News

Colloquium by G. Volpe at ICF, Cuernavaca, 13 Feb 2019

Emergent Complex Behaviour in Active Matter
Giovanni Volpe
Colloquium at Instituto de Ciencias Físicas
Cuernavaca, Morelos, Mexico
13 February 2019

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.
First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.
Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.
Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

https://www.fis.unam.mx/coloquios/473/qemergent-complex-behaviour-in-active-matterq

Talk by F. Schmidt at APS March Meeting 2019, Boston, 6 Mar 2019

Light-driven Assembly of Motile Colloidal Clusters from Immotile Building Blocks
Falko Schmidt, Benno Liebchen, Hartmut Löwen & Giovanni Volpe
APS March Meeting 2019, Boston, USA
6 March 2019 at 8:36-8:48 a.m., Room 258B

Active matter, consisting of self-propelled units locally injecting energy into the system, opens new horizons for the creation of functional soft materials with designable properties. Experiencing a constant energy input, allows active matter to self-assemble into phases with a complex architecture and functionality such as living clusters which dynamically form, reshape and break-up but would be forbidden in equilibrium material by the entropy maximization (or free energy minimization) principle. The challenge to control this active self-assembly has evoked widespread efforts typically hinging on an engineering of the properties of individual motile constituents. Here, we provide a different route, where activity occurs as an emergent phenomenon only when individual building blocks bind together, in a way which we control by laser light. Using experiments and simulations of two species of immotile microspheres, we exemplify this route by creating active molecules featuring a complex array of behaviors, becoming migrators, spinners and rotators. The possibility to control the dynamics of active self-assembly via light-controllable nonreciprocal interactions will inspire new approaches to understand living matter and to design active materials.

Reference: Schmidt et al. Light-controlled Assembly of Active Colloidal Molecules arXiv:1801.06868 (2018)

Theo Berglin joins the Soft Matter Lab

Theo Berglin joined the Soft Matter Lab on 21 January 2019.

Theo Berglin is a Master student in the Complex Adaptive Systems Master at Chalmers University of Technology.

He will work on his Master thesis on the development of Braph, the software for brain connector analysis developed by the Soft Matter Lab in collaboration with Karolinska Institutet.

Adam Liberda joins the Soft Matter Lab

Adam Liberda joined the Soft Matter Lab on 21 January 2019.

Adam Liberda is a Master student in the Complex Adaptive Systems Master at Chalmers University of Technology.

He will work on his Master thesis on the development of Braph, the software for brain connector analysis developed by the Soft Matter Lab in collaboration with Karolinska Institutet.

Seminar on fast volumetric light-sheet microscopy by Omar E. Olarte from Universidad ECCI, Colombia, Nexus, 17 Dec 2018

Fast volumetric light-sheet microscopy
Seminar by Omar E. Olarte
from Universidad ECCI, Colombia (and ICFO, Barcelona, Spain)

Light sheet fluorescence microscopy (LSFM) is a convenient tool for bio-imaging as it efficiently collects the generated fluorescence while at the same time minimizes photobleaching. For these reasons LSFM, being based on an intrinsic 2D illumination strategy, has been put forward as an interesting candidate for fast volumetric imaging.

We report on a LSFM microscope, combined with the use of wavefront coding (WFC) techniques, for fast volumetric imaging. This provides intrinsic 3D imaging capabilities as it extends the depth of field (DOF) of the microscope. In addition, because of the extended DOF, the light sheet can be axially scanned at fast speeds. As only the light sheet is moved, fast 3D imaging can be achieved without the need of any sample or objective movement. Since typical light scanning devices can run at KHz rates, 3D volumetric acquisition speeds will only be limited by the reading speed of the camera or the required signal to noise ratio.

WFC works at the expenses of introducing a controlled aberration to the system which blurs the resulting images. Then it requires a final deconvolution step to recover the image sharpness that would impose a limitation on the application. Here we present computational tools to perform real-time deconvolution and visualization of the images obtained with WFC-LSFM. To speed up such deconvolution processes, a routine directly developed in a GPUs has been developed. We present preliminary results on realistic computer generated images showing that real-time deconvolution and visualization is possible.

Place: Nexus
Time: 17 December 2018, 16:00

Seminar on effective drifts in generalized Langevin systems by Soon Hoe Lim from Nordita, Soliden 3rd floor, 12 Dec 2018

Effective Drifts in Generalized Langevin Systems
Seminar by Soon Hoe Lim
from Nordita, Stockholm, Sweden, EU

Generalized Langevin equations (GLEs) are stochastic integro-differential equations commonly used as models in non-equilibrium statistical mechanics to describe the dynamics of a particle coupled to a heat bath. From modeling point of view, it is often desirable to derive effective mathematical models, in the form of stochastic differential equations (SDEs), to capture the essential dynamics of the systems. In this talk, we consider effective SDEs describing the behavior of a large class of generalized Langevin systems in the limits when natural time scales become very small. It turns out that additional drift terms, called noise-induced drifts, appear in the effective SDEs. We discuss recent progress on the phenomena of noise-induced drift in these systems. This is joint work with Jan Wehr and Maciej Lowenstein.

Place: Soliden 3rd floor
Time: 12 December 2018, 13:00

Jalpa Soni is MSCA Fellow of the Week

Our Marie-Curie postdoctoral researcher Jalpa Soni becomes the #MSCA Fellow of the Week, and gets her project highlighted on Tweeter and Facebook pages of the Marie-Skłodowska-Curie Actions

Jalpa is studying the behaviour of micro swimmers like bacteria in 3D complex environments. That will give us the understanding of how they propagate in living systems, which in turn will be used to manipulate them for medicinal advantages.One such example would be to create artificial swimmers (active particles) mimicking natural bacteria for more efficient and targeted drug-delivery applications.To monitor the movement of such micro swimmers in 3D, Jalpa has developed a customised light-sheet microscope that is capable of fast volumetric imaging. The long term goal of the project is to create active particle induced drug-delivery methods for organ-on-chip devices and to monitor the drug efficacy in real time.

This is Jalpa’s insight as a MSCA fellow:

“The unique opportunity to build a new collaborative network has been the most beneficial aspect of my MSCA fellowship. The travels for the project has allowed me to experience different research organisations and to meet experts of various fields which is very important for interdisciplinary research that I love doing.”

Project Name: ActiveMotion3D – Experimental study of three-dimensional dynamics of Active particles

Learn more about Jalpa and her project:
CORDIS: https://bit.ly/2Rz1rVD

Tweeter: https://twitter.com/MSCActions/status/1070985015754919936
FB: