用于水下测量的二分力天平

本文介绍一种用于水下测量的二分力天平。天平采用内式悬臂梁双变形结构,把力和力矩的测量分开,避免了力作用点变化对测量结果的影响;天平设计和严格的加工精度保证了二分力之间干扰系数接近零;天平防水层采用了特制涂料。使用该天平在水洞中进行了单柱水动力系数测量实验,并将实验结果与已有的数据作了比较

海底边界对水下管线的水动力影响

本文叙述了在定常流中,用平板模拟海底平面边界,在雷诺数R_e为4.0×10~3～1.5×10~5范围内,测量了孤立圆柱和离平板不同距离上的单柱的阻力(C_D)、升力(C_L)、上抬力(C_(LO))等水动力系数和响应频率f。研究了管道距平板边界的相对间距H/D(H为圆柱与平板之间的间距;D为圆柱直径)对水动力特性的影响

The effects of viscous heating and the pressure-dependent viscosity on liquid flow in microtubes

The flow characteristics of isopropanol. in microtubes driven by a high pressure ranging from 1 MPa to 30 MPa are studied in this paper. The diameters of the microtubes are from 3 mu m to 100 mu n. The Reynolds number ranges from 0.1 to 1000 approximately. From the present experimental results, two reverse trends of the normalized friction coefficient C* are found for the various diameters. From the analysis of several possible factors, it may be seen that the pressure-dependence viscosity and viscous heating play the leading role. The relationship of viscosity versus pressure pointed out that the viscosity of most liquids, except the water, augmented with the increase of pressure. The analysis based on the energy equation turns out that pressure drop, specific heat, density, flow rate and heat resistance decide the average temperature rise due to viscous dissipation. Therefore, above two factors are treated as the function of pressure. An exponential function with the dependence of pressure is introduced into Hagen-Poiseuille (HP) equation to counteract the difference between experimental and theoretical values. Consequently, C* exhibits different trends which is decided by the relative importance of viscous heating and the pressure-dependent viscosity

The influence of nano-particle tracers on the slip length measurements by microPTV

Direct measurement of slip length is based on the measured fluid velocity near solid boundary. However, previous micro particle image velocimetry/particle tracking velocimetry (microPIV/PTV) measurements have reported surprisingly large measured near-wall velocities of pressure-driven flow in apparent contradiction with the no-slip hypothesis and experimental results from other techniques. To better interpret the measured results of the microPIV/PTV, we performed velocity profile measurements near a hydrophilic wall (z = 0.25-1.5 mu m) with two sizes of tracer particles (phi 50 nm and phi 200 nm). The experimental results indicate that, at less than 1 mu m from the wall, the deviations between the measured velocities and no-slip theoretical values obviously decrease from 93% of phi 200 nm particles to 48% of phi 50 nm particles. The Boltzmann-like exponential measured particle concentrations near wall were found. Based on the non linear Boltzmann distribution of particle concentration and the effective focus plane thickness, we illustrated the reason of the apparent velocity increase near wall and proposed a method to correct the measured velocity profile. By this method, the deviations between the corrected measured velocities and the no-slip theoretical velocity decrease from 45.8% to 10%, and the measured slip length on hydrophilic glass is revised from 75 nm to 16 nm. These results indicated that the particle size and the biased particle concentration distribution can significantly affect near wall velocity measurement via microPIV/PTV, and result in larger measured velocity and slip length close to wall

Observation of the induced pressure in a hybrid micro/nano-channel

This paper studies the flow characteristics in micro/nano-channels subjected to an applied electric field. The nano-channel flow was observed by means of the fluorescence Calcein. A Fluorescence Concentration Gradient Interface (FCGI) was observed across the nano-channel array. The front of the FCGI was shown to have an analogous parabolic shape. The propagation of this interface reflects indirectly the induced pressure at the micro/nano-channel junction, where the enrichment-depletion processes are known to take place. This induced pressure was predicted by numerical simulations, and this paper gives the first experimental evidence

Non-Gaussian statistics for the motion of self-propelled Janus particles: Experiment versus theory

