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The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as well. It has long been established that space weathering leads to the formation of outmost amorphous layers (50-200 nm in thickness) embedded nanophase iron (npFe

Previous investigations of 4$H_b$-TaS$_{2-2x}$Se$_{2x}$ mainly focused on the direct competition between superconductivity and charge density wave (CDW). However, the superconductivity itself, although has been prominently enhanced by isovalent Se substitution, has not been adequately investigated. Here, we performed a detailed electrical transport measurement down to 0.1 K on a series of 4$H_b$-TaS$_{2-2x}$Se$_{2x}$ single crystals. A systematic fitting of the temperature-dependent resistance demonstrates that the decreased Debye temperatures ($\Theta_{D}$) and higher electron-phonon coupling constants ($\lambda_{e-p}$) at the optimal Se doping content raise the superconducting transition temperature ($T_c$). Additionally, we discovered that the incorporation of Se diminishes the degree of anisotropy of the superconductivity in the highly layered structure. More prominently, a comprehensive analysis of the vortex liquid phase region reveals that the optimally doped sample deviates from the canonical 2D Tinkham prediction but favors a linear trend with the variation of the external magnetic field. These findings emphasize the importance of interlayer interaction in this segregated superconducting-Mott-insulating system., Comment: 11 pages, 5 figures

The development of suitable red phosphors to obtain improved white color stands a good chance to serve in the new generation of white light-emitting diodes. Owing to multi-elements via doping and oxidation of reduced valence state of lanthanide or transition metal ions, most of the reported phosphors usually suffer from complex synthetic processes and unstable color of the lighting industry cycle. In this work, we present a new red emitting and stable Sr3Eu2B4O12 phosphor with regard to its special structure. It crystallizes as an orthorhombic cell, with Sr and Eu atoms co-occupying three different lattice sites in the space group of Pnma (no. 62). It is proposed that the long bond distance between activators minimizes the content quenching, while the high disorder of location restricts the thermal quenching. This phosphor emits bright red light with good color purity under UV excitation, with the luminescence intensity and quantum yield tunable via the fabrication temperature. Through a preliminary optimization of the synthesis process, the Sr3Eu2B4O12 phosphor prepared at 1250 °C has high quantum yields of about 94.7% and excellent thermal stability of 85.6% intensity retention at 150 °C relative to the initial value at room temperature. The calculated Judd–Ofelt intensity parameters (Ω2, Ω4) further clarified that the Eu3+ site in Sr3Eu2B4O12 had lower symmetry without an inversion center, and more distorted local environment and structural rigidity of the host, predicting excellent thermal stability. Finally, a warm pc-WLED device has been produced by mixing as-prepared Sr3Eu2B4O12 powders and commercial BaMgAl10O17:Eu2+ and (Sr, Ba)2SiO4:Eu2+ phosphors, which exhibits a high color rendering index (Ra = 83.4) along with a color temperature at around 4102 K. The present work indicates that the Sr3Eu2B4O12 phosphor is an efficient red component with excellent thermal stability for white-light production of near-UV-excited w-LEDs.

Two-dimensional electron gas (2DEG) formed at the interface between two insulating oxides offers an opportunity for fundamental research and device applications. Binary alkaline earth metal oxides possess compatible lattice constants with both silicon and perovskite oxides, exhibiting an enormous potential to bridging those two materials classes for multifunctionalities. Here we report the formation of 2DEG at the interface between the rock-salt BaO and SrTiO3. The highest electron mobility reaches 69000 cm^2 V.S^-1 at 2 K, leading to the typical Shubniko de Haas (SdH) oscillations under the high magnetic fields. The presence of SdH oscillations at different field-angles reveals a quasi-two-dimensional character of the Fermi surface. The first-principles calculations suggest that the effective charge transfer from the BaO to Ti 3dxy orbital at the interfaces is responsible to the observed high carrier mobility. Our results demonstrate that the BaO/STO heterointerface is a platform for exploring the correlated quantum phases, opening a door to the low-power and mesoscopic electronic devices., Comment: 18 pages; 5 figures

The stress-strain response of pristine monolayer graphene under uniaxial loading/unloading over a larger size range (100nm×100nm) is studied by molecular dynamics (MD) simulations, which proves that graphene is perfectly elastic prior to the failure strain. Young’s modulus of graphene is calculated by selecting different strain ranges in the elastic region. It is found that Young’s modulus is strongly dependent on the strain range. When the selected strain ranges are increased from 0.5% to 8%, Young’s modulus of the armchair and zigzag graphene is reduced by approximately 60 Gpa and 150 Gpa, respectively. Based on the Pearson correlation coefficient method, the linearity of the stress-strain curve during graphene stretching is studied. The elastic region of the tensile curve is divided into the linear elastic region and non-linear elastic region. simultaneously, the linear elastic limit strains for the armchair and zigzag graphene are defined to be about 2.5% and 1.5%, respectively, and they are independent of the size of graphene. On this basis, the chirality dependence and size effects of Young’s modulus, failure strain, and fracture strength of pristine monolayer graphene are investigated. The results show that Young’s modulus is dependent on the chiral angle but insensitive to size. The failure strain and fracture strength depend on the chiral angle and have obvious size effects, which decrease with the increase of size range and size ratio.

