Simultaneous direct analysis of benzimidazole fungicides and relevant metabolites in agricultural products based on multifunction dispersive solid-phase extraction and liquid chromatography–mass spectrometry

A fast and flexible multi-residue procedure for effective extraction of benzimidazole fungicides and the related transformation products in various raw agricultural commodities is developed for direct and simultaneous analysis by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The new sample preparation method, introduced to allow direct extraction of the labile fungicides as the intact forms in complex matrices, is achieved using a conservative homogenizing extraction and multifunction adsorption cleanup (CHEMAC), which basically involves salting-out partitioning/extraction with acetate-buffered acetonitrile at low-temperature and sequential rapid solid-phase dispersive cleanup with a ternary sorbent mixture. The CHEMAC procedure was optimized and further modified by incorporating several pretreatment variables influencing sample stability and process efficiency, such as pH, temperature, salt and sorbent utilized. By using CHEMAC, a noteworthy improvement in extraction recoveries was obtained for the problematic fungicides, while no significant differential matrix effects were detected on the LC–MS/MS analysis in all 9 matrices. The in-source fragmentation of benomyl occurred but caused no cross-talk interference in multi-component analysis. Thus the CHEMAC-based LC–MS/MS strategy can serve as an attractive approach to satisfactory overall process efficiencies (70–92%) with acceptable repeatability (relative standard deviations below 16%) for all the analyte–matrix combinations. Mean accuracies were obtained within the range of 70–110% at fortified levels of 1–500 ng/g, with intra-day and inter-day variations less than 15 and 20%, respectively. The successful practical application of the proposed method to real samples has also been demonstrated.     

Metabonomic study on women of reproductive age treated with nutritional intervention: screening potential biomarkers related to neural tube defects occurrence

Nutritional intervention is effective in reducing the risk of neural tube defects (NTDs). To determine the effects of nutritional supplementation on human metabolism, a metabonomic study was carried out on 96 women of reproductive age. Subjects with nutritional intervention were given fortified wheat flour (containing folic acid, vitamin B₁, vitamin B₂, ferric sodium edetate and zinc oxide) for 8 months. Serum metabolic fingerprinting was detected via ultraperformance liquid chromatography in tandem with time‐of‐flight mass spectrometry (UPLC‐TOF MS), and data acquired was processed by multivariate statistical analysis. The result revealed a significant difference between the control and intervention group. Twenty potential biomarkers, including fructose 6‐phosphate, sphingosine 1‐phosphate, docosahexaenoic acid and hexadecanoic acid, were located and identified by the accurate mass measurement of TOF MS. These compounds are believed to be functionally related to anti‐oxidative competence in vivo. In conclusion, metabonomics study is a valuable approach in exploring the effect mechanism of nutritional intervention on NTD prevention. Copyright © 2010 John Wiley & Sons, Ltd.     

超促排卵治疗后卵泡破裂合并官外孕一例

一名继发不孕，多囊卵巢病史的妇女接受ＨＭＧ和ＨＣＧ超促排卵治疗后，发生了并发症，即卵泡破裂出血，宫外孕，卵巢过度刺激综合征等。提示进行超促卵治疗时，必须合理使用排卵药及加强监测手段，以促证治疗的安全性。     

Sobolev空间中的几个不等式的推广

本文将Sobolev空间中的Clarkson不等式的几个引理作了适当的推广,并给出了证明.     

Two more pieces of the colibactin genotoxin puzzle from Escherichia coli show incorporation of an unusual 1-aminocyclopropanecarboxylic acid moiety

Colibactin represents a structurally undefined class of bacterial genotoxin inducing DNA damage and genomic instability in mammalian cells, thus promoting tumour development and exacerbating lymphopenia in animal models. The colibactin biosynthetic gene cluster (clb) has been known for ten years and it encodes a hybrid nonribosomal peptide synthetase (NRPS)/polyketide synthase (PKS) assembly line. Nevertheless, the final chemical product(s) remain unknown. Previously, we and others reported several colibactin pathway-related metabolites including N-myristoyl-d-asparagine (1) as part of a prodrug precursor that is cleaved from the putative precolibactin to form active colibactin by the peptidase ClbP. Herein, we report two new colibactin pathway-related metabolites (2 and 3) isolated from a clbP mutant of the probiotic E. coli Nissle 1917 strain. Their structures were established by HRMS and NMR. Compound 2 shows an additional 4-aminopenatanoic acid moiety with respect to 1, while 3 is characterized by the presence of an unusual 7-methyl-4-azaspiro[2.4]hept-6-en-5-one residue. Moreover, we propose the biosynthetic pathway towards both intermediates on the basis of extensive gene inactivation and feeding experiments. The identification of 2 and 3 provides further insight into colibactin biosynthesis including the involvement and formation of a rare 1-aminocyclopropanecarboxylic acid unit. Thus, our work establishes additional steps of the pathway forming the bacterial genotoxin colibactin.     

