中央环保督察背景下地方政府环境管制行为研究

中央环保督察对环境的改善效果备受肯定,但是这种改善效果的持续性却受到质疑。基于演化博弈理论,本文构建了地方政府和污染企业的动态复制系统,探究中央环保督察压力下空气质量改善的途径。研究结果表明:中央环保督察过程中,空气质量的改善可能来自于地方政府无差别的关停污染企业;中央政府一味地加大对地方政府环保失职的惩罚,可能会导致地方政府采取一刀切式的“懒政”、“怠政”行为;辖区的初始污染水平、管制成本均影响地方政府的行为选择。地方政府一刀切行为是多因素驱动的结果,中央政府应协调各方力量,理性决策,推动中央环保督察的良性运行。     

双色光场驱动产生单个阿秒脉冲过程中的宏观效应

通过数值模拟三维传播方程研究了双色场产生高次谐波过程中宏观效应的影响,重点分析了阿秒脉冲的时域形状.在6 fs/800 nm和21.3 fs/400 nm组成的双色场中,通过调节双色场间的相对延时,双色场各焦点相对于气体盒子入口的间距和双色场束腰半径和气体压强等参数,可以在平台区得到超宽带连续谱.对该连续谱中420—540 eV的谐波直接进行滤波后可以得到时间同步性很好的单个阿秒脉冲.这种性质对实验上通过双色场方案产生超短的阿秒脉冲非常有利. 关键词： 传播效应 阿秒脉冲 时间同步性     

Stabilized vesicles consisting of small amphiphiles for stepwise photorelease via UV light

A small amphiphile consisting of hydrophilic tetraethylene glycol monoacrylate and hydrophobic alkyl chain which were connected by an o-nitrobenzyl unit, a photolabile group, was designed and synthesized. The critical aggregate concentration of the synthesized amphiphile was determined to be about 3 × 10(-5) M by the fluorescence probe technique. Nanosized vesicles were prepared and stabilized by in-situ radical polymerization without altering the morphology. The polymeric vesicle was highly stable which retained vesicular shape under dilution or UV irradiation. Hydrophobic guests can be encapsulated within the vesicle membrane and released out of the vesicle by UV stimulus through splitting the amphiphilic structure of the amphiphile. Distinguished dose-controlled photorelease of the polymeric vesicle is achieved due to the maintenance of the vesicular shape integrity which makes the guest release depend on the cleavage amount of amphiphilic structure during UV irradiation. This study provides a promising strategy to develop stable drug delivery systems for sustained and phototriggered release.     

TiO_2纳米管阵列光电催化制氢研究进展

以TiO2纳米管阵列为光阳极组成的光电解池光电催化分解水是目前光催化制氢领域内研究最广泛的体系之一。本文综述了近年来TiO2纳米管阵列在光电催化分解水制氢领域的最新研究进展,重点阐述了提高TiO2纳米管阵列光电转换效率和产氢速率的方法,指出了目前存在的问题,并对今后的发展提出了展望。     

Fe、N共掺杂TiO2纳米管阵列的制备及可见光光催化活性

应用电化学阳极氧化法结合浸渍和退火后处理制备了Fe和N共掺杂的TiO2纳米管阵列光催化剂,并用场发射扫描电镜(FESEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)和俄歇电子能谱(AES)仪对其进行了表征.结果表明,Fe、N共掺杂对TiO2纳米管阵列的形貌和结构没有明显影响,Fe和N均掺入了TiO2晶格.紫外-可见(UV-Vis)漫反射光谱显示Fe和N共掺杂TiO2纳米管阵列的吸收带边较纯TiO2纳米管阵列和单一掺杂TiO2纳米管阵列红移,可见光吸收增强.以可见光催化降解罗丹明B(RhB)考察了材料的光催化活性,Fe和N共掺杂TiO2纳米管阵列对RhB的降解速率较纯TiO2纳米管阵列和单一掺杂TiO2纳米管阵列明显提高,证明了Fe、N共掺杂产生的协同效应提高了TiO2纳米管阵列在可见光照射下的光催化活性.     

