Determination of phthalate esters in edible oils by use of QuEChERS coupled with ionic-liquid-based dispersive liquid–liquid microextraction before high-performance liquid chromatography

A selective and low organic-solvent-consuming method of sample preparation combined with high-performance liquid chromatography with diode-array detection is introduced for analysis of phthalic acid esters in edible oils. Sample treatment involves initial liquid–liquid partitioning with acetonitrile, then QuEChERS cleanup by dispersive solid-phase extraction with primary secondary amine as sorbent. Preconcentration of the analytes is performed by ionic-liquid-based dispersive liquid–liquid microextraction, with the cleaned-up extract as disperser solvent and 1-hexyl-3-methylimidazolium hexafluorophosphate as extraction solvent. Under the optimized conditions, correlation coefficients (r) were 0.998–0.999 and standard errors (S _y/x ) were 2.67–3.37?×?10³ for calibration curves in the range 50–1000 ng g^?1. Detection limits, at a signal-to-noise ratio of 3, ranged from 6 to 9 ng g^?1. Intra-day and inter-day repeatability, expressed as relative standard deviation, were in the ranges 1.0–6.9 % and 2.4–9.4 %, respectively. Recovery varied between 84 % and 106 %. The developed method was successfully used for analysis of the analytes in 28 edible oils. The dibutyl phthalate content of four of the 28 samples (14 %) exceeded the specific migration limit established by domestic and international regulations.

Fluorocarbon and Hydrocarbon N‐Heterocyclic (C5–C7) Imidazole‐Based Liquid Crystals

By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals (LCs) and related imidazolium‐based ionic liquid crystals (ILCs) have been prepared. The ring size of the N‐heterocycle and the length of the N‐terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid‐crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole‐based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based LCs and related imidazolium‐based ILCs could be used as new liquid‐crystalline materials.     

电极电势:从电化学势说起*

对于原电池,电极电势的本质是化学体系对电极材料上电子势能的影响,其正负极电势差反映化学能向电能转化的趋势。电极界面上化学物质的氧化/还原反应是通过何种途径影响到电极上电子势能的,现有的教材和论著没有给出明确的解释。本文基于相间电化学势平衡原则阐明了固液界面上离子平衡与电极上电子电势的关系,并由此给出了标准电势的物理含义:它是构成电极体系一系列物性参数的组合,包括被测电极的电子、离子化学势,工作电极电解液的离子化学势,参比电极的电子、离子化学势和参比电极电解液的离子化学势等。     

有机催化吲哚碳环上的不对称Friedel⁃Crafts烷基化反应

将金鸡纳碱衍生物双功能催化剂用于有机催化羟基吲哚与靛红的不对称Friedel-Crafts反应, 筛选出最佳反应条件: 催化剂为5%(摩尔分数)6′-脱甲基奎尼丁(1b), 溶剂为四氢呋喃, 反应温度 0 ℃. 以67%~91%的产率和最高达97%的对映选择性获得了苯环上取代的羟基烷基化产品. 拓宽了该反应的催化剂类型和底物范围.     

Gamma spectrum analysis for in situ automatic monitoring of radioactivity in seawater

The NaI(Tl) detector has been an important research topic and application in the field of in situ marine radioactive automatic monitoring because of its advantages of low power consumption, low cost, and good efficiency. However, its energy resolution is not high enough. This paper investigated an analytical method: spectrum de-noising, background correction based on the SNIP operator, peak search based on the top-hat transform and peak fitting using Gaussian distribution. Simulation and gamma spectra measured from seawater showed that the established energy spectrum analysis method presents satisfactory automatic analytical ability for identification and quantitatively analysis.

     

蚕丝基智能纤维及织物：潜力、现状与未来展望

纤维及织物因具有良好的柔性、透气性以及适宜的力学性能而成为人们日常生活必不可少的材料。随着柔性电子器件的快速发展,纤维及织物在其自身优势的基础上,开始被人们赋予智能化特征,使得智能纤维和织物逐渐在可穿戴领域占据一席之地。天然蚕丝具有产量大、机械性能优异和生物可降解的优势。近年来,面向智能应用的蚕丝基纤维与织物逐渐发展,被用于传感、致动、光学器件、能量收集和储能等领域。本文将首先介绍天然蚕丝的层级结构和性能,并介绍各种形貌结构的再生蚕丝材料;然后根据其在智能纤维及织物中应用领域的不同,详细阐述蚕丝基智能纤维及织物的制备方法、性能及工作机制;最后讨论进一步发展所面临的挑战与机会,并对未来前景进行展望。     

