Học tiếng Anh hiệu quả, nhanh chóng: http://www.facebook.com/HocTiengAnhVOA, http://www.voatiengviet.com/section/hoc-tieng-anh/2693.html. Nếu không vào được VOA, xin hãy vào http://vn3000.com để vượt tường lửa. Các chương trình học tiếng Anh miễn phí của VOA (VOA Learning English for Vietnamese) có thể giúp bạn cải tiến kỹ năng nghe và phát âm, hiểu rõ cấu trúc ngữ pháp, và sử dụng Anh ngữ một cách chính xác. Xem thêm: http://www.facebook.com/VOATiengViet
Luyện nghe nói và học từ vựng tiếng Anh qua video. Xem các bài học kế tiếp: https://www.youtube.com/playlist?list=PLD7C5CB40C5FF0531
Graphene is a type of graphite. Experts often call it the “Material of the 21st Century” because of its special properties. Graphene is often described as a one-atom-thick layer of carbon. The material has some extraordinary properties. It is 100 times stronger than steel of the same thickness. The nearly transparent material also carries heat and electricity very well. Dan Scheffer is vice-president of the manufacturing company, Vorbeck Materials. He says graphene has many possible uses. Mr. Scheffer says 100 percent pure graphene is difficult to make. But he adds that graphene of lesser purity can still have many of the features of the pure version. Mr. Scheffer says his company produces a layer of graphene that is 80 percent pure. Graphene can be mixed into ink for printers. Stretchable parts can be printed for products such as antennas for radio frequency identification circuits. Louise Brooks manages the product development team at Vorbeck Materials. She says graphene can even be used on wearable electronic clothing. She says the clothing can be machine washed and dried without damaging the graphene. The new material can also be used to make very sensitive microphones. Ray Sauro is a chemical engineer at Vorbeck Materials. He says a graphene piece less than one micron thick can pick up vibrations that no other kind of material can. Mr. Sauro says graphene membranes resist vibrations and heat and could be used by the automotive industry. The products would not be costly to make.