Kinetic modeling of the chemotactic process in run-and-tumble bacteria.

The chemotactic process of run-and-tumble bacteria results from modulating the tumbling rate in response to changes in chemoattractant gradients felt by the bacteria. The response has a characteristic memory time and is subject to important fluctuations. These ingredients are considered in a kinetic description of chemotaxis, allowing the computation of the stationary mobility and the relaxation times needed to reach the steady state.

Run-and-tumble bacteria slowly approaching the diffusive regime.

The run-and-tumble (RT) dynamics followed by bacterial swimmers gives rise first to a ballistic motion due to their persistence and later, through consecutive tumbles, to a diffusive process. Here we investigate how long it takes for a dilute swimmer suspension to reach the diffusive regime as well as what is the amplitude of the deviations from the diffusive dynamics. A linear time dependence of the mean-squared displacement (MSD) is insufficient to characterize diffusion and thus we also focus on the excess kurtosis of the displacement distribution.

Assessing the arrest of coalescence due to Marangoni effects in flowing emulsions using population balance.

The conditions for coalescence arrest due to Marangoni effect of surfactant enriched emulsions flowing through a microfluidic device are analyzed. For that aim, we develop a Population Balance Equation model that allows the quantification of coalescence occurrence for emulsion systems at different surfactant concentration making use of isotherms. Besides, our model requires three parameters with physical significance to describe the behavior of the emulsions under shear to include Marangoni flow.