What will power your house in the future？Nuclear, wind, or solar power？According toscientists at the Massachusetts Institute of Technology(MIT)in the US, it might beleaves—but artificial(人造的)ones.

    Natural leaves are able to change sunlight and water intoenergy. It is known as photosynthesis(光合作用). Nowresearchers have found a way to imitate this seemingly simple process.

    The artificial leaf developed by Daniel Nocera and hiscolleagues at MIT can be seen as a special silicon chip with catalysts(催化剂). Similar tonatural leaves, it can splitwater into hydrogen and oxygen when put into a bucket of water. The hydrogenand oxygen gases are then stored in a fuel cell, which usesthose two materials to produce electricity, located eitheron top of a house or beside the house.

Though the leaf is only about the shape of a poker card, scientistsclaimed that it is promising to be an inexpensive source of electricity indeveloping countries.“ One can imagine villages in India and Africa not longfrom now purchasing an affordable basic power system based on this technology, ”said Noceraat a conference of the American Chemical Society.

    The artificial leaf is not a new idea. The first artificial leafwas invented in 1997 but was too expensive and unstable for practical use. Thenew leaf, by contrast, is made ofcheap materials, easy to useand highly stable. In laboratory studies, Nocera showedthat an artificial leaf prototype(原型)could operatecontinuously for at least 45 hours without a drop in activity.

    The wonderful improvements come from Nocera's recent discoveryof several powerful, new andinexpensive catalysts. These catalysts make the energy transformation insidethe leaf more efficient with water and sunlight. Right now, the new leafis about 10 times more efficient at carrying out photosynthesis than a naturalone. Besides, the device canrun in whatever water is available；that is, it doesn'tneed pure water. This is important for some countries that don't have access topure water.

    With the goal to “make each home its own power station” and“give energy to the poor”, scientistsbelieve that the new technology could be widely used in developing countries, especially inIndia and rural China.

Yellowstone Weather

    Yellowstone National Park is at high altitude. Most of the park is above 7,500 feet (2,275 meters).

    Yellowstone's weather is unpredictable. In summer, it may be warm and sunny with temperatures in the high 70s. At night in any given month, the temperature may drop close to freezing. So it is best to come prepared for cold evenings and mornings, especially if you are camping or hiking. When you leave your campsite, please leave it prepared for possible thundershowers and wind.

    A sunny warm day may become fiercely stormy with wind, rain, sleet and sometimes snow. Without enough clothing, and easy day hike or boat trip can turn into a battle for survival.

    Hilary Smith belonged to a good family. But by the age of twenty, he had spent all the money the good old family had. He then had some trouble with the bank and was put in prison. He escaped from the prison and ran to Australia without delay.

    Hilary did not like Australia and Australia did not like Hilary. What he could do seemed to be one of two things: die or work. Then he remembered that he was not alone in the world. He had an aunt.

    She was his father's only sister, but his father used to say she brought no glory to the family. Hilary, of course, tried to discover what she had done. It seemed that she had failed to marry a nobleman. Instead, she had chosen a husband who was connected with "trade". Of course as soon as she became "Mrs. Parks", her brother considered her dead. Later on, Mr. Parks died and left her a lot of money; but that did not bring her back to life in her brother's opinion.

    Hilary discovered his aunt's address. Fortunately she remained faithful and honest to him even after she fell ill. So Hilary's star shone again, and soon he moved into her house and lived as comfortably as a sailor who had just reached harbor. He had only about six pence in his pocket.

    One thing was soon clear: his aunt was seriously ill, and nothing could cure her illness. Hilary was very worried. Fate had found a home for him, and was now going to throw him out of it. There was only one thing that could save him: her will.

    "Will?" she said, "yes, I have made one. That was when I was a girl and had not much money. I left all my money to some religious people."

    "Didn't you make another will when you were married?" Hilary asked.

    His aunt shook her head. "No," she said in a low voice, "There was no need. When I finally had a lot of money, I found I had no relations."

    On the next day he went to the public library and examined a book of law. It told him what he already believed. When a woman is married, an earlier will loses its value. A new will must be made. If no new will is made, the money goes to the nearest relation. Hilary knew that he was his aunt's only relation. His future was safe.

