The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite lo...The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite locally containing podiform chromite, dunite, layered and isotropic gabbro, a sheeted dike complex （SDC）, meta-pillow lavas with chert pods and layers, and tectonically intercalated marble. The SDC is a very important and significant part of the Miaowan ophiolitic sequence, and grades downward into gabbro and ultramafic rocks, and upward into meta-pillow lavas. Some dikes preserve one-way chilled margins, typical of extensional ophiolitic settings, whereas most preserve dou-ble chilled margins, in cases where the chilling direction can be determined. The SDC is mainly com-posed of meta-diabase （dolerite）, meta-plagiogranite, and small amounts of meta-gabbro and ultramafic rocks. LA-ICP-MS zircon dating yields an upper intercept age of 1 026±79 Ma for one meta-plagiogranite, 1 043±23 Ma for a second meta-plagiogranite and I 096±32 Ma for one meta-gabbro at the bottom of the SDC, suggesting formation of the SDC at circa 1 026-1 096 Ma, consistent with the recently determined formation age of the Miaowan ophiolite. Sparse geochemical data on the meta-diabase indicate that the protolith was a sub-alkaline, low-potassium tholeiite similar to mid-ocean ridge basalt （MORB）. The chondrite-normalized rare earth element （REE） patterns of the meta-diabase are generally flat （（La/Yb）N=0.56-0.94）, with a slight depletion in LREE, but no obvious Eu anomalies. Given that the meta-plagiogranites show evidence of formation in a suprasubduction zone environment, we suggest that the basalts were originally island arc tholeiites, perhaps formed in an extensional forearc setting. The geochemistry of the meta-diabase and plagiogranite from the sheeted dikes, together with regional relationships, all agree with the previous interpretations that the Miaowan ophiolite formed in a suprasubduction zone setting.展开更多
As anticipated from studies of ophiolite complexes,direct investigations of the oceanic crust confirm that basaltic dikes are an integral part of the upper 2 km of the oceanic crust.Currently available information sug...As anticipated from studies of ophiolite complexes,direct investigations of the oceanic crust confirm that basaltic dikes are an integral part of the upper 2 km of the oceanic crust.Currently available information suggests展开更多
The modern‘Penrose’definition of ophiolites is based largely on the Troodos complex of Cyprus,which contains a spectacular and well-exposed sheeted dike complex in which dike intrudes dike without intermediate scree...The modern‘Penrose’definition of ophiolites is based largely on the Troodos complex of Cyprus,which contains a spectacular and well-exposed sheeted dike complex in which dike intrudes dike without intermediate screens of展开更多
The Proterozoic Miaowan Ophiolite Complex is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze Craton(Peng et al.,2012).The rocks of this complex consist of,from bottom
The Dabaoshan porphyry Cu deposit(420 kilotons(kt)of Cu@0.36%)is located in South China.The newly discovered Cu orebodies are hosted in the dacite porphyry adjacent to a granodiorite porphyry.The alteration and minera...The Dabaoshan porphyry Cu deposit(420 kilotons(kt)of Cu@0.36%)is located in South China.The newly discovered Cu orebodies are hosted in the dacite porphyry adjacent to a granodiorite porphyry.The alteration and mineralization timing and stages of the porphyry Cu deposit were not well-constrained.In this study,we combine field mapping,petrography,whole-rock geochemistry,hydrothermal rutile U-Pb dating and Cu isotopes to synthesize an ore model at Dabaoshan.In situ hydrothermal rutile U-Pb dating yields an age of 159±13 Ma,which brackets the timing of porphyry Cu mineralization.From top to bottom,the alteration zones in Dabaoshan are divided into quartz-sericite,biotite,chlorite-epidote,and chlorite-sericite subzones.Veins are classified into four stages(Stage 1 to 4)with Stage 4 quartz-sericite-chalcopyrite veins being the main Cu ore-bearing veins.The mineralized dacite porphyry has high SiO_(2),but low MgO,CaO,and Na_(2)O contents.The chalcopyrite hosted in veins exhibitsδ^(65)Cu=values ranging from−1.29‰to 0.51‰.Such copper isotope fractionation is attributed to vapor-brine phase separation,and mixing of fluids from different geochemical reservoirs.The timing of Cu mineralization and hydrothermal alteration support that the Jurassic granodiorite porphyry is an ore-forming intrusion at Dabaoshan.展开更多
