Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a nov...Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a novel spinel-structured LaFe_(2)O_(4)via a self-doping strategy.The LaFe_(2)O_(4)demonstrates excellent ORR activity in a protonic ceramic fuel cell(PCFC)at temperature range of 350-500℃.The high ORR activity of LaFe_(2)O_(4)is mainly attributed to the facile release of oxide and proton ions,and improved synergistic incorporation abilities associated with interplay of multivalent Fe^(3+)/Fe^(2+)and La^(3+)ions.Using LaFe_(2)O_(4)as cathode over proton conducting BaZr_(0.4)Ce_(0.4)Y_(0.2)O_(3)(BZCY)electrolyte,the fuel cell has delivered a high-power density of 806 mW/cm^(2)operating at 500℃.Different spectroscopic and calculations methods such as UV-visible,Raman,X-ray photoelectron spectroscopy and density functional theory(DFT)calculations were performed to screen the potential application of LaFe_(2)O_(4)as cathode.This study would help in developing functional cobalt-free ORR electrocatalysts for low temperature-PCFCs(LT-PCFCs)and solid oxide fuel cells(SOFCs)applications.展开更多
Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studie...Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studies on the QS system mechanisms have been carried out in experiments, mathematical modeling to explore the QS system has become a powerful approach as well. In this paper, we review the research progress of network modeling in bacterial QS to capture the system's underlying mechanisms. There are four types of QS system models for bacteria: the Gram-negative QS system model, the Gram-positive QS system model, the model for both Gram-negative and Gram-positive QS system, and the synthetic QS system model. These QS system models are mostly described by the ordinary differential equations (ODE) or partial differential equations (PDE) to study the changes of signaling molecule dynamics in time and space and the cell population density variations. Besides the deterministic simulations, the stochastic modeling approaches have also been introduced to discuss the noise effects on kinetics in QS systems. Taken together, these current modeling efforts advance our understanding of the QS system by providing systematic and quantitative dynamics description, which can hardly be obtained in experiments.展开更多
Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit signifi...Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit significantly different amplitude and frequency dependences from the ones observed in the commensurate structures.The step widths still oscillate with the amplitude,but the form is no longer Bessel-like,i.e.,the anomaly appears in our simulations.The same type of anomalies is also exhibited by the critical depinning force.The oscillatory behavior and the anomalies are also revealed in the ((F),Fac) phase diagram where three phases are observed.These oscillations are directly correlated with the existence and the stability of interference phenomena in real systems.展开更多
The Kerr nonlinearity in two-dimensional(2D)nanomaterials is emerging as an appealing and intriguing research area due to their prominent light processing,modulation,and manipulation abilities.In this contribution,2D ...The Kerr nonlinearity in two-dimensional(2D)nanomaterials is emerging as an appealing and intriguing research area due to their prominent light processing,modulation,and manipulation abilities.In this contribution,2D black arsenic-phosphorus(B-AsP)nanosheets(NSs)were applied in nonlinear photonic devices based on spatial self-phase modula-tion(SSPM)method.By applying the Kerr nonlinearity in 2D B-AsP,an all-optical phase-modulated system is proposed to realize the functions of“on”and“off”in all-optical switching.By using the same all-optical phase-modulated system,another optical logic gate is proposed,and the logical“or”function is obtained based on the 2D B-AsP NSs dispersions.Moreover,by using the SSPM method,a 2D B-AsP/SnS_(2) hybrid structure is fabricated,and the result illustrates that the hybrid structure possesses the ability of the unidirectional nonlinear excitation,which helps in obtaining the function of spatial asymmetric light propagation.This function is considered an important prerequisite for the realization of diode functionalization,which is believed to be a factor in important basis for the design of isolators as well.The initial investig-ations indicate that 2D B-AsP is applicable for designing optical logical devices,which can be considered as an import-ant development in all-optical information processing.展开更多
Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configurati...Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configuration and the regulation method are pivotal and elusive.Here,we report a combined strategy of matrix-activization and controlled-induction to modify the CoN_(4)site by axial coordination of Co-S(Co1N_(4)-S_(1)),which was validated by the aberration-corrected electron microscopy and X-ray absorption fine structure analysis.The optimal Co1N_(4)-S_(1)exhibits an excellent alkaline ORR activity,according to the half-wave potential(0.897 V vs.reversible hydrogen electrode(RHE)),Tafel slope(24.67 mV/dec),and kinetic current density.Moreover,the Co1N_(4)-S_(1)based Zn-air battery displays a high power density of 187.55 mW/cm^(2)and an outstanding charge-discharge cycling stability for 160 h,demonstrating the promising application potential.Theoretical calculations indicate that the better regulation of CoN_(4)on electronic structure and thus the highly efficient ORR performance can be achieved by axial Co-S.展开更多
