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  • Your cell phone is mainly made of plastics and metals.

  • It's easy to appreciate the inventive process

  • by which those elements are made to add up to something so useful and entertaining.

  • But there's another story we don't hear about as much.

  • How did we get our raw ingredients in the first place

  • from the chaotic tangle of materials that is nature?

  • The answer is a group of clever hacks known as separation techniques.

  • They work by taking advantage of the fundamental properties of things

  • to disentangle them from each other.

  • Simple separation techniques apply to many physical scenarios,

  • like separating cream from milk,

  • extracting water from soil,

  • or even sifting out flecks of gold from river sand.

  • But not all mixtures are so easy to unravel.

  • In some of those cases,

  • we can exploit the differences between physical properties within a mixture,

  • like particle size,

  • density,

  • or boiling point

  • to extract what's required.

  • Take petroleum,

  • a mixture of different types of hydrocarbons.

  • Some of these are valuable as fuels,

  • and others make good raw materials for generating electric power.

  • To separate them, experts rely on one important feature:

  • different hydrocarbons boil at different temperatures.

  • During the boiling process, each type vaporizes at a precise point,

  • then gets separately funneled into a container

  • and collected as a liquid as it cools.

  • Separation techniques also take us to the sea.

  • In some drought-stricken countries,

  • the ocean is the only available water source.

  • But of course, humans can't drink salt water.

  • One way to get around this problem

  • is to remove salt from sea water with reverse osmosis,

  • a process that separates water's ingredients by size.

  • A membrane with pores bigger than water particles,

  • but smaller than salt particles,

  • only lets fresh water pass through,

  • transforming what was once undrinkable into a life saver.

  • Meanwhile in the medical world,

  • blood tests are a vital tool for evaluating a person's health,

  • but doctors typically can't examine blood samples

  • until they've separated the solid blood cells

  • from the liquid plasma they're dissolved in.

  • To do that, a powerful rotational force is exerted on the test tube,

  • causing heavier substances with higher density,

  • like blood cells,

  • to move away from the rotational axis.

  • Meanwhile, lighter substances with lower density,

  • like plasma,

  • move to its center.

  • The tube's contents divide clearly,

  • and the blood cells and liquid plasma can be tested independently.

  • But sometimes, unlike oil, seawater, and blood,

  • the parts of mixtures that we want to separate

  • share the same physical properties.

  • In these cases, the only way to isolate ingredients is by chemical separation,

  • a complex process that relies on unique interactions

  • between components within a mixture and another material.

  • One of these methods is chromatography,

  • a tool forensic scientists use to examine crime scenes.

  • They dissolve gathered evidence in a gas,

  • and can monitor and analyze the ingredients

  • as they separate and move at varying speeds

  • due to their unique chemical properties.

  • That information then tells scientists precisely what was present at the scene,

  • often helping to identify the culprit.

  • Separation techniques are not just about industry,

  • infrastructure,

  • medicine,

  • and justice.

  • One of the most technically ambitious projects in human history

  • is a separation technique aimed at answering the fundamental question,

  • "What is the Universe made of?"

  • By accelerating particles to extremely high speeds

  • and smashing them into each other,

  • we can break them into their constituent parts ever so briefly.

  • And if we succeed at that, what's next?

  • Is there a most elementary particle?

  • And if so, what's it made of?

Your cell phone is mainly made of plastics and metals.

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B1 中級

TED-ED】一見切り離せないものをどうやって切り離すのか?- イド・マゼン (【TED-Ed】How do we separate the seemingly inseparable? - Iddo Magen)

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    黃于珍 に公開 2021 年 01 月 14 日
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