In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation ...In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation is used to analyze the influence of various factors(namely,the inner diameter,thickening width,thickening height,thickening spacing,number of laps and adjacent pit axial rotation).The pressure drop and the flow resistance coefficient are the variable parameters for our analysis.The results show that these two parameters are proportional to the thickening height and thickening width,and inversely proportional to the inner diameter,thickening spacing and number of laps.Three different wall thickening structures of the vessel are compared and the pitted thickening vessel is shown to provide the largest structural flow resistance,the annular thickening vessel has the second largest resistance and the helical thickening vessel corresponds to the smallest resistance of the three structures.展开更多
Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud...Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud volcanoes,cinder or scoria cones,tuff rings or cones,pingos,and dirt cones.If the pitted cones identified in southern Utopia Planitia are mud volcanoes,as is speculated,they could be of particular interest due to the fact that mud volcanoes on Earth bring sediments from a depth of meters to kilometers to the surface.In this study,we have investigated the pitted cones near Zhurong rover’s landing site in southern Utopia Planitia,utilizing recent images and digital elevation models obtained from the High Resolution Imaging Camera instrument onboard China’s Tianwen-1 orbiter.By leveraging the high-resolution images and digital elevation models,we have conducted a geometric measurement to distinguish the origin of pitted cones in the vicinity of the Zhurong rover.The morphological characteristics of these pitted cones indicate an explosive mud volcano origin.These explosive mud volcanoes could have formed by the violent eruption of subsurface overpressurized sediments generated from the combined effect of overburden pressure and anomalous high heat flow.The sediments forming the pitted cones in the northern plains could be the remnants of an ancient ocean.With future in-situ observations of these pitted cones,we hope to gain further insights into the sediments of the putative northern ocean,as well as the physical and chemical properties of the Martian subsurface during the formation of the pitted cones.展开更多
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
Coating-free press-hardened steel(CF-PHS)had effectively tackled the challenge of high-temperature oxidation during processing through Cr-Si alloying strategy.However,it is equally essential to investigate its corrosi...Coating-free press-hardened steel(CF-PHS)had effectively tackled the challenge of high-temperature oxidation during processing through Cr-Si alloying strategy.However,it is equally essential to investigate its corrosion resistance and the role of the oxide scale in corrosion environments.The corrosion resistance of CF-PHS with and without oxide scale was comprehensively evaluated by analyzing electrochemical processes and corrosion products,as well as characterizing the corroded oxide scale features,while comparing it with commercial 22MnB5 steel.The results indicate that CF-PHS exhibits superior corrosion resistance compared to 22MnB5 steel and the presence of oxide scale may have a negative influence on short-time corrosion resistance.The ultra-thin oxide scale is unable to effectively and timely mitigate pit propagation during the rapid electrochemical tests.Conversely,during the prolonged corrosion process,the oxide scale can still function as the physical barrier to provide protective effects,making the corrosion process develop more slowly and evenly.展开更多
Effects of thermo-mechanical Laser Shock Peening without Absorbing Coating(LSPwC)on the dual-phase structural evolution and the potential of LSPwC in the corrosion resistance of2Cr13 martensitic stainless steel were i...Effects of thermo-mechanical Laser Shock Peening without Absorbing Coating(LSPwC)on the dual-phase structural evolution and the potential of LSPwC in the corrosion resistance of2Cr13 martensitic stainless steel were investigated.A Neodymium-doped Yttrium Aluminium Garnet(Nd:YAG)laser with a pulse energy of 7.6 J was used for the LSPwC treatment.Microstructural changes were characterized using X-Ray Diffraction(XRD),Transmission Electron Microscopy(TEM)and X-ray Photoelectron Spectroscopy(XPS).Corrosion behavior was evaluated via Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)measurements,and the morphology of corrosion pits was observed using Scanning Electron Microscopy(SEM).Results show that the LSPwC treatment led to an obvious reduction in the corrosion resistance owing to the precipitation of numerous Cr_(8)O_(21),surface roughening and tensile residual stress generated by laser ablation.However,LSPwC with subsequent treatment of slight ablation layer removal brought about 13.5 fold increase in charge transfer resistance and about 83.6% reduction of passive current density,and the significant improvement in the corrosion resistance is attributed to the Cr2O3-rich surface passive film resulting from Cr_(15.58)Fe_(7.42)C_(6)decomposition caused by LSPwC-induced mechanical effects.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
Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450...Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450℃induces significant temperature gradients,resulting in a proliferation of defects.The scarcity of comprehensive research on this crystal’s defects hinders the enhancement of crystal quality.In this study,we employed the chemical etching method to examine the etching effects on Lu_(2)O_(3)crystals under various conditions and to identify the optimal conditions for investi⁃gating the dislocation defects of Lu_(2)O_(3)crystals(mass fraction 70%H3PO4,160℃,15-18 min).The morphologies of dislocation etch pits on the(111)-and(110)-oriented Lu_(2)O_(3)wafers were characterized using microscopy,scanning electron microscopy and atomic force microscopy.This research addresses the gap in understanding Lu_(2)O_(3)line defects and offers guidance for optimizing the crystal growth process and improving crystal quality.展开更多
The corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-d...The corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-deposit corrosion mechanism of aluminum alloys in marine environments containing fungi.Electrochemical impedance spectroscopy,polarization curves,wire beam electrodes,and surface analysis were performed.Results indicate that A.terreus can survive beneath the deposit but the counts of sessile spores decline as the increase of deposit thickness,suggesting a poor biological activity of A.terreus beneath the deposit.Both the uniform corrosion and pitting corrosion are accelerated by A.terreus,while the pitting corrosion of AA7075 alloys beneath the deposit derives from a galvanic cell with a small anode and a large cathode.Deposits have a corrosion inhibition effect on AA7075.However,the galvanic effect caused by the bare and deposit-covered AA specimens is obviously enhanced by A.terreus.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
The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environme...The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environment before and after the transformation.The effect of the inclusion transformation on the pitting corrosion behavior of 316L stainless steel and its intrinsic mechanism was also revealed.Results revealed a gradual transformation of MnO-SiO_(2)inclusions into MnO-Cr_(2)O_(3) within the temperature range of 1373 to 1573 K.MnO-Cr_(2)O_(3)inclusions exhibited minimal dissolution in chloride ion corrosion environments,while MnO-SiO_(2)oxides demonstrated higher electrochemical activity and were more prone to dissolve and form pits.Meanwhile,IHT significantly reduced the dislocation density of stainless steel,rendering it more stable in corrosive environments.X-ray photoelectron spectroscopy peak distributions of the passive films demonstrated that IHT increased the proportion of Cr and Fe oxides and hydroxides in the passive film which improved the stability and corrosion resistance of the steel.展开更多
This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-...This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.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
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
基金supported by the National Natural Science Foundation of China(Grant Nos.51279071,51969009)the Foundation of the Ministry of Education of China for Ph.D candidates in University(Grant No.2013531413002).
文摘In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation is used to analyze the influence of various factors(namely,the inner diameter,thickening width,thickening height,thickening spacing,number of laps and adjacent pit axial rotation).The pressure drop and the flow resistance coefficient are the variable parameters for our analysis.The results show that these two parameters are proportional to the thickening height and thickening width,and inversely proportional to the inner diameter,thickening spacing and number of laps.Three different wall thickening structures of the vessel are compared and the pitted thickening vessel is shown to provide the largest structural flow resistance,the annular thickening vessel has the second largest resistance and the helical thickening vessel corresponds to the smallest resistance of the three structures.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB 41000000)the National Natural Science Foundation of China(Grant Nos.42273041,42272274,41830214)the Pre-research Project on Civil Aerospace Technologies of CNSA(Grant No.D020101).
