Suppression of surface pattern formation in spin‐coated polymer films by the addition of polydimethylsiloxane‐grafted silica nanoparticles

Polydimethylsiloxane (PDMS)‐grafted nanoparticles and PDMS were added, respectively, to inhibit the dewetting of polymer films and the formation of surface patterns in spin coating. Uniform and flat films were successfully achieved with the addition of PDMS‐grafted silica nanoparticles or PDMS. Time‐of‐flight secondary ion mass spectrometry depth profiling indicated that PDMS‐grafted silica nanoparticles and PDMS preferentially segregated to the surface. A high concentration of bromine end groups was observed at the interface. The surface layer of PDMS or PDMS‐grafted silica nanoparticles can decrease the surface tension of the polymer solutions and reduce the evaporation rates of the solvents, providing more time for the bromine end groups to anchor themselves at the silicon substrates. Copyright © 2016 John Wiley & Sons, Ltd.     

A green approach for synthesis of naphthoquinone-fused oxazine derivatives in water under ultrasonic irradiation

An efficient and eco-friendly procedure has been developed for synthesis of naphthoquinone-fused oxazine derivatives via one-pot pseudo four-component reaction of 2-hydroxy-1,4-naphthoquinone, aromatic amine and formaldehyde in water under ultrasound irradiation. This protocol has the advantages of being catalyst-free, with short reaction times and high yields, and being environmentally benign with an easy work-up.     

高效液相色谱-串联质谱法同时测定饲料中11种霉菌毒素

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时检测饲料中11种霉菌毒素的分析方法。样品经乙腈提取,MycoSep 228多功能净化柱填料和PRIME HLB固相萃取柱净化;采用Agilent Zorbax SB-C18色谱柱(150 mm×2.1 mm,3.5μm)分离,以甲醇和5 mmol/L乙酸铵水溶液(含0.1%(v/v)甲酸)为流动相梯度洗脱;采用ESI源正、负离子同时扫描,多反应监测(MRM)模式测定,内标法定量。结果表明,11种目标物在各自的线性范围内线性关系良好,相关系数均大于0.99,定量限为2.0~50.0μg/kg。11种霉菌毒素在3个加标水平(1、2、5倍定量限)下的平均回收率为79.3%~101.6%,相对标准偏差(RSD)为5.9%~13.2%(n=5)。该法简单快速,净化效果好,灵敏度高,适用于饲料中11种霉菌毒素的分析。     

Mean‐square stability of the backward Euler–Maruyama method for neutral stochastic delay differential equations with jumps

This paper is mainly considered whether the mean‐square stability of neutral stochastic delay differential equations (NSDDEs) with jumps is shared with that of the backward Euler–Maruyama method. Under the one‐sided Lipschitz condition and the linear growth condition, the trivial solution of NSDDEs with jumps is proved to be mean‐square stable by using the functional comparison principle and the Barbalat's lemma. It is shown that the backward Euler–Maruyama method can reproduce the mean‐square stability of the trivial solution under the same conditions. The implicit backward Euler–Maruyama method shows better characteristic than the explicit Euler–Maruyama method for the reason that it works without the linear growth condition on the drift coefficient. Compared with some existing results, our results do not need to add extra condition on the neutral part. The conclusions can be applied to NSDDEs and SDDEs with jumps. The effectiveness of the theoretical results is illustrated by an example. Copyright © 2016 John Wiley & Sons, Ltd.     

Robust optimization revisited via robust vector Farkas lemmas

This paper provides characterizations of the weakly minimal elements of vector optimization problems and the global minima of scalar optimization problems posed on locally convex spaces whose objective functions are deterministic while the uncertain constraints are treated under the robust (or risk-averse) approach, i.e. requiring the feasibility of the decisions to be taken for any possible scenario. To get these optimality conditions we provide Farkas-type results characterizing the inclusion of the robust feasible set into the solution set of some system involving the objective function and possibly uncertain parameters. In the particular case of scalar convex optimization problems, we characterize the optimality conditions in terms of the convexity and closedness of an associated set regarding a suitable point.     

