• Expert ANR

• Membre d'un pool d'experts

• Chimie/Génie chimique
  
• Sciences de l'ingénieur/Génie des procédés
  
• Sciences du Vivant/Médecine humaine et pathologie/Pneumologie et système respiratoire
  
• Sciences du Vivant/Biologie cellulaire/Organisation et fonctions cellulaires [q-bio.SC]
  
• Sciences du Vivant
  
• Physique/Physique/Biophysique
  
• Physique/Matière Condensée/Matière Molle
  
• Physique/Matière Condensée/Mécanique statistique
  
• Sciences du Vivant/Ecologie, Environnement/Santé
  
• Sciences du Vivant/Biotechnologies
  
• Sciences de l'ingénieur/Milieux fluides et réactifs
  
• Chimie/Polymères
  
• Chimie/Matériaux
  
• Physique/Matière Condensée/Science des matériaux
  
• Physique/Mécanique/Mécanique des solides
  
• Sciences de l'ingénieur/Mécanique/Mécanique des solides
  
• Chimie/Chimie organique
  
• Physique/Matière Condensée/Autre
  

Numerical simulations of a drop crossing a plane liquid-liquid interface in a centrifugal field have been performed by using the Level-Set method. The objective is to characterize the hydrodynamical parameters controlling the coating volume of the droplet, which results from the rupture of the liquid column of lighter phase entrained by the droplet during the crossing of the interface in the tailing regime. The numerical method has been first validated in two-phase flow simulations of a drop rising in a stagnant liquid, then in three-phase flow configurations to reproduce the theoretical critical condition for a drop to cross an interface in static conditions (without initial velocity). Then, in inertial conditions, extensive simulations of crossing droplets have been performed in a wide range of flow parameters and phase properties, for two types of drop: solid-like droplets (mimicking rigid particles) and deformable drops. The crossing criteria is found to remain very close to that given by the theory in static conditions, either for a spherical or a deformed droplet. For each studied case, the crossing time, the maximum length of the column of liquid pulled by the droplet and the volume encapsulating the drop after crossing have been computed and scaled as a function of an inertia parameter, which is the ratio F* between the inertial stresses pushing on the interface, defined from the minimum drop velocity reached during crossing as characteristic velocity, and the opposite stress pulling back the entrained column towards the interface. The maximal column length increases with F* (when rescaled by the minimal inertial required for crossing) under two distinct growth rates according to the flow regime in the column. For solid-like drops, the final coating volume is a unique function of F*, and grows with F* at large inertia. In the case of deformable droplets, the coating volume evolution can also be well predicted by F* but corrected by the drop-to-film viscosity ratio, which strongly affects the drainage rate of the film along the drop surface during the encapsulation process.

The mucociliary function of the bronchial epithelium ensures the continuous clearance of the respiratory system. This function relies on two main elements: mucus properties and cilia beating coordination. We work on high speed optical microscopy videos of Human bronchial epithelium from ALI (Air-liquid interface) cultures. We present here a technique based on the tracking of each cilium and on the spatiotemporal analysis of the obtained trajectories. To relate each cilium to its corresponding cell, a clustering method is used. The spatiotemporal coordination can than be quantified both, inside and in-between ciliated cells. In addition the physical parameters can be mapped to observe the heterogeneity of the cilia activity and compare different pathologies.

We describe an original method to measure mucus microrheology on human bronchial epithelium culture using optical tweezers. We probed rheology on the whole thickness of mucus above the epithelium and showed that mucus gradually varies in rheological response, from an elastic behavior close to the epithelium to a viscous one far away. Microrheology was also performed on mucus collected on the culture, on ex vivo mucus collected by bronchoscopy, and on another epithelium model. Differences are discussed and are related to mucus heterogeneity, adhesiveness and collection method.