摘要： A complex nanofluidic device consisting of a slit embedded with an array of nanopit cavities is used to study the physics of confined DNA. By measur- ing the number of cavities occupied by a molecule in varying geometries, the entropic free energy of confinement and effective molecular width were mea- sured. By measuring the correlation time of contour fluctuations between two pits, the dependence of the dominant relaxation modes on the local free energy landscape was investigated. By measuring the fraction of a molecule occupying single pits of varying size, the effects of excluded volume interactions in cavi- ties were studied. The results were considered in light of a model for the free energy of confinement taking into account semi-flexibility, excluded volume, and entropic elasticity, components of which were developed to understand these experiments.

关键词： 微流体系统   平面回转玻璃微通道   玻璃软化弯曲成形   正交试验  

摘要： 微通道作为微流体系统功能与性能的决定性元器件之一，随着不同微通道网络结构应用于微流体系统领域，微通道网络成形工艺已成为微流体领域的重要研究方向。仿生学研究的逐渐深入，微通道网络形态已普遍存在于自然界中，经历了长期自然环境选择生成的自然微通道网络是现有微通道网络结构中的最优形式，采用高效的仿生微通道网络结构为微流体系统研究提供了新的研究方向。　　本文基于前期制作的玻璃基仿生微通道制备仪，通过工艺参数分析与优化制得了玻璃仿生微通道。综合考虑仿生微通道在通道截面形状规整性，结构复杂性，材料组织和性能一致性，优异流动性等因素要求下，选择预先制得的平直玻璃微通道作为基体材料，通过对玻璃仿生微通道制作工艺参数优化、玻璃微通道网络弯曲成形工艺探索和微通道网络成形过程分析，研制了平面回转玻璃微通道网络成形装置，并对成形工艺影响参数进行了试验研究。本文主要完成了以下研究：　　（1）利用玻璃基仿生微通道制备仪，通过工艺参数分析与优化，完成优异特征尺寸平直微通道的制作，为后续微通道网络成形提供基材。　　（2）在研究粘度、表面张力和弹性等影响玻璃成型特性因素基础上，分析了平面回转玻璃微通道网络成形工艺原理和工艺过程，提出了利用加热软化和弯曲成型的方法加工出平面回转玻璃微通道网络，并完成了平面回转玻璃微通道网络成形机的功能需求分析及总体方案设计。　　（3）完成平面回转玻璃微通道网络成形装置的方案与结构设计，通过分析计算进行主要元器件的选型，绘制成形装置设计图纸，经外协加工后，完成成形装置的装配和调试工作。　　（4）通过改变单一变量的方法，研究了各参数对平面回转玻璃微通道成形的影响。利用正交试验方法，进行了各成形参数对平面回转玻璃微通道成形过程影响的显著性研究，得到了各参数对成形影响显著性的先后顺序，为下一步优化工艺参数提供数据支持。

关键词： 环境物理学  

ISBN: (纸本)9787030447975

摘要： 本书系统地阐述了环境流体力学的基本概念、基本理论及最新研究成果，内容主要包括：水环境和大气环境的基本概念、分子扩散理论、紊流扩散理论、射流理论、羽流理论、浮射流理论、阵喷流理论、大气扩散、剪切流离散、水质模型、地下水污染模型、分层流理论、水体混合理论、生态流体动力环境等。为便于读者自学，文字力求写得通俗易懂，对一些数学处理给出了比较详细的推导过程。书末附有环境流体力学常用术语中英文对照表、人名中外文对照表以及详细的参考文献，以便读者深入研究时参考。

