Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy...Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).展开更多
AIM: To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23 Sr RNA gene in Helicobacter pylori(H. pylori) by nested-allele specific primer-polymerase chain reaction(nested-ASP-PCR).METHODS: T...AIM: To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23 Sr RNA gene in Helicobacter pylori(H. pylori) by nested-allele specific primer-polymerase chain reaction(nested-ASP-PCR).METHODS: The gastric tissue and saliva samples from 99 patients with positive results of the rapid urease test(RUT) were collected. The nested-ASP-PCR method was carried out with the external primers and inner allele-specific primers corresponding to the reference strain and clinical strains. Thirty gastric tissue and saliva samples were tested to determine the sensitivity of nested-ASP-PCR and ASP-PCR methods. Then, clarithromycin resistance was detected for 99 clinical samples by using different methods, including nestedASP-PCR, bacterial culture and disk diffusion. RESULTS: The nested-ASP-PCR method was successfully established to test the resistance mutation points 2142, 2143 and 2144 of the 23 SrR NA gene of H. pylori. Among 30 samples of gastric tissue and saliva, the H. pylori detection rate of nested-ASP-PCR was 90% and 83.33%, while the detection rate of ASP-PCR was just 63% and 56.67%. Especially in the saliva samples, nested-ASP-PCR showed much higher sensitivity in H. pylori detection and resistance mutation rates thanASP-PCR. In the 99 RUT-positive gastric tissue and saliva samples, the H. pylori-positive detection rate by nested-ASP-PCR was 87(87.88%) and 67(67.68%), in which there were 30 wild-type and 57 mutated strains in gastric tissue and 22 wild-type and 45 mutated strains in saliva. Genotype analysis showed that three-points mixed mutations were quite common, but different resistant strains were present in gastric mucosa and saliva. Compared to the high sensitivity shown by nested-ASP-PCR, the positive detection of bacterial culture with gastric tissue samples was 50 cases, in which only 26 drug-resistant strains were found through analyzing minimum inhibitory zone of clarithromycin. CONCLUSION: The nested-ASP-PCR assay showed higher detection sensitivity than ASP-PCR and drug sensitivity testing, which could be performed to evaluate clarithromycin resistance of H. pylori.展开更多
The ＂sergeants and soldiers rule＂ occurring in helical copolymer emulsions derived from an achiral monomer （M1） and a chiral monomer （M2） was observed. TEM, GPC, and 1H-NMR techniques in combination demonstrate ...The ＂sergeants and soldiers rule＂ occurring in helical copolymer emulsions derived from an achiral monomer （M1） and a chiral monomer （M2） was observed. TEM, GPC, and 1H-NMR techniques in combination demonstrate the formation of nanoparticles constituted by the copolymers. CD and UV-Vis spectra show the （co）polymer chains in the nanoparticles adopt helical structures of a predominant helicity, and the copolymers follow the ＂sergeants and soldiers rule＂ in forming helical structure.展开更多
Nonpharmaceutical interventions(NPIs),particularly contact tracing isolation and household quarantine,play a vital role in effectively bringing the Coronavirus Disease 2019(COVID-19)under control in China.The pairwise...Nonpharmaceutical interventions(NPIs),particularly contact tracing isolation and household quarantine,play a vital role in effectively bringing the Coronavirus Disease 2019(COVID-19)under control in China.The pairwise model,has an inherent advantage in characterizing those two NPIs than the classical well-mixed models.Therefore,in this paper,we devised a pairwise epidemic model with NPIs to analyze COVID-19 outbreak in China by using confirmed cases during February 3rde22nd,2020.By explicitly incorporating contact tracing isolation and family clusters caused by household quarantine,our model provided a good fit to the trajectory of COVID-19 infections.We calculated the reproduction number R=1.345(95%CI:1.230-1.460)for Hubei province and R=1.217(95%CI:1.207-1.227)for China(except Hubei).We also estimated the peak time of infections,the epidemic duration and the final size,which are basically consistent with real observation.We indicated by simulation that the traced high-risk contacts from incubated to susceptible decrease under NPIs,regardless of infected cases.The sensitivity analysis showed that reducing the exposure of the susceptible and increasing the clustering coefficient bolster COVID-19 control.With the enforcement of household quarantine,the reproduction number R and the epidemic prevalence declined effectively.Furthermore,we obtained the resumption time of work and production in China(except Hubei)on 10th March and in Hubei at the end of April 2020,respectively,which is broadly in line with the actual time.Our results may provide some potential lessons from China on the control of COVID-19 for other parts of the world.展开更多