In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded s...In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded sheets by covering the tailor-welded sheets with better plastic properties overlapping sheets.At the same time,the interface friction effect between the overlapping and tailor-welded sheets was utilized to control the stress magnitude and further improve the formability and quality of the tailor-welded sheets.In this work,the bulging process of the tailor-welded overlapping sheets was taken as the research object.Aluminum alloy tailor-welded overlapping sheets bulging specimens were studied by a combination of finite element analysis and experimental verification.The results show that the appropriate use of interface friction between tailor-welded and overlapping sheets can improve the formability of tailor-welded sheets and control the flow of weld seam to improve the forming quality.When increasing the interface friction coefficient on the side of tailor-welded sheets with higher strength and decreasing that on the side of tailor-welded sheets with lower strength,the deformation of the tailor-welded sheets are more uniform,the offset of the weld seam is minimal,the limit bulging height is maximal,and the forming quality is optimal.展开更多
Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common c...Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.展开更多
This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the pre...This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the prepared surfaces are placed on top of each other and by rolling with reduction more than 50%,the bonding between layers is established.In this research,the roll bonding process was done at room temperature,without the use of lubricants and with a 70%thickness reduction.Then,the final thickness of the Ag/Al bilayer sheet reached 350μm by several stages of cold rolling.Before cold rolling,it should be noted that to decrease the hardness created due to plastic deformation,the roll-bonded samples were subjected to annealing heat treatment at 400℃for 90 min.Thus,the final samples were annealed at 200,300 and 400℃for 90 min and cooled in a furnace to examine the annealing temperature effects.The uniaxial tensile and microhardness tests measured mechanical properties.Also,to investigate the fracture mechanism,the fractography of the cross-section was examined by scanning electron microscope(SEM).To evaluate the formability of Ag/Al bilayer sheets,forming limit curves were obtained experimentally through the Nakazima test.The resistance of composites to failure due to cracking was also investigated by fracture toughness.The results showed that annealing increases the elongation and formability of the Ag/Al bilayer sheet while reduces the ultimate tensile strength and fracture toughness.However,the changing trend is not the same at different temperatures,and according to the results,the most significant effect is obtained at 300℃and aluminum layers.It was also determined that by increasing annealing temperature,the fracture mechanism from shear ductile with small and shallow dimples becomes ductile with deep cavities.展开更多
The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sh...The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.展开更多
Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ...Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ductility of Fe–Ga alloy. However, the im-pact of trace Tb doping on the microstructure and magnetostriction of Fe–Ga thin sheets is an open question. In this paper, the effects oftrace Tb addition on the secondary recrystallization and magnetostriction of Fe–Ga thin sheets are systematically studied by comparing thecharacteristics evolution of precipitation, texture, and nanoinclusions. The results indicate that trace Tb addition accelerates the secondaryrecrystallization of Goss texture due to the combined action of the bimodal size distributed precipitates, smaller grains, and more HEGBsin primary recrystallization. After quenching at 900℃, the magnetostriction value in 0.07 at %Tb-doped Fe_(81)Ga_(19) thin sheets increases by 30% to that of Fe_(81)Ga_(19) thin sheets. The increase in magnetostriction is attributed to the decrease in the number of Tb-rich precipitates andthe higher density of the nanometer-sized modified-D0_(3) inclusions induced by the dissolving of trace Tb elements after quenching. Theseresults demonstrate a simple and efficient approach for preparing Fe–Ga thin sheets with a large magnetostrictive coefficient by a combin-ation of trace RE element addition and conventional rolling method.展开更多
