سؤال قراءة ستيب محلول — فهم التفاصيل (تدريب 5686)

(1) Anybody who doesn’t know much about nanotechnology should begin with geckos. These are the lizards that are probably the world’s best climbers. Watching them climb upside down on a horizontal pane of glass, you realize that Spiderman should really have been called Geckoman. These guys out-climb spiders any day. (2) With perfect case they can hang from a single toe, and they do so by pure adhesion, not by sticking a toe in a hole or by curling it round something they can grip. With all the toes on the glass, scientists guess that if the rest of the body were strong enough it could take the weight of a 100kg person suspended below it. Although each toe is equipped with a tiny hook-like claw at the end, these are of no use on the glass. What keeps them up there is the amazing structure of the skin of the toe. (3) Seen under the microscope, each toe has around two million tiny hairs on its underside. Under the higher magnification of an electron microscope the end of each of these hairs is seen to split into hundreds of even tinier nano-hairs, which scientists have called spatulae. These hairs are so small that they are able to establish contact with the molecular structure of the surface the gecko is walking on. With that near-perfect contact the hairs are stuck to the surface by electromagnetic forces called Van der Waals forces. The molecules on the feet and on the surface have areas of slight positive or negative charge that attract each other like mini magnets when they get really close. (4) Scientists have been working for over 15 years now to try to unlock the secrets of the stickiness of gecko toes and find a way to artificially reproduce the same structure of nano-hairs. The hypothesis at the moment is that if any material can be shaped into nano-hairs they will have the same properties as those on gecko toes, so scientists are looking for a different material with which to make the stickiest synthetic surface ever. (5) This is one example of research in the field now known as nanotechnology. In this field, the technology being created can be measured in a few nanometers (one nanometer is a millionth of a millimeter). Interest in developing technology at this level was largely inspired by Richard Feynman at the beginning of the 1960s, but the ‘nano catchphrase was coined in the 1990s by Dr. Eric Drexler, who spurred scientists on through a series of speeches and a book with the title “Engines of Creation: The Coming Era of Nanotechnology”. (6) The scientists working on the geckos see an enormously wide range of possible applications for the kind of adhesive nanotechnology that they will develop the one that will make the biggest splash in the media will be the gloves and the boots that will allow rock climbers to take their sport to hitherto undreamed-of heights. But the technology could also be used in surgery to keep the edges of wounds together without the need for stitches. There will also be a huge potential in the manufacturing sector to stick millions of components together tighter than ever before without glue or screws.