HOW TO TAME COLD
People do not like extremes. Over the years a strong disregard for such extremes like “too bright” and “too dark”, “too smart” or “very stupid” has formed in men’s minds. People understood that among those qualities there is no “good and bad”; on the contrary, from the rational point of view, the golden mean between those is ideal in most cases.
Same is for hot and cold: people tend to eat warm food, live in warm conditions far from extreme heat or absolute zero. But let’s face the truth: More than 80 percent of the habitats on Earth are colder than 5 °C. And Finland, especially in winter conditions, is not an exception! Still, talking about living organisms in general, there is no shortage of species which are not that fastidious as human beings, that’s why scientists state: cold is not always a damaging phenomenon causing fragility. It can bring a positive effect on Earth environment, and Cryotechnologies are here to demonstrate it.
Why is cold considered to be dangerous? The answer is primitive: it destroys the organism. Get below 5 °C, and enzymes slow down their work almost critically. Metabolism and delivery of valuable nutrients almost stops. Below zero, ice crystals start to form in and around cells, sucking water out of them and cutting their membranes and contents to shreds. Matters and tissues suffer a lot.
But how do living organisms survive in cryo conditions? Is there anything we could inherit from them?
Top-7 creatures surviving in cold:
7. Painted turtle hatchlings
6. Wood frog
5. Red flat bark beetles
4. Upis beetles
3. Arctic ground squirrels
2. Arctic woolly bear moths (are the oldest-living caterpillars)
1. Tardigrades (water bears)
Let’s analyze this list now. For once, even microbes don’t come out on top: they stop growing at around -15°C. Surprisingly, more complex animals beat this record, employing an array of tricks to survive the freeze.
Amongst all the mammals, Arctic ground squirrels have the record of super-cooling their bodies below its freezing point, down to -2.9 °C. Of course, they do accumulate fat, change their fur for the winter season and hibernate, while the outside temperature drops down to -25 °C.
Freeze-tolerant animals, like cold-blooded reptiles and amphibians, have two major tricks up their sleeves. The first is to build up “antifreeze” chemicals in their bodies, for example, glycerol, which as any other alcohol can lower the freezing temperature of their bodily water. When the animals defrost, glycerol disintegrates to glucose, so their blood sugar level rises to ensure that damage repair mechanisms have enough energy.
Picture 1: frozen frog. Source: https://www.neponset.org/happenings/life-goes-on-beneath-the-ice/.
The frogs call on their second trick when antifreeze is not enough, and there is no way to escape being frozen solid. In such case, it is better to start forming internal ice crystals sooner rather than later. To control their growth and avoid cell damage, the animal needs an ice-nucleating agent (INA). Amongst all vertebrates, only frogs can produce that chemical in its own skin or imbibe it from the soil. In addition, some insects, mollusks and nematodes may produce INAs.
It’s not clear which particular INAs the brown tree frog is producing, but like most frogs, their skin is pretty versatile, able to manufacture antimicrobial chemicals and possibly neurotransmitters as well.
Of course, people cannot change naturally pre-set characteristics of their bodies, but still, Cryopreservation as a form of saving the body shell after death becomes more and more popular. It’s not just people – many more things are being frozen with the ability to temporarily close-down, and then retrieve data, cells, or other building components of the body. From embryos, umbilical cords and stem cells to endangered animal species. Storing rare animal’s genetic material or unusual plant’s seeds keeps it possible for future generations to recreate those populations, surely, on condition of saving its natural habitat. Nice perspective, isn’t it?
Picture 2. Art, mastodon frozen in a melting glacier. Credits: Steve Bronstein. Source: https://www.shutterbug.com/content/pros-choice-small-worlds-steve-bronstein-how-capture-whimsical-scenes-using-miniatures-and.
Now, let’s apply cryogenics not to biological but to industrial issues. Have you ever thought that we waste too much energy just heating up the atmosphere? All household electrical appliances operate with low efficiency due to normal conductive metal wires with overcoming electrical resistance followed by a rise of temperature. A device without resistance could make monthly bills much cheaper! But Superconductivity could not happen without the use of cryogenic systems.
Although electricity is a clean and relatively safe form of energy, its generation in ordinary power plants and supply has significant environmental impacts. Thus, rationally distributing its usage we can reduce the carbon footprint. But in addition to that, scientists tamed liquid gases in such way that they could produce electricity: storing liquid air in a tank and later exposing to ambient conditions makes it expand back into a gas. The volume increase is huge, about 700 times, which is used to drive a turbine to generate electricity. The amount of electrical energy you get out, can in some cases end up being more than the electrical energy you put in to liquify the gas.
Today’s need to minimize carbon emissions and reduce ozone damage means it is important to ensure that any laboratory is as environmentally friendly as possible. Low-temperature storages are ideal in this regard! Liquid nitrogen dewars and tanks do not emit any noise or heat pollution, moreover, they don’t even consume electricity to maintain temperature for very long terms. It seems cost-effective, saves on laboratory resource and enables researchers to concentrate on the complexities of the freezing process with the knowledge that their cryogenic experiments are extremely environmentally friendly.
Picture 3. Cryogenic Tanks. Source: http://www.planet.fr/conso-comment-se-faire-cryogeniser.590046.1404.html.
As it was mentioned above, cold is not always a damaging phenomenon causing fragility. To be honest, fragility is also not only a synonym of destruction but a useful material property. The recycling industry takes advantage of brittleness by immersing recyclable metals, insulators, semiconductors, plastics, composites, and living tissues in liquid gases, after which materials are easily pulverized and separated for reprocessing.
Why not use liquid gas as a fuel for vehicles? One of the latest environmental threats concerns on automobile exhausts. The limited amount of crude oil and the continuous rise in prices for petroleum products, as well as environmental problems, require the transition to a new alternative fuel, which simultaneously provides a significant reduction in harmful emissions. So, oil products are to be replaced with liquid natural gas and liquid hydrogen in the future. The use of natural gas makes it possible to maintain the technical characteristics of the engine and to approximately halve the burden on the environment. The effect is the same as the in the late 40’s when usage of kerosene and primus on a kitchen had been changed to natural gas.
To sum up, cryogenic technologies allow to expand technical and technological capabilities in various fields:
In healthcare – to preserve for a long time the blood, its components, stem cells and other biological materials, carry out anemic and bloodless surgeries, destroy neoplasms, effectively treat skin diseases, burns and perform many other cryotherapy operations and procedures;
Agriculture – to save and transport sperm or other biomaterials of farm animals for breeding work for a long time
Metallurgy – to obtain a material with given properties;
Mechanical engineering – to assemble the mechanisms without using heavy pressing equipment, high-temperature heating;
Food industry – to preserve the nutritional and consumer qualities of products during their processing, plus to increase the shelf life of the products;
Environment – to reduce the negative impact on the environment during the processing of secondary resources;
Science – to conduct experiments at low temperatures and to ensure the operation of superconducting and high-energy devices;
Fire safety – quickly and effectively suppress the fires.
Thus, today cryogenics is included in all spheres of human activity, it has not only become an integral part of high technologies but also plays a very important role in solving many socially significant tasks.