This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cy...This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cybersecurity,and cross-border data flows create additional compliance challenges.In terms of recognition,the subjectivity of traditional valuation methods,the lack of active markets,and the rapid depreciation of data value caused by technological iteration hinder reliable measurement.With respect to disclosure,organizations face a dilemma between transparency and confidentiality.Collectively,these issues exacerbate audit risks.It is therefore imperative to establish an appropriate legal,accounting,and auditing framework to mitigate such risks and remove barriers to the proper recognition of data assets on balance sheets.展开更多
This review summarizes recent progress in the study of impinging-jet dynamics and atomization,with a focus on liquid sheet formation,instability mechanisms,and the influence of key parameters such as fluid properties,...This review summarizes recent progress in the study of impinging-jet dynamics and atomization,with a focus on liquid sheet formation,instability mechanisms,and the influence of key parameters such as fluid properties,Weber number,and Reynolds number.Special attention is given to atomization behaviors under high pressure and external perturbations.Representative experimental and numerical approaches are introduced,and critical findings under complex conditions are highlighted.In addition,practical applications of impinging-jet technology in aerospace propulsion,biomedical devices,and energy science are discussed.This review aims to serve as a concise reference for researchers interested in multiphase flow dynamics and engineering applications of impinging jets.展开更多
Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including ...Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including as-cast(AC),as-rolled(AR)and as-extruded(AE),was systematically investigated and compared under the online heating rolling(O-LHR)process with a single-pass reduction of 50% at 250℃.The results show that both AC and AR sheets exhibit severe edge cracking behavior after the O-LHR.Among them,the AR sheet exhibits the severest edge cracking behavior on the rolling plane(RD-TD)and longitudinal section(RD-ND),which is attributed to the strong basal texture and extremely uneven microstructure with shear bands.While no visible edge crack appears in the AE rolled sheet,which is mainly related to the tilted texture and the more dynamic recrystallization during rolling process.Moreover,it is also found that the micro-cracks of the AC rolled sheet are mainly generated in the local fine-grained area and the twins where recrystallization occurs.In the AR rolled sheet,micro-cracks mainly develop inside the shear bands.Meanwhile,the micro-crack initiation mechanism of AC and AR rolled sheets was also discussed.展开更多
The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0....The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0.5 to 100 mm/min.Based on the stress−strain curves and the dynamic material model,the hot processing map was established,which demonstrates that the power dissipation factor(η)is the most sensitive to strain rate at 400℃via absorption of dislocations.At 400℃,sample at 0.5 mm/min possessesηof 0.89 because of its lower kernel average misorientation(KAM)value of 0.51,while sample at 100 mm/min possessesηof 0.46 with a higher KAM value of 1.147.In addition,the flow stress presents a slight decrease of 25.94 MPa at 10 mm/min compared to that at 100 mm/min and 100℃.The reasons are twofold:a special~34°texture component during 100℃-100 mm/min favoring the activation of basal slip,and dynamic recrystallization(DRX)also providing softening effect to some extent by absorbing dislocations.Difference in activation of basal slip among twin laminas during 100℃-100 mm/min results in deformation inhomogeneity within the grains,which generates stress that helps matrix grains tilt to a direction favorable to basal slip,forming the special~34°texture component.展开更多
Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and qu...Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.展开更多
During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile str...During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.展开更多
