【推荐1】Berlin-based Green City Solutions believes its moss(苔藓)walls, called City Trees, which are about 4m² in size, can filter(过滤)up to 80% of pollution particles(微粒)out of the air, including the tiny ones linked to lung diseases.

The walls collect rainwater, which is pumped through a watering system to the plants using solar energy. These also drive fans to increase airflow through the plants. As a result, the company says its product filters 3. 500 m of air an hour, which is equal to the total amount of air breathed by 7,000 people in that time.

Alison Haynes at the University of Wollongong and her colleagues recently looked at how effectively moss and trees reduced pollution. They found that moss was up to four times better at trapping particles than the native Australian tree.

But this doesn’t mean moss walls will necessarily protect people from pollution at busy bus stops, says Zoran Ristovski at the Queensland University of Technology. In a small room, a moss wall only needs to filter a relatively small amount of new air each hour, but tens or hundreds of times this amount of air is pushed past by buses, he says. Therefore, a moss wall in a street is unlikely to make any difference.

Different solutions will be needed, says Ruby Michael at Griffith University. Where streets are crowded with tall buildings on both sides, she says, tree planting can backfire(适得其反)because trees can reduce airflow and therefore moss walls may be a better choice.

Cities are unlikely to rush to replace their trees just yet. “It’s important to remember that street trees provide a whole host of other benefits, including habitat for urban wildlife, shelter from the sun for people on the street, and reduction of urban heat islands,” says Michael.

【推荐2】When dogs get lonely, they like keeping themselves busy by making a big mess around the house and that doesn’t really sit well with their owners. That’s why one German radio host, who also happens to be a dog owner came up with the idea for a programme designed to relax dogs and make them feel like they aren’t alone.

When 30­-year­-old Stephan Stock, a radio host at RadioTon, in Germany’s Baden­Württemberg region, announced the creation of a programme aimed at dogs, everyone thought it was just a clever April Fools trick. However, it wasn’t. For the past three and a half months, Hallo Hasso has been pumping out music for lonely dogs both on the radio and online.

Stock says he was inspired to create the special programme by his pet dog, Layla, who would sometimes get so bored when left alone that she would keep herself busy by making a big mess around the house. He and his colleagues at RadioTon started researching what kind of music usually appeals to dogs, and learnt that it should have as little drum and electric guitar as possible, and should be very slow.

“It’s not about keeping dogs quiet,” Stock said about Hallo Hasso. “It’s more about the dog feeling he’s not alone.” He adds that Layla isn’t as restless since listening to Hallo Hasso, and has become relatively quiet, even letting him take a nap (打盹儿) to the music from the radio.

Hallo Hasso is only available in Baden­Württemberg, via radio, but if you’d like to see if it can calm your four­legged pet, the programme can also be accessed online here. Just press the “play” arrow at the top of the page and let the music work its magic. If this doesn’t work, there’s always Dog TV.

【推荐3】Peppered moth caterpillars (桦尺蠖毛虫)live north of the equator. But if you’ve never seen one, don’t feel bad: They’re experts at blending in (融为一体). Each caterpillar looks like the branch it stays on, straightening its body into a stick-like shape. It also changes its color to match the branch’s color, whether white, green or brown.

According to a paper published in Communications Biology, the caterpillars sense the color of their surroundings not only with their eyes but also with their skin.

Ilik Saccheri, an author of the paper, normally studies the adult moth. This requires keeping a lot of caterpillars around. Years of observation awakened his curiosity about their color-changing abilities. Each caterpillar hatches tiny and black, and in its early days is blown around by the wind. Once it falls on a plant, it must disguise itself to avoid being spotted by birds.

“I was a bit disbelieving that they could change that only using their eyes,” Dr. Saccheri said.

Amy Eacock, a graduate student in Dr. Saccheri’s lab decided to investigate. First, she tested the caterpillars’ eyes for light-sensitive proteins called opsins (视蛋白). “We did the skin as kind of a negative control,” said Dr. Eacock. “But then we found they were expressed in the skin as highly as they were in the head.”

That’s when she suggested blindfolding the caterpillars. The researchers could cover their eyes, place them on different-colored dowels (木钉) , and see if they still changed to match.

“I thought it was kind of a crazy idea,” Dr. Saccheri said. The blindfolding itself was a difficult task, involving black paint, a tiny paintbrush, a microscope and lots of patience, Dr. Eacock said. Caterpillars molt (蜕皮) several times over their lives, which required that they be blindfolded again frequently.

But Dr. Eacock persisted, eventually testing more than 300 caterpillars. Over and over again, the blindfolded caterpillars successfully changed color to blend in.

Many questions remain, but the behavior alone impressed the researchers. Dr. Eacock said, “I remember turning to Ilik one day and saying, ‘You know what? The caterpillars are cooler than the moths.’” “Yes. They’re pretty amazing,” Dr. Saccheri agreed.