Characterization and separation of Cryptosporidium and Giardia cells using on-chip dielectrophoresis

Dielectrophoresis (DEP) has been shown to have significant potential for the characterization of cells and could become an efficient tool for rapid identification and assessment of microorganisms. The present work is focused on the trapping, characterization, and separation of two species of Cryptosporidium (C. parvum and C. muris) and Giardia lambia (G. lambia) using a microfluidic experimental setup. Cryptosporidium oocysts, which are 2-4 μm in size and nearly spherical in shape, are used for the preliminary stage of prototype development and testing. G. lambia cysts are 8–12 μm in size. In order to facilitate effective trapping, simulations were performed to study the effects of buffer conductivity and applied voltage on the flow and cell transport inside the DEP chip. Microscopic experiments were performed using the fabricated device and the real part of Clausius—Mossotti factor of the cells was estimated from critical voltages for particle trapping at the electrodes under steady fluid flow. The dielectric properties of the cell compartments (cytoplasm and membrane) were calculated based on a single shell model of the cells. The separation of C. muris and G. lambia is achieved successfully at a frequency of 10 MHz and a voltage of 3 Vpp (peak to peak voltage).     

Integration of programmable microfluidics and on-chip fluorescence detection for biosensing applications

We describe the integration of an actively controlled programmable microfluidic sample processor with on-chip optical fluorescence detection to create a single, hybrid sensor system. An array of lifting gate microvalves (automaton) is fabricated with soft lithography, which is reconfigurably joined to a liquid-core, anti-resonant reflecting optical waveguide (ARROW) silicon chip fabricated with conventional microfabrication. In the automaton, various sample handling steps such as mixing, transporting, splitting, isolating, and storing are achieved rapidly and precisely to detect viral nucleic acid targets, while the optofluidic chip provides single particle detection sensitivity using integrated optics. Specifically, an assay for detection of viral nucleic acid targets is implemented. Labeled target nucleic acids are first captured and isolated on magnetic microbeads in the automaton, followed by optical detection of single beads on the ARROW chip. The combination of automated microfluidic sample preparation and highly sensitive optical detection opens possibilities for portable instruments for point-of-use analysis of minute, low concentration biological samples.     

Ripple structure-generated hybrid electrokinetics for on-chip mixing and separating of functionalized beads

We present an electrokinetics-based microfluidic platform that is capable of on-chip manipulating, mixing, and separating microparticles through adjusting the interrelated magnitudes of dielectrophoresis and AC electroosmosis. Hybrid electrokinetic phenomenon is generated from an electric field-induced micro-ripple structure made of ultraviolet-curable glue. Size-dependent particle separation and selective removal over the ripple structure is demonstrated successfully. Varying the waveform from sine-wave to square-wave allows generating a fluid convection at specific positions to mix the antibody-functionalized beads and antigen. Potential application in the bead-based immunoassay was also demonstrated for immuno-reaction and subsequently separating the bead-bead aggregate and non-binding beads on-chip.     

Study on the use of dielectrophoresis and electrothermal forces to produce on-chip micromixers and microconcentrators

The present study uses the dielectrophoresis (DEP) and electrothermal (ET) forces to develop on-chip micromixers and microconcentrators. A microchannel with rectangular array of microelectrodes, patterned either on its bottom surface only or on both the top and the bottom surfaces, is considered for the analysis. A mathematical model to compute electrical field, temperature field, the fluid velocity, and the concentration distributions is developed. Both analytical and numerical solutions of standing wave DEP (SWDEP), traveling wave DEP (TWDEP), standing wave ET (SWET), and traveling wave ET (TWET) forces along the length and the height of the channel are compared. The effects of electrode size and their placement in the microsystem on micromixing and microconcentrating performance are studied and compared to velocity and concentration profiles. SWDEP forces can be used to collect the particles at different locations in the microchannel. Under positive and negative DEP effect, the particles are collected at electrode edges and away from the electrodes, respectively, irrespective of the position, size, and number of electrodes. The location of the concentration region can be shifted by changing the electrode position. SWET and TWET forces are used for mixing and producing concentration regions by circulating the fluid at a given location. The effect of forces can be changed with the applied voltage. The TWDEP method is the better method for mixing along the length of the channels among the four options explored in the present work. If two layers of particle suspension are placed side by side in the channel, triangular electrode configuration can be used to mix the suspensions. Triangular and rectangular electrode configurations can efficiently mix two layers of particle suspension placed side-by-side and one-atop-the-other, respectively. Hence, SWDEP forces can be successfully used to create microconcentrators, whereas TWDEP, SWET, and TWET can be used to produce efficient micromixers in a microfluidic chip.     

