A team of scientists at Harvard University says it has come up with a bionic leaf — a system that could use solar power and hydrogen-eating bacteria to generate liquid fuel. The findings, described in the journal Science, offer an alternative path to making carbon-neutral solar fuels.

Part microbe and part machine, the bionic leaf marks a tenfold improvement on the researchers' previous version and could be used to generate all kinds of products, from the precursors for bioplastics to fuel.

Researchers have wanted to channel light energy into a storable fuel, much in the way that plants turn energy into sugars. The process, called artificial photosynthesis, typically involves using electricity from a solar cell to split water into hydrogen and oxygen gas. The hydrogen is collected, and when it is burned in places like the tank of a car, the only byproduct is water.

"This paper is going the full distance of what I'll call the true artificial photosynthesis," said study co-author Daniel Nocera.

Tourists, gorillas mix without incident in wild

In some parts of Africa, tourists and researchers routinely trek into the undergrowth to see gorillas in their natural habitat. There are no barriers and no enclosures, and the apes, many of whom are accustomed to people, sometimes move past first-time visitors frozen in place, their awe mingling with apprehension.

This delicate interaction usually happens without incident, overseen by guides who brief trekkers on rules designed as much to protect infection-prone gorillas from humans as to shield humans from hulking wild animals. It's a very different situation from the tense, rapidly unfolding events on May 28 at the Cincinnati Zoo, where an animal response team shot and killed an endangered adult male gorilla named Harambe after a 3-year-old boy fell into an enclosure.

In Rwanda, guides who lead tourists to see habituated gorillas ask them to stay at least 23 feet away from the animals. They also say: Don't point, speak softly, don't cough or sneeze in the animals' direction and if a gorilla approaches, crouch down, don't make eye contact and make a low sound similar to that of clearing the throat, which gorillas use to express friendliness.

Astronomers find clues about 'hot Jupiters'

Scientists say they may have a clue to the mysterious origin of "hot Jupiters," those gas giant planets that circle uncomfortably close to their host star: There may be a second star involved. A survey of 77 stars hosting hot Jupiters has found that roughly half of them are binary star systems.

The findings, presented at the Canadian Astronomical Society's annual meeting in Winnipeg, shed light on the dynamics that shape these strange planetary systems, and might offer some insight into our own solar system.

"One big mystery about these hot Jupiters is, how did they get in such orbits?" said lead author Henry Ngo, a Ph.D. student in planetary scientist at Caltech.

Several theories have said there may have been a "friend" — either a nearby star or another massive planet — that could have influenced either the hot Jupiter's orbit or its formation.

Ngo and his colleagues set out to find some of these "friends." They surveyed 77 star systems that had hot Jupiters circling them. Sure enough, about half of them had companion stars within a distance of 50 to 2,000 astronomical units.

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