The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method ...The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method is adopted to eliminate the fitting error of the datum plane. In order to diminish the length error of the object plane, the tactics of measuring some part of the plane and then scale to the whole plane is employed. With large quantity of measuring experiments on fiat plates, the most appropriate number of points in measuring a plane is determined to reduce the sampling error.展开更多
The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-per...The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.展开更多
We investigate the energy bands,magnetism,and superconductivity of bilayer octagraphene with A-A stackingunder a perpendicular electric field.A tight-binding model is used to analyze the band structure of the system.T...We investigate the energy bands,magnetism,and superconductivity of bilayer octagraphene with A-A stackingunder a perpendicular electric field.A tight-binding model is used to analyze the band structure of the system.The doubling of the unit cell results in each band of the single layer splitting into two.We find that applyinga perpendicular electric field increases the band splitting.As the electric field strength increases,the nestingof the Fermi surface(FS)weakens,eventually disrupting the antiferromagnetic order,and bilayer octagrapheneexhibits superconductivity.Spin fluctuations can induce unconventional superconductivity with s±-wave pairing.Applying a perpendicular electric field to bilayer octagraphene parent weakens the nesting of the FS,ultimatelykilling the spin-density-wave(SDW)ordered state and transitioning it into the superconducting state,whichworks as a doping effect.We use the random-phase approximation approach to obtain the pairing eigenvaluesand pairing symmetries of the perpendicular electric field-tuned bilayer octagraphene in the weak coupling limit.By tuning the strength of the perpendicular electric field,the critical interaction strength for SDW order can bemodified,which in turn may promote the emergence of unconventional superconductivity.展开更多
When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov l...When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.展开更多
Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching a...Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching angle shift”, where the applied direct current is assumed to shift, via domain wall depinning during anti-domain expansion, the switching angle of a perpendicular magnetization in a linear proportional manner under a large rotating magnetic field. Here, we report that, for the most commonly employed perpendicular magnetization heterostructures in spintronics(e.g., those based on FeCoB, Co, and Co/Ni multilayers), the switching angle shift considerably misestimates the SOT within the domain wall depinning analysis of the slope of linear-in-current scaling and may also have a non-zero residual value at zero direct current. Our experiments and simulations unveil that the switching angle shift is most likely dominated by chiral asymmetric nucleation rather than expansion of anti-domains. The in-plane field from external magnets and current-induced SOTs lowers the perpendicular nucleation field and thus reduces the required switching angle, ultimately leading to an underestimation of SOTs by domain wall depinning analysis. These results have advanced our understanding of magnetization switching in spintronic devices.展开更多
Pd/Co_(2)MnSi(CMS)/Co/Pd multilayer films were designed based on the idea of combining highly spin-polarized materials with strong perpendicular magnetic anisotropy(PMA)films.The PMA of Pd/CMS/Co/Pd multilayer films w...Pd/Co_(2)MnSi(CMS)/Co/Pd multilayer films were designed based on the idea of combining highly spin-polarized materials with strong perpendicular magnetic anisotropy(PMA)films.The PMA of Pd/CMS/Co/Pd multilayer films was studied by optimizing the growth conditions and thickness of each film layer.The optimal structure of the multilayer films was Pd(6 nm)/CMS(5 nm)/Co(2 nm)/Pd(1 nm).Its abnormal Hall resistance(R_(Hall)),coercivity(H_(c))and effective magnetic anisotropy constant(Keff)are 0.08Ω,284 Oe and 1.36 Merg/cm^(3),respectively,which are 100%,492%,and 183%higher than the corresponding values(0.04Ω,48 Oe,and 0.48 Merg/cm^(3))of the Pd(6 nm)/Co(1 nm)/Pd(3 nm)trilayer films.The analysis shows that the increases of the above values are the result of the Pd/CMS interface effect and CMS/Co interface ferromagnetic(FM)coupling,and that it is closely related to the thickness of each film layer in the multilayer films and the growth conditions of the multilayer films.展开更多
