In the process of in situ leaching of uranium,the microstructure controls and influences the flow distribution,percolation characteristics,and reaction mechanism of lixivium in the pores of reservoir rocks and directl...In the process of in situ leaching of uranium,the microstructure controls and influences the flow distribution,percolation characteristics,and reaction mechanism of lixivium in the pores of reservoir rocks and directly affects the leaching of useful components.In this study,the pore throat,pore size distribution,and mineral composition of low-permeability uranium-bearing sandstone were quantitatively analyzed by high pressure mercury injection,nuclear magnetic resonance,X-ray diffraction,and wavelength-dispersive X-ray fluorescence.The distribution characteristics of pores and minerals in the samples were qualitatively analyzed using energy-dispersive scanning electron microscopy and multi-resolution CT images.Image registration with the landmarks algorithm provided by FEI Avizo was used to accurately match the CT images with different resolutions.The multi-scale and multi-mineral digital core model of low-permeability uranium-bearing sandstone is reconstructed through pore segmentation and mineral segmentation of fusion core scanning images.The results show that the pore structure of low-permeability uranium-bearing sandstone is complex and has multi-scale and multi-crossing characteristics.The intergranular pores determine the main seepage channel in the pore space,and the secondary pores have poor connectivity with other pores.Pyrite and coffinite are isolated from the connected pores and surrounded by a large number of clay minerals and ankerite cements,which increases the difficulty of uranium leaching.Clays and a large amount of ankerite cement are filled in the primary and secondary pores and pore throats of the low-permeability uraniumbearing sandstone,which significantly reduces the porosity of the movable fluid and results in low overall permeability of the cores.The multi-scale and multi-mineral digital core proposed in this study provides a basis for characterizing macroscopic and microscopic pore-throat structures and mineral distributions of low-permeability uranium-bearing sandstone and can better understand the seepage characteristics.展开更多
Objective: To study the effect of dexmedetomidine combined with ulinastatin on RAAS system, coagulation indexes and oxygen free radicals after acute aortic dissection surgery. Methods: A total of 48 patients with aort...Objective: To study the effect of dexmedetomidine combined with ulinastatin on RAAS system, coagulation indexes and oxygen free radicals after acute aortic dissection surgery. Methods: A total of 48 patients with aortic dissection who accepted endovascular graft exclusion treatment in the hospital between May 2014 and February 2017 were selected and randomly divided into two groups, group A received dexmedetomidine, ulinastatin combined with general anesthesia, and group B received general anesthesia. The RAAS hormones, coagulation indexes and oxygen free radical indexes were measured 1 d before surgery, during operation and 24 h after surgery. Results: During operation and after operation, serum REN, AT-II, ALD, FIB, DD, MDA and MPO contents as well as APTT and TT levels of both groups of patients were significantly higher than those before operation while TAOC and TSOD contents were significantly lower than those before operation, and serum REN, AT-II, ALD, FIB, DD, MDA and MPO contents as well as APTT and TT levels of group A were significantly lower than those of group B while TAOC and TSOD contents were significantly higher than those of group B. Conclusion: Dexmedetomidine combined with ulinastatin for acute aortic dissection can inhibit RAAS system and oxygen free radical generation and improve coagulation function.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.11775107)the Key Projects of Education Department of Hunan Province of China(No.16A184).
文摘In the process of in situ leaching of uranium,the microstructure controls and influences the flow distribution,percolation characteristics,and reaction mechanism of lixivium in the pores of reservoir rocks and directly affects the leaching of useful components.In this study,the pore throat,pore size distribution,and mineral composition of low-permeability uranium-bearing sandstone were quantitatively analyzed by high pressure mercury injection,nuclear magnetic resonance,X-ray diffraction,and wavelength-dispersive X-ray fluorescence.The distribution characteristics of pores and minerals in the samples were qualitatively analyzed using energy-dispersive scanning electron microscopy and multi-resolution CT images.Image registration with the landmarks algorithm provided by FEI Avizo was used to accurately match the CT images with different resolutions.The multi-scale and multi-mineral digital core model of low-permeability uranium-bearing sandstone is reconstructed through pore segmentation and mineral segmentation of fusion core scanning images.The results show that the pore structure of low-permeability uranium-bearing sandstone is complex and has multi-scale and multi-crossing characteristics.The intergranular pores determine the main seepage channel in the pore space,and the secondary pores have poor connectivity with other pores.Pyrite and coffinite are isolated from the connected pores and surrounded by a large number of clay minerals and ankerite cements,which increases the difficulty of uranium leaching.Clays and a large amount of ankerite cement are filled in the primary and secondary pores and pore throats of the low-permeability uraniumbearing sandstone,which significantly reduces the porosity of the movable fluid and results in low overall permeability of the cores.The multi-scale and multi-mineral digital core proposed in this study provides a basis for characterizing macroscopic and microscopic pore-throat structures and mineral distributions of low-permeability uranium-bearing sandstone and can better understand the seepage characteristics.
文摘Objective: To study the effect of dexmedetomidine combined with ulinastatin on RAAS system, coagulation indexes and oxygen free radicals after acute aortic dissection surgery. Methods: A total of 48 patients with aortic dissection who accepted endovascular graft exclusion treatment in the hospital between May 2014 and February 2017 were selected and randomly divided into two groups, group A received dexmedetomidine, ulinastatin combined with general anesthesia, and group B received general anesthesia. The RAAS hormones, coagulation indexes and oxygen free radical indexes were measured 1 d before surgery, during operation and 24 h after surgery. Results: During operation and after operation, serum REN, AT-II, ALD, FIB, DD, MDA and MPO contents as well as APTT and TT levels of both groups of patients were significantly higher than those before operation while TAOC and TSOD contents were significantly lower than those before operation, and serum REN, AT-II, ALD, FIB, DD, MDA and MPO contents as well as APTT and TT levels of group A were significantly lower than those of group B while TAOC and TSOD contents were significantly higher than those of group B. Conclusion: Dexmedetomidine combined with ulinastatin for acute aortic dissection can inhibit RAAS system and oxygen free radical generation and improve coagulation function.
