  Thanks to the long-term collaborations between nuclear and astrophysics, we
have good understanding on stellar nucleosynthesis, except for the elements
around Ti and some neutron-capture elements. From the comparison between
observations and Galactic chemical evolution models, it is necessary to have
the rapid neutron-capture process associated with core-collapse supernovae,
although the explosion mechanism is unknown. The impact of rotating massive
stars is also shown in this paper. Many of the key elements can be exclusively
obtained in the UV, and therefore without UV spectra it would not be possible
to fully understand the origin of elements in the universe.