With the rapid development of deep learning neural networks,new solutions have emerged for addressing fluid flow problems in porous media.Combining data-driven approaches with physical constraints has become a hot res...With the rapid development of deep learning neural networks,new solutions have emerged for addressing fluid flow problems in porous media.Combining data-driven approaches with physical constraints has become a hot research direction,with physics-informed neural networks(PINNs) being the most popular hybrid model.PINNs have gained widespread attention in subsurface fluid flow simulations due to their low computational resource requirements,fast training speeds,strong generalization capabilities,and broad applicability.Despite success in homogeneous settings,standard PINNs face challenges in accurately calculating flux between irregular Eulerian cells with disparate properties and capturing global field influences on local cells.This limits their suitability for heterogeneous reservoirs and the irregular Eulerian grids frequently used in reservoir.To address these challenges,this study proposes a physics-informed graph neural network(PIGNN) model.The PIGNN model treats the entire field as a whole,integrating information from neighboring grids and physical laws into the solution for the target grid,thereby improving the accuracy of solving partial differential equations in heterogeneous and Eulerian irregular grids.The optimized model was applied to pressure field prediction in a spatially heterogeneous reservoir,achieving an average L_(2) error and R_(2) score of 6.710×10^(-4)and 0.998,respectively,which confirms the effectiveness of model.Compared to the conventional PINN model,the average L_(2) error was reduced by 76.93%,the average R_(2) score increased by 3.56%.Moreover,evaluating robustness,training the PIGNN model using only 54% and 76% of the original data yielded average relative L_(2) error reductions of 58.63% and 56.22%,respectively,compared to the PINN model.These results confirm the superior performance of this approach compared to PINN.展开更多
In cell cultures monolayered cell growth is controlled by contact inhibition which again is controlled by the cell polarity system by always being positioned in accord with the cytoskeleton axis. Presently, cycling en...In cell cultures monolayered cell growth is controlled by contact inhibition which again is controlled by the cell polarity system by always being positioned in accord with the cytoskeleton axis. Presently, cycling endopolyploid cells (tetraploidy) were shown to undergo perpendicular divisions relative to the cytoskeleton axis which disrupted to some degree contact inhibition in the near-senescent phase of human primary cells. These experiments included genome damage-induced endopolyploidization (TAS-treated) to simulate as a model system the state of in vivo accelerated cell senescence (ACS) which is induced by therapy-associated genomic damage. From ACS delayed tumor re-growth (re-lapse) occurs from “robust” cell propagation, but mechanisms for such cell escape from senescence are unknown. For TAS-treated a karyoplast bud-off process with change to limited mitotic activity occurred in young senescent cultures. In old, deep senescent (5 - 8 weeks) cultures, unexpectedly escape cell-growth showed three dimensional (3-D) tumor-like spheres from growths of morphologically different cells as compared to the fibroblastic phenotype. These cells expressed cell polarity change, and very condensed nuclei were variously perpendicularly oriented to what-ever cell polarity was present. These results were discussed in regard to in vivo relapse and, to the importance of cell polarity change in tumorigenesis. Induced senescence as an anti-tumor mechanism in therapy treatment becomes a questionable procedure from the present experimental results.展开更多
In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on t...In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on the analysis of the test results,the following conclusions can be drawn.Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain.Brittle failure happened for all tensile tests.The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain.The failure modes for bamboo scrimber specimens under compression parallel to grain could be divided into four.Only one main failure mode happened both for the bending specimens and the shear specimens.With the COV values of 28.64 and 25.72 respectively,the values for the strength and elastic modulus under tensile perpendicular to grain have the largest discreteness for bamboo scrimber.From the point of CHV values,the relationship among the mechanical parameters for bamboo scrimber were proposed based on the test results.Compared with other green building materials,bamboo scrimber manufactured based on a new technique has better mechanical performance and could be used in construction area.Three stress strain relationship models which are four-linear model,quadratic function model,and cubic function model were proposed for bamboo scrimber specimens manufactured based on a new technique.The latter two models gives better prediction for stress strain relationship in elastic plastic stage.展开更多
In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one differen...In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.展开更多
Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers....Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.展开更多
