Moiré superlattices are formed when overlaying two materials with a slight mismatch in twist angle or lattice constant. They provide a novel platform for the study of strong electronic correlations and non-trivia...Moiré superlattices are formed when overlaying two materials with a slight mismatch in twist angle or lattice constant. They provide a novel platform for the study of strong electronic correlations and non-trivial band topology, where emergent phenomena such as correlated insulating states, unconventional superconductivity, and quantum anomalous Hall effect are discovered. In this review, we focus on the semiconducting transition metal dichalcogenides(TMDs) based moiré systems that host intriguing flat-band physics. We first review the exfoliation methods of two-dimensional materials and the fabrication technique of their moiré structures. Secondly, we overview the progress of the optically excited moiré excitons, which render the main discovery in the early experiments on TMD moiré systems. We then introduce the formation mechanism of flat bands and their potential in the quantum simulation of the Hubbard model with tunable doping, degeneracies, and correlation strength. Finally, we briefly discuss the challenges and future perspectives of this field.展开更多
Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for t...Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for type-II Weyl semimetal.We demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological material.Our analysis reveals the existence of Dirac points,in addition to Weyl points,giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single material.These findings not only confirm NbIrTe_(4) as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.展开更多
Searching for the dispersionless flat band(FB)in quantum materials,especially in topological systems,becomes an interesting topic.The kagome lattice is an ideal platform for such exploration because the FB can be natu...Searching for the dispersionless flat band(FB)in quantum materials,especially in topological systems,becomes an interesting topic.The kagome lattice is an ideal platform for such exploration because the FB can be naturally induced by the underlying destructive interference.Nevertheless,the magnetic kagome system that hosts the FB close to the Fermi level(EF)is exceptionally rare.Here,we study the electronic structure of a kagome magnet LuMn_(6)Sn_(6) by combining angleresolved photoemission spectroscopy and density functional theory calculations.The observed Fermi-surface topology and overall band dispersions are similar to previous studies of the XMn_(6)Sn_(6)(X=Dy,Tb,Gd,Y)family of compounds.We clearly observe two kagome-derived FBs extending through the entire Brillouin zone,and one of them is located just below EF.The photon-energy-dependent measurements reveal that these FBs are nearly dispersionless along the kz direction as well,supporting the quasi-two-dimensional character of such FBs.Our results complement the XMn_(6)Sn_(6) family and demonstrate the robustness of the FB features across this family.展开更多
To achieve high-efficiency organic solar cells(OSCs),the introduction of vip molecules into binary blended films(D:A system)has become the most effective method.However,the molecular design rules for vip molecules...To achieve high-efficiency organic solar cells(OSCs),the introduction of vip molecules into binary blended films(D:A system)has become the most effective method.However,the molecular design rules for vip molecules that achieve the goals by reducing voltage losses have been rarely reported.Here,guided by the molecular electrostatic potential(ESP)derived from density functional theory(DFT)calculations,we present a rationally designed vip acceptor,ANF-4,featuring very weak electrostatic interactions compared to the benchmark acceptor BTP-eC9.The larger ESP difference promotes stronger intermolecular interactions and higher miscibility.The addition of ANF-4 significantly alters the morphology of the binary system by suppressing the excessive aggregation of BTP-eC9,which leads to improved charge separation,reduced trap-assisted recombination,and efficient carrier transport.Consequently,the PM6:BTP-eC9:ANF-4-controlled device exhibits an improved radiative limit open-circuit voltage(V^(rad)_(OC))while significantly reducing non-radiative voltage loss(ΔV_(nr)),thus achieving a remarkable increase in open circuit voltage(V_(OC))of 33 mV.As a result,the device produces a new benchmark power conversion efficiency(PCE)of 20.23%(certified 20.0%)with a remarkably VOC of 0.876 V.This work provides a promising way to develop efficient vip molecules,thereby pushing the OSCs technology closer to commercial application.展开更多
