China restricts exports of high-tech metals in a slap at Washington ahead of Yellen’s visit

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FILE - A Chinese microchip is seen through a microscope set up at the booth for the state-controlled Tsinghua Unigroup project which is aimed at driving China's semiconductor ambitions during the 21st China Beijing International High-tech Expo in Beijing, China, on May 17, 2018. China has imposed export curbs on two metals used in computer chips and solar cells, expanding a squabble with Washington over high-tech trade ahead of Treasury Secretary Janet Yellen's visit to Beijing this week. (AP Photo/Ng Han Guan, File) BEIJING – China has imposed export curbs on two metals used in computer chips and solar cells,...