Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective co...Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.展开更多
Photosystem Ⅱ(PSⅡ)is a large membrane protein(∼700 kDa)complex,harboring P680+,the strongest oxidant known in biological systems,which is responsible for driving tyrosine oxidation and ultimately O_(2) generation.W...Photosystem Ⅱ(PSⅡ)is a large membrane protein(∼700 kDa)complex,harboring P680+,the strongest oxidant known in biological systems,which is responsible for driving tyrosine oxidation and ultimately O_(2) generation.While the enhancement and expansion of PSⅡ functions through genetic engineering would be beneficial for driving challenging chemical reactions,this has proven difficult due to its enormous complexity.Here,we report a genetically encoded,27 kDa photosensitizer protein(PSP3)that recapitulates the initial photoinduced key properties of PSⅡ.Through the genetic incorporation of benzophenone-alanine(BpA)into a fluorescent protein coupled with femtosecond transient absorption measurement,we show that photoinduced electron transfer from residue Tyr203 to the PSP3 chromophore occurs very rapidly(∼1 ps),which is comparable with that of the first electron transfer step in PSII.Since PSP3 can be overexpressed in high yield in Escherichia coli and genetically engineered easily,it might facilitate challenging oxidation and reduction reactions in vitro and in vivo.展开更多
Background:Return of spontaneous circulation(ROSC)is a core outcome element of cardiopulmonary resuscitation(CPR);however,the definition or criterion of ROSC is disputed and varies in resuscitation for out-of-hospital...Background:Return of spontaneous circulation(ROSC)is a core outcome element of cardiopulmonary resuscitation(CPR);however,the definition or criterion of ROSC is disputed and varies in resuscitation for out-of-hospital cardiac arrest(OHCA).Methods:This was a retrospective study of 126 patients with OHCA who achieved ROSC between January and December 2020.The probability of survival after OHCA related to CPR and ROSC duration was analyzed using the probability density function and empirical cumulative density functions.Results:There were no significant differences between ROSC sustained until emergency department arrival and that sustained for at least 20 minutes in terms of the 24-hour survival rate(31.3%[31/99]vs.35.7%[10/30];P=0.84),30-day survival rate(23.2%[23/99]vs.25.0%[7/30];P=0.99),or survival at 30 days with cerebral performance category(CPC)1 and 2(18.2%[18/99]vs.10.7%[3/30];P=0.44).The Kolmogorov-Smirnov test values from the empirical cumulative density functions with ROSC sustained until hospital arrival and that sustained for at least 20 minutes were 0.44,0.20,and 0.24 for CPC 1 or 2,CPC 3 or 4,and CPC 5,respectively.Conclusion:Return of spontaneous circulation is a core outcome element of CPR.It should be defined as sustained for at least 20 minutes or until arrival at the emergency department and as a basic standard for evaluating resuscitation success after OHCA.展开更多
文摘Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.
基金financially supported by the National Key Research and Development Program of China under award nos.2016YFA0501502 and 2017YFA0503704the National Science Foundation of China under award nos.91940306,21837005,21890743,21961142014,21750003,91527302,and 21827803+2 种基金pilot project of CAS under award no.XDB37040203the Sanming Project of Medicine in Shenzhen(no.Y8KF351001)the Youth Innovation Promotion Association CAS.
文摘Photosystem Ⅱ(PSⅡ)is a large membrane protein(∼700 kDa)complex,harboring P680+,the strongest oxidant known in biological systems,which is responsible for driving tyrosine oxidation and ultimately O_(2) generation.While the enhancement and expansion of PSⅡ functions through genetic engineering would be beneficial for driving challenging chemical reactions,this has proven difficult due to its enormous complexity.Here,we report a genetically encoded,27 kDa photosensitizer protein(PSP3)that recapitulates the initial photoinduced key properties of PSⅡ.Through the genetic incorporation of benzophenone-alanine(BpA)into a fluorescent protein coupled with femtosecond transient absorption measurement,we show that photoinduced electron transfer from residue Tyr203 to the PSP3 chromophore occurs very rapidly(∼1 ps),which is comparable with that of the first electron transfer step in PSII.Since PSP3 can be overexpressed in high yield in Escherichia coli and genetically engineered easily,it might facilitate challenging oxidation and reduction reactions in vitro and in vivo.
基金the Beijing Municipal Science and Technology Project(Z191100004419003)the National Science and Technology Fundamental Resources Investigation Project(2018FY100600)+1 种基金the Capital Medical Development Research Fund(2022-1-3031)the Beijing Public Health High-level Scholars Development Program(2022-1-001).
文摘Background:Return of spontaneous circulation(ROSC)is a core outcome element of cardiopulmonary resuscitation(CPR);however,the definition or criterion of ROSC is disputed and varies in resuscitation for out-of-hospital cardiac arrest(OHCA).Methods:This was a retrospective study of 126 patients with OHCA who achieved ROSC between January and December 2020.The probability of survival after OHCA related to CPR and ROSC duration was analyzed using the probability density function and empirical cumulative density functions.Results:There were no significant differences between ROSC sustained until emergency department arrival and that sustained for at least 20 minutes in terms of the 24-hour survival rate(31.3%[31/99]vs.35.7%[10/30];P=0.84),30-day survival rate(23.2%[23/99]vs.25.0%[7/30];P=0.99),or survival at 30 days with cerebral performance category(CPC)1 and 2(18.2%[18/99]vs.10.7%[3/30];P=0.44).The Kolmogorov-Smirnov test values from the empirical cumulative density functions with ROSC sustained until hospital arrival and that sustained for at least 20 minutes were 0.44,0.20,and 0.24 for CPC 1 or 2,CPC 3 or 4,and CPC 5,respectively.Conclusion:Return of spontaneous circulation is a core outcome element of CPR.It should be defined as sustained for at least 20 minutes or until arrival at the emergency department and as a basic standard for evaluating resuscitation success after OHCA.