Objective:To study the effect of sevoflurane pretreatment combined with propofol on cerebral oxygen metabolism and inflammatory response during one-lung ventilation.Methods:A total of 92 patients who accepted pulmonar...Objective:To study the effect of sevoflurane pretreatment combined with propofol on cerebral oxygen metabolism and inflammatory response during one-lung ventilation.Methods:A total of 92 patients who accepted pulmonary lobectomy under one-lung ventilation in Changzheng Hospital Affiliated to Second Military Medical University between August 2014 and March 2016 were selected and divided into sevoflurane group and control group. Before one-lung ventilation (T1), 30 min after one-lung ventilation (T2) and 60 min after one-lung ventilation (T3), cerebral oxygen metabolism indexes and serum inflammation indexes were determined;after surgical resection, the lung tissue was collected to determine the expression of inflammatory signaling molecules and hypoxia injury molecules.Results: CjvO2 and ajdDCO2 levels as well as serum ICAM-1, IL-1β and TNF-α contents were not significantly different between two groups of patients at T1;CjvO2 levels as well as serum ICAM-1, IL-1β and TNF-α contents of sevoflurane group at T2 and T3 were significantly lower than those of control group while ajdDCO2 levels were significantly higher than those of control group;after surgical resection, TLR4, NF-kB, AQP-4, p38MAPK, HO-1, GLUT-1, HIF-1毩 and CHOP protein expression in lung tissue of sevoflurane group were significantly lower than those of control group.Conclusion:Sevoflurane pretreatment combined with propofol can improve the cerebral oxygen metabolism and inhibit the inflammatory response during one-lung ventilation.展开更多
Deformation allocation is an important factor that affects 720°curling forming from copper-coated steel strips to double-walled brazed tubes(DWBTs).In this study,four schemes of deformation allocation,considering...Deformation allocation is an important factor that affects 720°curling forming from copper-coated steel strips to double-walled brazed tubes(DWBTs).In this study,four schemes of deformation allocation,considering different weights of the total feed distance,are proposed,and a 3D finite element(FE)model of the multi-pass roll forming process for DWBT is developed and verified to investigate the cross-sectional evolution and deformation features.The results show the following.(i)In the 720°curling forming process from the steel strip into double-walled tubes,the curvature of the formed circular arc initially increases and then remains stable with roll forming,and the inner and outer tubes of the DWBT are formed in the third and fifth forming passes.Size forming can eliminate the gap between the double walls and improve the overall roundness.(ii)For different deformation allocations,the cross-sectional profiles of the roll-formed parts exhibit a discrepancy,and the deformation amount varies with the roll-forming process.The deformation amount in Scheme three is the maximum,and the cross-sectional profile deviates significantly from the ideal shape and fails to form a DWBT,which indicates that the deformation allocation is unsuitable.(iii)The roundness of the outer tube is better than that of the inner tube.Therefore,the roundness of the inner tube is the key to restricting the forming accuracy of the DWBT.Compared with Schemes one and two,Scheme four with a linear allocation of the total feed distance exhibits the best roundness,and the deformation allocation is reasonable;i.e.,when the contact points between the rollers and steel strip are in a straight line,the roundness of the DWBT is in good agreement with the ideal condition.展开更多
For QSTE700 high-strength steel rectangular welded tube,the mechanical properties of the weld zone vary with the distancefrom the centerline of the weld.Therefore,the accurate description of constitutive relationship ...For QSTE700 high-strength steel rectangular welded tube,the mechanical properties of the weld zone vary with the distancefrom the centerline of the weld.Therefore,the accurate description of constitutive relationship of the weld zone is of greatsignificance for the study of formability of QSTE700 rectangular welded tube.Firstly,the mechanical properties of parentand mixed specimens containing weld zone and parent zone were obtained by uniaxial tensile test.And based on the micro-hardness test,the width and the microhardness distribution of the weld zone were determined.Secondly,by subdividingthe weld zone into several small areas,and combining with the rule of mixtures and nanoindentation test,the continuous functional relationships of strength coefficient K,hardening coeffecient n and elastic modulus E were obtained,and then,the continuous constitutive relationship of QSTE700 rectangular welded tube was established.Finally,the validity and reliability of the continuous constitutive relationship of welded tube were verified by nanoindentation fest and rotary drawbending of rectangular welded tubc.Besides,it was found that the finite element model of rotary draw bending of QSTE700 rectangular welded tube established by using the continuous constitutive relationship can well simulate the cross sectiondeformation and wall thickness variation.展开更多
基金Natural Science Foundation of China No:81372103.
