墨尔本PTE素材库——Fluoride’s Dental Dominion May Remain a Mystery

墨尔本PTE素材库——Fluoride’s Dental Dominion May Remain a Mystery

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其实这篇文章还是有些许难度的哦！如果有同学可以做到一次性全部听懂，全部理解，那么真的要给你一个大大的赞！说明你的词汇和语法的功底真的不弱哦！这段音频中的专业词汇和较难的大词真的不少，如果些许没有抓住，可能就会影响对于整段音频的理解。

这段音频的主要内容是关于氟化物对于牙齿保护的研究。之前人们只是知道氟化物可以帮助我们对付蛀牙，于是在我们日常的饮水中、牙膏中以及漱口水中都添加了氟化物。听完整篇音频，大家可以试着回答一下问题：

• 氟化物究竟是如何保护牙齿的？
• 美国人民每年要在防护蛀牙上花多少费用？
• 氟化物所形成的保护层，有多厚？

如果没有办法直接回答以上问题的同学们，可以参考下午的词汇表和英语原文哦！澳大利亚语言学院，定期会整理PTE相关的素材，包括音频或者视频，能够让各位PTE的考生在平日复习的时候也能有针对性的提升自己的英语水平！

【key Vocabulary】

Spectroscopic: 光谱学的，分光镜的，光谱的

Fluoridate: 向…中加入氟化物

Fluoride: 氟化物

Shield: 盾，防护物

Cavity: 腔，洞，凹处

Cavities：可以作为腔来理解，是cavity的复数形式；cavities本身的意思为空洞，蛀牙。

Chemically: 用化学，以化学方法

Enamel: n. 搪瓷，珐琅；Vt. 彩饰，涂以瓷釉

Decay: 衰退，腐烂，腐朽

Resistant:  抵抗的，反抗的

Decay-resistant: 抗腐蚀

Veneer: 外表，饰面

Photoelectron: [物]电子，光电子

Nanometers: 纳米 （十亿分之一米）

Chew: 咀嚼

Unravel: 解开，阐明

Full Transcript

Spectroscopic analysis finds that the fluoridated layer thought to protect teeth is probably too thin to be responsible for fluoride’s effects. Karen Hopkin reports

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. [Frank Müller et al., “Elemental Depth Profiling of Fluoridated Hydroxyapatite: Saving Your Dentition by the Skin of Your Teeth?”]

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 to form a thick, decay-resistant veneer. But the latest research kicks that idea in the teeth.

Scientists in Germany used x-ray photoelectron spectroscopy to get a detailed 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. In the meantime, we may not know how it works, but we know that it works. So keep brushing.

—Karen Hopkin

(http://www.scientificamerican.com/podcast/episode/fluorides-dental-dominion-may-remai-10-12-29/)