Hydrazine‐Assisted Liquid Exfoliation of MoS2 for Catalytic Hydrodeoxygenation of 4‐Methylphenol

A simple but effective method to exfoliate bulk MoS₂ in a range of solvents is presented for the preparation of colloid flakes consisted of one to a few molecular layers by application of ultrasonic treatment in N₂H₄. Their high yield in solution and exposure of more active surface sites allows the synthesis of corresponding solid catalysts with remarkably high activity in hydrodeoxygenation of 4‐methylphenol and this method can also be applied to other two dimensional materials.     

Multilayer brain network combined with deep convolutional neural network for detecting major depressive disorder

As a global and grievous mental disease, major depressive disorder (MDD) has received much attention. Accurate detection of MDD via physiological signals represents an urgent research topic. Here, a frequency-dependent multilayer brain network, combined with deep convolutional neural network (CNN), is developed to detect the MDD. Multivariate pseudo Wigner distribution is firstly introduced to extract the time-frequency characteristics from the multi-channel EEG signals. Then multilayer brain network is constructed, with each layer corresponding to a specific frequency band. Such multilayer framework is in line with the nature of the workings of the brain, and can effectively characterize the brain state. Further, a multilayer deep CNN architecture is designed to study the brain network topology features, which is finally used to accurately detect MDD. The experimental results on a publicly available MDD dataset show that the proposed approach is able to detect MDD with state-of-the-art accuracy of 97.27%. Our approach, combining multilayer brain network and deep CNN, enriches the multivariate time series analysis theory and helps to better characterize and recognize the complex brain states.

     

ZnO逆修饰小尺寸Cu/SiO2催化剂及其在CO2加氢制甲醇中的应用

Cu-ZnO is broadly used as a catalyst in CO₂ reduction to produce methanol, but fabricating small-sized Cu-ZnO catalysts with strong Cu-ZnO interactions remains a challenge. In this work, a simple, low-cost method is proposed to synthesize small-sized Cu-ZnO/SiO₂ with high activity and controllable Cu-ZnO interactions derived from copper silicate nanotubes. A series of Cu-ZnO/SiO₂ samples with different amounts of ZnO were prepared. The activities of the as-prepared catalysts for methanol synthesis were tested, and the results revealed a volcano relationship with the weight fraction of ZnO. At 523 K, the methanol selectivity increased from 20% to 67% when 14% ZnO was added to the Cu/SiO₂ catalyst, while the conversion of CO₂ increased first and then decreased with the addition of ZnO. The optimum space time yield (STY) of 244 g·kg^-1·h^-1 was obtained on C-SiO₂-7%ZnO at 543 K under 4.5 MPa H₂/CO₂. Furthermore, the synergistic effect of Cu and ZnO was studied by high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS), and temperature-programmed reduction (TPR) analyses. The HRTEM images showed that the Cu particles come in contact with ZnO more frequently with increased addition of ZnO, indicating that the catalysts with higher ZnO contents have a greater probability of formation of the Cu-ZnO interface, which promotes the catalytical activity of Cu-ZnO/SiO₂. Meanwhile, the HRTEM images, XRD patterns, and TPR results showed that the addition of excess ZnO leads to an increase in the size of the Cu particles, which in turn decreases the total number of active sites and further degrades the activity of the catalysts. The activation energy (E_a) for methanol synthesis and reverse water gas shift (RWGS) was calculated based on the results of the catalytical test. With the addition of ZnO, E_a for methanol synthesis decreased from 72.5 to 34.8 kJ·mol^-1, while that for RWGS increased from 61.3 to 102.7 kJ·mol^-1, illustrating that ZnO promotes the synergistic effect of Cu-ZnO. The results of XPS and in situ DRIFTS showed that the amount of Cu⁺ species decreases with the addition of ZnO, indicating that the Cu-ZnO interface serves as the active site. The Cu surface area and the turnover frequency (TOF) of methanol were calculated based on the H₂-TPR curves. The TOF of methanol on the Cu-ZnO/SiO₂ catalysts at 543 K increased from 1.5 × 10^-3 to 3.9 × 10^-3 s^-1 with the addition of ZnO, which further confirmed the promotion effect of the Cu-ZnO interface on the methanol synthesis. This study provides a method to construct Cu-ZnO interfaces based on copper silicate and to investigate the influence of ZnO on Cu-ZnO/SiO₂ catalysts.     