In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referr...In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referred to as M1 and M2 samples,respectively).The creep tests were performed on these samples at the temperature range of 150-200℃,and the stress level range of 50-100 MPa.The creep properties and fracture behavior of AZ31 extruded sheets with mixed-grain microstructures were studied.Results showed that the creep properties of the M2 sample always outperformed that of the M1 sample and M1 and M2 samples’creep was dominated by dislocation movement.The creep rate of M2 samples(1.5×10^(-7)±1.1×10^(-10) s^(-1))is an order of magnitude lower than that of M1 samples(4.8×10^(-6)±8.1×10^(-10) s^(-1))at 200℃under 50 MPa The high activity of basal slip and softening mechanism in the M1 sample significantly accelerated creep,resulting in a relatively high creep rate.Moreover,the stress concentration within the M1 sample caused by deformation incompatibility,increased the initiation and propagation of voids,ultimately leading to fracture and poorer creep performance.However,the numerous<10µm fine grains surrounding deformed coarse grains in the M2 sample facilitated better coordination of deformation through dislocation slip,effectively slowing down the initiation of voids during the creep process.Meanwhile,the strain was uniformly distributed within each grain,mitigating stress concentration,inhibiting voids propagation,and contributing to the superior creep resistance of the M2 sample.展开更多
The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic s...The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.展开更多
BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive...BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.展开更多
Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending st...Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending strains using electron backscatter diffraction and optical microscopy.The results show that the Mg–Er–Zr extruded sheet has excellent bending properties,with a failure bending strain of 39.3%,bending yield strength,and ultimate bending strength of 75.1 MPa and 250.5 MPa,respectively.The exceptional bending properties of the Mg–Er–Zr extruded sheets are primarily due to their fine grain size and the formation of rare-earth(RE)textures resulting from Er addition.Specifically,the in-grain misorientation axes(IGMA)and the twinning behaviors in various regions of the specimen during bending were thoroughly analyzed.Due to the polarity of the tensile twins and their low activation stress,a significant number of tensile twins are activated in the compression zone to regulate plastic deformation.The addition of Er weakens the basal texture of the sheet and reduces the critical resolved shear stress difference between non-basal slip and basal slip.Consequently,in the tensile zone,the basal and non-basal slips co-operate to coordinate the plastic deformation,effectively impeding crack initiation and propagation,and thereby enhancing the bending toughness of the Mg–Er–Zr sheet.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 91014002, 40821061, 41272242)Ministry of Education of China (No. B07039)+2 种基金the Open Foundation of Ministry of Education (No. TGRC201024)the Post-doctoral Science Foundation (No. 20100471203)the Ministry of Land and Resources Foundation (No. 1212010670104)
文摘The Miaowan （庙湾） ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite locally containing podiform chromite, dunite, layered and isotropic gabbro, a sheeted dike complex （SDC）, meta-pillow lavas with chert pods and layers, and tectonically intercalated marble. The SDC is a very important and significant part of the Miaowan ophiolitic sequence, and grades downward into gabbro and ultramafic rocks, and upward into meta-pillow lavas. Some dikes preserve one-way chilled margins, typical of extensional ophiolitic settings, whereas most preserve dou-ble chilled margins, in cases where the chilling direction can be determined. The SDC is mainly com-posed of meta-diabase （dolerite）, meta-plagiogranite, and small amounts of meta-gabbro and ultramafic rocks. LA-ICP-MS zircon dating yields an upper intercept age of 1 026±79 Ma for one meta-plagiogranite, 1 043±23 Ma for a second meta-plagiogranite and I 096±32 Ma for one meta-gabbro at the bottom of the SDC, suggesting formation of the SDC at circa 1 026-1 096 Ma, consistent with the recently determined formation age of the Miaowan ophiolite. Sparse geochemical data on the meta-diabase indicate that the protolith was a sub-alkaline, low-potassium tholeiite similar to mid-ocean ridge basalt （MORB）. The chondrite-normalized rare earth element （REE） patterns of the meta-diabase are generally flat （（La/Yb）N=0.56-0.94）, with a slight depletion in LREE, but no obvious Eu anomalies. Given that the meta-plagiogranites show evidence of formation in a suprasubduction zone environment, we suggest that the basalts were originally island arc tholeiites, perhaps formed in an extensional forearc setting. The geochemistry of the meta-diabase and plagiogranite from the sheeted dikes, together with regional relationships, all agree with the previous interpretations that the Miaowan ophiolite formed in a suprasubduction zone setting.
