SHANGHAI, May 14 — Not very long ago, China saw itself as a nation on the verge of a technological breakthrough. But today, China appears shocked and shamed by a scandal that has already begun to tarnish that vision. It involves a top computer scientist, Chen Jin, who became a national hero in 2003 when he said he had created one of China's first digital signal processing computer chips, sophisticated microchips that can process digitized data for mobile phones, cameras and other electronic devices. His milestone seemed to hold the promise of helping close the enormous gaps with the West...