听力文摘：蚕丝

Silk

蚕丝

Silk is the strongest natural fiber¹ in the world, as far as we know. Scientists long to understand just how exactly the silkworm manages the process of silk weaving, so they can replicate² the process in order to manufacture such things as high-strength and high-performance materials for sports and law enforcement.

蚕丝是史上全世界最强韧的天然纤维。长久以来，科学家想知道蚕如何产丝，然后仿效制丝过程，生产高强高性能的运动原材及执法材料。

Though our understanding of the silk-making process is not yet complete, scientists do know that the key to making silk lies in the animal’s careful managing of the water content in its silk glands³.

虽然我们对制丝的整个过程了解的不多，但是科学家可以肯定关键在于蚕如何细心掌控丝腺里的水分。

Silk gets its strength from its proteins. Parts of the proteins are hydrophilic, or water-loving; and parts are hydrophobic, or water-fearing. For some time it was a mystery how silkworms managed to convert these proteins into silk threads without the proteins crystallizing before the animal is ready to spin them. Premature⁴ crystallization would clog⁵ up their silk glands, which would likely prove fatal to the little creatures.

蚕丝的高强性是因为蛋白质。蛋白质部分是亲水的；部分是疏水的。蚕吐丝前，蛋白质尚未结晶，蚕是如何将蛋白质转换成蚕线一直是个未解之谜。而过早的结晶会阻塞丝腺，蚕很可能为此丧命。

The answer lies in the silkworm’s slowly decreasing the water content in its silk glands and in the proteins’ ability to retain water, keeping the solution soluble⁶ up until it is spun⁷. As the water decreases, the water-loving parts of the proteins fold together in chains, forcing the water-fearing parts together.

奥秘在于丝腺里的水分逐步流失，而蛋白质可以储存水分，蚕在吐丝前先溶解于水。水分渐渐流失，亲水的蛋白质丝丝缕缕缠绕在一起，将疏水的部分也裹在一起。

As the water level continues to drop, the folded chains of silk push together more and more to form larger and larger gel-like structures. All the while the water-loving parts retain enough water so that the solution does not crystallize prematurely⁸, before there is enough of the material to begin spinning.

水分继续流失，包裹在一起的蚕丝像滚雪球般形成凝胶状。亲水的蛋白质始终储存足够水分避免过早结晶。结晶后，蚕吐出蚕丝。

1 fiber   

n.纤维，纤维质

参考例句：

• The basic structural unit of yarn is the fiber.纤维是纱的基本结构单元。
• The material must be free of fiber clumps.这种材料必须无纤维块。

2 replicate   

v.折叠，复制，模写；n.同样的样品；adj.转折的

参考例句：

• The DNA of chromatin must replicate before cell division.染色质DNA在细胞分裂之前必须复制。
• It is also easy to replicate,as the next subsection explains.就像下一个小节详细说明的那样，它还可以被轻易的复制。

3 glands   

n.腺( gland的名词复数 )

参考例句：

• a snake's poison glands 蛇的毒腺
• the sebaceous glands in the skin 皮脂腺

4 premature   

adj.比预期时间早的；不成熟的，仓促的

参考例句：

• It is yet premature to predict the possible outcome of the dialogue.预言这次对话可能有什么结果为时尚早。
• The premature baby is doing well.那个早产的婴儿很健康。

5 clog   

vt.塞满，阻塞；n.[常pl.]木屐

参考例句：

• In cotton and wool processing,short length fibers may clog sewers.在棉毛生产中，短纤维可能堵塞下水管道。
• These streets often clog during the rush hour.这几条大街在交通高峰时间常常发生交通堵塞。

6 soluble   

adj.可溶的；可以解决的

参考例句：

• These tablets are soluble in water.这些药片可在水中溶解。
• Camphor is soluble in alcohol.樟脑在酒精中可以溶化。

7 spun   

v.纺，杜撰，急转身

参考例句：

• His grandmother spun him a yarn at the fire.他奶奶在火炉边给他讲故事。
• Her skilful fingers spun the wool out to a fine thread.她那灵巧的手指把羊毛纺成了细毛线。

8 prematurely   

adv.过早地，贸然地

参考例句：

• She was born prematurely with poorly developed lungs. 她早产，肺部未发育健全。 来自《简明英汉词典》
• His hair was prematurely white, but his busy eyebrows were still jet-black. 他的头发已经白了，不过两道浓眉还是乌黑乌黑的。 来自辞典例句