The variation in microbiota during pit fermentation is the main reason for the distinct characteristics of the 7 types of base Baijiu in jiang-flavor Baijiu(JFB)brewing.However,the specific structure,succession,and fu...The variation in microbiota during pit fermentation is the main reason for the distinct characteristics of the 7 types of base Baijiu in jiang-flavor Baijiu(JFB)brewing.However,the specific structure,succession,and functional differentiation of microbial communities across different fermentation rounds remain unclear.Therefore,this study compared the differences in microbiota structure,environmental factors driving community assembly,and functional differentiations throughout 1–7 rounds(JC1–JC7)of pit fermentation in JFB production.Results showed that Lactobacillus dominated all rounds and complied with declining relative abundance from rounds JC1–JC7.The mould composition was similar in JC3–JC5 while the yeast structure in JC4 was found intermediate between JC3 and JC5.LEf Se analysis unveiled aroma-producing microorganisms as prominent biomarkers in JC1,strong enzyme-producing attributes in JC2,JC6,and JC7 biomarkers,and an enzyme and aroma-producing focus with robust tolerance in JC3–JC5 biomarkers.Acidity mainly regulated the microbial community in the first 4 rounds,with nutrient limitation drove microbial succession from the fifth round onward.Functional predictions underscored enriched amino acid metabolism enzymes in JC6 and JC1,while carbohydrate degradation exhibited predominant enzymatic profiles in JC2,JC6,and JC7.This study laid a foundation for comprehending community composition,succession,and flavor regulatory mechanisms throughout JFB brewing.展开更多
Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we d...Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we demonstrate that TSP perovskite films exhibit a vertically gradient distribution of residual PbI_(2)clusters,which form Schottky heterojunctions with the perovskite,leading to substantial interfacial energy-level mismatches within NiO_(x)-based TSP p-i-n PSCs.These limitations were effectively addressed via a vertical interfacial engineering enabled by dual-interface modification incorporating tin trifluoromethanesulfonate(Sn(OTF)_(2))and 4-Fluorophenylethylamine chloride(F-PEA)at the NiO_(x)/perovskite and perovskite/C60 interfaces,respectively.The functional Sn(OTF)_(2)not only enhances the conductivity of NiO_(x)films but also suppresses ion migration,while inducing the formation of a Pb-Sn mixed perovskite interlayer that precisely regulates the energy level at the NiO_(x)/perovskite interface.Complementally,F-PEA post-treatment effectively converts surface residual PbI_(2)clusters into a 2D perovskite capping layer,which simultaneously passivates surface defects and enhances energy-level alignment at the perovskite/C60 interface.Consequently,the optimized NiO_(x)-based TSP p-i-n PSCs achieve a notable PCE of 25.6%with superior operational stability.This study elucidates the underlying mechanisms limiting the efficiency of TSP p-i-n PSCs,while establishing design principles for these devices targeting 26%efficiency.展开更多
Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular pro...Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular processes,particularly the role of the Ca^(2+)/H^(+)exchanger(CAX),remain unclear.This study aims to elucidate the function of the MdCAX5 gene in relation to BP development.To achieve this,we utilized transient transformation in apple,as well as stable transformation in Arabidopsis and tomato,to measure the mineral content in transgenic plants,thereby validating the function of MdCAX5.The overexpression of the MdCAX5 gene significantly reduced calcium(Ca)content in plants and disrupted the mineral element balance within the plant.Analysis of the MdCAX5 gene promoter revealed that Ca^(2+)can enhance promoter activity,indicating that the MdCAX5 gene can effectively respond to Ca signaling.Transcriptomic analysis of tomato plants stably overexpressing the MdCAX5 gene revealed significant alterations in the expression of genes involved in Ca signal transduction and transport,which in turn impacted the biosynthesis of secondary metabolites and metabolic pathways within the plants.These changes resulted in a reduction in Ca content,imbalanced Ca distribution,increased hydrolase activity,and disrupted cellular structures,including compromised organelles,cellular membranes,and membrane components.These disruptions culminated in the manifestation of Ca deficiency symptoms in the plants.This study provides theoretical insights into the mechanisms underlying the occurrence of apple BP disease.展开更多
Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical properties.The effects of different two-step s...Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical properties.The effects of different two-step solid solution treatments on microstructure andδphase precipitation of Inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was clarified.The precipitates were statistically analyzed by X-ray diffractometry.The results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid solution.The changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron microscopy.An intragranularδphase formed in Inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.展开更多
