Two‐component calculations of spin–orbit effects for a van der Waals molecule Rn2

Electronic structures of the weakly bound Rn₂ were calculated by the two‐component Møller–Plesset second‐order perturbation and coupled‐cluster methods with relativistic effective core potentials including spin–orbit operators. The calculated spin–orbit effects are small, but depend strongly on the size of basis sets and the amount of electron correlations. Magnitudes of spin–orbit effects on D_e (0.7–3.0 meV) and R_e (−0.4∼−2.2 Å) of Rn₂ are comparable to previously reported values based on configuration interaction calculations. A two‐component approach seems to be a promising tool to investigate spin–orbit effects for the weak‐bonded systems containing heavy elements. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 139–143, 1999     

A theoretical study of bond energies in model Si–H–Cl molecules using density functional approaches for representing Si surface chemistry

The reliability of density functional theory (DFT) methods for calculating Si(SINGLE BOND)2H, Si(SINGLE BOND)Cl, and Si(SINGLE BOND)Si bond energies is examined in reactions involving molecules and small clusters representing various surface sites appropriate for Si surface chemistry. Results are presented for systematic studies using a valence double-zeta polarization basis for both all-electron calculations and valence–electron calculations employing effective core potentials (ECPs). All-electron DFT results are comparable to much more demanding MP4, G2, and MC–SCF–CI calculations for computed bond energies. Whereas the use of ECPs introduces systematic energy differences of ca. 3–5 kcal/mol compared to AE results, depending on the type of bond involved, the use of ECPs for carrying out calculations on larger clusters is discussed where AE calculations become more computationally demanding. The convergence of Si bond energies as a function of replacing hydrogens with silyl groups is examined. In constructing models to describe etching processes involving Cl species on Si surfaces, the need for incorporating differences in thermochemistries for one-, two-, and three-coordinate Si surface sites is emphasized. Comparisons of semiempirical approaches for thermochemistries of Si-containing species find these methods somewhat less reliable for obtaining reliable bond energies compared to computationally more demanding DFT and ab initio correlated models. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 2075–2085, 1997     

Multicomponent latex IPN materials. I. Morphology control

A series of novel structured latex particles with interpenetrating polymer network (IPN) cores and glassy SAN shells were developed in an attempt to investigate the feasibility of these polymers as both toughening and damping agents in thermoplastics. The IPN cores were composed of one impact part (polybutadiene based) and one damping part (acrylic based, with T_g around +10°C). The particle morphologies of these polymers were determined by TEM. The glass transitions and mechanical behavior of the polymers were characterized from DMS. The effect of different components on the final core/shell particle morphologies and mechanical properties was studied. The mechanical behavior of core/shell particles with IPN cores was also compared with that of separate core/shell and multilayered core/shell particles. In addition, normal core/shell synthesis (rubbery part first then the glassy part) and inverted core/shell synthesis (glassy part first then the rubbery part) were performed to provide another access for morphology control. It was found that the core/shell latex particles with poly(butyl acrylate) based copolymers are more miscible than poly(ethylhexyl methacrylate)-based copolymers. The high grafting efficiency of poly(butyl acrylate) plays an important role in governing phase miscibility. The latex particles synthesized by the inverted core/shell mode showed higher miscibility than the normal synthesized ones. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2193–2206, 1997     

Core Shell Nanostructure: Impregnated Activated Carbon as Adsorbent for Hydrogen Sulfide Adsorption

This study focuses on the synthesis, characterization, and evaluation of the performance of core shell nanostructure adsorbent for hydrogen sulfide (H₂S) capture. Commercial coconut shell activated carbon (CAC) and commercial mixed gas of 5000 ppm H₂S balanced N₂ were used. With different preparation techniques, the CAC was modified by core shell impregnation with zinc oxide (ZnO), titanium oxide (TiO₂), potassium hydroxide (KOH), and zinc acetate (ZnAC₂). The core structure was prepared with CAC impregnated by single chemical and double chemical labelled with ZnAC₂-CAC (single chemical), ZnAC₂/KOH-CAC, ZnAC₂/ZnO-CAC, and ZnAC₂/TiO₂-CAC. Then, the prepared core was layered either with KOH, TiO₂, NH₃, or TEOS for the shell. The synthesized adsorbents were characterized in physical and chemical characterization through scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analyzers. Operation of the adsorber column takes place at ambient temperature, with absolute pressure at 1.5 bar. The H₂S gas was fed into the column at 5.5 L/min and the loaded adsorbents were 150 g. The performance of synthesized adsorbent was analyzed through the adsorbent’s capability in capturing H₂S gas. Based on the results, ZnAc₂/ZnO/CAC_WOS shows a better adsorption capacity with 1.17 mg H₂S/g and a 53% increment compared to raw CAC. However, the degradation of the adsorbents was higher compared to ZnAc₂/ZnO/CAC_OS and to ZnAc₂/ZnO/CAC_WS ZnAc₂/ZnO/CAC_OS. The presence of silica as a shell has potentially increased the adsorbent’s stability in several cycles of adsorption-desorption.     