Spherical Janus particles are one of the most prominent examples for active Brownian objects. Here, we study the diffusiophoretic motion of such microswimmers in experiment and in theory. Three stages are found: simple Brownian motion at short times, superdiffusion at intermediate times, and finally diffusive behavior again at long times. These three regimes observed in the experiments are compared with a theoretical model for the Langevin dynamics of self-propelled particles with coupled translational and rotational motion. Besides the mean square displacement also higher displacement moments are addressed. In particular, theoretical predictions regarding the non-Gaussian behavior of self-propelled particles are verified in the experiments. Furthermore, the full displacement probability distribution is analyzed, where in agreement with Brownian dynamics simulations either an extremely broadened peak or a pronounced double-peak structure is found, depending on the experimental conditions

养正消积胶囊辅助GP方案治疗晚期非小细胞肺癌临床研究

目的观察养正消积胶囊辅助GP方案治疗晚期非小细胞肺癌(NSCLC)的临床疗效。方法采用随机数字表法将89例晚期NSCLC患者分为对照组44例及观察组45例。2组均采用GP方案;观察组并予养正消积胶囊,每次4粒,每日3次,口服。2组均21d为1个周期,连续治疗2个周期,随访1年。观察2组治疗前后Ki67、Bax、Bcl-2蛋白表达及肿瘤标志物[血管内皮生长因子(VEGF)、骨桥蛋白(OPN)、癌胚抗原(CEA)、糖类抗原199(CA199)]、中医症状评分、生活质量评分,比较2组客观缓解率(ORR)、疾病控制率(DCR)、无进展生存时间(PFS),监测不良反应。结果观察组ORR、DCR明显优于对照组(P<0.05)。与本组治疗前比较,观察组治疗后、随访1年VEGF、OPN、CEA、CA199水平明显降低(P<0.05);对照组治疗后上述指标明显降低(P<0.05),随访1年CEA水平明显降低(P<0.05)。与本组治疗前比较,2组治疗后Ki67、Bcl-2蛋白表达明显降低,Bax蛋白表达明显升高(P<0.05);2组治疗后比较,观察组Ki67、Bcl-2蛋白表达低于对照组(P<0.05),Bax蛋白表达高于对照组(P<0.05)。与本组治疗前比较,2组治疗后中医症状评分(神疲乏力、胃纳少馨、腰膝无力、夜尿频多、头晕目眩)、生活质量评分(躯体功能、认知功能、社会功能、情绪功能)明显改善(P<0.05);2组治疗后比较,观察组上述评分改善明显优于对照组(P<0.05)。观察组PFS明显长于对照组(P<0.05),不良反应明显低于对照组(P<0.05)。结论养正消积胶囊辅助GP方案治疗晚期NSCLC可有效降低患者肿瘤标志物水平,改善生存质量,减少吉西他滨和顺铂的不良反应,提高疗效。福建省卫生厅中医药科研专项课题(wst201210

微纳复合管道流场特征分析

由于浓度极化等因素造成微纳复合管道结合部流场具有电渗流和压力流综合作用特点。根据流场观测,本报告将分析浓度扩散和富集发生的位置与过程,及纳微米通道尺度与富集效率的关系

微纳尺度流动实验研究

主要介绍本组近年在微纳米流动实验方面的工作:检验基于连续方程的Poisuille流量公式开展了微米通道(Φ100μm～Φ3μm)简单液体流动;利用MicroPIV/PTV测量滑移长度中,研究了纳米示踪粒子(Φ200 nm～Φ50 nm)对速度场测量的影响;粒子表面性质对扩散系数的影响

“微纳流动与复杂流体”专刊简介

二十一世纪初"微流控芯片""基因工程"等高新技术的兴起促进了微纳流体力学的发展。经典流体力学早期就开展了"低雷诺数""多孔介质"等低速、小空间尺度流动的研究,但微纳流动研究的空间或粒子的尺度更小,在一纳米至百微米范围,流动介质涉及细胞液、乳浊液等复杂流体。因此,微纳流动和复杂流体的研究具有了介观尺度的特性和更强的应用背景,需要流体力学、统计物理、化学、材料科学、生物学等多种学科的有机融合。《实验流体力学》适时推出"微纳流动与复杂流体"专刊,初衷是"为促进交流,希望向非力学专业(如化学、生物等)相关领域的学者们介绍微纳流动研究的前沿进展"