Dandelion (蒲公英) seeds can travel for miles before finally floating down and settling somewhere new. Researchers recently discovered how the plants decide to spread. “We noticed that the dandelion parachute (降落伞) is closed in foggy mornings but then open again when the sun is up during the day,” according to Naomi Nakayama, a researcher of bioengineering. “The dandelion uses a bunch of hairs to improve air drag and aid its flight. Unlike insects or birds, they don’t need any energy input to fly a long distance- even hundreds of kilometers—they simply catch the wind.”

Researchers discovered the parachutes open and close using what they say is like an actuator (触动器), a device that changes energy and signals into movement. But this actuator doesn’t use any energy. The middle of the dandelion’s parachute is able to sense the amount of humidity (湿度) by absorbing water molecules (分子) in the air. Using signals about humidity information, they either open their parachutes and fly off or they close them and stay where they are.

“The center of the parachute changes its shape, moving the hairs altogether in harmony,” Nakayama says. “It’s basically a sponge made of no-longer living plant cells, which are arranged in a tube empty inside. The inner side and the outer side swell with water to different degrees, and that drives the movement.”

Knowing what causes dandelions to spread their seeds could help scientists learn how they deal with climate change. They say understanding the response could help researchers design new soft robots, which are those made from flexible materials that imitate soft bodies. “How plants move their body parts are different from animals and a simple, localized expansion could be enough to move arms,” Nakayama says. “Movement of a few arms has been achieved, but this is the first of many arm actuators. It is simple in design, so there is a lot of space for biomimicry (仿生学)”.

There have been many attempts to create an all-plastic bike. However, most have never made it past the beginning stage. Igus, a Germany-based company of high-performance plastics, and Dutch start-up MTRL aim to change that with the igus:bike — the world’s first city bike crafted almost totally from recycled plastic.

Igus CEO Frank Blasé first got the idea while vacationing on a Florida beach. A conversation with workers at a rental company made him aware of the challenges of maintaining beach bicycles. The long-term exposure to sand, wind and saltwater caused the bikes to rust (生锈) rapidly. Many had to be replaced in as little as three months.

The igus: bike was uncovered at a German trade show. It can be left outdoors in all weathers and does not require lubricant oil to reduce friction (摩擦) between parts. Since it does not attract sand, dust or dirt, the bike can be cleaned with a garden water pipe in seconds. Currently, 90 percent of the igus:bike is made using plastic. This includes the bicycle’s hard but lightweight frame, bearings, pedals, and wheel rims.

The igus:bike will also help reduce the world’s plastic pollution. The company says a single adult bike gives new life to about 35 pounds of single-use plastic that would have entered our landfills or waterways. For example, the first prototypes were made from old fishing nets. MTRL says it is planning to set producing facilities near plastic landfills around the world.

“From ocean plastics to plastics from other sources, the igus:bike has what it takes to become a high-tech environmental product,” says MTRL co-founder Benjamin Alderse Baas.

The plastic bikes are expected to come onto the market in early 2023. An adult model, made from recycled plastic, will cost about €1,400. A slightly cheaper version made using new plastic and an electric bike are also in the works. Igus also plans on sharing its technology with other bicycle producers. “We want to enable the bicycle industry to produce plastic bikes,” says Blasé.

Microscopic particles (微观粒子) from outer space are also called space dust. They’re in the dirt on the ground and on your roof. They may discomfort your nose. They have settled all over our planet.

Despite their widespread presence, finding space dust isn’t easy. One place that the particles show up more easily is Antarctica. Around a decade ago, Matthew Genge at Imperial College London spent seven weeks searching for and collecting dust there.

The disadvantage of collecting dust from Antarctica is the high cost and complications of travelling there. That’s why Penny Wozniakiewicz of the University of Kent in the UK has focused on her research closer to home. The key is to collect material from a fairly undisturbed spot. She seeks the rooftops of old buildings in the UK as the source of her samples.

She focuses on these roofs because they are old and more untouched than modern buildings. What’s more, historic buildings usually have well-kept records that indicate when conservation and cleaning have been done. That makes it easier to determine how long space dust has been collected and gives researchers insight into what other particles might be present in the dust they collect. This allows them to more efficiently remove the Earth stuff, and focus on the space stuff.

“The idea is to actually take something you can barely see on your finger, and then make it much bigger so you can hold it in your hand,” says Wozniakiewicz. Each year, approximately 100 billion particles of space dust land on Earth, carrying secrets from outer space and offering glimpses into the formation of planetary systems. These particles not only contain water but also organic molecules (有机分子); they potentially serve as the building blocks for life on Earth. Space dust could, therefore, tell scientists about the complex relationship between these celestial bodies (天体) and Earth. It acts as a bridge, connecting us to the wider space.