MIT chemistry professor Daniel Nocera led research on the artificial leaf project, says he and his colleagues took their cues from plants, which are literally buzzing with electricity.
“What happens is that sunlight comes in and hits the leaf and then the leaf immediately takes that sunlight and makes a wireless current,”says Nocera.
During photosynthesis, the energy in sunlight splits water molecules into hydrogen and oxygen. The hydrogen joins with carbon dioxide to make sugar, an essential fuel for plant growth. In Nocera’s laboratory, scientists replicated that chemical process using a silicon device about the size and shape of a playing card, only thinner. It's coated with nickel and cobalt catalysts that when exposed to water and ultraviolet light, accelerate a chemical reaction.
“So you can literally just take this bottle of water and we could take the chip, put the chip inside the bottle of water, and go holding it up in the sun and you would start seeing hydrogen and oxygen bubbles coming up.”
The hydrogen is then recombined with the oxygen in a fuel cell to produce electricity. Nocera’s work builds on previous research. John Turner of the National Renewable Energy Laboratory pioneered the concept in 1998 using materials too expensive and unstable for commercialization.
Nocera says his so-called practical artificial leaf uses less expensive materials, is more stable and more efficient than that earlier design. He says the challenge is to collect the gases coming off the silicon and store them until the energy is needed. “That has to be engineered still,” he adds. “We don't know how to do that. It will be something that we will start doing pretty soon. You’ll be storing a fair amount of energy because this system is working at the efficiency more or less of the solar cell.”
In laboratory experiments, Nocera's solar cell prototype operated continuously for 45 hours without a drop in electrical output. Nocera notes that it works in any type of water. “So you can use natural water sources, which for us is a big deal, because if you are in rural parts of the world. especially where they are poor, it is really costly to bring in pure water and so, the fact that you can go over there' to a puddle and pick the water up and begin using it, is something that is very powerful for us."
Nocera believes the artificial leaf could be especially useful as an inexpensive source of electricity for low-income populations in developing countries. The goal, Nocera says, is to make each home its own power station. He predicts a commercial version of the artificial leaf will be on the market within three years.
1. MIT chemistry professor Daniel Norcera's research is different from John Turner's mainly in that________.| A．Norcera's research outcome is too commercialized |
| B．Norcera has found a cheaper and steadier material |
| C．Norcera's working system is like the solar cell |
| D．Norcera's research is original and unprecedented |
| A．an efficient way of storing gases coming off the silicon |
| B．a feasible system that is as efficient as solar cell |
| C．a silicon device that can accelerate the chemical reaction |
| D．how to spread the cheap source of electricity in developing countries |
| A．It is convenient for every home to own a power station |
| B．It can change the ordinary water into pure water |
| C．It has a commercial value for poor populations |
| D．It can recycle waste water and thus eco-friendly |
| A．Plants Can Produce Cheap and Steady Electricity |
| B．Storage of Energy Is a Tough Challenge |
| C．Artificial Leaf Tuns Sunlight into Electric Power |
| D．Inexpensive Source of Electricity Is Finally Available |
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【推荐1】Everyone talks about the “five” senses of man.And it is true that we get our information about the outside from our sense of sight,hearing,smell,touch and taste.Researchers tell us that the sense of sight—our visual sense—gives us up to 80% of what we know about the world outside our bodies; while the other senses,the auditory (hearing),the olfactory (smell),the tactile (touch),and the gustatory (taste) bring into our brains information about the other 20% of what is happening.But there are two other senses that we cannot get along without,though they are little noticed.These are the senses of balance (平衡),without which we would act like a drunk after a heavy drink,and the kinesthetic sense(动觉),which gives us our ideas about our own motion (运动).
1. Which is the best title for this passage?| A．The Five Senses of Man |
| B．The Senses of Man |
| C．Senses and Information |
| D．Important Senses |
| A．about half of our information about the world |
| B．about 20% of our information about the world |
| C．80% of our information about the world |
| D．all the needed our information about the world |
| A．about half of our information about the world |
| B．about 20% of our information about the world |
| C．about 80% of our information about the world |
| D．all the needed our information about the world |
| A．is blind |
| B．is deaf |
| C．has no sense of taste and touch |
| D．has no sense of balance and motion |
【推荐2】The word“diary”comes from the Latin word“diarium”，which means“daily allowance”.It refers to a book for disconnected writings by date and is used for business notes，planning activities，keeping track of scheduled appointments，or documenting what has already happened.
In America，from the 1940s through the 1980s，a diary was thought of mostly as a way to privately express one’s deepest thoughts while keeping marks about the day.In those times，and even continuing on today，writing in a diary was like writing to a special friend.Many times，movies would show a teenage girl beginning to write in her diary while she said aloud，“Dear diary,…”What followed was a brief statement of the day，usually filled with emotion.
