无捕收剂浮选的半导体能带理论讨论

用量子力学计算得到了方铅矿(PbS)和黄铁矿(FeS_2)的半导体能带图,以及分子氧和HS-离子的HOMO和LUMO的能量。计算结果画成方铅矿和黄铁矿半导体与分子氧和HS-离子作用的能级图,从电子转移微观层次上解释这两类矿物的无捕收剂浮选机理(包括自诱导浮选和硫化钠诱导浮选)。结果表明,P型半导体(以黄铁矿为典型代表)具有良好硫化钠诱导浮选行为,N型半导体(以方铅矿为典型代表)具有良好自诱导浮选行为。电子载流子浓度(n_e)与空穴载流子浓度(n_p)之比值可以作为一个参数来判断无捕收剂浮选行为:n_c/n_p值大,自诱导浮选行为好;n_p/n_e值大,硫化钠诱导浮选行为好。     

海内关外--港珠澳大桥澳门口岸交通配套工程设计实践

本文通过对港珠澳大桥澳门口岸交通配套工程项目的规划、设计和工程建设方面进行阐述和思考。提出了如何通过高效集约、功能整合及群体逻辑等来探讨解决澳门口岸交通换乘复杂性与地域的特殊性的问题、也通过在澳门项目中以国际模式进行工程实践的经验和总结,为我们今后深入实施建筑师负责制初步探索。     

Living and non-living Ziegler-Natta catalysts: electronic properties of active site

Most of polymerization reactions with Ziegler catalysts operate through the ‘non-living’ mechanism, whereas lanthanide catalysts show a living-mechanism character. The degree of ‘livingness’ in a polymerization reaction is generally investigated through kinetics and the product analysis rather than by direct analysis of a catalyst. We have developed a new insight for judging the ‘livingness’ in polymerization reaction in aspect of electronical properties of the active chain ends of Li, Ni and Nd catalysts for 1,3-butadiene polymerization using the frontier orbital analysis. The frontier orbitals of the Ni catalyst are different from those of the Li and Nd based catalysts. The HOMO of the Ni catalyst has mostly the d-orbital (Ni) character while the LUMO has the p-orbital (C_α and C_γ atoms) as well as the d-orbital (Ni) character. The π-butenyl coordination at the Ni catalyst is η¹-type but those of the Nd and Li catalysts are η³. The atomic charge (+0.003) on the Ni atom and the atomic charge (−0.14) on C_α of the Ni catalyst are much lower than those of the Nd catalyst (Nd +1.09, C_α −0.56).     

Ozonation of naphthalene sulfonic acids in aqueous solutions: part II--relationships of their COD,TOC removal and the frontier orbital energies

This paper evaluated the COD, TOC removal and molecular frontier energies in the ozonation of naphthalene sulfonic acids (NSAs). It was found that both COD and TOC degradation of the 11 compounds followed the pseudo-first-order kinetic and the reaction rate constants with ozone varied widely. A linear relationship between logarithm of global COD degradation rate constant and the energy of the highest occupied molecular orbit, E(homo), was obtained for these NSAs with a regression coefficient of 0.88 and a slope of 0.4672 eV(-1). TOC degradation kinetics also reached similar results with a regression coefficient of 0.90 and a slope of 0.9336 eV(-1). The results of correlation analysis suggested that TOC and COD removal in ozonation of NSAs follow the frontier orbital theory and can be predicted by E(homo), which indicated that electrophilic effect was the main factor in the ozonation of NSAs. Therefore, it is possible to improve the biodegradability of dyestuff wastewater bearing mainly NSAs by ozonation at an accepted cost and evaluate the economy of ozonation process.     

边境口岸型综合保税区规划设计——以新疆阿拉山口综合保税区规划为例

边境口岸型综合保税区是面向周边国家市场的、特殊的海关监管区域,具有独特的功能特征与规划要求。新疆阿拉山口综合保税区规划根据保税区面临的交通流线复杂、国内外轨道标准不一致、货物种类多样和国际市场不确定因素较多等问题,通过功能分区、空间布局和交通组织的规划方法,归纳出边境口岸型综合保税区的规划要点,即在满足海关监管要求的同时,强化综合交通流线的组织引导,按照货物储运条件优化空间布局及突出对用地开发的弹性考虑。     

