Greeting. I have noticed a pattern and wonder what is the reason. When ever I have suspension of particles in water droplet, be it bacteria or abiotic they seem to concentrate in the edge of the droplet, resulting in a ring as the water dry. Any idea what is the reason behind this phenomena?
Yoram
If any of you is interested turned out it is a well known phenomena ("The coffee ring effect"). I even found a paper by Deegan et al, Nature 1997. This paper explain that capillary effect in the edge of the drop pull the particles into the edge.
Even more interesting, turned out some bacteria fight this phenomena by producing surfactants.
Deegan et al. 1997:
https://www.researchgate.net/publication/221720307_Capillary_Flow_as_the_Cause_of_Ring_Stains_From_Dried_Liquid_Drops
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