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The Tiniest Electric Motor in the World 1. Scientists recently made public the tiniest electric motor ever built. You could stuff hundreds of them into the period at the end of this sentence. One day a similar engine might power a tiny mechanical doctor that would travel through your body to remove your disease. 2. The motor works by shuffling atoms between two molten metal droplets (小滴) in a carbon nanotube. One droplet is even smaller than the other. When a small electric current is applied to the droplets, atoms slowly get out of the larger droplet and join the smaller one. The small droplet grows—but never gets as big as the other droplet—and eventually bumps into the large droplet. As they touch, the large droplet rapidly sops up the atoms it had previously lost. This quick shift in energy produces a power stroke. 3. The technique exploits the fact that surface tension—the tendency of atoms or molecules to resist separating—becomes more important at small scales. Surface tension is the same thing that allows some insects to walk on water. 4. Although the amount of energy produced is small—20 microwatts—it is quite impressive in relation to the tiny scale of the motor. The whole setup is less than 200 nanometers on a side, or hundreds of times smaller than the width of a human hair. If it could be scaled up to the size of an automobile engine, it would be 100 million times more powerful than a Toyota Camry’s 225 horsepower V6 engine. 5. In 1988, Professor Richard Muller and colleagues made the first operating micrometer, which was 100 microns across, or about the thickness of a human hair. In 2003, Zettl’s group created the first nanoscale motor. In 2006, they built a nanoconveyor, which moves tiny particles along like cars in a factory. 6. Nanotechnology engineers try to mimic nature, building things atom by atom. Among other things, nanomotors could be used in optical circuits to redirect light, a process called optical switching. Futurists envision a day when nanomachines, powered by nanomotors, travel inside your body to find disease and repair damaged cells. A．An Introduction of a Toyota’s 225 Horsepower V6 Engine B．A Description of the Nanomotor in Terms of Power and Size C．Surface Tension D．Previous Inventions of Nanoscale Products E．The Working Principle of the Nanomotor F．Possible Fields of Application in the Future Paragraph 5 ______
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Batteries Built by Viruses What do chicken pox, the common cold, the flu, and AIDS have in common They’re all disease caused by viruses, tiny microorganisms that can pass from person to person. It’s no wonder that when most people think about viruses, finding ways to steer clear of viruses is what’s on people’s minds. Not everyone runs from the tiny disease carriers, though. In Cambridge, Massachusetts, scientists have discovered that some viruses can be helpful in an unusual way. They are putting viruses to work, teaching them to build some of the world’s smallest rechargeable batteries. Viruses and batteries may seem like an unusual pair, but they’re not so strange for engineer Angela Belcher, who first came up with the idea. At the Massachusetts Institute of Technology (MIT) in Cambridge, she and her collaborators bring together different areas of science in new ways. In the case of the virus-built batteries, the scientists combine what they know about biology, technology and production techniques. Belcher’s team includes Paula Hammond, who helps put together the tiny batteries, and Yet-Ming Chiang, an expert on how to store energy in the form of a battery. "We’re working on things we traditionally don’t associate with nature," says Hammond. Many batteries are already pretty small. You can hold A, C and D batteries in your hand. The coin-like batteries that power watches are often smaller than a penny. However, every year, new electronic devices like personal music players or ceil phones get smaller than the year before. As these devices shrink, ordinary batteries won’t be small enough to fit inside. The ideal battery will store a lot of energy in a small package. Right now, Belcher’s model battery, a metallic disk completely built by viruses, looks like a regular watch battery. But inside, its components are very small—so tiny you can only see them with a powerful microscope. How small are these battery parts To get some ideas of the size, pluck one hair from your head. Place your hair on a piece of white paper and try to see how wide your hair is—pretty thin, right Although the width of each person’s hair is a bit different, you could probably fit about 10 of these virus-built battery parts, side to side, across one hair. These microbatteries may change the way we look at viruses. What expression below is opposite in meaning to the word "shrink" appearing in paragraph 5
肠结构最主要的检查方法为______
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