# gst: apropos of transitions, when a liquid droplet takes a turn (as a swimming behavior of amoebas)

Masatoshi Ichikawa and coll.  << have analyzed the conditions that cause self-propelling droplets to take linear or curved trajectories. The team studied water droplets between 60 and 800 μm across as they moved through oil that contained a surfactant. The droplets moved as a result of the Marangoni effect, in which an unequal distribution of surfactant molecules on the surface of each droplet creates a surface-tension gradient. (They) found that larger droplets tended to follow more tightly curved paths than smaller droplets. To understand the cause of this difference, Ichikawa and coll.  created a 3D model describing the concentration of surfactant on the surface of the droplets. They also studied the droplets’ internal flow, by observing the paths of small tracer particles. They characterized this flow as the sum of multiple patterns of fluid motion present in each droplet, including radial, dipolar, and quadrupolar motion. These patterns of motion were determined by the surface-tension gradients created by the uneven surfactant distribution on each droplet. In turn, such patterns controlled how the droplets moved. In particular, the team found that the angular difference between the dipolar and quadrupolar flows within droplets was strongly correlated with more curved droplet trajectories. In larger droplets, this angle changed more easily, causing the tightly curved trajectories. The researchers say that this fundamental mechanism may also influence the swimming behavior of amoebas.  >>️

Sophia Chen. When Liquid Droplets Take a Turn. Physics 14, s109. Aug 19, 2021.

https://physics.aps.org/articles/v14/s109

Saori Suda, Tomoharu Suda, et al. Straight-to-Curvilinear Motion Transition of a Swimming Droplet Caused by the Susceptibility to Fluctuations. Phys. Rev. Lett. 127, 088005. Aug 19, 2021.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.088005

Also

keyword 'drop' | 'droplet' in FonT

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

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

# life: apropos of transitions, a leap from chemistry to biology, the hypothesis of self-assembling droplets, the 'droplet world'.

AA << identify conditions suitable for concurrent peptide generation and self-assembly, and (..) show how a proliferating peptide-based droplet could be created by using synthesised amino acid thioesters as prebiotic monomers. Oligopeptides generated from the monomers spontaneously formed droplets through liquid–liquid phase separation in water. The droplets underwent a steady growth–division cycle by periodic addition of monomers through autocatalytic self-reproduction. Heterogeneous enrichment of RNA and lipids within droplets enabled RNA to protect the droplet from dissolution by lipids. >>

Matsuo, M., Kurihara, K. Proliferating coacervate droplets as the missing link between chemistry and biology in the origins of life. Nat Commun 12, 5487. doi: 10.1038/ s41467-021-25530-6. Sep 24,  2021.

https://www.nature.com/articles/s41467-021-25530-6

<< By constructing peptide droplets that proliferate with feeding on novel amino acid derivatives, we have experimentally elucidated the long-standing mystery of how prebiotic ancestors were able to proliferate and survive by selectively concentrating prebiotic chemicals, (..) Rather than an RNA world, we found that 'droplet world' may be a more accurate description, as our results suggest that droplets became evolvable molecular aggregates—one of which became our common ancestor. >> Muneyuki Matsuo.

Answering a century-old question on the origins of life. Hiroshima University. Sep 27, 2021. 

https://phys.org/news/2021-09-century-old-life.html

Also

keyword 'drop' | 'droplet' in FonT

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

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

keyword 'transition' in FonT

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

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

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

keywords: life, originsoflife, transitions, drop, droplet

# 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

# gst: contactless manipulation of droplets levitating in an acoustic wave

<< A unique, versatile, and material-independent approach to manipulate contactlessly and merge two chemically distinct droplets suspended in an acoustic levitator is reported. Large-amplitude axial oscillations are induced in the top droplet by low-frequency amplitude modulation of the ultrasonic carrier wave, which causes the top sample to merge with the sample in the pressure minimum below. The levitator is enclosed within a pressure-compatible process chamber to enable control of the environmental conditions. The merging technique permits precise control of the substances affecting the chemical reactions, the sample temperature, the volumes of the liquid reactants down to the picoliter range, and the mixing locations in space and time. >>

Stephen J. Brotton, Ralf I. Kaiser. 

