【推荐2】Every November, Time magazine picks out what it calls “The 25 Best Inventions” of the year. Here, Teens has chosen some of the most interesting ones.

It’s hard to always keep coffee at the right temperature, especially in winter. It’s too hot to drink at first, but before we know it, it gets too cold and loses all its taste. The perfect level of warmth for a cup of coffee only lasts for 37 seconds, which makes the Ember Mug a great innovation. It keeps your coffee or tea at a certain temperature, anywhere between 45℃ and 62℃ once you set it through a smart-phone app.

TV cooking shows make cooking look so easy, but it’s almost impossible to get the recipes to cook the same as how the professionals cook. However, the Tasty One Top DIY cooking companion is here to help. Developed by Buzzfeed, the cooker can be connected to a smartphone app, which has more than 1,700 recipes and videos. You choose a recipe and the app will let the cooker know what to do. For example, it’ll tell you when to turn your steak or when to add certain ingredients.

Smart speakers from companies like Amazon and Xiaomi have added a lot of fun to our lives, but they’re still just faceless speakers. However, Jibo, developed by MIT professor Cynthia Breazeal, has brought smart technology to life. Said to be “the world’s first social robot for the home”, Jibo looks like a cartoon character. Inside its “head”, there are various sensors (传感器) and cameras, which allow it to recognize faces and speech. It can also set alarms, remind you of important things, tell you the weather and read news or messages from your friends and family.

【推荐1】If we want a fair shot at transitioning to renewable energy, we’ll need one critical thing: technologies that can change electricity from wind and sun into a chemical fuel for storage and vice versa. Commercial devices that do this exist, but most are costly and perform only half of the expectation. Now, researchers have created small lab-scale devices that do both jobs. If larger versions work as well, they would help make it possible—or at least more affordable—to run the world on renewables.

The market for such technologies has grown along with renewables: In 2007, solar and wind provided just 0.8% of all power in the United States; in 2017, that number was 8%, according to the U. S. Energy Information Administration. But the demand for electricity often doesn’t match the supply from solar and wind. In sunny California, for example, solar panels regularly produce more power than needed in the middle of the day, but none at night, after most workers and students return home.

Some companies are beginning to install massive rows of batteries in hopes of storing extra energy and balancing the financial sheet. But batteries are costly and store only enough energy to back up the power system for a few hours at most. Another option is to store the energy by transforming it into hydrogen fuel. Devices called electrolyzers do this by using electricity—ideally from solar and wind power—to break down water into oxygen and hydrogen gas, a carbon-free fuel. A second set of devices called fuel cells can then transform that hydrogen back to electricity to power cars, trucks, and buses, or to feed it to the power system. But commercial electrolyzers and fuel cells use different catalysts to speed up the two reactions, meaning a single device can’t do both jobs. The researchers must conquer this.

“They did a really good job with that.” says Sossina Haile, a chemist at Northwestern University in Evanston. Still, she holds the view that both her new device and the one from the O’Hayre lab are small laboratory demonstrations. For the technology to have a greater impact in society, researchers will need to scale up the button-size devices, a process that typically reduces performance.

【推荐2】In one high school biology class, almost four in every 10 low-income students would fail the course. But with some simple practices to reduce test anxiety(焦虑), researchers cut that number in half.

Christopher Rozek is a psychologist at Stanford University. He studies how stress and other things can affect leaning. Reducing test anxiety had raised test scores in several small studies, So Rozek and his team decided to test it on a larger scale. Rozek's group wanted to know if short stress-relief activities before an exam would affect a student's grade. They tested 1,175 biology students at a large, public high school in lllinois. At this school, a little more than half of low-income students fail their biology finals. Only 6 percent of high-income students fail.

They divide the students into four groups. One group spent 10 minutes free-writing about their fears. This was designed to clear the kids' heads so that they could then focus on the exam. Another group read how the body responds to stress and how these can actually help with attention. Then they answered reading comprehension questions. Students in a third group did both of these reading and writing activities. A fourth group, called the active control group, read a passage that told them to just ignore their worries.

Afterward, the students all took their final test in biology. A total of 205 low-income students did one or both stress-relieving activities. On average, these students scored higher on the exam than their classmates in the control group. Indeed, 82 percent of them passed the class. Only 61 percent of the lower-income students in the control group passed. It didn't seem to matter whether a student read or free-wrote about managing stress, or both. All methods worked equally well at helping students pass their tests.

Nearly all the high-income kids passed the class whether they did the activities or not. These students may be less nervous before exams. Or they may have already learned ways to deal with the stress, Rozek says.