关键词： 食品安全   风险分析框架   风险交流  

摘要： 国际学术界公认要解决好食品安全问题，需要遵循风险分析框架，但由于种种原因，作为食品安全风险分析框架的重要组成部分的风险交流体系建设工作，在我国则显得十分薄弱。当前，构建食品安全风险交流体系，制定科学的风险交流制度、政策、策略和具体措施，建立交流沟通渠道，强化知识普及和基础研究，对于促进我国社会共治食品安全、增强社会公众对食品安全问题的信心、切实改变我国食品安全现状，具有不可替代的重大意义。

关键词： Shallow lake   reed - open water interface   exchange flow   energy dissipation rate   turbulent characteristics   sediment deposition and resuspension  

摘要： Gradient-driven interactions and exchange mechanisms of the reed open water interface in shallow lake environment were investigated by localised field measurements and detailed data analysis. High frequency 3D flow velocities were recorded in several points . throughout a typical interface zone of Lake Feria. Based on the data the flow distribution, specific discharge, energy dissipation rate, turbulent characteristics, sediment deposition and resuspension tendencies were quantified near and inside the reed zone. Moving toward and into the reed zone, the decrease of the mean velocity component perpendicular to the interface, velocity fluctuation and the waverelated energy content of the flow were revealed along with the increasing tendency of the energy dissipation rate. Investigating the effect of different decomposition techniques on the turbulent characteristics, the one enabling the decomposition of wave-related components from turbulent components was suggested. Finally, continuous sediment deposition and the lack of resuspension were estimated in the investigated area.

关键词： 微流体系统   两相流流型   沸腾换热   压降特性   传热系数  

摘要： 通过分析微流体系统沸腾过程中两相流流型、压降特性和传热特性三个关键问题,总结了微流体系统中沸腾特性的研究进展。分散流、间歇流和环状流是微通道的三类基本流型。流型和传热分析中考虑了壁面润湿性、表面粗糙度及表面缺陷等因素。提出了横跨大尺度到微尺度的综合型流型图和压降预测方法的基本构想。微尺度相变传热领域还需要在流型转化界限、传热分区及预测、临界热流密度等方面进行深入研究,对新型通道结构、新的混合流体和新的应用背景下的特殊流体进行更为广泛的讨论,为微蒸发器的设计、制造及运行提供参考。

摘要： Microfluidics is attractive in many aspects and advancement of technology on these micron-scales have led to the development of devices often used in industries such as clinical and forensic analysis; micro-reaction engineering; surface patterning; and optical engineering. Despite its popularity, traditional microfluidic applications however, are known to have large dead volume; awkward chip- to-world interfaces; difficulty in exchanging solutions; and limited parallelization. Recent progresses in open microfluidic systems have shown great potential in addressing the aforementioned limitations. The aim of this thesis is to expand our understanding regarding fluid behaviour and interaction in the micro-domain scale of an open environment. Knowledge obtained through these studies could then be implemented in developing systems involving microfluidic components and bio-microfluidic applications. As a prelude to the main body of work, a basic theoretical framework on the background of microfluidics and the physics of the micro-scale is presented. The research can be divided into two major components, Part I: Open Microchannels and Part II: Microdroplets. These components were then further sub-categorized according to their applications including microfluidic pumping; mixing; liquid transfer; cell lysis; and concentration gradient generation. In all these, an open environment allowing for external interaction and manipulation was implemented. In Part I, flows on open channels and films was investigated. The open structures include a straight open channel defined by a narrow strip of solid surface and a wider structure allowing for multiple inputs and outputs. Computational models were also developed for fluid flow and the findings used to describe the factors affecting the stability of the system in both structures. The system can be seen as either a self-contained open fluidic device, or an open section in an otherwise enclosed system. Following on, the mixing mechanism