Controlled Chemistry via Contactless Manipulation and Merging of Droplets in an Acoustic Levitator. Anal. Chem. 2020, 92, 12, 8371–8377. doi: 10.1021/ acs.analchem.0c00929. Jun 1, 2020. 

https://pubs.acs.org/doi/10.1021/acs.analchem.0c00929#

Levitating droplets allow scientists to perform 'touchless' chemical reactions.  American Chemical Society. Jun 24, 2020.

https://phys.org/news/2020-06-levitating-droplets-scientists-touchless-chemical.html  

# gst: droplets scoot like caterpillars.

<< From swells in an ocean to ripples in a puddle, the shearing effect of wind blowing over a liquid is visible at all scales. This shear determines the interactions between Earth’s atmosphere and its surface water and, researchers now explain, the movement of liquid droplets that crawl up and down the window of a moving car in the rain. In a series of experiments, (AA) show that airflow triggers surface waves that cause such droplets to crawl like caterpillars before they break apart. >>️

<< At first, the airflow across the droplet’s surface caused the droplet to extend into an oval shape. The droplet also began to tilt, with the liquid piling up at the droplet’s downwind edge. When the drag force exerted by the airflow overcame the capillary force between the glycerin and the glass, the droplet began to slide and to stretch out even more. Surface waves then developed on the elongated droplet and traveled toward its leading edge. The waves induced a stable caterpillar-like motion, with the droplet stretching and contracting along its length. Eventually, beyond a threshold length that depended on the droplet’s volume, the caterpillar was no longer able to withstand the shearing force and broke into several droplets. >>️

AA << say that the behavior follows the same pattern as that of an elongated droplet sliding along an incline. >>

️

Rachel Berkowitz. Droplets Scoot Like Caterpillars. Physics 16, s110. Sep 1, 2023.

https://physics.aps.org/articles/v16/s110  

A. Chahine, J. Sebilleau, R. Mathis, D. Legendre. Caterpillar like motion of droplet in a shear flow. Phys. Rev. Fluids 8, 093601. Sep 1, 2023.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.8.093601

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

Keywords: gst, drop, droplet, droploid, bubble, transition

# 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: how to harvest energy from impacting droplets

AA << designed an electrical generator that can harvest energy from impacting droplets and other sources of mechanical energy. (..) The electrical generator can be explained as being a permanently charged capacitor, also known as an electret. >>

They << managed to convert 11.8% of the mechanical energy of an impacting droplet into electrical energy, which is a significant improvement compared to the efficiency of similar devices. Furthermore, they demonstrated that the energy harvesting efficiency does not degrade after 100 days, requiring only a single 15 minute charging cycle before long-term application. >>

K.W. Wesselink. Generator developed for harvesting energy from droplets. 

University of Twente. Jul 8, 2020.

https://phys.org/news/2020-07-harvesting-energy-droplets.html

Hao Wu, Niels Mendel, et al. Charge Trapping‐Based Electricity Generator (CTEG): An Ultrarobust and High Efficiency Nanogenerator for Energy Harvesting from Water Droplets. Advanced Materials. doi: 10.1002/ adma.202001699. July 6, 2020.

https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202001699  

Hao Wu, Niels Mendel, et al. Energy harvesting from drops impacting onto charged surfaces. Phys. Rev. Lett. Jun 25, 2020.

https://journals.aps.org/prl/accepted/ec07bYb0D261277cc08a6414c57b4ce4ab3e8da4f

Also

keyword 'drops' in Font:

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

# gst: dynamics and interactions of multiple bright droplets and bubbles, and interactions of kinks with droplets and with antikinks.