La(Ⅲ)-乙醇溶液微团簇理论和光谱研究

利用分子光谱和基于密度泛函理论的第一性原理,采用改进的TPSSTPSS泛函方法对C、H、O原子用6-31G基组并添加极化和弥散函数,对La原子选用Def2-SV(P)赝势基组,研究La3+/乙醇溶液微团簇构型。优化计算La3+在水溶液中的溶剂化结构,得出气相中的优化结果可以近似代替液相结果的结论;理论优化计算La3+/乙醇溶液可能存在的结构构型的结果表明,溶剂化数n=6时结构最稳定。采用荧光光谱和核磁共振实验对结果进行了验证,表明La3+的加入使荧光强度显著增强,在高浓度时生成的团簇构型比较稳定,且随着溶剂化数目的增加,O—H键长增大,La3+使其附近的质子产生强大的屏蔽效应,化学位移向高场移动,溶剂化数n=6时绝对误差最小,最稳定,与理论计算结论相吻合。     

Non‐Covalent Functionalization of Graphene with Bisphenol A for High‐Performance Supercapacitors

The reduced graphene oxide (RGO)/bisphenol A (BPA) composites were prepared by an adsorption‐reduction method. The composites are characterized by X‐ray diffraction (XRD), UV‐vis, thermogravimetric (TG) analysis, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM). The results confirm that BPA is adsorbed on the basal plane of RGO by π‐π stacking interaction. Furthermore, the electrochemical behaviors were evaluated by cyclic voltammetry, galvanostatic charge/discharge techniques and electrochemical impedance spectroscopy (EIS). The results show that the RGO/BPA nanocomposites exhibit ultrahigh specific capacitance of 466 F·g^?1 at a current density of 1 A·g^?1, excellent rate capability (more than 81% retention at 10 A·g^?1 relative to 1 A·g^?1) and superior cycling stability (90% capacitance decay after 4000 cycles). Consequently, the RGO/BPA nanocomposites can be regarded as promising electrode materials for supercapacitor applications.     

DMSO作为新的合成子在有机合成中的应用研究进展

二甲亚砜(DMSO)不但可以作为有机溶剂,同时还可以作为反应试剂,在有机合成中得到了广泛的应用.由于其具有来源广、价格低廉、操作简单等优点,近年来将DMSO作为反应试剂应用于有机合成反应引起了广大化学家的关注.本文作者对近几年来DMSO作为合成子在有机合成中的应用按照引入官能团的种类进行了总结,详细阐述了其转化为甲磺酰基、甲酰基、氰基、甲硫基等官能团的方法学研究,以期为开发DMSO新的应用提供参考依据.     

Synthesis and Crystal Structure of Rare Earth Metal Chlorides Bearing Bridged-Indenyl Ancillary Ligand

Two new rare earth metal chloride complexes supported by a bridged‐indenyl ancillary ligand, [C₉H₆SiMe₂‐ (CH₂)₂SiMe₂C₉H₆]Ln(µ‐Cl)₂Li(TMEDA) [Ln=Y ( 1 ), Lu ( 2 )], were synthesized via salt metathesis reaction. Reaction of C₉H₇SiMe₂(CH₂)₂SiMe₂C₉H₇ with 2 equiv. of n‐butyllithium in hexane at room temperature afforded [C₉H₆SiMe₂‐ (CH₂)₂SiMe₂C₉H₆]Li₂ as white powder in 95% isolated yield. Further treatment of [C₉H₆SiMe₂(CH₂)₂SiMe₂‐ C₉H₆]Li₂ with anhydrous LnCl₃ in 1:1 molar ratio in THF/TMEDA at room temperature provided the bridged‐indenyl rare earth metal chlorides 1 and 2 in 86%–89% isolated yields. Both complexes were characterized by FT‐IR spectroscopy, NMR spectroscopy, elemental analysis, and X‐ray single crystal structure analysis. The central metals in both complexes are eight‐coordinated by two indenyl ligands in η⁵‐fashion, and two chlorine atoms to adopt a distorted tetrahedral geometry.