Graphene-based materials on wearable electronics and bendable displays have received considerable attention for the mechanical flexibility,superior electrical conductivity,and high surface area,which are proved to be ...Graphene-based materials on wearable electronics and bendable displays have received considerable attention for the mechanical flexibility,superior electrical conductivity,and high surface area,which are proved to be one of the most promising candidates of stretching and wearable sensors.However,polarized electric charges need to overcome the barrier of graphene sheets to cross over flakes to penetrate into the electrode,as the graphene planes are usually parallel to the electrode surface.By introducing electron-induced perpendicular graphene(EIPG)electrodes incorporated with a stretchable dielectric layer,a flexible and stretchable touch sensor with"in-sheet-chargestransportation"is developed to lower the resistance of carrier movement.The electrode was fabricated with porous nanostructured architecture design to enable wider variety of dielectric constants of only 50-μm-thick Ecoflex layer,leading to fast response time of only 66 ms,as well as high sensitivities of 0.13 kPa-1 below 0.1 kPa and 4.41 MPa-1 above 10 kPa,respectively.Moreover,the capacitance-decrease phenomenon of capacitive sensor is explored to exhibit an object recognition function in one pixel without any other integrated sensor.This not only suggests promising applications of the EIPG electrode in flexible touch sensors but also provides a strategy for internet of things security functions.展开更多
[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on ...[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on the structure and magnetic properties of the multilayers were investigated. It was found that the difference between in-plane and out-of-plane coercivities varied with an increase of inserted Ag layer thickness in the [FePt 2 nm/Ag x nm]10 multilayers. The ratio of out-of-plane coercivity to in-plane coercivity reached the maximum value with the Ag layer thickness of 5 nm, indicating that the Ag layer thickness plays an important role in obtaining perpendicular orientation. For the [FePt 2 nm/Ag 5 um]n multilayers, perpendicular orientation is also influenced by n. The maximum value of the ratio of out-of-plane coercivity to in-plane coercivity appeared when n was given as 8. It was found that the [FePt 2 nm/Ag 5 nm]8 had a high perpendicular coercivity of 520 kA/m and a low in-plane one of 88 kA/m, which shows a strong perpendicular anisotropy.展开更多
D-InSAR is currently one of the most popular research tools in the field of Microwave Remote Sensing. It is unrivaled in its aspect of measuring ground deformation due to its advantages such as high resolution,continu...D-InSAR is currently one of the most popular research tools in the field of Microwave Remote Sensing. It is unrivaled in its aspect of measuring ground deformation due to its advantages such as high resolution,continuous spa-tial-coverage and dynamics. However,there are still a few major problems to be solved urgently as a result of the intrin-sic complexity of this technique. One of the problems deals with improving the accuracy of measured ground deforma-tion. In this paper,various factors affecting the accuracy of ground deformation measured by D-InSAR are systemati-cally analyzed and investigated by means of the law of measurement error propagation. At the same time,we prove that the ground deformation error not only depends on the errors of perpendicular baselines as well as the errors of the inter-ferometric phase for topographic pair and differential pair,but also on the combination of the relationship of perpen-dicular baselines for topographic pairs and differential pairs. Furthermore,a feasible approach for improving the accu-racy of measured ground deformation is proposed,which is of positive significance in the practical application of D-InSAR.展开更多
Stable operation of aircraft engine compressions is constrained by rotating surge. In this paper, an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is pres...Stable operation of aircraft engine compressions is constrained by rotating surge. In this paper, an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented. Firstly, this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors. Secondly, the expansion form of equilibrium manifold is introduced, and the choosing scheduling variable method is discussed. Then, this paper also gives the identification procedure of modeling the approximate nonlinear model. Finally, the modeling and simulations with high pressure （liP） compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermody- namic model, but has simpler structure and shorter computation time.展开更多
In a magnetic nanostripe, the effects of perpendicular magnetic anisotropy（PMA） on the current-driven horizontal motion of vortex wall along the stripe and the vertical motion of the vortex core are studied by micro...In a magnetic nanostripe, the effects of perpendicular magnetic anisotropy（PMA） on the current-driven horizontal motion of vortex wall along the stripe and the vertical motion of the vortex core are studied by micromagnetic simulations.The results show that the horizontal and vertical motion can generally be monotonously enhanced by PMA. However, when the current is small, a nonmonotonic phenomenon for the horizontal motion is found. Namely, the velocity of the horizontal motion firstly decreases and then increases with the increase of the PMA. We find that the reason for this is that the PMA can firstly increase and then decrease the confining force induced by the confining potential energy. In addition, the PMA always enhances the driving force induced by the current.展开更多
