Experts and former leaders from China and Central Asian countries called on Monday for the expansion of cooperation beyond ties in the energy sector.   "Energy is fundamental, but the economic ties between China and Central Asia are wide-range and multi-form," said Xing Guangcheng, a researcher at the Chinese Academy of Social Sciences.   China should "broaden the thinking" in its collaboration with Central Asia, Xing emphasized.   Trade between China and its fiv...