BACKGROUND At the end of 2019,a new epidemic of viral pneumonia emerged in China and was determined to be caused by a novel coronavirus,which was named coronavirus disease 2019(COVID-19)by the World Health Organizatio...BACKGROUND At the end of 2019,a new epidemic of viral pneumonia emerged in China and was determined to be caused by a novel coronavirus,which was named coronavirus disease 2019(COVID-19)by the World Health Organization.The epidemic quickly spread,causing a worldwide pandemic.Scientists and clinicians across the globe have shifted their research efforts towards understanding the virus itself and its epidemiology.CASE SUMMARY In mid-January 2020,a Chinese family made a visit to a local city,and within the next 2 wk one after another fell ill with COVID-19.At the beginning of their first illness onset,the family had eaten in a restaurant,which led to the subsequent illness onset in another two families.All cases were diagnosed as COVID-19 by real-time fluorescent reverse transcription-polymerase chain reaction.Epidemiological investigation showed that the transmission chain was complete.CONCLUSION This chain of social exposure highlights the danger of group aggregative behavior for spread of COVID-19.展开更多
The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide...The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.展开更多
基金The Guangzhou Science and Technology Program Key Projects,No.201704030132.
文摘BACKGROUND At the end of 2019,a new epidemic of viral pneumonia emerged in China and was determined to be caused by a novel coronavirus,which was named coronavirus disease 2019(COVID-19)by the World Health Organization.The epidemic quickly spread,causing a worldwide pandemic.Scientists and clinicians across the globe have shifted their research efforts towards understanding the virus itself and its epidemiology.CASE SUMMARY In mid-January 2020,a Chinese family made a visit to a local city,and within the next 2 wk one after another fell ill with COVID-19.At the beginning of their first illness onset,the family had eaten in a restaurant,which led to the subsequent illness onset in another two families.All cases were diagnosed as COVID-19 by real-time fluorescent reverse transcription-polymerase chain reaction.Epidemiological investigation showed that the transmission chain was complete.CONCLUSION This chain of social exposure highlights the danger of group aggregative behavior for spread of COVID-19.
基金supported by the National Natural Science Foundation of China(Nos.21375145,21221064)
文摘The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.
