关键词： 甲型胎兒蛋白   適合體   競爭型分析   C-反應蛋白   系統性配分子指數增益演繹程序   微機電系統   微流體  

摘要： 系统性配分子指数增益演绎程序(systematic evolution of ligands by exponential enrichment, SELEX)是一种体外筛选技术，透过该技术能在任意序列核酸分子库中，经由反覆结合、分离和进行聚合酶连锁反应(Polymerase chain reaction, PCR)放大的方式，筛选出一段与标的分子具高特异性和高亲和力之单股去氧核糖核酸(single stranded deoxyribonucleic acid, ssDNA)或核糖核酸(ribonucleic acid, RNA)片段，称之为适合体(aptamer)。此类适合体利用其本身特殊三维结构，可应用於多种用途上，包括感测及诊断分析，甚至可作为新药物设计等。然而，反覆结合、分离和放大的程序，费时费力，且需使用到数种大型仪器，更容易因人为操作产生误差和污染。近年，随着微机电系统(micro-electro-mechanical-system, MEMS)制程和微流体(microfluidic)技术之成熟，藉由微机电各种创新之制程技术，可将数种大型生化分析仪器缩小并整合至一微小的微流体晶片中，以减少生物试剂耗量及成本，且具有高检测效能、可抛弃式、可携带性等优点，因此在生物医学中扮演了十分重要的角色。 本研究利用微机电制程和微流体技术之整合，提出两个自动化SELEX晶片系统。此微型化晶片系统主要由两大模组组成，分别为用於流体传输以及混合之微流体操控模组和一个用於产生温度场以进行聚合酶连锁反应之微型温度控制模组。首先，利用和蛋白质具有高专一性键结之微型磁珠(magnetic microbeads)修饰上待测蛋白质，接着利用微流体操控模组，将磁珠和任意序列单股去氧核糖核酸均匀混合(incubation)，藉由流体造成之扰流，与标的蛋白质具有亲合力之单股去氧核糖核酸能固定在磁珠表面，接着利用外加磁场将磁珠在样品中进行分离及浓缩，藉由此步骤，检体将被净化且集中，最後再透过晶片上高升降温速率之微型温度控制模组，控制反应槽内温度高低循环进行聚合酶连锁反应，将磁珠上的单股去氧核糖核酸复制放大，如此便完成一次SELEX程序。利用此晶片系统，经由反覆的SELEX程序(5~6次)，可以快速在任意序列核酸分子库中筛选出与C-反应蛋白(C-reactive protein, CRP)和甲型胎儿蛋白(alpha-fetoprotein, AFP)具高专一性和亲合力之适合体，相较於传统筛选方法，可以节省一半以上的检测时间和试剂消耗。 即使经由SELEX程序筛选，仍只有部份的核酸最终被确认和标的分子具有足够的亲和力及专一性，因此，SELEX程序筛选过後的核酸还需利用竞争型测试(competitive assay)做进一步的确认，以节省之後定序、合成及亲和力量测等费用。然而，传统竞争试测除了要需要花费许多时间与人力外，繁覆的清洗步骤经常会有与待测物不具亲和力之核酸残留在试管之中造成污染，不利最後的判断；针对於这个问题，本研究提出竞争测试晶片，利用自动化的清洗装置和流线型的管道设计避免残留问题，达到精确筛选与标的分子具高亲和力及高专一性的适合体。根据竞争试测实验结果，C-反应蛋白和甲型胎儿蛋白适合体利用表面电浆共振(surface plasmon resonance, SPR)所测得之解离速率常数(dissociation constant)分别为3.51 nM 和 2.37 nM，与传统抗体相较，适合体比抗体具有更高的亲合力。 最後将所挑选出的C-反应蛋白和甲型胎儿蛋白之适合体实际应用於临床检测，由实验结果可知，C-反应蛋白和甲型胎儿蛋白之适合体检测极限约在0.0125 mg/L 和12.5 ng/mL，而C-反应蛋白在浓度为0.0125 mg/L到10 mg/L之间时，线性度0.9694 (R2 = 0.9694)，甲型胎儿蛋白在浓度为12.5 ng/mL到800 ng/mL之间时，线性度0.9747 (R2 = 0.9747)，皆符合临床检测上的应用，相信於不久的将来，本晶片系统所提供之自动化快速筛选平台，将对於利用适合体相关之分子生物研究有极大助益。

