Insight mechanism of nano iron difluoride cathode material for high-energy lithium-ion batteries: a review

Journal of Solid State Electrochemistry - Iron(II) fluoride (FeF2) is a promising candidate as the cathode material for lithium-ion batteries (LIBs) due to its quite high theoretical energy density...     

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.     

Extraction of parabens by melamine sponge with determination by high-performance liquid chromatography

In the present study, we propose a novel method for the extraction of parabens in personal care products. A new, simple adsorptive material was obtained by combining metal-organic frameworks and melamine sponges using the adhesive property of polyvinylidene fluoride. This new material, metal-organic frameworks/melamine sponges, was found to be particularly suitable for solid-phase extraction. The structural characteristics of metal-organic frameworks/melamine sponges were first analyzed by scanning electron microscopy. Subsequently, solid-phase extraction was performed on sample solutions, and the extracted substances were then analyzed by high-performance liquid chromatography. Following optimization of important experimental conditions, excellent recovery rates were obtained. Our novel method was then applied to the extraction of four parabens (methylparahydroxybenzoates, ethylparahydroxybenzoates, propylparahydroxybenzoates, and butylparahydroxybenzoates) from real samples. The results yielded limits of detection of 0.26–0.41 ng/mL. The inter- and intra-day recoveries were 104.0–109.7% and 91.2–98.1%, respectively (relative standard deviation, <13.8%).     

2,7-二芳基呫吨螺芴二醇衍生物的合成

以2,7-二溴-9-芴酮、间苯二酚和苯硼酸的衍生物为原料,经过环化、羟乙基化和Suzuki偶联等3步反应,设计并合成了一系列2,7-芳基呫吨螺芴二醇衍生物,通过红外光谱、核磁光谱（¹H NMR, ¹³C NMR）、元素分析等表征了化合物的结构。折光率和紫外可见光谱测试结果表明:与2,7-无取代基的呫吨螺芴二乙醇衍生物相比,目标化合物具有更高的折光率(1.66~1.68)和良好的透光率,有望作为聚碳酸酯光学树脂的二醇单体,应用于光学透镜、光学膜等领域。     

狄尔斯-阿尔德反应催化剂

狄尔斯-阿尔德(Diels-Alder)可以构建结构丰富的有机化合物,被认为是现代有机化学中的基石反应之一。自1928年被发现以来,Diels-Alder (D-A)反应得到了深入发展,这主要是由于该反应能够产生六元环结构,可以一步反应得到具有四个立体中心的产物,从而大大增加分子的复杂性。这种特殊的转化已广泛应用于复杂天然产物的合成、药物化学以及材料科学等领域。近十年,大量天然生物酶(如SpnF、MaDA等)被发现可用于体外单独催化D-A反应,同时,大量的非酶催化剂(如路易斯酸、过渡金属与配体复合物等)也被应用于催化D-A反应。本文主要从D-A反应催化剂的类型分类,对近年来天然酶、酸、过渡金属、电催化等参与的D-A反应进行简要概述,同时对催化剂所存在的问题和局限性进行总结,并对今后发展做了展望。     

洗涤用品质量安全检测技术研究进展

洗涤用品是日常使用的产品,其质量安全受到广大消费者的关注。洗涤用品中可能存在的化学风险物质,将对消费者的健康安全产生负面影响。为了减少和避免洗涤用品质量安全问题,研究人员采用多种分析测试技术,开发、建立了洗涤用品中化学风险物质的检测方法。该文综述了近年来洗涤用品质量安全检测技术的研究进展,以期为相关领域的科技人员提供理论支持和技术参考。     

Mixed Quantum Classical Reaction Rates based on the Phase Space Formulation of the Hierarchical Equations of Motion

In a previous work [J. Chem. Phys. 140 , 174105 (2014)], we have shown that a mixed quantum classical (MQC) rate theory can be derived to investigate the quantum tunneling effects in the proton transfer reactions. However, the method is based on the high temperature approximation of the hierarchical equation of motion (HEOM) with the Debye-Drude spectral density, and results in a multi-state Zusman type of equation. We now extend this theory to include quantum effects of the bath degrees of freedom. By writing the full HEOM into a multidimensional partial differential equation in phase space, we can define a new reaction coordinate, and the previous method can be generalized to the full quantum regime. The validity of the new method is demonstrated by using numerical examples, including the spin-Boson model, and the double well model for proton transfer reaction. The new method is found to resolve some key problems of the previous theory based on high temperature approximation, including possible numerical instability in long time simulation and wrong rate constant at low temperatures.     

Micro-CT参数对骨质疏松性椎体压缩性骨折术后复发的预测价值

本研究探讨Micro-CT参数对骨质疏松性椎体压缩性骨折(OVCF)患者术后复发的预测价值。选取OVCF患者127例,根据术后6个月骨折复发情况分为复发组(n=41)与未复发组(n=86)。患者均接受Micro-CT检查,对比两组Micro-CT参数,即骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁间隙(Tb.Sp)、结构模型指数(SMI),以及骨密度(BMD)、骨矿含量(BMC),分析各参数与BMD、BMC及术后复发相关性,并评价各参数对术后复发的预测价值。结果显示,复发组骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)低于未复发组,骨小梁间隙(Tb.Sp)、结构模型指数(SMI)高于未复发组(P<0.05);BV/TV、Tb.Th与骨密度(BMD)、骨矿含量(BMC)呈正相关,Tb.Sp、SMI与BMD、BMC呈负相关(P<0.05);将年龄、BMD、BMC等其他因素控制后,BV/TV、Tb.Sp、Tb.Th、SMI与OVCF术后骨折复发显著相关(P<0.05);BV/TV、Tb.Sp、Tb.Th、SMI联合预测OVCF术后骨折复发的曲线下面积(AUC)最大,为0.888(P<0.05)。提示Micro-CT参数在OVCF患者中呈异常表达,采用Micro-CT检查可为临床预测OVCF术后骨折复发提供科学指导。     

Comparative Analysis of Hydration Layer Reorientation Dynamics of Antifreeze Protein and Protein Cytochrome P450

Antifreeze proteins (AFPs) inhibit ice recrystallization by a mechanism remaining largely elusive. Dynamics of AFPs' hydration water and its involvement in the antifreeze activity have not been identified conclusively. We herein, by simulation and theory, examined the water reorientation dynamics in the first hydration layer of an AFP from the spruce budworm, Choristoneura fumiferana, compared with a protein cytochrome P450 (CYP). The increase of potential acceptor water molecules around donor water molecules leads to the acceleration of hydrogen bond exchange between water molecules. Therefore, the jump reorientation of water molecules around the AFP active region is accelerated. Due to the mutual coupling and excitation of hydrogen bond exchange, with the acceleration of hydrogen bond exchange, the rearrangement of the hydrogen bond network and the frame reorientation of water are accelerated. Therefore, the water reorientation dynamics of AFP is faster than that of CYP. The results of this study provide a new physical image of antifreeze protein and a new understanding of the antifreeze mechanism of antifreeze proteins.