Green synthesis and application of nanoscale zero-valent iron/rectorite composite material for P-chlorophenol degradation via heterogeneous Fenton reaction

A zero-valent iron/rectorite nanocomposite (NZVI/rectorite) was developed as a heterogeneous H₂O₂ catalyst for P-chlorophenol degradation. The physicochemical properties of NZVI/rectorite were characterized by various techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Results showed that NZVI sphere nanoparticles were successfully loaded on the rectorite surface with less aggregation and good dispersion. Moreover, compared with acid-leached rectorite (30.91 m²/g), the NZVI/rectorite appeared to have larger surface area (50.75 m²/g). In addition, the effects of pH, reaction time, initial P-chlorophenol concentration, catalyst amount, and H₂O₂ dosage on the P-chlorophenol degradation were systematically investigated. Results showed that NZVI/rectorite presents better properties for the degradation and mineralization of P-chlorophenol compared with pristine NZVI due to the large surface area, low aggregation, and good dispersion of the former. The degradation mechanisms of P-chlorophenol by NZVI/rectorite were adsorption and reduction coupled with a Fenton-like reaction. Four successive runs of the stability and regeneration study also showed that the NZVI/rectorite were unchanged even after 100% of P-chlorophenol degradation ratio. This study has extended the application of NZVI/rectorite as environment function material for the removal of P-chlorophenol from the environment.     

Atomic‐Scale Insight into Exsolution of CoFe Alloy Nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3−δ with Efficient CO2 Electrolysis

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal–oxide interface for CO₂ electrolysis in a solid oxide electrolysis cell. Atomic‐scale insight is provided into the exsolution of CoFe alloy nanoparticles in La_0.4Sr_0.6Co_0.2Fe_0.7Mo_0.1O_3?δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy‐dispersive X‐ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal–oxide interface improves CO₂ adsorption and activation, showing a higher CO₂ electrolysis performance than the LSCFM counterparts.     

OSCILLATION AND NON-OSCILLATION FOR SECOND-ORDER QUASI-LINEAR DIFFERENCE EQUATIONS

Some oscillation and non-oscillation criteria for second-order quasi-linear difference equations are given. The results in Zhang and Zhou [4] are improved.     

菜粉蝶颗粒体病毒包涵体在银胶中的表面增强拉曼光谱研究

本文讨论了菜粉蝶(preris rtpae)颗粒体病毒(简称 PrGV )包涵体在银胶中的表面增强拉曼光谱。PrGV 包涵体的 SERS 谱与其 RS 谱之间存在一定对应关系。PrGV 包涵体蛋白分子通过羧基和氨基基团吸附于银粒子表面,并构成阴离子形式(NU_2RCOO~-)存在于溶液中。PrGV 在银胶中的表面增强的增强机制属于短程作用。PrGV 包涵体与银胶表面的吸附主要是化学吸附。     

基于广义\mbox{\boldmath $Z_{4}$}线性Calderbank-McGuire码的对偶

本文讨论了广义Z4线性Calderbank-McGuire码的对偶的迹表示及2-adic表示, 同时给出了其最小Lee权估计.     

高超音速流场中锥体边界层转捩图象的纹影显示及处理

本文介绍了一种大画幅纹影成像技本,应用该技术,显示了高超音速流场中锥体边界层转捩。将所得到的纹影图象在显微密度计图象处理系统中进行处理与测量,并结合纹影法原理进行了分析计算,得到了边界层诸截面相对密度变化曲线以及边界层转捩位置等实验结果,该结果与有关气动理论和实践结果进行了比较。     

ε′对旋光光纤特性影响的理论分析与计算

通过对旋光光纤基本理论的讨论，以ε′为自变量为旋光光纤的基本参量和电磁场分量进行了数值分析，得出了相应的计算图表，另外，通过对实际的旋光光纤进行旋光角测量和进一步分析，论证了ε′与偏置磁场之间具有简单而明确的线性关系。这使得原本复杂的张量介电常量矩阵的求解变得非常简单。     

Preparation and nonisothermal crystallization behavior of polyamide 6/montmorillonite nanocomposites

Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X‐ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in γ‐crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami‐Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2878–2891, 2004     

用样条函数表示非球面方程式的光线追迹

提出用样条函数来表示非球面方程式,它优于一般的非球面方程式表示法,便于计算。