Tin(Sn)-lead(Pb)mixed halide perovskites have attracted widespread interest due to their wider re-sponse wavelength and lower toxicity than lead halide perovskites,Among the preparation methods,the two-step method mor...Tin(Sn)-lead(Pb)mixed halide perovskites have attracted widespread interest due to their wider re-sponse wavelength and lower toxicity than lead halide perovskites,Among the preparation methods,the two-step method more easily controls the crystallization rate and is suitable for preparing large-area per-ovskite devices.However,the residual low-conductivity iodide layer in the two-step method can affect carrier transport and device stability,and the different crystallization rates of Sn-and Pb-based per-ovskites may result in poor film quality.Therefore,Sn-Pb mixed perovskites are mainly prepared by a one-step method.Herein,a MAPb_(0.5)Sn_(0.5)I_(3)-based self-powered photodetector without a hole transport layer is fabricated by a two-step method.By adjusting the concentration of the ascorbic acid(AA)addi-tive,the final perovskite film exhibited a pure phase without residues,and the optimal device exhibited a high responsivity(0.276 A W^(-1)),large specific detectivity(2.38×10^(12) Jones),and enhanced stability.This enhancement is mainly attributed to the inhibition of Sn2+oxidation,the control of crystal growth,and the sufficient reaction between organic ammonium salts and bottom halides due to the AA-induced pore structure.展开更多
A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,conf...A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,confocal laser microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy,and electrochemical analysis,are employed to characterize MAO coatings at different stages of preparation.MAO has MgO,hydroxyapatite,Ca_(3)(PO_(4))_(2),and Mg2SiO4 phases.Its microstructure of the coating is characterized by"multiple breakdowns,pores within pores",and"repaired blind pores".The porosity and the uniformity of MAO coating first declines in the constant voltage mode,then augments while the discharge phenomenon takes place,and finally decreases in the repair stage.These analyses reveal a four-stage growth pattern for MAO coatings:anodic oxidation stage,micro-arc oxidation stage,breakdown stage,and repairing stage.During anodic oxidation and MAO stages,inward growth prevails,while the breakdown stage sees outward and accelerated growth.Simultaneous inward and outward growth in the repair stage results in a denser,more uniform coating with increased thickness and improved corrosion resistance.展开更多
In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to character...In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to characterize the strength of the backfill. However, the actual working temperature of slopes varies, and natural phenomena such as rainfall and groundwater infiltration commonly result in unsaturated soil conditions, with cracks typically present in cohesive slopes. This study introduces a novel approach for assessing the stability of unsaturated soil stepped slopes under varying temperatures, incorporating the effects of open and vertical cracks. Utilizing the kinematic approach and gravity increase method, we developed a three-dimensional (3D) rotational wedge failure mechanism to simulate slope collapse, enhancing the traditional two-dimensional analyses. We integrated temperature-dependent functions and nonlinear shear strength equations to evaluate the impact of temperature on four typical unsaturated soil types. A particle swarm optimization algorithm was employed to calculate the safety factor, ensuring our method’s accuracy by comparing it with existing studies. The results indicate that considering 3D effects yields a higher safety factor, while cracks reduce slope stability. Each unsaturated soil exhibits a distinctive temperature response curve, highlighting the importance of understanding soil types in the design phase.展开更多
The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microa...The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.展开更多
High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production meth...High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.展开更多
To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations ...To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses.The model incorporates localized electrochemical reactions,oxygen concentration,and homogeneous solution reactions.For improved computational accuracy,the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions.Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions.With increasing electrolyte film thickness(from 10μm to 500μm),corrosion rates at both peaks and troughs decrease progressively,and after 120 hours of simulation,the maximum corrosion rate at the peaks declines from 0.720 mm/a to 0.130 mm/a,and at the troughs from 0.520 mm/a to 0.120 mm/a,with the disparity in corrosion rates diminishing over time.Furthermore,as corrosion progresses,pits propagate deeper into the substrate,exhibiting both vertical penetration and lateral expansion along the passive film interface,ultimately breaching the substrate.This research offers valuable insights into designing corrosion mitigation strategies for stainless steel bellows in marine environments.展开更多