Simplified Determination of Organophosphorus Pesticides in Camellia Oil

A rapid, simple, and economical analytical approach has been developed and evaluated for the determination of six organophosphorus pesticides in camellia oil. This method is based on dispersive liquid?liquid microextraction (DLLME) following simple extraction. Oil was extracted with methanol by a high-speed blender and filtered with glass paper to remove fat. The filtrate was incorporated in the DLLME procedure. Acetonitrile was used as the dispersive solvent and chloroform as the extraction solvent. The residues were analyzed by gas chromatography–mass spectrometry. Under the optimized conditions, the recoveries were between 78.4 and 112.8% with relative standard deviations less than 12.3%. The limits of detection for the analytes were from 0.0003 to 0.0056?mg?·?kg^?1. The optimized method was used for the determination of organophosphorus pesticides in camellia oil.     

The enhancing effects of molecule X (X = PH2Cl,SHCl, ClCl) on chalcogen–chalcogen interactions in cyclic trimers Y···Y···X (Y = SHCl,SeHCl)

The enhancing effects of molecule X (X = PH₂Cl, SHCl, ClCl) on S···S and Se···Se chalcogen–chalcogen bonds in the cyclic trimers SHCl···SHCl···X and SeHCl···SeHCl···X were investigated by calculations at the MP2/aug‐cc‐pVTZ level. When molecule X is added to the dimer SHCl···SHCl (SeHCl···SeHCl), cyclic trimers are formed. Compared with the dimer, all the cyclic trimers have shorter S···S (Se···Se) lengths, greater electron densities, negative three‐body interaction energies, and larger second‐order perturbation energies. These results indicate that the addition of molecule X strengthens the original S···S (Se···Se) bond. For the SHCl···SHCl···X cyclic trimers, the S···S bond is strongest in SHCl···SHCl···PH₂Cl, weaker in SHCl···SHCl···SHCl, and weakest in SHCl···SHCl···ClCl. This same trend is observed for the Se···Se bond in SeHCl···SeHCl···X. This means that PH₂Cl provides the greatest enhancement to the S···S (Se···Se) interaction.     

A glassy carbon electrode modified with C-dots and silver nanoparticles for enzymatic electrochemiluminescent detection of glutamate enantiomers

This paper describes an electrochemiluminescent (ECL) based method for chiral recognition and detection of both glutamate (Glu) enantiomers. The luminophore luminol (Lum) was used as both the reductant and stabilizer of Ag nanoparticles (AgNP-Lum) which were combined with carbon quantum dots (C-dots) and placed on a glassy carbon electrode (GCE) along with the enzyme glutamate oxidase (GluOx). The use of these materials is found to result in strong amplification of ECL. The nanomaterials used were characterized by transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The stepwise fabrication of the electrode was verified by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions and by applying a typical potential of 0.6 V, the ECL increases linearly in the 5.0 μM to 5.0 mM Glu concentration range, with a 1.6 μM lower detection limit and satisfactory selectivity. A Glu logic gate idea has been designed that is based on this enzymatic biosensor.

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Graphical abstract Schematic presentation of the electrochemiluminescent (ECL) biosensor. A glassy carbon electrode (GCE) was modified with C-dots and silver nanoparticles which were deoxidized by luminol (AgNP-Lum) for enzymatic specific detection.

     

One-pot synthesis of tricyclo-1,4-benzoxazines via visible-light photoredox catalysis in continuous flow

A facile one-pot synthesis of tricyclo-1,4-benzoxazines has been developed via metal-free intramolecular cyclization of indole derivates. These reactions were efficiently achieved at ambient temperature by using visible-light photoredox catalysis in continuous flow. This directed intramolecular cyclization could be easily handled and scaled up in an open flask, enabling construction of a focused compound library for further pharmacological evaluation.     

Aerobic oxidation of secondary alcohols in water with ABNO/tert-butyl nitrite/KPF6 catalytic system

A green and efficient transition-metal free ABNO/tert-butyl nitrite/KPF₆-catalyzed aerobic oxidation of secondary alcohols in water has been achieved. Under the optimal reaction conditions, a number of secondary aliphatic alcohols and secondary benzylic alcohols can be converted to their corresponding ketones in excellent yields (up to 99%).