Batteries were invented in 1800, but their complex chemical processes are still being explored and improved. While there are several types of batteries, at its essence a battery is a device that converts chemical energy into electric energy.

Fish passage refers to the ability to effectively and efficiently allow fish to move through a water system, including successfully navigating human-made structures like dams and culverts, which can impede their journey.

Fentanyl analogs are illicit—and often deadly—alterations of the medically prescribed drug fentanyl. The analogs have similar—but not the same—chemical structure, and they mimic the pharmacological effects of the original drug.