First-principles calculations of the crystal structures, phase transition, and elastic properties of EuS have been carried out with the plane-wave pseudopotential density functional theory method. The calculated value...First-principles calculations of the crystal structures, phase transition, and elastic properties of EuS have been carried out with the plane-wave pseudopotential density functional theory method. The calculated values are in very good agreement with experimental data as well as some of the existing model calculations. The dependence of the elastic constants, the aggregate elastic modulus, and the elastic anisotropy on pressure have been investigated. Moreover, the variation of the Poisson＇s ratio, Debye temperature, and the compressional and shear elastic wave velocities with pressure have been investigated for the first time. Through the quasi-harmonic Debye model, the thermal expansions, heat capacities, Grneisen parameters and Debye temperatures dependence on the temperature and pressure are obtained in the pressure range from 0 GPa to 60 GPa and temperature range from 0 K to 800 K.展开更多
Feasibility of endoscopic retrograde cholangiopancreatography(ERCP) for biliary drainage is not always applicable due to anatomical alterations or to inability to access the papilla. Percutaneous transhepatic biliary ...Feasibility of endoscopic retrograde cholangiopancreatography(ERCP) for biliary drainage is not always applicable due to anatomical alterations or to inability to access the papilla. Percutaneous transhepatic biliary drainage has always been considered the only alternative for this indication. However,endoscopic ultrasonography-guided biliary drainage represents a valid option to replace percutaneous transhepatic biliary drainage when ERCP fails. According to the access site to the biliary tree,two kinds of approaches may be described: the intrahepatic and the extrahepatic. Endoscopic ultrasonography-guided rendezvous transpapillary drainage is performed where the second portion of the duodenum is easily reached but conventional ERCP fails. The recent introduction of self-expandable metal stents and lumen-apposing metal stents has improved this field. However,the role of the latter is still controversial. Echoendoscopic transmural biliary drainage can be challenging with potential severe adverse events. Therefore,trained endoscopists,in both ERCP and endoscopic ultrasonography are needed with surgical and radiological backup.展开更多
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.40804034 and No.11304141）, the Natural Science Foundation of the Education Department of Henan Province of China （No.2011B140014）, the Program for the Science and Technology Department of Henan Province of China （No. 112102310641）, and the Program for Innovative Research Team （in Science and Technology） in University of Henan Province （No.13IRTSTHN020）.
文摘First-principles calculations of the crystal structures, phase transition, and elastic properties of EuS have been carried out with the plane-wave pseudopotential density functional theory method. The calculated values are in very good agreement with experimental data as well as some of the existing model calculations. The dependence of the elastic constants, the aggregate elastic modulus, and the elastic anisotropy on pressure have been investigated. Moreover, the variation of the Poisson＇s ratio, Debye temperature, and the compressional and shear elastic wave velocities with pressure have been investigated for the first time. Through the quasi-harmonic Debye model, the thermal expansions, heat capacities, Grneisen parameters and Debye temperatures dependence on the temperature and pressure are obtained in the pressure range from 0 GPa to 60 GPa and temperature range from 0 K to 800 K.
文摘Feasibility of endoscopic retrograde cholangiopancreatography(ERCP) for biliary drainage is not always applicable due to anatomical alterations or to inability to access the papilla. Percutaneous transhepatic biliary drainage has always been considered the only alternative for this indication. However,endoscopic ultrasonography-guided biliary drainage represents a valid option to replace percutaneous transhepatic biliary drainage when ERCP fails. According to the access site to the biliary tree,two kinds of approaches may be described: the intrahepatic and the extrahepatic. Endoscopic ultrasonography-guided rendezvous transpapillary drainage is performed where the second portion of the duodenum is easily reached but conventional ERCP fails. The recent introduction of self-expandable metal stents and lumen-apposing metal stents has improved this field. However,the role of the latter is still controversial. Echoendoscopic transmural biliary drainage can be challenging with potential severe adverse events. Therefore,trained endoscopists,in both ERCP and endoscopic ultrasonography are needed with surgical and radiological backup.
