标题： 聚集红细胞的屈曲不稳定性 显示英文标题

标题： The buckling instability of aggregating red blood cells

摘要： 血浆蛋白如纤维蛋白原会诱导红细胞（RBC）聚集形成串钱状结构，这些结构负责血液明显的剪切稀化行为，控制着红细胞沉降率（ESR），这是一个常见的血液学测试，并且在许多生理相关的情况下起作用，例如微循环中血液的结构化或病理情况下的凝血形成。共聚焦显微镜用于表征平衡状态下红细胞在串钱状结构中的形状，作为大分子浓度的函数，揭示了接触区域形态的多样性。识别出三种之前仅部分预测过的不同结构，即降落伞形、男女形和S形，并通过数值模拟定量恢复。对两个细胞簇的详细实验和理论分析表明，变形随着相互作用能非线性增加。模型显示了一个前向分岔，在相互作用能达到临界值时，接触膜从平坦的接触区经历屈曲不稳定性变为变形的接触区。这些结果不仅有助于理解红细胞聚集体的形态和稳定性，而且对于一类相互作用的软性可变形物体，如囊泡、胶囊或组织中的细胞也具有重要意义。 显示英文摘要

摘要： Plasma proteins such as fibrinogen induce the aggregation of red blood cells (RBC) into rouleaux, which are responsible for the pronounced shear thinning behavior of blood, control the erythro- cyte sedimentation rate (ESR) a common hematological test and are involved in many situations of physiological relevance such as structuration of blood in the microcirculation or clot formation in pathological situations. Confocal microscopy is used to characterize the shape of RBCs within rouleaux at equilibrium as a function of macromolecular concentration, revealing the diversity of contact zone morphology. Three different configurations that have only been partly predicted before are identified, namely parachute, male-female and sigmoid shapes, and quantitatively recovered by numerical simulations. A detailed experimental and theoretical analysis of clusters of two cells shows that the deformation increases nonlinearly with the interaction energy. Models indicate a forward bifurcation in which the contacting membrane undergoes a buckling instability from a flat to a de- formed contact zone at a critical value of the interaction energy. These results are not only relevant for the understanding of the morphology and stability of RBC aggregates, but also for a whole class of interacting soft deformable objects such as vesicles, capsules or cells in tissues.