The presence of antiphospholipid antibodies was shown to be associated with thrombosis in coronavirus disease 2019(COVID-19)patients.Recently,according to reports from several studies,the vaccineinduced immune thrombo...The presence of antiphospholipid antibodies was shown to be associated with thrombosis in coronavirus disease 2019(COVID-19)patients.Recently,according to reports from several studies,the vaccineinduced immune thrombotic thrombocytopenia is mediated by anti-platelet factor 4(PF4)-polyanion complex in adenovirus-vectored COVID-19 vaccine recipients.It is impendent to explore whether inactivated COVID-19 vaccine widely used in China influences prothrombotic autoantibody production and induces thrombosis.In this prospective study,we recruited 406 healthcare workers who received two doses,21 days apart,of inactivated severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)vaccine(BBIBP-CorV,Sinopharm).Paired blood samples taken before vaccination and four weeks after the second vaccination were used in detecting prothrombotic autoantibodies,including anticardiolipin(aCL),anti-b2 glycoprotein I(ab2GP1),anti-phosphatidylserine/prothrombin(aPS/PT),and anti-PF4-heparin.The seroconversion rate of SARS-CoV-2 specific antibodies was 95.81%(389/406)four weeks after vaccination.None of the subjects had spontaneous thrombosis or thrombocytopenia over a minimum follow-up period of eight weeks.There was no significant difference in the presence of all ten autoantibodies between samples collected before and after vaccination:for aCL,IgG(7 vs.8,P=0.76),IgM(41 vs.44,P=0.73),IgA(4 vs.4,P=1.00);anti-b2GP1,IgG(7 vs.6,P=0.78),IgM(6 vs.5,P=0.76),IgA(3 vs.5,P=0.72);aPS/PT IgG(0 vs.0,P=1.00),IgM(6 vs.5,P=0.76);aPF4-heparin(2 vs.7,P=0.18),and antinuclear antibody(ANA)(18 vs.21,P=0.62).Notably,seven cases presented with anti-PF4-heparin antibodies(range:1.18–1.79 U/mL)after vaccination,and none of them exhibited any sign of thrombotic disorder.In conclusion,inactivated SARS-CoV-2 vaccine does not influence the profile of antiphospholipid antibody and anti-PF4-heparin antibody nor increase the risk of thrombosis.展开更多
In order to satisfy the machining requirements of aero-engine casing in modern aviation industry, this paper investigates three main issues during the design and development process of a five-axis machine tool with hi...In order to satisfy the machining requirements of aero-engine casing in modern aviation industry, this paper investigates three main issues during the design and development process of a five-axis machine tool with high accuracy, stiffness and efficiency, including whole structure design,key components design, and supporting stiffness design. First, an appropriate structure of five-axis machine tool is determined considering the processing characteristics of aero-engine casing. Then, a dual drive swing head and a compact motorized spindle are designed with enough drive capability and stiffness, and related structure, assembly method, cooling technology, and performance simulation are given in detail. Next, a design method of supporting stiffness of guide is proposed through the deformation prediction of the spindle end. Based on above work, a prototype of machine tool is developed, and some experiments are carried out, including performance tests of swing head and motorized spindle, and machining of a simulated workpiece of aero-engine casing. All experimental results show that the machine tool has satisfactory accuracy, stiffness and efficiency, which meets the machining requirements of aero-engine casing. The main work can be used as references for engineers and technicians, which are meaningful in practice.展开更多
Silk protein builds one of the strongest natural fibers based on its complex nanocomposite structures.However,the mechanical performance of silk protein,related to its molecular structure and packing is still elusive....Silk protein builds one of the strongest natural fibers based on its complex nanocomposite structures.However,the mechanical performance of silk protein,related to its molecular structure and packing is still elusive.In this study,we constructed an atomistic silk protein network model,which reproduces the extensive connection topology of silk protein with structure details of theβ-sheet crystallites and amorphous domains.With the silk protein network model,we investigated the structure evolution and stress distribution of silk protein under external loading.We found a pre-stretching treatment during the spinning process can improve the strength of silk protein.This treatment improves the properties of silk protein network,i.e.,increases the number of nodes and bridges,makes the nodes distributed homogeneously,and induces the bridges in the network well aligned to the loading direction,which is of great benefit to the mechanical performances of silk protein.Our study not only provides a realized atomistic model for silk protein network that well represents the structures and deformations of silk proteins under loading,but also gains deep insights into the mechanism how the pre-loading on silk proteins during spinning improves the mechanical properties of silk fibers.展开更多
基金supported by the Cultivation Project of Shanghai Major Infectious Disease Research Base(20dz2210500)the Shanghai Key Laboratory of Emergency Prevention,Diagnosis and Treatment of Respiratory Infectious Diseases(20dz2261100)the National Natural Science Foundation of China(81671589 and 81871272).
