Science in the hot spots of the week: my country will establish a near-Earth asteroid defense system

I wish you all a happy Labor Day. Here are the most popular scientific topics that we selected from Weibo's hot search list this week:

1. The first infrared image of a snow leopard was captured in Lhasa, Tibet

Recently, a domestic research team recorded infrared images of snow leopards for the first time on the back mountain of Nailang Monastery in Doilungdeqen District, Lhasa, Tibet. The straight-line distance from the center of Lhasa is less than 50 kilometers, filling the distribution gap of snow leopards in Lhasa and surrounding areas.

The snow leopard belongs to the genus Pantherinae of the family Felidae. It is a flagship species of high-altitude ecosystems and is also known as one of the most beautiful wild animals in the world. The reason why people think it is beautiful is mostly due to its mysteriousness. The snow leopard lives in remote and remote mountainous areas of Central Asia where few people go, and is closely related to the distribution of Tibetan Buddhism.

According to the currently popular "labeling" method, "East", "Buddhism", "Snowy Tibetan Land"... these symbols are enough to give the snow leopard a unique temperament.

Currently, there are about 3,900 to 7,900 snow leopards in the world, half of which are concentrated in China's Qinghai-Tibet Plateau. However, their number has dropped by 10% in the last three generations. Snow leopards tend to be distributed in areas with specific types of habitats (plateau meadows, rock cliffs), and then move between suitable areas to increase genetic exchanges between species. However, human activities and climate change have caused the area of ​​suitable habitats for snow leopards to decrease, making migration between these areas increasingly difficult. For this reason, biologists have set up multiple infrared cameras in the Qinghai-Tibet Plateau to monitor the traces of wild snow leopards and formulate measures to protect the snow leopard habitat.

The discovery of the snow leopard in Lhasa, Tibet also means that suitable snow leopard habitats are gradually recovering, and snow leopard research and protection work has achieved certain results.

Hotspot sources:

https://s.weibo.com/

Image source:

Shanshui Nature Conservation Center

The editor has something to say: Big cats look so cute!

2. my country will establish a near-Earth asteroid defense system

Recently, Wu Yanhua, deputy director of the National Space Administration, said that my country will build a complete asteroid monitoring and early warning system, and will also start to establish a near-Earth asteroid defense system.

To put it simply, this is to protect our home planet and the satellites in low-Earth orbit. Doesn't it sound very sci-fi (and it is), as if it only appears in movies? Of course, this system is not as powerful as in sci-fi movies, such as turning an asteroid into dust with one shot. We have set a small goal for this system: try to change the orbit of a threatening asteroid.

Although the Earth has lived relatively peacefully over the past few billion years, many "aliens" have visited the Earth during this period and brought certain disasters to the Earth. The most common of these are asteroids. Due to the large number of asteroids and their difficult whereabouts, in order to prevent them from happening, we need to monitor the trajectories of asteroids and think of countermeasures. Monitoring is easy to understand, which is to track the trajectories of asteroids and predict whether they will hit the Earth in the future. If an asteroid has such a sign, then we have to take precautions in advance. Specifically, we are more inclined to affect the orbit of asteroids rather than destroy them, because after destroying the asteroid, the fragments may be gathered together again by the gravity of the celestial body, and changing the orbit is mainly done by launching boosters at the asteroid or using a spacecraft to hit the asteroid. Some people may think that this is tantamount to "hitting a rock with an egg", but our goal is not to change the asteroid from one orbit to another. Even if it is only a 1 cm change, through the "butterfly effect", in the long run it is not just a small distance.

Hotspot sources:

https://s.weibo.com/

The editor has something to say: Everyone who drives knows that if you tilt the steering wheel a little bit, as long as the road is long enough, you can definitely drive to the Pacific Ocean.

3. A woman drank 3 liters of water in 2 hours and was almost killed and admitted to the ICU

Recently, a woman in Zhengzhou drank three liters of water in two hours. Not long after, she began to experience symptoms of nausea, vomiting, cramps in her hands and feet, and confusion. The doctor diagnosed her with typical "water poisoning."

