Bees and other pollinators（传粉者）  use smells to track down fresh flowers. Air pollutants can weaken those scents（气味）.  Scientists had worried this might make it harder for some pollinators to find a meal.

    Many animals help pollinate plants. Species that do this include bees, butterflies, etc. But for many reasons, the pollinators available to help plants in this way are decreasing. Scientists think a loss of habitat（栖息地）can be one factor. Diseases and exposure to poisonous chemicals also count.

    Jose Fuentes points to air pollution as another possible factor. He's an atmospheric scientist at Pennsylvania State University. In an earlier study, he showed some air pollutants could weaken or destroy scents emitted(发出)by flowers.

    Searching for a meal leaves pollinators out in the open and at risk of becoming other animal's lunch. And any time spent hunting food is time away from their duties back home, like protecting a hive（蜂巢）or nest, explains T'ai Roulston. He's an insect biologist at Virginia University. Roulston worked with Fuentes on the new study.

    In the study, the researchers focused on five kinds of representative scent molecules(分子)plants emit. One molecule they looked at, for example, is called beta-myrcene. Many flowers give off this chemical into the air.  Normally, this gas can travel some 800 meters from its flower source. But in polluted air, this same molecule could travel only half as far.

    Worse still, air pollution might do more than just weaken scent plumes（气味烟云）．Chemical reactions between air pollutants and plumes may transform the flowers' smells, creating new scents. And these scents may be unrecognizable to pollinators.

    That's certainly Fuentes' concern.  So, he says his next research project will look at how insects handle any new flower scent. "It's possible that some insects will change ways to detect and use these new molecules to find food," he says.

    You may have seen many pumpkins in posters and TV shows recently since Halloween came on October 31.

    Lanterns made of pumpkins, also known as jack-o'-lanterns, are often seen during Halloween. Many people in the U.S. like to make them and put them in front of their houses. People hollow out（挖空）a pumpkin, carve a face on one side and place a candle inside to make the pumpkin glow. The lanterns can look funny or scary.

    This is not the only way in which pumpkins are part of American culture.

    During the Thanksgiving holiday, pumpkin pie is a common food. It is made from pumpkins and has some delicious spices to give it a nice flavor. People often put some cream on top of it before serving it. It is one of my favorite things to eat during Thanksgiving.

    There is also “pumpkin chucking”. It's a competition where people build machines to throw pumpkins through the air. The person whose pumpkin flies the farthest wins the competition. The world record for pumpkin chucking was set in Utah in 2010. The distance for that world record was about 1.69 kilometers!

    Finally, there are also pumpkin growing contests. For these contests, farmers try to grow the biggest pumpkins they can. The person who has the biggest pumpkin will win the first prize.

    When we want to tell other people what we think, we can do it with the help of words. We can also do it in many other ways, too. Sometimes we move our heads up and down when we want to say "yes", and we shake our heads when we want to say "no". Some people can't hear or speak. They talk with the help of gestures（手势）. People from other countries often have to do it if they don't know your language.

    Here is a story. An American was once having his holiday in Italy, but he could not speak Italian. One day he went to a restaurant and sat down at a table. When the waiter came, the American opened his mouth, put his fingers in it and took them out again. In this way he wanted to say "Bring me something to eat". The waiter soon brought him a cup of tea. The American shook his head and the waiter understood that he didn't want tea. So he took it away and brought him a glass of milk. The American shook his head again. He was very hungry now and looked sad. He was just going to leave the restaurant when another man came in. When this man saw the waiter, he put his hands on his stomach(胃). In a few minutes there was a large plate of bread and meat on the table in front of him.

    Cao Yuan, a PhD student from China, had two papers published on strange behaviour in atom-thick layers of carbon that have opened up a new field of physics.

    Pablo Jarillo-Herrero's group at MIT was already layering and rotating (旋转) sheets of carbon at different angles when Cao joined the lab in 2014. Cao's job was to find out what happened when one graphene (石墨烯) sheet was twisted only slightly wiht respect to the other, which one theory predicted would thoroughly change the material's behaviour.

    Many physicists doubted the idea. But when Cao set out to create the subtly twisted stacks, he spotted something strange. Exposed to a small electric field and cooled to 1.7 degrees above absolute zero, the graphene—which ordinarily conducts electricity—became an insulator. That by itself was surprising. But the best was yet to come: with a slight change to the field, the twisted sheets became a superconductor, in which electricity flowed without resistance.

    The ability to get atom-thick carbon into a complex electronic state through a simple rotation now has physics demanding to engineer exciting behavior in other twisted 2D materials. Some even hope that graphene could shed light on how more-complex materials superconduct at much higher temperatures. "There are so many things we can do," says Cory Dean, a physicist at Columbia University. "The opportunities at hand now are almost irresistible."

    Hitting graphene's “magic angle”—a rotation between parallel sheets of around 1.1°—involved some trial and error, but Cao was soon able to do it reliably. His experimental skill was extremely important, says his supervisor Jarillo-Herrero. Cao pioneered a method of tearing a single sheet of graphene so that he could create a stack of two layers, from which he could then fine-tune alignment (微调校准).

    Cao loves to take things apart and rebuild them. A heart, he is “a tinkerer”, his supervisor says. On his own time, this means photographing the night sky using homemade cameras and telescopes—pieces of which usually lie across Cao's office. "Every ime I go in, it's a huge mess, with computers taken apart and pieces of telescope all over his desk," says Jarillo-Herrero.

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    NAIROBI­Tin Tin, a Chinese restaurant located in central Nairobi, has been serving local Kenyans for nearly four decades with its delicious dishes and unique cultural background.

   "This is a restaurant definitely worth a try," said Steven, a local resident in his 30s. "It has provided Chinese food since my grandfather's time."

    According to Henry Tin, the restaurant owner, Tin Tin was established in 1978 at the heart of the Nairobi Central Business District, upholding Chinese cuisines while adapting to Kenyan preferences.

    For years, it has become a defining part of the city's landmark­Kenya International Conference Center­attracting lots of office workers nearby and even presidential customers.

   "The former president of Kenya, Moi, was a very good customer for us. He came almost always in cash. Then former president Mwai Kibaki and now president Uhuru. They all like to enjoy our food," Tin said.

    Danis, an office worker of an insurance company near the KICC says he is a frequenter of the restaurant.

   "It is the only Chinese restaurant in the highly competitive downtown area. Besides, its food has been adapted to our taste," Danis said, "My favorite dishes are fried shrimp and fried pork, which you can also find in a Kenyan restaurant."

   "High­quality food consistently served over the decades has helped maintain loyal customers," Enoch Kivunaga said, at Tin Tin.

   "My experience depends on the customers. If I cook good food, they always come back, whether they are presidents or ministers," he said.

    Tin said he speaks Swahili well and perfectly pronounces local names, which shows the Chinese culture and its Kenyan counterpart are quickly combining. "I am a Kenyan Chinese. I love both great countries."