【推荐1】Once small farmers in Masii, a remote village in Kenya, have picked their crops, all they can do is wait until a buyer trucks through. The system works fairly well for beans and corn, but mangoes-the area’s other main crop-spoil (腐烂) more quickly. If the trader is late, they rot.

However, a simple coating could change that. A company, SmartTech, has created a product that doubles the shelf life of fresh produce, enabling farmers to access far-off, larger markets. More time for fresh produce on grocers’ shelves also means less food waste-a $2.6 trillion problem, according to the United Nations’ Food and Agriculture Organization (FAO).

James Rogers, CEO of SmartTech, wanted to solve the problem for food much in the same way that oxide barriers preventing rust (锈) have achieved for steel. Fortunately, researchers have found when plants made the jump from water to land, they developed cutin(蜡质), a barrier which is made of fatty acids that link together to form a seal around the plant, helping keep water in.

The cutin was such a grand strategy that today you’ll still find it across the plant kingdom. SmartTech discovered through researches that an orange can last longer than a strawberry not so much because of the thickness of its skin, but because of the difference in the arrangement of those cutin molecules (分子)on the surface. After extensive trials, Rogers and his team developed a natural and tasteless protective coating from plant material-stems, leaves and skins. The product extends the sweet spot between ripening and rot. And best of all, the treated produce doesn’t require refrigeration.

“SmartTech has huge potential to turn poor farmers in Africa into commercial farmers,” says Rogers. “That means more money in pockets, and more food in stomachs.” But whether the company can cost-effectively reach small farmers in far-off areas still remains a challenge.

【推荐3】On September 7, 1991, the costliest hailstorm (雹暴) in Canadian history hit Calgary’s southern suburbs. As a result, since 1996 a group of insurance companies have spent about $2 million per year on the Alberta Hail Suppression Project. Airplanes seed threatening storm cells with a chemical to make small ice crystals fall as rain before they can grow into dangerous hailstones. But farmers in east-central Alberta — downwind of the hail project flights — worry that precious moisture (水分) is being stolen from their thirsty land by the cloud seeding.

Norman Stienwand, who farms in that area, has been addressing public meetings on this issue for years. “Basically, the provincial government is letting the insurance companies protect the Calgary-Edmonton urban area from hail,” Mr. Stienwand says, “but they’re increasing drought risk as far east as Saskatchewan.”

The Alberta hail project is managed by Terry Krauss, a cloud physicist who works for Weather Modification Inc. of Fargo, North Dakota. “We affect only a very small percentage of the total moisture in the air, so we cannot be causing drought.” Dr. Krauss says. “In fact, we may be helping increase the moisture downwind by creating wetter ground.”

One doubter about the safety of cloud seeding is Chuck Doswell, a research scientist who just retired from the University of Oklahoma. “In 1999, I personally saw significant tornadoes form from a seeded storm cell in Kansas,” Dr. Doswell says. “Does cloud seeding create killer storms or reduce moisture downwind? No one really knows, of course, but the seeding goes on.”

Given the degree of doubt, Mr. Stienwand suggests, “It would be wise to stop cloud seeding.” In practice, doubt has had the opposite effect. Due to the lack of scientific proof concerning their impacts, no one has succeeded in winning a lawsuit against cloud-seeding companies. Hence, private climate engineering can proceed in relative legal safety.

【推荐1】An American cancer survivor has become the first person to swim across the English Channel four times on end.

Sarah Thomas, 37, completed the great achievement on Tuesday after over 54 hours of swimming. Her record-breaking achievement came just a year after she completed treatment for breast cancer(乳腺癌).

In a video on Facebook, a small group of people could be seen cheering on the swimmer from Colorado as she made her final arrival to beach at Dover. Supporters congratulated Mrs. Thomas on her non-stop swim, handing her chocolate and other gifts. In the video, Mrs. Thomas admitted to feeling “a little sick” but said she had been encouraged to keep going by her husband and her team.

Before the start of her challenge, Mrs. Thomas wrote that she was “fearful” and admitted she was “going to need some luck”.

In a Facebook post made on Saturday, she dedicated(奉献) the swim “to all the survivors out there”, adding, “This is for those of us who have wondered hopelessly about what comes next, and have overcome the pain bravely.”

