(ORDO NEWS) — Biologists have figured out how leaves survive icing. This was reported by the press service of the University of Kiel.
“We could show that fine hairs, the so-called trichomes, or the waxy layer on the leaves, are a good way to prevent or mitigate icing,” the scientists say.
To study the interaction between ice and leaves, the authors used a cryoelectron microscope. Before such a study, the samples are not dried, but quickly frozen.
Due to this, they are deprived of liquid water and become suitable for research in a vacuum chamber.
At the same time, their structure is well preserved, which makes it possible to study them almost in their original form.
So the scientists froze the leaves by briefly immersing them in liquid nitrogen at minus 196 degrees and were able to isolate several defense mechanisms.
The leaves of plants with trichomes, such as those of the daisy (Bellis perennis), are usually hydrophilic.
Therefore, ice crystals first form at their tips, and as soon as the temperature rises again, they also melt quickly. The main surface of the sheet remains free of ice and undamaged.
On the other hand, leaf surfaces covered with three-dimensional nanoscale waxy protrusions, as in some species of tulips (Tulipa gesneriana), are superhydrophobic.
Drops of water roll off them, this is especially noticeable on the example of lotuses.
Ice crystals can form here only if the water is stopped by defects in the wax layer, but even in this case, the sheet will remain intact: the wax will take damage.
The authors hope that the study of these natural mechanisms will make it possible to create artificial anti-icing surfaces that do not require reagents.
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