The synthesis of a perpendicular growth structure of MoS_(2)nanosheets on graphene for efficient sodium storage is challenging yet ideal due to the benefits of open ion diffusion channels and high electronic conductiv...The synthesis of a perpendicular growth structure of MoS_(2)nanosheets on graphene for efficient sodium storage is challenging yet ideal due to the benefits of open ion diffusion channels and high electronic conductivity.In this study,we have successfully fabricated a novel structure of vertical MoS_(2)nanosheets on graphene,with ZnS nanoparticles serving as bonding points(MoS_(2)/ZnS/G),through a facile hydrothermal method.During the synthesis process,Zn^(2+)not only acts as a landing site for the vertical growth of MoS_(2)nanosheets but also triggers the formation of a defect-rich structure in the final samples.This unique architecture of MoS_(2)/ZnS/G effectively combines the advantages of a vertically aligned geometry and a defectrich structure for energy storage.The resulting structure displays shortened transport paths for electrons/ions,enhanced conductivity,improved structural integrity,and an increased number of active sites for promising electrochemical performance.As expected,when used as anode for sodium-ion batteries,the as-synthesize d MoS_(2)/ZnS/G exhibits excellent rate capability(high capacity of 298 mAh·g^(-1)at 5 A·g^(-1))and good cycling stability(a capacity decay of 0.056%per cycle after 500 cycles at 1 A·g^(-1)).According to the kinetic investigations,the electrochemical process of the MoS_(2)/ZnS/G sample is primarily governe d by a pseudocapacitive behavior,which enhances the charge/discharge kinetics and allows the MoS_(2)/ZnS/G structure to remain intact during cycling.展开更多
ZSM-5 plates with a perpendicular intergrowth structure was synthesized by using a simple amine as the structure directing agent under hydrothermal conditions,in which the mother plate and the perpendicularly standing...ZSM-5 plates with a perpendicular intergrowth structure was synthesized by using a simple amine as the structure directing agent under hydrothermal conditions,in which the mother plate and the perpendicularly standing plates oriented along the(010)and(100)planes of MFI crystals,respectively.During the crystallization process,the mother plate was initially formed on the surface of the amorphous solid gel,while a set of parallel plates perpendicularly grew on its surface,via a homogeneous nucleation mechanism.The mother plate and the perpendicular plates had a similar thickness of 100-200 nm and were characterized by considerably shortened straight and zigzag 10 member ring pores,respectively.This unique intergrowth structure greatly facilitated the diffusion of the reactive molecules in HZSM-5 crystals during methanol conversion to hydrocarbons.展开更多
基金sponsored by the Special Research Fund for Young Teachers of Universities in Shanghai under Grant No.gjd-07048
文摘The principle of planc-to-plane perpendicularity measuring with coordinate measuring machine （CMM） is described and the main factors that influence the measuring precision are analyzed. The minimum condition method is adopted to eliminate the fitting error of the datum plane. In order to diminish the length error of the object plane, the tactics of measuring some part of the plane and then scale to the whole plane is employed. With large quantity of measuring experiments on fiat plates, the most appropriate number of points in measuring a plane is determined to reduce the sampling error.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1204000)the Beijing National Natural Science Foundation(Grant No.Z230006)the National Natural Science Foundation of China(Grant Nos.12304155 and 12274405).
文摘The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1402802)the National Natural Science Foundation of China(Grant Nos.12494591 and 92165204)+4 种基金the Leading Talent Program of Guangdong Special Projects(Grant No.201626003)the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the Research Center for Magnetoelectric Physics of Guangdong Province(Grant No.2024B0303390001)the Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2401010)supported by the National Natural Science Foundation of China(Grant Nos.12234016 and 12074031)。
文摘We investigate the energy bands,magnetism,and superconductivity of bilayer octagraphene with A-A stackingunder a perpendicular electric field.A tight-binding model is used to analyze the band structure of the system.The doubling of the unit cell results in each band of the single layer splitting into two.We find that applyinga perpendicular electric field increases the band splitting.As the electric field strength increases,the nestingof the Fermi surface(FS)weakens,eventually disrupting the antiferromagnetic order,and bilayer octagrapheneexhibits superconductivity.Spin fluctuations can induce unconventional superconductivity with s±-wave pairing.Applying a perpendicular electric field to bilayer octagraphene parent weakens the nesting of the FS,ultimatelykilling the spin-density-wave(SDW)ordered state and transitioning it into the superconducting state,whichworks as a doping effect.We use the random-phase approximation approach to obtain the pairing eigenvaluesand pairing symmetries of the perpendicular electric field-tuned bilayer octagraphene in the weak coupling limit.By tuning the strength of the perpendicular electric field,the critical interaction strength for SDW order can bemodified,which in turn may promote the emergence of unconventional superconductivity.