After her swim, Mrs. Thomas said, “I’m really tired and I’m losing my voice from all the salt water.” Asked what the worst part of her challenge was, she said, “Probably dealing with the salt water over two days. It really hurts your throat, your mouth and your tongue.” She praised her support team for helping her stay strong, adding that she was very prepared for the weather, currents(k it) and cold water. “I feel just mostly stunned right now. I just can’t believe that we did it.”

【推荐2】Anyone eager to view from high the cityscapes of Guangdong, a province in southern China, may soon be able to do so from the cabin of a flying taxi. On October 13th the Civil Aviation Administration of China (CAAC)awarded a “type certificate”, a crucial piece of aviation paperwork, to the world’s first electric vertical take-off and landing (eVTOL) taxi. And in case that does not sound futuristic enough, the small two-seater, called the EH216-s, was also cleared to fly without a pilot on board.

The EH216-S is made by EHang, a company based in Guangdong. It looks like a scaled-up consumer drone (无人机) with a passenger bubble mounted on top. Propulsion (动力) is provided by 16 small rotors (转子), mounted on the tips of eight arms that fold away when the vehicle is not in use, allowing it to park in small spaces.

The CAAC gave its approval after EHang had conducted more than 40,000 test flights, including with volunteer passengers in 18 cities across China. It also subjected the EH216-S to structural analysis and crash tests, and checked its ability to keep flying if one of its rotors fails. Regulators also inspected the wireless network which EHang uses to link its flying taxis to a control centre on the ground. That allows backup pilots to land an aircraft by remote control if there is a problem.

EHang says its pilotless eVTOLs will be quieter than helicopters, their closest cousins, and much cheaper to operate, thanks in part to the ability to swap (交换) out an expensive pilot, for a second paying passenger. Performance, though, will be limited, at least at first. The EH216-S has a range of about 30 km, and a speed of up to 130 kph. The firm thinks that doing away with pilots will make things safer too. A computer’s attention never wavers (动摇). And flying is, in many ways, much easier to automate than driving, for there are fewer obstacles and unexpected situations to navigate.

EHang has ambitions beyond China, too. The firm’s closest competitors are Volocopter, a German company, and a pair of Californian firms, Joby Aviation and Archer Aviation. All three are conducting test flights of piloted eVTOLs of various designs.

【推荐3】A woman who illegally entered Yellowstone National Parkon May 12 has suffered burns after accidentally falling into a thermal feature (热景观) near its Old Faithful Geyser, officials said. The park has been closed to all visitors since March 24 due to safety precautions amid the coronavirus pandemic(新冠病毒大流行).“Water in hot springs can cause severe or fatal burns, and hot water underlies most of the thin, breakable surface around hot springs,” the park advises on its website. “Hot springs have injured or killed more people in Yellowstone than any other natural   feature.”The woman, who is yet to be identified, was backing up while taking photos near the famous tourist attraction and fell into a hot spring or hole where hot gases emerge, according to park spokeswoman Linda Veress. Even with her injuries, she managed to hop back in her vehicle and drive about 50 miles until park guards stopped her. She was then sent to a burn center at a hospital in Idaho.

Visitors are advised to stay on the boardwalks near Yellowstone’s often boiling or acidic thermal features, which include geysers, hot springs, steam vents, and mud pots. This year, two tourists were sentenced to 10 days in prison for trespassing at the hot spring last September after they were caught walking “dangerously close” to the spout of the legendary geyser ( 间 歇 泉 ) without permission and taking photos on their cellphones.

“Thermal area safety is an extremely important part of any trip to Yellowstone. We ask visitors to take the Yellowstone Promise before coming to the park and to read the park visitor guide for more information on safety, rules, and regulations,” a spokesperson said following the incident last year. At times, tourists have taken risks off the designated walkways before being injured or killed. Last fall, a man who was walking off a boardwalk near Old Faithful at night fell into a hot spring, suffering serious burns. Back in June, a 23-year-old Oregon resident fell into a superheated, acidic mud pot and died. His remains couldn't be recovered.

Yellowstone is announcing plans for a phased reopening on May 13.The incident remains under investigation, Veress said.