摘要： The present PhD thesis is a contribution to the research field of induced-charge electro- osmotic (ICEO) flows, and to the field of applied topology optimization in microfluidic systems. The scientific efforts behind this contribution can be divided into four areas of research. These have been summarized below. Within the topic of ICEO, experimental studies of AC electro-osmotic pumping in microchannels generated above an array of asymmetric electrodes have been carried out. In the regime of low frequencies and low voltages a hitherto unobserved reversal of the flow direction has been detected. No existing electrokinetic models published in the liter- ature are able to account quantitatively for this observation. The impedance spectra of these pumps have additionally been thoroughly measured and investigated in terms of an equivalent circuit diagram. By fitting these spectra to a Bode plots, good agreement with our model was found using realistic parameter values. Furthermore, a conventional full nonlinear model of DC-driven ICEO flows has been implemented and solved numerically for fully resolved electric double layers. The im- plemented model has subsequently been validated against analytical flow results. The generated flow calculated by this model has been compared to the same flow calculated using a linear ICEO model, which is based on the assumption of an infinitely thin Debye layer with an effective slip-velocity condition on the flow outside the electrical double layer. It turns out that the slip-velocity model overestimates the flow compared to the full model. When the Debye length increases relative to the size of the flow-generating electrode, the discrepancy between the models increases significantly. Even when the Debye length is one percent of the electrode size, deviations of at least 10% are to be expected. This deviation could provide a partial explanation of the quantitative discrepancy between observed and calculated ICEO velocities reported in th

关键词： 同位素   水文地球化学   热储流体   热储温度   西安凹陷  

摘要： 本文以西安凹陷热储流体为研究对象,在大量收集研究资料及野外调查的基础上,应用环境同位素与水文地球化学相结合的方法,对该研究区热储流体环境同位素水文地球化学演化特征进行了分析,在此基础上,就热储系统的开放度,热储温度,热储流体的补给来源等与热储环境相关的水文地质和地热地质问题提供了环境同位素水文地球化学证据。 热储流体中环境同位素的研究成果表明:西安凹陷中西安城区及咸阳城区地热流体中δ18O同位素发生了明显漂移,提示其漂移前补给源为非现代大气降水。δ18O同位素交换的影响因素主要包括水温、水岩反应程度、围岩岩性、滞留时间及热储埋深。咸阳地区地热水比西安地区漂移更加明显,说明咸阳热储流体的赋存环境更加封闭,水岩作用更加强烈。咸阳热水δD值与西安热水δD显示出明显差异,表明两者补给环境的差异,分属不同的热水补给系统。 热储流体中水文地球化学的研究成果表明:不同热储层的热储流体,由于地层岩性、补给、径流、排泄条件的差异,其水化学成分有明显的不同。同一热储层的热储流体,在其由补给区向排泄区径流的过程中,水化学成分也发生了显著的变化。研究区热储流体水文地球化学的分布及演化反映了热储流体的补给,运移及循环的过程。 西安和咸阳城区热储流体同属于封存型地热流体,两者热储流体赋存的条件较为相似,但是咸阳地热流体的赋存环境比西安更加封闭,可更新程度更差,两者有着不同的补给来源,西安地热流体主要为由秦岭全新世前大气降水补给,而咸阳地热流体则主要由北山裸露灰岩大气降水补给。 Na-K-Mg三角图可以反映出水化学平衡状况和平衡温度。水样点位于完全平衡曲线上则说明地热水已经达到或近于平衡,其水化学成分适合估算地下水储层温度。若水样点位于部分平衡区域内,则指示水岩平衡程度不高或有局部冷水混入,其计算的热储温度仅作参考。此外,本文运用Na-K-Mg三角图法及地热温标法对西安凹陷在化学平衡条件下的热储温度进行了对比分析计算,研究区最高热储温度为118℃。

摘要： The overall goal of this work was to develop and utilize microfluidic models for investigating bacterial chemotaxis and biofilm formation - phenotypes that play key roles in bacterial infections. Classical methods for investigating chemotaxis and biofilm formation have many limitations and drawbacks. These include being unsuitable for investigating the effect of chemorepellents, non-quantitative readouts, and not accounting for interaction between hydrodynamics and biofilm formation. The novel microfluidic model systems for chemotaxis and biofilm formation developed in this study addresses these drawbacks. Chemotaxis model system development was done in three stages. We first developed two static chemotaxis model systems – the two fluorophore chemotaxis agarose plug assay and the μPlug assay - for rapidly determining the extent of chemotaxis in a qualitative manner. A key feature of these model systems was the incorporation of dead cells and differential labeling with green and red fluorescent proteins for partitioning the effects of movement due to fluid flow from chemotaxis. The static systems were used to rapidly screen a wide range of conditions for use in the flow- based μFlow chemotaxis model system. The effect of four major variables - cell preparation method, gradient strength, flow rate in the device, and imaging position - that influence the chemotactic response in the μFlow was characterized using the repellent taxis from Ni2+ gradients as the model chemoeffector. Using the μFlow chemotaxis device, we investigated the chemotaxis of Escherichia coli RP437 to different signals that are present in the human gastrointestinal tract and are likely to be mediators of infection through their effect on chemotaxis. Our data show that the bacterial signal indole is a repellent, while the signals autoinducer-2 (AI-2) and isatin are attractants for E. coli RP437. However, cells exposed to a competing gradient of indole and either AI-2 or isatin, attracts E. coli. The

