The EMMS/bubbling model originally proposed for fluidization of monodisperse particles is extended to fluidization of binary particle mixture in this study.The dense and dilute phases are considered to comprise of two...The EMMS/bubbling model originally proposed for fluidization of monodisperse particles is extended to fluidization of binary particle mixture in this study.The dense and dilute phases are considered to comprise of two types of particles differing in size and/or density.Governing equations and the stability condition are then formulated and solved by using an optimization numerical scheme.The effects of bubble diameter are first investigated and a suitable bubble diameter correlation is chosen.Preliminary validation for steady state behavior shows the extended model can fairly capture the overall hydrodynamic behaviors in terms of volume fraction of bubbles and average bed voidage for both monodisperse and binary particle systems.This encourages us to integrate this model with CFD for more validations in the future.展开更多
Compared to transient simulation,steady-state simulation of circulating fluidized bed risers is more efficient,but is also harder to perform due to the complex scale-dependency of dense gas-solid flows.In this work,st...Compared to transient simulation,steady-state simulation of circulating fluidized bed risers is more efficient,but is also harder to perform due to the complex scale-dependency of dense gas-solid flows.In this work,steady-state computational fluid dynamics(CFD)simulation of a riser is performed using the steady energy-minimization multi-scale(EMMS)drag.It is found that the steady state corresponds to an extremely large scale of length and time,thus the grid size required in steady-state simulation is larger than that in transient one.The time-averaged two-fluid model(TFM)coupled with the steady-state EMMS/1M drag model enables a good prediction of the S-shaped,axial solids distribution and the choking transition,whereas the two-phase turbulence and solids stress models are important in predicting the radially core-annular distribution of solids.So far as we know,this is the first time that one can predict the choking transition in a steady-state CFD simulation.Further improvement may need an EMMS modeling of the time-averaged solid stresses.展开更多
The development of distinct dendritic cell(DC)subsets,namely,plasmacytoid DCs(pDCs)and conventional DC subsets(cDC1s and cDC2s),is controlled by specific transcription factors.IRF8 is essential for the fate specificat...The development of distinct dendritic cell(DC)subsets,namely,plasmacytoid DCs(pDCs)and conventional DC subsets(cDC1s and cDC2s),is controlled by specific transcription factors.IRF8 is essential for the fate specification of cDC1s.However,how the expression of Irf8 is regulated is not fully understood.In this study,we identified TRIM33 as a critical regulator of DC differentiation and maintenance.TRIM33 deletion in Trim33fl/fl Cre-ERT2 mice significantly impaired DC differentiation from hematopoietic progenitors at different developmental stages.TRIM33 deficiency downregulated the expression of multiple genes associated with DC differentiation in these progenitors.TRIM33 promoted the transcription of Irf8 to facilitate the differentiation of cDC1s by maintaining adequate CDK9 and Ser2 phosphorylated RNA polymerase II(S2 Pol II)levels at Irf8 gene sites.Moreover,TRIM33 prevented the apoptosis of DCs and progenitors by directly suppressing the PU.1-mediated transcription of Bcl2l11,thereby maintaining DC homeostasis.Taken together,our findings identified TRIM33 as a novel and crucial regulator of DC differentiation and maintenance through the modulation of Irf8 and Bcl2l11 expression.The finding that TRIM33 functions as a critical regulator of both DC differentiation and survival provides potential benefits for devising DC-based immune interventions and therapies.展开更多
Dear Editor,Dendritic cells(DCs)are the most efficient professional antigen presenting cells that act as sentinels of the immune system and conduct vital functions in the initiation and regulation of innate and adapti...Dear Editor,Dendritic cells(DCs)are the most efficient professional antigen presenting cells that act as sentinels of the immune system and conduct vital functions in the initiation and regulation of innate and adaptive immunities(Wculek et al.,2020).In addition to being critical cellular components in pathogen clearance,DCs are promising targets for improved tumor immunotherapy,vaccine design,and intervention of autoimmune diseases(Nutt and Chopin,2020).DCs can be classified as plasmacytoid DCs(pDCs)and conventional DCs(cDCs)in both mouse and human(Anderson et al.,2018;Nutt and Chopin,2020).展开更多
基金Supported by the National Natural Science Foundation of China(21576263,21625605,91334204)the Youth Innovation Promotion Association CAS(2015033)
文摘The EMMS/bubbling model originally proposed for fluidization of monodisperse particles is extended to fluidization of binary particle mixture in this study.The dense and dilute phases are considered to comprise of two types of particles differing in size and/or density.Governing equations and the stability condition are then formulated and solved by using an optimization numerical scheme.The effects of bubble diameter are first investigated and a suitable bubble diameter correlation is chosen.Preliminary validation for steady state behavior shows the extended model can fairly capture the overall hydrodynamic behaviors in terms of volume fraction of bubbles and average bed voidage for both monodisperse and binary particle systems.This encourages us to integrate this model with CFD for more validations in the future.