文摘As anticipated from studies of ophiolite complexes,direct investigations of the oceanic crust confirm that basaltic dikes are an integral part of the upper 2 km of the oceanic crust.Currently available information suggests
文摘The modern‘Penrose’definition of ophiolites is based largely on the Troodos complex of Cyprus,which contains a spectacular and well-exposed sheeted dike complex in which dike intrudes dike without intermediate screens of
文摘The Proterozoic Miaowan Ophiolite Complex is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze Craton(Peng et al.,2012).The rocks of this complex consist of,from bottom
基金funded by the China Geological Survey(Grant Nos.DD20190379,DD20221695 and DD20221684)a collaboration program(2019-2024)between the Institute of Mineral Resources(Chinese Academy of Geological Sciences)and the Guangdong Dabaoshan Mining Co.,Ltd.
文摘The Dabaoshan porphyry Cu deposit(420 kilotons(kt)of Cu@0.36%)is located in South China.The newly discovered Cu orebodies are hosted in the dacite porphyry adjacent to a granodiorite porphyry.The alteration and mineralization timing and stages of the porphyry Cu deposit were not well-constrained.In this study,we combine field mapping,petrography,whole-rock geochemistry,hydrothermal rutile U-Pb dating and Cu isotopes to synthesize an ore model at Dabaoshan.In situ hydrothermal rutile U-Pb dating yields an age of 159±13 Ma,which brackets the timing of porphyry Cu mineralization.From top to bottom,the alteration zones in Dabaoshan are divided into quartz-sericite,biotite,chlorite-epidote,and chlorite-sericite subzones.Veins are classified into four stages(Stage 1 to 4)with Stage 4 quartz-sericite-chalcopyrite veins being the main Cu ore-bearing veins.The mineralized dacite porphyry has high SiO_(2),but low MgO,CaO,and Na_(2)O contents.The chalcopyrite hosted in veins exhibitsδ^(65)Cu=values ranging from−1.29‰to 0.51‰.Such copper isotope fractionation is attributed to vapor-brine phase separation,and mixing of fluids from different geochemical reservoirs.The timing of Cu mineralization and hydrothermal alteration support that the Jurassic granodiorite porphyry is an ore-forming intrusion at Dabaoshan.
基金Funded by the National Natural Science Foundation of China(Nos.52075347,51575364)and the Natural Science Foundation of Liaoning Provincial(No.2022-MS-295)。
文摘In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded sheets by covering the tailor-welded sheets with better plastic properties overlapping sheets.At the same time,the interface friction effect between the overlapping and tailor-welded sheets was utilized to control the stress magnitude and further improve the formability and quality of the tailor-welded sheets.In this work,the bulging process of the tailor-welded overlapping sheets was taken as the research object.Aluminum alloy tailor-welded overlapping sheets bulging specimens were studied by a combination of finite element analysis and experimental verification.The results show that the appropriate use of interface friction between tailor-welded and overlapping sheets can improve the formability of tailor-welded sheets and control the flow of weld seam to improve the forming quality.When increasing the interface friction coefficient on the side of tailor-welded sheets with higher strength and decreasing that on the side of tailor-welded sheets with lower strength,the deformation of the tailor-welded sheets are more uniform,the offset of the weld seam is minimal,the limit bulging height is maximal,and the forming quality is optimal.
基金Supported by the National Natural Science Foundation of China(Nos.52192693,52192690,52371270,U20A20327)the National Key Research and Development Program of China(Nos.2021YFC2803400).
文摘Ice-breaking methods have become increasingly significant with the ongoing development of the polar regions.Among many ice-breaking methods,ice-breaking that utilizes a moving load is unique compared with the common collision or impact methods.A moving load can generate flexural-gravity waves(FGWs),under the influence of which the ice sheet undergoes deformation and may even experience structural damage.Moving loads can be divided into above-ice loads and underwater loads.For the above-ice loads,we discuss the characteristics of the FGWs generated by a moving load acting on a complete ice sheet,an ice sheet with a crack,and an ice sheet with a lead of open water.For underwater loads,we discuss the influence on the ice-breaking characteristics of FGWs of the mode of motion,the geometrical features,and the trajectory of motion of the load.In addition to discussing the status of current research and the technical challenges of ice-breaking by moving loads,this paper also looks ahead to future research prospects and presents some preliminary ideas for consideration.