The recently discovered layered kagome metals AV_{3}Sb_{5} (A=K, Rb, and Cs) with vanadium kagome networks provide a novel platform to explore correlated quantum states intertwined with topological band structures. Here we report the prominent effect of hole doping on both superconductivity and charge density wave (CDW) order, achieved by selective oxidation of exfoliated thin flakes. A superconducting dome is revealed as a function of the effective doping content. The superconducting transition temperature (T_{c}) and upper critical field in thin flakes are significantly enhanced compared with the bulk, which are accompanied by the suppression of CDW. Our detailed analyses establish the pivotal role of van Hove singularities in promoting correlated quantum orders in these kagome metals. Our experiments not only demonstrate the intriguing nature of superconducting and CDW orders, but also provide a novel route to tune the carrier concentration through both selective oxidation and electric gating. This establishes CsV_{3}Sb_{5} as a tunable 2D platform for the further exploration of topology and correlation among 3d electrons in kagome lattices.

We report the structure and physical properties of two newly-discovered compounds AV8Sb12 and AV6Sb6 (A = Cs, Rb), which have C2 (space group: Cmmm) and C3 (space group: R-3m) symmetry, respectively. The basic V-kagome unit is present in both compounds, but stacking differently. A V2Sb2 layer is sandwiched between two V3Sb5 layers in AV8Sb12, altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In AV6Sb6, the building block is a more complex slab made up of two half-V3Sb5 layers that are intercalated by Cs cations along the c-axis. Transport property measurements demonstrate that both compounds are nonmagnetic metals, with carrier concentrations at around 1021cm-3. No superconductivity has been observed in CsV8Sb12 above 0.3 K under in-situ pressure up to 46 GPa. In contrast to CsV3Sb5, theoretical calculations and angle-resolved photoemission spectroscopy (ARPES) reveal a quasi-two-dimensional electronic structure in CsV8Sb12 with C2 symmetry and no van Hove singularities near the Fermi level. Our findings will stimulate more research into V-based kagome quantum materials., Comment: 11 pages 6 figures

The development of suitable red phosphors to obtain improved white color stands a good chance to serve in the new generation of white light-emitting diodes. Owing to multi-elements via doping and oxidation of reduced valence state of lanthanide or transition metal ions, most of the reported phosphors usually suffer from complex synthetic processes and unstable color of the lighting industry cycle. In this work, we present a new red emitting and stable Sr

The stress-strain response of pristine monolayer graphene under uniaxial loading/unloading over a more extensive size range (100 nm×100 nm) is studied by molecular dynamics simulations, which proves that graphene is perfectly elastic prior to the failure strain. Young’s modulus of graphene is calculated by selecting different strain ranges in the elastic region. It is found that Young’s modulus is strongly dependent on the strain range. When the selected strain ranges are increased from 0.5% to 8%, Young’s modulus of the armchair and zigzag graphene is reduced by approximately 60 GPa and 150 GPa, respectively. Based on the Pearson correlation coefficient method, the linearity of the stress-strain curve during graphene stretching is studied. The elastic region of the tensile curve is divided into the linear elastic region and non-linear elastic region. Simultaneously, the linear elastic limit strains for the armchair and zigzag graphene are defined to be about 2.5% and 1.5%, respectively, and they are independent of the size of graphene. On this basis, the chirality dependence and size effects of Young’s modulus, failure strain, and fracture strength of pristine monolayer graphene are investigated. The results show that Young’s modulus is dependent on the chiral angle but insensitive to size. The failure strain and fracture strength depend on the chiral angle and have obvious size effects.

