【推荐1】Copper surfaces kill microbes (微生物)that come into contact with them in a matter of hours. A new technique makes the familiar metal even deadlier.

Bacteria “are becoming more aggressive and resistant to medicines; it's the same thing for viruses/' says Ravi Rahimi, a materials engineer. "There is a lot of interest in how to create surfaces that actually, on contact with the bacterium or the virus, immediately lull the pathogen (病原体)" because this "thwarts” the spread of that pathogen into the environment."

Copper is a good candidate, for such surfaces: humans have been taking advantage of its bacteria-killing properties for at least 8,000 years. People in some Bronze Age civilizations let their drinking water rest in copper vessels to avoid disease, says Michael Schmidt, a microbiologist, who was not involved in the new research. Copper's germ-destroying power, he explains, comes from its ability to conduct electricity. When a microbe touches a metal surface, the substance carries electrons always from the microbe's cellular membrane (细胞膜).This reaction sets off a chemical process that finally forces open the organism's pores (毛孔)and destroys it. .

To enhance the process, Rahimi's team hit a copper sample with laser light for a milliseconds, thereby creating nanoscale pores in the fiat metal and increasing its surface area. Schmidt says the added vertical structures “increased the amount of 'square fbotage⁵ available to kill microbes? The rough surface also made the copper cling (附着于)more strongly to water - and thus to any bacteria within it.

The researchers tested this newly rough surface by placing several bacterial species on both flat and laser-treated pieces of copper. As soon as the cells hit the metal, their membranes began to suffer damage; that surface completely destroyed the bacteria, in some cases much more quickly than the untreated one. The surface killed some viruses immediately on contact and took from 40 minutes to two hours to wipe out a full colony, depending on the species and concentration.

The laser treatment could also work with other metals, including titanium, which is often used for surgical implants, Rahimi says. He points out that all types of metals display some antimicrobial properties, although titanium, which has little conductivity, kills germs much more slowly than highly conductive ones such as copper.

【推荐2】Scientists can figure out a movie's emotional tone from the gasps（喘气）of its audience.

These gases could point the way to a subtle form of human communication，a new study suggests. “When you see a movie，you can hear the music and see the pictures. However，you don't realize there are chemical signals in the air. And they，too，could be affecting you，"says Williams，who led the study. As an atmospheric chemist，he studies the chemical makeup of the air around us.

Williams started out measuring the air in a soccer stadium. He noticed that levels of carbon dioxide and other gases changed wildly whenever the crowd cheered. That got him wondering--Could the gases people breathe out be influenced by emotions？

To find out，he went to the movies.

Williams and his coworkers measured air samples collected over six weeks in two movie theaters. Overall，9，500 movie goers watched 16 films. They included a mix of comedy，romance，action and horror films. Among them were The Hunter Games，Catching Fire，Carrie，and Walking with Dinosaurs. The researchers gave scenes from the movies such labels as“suspense”，“ laughter"，and“crying”. Then they looked for hundreds of chemicals in the air that showed up as people were watching particular movie scenes.

And certain scenes had distinct chemical“fingerprints”，Scenes that had people laughing or on the edge of their seats were especially distinctive. During screenings of The Hunger Games，levels of carbon dioxide and isoprene got to the highest at two suspenseful moments. Because isoprene is related to muscle movement，the researchers think tense movie moments likely led to its peak. Williams and his colleagues think the increase in carbon dioxide was due to the viewers' increased pulse and breathing rates.

Scientists need more data to make stronger links between human emotions and what's in their breath. But Williams can see potential practical uses. Companies，for instance，could quickly measure the air during tests to see how people feel about new products. He pictures future studies recording other body variables（变数）as well. These might include heart rate and body temperature，for instance. “It's something to find out. ”