Closed and open-ended stacking fault tetrahedra formation along the interfaces of Cu–Al nanolayered metals

Stacking fault tetrahedra (SFTs) are volume defects that typically form by the clustering of vacancies in face-centred cubic (FCC) metals. Here, we report a dislocation-based mechanism of SFT formation initiated from the semi-coherent interfaces of Cu–Al nanoscale multilayered metals subjected to out-of-plane tension. Our molecular dynamics simulations show that Shockley partials are first emitted into the Cu interlayers from the dissociated misfit dislocations along the Cu–Al interface and interact to form SFTs above the triangular intrinsic stacking faults along the interface. Under further deformation, Shockley partials are also emitted into the Al interlayers and interact to form SFTs above the triangular FCC planes along the interface. The resulting dislocation structure comprises closed SFTs within the Cu interlayers which are tied across the Cu–Al interfaces to open-ended SFTs within the Al interlayers. This unique plastic deformation mechanism results in considerable strain hardening of the Cu–Al nanolayered metal, which achieves its highest tensile strength at a critical interlayer thickness of ~4 nm corresponding to the highest possible density of complete SFTs within the nanolayer structure.     

Spatiotemporal dynamics in a predator-prey model with a functional response increasing in both predator and prey densities

In this paper, we studied a diffusive predator-prey model with a functional response increasing in both predator and prey densities. The Turing instability and local stability are studied by analyzing the eigenvalue spectrum. Delay induced Hopf bifurcation is investigated by using time delay as bifurcation parameter. Some conditions for determining the property of Hopf bifurcation are obtained by utilizing the normal form method and center manifold reduction for partial functional differential equation.     

Studies on the Determination of the Micro Components by Photochemical Kinetics

The iodides can be oxidated to iodine by O_2 in air because of their lower redox potential. In an acidic solution, this reaction can be accelerated by ultraviolet light. Because the iodine yielded from potassium iodide by light irradiating solution can react with other oxidizer components, the iodine is constantly consumed. When it arrives the terminal points of the reaction, the iodine appears. According to the reaction time of the iodine appearing the quantities of the components are determined. And the terminal points can be pointed out by the blue of the iodine-starch or potentiometric     

没食子酸磁性表面分子印迹聚合物的制备与选择性识别性能

羟基苯甲酸类化合物用途广泛,极性较强,在复杂水溶液体系中这些类似物的分离纯化与分析非常困难。 本文以磁性Fe₃O₄纳米颗粒为载体,没食子酸(GA)为模板分子,制备了磁性表面分子印迹聚合物(MIP)。 利用透射电子显微镜、红外光谱、磁强测定等检测手段对MIP进行了结构表征。 并对其吸附性能进行研究,比较了该MIP对GA及其它3种结构类似物的吸附性能差异。 结果表明,制备的以GA为模板的磁性分子印迹聚合物为核壳球形结构,键合牢固,对GA的吸附动力学符合准二级动力学方程模型,吸附过程属于Langmuir单分子层吸附。 该聚合物对GA表现出优异的选择性识别能力,其吸附量(318 K时37.736 mg/g)远远高于结构类似物。 该磁性分子印迹聚合物对模板分子不仅具有特异识别能力,而且能够磁控分离,分离效率高,可用于固相萃取。     

Quasi-square-shaped cadmium hydroxide nanocatalysts for electrochemical CO2 reduction with high efficiency

Powered by a renewable electricity source, electrochemical CO₂ reduction reaction is a promising solution to facilitate the carbon balance. However, it is still a challenge to achieve a desired product with commercial current density and high efficiency. Herein we designed quasi-square-shaped cadmium hydroxide nanocatalysts for CO₂ electroreduction to CO. It was discovered that the catalyst is very active and selective for the reaction. The current density could be as high as 200 mA cm⁻² with a nearly 100% selectivity in a commonly used H-type cell using the ionic liquid-based electrolyte. In addition, the faradaic efficiency of CO could reach 90% at a very low overpotential of 100 mV. Density functional theory studies and control experiments reveal that the outstanding performance of the catalyst was attributed to its unique structure. It not only provides low Cd–O coordination, but also exposes high activity (002) facet, which requires lower energy for the formation of CO. Besides, the high concentration of CO can be achieved from the low concentration CO₂via an adsorption-electrolysis device.

