An interdisciplinary effort to understand chemical organizations at the origin of life.

This backstory features the perspectives of three group leaders of a Franco-Indian collaboration on the origin of life, involving efforts to engineer evolvable chemical systems. The researchers explain how they overcame the difficulties to bring empiricist and theorist cultures together and the importance of such synergy for the future of origin of life research.

Interfacially driven instability in the microchannel flow of a shear-banding fluid.

Using microparticle image velocimetry, we resolve the spatial structure of the shear-banding flow of a wormlike micellar surfactant solution in a straight microchannel. We reveal an instability of the interface between the shear bands, associated with velocity modulations along the vorticity direction. We compare our results with a detailed theoretical study of the diffusive Johnson-Segalman model. The quantitative agreement obtained favors an instability scenario previously predicted theoretically but hitherto unobserved experimentally, driven by a normal stress jump across the interface between the bands.