文摘Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud volcanoes,cinder or scoria cones,tuff rings or cones,pingos,and dirt cones.If the pitted cones identified in southern Utopia Planitia are mud volcanoes,as is speculated,they could be of particular interest due to the fact that mud volcanoes on Earth bring sediments from a depth of meters to kilometers to the surface.In this study,we have investigated the pitted cones near Zhurong rover’s landing site in southern Utopia Planitia,utilizing recent images and digital elevation models obtained from the High Resolution Imaging Camera instrument onboard China’s Tianwen-1 orbiter.By leveraging the high-resolution images and digital elevation models,we have conducted a geometric measurement to distinguish the origin of pitted cones in the vicinity of the Zhurong rover.The morphological characteristics of these pitted cones indicate an explosive mud volcano origin.These explosive mud volcanoes could have formed by the violent eruption of subsurface overpressurized sediments generated from the combined effect of overburden pressure and anomalous high heat flow.The sediments forming the pitted cones in the northern plains could be the remnants of an ancient ocean.With future in-situ observations of these pitted cones,we hope to gain further insights into the sediments of the putative northern ocean,as well as the physical and chemical properties of the Martian subsurface during the formation of the pitted cones.
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supported by the National Natural Science Foundation of China(Grant Nos.U22A20106,52201112,and U22A20173)Fundamental Research Funds for the Central Universities(N25LJ002).
文摘Coating-free press-hardened steel(CF-PHS)had effectively tackled the challenge of high-temperature oxidation during processing through Cr-Si alloying strategy.However,it is equally essential to investigate its corrosion resistance and the role of the oxide scale in corrosion environments.The corrosion resistance of CF-PHS with and without oxide scale was comprehensively evaluated by analyzing electrochemical processes and corrosion products,as well as characterizing the corroded oxide scale features,while comparing it with commercial 22MnB5 steel.The results indicate that CF-PHS exhibits superior corrosion resistance compared to 22MnB5 steel and the presence of oxide scale may have a negative influence on short-time corrosion resistance.The ultra-thin oxide scale is unable to effectively and timely mitigate pit propagation during the rapid electrochemical tests.Conversely,during the prolonged corrosion process,the oxide scale can still function as the physical barrier to provide protective effects,making the corrosion process develop more slowly and evenly.
基金financial support from the National Natural Science Foundation of China(Nos.52305363 and 12104508)the Natural Science Research of Jiangsu Higher Education Institutions in China(No.23KJB460006)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.SJCX24_2388)。
文摘Effects of thermo-mechanical Laser Shock Peening without Absorbing Coating(LSPwC)on the dual-phase structural evolution and the potential of LSPwC in the corrosion resistance of2Cr13 martensitic stainless steel were investigated.A Neodymium-doped Yttrium Aluminium Garnet(Nd:YAG)laser with a pulse energy of 7.6 J was used for the LSPwC treatment.Microstructural changes were characterized using X-Ray Diffraction(XRD),Transmission Electron Microscopy(TEM)and X-ray Photoelectron Spectroscopy(XPS).Corrosion behavior was evaluated via Electrochemical Impedance Spectroscopy(EIS)and Potentiodynamic Polarization(PDP)measurements,and the morphology of corrosion pits was observed using Scanning Electron Microscopy(SEM).Results show that the LSPwC treatment led to an obvious reduction in the corrosion resistance owing to the precipitation of numerous Cr_(8)O_(21),surface roughening and tensile residual stress generated by laser ablation.However,LSPwC with subsequent treatment of slight ablation layer removal brought about 13.5 fold increase in charge transfer resistance and about 83.6% reduction of passive current density,and the significant improvement in the corrosion resistance is attributed to the Cr2O3-rich surface passive film resulting from Cr_(15.58)Fe_(7.42)C_(6)decomposition caused by LSPwC-induced mechanical effects.