<< Droplets bearing different chemical potentials experience mass-exchange phenomena. Individual bubbles exhibit core expansion and mutual attraction prior to their destabilization. Droplets interacting with kinks are absorbed by them, a process accompanied by the emission of dispersive shock waves and gray solitons. Kink-antikink interactions are repulsive, generating counter-propagating shock waves. >> 

 

G. C. Katsimiga, S. I. Mistakidis, et al. Interactions and dynamics of one-dimensional droplets, bubbles and kinks. arXiv: 2306.07055v2 [cond-mat.quant-gas]. Jul 26, 2023.

https://arxiv.org/abs/2306.07055

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

Keywords: gst, drop, bubble, kink, wave, soliton, homoclinic orbits

# 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: when droplets are capable of self-propulsion as if they were surfing on a self-generated wave.

<< active droplets can move autonomously or oscillate between confining walls (..). Those behaviors could provide a clue about how life emerged from inanimate material. >>️

<< in the past decades, it has become clear that weak physical interactions among biomolecules are a crucial part of the answer. Such interactions allow some molecules to stay together transiently while avoiding others, which can lead to the spontaneous formation of droplets whose composition differs from their surroundings. Although biochemist Alexander Oparin suggested such ideas a century ago (..), experimental corroboration arrived only recently >>️

<< The key contribution of Demarchi and his collaborators is to demonstrate that droplet drift can enhance the heterogeneity of substrate and product. The resulting positive feedback allows droplets to move continuously as if they were surfing on a self-generated wave. >>️

David Zwicker. Droplets Come to Life. Physics 16, 45. Mar 20, 2023. 

https://physics.aps.org/articles/v16/45

AA << find that condensates move toward the center of a confining domain when this feedback is weak. Above a feedback threshold, they exhibit self-propulsion, leading to oscillatory dynamics. Moreover, catalysis-driven enzyme fluxes can lead to interrupted coarsening, resulting in equidistant condensate positioning, and to condensate division. >>

️

Leonardo Demarchi, Andriy Goychuk, et al. Enzyme-Enriched Condensates Show Self-Propulsion, Positioning, and Coexistence. Phys. Rev. Lett. 130, 128401. Mar 20, 2023.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.128401

Also

'drop', 'droplet', 'droploid', 'transition' in 

https://www.inkgmr.net/kwrds.html

Keywords: gst, drop, droplet, waves, transition, liquid-liquid phase transition, nonequilibrium systems

# gst: apropos of weird transitions: from non-equilibrium conditions square droplets and liquid lattices can emerge.

<< Spontaneous emergence of organized states in materials driven by non-equilibrium conditions is of notable fundamental and technological interest. In many cases, the states are complex, and their emergence is challenging to predict. Here, (AA) show that an unexpectedly diverse collection of dissipative organized states emerges in a simple system of two liquids under planar confinement when driven by electrohydrodynamic shearing.

At low shearing, a symmetry breaking at the liquid-liquid interface leads to a one-dimensional corrugation pattern. 

At slightly stronger shearing, topological changes give raise to the emergence of Quincke rolling filaments, filament networks, and two-dimensional bicontinuous fluidic lattices. 

At strong shearing, the system transitions into dissipating polygonal, toroidal, and active droplets that form dilute gas-like states at low densities and complex active emulsions at higher densities. >>

Geet Raju, Nikos Kyriakopoulos, Jaakko V. I. Timonen. Diversity of non-equilibrium patterns and emergence of activity in confined electrohydrodynamically driven liquids. Science  Advances. Vol 7, Issue 38. doi: 10.1126/ sciadv.abh1642. 15 Sep 15, 2021.

https://www.science.org/doi/10.1126/sciadv.abh1642

<< Things in equilibrium tend to be quite boring, (..) It's fascinating to drive systems out of equilibrium and see if the non-equilibrium structures can be controlled or be useful. Biological life itself is a good example of truly complex behavior in a bunch of molecules that are out of thermodynamic equilibrium. >>  Jaakko Timonen.

Physicists make square droplets and liquid lattices. Aalto University. Sep 15, 2021. 

https://phys.org/news/2021-09-physicists-square-droplets-liquid-lattices.html

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, drop, droplet, lattice, transition, out of equilibrium.

# 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: apropos of modulational instabilities, the case of vortex-ring quantum droplets in a radially-periodic potential.