双金属纳米天线在少周期激光中的宽带超快电磁响应

研究了耦合的核壳双金属纳米粒子天线的光场增强与超快时域响应. 在少周期激光的应用中, 如表面等离激元金属纳米器件中的超快响应探测元件, 这种双金属天线展示了超宽带共振频谱及控制局域表面等离激元增强的能力. 研究了二聚体、三聚体以及七聚体, 并且发现三聚体Ag/Au核壳结构显现了极高的场增强能力, 其场振幅增强因子超过了120, 并在5 fs的时间内场振幅迅速衰减为30, 保持了超快的光学响应特性. 利用该结构的表面等离激元增强效应产生高次谐波, 对于产生超快阿秒脉冲有着潜在的重要应用价值. 关键词： 纳米光学天线 双金属球壳结构 少周期激光脉冲 表面等离激元     

EAST装置锂化壁下低杂波等离子体温度行为研究

在EAST全超导托卡马克归一化半径r/a ≤qslant 0.6区域内部, 在高功率低混杂波电流驱动辅助加热下,以及第一壁锂化处理条件下, 在低混杂波注入中期观测到电子温度剖面和离子温度剖面变平的现象. 利用X射线弯曲晶体光谱仪诊断系统,并结合其他相关诊断系统研究了在第一壁锂化条件下, 以及EAST低杂波放电位形下,电子温度剖面和离子温度的剖面行为. 研究结果表明:电子温度剖面和离子温度剖面变平的现象是由于第一壁锂化处理技术对从等离子体边界流向第一壁的粒子流产生了影响,使得边界粒子再循环模式受到抑制, 这种低再循环模式的存在引起了温度剖面的变化.同时观察到离子温度和电子温度彼此接近的现象, 这是由于随着等离子体密度的增加,电子与离子之间的碰撞行为加剧所产生的结果.     

金融危机前后中英美股票市场间波动溢出效应比较

为研究波动溢出效应是否存在于中英美股市问,若存在,波动溢出效应传导机制如何,截取2005年7月22日至2009年6月30日的标准普尔500指数、伦敦金融时报100指数、沪深300指数共1045个日收盘数据,时间段分为金融危机前后,分别构建三元MGARCH-BEKK模型,实证结果表明:(1)金融危机发生前,中英美股市间存在波动溢出效应,传导机制为:先从英国到美国再到中国;(2)金融危机发生后,中英美股市间仍存在波动溢出效应,但传导机制变为:先从美国到英国再到中国。通过比较分析实证结果,得出如下结论:(1)美国是全球股票市场风险的主要来源国,特别是金融危机之后更加明显;(2)中国是全球股票市场风险的主要接受国。     

Morphology and formation mechanism of ceria nanoparticles by spray pyrolysis

Ceria-based materials are used in industrial applications such as catalyst supports, carbon monoxide reduction catalysts, and solid oxide fuel cell electrolytes. Various applications require different morphological particles. The ceria particles with various morphologies from the precursors of cerium(III) acetate hydrate, cerium(IV) nitrate hydrate, and cerium(IV) ammonium nitrate were prepared by spray pyrolysis (SP) because SP has the potential for simple and continuous process. The precursor behaviors and the particle morphologies were characterized by thermogravimetric analysis and by transmission electron microscopy. Four main morphologies of solid spherical, hollow spherical with a single pore, hollow concave, and hollow spherical with multiple pores were observed. The experimental results suggest that the morphological formation mechanism is highly correlated with the factors of precursor solubilities, solvent evaporation rates (droplet diameters), and precursor melting temperatures. In addition, total concentrations of cerium(III) in the ceria particles from various precursors were examined using X-ray photoelectron spectroscopy.     

Synthesis,structures, thermal behaviour,luminescence and magnetic properties of lanthanide complexes constructed from 2,6-dimethylbenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

Six new lanthanide complexes, with the formula [La(2,6-DMBA)₃(5,5′-DM-2,2′-bipy)(H₂O)]₂ (1) and [Ln(2,6-DMBA)₃(5,5′-DM-2,2′-bipy)]₂ (Ln = Tb(2), Dy(3), Ho(4), Pr(5), Nd(6)) (2,6-DMBA = 2,6-dimethylbenzoate, 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine) have been successfully synthesized and characterized. These title complexes have three different structural types. The structure of complex 1(type I) contains coordination water molecules, and the coordination number is 8. The coordination numbers of complexes 2–4 and 5–6 are 8 and 9, showing a distorted square antiprism geometry and distorted monocapped square anti-prismatic geometry, respectively. However they have the same general formula and they can be all assembled into the same 1D, 2D supramolecular structures via the C-H···O hydrogen bonding interactions, which is interesting in previous lanthanide complexes. The complexes were analyzed by TG-DSC/FTIR. In addition, the visible light luminescence experiments of Tb (III) complex was carried out, and the characteristic luminescence behavior of strong green color was shown. And the fluorescence lifetime and intrinsic quantum yield were calculated. The magnetic properties of complexes 2–4 were also studied, and the results showed that complex 3 and complexes 2, 4 have ferromagnetic interactions and antiferromagnetic interactions, respectively.