# gst: switching from active Brownian motion to stationary rotation of Janus particles in a viscoelastic fluid.

<< Swimming micro-objects exist in viscoelastic fluids. Elucidating the effect of viscoelasticity on the motion of these objects is important for understanding their behavior. >>

AA << examined the motion of Janus particles self-propelled by induced charge electrophoresis over a wide range of speeds in semidilute polymer solutions. In (Their) system, the motion of Janus particles changed from active Brownian motion to stationary rotation as the speed increased. The torque for stationary rotation originates from the difference between the direction of self-propulsion and that of the time-delayed restoring force from the polymer solution, which has been reported in another self-propelled particle system. The switch from active Brownian motion to stationary rotation at different polymer concentrations can be explained by the Weisenberg number, which is defined as the ratio of the relaxation time of the polymer network to the travel time of the Janus particle to its size. >>

Keita Saito, Ryunosuke Kawano, et al. Self-propelled motion of induced-charge electrophoretic Janus particles in viscoelastic fluids. Phys. Rev. E 111, 045409. Apr 10, 2025.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.111.045409

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Also: Janus, transition, particle, in FonT:

Janus https://flashontrack.blogspot.com/search?q=janus 

transition https://flashontrack.blogspot.com/search?q=transition 

particle https://flashontrack.blogspot.com/search?q=particle

Keywords: gst, Janus, transitions, particles, self-propelled particles

# gst: traveling strings of active dipolar colloids.

AA << study an intriguing new type of self-assembled active colloidal polymer system in 3D. It is obtained from a suspension of Janus particles in an electric field that induces parallel dipoles in the particles as well as self-propulsion in the plane perpendicular to the field. >>

<< At low volume fractions, in experiment, the particles self-assemble into 3D columns that are self-propelled in 2D. Explicit numerical simulations combining dipolar interactions and active self-propulsion find an activity dependent transition to a string phase by increasing dipole strength. >>

AA << classify the collective dynamics of strings as a function of rotational and translational diffusion. (..) (They) also discover long range correlations of the fluctuations along the string contour that grow with the active persistence time, a purely active effect that disappears in the thermal limit. >>

Xichen Chao, Katherine Skipper, et al. Traveling Strings of Active Dipolar Colloids. Phys. Rev. Lett. 134, 018302. Jan 6, 2025. 

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.018302

Also: particle, colloids, self-assembly, transition, in https://www.inkgmr.net/kwrds.html 

Keywords: gst, particle, colloids, self-assembly, Janus, polymers, strings, transition

# game: flocking by turning away.

<< Flocking, as paradigmatically exemplified by birds, is the coherent collective motion of active agents. As originally conceived, flocking emerges through alignment interactions between the agents. >>️

AA << report that flocking can also emerge through interactions that turn agents away from each other. >>

<< Whereas repulsion often leads to motility-induced phase separation of active particles, here it combines with turn-away torques to produce flocking. Therefore, (AA) findings bridge the classes of aligning and nonaligning active matter. (Their) results could help to reconcile the observations that cells can flock despite turning away from each other via contact inhibition of locomotion.  >>️

AA << work shows that flocking is a very robust phenomenon that arises even when the orientational interactions would seem to prevent it. >>️

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Suchismita Das, Matteo Ciarchi, Ziqi Zhou, Jing Yan, Jie Zhang, Ricard Alert. Flocking by Turning Away. Phys. Rev. X 14, 031008. Jul 12, 2024.

https://journals.aps.org/prx/abstract/10.1103/PhysRevX.14.031008

Also: Janus, in FonT 

https://flashontrack.blogspot.com/search?q=janus 

Also: game, flock, in https://www.inkgmr.net/kwrds.html 

Keywords: game, flock, Janus

FonT: an approach of this type could hypothetically generate intriguing, bizarre, unexpected game scenarios in various other contexts ...

# gst: breakup of Janus droplet in a bifurcating microchannel

<< Droplet breakup is frequently observed in natural and industrial processes (..)  Although valuable insights on the breakup mechanisms of single-phase droplets in microchannels have been provided over the past decades, the breakup physics of complex emulsions is still poorly understood. >>️

<< Spatially asymmetric Janus microdroplets, distinct from single-phase or double emulsion droplets possessing one uniform interface with the ambient phase, are anticipated to show unique breakup behaviors, which has not been explored.  >>️

AA << conduct both microfluidic experiments and three-dimensional lattice Boltzmann simulations to investigate the dynamic breakup of ionic liquid (IL)-water Janus droplets in an assembled 3D-printed microchannel with a bifurcation. >>️

<< Three different flow regimes are identified: (i) division into two daughter Janus droplets, (ii) breakup into a single-phase droplet and a smaller Janus droplet, and (iii) nonbreakup.  >>️

AA << find that the strong constraint effect of the main channel and large Ca_av (average capillary numbers) values are essential to the symmetrical breakup of Janus droplets. The tunnel between the mother droplet and the wall of the main channel, which allows the lateral shift of the Janus droplet, and moderate flow rates facilitate the breakup of the IL single-phase portion of Janus droplets.  >>

