Rewriting textbooks, chemists broke a century-old rule | Science and Technology Weekly

Compiled by Zhou Shuyi and Wang Xiang

Private jet CO2 emissions soar

A new study shows that the number of private jets, the number of flights and the mileage have increased significantly in the past few years, driving a surge in carbon emissions. From 2019 to 2023, annual carbon dioxide emissions from private aircraft rose by 46%. In 2023 alone, the private aviation industry emitted more than 15.6 million tons of carbon dioxide. The analysis also shows that some individuals who frequently use private jets may produce nearly 500 times more carbon dioxide than the average person in a year.

Private jets are one of the most energy-intensive means of transportation, used by only about 0.003% of the world's population. "The carbon emissions of a large private jet per hour are equivalent to the carbon emissions of an average person in a year," said Stefan Gössling, an author of the paper from Linnaeus University in Sweden. However, there has been no accurate data on the true size and carbon emissions of the private aviation industry.

Map of all 4.3 million direct private flights between cities recorded in the study. The thickness of the line indicates the number of flights during the assessment period, with thicker lines indicating more flights. | Communications Earth & Environment

The researchers analyzed flight data from 18,655,789 flights of 25,993 registered private aircraft (business jet type) between 2019 and 2023, covering the vast majority of the private aviation industry. They combined the nominal fuel consumption levels of 72 aircraft models with flight duration and trajectory to calculate the carbon dioxide emissions of each flight. The results show that from 2019 to 2023, the number of private aircraft increased by 28.4%; total carbon dioxide emissions increased from 10.7 million tons to 15.6 million tons, an increase of 46%. Nearly 50% of flights fly less than 500 kilometers, and each flight produces an average of about 3.6 tons of carbon dioxide emissions.

Peak emissions occur during specific international events, such as COP28 and the 2022 FIFA World Cup. The authors note that large international events see a large increase in private flights, with COP28 associated with 4,800 tonnes of CO2 from 644 private flights, and the 2022 FIFA World Cup associated with 14,700 tonnes of CO2 from 1,846 private flights. In addition, the largest emitters will produce around 2,400 tonnes of CO2 in 2023. This is nearly 500 times the average individual emissions in 2020 (4.5 tonnes of CO2). The private aviation industry is concentrated in the United States, where 68.7% of private aircraft are registered.

Experts say that although private aviation accounts for only a small part of commercial aviation, the new research reveals how serious the damage it causes to the earth. The author believes that the rise in carbon emissions from private aircraft worldwide is "unsustainable" and stricter regulations may alleviate this trend; in the future, further research will be conducted on other non-carbon dioxide emissions such as methane and sulfur dioxide in the aviation industry. The relevant paper was published in Communications Earth & Environment on November 7.

Singles have an 80% higher risk of depression than married people

A study published in Nature Human Behaviour on November 4 analyzed data from more than 100,000 participants from seven countries and found that unmarried people may have an 80% higher risk of depressive symptoms than married people. The study also found that men and unmarried people with higher education levels have a higher risk of depression.

Depression is a global public health problem, with approximately 5% of adults worldwide experiencing severe depression. Although previous studies have shown that marriage may reduce the risk of depression, these studies have typically focused on a single country (usually a Western country), the results often vary from country to country, and the interaction between marital status and other factors such as socioeconomic status, age, and education level is unclear.

The researchers retrieved individual data from 106,556 participants from seven countries (the United States, the United Kingdom, Mexico, Ireland, South Korea, China, and Indonesia), and followed up 20,865 of them for 4 to 18 years to analyze and compare the risk of depressive symptoms between married and unmarried people. The results showed that the correlation between unmarried status and the risk of depressive symptoms was 79% higher than that of married people. Divorced or separated individuals have a 99% higher risk of depression than married individuals, and widowed individuals have a 64% higher risk than married individuals. In addition, compared with Eastern countries (including South Korea, China, and Indonesia), unmarried people in Western countries (including the United States, the United Kingdom, and Ireland) have a relatively higher risk of depression. Unmarried men have a higher risk of depression than unmarried women, and individuals with higher education have a higher risk of depression than those with lower education.

The study suggests that married couples have a lower risk of depression, possibly because they can provide social support to each other and have better economic resources, which has a positive impact on the happiness of both parties. The reason why highly educated unmarried people have a higher risk of depressive symptoms may be due to pressure from traditional marriage concepts, lack of understanding from social public opinion, and lack of financial support from their spouses. The pursuit of career success, financial stability, and professional recognition may also bring additional psychological pressure.

