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SSS 2010-12-29

时间:2011-01-06 06:54来源:互联网 提供网友:tianshun   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

Beauty is only skin deep. And the beauty of shiny white teeth is even less deep. Because a new study shows that fluoride forms a thinner protective shield than experts thought it did. The results appear in the surface science journal Langmuir.

American consumers spend more than $50 billion a year fighting cavities. When we realized that fluoride could help, we put it in our drinking water, our toothpaste and our mouthwash. But how does fluoride work its magic? Many figured that fluoride chemically reacts with the main mineral in enamel1 to form a thick, decay-resistant veneer2. But the latest research kicks that idea in the teeth.

Scientists in Germany used x-ray photoelectron spectroscopy to get a detailed3 image of the surface of a treated tooth. And they found that the protective covering is actually only 6 nanometers thick. That's about a fifteen-thousandth as thick as a sheet of paper. And a layer that skimpy would likely be worn away by ordinary chewing.

How fluoride keeps the tooth fairy away is a mystery that researchers are still working to unravel4. In the meantime, we may not know how it works, but we know that it works. So keep brushing.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Karen Hopkin.


点击收听单词发音收听单词发音  

1 enamel jZ4zF     
n.珐琅,搪瓷,瓷釉;(牙齿的)珐琅质
参考例句:
  • I chipped the enamel on my front tooth when I fell over.我跌倒时门牙的珐琅质碰碎了。
  • He collected coloured enamel bowls from Yugoslavia.他藏有来自南斯拉夫的彩色搪瓷碗。
2 veneer eLczw     
n.(墙上的)饰面,虚饰
参考例句:
  • For the first time her veneer of politeness began to crack.她温文尔雅的外表第一次露出破绽。
  • The panel had a veneer of gold and ivory.这木板上面镶饰了一层金和象牙。
3 detailed xuNzms     
adj.详细的,详尽的,极注意细节的,完全的
参考例句:
  • He had made a detailed study of the terrain.他对地形作了缜密的研究。
  • A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
4 unravel Ajzwo     
v.弄清楚(秘密);拆开,解开,松开
参考例句:
  • He was good with his hands and could unravel a knot or untangle yarn that others wouldn't even attempt.他的手很灵巧,其他人甚至都不敢尝试的一些难解的绳结或缠在一起的纱线,他都能解开。
  • This is the attitude that led him to unravel a mystery that long puzzled Chinese historians.正是这种态度使他解决了长期以来使中国历史学家们大惑不解的谜。
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