关键词： 微流体系统   微流量传感器   Lamb波传感器   柔性平板波   温度补偿  

摘要： 微流体系统是微机电系统(MEMS)的一个重要分支，在生物、医学、化学等领域有着巨大的应用前景。微流量传感器作为微流体系统定量输出的核心元件，具有热惯性小、响应速度快、低功耗、低成本等优点，在微流体系统中有广泛的应用。随着微流体系统的发展，迫切需求微量流体的精确测量。本文旨在研制一种高灵敏度、大动态范围的微流量传感器。\n 本文根据微流量传感器的国内外发展现状，利用Lamb波的高灵敏度、大动态范围的特性，提出了一种新型的Lamb波压差式微流量测试方法；介绍了微流量传感器的结构、工作原理以及温度补偿方式；设计、制作了Lamb波信号检测谐振电路，以频率输出的方式实时测量了Lamb波器件在空气中的频率稳定性;设计了微通道的结构，并采用MEMS技术进行制作，搭建了微流量传感器的实验系统；在室温20℃下以去离子水为工质，完成了Lamb波传感器的压力标定，并在长20mm、宽1mm、高50μm的微通道中进行流量测试实验。\n 实验结果表明：在流量测试范围内，微通道两端的频率差与流量基本呈线性变化，其线性相关系数为0.9999；在微流量传感器没进行优化的情况下，最小检测量为0.627μL/s。说明本文研究的Lamb波压差式微流量传感器具有较高的灵敏度，适于微流体系统的应用。

关键词： 超临界流体技术   研究方向   环境保护  

摘要： 20世纪70年代末兴起的超临界流体技术,近年来发展迅速,被广泛应用于化工、食品、生物等领域。将超临界流体技术用于环境保护则是一个新兴的研究方向。文章简明阐述了超临界流体技术的基本原理及其在环境保护方面的应用。

关键词： 生物MEMS   微流体系统   反应离子刻蚀   ParyleneC  

摘要： 首先简要介绍了聚合物Parylene,并以Parylene C薄膜为原料,进行反应离子刻蚀,着重研究了功率和工作气压对刻蚀速率的影响,并给出了优化的刻蚀工艺参数。结果表明,刻蚀速率随功率增加而增大,当功率为80 W时,刻蚀速率达到0.44μm/min,适当增大功率有利于各向异性刻蚀。刻蚀速率在一定范围内随气压增大而增大,工作压力为10.67 Pa时,刻蚀速率达到0.47μm/min;当气压超过10.67 Pa后,刻蚀速率基本保持不变。

关键词： 自然通风   置换通风   强制通风   水汽凝结  

摘要： 半封闭与全封闭空间的环境流体力学包括系统内的空气流动、温度和湿度分布以及污染物的凝积等问题,其中涉及控制空间的空气质量、通风设计以及预防水汽凝结等多个方面的研究.本文着重介绍国内外近年来相关的工作,研究如何从理论分析、实验研究以及数值模拟等方面入手,解决通风问题,以达到获得高通风效率、低能耗和提高空气舒适度的目的.研究的对象包括房间,建筑物,城市等半封闭空间,以及汽车、地铁、飞机、潜艇、载人航天飞行器等不同程度的全封闭空间.现有的理论研究已经从解释单点源纯浮力对流的基础模型发展到能够描述具有体积流量和动量流量的扩散流的湍流喷泉模型.然而,理论研究上的进步还不足以使它能够处理实际问题中多样的通风情况和复杂的空间结构,工程应用中还需更多依靠实验研究和数值模拟的结论.对载人航天飞行器中的环境流体问题的研究虽然刚刚起步,但其研究手段和经验可以从相对成熟的半封闭与全封闭空间的相关研究中获得借鉴.

关键词： 聚乙二醇   明胶   琼脂   水基磁流体  

摘要： 用共沉淀法在室温条件下制备纳米Fe3O4磁性粒子，选用聚乙二醇、明胶、琼脂等环境友好分散剂制备水基磁流体。最佳工艺条件为：（1）Fe^3＋／Fe^2＋（物质的量）之比在1．70～1．75；（2）沉淀剂25％NH3·H2O过量（20-30）％，在温度35℃，pH值10-11，搅拌速度3000r／main，反应时间为1h；（3）琼脂、明胶的最佳用量为（0．050～0．060）g／150mL；包覆的最佳温度为（55～60）℃，pH值为9～11；聚乙二醇作为第二次包裹时，最佳温度为55℃，搅拌速度3000r／min，反应时间是1h；并用透射电镜、分光光度计、古埃磁天平等进行了初步表征。在Fe3O4粒子中加入镝（n（Fe）：n（Dy^3＋）=14：1），明显提高了磁性。

关键词： RESS   Nozzle   Fluidization   Coating   High pressure   Paraffin wax   Solubility  

摘要： Fluidized bed combined with RESS Process in supercritical carbon dioxide (SC-CO2) is a promising technology for coating heat-sensitive materials of high added value. This work presents a study of the most influencing operation parameters (temperature. pressure and flow) of the two steps of the process (saturation and coating). As a model system,glass beads particles(d(p,s) = 176 mu m) were encapsulated with paraffin (T-m = 52-54 C). Two different ways of injecting the coating solution of paraffin in the SC-CO2 in the fluidized bed were tested, bottom and top spray. The operation variables were kept in the following ranges for the saturation step: pressure from 18 to 22 MPa and temperature from 35 to 55 C. In the coating process the pressure range from 8 to 10 MPa and temperature from 35 to 50 degrees C. Yields of the global process Lip to 70% were achieved. SEM-images of the achieved coatings show complete coating films with no agglomeration in the top Spray experiments. (c) 2008 Elsevier B.V. All rights reserved.

关键词： 微技术   世界   集成电路技术   微流体系统   微机电  

摘要： 20世纪80年代，在集成电路技术的基础上诞生了世界首套微机电和微流体系统。从那时起，微技术领域的发展可谓日新月异。如今，微技术已在环境条件极为复杂的油田领域得到广泛应用。