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 National Key Research and Development Program of China(2021YFB3601403)National Natural Science Foundation of China(62105181)Taishan Scholar of Shandong Province(tsqn202306014)。
文摘Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450℃induces significant temperature gradients,resulting in a proliferation of defects.The scarcity of comprehensive research on this crystal’s defects hinders the enhancement of crystal quality.In this study,we employed the chemical etching method to examine the etching effects on Lu_(2)O_(3)crystals under various conditions and to identify the optimal conditions for investi⁃gating the dislocation defects of Lu_(2)O_(3)crystals(mass fraction 70%H3PO4,160℃,15-18 min).The morphologies of dislocation etch pits on the(111)-and(110)-oriented Lu_(2)O_(3)wafers were characterized using microscopy,scanning electron microscopy and atomic force microscopy.This research addresses the gap in understanding Lu_(2)O_(3)line defects and offers guidance for optimizing the crystal growth process and improving crystal quality.
基金supported by Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515012146)the National Natural Science Foundation of China(No.52271083).
文摘The corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-deposit corrosion mechanism of aluminum alloys in marine environments containing fungi.Electrochemical impedance spectroscopy,polarization curves,wire beam electrodes,and surface analysis were performed.Results indicate that A.terreus can survive beneath the deposit but the counts of sessile spores decline as the increase of deposit thickness,suggesting a poor biological activity of A.terreus beneath the deposit.Both the uniform corrosion and pitting corrosion are accelerated by A.terreus,while the pitting corrosion of AA7075 alloys beneath the deposit derives from a galvanic cell with a small anode and a large cathode.Deposits have a corrosion inhibition effect on AA7075.However,the galvanic effect caused by the bare and deposit-covered AA specimens is obviously enhanced by A.terreus.
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the support from the National Natural Science Foundation of China(Grant Nos.52074198,52374342,and U21A20113)the Department of Science and Technology of Hubei Province(Grant Nos.2023AFB603 and 2023DJC140).
文摘The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environment before and after the transformation.The effect of the inclusion transformation on the pitting corrosion behavior of 316L stainless steel and its intrinsic mechanism was also revealed.Results revealed a gradual transformation of MnO-SiO_(2)inclusions into MnO-Cr_(2)O_(3) within the temperature range of 1373 to 1573 K.MnO-Cr_(2)O_(3)inclusions exhibited minimal dissolution in chloride ion corrosion environments,while MnO-SiO_(2)oxides demonstrated higher electrochemical activity and were more prone to dissolve and form pits.Meanwhile,IHT significantly reduced the dislocation density of stainless steel,rendering it more stable in corrosive environments.X-ray photoelectron spectroscopy peak distributions of the passive films demonstrated that IHT increased the proportion of Cr and Fe oxides and hydroxides in the passive film which improved the stability and corrosion resistance of the steel.
文摘This study examines the effects of friction stir welding(FSW)and post-weld heat treatment(PWHT)on the grain boundary character distribution and corrosion resistance of cross sectional(top and bottom)regions of nickel-and molybdenum-free high-nitrogen austenitic stainless steel(HNASS).FSW at 400 rpm and 30 mm/min resulted in finer grains(4.18μm)and higher coincident site lattice(CSL)boundaries(32.3%)at the top of the stir zone(SZ)due to dynamic recrystallization(DRX).PWHT at 900℃for 1 h led to grain coarsening(12.91μm the bottom SZ)but enhanced CSL boundaries from 24.6%to 30.2%,improving grain boundary stability.PWHT reduced the kernel average misorientation(KAM)by 14.9%in the SZ-top layer and 20.4%in the SZ-bottom layer,accompanied by a 25%decrease in hardness in the SZ-top layer and 26.7%in the SZ-bottom layer,indicating strain recovery and reduced dislocation density.Potentiodynamic polarization tests(PDP)showed a 18%increase in pitting potential and a 76%reduction in corrosion rate after PWHT.The improvement in corrosion resistance is attributed to the increase inΣ3 twin boundaries,which enhance grain boundary stability and reduce susceptibility to localized corrosion.These findings highlight the role of PWHT in refining the microstructure and strengthening corrosion resistance,making HNASS a promising material for demanding applications.
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 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.
