超快速液相色谱－三重四极杆－线性离子阱质谱法同时测定桑寄生中多元活性成分

建立了超快速液相色谱－三重四极杆－线性离子阱质谱（UFLC－QTRAP－MS/MS）同时测定桑寄生中黄酮类、有机酸类、核苷类和氨基酸类共33种活性成分含量的方法,并对不同寄主的桑寄生茎枝和叶进行比较分析。通过Box－Behnken响应面法优化供试品制备条件;采用XBridge?C18（4.6 mm × 100 mm,3.5 μm）色谱柱进行分离,以0.1%甲酸水－甲醇为流动相进行梯度洗脱;质谱采用电喷雾离子源（ESI）,以多反应监测（MRM）模式进行检测。结果表明,最佳制备条件为甲醇体积分数70%,液料比（mL∶g）31∶1,提取时间32 min。33种目标成分在相应质量浓度范围内的线性关系良好,相关系数（r）均不低于0.999 0;检出限（LOD）和定量下限（LOQ）分别为0.13 ~ 66.85 ng/mL和0.42 ~ 222.83 ng/mL;平均加标回收率为98.0% ~ 101%,相对标准偏差（RSD）均小于4.0%。所构建的方法准确、稳定,可为桑寄生药材质量的综合评价和全面控制提供新的方法参考,也为桑寄生的合理开发利用提供了依据。     

大气气溶胶吸湿性及其对环境的影响

吸湿性是气溶胶重要的物理化学特性,不仅会影响气溶胶的生命周期和大气行为,还会对大气环境、气候和人体健康产生重要影响。本文简要介绍了气溶胶吸湿参数和热力学模型,对粒径、化学组分以及多组分共存等因素对气溶胶吸湿性的影响进行分析,进一步总结了城市、农村森林和海洋极地等不同区域气溶胶吸湿观测结果。吸湿增长因子g(RH)、散射吸湿增长因子f(RH)和吸湿性参数κ等常用吸湿参数可以衡量气溶胶的吸湿能力;Zdanovskii-Stokes-Robinson(ZSR)混合定律和各种热力学模型能预测不同化学成分气溶胶的吸湿能力,是研究多组分混合气溶胶和气相平衡的重要工具。粒径、化学组分和混合状态影响气溶胶的吸湿性,如气溶胶g(RH)、潮解点或风化点的改变。由于排放源和环境条件的不同,城市、农村、森林、海洋、极地地区气溶胶粒径分布、化学组分和混合状态具有差异,气溶胶吸湿性不同。气溶胶吸湿性直接影响气溶胶含水量和相态,改变气溶胶的大气化学过程、老化过程和大气寿命,还影响环境能见度、辐射效应和在人体内的沉积位置和毒性。通过总结吸湿参数、理论模型、实验室研究、外场观测和环境影响等多方面的最新研究成果,以期为未来的吸湿研究提供参考和借鉴。     

Electrochemical Immunosensor for the Sensitive Detection of Alzheimer's Biomarker Amyloid-β (1–42) Using the Heme-amyloid-β (1–42) Complex as the Signal Source

The amyloid-β peptide (1–42) (Aβ₄₂) can provide high diagnostic accuracy for the early diagnosis of Alzheimer's disease (AD). In this study, an immunosensor based on the peroxidase-like activity of heme-Aβ₄₂ was designed for Aβ₄₂ detection. The glassy carbon electrode (GCE) was electrodeposited Au particles (GCE/Au). The GCE/Au was modified using polythionine-methylene blue (PTH−MB), AuNPs, monoclonal antibody (anti-Aβ₄₂), and bovine serum albumin (BSA), successively. The GCE/Au/PTH−MB/AuNPs/anti-Aβ₄₂/BSA could competitively recognize Aβ₄₂ and heme-Aβ₄₂. The anchored heme-Aβ₄₂ showed strong electrocatalytic activity between H₂O₂ and ferrocenemethanol. Under optimum conditions, we determined detection limits of 17.3 pM in PBS pH 7, 25.2 pM in serum, and 23.8 pM in saliva. The recovery ranged from 71.0 % to 117.8 %.     

