SSS 2010-12-29
时间：2018-12-02 作者：英语课 分类：Scientific American(十二)月
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 enamel 1 to form a thick, decay-resistant veneer 2. But the latest research kicks that idea in the teeth.
Scientists in Germany used x-ray photoelectron spectroscopy to get a detailed 3 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 unravel 4. 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.
- 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。
- 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。