Thorium-229 possesses the lowest first nuclear excited state,with an energy of approximately 8 eV.The extremely narrow linewidth of the first nuclear excited state,with an uncertainty of 53 THz,prevents direct laser e...Thorium-229 possesses the lowest first nuclear excited state,with an energy of approximately 8 eV.The extremely narrow linewidth of the first nuclear excited state,with an uncertainty of 53 THz,prevents direct laser excitation and realization of the nuclear clock.We present a proposal using the Coulomb crystal of a linear chain formed by229Th^(3+)ions,where the nuclei of229Th3+ions in the ion trap are excited by the electronic bridge(EB)process.The 7 P1∕2state of the thorium-229 nuclear ground state is chosen for EB excitation.Using the two-level optical Bloch equation under experimental conditions,we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the first nuclear excited state,and it takes approximately 2 h to scan over an uncertainty of 0.22 eV.Taking advantage of the transition enhancement of EB and the long stability of the Coulomb crystal,the energy uncertainty of the first excited state can be limited to the order of 1 GHz.展开更多
The recent SARS-CoV-2 pandemic renewed interest in other previously discovered human coronaviruses—the non-severe acute respiratory syndrome human coronavirus (non-SARS hCoVs) and this study is a starting point for a...The recent SARS-CoV-2 pandemic renewed interest in other previously discovered human coronaviruses—the non-severe acute respiratory syndrome human coronavirus (non-SARS hCoVs) and this study is a starting point for a closer investigation of those. With the pandemic behind us we believe it to be important to also examine the current and past respiratory pathogen landscape in the patient population in our care. Therefore, 954 nasopharyngeal swabs of patients with respiratory diseases collected between October 2018 and March 2020 were tested against the pathogens Mycoplasma pneumoniae, Bordetella pertussis, Influenza A and virus, Human metapneumovirus, respiratory syncytial virus, Parainfluenza virus, human Adenovirus and Polyoma virus BK/JC. Swabs negative against these pathogens were further tested for OC43 and 229E by RT-qPCR. Human coronaviruses 229E and OC43 were proven as the causative agents in a considerable number of cases, confirmed by PCR. Overall, our results show that those two non-SARS hCoVs were responsible for 13.9% (11 of 79) of infections with flu-like symptoms of unknown etiology in the study area. In the subsequent seroprevalence study, it was shown that the seroprevalence rate of IgG antibodies against 229E and OC43 was over 50%, indicating that a big part of the population in our study area has been in contact with these non-SARS-CoVs and has built the specific humoral immune response accordingly.展开更多
基金the National Natural Science Foundation of China(No.11804372).
文摘Thorium-229 possesses the lowest first nuclear excited state,with an energy of approximately 8 eV.The extremely narrow linewidth of the first nuclear excited state,with an uncertainty of 53 THz,prevents direct laser excitation and realization of the nuclear clock.We present a proposal using the Coulomb crystal of a linear chain formed by229Th^(3+)ions,where the nuclei of229Th3+ions in the ion trap are excited by the electronic bridge(EB)process.The 7 P1∕2state of the thorium-229 nuclear ground state is chosen for EB excitation.Using the two-level optical Bloch equation under experimental conditions,we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the first nuclear excited state,and it takes approximately 2 h to scan over an uncertainty of 0.22 eV.Taking advantage of the transition enhancement of EB and the long stability of the Coulomb crystal,the energy uncertainty of the first excited state can be limited to the order of 1 GHz.
文摘The recent SARS-CoV-2 pandemic renewed interest in other previously discovered human coronaviruses—the non-severe acute respiratory syndrome human coronavirus (non-SARS hCoVs) and this study is a starting point for a closer investigation of those. With the pandemic behind us we believe it to be important to also examine the current and past respiratory pathogen landscape in the patient population in our care. Therefore, 954 nasopharyngeal swabs of patients with respiratory diseases collected between October 2018 and March 2020 were tested against the pathogens Mycoplasma pneumoniae, Bordetella pertussis, Influenza A and virus, Human metapneumovirus, respiratory syncytial virus, Parainfluenza virus, human Adenovirus and Polyoma virus BK/JC. Swabs negative against these pathogens were further tested for OC43 and 229E by RT-qPCR. Human coronaviruses 229E and OC43 were proven as the causative agents in a considerable number of cases, confirmed by PCR. Overall, our results show that those two non-SARS hCoVs were responsible for 13.9% (11 of 79) of infections with flu-like symptoms of unknown etiology in the study area. In the subsequent seroprevalence study, it was shown that the seroprevalence rate of IgG antibodies against 229E and OC43 was over 50%, indicating that a big part of the population in our study area has been in contact with these non-SARS-CoVs and has built the specific humoral immune response accordingly.