Classical epidemiological models assume mass action.However,this assumption is violated when interactions are not random.With the recent COVID-19 pandemic,and resulting shelter in place social distancing directives,ma...Classical epidemiological models assume mass action.However,this assumption is violated when interactions are not random.With the recent COVID-19 pandemic,and resulting shelter in place social distancing directives,mass action models must be modified to account for limited social interactions.In this paper we apply a pairwise network model with moment closure to study the early transmission of COVID-19 in New York and San Francisco and to investigate the factors determining the severity and duration of outbreak in these two cities.In particular,we consider the role of population density,transmission rates and social distancing on the disease dynamics and outcomes.Sensitivity analysis shows that there is a strongly negative correlation between the clustering coefficient in the pairwise model and the basic reproduction number and the effective reproduction number.The shelter in place policy makes the clustering coefficient increase thereby reducing the basic reproduction number and the effective reproduction number.By switching population densities in New York and San Francisco we demonstrate how the outbreak would progress if New York had the same density as San Francisco and vice-versa.The results underscore the crucial role that population density has in the epidemic outcomes.We also show that under the assumption of no further changes in policy or transmission dynamics not lifting the shelter in place policy would have little effect on final outbreak size in New York,but would reduce the final size in San Francisco by 97%.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFA1602200)the National Natural Science Foundation of China(Nos.12341501 and 12405174)the Hefei Comprehensive National Science Center for the strong support on the STCF key technology research project.
文摘Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).
基金the Hospital of Qixia in Nanjing for providing sufficient financial support for this study
文摘AIM: To investigate clarithromycin resistance positions 2142, 2143 and 2144 of the 23 Sr RNA gene in Helicobacter pylori(H. pylori) by nested-allele specific primer-polymerase chain reaction(nested-ASP-PCR).METHODS: The gastric tissue and saliva samples from 99 patients with positive results of the rapid urease test(RUT) were collected. The nested-ASP-PCR method was carried out with the external primers and inner allele-specific primers corresponding to the reference strain and clinical strains. Thirty gastric tissue and saliva samples were tested to determine the sensitivity of nested-ASP-PCR and ASP-PCR methods. Then, clarithromycin resistance was detected for 99 clinical samples by using different methods, including nestedASP-PCR, bacterial culture and disk diffusion. RESULTS: The nested-ASP-PCR method was successfully established to test the resistance mutation points 2142, 2143 and 2144 of the 23 SrR NA gene of H. pylori. Among 30 samples of gastric tissue and saliva, the H. pylori detection rate of nested-ASP-PCR was 90% and 83.33%, while the detection rate of ASP-PCR was just 63% and 56.67%. Especially in the saliva samples, nested-ASP-PCR showed much higher sensitivity in H. pylori detection and resistance mutation rates thanASP-PCR. In the 99 RUT-positive gastric tissue and saliva samples, the H. pylori-positive detection rate by nested-ASP-PCR was 87(87.88%) and 67(67.68%), in which there were 30 wild-type and 57 mutated strains in gastric tissue and 22 wild-type and 45 mutated strains in saliva. Genotype analysis showed that three-points mixed mutations were quite common, but different resistant strains were present in gastric mucosa and saliva. Compared to the high sensitivity shown by nested-ASP-PCR, the positive detection of bacterial culture with gastric tissue samples was 50 cases, in which only 26 drug-resistant strains were found through analyzing minimum inhibitory zone of clarithromycin. CONCLUSION: The nested-ASP-PCR assay showed higher detection sensitivity than ASP-PCR and drug sensitivity testing, which could be performed to evaluate clarithromycin resistance of H. pylori.
