RINA CHANDRAN  CHINA has tightened its grip over a wide range of industries including technology firms, as authorities introduce sweeping reforms to activities they consider harmful to young people, from celebrity fan culture to private tutoring. The crackdown on some of China's biggest tech companies including Alibaba, Didi and Tencent comprise measures ranging from limiting the amount of time spent on online games, to ordering food delivery companies to better protect workers. By imposing these rules, the Chinese government has said it is hoping to create "positive energy" among young people, and educate them on what Beijing considers as "correct…