Those private reflections may have historical significance long after the author’s death.A diary kept by a young German Jewish girl by the name of Anne Frank provides us with invaluable lessons about history，for she documented her experiences while she hid from the Nazis during their occupation of the Netherlands in the World War II.Her diary became one of the world’s most widely read books and is the basis for many films.
Semuel Pepys，who lived during the 17th Century，is the earliest diary-keeper that is famous today.His diary is also an important documentation of history，for it gives personal insight into London’s Great Plague and the Great Fire.Pepys took diary writing from the realm of business to the individual.His diary is being published on the Internet，and it's interesting to note that there has been a new entry every day since January of 2003.It will continue over the course of several years to come.Reading his diary is fascinating，and it makes his life all the more real to us.
Today’s electronic version of the diary，the web log，or“blog”has once again stretched the diary to be much more than a personal account of the day’s events.There are blogs to document recipes，traveling，movies，independent news，product announcements，photos，and anything else that needs to be recorded over time.Search engines like Technorati.com have been created to keep track of the more than 112 million blogs that are currently public.In its newest replacement，the diary has become more popular than ever.
1. Generally what is a diary used for?| A．Taking business notes. | B．Planning activities. |
| C．Keeping daily happenings. | D．Confirming the appointments. |
| A．Kingdom. | B．Field. | C．Department. | D．Land. |
| A．To let us know the popularity of her diary. |
| B．To show us the invaluable lessons about the history. |
| C．To present her dramatic and interesting experience during the War. |
| D．To emphasis the importance of keeping diaries for historical purposes. |
| A．It has been more widely accepted by the public. |
| B．Technorati is the only search engine created for it. |
| C．The diary remains the same form but still popular. |
| D．Nothing but the individual daily events can be recorded. |
【推荐3】Your brain isn't necessarily the same age as the rest of you． Now， it may be possible to predict how quickly a person's brain will age throughout life based on tests taken when he or she is three years old．
A person's biological age may be a better indicator of their health than their real age． Brain age can be measured using brain scans and machine﹣learning to determine if a person's brain looks older or younger than the average healthy brain for people of the same age．
To find out if brain age might reveal anything about a person's health in midlife， Max Elliott at Duke University in North Carolina and his colleagues assessed the brains of 869 adults in New Zealand who have undergone regular medical and cognitive （认知的） testing since they were 3 years old．
When the volunteers， all aged between 43 and 46， underwent MRI brain scans， the team found that their brain ages ranged from 23 to 71． Those with older brain ages performed worse on tests of cognition， memory and IQ． The researchers also found that some people have a very advanced brain age but their bodies seem to be ageing slowly， and vice versa （反之亦然）． However， the team found that those who had the highest scores on cognitive tests when they were 3 years old went on to have the youngest﹣looking brains．
This suggests we might be able to tell who is at risk of accelerated brain ageing early in life． Researchers hope that predicting brain ageing earlier in life could allow treatments for conditions like dementia （痴呆） to be started sooner． This means treatments might have a better chance of working．
We don't yet have a way to treat brain ageing， but given the known benefits to the brain of healthy eating and exercise， these aren't a bad place to start．
1. What helps predict the speed of one's brain ageing？| A．One's health condition． |
| B．A test result at the age of 3． |
| C．The actual age of one's brain． |
| D．A machine for medical check． |
| A．To find out why people look older or younger． |
| B．To measure people's brain age at different stages． |
| C．To discover whether brain age can be measured by machines． |
| D．To explore the relationship between brain age and future health． |
| A．The influence of cognitive tests． |
| B．The procedure of Elliott's study． |
| C．The information about volunteers． |
| D．The findings of the brain research． |
| A．We should test our brain age earliest possible． |
| B．People suffering dementia can go on working． |
| C．Brain ageing could be predicted at an early age． |
| D．Healthy eating and exercise can cure brain ageing． |
【推荐1】One of the most traditional British holidays is the seaside holiday. Typically, families travel to British seaside towns.
In the late 1970s, air travel became affordable for the average family, and more and more British people started travelling abroad for their summer holidays. After all, the British weather isn’t very good, even in summer.
In the 1980s and 1990s, British young people became wealthier. They started to go abroad in groups. Once at their destination they socialised with other young people and had one long party.
British holidaying habits have begun to change, however. The UK now has a warmer climate than before, so people don’t always feel they need to go overseas. Also, the world seems a less certain place as interconnected economies (经济) rise and fall, which means that the cost of foreign holidays is less predictable than before. The domestic (国内的) tourism industry — when people go on holiday in their own country — is healthier than it has been in decades. UK newspapers have even invented a new word: a “staycation”.
