Egyptian nobel prize-winning chemist Ahmed Zewail dies at 70

Ahmed Zewail, a science adviser to US President Barack Obama who won the 1999 Nobel Prize for his work on the study of chemical reactions over immensely short timescales, has died at the age of 70.

His death was announced by the California Institute of Technology (Caltech) in Pasadena, California, where he was Linus Pauling Professor of Chemistry and director of the Physical Biology Centre for Ultrafast Science and Technology.