1. Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, UK
2. Institute of Power Engineering, Mory 8, 01-330 Warsaw, Poland
3. Epoch Wires Ltd, Unit 8, Burlington Park, Foxton, Cambridge, CB22 6SA, UK
4. Department of Physics and Energy, Bernal Institute, University of Limerick, Castletroy, Ireland