摘要：The effects of cation ordering and surface compensating anions on the magnetic structure and catalytic properties of unilamellar Ni-Fe hydroxide nanosheets are studied by using the density functional theory （DFT） plus U method. Fe-segregation in the nanosheets yields magnetic domains with different spin alignments, while the surface compensating anions affect the local moments and valence states of the Fe atoms. The two conditions do not radically change the super-exchange nature of interactions between the paramagnetic metal centers, hut facilitate the formation of various magnetic superlattices in the nanosheets. The calculated free energy change of the intermediates shows that the most stable magnetic structure of Ni-Fe hydrox- ide nanosheets exhibits superior catalytic activity towards oxygen reduction/evolution reactions, which is indicative of magnetic catalyst. This is due to the cycle transition between Fe2＋ and Fe~~ ions in the reactions, which determines the sequence of cleavage of the O-H bond and the release of the OH group, controlling the rate-limiting steps of the reaction. The relationship of magnetism and catalytic activity of Ni-Fe hydroxide nanosheets is established by the valence state change of the Fe ions, which will be helpful to open the way for the design of hydroxide/layered double hydroxides （LDHs）-based magnetic catalysts.

摘要：Tandem electrocatalysis is an emerging concept for effective electrochemical CO_(2) reduction reaction(CO_(2)RR)towards multicarbons(C_(2+)).This decouples the multiple steps of CO_(2)-to-C_(2+)into two steps of CO_(2)-to-CO and CO-to-C_(2+)catalyzed by individual catalysts,to improve the Faradic efficiency(FE).However,due to the mass-transport limitation of CO from the generation site to the long-distance consumption site,such a strategy still remains challenge for high-rate production of C_(2+)***,we designed CuO/Ni single atoms tandem catalyst,which made the catalytic sites of Ni and Cu for independently catalyzing CO_(2)-to-CO and CO-to-C_(2+)compactly neighbored,enabling the in-situ generation and rapid consumption of *** CuO/Ni SAs tandem catalyst achieved a particularly high partial current density of C_(2+)products(1220.8 mA/cm^(2)),while still maintained outstanding C_(2+)products FE(81.4%)and excellent selectivities towards ethylene(FE 54.1%)and ethanol(FE 28.8%),enabling the profitable production of multicarbons by CO_(2)RR.

摘要：How to increase strength without sacrificing ductility has been developed as a key goal in the manufacture of high-performance metals or alloys. Herein, the double-nanophase intragranular yttrium oxide dispersion strengthened iron alloy with high strength and appreciable ductility was fabricated by solution combustion route and subsequent spark plasma sintering, and the influences of yttrium oxide content and sintering temperature on microstructures and mechanical properties were investigated. The results show at the same sintering temperature,with the increase of yttrium oxide content, the relative density of the sintered alloy decreases and the strength increases. For Fe–2wt%Y_(2)O_(3)alloy, as the sintering temperature increases gradually, the compressive strength decreases, while the strain-to-failure increases. The Fe–2wt%Y_(2)O_(3)alloy with 15.5 nm Y_(2)O_(3)particles uniformly distributed into the 147.5 nm iron grain interior sintered at 650℃ presents a high ultimate compressive strength of 1.86 GPa and large strain-to-failure of 29%. The grain boundary strengthening and intragranular second-phase particle dispersion strengthening are the main dominant mechanisms to enhance the mechanical properties of the alloy.

摘要：Tunneling heterostructures are emerging as a versatile architecture for photodetection due to their advanced optical sensitivity,tailorable detection band,and wellbalanced photoelectric ***,the existing tunneling heterostructures are mainly operated in the visible wavelengths and have been rarely investigated for the nearinfrared ***,we report the design and realization of a novel broken-gap tunneling heterostructure by combining WSe2 and Bi2Se3,which is able to realize the simultaneous visible and near-infrared detection because of the complementary bandgaps of WSe2 and Bi2Se3(1.46 and 0.3 e V respectively).Thanks to the realigned band structure,the heterostructure shows an ultralow dark current below picoampere and a high tunneling-dominated *** photodetector based on our tunneling heterostructure exhibits a superior specific detectivity of 7.9×1012Jones for a visible incident of 532 nm and 2.2×1010Jones for a 1456 nm nearinfrared *** study demonstrates a new band structure engineering avenue for the construction of van der Waals tunneling heterostructures for high-performance wide band photodetection.

摘要：Development of highly efficient photocatalysts has emerged as a research hotspot because of their crucial role in affecting the conversion efficiency of solar energy for applications in resource exploitation and environmental *** photocatalytic performance of the photocatalysts basically depends on the behaviors of light absorption,charge generation and separation,surface property and structural *** to its unique advantages(high surface area,tunable porosity,modifiable surface),porous silica provides an interesting platform to construct well-defined nanostructures such as core-shell,yolk-shell and other specific structures which effectively improved one or more of the above behaviors for ***,the structure with hollow morphology favors the light scattering and enlargement of surface area,while coating or binding with silica can modify the surface property of a photocatalyst to enhance the surface adsorption of reactants and physicochemical stability of *** review discusses the recent advances in the design,synthesis,formation mechanism of well-defined silica-based nanostructures,and the achievements of desired physicochemical properties for regulating the photocatalytic performance.

