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1、第六篇 Making Light of1 SleepAll we have a clock located inside our brains. Similar to your bedside alarm clock， your internal clock2 runs on a 24-hour cycle. This cycle，called a circadian rhythm，helps control whenyou wake，when you eat and when you sleep.Somewhere around puberty，something happens in th
2、e timing of the biological clock. Theclock pushes forward，so adolescents and teenagers are unable to fall asleep as early as they used to. When your mother tells you its time for bed，your body may be pushing you to stay up3 for several hours more. And the light coming from your computer screen or TV
3、 could be pushing you to stay up even later.This shift4 is natural for teenagers. But staying up very late and sleeping late can get your bodys clock out of sync with the cycle of light and dark5. It can also make it hard to get out of bed in the morning and may bring other problems，too. Teenagers a
4、re put in a kind of a gray cloud6 when they dont get enough sleep，says Mary Carskadon，a sleep researcher at Brown University in Providence，RI7 .It affects their mood and their ability to think and learn.But just like your alarm clock，your internal clock can be reset. In fact，it automatically resetsi
5、tself every day. How? By using the light it gets through your eyes.Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal clocks. For years，researchers thought that the signals that synchronize the bodys clock8 were handled thro
6、ugh the same pathways that we use to see.But recent discoveries show that the human eye has two separate light-sensing systems. One system allows us to see. The second system tells our body whether its day or night.Graphenes Superstrength1Big technology comes in tiny packages. New cell phones and pe
7、rsonal computers get smallerevery year，which means these electronics require even smaller components on the inside.Engineers are looking for creative ways to build these components，and theyve turned their eyes to graphene，a superthin2 material，made of carbon，that could change the future of electroni
8、cs.This years Nobel Prize for Physics3 has been awarded to Andre Geim and Kostya Novoselovfrom the University of Manchester4，UK. for the discovery of graphene. Graphene isnt just small,its“the thinnest possible material in this world，” says Novoselov. He calls it a“wondermaterial. ”Its so thin that
9、you would need to stack about 25,000 sheets just to make a pile as thick as a piece of ordinary white paper. If you were to hold a sheet of graphene in your fingers5，youd have no idea because you wouldnt be able to see it.Carbon is one of the most abundant elements in the universe. Every known kind
10、of lifecontains carbon. Graphene is a sheet of carbon，but only one atom thick. You dont have to lookfar to find grapheme its all around you.If you want this high-tech wonderstuff6，all you need is a pencil，paper and a little adhesivetape. Use the pencil to shade a small area on the paper, and then ap
11、ply a small piece of adhesivetape over the area7. When you pull up the tape，youll see that it pulls up a thin layer of some ofthe shading from your pencil. That layer is called graphite，one of the softest minerals in the world.Now stick the same piece of tape on another sheet of paper and pull the t
12、ape up there should be an even thinner layer，this time left on the paper. Now imagine that you do this over and over，until you get the thinnest possible layer of material on the paper. This layer would be only one atom thick，and you wouldnt be able to see it. Graphite is made of layers of graphene，s
13、o when you get to the thinnest possible layer，youve found graphene. Life Form Found on Saturns TitanScientists say they have discovered hints of alien life1 on the Saturns moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spacecraf
14、t Cassini4,which pointed to,the existence of methane-based form of life on Saturns biggest moon.Scientists have reportedly discovered clues showing primitive alien beings arebreathing inTitans dense atmosphere filled with hydrogen.They argue that hydrogen gets absorbed before hitting Titans planet-l
15、ike surface covered with methane lakes and rivers. This,they say,points to the existence of somebugs5 consuming the hydrogen at the surface of the moon less than half the size of the Earth.We suggested hydrogen consumption because its the obvious gas for life to consume on Titan,similar to the way w
16、e consume oxygen on Earth,says NASA scientist Chris McKay.If these signs do turn out to be a sign of life,it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.To date,scientists have not yet detected this form of life anywhere,though there are liquid-water-based microorganisms on