In some ways, therefore, the UK has come full circle. There is now an increased appreciation among Britons for the diversity of the UK. It is not just the geography, which ranges from the flat fens (沼泽) of East Anglia to the valleys of Wales to the mountains of Scotland, which is diverse. And it is not just the diversity of climate-based activities on offer, which range from surfing in the warm southwest of England, to hillwalking and skiing in the north, it is also the diversity of the cultures in the UK that is beginning to be of interest to domestic tourists. People forget sometimes that there are different accents, languages, traditions, cuisines and peoples across all the parts of the UK.
1. Why do more British people take their holidays in their own country?| A．The Internet makes them closer. |
| B．They are wealthier and more sociable. |
| C．The global climate is getting much warmer. |
| D．The expense on foreign holidays is unsteady. |
| A．A vacation spent at home. | B．A healthier style of living. |
| C．A new way to spend holiday. | D．A fashionable tourism industry. |
| A．Flights of fancy. | B．Sun, sea and sand. |
| C．The length and width. | D．Footloose and fancy-free. |
| A．To prove the UK has diverse scenery. |
| B．To show the UK starts to discover itself. |
| C．To tell the development of the United Kingdom. |
| D．To explain why the British spend holidays inland. |
【推荐2】Is dark chocolate healthy? Yes，dark chocolate has compounds (化合物)that offer health benefits and can be enjoyed without guilt，even on a daily basis.But the amount matters，since too many bites can contribute to extra fat，sugar and calories and get rid of its health benefits.
Dark chocolate is rich in cocoa，which contains compounds known as flavanols(黄烷醇)．At high levels，cocoa flavanols have been shown to help lower blood pressure and the risk of diabetes. Dark chocolate has the highest amount of cocoa flavanols：milk chocolate has lens，and white chocolate has none.
But while cocoa flavanols in dark chocolate make it a healthful treat，they give it a biter flavor. Producers may process chocolate to make it more delicious，but doing so can remove some of these beneficial compounds，said Matt Hartings，an American professor. In spite of this，dark chocolate is still a healthier choice than milk chocolate，which tends to have more sugar. Additionally，cocoa powder contains minerals. So you can enjoy a piece of dark chocolate even after a meal. Just keep the following in mind.
First ，buy chocolate that has at least 60% cocoa.“Generally speaking，the higher the percentage，the more flavanols. These higherpercentage chocolates have the added benefit over the lower percentages and milk and white chocolates because they contain less sugar and less fat，” Hartings said.
Second，if possible，choose natural cocoa over Dutch processed cocoa，which is treated with an alkali (碱)．This gives chocolate a milder flavor but removes healthful flavanols.
And finally，to keep weight in check，limit to 30 grams of dark chocolate daily，or about 150 calories，
1. Dark chocolate is healthy mainly because of the existence of ．
| A．rich minerals | B．less sugar |
| C．cocoa flavanols | D．fewer calories |
| A．Something enjoyable. |
| B．A saltfree diet. |
| C．Food paid by others. |
| D．A cure for an illness. |
| A．Cocoa flavanols leads to high blood pressure. |
| B．White chocolate is good for health. |
| C．One can feel free to eat dark chocolate. |
| D．Alkali can affect flavanols' content. |
| A．To show his love for dark chocolate. |
| B．To promote the sales of chocolate. |
| C．To provide facts about dark chocolate. |
| D．To make a distinction among chocolates. |
【推荐3】Leonardo da Vinci was famous artist who was born in Italy. He was also a great inventor. Many of his inventions have become important in modern life. Although Leonardo hated war, he invented many different machines used for war. His most special invention was the machine gun, which was produced and used in war. Besides, Leonardo spent days thinking about how to save time. He developed ideas for something like cutting machines.
Leonardo was strange man. He never ate meat. That was very unusual in those times. He never published scientific discoveries. He usually used mirror writing, which looks like usual writing in a mirror, starting from the right side of the page and moving to the left side.
Only a few of his paintings are left today. Many paintings were not finished because he thought they were not perfect.
Leonardo was talented and creative. He was regarded as one of the most intelligent men in the world.
1. What’s Leonardo’s status besides an artist?| A．An actor. | B．A worker. | C．A farmer. | D．An inventor. |
| A．The cutting machine. | B．The machine gun. |
| C．The air conditioner. | D．The washing machine. |
| A．He never ate meat. | B．He never published scientific discoveries. |
| C．He used mirror writing. | D．He hated war. |
| A．Because many paintings were not finished. | B．Because many paintings were lost in war. |
| C．Because he burnt most of his paintings. | D．Because he had no time to paint. |
| A．Famous but not great. | B．Great but not famous. |
| C．Intelligent but not usual. | D．Talented but not strange. |