By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to cla...By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.展开更多
Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from...Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from the hexagonal close-packed crystal structure in magnesium alloy puts forwards a great challenge for thin-walled cylindrical components fabrication,especially for extreme structure with the thicknesschanging web and the high thin-wall.In this research,an ZK61 magnesium alloy thin-walled cylindrical component was successfully fabricated by two-step forging,i.e.,the pre-forging and final-forging is mainly used for wed and thin-wall formation,respectively.Microstructure and mechanical properties at the core,middle and margin of the web and the thin-wall of the pre-forged and final-forged components are studied in detail.Due to the large strain-effectiveness and metal flow along the radial direction(RD),the grains of the web are all elongated along RD for the pre-forged component,where an increasingly elongated trend is found from the core to the margin of the wed.A relatively low recrystallized degree occurs during pre-forging,and the web at different positions are all with prismatic and pyramid textures.During finalforging,the microstructures of the web and the thin-wall are almost equiaxed due to the remarkable occurrence of dynamic recrystallization.Similarity,except for few basal texture of the thin-wall,only prismatic and pyramid textures are found for the final-forged component.Compared with the initial billet,an obviously improved mechanical isotropy is achieved during pre-forging,which is well-maintained during final-forging.展开更多
Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of un...Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of unsteady flows.To enhance computational efficiency,we propose the Implicit-Explicit Two-Step Runge-Kutta(IMEX-TSRK)time-stepping discretization methods for unsteady flows,and develop a novel adaptive algorithm that correctly partitions spatial regions to apply implicit or explicit methods.The novel adaptive IMEX-TSRK schemes effectively handle the numerical stiffness of the small grid size and improve computational efficiency.Compared to implicit and explicit Runge-Kutta(RK)schemes,the IMEX-TSRK methods achieve the same order of accuracy with fewer first derivative calculations.Numerical case tests demonstrate that the IMEX-TSRK methods maintain numerical stability while enhancing computational efficiency.Specifically,in high Reynolds number flows,the computational efficiency of the IMEX-TSRK methods surpasses that of explicit RK schemes by more than one order of magnitude,and that of implicit RK schemes several times over.展开更多
The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation...The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.展开更多
Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully ap...Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully applied to geological reconstruction and modeling of surface scenes in open pit mines.However,an integrated modeling method for surface and underground mine sites has not been reported.Methods In this study,we propose an integrated modeling method for open pit mines that fuses a real scene on the surface with an underground geological model.Based on oblique photography,a real-scene model was established on the surface.Based on the surface-stitching method proposed,the upper and lower surfaces and sides of the model were constructed in stages to construct a complete underground three-dimensional geological model,and the aboveground and underground models were registered together to build an integrated open pit mine model.Results The oblique photography method used reconstructed a surface model of an open pit mine using a real scene.The surface-stitching algorithm proposed was compared with the ball-pivoting and Poisson algorithms,and the integrity of the reconstructed model was markedly superior to that of the other two reconstruction methods.In addition,the surface-stitching algorithm was applied to the reconstruction of different formation models and showed good stability and reconstruction efficiency.Finally,the aboveground and underground models were accurately fitted after registration to form an integrated model.Conclusions The proposed method can efficiently establish an integrated open pit model.Based on the integrated model,an open pit auxiliary planning system was designed and realized.It supports the functions of mining planning and output calculation,assists users in mining planning and operation management,and improves production efficiency and management levels.展开更多
Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution env...Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution environments.To solve this problem,a strategy of introducing nano-sized L12 precipitates in CoCrFeNiAlTi HEAs has been proposed in this work.Results demonstrate the pitting corrosion potential can be elevated from 258 mVSCE to 603 mVSCE by increasing the precipitate content to 38 wt.%.Such an improvement in localized corrosion resistance can be attributed to two aspects.Firstly,L12 precipitates tend to be dissolved during the corrosion process,which promotes the heterogeneous nucleation of protective Cr2 O3 due to the rapid deposition of oxides/hydroxides of Al/Ti,and improves the passive film stability due to the Crrich FCC matrix.Secondly,the dissolution kinetic inside the pits can be suppressed on account of the enrichment of Cr element in the FCC matrix,thus inhibiting the pitting growth.In summary,the current work not only reveals the mechanisms of the nano-sized L12 precipitates upon the corrosion behavior,but also provides a strategy for designing corrosion-resistant HEA.展开更多