FIG. 11: (Color online) Typical examples of stable nested patterns with soliton and vortex QDs (quantum droplets)  which were created in adjacent radial troughs. In panels (a1-b4) the pattern was created from the initial dynamical states with parameters (N,S,On) = (46,0,2) and (N,S,On) = (35,1,1) in the outer and inner troughs, respectively. In panels (c1-d4) the input was taken with parameter sets (N,S,On) = (120,1,3) and (N,S,On) = (46,0,2) in the outer and inner troughs.

AA << establish stability and characteristics of two-dimensional (2D) vortex ring-shaped quantum droplets (QDs) formed by binary Bose-Einstein condensates. >>️

<< another noteworthy option is to construct a two-ring complex in which one vortex-ring component is subject to the MI  (modulational instability), hence it is replaced by an azimuthal soliton (or maybe several solitons), (..), while the vortex component trapped in another potential trough avoids the azimuthal MI and remains essentially axisymmetric. >>️

<< Examples of such heterogeneous robust states, produced by simulations of Eq. (3), are displayed in Fig. 11. Panels 11(a1-b4) show a complex in which the MI takes place in the outer circular trough, producing an azimuthal soliton which performs rotary motion, while the inner vortex ring is  modulationally stable. An opposite example is produced in Figs. 11(c1-d4), where the outer vortex ring remains stable against azimuthal perturbations, while the MI creates a soliton exhibiting the rotary motion in the embedded (inner) circular trough. The rotation direction of the soliton is driven by the vorticity sign of the underlying QD (quantum droplet). It is relevant to mention that the multi-ring potential considered here holds different vortex-ring or azimuthal-soliton states nearly isolating them from each other. (..) An additional problem, which is left for subsequent analysis, is interplay between adjacent radial modes in the case when the separation between the adjacent rings is essentially smaller. >>️

Bin Liu, Yi xi Chen, et al. Vortex-ring quantum droplets in a radially-periodic potential. arXiv: 2212.05838v1 [nlin.PS]. Dec 12, 2022.

https://arxiv.org/abs/2212.05838

Also

keyword 'drop' | 'droplet' | 'droploids' in FonT

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

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

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

keyword 'goccia' in Notes 

(quasi-stochastic poetry): 

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

keyword 'instability' | 'instabilities' in FonT

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

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

keyword 'instabile' in Notes 

(quasi-stochastic poetry)

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

Keywords: gst, drop, droplet, vortex, vortices, vortexes, vorticity, instability,  modulational instabilities

# life: to save Western lifestyle from a catapulting collapse (caused by one or two Wuhan "achoo") use a techno mask (e.g. "cowboy" or "burqa" techno masks)

<< WHEN YOU LOOK at photos of Americans during the 1918 influenza pandemic, one feature stands out above all else: masks.  (..)  Newspapers published instructions for sewing masks at home. >>

<< After the 1918 pandemic, the prophylactic use of masks among the general public largely fell out of favor in America and much of the West. The US Centers for Disease Control and Prevention has almost never advised healthy people to wear masks in public to prevent influenza or other respiratory diseases. In the past few months, with medical supplies dangerously diminished, the CDC, US surgeon general Jerome Adams, and the World Health Organization have urged people not to buy masks, paradoxically claiming that masks are both essential for the safety of health care workers and incapable of protecting the public from Covid-19. >>

<< Recently, some experts have disputed this contradictory advice. They propose that widespread use of masks is one of the many reasons why China, Japan, South Korea, and Taiwan have controlled outbreaks of coronavirus much more effectively than the US and Europe. "Of course masks work," sociologist Zeynep Tufekci wrote in a New York Times editorial. "Their use has always been advised as part of the standard response to being around infected people." Public health expert Shan Soe-Lin and epidemiologist Robert Hecht made a similar argument in the Boston Globe (..) Last week, George Gao, director-general of the Chinese Center for Disease Control and Prevention, said that America and Europe are making a "big mistake" by not telling the public to wear masks during the ongoing pandemic. >>

<< N95s (N95 mask) are so-named because they filter out 95 percent of particles with a diameter of 0.3 microns, (..) Particles 0.3 microns wide are just the right size to ride a stream of air through a filter’s fibrous maze, but it is still possible to thwart them with enough twists and turns.>>

