Potential applications of passive sampling for monitoring non-polar industrial pollutants in the aqueous environment in support of REACH

Possible roles of passive sampling within the context of the European REACH legislation are discussed. Passive samplers can provide information on environmental concentrations, fate and behaviour of substances of concern. They can potentially replace biota in the assessment of bioavailability, having advantages including lower cost and variability, and greater repeatability and acceptability on ethical grounds. Where remedial actions (e.g., product withdrawal, replacement or redesign) may be required, wrong decisions are potentially very costly. Against this background it may be possible to develop strategies based on passive sampling that will protect the environment from potential damage whilst minimising operational costs.     

Assessing indoor air exposures using passive sampling with bioanalytical methods for estrogenicity and aryl hydrocarbon receptor activity

Passive air sampling was undertaken using polyurethane foam passive air samplers at three types of locations, including indoors (six offices) at buildings in the central business district (CBD) and at a private suburban home (indoor and outdoor) located 9 km from the CBD in Brisbane, Queensland, Australia. Estrogenic (E-SCREEN—MCF7-BOS) and aryl hydrocarbon receptor (AhR) (CAFLUX—H4G1.1c2) activity were assessed for samples collected from each of these locations. The samples were tested either as crude extracts (“untreated”) or were subjected to H₂SO₄ silica gel (“treated”) for each location in order to determine whether chemicals, which are not resistant to this treatment like polycyclic aromatic hydrocarbons, potentially account for the observed activity. In most cases, H₂SO₄ treatment resulted in a statistically significant reduction of potency for both endpoints, suggesting that chemicals less resistant to treatment may be responsible for much of the detected biological activity in these locations. Estrogenic potency measurements (<0.22–185 pg m⁻³) were highest in the indoor offices, followed by the indoor suburban home and finally the outdoor suburban home (which was not estrogenic). Total AhR activity for crude extracts (1.3–10 pg m⁻³) however was highest for the outdoor suburban home site. Levels of polycyclic aromatic hydrocarbons were monitored indoors and outdoors at the suburban home. At that location, polycyclic aromatic hydrocarbon air concentrations were on average approximately two times higher outdoor than indoor, while AhR potency was five times higher outdoor than indoor. No significant correlation was found between the estrogenic and AhR activity (P = 0.88) for the sites in this study. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Mixed-integer programming approaches for index tracking and enhanced indexation

We consider the problem of reproducing the performance of a stock market index, but without purchasing all of the stocks that make up the index, index tracking. We also consider the problem of out-performing the index, enhanced indexation. We present mixed-integer linear programming formulations of these problems. Our formulations include transaction costs, a constraint limiting the number of stocks that can be purchased and a limit on the total transaction cost that can be incurred. As our formulations of these problems are mixed-integer linear programs we can use a standard solver (Cplex). Numeric results are presented for eight data sets drawn from major markets. The largest of these data sets involves over 2000 stocks.     

真菌鉴别和检测的SERS光谱技术研究进展

真菌是一种广泛存在于自然界的病原微生物,具有细胞核、细胞壁等结构,可以引起动、植物和人类的多种疾病。真菌感染是临床上常见的感染性疾病之一,使得近年来针对真菌的高效检测及真菌相关领域的研究备受关注。目前真菌的传统检测方法主要有培养、镜检与分子生物学检测法等,均具有操作复杂、耗时等缺点。表面增强拉曼散射(SERS)技术以其不受水分子干扰、能反应分子指纹信息、检测迅速等特点在真菌的检测与鉴别领域逐渐发挥出明显的优势。在简要介绍真菌的结构特点及真菌常用的检测方法基础之上,主要针对拉曼光谱(Raman spectrum)/SRES技术在真菌检测和鉴别中的应用进行调研和讨论。首先通过对Raman/SERS技术的特点以及真菌的结构特征进行解析,根据调研Raman/SERS技术用于真菌检测的相关文献,分析了SERS技术用于真菌检测的可行性,提出SERS技术在真菌检测时会面临检测灵敏度低、信号复杂、选择性和特异性差以及信号重现性和稳定性不佳等难点。为解决以上难题,分析了SERS的增强模式,重点针对SERS的纳米增强介质材料、SERS标签(SERS tag)的信号放大效应以及SERS光谱分析技术与微流控芯片分析技术结合等SERS分析新进展,予以了系统地综述和讨论。通过纳米材料选择和纳米微结构的构建,SERS增强介质所产生的SERS增强效应在真菌鉴别以及临床疾病快速诊断中显示出巨大的发展潜力;基于SERS tag产生的信号放大机制,可以有效提高真菌SERS检测的灵敏度、特异性和重现性;在微流控芯片中设计和集成SERS增强纳米微结构,构建基于SERS tag 的信号放大策略,开展针对真菌的快速高效测试方法研究,更有望实现真菌样本的高通量及高内涵SERS检测,其在真菌的鉴别和检测上显示出巨大的研究价值和应用前景。     

