The Qin Dynasty fell? Maybe it’s not entirely Qin Shi Huang’s fault…｜BoLan Daily

The Qin Dynasty fell? Maybe it’s not entirely Qin Shi Huang’s fault…

When we know the exact year of each growth ring of a tree, it is equivalent to opening an archive book that records past environmental changes.

Each tree ring has a page number, and each page contains recorded information , including sunlight, sunshine, rainfall, soil conditions, etc. ... and these are corroborated by historical materials, witnessing the rise and fall of dynasties and the changes in the world .

Following the guidance of tree rings and following the track of time, we will find that after Qin unified the six kingdoms, trees grew well. But during the uprising of Chen Sheng and Wu Guang, even the big trees did not grow well, and the lives of ordinary people can be imagined.

Similarly, through tree rings, we discovered that the drought in the Eastern Han Dynasty corresponded to the locust outbreaks recorded in history books, and that the drought lasted for several decades in the Eastern Jin Dynasty... Each tree ring is like an old man who has witnessed the changes in the world, and the researchers are about to turn over the memories inside to see what it tells us.

Why can't you fall asleep after drinking a sip of coffee , but he can drink anything?

Everyone responds to caffeine differently. The rate at which caffeine is metabolized varies widely between individuals, likely due largely to the efficiency of enzymes in the liver that metabolize caffeine . Our genes, age, weight, and even gender can affect our response to caffeine.

More specifically, some people's livers may have more liver enzymes such as cytochrome oxidase, which allows them to quickly break down caffeine, weakening its effects; while some people may be more sensitive to caffeine due to the lack of these enzymes, and may have a pounding heart and trembling hands after drinking coffee. For these people, it is still necessary to pay attention to controlling the amount of caffeine intake.

In addition, the caffeine content in some milk teas is even several times higher than that in coffee , which is why many people have difficulty falling asleep after drinking milk tea.

Some people who drink coffee regularly may find that coffee is becoming less and less effective! Adenosine and adenosine receptors are responsible for making us sleepy in our brains. The molecular structure of caffeine is similar to that of adenosine. If we take caffeine continuously, caffeine will always occupy adenosine receptors, and the amount of free adenosine in the body will increase, which will make us more sleepy.

In addition, studies have found that long-term caffeine intake will increase the number of adenosine receptors to receive the homeless adenosine that is free outside. This will make people more sleepy and more dependent on coffee.

Why are zebrafish the fish to be raised in space?

The Shenzhou-18 manned spacecraft was launched at 20:59 tonight, and a zebrafish also set off with the three astronauts.

The beautiful zebrafish is a famous model organism in the scientific community. It has the advantages of small size, short development cycle, short experimental cycle, and easy breeding. The fish eggs are transparent, making it easy for researchers to observe the embryonic development process, and it is widely used in biomedical research.

According to the plan, the fry will be installed on the manned spacecraft before launch. It is also possible to conduct in-orbit research on insects and small animals on the space station in the future. Looking forward to it!

Faced with the problem of wanting so much , how do scientists solve the problem?

In chemistry class, it is a "colorless, highly toxic compound with the smell of rotten eggs." In industry, it is an "inaudible killer." Here we go -- hydrogen sulfide!

Hydrogen sulfide is usually produced as a byproduct of natural gas extraction, oil refining, coal chemical industry and smelting processes. According to incomplete statistics, my country's annual hydrogen sulfide treatment volume is about 8 billion cubic meters. How to safely, efficiently and environmentally friendly treat this huge amount of "cancer" has always been a difficult problem faced by the industry.

Recently, the team of Academician Li Can from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, finally developed an ingenious solution to hydrogen sulfide after years of deep research in this field.

By taking advantage of the chemical potential difference between the electron-mediated pair and hydrogen sulfide, the process of hydrogen sulfide oxidation to generate sulfur, which originally occurred on the electrode surface, was transferred to an external reactor. The same strategy was used to utilize the valence change of another pair of electron-mediated pairs to guide the process of hydrogen ion generation to another container outside the electrode.

This innovative off-site electrocatalytic technology can decompose hydrogen sulfide into hydrogen and sulfur under mild conditions. It not only avoids the defects of traditional processes and provides the possibility for process scale-up, but also realizes the resource utilization of hydrogen sulfide. It not only improves the conversion rate of hydrogen sulfide, but also reduces pollutant emissions and obtains hydrogen with a purity of more than 99.999%.

High-speed trains always have two or three seats . This is a math problem.

When we step onto the high-speed train and look for our seats, we may rarely think about the logic behind the seat layout. However, the seat design of the high-speed train is actually the result of careful consideration by engineers and designers. It is not only about the comfort of the ride, but also contains mathematical wisdom.

High-speed rail seats are generally arranged in a 3+2 pattern, and this design can meet the travel needs of groups of different sizes. Whether it is a two-person trip or a group of three or five, you can find adjacent seats to avoid being left alone. The mathematical basis of this design is the Frobenius coin problem, "Given coins of several denominations, what is the maximum amount that cannot be paid with these coins?" For example, if there are only coins with denominations of 3 yuan and 5 yuan, then the maximum amount that cannot be paid is 7 yuan. In this problem, if the denominations of the two coins are prime to each other, then they can form any amount except a specific value. Similarly, the 2-person and 3-person seats of the high-speed rail can meet the needs of any group of more than 2 people, because 2 and 3 are prime to each other.

This design cleverly solves a seemingly simple but actually complex seat allocation problem. It not only improves the riding experience, but also demonstrates the practicality and beauty of mathematics in solving practical problems.

Frobenius coin problem

The content is compiled from China Science Popularization Expo Weibo, Institute of Physics, Chinese Academy of Sciences, CCTV News, Science Academy, Gezhi Lundao Forum, Science World

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