A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells....A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.展开更多
Dear Editor,Compared with traditional technologies affecting gene expression,changing DNA sequences of target genes is one of the most outstanding characters of CRISPR(Clustered Regularly Interspaced Short Palindromic...Dear Editor,Compared with traditional technologies affecting gene expression,changing DNA sequences of target genes is one of the most outstanding characters of CRISPR(Clustered Regularly Interspaced Short Palindromic Repeats).Single-guide RNAs(sgRNAs)guiding endonuclease Cas to target sites is a crucial step of CRISPR-Cas system for changing DNA sequences.An ideal sgRNA should only bind to the target gene.However,similar sequences of non-target sites can also be recognized leading to off-target effects[1].展开更多
基金by the National Natural Science Foundation of China(No.51976138)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A10).
文摘A three-dimensional multicomponent multiphase lattice Boltzmann model(LBM)is established to model the coupled two-phase and reactive transport phenomena in the cathode electrode of proton exchange membrane fuel cells.The gas diff usion layer(GDL)and microporous layer(MPL)are stochastically reconstructed with the inside dynamic distribution of oxygen and liquid water resolved,and the catalyst layer is simplifi ed as a superthin layer to address the electrochemical reaction,which provides a clear description of the fl ooding eff ect on mass transport and performance.Diff erent kinds of electrodes are reconstructed to determine the optimum porosity and structure design of the GDL and MPL by comparing the transport resistance and per-formance under the fl ooding condition.The simulation results show that gradient porosity GDL helps to increase the reactive area and average concentration under fl ooding.The presence of the MPL ensures the oxygen transport space and reaction area because liquid water cannot transport through micropores.Moreover,the MPL helps in the uniform distribution of oxygen for an effi cient in-plane transport capacity.Crack and perforation structures can accelerate the water transport in the assembly.The systematic perforation design yields the best performance under fl ooding by separating the transport of liquid water and oxygen.
基金This work was supported by National Natural Science Foundation of China(Grant No.32100501)Shenzhen Science and Technology Program(Grant No.RCBS20210609103819020)J.Z.was funded by the Zhejiang Science and Technology Major Program on Agricultural New Variety Breeding(2021C02070-1).
文摘Dear Editor,Compared with traditional technologies affecting gene expression,changing DNA sequences of target genes is one of the most outstanding characters of CRISPR(Clustered Regularly Interspaced Short Palindromic Repeats).Single-guide RNAs(sgRNAs)guiding endonuclease Cas to target sites is a crucial step of CRISPR-Cas system for changing DNA sequences.An ideal sgRNA should only bind to the target gene.However,similar sequences of non-target sites can also be recognized leading to off-target effects[1].
