多环化合物的芳香性

介绍了简单判断多环化合物的芳香性、非芳香性、反芳香性、同芳香性及反同芳香性的方法及其在有机化学中的应用.     

Reinforcement of Biodegradable Poly(DL-lactic acid) Material by Equal-Channel Angular Extrusion

The purpose of this study was to reinforce biodegradable poly(DL -lactic acid) (PDLLA) material using a new method, equal-channel angular extrusion (ECAE). Different processing parameters, including the number of extrusion passes and the process temperature, were investigated to analyze their effect on the PDLLA properties. Experimental results indicate that the mechanical strength of PDLLA increased with the number of extrusion passes. The extrusion temperature also affected the mechanical strength of the PDLLA. After two ECAE passes, the bending strength of PDLLA increased from 83.3 to 178.7 MPa. The bending fracture mode for PDLLA changed from brittle failure for initial specimens to ductile fracture after ECAE processing. SEM micrographs showed that the longitudinal split surfaces of PDLLA are of a fibrillar structure. Taken together, the results suggest that ECAE might represent a useful approach for the preparation of reinforced PDLLA.     

Extension of isometries between the unit spheres of complex l(Γ)(p>1)spaces

In this paper, we study the extension of isometries between the unit spheres of complex Banach spaces l^p(Γ) and l^p(Δ)(p > 1). We first derive the representation of isometries between the unit spheres of complex Banach spaces l^p(Γ) and l^p(Δ). Then we arrive at a conclusion that any surjective isometry between the unit spheres of complex Banach spaces l^p(Γ)and l^p(Δ) can be extended to be a linear isometry on the whole space.     

Pd修饰对Cd0.8Zn0.2S/SiO2光催化甘油水溶液制氢性能的影响

用等体积浸渍法制备了不同Pd负载量的Pd/Cd_0.8Zn_0.2S/SiO₂光催化材料,采用XRD、H₂-TPR、XPS、UV-vis DRS和光催化反应评价等方法对光催化材料的表面结构、光吸收性能以及光催化甘油水溶液制氢反应性能进行了考察。研究结果表明,ZnS与CdS在SiO₂表面形成了Cd_0.8Zn_0.2S固溶体,金属Pd负载未对固溶体Cd_0.8Zn_0.2S/SiO₂的结构造成影响;金属Pd修饰明显地提高了原固溶体的光响应性能,拓展了其吸光域,增强了吸光效率。金属Pd修饰后,Cd_0.8Zn_0.2S/SiO₂的光解甘油水溶液产氢速率显著提高,Pd负载量为0.5%的Pd/Cd_0.8Zn_0.2S/SiO₂具有最佳的光催化甘油水溶液制氢性能,其在紫外光照射下的氢气生成速率为831 μmol/h,较未负载时提高了近四倍;模拟太阳光下为153 μmol/h,较未负载时提高了近两倍。     

Acetate coverage effect on the reactivity of vinyl acetate synthesis on Pd/Au alloy surfaces

Vinyl acetate (VA) synthesis on Pd/Au(111) and Pd/Au(100) surfaces has been systematically investigated through first-principles density functional theory (DFT) calculations. The DFT results showed that for VA synthesis, the ‘Samanos’ reaction mechanism (i.e., direct coupling of coadsorbed ethylene and acetate species and subsequent β-hydride elimination to form VA) is more favorable than the ‘Moiseev’ mechanism (i.e., ethylene first dehydrogenates to form vinyl species which then couple with the coadsorbed acetate species to form VA). More importantly, it was found the surface coverage of acetate has a significant effect on the reactivity of VA synthesis, and the activation energy of the rate-controlling step on Pd/Au(100) surface is smaller than that on Pd/Au(111) surface (0.88 vs. 0.95 eV), indicating the former is more active than the latter.     

蓝色低压阴极射线荧光粉ZnSⅩⅣZn,Pb的研究

研制的阴极射线用低压蓝色荧光粉ZnSⅩⅣMn,Pb的亮度高于现行使用的ZnSⅩⅣMn,与ZnOZn相近,且发光峰值位置接近ZnSⅩⅣMn.当与粒径为荧光粉颗粒的二分之一的In2O3混合时,其临界电压从80V降低到8V.这种荧光粉将适用于场发射显示器件中.     

有机材料在各种波长的折射率计算

使用Vogel方法和介质的色散关系,计算有机化合物在各波长的折射率n(λ).用Vogel方法把化合物分子分解成碎片,加和得到化合物在某几个波长的折射率.假设化合物在所计算的波长范围内为正常色散关系,使用Voyel方法得到的两个折射率,通过Cauchy公式得到色散曲线,从而得到各波长的折射率n(λ).通过对有机化合物芪盐和高分子材料聚苯乙烯的各波长折射率进行计算,并与材料在某一特定波长的实际折射率对比,证明了计算结果比较准确.并对双折射液晶材料的折射率计算进行了探索.     

BuFCl:Eu2+中两种F色心的浓度比值与光激励截面比值的测定方法

本文研究了紫外线辐照下BaFCl:Eu2+的光激励发光性质.通过改变激励方式及激励光的扫描方向,给出了BaFCl:Eu2+光激励发光过程中,两种F色心的浓度比值和光激励截面比值的测定方法.     

ZnS:Zn,Pb蓝粉在低压阴极射线激发下的应用

通过对ZnS:Zn,Pb蓝色荧光粉进行表面包覆SiO₂以改善其稳定性;In₂O₃材料的适量混合,提高了荧光粉的导电性,降低了它的起辉电压。采用沉淀法制备荧光屏,考察了阳极电压和阳极电流对亮度以及衰减过程的影响,实验结果表明ZnS:Zn,Pb的性能优于ZnS:Ag,Cl和ZnS:Zn,可适用于FED等低压显示器。     

晶面结构非均匀性对金刚石晶形的影响

 不仅考虑表面能，同时也引入表面结构非均匀性自由焓G_stⁱ，通过热力学分析，解释了随着晶体的逐渐长大而{110}面常在金刚石的外形中消失的机理，并用逆推法计算了有关数值。