Structure characterization of the oxide film on FGH96 superalloy powders with various oxidation degrees

The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys.In this study,FGH96 alloy powders with various oxygen contents were investigated using high-resolution transmission electron microscopy and atomic probe technology to elucidate the structure evolution of the oxide film.Energy dispersive spectrometer analysis revealed the presence of two distinct components in the oxide film of the alloy powders:amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide.The alloying elements within the oxide layer showed a laminated distribution,with Ni,Co,Cr,and Al/Ti,which was attributed to the decreasing oxygen equilibrium pressure as oxygen diffused from the surface into the γ matrix.On the other hand,Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase.Comparative analysis of the oxide film with oxygen contents of 140,280,and 340 ppm showed similar element distributions,while the thickness of the oxide film varies approximately at 9,14,and 30 nm,respectively.These findings provide valuable insights into the structural analysis of the oxide film on FGH96 alloy powders.

Improved simulation of winter wheat yield in North China Plain by using PRYM-Wheat integrated dry matter distribution coefficient

The accurate simulation of regional-scale winter wheat yield is important for national food security and the balance of grain supply and demand in China.Presently,most remote sensing process models use the“biomass×harvest index(HI)”method to simulate regional-scale winter wheat yield.However,spatiotemporal differences in HI contribute to inaccuracies in yield simulation at the regional scale.Time-series dry matter partition coefficients(Fr)can dynamically reflect the dry matter partition of winter wheat.In this study,Fr equations were fitted for each organ of winter wheat using site-scale data.These equations were then coupled into a process-based and remote sensingdriven crop yield model for wheat(PRYM-Wheat)to improve the regional simulation of winter wheat yield over the North China Plain(NCP).The improved PRYM-Wheat model integrated with the fitted Fr equations(PRYM-Wheat-Fr)was validated using data obtained from provincial yearbooks.A 3-year(2000-2002)averaged validation showed that PRYM-Wheat-Fr had a higher coefficient of determination(R^(2)=0.55)and lower root mean square error(RMSE=0.94 t ha^(-1))than PRYM-Wheat with a stable HI(abbreviated as PRYM-Wheat-HI),which had R^(2) and RMSE values of 0.30 and 1.62 t ha^(-1),respectively.The PRYM-Wheat-Fr model also performed better than PRYM-Wheat-HI for simulating yield in verification years(2013-2015).In conclusion,the PRYM-Wheat-Fr model exhibited a better accuracy than the original PRYM-Wheat model,making it a useful tool for the simulation of regional winter wheat yield.

Effect of seed layers on the static and dynamic magnetic properties of CoIr films with negative effective magnetocrystalline anisotropy

The c-axis oriented hcp-Co_(81)Ir_(19)magnetic films were prepared on different seed layers(Ni,Cu,Ir,Pt,Au,and No seed).We systematically investigated the impact that surface-free energy and strain energy have on the orientation and defects and/or internal stress of the grains by increasing the lattice mismatch ratio.Moreover,the initial permeability and the natural resonance frequency were discussed in great detail using a comparison between calculated values and experimental values.We found that the almost unchanged 4πM_(s) andμ_(i) are not affected,while the changed H_(c),intrinsic K_(grain),and f_(r) are strongly dependent on the seed layer and seed layer material.Moreover,the extracted damping constant is sensitive to the defects and/or internal stress and orientation of the grains.Therefore,the soft magnetic properties and microwave properties are adjusted and optimized by seed layers with different materials.

Flow softening and dynamic recrystallization behavior of a Mg-Gd-Y-Nd-Zr alloy under elevated temperature compressions

Flow softening behavior of a homogenized Mg-7Gd-4Y-1Nd-0.5Zr alloy under compression to a final strain of∼1.8 at elevated temperatures of 450∼550℃ and a constant strain rate of 2s^(−1) has been investigated by optical microscopy,scanning electron microscopy,electron back-scattered diffraction and transmission electron microscopy.The results show that true stress first rises to the peak point and then drops to the bottom value and increases again with further increasing strain at each temperature.Twinning dynamic recrystallization(DRX)and continuous DRX contribute to the formation of new fine grains at temperatures 450∼475℃ when the restoration is caused by both DRX and texture change due to extension twinning,resulting in the larger softening degrees compared with the softening effects owing to continuous DRX and discontinuous DRX at 500∼550℃ when twinning activation is suppressed.500℃ is the transition temperature denoting a significant decline in the contribution of twinning and TDRX to the strain with increasing temperature.The cuboid-shape phase exists in both homogenized and compressed samples,while the compositions are varied.

A two-scale approach for estimating forest aboveground biomass with optical remote sensing images in a subtropical forest of Nepal

Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.

