The politicians internal divisions have led to fears that a political vacuum could give Sunni militants a chance to revive the sectarian violence that roiled the nation in 2006 and 2007.

VOA: standard.2010.04.04

This is titanium sponge that comes out of the bottom of this reactor, and it subsequently re-melted in a vacuum arc furnace.

海绵状的钛,从反应器的底部出来，随后在真空炉中重新熔炼。

麻省理工公开课 - 固态化学导论课程节选