Effects of pre-compression on formation of dynamic precipitates and creep anisotropy of hot-extruded AZ91−2Y magnesium alloy

The creep anisotropy behavior under different stresses at 180℃ of hot-extruded AZ91−2Y magnesium alloy with pre-compression(PC)and without pre-compression(NPC)was studied.Microstructure,texture and mechanical properties of the alloy were examined by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM)and tensile creep tests.The results revealed that the creep resistance was proportional to the volume fraction of spherical Mg_(17)Al_(12) precipitates.The dynamic precipitation of large volume fraction of lamellar Mg_(17)Al_(12) in NPC samples leads to the basaláañslip as the dominant creep mechanism,and the NPC samples have obvious anisotropy.In the PC samples,dynamic precipitation of large volume fraction of spherical Mg_(17)Al_(12) has inhibitory effect on the basaláañslip.The pyramidalác+añslip and twinning improve the creep anisotropy resistance significantly.

A combined pre- and intra-operative nomogram in evaluation of degrees of liver cirrhosis predicts post-hepatectomy liver failure: a multicenter prospective study

Background:Adequate evaluation of degrees of liver cirrhosis is essential in surgical treatment of hepatocellular carcinoma(HCC)patients.The impact of the degrees of cirrhosis on prediction of post-hepatectomy liver failure(PHLF)remains poorly defined.This study aimed to construct and validate a combined pre-and intra-operative nomogram based on the degrees of cirrhosis in predicting PHLF in HCC patients using prospective multi-center’s data.Methods:Consecutive HCC patients who underwent hepatectomy between May 18,2019 and Dec 19,2020 were enrolled at five tertiary hospitals.Preoperative cirrhotic severity scoring(CSS)and intra-operative direct liver stiffness measurement(DSM)were performed to correlate with the Laennec histopathological grading system.The performances of the pre-operative nomogram and combined pre-and intra-operative nomogram in predicting PHLF were compared with conventional predictive models of PHLF.Results:For 327 patients in this study,histopathological studies showed the rates of HCC patients with no,mild,moderate,and severe cirrhosis were 41.9%,29.1%,22.9%,and 6.1%,respectively.Either CSS or DSM was closely correlated with histopathological stages of cirrhosis.Thirty-three(10.1%)patients developed PHLF.The 30-and 90-day mortality rates were 0.9%.Multivariate regression analysis showed four pre-operative variables[HBV-DNA level,ICG-R15,prothrombin time(PT),and CSS],and one intra-operative variable(DSM)to be independent risk factors of PHLF.The pre-operative nomogram was constructed based on these four pre-operative variables together with total bilirubin.The combined pre-and intra-operative nomogram was constructed by adding the intra-operative DSM.The pre-operative nomogram was better than the conventional models in predicting PHLF.The prediction was further improved with the combined pre-and intra-operative nomogram.Conclusions:The combined pre-and intra-operative nomogram further improved prediction of PHLF when compared with the pre-operative nomogram.