We report the crystal structure and physical properties of two Ni

The static and dynamic mechanical behaviors of atoms/ions migrating on graphene surface are investigated via theoretical and numerical calculations, and a design idea of nano-scale device that can be used for atoms/ions screening is proposed on this basis. By using the Fourier expansion of the interaction potential between atoms, the analytical expression of the interaction force between an atom/ion and infinitely large graphene is derived. The dependence of the interaction force on the vertical distance from the atom/ion to graphene surface and the atomic/ionic types are analyzed. Based on the interaction force, a dynamics governing equation for the migration of atoms/ions on graphene surface is established, and the dynamics behaviors of atoms/ions when they migrate on the graphene surface at different initial velocities are studied. Taking lithium-ion as an example, it is found that there are three migration states along the armchair direction of graphene. No matter which migration state, the lithium-ion will eventually be stably adsorbed above the center of a hexagonal carbon ring (the hollow site). By adjusting the initial velocity, the lithium-ion can be steadily adsorbed at the specified sites, so as to control the migration distance of lithium-ion. What's more, the functional relationship between the critical initial velocity of the lithium-ion and the stable adsorption sites on graphene surface is given, and the influence of the vertical distance from the lithium-ion to graphene surface on the migration process is analyzed. In addition, the dynamics behaviors of the migration of different atoms/ions on graphene surface are studied, and it is found that the migration of alkali metal particles is more free with the increase of atomic number, and the stable site is further away from the initial position, which is in good agreement with the results of molecular dynamics simulation in the literature. Besides, the effects of initial position, damping and migration path on the dynamics behaviors of atoms/ions migrating on graphene surface are also studied. Finally, on the basis of theoretical results, a design idea of graphene-based nano-scale device is proposed, which can be used to screen specified atoms/ions and control their in and out positions.

The adsorption and migration behaviors of atoms/ions on the surface of infinite single-layer graphene are studied with the influence of surface corrugation taken into consideration. Based on Lennard-Jones (L-J) potential and Fourier expansion, the analytical expressions of the interaction potential and force between a single atom/ion and sinusoidal corrugated graphene are derived. The effects of lattice period, chirality, wavelength and amplitude of surface sinusoidal ripples on the mechanical behaviors of atom/ion adsorption and migration on graphene surface are analyzed. The interaction potential and force between the adsorbed atom/ion and graphene are found to be periodic when the lattice period of graphene and the wavelength of surface sinusoidal ripples meet a certain coupling relationship. Moreover, the periods of interaction potential and force, equilibrium position and diffusion barrier of the adsorbed atom/ion on the graphene surface can be regulated by changing the wavelength and amplitude of the sinusoidal ripples. Taking lithium-ion (Li1+) as an example, by changing the wavelength of the sinusoidal ripples, the equilibrium sites of a lithium-ion on the surface of graphene can be readjusted, and the magnitude and amount of the energy barriers that it gets over can be regulated when the lithium-ion moves along the surface of graphene. What is more, the amplitude of the sinusoidal ripples can significantly influence the tangential force exerted by the graphene on the moving lithium-ion. Finally, it is found that the migration of an adsorbed atom/ion on the surface of sinusoidal corrugated graphene is also dependent on the chirality of graphene. The magnitude and period of the energy barrier and tangential force are both different when a lithium-ion migrates on the graphene surface in its different chiral directions. This research may be helpful to lithium-ion batteries, monoatomic device design, and atoms/ions screening.

Based on the theories of solid state physics and quantum fracture mechanics, a theoretical model is proposed to investigate the fracture properties of pre-cracked single-layer graphene, and the analytical expressions of failure strength and fracture toughness of pre-cracked graphene are derived. Simultaneously, the failure strength of pre-cracked graphene is calculated by finite element method (FEM) based on molecular structure mechanics. The results of FEM are in good agreement with the theoretical counterparts. Via the theoretical analyses and numerical calculations, the effects of crack length, crack tip radius and domain size of graphene on the failure strength and fracture toughness of pre-cracked graphene are systematically studied. It is found that the failure strength of pre-cracked graphene gradually decreases with increasing crack length and domain size of graphene. However, as the crack tip radius increases, the failure strength gradually increases. In addition, it is also found that the crack length and domain size of graphene have little impact on the fracture toughness of graphene. The fracture toughness is significantly affected by crack tip radius.

Aimed at a rope deployment mechanism, under the hypothesis that the rope can not extend, the kinematic relationship between the rods and the multi-rigidbody geostatic model of the mechanism are established. Through the simulation and the mechanical analysis of the deployment process, the prototype deployment experiment had been done with controlling of the trace of the deployment velocity. The consequence shows the displacement, power consumption and disturbance of the mechanism accord with the expectation value of the theoretic model. It more shows our model could reflect the characteristic of this kind of mechanism, and also provides the gist for the deployment mechanism design。

A large Y-shaped Intersection usually has the triangular island inside. In order to improve the traffic capacity of the intersection without demolishing the triangular island, a large Y-shaped intersection secondary starting model was established based on a typical example, which also includes the relevant outcomes of the intersection signal design. By comparing the improved design to the original design via VISSIM, it seems that the proposed model in this paper achieved a favorable testing result as expected.

