In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

Example Input: Nebulized arformoterol in patients with COPD: a 12-week, multicenter, randomized, double-blind, double-dummy, placebo- and active-controlled trial.
Example Output: arformoterol

Example Input: Effects of silver nanoparticles on the liver and hepatocytes in vitro.
Example Output: silver

Example Input: Effect of amrinone on tumor necrosis factor production in endotoxic shock.
Example Output:
amrinone