简易高斯灰度扩散模型的误差分析及适用性研究

为了验证简易高斯灰度扩散模型的适用性,与传统高斯灰度扩散模型进行了对比分析。将两种高斯模型做归一化处理,设定检验像素,分析检验像元灰度的归一化值的相对误差;进行星图模拟,得到4个不同高斯半径(σ)下灰度赋值相对误差与像点映射位置偏离值的关系曲线,整体上误差随σ的增大而减小;对星图模拟得到的系列星像点采用灰度重心法提取质心,质心误差随σ增大而减小,传统模型模拟像点的质心提取精度比简易模型高约2个数量级。无噪声条件下σ=0.671时,简易模型模拟像点最大质心误差仅为0.033pixel。仿真结果表明:单就像点外形仿真而言,当σ较小时,简易模型不再适用;但针对像点的质心定位及后续算法,简易模型带来质心误差量级可以忽略,运算量更小,适于应用。     

高分散镁铝层状双氢氧化物的煅烧改性及其对甲基橙的吸附性能研究

以Mg(NO3)2·6H2O为镁源,Al(NO3)3·9H2O为铝源,采用水热法制备了高分散的镁铝层状双氢氧化物MgAl-LDH,并高温煅烧生成MgAl-LDO.利用场发射扫描电子显微镜(FE-SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)、X射线光电子分析(XPS)、氮气吸附-脱附法对产物进行表征分析,并且探讨了其吸附机理.结果 表明,2种产物的吸附过程对比于Langmuir吸附模型基本一致,其中MgAl-LDO的比表面积更大,吸附性能更好,对甲基橙的最大吸附量可达925.9 mg·g-1.吸附机制包括化学作用、氢键、静电作用和表面络合作用.     

Structural engineering of cathodes for improved Zn-ion batteries

Aqueous zinc-ion batteries (ZIBs) are attracting considerable attention because of their low cost,high safety and abundant anode material resources.However,the ...     

STUDIES OF MAIN CHAIN DYNAMICS OF FLUORINE-CONTAINING IONOMERS BY CARBON-13 NUCLEAR MAGNETIC RELAXATION

The carbon-13 spin-spin relaxation times of fluorine-containing ionomers are measured and motional correlation times τ_o and τ_d are calculated by using VJGM model . The results show that the motions of polymer main chain in ionomers become more difficult with increasing of ionization degree and contents of functional group, and depend on the fine structures and stability of ionic microdomains.     

抗凝血高分子

本文就便于短期应用的高分子负栽型抗凝血材料、具有良好发展前景的亲水—疏水型材料及杭凝血高分子材料中的微观相分离结构问题的研究进展,进行了扼要综述。     

Mesoporous carbon capsules as electrode materials in electrochemical double layer capacitors

The performance of mesoporous carbon capsules as electrode materials in electrochemical double layer capacitors (EDLCs) was evaluated in the presence of a variety of electrolytes, including room temperature ionic liquids (ILs).     

Computational investigation of the structures,properties, and host-guest chemistry of prism[n]arenes

The discovery of new and functional macrocyclic host compounds is an important part of supramolecular chemistry. Since the experimental synthesis, prism[n]arenes (Pr[n]As), a class of naphthol-based macrocyclic arenes, have attracted much attention. In this work, from the perspective of theoretical calculation and research, Pr[n]As (n = 4 ~ 7) were studied by density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The prismatic configuration isomers, electronic structures, absorption spectra, and host-guest chemistry were discussed thoroughly. DFT calculation results showed that 1,5-, 3,7-, and “hybrid” 15,37-Pr[n]As were the most representative configurations with the rigid prismatic molecular skeleton. Based on time-dependent density functional theory (TD-DFT), the absorption spectra of Pr[n]As were all in the range of ultraviolet light which were mainly attributed to π-π* transitions. The molecular cavities of Pr[n]As were electron-rich and capable of accommodating a variety of cations or electron-conjugated molecules. MD simulation results showed that a Pr[n]A molecule was able to capture the guest molecule into its molecular cavity and maintain in the state of equilibrium in solvents.     

Synthesis of ZnS hollow nanoneedles via the nanoscale Kirkendall effect

The facile synthesis of one-dimensional II–VI semiconductor hollow nanostructures with sharp tips is of particular interest for their applications in novel nanodevices. In this study, by employing ZnO nanoneedles with lower symmetry structures as self-sacrificed templates, ZnS hollow nanoneedles with homogeneous thickness have been synthesized by a low temperature hydrothermal route through in situ chemical conversion manner and the nanoscale Kirkendall effect. The hollow needlelike structures obtained in the present study can be used as starting materials to create fantastic nanoarchitectures and may have important applications in optoelectronic nanodevices.     

Vacancy-defect scattering in Ag(111)-supported silicene interface

The role of vacancy-defect scattering in electron mobility near the two-dimensional (2D) Ag(111)-supported silicene sheet interface was investigated in this paper. The interface structures of Ag(111)-supported silicene and silicene-sheet charge density were considered. Mobility limited by the vacancy-defect scattering was calculated in the order of 10²–10⁵ cm²/V?s, which was comparable with first-principle calculations and experimental results for free-standing and substrate-supported silicene. Results further showed the decay relationship between the electron mobility and vacancy density of silicene sheet. Furthermore, the influence of the Ag(111)-supported silicene sheet structure on electron mobility was confirmed through calculations. This study can contribute to the prediction of the electron mobility of other 2D graphene-like honeycomb-structure systems.