基金supported by the National Key Research Program of China(Grant Nos.2021YFA1401900,2022YFA1403300,and 2020YFA0309100)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0302602 and 2024ZD0300103)+1 种基金the National Natural Science Foundation of China(Grant No.12074073)for samplefabrication and measurementthe support by the The Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08).
文摘When a perpendicular magnetic field penetrates a thin slab of a type-Ⅱ superconductor it produces vortices,with one vortex per flux quantum,h/2e.The vortices interact repulsively and form an ordered array(Abrikosov lattice)in clean systems,while strong disorder changes the lattice into a vortex glass.The collective vortex dynamics is extremely vulnerable to external perturbations.Consequently,although of great importance,experimental observation is limited.Here we investigate type-Ⅱ superconducting films(PdBi_(2)and NbSe_(2))with surface acoustic waves(SAWs)at mK temperature.When sweeping the magnetic field at an extremely slow rate,we observe a series of spikes in the attenuation and velocity of the SAW,on average separated in field by approximately Hc1.We propose the following scenario:The vortex-free region at the edges of the film produces an edge barrier across which the vortices can enter or leave.When the applied field changes,the induced supercurrents flowing along this edge region lowers this barrier until there is an instability.At that point,vortices avalanche into(or out of)the bulk and change the vortex crystal,suggested by the sharp jump in each such spike.The vortices then gradually relax to a new stable pinned configuration,leading to a~30 s relaxation after the jump.Our observation enriches the limited experimental evidence on the important topic of real-time vortex dynamics in superconductors.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFA1204000)partly by the National Natural Science Foundation of China (Grant Nos.12274405,12304155,and 12393831)the Beijing Natural Science Foundation (Grant No.Z230006)。
文摘Accurate quantification of the spin–orbit torques(SOTs) is critical for the identification and applications of new spin-orbitronic effects. One of the most popular techniques to quantify the SOTs is the “switching angle shift”, where the applied direct current is assumed to shift, via domain wall depinning during anti-domain expansion, the switching angle of a perpendicular magnetization in a linear proportional manner under a large rotating magnetic field. Here, we report that, for the most commonly employed perpendicular magnetization heterostructures in spintronics(e.g., those based on FeCoB, Co, and Co/Ni multilayers), the switching angle shift considerably misestimates the SOT within the domain wall depinning analysis of the slope of linear-in-current scaling and may also have a non-zero residual value at zero direct current. Our experiments and simulations unveil that the switching angle shift is most likely dominated by chiral asymmetric nucleation rather than expansion of anti-domains. The in-plane field from external magnets and current-induced SOTs lowers the perpendicular nucleation field and thus reduces the required switching angle, ultimately leading to an underestimation of SOTs by domain wall depinning analysis. These results have advanced our understanding of magnetization switching in spintronic devices.
基金Project supported by Shandong Provincial Natural Science Foundation,China(Grant No.ZR2022ME059)。
文摘Pd/Co_(2)MnSi(CMS)/Co/Pd multilayer films were designed based on the idea of combining highly spin-polarized materials with strong perpendicular magnetic anisotropy(PMA)films.The PMA of Pd/CMS/Co/Pd multilayer films was studied by optimizing the growth conditions and thickness of each film layer.The optimal structure of the multilayer films was Pd(6 nm)/CMS(5 nm)/Co(2 nm)/Pd(1 nm).Its abnormal Hall resistance(R_(Hall)),coercivity(H_(c))and effective magnetic anisotropy constant(Keff)are 0.08Ω,284 Oe and 1.36 Merg/cm^(3),respectively,which are 100%,492%,and 183%higher than the corresponding values(0.04Ω,48 Oe,and 0.48 Merg/cm^(3))of the Pd(6 nm)/Co(1 nm)/Pd(3 nm)trilayer films.The analysis shows that the increases of the above values are the result of the Pd/CMS interface effect and CMS/Co interface ferromagnetic(FM)coupling,and that it is closely related to the thickness of each film layer in the multilayer films and the growth conditions of the multilayer films.
