People are always racking_their_brains to find a way of preventing buildings’ collapse.Better materials and technology help，but they are not a solution.

　　Just like humans，a building has its own life cycle from “birth” to “death”．If we know when a building is going to collapse，we can repair it in advance or get out of it before it falls.

　　Now，scientists at the University of Illinois have developed a material that turns red before it breaks.The invention could be used in things like climbing ropes or bridge supports.

　　The research was led by Nancy Sottos，a professor at the university’s Beckman Institute，and Douglas Davis，a graduate research assistant.

　　The secret behind the color­changing material is a type of molecule (分子)．A molecule is a group of atoms held together by chemical bonds.Imagine you and your friends standing in a circle，holding hands.Each person stands for one atom，your hands represent the bonds，and the entire circle represents a molecule.If one person lets go of his or her hands，the molecule changes color.

　　The research team put the molecule into a soft material.When the researchers stretched the material，it turned bright red for a few seconds before it broke into two pieces.When they repeatedly stretched and relaxed the material，without breaking it，it only turned a little red.

　　The major problem is that light can get rid of the red color.When the team shone bright light on the molecule，the broken bond was fixed，and the color disappeared.

【2017届高考英语一轮复习基础巩固学案：Unit 3《The Million Pound Bank Note》（重大版必修3）】相关文章：

★ 【北京专用】2014届高考英语一轮复习方案课时作业：选修6 Unit 4 Global warming

★ 2014高考英语（新人教版）一轮基础训练（17）A、B卷（附答案或解析）

★ 【三维设计】2017届高考英语（江苏专用）二轮复习课件：必修2 Unit 3《Amazing people》

★ 【优化方案】2017届高考英语二轮复习全国卷Ⅱ题型重组训练：第2组（含解析）

★ 【北京专用】2014届高考英语一轮复习方案课时作业：选修6 Unit 3 A healthy life

★ 2014高考英语（新人教版）一轮基础训练（14）A、B卷（附答案或解析）

★ （安徽专用）2014届高考英语一轮复习方案 作业手册（5）模块2 《Unit 5 Rhythm》（含解析） 北师大版必修1

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 2 B卷 Word版含解析

★ 四川省2016届高考英语一轮复习课时作业（45） Module 3 Foreign Food 外研版选修8

★ 2014届高考英语一轮复习课时作业(二十九)必修5Module 5《The Great Sports Personality》（外研版）