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  3. One of the differences between animals and machines is that animal bodies can repair much of the damage that a cruel and hostile

One of the differences between animals and machines is that animal bodies can repair much of the damage that a cruel and hostile

admin2015-04-10  30
问题     One of the differences between animals and machines is that animal bodies can repair much of the damage that a cruel and hostile world inflicts on them. A machine, by contrast, has to wait for someone to fix it. But that may change if researchers of self-repairing materials have their way. Two groups in America and Britain are trying to create composite materials that mend themselves if they get cracked, in much the same way that an animal’s broken bone heals itself. The difference is that these materials will heal in minutes rather than months.
    Such self-healing composites may take a while to enter everyday use. But if they can be made reliable they will be welcome in high-stress applications. Jeffrey Moore and his colleagues at the University of Illinois are working on the problem by adding extra components to their composites. These composites consist of fibres embedded in a plastic matrix. The main extra component added by Dr. Moore is a sprinkling of tiny capsules containing a chemical. If the composite cracks, the capsules near the crack break open and release the chemical molecules, which link together to form another type of plastic that binds the crack together and heals the material.
    Ian Bond and his colleagues at the University of Bristol’s department of aerospace engineering are taking a slightly different approach. They use glass fibres rather than carbon fibres in their composite and, instead of adding capsules, they have put the healing molecules into the fibres themselves. The molecules in question are the two ingredients of epoxy resin. Half the fibres contain one ingredient and half contain the other. A crack in the material breaks the fibres, releasing the ingredients which react, form more epoxy, and thus mend the crack. The advantage of this approach is that it retains the basic fibre-plus-matrix structure of the material. Adding capsules changes that and risks weakening it. The disadvantage is that capsules are easier to make than hollow, fluid-filled fibres.
    Whichever system is adopted, two further things are needed. One is a way of checking that a component really has healed. The other is a way to top up the healing molecules once some of them have been used. A repaired area would develop a bruise. Topping up the supply of healing fluid might be done by mimicking another biological system—the network of blood capillaries that supplies living tissues with the stuff they need to thrive. Dr. Moore and Dr. Bond are attempting to borrow from nature this way. If they succeed, the machines of the future will have longer and healthier lives.
Both Dr. Moore and Dr. Bond’s researches aim to
选项 A、add a new extra ingredient to the machines.
B、make the future machines longer and healthier lives.
C、find a way of checking that an ingredient has really healed.
D、make up for the healing molecules once some of them have been used.
答案B
解析 穆尔博士和邦德博士的研究都是为了[A]在机器中加入一种新的其他成分。[B]使未来的机器更持久耐用。[C]找到确定一种成分是否真正实现修复的方法。[D]补充修复分子以备不时之需。文章最后一句提到穆尔博士和邦德博士都在尝试着借用自然界的方式。如果他们成功，未来的机器将更加持久耐用。由此可知他们研究的最终目的是使机器更持久耐用。故[B]正确。
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