欧美伦理一区二区-91视频网页-国产高清在线视频-国产黄色在线-免费的黄色-日本精品视频在线观看

A. Carbon nanotubes are molecular tubes about 10,000 times thinner than a human hair. They consist of rolled up sheets of carbon hexagons. They have remarkable electronic and mechanical properties that make them suitable for many applications.