基金supported by the National Natural Science Foundation of China (Nos. 21174010, 20974007)the Fundamental Research Funds for the Central Universities (ZZ1117)
文摘The ＂sergeants and soldiers rule＂ occurring in helical copolymer emulsions derived from an achiral monomer （M1） and a chiral monomer （M2） was observed. TEM, GPC, and 1H-NMR techniques in combination demonstrate the formation of nanoparticles constituted by the copolymers. CD and UV-Vis spectra show the （co）polymer chains in the nanoparticles adopt helical structures of a predominant helicity, and the copolymers follow the ＂sergeants and soldiers rule＂ in forming helical structure.
基金This research was funded by the National Natural Science Foundation of China(grant numbers:61873154,12022113)the Shanxi Research Project on COVID-19 epidemic control and prevention(grant number:202003D31011/GZ).
文摘Nonpharmaceutical interventions(NPIs),particularly contact tracing isolation and household quarantine,play a vital role in effectively bringing the Coronavirus Disease 2019(COVID-19)under control in China.The pairwise model,has an inherent advantage in characterizing those two NPIs than the classical well-mixed models.Therefore,in this paper,we devised a pairwise epidemic model with NPIs to analyze COVID-19 outbreak in China by using confirmed cases during February 3rde22nd,2020.By explicitly incorporating contact tracing isolation and family clusters caused by household quarantine,our model provided a good fit to the trajectory of COVID-19 infections.We calculated the reproduction number R=1.345(95%CI:1.230-1.460)for Hubei province and R=1.217(95%CI:1.207-1.227)for China(except Hubei).We also estimated the peak time of infections,the epidemic duration and the final size,which are basically consistent with real observation.We indicated by simulation that the traced high-risk contacts from incubated to susceptible decrease under NPIs,regardless of infected cases.The sensitivity analysis showed that reducing the exposure of the susceptible and increasing the clustering coefficient bolster COVID-19 control.With the enforcement of household quarantine,the reproduction number R and the epidemic prevalence declined effectively.Furthermore,we obtained the resumption time of work and production in China(except Hubei)on 10th March and in Hubei at the end of April 2020,respectively,which is broadly in line with the actual time.Our results may provide some potential lessons from China on the control of COVID-19 for other parts of the world.
基金supported by the National Natural Science Foundation of China grants 61873154 and 12101573Health Commission of Shanxi Province grants 2020XM18+4 种基金Shanxi Provincial Department of ScienceTechnology COVID-19 Emergency Special Fund grants 202003D31011/GZFundamental Research Program of Shanxi Province grants 20210302124608 and 20210302124381partially supported by a Canada Research Chair(MAL),NSERC Discovery Grants(HW and MAL),NSERC Discovery Accelerator Supplement Award(HW)an Alberta Innovates grant 202100502.
文摘Classical epidemiological models assume mass action.However,this assumption is violated when interactions are not random.With the recent COVID-19 pandemic,and resulting shelter in place social distancing directives,mass action models must be modified to account for limited social interactions.In this paper we apply a pairwise network model with moment closure to study the early transmission of COVID-19 in New York and San Francisco and to investigate the factors determining the severity and duration of outbreak in these two cities.In particular,we consider the role of population density,transmission rates and social distancing on the disease dynamics and outcomes.Sensitivity analysis shows that there is a strongly negative correlation between the clustering coefficient in the pairwise model and the basic reproduction number and the effective reproduction number.The shelter in place policy makes the clustering coefficient increase thereby reducing the basic reproduction number and the effective reproduction number.By switching population densities in New York and San Francisco we demonstrate how the outbreak would progress if New York had the same density as San Francisco and vice-versa.The results underscore the crucial role that population density has in the epidemic outcomes.We also show that under the assumption of no further changes in policy or transmission dynamics not lifting the shelter in place policy would have little effect on final outbreak size in New York,but would reduce the final size in San Francisco by 97%.
