Pyrolytic Carbon‐coated Cu‐Fe Alloy Nanoparticles with High Catalytic Performance for Oxygen Electroreduction

Well‐dispersed carbon‐coated or nitrogen‐doped carbon‐coated copper‐iron alloy nanoparticles (FeCu@C or FeCu@C?N) in carbon‐based supports are obtained using a bimetallic metal‐organic framework (Cu/Fe‐MOF‐74) or a mixture of Cu/Fe‐MOF‐74 and melamine as sacrificial templates and an active‐component precursor by using a pyrolysis method. The investigation results attest formation of Cu?Fe alloy nanoparticles. The obtained FeCu@C catalyst exhibits a catalytic activity with a half‐wave potential of 0.83 V for oxygen reduction reaction (ORR) in alkaline medium, comparable to that on commercial Pt/C catalyst (0.84 V). The catalytic activity of FeCu@C?N for ORR (E_half‐wave=0.87 V) outshines all reported analogues. The excellent performance of FeCu@C?N should be attributed to a change in the energy of the d‐band center of Cu resulting from the formation of the copper–iron alloy, the interaction between alloy nanoparticles and supports and N‐doping in the carbon matrix. Moreover, FeCu@C and FeCu@C?N show better electrochemical stability and methanol tolerance than commercial Pt/C and are expected to be widely used in practical applications.     

Simultaneous determination of major components of Huangqi–Honghua extract in rat plasma using LC–MS/MS and application to a pharmacokinetic study

A sensitive and reliable LC–MS/MS method was developed and validated for simultaneous quantification of the major components of Huangqi–Honghua extact in rat plasma, including hydroxysafflor yellow A (HSYA), astragaloside IV (ASIV), calycosin‐7‐O‐β‐d ‐glucoside (CAG), calycosin, calycosin‐3′‐O‐glucuronide (C‐3′‐G) and calycosin‐3′‐O‐sulfate (C‐3′‐S). After extraction by protein precipitation with acetonitrile and methanol from plasma, the analytes were separated on a Hypersil BDS C₁₈ column by gradient elution with acetonitrile and 5 mM ammonium acetate. The detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source switched between negative and positive modes. HSYA was monitored in negative ionization mode from 0 to 4.9 min, and ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S were determined in positive ionization mode from 4.9 to 10 min. The lower limits of quantification of the analytes were 6.25 ng/mL for HSYA, 0.781 ng/mL for CAG and 1.56 ng/mL for ASIV and calycosin. The intra‐ and inter‐assay precision (RSD) values were within 13.43%, and accuracy (RE) ranged from ?8.75 to 9.92%. The validated method was then applied to the pharmacokinetic study of HSYA, ASIV, CAG, calycosin, C‐3′‐G and C‐3′‐S in rat after an oral administration of Huangqi–Honghua extract.     

Room temperature suzuki cross‐coupling polymerizations of aryl dihalides and aryldiboronic acid/acid esters with t‐Bu3P‐coordinated 2‐phenylaniline‐based palladacycle complex as the precatalyst

Room temperature Suzuki cross‐coupling polymerization of aryl dibromides/diiodides with aryldiboronic acids/acid esters with t‐Bu₃P‐coordinated 2‐phenylaniline‐based palladacycle complex, [2′‐(amino‐kN)[1,1′‐biphenyl]‐2‐yl‐kC]chloro(tri‐t‐butylphosphine)palladium, as a general precatalyst is described. Such room temperature Suzuki cross‐coupling polymerization is achieved by employing six equivalents or more of the base and affords polymers within an hour, with the yields and the molecular weights in general comparable to or higher than reported results that required higher reaction temperature and/or longer polymerization time. Our study provides a general catalyst system for the room temperature Suzuki cross‐coupling polymerization of aryl dibromides/diiodides with aryldiboronic acids/acid esters and paves the road for the investigation of employing other monodentate ligand‐coordinated palladacycle complexes including other electron‐rich monophosphine‐coordinated ones for room temperature cross‐coupling polymerizations. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1606–1611     

短孔道Pt/W-s-SBA-15催化剂的合成及甘油催化氢解制1,3-丙二醇性能的研究

合成了孔道平行于短轴方向的W原位掺杂的介孔SBA-15分子筛(W-s-SBA-15), 以其为载体制备了Pt/W-s-SBA-15催化剂, 考察了催化剂中Pt、W负载量变化对甘油氢解制1,3-丙二醇(1,3-PDO)性能的影响. 采用多种手段对催化剂的形貌、活性组分Pt和W的存在状态、催化剂的酸性等性质进行了系统的表征. 催化剂评价结果表明, 随着Pt、W负载量的增加, 甘油的总转化率和液相转化率(CTL)提高, 而1,3-PDO选择性呈先升高后降低的火山型变化趋势. 在Pt负载量为4.0 wt%、W/Si物质的量比为1/480的4Pt/W-s-SBA-15(1/480)催化剂上, 在433 K、H₂压力4.0 MPa、反应时间24 h的条件下, 甘油氢解制1,3-PDO的得率可达49.0%. 根据表征结果, 我们发现在Pt/W-s-SBA-15催化剂上的甘油转化率与Pt活性比表面积直接相关, 而小的Pt粒径、Pt与单分散WO₄之间密切的协同作用, 则有助于提高1,3-PDO的选择性.     

Coaxial electrospinning core-shell fibers for self-healing scratch on coatings

Polystyrene (PS) fibers with core-shell structure were prepared by coaxial electrostatic spinning using liquid epoxy or curing agent as the core and PS solution as the shell. Scratch self-healing coatings were realized by using the healant-loaded core-shell fibers in the matrix.     

含钼化合物及其配合物的抗癌抗肿瘤活性

钼是生命体所必需的微量元素。本文介绍了钼在人体中的作用，钼缺乏和钼过量对人体的影响，并介绍了含钼化合物以及配合物的抗癌抗肿瘤研究情况。     

液体和非晶态Ni64B36合金结构的从头算分子动力学模拟

运用从头算分子动力学模拟了液体以及猝冷后形成的非晶态Ni₆₄B₃₆合金体系, 得到了它们的对相关函数、结构因子、键对分析方面的结构信息, 与实验结果相当一致; 结果表明, 猝冷得到的合金性质与液体合金性质相似, 为非晶态结构. B原子多数以B—B双原子成键形式分散于Ni原子构成的骨架中. 电子态密度分析表明, Ni 3d电子最活泼, 因此在合金中Ni为活性位. 轨道电荷分析从电子结构角度揭示了在NiB 催化剂中B作为修饰剂的机理.     

自主开发多媒体课件进行原子吸收光谱法教学

介绍采用Flash、PowerPoint软件制作原子吸收光谱仪的教学动画片,以解决教学中大型分析仪器不足的问题。     

羧甲基纤维素对某些碱性吖啶染料的褪色作用及其分析应用

在近中性至弱碱性介质中,羧甲基纤维素钠(CMC)由于多个羧基离解而以大阴离子状态存在,它能与吖啶黄(AY)或吖啶橙(AO)阳离子借静电引力和疏水作用力而形成离子缔合复合物。此时,溶液的吸收光谱发生变化,染料在紫外和可见区的最大吸收显著降低,最大褪色波长分别位于264nm和434nm附近(AY体系)以及266nm和488nm附近(AO体系);反应有很高的灵敏度,最大摩尔吸光系数分别达7.20×107L(mol·cm)-1(AY体系λ=264nm)和1.13×108L(mol·cm)-1(AO体系λ=488nm);方法有较好的选择性,且简便快速,可用于烟丝中微量CMC的紫外可见分光光度法测定。