Do you know what is the freezing temperature of water? are you sure?

At some point in your elementary school (1st grade, if you’re a bit more experienced…), you learned that the freezing point of water is 0 degrees Celsius. If you haven’t learned, you don’t know ProblemBecause the time has come to forget same. That’s because the new study brings in a much smaller margin than that.

By creating ice from tiny droplets the size of a few hundred molecules, the researchers were able to lower the freezing point of water more than ever before.

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And how important is it to know how and why water turns to ice? According to scientists, this information is necessary to understand a wide range of natural processes. Climate variability, cloud dynamics, and the water cycle, for example, are all affected by the solidification of water.

Even animals that live in frigid conditions need to know and use this knowledge. Wood frogs, for example, survive the winter on land by freezing their bodies. This allows them to get out of Hibernation Faster than the species that survives the winter under water without freezing.

However, ice crystals can break cell membranes, so animals using this technique need to find a way to prevent ice from forming in their cells and tissues. A better understanding of how water freezes is important not only to the pet itself, but can also lead to a greater awareness of humans about these extreme species.

Is the freezing point of water relative?

While the rule of thumb is that water freezes at 0 degrees Celsius, in fact it can sometimes remain liquid over cold temperatures. Until now, it was believed that this time period stops at a temperature of minus 38 degrees Celsius. That is, any temperature below that, and the water freezes.

Now, in the latest study published in the journal Nature CommunicationsThe researchers were able to keep the water droplets inside liquid status It reaches minus 44 degrees Celsius.

They started with droplets ranging from 150 nanometers, which is barely larger than a virus particle, to 2 nanometers, a group of just 275 water molecules. This diversity in droplet sizes helped researchers discover the role of size in turning water into ice.

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“We’re covering all of these ranges so we can understand the conditions under which the ice will form — what temperature, what size droplets,” study co-author Hadi Ghasemi, a professor of mechanical engineering at the University of Houston, told Live Science. . “Importantly, we found that if the water droplets were covered with some soft material, the freezing temperature could be brought down to a very low temperature.”

As a soft material, octane was used, an oil that envelops each drop within the nanopores of an oxidized aluminum oxide membrane. This caused the droplets to take on a more rounded shape and greater pressure, which scientists believe is needed to prevent ice from forming at these low temperatures.

The smaller the water droplet, the lower the temperature

Since it is virtually impossible to observe the freezing process at such small scales, the researchers used measurements of electrical conductivity — since ice is more conductive than water — and emitted light in the infrared spectrum to capture the exact moment and temperature at which the droplets turned water into ice.

They found that the smaller the droplet, the cooler the ice should be—and for droplets 10 nanometers in diameter or smaller, the rate of ice formation decreased dramatically. In the smallest droplets they measured, ice did not form until the water’s temperature reached minus 44 degrees Celsius.

Does this mean that microscopic droplets inside clouds and biological cells can get colder than we thought? “As a scientist, I’d say we don’t know yet,” Ghasemi said. “But this discovery could mean big things to prevent ice in man-made materials such as those in aviation and energy systems.”

If water on soft surfaces takes longer to freeze, engineers can incorporate a mixture of soft and hard materials into their designs to prevent ice build-up on those surfaces. “There are many ways to use this knowledge in designing surfaces to prevent ice formation,” Ghasemi said. “Once we have this basic understanding, the next step is just to engineer these surfaces based on the soft materials.”

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