社会保障基金收缴中存在的问题及对策

随着市场经济的不断深化和发展，机关事业单位职工社会保障基金制度改革逐步深化，社会保障基金的统筹在社会经济生活中，起着越来越重的作用。分析了社会保障基金收缴中存在的总是，并提出了防治对策。     

绿色制造-物流协同演化背景下的企业知识链创新

《中国制造2025》为中国走绿色制造可持续发展道路提供了政策导向。基于绿色制造-物流协同演化背景，本文认为企业知识链创新必须在实体产业与知识链的融合过程中进行研究，才能保障企业知识链获得创新生命力，避免知识链路径依赖的制约；同时也可以进一步发展和完善企业知识链的理论研究。本文在研究分析知识链内涵与局限性基础上，论述了绿色制造-物流协同演化下企业知识链创新的必要性；其次，从信息结构入手破解知识链路径依赖的可行性；最后基于绿色制造-物流协同背景构建知识链反馈回路模型，并提出了相应的创新对策。     

加快中国绿色农业和绿色食品技术标准体系建设

文章对绿色革命到绿色农业和绿色食品的发展进行了系统深入的论述,认为绿色农业是第二次绿色革命的主体形式。中国绿色农业和绿色食品是对发达国家有机农业和有机食品的进一步发展,中国的绿色食品逐渐在国内外占领更大的市场,对世界粮食安全做出了重要贡献。但我国还需学习和借鉴国内外有机农业和有机食品的生产标准和管理体系,逐渐和国外食品安全法规接轨。针对我国食品安全法落实中遇到的困难和问题,建议加快中国绿色农业和绿色食品生产技术标准体系建设,其应成为我国"十二五"规划的一项重要内容。     

日本绿色技术创新现状及发展趋势

在绿色潮流席卷全球之际，各国都展开了绿色技术创新。发达国家的成功经验可给我国以借鉴作用。通过大量实例，阐述了日本绿色技术创新的研究组织、研究领域、创新模式及未来趋势。     

帕累托定律运用于图书馆藏书建设

帕累托定律在经济世界和人类日常生活中的影响已经世人皆知了,但它对图书馆藏书建设的作用很少有人探讨。本文应用帕累托定律的核心思想,论述了帕累托定律在高校图书馆藏书建设中的指导作用,以及如何在藏书建设中以较少的投入获得较大的效益。     

变重力场中理想气体的“P—V”循环及熵变

在恒定的重力场中密闭于刚性容器中的理想气体在垂直方向上的压缩和膨胀构成“压力一体积”（P-V）循环,利用此循环可实现“热一功”转化,但气体必须工作在两个不同温度的热源之间。由于重力场中刚性容器中的气体的压力分布随重力的变化而变化,因此可通过增、减重力加速度使密闭容器中气体压力改变构成P—V循环,通过此循环也可实现“热-功”转化,此类“热-功”转化的循环有别于传统的卡诺循环。变重力场中理想气体的P—v循环导致的“热-功”转化不需要两个不同温度的热源。本文的计算表明在可逆过程中此P—V循环的熵变量不符合热力学第二定律,深刻地揭示了热力学第二定律的局限性。     

