Publications by authors named "Vincent Bertin"
The dispersive spreading of microscopic particles in shear flows is influenced both by advection and thermal motion. At the nanoscale, interactions between such particles and their confining boundaries become unavoidable. We address the roles of electrostatic repulsion and absorption on the spatial distribution and dispersion of charged nanoparticles in near-surface shear flows, observed under evanescent illumination.
View Article and Find Full Text PDFMicroplastics in the abyss: a first investigation into sediments at 2443-m depth (Toulon, France).
Environ Sci Pollut Res Int
February 2022
Plastic and microplastic pollutions are known to be widespread across the planet in all types of environments. However, relatively little about microplastic quantities in the deeper areas of the oceans is known, due to the difficulty to reach these environments. In this work, we present an investigation of microplastic (<5 mm) distribution performed in the bottom sediments of the abyssal plain off the coast and the canyon of Toulon (France).
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- The study examines how self-propelled water-in-oil droplets behave when confined in different capillaries, revealing that dropping velocity decreases with increased confinement but stabilizes at high confinement levels.
- The research finds that as droplets are confined, unusual flow dynamics occur, including a thinning lubrication layer and neck formation at the droplet's rear, culminating in spontaneous splitting under very high confinement.
- An analytical model integrating interface activity with micelle transport is proposed to explain these dynamics, including the stabilization of velocity and the unique lubrication patterns that lead to droplet division.
We present experiments to study the relaxation of a nanoscale cylindrical perturbation at one of the two interfaces of a thin viscous freestanding polymeric film. Driven by capillarity, the film flows and evolves toward equilibrium by first symmetrizing the perturbation between the two interfaces and eventually broadening the perturbation. A full-Stokes hydrodynamic model is presented, which accounts for both the vertical and lateral flows and which highlights the symmetry in the system.
View Article and Find Full Text PDFWe present the first direct measurement of the elastohydrodynamic lift force acting on a sphere moving within a viscous liquid, near and along a soft substrate under nanometric confinement. Using atomic force microscopy, the lift force is probed as a function of the gap size, for various driving velocities, viscosities, and stiffnesses. The force increases as the gap is reduced and shows a saturation at small gap.
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- The deep ocean is the largest and least understood ecosystem on Earth, hosting many light-emitting pelagic organisms.
- A unique data set collected from December 2007 to June 2010 provides the longest continuous record of deep-sea bioluminescence, revealing significant seasonal light intensity blooms linked to changes in deep water properties.
- These blooms are mainly driven by luminous bacteria and highlight the connection between deep-sea biological activity and oceanic processes; monitoring these changes is crucial as climate change affects deep-sea ecosystems.