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Duration:05:03
Uploaded:2016-09-23
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Why did some of Samsung's Galaxy Note7 phones explode? And what can Tardigrades teach us about protecting our DNA?

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Hosted by: Hank Green
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Sources:

Cell Phone
http://www.forbes.com/sites/shelbycarpenter/2016/09/16/government-official-recall-samsung-galaxy-note-7/#43ce57426e53
http://www.forbes.com/sites/jvchamary/2016/09/04/samsung-note7-battery/#71c2784c1eb2
http://www.samsung.com/us/note7recall/
http://www.cpsc.gov/en/Recalls/2016/Samsung-Recalls-Galaxy-Note7-Smartphones/
http://electronics.howstuffworks.com/everyday-tech/lithium-ion-battery.htm
http://www.livescience.com/50643-watch-lithium-battery-explode.html
http://batteryuniversity.com/learn/archive/understanding_lithium_ion
http://pubs.rsc.org/en/content/articlehtml/2013/ra/c3ra45748f
http://pubs.rsc.org/en/content/articlehtml/2013/ra/c3ra45748f
https://www.cnet.com/news/samsung-galaxy-note-7-explosion-battery-manufacturing-error/
http://engineering.mit.edu/ask/how-does-battery-work

Tardigrades
http://nature.com/articles/doi:10.1038/ncomms12808
http://www.bbc.com/earth/story/20150313-the-toughest-animals-on-earth
http://tvblogs.nationalgeographic.com/2014/03/19/5-reasons-why-the-tardigrade-is-natures-toughest-animal/
http://www.mayoclinic.org/tests-procedures/x-ray/basics/risks/prc-20009519
http://www.bowdish.ca/lab/wp-content/uploads/2014/11/Culture-of-HEK-cells.pdf

Image Sources:
https://commons.wikimedia.org/wiki/File:Samsung-Galaxy-Note-7-renders-1.jpg
https://commons.wikimedia.org/wiki/File:NOAAseep_600CratersBrinePools.jpg
https://commons.wikimedia.org/wiki/File:Cistern_spring_in_Yellowstone.jpg
[SciShow intro plays]

Hank: It’s that time of year again: people are upgrading their smartphones to the newest, flashiest model. But some customers are getting a little too much bang for their buck.

At least 90 people who bought Samsung’s Galaxy Note 7 smartphone have reported that the phones are overheating, causing burns, or even catching on fire. Both Samsung and the US government’s Consumer Product Safety Commission have officially issued a recall of Galaxy Note 7s that were sold before September 15th. It is just too dangerous to use these phones, because of a battery-related manufacturing problem.

A battery is made of a positive electrode called a cathode and a negative electrode called an anode. These electrodes connected by a liquid or gel called the electrolyte, which lets charged particles move around. The chemical reactions inside a battery generate electrical energy, as electrons or ions flow from one electrode to the other.

A lithium-ion battery, specifically, is a rechargeable battery that can be really compact. So they’re used in all kinds of electronics, from cell phones to laptops. Its cathode is made from a lithium metal oxide and its anode is made of graphite, and they’re kept apart by a thin polymer separator that still lets lithium ions flow back and forth.

When one of these batteries is being charged, lithium ions flow through the electrolyte from the cathode to the anode. And when you’re using the battery, they move in the opposite direction. Because of lithium’s atomic structure, these batteries can store a lot of energy, which is great for things like cell phones. But it’s not so great if something goes wrong, like if the battery is overcharged or the separator between the electrodes gets damaged.

If the separator gets punctured, for example, it can cause a short circuit, since the lithium ions would flow through the new path of least resistance. A short circuit can cause a buildup of heat, which can cause more heat-generating chemical reactions inside the battery, and it might start degrading in what’s called thermal runaway. That’s when the battery might catch fire or even explode.

There’s a very small chance that this could happen in any device that has a lithium-ion battery that’s poorly designed or installed – like, that’s why you hear about hoverboards combusting. In the case of these early Galaxy Note 7s, the batteries are probably overheating because of a manufacturing problem.

Samsung thinks that a production error put too much pressure on the battery inside some of the first phones to be manufactured, squeezing together the cathode and anode, which can cause a short circuit and all that excess heat. So people charging or using their phones normally are all of a sudden getting hurt by overheated batteries. Basically, the only way to fix it is to swap your phone out for a not-so-dangerous one – that’s the reason for the recall. So if you bought a Galaxy Note 7 before September 15th, you should probably go do that before it burns a hole in your pants.

Now, you know who probably could survive an overheating battery fire and not even give a crap? Tardigrades! Also known as water bears, tardigrades are a phylum of adorably tiny invertebrates with four pairs of legs, tube-shaped spiky mouths... and superpowers.

They’ve been found in extreme environments, from the bottom of the ocean to boiling hot springs. Scientists have dehydrated them, blasted them with radiation, and even shot them into the vacuum of space. And they’ve survived every time.

In a paper published in Nature this week, Japanese researchers found some of the genes that make tardigrades so tough – including a protein that can also protect human DNA from radiation damage. A team of scientists, led by a researcher from the University of Tokyo, sequenced the genome of the tardigrade species Ramazzottius varieornatus. They found more of the genes that are known to help with cell survival in other animals, like by reducing oxidative stress and repairing damaged DNA. Plus, they found a new protein that binds to nuclear DNA strands, that they called Damage suppressor, or Dsup, because they thought it might protect DNA somehow.

To test their hypothesis, scientists added the Damage suppressor gene to cultured human kidney cells, so that these cells were making the tardigrade protein. Then, they pummeled the cells with X-ray radiation, which can cause breaks in one or both strands of the DNA double helix, and some hydrogen peroxide, which also damages DNA. And the cells with this tardigrade protein had much less DNA damage than the unprotected cells! More protected cells stayed alive, and some even kept dividing, as if they hadn’t been irradiated at all.

The scientists looked for the Damage suppressor gene in databases of other animals’ DNA, but they couldn’t find it. So the extra protection might be unique to tardigrades. And this is probably just one of many genes and proteins that help them cope with biological stress. By understanding what makes super-survivors like tardigrades so dang tough, maybe eventually we can figure out some new ways to protect our own cells from harsh environments.

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