关键词： 流体模拟   纳维-斯托克斯方程   数值耗散   泊松方程   适应性细节维护   环境介质耦合  

摘要： 翻涌的流水，缭绕的烟雾，摇曳的烛火，这些都是人们平时眼熟能详的流体现象。但是流体的运动机理较为复杂，若要在计算机上模拟流体的运动并呈现其精美的视觉效果，最有效的手段就是追溯流体的物理本源，去求解控制流动系统的物理模型——纳维-斯托克斯方程。然而，单纯的求解控制方程并不能得到令人满意的结果，因为任何流体都不能隔离对待，它会与各种环境介质彼此影响，所以正确的求解需要在控制方程的基础上设计满足要求的算法模型。此外，精良的视觉效果要求精度较高的解，这些目标要依靠有效的细节策略来辅助达成。\n 在基于物理的流体模拟这个研究方向上，本文对几个相关问题进行了深入的研究与探讨，给出了有效的解决方案，旨在对几种流体与环境介质的耦合现象进行数学建模，并以此为依据设计高效可行的数值方法来解算流场以得到稳定、收敛且保持精度的结果，同时结合精良的细节策略来为流体的渲染过程提供细致、可信赖的数据。\n 本文的研究工作是基于欧拉流体框架的，在此之上提出了几种算法来改进模拟的效率与效果。本文的主要贡献有几下几个方面:\n 在求解对流方程时，为了增强无粘流关键区域的细节并保持全局的求解效率，本文设计了一种适应性锐化流场的FLIP/SLA混合模型。该算法模型的核心思想是在细节密集的流域内以FLIP方式来抑制数值耗散，同时在其他区域以半拉格朗日的方式进行高效率的对流。在算法的具体实现中，本文制定了精致的区域速度场融合机制及并提出了一种新的插值模板OB-box，达到了在不同对流方式的区域间以尖锐的方式交换信息的目的，在降低关键区域数值耗散的同时保证了全局的计算效率。\n 在求解流体的压力方程时，本文通过设计等价泛函模型的方法来隐式处理各种边界条件，解决了两大类问题。第一，针对无粘流Dirichlet边界条件与Neumann边界条件的处理，本文先利用两个等价模型有效修正了固体边界处的体素化错误和自由边界处的压力跳变。接着，为了正确模拟液体与气体之间的两相耦合作用，本文将等价模型与幽灵流体方法相结合，通过求解变系数的泊松方程来解算液体和其自由表面外部的一定带宽的气体流场，实现了对自由界面拓扑特征有重要影响的张力效果。第二，为了模拟粘性流体丰富的形变过程，本文通过一种等价的能量模型将耗散过程与投影过程耦合入一个线性系统中，使粘性项以全隐式的离散形式解算，同时使最终的速度场既保持无散性，又满足了对粘性形变至关重要的零应力条件，从而避免了显式近似该边界应力条件而导致的精度损失。该算法可以模拟蜷曲、翻滚、盘绕等粘性形变，并有效地支持可变粘性。\n 为了进一步提高压力方程求解的精度，本文提出一种将Neumann边界条件嵌入到泊松系统的投影算法。该方法基于有限体积法和守恒律的理论基础，在不改变之前算法框架的前提上，通过给散度算子的简单加权实现了近二阶精度的压力求解。该方法可以充分体现子网格信息，使流体可以在小于网格单元的狭窄路径中正确流动。接着，基于这种改进的算法本文实现了有效的二路流-固耦合的模拟，即通过使用修改梯度算子矩阵的方法保持流体和刚体系统的动量守恒。接着，本文将该投影算法扩展到了非结构化网格上，在针对八叉树网格时，通过改进压力梯度的离散方式实现了二阶精度的压力求解，并给出了基于八叉树的更简单高效的二路流-固耦合算法。在针对泰森多边形网格时，本文基于自由界面的拓扑特征来分布压力采样，以精确解析液体表面的稀薄细节。此外，在自由界面追踪与重构的问题上，本文提出了一种半隐式算法。该算法根据界面的显式描述来动态生成八叉树网格并进行精确的几何计算;而在更新界面时使用隐式描述，通过结合半拉格朗日对流与辅助粒子的方式求解LevelSet方程来完成这一过程，从而避免了显式界面面临的复杂拓扑问题。\n 针对每种算法，本文都给出了实验结果来证明算法的特性和优势，并根据模拟的效果和运行效率对算法的有效性、稳定性、收敛精度等方面作出了细致的分析，同时也指出了算法的局限性和下一步的改进策略。

关键词： 装甲车   数值模拟   风洞   温度场   计算流体力学  

摘要： 为更加准确地描述装甲车乘员室在不同条件下的热环境,采用两方程湍流模型,将装甲车置于数字风洞模型内,模拟求解不同条件下装甲车内的三维对流换热和空气流动状况,该方法可为装甲车乘员室热环境设计研究提供参考。

关键词： Solid state reaction method   X-ray diffraction   Scanning electron microscopy   Microstructure   SEM   Magnetoresistance   MR   LCO   LCCO  