Ti-based bulk metallic glasses(BMGs)have attracted increasing attention due to their high specific strength.However,a fundamental conflict exists between the specific strength and glass-forming ability(GFA)of Ti-based...Ti-based bulk metallic glasses(BMGs)have attracted increasing attention due to their high specific strength.However,a fundamental conflict exists between the specific strength and glass-forming ability(GFA)of Ti-based BMGs,restricting their commercial applications significantly.In this study,this challenge was addressed by introducing a two-step alloying strategy to mitigate the remarkable density increment effect associated with heavy alloying elements required for enhancing the GFA.Consequently,through two-step alloying with Al and Fe in sequence,simultaneous enhancements in specific strength and GFA were achieved based on a Ti-Zr-Be ternary metallic glass,resulting in the development of a series of centimeter-sized metallic glasses exhibiting ultrahigh-specific strength.Notably,the newly developed(Ti_(45)Zr_(20)Be_(31)A_(l4))_(94)Fe_(6)alloy established a new record for the specific strength of Ti-based BMGs.Along with a critical diameter(D_(c))of 10 mm,it offers the optimal scheme for balancing the specific strength and GFA of Ti-based BMGs.The present results further brighten the application prospects of Ti-based BMGs as lightweight materials.展开更多
In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack init...In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack initiation for 10Cr13Co13Mo5Ni3W1VE ultra-high strength stainless steel(UHSS)has been clarified.PAGB had the highest carbide distribution coefficient and was the main location where pitting preferentially initiated for the UHSS in 3.5 wt.%NaCl solution without strain.It was shown that nanocarbides were the key factor of pitting initiation for the UHSS without strain.However,BGB was the key factor of pitting/microcrack initiation for the UHSS with strain,which was attributed to the high-density dislocations accumulated at BGB and then enhanced the local electrochemical activity of the UHSS surface.The change of the key factor for the pitting initiation in the UHSS was the result of the synergy between strain and corrosion environment.This study provides guidance for designing advanced UHSS with high service stability and safety.展开更多
As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highr...As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highrise buildings,the deep foundation pit support provides the necessary stability for the foundation structure of the building project,and more effectively guarantees the quality of the project.Through the reasonable supporting structure,the deep foundation pit technology can effectively prevent the risk of soil collapse,foundation pit deformation and other risks,and improve the safety factor of the whole construction project.Especially in the high-rise buildings,the deep foundation pit support technology can consolidate the foundation for the long-term stability of the project,and significantly prolong the service life of the building.The continuous development of deep foundation pit construction technology is the inevitable demand of high-rise building construction,and also provides a powerful help for the development of civil engineering industry.Based on this,this paper focuses on the application of deep foundation pit construction technology in civil engineering construction.展开更多
文摘The variation in microbiota during pit fermentation is the main reason for the distinct characteristics of the 7 types of base Baijiu in jiang-flavor Baijiu(JFB)brewing.However,the specific structure,succession,and functional differentiation of microbial communities across different fermentation rounds remain unclear.Therefore,this study compared the differences in microbiota structure,environmental factors driving community assembly,and functional differentiations throughout 1–7 rounds(JC1–JC7)of pit fermentation in JFB production.Results showed that Lactobacillus dominated all rounds and complied with declining relative abundance from rounds JC1–JC7.The mould composition was similar in JC3–JC5 while the yeast structure in JC4 was found intermediate between JC3 and JC5.LEf Se analysis unveiled aroma-producing microorganisms as prominent biomarkers in JC1,strong enzyme-producing attributes in JC2,JC6,and JC7 biomarkers,and an enzyme and aroma-producing focus with robust tolerance in JC3–JC5 biomarkers.Acidity mainly regulated the microbial community in the first 4 rounds,with nutrient limitation drove microbial succession from the fifth round onward.Functional predictions underscored enriched amino acid metabolism enzymes in JC6 and JC1,while carbohydrate degradation exhibited predominant enzymatic profiles in JC2,JC6,and JC7.This study laid a foundation for comprehending community composition,succession,and flavor regulatory mechanisms throughout JFB brewing.