We demonstrate an all-optical strategy for realizing spherical three-dimensional(3D)super-resolution(∼λ3/22)spot arrays of pure longitudinal magnetization by exploiting a 4πoptical microscopic setup with two high n...We demonstrate an all-optical strategy for realizing spherical three-dimensional(3D)super-resolution(∼λ3/22)spot arrays of pure longitudinal magnetization by exploiting a 4πoptical microscopic setup with two high numerical aperture(NA)objective lenses,which focus and interfere two modulated vectorial beams.Multiple phase filters(MPFs)are designed via an analytical approach derived from the vectorial Debye diffraction theory to modulate the two circularly polarized beams.The system is tailored to constructively interfere the longitudinal magnetization components,while simultaneously destructively interfering the azimuthal ones.As a result,the magnetization field is not only purely longitudinal but also super-resolved in all three dimensions.Furthermore,the MPFs can be designed analytically to control the number and locations of the super-resolved magnetization spots to produce both uniform and nonuniform arrays in a 3D volume.Thus,an all-optical control of all the properties of light-induced magnetization spot arrays has been demonstrated for the first time.These results open up broad applications in magnetic-optical devices such as confocal and multifocal magnetic resonance microscopy,3D ultrahigh-density magneto-optic memory,and light-induced magneto-lithography.展开更多
The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study,...The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.展开更多
基金Project supported by the National Natural Science Foundation of China(51772080,11604088,51706093)Jiangsu Provence Talent Program(JSSCRC2021491)。
文摘Highly active and stable electrocatalysts are mandatory for developing high-performance and longlasting fuel cells.The current study demonstrates a high oxygen reduction reaction(ORR)electrocatalytic activity of a novel spinel-structured LaFe_(2)O_(4)via a self-doping strategy.The LaFe_(2)O_(4)demonstrates excellent ORR activity in a protonic ceramic fuel cell(PCFC)at temperature range of 350-500℃.The high ORR activity of LaFe_(2)O_(4)is mainly attributed to the facile release of oxide and proton ions,and improved synergistic incorporation abilities associated with interplay of multivalent Fe^(3+)/Fe^(2+)and La^(3+)ions.Using LaFe_(2)O_(4)as cathode over proton conducting BaZr_(0.4)Ce_(0.4)Y_(0.2)O_(3)(BZCY)electrolyte,the fuel cell has delivered a high-power density of 806 mW/cm^(2)operating at 500℃.Different spectroscopic and calculations methods such as UV-visible,Raman,X-ray photoelectron spectroscopy and density functional theory(DFT)calculations were performed to screen the potential application of LaFe_(2)O_(4)as cathode.This study would help in developing functional cobalt-free ORR electrocatalysts for low temperature-PCFCs(LT-PCFCs)and solid oxide fuel cells(SOFCs)applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704318,11675134,and 11874310)the China Postdoctoral Science Foundation(Grant No.2016M602071).
文摘Quorum sensing (QS) refers to the cell communication through signaling molecules that regulate many important biological functions of bacteria by monitoring their population density. Although a wide spectrum of studies on the QS system mechanisms have been carried out in experiments, mathematical modeling to explore the QS system has become a powerful approach as well. In this paper, we review the research progress of network modeling in bacterial QS to capture the system's underlying mechanisms. There are four types of QS system models for bacteria: the Gram-negative QS system model, the Gram-positive QS system model, the model for both Gram-negative and Gram-positive QS system, and the synthetic QS system model. These QS system models are mostly described by the ordinary differential equations (ODE) or partial differential equations (PDE) to study the changes of signaling molecule dynamics in time and space and the cell population density variations. Besides the deterministic simulations, the stochastic modeling approaches have also been introduced to discuss the noise effects on kinetics in QS systems. Taken together, these current modeling efforts advance our understanding of the QS system by providing systematic and quantitative dynamics description, which can hardly be obtained in experiments.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91026005 and 11105054the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province under Grant No LYM10065the Domestic Visiting Scholars Program of the Doctoral Candidates of Northwest Normal University of China.
文摘Dynamical mode locking phenomena in incommensurate structures of the dc- and ac-driven overdamped FrenkelKontorova model are studied by molecular-dynamics simulations.It is found that the Shapiro steps exhibit significantly different amplitude and frequency dependences from the ones observed in the commensurate structures.The step widths still oscillate with the amplitude,but the form is no longer Bessel-like,i.e.,the anomaly appears in our simulations.The same type of anomalies is also exhibited by the critical depinning force.The oscillatory behavior and the anomalies are also revealed in the ((F),Fac) phase diagram where three phases are observed.These oscillations are directly correlated with the existence and the stability of interference phenomena in real systems.