Synthesis of Non-precious N-doped Mesoporous Fe3O4/CoO@NC Materials towards Efficient Oxygen Reduction Reaction for Microbial Fuel Cells

N-doped transition metal oxides are strategic materials towards the efficient oxygen reduction reaction (ORR) of microbial fuel cells (MFCs). Non-precious N-doped Fe₃O₄/CoO@NC−T (T represents carbonization temperature) catalysts are prepared by an efficient two-step strategy for ORR. Fe₃O₄/CoO@NC-750 exhibits the best performance with an efficient four-electron transfer pathway. The optimal power density of MFCs by using Fe₃O₄/CoO@NC-750 as the cathode catalyst (1243.4 mW ⋅ m⁻²) is superior to that of the MFCs with commercial Pt/C catalyst (1080 mW ⋅ m⁻²), which shows an outstanding activity towards ORR. No significant decrease in output voltage results over 70 days, which shows an excellent electrochemical stability.     

视觉表征视角下中学化学教科书编排的“三序”结合*——以“物质结构”相关内容为例

教科书的编排有其内在的逻辑结构,视觉表征是教科书的重要组成部分,因此视觉表征的选用也应遵循一定的原则。研究借鉴Gkitzia等人的分析框架对人教版初、高中化学教科书中“物质结构”相关内容的视觉表征进行编码分析。在对表征类型及功能分布分析的基础上,结合教科书中物质结构相关知识内容的编排及学生认知、心理发展规律展开讨论。研究发现,人教版教科书中视觉表征的分布与教科书编排的“三序”原则较为契合,能够针对不同学段、学生特点选用视觉表征。最后,依据研究结论,针对教科书中视觉表征的编选和使用提出建议。     

Design of CuCs-doped Ag-based Catalyst for Ethylene Epoxidation

Our recent theoretical studies have screened out CuCs-doped Ag-based promising catalysts for ethylene epoxidation [ACS Catal. 11 , 3371 (2021)]. The theoretical results were based on surface modeling, while in the actual reaction process Ag catalysts are particle shaped. In this work, we combine density functional theory (DFT), Wulff construction theory, and micro kinetic analysis to study the catalytic performance of Ag catalysts at the particle model. It demonstrates that the CuCs-doped Ag catalysts are superior to pure Ag catalysts in terms of selectivity and activity, which is further proved by experimental validation. The characterization analysis finds that both Cu and Cs dopant promote particle growth as well as particle dispersion, resulting in a grain boundary-rich Ag particle. Besides, CuCs also facilitate electrophilic atomic oxygen formation on catalyst surface, which is benefitial for ethylene oxide formation and desorption. Our work provides a case study for catalyst design by combining theory and experiment.     

One-step low-temperature solid-state synthesis of lead-free cesium copper halide Cs3Cu2Br5 phosphors with bright blue emissions

The development of new efficient and environmental-friendly inorganic phosphors is highly important for phosphor-converted white light-emitting diodes and optoelectronic displays. In this paper, we report a novel and simple one-step solid-state reaction to synthesize lead-free cesium copper halide Cs₃Cu₂Br₅ powders with bright blue emission around 460 nm. The preparation process is performed at low calcination temperatures (290–320 °C) and requires no complex apparatus, reagents, or techniques, and thus it holds great potential for mass production of halide emitters. The Cs₃Cu₂Br₅ powder phosphors are characterized by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence excitation and emission spectroscopy, CIE color coordinates, color purity, photoluminescence quantum yield, and temperature-dependent emission spectra. The effect of calcination temperature on the photoluminescence properties of the as-prepared Cs₃Cu₂Br₅ blue phosphors has been investigated and the air-stability property has also been discussed. Impressively, Cs₃Cu₂Br₅ blue phosphors show outstanding stability toward air exposure exceeding one month (30 days). Our work will open a new and simple approach to obtain excellent halide emitters for future solid-state lighting and displays.     

基于CEEMD特征提取的无绝缘轨道电路补偿电容故障诊断

本文利用电路网络理论和传输线理论构建ZPW-2000A轨道电路传输模型,仿真并分析了补偿电容故障对轨面电压的影响,提出基于互补的总体经验模式分解(CEEMD)特征提取的补偿电容故障诊断方法。实验结果表明,相比于传统经验模式分解(EMD)和总体经验模式分解(EEMD),基于CEEMD特征提取的补偿电容故障诊断方法可以有效地克服EMD方法引起的模态混叠和能量泄露现象,减少EEMD方法在信号重构过程中的白噪声残留,为补偿电容的故障诊断提供了一种快速准确的方法,为保证信号传输质量提供了参考依据。