At present,titanium(Ti)and its alloys are most commonly use in hemostasis clip clinical applications.However,the Ti Clip cannot be absorbed in human body and produce artifacts on computed tomography(CT),and induce cli...At present,titanium(Ti)and its alloys are most commonly use in hemostasis clip clinical applications.However,the Ti Clip cannot be absorbed in human body and produce artifacts on computed tomography(CT),and induce clinically relevant hypersensitivity in patients.In order to overcome the drawbacks of the non-degradable Ti clips,an Mg-Zn-Ca alloy operative clip was fabricated by combining hot extrusion and blanking processing.In vitro and in vivo biocompatibility of Mg-Zn-Ca alloy operative clip were evaluated by L-929 Cells and SD rat model respectively.It was found that Mg-Zn-Ca alloy exhibited non-cytotoxic to L929 cells.In vivo implantation showed that the newly designed Mg-Zn-Ca clip can successfully ligated carotid artery and no blood leakage occurred post-surgery.During the period of the clip degradation,a small amount of H2 gas formation and no tissue inflammation around the clips were observed.The degradation rate of the clip near the heart ligated the arteries faster than that of clip far away the heart due do the effect of arterial blood.Histological analysis and various blood biochemical parameters in rat serum samples collected at different times after clip implantation showed no tissue inflammation around the clips.展开更多
A unique characteristic of piezoelectric materials is their ability of electric-mechanical transduction and converting mechanical energy to electrical energy or vice versa. This remarkable property, embedded in piezoe...A unique characteristic of piezoelectric materials is their ability of electric-mechanical transduction and converting mechanical energy to electrical energy or vice versa. This remarkable property, embedded in piezoelectric materials, has been exploited to construct a wide variety of acoustic transducers for industrial applications. These include acoustic experimental measurements [1-3], mobile and internet communications [4,5], intravascular ultrasound [6], medical imaging [7], rangefinders [8], fingerprint sensors, implantable micro-devices, nondestructive detection, mea-surement of the in-situ stresses of underground rock formation, and early warning systems for dam damage and natural hazards, among others.展开更多
We report two models of the lateral displacement of acoustic-wave scattering on a fluid-solid interface that reveal an acoustic analog of the Goos-Hainchen effect in optics. This acoustic analog is called the acoustic...We report two models of the lateral displacement of acoustic-wave scattering on a fluid-solid interface that reveal an acoustic analog of the Goos-Hainchen effect in optics. This acoustic analog is called the acoustic Goos-Hainchen effect. Using newly proposed models, we made numerical calculations for the system ofa water-Perspex interface. Specifically, in the post-critical-angle region, we observed a lateral displacement （and transition time） of the reflected P-wave with respect to the incident P-wave. The first arrival of the acoustic signal from the interface is found to be a reflected P-wave rather than the sliding-refraction P-wave usually described in traditional acoustic-logging sliding P-wave theory. For both proposed models, the effective propagation speed of the reflected P-wave along the interface depends on not only the physical properties of the interracial media but also the incident angle. These observations are intriguing and warrant further investigation.展开更多
This paper discusses the influence of the anisotropy parameters on elliptical-polarization of the inhomogenously refracted P-wave induced at VTI-media interface.For this refracted P-wave,we have derived,the equations ...This paper discusses the influence of the anisotropy parameters on elliptical-polarization of the inhomogenously refracted P-wave induced at VTI-media interface.For this refracted P-wave,we have derived,the equations of the elliptical-polarization trajectory.Following the elliptical-polarization trajectory,we calculated the effects of the rock anisotropic-parameters on the polarization state,with a Poincare-sphere-like representation,for several varying media parameters.It is noted that the size,shape and initial phase angle of the elliptical-polarization trajectory are all depending the anisotropy media,as well as on the incident-angle.We expect that the findings from this paper would be applied to practical applications of seismic exploration.展开更多