基金supported by the National Natural Science Foundation of China (No. 52274048)Beijing Natural Science Foundation (No. 3222037)。
文摘With the rapid development of deep learning neural networks,new solutions have emerged for addressing fluid flow problems in porous media.Combining data-driven approaches with physical constraints has become a hot research direction,with physics-informed neural networks(PINNs) being the most popular hybrid model.PINNs have gained widespread attention in subsurface fluid flow simulations due to their low computational resource requirements,fast training speeds,strong generalization capabilities,and broad applicability.Despite success in homogeneous settings,standard PINNs face challenges in accurately calculating flux between irregular Eulerian cells with disparate properties and capturing global field influences on local cells.This limits their suitability for heterogeneous reservoirs and the irregular Eulerian grids frequently used in reservoir.To address these challenges,this study proposes a physics-informed graph neural network(PIGNN) model.The PIGNN model treats the entire field as a whole,integrating information from neighboring grids and physical laws into the solution for the target grid,thereby improving the accuracy of solving partial differential equations in heterogeneous and Eulerian irregular grids.The optimized model was applied to pressure field prediction in a spatially heterogeneous reservoir,achieving an average L_(2) error and R_(2) score of 6.710×10^(-4)and 0.998,respectively,which confirms the effectiveness of model.Compared to the conventional PINN model,the average L_(2) error was reduced by 76.93%,the average R_(2) score increased by 3.56%.Moreover,evaluating robustness,training the PIGNN model using only 54% and 76% of the original data yielded average relative L_(2) error reductions of 58.63% and 56.22%,respectively,compared to the PINN model.These results confirm the superior performance of this approach compared to PINN.
文摘In cell cultures monolayered cell growth is controlled by contact inhibition which again is controlled by the cell polarity system by always being positioned in accord with the cytoskeleton axis. Presently, cycling endopolyploid cells (tetraploidy) were shown to undergo perpendicular divisions relative to the cytoskeleton axis which disrupted to some degree contact inhibition in the near-senescent phase of human primary cells. These experiments included genome damage-induced endopolyploidization (TAS-treated) to simulate as a model system the state of in vivo accelerated cell senescence (ACS) which is induced by therapy-associated genomic damage. From ACS delayed tumor re-growth (re-lapse) occurs from “robust” cell propagation, but mechanisms for such cell escape from senescence are unknown. For TAS-treated a karyoplast bud-off process with change to limited mitotic activity occurred in young senescent cultures. In old, deep senescent (5 - 8 weeks) cultures, unexpectedly escape cell-growth showed three dimensional (3-D) tumor-like spheres from growths of morphologically different cells as compared to the fibroblastic phenotype. These cells expressed cell polarity change, and very condensed nuclei were variously perpendicularly oriented to what-ever cell polarity was present. These results were discussed in regard to in vivo relapse and, to the importance of cell polarity change in tumorigenesis. Induced senescence as an anti-tumor mechanism in therapy treatment becomes a questionable procedure from the present experimental results.
基金supported by the National Natural Science Foundation of China(51878354)the Natural Science Foundation of Jiang-su Province(No.BK20181402)+1 种基金Six Peak High-level Talents Project of Jiangsu Provincea Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on the analysis of the test results,the following conclusions can be drawn.Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain.Brittle failure happened for all tensile tests.The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain.The failure modes for bamboo scrimber specimens under compression parallel to grain could be divided into four.Only one main failure mode happened both for the bending specimens and the shear specimens.With the COV values of 28.64 and 25.72 respectively,the values for the strength and elastic modulus under tensile perpendicular to grain have the largest discreteness for bamboo scrimber.From the point of CHV values,the relationship among the mechanical parameters for bamboo scrimber were proposed based on the test results.Compared with other green building materials,bamboo scrimber manufactured based on a new technique has better mechanical performance and could be used in construction area.Three stress strain relationship models which are four-linear model,quadratic function model,and cubic function model were proposed for bamboo scrimber specimens manufactured based on a new technique.The latter two models gives better prediction for stress strain relationship in elastic plastic stage.
基金supported by the Natural Science Foundation of Jiang-su Province(No.BK20181402)the National Natural Science Foundation of China(51878354)+3 种基金National Key R&D Program of China,the Open Fund Project from Key Laboratory of Concrete and Pre-stressed Concrete Structure of Ministry of Education(Southeast university)the China Postdoctoral Science Foundation(2015M580382)Jiangsu Postdoctoral Science Foundation Project(1501037A)Qing Lan Project,and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.
