We present two examples of active chemo-mechanical biological systems focusing on the question of how chemistry is coupled to mechanics. The first example examines the active generation of stress in skeletal muscles, which critically depends on ATP hydrolysis. The underlying mechanical processes take place far from equilibrium and can be represented by a stochastic model  that both dissipates energy and receives energy input from external sources.  We introduce a minimal mechanical framework capable of reproducing all four states in the minimal Lymn–Taylor chemical  cycle of muscle contractions thereby opening new avenues for the design of artificial devices that mimic enzymatic activity. The second example addresses the active mechanics of cell motility. Although the molecular and biochemical mechanisms underlying active  self-propulsion  are well established, a comprehensive mechanical theory of this phenomenon remains an open challenge.    motility.  To clarify the  mechanical interplay between the underlying contraction and the resulting  protrusion  we develop   a model of the simplest lamellipodial  Mathematically, this model takes the form of a Keller–Segel-type dynamical system; however, unlike classical chemotaxis models, its nonlocality arises from mechanical rather than chemical pathways. Characteristically, the resulting active system exhibits both dissipative and anti-dissipative behavior. Beyond its theoretical significance, our analysis suggests a new paradigm for the optimal design of crawling biomimetic robots, where conventional mechanical actuation is augmented by distributed chemical control of material remodeling within the force-transmitting machinery.

Bio:

LEV TRUSKINOVSKY is  Directeur de Recherche CNRS (DR CE2) working at  ESPCI, France. He received his education in the school of Mathematics and Mechanics at Moscow state University  and before coming to France  was for 15 years a professor at the Department of Aerospace Engineering and Mechanics at the  University of Minnesota. He served as a President of  International Society for the Interaction of Mechanics and Mathematics and as Editor in Chief of Springer Journal  Continuum Mechanics and Thermodynamics. He is now a member of the National French Committee of Theoretical and Applied Mechanics.