中国区域科技成果转化效率研究—基于DEA和SFA的比较分析

搜集省际面板数据,运用非参数数据包络分析方法(DEA)和参数随机前沿分析方法(SFA)对中国区域科技成果转化效率进行测算。结果表明,2种方法计算的科技成果转化整体效率水平均不高,SFA方法测算的值大于DEA方法测算的值。2种方法的聚类结果进一步表明:SFA方法更好地拟合各地区科技成果转化现况;科技成果转化存在东、中、西部不平衡的现象。     

Efficient enhancement of second order nonlinear optical response by complexing metal cations in conjugated 7-substituted coumarin

Most of the coumarins have been found useful as non-linear optical chromophores. The four novel water-soluble coumarin-based compounds (OC6, NC6, OC7, and NC7) and the metallic compounds of NC7 with different metal cations (Na⁺, K⁺, Mg²⁺, Ca²⁺, Fe²⁺, and Zn²⁺) have been investigated by carrying out density functional theory (DFT). Our DFT calculations revealed that the second-order nonlinear optical properties have a pronounced enhancement by means of the introduction of π-conjugatd electron donor (dimethylamino phenyl alkynyl) in 7-position of the coumarin ring and metal cations, especially for transition metals. The further investigations of the larger first hyperpolarizability (β_tot) reveal that the NC7*Fe²⁺ and NC7*Zn²⁺ present the larger values as 1.151 × 10⁻²⁷ and 1.083 × 10⁻²⁷ esu owing to the lower transition energies and larger oscillator strengths of crucial electronic transitions. Moreover, time-dependent DFT results show that the large intramolecular charge transfers exist in the NC7*Fe²⁺ and NC7*Zn²⁺. In addition, the natural bond orbital analysis demonstrated that the second-order stabilization energies is from the lone pair (LP) orbital on O atom to the LP* orbital of metal cations interaction correlate with the O-Mⁿ⁺ atomics distance. On the other hand, the atoms in molecules analysis showed that the O-Mⁿ⁺ interactions can be characterized by the presence of a bond critical point (BCP) and the O-Fe²⁺ and O-Zn²⁺ interactions have partially ionic and partially covalent bonds rather than an electrostatic character for O-Mⁿ⁺ (Na⁺, K⁺, Mg²⁺ and Ca²⁺). In addition, the delocalization indices of O-Mⁿ⁺ bonds correlate reasonably well with electron density, kinetic and potential energy densities in these complexes. Thus, we hope this research will introduce a new relation between the structure and the property of chromophore nonlinear optical activity.     

边塞建筑特征及其当代设计传承方法浅析

“边塞”是古代黄河流域农耕文明 与北方游牧文明互动的历史产物,历代大规 模的边塞营建和屯田活动将中原文明推广至 边塞地区,并与当地自然环境、社会经济、民 族文化相互碰撞融合,逐渐形成边塞文化。 边塞建筑作为边塞文化的物质载体,亦具有 鲜明的地域文化特征。文章以研究边塞建筑 形态及空间的文化特征、艺术特征为切入点, 提炼出边塞建筑现象中蕴含的多种空间意象 及其形式规律,结合当今的地域建筑创作及 设计方法,讨论边塞建筑形式与空间中可能 存在的现代传承性和适用性。     

Regulation and performance: A production frontier estimate for the Latin American water and sanitation sector

The objective of this paper is to analyze the efficiency of the water sector in Latin American countries. We try to find factors affecting efficiency rather than identifying which country or individual provider is more or less efficient. We also consider which model would be more fitting for the water sector production in this region. Our motivation is to develop instruments to make benchmarking operative for regulatory actions that can reduce information asymmetry and increase efficiency in Latin American countries. We estimate econometric efficiency frontiers using data from a regional survey conducted by the Latin American Association of Water Regulators. The paper develops a model based on the core variables that explain the phenomena and explores “environmental” (contextual or beyond management control) variables to achieve fair comparisons. The study does not “name and shame” services but provides elements to foster the development of indicative goals at the regional level.     

机械工程前沿研究在汽车轻量化中的应用前景分析

对后门上铰链安装板进行冲压工艺性分析,采用多工位级进模冲压生产。介绍了制件排样设计、模具结构设计及模具 关键零件设计。模具采用自动送料机构作粗定位、导正销精定位,保证了送料精度;凸、凹模镶块均采用镶拼式结构,便于维修; 材料选用DC53,提高了模具寿命和减少加工工序。目前,模具运行情况良好,产品质量稳定,达到了预期效果。