A Novel 12-Tungstovanadate Doubly-Grafted by Zn-Complexes: Synthesis, Crystal Structure and Properties

A novel vanadium-centered tungstovanadate, {[Zn(phen)₂(H₂O)]₂[VW₁₂O₄₀]}·3H₂O (1) (phen = 1,10-phenanthroline), has been hydrothermally synthesized and characterized by elemental analysis, single-crystal X-ray diffraction, IR spectroscopy and thermogravimetric analysis. Single-crystal X-ray diffraction at 293 K reveals that 1 consists of a [VW₁₂O₄₀]^4? Keggin unit doubly-grafted by a [Zn(phen)₂(H₂O)]²⁺ complex. The modified carbon-paste electrode of this tungstovanadate displays good electrocatalytic activity not only towards normal inorganic molecules NO₂ ^?, BrO₃ ^? and H₂O₂, but also biological molecule vitamin C. To some extent, this work shows that vanadium can be introduced into a polyoxometalate-modified electrode to facilitate catalytic oxidation or reduction of some chemical materials. Furthermore, this tungstovanadate shows high photoactivity with respect to degradation of methylene blue.     

保特征的自适应三角网格规范化算法

为了提高基于工业CT图像重构的三角网格质量,提出了顶点调整和特征因子相结合的网格规范化算法。引入模型特征因子和局部网格质量提高程度作为网格调整的控制条件,保留原始模型的局部细节特征;采用法矢量阈值按规律递增的方式自适应控制网格调整,实现不同曲率特征的自动识别。实验结果表明,与现有方法相比,该方法能更好地规范模型的三角网格,同时保留了原始模型的细节特征。     

柠檬酸单月桂醇酯二钠盐的合成过程及光谱分析

简述了柠檬酸月桂醇单酯二钠盐的合成过程。以乙酸酐、柠檬酸为原料 ,合成柠檬酸酐中间体 :柠檬酸∶乙酸酐 =2 0∶1 0 ,温度 36℃～ 37℃ ,反应时间 18h ,产率为 71 0 % ;酯化反应 :柠檬酸酐∶月桂酸=1 0∶1 1,温度 85℃～ 90℃ ,反应时间 2 0h ,单酯的产率为 83%～ 84 %。并采用红外光谱对合成过程中的原料、中间体及产物进行了研究。通过柠檬酸 ,柠檬酸酐及柠檬酸单酯二钠盐的红外光谱比较分析 ,证实了环状柠檬酸酐的形成。证明了直接制备高纯度的柠檬酸单月桂醇酯二钠盐工艺路线的合理性及可行性。同时表明可以用红外光谱对反应的中间体及产物进行验证。     

Ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming for the extraction of psoralen and isopsoralen from Psoralea corylifolia seeds

Recently, integrated and sustainable methods for extracting active substances from plant materials using green solvents, i.e., ionic liquids, have gained increasing attention. Ionic liquids show superiority over conventional organic solvents; however, they also exhibit negative factors and problems, such as high viscosity, poor water intermiscibility, intensive foaming and poor affinity for fat-soluble substances. The proposed method utilizes ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming (UESILED) to improve the extraction efficiency of ionic liquids. Single-factor experiments and a Box-Behnken design (BBD) were utilized to optimize the extraction procedure. The optimal conditions were as follows: extraction solvent, [C₁₀MIM]Br; ultrasonic treatment time, 28 min; ultrasonic irradiation power, 437 W; liquid–solid ratio, 10 mL/g; particle size, 60 ~ 80 mesh; ultrasonication temperature, 313 K; and [C₁₀MIM]Br solution concentration, 0.5 mol/L. In comparison with those of other reference extraction methods, the proposed method exhibited higher yields of two furocoumarins and operational feasibility. Moreover, the mechanism of UESILED was elaborated in terms of accelerating infiltration, dissolution and defoaming. The feasible and efficient ultrasonic-enhanced ionic liquid-based extraction established in this study strongly contributes to overcoming the limitations of ionic liquid solvents. The present research indicates that this improved process will be beneficial for the extraction of other fat-soluble substances and provides promising concepts and experimental data.     

Nanoscale experimental study of the morphology of a microcrack in silicon by transmission electron microscopy

A microcrack in a silicon single crystal was experimentally investigated using high-resolution transmission electron microscopy (HRTEM). In particular, the numerical Moiré (NM) method was used to visualize the deformations and defects. The lattice structure of the microcrack was carefully observed at the nanoscale. HRTEM images of the microcrack demonstrated that the lattice structure of most of the microcrack regions is regular with good periodicity. In addition, the microcrack cleavage expands alternately along different crystal planes, where the principal cleavage plane is the (1 1 1) crystal plane. The NM maps showed no sharp plastic deformation around the microcrack, but discrete edge dislocations can be found only near the crack tip.     

