HZSM-5沸石中Lewis酸与Brönsted酸协同作用下的甲基环己烷开环反应

由于水蒸气处理HZSM-5生成的骨架外铝在分子筛中体现Lewis酸性, 分子筛中骨架外铝物种的可移动性导致Lewis酸与分子筛本身的Brönsted酸在空间上具有临近性. 当甲基环己烷分子在HZSM-5的笼中转化时, Lewis酸与Brönsted酸的协同作用加快了甲基环己烷分子的转化速率, 且骨架外铝物种浓度越高, 这种协同效应越明显. 而产物的选择性只与催化剂的孔道结构有关, 与水蒸气处理所导致的酸性质的变化无关.     

Determination of mercurial species in fish by inductively coupled plasma mass spectrometry with anion exchange chromatographic separation

This work demonstrated the feasibility of mercury speciation analysis by anion exchange chromatographic separation with inductively coupled plasma mass spectrometry detection. For the first time, by complexing with the mobile phase containing 3-mercapto-1-propanesulfonate into negatively charged complexes, fast separation of inorganic mercury (Hg²⁺), monomethylmercury (MeHg), ethylmercury (EtHg) and phenylmercury (PhHg) was achieved within 5 min on a 12.5-mm strong anion exchange column. The detection limits for Hg²⁺, MeHg, EtHg and PhHg were 0.008, 0.024, 0.029 and 0.034 μg L⁻¹, respectively. The relative standard deviations of peak height and peak area (5.0 μg L⁻¹ for each Hg species) were all below 3%. The determined contents of Hg²⁺, MeHg and total Hg in a certified reference material of fish tissue by the proposed method were in good accordance with the certified values with satisfactory recoveries. The relative errors for determining MeHg and total mercury were −2.4% and −1.2%, respectively, with an acceptable range for spike recoveries of 94–101%. Mercury speciation in 11 fish samples were then analyzed after the pretreated procedure. The mercury contents in all fish samples analyzed were found compliant with the criteria of the National Standards of China.     

Quantum-chemical calculations and IR spectra of the (F2)MF2 molecules (M = B, Al, Ga, In, Tl) in solid matrices: a new class of very high electron affinity neutral molecules

Electron-deficient group 13 metals react with F(2) to give the compounds MF(2) (M = B, Al, Ga, In, Tl), which combine with F(2) to form a new class of very high electron affinity neutral molecules, (F(2))MF(2), in solid argon and neon. These (F(2))MF(2) fluorine metal difluoride molecules were identified through matrix IR spectra containing new antisymmetric and symmetric M-F stretching modes. The assignments were confirmed through close comparisons with frequency calculations using DFT methods, which were calibrated against the MF(3) molecules observed in all of the spectra. Electron affinities calculated at the CCSD(T) level fall between 7.0 and 7.8 eV, which are in the range of the highest known electron affinities.     

圆电流中导体的磁悬浮效应研究

本文基于椭圆积分法计算了圆电流产生的磁场,进而得到了导体在圆电流产生的高频电磁场中受力的解析表达式.结果表明:高频电磁场作用下,趋肤深度内的导体受到强烈的磁悬浮作用.频率越低,磁悬浮力的穿入深度越大,但其数值降低得越快.     

A lithium salt additive Li<Subscript>2</Subscript>ZrF<Subscript>6</Subscript> for enhancing the electrochemical performance of high-voltage LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.5</Subscript>O<Subscript>4</Subscript> cathode

In this work, Li₂ZrF₆, a lithium salt additive, is reported to improve the interface stability of LiNi_0.5Mn_1.5O₄ (LNMO)/electrolyte interface under high voltage (4.9 V vs Li/Li⁺). Li₂ZrF₆ is an effective additive to serve as an in situ surface coating material for high-voltage LNMO half cells. A protective SEI layer is formed on the electrode surface due to the involvement of Li₂ZrF₆ during the formation of SEI layer. Charge/discharge tests show that 0.15 mol L^?1 Li₂ZrF₆ is the optimal concentration for the LiNi_0.5Mn_1.5O₄ electrode and it can improve the cycling performance and rate property of LNMO/Li half cells. The results obtained by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) demonstrate that Li₂ZrF₆ can facilitate the formation of a thin, uniform, and stable solid electrolyte interface (SEI) layer. This layer inhibits the oxidation decomposition of the electrolyte and suppresses the dissolution of the cathode materials, resulting in improved electrochemical performances.     

应变率对Gr/Al金属基复合材料力学性能的影响

利用自行研制的冲击拉伸实验装置对单向石墨纤维增强铝基复合材料实施了不同应变率下的拉伸实验。获得了材料在００００５～１３００ｓ－１应变率范围内完整的应力应变曲线。结果表明Ｇｒ／Ａｌ的应力应变曲线可分为两个部分:非线性弹脆性变形以及材料失稳后的残余变形。实验结果还表明Ｇｒ／Ａｌ是一种应变率敏感材料,随着应变率的提高,材料的拉伸强度、失稳应变以及剩余应力均相应提高。根据不同应变率下的实验结果,提出了计及应变率强化效应的复合丝束统计本构模型,模型拟合的结果与实验结果吻合得很好。拟合结果还表明,特征纤维统计分布的Ｗｅｉｂｕｌ参数（尺度参数与形状参数）均是与应变率无关的,复合材料的应变率效应主要是由基体的应变率强化效应引起的。     

The double mode model of the chaotic motion for a large deflection plate

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因子分析-氢化物发生原子吸收法分析砷的形态

报道了用流动注射氢化物发生原子吸收法（ＦＩ－ＨＧＡＡＳ）对砷４种形态,Ａｓ,ＤＭＡ,ＭＭＡ）的混合体系进行测量后,根据吸光度加和性原则,用因子分析法（ＴＦＡ）对测定值进行解析,从而测定了混合体系中砷存在形态的数目、种类和含量。实验结果表明,不同酸度介质中不同形态砷校正曲线的斜率可作为相应的目标检测向量,应用于μｇ／Ｌ级低浓度砷的形态分析,平均回收率为９３．９％,结果令人满意。     

微流控芯片系统在单细胞研究中的应用

微流控芯片具有网络式通道结构,扩展了在细胞和亚细胞水平进行生命科学研究的能力,为单细胞研究提供了一个新的平台.在微流控芯片通道中,人们利用气压、液压和电压,或利用介电电泳、光学陷阱、行波介电电泳以及磁场等技术,可以操纵细胞通过或驻留在通道内的任意位置,从而使单细胞计数、筛选以及胞内组分分析等操作大大简化.本文对微流控芯片系统在血液流变学、单细胞操纵与计数以及单细胞胞内组分分析中的应用进行了综述,介绍了用于单细胞研究的多种微芯片系统,讨论了芯片上进行单细胞操纵的各种方法     

一类KKT系统的结构敏度分析

本文讨论一类KKT系统的敏度分析，这类KKT系统产生于用有限元方法离散Stokes方程，有结构特性．首先给出了最佳向后扰动界，接下来定义了偏条件数并导出了表达式．最后给出了新的扰动界．