关键词： 镁   可吸收支架   降解/腐蚀   流体   生物反应器   表面改性  

摘要： 目前,医疗植入器械产业正处于从永久型植入物到可吸收再生型植入物的转型。这些可吸收金属材料主要有由镁和镁合金制成。虽然目前关于可吸收金属材料已经开展了大量的研究,但现有的美国材料与试验协会和国际标准化组织已公布的标准不能准确的评价体外降解行为进而预估体内降解行为。发展现行标准的一个关键步骤是在试验系统中明确和测试相关的微环境和参数。此外,针对于可吸收镁基血管支架的临床应用,需要完全理解镁基支架的生物降解机制,同时需要建立可控降解和提高生物相容性的可靠方法。本研究的主要目的是为了更好地认识在模拟血管微环境中流体动力学对镁降解的影响。我们自主开发了一系列血管的生物反应器来模拟体内/临床条件以揭示降解机制,例如体外多流速动态实验与计算机流体动力模拟相结合系统,原位瞬时电化学检测系统,以及模拟血管内皮化前后阶段的镁降解行为的体外猪主动脉生物反应器模型和体内鼠动脉模型评价系统。准确测定腐蚀类型,腐蚀速率和腐蚀产物对预测镁基血管支架的使用寿命起着关键的作用。实验表明流体动力学,流体流速和剪切力对可吸收镁基支架的降解/腐蚀行为起着关键的作用。流体剪切应力加速了质量和电子的转移过程,导致整个腐蚀过程加剧,包括局部腐蚀、均匀腐蚀、点蚀和侵蚀。流体剪切应力提高了平均的均匀腐蚀速率、局部腐蚀的覆盖率和腐蚀深度、以及增加了局部腐蚀区域内部腐蚀产物的去除率。这些结果与电化学测试的均匀腐蚀产物层阻抗、局部腐蚀阻抗以及极化阻抗呈现了一致的相关性。就镁合金血管支架而论,在流体剪切力为0.056 Pa条件下的腐蚀前后体积损失率是0 Pa条件下的两倍。流体运动方向对腐蚀行为有明显的影响,面对流向一侧的腐蚀产物层易从支架筋上剥落。为了认知镁在血管重塑内皮化前后阶段相关的降解行为,本文建立了一个猪主动脉生物反应器模型来研究流体对流和扩散引起的镁的生物降解行为。结果显示管腔表面流体的对流严重加剧了镁的腐蚀,因其增加了镁的质量转移、流体剪切应力、脉动舒张和收缩应力。同时,本文进一步建立了体内鼠动脉模型研究,研究镁的生物降解行为。结果显示无论是管壁还是管腔内的镁丝的降解速率都低于体外模型镁丝的降解速率。管壁内镁丝的降解略快于管腔内的镁丝,同时引起的钙化的富集。考虑到镁基支架的腐蚀和生物相容性的控制,本文设计将表面溶蚀型的聚三亚甲基碳酸酯(PTMC)涂覆在镁合金表面,也对它的动态降解行为、电化学腐蚀、生物相容性和组织相容性进行了研究。在动态降解实验中,PTMC涂层有效地保护了镁合金,减慢其腐蚀速率。经PTMC涂层改性的镁合金的自腐蚀电流密度分别低于参照样未改性镁合金三个数量级和聚己内酯(PCL)改性的镁合金一个数量级。体外静态和动态的血液实验表明相较于对照样附着在PTMC涂层表面的有极少量的血小板粘附和激活,更少的红细胞,更低的溶血率。PTMC改性的镁合金植入到小鼠皮下16个星期后,剩余的PTMC涂层厚度约为其原始厚度的55%,且其均匀平坦的表面证明了是表面侵蚀降解行为;与之形成对比的是,PCL涂层对照组表现出了非均匀的体降解行为。体内试验52周后,与对照组相比,PTMC涂层镁合金的体积减少量更小,腐蚀产物也更少。没有观察到过度的炎症反应,细胞坏死和氢气聚集。PTMC涂层从外部到内部(表面溶蚀行为)均匀的表面侵蚀和中性降解产物促成了其优良的防护性能。总而言之,PTMC作为表面溶蚀型材料是一种对镁基血管支架具有前途的候选涂层材料。本研究强调应充分考虑到流体诱导的降解行为而实现恰当地设计镁基血管支架。这篇论文所展示的数据旨在缩小体内和体外试验结果之间的差距,以及提供更可靠的信息以便更好地理解可吸收金属支架的降解行为。

关键词： 微流体系统   微通道网络   制作材料   成形工艺   仿生微通道  

摘要： 微通道作为微流体系统的重要组成部分,是提高微流动性能的关键因素。现有微通道制作材料包括硅、石英和玻璃等无机材料,以及PDMS、PMMA、PC和环氧树脂等有机材料,而加工工艺主要有湿/干法刻蚀、热压成型、微/纳光刻技术、激光微加工和模塑法等类型。根据不同应用领域中微通道的功能需求和空间布置情况,可将微通道网络分为线性、平面和立体三种类型,综述了不同类型微通道网络成形工艺的国内外研究现状,其中线性和平面微通道网络的制作与成形一般是同时完成的,工艺较成熟,而立体微通道网络需分步实现,难度较大。探讨了现有微通道网络成形工艺的不足和发展趋势。简要介绍了玻璃基仿生微通道及其网络成形工艺研究进展。

关键词： 纳米流体   稳定性   温度   粒径分布   沉降速率  

摘要： 采用"两步法"制备浓度为1.0%且不含分散剂的Al2O3-乙醇纳米流体,研究了中低温环境下温度变化对Al2O3-乙醇纳米流体稳定性的影响。采用紫外吸光度方法评价了纳米流体的稳定性;测试了悬浮颗粒的粒径分布并拟合出不同温度下粒径分布随时间的变化关系,计算了悬浮颗粒的沉降速率并拟合出不同温度下沉降速率随时间的变化关系;从势垒值变化的角度解释了温度影响纳米流体稳定性的原因。结果显示,Al2O3-乙醇纳米流体能在低温下保持较好的稳定性。