关键词： 人体运动系统   人体流体交互系统   人体运动路径规划   拉格朗日动力系统   耦合面   状态集  

摘要： 计算机三维动画是现在计算机的研究重点,其中,人体运动仿真技术被引用到了各个领域中。本文的研究重点在于实现流体环境下人体运动的仿真系统,由于硬件条件的限制,仿真系统的实时性仍是国内外研究的难点。本文的研究目的在于保证仿真效果的真实性下,尽力提高仿真效率,如果仿真效率遇到瓶颈,可以适当降低计算的精确度以提高仿真效率。本文在铰链体动画的基础上,建立人体运动仿真模型,实现了人体与流体的交互过程,并且控制人体在流体环境下进行运动。人体模型为树形结构,子链间满足父子链关系,通过仿真系统控制子链间的运动关系。本文通过一种基于耦合面的方法,研究了流体与人体的相互作用力。本文通过三维的A*算法计算得到人体运动的目标路径,并根据设定的状态改变量和相应的选择算法,研究了人体在流体环境下的运动路径。本文对常规方法的改进主要体现在三个方面,本文对耦合面的传递算法进行了改进,使得交互仿真性能得到提高;本文对加速度的计算公式进行了改进,使得速度更加平稳;本文对流体环境下人体的寻径算法进行了改进,使人体的运动状态种类更多,仿真效果更好。因为耦合面的数量巨大,矩阵计算的复杂度较高,本文提出了一种基于采样的方法,降低了耦合面的传递数量,对剩余耦合面进行插值计算。进一步的,考虑了流体的粘滞阻力,将速度计算公式由线性计算公式改进为非线性计算公式,然后对公式的收敛性进行了证明,随后本文提出基于视觉空间的状态选择算法,并对仿真系统的整体实现与测试进行了介绍,对其中一些关键模块的实现与接口的定义进行了阐述,详细介绍了仿真系统与渲染系统两个部分。最后,本文对系统的测试效果进行验证,并且对目前的研究成果进行了总结,以及对将来进一步工作的展望。

关键词： 一次性閥門   表面改質   微流體系統  

摘要： 为了达到微量控制待测流体，阀门对於试剂的储存以及保存、流体流动方向的控制、以及平行多工试剂的输送等目的有存在的必要性。本研究将利用低吸水性、低氧气与水气穿透性、以及低气体放射特性之热塑性塑胶材料如cyclo olefin polymer（COP）热塑性塑胶材料应用於阀门上，元件上局部区域先利用紫外臭氧处理COP元件表面後，在反应区域生长出一层会对非极性溶剂有阻抗性的薄氧化层，所以当元件使用溶剂接合来接合时，此紫外臭氧处理区域并不会接合因而形成一微小的缝隙，接着可以利用热接合方式将此缝隙封闭住，由於两种接合强度差异，使此设定之特定区域具备一次性压力阀门特性。本报告所提出阀门在没有外力作用下处於关闭的状态，达到节省储存试剂的能量需求，并且试剂能够保存於储水区而不需要其他致动弹性薄膜等避免溢漏等多余装置。不同驱动压力的一次性阀门可藉由简单改变紫外臭氧处理区域大小而同时制作於同一元件上，吾人相信此阀门具备便宜、使用介面友善、耐用、不需要额外设备且能够直接送至终端使用者之元件其中构成成份的潜力。

关键词： Paramagnetic Particles Based Isolation   Microfluidics   Glassy Carbon Electrode   Copper Nanoparticles Modification   Viral Nucleic Sequences   Stopped Flow Injection Analysis   Microwave Hydrolysis  

