【推荐1】A new property development in Austin, Texas is set to become the world’s largest community of 3D-printed homes. Scheduled to break ground next year, the project will feature 100 single-story houses with their roofs covered in solar cells. Printed on-site using advanced robotic construction and a concrete-based building material, each of the houses will take approximately a week to build.

According to ICON, a Texas-based construction firm specializing in 3D-printed structures, its technology is significantly faster and cheaper than conventional construction methods, partly because it requires less manual labor.

“Construction-scale 3D printing not only delivers homes faster and more affordably, but fleets of printers can change the way that entire communities are built for the better,” said Ballard, CEO of ICON. “The United States faces a deficit of approximately 5 million new homes, so there is an urgent need to swiftly increase supply without compromising quality, beauty, or sustainability and that is exactly the strength of our technology.”

Advocates believe that the method can cut waste and carbon dioxide emissions. The ability of 3D printers to construct buildings without formwork can significantly reduce overall use of the material which is responsible for about 8% of global CO2 emissions annually. A recent study in Singapore, for instance, found that constructing a bathroom unit using 3D printing produced almost 86% less carbon dioxide than conventional construction methods.

Critics have meanwhile pointed out that 3D concrete printing still relies on a non-renewable material, and that structures’ safety and stability are not specifically addressed by existing building codes.

Although ICON has yet to reveal prices for the project, Ballard claimed at a press conference that it could deliver a much higher-quality product to the housing market that is typically not available for low-income families. Hopefully, the technology can also be used to fight homelessness and may be employed during disaster relief.

“3D printing is not science fiction.” Ballard said at the time. “We have crossed that doorway from science fiction into reality. In the future, our bet is that this will be humanity’s best hope for a housing solution that matches our highest values and ideals.”

【推荐1】As the world approaches the second anniversary of the declaration of the Covid-19 pandemic by the World Health Organization(WHO), on March 11, more nations are rolling out, or are discussing the possibility of, fourth doses of coronavirus vaccine for their most vulnerable. In the United States, leading public health officials say they are “very carefully” monitoring if or when fourth doses might be needed.

Israel was the first nation to roll out fourth doses, announcing in December that adults 60 and older, medical workers and people with suppressed(抑制的) immune systems were qualified to receive the extra shot if at least four months have passed since their third dose. More recently, the Public Health Agency of Sweden announced last week that second booster doses are recommended for everyone 80 and older in the country. The United Kingdom’s Department of Health and Social Care announced Monday that an extra booster dose(加强剂量) of coronavirus vaccine will be offered in the spring to adults 75 and older, residents in care homes for older adults and immunosuppressed(免疫功能不全) people 12 and older.

In the US, health officials emphasized late last year that fourth doses were not yet needed and said it was too early to be discussing a potential fourth dose of coronavirus vaccine for most people. Now, the US Food and Drug Administration “is indeed continually looking at the emerging data on the pandemic and variants(变种) in the United States and overseas in order to evaluate the potential utility and composition of booster doses,” FDA spokesperson Alison Hunt wrote in an email to CNN on Friday.

She confirmed that although Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation, has noted that there is still much uncertainty as to how the pandemic may further evolve, he also has said it is possible that a fourth dose might be recommended as we move into fall. A fall timeline exist at the same time of the administration of flu shots, which could be convenient for people and makes sense scientifically because respiratory(呼吸的) viruses – like the coronavirus – tend to peak in the winter months that follow.

【推荐2】A small but shining silver lining: The corona-virus has quickened the shift to pedal power in Europe. The German Cycling Association (ADFC) reports that Germans across the country are spending twice as much time biking as they were before the COVID-19. There is growing demand for bikes and shared-bike subscriptions, and now even shortages throughout bicycle supply chain. For bike shops it's an unexpected boom. So much so that it requires cities to improve their biking facilities.

In unimagined numbers, bikes are starting to take the place of cars in our cities. It has increased 930 miles of new bike lanes (车道) in Europe, “muscling aside cars on Europe’s city streets,” according to European Cyclists Federation. Belgium, Denmark, and the Netherlands are pioneering fast lanes for riders. “Pop-up lanes” are being used for bikes in Berlin and Paris; Rome has painted new bike lanes, in each case taking away lanes from cars.

Women riders are reportedly another big factor in the biking transformation. E-bikes are, too. E-bikes use an onboard battery to boost power when the rider is going up a hill, or just needs a rest. E-bikes have removed “the sweat factor”. Who wants to show up to work or a party sweaty?

The European Cyclists’ Federation states that bikes are also strongly supported by European governments to cut carbon and increase the quality of their cities. European countries provide direct financial stimulation for cyclists.

At the end of April, France announced a 20 million Euro plan to promote cycling after the end of the lockdown. The plan includes 50 Euro vouchers (代金券) for the repair of a bike. Italy worked on a regulation for Covid recovery, by means of which 120 million Euro was set aside to cover 70% and up to 500 Euro of the price of conventional, muscle-powered and electric bikes.

