He devoted himself to scientific research with unwavering commitment.
Tips
register
Formal and literary - fits speeches, biographies, love declarations in formal writing. In casual speech use 一直 or 从未改变 instead.
memory
矢 originally means 'arrow', by extension 'to swear/pledge' (as if releasing an oath like an arrow). 渝 = to change (cognate with Chongqing's abbreviation 渝, from the river). Literally 'pledge the resolve, do not change'.
