in january 2021, ollie stevens - to protect them.ary 2021, ollie stevens set off| to protect them. in january l 2021, ollie stevens set off to meet a friend just minutes from his home. the 13—year—old was about to be ambushed. he suffered two fatal stab wounds. ollie's parents have been speaking at this knife crime conference in milton keynes. it's highlighting other problems being tackled including through prevention and education. thames valley police saver dealing with knife crime is their top priority. they are the first force in the country to use an app which highlights hotspots and monitors patrols. for more stories from across the uk, head to the bbc news website. the chinese government is tightening controls over exports of key materials used in the manufacturing of semiconductor chips, technology that's at the center of disputes between the us and china. the announcement comes just days before us treasury secretary janet yellen makes a high—stakes trip to beijing. in recent months, both superpowers have issued restrictive m