摘要： Detection of the specific sequences of pandemic-causing viral nucleic acids is area attracting numerous scientists worldwide. In this study, we focused on the isolation and detection of oligonucleotide specific sequences of life-threatening viruses (HIV (GAGCAGTGGGAATA), Influenza (TAATAACCATTGGA) and Ebola (ACCTCACTAGAAAA)) by flow injection analysis with electrochemical detection coupled with paramagnetic particles based isolation. All of used viral genomic sequences contained A6 adenine repetition on the 5' end. This modification enables us to bind them on paramagnetic particle anchoring T25 (MPs-(dT)(25)). The isolated sequences were subsequently hydrolysed by optimized method using microwaves to obtain single adenines. The obtained samples were detected by microfluidic tool based on stopped flow injection analysis with glassy carbon electrode in the presence of Cu(II)/or CuS nanoparticles to enhance sensitivity and to lower detection limit for adenine. Basic detection parameters as accumulation of CuS nanoparticles, flow influence and accumulation of the adenine deposition influencing the analytical response were also tested. We found that bases gave well developed signals with detection limit down to 30 ng per ml (50 pg per electrochemical cell) under the optimized conditions.

关键词： CO2-bearing fluid inclusions   Collision   Iran   Laser Raman spectroscopy   Meiduk porphyry copper deposit  

摘要： Hydrothermal alteration of the Meiduk porphyry copper deposit, south of the Kerman Cenozoic magmatic arc and southeast of the central Iranian volcano-plutonic belt has resulted in three stages of mineralisation characterised by veins and veinlets. These are, from early to late: (1) quartz + K-feldspar + biotite + pyrite ± chalcopyrite ± pyrrhotite ± magnetite (early potassic alteration and type-A veins);(2) quartz + chalcopyrite + pyrite + bornite + pyrrhotite + K- -feldspar + biotite + magnetite (potassic-sericitic alteration and type-B veins);and (3) quartz + pyrite + chalcopyrite + sericite (sericitic alteration and type-C veins). Most ores were formed during stages 2 and 3. Three main types of fluid inclusions are distinguished based on petrographical, microthermometrical and laser Raman spectroscopy analyses, i.e. type I (three-phase aqueous inclusions), type II (three-phase liquid-carbonic inclusions) and type III (multi-phase solid inclusions). The fluid inclusions in quartz veins of the stages are mainly homogenised at 340-530°C (stage 1), 270-385°C (stage 2) and 214-350°C (stage 3), respectively, with salinities of 3.1-16 wt.% NaCl equivalent, 2.2-43 wt.% NaCl equivalent and 8.2-22.8 wt.% NaCl equivalent, respectively. The estimated trapping pressures are 97.9-123.6 MPa (3.7-4.6 km) in stage 1 and 62.5-86.1 MPa (2.3-3.1 km) in stage 2, respectively. These fluid inclusions are homogenised in different ways at similar temperatures, suggesting that fluid boiling took place in stages 2 and 3. The fluid system evolved from high-temperature, medium-salinity, high-pressure and CO₂-rich to low-temperature, low-pressure, high-salinity and CO₂-poor, with fluid boiling being the dominating mechanism, followed by input of meteoric water. CO₂ escape may have been a factor in increasing activities of NaCl and S^2- in the fluids, diminishing the oxidation of the fluids from stage 1 to 3. The result was precipitation of sulphides

关键词： CELL separation   ENTROPY   MICROFLUIDICS   BROWNIAN motion processes   BIOPHYSICS  

摘要： A physical model is derived to create a biological cell separator that is based on controlling the entropy in a microfluidic system having conjoined spherical structures. A one-dimensional simplified model of this three-dimensional problem in terms of the corresponding effects of entropy on the Brownian motion of particles is presented. This dynamic mechanism is based on the Langevin equation from statistical thermodynamics and takes advantage of the characteristics of the Fokker-Planck equation. This mechanism can be applied to manipulate biological particles inside a microfluidic system with identical, conjoined, spherical compartments. This theoretical analysis is verified by performing a rapid and a simple technique for separating yeast cells in these conjoined, spherical microfluidic structures. The experimental results basically match with our theoretical model and we further analyze the parameters which can be used to control this separation mechanism. Both numerical simulations and experimental results show that the motion of the particles depends on the geometrical boundary conditions of the microfluidic system and the initial concentration of the diffusing material. This theoretical model can be implemented in future biophysics devices for the optimized design of passive cell sorters. (C) 2013 AIP Publishing LLC.