High efficiency D-A structured luminogen with aggregation-induced emission and mechanochromic characteristics

A novel luminogen, CZ2TPAN, with typical D-A architecture was obtained. It shows intramolecular charge transfer and aggregation-induced emission characteristics with high solid-state efficiency of 65.3%. Moreover, it exhibits reversible mechanochromic behavior between crystalline and amorphous states with remarkable emission color change from green (504 nm) to yellow (545nm).     

The research of human exposure to polybrominated diphenyl ethers and perfluoroocatane sulfonate

As two kinds of emerging chemicals, the pollution of polybrominated diphenyl ethers （PBDEs） and perfluoroocatane sulfonate （PFOS） has been becoming a global environmental problem. Also, research of the transport, transfer, bioaccumulation in organism, and toxicology of these two kinds of pollutant is a hotspot in environmental sciences now. In this paper, we summarize and critically review the status and progress of PBDEs and PFOS exposure to human beings. Further, data analyses based on statistical methods are done to study the characters of PBDEs and PCBs concentrations in different regions in the world.     

An analytical method for chlorinated paraffins and their determination in soil samples

Short chain chlorinated paraffins (SCCPs) are possibly persistent organic pollutants (POPs), and are candidate POPs of the Stockholm Convention. In this study, three quantitative methods for analyzing CPs were compared using a gas chromato-graph-electron capture detector (GC-ECD), gas chromatograph-electron capture negative ion low resolution mass spectrometry (GC-ECNI-LRMS) and gas chromatograph-electron ionization tandem mass spectrometry (GC-EI-MS²). A quantitative method for the analysis of total CPs in soil samples was established. The environmental levels of CPs in an e-waste dismantling area in China were evaluated.     

Contamination trends of polybrominated diphenyl ethers, organochlorine pesticides and heavy metals in sediments from Dagu Drainage River estuary, Tianjin

Concentrations of polybrominated diphenyl ethers （PBDEs）, organochlorine pesticides （OCPs） and heavy metals in two sediment cores, taken from the Dagu Drainage River, were determined. The contamination trends of these three kinds of compounds were obtained. The results showed that concentrations of PBDEs increased in recent years; there were new contamination sources for OCPs in this area; contamination levels of heavy metals had no significant change in the last several years. Comparing the results of these two cores, erosion and dilution of seawater had different effects on the transportation of these compounds.     

Concentrations, profiles and gas-particle partitioning of PCDD/Fs, PCBs and PBDEs in the ambient air of an E-waste dismantling area, southeast China

Polychlorinated diebenzo-p-dioxins （PCDDs）, polychlorinated diebenzofurans （PCDFs）, polychlorinated biphenyls （PCBs） and polybrominated diphenyl ethers （PBDEs） were monitored in the ambient air of Taizhou, an E-waste dismantling area of southeast China to evaluate their concentrations, profiles and gas-particle partitioning. The ∑PCDD/Fs concentrations ranged from 2.91 to 50.6 pg/ma, with an average of 14.3 pg/ma. The I-TEQs for PCDD/Fs were in the range of 0.20-3.45 pg/ma, with an average of 1.10 pg/ma, The ∑PCBs concentrations and TEQs ranged from 4.23 to 11.35 ng/ma, 0.050 to 0.859 pg（TEQ）/ma, respectively. The concentrations of ∑PBDEs ranged from 92 to 3086 pg/ma, with an average of 894 pg/ma, The pollution levels of PCDD/Fs, PCBs and PBDEs were higher than other urban sites, which may be associated with the E-waste dismantling activities. The PCDD/Fs were found exclusively in the particle phase whereas PCBs distributed dominantly in the gas phase. The gas-partilce partitioning was also assessed by correlating the gas-particle partition coefficient （Kp） with the subcooled liquid vapor pressure （pL^0）. The measured particulate sorptions of PCDD/Fs, PCBs and PBDEs were compared with the predictions from Junge-Pankow model and Koa absorption model. The Junge-Pankow model well estimated the particulate fractions of PCBs. However, it underestimated the sorptions of PCDD/Fs and overestimated the fractions of PBDEs. The predicted particulate fractions of PCDD/Fs and PCBs from Koa model fitted well with the measured data.     

基于LDA的中文词语相似度计算

针对基于语料库统计的词语相似度计算方法存在的一些缺陷,如：计算量大、向量的特征维度高、特征稀疏、忽略了词语的语义信息等,提出了一种基于latent Dirichlet allocation（LDA）的词语相似度计算方法,通过将词语的特征向量映射为词语的主题分布来计算词语间的相似度;通过与基于《知网》的词语相似度计算方法的对比,证明了该方法能有效降低特征维度,并具有较好的词语相似度计算效果。     

Preparation of nano-compounded polyolefin materials through in situ polymerization technique: status quo and future prospects

Nano-compounding of polyolefins, an economical yet very effective route to high-performance polyolefin materials, has received considerable attention in recent years. Unlike most of the other polymers, polyolefins are chemically inert, which dictates that nano-compounding of polyolefins has to be conducted via in situ polymerization. In this review, a technological progress of the nano-compounding of polyolefins via in situ polymerization technique was summarized thoroughly, with emphasis laid on the current research status of polyolefin/montmorillonite (MMT) nanocomposites. A clear perspective for future researches on this specific family of materials was envisaged. Supported by National Natural Science Foundation of China (Grant No. 50373048) and State Key Development Program of Basic Research Program of Ministry of Science and Technology of China (Grant No. G2003CB615600)     

参与式方法在雁门关地区生态环境恢复及扶贫中的应用

由于在"中日技术合作雁门关地区生态环境恢复及扶贫项目"的执行过程中采用了参与式方法,所以充分调动了农户的积极性,使农户积极参与到整个活动中。通过项目的科学规划、实施、监测和评估,完成了林草种植、畜种改良、设施养殖、水利设施建设和技术普及培训等工作,真正意义上实现了农民脱贫致富和改善生态环境的目标。     

基于Ackermann公式的滑模控制设计方法

从滑模变结构控制的机理出发,设计了具有理想动态特性和较强鲁棒性的滑模控制器。该方法使用了Ackermann公式来设计滑模控制,从而可以使滑模控制的不连续超平面以简单的方式表达。在此基础上引入了Butterworth滤波器传递函数的极点作为系统的理想特征值,使闭环系统及滑模面达到了较理想的动态特性,并采用Sigmoid函数来取代开关函数更有效的抑制滑模控制的抖动;通过倒立摆控制的仿真实例验证了该方法的控制效果,且在系统参数不确定时,取得较快的收敛速度和较好的控制性能。所设计的控制器在系统动态过程中显示改进型Butterworth滤波器的动态特性,静态时在有限时间内到达期望的滑模面的邻域,整个系统具有较为理想的动态特性。