化学工业新进展对人力资源的要求

介绍化学工业以及与之相关学科的新发展,论述了化学化工学科与生物、材料、能源、信息、环境等学科的交叉特征,在此基础上浅析了化学化工学科人才培养、人力资源开发的新要求.     

论特色经济与提升西部民族地区核心竞争力

区域核心竞争力能够支持一个区域经济长期和持续不断地发展。特色经济由于其独占性、效益性、辐射和扩散性以及可持续性,是提升区域核心竞争力的内生力量。对西部民族地区而言,利用其独有的资源条件发展特色经济,能够将民族地区的比较优势转化为竞争优势,并形成民族地区的核心竞争力,从而促进西部民族地区经济的持续快速发展。     

再论道德叙事

西方道德教育从强调道德相对主义到提倡核心价值观,反映了西方社会对学校道德教育实效性的一种反思.20世纪90年代,复兴的品格教育把古老的道德叙事这种道德教育方法运用到学校、家庭、社会中进行核心价值观的教育取得一定的成效.作为西方社会进行核心价值观教育的有效方法,道德叙事将给我国学校德育工作带来有益的启示.     

Uniqueness and Flat Core of Positive Solutions for Quasilinear Elliptic Eigenvalue Problems in General Smooth Domains

The structure of positive solutions to the quasilinear elliptic problems –div(|Du|^p–2Du = λf(u) in Ω, u = 0 on ∂Ω, p > 1, Ω ⊂ R^Na bounded smooth domain, is precisely studied when λ is sufficiently large, for a class of logistic‐type nonlinearities f(u) satisfying that f(0) = f(a) = 0, a > 0, f(u) > 0 for u ∈ (0,a), , while u = a is a zero point of f with order ω. It is shown that if ω ≥ p – 1, the problem has a unique positive solution u_λ with sup _Ω u_λ < a, which develops a boundary layer near ∂Ω. It is shown that if 0 < ω < p – 1, the problem also has a unique positive solution u _λ, but the flat core {x ∈ Ω : u_λ(x) = a} ≠ ∅︁ exists. Moreover, the asymptotic behaviour of the flat core is studied as λ → ∞.     

PBT/POE-g-MAH/PP共混体系的相态结构与性能

采用马来酸酐接枝乙烯-辛烯共聚物弹性体(POE-g-MAH)与聚丙烯(PP)在双螺杆挤出机上进行熔融共混,制备了3种新型增韧改性剂.研究了增韧改性剂的种类及其用量对共混物的力学性能、相形态结构、熔融与结晶行为的影响.力学性能测试表明,POE-g-MAH与适量PP并用具有显著的协同增韧作用,当POE-g-MAH与PP的配比为70/30时,所得增韧改性剂(POEg2)具有最佳的增韧效果.当POEg2含量达到15%时,共混物的缺口冲击强度(Is)从纯PBT的7.5 kJ/m2提高到51.2 kJ/m2,与15%的纯POE-g-MAH弹性体增韧PBT具有相近的缺口冲击强度值.同时,共混物的拉伸强度(σb)损失最小.采用AFM和SEM观察发现,新型增韧改性剂作为分散相具有软壳-硬核结构.DSC测试表明,随增韧改性剂中PP含量增加到一定值时,壳-核结构中软壳层出现不完整现象,导致界面作用力减小,共混物的Is和σb都出现明显下降.     

水绿矾的状态方程和高压熔化

 用阻抗匹配法和压电探针技术测量了初始密度为1.714 g/cm³（孔隙率α=ρ₀/ρ₀₀=1.898/1.714=1.107）的水绿矾（FeSO₄·7H₂O）的冲击压缩线,发现其在0～100 GPa范围内存在两个明显相区：含有部分熔融的低压相和完全熔化的高压相。在两个相区内,冲击波速度D和波后粒子速度u可分别描述为：D=0.59+2.06u（u<3.12 km/s）和D=3.18+1.223u（u≥3.12 km/s）。从冲击压缩数据出发,用欧拉有限应变理论得到了其等熵状态方程。其熔化方程可用p_m(GPa) =0.159(T_m(K)/1000)^6.3371+0.69来近似描述。