,通过串联得到了新的蠕变模型。结果表明:该模型能够较好地描述软岩的衰减蠕变、稳态蠕变、加速蠕变阶段。用该模型对泥质页岩的蠕变试验结果进行数据拟合对比,结果显示该模型的拟合曲线与实验曲线基本吻合,拟合度为0.99733,能够很好地反映出软岩蠕变的特性,适合用于描述深部软岩的蠕变行为。     

单相旋转型驻波超声电机的数学模型及仿真

尽管单相驱动的旋转型驻波超声电机的原理样机早巳研制成功，但对这类电机的运动机理的研究却一直局限在定性分析上。本文将从能量角度，根据Hamilton变分原理，定、转子摩擦界面采用纯滑动模型建立了该种电机的数学模型；并根据此模型，用MATLAB语言作了计算机仿真，得到了该种电机的开、关过程动态响应。     

Recovery-Based Error Estimator for Natural Convection Equations Based on Defect-Correction Methods

In this paper, we propose an adaptive defect-correction method for natural convection (NC) equations. A defect-correction method (DCM) is proposed for solving NC equations to overcome the convection dominance problem caused by a high Rayleigh number. To solve the large amount of computation and the discontinuity of the gradient of the numerical solution, we combine a new recovery-type posteriori estimator in view of the gradient recovery and superconvergent theory. The presented reliability and efficiency analysis shows that the true error can be effectively bounded by the recovery-based error estimator. Finally, the stability, accuracy and efficiency of the proposed method are confirmed by several numerical investigations.     

Ameliorating the interfacial issues of all-solid-state lithium metal batteries by constructing polymer/inorganic composite electrolyte

Lithium metal is one of the most promising anodes for next-generation batteries due to its high capacity and low reduction potential.However,the notorious Li de...