Actin cytoskeleton reorganization, which is governed by actin-associated proteins, has a close relationship with the change of cell biological behavior. However, a perceived understanding of how actin mechanical property links to cell biological property remains unclear. This paper reports a label-free biomarker to indicate this interrelationship by using the actin cytoskeleton model and optical tweezers (OT) manipulation technology. Both biophysical and biochemical methods were employed, respectively, as stimuli for two case studies. By comparing the mechanical and biological experiment results of the leukemia cells under electrical field exposure and human mesenchymal stem cells (hMSC) under adipogenesis differentiation, we concluded that β-actin can function as an indicator in characterizing the alteration of cellular biological behavior during the change of actin cytoskeleton mechanical property. This study demonstrated an effective way to probe a quantitative understanding of how actin cytoskeleton reorganization reflects the interrelation between cell mechanical property and cell biological behavior.

Using supercritical CO₂ as a heat transfer fluid in microchannel receivers is a promising alternative for tower concentrating solar power plants. In this paper, the heat transfer and flow characteristics of supercritical CO₂ in microchannels at high temperature are investigated by numerical simulations. The effects of microchannel structure, mass flow rate, heat flux, pressure, inlet temperature and radiation are analyzed and discussed. The results show that higher mass flow rate obtains poorer heat transfer performance with larger flow resistance of supercritical CO₂ in microchannels at high temperature. The fluid and wall temperatures, average heat transfer coefficient and pressure drop all increase nearly linearly with the increases in heat flux and inlet temperature in the high-temperature region. Moreover, high pressure contributes to great hydraulic performance with approximate thermal performance. The effect of radiation on thermal performance is more pronounced than that on hydraulic performance. Furthermore, the optimized structures of inlet and outlet headers, as well as those of the multichannel in the microchannels, are proposed to obtain good temperature uniformity in the microchannels with relatively low pressure drop. The results given in the current study can be conducive to the design and application of microchannel receivers with supercritical CO₂ as a heat transfer fluid in the third generation of concentrating solar power plants.

微通道流动沸腾冷却技术兼具相变潜热和微尺度效应的诸多优点，是解决微电子器件热致失效问题的重要方法之一。HFE-7100是一种安全环保的电子氟化液，特别适用于微电子器件的冷却。本文在水力直径为0.5 mm的矩形平行微通道内，对HFE-7100的流动沸腾传热和两相流动特性进行了实验研究。测量范围为常压下质量流率88.9 ~ 277.8 kg∙m^-2∙s^-1、入口过冷度20 ~ 35.5°C和有效热流密度12 ~ 279 kW∙m^-2。分析了质量流率、入口过冷度、有效热流密度和干度对传热系数和压降的影响，发现较低的入口过冷度下HFE-7100出现了沸腾迟滞现象，且增大入口过冷度和质量流率会延缓沸腾起始点的发生，同时提高传热系数和临界热流密度。两相压降受有效热流密度影响较大，且在定干度下不同质量流率的两相压降在塞状流和环状流阶段有明显差异。同时，通过观测两相流型，对流动沸腾传热现象进行了分析。本文还将两相压降实验数据与文献关联式预测值进行了对比，与Lockhart提出的关联式预测值偏差为19.6%。本文研究结果可为微电子器件散热设备的优化设计提供理论指导：以HFE-7100作为传热工质并将微通道流动沸腾冷却技术应用于微电子器件散热设备，可以提高设备的稳定性和可靠性；在不同热流密度的设备中通过控制入口过冷度和质量流率可有效提升其散热性能；采用Lockhart提出的两相压降关联式可预测散热设备所需泵功。