Peng Si caresses his mother's head at a hospital in Guangzhou, South China's Guangdong province on Sep 10, 2011. The 22-year-old son returned to Guangzhou from studying in the US to donate part of his liver to his mother, who was suffering from fulminant hepatitis. With 60 percent of his liver transplanted during a successful operation, he has saved his mother's life. [Photo/Xinhua]