Cu2O/MWCNTs的制备、机理及气敏性研究

以Cu(Ac)2和多壁碳纳米管(MWCNTs)为原料,乙二醇(EG)作溶剂和还原剂制备了Cu2O/MWCNTs纳米复合材料。通过傅里叶红外光谱(FT-IR)、X射线粉末衍射(XRD)和透射电镜(TEM)对材料进行了表征,探讨了Cu2O以纳米粒子负载于MWCNTs表面的形成机理,并测试了复合材料对NOx的气敏性。结果表明Cu2O纳米粒子能够以键合作用负载在MWCNTs表面,Cu2O以纳米粒子形式有效负载是MWCNTs表面的化学吸附中心和Cu2+使用量的综合作用结果;Cu2O的负载有效增强了MWCNTs对NOx的气敏范围和灵敏度。     

Permeable cracks between two dissimilar piezoelectric materials

An interfacial crack with electrically permeable surfaces between two dissimilar piezoelectric ceramics under electromechanical loading is investigated. An exact expression for singular stress and electric fields near the tip of a permeable crack between two dissimilar anisotropic piezoelectric media are obtained. The interfacial crack-tip fields are shown to consist of both an inverse square root singularity and a pair of oscillatory singularities. It is found that the singular fields near the permeable interfacial crack tip are uniquely characterized by the real valued stress intensity factors proposed in this paper. The energy release rate is obtained in terms of the stress intensity factors. The exact solution of stress and electric fields for a finite interfacial crack problem is also derived.     

Chemical Composition,Anti-Breast Cancer Activity and Extraction Techniques of Ent-Abietane Diterpenoids from Euphorbia fischeriana Steud

Ent-abietane diterpenoids are the main active constituents of Euphorbia fischeriana. In the continuing search for new anti-breast cancer drugs, 11 ent-abietane diterpenoids (1–11) were isolated from E. fischeriana. The structures of these compounds were clearly elucidated on the basis of 1D and 2D NMR spectra as well as HRESIMS data. Among them, compound 1 was a novel compound, compound 10 was isolated from Euphorbia genus for the first time, compound 11 was firstly discovered from E. fischeriana. These compounds exhibited varying degrees of growth inhibition against the MCF-10A, MCF-7, ZR-75-1 and MDA-MB-231 cell lines in vitro. The experimental data obtained permit us to identify the roles of the epoxy group, hydroxyl group and acetoxyl group on their cytotoxic activities. Extraction is an important means for the isolation, identification, and application of valuable compounds from natural plants. To maximize yields of ent-abietane diterpenoids of E. fischeriana, 17-hydroxyjolkinolide B, jolkinolide B, 17-hydroxyjolkinolide A and jolkinolide A were selected as quality controls to optimize the salting-out-assisted liquid–liquid extraction (SALLE) by response surface methodology (RSM). The optimized conditions for SALLE were 0.47 g sodium dihydrogen phosphate, 5.5 mL acetonitrile and 4.5 mL water at pH 7.5. The experimental values of 17-hydroxyjolkinolide B, jolkinolide B, 17-hydroxyjolkinolide A and jolkinolide A (2.134, 0.529, 0.396, and 0.148 mg/g, respectively) were in agreement with the predicted values, thus demonstrating the appropriateness of the model.     

Ag/质子化g-C3N4纳米棒材料的制备及其光催化降解性能

制备了 Ag 负载于质子化 g-C₃N₄(pCN)的纳米棒材料(Ag/pCN),对比了 g-C₃N₄(CN)、表面负载 Ag 的 CN(Ag/CN)、pCN 和 Ag/pCN在可见光条件下光催化降解亚甲蓝(MB)溶液的效果。结果表明,Ag/pCN光催化效率最高(92.63%),并且具有良好的稳定性;通过光电流-时间(I-t)曲线、Nyquist曲线、Mott-Schokkty曲线和捕获实验探究了Ag/pCN光催化降解MB的机理：虽然pCN的π共轭体系较CN发生变化,但由于形成了纳米棒,其比表面积的增加以及Ag负载的协同效应致使Ag/pCN具有优异的光催化性能。光催化过程中羟基自由基(·OH)是起主要作用的活性物质,其由光生电子(e^-)与表面吸附的 O₂反应产生以及光生空穴(h⁺)与H₂O或OH^-反应产生。     

多元弱酸的准确滴定

用二元弱酸滴定的林邦滴定曲线方程推导第一和第二滴定突跃绝对值,用第一和第二滴定突跃绝对值推导二元弱酸第一和第二级解离的H+准确滴定的条件,并将其应用于多元弱酸的准确滴定.