2. 外语
  3. New Understanding of Natural Silk’s Mysteries Natural silk, as we all know, has a strength that manmade materials have long

New Understanding of Natural Silk’s Mysteries Natural silk, as we all know, has a strength that manmade materials have long

admin2014-01-28  61
问题                 New Understanding of Natural Silk’s Mysteries
    Natural silk, as we all know, has a strength that manmade materials have long struggled to match. In a discovery that sounds more like an ancient Chinese proverh than a materials science breakthrough, MIT researchers have discovered that silk gets its strength from its weakness. Or, more specifically, its many weaknesses. Silk gets its extraordinary durability and ductility from an unusual arrangement of hydrogen bonds that are inherently very weak but that work together to create a strong, flexible structure.
    Most materials—especially the ones we engineer for strength—get their toughness from brittleness. As such, natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight, ductility and high strength(pound for pound, silk is stronger than steel and far less brittle). But on its face, it doesn’t seem that silks should be as strong as they are; molecularly, they are held together by hydrogen bonds, which are far weaker than the covalent bonds found in other molecules.
    To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals is such that the hydrogen bonds are able to work cooperatively, reinforcing one another against external forces and failing slowly when they do fail, so as not so allow a sudden fracture to spread across a silk structure.
    The result is that natural silks can stretch and bend while retaining a high degree of strength. But while that’s all well and good for spiders, bees and the like, this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture. Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).
    By looking to silk as a model, researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid, more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk—like carbon nanotubes. Super-silks are on the horizon.
Biologists and engineers are interested in understanding natural silks because they are very light and brittle.
选项 A、Right
B、Wrong
C、Not mentioned
答案B
解析 根据文章第二段第二句话可知，和蜘蛛制造的蛛丝类似的蚕丝，因其重量轻，延展性强和韧性高，长期以来引起了生物学家和工程师的兴趣(同样重量，蚕丝比钢要壮，也不那么脆)，题目说生物学家和工程师有兴趣了解天然丝绸，因为它们非常轻盈和脆弱。
转载请注明原文地址:https://kaotiyun.com/show/asGd777K
本试题收录于： 职称英语理工类A级题库职称英语分类
0

职称英语理工类A级

职称英语

相关试题推荐
随机试题
最新回复(0)