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    On the adhesion between thin sheets and randomly rough surfaces
    (Lausanne : Frontiers Media, 2022) Wang , Anle; Müser, Martin H.
    Thin, elastic sheets are well known to adapt to rough counterfaces, whereby adhesive interactions and pull-off stresses σp can be significant, yet no generally applicable, quantitative guideline has been suggested hitherto as to when a sheet should be considered thin enough to be sticky. Using computer simulations, we find that the dependence of σp on surface energy γ has a high and a low-pull-off-stress regime. For randomly rough surfaces, we locate the dividing line at the point, where γ is approximately half the elastic energy per unit area needed to make conformal contact, which is the same ratio as for semi-infinite elastic solids. This rule of thumb also applies to a certain degree for single-wavelength roughness, in which case the transition from low to high stickiness occurs when at the moment of maximum tension contact is not only broken at the height maxima but also at the saddle points.
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    Microenvironments designed to support growth and function of neuronal cells
    (Lausanne : Frontiers Media, 2018) Farrukh, Aleeza; Zhao, Shifang; del Campo, Aránzazu
    Strategies for neural tissue repair heavily depend on our ability to temporally reconstruct the natural cellular microenvironment of neural cells. Biomaterials play a fundamental role in this context, as they provide the mechanical support for cells to attach and migrate to the injury site, as well as fundamental signals for differentiation. This review describes how different cellular processes (attachment, proliferation, and (directional) migration and differentiation) have been supported by different material parameters, in vitro and in vivo. Although incipient guidelines for biomaterial design become visible, literature in the field remains rather phenomenological. As in other fields of tissue regeneration, progress will depend on more systematic studies on cell-materials response, better understanding on how cells behave and understand signals in their natural milieu from neurobiology studies, and the translation of this knowledge into engineered microenvironments for clinical use.