Placeholder Image

字幕表 動画を再生する

  • Your hands, up close, are anything but smooth.

  • With peaks and valleys, folds and rifts,

  • there are plenty of hiding places for a virus to stick.

  • If you then touch your face, the virus can infect you.

  • But there are two extraordinarily simple ways you can keep that from happening:

  • soap and water, and hand sanitizer.

  • So which is better?

  • The coronavirus that causes COVID-19

  • is one of many viruses whose protective outer surface is made of a lipid bilayer.

  • These lipids are pin shaped molecules whose heads are attracted to water,

  • and tails are repulsed by it.

  • So in water-rich environments, lipids naturally form a shell like this,

  • with the heads outside and the tails inside.

  • Their shared reaction to water makes the lipids stick loosely together

  • this is called the hydrophobic effect.

  • This outer structure helps the molecular machinery of the virus

  • break through cellular membranes and hijack our cells.

  • But it has thousands upon thousands of weak points

  • where the right molecules could pry it apart.

  • And this is where soap comes in.

  • A single drop of any brand of soap contains quadrillions of molecules

  • called amphiphiles, which resemble biological lipids.

  • Their tails, which are similarly repulsed by water,

  • compete for space with the lipids that make up the virus's shell.

  • But they're just different enough to break up the regularity of the virus's membrane,

  • making the whole thing come crashing down.

  • Those amphiphiles then form bubbles of their own around particles

  • including the virus's RNA and proteins.

  • Apply water, and you'll wash that whole bubble away.

  • Hand sanitizers work less like a crowbar, and more like an earthquake.

  • When you surround a coronavirus with water,

  • the hydrophobic effect gives the bonds within the membrane their strength.

  • That same effect also holds the big proteins

  • that form coronavirus's spikes in place

  • and in the shape that enables them to infect your cells.

  • If you dry the virus out in air, it keeps its stability.

  • But now surround it with a high concentration of an alcohol,

  • like the ethanol or isopropanol found in most hand-sanitizers.

  • This makes the hydrophobic effect disappear,

  • and gives the molecules room to move around.

  • The overall effect is like removing all of the nails and mortar from a house

  • and then hitting it with an earthquake.

  • The cell's membrane collapses and those spike proteins crumble.

  • In either method, the actual process of destroying the virus

  • happens in just a second or two.

  • But doctors recommend at least 20 seconds of hand-washing

  • because of the intricate landscape that is your hand.

  • Soap and sanitizer need to get everywhere, including your palms, fingertips,

  • the outsides of your hands, and between your fingers,

  • to protect you properly.

  • And when it comes to a coronavirus outbreak,

  • doctors recommend washing your hands with soap and water whenever possible.

  • Even though both approaches are similarly effective at killing the virus,

  • soap and water has two benefits:

  • first it washes away any dirt which could otherwise hide virus particles.

  • But more importantly,

  • it's simply easier to fully cover your hands with soap and water

  • for 20 seconds.

  • Of course, hand sanitizer is more convenient to use on the go.

  • In the absence of a sink, use the sanitizer as thoroughly as possible

  • and rub your hands together until they're dry.

  • Unfortunately, there are billions of people

  • who don't have access to clean drinking water,

  • which is a huge problem at any time but especially during an outbreak.

  • Researchers and aid groups are working to provide solutions for these communities.

  • One example is a device that uses salt, water, and a car battery

  • to make chlorinated water that kills harmful pathogens

  • and is safe for hand-washing.

  • So wherever possible, soap and water are recommended for a coronavirus,

  • but does that mean it's best for every viral outbreak?

  • Not necessarily.

  • Many common colds are caused by rhinoviruses

  • that have a geometric protein structure called a capsid

  • instead of a lipid membrane.

  • The capsid doesn't have nearly as many weak points

  • where soap amphiphiles can pry it apart,

  • so it takes longer for soap to be effective.

  • However some of its surface proteins are still vulnerable

  • to the destabilizing effect of hand sanitizer.

  • In this and similar cases, hand sanitizer may be more effective,

  • especially if you then wash your hands to remove residual particles.

  • The best way to know which to use for any given outbreak

  • is to do what's best for all things illness-related:

  • follow the advice of accredited medical professionals.

Your hands, up close, are anything but smooth.

字幕と単語

動画の操作 ここで「動画」の調整と「字幕」の表示を設定することができます

B1 中級

どっちがいいの?石鹸やハンドサニタイザーは、 - アレックスローゼンタールとポールThordarson (Which is better: Soap or hand sanitizer? - Alex Rosenthal and Pall Thordarson)

  • 224 6
    Seraya に公開 2021 年 01 月 14 日
動画の中の単語