影响弱体质大学生体育锻炼投入的因素研究

为探索主观体验和社会支持在锻炼认同与锻炼投入关系中的中介作用。采用锻炼认同量表、锻炼投入量表、主观锻炼体验量表、领悟社会支持量表对选取的川、滇、黔三省6所高校的600名弱体质大学生进行测试。相关分析显示,锻炼认同与锻炼投入呈显著正相关关系,其余各变量之间均呈现显著的正相关。中介分析显示,主观体验和社会支持在锻炼认同与锻炼投入之间起中介作用,Bootstrap方法检验得出,锻炼认同和锻炼投入之间的三条中介路径上存在显著效果。弱体质大学生具有正确的锻炼价值认知,但由于曾经参与体育锻炼中的不良锻炼体验,主观经验和体验记忆造成了弱体质大学生不愿参与到体育锻炼中,研究发现可以通过介入理性认知系统,让决策发生变化,从而促使个体参与到体育锻炼活动中。

Should Low-Frequency-High-Consumption Enterprises Add Online-to-Offline Platforms?An Empirical Study Using the VAR Model

This study investigates the impact of online-to-offline(O2O)platforms,such as Ele.me and Meituan,on offline sales in low-frequency-high-consumption industries,specifically a mid-to-highend liquor distribution chain.Using data from 77 offline stores in Beijing collected during 2019-2022,the study employs a VAR model to analyze the relationship between offline sales and the use of O2O platforms.The results reveal a long-term equilibrium between the two,with most indicators showing a positive impact of O2O platforms on offline sales.The research provides valuable insights for lowfrequency-high-consumption enterprises in making multi-channel decisions and quantifies the impact of O2O platforms on offline sales.

Effect of stabilizing treatment on microstructure and stress rupture properties of phosphorus microalloyed Inconel 706 alloy

The microstructure and stress rupture properties of Inconel 706 alloy microalloyed with phosphorus are examined under stabilizing and unstabilizing heat treatment conditions.It was found that applying the stabilizing treatment resulted in a 98% increment in the stress rupture life and a 215% increment in the elongation tested at 650℃/690 MPa for the alloy compared to that under the unstabilizing heat treatment condition.The stabilizing treatment led to the precipitation of rod-shaped and needle-shaped n phases at the grain boundaries.Morphologies of γ'-γ" co-precipitates in the grain interior were noncompact form and compact form for the alloy under unstabilizing and stabilizing heat treatment conditions,respectively.Based on the microstructure characterizations,the improvement of stress rupture properties by the stabilizing treatment was attributed to the precipitation of n phases at the grain boundaries,which can hinder cracks initiation and propagation and relieve the stress concentration.

A Processive Arabidopsis Formin Modulates Actin Filament Dynamics in Association with Profilin

Formins are conserved regulators of actin cytoskeletal organization and dynamics that have been impli- cated to be important for cell division and cell polarity. The mechanism by which diverse formins regulate actin dynamics in plants is still not well understood. Using in vitro single-molecule imaging technology, we directly observed that the FH1-FH2 domain of an Arabidopsis thaliana formin, AtFH14, processively at- taches to the barbed end of actin filaments as a dimer and slows their elongation rate by 90%. The attach- ment persistence of FH1-FH2 is concentration dependent. Furthermore, by use of the triple-color total internal reflection fluorescence microscopy, we found that ABP29, a barbed-end capping protein, com- petes with FH1-FH2 at the filament barbed end, where its binding is mutually exclusive with AtFH14. In the presence of different plant profilin isoforms, FH1-FH2 enhances filament elongation rates from about 10 to 42 times. Filaments buckle when FH1-FH2 is anchored specifically to cover slides, further indicating that AtFH 14 moves processively on the elongating barbed end. At high concentration, AtFH 14 bundles actin filaments randomly into antiparallel or parallel spindle-like structures; however, the FH1-FH2-mediated bundles become thinner and longer in the presence of plant profilins. This is the direct demonstration of a processive formin from plants. Our results also illuminate the molecular mechanism of AtFH14 in regulating actin dynamics via association with profilin.

Segregation of Phosphorus and Precipitation of MNP-Type Phosphide at the Grain Boundary of IN706 Superalloy

The effect of phosphorus content and heat treatment on the segregation of phosphorus and precipita- tion of phosphide at the grain boundary of IN706 alloy has been investigated, The phosphide had a stoichiometry of MNP （M = Nb, Ti and N = Ni, Fe, Cr） and an orthorhombic crystal structure. The solubil- ity of phosphorus in the grain matrix of IN706 alloy was determined to be between 0.008% and 0.013%. When soaked at 980 ℃ for 5 min, the phosphide was noticeably precipitated at grain boundaries with the grain size unchanged. When soaked at 980 ℃ for 3 h, the grains grew significantly, but the phos- phide stayed at original grain boundaries which outlined the grain shape before soaking. Soaking at 1060 ℃ for 2 h fully dissolved the pre-existing phosphide but phosphorus atoms were not distributed uni- formly in the grain matrix. When the holding time at 1060 ℃ was extended to 10 h, the phosphorus atoms were distributed uniformly in the grain matrix by sufficient diffusion, and the phosphide could only be formed at grain boundaries during the 980 ℃ soaking. The precipitation of phosphide mainly relied on the phosphorus segregation which was built up by diffusion.

