What was a major concern of scientists who left nazi germany for the united states beforw world war ll?

They feared germany was trying to develop nuclear weapons.

The embargo act of 1807  was a law passed by the united state congress and signed by president thomas jefferson on december 22,  1807. it prohibited american ships from trading in all foreign ports. in 1806, france passed a law that prohibited trade between neutral parties, like the u.s., and britain.