Egyptian Nobel prize-winning chemist Zewail dies aged 70

Nobel prize-winning Egyptian-American chemist Ahmed Zewail, who served as a science and technology advisor to US President Barack Obama, died Tuesday in the United States. Zewail, a naturalised US citizen, won the Nobel prize for chemistry in 1999 for his groundbreaking work in the study of chemical reactions in extremely short timescales. According to the Nobel Prize website, Zewail's work led to the birth of the research area called femtochemistry, "which enables us to understand why certain chemical reactions take place but not others".