The effect of side-chain engineering of conjugated molecules on the morphology and device performance in binary organic solar cells has been widely investigated. However, this relationship has hardly been studied in t...The effect of side-chain engineering of conjugated molecules on the morphology and device performance in binary organic solar cells has been widely investigated. However, this relationship has hardly been studied in the vip components of ternary organic solar cells. In this study, a family of non-fullerene vip acceptors, namely XY-3, XY-5 and XY-7, with hydrogen substituent,straight and branched alkyl chains on the bithiophene units, respectively, were designed and synthesized to understand their effects on aggregation properties and device performance. The straight and branched alkyl chains on the bithiophene units result in sightly blue-shifted absorption compared to the hydrogen substituent and the XY-7 demonstrates the most appropriate phase separation scale and the most balanced charge transport. Consequently, the OSCs based on D18:e C9:XY-7 achieve a high shortcircuit current density(JSC) and fill factor(FF), while maintaining the enhancement of the open-circuit voltage(VOC) achieving an efficiency of 19.32%, exceeding those of D18:e C9, D18:e C9:XY-3, D18:e C9:XY-5(PCE:18.28%, 19.04%, 18.75%, respectively). These results highlight that the side-chain engineering of Y series non-fullerene acceptors as the vip acceptors has great potential in optimizing morphology properties and promoting photovoltaic performance.展开更多
CD147 （cluster of differentiation 147）, also known as basigin or extracellular matrix metalloproteinase inducer （EMMPRI N）, is a cell-surface type I transmembrane glycoprotein expressed at different levels in vari...CD147 （cluster of differentiation 147）, also known as basigin or extracellular matrix metalloproteinase inducer （EMMPRI N）, is a cell-surface type I transmembrane glycoprotein expressed at different levels in various cells and tissues, especially at high levels in tumor cells （Grass and Toole, 2015）. CD147 plays important roles in multiple physiological processes, such as spermatogenesis, neural network formation, T-cell activation and in the progression of several diseases including tumor metastasis rheumatoid arthritis （RA） atherosclerosis malaria and HIV infection （Muramatsu, 2016）.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62022089,12174439,11874405,52272135,62274010,61971035)the National Key Research and Development Program of China(Grant Nos.2019YFA0308000,2021YFA1401300,2021YFA1401800,2018YFA0704200,2021YFA1400100,2020YFA0308800)+2 种基金Chongqing Outstanding Youth Fund(Grant No.2021ZX0400005)Beijing Institute of Technology Science and Technology Innovation Program Innovative Talent Science and Technology Funding SpecialProgram(No.2022CX01022)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant Nos.XDB33000000)。
文摘Moiré superlattices are formed when overlaying two materials with a slight mismatch in twist angle or lattice constant. They provide a novel platform for the study of strong electronic correlations and non-trivial band topology, where emergent phenomena such as correlated insulating states, unconventional superconductivity, and quantum anomalous Hall effect are discovered. In this review, we focus on the semiconducting transition metal dichalcogenides(TMDs) based moiré systems that host intriguing flat-band physics. We first review the exfoliation methods of two-dimensional materials and the fabrication technique of their moiré structures. Secondly, we overview the progress of the optically excited moiré excitons, which render the main discovery in the early experiments on TMD moiré systems. We then introduce the formation mechanism of flat bands and their potential in the quantum simulation of the Hubbard model with tunable doping, degeneracies, and correlation strength. Finally, we briefly discuss the challenges and future perspectives of this field.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12274455,12274459,and 12204533)the National Key R&D Program of China (Grant No.2022YFA1403800)the Beijing Natural Science Foundation (Grant No.Z200005)。
文摘Using angle-resolved photoemission spectroscopy and density functional theory calculations methods,we investigate the electronic structures and topological properties of ternary tellurides NbIrTe_(4),a candidate for type-II Weyl semimetal.We demonstrate the presence of several Fermi arcs connecting their corresponding Weyl points on both termination surfaces of the topological material.Our analysis reveals the existence of Dirac points,in addition to Weyl points,giving both theoretical and experimental evidences of the coexistence of Dirac and Weyl points in a single material.These findings not only confirm NbIrTe_(4) as a unique topological semimetal but also open avenues for exploring novel electronic devices based on its coexisting Dirac and Weyl fermions.
基金Project supported by the National Natural Science Foundation of China(Grant No.12204536)the Fundamental Research Funds for the Central Universities,and the Research Funds of People’s Public Security University of China(PPSUC)(Grant No.2023JKF02ZK09).
