Original sentence: In 1949 he joined the Department of Physical Chemistry at the Polytechnic Institue in Sofia (now the University of Chemical Technology and Metallurgy) as an assistant where he stayed until moving to the Department of Inorganic Chemistry at Sofia University in 1951, becoming full professor and head of department in 1960
Edited sentence: In 1949 he joined the Department of Physical Chemistry at the Polytechnic Institute in Sofia (now the University of Chemical Technology and Metallurgy) as an assistant where he stayed until moving to the Department of Inorganic Chemistry at Sofia University in 1951, becoming full professor and head of department in 1960