Design of an Ultra‐Compact UHF Passive RFID Tag Antenna for a Medical Sample Tube

In this letter, a small‐sized ultra‐high frequency (UHF) RFID tag antenna for a medical sample tube is proposed. The RFID tag antenna is designed and fabricated based on the circular loop antenna used in the UHF band (Korea standard, 917 MHz to 923.5 MHz). The tag antenna size is reduced using a circular meander stub. The antenna has a physical size of 8 mm, which is about λ/40 in electrical length. The proposed tag antenna is molded into a medical sample and multitag identification is performed.     

一种新型的有源标签防碰撞算法

有源射频识别系统被广泛应用在现代物流、人员追踪与定位中。随着标签数增加,防碰撞问题越来越重要,目前有源标签防碰撞算法普遍比较简单,算法效率不高,而有源标签硬件资源丰富也为设计更好算法提供了可能。提出一种防碰撞算法,采用主从读写器包拯救机制和空闲时隙利用机制,并动态控制帧结束和标签接入,调整接入期收集期顺序。通过对归一化吞吐量的研究与仿真表明,这种新的防碰撞协议性能远优于目前已有研究成果。     

有机基板中埋入无源元件概述

介绍了埋入无源元件在减小基板面积和提高基板高频特性的优点,总结了目前正在应用和研究的埋入电阻和埋入电容技术的实现方法.并提出基于埋入平面薄膜电阻和埋入薄芯介质材料形成平面电容技术的混合埋入技术将成为未来埋入无源元件PCB的主流技术.最后阐述了埋入无源元件技术在产业化过程中遇到的困难.     

一种改进的RFID系统多状态防碰撞算法

标签防碰撞技术是RFID系统中的关键技术和研究热点.详细分析了典型的二进制及其他改进防碰撞算法原理,并在多状态二进制搜索算法的基础上进行了改进和创新.新算法根据标签碰撞的特点,充分利用已得到的冲突信息,取消了激活命令,大大节省了算法时间,并且新算法能够动态选择分叉数量,使得标签的识别效率得到了提高.性能分析表明,该算法比已有的二进制及动态二进制反碰撞算法具有更明显的优势.     

A diode end-pumped passively Q-switched Nd:YAG/KTA Raman laser

A diode end-pumped passively Q-switched Nd:YAG/KTA intracavity Raman laser is presented. A KTA crystal with a size of 5 mm × 5 mm × 25 mm is used as the Raman active medium and its 234 cm^?1 Raman mode is employed to finish the conversion from 1064 nm fundamental laser to 1091 nm Raman laser. A 2 mm thick Cr⁴⁺:YAG crystal is used as the saturable absorber. With an LD pump power of 7.5 W, the first-Stokes power of 250 mW is obtained with a pulse repetition frequency of 14.5 kHz. The corresponding diode-to-Stokes conversion efficiency is 3.3% and the pulse energy is 17.2 μJ. Pulse width is measured to be 12.6 ns and peak power is 1.4 kW.     

一种UHFRFID系统宽带标签天线的设计

基于微带天线结构,设计了一款适用于整个UHF RFID系统的新型宽带标签天线。在H型贴片上开H槽,形成了两个相近的谐振点,调整H槽的位置和大小,使两个谐振点靠近耦合,从而拓展了天线带宽。通过改变贴片底部矩形槽深度和微带线长度调整天线的输入阻抗。使用软件HFSS14.0进行仿真分析。结果表明,该天线具有很好的宽频特性(766～989 MHz,回波损耗S11<10 dB),在超高频段(840～960 MHz)内具有良好的阻抗匹配特性。