The top economic aide to China’s President Xi Jinping has told researchers at the country’s leading scientific institution to keep a “low profile” and stay down to earth. The comments by Vice-Premier Liu He were published on the website of the Chinese Academy of Sciences (CAS) on Monday but Friday’s visit was not reported in state media. His visit came amid a deepening “technology war” with Washington restricting exports of key components to China while Beijing blamed the US for trying to impede the country’s technological advancement.