标题： 材料主动重排的奇异流变学 显示英文标题

标题： Exotic rheology of materials with active rearrangements

摘要： 在发育过程中，生物组织的流动通过细胞与组织中机械环境相互作用产生的主动应力来控制。 许多发育过程由收敛-延伸流驱动，其中组织表现出一种涌现的负剪切模量和粘度。 这种奇特的流变特性是通过主动T1转变产生的，其中重排方向与施加的应力方向相反。 在此，我们引入了一个平均场弹塑性模型，该模型基于Hebraud-Lequeux模型，展示了收敛-延伸流，包含被动和主动弹性元件，其应力响应相反。 我们发现，引入主动元件显著改变了流变特性。 超过一定比例的主动元件后，它会导致非单调的流动曲线以及在正应变率下的负应力。 受主动比例和应力扩散速率的控制，我们发现了具有正或负屈服应力或粘度的屈服应力材料和流体。 这些特性是超材料的特征，并突显了生物学如何利用具有奇特流变特性的无序主动材料。 显示英文摘要

摘要： The flow of biological tissues during development is controlled through the active stresses generated by cells interacting with their mechanical environment in the tissue. Many developmental processes are driven by convergence-extension flows where the tissue has an emergent negative shear modulus and viscosity. This exotic rheology is generated through active T1 transitions where rearrangements are opposite the applied stress direction. Here, we introduce a mean-field elasto-plastic model which shows convergence-extension, based on the Hebraud-Lequeux model, that includes both passive and active elastic elements with opposite stress responses. We find that the introduction of active elements profoundly changes the rheology. Beyond a threshold fraction of active elements, it gives rise to non-monotonic flow curves and negative stresses at positive strain rates. Controlled by the active fraction and the stress diffusion rate, we find both yield stress materials and fluids, with either a positive or negative yield stress or viscosity. These features are characteristic of metamaterials, and highlight how biology uses disordered, active materials with exotic rheology.