1. Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, 06006 Badajoz, Spain
2. Department of Biology, Saint Michael's College, Colchester, VT 05439, USA
3. Department of Archaeological Sciences, Faculty of Archaeology, Leiden University, 2333CC Leiden, The Netherlands
4. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA