In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and extern...In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats. The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes, the failure of high speed rotating machineries and accidental drops. The external impact threats may come from airborne missiles, aircraft impact, explosion blast and fragments. The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed. Methods and procedures for the impact assessment of nuclear power plants are introduced. Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures.展开更多
Trivalent lanthanide(Ln^(3+))-doped luminescent nanoparticles(NPs)have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared(NIR)lu...Trivalent lanthanide(Ln^(3+))-doped luminescent nanoparticles(NPs)have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared(NIR)luminescence upon irradiation of NIR light.However,in most cases,the power density of irradiation used for in vivo biological imaging is much higher than that of the reported maximum permissible exposure(MPE)value of NIR light,which inevitably does great damage to the living organisms under study and thus impedes the plausible clinical applications.Herein,by using a facile syringe pump-aided shell epitaxial growth method,we construct for the first time a new class of Ln^(3+)-doped KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs that can be activated by utilizing a 980-nm xenon lamp or diode laser with an ultralow excitation power density down to 0.08 mW cm^(−2),a value that is approximately 4 orders of magnitude lower than the MPE value set by the American National Standards Institute(ANSI)for safe bioimaging in vivo.By combining the comparative spectroscopic investigations with atomic-resolved spherical aberration corrected transmission electron microscopy(AC-TEM)characterization,we find that the reduced crystallographic defects are the primary cause underlying such an ultralow-power-excitable feature of the KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs.And,by the same token,the resultant KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs also exhibit an anomalous thermo-enhanced photoluminescence(PL)behavior coupled with an excellent photothermal stability that cannot occur in other Ln^(3+)-doped core-shell NPs.These findings described here unambiguously pave a new way to prepare high-quality Ln^(3+)-doped luminescent NPs with desirable ultralow-power-excitable capability and photothermal stability for future biomedical applications.展开更多
Tuberculosis （TB） continues to be a global health threat. BCG was developed as an attenuated live vaccine for tuberculosis control nearly a century ago. Despite being the most widely used vaccine in human history, B...Tuberculosis （TB） continues to be a global health threat. BCG was developed as an attenuated live vaccine for tuberculosis control nearly a century ago. Despite being the most widely used vaccine in human history, BCG is not an ideal vaccine and has two major limitations, its poor efficacy against adult pulmonary TB and its disconcerting safety in immunocompromised individuals. A safer and more effective TB vaccine is urgently needed. This review article discusses current strategies to develop the next generation of TB vaccines to replace BCG. While some progresses have been made in the past decade, significant challenges lie ahead.展开更多
文摘In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats. The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes, the failure of high speed rotating machineries and accidental drops. The external impact threats may come from airborne missiles, aircraft impact, explosion blast and fragments. The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed. Methods and procedures for the impact assessment of nuclear power plants are introduced. Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures.
基金supported by the Fund of Fujian Science&Technology Innovation Laboratory for Optoelectronic Information(2020ZZ114)the Key Research Program of Frontier Science CAS(QYZDY-SSW-SLH025)+1 种基金the National Natural Science Foundation of China(21731006 and 21871256)the Fund of Advanced Energy Science and Technology Guangdong Laboratory(DJLTN0200/DJLTN0240)。
文摘Trivalent lanthanide(Ln^(3+))-doped luminescent nanoparticles(NPs)have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared(NIR)luminescence upon irradiation of NIR light.However,in most cases,the power density of irradiation used for in vivo biological imaging is much higher than that of the reported maximum permissible exposure(MPE)value of NIR light,which inevitably does great damage to the living organisms under study and thus impedes the plausible clinical applications.Herein,by using a facile syringe pump-aided shell epitaxial growth method,we construct for the first time a new class of Ln^(3+)-doped KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs that can be activated by utilizing a 980-nm xenon lamp or diode laser with an ultralow excitation power density down to 0.08 mW cm^(−2),a value that is approximately 4 orders of magnitude lower than the MPE value set by the American National Standards Institute(ANSI)for safe bioimaging in vivo.By combining the comparative spectroscopic investigations with atomic-resolved spherical aberration corrected transmission electron microscopy(AC-TEM)characterization,we find that the reduced crystallographic defects are the primary cause underlying such an ultralow-power-excitable feature of the KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs.And,by the same token,the resultant KMgF_(3):Yb/Er@KMgF_(3)core-shell NPs also exhibit an anomalous thermo-enhanced photoluminescence(PL)behavior coupled with an excellent photothermal stability that cannot occur in other Ln^(3+)-doped core-shell NPs.These findings described here unambiguously pave a new way to prepare high-quality Ln^(3+)-doped luminescent NPs with desirable ultralow-power-excitable capability and photothermal stability for future biomedical applications.
文摘Tuberculosis （TB） continues to be a global health threat. BCG was developed as an attenuated live vaccine for tuberculosis control nearly a century ago. Despite being the most widely used vaccine in human history, BCG is not an ideal vaccine and has two major limitations, its poor efficacy against adult pulmonary TB and its disconcerting safety in immunocompromised individuals. A safer and more effective TB vaccine is urgently needed. This review article discusses current strategies to develop the next generation of TB vaccines to replace BCG. While some progresses have been made in the past decade, significant challenges lie ahead.