<< Through 90° rotation of the splitting microchannel, (AA) elucidate the distinctions in Janus droplet behaviors under two baffle orientations. Potential impacts of the oblique flow characteristic of [bmim]⁢Fe⁢Cl4-water Janus droplets on the droplet breakup are discussed. >>️

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Hao Wang, Shiteng Wang, et al. Dynamic breakup of Janus droplet in a bifurcating microchannel. Phys. Rev. Fluids 9, 064203. Jun 11, 2024. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.064203 

Also: 'Janus' in FonT https://flashontrack.blogspot.com/search?q=janus

Also: 'drop', 'droplet', 'droploid', in https://www.inkgmr.net/kwrds.html 

Keywords: gst, Janus, drop, droplet, droploid

# gst: exotic geometries, a Janus trefoil knot, which rotates as it swims forwards.

AA << present an asymptotic theory for solving the dynamics of slender autophoretic loops and knots. >>️

They << elucidate the behavior of many exotic active particle geometries, such as a bumpy uniformly active torus that spins and a Janus trefoil knot, which rotates as it swims forwards. >>️

Panayiota Katsamba, Matthew D. Butler, et al. Slender phoretic loops and knots. Phys. Rev. Fluids 9, 054201. May 10, 2024. 

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.9.054201

Also: keywords janus, knots, particle, in FonT

https://flashontrack.blogspot.com/search?q=janus 

https://flashontrack.blogspot.com/search?q=knots 

https://flashontrack.blogspot.com/search?q=particle

https://flashontrack.blogspot.com/search?q=quasiparticle 

Keywords: janus, loops & knots, particles

# life: mimesis, ambiguity, noise, when an entity is master of disguise.

<< At every stage in their lives, from egg to adult, leaf and stick insects prove to be prey that can trick their predators. >>️

Allie Yang. These insects are masters of disguise—even before hatching. nationalgeographic.com. Oct 17, 2023.

https://www.nationalgeographic.com/animals/article/phasmids-stick-leaf-insects-eggs-camouflouge

Also: mimesis, in Notes (quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=mimesi

https://inkpi.blogspot.com/search?q=mimetico

Also: noise, metamorphosis, in https://www.inkgmr.net/kwrds.html

Keywords: mimesis, disguise, ambiguity, noise, metamorphosis, two-faced Janus

# gst: tuning of Janus particles under flows

<< Active colloidal systems with nonequilibrium self-organization constitute a long-standing, challenging area in material sciences and biology. To understand how hydrodynamic flow may be used to actively control self-assembly of Janus particles (JPs), (AA)  developed a model for the many-body hydrodynamics of amphiphilic JPs suspended in a viscous fluid with imposed far-field background flows. >>

They << alter the hydrophobic distribution on the JP-solvent interface to investigate the hydrodynamics that underlies the various morphologies and rheological properties of the JP assembly in the suspension. (They) find that JPs assemble into unilamellar, multilamellar, and striated structures. >>

AA << characterize the effective material properties of the JP structures and find that the unilamellar structure increases orientation order under shear flow, the multilamellar structure behaves as a shear thinning fluid, and the striated structure possesses a yield stress. >> ️

Szu-Pei Fu, Rolf Ryham, Bryan Quaife, and Y.-N. Young. Effects of tunable hydrophobicity on the collective hydrodynamics of Janus particles under flows. Phys. Rev. Fluids 8, 050501. May 11, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.050501

Also: Janus, in FonT:  https://flashontrack.blogspot.com/search?q=janus

Also: particle, self-assembly, in: https://www.inkgmr.net/kwrds.html

Keywords: particles, Janus, Janus particles, self-organization, self-assembly

# gst: apropos of transitions, reversing order-disorder of Janus nano particles confined in two dimensions

<< Janus particles with different patch sizes, confined to two dimensions, generate a series of patterns of interest to the field of nanoscience >>

AA << observe reverse melting, where for some densities the system melts under cooling. For a broad range of hydrophobic patch sizes (..), a reentrant transition from solid to liquid and then to an ordered phase emerges as temperature (T) decreases due to the formation of rhombus chains at low T.  This reentrant phase has pseudo long-range orientational order but short-range translational order, >>

The << work provides guidelines to study the melting and assembly of Janus particles in two dimensions, as well as mechanisms to generate phases with specific symmetry. >>️️

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Yihao Liang, Boran Ma, Monica Olvera de la Cruz. Reverse order-disorder transition of Janus particles confined in two dimensions. Phys. Rev. E 103, 062607. Jun 9, 2021.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.103.062607

Also

keyword 'nano' in FonT

https://flashontrack.blogspot.com/search?q=nano

keyword 'nano' in Notes 

(quasi-stochastic poetry)

https://inkpi.blogspot.com/search?q=nano