基金Project(4013311)supported by the National Science Foundation of Iran(INSF)。
文摘This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the prepared surfaces are placed on top of each other and by rolling with reduction more than 50%,the bonding between layers is established.In this research,the roll bonding process was done at room temperature,without the use of lubricants and with a 70%thickness reduction.Then,the final thickness of the Ag/Al bilayer sheet reached 350μm by several stages of cold rolling.Before cold rolling,it should be noted that to decrease the hardness created due to plastic deformation,the roll-bonded samples were subjected to annealing heat treatment at 400℃for 90 min.Thus,the final samples were annealed at 200,300 and 400℃for 90 min and cooled in a furnace to examine the annealing temperature effects.The uniaxial tensile and microhardness tests measured mechanical properties.Also,to investigate the fracture mechanism,the fractography of the cross-section was examined by scanning electron microscope(SEM).To evaluate the formability of Ag/Al bilayer sheets,forming limit curves were obtained experimentally through the Nakazima test.The resistance of composites to failure due to cracking was also investigated by fracture toughness.The results showed that annealing increases the elongation and formability of the Ag/Al bilayer sheet while reduces the ultimate tensile strength and fracture toughness.However,the changing trend is not the same at different temperatures,and according to the results,the most significant effect is obtained at 300℃and aluminum layers.It was also determined that by increasing annealing temperature,the fracture mechanism from shear ductile with small and shallow dimples becomes ductile with deep cavities.
基金the National Natural Science Founda-tion of China(NSFC,Grant No.42174181)and the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDJ-SSW-DQC010).
文摘The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.
基金financially supported by the National Natural Science Foundation of China (No. 52004164)the Funding Program of Science and Technology Department of Liaoning Province, China (No. 2023-MSLH-249)the Funding Program of Education Department of Liaoning P rovince, China (No. LMGD2023018)。
文摘Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ductility of Fe–Ga alloy. However, the im-pact of trace Tb doping on the microstructure and magnetostriction of Fe–Ga thin sheets is an open question. In this paper, the effects oftrace Tb addition on the secondary recrystallization and magnetostriction of Fe–Ga thin sheets are systematically studied by comparing thecharacteristics evolution of precipitation, texture, and nanoinclusions. The results indicate that trace Tb addition accelerates the secondaryrecrystallization of Goss texture due to the combined action of the bimodal size distributed precipitates, smaller grains, and more HEGBsin primary recrystallization. After quenching at 900℃, the magnetostriction value in 0.07 at %Tb-doped Fe_(81)Ga_(19) thin sheets increases by 30% to that of Fe_(81)Ga_(19) thin sheets. The increase in magnetostriction is attributed to the decrease in the number of Tb-rich precipitates andthe higher density of the nanometer-sized modified-D0_(3) inclusions induced by the dissolving of trace Tb elements after quenching. Theseresults demonstrate a simple and efficient approach for preparing Fe–Ga thin sheets with a large magnetostrictive coefficient by a combin-ation of trace RE element addition and conventional rolling method.
文摘This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cybersecurity,and cross-border data flows create additional compliance challenges.In terms of recognition,the subjectivity of traditional valuation methods,the lack of active markets,and the rapid depreciation of data value caused by technological iteration hinder reliable measurement.With respect to disclosure,organizations face a dilemma between transparency and confidentiality.Collectively,these issues exacerbate audit risks.It is therefore imperative to establish an appropriate legal,accounting,and auditing framework to mitigate such risks and remove barriers to the proper recognition of data assets on balance sheets.
基金supported by the National Natural Science Foundation of China(Grant Nos.U23B6009 and 12272050).
