Near-zero Poisson's ratio and suppressed mechanical anisotropy in strained black phosphorene/SnSe van der Waals heterostructure:a first-principles study

Black phosphorene(BP)and its analogs have attracted intensive attention due to their unique puckered structures,anisotropic characteristics,and negative Poisson’s ratio.The van der Waals(vdW)heterostructures assembly by stacking different materials show novel physical properties,however,the parent materials do not possess.In this work,the first-principles calculations are performed to study the mechanical properties of the vdW heterostructure.Interestingly,a near-zero Poisson’s ratio ν_(zx)is found in BP/SnSe heterostructure.In addition,compared with the parent materials BP and SnSe with strong in-plane anisotropic mechanical properties,the BP/SnSe heterostructure shows strongly suppressed anisotropy.The results show that the vdW heterostructure has quite different mechanical properties compared with the parent materials,and provides new opportunities for the mechanical applications of the heterostructures.

Observation of Ferroelastic and Ferroelectric Domains in AgNbO_(3) Single Crystal

Compared to AgNbO_(3) based ceramics, the experimental investigations on the single crystalline AgNbO_(3), especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO_(3) single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy.This finding may provide a new aspect for studying AgNbO_(3). The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO_(3), which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO_(3) single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO_(3) ceramic materials.

Dynamical evolution of cross phase of edge fluctuations and transport bifurcation

The dynamical evolution of edge turbulence during a transport bifurcation is explored using a flux-driven nonlinear fluid model with a geometry relevant to the plasma edge region.The simulations show that the self-generated mean shear flows can dramatically modify the phase angle between turbulent fluctuations.The changes in phase differences and amplitudes of edge fluctuations give rise to the modifications of turbulent edge transport.The statistical properties of flux and fluctuations are also investigated before and after edge shear flow generation.

C1QTNF5 is a novel attachment factor that facilitates the entry of influenza A virus

Influenza A virus(IAV)binds sialic acid receptors on the cell surface to enter the host cells,which is the key step in initiating infection,transmission and pathogenesis.Understanding the factors that contribute to the highly efficient entry of IAV into human cells will help elucidate the mechanism of viral entry and pathogenicity,and provide new targets for intervention.In the present study,we reported a novel membrane protein,C1QTNF5,which binds to the hemagglutinin protein of IAV and promotes IAV infection in vitro and in vivo.We found that the HA1 region of IAV hemagglutinin is critical for the interaction with C1QTNF5 protein,and C1QTNF5 interacts with hemagglutinin mainly through its N-terminus(1–103 aa).In addition,we further demonstrated that overexpression of C1QTNF5 promotes IAV entry,while blocking the interaction between C1QTNF5 and IAV hemagglutinin greatly inhibits viral entry.However,C1QTNF5 does not function as a receptor to mediate IAV infection in sialic acid-deficient CHO-Lec2 cells,but promotes IAV to attach to these cells,suggesting that C1QTNF5 is an important attachment factor for IAV.This work reveals C1QTNF5 as a novel IAV attachment factor and provides a new perspective for antiviral strategies.

AIMP2 restricts EV71 replication by recruiting SMURF2 to promote the degradation of 3D polymerase

Hand,foot and mouth disease(HFMD),mainly caused by enterovirus 71(EV71),has frequently occurred in the Asia-Pacific region,posing a significant threat to the health of infants and young children.Therefore,research on the infection mechanism and pathogenicity of enteroviruses is increasingly becoming important.The 3D polymerase,as the most critical RNA-dependent RNA polymerase(RdRp)for EV71 replication,is widely targeted to inhibit EV71 infection.In this study,we identified a novel host protein,AIMP2,capable of binding to 3D polymerase and inhibiting EV71 infection.Subsequent investigations revealed that AIMP2 recruits the E3 ligase SMURF2,which mediates the polyubiquitination and degradation of 3D polymerase.Furthermore,the antiviral effect of AIMP2 extended to the CVA16 and CVB1 serotypes.Our research has uncovered the dynamic regulatory function of AIMP2 during EV71 infection,revealing a novel antiviral mechanism and providing new insights for the development of antienteroviral therapeutic strategies.

Stress compensation based on interfacial nanostructures for stable perovskite solar cells

The long-term stability issue of halide perovskite solar cells hinders their commercialization.The residual stress-strain affects device stability,which is derived from the mismatched thermophysical and mechanical properties between adjacent layers.In this work,we introduced the Rb_(2)CO_(3)layer at the interface of SnO_(2)/perovskite with the hierarchy morphology of snowflake-like microislands and dendritic nanostructures.With a suitable thermal expansion coefficient,the Rb_(2)CO_(3)layer benefits the interfacial stress relaxation and results in a compressive stress-strain in the perovskite layer.Moreover,reduced nonradiative recombination losses and optimized band alignment were achieved.An enhancement of open-circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed,which led to power conversion efficiency(PCE)of 22.7%(active area of 0.08313 cm^(2))and 20.6%(1 cm2).Moreover,these devices retained 95%of its initial PCE under the maximum power point tracking(MPPT)after 2700 h.It suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics,which improves the operational stability of perovskite cells.

