Theoretical STM images of alkaline-earth metal adsorbed Si(1 1 1)3 × 2 surfaces

We have performed total-energy calculations to study theoretical scanning tunneling microscopy (STM) images of the Si(1 1 1)3 × 2 surfaces induced by the adsorption of alkaline-earth metals (AEMs). Previously, in a series of works on Ba/Si(1 1 1) system, we have found that the observed Si(1 1 1)3 × 1-Ba LEED phase indeed has a 3 × 2 periodicity with a Ba coverage of 1/6 ML and the HCC substrate structure. Based on results of the Ba case, we proposed that the HCC structure is also adopted for other AEM atoms, which was confirmed by our recent work. In this paper, we mainly report the STM simulations for different AEM systems to compare with existing experimental data. We discuss the difference in the detailed STM images for different AEM adsorbates. Especially, the difference in filled-state images between Mg and other AEM atoms is attributed to the strong Mg-Si interaction.     

有序自组装聚合物纳米结构

采用水辅助方法(water-assisted fabrication method),分别以4-十二烷基苯磺酸掺杂的聚苯胺(PANI-DBSA)和聚2-甲氧基-5-(2′-乙烯基-己氧基)苯乙炔(MEH-PPV)两种功能高聚物为成膜材料,冷凝水滴为模板,利用水滴在聚合物溶液表面的自组装,制备出了两种纳米层次以上的蜂窝状有序多孔聚合物薄膜.通过原子力显微镜和共聚焦荧光显微镜对其形貌、电学性质和荧光图像进行了表征.     

Exciton-polaritons in lattices: A non-linear photonic simulator

Microcavity polaritons are mixed light–matter quasiparticles with extraordinary nonlinear properties, which can be easily accessed in photoluminescence experiments. Thanks to the possibility of designing the potential landscape of polaritons, this system provides a versatile photonic platform to emulate 1D and 2D Hamiltonians. Polaritons allow transposing to the photonic world some of the properties of electrons in solid-state systems, and to engineer Hamiltonians for photons with novel transport properties. Here we review some experimental implementations of polariton Hamiltonians using lattice geometries.     

Changing the adsorption capacity of coal-based honeycomb monoliths for pollutant removal from liquid streams by controlling their porosity

Coal-based honeycomb monoliths extruded using methods developed for ceramic materials have been used to retain methylene blue and p-nitrophenol from aqueous solutions. The influence of the filters’ thermal treatment on their textural properties and performance as adsorbents was examined. Characterization by N₂ physisorption, mercury porosimetry and scanning electron microscopy along with adsorption tests under dynamic conditions suggest that, depending on the pollutant and its initial concentration, it can be more convenient to previously submit the monoliths to a simple carbonization or to an additional activation, with or without preoxidation, as a consequence of their different resulting pore structures. Infrared spectroscopy indicates that their different adsorption behaviour seems not to be related to differences in their surface chemical groups. In addition, axial crushing tests show that the monoliths have an acceptable mechanical resistance for the application investigated.     

Preparation of honeycomb porous La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.2Ce0.8O2−δ composite cathodes by breath figures method for solid oxide fuel cells

Honeycomb porous La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ-Gd_0.2Ce_0.8O_2−δ (LSCF-GDC) composite cathodes are prepared using the breath figures (BFs) method with nontoxic and easily available water droplets as templates. The fabrication of honeycomb porous membranes is realized in a relatively humid environment, using a volatile solvent. The microstructure and morphology of the membranes produced are investigated by scanning electron microscopy (SEM). The SEM micrographs suggest that experimental conditions, such as ambient temperature, relative humidity, and concentration of polymer and LSCF-GDC powder, which have direct influence on the solvent evaporation affects the pore structure of the porous membranes. Electrochemical impedance spectroscopy (EIS) is used to evaluate the polarization resistance of LSCF-GDC composite cathodes prepared at different experimental conditions. The honeycomb porous LSCF-GDC composite cathode showing average pore diameter of 10 μm illustrates the lowest polarization resistance.     