文摘Searching for the dispersionless flat band(FB)in quantum materials,especially in topological systems,becomes an interesting topic.The kagome lattice is an ideal platform for such exploration because the FB can be naturally induced by the underlying destructive interference.Nevertheless,the magnetic kagome system that hosts the FB close to the Fermi level(EF)is exceptionally rare.Here,we study the electronic structure of a kagome magnet LuMn_(6)Sn_(6) by combining angleresolved photoemission spectroscopy and density functional theory calculations.The observed Fermi-surface topology and overall band dispersions are similar to previous studies of the XMn_(6)Sn_(6)(X=Dy,Tb,Gd,Y)family of compounds.We clearly observe two kagome-derived FBs extending through the entire Brillouin zone,and one of them is located just below EF.The photon-energy-dependent measurements reveal that these FBs are nearly dispersionless along the kz direction as well,supporting the quasi-two-dimensional character of such FBs.Our results complement the XMn_(6)Sn_(6) family and demonstrate the robustness of the FB features across this family.
基金supported by the National Science Fund for Distinguished Young Scholars(21925506)the National Natural Science Foundation of China(U21A20331,22439004,22409202)the National Postdoctoral Program for Innovative Talents(BX20230386)。
文摘To achieve high-efficiency organic solar cells(OSCs),the introduction of vip molecules into binary blended films(D:A system)has become the most effective method.However,the molecular design rules for vip molecules that achieve the goals by reducing voltage losses have been rarely reported.Here,guided by the molecular electrostatic potential(ESP)derived from density functional theory(DFT)calculations,we present a rationally designed vip acceptor,ANF-4,featuring very weak electrostatic interactions compared to the benchmark acceptor BTP-eC9.The larger ESP difference promotes stronger intermolecular interactions and higher miscibility.The addition of ANF-4 significantly alters the morphology of the binary system by suppressing the excessive aggregation of BTP-eC9,which leads to improved charge separation,reduced trap-assisted recombination,and efficient carrier transport.Consequently,the PM6:BTP-eC9:ANF-4-controlled device exhibits an improved radiative limit open-circuit voltage(V^(rad)_(OC))while significantly reducing non-radiative voltage loss(ΔV_(nr)),thus achieving a remarkable increase in open circuit voltage(V_(OC))of 33 mV.As a result,the device produces a new benchmark power conversion efficiency(PCE)of 20.23%(certified 20.0%)with a remarkably VOC of 0.876 V.This work provides a promising way to develop efficient vip molecules,thereby pushing the OSCs technology closer to commercial application.
基金the financial support for this work from the National Natural Science Foundation of China(U1764254)supported by Tianjin Science and Technology(15ZCZDSY00920)。
文摘At present,titanium(Ti)and its alloys are most commonly use in hemostasis clip clinical applications.However,the Ti Clip cannot be absorbed in human body and produce artifacts on computed tomography(CT),and induce clinically relevant hypersensitivity in patients.In order to overcome the drawbacks of the non-degradable Ti clips,an Mg-Zn-Ca alloy operative clip was fabricated by combining hot extrusion and blanking processing.In vitro and in vivo biocompatibility of Mg-Zn-Ca alloy operative clip were evaluated by L-929 Cells and SD rat model respectively.It was found that Mg-Zn-Ca alloy exhibited non-cytotoxic to L929 cells.In vivo implantation showed that the newly designed Mg-Zn-Ca clip can successfully ligated carotid artery and no blood leakage occurred post-surgery.During the period of the clip degradation,a small amount of H2 gas formation and no tissue inflammation around the clips were observed.The degradation rate of the clip near the heart ligated the arteries faster than that of clip far away the heart due do the effect of arterial blood.Histological analysis and various blood biochemical parameters in rat serum samples collected at different times after clip implantation showed no tissue inflammation around the clips.