基金financially supported by the National Nature Science Foundation of China (62504130)National Key Research and Development Program of China (2018YFB0704100)+3 种基金the Key university laboratory of highly efficient utilization of solar energy and sustainable development of Guangdong (Y01256331)the Technology Development Project of Henan Province (252102240047)the Pico Center at SUSTech CRF which receives support from the Presidential FundDevelopment and Reform Commission of Shenzhen Municipality
文摘Two-step-processed(TSP)inverted p-i-n perovskite solar cells(PSCs)have demonstrated significant promise in tandem applications.However,the power conversion efficiency(PCE)of TSP p-i-n PSCs rarely exceeds 24%.Here,we demonstrate that TSP perovskite films exhibit a vertically gradient distribution of residual PbI_(2)clusters,which form Schottky heterojunctions with the perovskite,leading to substantial interfacial energy-level mismatches within NiO_(x)-based TSP p-i-n PSCs.These limitations were effectively addressed via a vertical interfacial engineering enabled by dual-interface modification incorporating tin trifluoromethanesulfonate(Sn(OTF)_(2))and 4-Fluorophenylethylamine chloride(F-PEA)at the NiO_(x)/perovskite and perovskite/C60 interfaces,respectively.The functional Sn(OTF)_(2)not only enhances the conductivity of NiO_(x)films but also suppresses ion migration,while inducing the formation of a Pb-Sn mixed perovskite interlayer that precisely regulates the energy level at the NiO_(x)/perovskite interface.Complementally,F-PEA post-treatment effectively converts surface residual PbI_(2)clusters into a 2D perovskite capping layer,which simultaneously passivates surface defects and enhances energy-level alignment at the perovskite/C60 interface.Consequently,the optimized NiO_(x)-based TSP p-i-n PSCs achieve a notable PCE of 25.6%with superior operational stability.This study elucidates the underlying mechanisms limiting the efficiency of TSP p-i-n PSCs,while establishing design principles for these devices targeting 26%efficiency.
基金funded by National Natural Science Foundation of China(Grant No.32300327).
文摘Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular processes,particularly the role of the Ca^(2+)/H^(+)exchanger(CAX),remain unclear.This study aims to elucidate the function of the MdCAX5 gene in relation to BP development.To achieve this,we utilized transient transformation in apple,as well as stable transformation in Arabidopsis and tomato,to measure the mineral content in transgenic plants,thereby validating the function of MdCAX5.The overexpression of the MdCAX5 gene significantly reduced calcium(Ca)content in plants and disrupted the mineral element balance within the plant.Analysis of the MdCAX5 gene promoter revealed that Ca^(2+)can enhance promoter activity,indicating that the MdCAX5 gene can effectively respond to Ca signaling.Transcriptomic analysis of tomato plants stably overexpressing the MdCAX5 gene revealed significant alterations in the expression of genes involved in Ca signal transduction and transport,which in turn impacted the biosynthesis of secondary metabolites and metabolic pathways within the plants.These changes resulted in a reduction in Ca content,imbalanced Ca distribution,increased hydrolase activity,and disrupted cellular structures,including compromised organelles,cellular membranes,and membrane components.These disruptions culminated in the manifestation of Ca deficiency symptoms in the plants.This study provides theoretical insights into the mechanisms underlying the occurrence of apple BP disease.
基金supported by the National Natural Science Foundation of China(Nos.52201203 and 52171107)the Hebei Provincial Natural Science Foundation,China(No.E2021501026)+1 种基金the National Natural Science Foundation of China-Joint Fund of Iron and Steel Research(No.U1960204)the“333”Talent Project of Hebei Province,China(No.B20221001).
文摘Inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical properties.The effects of different two-step solid solution treatments on microstructure andδphase precipitation of Inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was clarified.The precipitates were statistically analyzed by X-ray diffractometry.The results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid solution.The changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron microscopy.An intragranularδphase formed in Inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.
基金supported by the National Natural Science Foun-dation of China(Nos.52025028,52332008,52372214,52202273,and U22A20137)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘Tin(Sn)-lead(Pb)mixed halide perovskites have attracted widespread interest due to their wider re-sponse wavelength and lower toxicity than lead halide perovskites,Among the preparation methods,the two-step method more easily controls the crystallization rate and is suitable for preparing large-area per-ovskite devices.However,the residual low-conductivity iodide layer in the two-step method can affect carrier transport and device stability,and the different crystallization rates of Sn-and Pb-based per-ovskites may result in poor film quality.Therefore,Sn-Pb mixed perovskites are mainly prepared by a one-step method.Herein,a MAPb_(0.5)Sn_(0.5)I_(3)-based self-powered photodetector without a hole transport layer is fabricated by a two-step method.By adjusting the concentration of the ascorbic acid(AA)addi-tive,the final perovskite film exhibited a pure phase without residues,and the optimal device exhibited a high responsivity(0.276 A W^(-1)),large specific detectivity(2.38×10^(12) Jones),and enhanced stability.This enhancement is mainly attributed to the inhibition of Sn2+oxidation,the control of crystal growth,and the sufficient reaction between organic ammonium salts and bottom halides due to the AA-induced pore structure.
