Don’t throw away used masks, you can mix them with cement to build a building!

Welcome to watch the science of the week. This week you will see: ① A new idea for mask recycling; ② A small device that flies into the sky; ③ A small spider kicks away the object and ejects to escape; ④ A speaker as thin as paper; ⑤ A safety warning that is unsafe.

Mask concrete

How to deal with the growing piles of discarded masks? Researchers at Washington State University have come up with a new idea: recycling them and adding them to concrete can create a stronger building material[1].

Recycling microfiber materials from masks | WSU

The filter layer of disposable medical masks is made of polypropylene meltblown cloth, which is staggered with fine polymer microfibers. The researchers extracted these microfiber components from the masks, treated them with an aqueous solution of graphene oxide, and then mixed them into regular cement concrete as an additive. Experiments show that such treatment can increase the splitting tensile strength of concrete by up to 47% - that is, it will become stronger and less likely to crack.

In addition to turning masks into valuable items, this strengthening treatment can also increase the service life of concrete, thereby reducing energy consumption and carbon emissions caused by the production of new cement.

Soaring into the sky

Scientists have created the highest-jumping mechanical device yet—it can reach a height of 30 meters in one breath.[2]

A mechanical device that can jump 30 meters high | Hawkes Lab / UC Santa Barbara

This device consists of an engine, a carbon fiber compression bow, and a rubber band. When the line wrapped around the engine drive spindle is pulled, the rubber band is stretched and the carbon fiber bow is compressed like a spring, which stores power and bounces itself out. Even creatures that are good at jumping high are limited by the work generated by a single muscle stroke; but when a mechanical device bounces, it can make the engine stroke repeatedly, store the energy generated in a huge spring, and then fly into the sky. This device can quickly accelerate to 60 miles per hour (about 26.8 meters per second) and rush 30 meters in one breath.

New device features giant springs | Hawkes Lab / UC Santa Barbara

The researchers expect the device to be useful in space, traveling across strange planets without having to clear obstacles on the ground. They calculated that if it were on the moon, the device could jump forward 500 meters and clear an obstacle 125 meters high.

Ejection escape

Animal video of the week: Watch a tiny spider perform a lightning-fast catapult escape.

Many animals can perform blurry-fast catapults, which they usually use to catch prey or escape from predators, but the male Philoponella prominens spider in the video catapults himself to get away from his sweetheart as soon as possible after mating to prevent himself from being eaten by the female spider.

The study showed that these male spiders use the accumulated hydraulic pressure to drive the first pair of leg joints to stretch rapidly, thus completing the escape action, with the peak ejection speed reaching up to 88.2 cm/s. In experimental observations, 97.4% of males successfully escaped by ejection after mating, while the few unlucky ones who failed to escape were eaten by female spiders on the spot.

Researchers from Hubei University reported the discovery this week in the journal Current Biology[3]. They said that keeping the lightning-fast spiders in focus was the biggest challenge in the study.

Thin and light speakers

Engineers at MIT have created a new speaker that is as thin as paper, produces high-quality sound, and can be attached to any surface[4].

The key component of the thin speaker is a thin layer of piezoelectric material, which is processed into many tiny arch structures 15 microns high. Under the action of electric current, these tiny arch structures vibrate, and their combined force produces a sound with a sufficient volume.

This new type of speaker can be processed in just three simple steps. It is also very energy-saving, consuming only about 100 milliwatts per square meter. Sticking it in the room can create a three-dimensional sound effect and can also be used for active noise reduction.

Hazard warning signs

Signs reminding people to drive safely aren’t necessarily better for safety — sometimes they can even lead to more car accidents, according to a study published in Science[5].

Overly attention-grabbing warning signs can backfire | Jonathan Hall

The warning signs that the researchers focused on are large electronic displays that show the number of people killed in traffic accidents in the area in a year. In Texas, these warnings are only displayed on highways one week a month, which provides researchers with a good opportunity for comparative analysis.

After analyzing data from 2010-2017, the researchers found that displaying traffic accident death figures did not promote safety - on the contrary, it even increased traffic accidents by 4.5% within the next 10 kilometers. The researchers speculated that these negative messages may have attracted drivers' attention excessively, thus affecting their driving operations.

References

[1] https://www.sciencedirect.com/science/article/abs/pii/S0167577X22005912

[2] https://www.nature.com/articles/s41586-022-04606-3

[3] https://www.cell.com/current-biology/fulltext/S0960-9822(22)00485-7#%20

[4] https://news.mit.edu/2022/low-power-thin-loudspeaker-0426

[5] https://www.science.org/doi/10.1126/science.abm3427

Author: Mai Mai, Rain Knocking on the Window

Edit: Window knocking rain

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