基金supported by Xi’an University of Posts and Telecommunicationsthe Physical Sciences Division at The University of Chicago
文摘A unique characteristic of piezoelectric materials is their ability of electric-mechanical transduction and converting mechanical energy to electrical energy or vice versa. This remarkable property, embedded in piezoelectric materials, has been exploited to construct a wide variety of acoustic transducers for industrial applications. These include acoustic experimental measurements [1-3], mobile and internet communications [4,5], intravascular ultrasound [6], medical imaging [7], rangefinders [8], fingerprint sensors, implantable micro-devices, nondestructive detection, mea-surement of the in-situ stresses of underground rock formation, and early warning systems for dam damage and natural hazards, among others.
基金the Xi’an University of Posts and Telecommunicationsthe Physical Sciences Division at the University of Chicagothe Scientific Research Program(Grant No.15JK1685)of the Shaanxi Provincial Education Department
文摘We report two models of the lateral displacement of acoustic-wave scattering on a fluid-solid interface that reveal an acoustic analog of the Goos-Hainchen effect in optics. This acoustic analog is called the acoustic Goos-Hainchen effect. Using newly proposed models, we made numerical calculations for the system ofa water-Perspex interface. Specifically, in the post-critical-angle region, we observed a lateral displacement （and transition time） of the reflected P-wave with respect to the incident P-wave. The first arrival of the acoustic signal from the interface is found to be a reflected P-wave rather than the sliding-refraction P-wave usually described in traditional acoustic-logging sliding P-wave theory. For both proposed models, the effective propagation speed of the reflected P-wave along the interface depends on not only the physical properties of the interracial media but also the incident angle. These observations are intriguing and warrant further investigation.
基金supported by Xi'an University of Posts and Telecommunications,and the Physical Sciences Division at The University of Chicago
文摘This paper discusses the influence of the anisotropy parameters on elliptical-polarization of the inhomogenously refracted P-wave induced at VTI-media interface.For this refracted P-wave,we have derived,the equations of the elliptical-polarization trajectory.Following the elliptical-polarization trajectory,we calculated the effects of the rock anisotropic-parameters on the polarization state,with a Poincare-sphere-like representation,for several varying media parameters.It is noted that the size,shape and initial phase angle of the elliptical-polarization trajectory are all depending the anisotropy media,as well as on the incident-angle.We expect that the findings from this paper would be applied to practical applications of seismic exploration.
基金supported by the National Natural Science Foundation of China (U21A20331)the National Science Fund for Distinguished Young Scholars (21925506)the Zhejiang Provincial Natural Science Foundation (LQ22E030013)。
文摘The effect of side-chain engineering of conjugated molecules on the morphology and device performance in binary organic solar cells has been widely investigated. However, this relationship has hardly been studied in the vip components of ternary organic solar cells. In this study, a family of non-fullerene vip acceptors, namely XY-3, XY-5 and XY-7, with hydrogen substituent,straight and branched alkyl chains on the bithiophene units, respectively, were designed and synthesized to understand their effects on aggregation properties and device performance. The straight and branched alkyl chains on the bithiophene units result in sightly blue-shifted absorption compared to the hydrogen substituent and the XY-7 demonstrates the most appropriate phase separation scale and the most balanced charge transport. Consequently, the OSCs based on D18:e C9:XY-7 achieve a high shortcircuit current density(JSC) and fill factor(FF), while maintaining the enhancement of the open-circuit voltage(VOC) achieving an efficiency of 19.32%, exceeding those of D18:e C9, D18:e C9:XY-3, D18:e C9:XY-5(PCE:18.28%, 19.04%, 18.75%, respectively). These results highlight that the side-chain engineering of Y series non-fullerene acceptors as the vip acceptors has great potential in optimizing morphology properties and promoting photovoltaic performance.
文摘CD147 （cluster of differentiation 147）, also known as basigin or extracellular matrix metalloproteinase inducer （EMMPRI N）, is a cell-surface type I transmembrane glycoprotein expressed at different levels in various cells and tissues, especially at high levels in tumor cells （Grass and Toole, 2015）. CD147 plays important roles in multiple physiological processes, such as spermatogenesis, neural network formation, T-cell activation and in the progression of several diseases including tumor metastasis rheumatoid arthritis （RA） atherosclerosis malaria and HIV infection （Muramatsu, 2016）.
