Microgravity fluid physics is an important part of microgravity sciences, which consists of simple fluids of many new systems, gas-liquid two-phase flow and heat transfer, and complex fluid mechanics. In addition to the importance of itself in sciences and applications, microgravity fluid physics closely relates to microgravity combustion, space biotechnology and space materials science, and promotes the developments of interdisciplinary fields. Many space microgravity experiments have been performed on board the recoverable satellites and space ships of China and pushed the rapid development of microgravity sciences in China. In the present paper, space experimental studies and the main results of the microgravity fluid science in China in the last 10 years or so are introduced briefly.
HU WenRuiLONG MianKANG QiXIE JingChangHOU MeiYingZHAO JianFuDUAN LiWANG ShuangFeng
Neutrophil (PMN) spreading on endothelium, mediated by the interactions between surface-bound β2 integrin and intercellular adhesion molecule-1 (ICAM-1) in the inflammatory cascade, is crucial for PMN post-adhesion and trans-migration in blood flow. The underlying mechanisms by which shear flow regulates PMN spreading dynamics are not well understood. Here, a parallel-plate flow chamber assay was applied to quantify the time course of PMN adhesion and spreading on an ICAM-1-immobilized substrate. Two types of shear flow, steady flows at shear stresses of 0.2, 0.5, and 1 dyne/cm2 and stepwise flows at 0, 1, and 10 dyne/cm2, were used to elucidate the impact of shear flow on cell adhesion and spreading. The number of adhered PMNs, the fraction of spreading PMNs and the projected area of spread PMNs were determined and were found to correlate with the distribution of surface-bound β2 integrin subunit (CD11a, CD11b, or CD18). The results indicate that PMN spreading on an ICAM-1 substrate is bi-directionally regulated under shear flow. CD11a, CD11b and CD18 subunits of β2 integrin contribute distinctly to PMN spreading on ICAM-1 substrates. This work provides new insights into understanding PMN spreading on the endothelium, mediated by β2 integrin and ICAM-1 under shear flow.
