高效液相色谱-四极杆/飞行时间质谱鉴定阿莫西林克拉维酸钾干混悬剂中的未知组分

采用高效液相色谱-四极杆/飞行时间质谱(HPLC-QTOF/MS)建立了阿莫西林克拉维酸钾混悬剂(ACPS)中未知组分的鉴定方法,以BDS Hypersil C18(4.6 mm×250 mm,5μm)为色谱柱,以乙腈-水(0.1%甲酸)为流动相,流速为1 mL/min。比较了中国药典方法和HPLC-QTOF/MS方法的相关性;利用半制备液相色谱收集未知组分,并在HPLC-QTOF/MS体系中进行定位和确认,确定未知组分在液质体系中的出峰位置和准确分子量;筛查混合空白辅料成分,并通过与标准品比对,利用HPLC-QTOF/MS鉴定ACPS的未知组分为糖精钠。方法可为抗生素药品中未知组分的鉴定提供参考。     

CO2-水-页岩相互作用的研究现状及展望

简要综述了CO2、水和页岩间矿物的相互作用,分析了CO2注入到地下进入页岩层后,地下含水层pH值的变化,并根据页岩层的矿物学组成分为黏土矿物和脆性矿物,较为详细地描述了CO2与黏土矿物和脆性矿物之间发生的地球化学反应,概述了此反应对页岩层孔隙度和渗透率的影响。同时,也讨论了CO2增强页岩气开采的现实问题及发展趋势,为今后的研究提供了参考。     

Circumvent PEGylation dilemma by implementing matrix metalloproteinase-responsive chemistry for promoted tumor gene therapy

Surface modification by poly(ethylene glycol) (PEGylation) has been acknowledged as a powerful strategy in minimizing non-specific reactions for biomedical devices. Once applied into manufacture of drug/gene delivery systems, PEGylation has demonstrated to significantly improve their biocompatibility and stealthiness in physiological environment. Nonetheless, reluctant cell membrane affinities thus cellular uptake efficiencies owing to PEGylation brought up further issues that are imperative to be resolved. Pertain to this PEGylation dilemma, we attempted to introduce peptide (GPLGVRG) linkage between block copolymer of PEG-poly{N'-[N-(2-aminoethyl)-2-aminoethyl]aspartamide} PAsp(DET), wherein the cationic PAsp(DET) could self-assemble with pDNA into nanoscaled complex core. Noteworthy was the peptide linkage whose amino acids sequence could be specifically recognized and degraded by matrix metalloproteinases (MMPs) (overexpressed in extracellular milieu of tumors). Therefore, our subsequent studies validated facile detachment of PEGylation from the aforementioned polyplex micelles upon treatment of MMPs, which elicited improved cytomembrane affinities and cellular uptake efficiencies. In addition, promoted escape from endosome entrapment was also confirmed through direct endosome membrane destabilization by PAsp(DET), which was further elucidated to be attributable to dePEGylation as well as elevated charged density of PAsp(DET) in acidic endosomes. These benefits from dePEGylation eventually contributed to promoted gene expression at the affected cells and potent tumor growth suppression based on anti-angiogenic approach. Therefore, our developed strategy has provided a facile approach in overcoming the dilemma of PEGylation, which could be informative in design of drug/gene delivery systems.     

手持技术数字化实验支持下的化学概念教学研究进展*

以“中国知网”数据库发表的手持技术数字化实验支持下的化学概念教学研究主题的期刊论文为研究对象,使用内容分析法,从概念选取、应用价值、应用策略等3个维度综述手持技术数字化实验支持下的化学概念教学的研究进展。最后,基于已有研究,得出相应启示,并提出该领域的研究展望。     

Thermodynamically Favourable States in the Reaction of Nitrogenase without Dissociation of any Sulfide Ligand

We have used combined quantum mechanical and molecular mechanical (QM/MM) calculations to study the reaction mechanism of nitrogenase, assuming that none of the sulfide ligands dissociates. To avoid the problem that there is no consensus regarding the structure and protonation of the E₄ state, we start from a state where N₂ is bound to the cluster and is protonated to N₂H₂, after dissociation of H₂. We show that the reaction follows an alternating mechanism with HNNH (possibly protonated to HNNH₂) and H₂NNH₂ as intermediates and the two NH₃ products dissociate at the E₇ and E₈ levels. For all intermediates, coordination to Fe6 is preferred, but for the E₄ and E₈ intermediates, binding to Fe2 is competitive. For the E₄, E₅ and E₇ intermediates we find that the substrate may abstract a proton from the hydroxy group of the homocitrate ligand of the FeMo cluster, thereby forming HNNH₂, H₂NNH₂ and NH₃ intermediates. This may explain why homocitrate is a mandatory component of nitrogenase. All steps in the suggested reaction mechanism are thermodynamically favourable compared to protonation of the nearby His-195 group and in all cases, protonation of the NE2 atom of the latter group is preferred.     