摘要： Polycrystalline samples with the general formula La1.8Ca0.20Cu1-yMnyO4, y= 0.0, 0.10, 0.15, 0.20 have been synthesized and their structural and magnetotransport properties have been studied. Polycrystalline samples were prepared by usual solid state reaction method to keep the cation in desired valence states. Powder X-ray diffraction shows these samples are single phase. The anomalous change in the lattice parameters in La1.8Ca0.20Cu1-yMnyO4 have been reported in this paper, which imply the substitution of Cu by Mn influences the microstructure of above system. Scanning Electron Microscopy was done to study the surface morphology. Positive magnetoresistance is observed for La1.8Ca0.20Cu0.85Mn0.15O4.

关键词： Immunoassay   Microfluidic devices  

摘要： Immunoassay, as a technique that utilizes antibody-antigen interactions for the detection of relevant analytes, plays an important role in our daily life. It can be used for the quantification of proteins and small molecules in a number of different fields, such as medical diagnosis, food safety and environmental monitoring. The analysis of antibodies directed against specific epitopes with high specificity and sensitivity in human serum is becoming an increasingly critical task in medical and life sciences as the process provides detection of a serologic biomarker which enables early diagnosis in many diseases: for example, infectious diseases such as HIV and hepatitis B, autoimmune diseases such as systemic lupus erythematosus (SLE), as well as allergies and cancers. Recently, there is an urgent global need for point-of-care immunoassays which can be operated by end users since early stage antibody detection plays a crucial role in disease diagnosis and treatment. In this thesis work, we developed a new on-chip immunoassay platform, which combines the yeast surface display (YSD) technique and a microfluidic system. By directly counting genetically-engineered yeast cells bound with target analytes, the immunoassay was realized on a microchip tailored for point-of-care applications. Taking advantage of YSD, antigenic reporters are easily to be obtained by simply yeast culture, and the tedious steps of antigen purification and wet-chemistry processes to immobilize probe antigen can be eliminated. At the same time, with individual cells readily counted by routine microscopy, fewer numbers of cells can be detected than fluorescence or chromophore-based methods. Thus, this method has the inherent characteristic to be highly sensitive. Furthermore, controlled laminar flow can be applied to preferentially remove nonspecifically bound cells, improving the selectivity of the assay. We have built a prototypical microfluidic immunoassay device incorporating functionalized pla

关键词： batch dissolution   dissolution hydrodynamics   dissolution kinetics   dissolution mechanism   gypsum   salt dissolution   silica gel dissolution   shrinking object model   sucrose  

摘要： This paper reviews progress made over the last decade with the shrinking object approach to the kinetics of batch dissolution. It demonstrates how the O'Connor-Greenberg equation leads to three dissolutions: those that remain well undersaturated, those that saturate with a great excess of solid left-over, and those in the middle ground where saturation is approached or attained, but where much of the solid originally added dissolves. The equations that describe these conditions are discussed, alongside sample results that validate their use with test substances, for example, salts, sucrose, silica gel, and gypsum. The equations are then shown to be consistent with the hydrodynamic approach to dissolution. Finally, further work with middle-ground dissolutions of gypsum lead to a mechanism for the back-reaction, which involves the CaSO(4)(0) ion-pair. After comparison with existing studies of calcium carbonate dissolution, it is argued that this is a universal mechanism for salt dissolutions. The work improves batch dissolution as a technique to the point where it can be used synergistically with chemo-stat and rotating disc approaches. Suggestions are made for greater standardization in dissolution conditions, especially in environmental work where the data collected has to have global consistency.

关键词： 声表面波   叉指换能器   模拟   混合   微流体系统  

摘要： 报道了在微流系统中使用基于叉指聚焦换能器的声表面波的一种有效方法。利用lift-off和软光刻技术在铌酸锂(LiN-bO3)压电单晶片基底上制作器件。使用有限元分析软件COMSOL Multiphysics分别模拟聚焦叉指电极和平行叉指电极两种声表面波的形成和分布。通过与相同条件下的平行叉指电极比较,说明聚焦叉指电极可以显著增强声表面波的能量。实验结果说明聚焦叉指电极可以在几秒内快速的混合PS(聚苯-乙烯)球。这种器件为生物应用提供了一种有用的微流芯片体系。

