Wells, J. Ortega, D. Steinhoff, U. Dutz, S. Garaio, E. Sandre, O. Natividad, E. Cruz, M.M. Brero, F. Southern, P. Pankhurst, Q.A. Spassov, S. the, RADIOMAG, consortium Challenges and recommendations for magnetic hyperthermia characterization measurements Int. j. hypertherm. 10.1080/02656736.2021.1892837 2021 2021