Complex sentence: Returning to Australia in 1990, Sheil accepted a lectureship in chemistry at the University of Wollongong, was promoted to Professor of Chemistry in 2000 (making her the Australia's first femaly chemistry professor) before becoming Dean of Science in 2001.
Split into simpler sentences: Returning to Australia in 1990, Sheil accepted a lectureship in chemistry at the University of Wollongong. She was promoted to Professor of Chemistry in 2000, the first female chemistry professor in Australia, before becoming Dean of Science in 2001.