A Highly Sensitive and Selective Label-free Electrochemical Biosensor with a Wide Range of Applications for Bisphenol A Detection

A label-free DNA-based electrochemical biosensor owning high sensitivity and selectivity has been established for detecting bisphenol A in a wide range of applications. Coupling the high electrochemical performance of graphene oxide-thionine-Au nanomaterial with the specific binding capacity of the aptamers to BPA, the monitoring of trace amount of BPA was realized, the detection limit was 3.3 pg ⋅ mL⁻¹ with strong anti-interference. Besides, using molecular docking, it was found that BPA binds to the bases DC-49, DC-51, DG-52, DG-53 and DA-63 on the aptamer via hydrogen bonding and π-π stacking interactions. Finally, the biosensor had been successfully applied in different real samples.     

Exploring Effects of Chitosan Oligosaccharides on the DSS-Induced Intestinal Barrier Impairment In Vitro and In Vivo

Intestinal barrier dysfunction is an essential pathological change in inflammatory bowel disease (IBD). The mucus layer and the intestinal epithelial tight junction act together to maintain barrier integrity. Studies showed that chitosan oligosaccharide (COS) had a positive effect on gut health, effectively protecting the intestinal barrier in IBD. However, these studies usually focused on its impact on the intestinal epithelial tight junction. The influence of COS on the intestinal mucus layer is still poorly understood. In this study, we explored the effect of COS on intestinal mucus in vitro using human colonic mucus-secreted HT-29 cells. COS relieved DSS (dextran sulfate sodium)-induced mucus defects. Additionally, the structural characteristics of COS greatly influenced this activity. Finally, we evaluated the protective effect of COS on intestinal barrier function in mice with DSS-induced colitis. The results indicated that COS could manipulate intestinal mucus production, which likely contributed to its intestinal protective effects.     

Size-controllable carbon spheres doped Ni (II) for enhancing the catalytic oxidation of methanol

Ni(II)/CSs were prepared using a simple two-step hydrothermal method. The morphology and composition of the catalysts were studied with scanning electron microscope, transmission electron microscope, and X-ray diffraction. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed that the surface of the prepared carbon spheres was rich in hydroxyl groups, which was beneficial to remove CO intermediates, and therefore, improving the catalytic efficiency and the antipoisoning ability of the catalysts. The results of cyclic voltammetry and chronoamperometry showed that the electrocatalytic activity and stability of Ni(II)/CSs were higher than that of unloaded NiAc under alkaline environment. When the nickel content was 5 wt.%, the peak oxidation current density of methanol on Ni(II)/CSs electrocatalyst reached the maximum of 34.54 mA/cm², which was about 1.8 times that of unloaded NiAc. These results indicate that Ni(II)/CSs has potential applications in the electrocatalytic oxidation of methanol.     

In situ vaccination and gene-mediated PD-L1 blockade for enhanced tumor immunotherapy

Despite of the promising achievements of immune checkpoints blockade therapy (ICB) in the clinic, which was often limited by low objective responses and severe side effects. Herein, we explored a synergistic strategy to combine in situ vaccination and gene-mediated anti-PD therapy, which was generated by unmethylated cytosine-phosphate-guanine (CpG) and pshPD-L1 gene co-delivery. PEI worked as the delivery carrier to co-deliver the CpG and pshPD-L1 genes, the formed PDC (PEI/DNA/CpG) nanoparticles were further shielded by aldehyde modified polyethylene glycol (OHC-PEG-CHO) via pH responsive Schiff base reaction for OHC-PEG-CHO-PEI/DNA/CpG nanoparticles (P(PDC) NPs) preparation. All steps could be finished within 30 min. Such simple nanoparticles achieved the synergistic antitumor efficacy in B16F10 tumor-bearing mice, and the amplified T cell responses, together with enhanced NK cells infiltration were observed after the combined treatments. In addition, the pH responsive delivery system reduced the side effects triggered by anti-PD therapy. The facile and effective combination strategy we presented here might provide a novel treatment for tumor inhibition.