The iterative correction method for Volterra integral equations

We show that the (n – 1)-fold application of an iterative correction technique to the iterated collocation solution corresponding to the one-point Gauss collocation solution for a Volterra integral equation of the second kind l6eads to a significant improvement in the precision of these approximations: the resulting rate of (global) convergence is .The work of first author has been supported by the Natural Sciences and Engineering Research Council of Canada (Research Grant OGP0009406).     

A stereoselective route to cis-2-phenyl-3-piperidinol

Enantiopure cis-2-phenyl-3-piperidinol is a commonly used synthon for the obtention of a potent class of neurokinin substance P receptor antagonists. Starting from (R)-phenylglycine, the present report describes an efficient route for the stereoselective synthesis of the above piperidinol structural core.     

氧化石墨烯-邻苯二甲酸二(2-乙基己)酯表面分子印迹吸附剂的合成及应用

合成了以纳米材料氧化石墨烯为载体的表面分子印迹固相萃取材料，建立了分子印迹萃取联用高效液相色谱法检测牛奶塑料包装袋中的塑化剂邻苯二甲酸二（2-乙基己）酯（DEHP）残留的方法。以氧化石墨烯为基质、DEHP为模板分子、甲基丙烯酸为功能单体、N，N-二甲基甲酰胺为溶剂，通过沉淀聚合法合成表面分子印迹材料，优化了合成条件并对产品进行红外光谱、透射电镜表征。对产品的吸附性能（包括选择性、吸附平衡时间、吸附容量、重复使用率等）进行测定。在最优萃取条件下对牛奶包装袋提取液中DEHP进行选择性富集，通过高效液相色谱-紫外法检测，线性范围为0.5~50 mg/L，检出限为0.03 mg/L，定量限为0.1 mg/L。3种加标浓度下回收率为81.6%~92.4%，相对标准偏差（RSDs）小于7%。结果表明，该方法能够应用于实际样品中DEHP分析。     

One‐pot synthesis of polyfluoroterphenyls via palladium‐catalyzed Suzuki–Miyaura coupling of chlorobromobenzene and CH bond functionalization of perfluoroarenes

An efficient tandem route for the synthesis of polyfluoroterphenyl derivatives has been developed. The target compounds were obtained in moderate to good yields by a Pd(OAc)₂‐catalyzed three‐component coupling reaction involving palladium‐catalyzed direct C? H activation of perfluoroarenes. This in turn will set the stage for a wide application of this useful reaction for the synthesis of fluorinated liquid crystal compounds containing the privileged polyfluoroterphenyl structure. Copyright © 2014 John Wiley & Sons, Ltd.     

Carbon fiber-bridged polyaniline/graphene paper electrode for a highly foldable all-solid-state supercapacitor

Journal of Solid State Electrochemistry - A simple, scalable approach is developed to fabricate a flexible hybrid paper electrode composed of the polyaniline/graphene and the carbon fiber...     

Selective magnetic solid-phase extraction of amide herbicides from fish samples coupled with ultra-high-performance liquid chromatography with tandem mass spectrometry

An efficient magnetic dummy template molecularly imprinted polymer nanocomposite was prepared using multi-walled carbon nanotubes as a support and metolachlor deschloro as a dummy template. The obtained nanocomposites were characterized using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, and transmission electron microscopy. The adsorption performance of the obtained nanocomposites was evaluated through binding experiments, including static adsorption, kinetic adsorption, and selective recognition studies. The obtained nanocomposites were successfully applied as selective sorbents for the magnetic solid-phase extraction of seven amide herbicides (alachlor, acetochlor, pretilachlor, butachlor, metolachlor, diethatyl ethyl, and dimethachlor) coupled with liquid chromatography-tandem mass spectrometry from fish samples. Under the optimized conditions, the limit of detection was 0.01–0.1 μg/kg. The obtained recoveries of the amide herbicides from the fish samples were in the range of 88.0 to 102.1% with a relative standard deviation of less than 7.5%. This method, which eliminated the effect of template leakage on qualitative and quantitative analysis was found to be superior to the methods reported in the literature. The results indicated that it could be successfully applied to analyze amide herbicides in fish samples with satisfactory recoveries.     

Innovative strategies to effectively increase the active-site density of M-N-C materials for electrochemical application

Owning the merits of low-cost, unique electronic and geometric properties, atomically dispersed M-N-C materials have been extensively examined as robust electrocatalysts for many important electrochemical reactions. Nevertheless, it remains a grand synthetic challenge to fabricate such materials with a high concentration of isolated metal active sites, as the formation of metal clusters/nanoparticles seems to be inevitable during the calcination process due to the high surface free energy of single-atom metals. As a result, although M-N-Cs have been successfully tuned to display remarkable activities per metal atomic site, their overall catalytic performances are still unsatisfactory. In this current opinion article, we summarize recent advances in innovative strategies to increase the active-site density of M-N-Cs and also propose the future opportunities and challenges for fostering the practical application of M-N-Cs in electrochemical devices.     

A NEW FINITE ELEMENT APPROXIMATION OF A STATE-CONSTRAINED OPTIMAL CONTROL PROBLEM

In this paper, we study numerical methods for an optimal control problem with pointwise state constraints. The traditional approaches often need to deal with the deltasingularity in the dual equation, which causes many difficulties in its theoretical analysis and numerical approximation. In our new approach we reformulate the state-constrained optimal control as a constrained minimization problems only involving the state, whose optimality condition is characterized by a fourth order elliptic variational inequality. Then direct numerical algorithms （nonconforming finite element approximation） are proposed for the inequality, and error estimates of the finite element approximation are derived. Numerical experiments illustrate the effectiveness of the new approach.     

Finite element method for a nonsmooth elliptic equation

In this paper, we study the finite element method for a non-smooth elliptic equation. Error analysis is presented, including a priori and a posteriori error estimates as well as superconvergence analysis. We also propose two algorithms for solving the underlying equation. Numerical experiments are employed to confirm our error estimations and the efficiency of our algorithms.