EZ模型中的有限尺寸效应

研究EZ模型中的有限尺寸效应.当经纪人数目N足够大及发生交易的概率a1/N，发现有限尺 寸效应是重要的.此时，系统几乎变成包含所有经纪人的单一集团.而对较小集团，尺寸分布 仍然服从幂函数律，但是指数因涨落效应而改变.但当a1/N时，可以论证涨落效应不重要 ，因而平均场理论是严格成立的. 关键词： EZ模型 有限尺寸效应 涨落 平均场理论     

Characterization of multilayer nanofiltration membranes using positron annihilation spectroscopy

Positron annihilation spectroscopy (PAS) coupled with a slow positron beam was used to characterize in situ the layer structure and depth profile of the cavity size in thin film composite (TFC) polyamide nanofiltration (NF) membranes prepared by the interfacial polymerization method. Two techniques, using PAS coupled with a slow positron beam of Doppler broadening energy spectra (DBES) and positron annihilation lifetime spectroscopy (PALS) designed to reveal the layer structure and the cavity sizes contained in a multilayer thin film composite NF membrane, were assessed. To the best knowledge of the authors, a characterization of the depth profile of cavities in NF membranes using PAS coupled with a slow positron beam has never been reported. The membranes selected have a composite structure containing three layers: a selective polyamide layer, a transition layer, and a porous support prepared by the phase inversion technique. Furthermore, the cavity size distribution in the selective top layer plays an important role in determining the performance of the NF membranes.     

多孔弹性介质三层夹心板的隔声性能研究

应用Biot关于流体饱和多孔弹性介质的声传播理论,采用传递矩阵的分析方法,就复合多孔弹性材料夹心三层板在不同结构情况下的隔声性能进行了理论研究和实验分析,并与同等条件下双层夹心板的隔声性能进行了比较。数值计算和实验结果均表明,与双层夹心板相比,三层夹心板在中高频段隔声性能有明显优势,但低频段隔声性能有一定程度上的下降。研究还表明不同结构的复合三层夹心板在隔声效果上也各有特色。     

巨磁阻微流体免疫传感器快速定量检测D-二聚体

将巨磁阻(GMR)传感器集成在微流体通道中,以100 nm磁颗粒为信号探针,研制了可快速检测血栓标志物D-二聚体的免疫传感器.用GMR传感器在线检测免疫反应后被捕捉在芯片上的磁颗粒的信息,测定血浆中D-二聚体的含量.通过对反应条件的优化,建立了GMR微流体传感器检测血浆中D-二聚体的方法.本方法的线性检测范围为5～6500 ng/mL,检出限为5 ng/mL.批内相对标准偏差＜12％;批间相对标准偏差＜14％,具有良好的稳定性和重现性.本方法可在9 min内完成检测,临床血浆样本的测试结果与日本Sysmex公司的CA1500血凝仪测试结果一致,具有灵敏度高、检测时间短、检测结果准确等优点.     

Multilayered poly(vinylidene fluoride) composite membranes with improved interfacial compatibility: correlating pervaporation performance with free volume properties

A spin-coating process integrated with an ozone-induced graft polymerization technique was applied in this study. The purpose was to improve the poor interfacial compatibility between a selective layer of poly(2-hydroxyethyl methacrylate) (PHEMA) and the surface of a poly(vinylidene fluoride) (PVDF) substrate. The composite membranes thus fabricated were tested for their pervaporation performance in dehydrating an ethyl acetate/water mixture. Furthermore, the composite membranes were characterized by field emission scanning electron microscopy (FE-SEM) for morphological change observation and by Fourier transform infrared spectroscopy equipped with attenuated total reflectance (ATR-FTIR) for surface chemical composition analysis. Effects of grafting density and spin-coating speed on pervaporation performance were examined. The composite membrane pervaporation performance was elucidated by means of free volume and depth profile data obtained with the use of a variable monoenergy slow positron beam (VMSPB). Results indicated that a smaller free volume was correlated with a higher pervaporation performance of a composite membrane consisting of a selective layer of spin-coated PHEMA on a PHEMA-grafted PVDF substrate (S-PHEMA/PHEMA-g-PVDF). The composite membrane depth profile illustrated that an S-PHEMA layer spin-coated at a higher revolutions per minute (rpm) was thinner and denser than that at a lower rpm.     

Local Minority Game with Evolutionary Strategies

We study a model of local minority game in the random Kauffman network with evolutionary strategies and propose three methods to update the strategy of poor agents, with lower points in a given generation： namely to update either the Boolean function of their strategies randomly, or their local information of randomly adjacent m agents, or the number m of randomly chosen adjacent agents. The results of extended numerical simulations show that the behaviour of strategies in the three methods may enhance significantly the entire coordination of agents in the system. It is also found that a poor agent tends to use both small m strategies and correlated strategies, and the strategies of agents will finally self-organize into a steady-state distribution for a long time playing of the game.     

一种侧链共轭噻吩共聚物增强的三阶非线性光学特性

侧链共轭的聚噻吩衍生物具有拓宽的共轭程度,有望成为一类性能优良的三阶非线性光学材料.合成了一种侧链共轭的噻吩共聚物:聚 -噻吩(POTVTh-Th),该聚合物与其均聚物相比,吸收光谱发生了明显的红移,禁带宽度为1.72eV.采用Z扫描技术在800nm下用飞秒激光器研究了该聚合物溶液和薄膜的三阶非线性光学特性,结果表明该共聚物四氢呋喃溶液中的三阶非线性极化率为8.84×10^-10esu,聚合物薄膜的三阶非线性极化率为7.25×10^-9esu,分别是其 关键词： 侧链共轭 噻吩共聚物 三阶非线性极化率 非线性吸收     

Two New Furo[3,2-c]Quinolines from the Stems of Nicotiana tabacum and Their Anti-Tobacco Mosaic Virus Activity

Chemistry of Natural Compounds - Two new (1 and 2), together with two known (3 and 4), quinoline alkaloids were isolated from the stems of Nicotiana tabacum. Their structures were elucidated using...     

经纪人模仿在演化少数者博弈模型中引入的自组织分离效应

引入真实金融市场中普遍存在的模仿机理,提出并研究了一种新的演化少数者博弈模型.在该模型中,所有的经纪人排列成满足一维周期性条件的链并有一个共同的策略.每个经纪人有一个概率p值,作决定时以概率p选择策略预测的取胜方,以概率1-p作出相反的决定,同时经纪人可以模仿财富高于自己的最近邻邻居的p值.数值模拟结果显示,通过演化使得经纪人组成的系统自组织分离成由极端行为表征的相反人群.模仿引起的演化可以明显提高系统的协作. 关键词： 科学与社会 自组织系统     

Two New Anti-Tobacco Mosaic Virus Isoindolin-1-Ones from the Leaves of Nicotiana tabacum

Chemistry of Natural Compounds - Two new isoindolin-1-ones, 6-(3-hydroxypropyl)-2,4-dimethylisoindolin-1-one (1) and 4-(hydroxymethyl)-6-(3-hydroxypropyl)-2-methylisoindolin-1-one (2), were...