文摘The presence of antiphospholipid antibodies was shown to be associated with thrombosis in coronavirus disease 2019(COVID-19)patients.Recently,according to reports from several studies,the vaccineinduced immune thrombotic thrombocytopenia is mediated by anti-platelet factor 4(PF4)-polyanion complex in adenovirus-vectored COVID-19 vaccine recipients.It is impendent to explore whether inactivated COVID-19 vaccine widely used in China influences prothrombotic autoantibody production and induces thrombosis.In this prospective study,we recruited 406 healthcare workers who received two doses,21 days apart,of inactivated severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)vaccine(BBIBP-CorV,Sinopharm).Paired blood samples taken before vaccination and four weeks after the second vaccination were used in detecting prothrombotic autoantibodies,including anticardiolipin(aCL),anti-b2 glycoprotein I(ab2GP1),anti-phosphatidylserine/prothrombin(aPS/PT),and anti-PF4-heparin.The seroconversion rate of SARS-CoV-2 specific antibodies was 95.81%(389/406)four weeks after vaccination.None of the subjects had spontaneous thrombosis or thrombocytopenia over a minimum follow-up period of eight weeks.There was no significant difference in the presence of all ten autoantibodies between samples collected before and after vaccination:for aCL,IgG(7 vs.8,P=0.76),IgM(41 vs.44,P=0.73),IgA(4 vs.4,P=1.00);anti-b2GP1,IgG(7 vs.6,P=0.78),IgM(6 vs.5,P=0.76),IgA(3 vs.5,P=0.72);aPS/PT IgG(0 vs.0,P=1.00),IgM(6 vs.5,P=0.76);aPF4-heparin(2 vs.7,P=0.18),and antinuclear antibody(ANA)(18 vs.21,P=0.62).Notably,seven cases presented with anti-PF4-heparin antibodies(range:1.18–1.79 U/mL)after vaccination,and none of them exhibited any sign of thrombotic disorder.In conclusion,inactivated SARS-CoV-2 vaccine does not influence the profile of antiphospholipid antibody and anti-PF4-heparin antibody nor increase the risk of thrombosis.
基金co-supported by the Natural Science Foundation of Beijing(No.3214043)the Project of State Key Lab of Tribology of Tsinghua University(No.SKLT2021D16)the National Natural Science Foundation of China(No.51975319)。
文摘In order to satisfy the machining requirements of aero-engine casing in modern aviation industry, this paper investigates three main issues during the design and development process of a five-axis machine tool with high accuracy, stiffness and efficiency, including whole structure design,key components design, and supporting stiffness design. First, an appropriate structure of five-axis machine tool is determined considering the processing characteristics of aero-engine casing. Then, a dual drive swing head and a compact motorized spindle are designed with enough drive capability and stiffness, and related structure, assembly method, cooling technology, and performance simulation are given in detail. Next, a design method of supporting stiffness of guide is proposed through the deformation prediction of the spindle end. Based on above work, a prototype of machine tool is developed, and some experiments are carried out, including performance tests of swing head and motorized spindle, and machining of a simulated workpiece of aero-engine casing. All experimental results show that the machine tool has satisfactory accuracy, stiffness and efficiency, which meets the machining requirements of aero-engine casing. The main work can be used as references for engineers and technicians, which are meaningful in practice.
基金This work was supported by the National Natural Science Foundation of China(Grants Nos.12122212,11932017,11772054,and 11772055).
文摘Silk protein builds one of the strongest natural fibers based on its complex nanocomposite structures.However,the mechanical performance of silk protein,related to its molecular structure and packing is still elusive.In this study,we constructed an atomistic silk protein network model,which reproduces the extensive connection topology of silk protein with structure details of theβ-sheet crystallites and amorphous domains.With the silk protein network model,we investigated the structure evolution and stress distribution of silk protein under external loading.We found a pre-stretching treatment during the spinning process can improve the strength of silk protein.This treatment improves the properties of silk protein network,i.e.,increases the number of nodes and bridges,makes the nodes distributed homogeneously,and induces the bridges in the network well aligned to the loading direction,which is of great benefit to the mechanical performances of silk protein.Our study not only provides a realized atomistic model for silk protein network that well represents the structures and deformations of silk proteins under loading,but also gains deep insights into the mechanism how the pre-loading on silk proteins during spinning improves the mechanical properties of silk fibers.
