The Wonderful World of Small
There’s a quiet revolution going on, and its name is nanotechnology. A host of innovations are coming our way. Some seem almost magical, like the new material created in 2004 by Ray Baughman, a professor at the University of Texas. It’s stronger than steel, transparent, very, very light. A hectare-size sheet would weigh just 280 grams.
When the professor announced that he hadn’t decided what to call it, he started to get emails from around the world suggesting names. Since it was so light and strong, people started calling it "mithril" — the name of a highly prized type of armor used in The Lord of Rings.
There are other discoveries too — perhaps not so astounding, but practical and pleasant. Now there are socks that don’t get smelly, pants that resist stains, windows that repel dirt and toilets that clean themselves. All this results from exploring the world of the very, very small.
Nano comes from the Greek word from dwarf. Usually nanotechnology is defined as the study and manipulation of matter smaller than 100 nanometers (纳米) — that’s the scale of things like molecules and viruses. Ten hydrogen atoms pressed together against each other are just one nanometer long. And one million nanometers fit into a millimeter. Hard to grasp Think of it this way: If everyone in Manila were a nanometer wide, the entire population, standing shoulder to shoulder, would fit on your thumbnail.
Stunning Uses of Nanotechnology
Like Alice in Wonderland, researchers in Nanoland find themselves in a world where old rules don’t apply. Small things behave differently. This is behind several innovations, including the self-cleaning toilet. The toilet bowl is sealed with a super-smooth glaze (涂层) that has microscopic holes under 30 nanometers. Because they’re smaller than bacteria or other tiny particles, there’s not enough room for dirt to get stuck in the suce. Flushing is basically all the work you have to do.
Researchers in Nanoland are also really, really small things with astonishing properties — like the carbon nanotube. Chris Papadopoulos of the University of Victoria, says, "The carbon nanotube is the poster boy for nanotechnology."
In your pencil, carbon, in the form of graphite (石墨), is soft and easily broken. But a carbon nanotube is tough as nails — much tougher in fact. It’s very thin sheet graphite that’s formed into a tube. These tiny straw-like cylinders, which can be as small as half a nanometer wide, are up to 100 times stronger than steel and six times lighter. They are the hardest, stiffest, strongest materials known and are among the world’s best conductors of heat and electricity. They can carry some 1,000 times more electricity current than copper wire: Everybody wants them, but until now they’ve been in short supply and pricey. The current annual production, worldwide, is only 300 kilograms. At ＄ 860 a gram, carbon nanotubes cost 50 times more than gold.
When it comes to finding uses for carbon nanotubes, the range is huge. The National Research Council Canada (NRC) is looking at harnessing their strength by embedding them in construction materials, among other applications. The Boeing Company thinks nanotubes may be the source of futute improvements for high-performance aircraft. Some of the most stunning uses come out of Ray Baughman’s research. Employing what he calls the "ancient technology of spinning", Baughrnan and his team developed a way of spinning carbon nanotubes into fibers that are four times tougher than spider silk, the toughest natural filament (细丝). Since they also conduct electricity, the futuristic yarns could be woven into "smart" clothing that stores electricity, is potentially bulletproof and incorporates sensors capable of adjusting the temperature of garment. The fibers could also be made into cables for suspension bridges much longer than any we have now.
And then there are Baughman’s superstrong, superlight sheets. Papadopoulos explains that one of the reasons scientists are oxcited by the sheets is that they would make ideal solar sails. He says, "With a solar sail, you are allowing the pressure of the sun’s light to propel you through space the same way wind powers a sailboat." But there is also something in this for the earthbound traveler. Using an ordinary microwave oven, Baughman’s team was able to weld one of his sheets between two pieces of plexiglass (树脂玻璃). Afterwards, it still conducted electricity and remained transparent. One idea, therefore, is to put these sheets in windshields of the car and run current through them to defrost car windows.
Medicine and Nanotechnology
Many disease-causing bacteria and viruses are nano size. So only nanotechnology would offer us ways of fighting back. Nucryst Pharmaceuticals has come up with a winning formula that combines nanoscience with old-fashioned folk wisdom. The ancient Greeks used silver to promote healing and pr infection, but the treatment took a back seat when antibiotics came on the scene. Nucryst has revived and improved on the old cure by coating a burn-and-wound bandage with nano-size silver particles that are more reactive than the bulk form of metal. They penetrate into the skin and work steadily. As a result, burn victims can have their dressings changed as little as once a week. Before Nucryst, such dressings had to be changed several times a day, a painful procedure that involved removing a healing cream.
In 2004, Nucryst produced over three million bandages, and its sales topped ＄ 30 million. 70% of chronic-wound patients who were not healing at the expected rate got better with the use of these bandages.
Copy Nature with Nanoteehnology
With new instruments that reveal natural structures down to the last atom, nanotechnologists’ ability to copy nature has taken off. When Bharat Bhushan, a mechanical engineering professor at Ohio State University, wanted to make a super-smooth suce, he decided to copy lotus leaves. Scientists have long known that the leaves shed water very well: They’re waxy and covered with tiny nano-size bumps, so water rolls off. Bhushan succeeded in a polymer (聚合体) sheet that was equally smooth. "If you applied it to glass, you could have windows that don’t need washing." says Bhushan.
Hicham Fenniri, a chemistry professor at the Univeristy of Alberta, took a similar tack to make artificial joints act more like natural ones. The body recognizes an artificial hip or knee as foreign and may reject it. In most cases, the implant can become loose and painful and has to be replaced. But Fenniri has made a nanotube coating for the artificial joint. It’s a very good imitation of collagen (原质), a natural protein that is part of bone. As a result, the coating attracts bone cells. This is important because bone growth helps integrate an artificial joint into the body. Says Fenirri, "You need to attract the right cells to the right places, right away. Speed is essential when incorporating an artificial joint into the body."
(1,146 words) Nanotechnology has resulted in a wide range of amazing, practical discoveries such as stain-resistant trousers and self-cleaning toilets.