Markets opened lower on Tuesday, as Russia-Ukraine peace talks made scant progress and oil prices at 14-year highs kept investors on edge over imported inflation. The blue-chip NSE Nifty 50 index was down 0.41 per cent at 15,798.40, as of 0351 GMT, and the S&P BSE Sensex fell 0.39 per cent to 52,636.17. If losses hold, both indices would mark their fifth straight session of