基金financially supported by the National Natural Science Foundation of China (Nos. 11174020, 51331002, and 51371027)the Fundamental Research Funds for the Central Universities FRF-SD-12-011A
文摘Pseudo spin valves（SVs） exhibiting perpendicular magnetic anisotropy were prepared by magnetron sputtering. Magnetization measurements of the Co/Pt multilayers were performed to select the reference and free layers. The selection criteria are square magnetic hysteresis loops, weaker current shunting effect, and proper coercivity. The optimal reference layer and free layer are Pt（5.0 nm）/[Co（0.4 nm）/Pt（0.6 nm）]3/Co（0.4 nm）/Cu（3.0 nm）and Cu（3.0 nm）/[Co（0.4 nm）/Pt（1.5 nm）]4, respectively.The resulting pseudo SV exhibits two well-separated hysteresis loops when the field is applied perpendicular to the film plane. The minor hysteresis loop corresponding to the free layer shifts toward negative direction of the magnetic field axis, indicating ferromagnetic interlayer exchange coupling between the two magnetic layers. The coupling also enhances the coercivity（HC） of both layers. The perpendicular giant magnetoresistance（GMR） of 2.7 % is achieved with current in plane measurement. The GMR first increases when Pt seed layer is thickened, reaches a maximum of 3.0 % at 4 nm and then decreases with the further increase of thickness. But thicker Cu spacer layer always lowers the GMR of the SV.
基金the National Key R&D Program of China(Grant No.2018YFB1306100)China Postdoctoral Science Foundation(Grant No.2019M653607)the Fundamental Research Funds for the Central Universities。
文摘Graphene-based materials on wearable electronics and bendable displays have received considerable attention for the mechanical flexibility,superior electrical conductivity,and high surface area,which are proved to be one of the most promising candidates of stretching and wearable sensors.However,polarized electric charges need to overcome the barrier of graphene sheets to cross over flakes to penetrate into the electrode,as the graphene planes are usually parallel to the electrode surface.By introducing electron-induced perpendicular graphene(EIPG)electrodes incorporated with a stretchable dielectric layer,a flexible and stretchable touch sensor with"in-sheet-chargestransportation"is developed to lower the resistance of carrier movement.The electrode was fabricated with porous nanostructured architecture design to enable wider variety of dielectric constants of only 50-μm-thick Ecoflex layer,leading to fast response time of only 66 ms,as well as high sensitivities of 0.13 kPa-1 below 0.1 kPa and 4.41 MPa-1 above 10 kPa,respectively.Moreover,the capacitance-decrease phenomenon of capacitive sensor is explored to exhibit an object recognition function in one pixel without any other integrated sensor.This not only suggests promising applications of the EIPG electrode in flexible touch sensors but also provides a strategy for internet of things security functions.
基金This work is financially supported by the National Natural Science Foundation of China (No. 10574085) Natural Science Foundation ofShanxi Province, China (No. 20041032).
文摘[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on the structure and magnetic properties of the multilayers were investigated. It was found that the difference between in-plane and out-of-plane coercivities varied with an increase of inserted Ag layer thickness in the [FePt 2 nm/Ag x nm]10 multilayers. The ratio of out-of-plane coercivity to in-plane coercivity reached the maximum value with the Ag layer thickness of 5 nm, indicating that the Ag layer thickness plays an important role in obtaining perpendicular orientation. For the [FePt 2 nm/Ag 5 um]n multilayers, perpendicular orientation is also influenced by n. The maximum value of the ratio of out-of-plane coercivity to in-plane coercivity appeared when n was given as 8. It was found that the [FePt 2 nm/Ag 5 nm]8 had a high perpendicular coercivity of 520 kA/m and a low in-plane one of 88 kA/m, which shows a strong perpendicular anisotropy.
基金Projects 400471090 supported by the National Natural Science Foundation of China and 1421 by the European Space Agency
文摘D-InSAR is currently one of the most popular research tools in the field of Microwave Remote Sensing. It is unrivaled in its aspect of measuring ground deformation due to its advantages such as high resolution,continuous spa-tial-coverage and dynamics. However,there are still a few major problems to be solved urgently as a result of the intrin-sic complexity of this technique. One of the problems deals with improving the accuracy of measured ground deforma-tion. In this paper,various factors affecting the accuracy of ground deformation measured by D-InSAR are systemati-cally analyzed and investigated by means of the law of measurement error propagation. At the same time,we prove that the ground deformation error not only depends on the errors of perpendicular baselines as well as the errors of the inter-ferometric phase for topographic pair and differential pair,but also on the combination of the relationship of perpen-dicular baselines for topographic pairs and differential pairs. Furthermore,a feasible approach for improving the accu-racy of measured ground deformation is proposed,which is of positive significance in the practical application of D-InSAR.
