The Sensex at the Bombay Stock Exchange gained 81 points, or 0.5 per cent, to 17,772 in opening trade, this morning, on sustained buying by funds and retail investors, driven by the government's bid to revive investment. Later, the Sensex gained some more ground, and stood 115 points, or 0.7 per cent in the positive zone, at 17,806 in afternoon deals, a short while ago.Other Asian markets in Japan, Hong Kong, South Korea, Singapore and Taiwan were trading mixed, today. The US Dow Jones Industrial Average had ended flat in yesterday's trade.