PT Journal AU Rossell, MD Kübel, C Ilari, G Rechberger, F Heiligtag, FJ Niederberger, M Koziej, D Erni, R TI Impact of sonication pretreatment on carbon nanotubes: A transmission electron microscopy study SO Carbon PY 2013 BP 404 EP 411 VL 61 DI 10.1016/j.carbon.2013.05.024 LA english ER