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  • It's midnight and all is still, except for the soft skittering of a gecko hunting a spider.

    午夜時間,一切看起來很平靜,除了一隻壁虎輕手輕腳地正在獵捕一隻蜘蛛。

  • Geckos seem to defy gravity, scaling vertical surfaces and walking upside down without claws, adhesive glues or super-powered spiderwebs.

    壁虎看來好像可以抵抗地心引力、攀爬垂直表面,甚至能不依靠爪子、黏著劑或力量很強大的蜘蛛網頭下腳上走路。

  • Instead, they take advantage of a simple principle: that positive and negative charges attract.

    牠們利用的,反而是一個簡單的原理:正電荷和負電荷相吸。

  • That attraction binds together compounds, like table salt, which is made of positively charged sodium ions stuck to negatively charged chloride ions.

    這個吸引力把化合物結合在一起,例如食鹽,是由帶正電的鈉離子黏著帶負電的氯離子構成。

  • But a gecko's feet aren't charged and neither are the surfaces they're walking on.

    但是,壁虎的腳並沒有帶電,牠們攀爬的表面也沒有。

  • So, what makes them stick?

    那麼,是什麼東西讓壁虎的腳可以有黏性呢?

  • The answer lies in a clever combination of intermolecular forces and structural engineering.

    答案就在分子間的作用力和結構工程的巧妙結合。

  • All the elements in the periodic table have a different affinity for electrons.

    元素週期表裡的所有元素都有不同的電子親和力。

  • Elements like oxygen and fluorine really, really want electrons while elements like hydrogen and lithium don't attract them as strongly.

    元素如氧和氟,真的很想要電子,而元素如氫和鋰,則沒有那麼想要電子。

  • An atom's relative greed for electrons is called its electronegativity.

    原子對電子的相對吸引力,稱為電負度 (隱電性/負電性)。

  • Electrons are moving around all the time and can easily relocate to wherever they're wanted most.

    電子總是到處移動,而且很輕易地搬遷到任何它們最想要去的地點。

  • So when there are atoms with different electronegativities in the same molecule, the molecules cloud of electrons gets pulled towards the more electronegative atom.

    所以,當同一個分子裡有不同的電負度原子時,電子雲便會向電負度較高的原子靠近。

  • That creates a thin spot in the electron cloud where positive charge from the atomic nuclei shines through, as well as a negatively charged lump of electrons somewhere else.

    這在電子雲中產生了一個薄薄的區塊,在這裡原子核裡的正電荷及負電的電子塊皆自由移動。

  • So the molecule itself isn't charged, but it does have positively and negatively charged patches.

    分子本身是不帶電的,但它確實有帶正電板和帶負電板。

  • These patchy charges can attract neighboring molecules to each other.

    這些電板可以彼此互相吸引鄰近的分子。

  • They'll line up so that the positive spots on one are next to the negative spots on the other.

    它們會排成一列 ,而正極的那一端會對著另一個分子的負極端。

  • There doesn't even have to be a strongly electronegative atom to create these attractive forces.

    基本上,根本不需要強烈的電負度原子來產生這些吸引力。

  • Electrons are always on the move, and sometimes they pile up temporarily in one spot.

    電子總是在移動,有時它們會暫時聚集在某一個區塊。

  • That flicker of charge is enough to attract molecules to each other.

    那帶電量足夠讓分子相互吸引。

  • Such interactions between uncharged molecules are called van der Waals forces.

    這種未帶電分子之間的相互作用,叫做「凡德瓦力」。

  • They're not as strong as the interactions between charged particles, but if you have enough of them, they can really add up.

    雖然不如帶電粒子之間的相互作用那麼強烈,但是,假如有足夠的未帶電分子,它們也能產生強大的「凡德瓦力」。

  • That's the gecko's secret.

    那就是壁虎的秘密。

  • Gecko toes are padded with flexible ridges.

    壁虎的腳趾上襯著富有彈性的脊。

  • Those ridges are covered in tiny hair-like structures, much thinner than human hair, called setae.

    而這些彈性脊上佈滿了像毛髮般細小的結構,是比人類頭髮纖細更多的毛,叫「剛毛」。

  • And each of the setae is covered in even tinier bristles called spatulae.

    每一根剛毛上又覆蓋了更細小的刷毛,叫「鏟狀匙突」。

  • Their tiny spatula-like shape is perfect for what the gecko needs them to do: stick and release on command.

    這些像小鏟子般的「鏟狀匙突」,正是壁虎所需要的:依照大腦指令黏住和放開。

  • When the gecko unfurls its flexible toes onto the ceiling, the spatulae hit at the perfect angle for the van der Waals force to engage.

    當壁虎在天花板上撐開牠的富有彈性的趾頭時,腳趾上的鏟狀匙突會打開剛好的角度,讓「凡德瓦力」發揮作用。

  • The spatulae flatten, creating lots of surface area for their positively and negatively charged patches to find complimentary patches on the ceiling.

    當鏟狀匙突變平坦時,會產生很多表面積,能夠讓帶正電板和帶負電板在天花板上找到彼此。

  • Each spatula only contributes a minuscule amount of that van der Waals stickiness.

    每一個鏟狀匙突只貢獻極小的「凡德瓦力」黏著力。

  • But a gecko has about two billion of them, creating enough combined force to support its weight.

    但一隻壁虎有約二十億個鏟狀匙突,能產生足夠的結合力可以來支撐牠的重量。

  • In fact, the whole gecko could dangle from a single one of its toes.

    事實上,一根腳趾便能支撐整隻壁虎的重量。

  • That super stickiness can be broken, though, by changing the angle just a little bit.

    不過,那超級黏性也有被破壞的可能,只要角度稍為改變一點的話。

  • So, the gecko can peel its foot back off, scurrying towards a meal or away from a predator.

    所以,壁虎可以從行走的表面脱落,然後快速地接近牠的獵物,或是逃離牠的掠捕者。

  • This strategy, using a forest of specially shaped bristles to maximize the van der Waals forces between ordinary molecules has inspired man-made materials designed to imitate the gecko's amazing adhesive ability.

    這個策略,利用一大片的特殊形狀刷毛,在普通分子之間,將「凡德瓦力」發揮到最大,啟發人類設計出仿壁虎驚人黏性力的人造材料。

  • Artificial versions aren't as strong as gecko toes quite yet, but they're good enough to allow a full-grown man to climb 25 feet up a glass wall.

    人造版本的黏性度還沒有壁虎腳趾的黏性度好,但是它也已經足夠讓一個成年人在玻璃牆上爬行 25 呎。

  • In fact, our gecko's prey is also using van der Waals forces to stick to the ceiling.

    事實上,壁虎的獵物也是利用「凡德瓦力」停在天花板上。

  • So, the gecko peels up its toes and the chase is back on.

    因此,壁虎移動牠的腳趾繼續和牠的獵物展開追逐大戰。

It's midnight and all is still, except for the soft skittering of a gecko hunting a spider.

午夜時間,一切看起來很平靜,除了一隻壁虎輕手輕腳地正在獵捕一隻蜘蛛。

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B2 中高級 中文 美國腔 壁虎 凡德瓦力 分子 電子 腳趾 電板

【TED-Ed】飛簷走壁的壁虎! (How do geckos defy gravity? - Eleanor Nelsen)

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    稲葉白兎   發佈於 2019 年 03 月 03 日
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