Leiden University
Colloquium Ehrenfestii 2017


COLLOQUIUM EHRENFESTII 2017

initiated by Paul Ehrenfest in 1912
currently organized by Vincenzo Vitelli & Koenraad Schalm (read about its history)


Meal reservation form

1 March

Oleg Lavrentovich (Kent State)

Dynamics of colloids in liquid crystals

Behavior of small particles in fluids has fascinated scientist for centuries. Phenomena such as Brownian motion, sedimentation, and electrophoresis continue to inspire cutting-edge research and innovation. The fluid in which the colloidal particles move is typically isotropic, such as water or a dilute polymer solution. There is a growing interest to the dynamics of colloids in crowded environments with some elements of order. As a model system, we explore colloidal dynamics in a nematic liquid crystal. Orientational order of the liquid crystal leads to long-range elastic interactions that dramatically alter static behavior of the colloids and support their levitation. Equally strong changes are seen in the dynamics. The liquid crystalline environment enables anomalous Brownian diffusion and new mechanisms of electrokinetics with nonlinear (quadratic) dependence of flow velocities on the applied electric field. Addition of swimming bacteria to a non-toxic liquid crystal creates an experimentally controlled active system, which exhibits a cascade of transitions from equilibrium to non-equilibrium orientational patterns triggered by an increase of activity. Patterned director fields including those with topological defects control the threshold and polarity of active flows and spatial distribution of microswimmers. The new phenomena are rooted in anisotropy of the liquid crystals properties, such as surface tension, viscosity and elasticity, dielectric permittivity and conductivity.


The Colloquium Ehrenfestii takes place Wednesday evenings starting at 19:30 hours in the main auditorium of the Oort building. Before the Colloquium, there is a common dinner in the canteen located on the ground floor of the Oort building. This dinner starts at 18:00 hours sharp and is free of charge, under the condition that one attends the colloquium and that one has made a reservation before noon on the Tuesday preceding the colloquium. [Registration may close earlier, when 80 persons have signed up]

Colloquium Ehrenfestii 2017

1 Feb

Leo Radzihovsky (Boulder)

Chiral symmetry breaking, emergent Higgs mechanism, and critical matter

15 Feb

Yossi Avron (Technion)

The geometry of non-dissipative transport: From conductance to viscosity

1 Mar

Oleg Lavrentovich (Kent State)

Dynamics of colloids in liquid crystals

8 Mar

Anne Davis (Cambridge)

TBA

5 Apr

Jacques Prost (Curie Institute)

TBA

19 Apr

Cristina Marchetti (Syracuse)

TBA

10 May

Michael Berry (Bristol)

TBA

31 May

Julia Yeomans (Oxford)

TBA

14 Jun

Renata Kallosh (Lorentz Professor)

TBA

Programs from previous years

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