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  3. If you are a fan of science fiction, you’ve no doubt encountered the term na

If you are a fan of science fiction, you’ve no doubt encountered the term na

游客2025-04-21  41
问题     If you are a fan of science fiction, you’ve no doubt encountered the term nanotechnology. Yet over the past year also, a series of breakthroughs have transformed nanotech from sci-fi fantasy into a real world. Applied science, in the process, inspired huge investments by business, academia, and government. In industries as diverse as health care, computers, chemicals, and aerospace, nanotech is overhauling production techniques, resulting in new and improved products, some of which may already be in your home or workplace.
    The inspiration for nanotech goes back to a 1959 speech by the late physicist Richard Feynman, then a professor at the California Institute of Technology, titled "There’s Plenty of Room at the Bottom. " Four decades later, Chad Mirkin, a Chemistry professor at Northwestern University’s $ 34 million nanotech center, used a nanoscale device to etch most of Feynman’s speech onto a surface the size of about 10 tobacco smoke particles.
    What accounts for the sudden acceleration of nanotechnology? A key breakthrough came in 1990, when researchers at IBM’s Almaden Research Center succeeded in rearranging individual atoms at will. Using a device’ known as a scanning probe microscope, the team slowly moved 35 atoms to spell the three-letter IBM logo, thus proving Feynman right. The entire Logo was less than three nanometers.
    Soon, scientists were not only manipulating individual atoms but "spray painting" with them as well. Using a tool known as a molecular beam epitaxy, scientists have learned to create ultra fine films of specialized crystals, built up one molecular layer at a time. This is the technology used today to build read-head components for computer hard drives.
    The next stage in the development of nanotechnology borrows a page from nature. Building a supercomputer no bigger than a speck of dust might seem an impossible task, until one realizes that evolution solved such problems more than a billion years ago. Living cells contain all sorts of nanoscale motors made of proteins that perform myriad mechanical and chemical functions, from muscle contraction to photosynthesis. In some instances, such motors may be re-engineered, or imitated, to produce products and processes useful to humans.
    How are these biologically inspired machines constructed? Often, they construct themselves, manifesting a phenomenon of nature known as self assembly. The macromolecules of such biological machines have exactly the right shape and chemical binding preferences to ensure that when they combine they will snap together in predesigned ways. For example, the two strands that make up DNA’s double helix match each other exactly, which means that if they are separated in a complex chemical mixture, they are still able to find each other easily. [br] According to the passage, all of the following statements are true EXCEPT ______ .
选项 A、The two strands making up DNA’s double helix can find each other easily in a complex chemical mixture
B、Evolution has solved the problem of building a computer smaller than a speck of dust a long time before
C、DNA not only programs cells to replicate themselves but also instructs them how to assemble individual molecules into new materials
D、The read-head components for computer hard drives are constructed by means of the technology known as a molecular beam epitaxy
答案 C
解析 本题的四个选项中，只有C项为正确答案。从最后一段最后一句话可知A项正确；从第五段第二句话可知B项正确；从第四段可知D项正确。只有C项在文中未被提及。
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