<< the bacterium that causes anthrax is 0.8 microns wide and 1.4 microns long, whereas influenza viruses and coronaviruses are usually between 0.08 and 0.12 microns. But microbes expelled from someone’s respiratory tract are rarely naked: the droplets they travel in range in size from 0.6 to more than 1,000 microns. >>

<< Although surgical masks are not tightly sealed like N95s, the filters they contain are still a major impediment to microbes. The CDC and other health agencies often say that surgical masks catch only spurts of bodily fluids and very large respiratory droplets, and that they cannot filter tiny infectious particles. But this is simply not true. >>

<< Because so many trials find only a marginal benefit or none at all, some health agencies have decided against recommending masks to the general public. But the inconsistency of randomized trials does not negate the robust physical evidence that masks block respiratory droplets and microbes.  >>

<< "To be honest, it’s common sense," says Tang (virologist Julian Tang). "If you put something in front of your face, it’s going to help more than not." If enough people wear masks at least somewhat correctly at least some of the time, the overall benefits could be dramatic. A 2011 review of high-quality studies found that among all physical interventions used against respiratory viruses-including handwashing, gloves, and social distancing-masks performed best, although a combination of strategies was still optimal. >>

It's Time to Face Facts, America: Masks Work. Official advice has been confusing, but the science isn't hard to grok. Everyone should cover up. Wired. Ideas. March 30, 2020.

https://www.wired.com/story/its-time-to-face-facts-america-masks-work/

Also 

a funky, immediate approach of the sneezing from Wuhan (a relative safe barrier - this device is NOT a filter) FonT.  Mar 20, 2020

https://flashontrack.blogspot.com/2020/03/life-funky-immediate-approach-of.html

Also

climate change plus Zika, then a behavioral transition, hat burqa- like everywhere ... FonT.  Mar13, 2016.

https://flashontrack.blogspot.com/2016/03/s-epidemiol-climate-change-plus-zika.html

Also

keyword 'virus' in FonT

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

keyword 'virus' in Notes (quasi- stochastic poetry)

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

keyword 'snake' in FonT

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

keyword 'bat' in FonT

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

# gst: apropos of the variety in the ways liquid jets break up

<< When a liquid exits a nozzle and encounters something it cannot immediately mix into—a gas, for example—it forms a cylinder. Quickly, small surface perturbations and various forces cause the liquid tube to break apart into droplets. The entire cylinder either pinches off into droplets one at a time at the tip, takes on a wavy or corkscrew-like structure, or atomizes into a fine spray. >> 

<< Our results show that the gas and liquid flows are equally important in the interface region, an idea neglected by most other studies, (Nathan Speirs).  The irregular shapes of the droplets formed are quite interesting as well, (Kenneth Langley) >> 

<< There's so much variety in the ways liquid jets break up. (Nathan Speirs) >>  

King Abdullah. Slippery superfluids push jets to breaking point. University of Science and Technology. Aug 31, 2020. 

https://phys.org/news/2020-08-slippery-superfluids-jets.html 

<< Past studies have shown that liquid jet breakup behavior can be classified into five regimes: Rayleigh, first wind, sinuous, second wind, and atomization. By experimentally examining the breakup of superfluid and normal liquid 4^He in an atmosphere of its own vapor, (AA) investigate the evolution of the jet behavior >>

N. B. Speirs, K. R. Langley, et al. Jet breakup in superfluid and normal liquid  4^He. Phys. Rev. Fluids 5, 044001. Apr 2, 2020.

https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.5.044001    

# gst: compression and fracture of ordered and disordered droplet rafts

AA << simulate a two-dimensional array of droplets being compressed between two walls. The droplets are adhesive due to an attractive depletion force. As one wall moves toward the other, the droplet array is compressed and eventually induced to rearrange. The rearrangement occurs via a fracture, where depletion bonds are quickly broken between a subset of droplets. >>

<< For monodisperse, hexagonally ordered droplet arrays, this fracture is preceded by a maximum force exerted on the walls, which drops rapidly after the fracture occurs. >>

