Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event

In the Jurassic period, the Early Toarcian oceanic anoxic event (about 183 million years ago) is associated with exceptionally high rates of organic-carbon burial, high palaeotemperatures and significant mass extinction. Heavy carbon-isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon, which is isotopically light. In contrast, examples of light carbon-isotope values from marine organic matter of Early Toarcian age have been explained principally in terms of localized upwelling of bottom water enriched in 12C versus 13C (refs 1,2,5,6). Here, however, we report carbon-isotope analyses of fossil wood which demonstrate that isotopically light carbon dominated all the upper oceanic, biospheric and atmospheric carbon reservoirs, and that this occurred despite the enhanced burial of organic carbon. We propose that--as has been suggested for the Late Palaeocene thermal maximum, some 55 million years ago--the observed patterns were produced by voluminous and extremely rapid release of methane from gas hydrate contained in marine continental-margin sediments.     

血糖指数在耐力运动中应用的研究进展

综述长时间、大强度运动前、中、以及运动后恢复期间不同血糖指数的含碳水化合物(CHO)食物的补充对耐力运动能力及代谢的影响,目的在于为教练员、运动员及体育科研人员提供更为有益的运动营养补充方式,使营养补充与提高运动能力之间的关系达到更加优化的程度。     

甲烷预混气螺旋爆轰的定量不稳定性研究

针对CH4这种特别气体,对其实验结果运用数字化处理方法研究CH4稳定性.在内径50.8 mm圆形管道内获得CH4+2O2预混气在不同初始压力条件下的胞格爆轰结果并使用烟膜记录,且测得的平均爆轰速度数据与CJ爆轰速度接近,在初始压力高于5 kPa时爆轰可稳定传播.烟膜上形成的三波点轨迹十分不规则.为减少人为误差,使用改进后的数字化处理烟膜图像的技术方法,从烟膜轨迹中得出柱状图及自相关函数结果,发现CH4+2O2是一种爆轰十分不稳定的气体,并给出CH4+2O2预混气的爆轰胞格尺寸及差距,结果显示人为测量结果偏大而数字化处理方法更为准确.这种方法能计算CH4+2O2预混气胞格尺寸及不稳定度,完善了定量化预混气不稳定程度的方法.