Control of Chemical Waves by Fluid Stretching and Compression.

Oscillatory kinetics coupled to diffusion can produce traveling waves as observed in physical, chemical, and biological systems. We show experimentally that the properties of such waves can be controlled by fluid stretching and compression in a hyperbolic flow. Localized packet waves consisting in a train of parallel waves can develop due to a balance between diffusive broadening and advective compression along the unstable manifold.

Structural and hydrodynamic controls on fluid travel time distributions across fracture networks.

Fracture networks are preferential flow paths playing a critical role in a wide range of environmental and industrial problems. Their complex multiscale structure leads to broad distributions of fluid travel times, affecting many biogeochemical processes. Yet, the relationship between the fracture network structures, their hydrodynamic properties, and the resulting anomalous transport dynamics remains unclear.

Transient nicotine exposure in early adolescent male mice freezes their dopamine circuits in an immature state.

How nicotine acts on developing neurocircuitry in adolescence to promote later addiction vulnerability remains largely unknown, but may hold the key for informing more effective intervention efforts. We found transient nicotine exposure in early adolescent (PND 21-28) male mice was sufficient to produce a marked vulnerability to nicotine in adulthood (PND 60 + ), associated with disrupted functional connectivity in dopaminergic circuits. These mice showed persistent adolescent-like behavioral and physiological responses to nicotine, suggesting that nicotine exposure in adolescence prolongs an immature, imbalanced state in the function of these circuits.

Fluid flow drives phenotypic heterogeneity in bacterial growth and adhesion on surfaces.

Bacteria often thrive in surface-attached communities, where they can form biofilms affording them multiple advantages. In this sessile form, fluid flow is a key component of their environments, renewing nutrients and transporting metabolic products and signaling molecules. It also controls colonization patterns and growth rates on surfaces, through bacteria transport, attachment and detachment.

Microscale Chaotic Mixing as a Driver for Chemical Reactions in Porous Media.

Mixing-induced reactions play a key role in a large range of biogeochemical and contaminant transport processes in the subsurface. Fluid flow through porous media was recently shown to exhibit chaotic mixing dynamics at the pore scale, enhancing microscale concentration gradients and controlling mixing rates. While this phenomenon is likely ubiquitous in environmental systems, it is not known how it affects chemical reactions.