Quasi-square cadmium hydroxide nanocrystals (Cdhy-QS) showed outstanding performance for electroreduction CO₂ to CO.     

Synthesis of magnetic/luminescent alginate-templated composite microparticles with temperature-dependent photoluminescence under high-frequency magnetic field

Highly magnetic luminescent alginate-templated composite microparticles were successfully synthesized by a novel process combining emulsification and layer-by-layer self-assembly techniques. The composite microparticles were characterized by ζ-potential analyzer, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscope, fluorescence spectrophotometer, and vibrating sample magnetometer. Experimental observations indicated that the composite microparticles had excellent magnetic properties, and its photoluminescence could be precisely controlled by varying the number of deposition cycles of polyelectrolytes and CdTe/polyelectrolyte multilayers. Moreover, the composite microparticles could be heated up in a high-frequency magnetic field and demonstrated linear temperature-dependent photoluminescence over the range from room temperature to hyperthermia temperature. The composite microparticles are expected to be promising candidates for biomedical applications, such as immunoassay, biosensing and imaging, and cancer diagnosis and treatment.     

Improvement of electrochemical performance for Li-rich spherical Li1.3[Ni0.35Mn0.65]O2+x modified by Al2O3

The Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x microspheres are firstly prepared and subsequently transferred into the Al₂O₃-coated Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x microspheres by a simple deposition method. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results reveal that the Al₂O₃-coated Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x sample has a typical α-NaFeO₂ layered structure with the existence of Li₂MnO₃-type integrated component, and the Al₂O₃ layer is uniformly coated on the surface of the spherical Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x particles with a thickness of about 4 nm. Importantly, the Al₂O₃-coated Li-rich sample exhibits obviously improved electrochemical performance compared with the pristine one, especially the 2 wt.% Al₂O₃-coated sample shows the best electrochemical properties, which delivers an initial discharge capacity of 228 mAh g^?1 at a rate of 0.1 C in the voltage of 2.0–4.6 V, and the first coulombic efficiency is up to 90 %. Furthermore, the 2 wt.% Al₂O₃-coated sample represents excellent cycling stability with capacity retention of 90.9 % at 0.33 C after 100 cycles, much higher than that of the pristine one (62.2 %). Particularly, herein, the typical inferior rate capability of Li-rich layered cathode is apparently improved, and the 2 wt.% Al₂O₃-coated sample also shows a high rate capability, which can deliver a capacity of 101 mAh g^?1 even at 10 C. Besides, the thin Al₂O₃ layer can reduce the charge transfer resistance and stabilize the surface structure of active material during cycling, which is responsible for the improvement of electrochemical performance of the Li-rich Li_1.3[Ni_0.35Mn_0.65]O_2+x .     

羧基亚胺配体的合成及其促进Suzuki偶联反应的研究

合成了4种羧基亚胺配体并将其用于促进Suzuki偶联反应。通过考察配体结构、溶剂极性、碱强度和温度等因素对反应产率的影响,确定了羧基亚胺配体参与的钯催化Suzuki偶联反应的最佳条件为:催化剂的量为0.001(mol)%的Pd Cl2和0.002(mol)%的配体,以碳酸钾作碱,4m L乙醇水溶液(1∶1,体积比)作溶剂,反应温度为60℃,在空气条件下反应。结果表明,羧基亚胺配体能够有效促进Suzuki偶联反应;在合成的配体L1~L4中,具有适当的位阻和给电子基团的L2的催化活性最高,能够高效催化合成一系列联芳类化合物。