One of his scientific studies is the first in its field. This study has become the focus of discussions for some reason. The thing produced in the mentioned study is still used today. Black and yellow are dominant colors  in the flag of the city where this person was born. Who is this person?

I know, it's like a puzzle. I can't find the answer, please help.

Some person invented something and the only other clue is that this person lives in a city on earth that has a city flag with black yellow in it?  Wow, seems like not enough info....

 

If you assume country flags, then Belgium or Germany seem likely candidates.
Unfortunately the list of studies produced in those countries which are still being discussed today, is extremely large.
Any other clues ?