关键词： 流场非均匀环境   搅拌系统优化   Scale-down   计算流体力学  

摘要： 现代生物技术应用需要大量低成本、高质量的产品。而产品的获得必须以实验室规模的生物过程准确放大到工业级规模为前提。但准确放大往往由于放大效应而难以实现,其中一个主要的表现就是反应器内环境的非均匀分布。因此本文的主要研究方向就是基于反应器内非均匀环境的流体动力学研究。为了消除反应器内的非均匀环境,本文采取了两种研究方式。 在200L冷模反应器中,通过将计算流体力学（Computational Fluid Dynamics, CFD）模拟与实际测定相结合,优化得到了八种能够消除反应器内环境梯度,功率消耗较低、气液分散特性较好的气液两相搅拌系统。 本文还采用了Scale-down方法,通过构建Scale-down反应器来模拟工业级反应器内的非均匀环境。实验中通过测定Scale-down系统中的混合时间及停留时间分布等流体动力学参数,对系统的流体动力学特性有了初步了解。混合实验结果表明,混合时间受循环流量和PFR形式的影响较大。增大循环流量、PFR部分体积或者采用较小的管径均有利于保持PFR中平推流特性。在数据处理中,通过引入虚拟体积（Vvrit）本文对所得混合时间数据进行拟合,对混合时间特性进行了深入的分析。停留时间分布在验证了系统内存在死区或者返混情况的同时,表明PFR内的流体动力学特性受循环流量和管径的影响较大。但由于PFR体积与系统体积相比较小,所以在停留时间分布测定中表现出PFR部分差异对系统流体动力学特性影响较小的特点。在实验测定的基础上,本文对Scale-down内的流场及流体动力参数进行了CFD模拟验证。模拟结果表明实验中所得数据及结论真实有效,为后期的发酵试验提供了坚实的理论基础。

摘要： Digital microfluidic devices provide a new technology platform for controlled motion of small volumes of fluid. These systems can provide high speed mi- crodroplet transport on integrated electrode arrays. The generic nature of these electrode architectures offers versatility, scalability, and reconfigurabil- ity that is crucial for biomedical, chemical, and sensing applications. The structural layout of digital microfluidic devices and the employed elec- trical activation schemes must be considered together in the design and op- eration of successful fluid actuation. Microfluidic models provide an effec- tive tool for predicting this device performance and optimizing parameters to achieve high efficiency. Numerical simulation of the electrodynamics of microdroplet motion in digital microfluidic systems will provide better un- derstanding of the effects of electrode shape on actuation forces, actuation voltage/frequency and liquid properties (e. g., conductivity, permittivity, and surface tension) on microdroplet actuation. However, the development of such models is far from trivial as many complex physicochemical phenomena become involved in the transport. In this thesis, a novel numerical multiphysic approach is used to model the microdroplet motion in digital microfluidic systems. The actuation force in the system of the interest is provided by applying voltage to the underlying electrodes. The main focus of this study is on the conductive liquids, however the electromechanical approach used in this research cab be readily extended to dielectric liquids. The proposed model employs an electrohydrodynamic approach for estimating the driving, wall and filler forces. Additionally, the effects of the evaporation are considered from two aspects: it is shown that an additional force is needed to balance the dynamic equation of the mi- crodroplet motion, and the microdroplet interface is deformed due to the change in the microdroplet radius. Finally, the effects of the b

摘要： Calcific aortic valve disease is highly prevalent, especially in the elderly [1]. Every year, aortic valve disorders are associated with over 40,000 deaths [2] and 95,000 surgeries are performed on the aortic valve in the US. Majority of aortic calcification cases are termed idiopathic, indicating our lack of knowledge on the exact mechanism causing the disease. Our current knowledge on how to prevent or cure the disease is also limited. The current treatment for the disease is the replacement of the valve with prosthetic valves, which has limited durability, and is associated with many complications. Thus far, ex vivo investigations have provided evidence that the aortic valve's biological response is very sensitive to mechanical forces, including fluid shear stresses [3-7]. Shear stresses were shown to be anti-inflammatory and oxidative as opposed to static culture [4], and adverse patterns of shear stresses can cause inflammatory responses to the valve [5], which is known to be a precursor to valve sclerosis and calcification. Further, it has been suggested that the localization of calcification nodules on the aortic surface of the valve leaflet is due to "disturbed fluid shear stress" on the aortic surface, and "undisturbed fluid shear stress" on the ventricular surface [8, 9]. All these have led to the hypothesis that adverse fluid shear stress environment play a role in leading to valve calcification. The case of the congenital bicuspid aortic valve provides a good test bed for this hypothesis. The bicuspid valve is a geometric deformation in the valve where two of the three leaflets are fused together at birth and occurs in 1-2% of the population [10, 11]. Bicuspid valve patients suffer from drastically increased risk of aortic valve calcification [12, 13]. Since the drastic change in the bicuspid valve geometry may have drastically changed its mechanical environment, the bicuspid valve is a good case for investigating the hypothesis that mechanical forces in