The National Zoo's two giant pandas don't know how to mate with each other. But thanks to artificial insemination Mei Xiang (L) and Tian Tian (R) have produced two cubs, and a third may be on the way.

Biofuels might be a way to make energy out of renewable resources and cut dependence on fossil fuels, but currently, producing them from corn and other edible plants is largely impractical. Subscribe ...