The study also examined the relationship between smoking and drinking and the risk of depression among singles. Smoking and drinking behaviors are associated with the risk of depression, but due to differences in physiological and cultural characteristics, the results vary significantly between countries. For example, alcohol is a major factor in the increased risk of depression among singles in South Korea, but not in the United States and Ireland. The study also found that the impact of cigarettes on the risk of depression among unmarried people in China was 43.8%, and in Mexico it was 22.1%.

The authors also noted that the study had limitations: the data came from self-report questionnaires rather than clinical diagnoses of depression, and all couples analyzed in the study were heterosexual.

The world's first wooden-shell satellite is launched

The Space Wood Research Laboratory of Kyoto University in Japan said on November 5 that the world's first wooden-shelled artificial satellite "LignoSat" developed by the institution was launched into space on a cargo spacecraft of the US SpaceX company on the evening of November 4, Eastern Time.

LignoSat is named after the Latin word for wood (Ligno) | STR/JIJI PRESS/AFP

The laboratory and Japan's Sumitomo Forestry Corporation launched the "Space Wood Project" in April 2020, and it took about four years to develop this wooden-shelled satellite. According to reports, this is an ultra-small satellite with a cube shape, a side length of 10 cm and a weight of about 1 kg. Many parts of the satellite are made of a tree called "Japanese Magnolia" and are covered with solar panels. It will be released from the Japanese "Hope" module about a month after it arrives at the International Space Station with the spacecraft. The satellite will measure the stress, temperature and other changes of the wooden structure in space and transmit the data back to Kyoto University.

It is reported that currently small artificial satellites usually fall into the Earth's atmosphere and burn up after completing their missions. Metal satellites often contain more aluminum, which will produce a large amount of aluminum oxide particles when burning, which will have a negative impact on the Earth's environment and wireless communications. Wood can be completely burned in the atmosphere, which is expected to reduce such negative effects. The researchers added that wood will neither burn nor rot in a vacuum environment, making it more durable than on Earth.

43 experimental monkeys escape from a medical research institute in the United States

According to CBS, 43 experimental monkeys escaped from a medical research institute called Alpha Origin in Yemassee, South Carolina, on November 6, local time. Local police said that the escaped monkeys were all female rhesus monkeys, weighing about 7 pounds (about 3.18 kilograms). This group of female monkeys are "very young" and have never been used in experiments in research institutions due to their age. "They are not infected with any diseases and will not cause harm" - there is "almost no danger" to the public. However, the police still urged local residents to lock their doors and not approach these animals under any circumstances.

The monkeys escaped because a new employee of Alpha Origin "did not completely close the fence". "There were 50 monkeys at the time, and only seven did not run away." The police are currently helping the research institute search for the monkeys. The police said they had set traps and used thermal imaging cameras to locate and capture the monkeys, and found their traces in a forest near the institute that day. Alpha Origin staff are trying to lure the monkeys back with food to ensure they are safely captured.

Alpha Origin reportedly provides "non-human primate products and biological research services" worldwide, with clinical trials including research on progressive brain diseases. Eight years ago, 19 monkeys escaped from Alpha Origin and were captured about six hours later.

EU agency: 2024 will be the hottest year on record

The Copernicus Climate Change Service, the European Union's climate monitoring agency, said on November 7 that temperature data from the first 10 months of 2024 showed that this year will be the hottest year since records began in 1850.

The Copernicus Climate Change Service issued a press release on the same day saying that the global average temperature in the first 10 months of 2024 was 0.71 degrees Celsius higher than the average temperature in the same period from 1991 to 2020, the highest value on record, and 0.16 degrees Celsius higher than the same period in 2023. In fact, it is certain that 2024 will be the hottest year on record unless the average temperature drops to close to 0 degrees Celsius for the rest of the time.

The agency predicts that the average annual temperature in 2024 will be 1.5 degrees Celsius higher than the pre-industrial temperature level between 1850 and 1900, or even more than 1.55 degrees Celsius.

The agency's monitoring data also showed that the just-passed October was the second hottest October in the world after October 2023, with an average temperature of 15.25 degrees Celsius, 0.8 degrees Celsius higher than the average temperature in October from 1991 to 2020, and 1.65 degrees Celsius higher than the pre-industrial level.