摘要： Coral bleaching and mortality have typically been characterised by the anomaly of sea surface temperature (SST). However, many stud- ies have established that corals in some areas emerged relatively un- scathed from anomalously high SST maxima that equal or exceed those associated with extensive bleaching. This thesis qualitatively and quantitatively explored the temperature deviations between coral surface temperature and ambient seawater temperature that likely de- termines the microscale physical processes involved in coral bleaching. It was deemed to be imperative to be able to gain a clear understand- ing of how the key physiological and environmental stressors – irradi- ance, water flow, and coral morphological features (colony shape, size, tissue thickness, and pigmentation) – drive the temperature microen- vironment of corals, which may subsequently improve the bleaching or recovery predictions, thereby leading to more effective reef man- agement. The work presented in this thesis applied Computational Fluid Dy- namics (CFD) technique coupled with hydrodynamic modelling and ray-tracing technique to predict coral surface warming due to the ef- fects of various primary and secondary stressors under both controlled laboratory-scale conditions and shallow reef-flat environments. A de- tailed overview of the mechanistic basis for understanding the role of radiative heat flux, water flow and circulation pattern, and coral morphological features in affecting the microscale temperature was de- scribed. Secondary stressors – such as cloud cover, water clarity, flow regimes, waves and wind-driven currents, permeability and porosity of both tissue layer and skeletal matrix, colony pigmentation, tissue thickness – were covered in the "ecosystem" models developed as part of this work. The model results were validated thoroughly against published laboratory and field observations. This thesis demonstrates that modelling microscale temperature could yield important insight

关键词： 电子商务   心流体验   消费体验  

摘要： 电子商务环境下心流体验研究是近年来消费者行为领域研究的热点。本文在对国外相关研究进行梳理的基础上,回顾了电子商务环境下消费者网络购物心流体验的实质及其前因后果,并评述了现有研究的局限,最后对未来研究进行了展望。

关键词： Microfluidic system   HTDS   Combinational chemotherapy   PC-3   TRAIL   Curcumin  

摘要： We have developed a fully automated high throughput drug screening (HTDS) system based on the microfluidic cell culture array to perform combinational chemotherapy. This system has 64 individually addressable cell culture chambers where the sequential combinatorial concentrations of two different drugs can be generated by two microfluidic diffusive mixers. Each diffusive mixer has two integrated micropumps connected to the media and the drug reservoirs respectively for generating the desired combination without the need for any extra equipment to perfuse the solution such as syringe pumps. The cell array is periodically exposed to the drug combination with the programmed LabVIEW system during a couple of days without extra handling after seeding the cells into the microfluidic device and also, this device does not require the continuous generation of solutions compared to the previous systems. Therefore, the total amount of drug being consumed per experiment is less than a few hundred micro liters in each reservoir. The utility of this system is demonstrated through investigating the viability of the prostate cancer PC3 cell line with the combinational treatments of curcumin and tumor necrosis factor-alpha related apoptosis inducing ligand (TRAIL). Our results suggest that the system can be used for screening and optimizing drug combination with a small amount of reagent for combinatorial chemotherapy against cancer cells.

关键词： Hydrokinetic generation   Resource assessment   Environmental impact assessment   Acoustic Doppler current profiler   Field measurements   Three-dimensional velocity  

摘要： The use of hydrokinetic technology in rivers for energy generation is an area of active research with potential applications in urban and rural settings. Negating the need for a physical barrier to the flow, instream hydrokinetic devices are viewed as having less environmental impact than conventional hydropower. The introduction of any device that alters the flow field, however, has the potential to affect both the river morphology and the ecosystem it supports. Characterizing the pre-installation flow conditions and monitoring changes following device installation are necessary to evaluate the ecological costs associated with this developing technology. This study presents techniques for quantifying the mean flow field throughout a study reach using an acoustic Doppler current profiler. Employing two survey procedures that provide flexibility in terms of the resolution and extent of measurements, quantities ranging from bulk flow features, such as discharge, to mean three-dimensional velocity profiles can be obtained. Results of the different survey procedures are demonstrated using data collected on the lower Roanoke River, USA. Recommendations are given to aid in the design of field data collection to best match the stage of the project. These measurements contribute to resource assessment at the site scale, designing turbines and planning installation, and environmental impact studies. (C) 2014 Elsevier Ltd. All rights reserved.