文摘Objective:To study the effect of sevoflurane pretreatment combined with propofol on cerebral oxygen metabolism and inflammatory response during one-lung ventilation.Methods:A total of 92 patients who accepted pulmonary lobectomy under one-lung ventilation in Changzheng Hospital Affiliated to Second Military Medical University between August 2014 and March 2016 were selected and divided into sevoflurane group and control group. Before one-lung ventilation (T1), 30 min after one-lung ventilation (T2) and 60 min after one-lung ventilation (T3), cerebral oxygen metabolism indexes and serum inflammation indexes were determined;after surgical resection, the lung tissue was collected to determine the expression of inflammatory signaling molecules and hypoxia injury molecules.Results: CjvO2 and ajdDCO2 levels as well as serum ICAM-1, IL-1β and TNF-α contents were not significantly different between two groups of patients at T1;CjvO2 levels as well as serum ICAM-1, IL-1β and TNF-α contents of sevoflurane group at T2 and T3 were significantly lower than those of control group while ajdDCO2 levels were significantly higher than those of control group;after surgical resection, TLR4, NF-kB, AQP-4, p38MAPK, HO-1, GLUT-1, HIF-1毩 and CHOP protein expression in lung tissue of sevoflurane group were significantly lower than those of control group.Conclusion:Sevoflurane pretreatment combined with propofol can improve the cerebral oxygen metabolism and inhibit the inflammatory response during one-lung ventilation.
基金the National Natural Science Foundation of China(Grant No.52275379).
文摘Deformation allocation is an important factor that affects 720°curling forming from copper-coated steel strips to double-walled brazed tubes(DWBTs).In this study,four schemes of deformation allocation,considering different weights of the total feed distance,are proposed,and a 3D finite element(FE)model of the multi-pass roll forming process for DWBT is developed and verified to investigate the cross-sectional evolution and deformation features.The results show the following.(i)In the 720°curling forming process from the steel strip into double-walled tubes,the curvature of the formed circular arc initially increases and then remains stable with roll forming,and the inner and outer tubes of the DWBT are formed in the third and fifth forming passes.Size forming can eliminate the gap between the double walls and improve the overall roundness.(ii)For different deformation allocations,the cross-sectional profiles of the roll-formed parts exhibit a discrepancy,and the deformation amount varies with the roll-forming process.The deformation amount in Scheme three is the maximum,and the cross-sectional profile deviates significantly from the ideal shape and fails to form a DWBT,which indicates that the deformation allocation is unsuitable.(iii)The roundness of the outer tube is better than that of the inner tube.Therefore,the roundness of the inner tube is the key to restricting the forming accuracy of the DWBT.Compared with Schemes one and two,Scheme four with a linear allocation of the total feed distance exhibits the best roundness,and the deformation allocation is reasonable;i.e.,when the contact points between the rollers and steel strip are in a straight line,the roundness of the DWBT is in good agreement with the ideal condition.
基金The authors would like to thank the Science and Technology Plan Project of Shenzhen Science and Technology Innovation Committee(JCYJ20180306171058717)Natural Science Basis Research Plan in Shaanxi Province of China(2019JZ-03).
文摘For QSTE700 high-strength steel rectangular welded tube,the mechanical properties of the weld zone vary with the distancefrom the centerline of the weld.Therefore,the accurate description of constitutive relationship of the weld zone is of greatsignificance for the study of formability of QSTE700 rectangular welded tube.Firstly,the mechanical properties of parentand mixed specimens containing weld zone and parent zone were obtained by uniaxial tensile test.And based on the micro-hardness test,the width and the microhardness distribution of the weld zone were determined.Secondly,by subdividingthe weld zone into several small areas,and combining with the rule of mixtures and nanoindentation test,the continuous functional relationships of strength coefficient K,hardening coeffecient n and elastic modulus E were obtained,and then,the continuous constitutive relationship of QSTE700 rectangular welded tube was established.Finally,the validity and reliability of the continuous constitutive relationship of welded tube were verified by nanoindentation fest and rotary drawbending of rectangular welded tubc.Besides,it was found that the finite element model of rotary draw bending of QSTE700 rectangular welded tube established by using the continuous constitutive relationship can well simulate the cross sectiondeformation and wall thickness variation.