基金supports from the National Natural Science Foundation of China(NSFC)(61435010 and 21773168)the Science and Technique Planning Project of Guangdong Province(Grant No.2016B050501005)+1 种基金the Science and Technology Innovation Commission of Shenzhen(JCYJ20170302153323978 and JCYJ201704101719588539)the Science and Technology Development Fund(No.007/2017/A1 and132/2017/A3),Ma-cao SAR,China.
文摘The Kerr nonlinearity in two-dimensional(2D)nanomaterials is emerging as an appealing and intriguing research area due to their prominent light processing,modulation,and manipulation abilities.In this contribution,2D black arsenic-phosphorus(B-AsP)nanosheets(NSs)were applied in nonlinear photonic devices based on spatial self-phase modula-tion(SSPM)method.By applying the Kerr nonlinearity in 2D B-AsP,an all-optical phase-modulated system is proposed to realize the functions of“on”and“off”in all-optical switching.By using the same all-optical phase-modulated system,another optical logic gate is proposed,and the logical“or”function is obtained based on the 2D B-AsP NSs dispersions.Moreover,by using the SSPM method,a 2D B-AsP/SnS_(2) hybrid structure is fabricated,and the result illustrates that the hybrid structure possesses the ability of the unidirectional nonlinear excitation,which helps in obtaining the function of spatial asymmetric light propagation.This function is considered an important prerequisite for the realization of diode functionalization,which is believed to be a factor in important basis for the design of isolators as well.The initial investig-ations indicate that 2D B-AsP is applicable for designing optical logical devices,which can be considered as an import-ant development in all-optical information processing.
基金supported by the National Key Research and Development Program of China(No.2021YFF0500503)theNational Natural Science Foundation of China(Nos.22275109,21971135,21925202,21872076,and 21471102)+2 种基金the Beijing Municipal Natural Science Foundation(No.2214060)the China Postdoctoral Science Foundation(No.2020M680508)Shenzhen Basic Research Foundation(No.JCYJ20190808110613626).
文摘Regulating the coordination environment of transition-metal based materials in the axial direction with heteroatoms has shown great potential in boosting the oxygen reduction reaction(ORR).The coordination configuration and the regulation method are pivotal and elusive.Here,we report a combined strategy of matrix-activization and controlled-induction to modify the CoN_(4)site by axial coordination of Co-S(Co1N_(4)-S_(1)),which was validated by the aberration-corrected electron microscopy and X-ray absorption fine structure analysis.The optimal Co1N_(4)-S_(1)exhibits an excellent alkaline ORR activity,according to the half-wave potential(0.897 V vs.reversible hydrogen electrode(RHE)),Tafel slope(24.67 mV/dec),and kinetic current density.Moreover,the Co1N_(4)-S_(1)based Zn-air battery displays a high power density of 187.55 mW/cm^(2)and an outstanding charge-discharge cycling stability for 160 h,demonstrating the promising application potential.Theoretical calculations indicate that the better regulation of CoN_(4)on electronic structure and thus the highly efficient ORR performance can be achieved by axial Co-S.
基金supported by the National Natural Science Foundation of China(Nos.61575139,11474077,11374079,11604236,51602213,61605136 and 11404283)Fundamental&advanced research projects of Chongqing,China(cstc2013jcyjC00001)+3 种基金the Youth Foundation of the Taiyuan University of Technology(No.2015QN066)the Youth Science Foundation of the Taiyuan Institute of Technology(No.2015LQ14)the Science and Technology Program of Guangdong(2016A040403124)the Shanxi Scholarship Council of China(No.2013-037).
文摘We demonstrate an all-optical strategy for realizing spherical three-dimensional(3D)super-resolution(∼λ3/22)spot arrays of pure longitudinal magnetization by exploiting a 4πoptical microscopic setup with two high numerical aperture(NA)objective lenses,which focus and interfere two modulated vectorial beams.Multiple phase filters(MPFs)are designed via an analytical approach derived from the vectorial Debye diffraction theory to modulate the two circularly polarized beams.The system is tailored to constructively interfere the longitudinal magnetization components,while simultaneously destructively interfering the azimuthal ones.As a result,the magnetization field is not only purely longitudinal but also super-resolved in all three dimensions.Furthermore,the MPFs can be designed analytically to control the number and locations of the super-resolved magnetization spots to produce both uniform and nonuniform arrays in a 3D volume.Thus,an all-optical control of all the properties of light-induced magnetization spot arrays has been demonstrated for the first time.These results open up broad applications in magnetic-optical devices such as confocal and multifocal magnetic resonance microscopy,3D ultrahigh-density magneto-optic memory,and light-induced magneto-lithography.
文摘The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.