<< In small droplet arrays a fracture is a single well-defined event, but for larger droplet arrays, competing fractures can be observed. These are fractures nucleated nearly simultaneously in different locations. >>

AA << also study the compression of bidisperse droplet arrays. The addition of a second droplet size further disrupts fracture events, showing differences between ideal crystalline arrays, crystalline arrays with a small number of defects, and fully amorphous arrays. >>

️

Pablo Eduardo Illing, Jean-Christophe Ono-dit-Biot, et al. Compression and fracture of ordered and disordered droplet rafts. Phys. Rev. E 109, 014610. Jan 17, 2024.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.109.014610

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

Also:  raft   https://flashontrack.blogspot.com/search?q=raft  

zattera (quasi-stochastic poetry) https://inkpi.blogspot.com/2005/04/1864-onda-di-liberazione.html  

randa (quasi-stochastic poetry) https://inkpi.blogspot.com/search?q=randa

Keywords: gst, drop, droplet, raft, defect, fracture, crack

# gst: soft entities; strange randomly flying of droplets across surfaces, to condense ...

<< when researchers took a look at the newest method of condensation, they saw something strange: When a special type of surface is covered in a thin layer of oil, condensed water droplets seemed to be randomly flying across the surface at high velocities, merging with larger droplets, in patterns not caused by gravity. >>

Brandie Jefferson. Solving a condensation mystery. Washington University in St. Louis. Jun 25, 2019.

https://m.phys.org/news/2019-06-condensation-mystery.html

Jianxing Suna, Patricia B. Weisensee. Microdroplet self-propulsion during dropwise condensation on lubricant-infused surfaces. Soft Matter. 2019,15, 4808-4817. doi: 10.1039/C9SM00493A. May 8, 2019.

https://pubs.rsc.org/en/content/articlelanding/2019/SM/C9SM00493A#!divAbstract  

Also

Anomalous formation of molecules after vapor deposition. Dec 31, 2015.

http://flashontrack.blogspot.com/2015/12/rmx-s-gst-anomalous-formation-of.html

# gst: interface mobility enhances the bounce effect of bubbles

<< Theoretically, when a bubble reaches the surface of a pure liquid, the thin film of liquid between the bubble and the air above should quickly drain away, allowing the bubble to coalesce with the air. The same would be expected when two bubbles meet within the liquid or when two droplets of oil come together in water.  >>

<< Counterintuitively, bubbles or droplets reaching the highly mobile fluorocarbon liquid-air interface bounced off of the interface much more strongly than from the immobilized interface. The reason is that there is less friction on the mobile interface and thus less energy is lost during the bounce. "To our knowledge, our studies and simulations are the first to demonstrate an enhanced bounce effect due to interface mobility," >> Ivan U. Vakarelski.

When bubbles bounce back.  King Abdullah University of Science and Technology. Nov 13, 2019.

https://m.phys.org/news/2019-11-when-bubbles-bounce-back.html

Ivan U. Vakarelski, Fan Yang, et al. 

Mobile-surface bubbles and droplets coalesce faster but bounce stronger. Science Advances  25 Oct 2019:

Vol. 5, no. 10, eaaw4292 DOI: 10.1126/sciadv.aaw4292 

https://advances.sciencemag.org/content/5/10/eaaw4292

# 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: the auto assembly of a drop (from thermal capillary waves)

<< after single or multiple bridges form due to the presence of thermal capillary waves, the bridge growth commences in a thermal regime. Here, the bridges expand linearly in time much faster than the viscous-capillary speed due to collective molecular jumps near the bridge fronts. Transition to the classical hydrodynamic regime only occurs once the bridge radius exceeds a thermal length scale l_(T) ~ sqrt(Radius). >>

Sreehari Perumanath, Matthew K. Borg, et al. Droplet Coalescence is Initiated by Thermal Motion. Phys. Rev. Lett. 122, 104501 Mar 13, 2019.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.104501

Supercomputer sheds light on how droplets merge. University of Edinburgh. Mar 20, 2019.

https://m.phys.org/news/2019-03-supercomputer-droplets-merge.html