文摘A custom micro-arc oxidation(MAO)apparatus is employed to produce coatings under optimized constant voltage–current two-step power supply mode.Various analytical techniques,including scanning electron microscopy,confocal laser microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy,and electrochemical analysis,are employed to characterize MAO coatings at different stages of preparation.MAO has MgO,hydroxyapatite,Ca_(3)(PO_(4))_(2),and Mg2SiO4 phases.Its microstructure of the coating is characterized by"multiple breakdowns,pores within pores",and"repaired blind pores".The porosity and the uniformity of MAO coating first declines in the constant voltage mode,then augments while the discharge phenomenon takes place,and finally decreases in the repair stage.These analyses reveal a four-stage growth pattern for MAO coatings:anodic oxidation stage,micro-arc oxidation stage,breakdown stage,and repairing stage.During anodic oxidation and MAO stages,inward growth prevails,while the breakdown stage sees outward and accelerated growth.Simultaneous inward and outward growth in the repair stage results in a denser,more uniform coating with increased thickness and improved corrosion resistance.
基金Project(51378510) supported by the National Natural Science Foundation of China。
文摘In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to characterize the strength of the backfill. However, the actual working temperature of slopes varies, and natural phenomena such as rainfall and groundwater infiltration commonly result in unsaturated soil conditions, with cracks typically present in cohesive slopes. This study introduces a novel approach for assessing the stability of unsaturated soil stepped slopes under varying temperatures, incorporating the effects of open and vertical cracks. Utilizing the kinematic approach and gravity increase method, we developed a three-dimensional (3D) rotational wedge failure mechanism to simulate slope collapse, enhancing the traditional two-dimensional analyses. We integrated temperature-dependent functions and nonlinear shear strength equations to evaluate the impact of temperature on four typical unsaturated soil types. A particle swarm optimization algorithm was employed to calculate the safety factor, ensuring our method’s accuracy by comparing it with existing studies. The results indicate that considering 3D effects yields a higher safety factor, while cracks reduce slope stability. Each unsaturated soil exhibits a distinctive temperature response curve, highlighting the importance of understanding soil types in the design phase.
基金founded by National Natural Science Foundations of China(Nos.52231003,52201084,and U21A20113)Major Program(JD)of Hubei Province(No.2023BAA019)+1 种基金Natural Science Foundation of Guangdong Province(No.2024A1515011022)Guangdong Province Basic and Applied Basic Research Fund Offshore Wind Power Joint Fund(No.2023B1515250006).
文摘The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.
基金Natural Science Foundation of Shanghai(24ZR1400800)he Natural Science Foundation of China(U23A20685,52073058,91963204)+1 种基金the National Key R&D Program of China(2021YFB3701400)Shanghai Sailing Program(23YF1400200)。
文摘High-performance graphite materials have important roles in aerospace and nuclear reactor technologies because of their outstanding chemical stability and high-temperature performance.Their traditional production method relies on repeated impregnation-carbonization and graphitization,and is plagued by lengthy preparation cycles and high energy consumption.Phase transition-assisted self-pressurized selfsintering technology can rapidly produce high-strength graphite materials,but the fracture strain of the graphite materials produced is poor.To solve this problem,this study used a two-step sintering method to uniformly introduce micro-nano pores into natural graphite-based bulk graphite,achieving improved fracture strain of the samples without reducing their density and mechanical properties.Using natural graphite powder,micron-diamond,and nano-diamond as raw materials,and by precisely controlling the staged pressure release process,the degree of diamond phase transition expansion was effectively regulated.The strain-to-failure of the graphite samples reached 1.2%,a 35%increase compared to samples produced by fullpressure sintering.Meanwhile,their flexural strength exceeded 110 MPa,and their density was over 1.9 g/cm^(3).The process therefore produced both a high strength and a high fracture strain.The interface evolution and toughening mechanism during the two-step sintering process were investigated.It is believed that the micro-nano pores formed have two roles:as stress concentrators they induce yielding by shear and as multi-crack propagation paths they significantly lengthen the crack propagation path.The two-step sintering phase transition strategy introduces pores and provides a new approach for increasing the fracture strain of brittle materials.
基金supported by the National Natural Science Foundation of China(No.52074130)Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality,Ministry of Education,200237 Shanghai,PR China.