Optimum properties of extruding paste powders on the basis of TiO2, Al2O3 and other substances for production of honeycomb supports

Structure-mechanical and rheological characteristics of pastes on the basis of TiO₂ and Al₂O₃ are discussed. Optinum values to prepare honeycomb supports are determined.     

Flexible asymmetric supercapacitor based on MnO2 honeycomb structure

By controlling the electroplating time of solution containing Mn(Ac)₂, the MnO₂ nanosheets were self-assembled to the honeycomb structure and showed an excellent electrochemical performance in 1 mol/L Na₂SO₄ electrolyte. Via pairing with activated carbon as negative electrode, the capacitor could deliver a maximum energy density of 43.84 Wh/kg and a maximum power density of 6.62 kW/kg.     

LED汽车前大灯散热器正交优化设计与分析

设计了一种LED汽车前大灯散热器结构,该结构主要由一条通风管和一台无叶风扇组成.在SolidWorks软件中建立该散热结构模型,并导入FloEFD软件进行散热仿真,得到LED结温温度为148℃.提出在通风管中填充矩形翅片和填充蜂窝结构两种改进方案.仿真结果表明,采用两种改进方案后LED汽车前大灯的结温温度分别下降至102.01℃和86.20℃.对填充蜂窝结构方案进行正交优化试验,分析得出影响该系统散热性能的因素依次为:蜂窝等效直径、蜂窝类型、填充长度、壁厚和通风管长度.按照该顺序优化参数值,得到最优散热结构.仿真结果表明,经过正交优化后,LED汽车前大灯的温度降为75.17℃,进一步提高了整体结构的散热性能.最后分析了该结构的基板温度与风速的关系,结果表明当风速低于5m/s时,温度随着风速的增大急剧降低,当风速高于5m/s时,温度下降趋势相对缓慢.     

遮光罩内壁蜂窝结构单元的双向反射特性

内壁蜂窝结构是决定遮光罩杂散光抑制性能的主要因素,掌握其各向异性辐射传输特性对遮光罩的杂散光分析和优化设计具有重要意义.针对蜂窝结构单元,建立辐射传输模型,导出了表面双向反射分布函数的离散表达式;通过蒙特卡罗法模拟蜂窝结构单元的辐射传输过程,分析了几何参量和涂层反射率对等效面反射特性的影响;根据模拟所得双向反射分布函数数据库,建立了用于遮光罩杂散光分析的蜂窝结构等效面的反射特性概率模型.分析结果表明,蜂窝结构对杂散光呈现很强的后向散射特征,等效面的反射特性概率模型与直接模拟结果符合很好,可用于遮光罩杂散光分析和设计.     

聚乳酸蜂窝状多孔膜的形成与控制

以单一组分聚L-乳酸(PLLA)为成膜材料,利用水辅助法制备了聚乳酸(PLLA)蜂窝状多孔膜.利用扫描电镜(SEM)和原子力显微镜(AFM)观察多孔膜形貌.研究溶剂、溶液浓度、环境温度和湿度等因素对所成多孔膜结构的影响.实验结果表明,高湿度环境和具有一定浓度的聚合物溶液是制备蜂窝状多孔膜的必要条件.溶剂的挥发性是形成规整蜂窝状孔结构的关键因素.环境相对湿度由43%增加到91%,PLLA多孔膜的孔径由(1.75±0.24)μm增加到(11.50±1.43)μm,且孔呈现六边形的蜂窝状结构.扫描电镜断面和AFM表明:膜表面形成了深度约为1.8μm的单层孔结构.通过控制溶液浓度、环境温度和湿度等因素来控制膜的表面形貌及其所成蜂窝状孔的大小.最佳的成膜条件为溶剂CH2Cl2,湿度75%RH,温度34℃,浓度3 wt%.讨论了蜂窝状多孔膜的形成机理.