scholarly journals Emergent vortices and phase separation in systems of chiral active particles with dipolar interactions

Soft Matter ◽  
2021 ◽  
Author(s):  
Guo-Jun Liao ◽  
Sabine H. L. Klapp
Keyword(s):  
Phase Separation ◽  
Brownian Dynamics ◽  
The Self ◽  
Self Organization ◽  
Dipolar Interactions ◽  
Active Particles

Using Brownian dynamics (BD) simulations we investigate the self-organization of a monolayer of chiral active particles with dipolar interactions. Each particle is driven by both, translational and rotational self-propulsion, and...

scholarly journals Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1152
Author(s):  
Tatyana Kirila ◽  
Anna Smirnova ◽  
Alla Razina ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Phase Separation ◽  
Salt Concentration ◽  
Monomer Unit ◽  
Salt Content ◽  
The Self ◽  
Self Organization ◽  
Phase Separation Temperature ◽  
The Core ◽  
Separation Temperature ◽  
Water Salt

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

scholarly journals Group formation and cohesion of active particles with visual perception–dependent motility

Science ◽  
2019 ◽  
Vol 364 (6435) ◽  
pp. 70-74 ◽  
Author(s):  
François A. Lavergne ◽  
Hugo Wendehenne ◽  
Tobias Bäuerle ◽  
Clemens Bechinger
Keyword(s):  
Visual Perception ◽  
Feedback Loop ◽  
Group Formation ◽  
Autonomous Systems ◽  
The Self ◽  
Living Systems ◽  
Self Organization ◽  
Response Threshold ◽  
Active Particles ◽  
Motility Change

Group formation in living systems typically results from a delicate balance of repulsive, aligning, and attractive interactions. We found that a mere motility change of the individuals in response to the visual perception of their peers induces group formation and cohesion. We tested this principle in a real system of active particles whose motilities are controlled by an external feedback loop. For narrow fields of view, individuals gathered into cohesive nonpolarized groups without requiring active reorientations. For wider fields of view, cohesion could be achieved by lowering the response threshold. We expect this motility-induced cohesion mechanism to be relevant not only for the self-organization of living systems, but also for the design of robust and scalable autonomous systems.

scholarly journals Tuning the self-organization of confined active particles by the steepness of the trap

Soft Matter ◽  
2019 ◽  
Vol 15 (43) ◽  
pp. 8865-8878 ◽  
Author(s):  
Shubhashis Rana ◽  
Md. Samsuzzaman ◽  
Arnab Saha
Keyword(s):  
The Self ◽  
Self Organization ◽  
Polar Cluster ◽  
Active Particles

A 2D polar layer of self-propelling and self-aligning particles, rotating along the boundary of a circular trap, becomes a round-shaped polar cluster with hexagonal order when the steepness of the trap-boundary is reduced gradually.

scholarly journals Phase separation of an active colloidal suspension via quorum-sensing

Soft Matter ◽  
2021 ◽  
Author(s):  
Francis Jose ◽  
Shalabh K. Anand ◽  
Sunil P. Singh
Keyword(s):  
Phase Separation ◽  
Quorum Sensing ◽  
Brownian Dynamics ◽  
Local Density ◽  
Colloidal Suspension ◽  
Two Dimensions ◽  
The Self ◽  
Dynamics Simulation ◽  
Brownian Dynamics Simulation

We present the Brownian dynamics simulation of an active colloidal suspension in two dimensions, where the self-propulsion speed of a colloid is regulated according to the local density sensed by it.

scholarly journals From collections of independent, mindless robots to flexible, mobile, and directional superstructures

2021 ◽  
Vol 6 (56) ◽  
pp. eabd0272
Author(s):  
J. F. Boudet ◽  
J. Lintuvuori ◽  
C. Lacouture ◽  
T. Barois ◽  
A. Deblais ◽  
...  
Keyword(s):  
Space Exploration ◽  
External Environment ◽  
The Self ◽  
Simple Function ◽  
Self Organization ◽  
Simple Strategy ◽  
Active Particles ◽  
Directional Motion ◽  
The Individual

A swarm of simple active particles confined in a flexible scaffold is a promising system to make mobile and deformable superstructures. These soft structures can perform tasks that are difficult to carry out for monolithic robots because they can infiltrate narrow spaces, smaller than their size, and move around obstacles. To achieve such tasks, the origin of the forces the superstructures develop, how they can be guided, and the effects of external environment, especially geometry and the presence of obstacles, need to be understood. Here, we report measurements of the forces developed by such superstructures, enclosing a number of mindless active rod-like robots, as well as the forces exerted by these structures to achieve a simple function, crossing a constriction. We relate these forces to the self-organization of the individual entities. Furthermore, and based on a physical understanding of what controls the mobility of these superstructures and the role of geometry in such a process, we devise a simple strategy where the environment can be designed to bias the mobility of the superstructure, giving rise to directional motion. Simple tasks—such as pulling a load, moving through an obstacle course, or cleaning up an arena—are demonstrated. Rudimentary control of the superstructures using light is also proposed. The results are of relevance to the making of robust flexible superstructures with nontrivial space exploration properties out of a swarm of simpler and cheaper robots.

scholarly journals Universality class of the motility-induced critical point in large scale off-lattice simulations of active particles.

Soft Matter ◽  
2021 ◽  
Author(s):  
Claudio Maggi ◽  
Matteo Paoluzzi ◽  
Andrea Crisanti ◽  
Emanuela Zaccarelli ◽  
Nicoletta Gnan
Keyword(s):  
Phase Separation ◽  
Critical Point ◽  
Computer Simulations ◽  
Large Scale ◽  
Universality Class ◽  
Critical Behaviour ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Active Particles ◽  
Two Dimensional Model

We perform large-scale computer simulations of an off-lattice two-dimensional model of active particles undergoing a motility-induced phase separation (MIPS) to investigate the systems critical behaviour close to the critical point...

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