Lithium (锂) is called “white gold” for good reason. The metal value has been growing rapidly over the last several years, mainly because it is an essential material of lithium-ion batteries, which play an important part in several key sustainable technologies, for example, electric cars.

As ocean waves, wind and solar power have grown into major players in the energy industry, lithium has also become key to building a future free of petrol. But getting lithium comes at a huge cost. As with most meals, its mining is damaging. It often works like this: Briny water, containing lithium and other meal, is pumped to the surface from underground. Then it sits in pools to allow the water to evaporate, leaving the rest behind as poisonous matter. Workers use chemical reactions to remove the lithium from that, making it into powder which is then packaged and shipped to the buyers around the world. Any accident that releases mine matter into surrounding communities or the groundwater supply could have damaging long-term impacts.

Indigenous (当地的) communities often bear the result of the damage, and political leaders have paid little attention to their concerns. In Arizona, for example, an expanding lithium mine is threatening the Hualapai Tribe’s historical sites. And for politicians who have promised to work with native peoples to deal with it, mining lithium and other precious metals is putting them into a dilemma: How do you ensure the availability of materials which are essential to the future while protecting indigenous people’s rights?

Mining of the metal is expected to increase greatly in coming years. Overtime, that will make electric cars inexpensive and, therefore, more popular.

As environmentally conscious consumers buy electric cars in ever-greater numbers, it’s important to be aware of the dirty process that powers those clean air vehicles.

Scientists have long said getting a good night's sleep is important to your health. The U.S. National Institute of Health says lack of sleep may even increase the risk of impaired brain activity, or cognitive decline(认知减退), and Alzheimer's disease.

Now, an American team of scientists reports that too much sleep might be similarly linked to such conditions.

Researchers at Washington University School of Medicine in St. Louis, Missouri, did the sleep study. Their findings were published in the September issue of the scientific publication Brain.

Dr. Brendan Lucey is director of the Washington University Sleep Medicine Center and led the research. He said, "Our study suggests that there is a middle range(区间), or ‘sweet spot,' for total sleep time" for best cognitive performance.

"Short and long sleep times were associated with worse cognitive performance, perhaps due to insufficient(不足的) sleep or poor sleep quality, " Lucey added.

Other studies have shown that lack of sleep was linked with cognitive decline. A small 2018 study published in the Proceedings of the National Academy of Sciences found that losing just one night of sleep led to an increase in beta-amyloid production. Beta-amyloid is a metabolic(新陈代谢的) waste product found in between brain cells. It has been long linked to brain disorders, such as Alzheimer's disease.

The National Sleep Foundation advises that healthy adults need between seven and nine hours of sleep per night. Babies, young children, and teens need even more sleep for their growth and development. And people over 65 should also get seven to eight hours per night, the foundation says.

One unanswered question from the Washington University study is whether increasing sleep time for short sleepers would help their cognitive performance.

But lead writer Lucey said each person's sleep needs are individual. If people feel rested, there is no need to change how they sleep. But those who are not sleeping well should know that sleep problems often can be treated, Lucey said.

Dr. David Holtzman, another top researcher on the study, added, "It suggests that sleep quality may be key, as opposed to simply total sleep."

A self-driving ship named after the Mayflower has been brought back while trying to re-create the cross-Atlantic trip made by the original Mayflower in 1620.

Last Tuesday, a robotic ship called the Mayflower Autonomous Ship (MAS) took off from Plymouth, England. Its mission was to re-create the 1620 crossing of the Atlantic by the Mayflower, which brought the first European settlers to what is now Plymouth, Massachusetts.

But unlike the original Mayflower, there are no people on the MAS. Everything about the ship is designed to run automatically. The ship is guided by an artificial intelligence (AI) system called “Al Captain”.

The MAS is a project run by a group called ProMare along with the computer company, IBM. The ship's electric motor is powered by solar energy. The goal of the project is to test different kinds of technologies for collecting information about the sea. If these can be handled by machines, it could be a big advance in ocean research. Sending humans to collect information at sea can be difficult, lonely, and dangerous.

In addition to cameras and radar to help the ship guide itself, the ship is carrying many different kinds of tools and sensors. It has special listening devices which can detect whales and dolphins. It even has a special “tongue” which can report back on the chemicals in the water.

Last Friday morning, scientists tracking the ship noticed that it was going about half as fast as it should have been going. The AI Captain was working well, but there seemed to be something slowing the motor down. Since the ship had only covered 10% of the way across the Atlantic, the team decided to bring it back to Plymouth so they could fix the problem and send it out again. They sent the MAS instructions to turn back.

When the MAS finally does put out to sea again, it is expected to take about three weeks to cross the Atlantic Ocean. The fastest speed for the MAS is about 10 mph (10 miles per hour). That may seem slow, but it's about 5 times faster than the original Mayflower, which took 66 days to make the journey.