基金National Natural Science Foundation of China (61104146)Innovation Plan of Aero Engine Complex System Safety by the Ministry of Education Chang Jiang Scholars of China (IRT0905)
文摘Stable operation of aircraft engine compressions is constrained by rotating surge. In this paper, an approximate nonlinear surge margin model of aircraft engine compression system by using equilibrium manifold is presented. Firstly, this paper gives an overview of the current state of modeling aerodynamic flow instabilities in engine compressors. Secondly, the expansion form of equilibrium manifold is introduced, and the choosing scheduling variable method is discussed. Then, this paper also gives the identification procedure of modeling the approximate nonlinear model. Finally, the modeling and simulations with high pressure （liP） compressor surge margin of the aircraft engine show that this real-time model has the same accuracy with the thermody- namic model, but has simpler structure and shorter computation time.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11247026 and 11374253)
文摘In a magnetic nanostripe, the effects of perpendicular magnetic anisotropy（PMA） on the current-driven horizontal motion of vortex wall along the stripe and the vertical motion of the vortex core are studied by micromagnetic simulations.The results show that the horizontal and vertical motion can generally be monotonously enhanced by PMA. However, when the current is small, a nonmonotonic phenomenon for the horizontal motion is found. Namely, the velocity of the horizontal motion firstly decreases and then increases with the increase of the PMA. We find that the reason for this is that the PMA can firstly increase and then decrease the confining force induced by the confining potential energy. In addition, the PMA always enhances the driving force induced by the current.
基金financially supported by the Natural Science Foundation of Jiangsu Province(No.BK20211352)the Nature Science Fundation of Jiangsu Higher Education Institutions of China(No.22KJA430005)。
文摘The synthesis of a perpendicular growth structure of MoS_(2)nanosheets on graphene for efficient sodium storage is challenging yet ideal due to the benefits of open ion diffusion channels and high electronic conductivity.In this study,we have successfully fabricated a novel structure of vertical MoS_(2)nanosheets on graphene,with ZnS nanoparticles serving as bonding points(MoS_(2)/ZnS/G),through a facile hydrothermal method.During the synthesis process,Zn^(2+)not only acts as a landing site for the vertical growth of MoS_(2)nanosheets but also triggers the formation of a defect-rich structure in the final samples.This unique architecture of MoS_(2)/ZnS/G effectively combines the advantages of a vertically aligned geometry and a defectrich structure for energy storage.The resulting structure displays shortened transport paths for electrons/ions,enhanced conductivity,improved structural integrity,and an increased number of active sites for promising electrochemical performance.As expected,when used as anode for sodium-ion batteries,the as-synthesize d MoS_(2)/ZnS/G exhibits excellent rate capability(high capacity of 298 mAh·g^(-1)at 5 A·g^(-1))and good cycling stability(a capacity decay of 0.056%per cycle after 500 cycles at 1 A·g^(-1)).According to the kinetic investigations,the electrochemical process of the MoS_(2)/ZnS/G sample is primarily governe d by a pseudocapacitive behavior,which enhances the charge/discharge kinetics and allows the MoS_(2)/ZnS/G structure to remain intact during cycling.
文摘ZSM-5 plates with a perpendicular intergrowth structure was synthesized by using a simple amine as the structure directing agent under hydrothermal conditions,in which the mother plate and the perpendicularly standing plates oriented along the(010)and(100)planes of MFI crystals,respectively.During the crystallization process,the mother plate was initially formed on the surface of the amorphous solid gel,while a set of parallel plates perpendicularly grew on its surface,via a homogeneous nucleation mechanism.The mother plate and the perpendicular plates had a similar thickness of 100-200 nm and were characterized by considerably shortened straight and zigzag 10 member ring pores,respectively.This unique intergrowth structure greatly facilitated the diffusion of the reactive molecules in HZSM-5 crystals during methanol conversion to hydrocarbons.
