The [001]c-polarized(1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3(PMN-PT) single crystals are widely used in ultrasonic detection transducers and underwater acoustic sensors. However, the relatively small coercive field( 2 kV/cm) of...The [001]c-polarized(1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3(PMN-PT) single crystals are widely used in ultrasonic detection transducers and underwater acoustic sensors. However, the relatively small coercive field( 2 kV/cm) of such crystals restricts their application at high frequencies because the driving field will exceed the coercive field. The depolarization field can be considerably larger in an antiparallel direction than in a parallel direction with respect to polarization when the bipolar driving cycle starts. Thus, if the direction of the sine wave signal in the first half cycle is opposite to the polarization direction, then the depolarized domains can be repolarized in the second half of the sine cycle. However, if the direction of the sine wave signal in the first half of the cycle is along the polarization direction, then the change is negligible,and the domains switched in the second half of the sine cycle cannot be recovered. The design of electric driving method needs to allow the use of a large applied field to emit strong enough signals and produce good images. This phenomenon combined with the coercive field increases with the driving frequency, thereby making the PMN-PT single crystals usable for high-frequency applications. As such, the applied field can be considerably larger than the conventionally defined coercive field.展开更多
Using the generalized Ginzburg-Landau-Devonshire theory, the characteristics of phase transformation of a ferroelectric thin film with surface layers are investigated. We study the effect of the surface layer on the p...Using the generalized Ginzburg-Landau-Devonshire theory, the characteristics of phase transformation of a ferroelectric thin film with surface layers are investigated. We study the effect of the surface layer on the properties (coercive field, critical thickness) of a ferroelectric thin film. Our theoretical results show that the surface layer is likely to answer for the emergence of phase transformation.展开更多
RNA modifications have become hot topics recently.By influencing RNA processes,including generation,transportation,function,and metabolization,they act as critical regulators of cell biology.The immune cell abnormalit...RNA modifications have become hot topics recently.By influencing RNA processes,including generation,transportation,function,and metabolization,they act as critical regulators of cell biology.The immune cell abnormality in human diseases is also a research focus and progressing rapidly these years.Studies have demonstrated that RNA modifications participate in the multiple biological processes of immune cells,including development,differentiation,activation,migration,and polarization,thereby modulating the immune responses and are involved in some immune related diseases.In this review,we present existing knowledge of the biological functions and underlying mechanisms of RNA modifications,including N6-methyladenosine(m^(6)A),5-methylcytosine(m^(5)C),N1-methyladenosine(m1 A),N7-methylguanosine(m^(7)G),N4-acetylcytosine(ac^(4)C),pseudouridine(Ψ),uridylation,and adenosine-to-inosine(A-to-I)RNA editing,and summarize their critical roles in immune cell biology.Via regulating the biological processes of immune cells,RNA modifications can participate in the pathogenesis of immune related diseases,such as cancers,infection,inflammatory and autoimmune diseases.We further highlight the challenges and future directions based on the existing knowledge.All in all,this review will provide helpful knowledge as well as novel ideas for the researchers in this area.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11674270)the Fundamental Research Funds for Xiamen University,China(Grant No.20720180113)+2 种基金the Education and Scientific Research Project for Young and Middle-aged Teachers of Fujian Province,China(Grant No.JAT170036)the Opening Fund of Acoustics Science and Technology Laboratory,China(Grant No.SSKF2018006)sponsored by the Education Department of Fujian Province,China for his study at the Pennsylvania State University(Grant No.2016071145)
文摘The [001]c-polarized(1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3(PMN-PT) single crystals are widely used in ultrasonic detection transducers and underwater acoustic sensors. However, the relatively small coercive field( 2 kV/cm) of such crystals restricts their application at high frequencies because the driving field will exceed the coercive field. The depolarization field can be considerably larger in an antiparallel direction than in a parallel direction with respect to polarization when the bipolar driving cycle starts. Thus, if the direction of the sine wave signal in the first half cycle is opposite to the polarization direction, then the depolarized domains can be repolarized in the second half of the sine cycle. However, if the direction of the sine wave signal in the first half of the cycle is along the polarization direction, then the change is negligible,and the domains switched in the second half of the sine cycle cannot be recovered. The design of electric driving method needs to allow the use of a large applied field to emit strong enough signals and produce good images. This phenomenon combined with the coercive field increases with the driving frequency, thereby making the PMN-PT single crystals usable for high-frequency applications. As such, the applied field can be considerably larger than the conventionally defined coercive field.
文摘Using the generalized Ginzburg-Landau-Devonshire theory, the characteristics of phase transformation of a ferroelectric thin film with surface layers are investigated. We study the effect of the surface layer on the properties (coercive field, critical thickness) of a ferroelectric thin film. Our theoretical results show that the surface layer is likely to answer for the emergence of phase transformation.
基金supported by grants from National Natural Science Foundation of China(No.81872522,82073429)Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00046)+1 种基金Clinical Research Plan of SHDC(No.SHDC2020CR1014B,SHDC12018X06)Program of Shanghai Academic Research Leader(No.20XD1403300).
文摘RNA modifications have become hot topics recently.By influencing RNA processes,including generation,transportation,function,and metabolization,they act as critical regulators of cell biology.The immune cell abnormality in human diseases is also a research focus and progressing rapidly these years.Studies have demonstrated that RNA modifications participate in the multiple biological processes of immune cells,including development,differentiation,activation,migration,and polarization,thereby modulating the immune responses and are involved in some immune related diseases.In this review,we present existing knowledge of the biological functions and underlying mechanisms of RNA modifications,including N6-methyladenosine(m^(6)A),5-methylcytosine(m^(5)C),N1-methyladenosine(m1 A),N7-methylguanosine(m^(7)G),N4-acetylcytosine(ac^(4)C),pseudouridine(Ψ),uridylation,and adenosine-to-inosine(A-to-I)RNA editing,and summarize their critical roles in immune cell biology.Via regulating the biological processes of immune cells,RNA modifications can participate in the pathogenesis of immune related diseases,such as cancers,infection,inflammatory and autoimmune diseases.We further highlight the challenges and future directions based on the existing knowledge.All in all,this review will provide helpful knowledge as well as novel ideas for the researchers in this area.