【推荐3】A 13-year-old American boy on Saturday became the youngest climber to conquer Mount Everest, the world’s highest mountain.

Jordan Romero from Big Bear, California, climbed up the 8, 850-meter summit(峰顶) from the Tibetan side. On the same day, a Nepali(尼泊尔的)man, Apa Sherpa, broke his own world record of climbing Everest when he reached the summit for the twentieth time. Apa Shepa’s team set off from Nepal’s capital, Kathmandu, last month, heading for the base camp(大本营) on the Chinese side of the mountain.

“The team has just called in and believe that they are standing on top of Mt. Everest, ” Romero’s blog said. “Their dreams have now come true. Everyone is happy. ”

The climbing has put Romero one step closer to reaching his goal of climbing the highest mountains on all seven continents (大洲). “It is just a goal，” Romero said. He had already climbed five peaks (高峰), and needs to climb only Vinson Massif, the highest peak in Antarctica, to hit his goal.

The youngest person before to climb Everest was 16-year-old Temba Tsheri Sherpa of Nepal. Romero climbed together with a team including his father Paul and three local guides. He wanted to pick a small piece of rock from the top of the world and wear it in a necklace.

While Nepal insists that anyone planning to climb Mount Everest must beat least 16, China does not have any age restrictions (限制). Some mountain climbers haven’t agreed with the Romero family for letting him try it but his father said the climbing from the Chinese side is less dangerous.

【推荐1】Emmanuel Mendoza, a college student, is currently running a study at Texas A&M University, where he’s mixing simulated (模拟的)Martian (火星的) soil and frass(粪便)from fly larvae(幼虫)to find just the right recipe for growing plants on Mars.

The seed of this idea was planted when Mendoza was in middle school, watching Ridley Scott’s 2015 film The Martian, in which Mark Watney becomes stuck on the planet and grows potatoes to survive. “That got me really interested in what nutrients or what soil structure Martian soil has that we could potentially take advantage of, ”Mendoza said.

Now, he’s running an experiment growing English peas in simulated Martian soil. “I definitely considered potatoes like Mark Watney, ”he said. “But the fact was that I couldn’t necessarily get the data I wanted out of them. ”

He wanted to be able to measure plant growth as it occurred throughout his experiment. Since potatoes grow underground, he’d only be able to collect data once they were done growing. In the end, Mendoza chose to grow English peas because they’re self-pollinating(自花传粉), grow fairly quickly and he can see the shoots climb.

Martian soil, though it does contain other essential nutrients, isn’t exactly ideal for plants from Earth. It tends to be rocky and lacks the right organic (有机 的)matter. Here’s where the larvae come in. Mendoza turned to the larvae of black soldier flies, which produce a waste known as frass. “They can break down almost any biomatter and turn it into really useful matter, “Mendoza said. “And then you can use the frass as a nutrient alternative to soil.”

For this experiment, Mendoza mixed different percentages of simulated Martian soil and frass to see what best supported growing English pea plants. Now, he said he’s seeing growth across all his plants—even the ones growing in 100%simulated Martian soil.

【推荐3】Maybe you’ve wondered what you would hear if plants could speak. A stream of gossip from the roses? Wise whispering from the branches of an old tree? A faint, high-pitched cry of terror when your older brother takes out the lawn mower(割草机)?

Ariel Novoplansky, an ecologist in Israel, is studying how plants communicate with each other. To listen in, he set up a kind of telephone game among plants in his lab. Experiment used pea plants standing in rows of containers. The center plant in each row was the target: Scientists would stress out that plant and see whether the plants on either side of it picked up any alarm signals.

The pea plants had been grown with two main roots. On one side of the stressed plant, each plant had one root in its own pot and the other reaching into a neighbor’s pot. The central plant connected to its closest neighbor, which connected to another neighbor, and so on down the line. On the other side of the stressed plant, all the plants kept their roots in their own pots unconnected to their neighbors. Then the scientists dried up the soil of the central target plant, creating a drought.

Within 15 minutes, the dried-out plant reacted the same way it would in nature: it had closed up the tiny pores(气孔) on its leaves to save water. What’s amazing is that the central plant’s closest neighbor with connected roots had also closed up its leaf pores. And after an hour, the message had traveled down the whole row of connected plants. On the other side of the pea chain, where the plants’ roots weren’t connected, all their pores stayed open. This means the warning signal traveled from the stressed plant’s roots through the soil.

Dried-out roots aren’t the only talkative plant parts scientists have discovered. When sugar maple trees are damaged, they send signals through the air telling their neighbors to produce bad-tasting chemicals. When caterpillars chew on corn leaves, nearby corn plants also make more self-defense molecules(分子). The plants around us may not be speaking with any volume, but they are saying plenty.