Transformation mechanism of ions on different waters in alpine region.

The study investigates transformation mechanism of ions on different waters in Alpine region through analyzed the hydrochemical characteristics of the major ions of precipitation, glacier and snow meltwater, supra-permafrost water and river water in permafrost regions in the Tibetan Plateau under climate warming. The results showed that, The relation between recharge and discharge was the major ways for ionic transformation of each water body. Precipitation and glacier and snow meltwater are the main input sources for ionic transformation, and river water is the final output source. Different water bodies had different ionic concentrations and different hydrochemical types. However, different water bodies in different months (from June to September) also had different hydrochemical types. The water - rock interaction, reactions for ions, dilution effect and other effect for ions played an important role in the process of ion transformation. The increasing of temperature would lead to the accelerated melting of glaciers, permafrost and snow in the alpine regions, so the amount of supra-permafrost water and glacier and snow meltwater will increase, which leads to the increase of runoff. Meanwhile, the increase of temperature makes evaporation stronger. The strong of evaporation will accelerate the transformation of liquid water to gaseous water. Moreover, ion translation and water conversion are synchronous. Accordingly, ions are also accelerating transformation in the process of accelerated transformation of water body. Climate change is not only the main driving force for multiphase water transformation, but also the main driving force for the ion transformation of various water bodies.

The sources of supra-permafrost water and its hydrological effect based on stable isotopes in the third pole region.

The sources of supra-permafrost water and its hydrological effects were studied, based on the presence of stable isotopes in 562 samples collected in different ablation periods from the source regions of the Yangtze River. The δ18O (δD and d-excess) values for the initial ablation, ablation, and end ablation periods were -10.18‰ (-71.39‰ and 10.08‰), -12.14‰ (-85.58‰ and 11.51‰) and -11.50‰ (-78.75‰ and 13.23‰), respectively. The order of the slopes for the supra-permafrost water evaporation lines from the different ablation periods was initial ablation (IA) > ablation (A) > end ablation (EA). An anti-altitude effect is documented here, for a specific altitude range, in what is believed to be the first record of such an occurrence. Outside of that range, clear altitude effects were apparent. We have been able to show that supra-permafrost water was mainly recharged by atmospheric precipitation, ground ice, and glacier and snow meltwater, in the initial ablation and end ablation periods, and contributions from glacier and snow meltwater were mainly concentrated in higher altitude regions. In contrast, in the ablation period, supra-permafrost water was mainly recharged by atmospheric precipitation and ground ice. The contributions of precipitation to supra-permafrost water were 78.79%, 85.47%, and 82.99% in the initial ablation, ablation, and end ablation periods, respectively. The contributions of ground ice to the supra-permafrost water were 14.05%, 14.53%, and 11.94%, respectively, while contributions of glacier and snow meltwater were 7.15% and 5.07% in the initial and end ablation period. For the initial ablation, ablation, and end ablation periods, contributions from atmospheric precipitation to the supra-permafrost water were 85.47%, 86.86%, and 86.84%, while contributions from ground ice were 14.53%, 13.14% and 13.16%, respectively.

[Coronary artery bypass graft for patients with ascending aorta atherosclerosis].

OBJECTIVE: The increasing number of aged patients with severe ascending aorta atherosclerosis who are undergoing coronary artery bypass graft (CABG) present high risk for ascending aortic cannulation, cross-clamping or partial occluding and proximal anastomosis. We reviewed the surgical experience in 22 patients of CABG with ascending aorta atherosclerosis and tried to find the way to minimize the complications. METHODS: Twenty-two patients with severe atherosclerotic and calcified ascending aorta underwent CABG in our hospital. Thirteen of them received CABG on beating heart. Nine patients had their CABG with extracorporeal circulation. With deep hypothermia, we reduced the flow rate and intermittently arrested the circulation for the proximal anastomosis on ascending aorta in 5 patients with neither cross-clamping nor partial occluding. The sequential grafts and "Y" type anastomosis between reversed saphenous venous grafts were employed. RESULTS: Twenty of the patients survived after surgery. One died of inhalation pneumonia in two weeks after surgery. Another died of right hemothorax in ten days after surgery. The complications include: pneumonia 4 patients (18%), angina 2 patients (9%), ventricular fibrillation 1 patients (5%), post-CABG myocardium infarction 1 case (5%) and hemothorax 1 case (5%). There is no neurologic complications or aortic dissection after CABG. CONCLUSION: CABG on beating heart with pedicel arterial grafts is the best approach to performing the surgery without touching the diseased ascending aorta. Ventricular fibrillation under mild hypothermia cardiopulmonary bypass and left ventricular suction were employed for quiet and bloodless field while distal anastomosis had no cross-clamping the ascending aorta. Also deep hypothermia and intermittently circulatory arrest offer quiet and bloodless field for the proximal anastomosis on ascending aorta without cross-clamping or partial-occluding. Distal sequential anastomosis and proximal "Y" type anastomosis are the effective approach to minimizing the proximal anastomosis on the ascending aorta.