Detection of the Destruction Mechanism of Perfluorinated Elastomer (FFKM) Network under Thermo-oxidative Aging Conditions

Chinese Journal of Polymer Science - The changes of crosslinking network of perfluorinated elastomer (FFKM) cured by TAIC and DBPH under thermo-oxidative aging conditions were investigated. Two...     

Efficient Stress Dissipation in Well-Aligned Pyramidal SbSn Alloy Nanoarrays for Robust Sodium Storage

Alloy-type anode materials are promising for sodium-ion batteries owing to their high theoretical specific capacity. However, their practical application is limited by the rapid capacity decay resulted from drastic volume change upon sodium (Na) alloying/dealloying. Here, a facile fabrication of well-aligned antimony tin (SbSn) alloy nanoarrays electrodeposited on copper (Cu) substrates is reported. Such a binary alloy possesses well-defined triangular pyramid-like structure, and the subsequent thermal annealing process develops an “alloy glue” at the root of the nanoarrays which generates a strong connection between the active alloy and the copper substrate. Density functional theory calculation results suggest that the as-fabricated alloy offers an energetically favorable Na diffusion as compared to the individual metals, and the “alloy glue” provides a strong interaction between the substrate and SbSn. More importantly, based on finite-element analysis, such a unique construction of the triangular pyramid-like nanostructure not only creates a small difference in the Na⁺ concentration gradient, but also builds a uniform stress distribution that promotes both highly efficient Na⁺ diffusion and effective stress dissipation. Collectively, the optimized composition and geometry give rise to the enhanced high-rate performance and prolonged cycle life of the current SbSn alloy nanoarrays.     

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdHx

Controllable synthesis of well‐defined supported intermetallic catalysts is desirable because of their unique properties in physical chemistry. To accurately pinpoint the evolution of such materials at an atomic‐scale, especially clarification of the initial state under a particular chemical environment, will facilitate rational design and optimal synthesis of such catalysts. The dynamic formation of a ZnO‐supported PdZn catalyst is presented, whereby detailed analyses of in situ transmission electron microscopy, electron energy‐loss spectroscopy, and in situ X‐ray diffraction are combined to form a nanoscale understanding of PdZn phase transitions under realistic catalytic conditions. Remarkably, introduction of atoms (H and Zn in sequence) into the Pd matrix was initially observed. The resultant PdH_x is an intermediate phase in the intermetallic formation process. The evolution of PdH_x in the PdZn catalyst initializes at the PdH_x/ZnO interfaces, and proceeds along the PdH_x ?111? direction.     

分子束外延生长InGaN/AlN量子点的组分研究

报道了分子束外延生长的绿光波段InGaN/AlN量子点材料,并综合考虑InGaN量子点的应变弛豫,以及应力和量子限制斯塔克效应对量子点发光波长的影响,提出了一种结合反射式高能电子衍射原位测量与光致荧光测量确定InGaN量子点组分的方法.     

Modeling dynamics of?disaster spreading in community networks

In this paper, we investigate the dynamics of disaster spreading in community networks. Unlike the case in other kinds of complex networks, the transitions between the self-healing and spreading dynamics for community networks are in ladder-type in dependent of the recovery time and time delay. Statistical analysis on the average erupting time of disaster in communities shows that large-scale disaster firstly erupts in the community with maximal average degree, which is unrelated with the location where the initial disturbance seed is. Moreover, the average erupting time of disaster reduces along with the decrease of the average degrees of communities. Therefore, the community structure is helpful on the control of the disaster spreading.     

Fabrication of micro-sized-copper column array through localized electrochemical deposition using 20-μm-diameter micro-anode

Journal of Solid State Electrochemistry - Local electrochemical deposition (LECD) is an economical and efficient three-dimensional (3D) microstructure fabrication method. In this study, we...     

Epoxidation of cyclohexene with H2O2 over efficient water‐tolerant heterogeneous catalysts composed of mono‐substituted phosphotungstic acid on co‐functionalized SBA‐15

A series of Keggin‐type heteropolyacid‐based heterogeneous catalysts (Co‐/Fe‐/Cu‐POM‐octyl‐NH₃‐SBA‐15) were synthesized via immobilized transition metal mono‐ substituted phosphotungstic acids (Co‐/Fe‐/Cu‐POM) on octyl‐amino‐co‐functionalized mesoporous silica SBA‐15 (octyl‐NH₂‐SBA‐15). Characterization results indicated that Co‐/Fe‐/Cu‐POM units were highly dispersed in mesochannels of SBA‐15, and both types of Brønsted and Lewis acid sites existed in Co‐/Fe‐/Cu‐POM‐octyl‐NH₃‐SBA‐15 catalysts. Co‐POM‐octyl‐NH₃‐SBA‐15 catalyst showed excellent catalytic performance in H₂O₂‐mediated cyclohexene epoxidation with 83.8% of cyclohexene conversion, 92.8% of cyclohexene oxide selectivity, and 98/2 of epoxidation/allylic oxidation selectivity. The order of catalytic activity was Co‐POM‐octyl‐NH₃‐SBA‐15 > Fe‐POM‐octyl‐NH₃‐SBA‐15 > Cu‐POM‐octyl‐NH₃‐SBA‐15. In order to obtain insights into the role of ‐octyl moieties during catalysis, an octyl‐free catalyst (Co‐POM‐NH₃‐SBA‐15) was also synthesized. In comparison with Co‐POM‐NH₃‐SBA‐15, Co‐POM‐octyl‐NH₃‐SBA‐15 showed enhanced catalytic properties (viz. activity and selectivity) in cyclohexene epoxidation. Strong chemical bonding between ‐NH₃⁺ anchored on the surface of SBA‐15 and heteropolyanions resulted in excellent stability of Co‐POM‐octyl‐NH₃‐SBA‐15 catalyst, and it could be reused six times without considerable loss of activity.     

Solutions for conformally invariant fractional Laplacian equations with multi-bumps centered in lattices

In this paper, we consider the following nonlinear elliptic equation involving the fractional Laplacian with critical exponent:

${(?\mathrm{\Delta })}^{s}u=K(x)u^{\frac{N+2s}{N?2s}},u>0\mathrm{in}{\mathbb{R}}^N,$

where $s\in (0,1)$ and $N>2+2s$, $K>0$ is periodic in $(x_1,\dots ,x_k)$ with $1\le k<\frac{N?2s}{2}$. Under some natural conditions on K near a critical point, we prove the existence of multi-bump solutions where the centers of bumps can be placed in some lattices in ${\mathbb{R}}^k$, including infinite lattices. On the other hand, to obtain positive solution with infinite bumps such that the bumps locate in lattices in ${\mathbb{R}}^k$, the restriction on $1\le k<\frac{N?2s}{2}$ is in some sense optimal, since we can show that for $k\ge \frac{N?2s}{2}$, no such solutions exist.     

基于SE4205的汽车大灯调节系统设计

随着汽车普及率的提高,安全驾驶的重要性越来越高,夜间驾驶时前照灯的照射光束位置至关重要,本文设计了一款基于SE4205的汽车前照灯调节系统,详细说明了它的工作原理,经实物成品测试成功,并已推向市场。