As we all know, water is the source of life. The largest substance in our body is water. Every day we lose some water through breathing, sweating, urination, etc. The way we replenish water is usually to drink water, but we cannot drink water without restraint.

According to the "Dietary Guidelines for Chinese Residents" (2022 edition), under mild climate conditions, low-activity adult males should drink about 3.7 liters of water per day (including water in food), and adult women should drink about 2.7 liters per day (including water in food). Of course, this does not mean that this limit cannot be exceeded, but excessive drinking may lead to "water intoxication". The reason is that the cell membrane of human cells is a semi-permeable membrane. If the body takes in too much water, it will cause the osmotic pressure inside and outside the cells to lose balance, and more water will enter the cells, causing the cells to swell (imagine the angry look of pufferfish), destroying the normal structure and function of the cells. Brain cells react the fastest because they are fixed in the hard cranial cavity. Once brain cells become edematous, the pressure in the skull will increase, leading to symptoms such as dizziness, nausea, brain swelling, blurred vision, and in severe cases, coma or even life-threatening.

Hotspot sources:

https://s.weibo.com/

The editor has something to say: Just like the city’s drainage system, it can cope with normal precipitation, but if there is a heavy rainstorm, the drainage system may not be able to cope with it.

4. Not all fruits and vegetables are suitable for the refrigerator

For most families, the refrigerator is like a "treasure box" in which vegetables, fruits, meat and even everything edible at home can be placed, mainly for the purpose of preserving freshness. However, this is actually a misunderstanding among people. In fact, some fresh vegetables, fruits and other foods are not suitable for being placed in the refrigerator.

For fruits, putting them in the refrigerator is mainly to maintain the quality and flavor of the fruits after harvest and reduce decay by effectively reducing the respiratory metabolism and other life activities of the fruits and inhibiting the activity of microorganisms under low temperature conditions. However, studies have shown that different fruits actually have different requirements for temperature, and they each have a suitable low-temperature preservation range. If you do not understand the requirements of low-temperature preservation and blindly treat the fruits at low temperatures, it will cause low-temperature damage. For example, tropical or subtropical fruits such as bananas, dragon fruits, and mangoes are sensitive to low temperatures. Low-temperature storage may cause browning of the peel and poor ripening. The same is true for vegetables. Vegetables such as cucumbers, green peppers, and sweet potatoes like warmth and are suitable for storage above 10°C. Storing them at low temperatures is prone to frost damage or accelerated corruption. In addition, when putting common green leafy vegetables in the refrigerator, pay attention to removing yellow and bad leaves, and when using fresh-keeping bags to seal them, do not allow obvious condensation to appear on the leaves.

Hotspot sources:

https://s.weibo.com/

The editor has something to say: Fruits can also be "unsuitable for local climates"

In conclusion:

① Snow leopards, seemingly occupying unfavorable terrain, may leave behind a relatively intact population of large cats after avoiding fertile lands where humans are more frequent;

② Through the construction of an asteroid monitoring and defense system, China will make new contributions to helping future humans truly respond to the threat of asteroids and extraterrestrial bodies to our home planet;

③ Of course, whether drinking too much water is also closely related to personal weight, activity level and other factors. In some specific environments or situations (such as heat and humidity, illness, etc.), it is necessary to drink more water;

④ In order to prevent low-temperature damage to vegetables and fruits caused by low-temperature preservation and to preserve the original flavor and nutrients to the maximum extent, measures such as gradual temperature increase or decrease or pre-cooling before storage, temperature increase during storage, and chemical treatment can be adopted.

References:

[1] Zhu Dan, Li Lijuan, Huang Bisheng. Research progress in fruit preservation technology[J]. Journal of Dali University: Comprehensive Edition, 2013, 12(4):3.

[2] Xiao Lingyun, Panorama. Snow Leopard: King of the Snow Mountains[J]. Forests and Humans, 2017(7):10.

[3]https://doi.org/10.1038/s41598-020-76912-7