    After a few months had passed, Hilary's problems became serious. He badly needed money. He had expensive tastes, and owed a lot of money to shopkeepers. They trusted him because his aunt was rich, but the debt was terrible.

    Unfortunately his aunt did not want to discuss money matters at all. In the end they had a quarrel about the small amount of ten pounds. Hilary was not very angry. He began to wonder about a new problem. Was it kind to want his aunt to live any longer? Was it not better for her to die now? While he was considering what to do, his aunt told him that she was going to send for her lawyer. So she was going to make a new will, Hilary thought. She might leave all her money to someone else. Soon he reached a clear decision. He must do a great kindness to the poor old woman.

    One night when the old servant who had been nursing his aunt went off, he doubled the amount of some medicine. The total amount was too great and it could just put her to sleep forever.

    "Thank you," his aunt took the glass from his hand with a grateful look." I want, more than anything, to sleep, and never to wake up again. Is that what you wish, Hilary? Don't blame me if I have some doubts about what you intended to do. Sick people get these ideas, you know. One thing I ought to explain to you. Mr. Parks never married me. He already had a wife and couldn't marry again. That made your foolish father very angry with me...Well, if I am alive tomorrow, I shall make another will in your favor. If I die tonight, you'll get nothing...No, Hilary, don't try to take the glass away. If you do that, I shall know and I don't want to know. Good night, Hilary."

    Then, very carefully, she raised the glass to her mouth and drank.

    In the United States, when one becomes rich, he wants people to know it. And even if he does not become very rich, he wants people to think that he is. That is what "keeping up with the Joneses" is about. It is the story of someone who tried to look as rich as his neighbors.

    The expression was first used in 1913 by a young American called Arthur Momand. He told this story about himself. He began earning $ 125 a week at the age of 23. That was a lot of money in those days. He got married and moved with his wife to a very wealthy neighborhood. When he saw that rich people rode horses, Momand went horseback riding every day. When he saw that rich people had servants. Momand and his wife also hired a servant and gave big parties for their new neighbors.

    It was like a race, but one could never finish this race because one was always trying to keep up. The race ended for Momand and his wife when they could no longer pay for their new way of life. They had to move back to an apartment in New York City. Momand looked around him and noticed that many people do things just to keep up with rich lifestyle of their neighbors. He saw the funny side of it and started to write a series of short stories. He called it "Keeping up with the Joneses" because "Jones" is a very common name in the United States. "Keeping up with the Joneses" came to mean keeping up with rich lifestyle of the people around you. Momand's series appeared in different newspapers across the country for over 28 years.

    People never seem to get tired of keeping up with the Joneses. And there are "Joneses" in every city of the world. But one must get tired of trying to keep up with the Joneses because no matter what one does, Mr. Jones always seems to be ahead.

    Surely, given the near-universal use of home computers and smart devices(设备 )like smartphones and tablets, most of us would suspect that watching TV-seen as out dated or even old-fashioned by some-is on the decline. We probably would. And we would be wrong. A new study on screen time conducted by researchers from Robert Stempel College of Public Health Social Work have found that TV-watching has actually gone up since the moment when smart devices became widely available in 2014.

    "The findings are surprising as it feels like mobile devices are omnipresent, but the television still commands more eyeballs than its more advanced brothers and sisters" said Dr. Jenny Radskey" And there is a growing concern over the screen time of children, particularly very young children, for whom watching shows in front of screens is still the most common way to consume media."

    According to a study published in JAMA (The Journal of the American Medical Association) Pediatrics the increase in the amount of screen time for inns and toddlers(婴幼儿) is telling. Specifically, in 1997 children under the age of 2 spent 1.3 hours in front of TV per day on average, while children between the ages of3 and 5 did the same for 2.5 hours. By 2014, however, the latter group showed no significant change, while the former group more than doubled their time spent watching TV, clocking in at 3 hours per day.

    The research also shows that too much screen time before age 2 or 3 is associated with language development delays, ADHD, and learning difficulties. A child's brain develops rapidly during the first years, and young children learn best by interacting with people, not screens.

    Based on these findings, parents who worry about the excessive amount of time their children spend glued to their smartphones and tablets might do well to pay more attention to their littlest ones, for whom viewing time in front of the TV should be greatly cut down.