# gst: rearrangements of a jammed 2-D emulsion (during slow compression).

<< As amorphous materials get jammed, both geometric and dynamic heterogeneity are observed. (AA)  investigate the correlation between the local geometric heterogeneity and local rearrangements in a slowly compressed bidisperse quasi-two-dimensional emulsion system. The compression is driven by evaporation of the continuous phase. >>

<< droplets in heterogeneous local regions are more likely to have local rearrangements. These rearrangements are generally T1 events where two droplets converge toward a void, and two droplets move away from the void to make room for the converging droplets. Thus, the presence of the voids tends to orient the T1 events. >>️

<< The presence of a correlation between the structural quantities and the rearrangement dynamics remains qualitatively unchanged over the entire range of packing fractions observed. >>️

Xin Du, Eric R. Weeks. Rearrangements during slow compression of a jammed  two-dimensional emulsion. Phys. Rev. E 109, 034605. Mar 20,  2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.034605

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

Keywords: drops, droplets, droploids 

# gst: ️apropos of spontaneous active matter, the active droploids.

<< Active matter comprises self-driven units, such as bacteria and synthetic microswimmers, that can spontaneously form complex patterns and assemble into functional microdevices. These processes are possible thanks to the out-of-equilibrium nature of active-matter systems, fueled by a one-way free-energy flow from the environment into the system. Here, (AA) take the next step in the evolution of active matter by realizing a two-way coupling between active particles and their environment, where active particles act back on the environment giving rise to the formation of superstructures. >>️

<< These structures hinge on mutually coupled structure formation processes of the colloids, which form an engine, and the surrounding solvent, which phase separates in regions of high colloidal density and encapsulates the engine within a droplet shell.  >>

️

Jens Grauer, Falko Schmidt, et al. Active droploids. arXiv:2109.10677v1 [cond-mat.soft]. Sep 22, 2021.

https://arxiv.org/abs/2109.10677

Also

keyword 'drop' | 'droplet' in FonT

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

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

keyword 'goccia' in Notes (quasi-stochastic poetry): 

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

keywords: gst, drops, droplets, colloids, active matter, active droploids, self-assembly, solitons.

# gst: apropos of (multitudes) of transitional droplets, when a liquid film collapses in a foam ...

<< Foams have unique properties that distinguish them from ordinary liquids and gases, and are ubiquitously observed in nature, both in biological systems and industrial products. >>

️

<< Once a crack appears near the border and a collapse front is formed, (AA) find that the curvature of the front reverses as it migrates, followed by the emergence and emission of droplets. (they) elucidate the origins of this behavior and discuss the stability of foams, establishing how the characteristic time scales of the process relate to each other. >>️

Naoya Yanagisawa, Marie Tani, Rei Kurita. Dynamics and mechanism of liquid film collapse in a foam. Soft Matter. 17, 1738-1745. Feb 17, 2021.

https://pubs.rsc.org/en/content/articlelanding/2021/SM/D0SM02153A#

Also

keyword 'foam' in FonT

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

keyword 'collapse' in FonT

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

keyword 'schiuma' in Notes

(quasi-stochastic poetry)

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

# gst: when and how a levitating droplet sings (as a pipe)

<< Sprinkle water onto a very hot pan, and you may notice that the droplets evaporate surprisingly slowly. They stick around because of what’s called the Leidenfrost effect—a thin layer of vapor forms between the droplets and the hot surface, insulating them from the heat, and keeping them from boiling off immediately. (..) droplets of water in this Leidenfrost regime emit periodic sounds, or beats.  >>️

<< While emitting sounds, the droplets oscillated as pulsing stars whose points moved radially in and out. (..) this vapor-layer frequency matched the period of the beats, and (AA) therefore concluded that vapor escaping from beneath the droplet was responsible for producing the periodic sounds. >>️

<< the frequency of the sounds made by a droplet depended on the droplet’s size—following the model of an organ pipe, whose tone depends on the velocity of sound and the length of the pipe. This implies that the sound production mechanism in a Leidenfrost droplet is similar to that of a wind instrument. >>

️

Erika K. Carlson. The Sounds of Levitating Water Droplets. Physics 13, s148. Nov 19, 2020.

https://physics.aps.org/articles/v13/s148

Tanu Singla,  Marco Rivera. Sounds of Leidenfrost drops. Phys. Rev. Fluids 5, 113604. doi: 10.1103/ PhysRevFluids.5.113604. Nov 19, 2020.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.5.113604

img     https://physics.aps.org/assets/73455c27-7d24-443b-a685-de931db74e09/e148_1.png

# gst: active drops: from steady to chaotic self-propulsion

<< Individual chemically active drops suspended in a surfactant solution were observed to self-propel spontaneously with straight, helical, or chaotic trajectories. (..) strong advection (e.g., large droplet size) may destabilize a steadily self-propelling drop; once destabilized, the droplet spontaneously stops and a symmetric extensile flow emerges. If advection is strengthened even further in comparison with molecular diffusion, the droplet may perform chaotic oscillations. >>

Matvey Morozov, Sebastien Michelin. Nonlinear dynamics of a chemically-active drop: From steady to chaotic self-propulsion. J. Chem. Phys. 150, 044110 (2019). doi: 10.1063/1.5080539. Jan 31, 2019.  https://aip.scitation.org/doi/10.1063/1.5080539

# chem: acoustic levitation techniques to perform chemistry in floating droplets

<<  Beauchamp (Jack Beauchamp) is doing work in what he calls "lab-in-a-drop" chemistry, in which chemical reactions are performed within a drop of liquid suspended in midair through acoustic levitation. >>

Performing chemistry in floating droplets. California Institute of Technology. Jul 29, 2019.

https://m.phys.org/news/2019-07-chemistry-droplets.html  

Chaonan Mu, Jie Wang, et al. Mass Spectrometric Study of Acoustically Levitated Droplets Illuminates Molecular‐Level Mechanism of Photodynamic Therapy for Cancer involving Lipid Oxidation. Angewandte Chemie International Edition. Volume 58, Issue 24. doi: 10.1002/anie.201902815. Apr 23, 2019.

https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201902815 

# gst: the intermittent dance of liquid droplets

<< Liquid droplets bouncing on a vibrating liquid surface can execute a surprising cycle, alternating between moving and standing still. >>

Focus: Video—Stop and Go Droplets.
July 12, 2019• Physics 12, 80.    https://physics.aps.org/articles/v12/80    

Rahil N. Valani, Anja C. Slim, and Tapio Simula. Superwalking Droplets.
Phys. Rev. Lett. 123, 024503 – Published 12 July 2019.   https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.024503  

Also

"droplets". In FonT.   https://flashontrack.blogspot.com/search?q=droplets