Zeolitic imidazolate framework-8 as a dispersive solid phase extraction sorbent for simultaneous determination of 145 pesticide residues in polyphenol-rich plants

Many plants have a high polyphenol content, which causes the matrix effect and makes the analysis of trace pesticide residues highly challenging. A common approach to improving matrix effects is to purify pesticides through the use of sorbents, but this requires a combination of multiple sorbents and extensive use. Zeolitic imidazolate framework-8 is widely used for pesticide analysis due to its high porosity, large specific surface area, and versatility. Here, we established and validated a modified quick, easy, cheap, effective, rugged, and safe method based on a zeolitic imidazolate framework-8 that was used to test the removal ability for polyphenols. To this end, 145 pesticide residues in peppermint, perilla, fennel, and mulberry leaves were analyzed by the modified method coupled with liquid chromatography with tandem mass spectrometry. The mean recoveries of all pesticide residues were in the range of 74.3–103.7%, with mean relative standard deviations ≤9.1% at spiked concentrations of 1, 10, 50, and 100 μg/kg for mulberry leaves. The limits of quantitation of the method ranged from 1 to 50 μg/kg. This study offers a reliable approach for the accurate quantitative analysis of various trace substances in the polyphenol-rich plants.     

氰基衍生化制备胺的研究进展

胺是有机分子中最常见且重要的结构之一,广泛存在于天然产物分子、药物、染料、塑料等的分子结构中,开发合成胺的有效方法在化学工业中具有很高的需求但仍充满挑战。在诸多已知有机胺的合成方法中,以氰基为前体还原衍生化制备胺被认为是一条原子经济且绿色可行的方案。然而,氰基中存在稳定的碳氮三重键,还原过程涉及较多中间体,而部分中间体活性比氰基更高,因此反应受还原剂、催化剂、反应条件的影响很大,由氰基选择性制备目标胺结构仍充满挑战。本文从氰基的基本电子结构与反应活性出发,综述了近年来以氰基为原料的官能团胺基化反应,对部分重要反应的催化剂和反应机理做了简要讨论,为设计氰基制胺催化剂和应用工艺提供了新的视角。     

Preparation and Characterization of Polyborosiloxanesand Their Blends with Phenolic Resin as ShapeableCeramic Precursors简

Two polyborosiloxanes(PBSis) with char yield up to 74.13% at 800 °C were synthesized by the direct polycondensation of boric acid with phenyltrimethoxysilane in diglyme. The PBSis were characterized by gel permeation chromatography, IR spectroscopy as well as1H-,29Si- and11B-NMR. PBSi modified phenol-formaldehyde resins(PBSi/PFs) were prepared at different PBSi/PF mass ratios and were cured at 150 °C. The PBSi/PFs were characterized by IR spectroscopy, scanning electron microscopy, thermogravimetric analysis and tensile test. The results revealed that the cured PBSi/PFs had sea-island morphology and higher char yield than the common PF. PBSi/PF blend with PBSi/PF mass ratio of 0.4:1 had char yield up to 70.83% at 800 °C. The PBSi/PFs had tensile strength similar to PF. The ceramization of PBSi/PFs was also studied. The silicon boron oxycarbide(SiBOC) ceramics formed were characterized by IR spectroscopy and elemental analysis. This method provided a valuable way to prepare easily shapeable polymer blends as ceramic precursors.     

Crystal structures and electrochemical properties of two Mn(II) 2-sulfoterephthalate complexes with N-donor ligands

Two Mn(II) sulfoterephthalate complexes, [Mn(HStp)(o-Phen)₂] (I) and [Mn(HStp)(2,2′-Bipy)₂] (II) (H₃Stp = 2-sulfoterephthalic acid, o-Phen = 1,10-phenanthroline, 2,2′-Bipy = 2,2′-bipyridine), were synthesized under hydrothermal condition. Single crystal X-ray diffraction analyses reveal that complexes I and II possess similar structure, in which the center Mn²⁺ ions are hexa-coordinated with one Hstpanion and two N-donor ligands. For both of them, the formation of 3D supramolecular structures are based on both H-bonds and π...π/C-H...π stacking interactions. Electrochemical properties of complexes I and II have been investigated by means of cyclic voltmetry, which shows that electron transfer between Mn(III) and Mn(II) in electrolysis is quasi-reversible process.     

CdS/SiO2纳米复合材料的合成及光学性能

以合成的丙氨酸镉为纳米粒子的前驱体,在不加酸或碱性催化剂的条件下,利用丙氨酸镉分子中的胺基催化硅氧烷水解缩合生成二氧化硅,同时将丙氨酸镉均匀地引入到二氧化硅的内部,通过硫化原位生成硫化镉纳米颗粒,制得硫化镉/二氧化硅(CdS/SiO2)纳米复合材料.用傅里叶变换红外光谱、核磁共振氢谱、紫外-可见光谱、荧光显微镜和透射电子显微镜等方法对CdS/SiO2复合材料进行表征,结果表明,硫化镉粒子均匀分布在二氧化硅内部,使其具有良好的荧光特性.