How follicular T-helper （Tfh） cells develop is incom- pletely understood. We find that, upon antigen exposure in vivo, both naive and antigen-experienced T cells sequentially upregulate CXCR5 and Bc16 within the fir...How follicular T-helper （Tfh） cells develop is incom- pletely understood. We find that, upon antigen exposure in vivo, both naive and antigen-experienced T cells sequentially upregulate CXCR5 and Bc16 within the first 24 h, relocate to the T-B border, and give rise to phenotypic Bcl6＋CXCR5＋ Tfh cells before the first cell division. CXCR5 upregulation is more dependent on ICOS costimulation than that of Bcl6, and early Bcl6 induction requires T-cell expression of CXCR5 and, presumably, relocation toward the follicle. This early and rapid upregulation of CXCR5 and Bcl6 depends on IL-6 produced by radiation-resistant cells. These results suggest that a Bcl6hiCXCR5hi phenotype does not automatically define a Tfh lineage but might reflect a state of antigen exposure and non-commitment to terminal effector fates and that niches in the T-B border and/or the follicle are important for optimal Bcl6 induction and maintenance.展开更多
As promising candidates for plasma-facing materials,tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux.Radiati...As promising candidates for plasma-facing materials,tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux.Radiation-produced defects,e.g.self-interstitial atoms(SIAs)and vacancies(Vs),can induce the hardening and embrittlement of tungsten,meanwhile enhancing the retention of hydrogen isotopes and helium in tungsten.Reducing the grain size of materials to introduce a high density of defect sinks,e.g.,grain boundaries(GBs)prevalent in nano-/ultrafine-crystalline materials,was demonstrated to be an effective approach for mitigating irradiation damage in tungsten.In this paper,we reviewed the theoretical advances in exploring radiation-resistance of nano-structured tungsten at across scales.It was concentrated on the results of molecular dynamics,molecular statics,and the object kinetic Monte Carlo simulations on the fundamental interaction of the radiation-created Vs and SIAs with the GB.These mechanisms include GB-promoted V/SIA migration and SIA-V recombination,interstitial-emission induced annihilation,coupling of the V migration close to the GB with the SIA motion within the GB,and interstitial reflection by the locally dense GB structure.We proposed the remaining scientific issues on the defect-GB interactions at across scales and their relation to experimental observations.We prospected the possible trends for simulating the radiation damage accumulation and healing processes in nano-structured tungsten in terms of the development of the across-scale computational techniques and efficiency of the GB-enhanced tolerance of tungsten to irradiation under complex in-service conditions.展开更多
文摘How follicular T-helper （Tfh） cells develop is incom- pletely understood. We find that, upon antigen exposure in vivo, both naive and antigen-experienced T cells sequentially upregulate CXCR5 and Bc16 within the first 24 h, relocate to the T-B border, and give rise to phenotypic Bcl6＋CXCR5＋ Tfh cells before the first cell division. CXCR5 upregulation is more dependent on ICOS costimulation than that of Bcl6, and early Bcl6 induction requires T-cell expression of CXCR5 and, presumably, relocation toward the follicle. This early and rapid upregulation of CXCR5 and Bcl6 depends on IL-6 produced by radiation-resistant cells. These results suggest that a Bcl6hiCXCR5hi phenotype does not automatically define a Tfh lineage but might reflect a state of antigen exposure and non-commitment to terminal effector fates and that niches in the T-B border and/or the follicle are important for optimal Bcl6 induction and maintenance.
基金This work was financially supported by the National Key Research and Development Program of China(Grant Nos.2017YFE0302400,2017YFA0402800,and 2018YFE0308102)the National Natural Science Foundation of China(Grant Nos.11735015,51871207,51671185,U1832206,51771181,U1967211 and 51971212)the Center for Computation Science,Hefei Institutes of Physical Sciences.
文摘As promising candidates for plasma-facing materials,tungsten-based materials suffer the irradiation of high-energy neutrons in addition to the hydrogen isotopes and helium irradiation and the high-thermal flux.Radiation-produced defects,e.g.self-interstitial atoms(SIAs)and vacancies(Vs),can induce the hardening and embrittlement of tungsten,meanwhile enhancing the retention of hydrogen isotopes and helium in tungsten.Reducing the grain size of materials to introduce a high density of defect sinks,e.g.,grain boundaries(GBs)prevalent in nano-/ultrafine-crystalline materials,was demonstrated to be an effective approach for mitigating irradiation damage in tungsten.In this paper,we reviewed the theoretical advances in exploring radiation-resistance of nano-structured tungsten at across scales.It was concentrated on the results of molecular dynamics,molecular statics,and the object kinetic Monte Carlo simulations on the fundamental interaction of the radiation-created Vs and SIAs with the GB.These mechanisms include GB-promoted V/SIA migration and SIA-V recombination,interstitial-emission induced annihilation,coupling of the V migration close to the GB with the SIA motion within the GB,and interstitial reflection by the locally dense GB structure.We proposed the remaining scientific issues on the defect-GB interactions at across scales and their relation to experimental observations.We prospected the possible trends for simulating the radiation damage accumulation and healing processes in nano-structured tungsten in terms of the development of the across-scale computational techniques and efficiency of the GB-enhanced tolerance of tungsten to irradiation under complex in-service conditions.