文摘To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses.The model incorporates localized electrochemical reactions,oxygen concentration,and homogeneous solution reactions.For improved computational accuracy,the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions.Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions.With increasing electrolyte film thickness(from 10μm to 500μm),corrosion rates at both peaks and troughs decrease progressively,and after 120 hours of simulation,the maximum corrosion rate at the peaks declines from 0.720 mm/a to 0.130 mm/a,and at the troughs from 0.520 mm/a to 0.120 mm/a,with the disparity in corrosion rates diminishing over time.Furthermore,as corrosion progresses,pits propagate deeper into the substrate,exhibiting both vertical penetration and lateral expansion along the passive film interface,ultimately breaching the substrate.This research offers valuable insights into designing corrosion mitigation strategies for stainless steel bellows in marine environments.
基金supported by the National Natural Science Foun-dation of China(No.52401222)Zhejiang Provincial Natural Sci-ence Foundation(LQN25E010011)+2 种基金Ningbo Natural Science Founda-tion(2024J073)Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025"(No.2022Z107)Ningbo Key Research and Development Program(No.2023Z097).
文摘By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.
基金supported by the National Natural Science Foundation of China(No.52405408,No.U21A20131,No.U2037204,No.52422510)the Natural Science Foundation of Hubei Province(No.2023AFB116)+1 种基金the State Key Laboratory of Materials Processing and Die&Mould TechnologyHuazhong University of Science and Technology(No.P2022-005)。
文摘Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from the hexagonal close-packed crystal structure in magnesium alloy puts forwards a great challenge for thin-walled cylindrical components fabrication,especially for extreme structure with the thicknesschanging web and the high thin-wall.In this research,an ZK61 magnesium alloy thin-walled cylindrical component was successfully fabricated by two-step forging,i.e.,the pre-forging and final-forging is mainly used for wed and thin-wall formation,respectively.Microstructure and mechanical properties at the core,middle and margin of the web and the thin-wall of the pre-forged and final-forged components are studied in detail.Due to the large strain-effectiveness and metal flow along the radial direction(RD),the grains of the web are all elongated along RD for the pre-forged component,where an increasingly elongated trend is found from the core to the margin of the wed.A relatively low recrystallized degree occurs during pre-forging,and the web at different positions are all with prismatic and pyramid textures.During finalforging,the microstructures of the web and the thin-wall are almost equiaxed due to the remarkable occurrence of dynamic recrystallization.Similarity,except for few basal texture of the thin-wall,only prismatic and pyramid textures are found for the final-forged component.Compared with the initial billet,an obviously improved mechanical isotropy is achieved during pre-forging,which is well-maintained during final-forging.
基金supported by the National Natural Science Foundation of China(No.92252201)the Fundamental Research Funds for the Central Universitiesthe Academic Excellence Foundation of Beihang University(BUAA)for PhD Students。
文摘Efficient and accurate simulation of unsteady flow presents a significant challenge that needs to be overcome in computational fluid dynamics.Temporal discretization method plays a crucial role in the simulation of unsteady flows.To enhance computational efficiency,we propose the Implicit-Explicit Two-Step Runge-Kutta(IMEX-TSRK)time-stepping discretization methods for unsteady flows,and develop a novel adaptive algorithm that correctly partitions spatial regions to apply implicit or explicit methods.The novel adaptive IMEX-TSRK schemes effectively handle the numerical stiffness of the small grid size and improve computational efficiency.Compared to implicit and explicit Runge-Kutta(RK)schemes,the IMEX-TSRK methods achieve the same order of accuracy with fewer first derivative calculations.Numerical case tests demonstrate that the IMEX-TSRK methods maintain numerical stability while enhancing computational efficiency.Specifically,in high Reynolds number flows,the computational efficiency of the IMEX-TSRK methods surpasses that of explicit RK schemes by more than one order of magnitude,and that of implicit RK schemes several times over.
文摘The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.
基金Supported by Liaoning Province Science and Technology Research Project(2021JH1/10400011)National Natural Science Foundation of China(61971118).
文摘Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully applied to geological reconstruction and modeling of surface scenes in open pit mines.However,an integrated modeling method for surface and underground mine sites has not been reported.Methods In this study,we propose an integrated modeling method for open pit mines that fuses a real scene on the surface with an underground geological model.Based on oblique photography,a real-scene model was established on the surface.Based on the surface-stitching method proposed,the upper and lower surfaces and sides of the model were constructed in stages to construct a complete underground three-dimensional geological model,and the aboveground and underground models were registered together to build an integrated open pit mine model.Results The oblique photography method used reconstructed a surface model of an open pit mine using a real scene.The surface-stitching algorithm proposed was compared with the ball-pivoting and Poisson algorithms,and the integrity of the reconstructed model was markedly superior to that of the other two reconstruction methods.In addition,the surface-stitching algorithm was applied to the reconstruction of different formation models and showed good stability and reconstruction efficiency.Finally,the aboveground and underground models were accurately fitted after registration to form an integrated model.Conclusions The proposed method can efficiently establish an integrated open pit model.Based on the integrated model,an open pit auxiliary planning system was designed and realized.It supports the functions of mining planning and output calculation,assists users in mining planning and operation management,and improves production efficiency and management levels.
