Wet scalp could protect you from lightning, structural colour makes blueberries blue – Physics World

Wet scalp could protect you from lightning, structural colour makes blueberries blue – Physics World

Time Stamp: February 9, 2024 11:20 AM

Lightning
Brilliant idea: researchers have found that wet scalp could protect you if you are struck by lightning. (Courtesy: iStock/WolfeLarry)

While the odds of being struck by lightning is about one in a million, a direct hit can be fatal, especially to the head. So what can you do to protect yourself against such a shocking event? According to researchers in Germany, applying rainwater to the scalp could help. To investigate, they used two model “heads” that contained three layers corresponding to the scalp, skull and brain. One head was sprayed with a weak salt solution to mimic rainwater with the other one kept dry. The two heads were then exposed to ten electrical discharges of 2 kA and 12 kV.

They found that the wet head carried a lower amount of current in the brain layer compared to the dry head and could correspond to a survival rate of 70-90% compared to 30% for a dry head. It struck the researchers that the reason for the lower activity could be that vaporising water helps to reduce the temperature of the skin and directs lightning away from it. They now plan to conduct more research into the effect.

The research is described in Nature.

What colour are blueberries? This might sound like a silly question because they appear to be blue in colour. But, it’s more complicated than that – according to Rox Middleton and colleagues at the UK’s University of Bristol. The team has shown that the blue hue of the popular fruit is a result of structural colour on the skin of the blueberry.

Tiny structures

Structural colour is created by tiny, recurring surface structures that have spacings on par with the wavelength of light. Interference effects at the surface allow some wavelengths of light to be reflected while other wavelengths are not, making the surface appear certain colours. A wide range of living organisms make use of structural colour – including plants, birds, insects and cephalopods.

Now work done by Middleton’s team adds blueberries to that list. The researchers identified a layer of wax on the skin of the fruit that is is made up of randomly arranged crystal structures that scatter blue and UV light. Apparently, the chemical pigments on the skin of the berries are red in colour, but what we see is the blue structural colour from the waxy layer – which is only 2 micron thick.

The team confirmed this by mashing up the wax structures, at which point they ceased to be blue. However, they were able to carefully reconstitute the wax crystals on a substrate, creating a blue-UV coating.

The researchers are now investigating practical ways to create similar coatings with the goal of creating sustainable, biocompatible and even edible UV and blue-reflective paint.

Describing their work in Science Advances, the team also reports similar waxy structures on plums and juniper cones.

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