Background:China has experienced a COVID-19 wave caused by Omicron XBB variant starting in April 2023.Our aim is to conduct a retrospective analysis exploring the dynamics of the outbreak under counterfactual scenario...Background:China has experienced a COVID-19 wave caused by Omicron XBB variant starting in April 2023.Our aim is to conduct a retrospective analysis exploring the dynamics of the outbreak under counterfactual scenarios that combine the use of vaccines,antiviral drugs,and nonpharmaceutical interventions.Methods:We developed a mathematical model of XBB transmission in China,which has been calibrated using SARS-CoV-2 positive rates per week.Intrinsic age-specific infection-hospitalization risk,infection-ICU risk,and infection-fatality risk were used to estimate disease burdens,characterized as number of hospital admissions,ICU admissions,and deaths.Results:We estimated that in absence of behavioral change,the XBB outbreak in spring 2023 would have resulted in 0.86 billion infections(∼61%of the total population).Our counterfactual analysis shows that the synergetic effect of vaccination(70%vaccination coverage),antiviral treatment(20%receiving antiviral treatment),and moderate nonpharmaceutical interventions(20%isolation and L1 PHSMs)could reduce the number of deaths to levels close to seasonal influenza(1.17 vs.0.65 per 10,000 individuals and 5.85 vs.3.85 per 10,000 individuals aged 60+,respectively).The maximum peak prevalence of hospital and ICU admissions are estimated to be lower than the corresponding capacities(8.6 vs.10.4 per 10,000 individuals and 1.2 vs.2.1 per 10,000 individuals,respectively).Conclusion:Our findings suggest that the capacity of the Chinese healthcare system was adequate to face the Omicron XBB wave in spring 2023 but,at the same time,supports the importance of administering highly effective vaccine with long-lasting immune response,and the use of antiviral treatments.展开更多
The revised funding detail is given below.“The study was supported by grants from the Key Program of the National Natural Science Foundation of China(82130093),the National Key Research and Development Program of Chi...The revised funding detail is given below.“The study was supported by grants from the Key Program of the National Natural Science Foundation of China(82130093),the National Key Research and Development Program of China(grant no.2023YFC0872600),and the National Institute for Health Research(NIHR)(grant no.16/137/109)using UK aid from the UK Government to support global health research.We also acknowledge grant from Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response(20dz2260100).The views expressed in this publication are those of the author(s)and not necessarily those of the NIHR or the UK Department of Health and Social Care.”展开更多
In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical pro...In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical properties and wear resistance of medium manganese steel reinforced with Ti(C,N)particles was investigated.It was found that the matrix of medium manganese steel was austenite.The austenite grain size was refined,and Ti(C,N)particles were precipitated after aging treatment.Compared to that of the as-hot rolled sample,the initial hardness of 500°C aged sample increased by 9.5%to 312.86 HV,whose impact energy was more than doubled to 148.5 J.As the aging temperature raised to 600°C,the initial hardness changed slightly.However,the impact energy dropped significantly to 8 J due to the aggregation of Mn at the grain boundaries.In addition,the main wear mechanisms of the samples were fatigue wear and abrasive wear.It was worth noting that 500°C aged sample exhibited the best wear resistance under a 300 N applied load,whose wear loss was just half of the as-hot rolled sample.The relationship between wear loss and mechanical properties indicated that the wear resistance of medium manganese steel was independent of the initial hardness.The large difference in the wear resistance was predominately due to the outstanding work hardening ability of 500°C aged sample,whose strengthening mechanisms were contributed from transformation induced plasticity(TRIP)effect,dislocation strengthening,twinning induced plasticity(TWIP)effect,and precipitation strengthening.展开更多
基金supported by grants from the Key Program of the National Natural Science Foundation of China(82,130,093)the National Institute for Health Research(NIHR)(grant no.16/137/109)using UK aid from the UK Government to support global health researchgrant from Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response(20dz2260100).
文摘Background:China has experienced a COVID-19 wave caused by Omicron XBB variant starting in April 2023.Our aim is to conduct a retrospective analysis exploring the dynamics of the outbreak under counterfactual scenarios that combine the use of vaccines,antiviral drugs,and nonpharmaceutical interventions.Methods:We developed a mathematical model of XBB transmission in China,which has been calibrated using SARS-CoV-2 positive rates per week.Intrinsic age-specific infection-hospitalization risk,infection-ICU risk,and infection-fatality risk were used to estimate disease burdens,characterized as number of hospital admissions,ICU admissions,and deaths.Results:We estimated that in absence of behavioral change,the XBB outbreak in spring 2023 would have resulted in 0.86 billion infections(∼61%of the total population).Our counterfactual analysis shows that the synergetic effect of vaccination(70%vaccination coverage),antiviral treatment(20%receiving antiviral treatment),and moderate nonpharmaceutical interventions(20%isolation and L1 PHSMs)could reduce the number of deaths to levels close to seasonal influenza(1.17 vs.0.65 per 10,000 individuals and 5.85 vs.3.85 per 10,000 individuals aged 60+,respectively).The maximum peak prevalence of hospital and ICU admissions are estimated to be lower than the corresponding capacities(8.6 vs.10.4 per 10,000 individuals and 1.2 vs.2.1 per 10,000 individuals,respectively).Conclusion:Our findings suggest that the capacity of the Chinese healthcare system was adequate to face the Omicron XBB wave in spring 2023 but,at the same time,supports the importance of administering highly effective vaccine with long-lasting immune response,and the use of antiviral treatments.
文摘The revised funding detail is given below.“The study was supported by grants from the Key Program of the National Natural Science Foundation of China(82130093),the National Key Research and Development Program of China(grant no.2023YFC0872600),and the National Institute for Health Research(NIHR)(grant no.16/137/109)using UK aid from the UK Government to support global health research.We also acknowledge grant from Shanghai Key Laboratory of Infectious Diseases and Biosafety Emergency Response(20dz2260100).The views expressed in this publication are those of the author(s)and not necessarily those of the NIHR or the UK Department of Health and Social Care.”
基金The authors acknowledge the support from the National Natural Foundation of China(Grant No.51974084)Taiyuan University of Science and Technology Scientific Research Initial Funding(Grant Nos.20202039 and 20212052)China Postdoctoral Science Foundation(Grant Nos.2020M673194 and 2020T130329).
文摘In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical properties and wear resistance of medium manganese steel reinforced with Ti(C,N)particles was investigated.It was found that the matrix of medium manganese steel was austenite.The austenite grain size was refined,and Ti(C,N)particles were precipitated after aging treatment.Compared to that of the as-hot rolled sample,the initial hardness of 500°C aged sample increased by 9.5%to 312.86 HV,whose impact energy was more than doubled to 148.5 J.As the aging temperature raised to 600°C,the initial hardness changed slightly.However,the impact energy dropped significantly to 8 J due to the aggregation of Mn at the grain boundaries.In addition,the main wear mechanisms of the samples were fatigue wear and abrasive wear.It was worth noting that 500°C aged sample exhibited the best wear resistance under a 300 N applied load,whose wear loss was just half of the as-hot rolled sample.The relationship between wear loss and mechanical properties indicated that the wear resistance of medium manganese steel was independent of the initial hardness.The large difference in the wear resistance was predominately due to the outstanding work hardening ability of 500°C aged sample,whose strengthening mechanisms were contributed from transformation induced plasticity(TRIP)effect,dislocation strengthening,twinning induced plasticity(TWIP)effect,and precipitation strengthening.
