Complex sentence: John Howard Purnell (born 1925 in the Rhondda Valley, South Wales, died 1996) was Professor of Physical Chemistry at University College, Swansea from 1965 until his retirement in 1992.
Split into simpler sentences: John Howard Purnell was born in 1925 in the Rhondda Valley, South Wales. He was Professor of Physical Chemistry at University College, Swansea from 1965 until his retirement in 1992.