An interesting study posted on Facebook recently shows how men and women develop new interests as they mature(成熟).

    While women tend to take exercise seriously from the age of 34, men will wait until their 45th birthdays before working hard to get in shape.The average woman spends more time talking about sports, politics, career and money as she gets older.

    Women's interest in books reaches its peak(顶峰) at the age of 22, while that of men does so when they are in their 50s.

    Men start to change their focus from the workplace to other things after age 30, while women do not do so until eight years later. Both, however, care most about fashion at age 16.

    The research used anonymous(匿名的) data donated by thousands of Facebook users, recording the statuses, 'likes' and 'interests' they had posted on their profiles.

    It found the average woman talks about television most at 44, while men peak much younger, at age 31.

    Men are also most likely to see a film in a cinema at age 31, while women go out to see films most when they are only 19.

    Men are most interested in travel at 29, women at 27, while women talk most about food and drink at 35, and men at 38.

    And if you are middle aged, a safe topic for any audience is the weather, which is a key interest for many as they approach 60.

    Stephen Wolfram, the British scientist who carried out the research, says, “It's almost shocking how much this tells us about the changes of people's typical interests.

    “People talk less about video games as they get older, and more about politics.”

    Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri(MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.

    “To provide enough power, we need certain methods with high energy density (密度)”，said Jae Kwon, assistant professor of electrical and computer engineering at MU. “The radioisotope (放射性同位素) battery can provide power density that is much higher than chemical batteries.”

    Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro/nanoelectromechanreal systems (MNEMS) Although nuclear batteries can cause concerns, Kwon said they are safe.

    “People hear the word 'nuclear' and think of something very dangerous,” he said, “However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems.”

    His new idea is not only in the battery's size, but also in its semiconductor(半导体). Kwon's battery uses a liquid semiconductor rather than a solid semiconductor.

    “The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure(晶体结构) of the solid semiconductor,” Kwon said, “By using a liquid semiconductor, we believe we can minimize that problem.”

    Together with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, Kwon is working to build and test the battery, In the future, they hope to increase the battery's power, shrink its size and try with various other materials. Kwon said that battery could be thinner than the thickness of human hair.

    There is an English saying that “Laughter is the best medicine.” Until recently, few people took the saying seriously. Now, however, doctors have begun to look into laughter and the effects it has on the human body. They have found that laughter can really improve people's health.

    Tests were carried out to study the effects of laughter on the body. People watched funny films while doctors checked their hearts, blood pressure, breathing and muscles. It was found that laughter has similar effects to physical exercise. It increases blood pressure, makes the heart beat quicker and makes people breathe deeper; it also works on several groups of muscles in the face, the stomach, and even the feet. If laughter exercises the body, it must be beneficial(有益的).

Other tests have shown that laughter appears to be able to reduce the effects of pain on the body. In one experiment doctors produced pain in groups of students who listened to different radio programs. The group that tolerated（忍耐）the pain for the longest time was the group which listened to a funny program. The reason why laughter can reduce pain seems to be that it helps to produce a kind of chemical in the brain which diminishes both stress and pain.

    As a result of these discoveries, some doctors in the United States now hold laughter clinics(诊所), in which they help to improve their patients' condition by encouraging them to laugh. They have found that even if their patients do not really feel like laughing, making them smile is enough to produce beneficial effects similar to those caused by laughter.

    One February afternoon, Jesus Delgado was on break behind T2 Tacos, where he works as a cook, when he heard a commotion(骚动). He ran to the front of the Los Angeles Taco stand and saw a man and a woman arguing. She was screaming for help and had two young boys at her side. All of a sudden, the man hit her in the mouth, seized the smaller boy, and ran down the street.

    "I followed my judgement and chased him." Jesus, 35, told the Argonaut newspaper. The older boy ran in the other direction to get help. A group of teenagers who had witnessed the attack assisted the woman, Lauren Kornacki, and called 911. She told them that she was the boys' babysitter.

    Within a few blocks, Jesus caught up to the man, Andron Gazarov, 33. They fought, and Jesus wrestled (抢夺) the young boy from Gazarov's arms. Then Gazarov threw himself onto the sidewalk. "He was yelling at me that the kid didn't belong to me. I was telling him the kid didn't belong to him," Jesus told the Argonaut.

    Minutes later, Los Angeles police officers arrived and arrested Gazarov, who was charged with kidnapping, attempted kidnapping, and attack. He faces up to 12 years in prison, if convicted (定罪). The kids, Brendan O'Brien, 6, and Grady O' Brien, 4, were unharmed.

    The next night, the boys' father, Tom O'Brien, went to the Taco stand to thank Jesus for his actions. He also started an online fund to help Jesus pay the medical expenses for his special-needs daughter. By May, more than $27,000 had been raised.

    People need to relax and enjoy themselves. One way they can have a good time is to watch a baseball game or another sports event. Even thousands of years ago, groups of people gathered to watch skilled athletes (运动员).

    Over 2000 years ago in Greece, certain days in the year were festival days. These were holidays when people stopped work and enjoyed themselves. They liked to watch athletes take part in races and other games of skill.

The most important festival was held every four years at the town of Olympia. It was held in honor of the Greek god Zeus (宙斯). For five days, athletes from all parts of the Greek world took part in the Olympic Games. At the Olympic Games, people could watch them box, run, jump and so on. There was a relay race between two teams of men in which a lighted torch (火矩) was passed from runner to runner. The Olympic Games were thought to be so important that cities which were at war with one another had to stop fighting. People were allowed to travel to the games safely. Thousands of people came to Olympia from cities in Greece and from her colonies (殖民地) in Africa, Asia and Italy. They met as friends to cheer their favorite athletes and to enjoy themselves.

The periodic table of elements is a common sight in classrooms，campus hallways and libraries. The mode periodic table arranges the elements by their atomic numbers and periodic properties（周期性）. Several scientists worked over a century to assemble the elements into this format. 

In 1789，French chemist Antoine Lavoisiertried grouping the elements as metals and nonmetals. Forty years later，German physicist Johann Wolfgang Dobereiner observed similarities in physical and chemical properties of certain elements. He arranged them in groups of three in increasing order of atomic weight and called them triads，observing that some properties of the middle element，such as atomic weight and density，approximated the average value of these properties in the other two in each triad. 

A breakthrough came with the pu blication of a revised list of elements and their atomic masses at the first international conference of chemistry in Karlsruhe，Germany，in 1860. They concluded hydrogen would be assigned the atomic weight of 1 and that the atomic weight of other elements would be decided by comparison with hydrogen. For example，carbon，being 12 times heavier than hydrogen，would have an atomic weight of 12. 

In 1869，Russian chemist Dmitri Mendeleev created the framework that became the moder periodic table，leaving gaps for elements that were yet to be discovered. Mendeleev predicted the properties of some undiscovered elements and gave them names such as"eka-aluminum"for an element with properties similar to aluminum. Later "eka-aluminum"was discovered as gallium. 

German chemist Lothar Meyer produced a version of the periodic table similar to Mendeleev's in 1870. He left gaps for undiscovered elements but never predicted their properties. The Royal Society of London awarded the Davy Medal in 1882 to both Mendeleev and Meyer. The later discovery of elements predicted by Mendeleev verified（证实）his predictions and his periodic table won universal recognition. In 1955 the 101st element was named mendelevium in his honor. 

On UNESCO website，it wrote，"The Periodic Table of Chemical Elements is more than just a guide or catalogue of the entire known atoms in the universe；it is essentially a window on the universe，helping to expand our understanding of the world around us. "