Perovskite ferroelectrics play an essential role in modern science and technology.The excellent properties of perovskites are closely related to their lattice dynamics.Potassium tantalate niobate(KTa_(1-x)Nb_(x)O_(3),...Perovskite ferroelectrics play an essential role in modern science and technology.The excellent properties of perovskites are closely related to their lattice dynamics.Potassium tantalate niobate(KTa_(1-x)Nb_(x)O_(3),abbreviated as KTN)is a typical solid-solution perovskite with superior properties.Although the optical and electrical performances of KTN crystals have been widely explored,information on their lattice dynamics is still scarce,which partially limits the research and performance optimization of KTN.As a solid-solution,spontaneous polarization of KTN exhibits strong tunability,and there is stress within KTN.Here,we performed first-principles calculations in conjunction with experiments to investigate the polarization-and stress-related lattice dynamics in KTN.We assigned the vibration modes of observed Raman peaks,and established the relationship between spontaneous polarization and vibration.Especially,the lattice dynamics evolution of KTN crystal under stress was investigated.And the results provide insights into the regulatory effect of stress on dielectric property from the perspective of lattice dynamics.Finally,the variation trends of phonons under stress,as well as the mechanism of stress effect in tetragonal perovskites were explained.The conclusions drawn for KTN crystal were generalized to tetragonal ferroelectric systems.Our results help to reflect spontaneous polarization and structural characteristics distribution through non-destructive Raman spectra,and give a reference for improving performance by regulating lattice dynamics.The findings will hopefully guide research on performance origin and refined design of perovskite functional materials.展开更多
Uveitis is a common cause of blindness worldwide.Experimental autoimmune uveitis(EAU)is an animal model of noninfectious uveitis.Chrysin(5,7-dihydroxyflavone)is a member of the flavonoid family and has anti-inflammato...Uveitis is a common cause of blindness worldwide.Experimental autoimmune uveitis(EAU)is an animal model of noninfectious uveitis.Chrysin(5,7-dihydroxyflavone)is a member of the flavonoid family and has anti-inflammatory effects.We immunized C57BL/6J mice with human interphotoreceptor retinoid-binding protein peptide 1–20 to induce EAU.Chrysin was administered intragastrically at 25 mg/kg daily to the chrysin-treated mice from 3 days before immunization to 21 days after immunization.Vehicle was administered to the mice in the control group according to the same protocol.Lower clinical and histopathological scores,increased integrity of the blood–retinal barrier(BRB)and higher expression of tight junction proteins were observed in the chrysin-treated mice.Chrysin significantly decreased the proportions of Th1,Th17 and CD4^(+)CD3^(+)CD62L^(+)Th0 cells,and increased the proportion of Treg cells.Both macrophage infiltration and the expression of inducible nitric oxide synthase in the retina were efficiently inhibited by chrysin treatment.In chrysin-treated mice,the expression of interferon-γ,interleukin(IL)-17A,IL-6,IL-1βand tumor necrosis factor-αwas reduced in the retina,whereas higher levels of transforming growth factor-βwere detected.Furthermore,NF-κBp65 was downregulated after chrysin treatment.In conclusion,as an anti-inflammatory molecule,chrysin exerts a preventive effect on EAU by modulating the balance among helper T-cell subsets and suppressing ocular inflammation,thereby maintaining the integrity of the BRB.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.12004085 and 12074092)the Fundamental Research Funds for the Central Universities(No.2023FRFK06004)+2 种基金the Natural Science Foundation of Heilongjiang Province of China(Nos.YQ2022A010 and ZD2022E003)the fellow-ship of China National Postdoctoral Program for Innovative Talents(No.BX20200111)the Heilongjiang Postdoctoral Funds(Nos.LBH-Z20065 and LBH-Z22121).
文摘Perovskite ferroelectrics play an essential role in modern science and technology.The excellent properties of perovskites are closely related to their lattice dynamics.Potassium tantalate niobate(KTa_(1-x)Nb_(x)O_(3),abbreviated as KTN)is a typical solid-solution perovskite with superior properties.Although the optical and electrical performances of KTN crystals have been widely explored,information on their lattice dynamics is still scarce,which partially limits the research and performance optimization of KTN.As a solid-solution,spontaneous polarization of KTN exhibits strong tunability,and there is stress within KTN.Here,we performed first-principles calculations in conjunction with experiments to investigate the polarization-and stress-related lattice dynamics in KTN.We assigned the vibration modes of observed Raman peaks,and established the relationship between spontaneous polarization and vibration.Especially,the lattice dynamics evolution of KTN crystal under stress was investigated.And the results provide insights into the regulatory effect of stress on dielectric property from the perspective of lattice dynamics.Finally,the variation trends of phonons under stress,as well as the mechanism of stress effect in tetragonal perovskites were explained.The conclusions drawn for KTN crystal were generalized to tetragonal ferroelectric systems.Our results help to reflect spontaneous polarization and structural characteristics distribution through non-destructive Raman spectra,and give a reference for improving performance by regulating lattice dynamics.The findings will hopefully guide research on performance origin and refined design of perovskite functional materials.
基金supported by the National Natural Science Foundation of China(grant numbers 81371038 and 91442124)the Natural Science Foundation of Tianjin(grant 12JCYBJC33900 and 14JCYBJC28000)TMUGH(grant number ZYYFY2015026).
文摘Uveitis is a common cause of blindness worldwide.Experimental autoimmune uveitis(EAU)is an animal model of noninfectious uveitis.Chrysin(5,7-dihydroxyflavone)is a member of the flavonoid family and has anti-inflammatory effects.We immunized C57BL/6J mice with human interphotoreceptor retinoid-binding protein peptide 1–20 to induce EAU.Chrysin was administered intragastrically at 25 mg/kg daily to the chrysin-treated mice from 3 days before immunization to 21 days after immunization.Vehicle was administered to the mice in the control group according to the same protocol.Lower clinical and histopathological scores,increased integrity of the blood–retinal barrier(BRB)and higher expression of tight junction proteins were observed in the chrysin-treated mice.Chrysin significantly decreased the proportions of Th1,Th17 and CD4^(+)CD3^(+)CD62L^(+)Th0 cells,and increased the proportion of Treg cells.Both macrophage infiltration and the expression of inducible nitric oxide synthase in the retina were efficiently inhibited by chrysin treatment.In chrysin-treated mice,the expression of interferon-γ,interleukin(IL)-17A,IL-6,IL-1βand tumor necrosis factor-αwas reduced in the retina,whereas higher levels of transforming growth factor-βwere detected.Furthermore,NF-κBp65 was downregulated after chrysin treatment.In conclusion,as an anti-inflammatory molecule,chrysin exerts a preventive effect on EAU by modulating the balance among helper T-cell subsets and suppressing ocular inflammation,thereby maintaining the integrity of the BRB.