Stable large-area monodomain in as-grown bulk ferroelectric single crystal Sn_(2)P_(2)S_(6)

Driven by the minimization of total energy,the multi-domain morphology is preferred in as-grown ferroelectrics to reduce the depolarization and strain energy during the paraelectric to ferroelectric phase transition.However,the complicated multi-domain is not desirable for certain high-performance ferroelectric electro-optic devices.In this work,we achieve a reproducible and stable large-area monodomain in as-grown bulk ferroelectric single crystal Sn_(2)P_(2)S_(6).The monodomain dominates the entire single crystal,which is attributed to the internal charge carriers from the photoexcited disproportionation reaction of Sn ions.The charge carriers effectively screen the depolarization field and therefore decrease the depolarization energy and facilitate the formation of monodomain.This work offers a potential approach for engineering bulk ferroelectrics with a stable monodomain,which is desirable for the high-performance ferroelectric electro-optic devices.

Inhomogeneous-strain-induced magnetic vortex cluster in one-dimensional manganite wire

Mixed-valance manganites with strong electron correlation exhibit strong potential for spintronics,where emergent magnetic behaviors,such as propagation of high-frequency spin waves and giant topological Hall Effects can be driven by their mesoscale spin textures.Here,we create magnetic vortex clusters with flux closure spin configurations in single-crystal La0.67Sr0.33MnO3 wire.A distinctive transformation from out-of-plane domains to a vortex state is directly visualized using magnetic force microscopy at 4 K in wires when the width is below 1.0μm.The phase-field modeling indicates that the inhomogeneous strain,accompanying with shape anisotropy,plays a key role for stabilizing the flux-closure spin structure.This work offers a new perspective for understanding and manipulating the non-trivial spin textures in strongly correlated systems.

Enhanced piezo-response in copper halide perovskites based PVDF composite films

ln-situ fabricated perovskite nanocrystals in polymeric matrix provide new generation composite mate- rials for plenty of cutting edge technology. In this work, we report the in-situ fabrication of copper halide perovskite （MA_2CuCI_4, MA：CH_3NH＋3） embedded poly（vinylidene fluoride） （PVDF） composite films. The optimized MA_2CuCI_4/PVDF composite films exhibit greatly enhanced piezo-response in comparasion with pure PVDF films. The enhancements were invesitgated and explained by applying piezo-response force microscopy （PFM） measurements and density functional theory （DFT） caculations. We proposed that the high piezoelectric properties of MA_2CuCI_4/PVDF composite films could be related to the large Cu off-centering displacement, the strong interactions between MA_2CuCI_4 and PVDF as well as large stress concentration around the MA_2CuCI_4 particles in the films. These piezoelectric composite films are expected to be suitable functional materials for flexible and/or wearable niezoelectrics.

Enhanced domain wall conductivity in photosensitive ferroelectrics Sn_(2)P_(2)S_(6) with full-visible-spectrum absorption

Recent optical stimulation suggests a vital non-contact pathway to manipulate both macroscopic and microscopic ferroelectric properties and paves the foundation for optoelectronics devices.However,up to date,most optical-related manipulation of ferroelectric properties is restricted due to their intrinsic bandgap and limited visible light spectrum absorption.Here,we reveal non-oxide Sn_(2)P_(2)S_(6) single crystal possesses full-visible-spectrum absorption(from 300 to 800 nm)with a unique disproportionation mechanism of photoexcited Sn ions and Urbach tail,which is not contradicting to the intrinsic band gap.Interestingly,we observed the existence of conductive domain walls(c-DW)and the light illumination induced significant enhancement of the domain wall conductivity caused by such disproportionation reaction.In addition,the domains separated by c-DW also exhibited noticeable electrical conductivity difference in the presence of optical illumination owing to the interfacial polarization charge with opposite signs.The result provides a novel opportunity for understanding the electrical conductivity behavior of the domains and domain walls in ferroelectrics with full-visible-spectrum absorption and achieving greatly enhanced performances for optoelectronics.

Solid state reaction for the formation of spinel MgFe_2O_4 across perovskite oxide interface

Solid state reaction is a conventional method to synthesize structurally stable inorganic solids by mixing powdered reactants together at high pressure （over 1 x 105 mbar （1 mbar = 100 Pa）） and high temperature （over 1300 K） [1-4]. This method is effective and sophisticated to prepare solid mate- rials, especially the functional complex oxides such as high temperature superconductors, piezoelectrics, dielectrics, etc. However, the chemical reactions cannot be intrinsically con- trolled and integrated at an atomic level in order to achieve the applications of future thin film devices with reduced dimensions [5]. With the desire of designing high-quality products with the micro/nanoscale integration, many pow- erful physical techniques, such as, pulsed-laser deposition （PLD）, molecular beam epitaxy （MBE）, sputtering deposi- tion, etc., have experienced enormous development due to their ability of lattice and/or interfacial controls. Using these growth techniques, layer-by-layer deposition （multilayer and/or superlattice） can be achieved, providing us a platform to tune the crystal structures at an atomic level by controlling the interfacial terminations and epitaxial strain, which are absent in their bulk counterparts [6-8]. From this point of view, well-controlled interfacial structures may also provide the solid state reaction at an atomic level during the physical depositions, which provides us an effective way to design the desired products from the chemical bonding reconstruction.