Effect of cooling rate on phosphorus segregation behavior and the corresponding precipitation of γ’’ and γ’ phases in IN718 alloy

Effect of segregation behaviors of P at different cooling rates on the precipitation of γ" and γ' phases and the corresponding strength are investigated. The precipitation of γ" and γ' phases during cooling is sensi-tive to P concentration. With increasing the concentration of Pf the amount of γ" and γ' particles increases after air cooling. With decreasing the cooling rate, the accelerating effect of P on the precipitation of γ" and γ' phases decreased first and then increased, which demonstrates the concentration of P dissolved in the grain interior decreases first and then increases. The different effects of P on γ"and γ' phases with different cooling rates were analyzed by the kinetic characteristic of nonequilibrium grain-boundary seg-regation. The characteristic of nonequilibrium grain-boundary segregation of P in superalloy is further confirmed, and the phenomenon caused by critical cooling rate is captured.

Distribution of Phosphorus and Its Effects on Precipitation Behaviors and Tensile Properties of IN718C Cast Superalloy

The effect of phosphorus on the precipitations of γ",γ’ and δ phases and associated tensile properties in IN718C alloy are investigated in this study.It is revealed that P atoms are dissolved in the grain interior to a relatively high degree and hence influence the precipitation behaviors in the grain interior and improve the tensile strength of IN718C alloy.γ" and γ’ phases did not precipitate in the alloy without P addition during air cooling,while γ" and γ’ phases precipitated in the grain interior during air cooling in the alloys with P addition,and the amounts of γ" and γ’ phases increased with increasing P content.Therefore,the Vickers micro-hardness in the as-cast state increased gradually with increasing P content.In double-aging state,the sizes of γ" and γ’ phases in the alloys with P addition were larger than that in the alloy without P addition,while the sizes were invariable when the P content(wt%)was higher than 0.015.Therefore,the micro-hardness and tensile strength of IN718C alloy treated by double aging increased first and then kept invariable with increasing P content.The precipitations of δ phases both in the grain interior and on grain boundaries were inhibited by P markedly.The inhibitory effect of P on δ phase enhanced gradually with increasing content of P,but the plasticity increased first and then decreased.What is more,the crack tended to propagate into the matrix around the particles(Laves phases and NbC carbides)in the alloys without P addition at the beginning of the tensile fracture,while it tended to propagate along the interfaces between the matrix and those particles in the alloys with P addition,which resulted from the synthetical effect of P on γ" γ’ and δ phases.

Photocrosslinkable Polynorbornene-based Block Copolymers with Enhanced Dielectric and Thermal Properties

Block copolymers poly（endo-N-3,5-bis（trifluoromethyl）biphenyl-norbornene-pyrrolidine）-block-poly（exo-N-（cinnamoyloxyethyl）-7-oxanorborn-5-ene-2,3-dicarboximide）（endo-PTNP-b-exo-PCONBI） and poly（exo-N-3,5-bis（trifluoromethyl）biphenyl-norbornene-pyrrolidine）-block-poly（exo-N-（cinnamoyloxyethyl）-7-oxanorborn-5-ene-2,3-dicarboximide）（exo-PTNP-b-exo-PCONBI） were synthesized by ring-opening metathesis polymerization. The endo- or exoPTNP served as the high dielectric functional chain, and exo-PCONBI acted as the crosslinking segment. The endo-PTNPb-exo-PCONBI, in which endo-PTNP has a high content of trans double bond and adopts isotactic configuration, shows a dielectric constant（？） of 15.5, whereas exo-PTNP-b-exo-PCONBI, in which exo-PTNP has 67% trans double bonds and atactic microstructure, displays relatively low ？ of 7.1. The cinnamate groups in exo-PCONBI were crosslinked to form three-dimensional network by cycloaddition reaction under UV irradiation. Exposed to UV-light for 10 min, the cinnamate group in polymer films has a crosslinking conversion of 36%, as determined by UV-Vis absorption measurements. By photocrosslinking, the polymer film has an increased ？ of 16.6, a dielectric loss of 0.03, an elevated glass-transition temperature of 137 ？C, and an enhanced decomposition temperature of 405 ？C, compared to those of polymer films without irradiation.

Re-recognition of the Effects of Phosphorus and Boron on the γ’’ and γ’ Phases in IN718 Alloy

The effects of P and B on the matrix strength and precipitations of γ’ and γ’’ phases in the grain interior were re-recognized in this study. The combination addition of P and B markedly accelerated the precipitations of γ’ and γ’’ phases and strengthened the matrix of IN718 alloy when air-cooled from high temperature, while made no difference when waterquenched from high temperature. The effect of single addition of P on the precipitations of γ’’ and γ’ phases was the same with that of the combination addition of P and B, while the single addition of B had no effect on the precipitations of the two phases. Therefore, it was P rather than B which accelerated the precipitations of γ’ and γ’’ phases. P could take part in the precipitations of γ’ and γ’’ phases, which was revealed by electrochemical extraction and quantitative analysis of chemical composition. It also revealed that P atoms were dissolved in the c matrix to a relatively high degree at the temperature that γ’ and γ’’ phases began to precipitate, and consequently the precipitations of γ’ and γ’’ phases were accelerated. The first-principle calculation indicated that P decreased the formation enthalpies of γ’ and γ’’ phases when it occupied the Ni lattice sites in the two phases, which explained the effect of P on the γ’ and γ’’ phases.