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    Why is alcohol used to store things?

    Hammerhead sharks preserved in alcohol in the East Wing of the Natural History Museum in Berlin, Germany. (Image credit: Sean Gallup / Getty Images)

    I have visited laboratories and museums and admired the pristine nature Eyeball Or a small dead creature floating in a glass jar, you’ve seen the conservative force of alcohol. The official name of this technology is liquid storage. Scientists have relied on this to preserve curious specimens since the 1600s.And if done correctly, it can maintain the sample for hundreds of years, and American Museum of Natural History..

    But how does it work?

    Bill Carroll, an adjunct professor at Indiana University Bloomington, told Live Science: He used wine as an example. It is made by yeast eating the sugar in the grapes and excreting alcohol. However, yeast excretes so much alcohol that its concentration becomes toxic and kills yeast, he said. And its alcohol content (about 14%) helps slow the growth of bacteria for years (many wines also contain additional preservatives such as sulfur). California Wine Advisor..

    Related: Does salt bring water to a boil faster?

    Preservation of other organic materials — DNACatherine Maslenikov, fish collection manager at the Burke Museum in Seattle, says that even tissues and animals as a whole need higher alcohol levels. Maslenikov usually relies on alcohol, especially ethanol, for long-term storage.

    For example, Maslenikov takes fish specimens, takes some tissue samples for DNA analysis, injects formalin (a solution of formaldehyde gas dissolved in water) into the fish, and internal organisms such as enzymatic reactions and tissue degradation. Stop the scientific process. Then she may soak the fish specimen in a jar of 70% alcohol and 30% water. For long-term storage, “70% seems to be that magic number,” says Maslenikov. The solution has enough water to keep the tissue hydrated, which helps animals and specimens to retain their shape. There is also enough alcohol to prevent the growth of mold and bacteria.

    Higher concentrations of alcohol, such as 95% ethanol, act as a dehydrating agent. That is, it removes water from cells, tissues, or whole-body specimens and replaces them with alcohol. When water is scarce, water-sensitive proteins change. They unfold or denature, cure adjacent to each other and fix the shape of the specimen. According to Ask a Biologist, A series run by Arkansas State University. According to a 2013 study in the journal, this technique is a common way to store DNA. PLOS One..

    Determining the percentage of alcohol used can be difficult. Using too much or too little can affect the shape and flexibility of the sample and reduce the ability of the sample to be stored in solution. The high concentration of alcohol used to dehydrate the specimen preserves it. However, Maslenikov said the process can also cause the specimen to shrink (due to the loss of water) and become brittle (from the hardened protein). Sometimes it’s okay. It all depends on what you are trying to save.

    On the other hand, if too much water is retained, the test piece may deteriorate rapidly.

    “If the tissue of the organism has enough water, alcohol can be diluted,” Christopher Rogers, an associate research professor at the Center for Biological Research and Ecology at the University of Kansas, told Live Science in an email. Told. If this happens, the alcohol concentration may not be strong enough to kill lurking microbes that may be lurking deeper in the specimen, such as the intestines of whole animal specimens. ..What I missed Bacteria The specimen can be disassembled. “This is why it is important to change alcohol [about] “24 hours after pickling the creatures,” Rogers said to increase the alcohol content of the solution.

    When it comes to using alcohol as a preservative, Carroll said you’re looking for a sweet spot of concentration: “a concentration that inhibits microbes but doesn’t destroy the cellular structure of what you’re seeing.” ..

    Originally published in Live Science.

    Why is alcohol used to store things?

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