基金supported by the National Natural Science Foundation of China(grant Nos.22208351,22161142006,21821005)the State Key Laboratory of Mesoscience and Engineering,Institute of Process Engineering,Chinese Academy of Sciences(grant Nos.MESO-23-D03,MESO-23-A02)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDA0390502).
文摘Compared to transient simulation,steady-state simulation of circulating fluidized bed risers is more efficient,but is also harder to perform due to the complex scale-dependency of dense gas-solid flows.In this work,steady-state computational fluid dynamics(CFD)simulation of a riser is performed using the steady energy-minimization multi-scale(EMMS)drag.It is found that the steady state corresponds to an extremely large scale of length and time,thus the grid size required in steady-state simulation is larger than that in transient one.The time-averaged two-fluid model(TFM)coupled with the steady-state EMMS/1M drag model enables a good prediction of the S-shaped,axial solids distribution and the choking transition,whereas the two-phase turbulence and solids stress models are important in predicting the radially core-annular distribution of solids.So far as we know,this is the first time that one can predict the choking transition in a steady-state CFD simulation.Further improvement may need an EMMS modeling of the time-averaged solid stresses.
基金The Ministry of Science and Technology of China National Key Research Projects provided grants 2019YFA0508502 and 2022YFC2505001 to LWThe National Natural Science Foundation of China funded grant 31991174 to LW+4 种基金The National Natural Science Foundation of China provided Basic Research Center grant 82388101 to LWThe National Natural Science Foundation of China provided grant 81801641 to JLThe National Natural Science Foundation of China provided grant 31800769 to ZHThe Ministry of Science and Technology of China National Key Research Projects provided grants 2022YFC2505002 to TWFunding from the Tsinghua-Peking Center for Life Sciences to LW is acknowledged.
文摘The development of distinct dendritic cell(DC)subsets,namely,plasmacytoid DCs(pDCs)and conventional DC subsets(cDC1s and cDC2s),is controlled by specific transcription factors.IRF8 is essential for the fate specification of cDC1s.However,how the expression of Irf8 is regulated is not fully understood.In this study,we identified TRIM33 as a critical regulator of DC differentiation and maintenance.TRIM33 deletion in Trim33fl/fl Cre-ERT2 mice significantly impaired DC differentiation from hematopoietic progenitors at different developmental stages.TRIM33 deficiency downregulated the expression of multiple genes associated with DC differentiation in these progenitors.TRIM33 promoted the transcription of Irf8 to facilitate the differentiation of cDC1s by maintaining adequate CDK9 and Ser2 phosphorylated RNA polymerase II(S2 Pol II)levels at Irf8 gene sites.Moreover,TRIM33 prevented the apoptosis of DCs and progenitors by directly suppressing the PU.1-mediated transcription of Bcl2l11,thereby maintaining DC homeostasis.Taken together,our findings identified TRIM33 as a novel and crucial regulator of DC differentiation and maintenance through the modulation of Irf8 and Bcl2l11 expression.The finding that TRIM33 functions as a critical regulator of both DC differentiation and survival provides potential benefits for devising DC-based immune interventions and therapies.
文摘Dear Editor,Dendritic cells(DCs)are the most efficient professional antigen presenting cells that act as sentinels of the immune system and conduct vital functions in the initiation and regulation of innate and adaptive immunities(Wculek et al.,2020).In addition to being critical cellular components in pathogen clearance,DCs are promising targets for improved tumor immunotherapy,vaccine design,and intervention of autoimmune diseases(Nutt and Chopin,2020).DCs can be classified as plasmacytoid DCs(pDCs)and conventional DCs(cDCs)in both mouse and human(Anderson et al.,2018;Nutt and Chopin,2020).