绿色供应链背景下的互补产品捆绑与绿色创新决策

以包括两个互补产品供应商和一个零售商的二级供应链为研究对象,基于互补产品绿色创新溢出效应和捆绑效应,考虑互补产品供应商绿色创新与否、零售商的绿色营销和销售策略,构建多阶段供应链定价与绿色度决策模型。通过模型求解和数值实验,研究发现：当互补产品的捆绑效应较大时,互补产品供应商的最优策略是进行绿色制造,而零售商的绿色营销和捆绑销售策略与互补产品供应商的最优策略和捆绑效应大小有关;供应链中其他成员进行绿色制造和投入会促进产品供应商提高绿色制造水平,且零售商的捆绑销售也会促使其提高产品绿色度;另外,互补产品的绿色创新溢出效应也会影响供应链成员及整体的利润。     

绿色贸易壁垒的表现形式及跨越

中国加入WTO后，一些发达国家通过提高绿色贸易壁垒的方式，制约我国产品的出口。为了探讨有效跨越国外绿色贸易壁垒形成的出口障碍，在对绿色贸易壁垒及其发展作出简要阐述的基础上，深入分析了绿色贸易壁垒的主要特点和表现形式，并提出了突破绿色贸易壁垒的若干途径。     

一种基于射频IC卡的检票系统的研究与实现

本文主要介绍了一种基于射频IC卡的检票系统的设计及实现的关键技术,利用可视化编程语言VB与SOL Server 数据库等相关技术,实现计算机与读卡器之间的通信.最终完成票夯数据的处理.     

Regional diversification and green employment in US metropolitan areas

Adapting or supplanting production and distribution systems to accommodate new criteria of environmental sustainability entails the search for and the recombination of know-how from a variety of domains. How this process plays out in different areas depends crucially on the specific composition of local economic activities. This paper contributes this debate by analysing whether and to what extent regional industrial and occupational diversification affects the change in green employment across 363 Metropolitan Statistical Areas (MSAs) in the United States between 2006 and 2014. Our findings suggest that industrial unrelated variety within MSAs is a positive and significant predictor of green employment growth whereas related variety has very little impact. Conversely, both related and unrelated diversification across occupations are positively associated with green employment growth. The analysis also uncovers heterogeneity across existing, new and evolving green jobs.     

Electrowetting on dielectric driven droplet resonance and mixing enhancement in parallel-plate configuration

This study experimentally verifies that the mixing process in a droplet can be enhanced by driving the droplet at resonant frequencies and at alternating driving frequencies using a parallel-plate electrowetting on dielectric device. The mixing time, which is defined as the time required for reaching the well-mixed state, in a resonant droplet is found to be significantly shorter than that in a non-resonant droplet. Besides, it is also found that a higher driving potential leads to a better mixing effect, especially at resonant frequencies. Furthermore, when a droplet is driven by alternating two driving frequencies, especially two resonant frequencies, the mixing efficiency is found to be significantly enhanced for a specific alternating duration of these two frequencies.     

串行通信标准在工业现场数据采集中的应用

本文在分析RS-232C、RS-485、USB等串行通信接口特点的基础上,介绍了基于串行通信标准的典型的工业控制应用产品及其在工业现场数据采集中的应用方法.     

公路水土保持与绿化措施

公路的迅速发展对经济的发展起到了巨大地促进作用,由此所引起的水土流失却给环境带来严重的威胁。如何预防及杜绝水土流失是公路建设中需要解决的一项重要工作,对水土保持措施的研究有重要的意义。     

变重力场中理想气体的位能循环及热功转化

重力场中密闭于刚性容器中的气体密度随高度减小,且气体的气体密度分布及总位能随重力的变化而变化．从理论上来看,可通过增、减重力加速度使密闭容器中的气体位能实现循环,通过此循环还可实现“热——功”转化,此类“热——功”转化的循环有别于传统的卡诺循环。变重力场中理想气体的位能循环导致的“热——功”转化效率计算不能直接应用卡诺定理,笔者分析了在可逆过程中此类循环的效率及熵变计算方法。