摘要：The rapid growth of air traffic has continuously increased the workload of controllers,which has become an important factor restricting sector *** similar traffic scenes can be identified,the historical decision-making experience may be used to help controllers decide control strategies *** that there are many traffic scenes and it is hard to label them all,in this paper,we propose an active SVM metric learning(ASVM2L)algorithm to measure and identify the similar traffic *** of all,we obtain some traffic scene samples correctly labeled by experienced air traffic *** design an active sampling strategy based on voting difference to choose the most valuable unlabeled samples and label *** the metric matrix of all the labeled samples is learned and used to complete the classification of traffic *** verify the effectiveness of ASVM2L on standard data sets,and then use it to measure and classify the traffic scenes on the historical air traffic data set of the central South Sector of *** experimental results show that,compared with other existing methods,the proposed method can use the information of traffic scene samples more thoroughly and achieve better classification performance under limited labeled samples.

摘要：Constant current power transmission is considered a good choice for subsea observatories due to its high resistance to shunt faults. A constant current subsea observatory is planned to be constructed in the East china Sea. We discuss a constant current subsea observatory system used for scientific experiments. The power system and its heat dissipation system are carefully designed. The power conversion method is challenging due to the use of constant current power, which is considerably different from traditional power systems. Thus, we adopt power compensation circuits in the conversion system to obtain a constant 48-V output for science users. A power management system that performs overvoltage protection and real-time monitoring and control of junction box is discussed. An innovative heat dissipation structure of a junction box is designed in consideration of a sealed working environment to extend the useful life of the junction box. Simulations and experiments reveal that the system has high efficiency and stability, especially in long-term applications.

摘要：热处理是金属材料热机械加工的常用手段.随着热处理温度的升高而湮灭的缺陷通常导致材料的塑性提升而强度降低.本研究中,我们通过提高热处理温度促进相溶解而协同提升了TiZrNbTa高熵合金的强度和塑性.当热处理温度从800提升至1250°C,合金的拉伸屈服强度提高了40%,达到1003±16 MPa.同时,合金的伸长率增加了近一倍,达到16.79%±1.03%.热处理温度提升引起的相溶解加剧了晶格畸变,从而增强了晶格摩擦应力并提升了屈服强度.相溶解也降低了界面失配并缓解了应力集中.此外,1250°C热处理合金中的局部化学有序结构促进了位错共平面滑移和位错增殖.两种机制共同提升了合金的塑性.该研究不仅扩展了关于金属材料中热处理和相溶解的理解,而且也为合金的强韧化设计提供了思路.

摘要：聚乙烯醇/中国墨水混合物被均匀涂覆在聚乙烯薄膜上制备了结构稳定的双层软驱动器.由于两层材料的热膨胀系数的显著差异,在氙灯照射下,驱动器能以较快的响应速度实现较大的弯曲变形.通过改变光的强度以及结合尺蠖的仿生结构设计,机器人可以在不同的表面(如纸张和树叶)上实现各种形式的运动.同时在光的驱动下,它可以实现物体的捕获、表情的改变、象鼻的收缩与卷曲以及仿生花朵的开闭等.此外,基于双层驱动器良好的光热转换和灵敏的压力传感性能,它可以实现人体运动监测(如关节弯曲、呼吸、吞咽等),还能与光电转换装置集成.这种多功能、多驱动模式软机器人在可穿戴设备、交通运输、光电转换设备等应用领域具有巨大潜力.

摘要：Developing transition metal-based electrocatalysts with rich active sites for water electrolysis plays important roles in renewable energy fields. So far, some strategies including designing nanostructures, incorporating conductive support or foreign elements have been adopted to develop efficient electrocat- alysts. Herein, we summarize recent progresses and propose in-situ electrochemical activation as a new pretreating technique for enhanced catalytic performances. The activation techniques mainly comprise facile electrochemical processes such as anodic oxidation, cathodic reduction, etching, lithium-assisted tuning and counter electrode electro-dissolution. During these electrochemicaI treatments, the catalyst surfaces are modified from bulk phase, which can tune local electronic structures, create more active spe- cies. enlarge surface area and thus improve the catalytic performances. Meanwhile, this technique can couple the atomic, electronic structures with electrocatalysis mechanisms for water splitting. Compared to traditional chemical treatment, the in-situ electrochemical activation techniques have superior advantages such as facile operation, mild environment, variable control, high efficiency and flex- ibility. This review may provide guidance for improving water electrolysis efficiencies and hold promis- ing for application in many other energy-conversion fields such as supercapacitors, fuel cells and batteries.