基金supported by the National Natural Science Foun-dation of China(Nos.U1908219,52171163)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2)+1 种基金the Applied Basic Research Program of Liaoning Province(grant no.2022JH2/101300005)the Central Guidance for Local Science and Technology Development Funds of Liaoning Province(grant no.2023JH6/100100016).
文摘Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution environments.To solve this problem,a strategy of introducing nano-sized L12 precipitates in CoCrFeNiAlTi HEAs has been proposed in this work.Results demonstrate the pitting corrosion potential can be elevated from 258 mVSCE to 603 mVSCE by increasing the precipitate content to 38 wt.%.Such an improvement in localized corrosion resistance can be attributed to two aspects.Firstly,L12 precipitates tend to be dissolved during the corrosion process,which promotes the heterogeneous nucleation of protective Cr2 O3 due to the rapid deposition of oxides/hydroxides of Al/Ti,and improves the passive film stability due to the Crrich FCC matrix.Secondly,the dissolution kinetic inside the pits can be suppressed on account of the enrichment of Cr element in the FCC matrix,thus inhibiting the pitting growth.In summary,the current work not only reveals the mechanisms of the nano-sized L12 precipitates upon the corrosion behavior,but also provides a strategy for designing corrosion-resistant HEA.
基金supported by the National Natural Science Foundation of China(Nos.52271148 and 51871129).
文摘Ti-based bulk metallic glasses(BMGs)have attracted increasing attention due to their high specific strength.However,a fundamental conflict exists between the specific strength and glass-forming ability(GFA)of Ti-based BMGs,restricting their commercial applications significantly.In this study,this challenge was addressed by introducing a two-step alloying strategy to mitigate the remarkable density increment effect associated with heavy alloying elements required for enhancing the GFA.Consequently,through two-step alloying with Al and Fe in sequence,simultaneous enhancements in specific strength and GFA were achieved based on a Ti-Zr-Be ternary metallic glass,resulting in the development of a series of centimeter-sized metallic glasses exhibiting ultrahigh-specific strength.Notably,the newly developed(Ti_(45)Zr_(20)Be_(31)A_(l4))_(94)Fe_(6)alloy established a new record for the specific strength of Ti-based BMGs.Along with a critical diameter(D_(c))of 10 mm,it offers the optimal scheme for balancing the specific strength and GFA of Ti-based BMGs.The present results further brighten the application prospects of Ti-based BMGs as lightweight materials.
文摘In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack initiation for 10Cr13Co13Mo5Ni3W1VE ultra-high strength stainless steel(UHSS)has been clarified.PAGB had the highest carbide distribution coefficient and was the main location where pitting preferentially initiated for the UHSS in 3.5 wt.%NaCl solution without strain.It was shown that nanocarbides were the key factor of pitting initiation for the UHSS without strain.However,BGB was the key factor of pitting/microcrack initiation for the UHSS with strain,which was attributed to the high-density dislocations accumulated at BGB and then enhanced the local electrochemical activity of the UHSS surface.The change of the key factor for the pitting initiation in the UHSS was the result of the synergy between strain and corrosion environment.This study provides guidance for designing advanced UHSS with high service stability and safety.
文摘As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highrise buildings,the deep foundation pit support provides the necessary stability for the foundation structure of the building project,and more effectively guarantees the quality of the project.Through the reasonable supporting structure,the deep foundation pit technology can effectively prevent the risk of soil collapse,foundation pit deformation and other risks,and improve the safety factor of the whole construction project.Especially in the high-rise buildings,the deep foundation pit support technology can consolidate the foundation for the long-term stability of the project,and significantly prolong the service life of the building.The continuous development of deep foundation pit construction technology is the inevitable demand of high-rise building construction,and also provides a powerful help for the development of civil engineering industry.Based on this,this paper focuses on the application of deep foundation pit construction technology in civil engineering construction.
