With the constantly mutating of SARS-CoV-2 and the emergence of Variants of Concern(VOC),the implementation of vaccination is critically important.Existing SARS-CoV-2 vaccines mainly include inactivated,live attenuate...With the constantly mutating of SARS-CoV-2 and the emergence of Variants of Concern(VOC),the implementation of vaccination is critically important.Existing SARS-CoV-2 vaccines mainly include inactivated,live attenuated,viral vector,protein subunit,RNA,DNA,and virus-like particle(VLP)vaccines.Viral vector vaccines,protein subunit vaccines,and mRNA vaccines may induce additional cellular or humoral immune regulations,including Th cell responses and germinal center responses,and form relevant memory cells,greatly improving their efficiency.However,some viral vector or mRNA vaccines may be associated with complications like thrombocytopenia and myocarditis,raising concerns about the safety of these COVID-19 vaccines.Here,we systemically assess the safety and efficacy of COVID-19 vaccines,including the possible complications and different effects on pregnant women,the elderly,people with immune diseases and acquired immunodeficiency syndrome(AIDS),transplant recipients,and cancer patients.Based on the current analysis,governments and relevant agencies are recommended to continue to advance the vaccine immunization process.Simultaneously,special attention should be paid to the health status of the vaccines,timely treatment of complications,vaccine development,and ensuring the lives and health of patients.In addition,available measures such as mix-and-match vaccination,developing new vaccines like nanoparticle vaccines,and optimizing immune adjuvant to improve vaccine safety and efficacy could be considered.展开更多
H‐ZSM‐5 zeolite is a typical catalyst for methanol‐to‐olefins(MTO)conversion.Although the performance of zeolite catalysts for MTO conversion is related to the actual location of acid sites in the zeolite framewor...H‐ZSM‐5 zeolite is a typical catalyst for methanol‐to‐olefins(MTO)conversion.Although the performance of zeolite catalysts for MTO conversion is related to the actual location of acid sites in the zeolite framework,the catalytic roles of the acid sites in different pore channels of the H‐ZSM‐5 zeolite are not well understood.In this study,the MTO reaction network,involving the aromatic cycle,alkene cycle,and aromatization process,and also the diffusion behavior of methanol feedstock and olefin and aromatic products at different acid sites in the straight channel,sinusoidal channel,and intersection cavity of H‐ZSM‐5 zeolite was comparatively investigated using density functional theory calculations and molecular dynamic simulations.The results indicated that the aromatic cycle and aromatization process occurred preferentially at the acid sites in the intersection cavities with a much lower energy barrier than that at the acid sites in the straight and sinusoidal channels.In contrast,the formation of polymethylbenzenes was significantly suppressed at the acid sites in the sinusoidal and straight channels,whereas the alkene cycle can occur at all three types of acid sites with similar energy barriers and probabilities.Consequently,the catalytic performance of H‐ZSM‐5 zeolite for MTO conversion,including activity and product selectivity,can be regulated properly through the purposive alteration of the acid site distribution,viz.,the location of Al in the zeolite framework.This study helps to elucidate the relation between the catalytic performance of different acid sites in the H‐ZSM‐5 zeolite framework for MTO conversion,which should greatly benefit the design of efficient catalyst for methanol conversion.展开更多
基金the National Key Research and Development Program of China(Grant No.2022YFC0867500,BWS21J025,20SWAQK22 and 2020YFA0712102)National Natural Science Foundation of China(Grant No.82151224)+2 种基金Key Project of Beijing University of Chemical Technology(Grant No.XK1803-06,XK2020-02)Fundamental Research Funds for Central Universities(Grant No.BUCTZY2022)H&H Global Research and Technology Center(Grant No.H2021028).
文摘With the constantly mutating of SARS-CoV-2 and the emergence of Variants of Concern(VOC),the implementation of vaccination is critically important.Existing SARS-CoV-2 vaccines mainly include inactivated,live attenuated,viral vector,protein subunit,RNA,DNA,and virus-like particle(VLP)vaccines.Viral vector vaccines,protein subunit vaccines,and mRNA vaccines may induce additional cellular or humoral immune regulations,including Th cell responses and germinal center responses,and form relevant memory cells,greatly improving their efficiency.However,some viral vector or mRNA vaccines may be associated with complications like thrombocytopenia and myocarditis,raising concerns about the safety of these COVID-19 vaccines.Here,we systemically assess the safety and efficacy of COVID-19 vaccines,including the possible complications and different effects on pregnant women,the elderly,people with immune diseases and acquired immunodeficiency syndrome(AIDS),transplant recipients,and cancer patients.Based on the current analysis,governments and relevant agencies are recommended to continue to advance the vaccine immunization process.Simultaneously,special attention should be paid to the health status of the vaccines,timely treatment of complications,vaccine development,and ensuring the lives and health of patients.In addition,available measures such as mix-and-match vaccination,developing new vaccines like nanoparticle vaccines,and optimizing immune adjuvant to improve vaccine safety and efficacy could be considered.
文摘H‐ZSM‐5 zeolite is a typical catalyst for methanol‐to‐olefins(MTO)conversion.Although the performance of zeolite catalysts for MTO conversion is related to the actual location of acid sites in the zeolite framework,the catalytic roles of the acid sites in different pore channels of the H‐ZSM‐5 zeolite are not well understood.In this study,the MTO reaction network,involving the aromatic cycle,alkene cycle,and aromatization process,and also the diffusion behavior of methanol feedstock and olefin and aromatic products at different acid sites in the straight channel,sinusoidal channel,and intersection cavity of H‐ZSM‐5 zeolite was comparatively investigated using density functional theory calculations and molecular dynamic simulations.The results indicated that the aromatic cycle and aromatization process occurred preferentially at the acid sites in the intersection cavities with a much lower energy barrier than that at the acid sites in the straight and sinusoidal channels.In contrast,the formation of polymethylbenzenes was significantly suppressed at the acid sites in the sinusoidal and straight channels,whereas the alkene cycle can occur at all three types of acid sites with similar energy barriers and probabilities.Consequently,the catalytic performance of H‐ZSM‐5 zeolite for MTO conversion,including activity and product selectivity,can be regulated properly through the purposive alteration of the acid site distribution,viz.,the location of Al in the zeolite framework.This study helps to elucidate the relation between the catalytic performance of different acid sites in the H‐ZSM‐5 zeolite framework for MTO conversion,which should greatly benefit the design of efficient catalyst for methanol conversion.