Synthesis and simultaneous self‐assembly of multiblock fluorinated polyurethane in iniferter polymerization

A multiblock fluorinated polyurethane was synthesized using tetraphenylethane‐based polyurethane as macroiniferter to free‐radically polymerize 1H,1H,3H‐trihydro perfluoro‐2,4‐dimethylpentyl methacrylate (FDPMA). Simultaneous self‐assembly occurred in FDPMA polymerization process and various nanostructures, like multicore particles, formed depending on FDPMA concentration. Fluorophobic effect and the cooperation of the fluorinated blocks with polyurethane blocks are demonstrated to be the main contribution. That soluble FDPMA in DMF becomes insoluble after polymerization triggers the self‐assembly process and leads to the nanostructure formation, and the polyurethane blocks that are soluble in DMF and immiscible with the fluorinated blocks stabilize the discrete nanostructures. Further, the nanostructures in solutions can evolve into various morphologies, such as disk and fiber, when dried to solid state. All these results not only reveal the feasibility and robustness of the multiblock copolymer on the modulation of self‐assembly structure but also represent a facile and efficient approach for novel nanostructure construction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013     

盐酸介导策略合成的具有优异光催化能力的ZnFe2O4小颗粒点缀一维苝二酰亚胺S型异质结

由于有机材料的结构多样性,越来越多的研究者选择有机材料作为光催化剂.典型的n型有机半导体花二酰亚胺(PDI)不仅在可见光照射下有较强的光响应能力,而且有合适的带隙和负导带,使得光激发电子具有较强的还原能力.半导体光催化剂的适用性受到光生载流子复合的限制,而构建S型异质结可有效保证电荷分离,也可保证空穴和电子的强氧化能力...     

微等电聚焦分离等位基因表达蛋白的研究

借助于显微操作方法,用等电聚焦和改进的超敏感染色技术对西葫芦单个花粉粒中的可溶性蛋白进行了电泳分析,获得了清晰的电泳图谱。在靠近酸性端有两条相距极近而且分布比较特殊的蛋白带,在第１种植株中,这两条带稍微靠近酸性端;在第２种植株中,它们稍微远离酸性端;在第３种植株中,它们相同于第１种和第２种,而且在两种之间的分布比例为１∶１。就这两条带的分布情况在判断植株的相对纯合性或杂合性方面的应用以及单花粉蛋白等电聚焦技术配合显微操作方法在群体遗传学和发育生物学研究方面的应用作了讨论。     

LiMn2O4正极在高温下性能衰退现象的研究

采用恒流充放电方法测量了温度升高导致ＬｉＭｎ２Ｏ４正极容量衰减的情况。发现当环境温度上升到５０℃时,ＬｉＭｎ２Ｏ４电极出现严重的容量损失和性能衰退,充电态的电极受影响的程度最为严重。对电解液的原子发射和红外光谱分析,电极晶相结构Ｘ－射线衍射及循环伏安实验速增加,电解液出现催化氧化是导致容量不可逆衰砬的原因。采用富锂尖晶石材料是抑制ＬｉＭｎ２Ｏ４高温性能下降的一种有效方法。     

二维离子色谱法测定精己二酸中痕量硝酸根离子

建立二维离子色谱法测定精己二酸中痕量硝酸根离子含量的方法。第一维采用去离子水作为流动相,经过Ion Pac ICE–AS1色谱柱将精己二酸中的硝酸根离子和己二酸进行预分离,分离出来的硝酸根富集于Ion Pac TAC–ULP1浓缩柱上。以淋洗液发生器产生的不同质量浓度的氢氧化钾溶液作为淋洗液,将富集柱上的硝酸根淋洗下来,经第二维Ion Pac AS17–C色谱柱进行分离,以抑制型电导检测器测定硝酸根离子的含量。精己二酸中硝酸根离子的质量浓度在2.0~50.0μg/L范围内与其色谱峰面积呈良好线性,线性相关系数r20.999,检出限为0.10μg/L,测定结果的相对标准偏差小于1.5%(n=7),加标回收率为98.0%~105.0%。该方法操作简单,灵敏度、准确度高,选择性好,能够准确测定精己二酸中痕量硝酸根离子的含量。