Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which cau...Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.展开更多
BACKGROUND Progressive pancreaticβcell dysfunction is a fundamental aspect of the pathology underlying type 2 diabetes mellitus(T2DM).Recently,mesenchymal stem cell(MSC)transplantation has emerged as a new therapeuti...BACKGROUND Progressive pancreaticβcell dysfunction is a fundamental aspect of the pathology underlying type 2 diabetes mellitus(T2DM).Recently,mesenchymal stem cell(MSC)transplantation has emerged as a new therapeutic method due to its ability to promote the regeneration of pancreaticβcells.However,current studies have focused on its efficacy,and there are few clinical studies on its safety.AIM To evaluate the safety of human umbilical cord(hUC)-MSC infusion in T2DM treatment.METHODS An open-label and randomized phase 2 clinical trial was designed to evaluate the safety of hUC-MSC transplantation in T2DM in a Class A hospital.Ten patients in the placebo group received acellular saline intravenously once per week for 3 wk.Twenty-four patients in the hUC-MSC group received hUC-MSCs(1×106 cells/kg)intravenously once per week for 3 wk.Diabetic clinical symptoms and signs,laboratory findings,and imaging findings were evaluated weekly for the 1st mo and then at weeks 12 and 24 post-treatment.RESULTS No serious adverse events were observed during the 24-wk follow-up.Four patients(16.7%)in the hUC-MSC group experienced transient fever,which occurred within 24 h after the second or third infusion;this did not occur in any patients in the placebo group.One patient from the hUC-MSC group experienced hypoglycemic attacks within 1 mo after transplantation.Significantly lower lymphocyte levels(weeks 2 and 3)and thrombin coagulation time(week 2)were observed in the hUC-MSC group compared to those in the placebo group(all P<0.05).Significantly higher platelet levels(week 3),immunoglobulin levels(weeks 1,2,3,and 4),fibrinogen levels(weeks 2 and 3),D-dimer levels(weeks 1,2,3,4,12,and 24),and neutrophil-to-lymphocyte ratios(weeks 2 and 3)were observed in the hUC-MSC group compared to those in the placebo group(all P<0.05).There were no significant differences between the two groups for tumor markers(alpha-fetoprotein,carcinoembryonic antigen,and carbohydrate antigen 199)or blood fat.No liver damage or other side effects were observed on chest X-ray.CONCLUSION Our study suggested that hUC-MSC transplantation has good tolerance and high safety in the treatment of T2DM.It can improve human immunity and inhibit lymphocytes.Coagulation function should be monitored vigilantly for abnormalities.展开更多
基金Fofinancially supported by the National Natural Science Foundation of China(Grant No.52271288)Peiyang Scholar Initiation Fund from Tianjin University。
文摘Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.
基金Shenzhen Science and Technology Innovation Committee Projects,No.JCYJ20170816105416349Shenzhen High-Level Hospital Construction Fund,Shenzhen Key Medical Discipline Construction Fund,No.SZXK010.
文摘BACKGROUND Progressive pancreaticβcell dysfunction is a fundamental aspect of the pathology underlying type 2 diabetes mellitus(T2DM).Recently,mesenchymal stem cell(MSC)transplantation has emerged as a new therapeutic method due to its ability to promote the regeneration of pancreaticβcells.However,current studies have focused on its efficacy,and there are few clinical studies on its safety.AIM To evaluate the safety of human umbilical cord(hUC)-MSC infusion in T2DM treatment.METHODS An open-label and randomized phase 2 clinical trial was designed to evaluate the safety of hUC-MSC transplantation in T2DM in a Class A hospital.Ten patients in the placebo group received acellular saline intravenously once per week for 3 wk.Twenty-four patients in the hUC-MSC group received hUC-MSCs(1×106 cells/kg)intravenously once per week for 3 wk.Diabetic clinical symptoms and signs,laboratory findings,and imaging findings were evaluated weekly for the 1st mo and then at weeks 12 and 24 post-treatment.RESULTS No serious adverse events were observed during the 24-wk follow-up.Four patients(16.7%)in the hUC-MSC group experienced transient fever,which occurred within 24 h after the second or third infusion;this did not occur in any patients in the placebo group.One patient from the hUC-MSC group experienced hypoglycemic attacks within 1 mo after transplantation.Significantly lower lymphocyte levels(weeks 2 and 3)and thrombin coagulation time(week 2)were observed in the hUC-MSC group compared to those in the placebo group(all P<0.05).Significantly higher platelet levels(week 3),immunoglobulin levels(weeks 1,2,3,and 4),fibrinogen levels(weeks 2 and 3),D-dimer levels(weeks 1,2,3,4,12,and 24),and neutrophil-to-lymphocyte ratios(weeks 2 and 3)were observed in the hUC-MSC group compared to those in the placebo group(all P<0.05).There were no significant differences between the two groups for tumor markers(alpha-fetoprotein,carcinoembryonic antigen,and carbohydrate antigen 199)or blood fat.No liver damage or other side effects were observed on chest X-ray.CONCLUSION Our study suggested that hUC-MSC transplantation has good tolerance and high safety in the treatment of T2DM.It can improve human immunity and inhibit lymphocytes.Coagulation function should be monitored vigilantly for abnormalities.
