Soda has been popular around the world for centuries. But what is the secret behind these bubbles(气泡)? The bubbles in soda is in fact filled with carbon dioxide, or CO₂, which is added to carbonated(碳酸的) drinks at high pressures during production.

The history of modern carbonated sodas can date back to English scientist Joseph Priestley, who is called “the father of the soft drinks industry”, for developing a carbonating device in 1772.

At first, bottled carbonated water was used as a kind of medicine. Flavors(味道) were added later—ginger by about 1820, and lemon in the 1830s. In 1886, John Pemberton in Atlanta, Georgia, invented Coca-Cola, the first cola drink.

After soda is filled with carbon dioxide, the gas escapes due to a principle in physical chemistry known as Henry’s law, put forward by British chemist William Henry in 1803. It states that the amount of a gas dissolved(溶解) in a liquid is proportional(成比例的) to the pressure of that same gas in the liquid’s surroundings. When soda is canned or bottled, the space above the drink is usually filled with CO₂. Because of Henry’s law and the pressure of the gas trapped at the top of the container, the carbon dioxide that’s dissolved in the drink stays within the liquid.

However, when a soda container is opened, the balance is broken. The pressurized CO₂ escapes and produces the symbolic sound one expects to hear from a newly opened soda bottle or can. If a can or bottle has been shaken before it is opened, gas trapped within the liquid can escape to join the gas above the drink. It increases the pressure in the gas above the drink and results in the soda rushing out when the container is opened.

According to a new study, a chatbot may help reduce the possibility that a person develops an eating disorder. For women at a high risk of an eating disorder, going through a dialogue with a chatbot developed by researchers reduced concern over body weight and shape—a factor that contributes to their risk.

“Previous research showed that digital prevention programs are more effective when they’re guided by a human moderator (调解人),”said study author Ellen Fitzsimmons-Craft, a professor at Washington University School of Medicine. But it’s hard to get funding in the United States for programs that prevent mental health conditions. The team thought a chatbot could be a cheaper version of such a program that offers some aspects of moderation in an automatic form. The team developed a chatbot version of the prevention programs that are usually delivered through a website and include information al content, exercises, and journal prompts. Participants could use the chatbot through texts or through chatting apps.

The study recruited (招募) female participants through online ads. Women who didn’t have an eating disorder but had risk factors for one, like negative body image or excessive (过度的) concern about the weight, were randomly assigned to either engage with the chatbot or sit on a waiting list. The chatbot offered eight conversations about topics around body image and healthy eating, and women who used the chatbot were encouraged to have two of the conversations each week. At three- and six-month check, women who talked to the chatbot had a bigger drop in concerns, on a survey, about their weight and body shape—a major risk factor for developing an eating disorder—than women in the waiting list group.

The study also found some indication that women in the chatbot group were less likely to have developed a clinical eating disorder by the end of the six months than women in the waiting list group. “This could have a positive effect on public health if we can continue to find ways to spread it widely,” said Ellen.

There is a lot of interest in finding ways to help people get smarter and more effective at what they do in life. That is one reason why brain training apps continue to be popular despite evidence that suggests they do not increase general intelligence.

But that doesn’t mean that there aren’t any activities that can influence overall cognitive (认 知) ability. Indeed, a new study suggests that learning to play a musical instrument may help, at least in the long-term.

These researchers analyzed data from a study that followed a group of individuals who grew up in Scotland and were born in 1936. They were given several different kinds of tests and surveys over the course of their lives. Of particular interest, these participants did a test of cognitive ability at the age of 11 and again at the age of 70. At the age of 82, surviving members of this group were also asked about their experience learning to play a musical instrument over the course of their lives.

The study didn’t include people who still played their instrument regularly at the age of 82 to avoid affecting the result. To do this analysis properly, the authors also used other data that had been collected in this study to address other factors that might lead to changes in intelligence such as diseases like heart disease, high blood pressure, occupation, sex, and education level. The aim was to filter out the influence of as many other factors as possible.

In addition, the authors treated experience with a musical instrument on a continuum rather than just a Yes/No. The questionnaire (调查问卷) about musical experience asked about the number of instruments played, years of experience, years of practice, and hours per week of practice. This way, the researchers could look at whether more experience with an instrument had a bigger impact on cognitive ability than less experience.

The analysis suggests that there is a small but reliable influence of playing a musical instrument on increases in cognitive ability during the life. But these findings do not explain why playing an instrument might have this effect on ability.