Micro-Raman Spectroscopy (MRS) is an effective stress measurement method. Generally, the application of MRS for stress measurement requires the quantitative relationship between Raman shift and stress based on the material of the objects to be measured. In this paper, a theoretical investigation of Raman stress measurement for porous silicon (PS) material was presented. First, the mathematical expressions for the Raman shift and stress components of transversely isotropic material were deduced by analyzing the transversely isotropic characteristics of porous silicon material and applying the secular equation of lattice dynamics for diamond-type crystal. Meanwhile, the nanoindentation technique and digital speckle correlation method were introduced to detect the elastic moduli and Poisson's ratio of porous silicon material, respectively. Subsequently, the Raman shift to stress coefficients of porous silicon material, as well as their regularity varying with PS porosity, are achieved by substituting the material parameters determined in the experiments into the analytic relationship acquired through deductions. Using these coefficients, the distribution of residual stress along the thickness direction in the PS-film/Si-substrate structure was measured.

Combined with one shaft construction employing pneumatic caisson in Shanghai, in-situ measurement of ground deformation was conducted. Based on the particular construction process of pneumatic caisson, one kinematic numerical analysis method was proposed for evaluating its influence on the surrounding strata. Through comparisons between calculated results and measurements, the proposed mechanical model and numerical analysis method were verified.

In order to investigate the positive rate of streptococcus suis type 2 and the genes of their suilysin (sly), extracellular protein (epf) and muramidasa-released protein ( mrp) and to understand the antibiotic susceptibility of S. suis type 2.S. suis type 2, isolated from slaughtered healthy pig's tonsil in 10 county area of Guangxi, were identified by Multiplex PCR, and the genes of their sly, epf, mrp and the antimicrobial sensitivity analysis were performed.1105 strains of Streptococcus including 667 strains of S. suis and 33 strains of S. suis type 2 were detected from 1179 samples. In these S. suis type 2 strains, there were 22 strains of sly + mrp + epf+ type,1 strain of sly + mrp + epf - type, 2 strains of sly - mrp + epf + type, 7 strains of sly - mrp + epf - type and 1 strain of sly - mrp - epf- type. When these strains were subjected to be tested with penicillin, eritrocina, vacocin, gentamycin, specti-nomysin, enraxacin, ciprofloxaxin, cephalothin VI, sulfadiazine sodium, cyantin, mycifradin, amikacin and achromcin, some were found to be resistant to but most strains were susceptible to cephalothin VI, penicillin and enraxacin. There were 31, 29 and 27 strains over medium sensitivity, respectively, but 28 and 27 resistant strains to amikacin and achromcin were found.The positive rate of S. suis type 2 in clinical healthy pigs was low (2.8%) and did not show obvious difference between the counties with or without a history of S. suis infection. All the isolated strains were susceptible to cephalothin VI, but most strains were virulent.

To observe the effect of Epimedium brevicornum, E. sagittatum, E. koreanum, E, wushanense and E. elongntum on the growth of cartilage and proliferation of cartilage cell in vitro.According to the paired design method, either femur of each chichen embryo was put into the control tube with the medium containing no Epimedium injection, and the other was put into the treated tube with the medium containing 3% Epimedium injection. The length and weight of cultured cartilage and proliferation of cartilage cell (MTY method) were used as the indices to observe the cartilage biological activities of the five species of Epimedium in culture.The results showed that the indices of length, weight and MTT in the E. brevicornum and E. sagittatum group were significantly higher than those in the contral group, but the above indices in groups E. koreanum, E. wushanens and E. elongntum were similar to those of the control with no statistical difference.E. brevicornum and E. sagittatum can improve the growth of cartilage and proliferation of cartilage cell in vitro, and other three Epimedium have not the same effect in this test.

Deformation mechanisms of carbon nanotube (CNT) fibres under tensile loading are studied by means of in situ Raman spectroscopy to detect the CNT deformation and stress distributions in the fibres. The G' band in the Raman spectrum responds distinctly to the tensile stress in Raman shift, width and intensity. The G' band changes with the tensile deformation of the fibre at different stages, namely elastic deformation, strengthening and damage-fracture. It is deduced that the individual CNTs only deform elastically without obvious damage or bond breaking. The yield and fracture of fibres can be due to the slippage among the CNTs.