In addition, several extreme weather events occurred around the world in October, including heavy rainfall that caused severe floods in Spain, killing more than 200 people; and hurricanes Helene and Milton that landed in Florida and other places in the United States. (Xinhua News Agency)

Just five minutes of extra exercise a day can lower your blood pressure

Just five minutes of exercise a day, such as climbing stairs or riding a bike, can lower blood pressure and improve health, a new study suggests.

Hypertension refers to high blood pressure in blood vessels (140/90 mmHg or higher), which threatens the heart, brain, kidneys and other organs and increases the risk of other diseases. It is the main cause of premature death, and about 1.28 billion adults worldwide suffer from hypertension. Because its symptoms are difficult to detect, 46% of adult hypertensive patients do not know they have the disease.

Unsplash/CC0 Public Domain

The researchers retrieved data from 14,761 participants from five countries to analyze the relationship between daily activities and blood pressure levels. Participants wore accelerometers to monitor their activities throughout the day. The study divided daily activities into six categories: sleep, sitting, slow walking (slower than 100 steps per minute), fast walking, standing, and relatively intense exercise (such as running, cycling, or climbing stairs). The data showed that the participants slept an average of 7 hours a day, sat for 10 hours, stood for 3 hours, walked slowly for 1 hour, walked fast for 1 hour, and only 16 minutes of relatively intense exercise.

Statistical analysis shows that an extra 5 minutes of exercise per day to replace other resting states can reduce systolic blood pressure by 0.68 mmHg and diastolic blood pressure by 0.54 mmHg. At the population level, a 2 mmHg reduction in systolic blood pressure and a 1 mmHg reduction in diastolic blood pressure is equivalent to an approximately 10% reduction in cardiovascular disease risk. The study estimates that as long as 20 to 27 minutes of additional exercise per day can achieve a "clinically significant" improvement.

The researchers said the new study highlights how even a small amount of daily exercise can improve blood pressure. "The good news is that no matter your exercise capacity, you don't have to exercise for a long time to have a positive impact on blood pressure. ... From climbing stairs to taking a short bike ride, these are easy to do every day."

Rewriting textbooks, chemists break a century-old rule

Chemists have overturned Brett's rule, which has "bound chemists for a century", and for the first time created a class of molecules that were previously thought to be unstable and therefore non-existent, providing a new way to synthesize potential drugs. Craig Williams, a chemist at the University of Queensland in Australia, said the research was "a landmark contribution".

Brett's rule is an empirical observation in organic chemistry, first proposed by German chemist Julius Brett 100 years ago, which states that unless the ring is large enough, the bridgehead position (i.e. the place where two rings are connected) in a bridged ring compound cannot contain a carbon-carbon double bond. This is mainly because in small and medium rings (less than eight members), the double bond at the bridgehead has ring strain, especially angle strain. The geometric configuration of trans-Brett olefins (ABO) with carbon-carbon double bonds at the bridgehead position is highly distorted, making them difficult to form and generally unstable and easy to decompose.

The norbornene isomer on the right is "anti-Brett," with a highly distorted double bond geometry.

The researchers treated silicon-based (pseudo) halides with a fluorine source to trigger a milder elimination reaction and successfully synthesized trans-Brett olefins. They are very unstable, so the research team also introduced capture agents to stabilize these trans-Brett olefins to form compounds that can be separated. Unlike typical olefins, trans-Brett olefins are chiral compounds. The researchers synthesized and captured an enantiomerically enriched trans-Brett olefin that can be used as an unconventional molecular building block for enantiomerically enriched compounds and has high practical value for new drug design.

Preparation principle

Li Chuangchuang, a professor at the Southern University of Science and Technology in China, said the method could be used to explore innovative synthetic pathways for other challenging molecules, such as the chemotherapy drug paclitaxel. "It is a valuable and reliable method."

It is worth mentioning that early calculations showed that anti-Brett olefins could not exist at all, but later calculation methods showed otherwise. If others had not believed in superstition, they could have made this achievement a few years earlier. "We should not stick to the rules - or, even if there are rules, we should always remind ourselves that they are just guidelines, not iron laws," said Neil Garg, the author of the paper at the University of California, Los Angeles. "If we make so-called insurmountable rules, it will eliminate creativity." The relevant paper was published in Science on November 1.

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