文摘This review summarizes recent progress in the study of impinging-jet dynamics and atomization,with a focus on liquid sheet formation,instability mechanisms,and the influence of key parameters such as fluid properties,Weber number,and Reynolds number.Special attention is given to atomization behaviors under high pressure and external perturbations.Representative experimental and numerical approaches are introduced,and critical findings under complex conditions are highlighted.In addition,practical applications of impinging-jet technology in aerospace propulsion,biomedical devices,and energy science are discussed.This review aims to serve as a concise reference for researchers interested in multiphase flow dynamics and engineering applications of impinging jets.
基金financially supported by the National Natural Science Foundation of China(Nos.52071036,U2037601)the Guangdong Major Project of Basic and Applied Basic Research,China(No.2020B0301030006)+1 种基金the Independent Research Project of State Key Laboratory of Mechanical Transmissions,China(Nos.SKLMT-ZZKT-2022Z01,SKLMT-ZZKT-2022M12)the Chongqing Science and Technology Commission,China(No.CSTB2022TIAD-KPX0021)。
文摘Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including as-cast(AC),as-rolled(AR)and as-extruded(AE),was systematically investigated and compared under the online heating rolling(O-LHR)process with a single-pass reduction of 50% at 250℃.The results show that both AC and AR sheets exhibit severe edge cracking behavior after the O-LHR.Among them,the AR sheet exhibits the severest edge cracking behavior on the rolling plane(RD-TD)and longitudinal section(RD-ND),which is attributed to the strong basal texture and extremely uneven microstructure with shear bands.While no visible edge crack appears in the AE rolled sheet,which is mainly related to the tilted texture and the more dynamic recrystallization during rolling process.Moreover,it is also found that the micro-cracks of the AC rolled sheet are mainly generated in the local fine-grained area and the twins where recrystallization occurs.In the AR rolled sheet,micro-cracks mainly develop inside the shear bands.Meanwhile,the micro-crack initiation mechanism of AC and AR rolled sheets was also discussed.
基金Project(52005362) supported by the National Natural Science Foundation of ChinaProjects(202303021221005,202303021211045) supported by the Natural Science Foundation of Shanxi Province,China+1 种基金Project(202402003) supported by the Patent Commercialization Program of Shanxi Province,ChinaProject supported by the Key Research and Development Plan of Xinzhou City,China。
文摘The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0.5 to 100 mm/min.Based on the stress−strain curves and the dynamic material model,the hot processing map was established,which demonstrates that the power dissipation factor(η)is the most sensitive to strain rate at 400℃via absorption of dislocations.At 400℃,sample at 0.5 mm/min possessesηof 0.89 because of its lower kernel average misorientation(KAM)value of 0.51,while sample at 100 mm/min possessesηof 0.46 with a higher KAM value of 1.147.In addition,the flow stress presents a slight decrease of 25.94 MPa at 10 mm/min compared to that at 100 mm/min and 100℃.The reasons are twofold:a special~34°texture component during 100℃-100 mm/min favoring the activation of basal slip,and dynamic recrystallization(DRX)also providing softening effect to some extent by absorbing dislocations.Difference in activation of basal slip among twin laminas during 100℃-100 mm/min results in deformation inhomogeneity within the grains,which generates stress that helps matrix grains tilt to a direction favorable to basal slip,forming the special~34°texture component.
基金supported by the following funding sources:Ministry of Education-Singapore MOE2019-T2-2-094 Ministry of Education-Singapore Tier I R-397-000-327-114 ScienceTechnology Project of Jiangsu Province(Grant No.BZ2022056)Biomedical and Health Technology Platform,National University of Singapore(Suzhou)Research Institute.
文摘Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.
基金sponsored by Natural Science Research Project of Anhui Educational Committee(GrantNo.2022AH050810),NationalNatural Science Foundation of China(GrantNos.42402276,41972286,42072309,42102329)State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University(No.PBSKL2023A1)the Open Fund of National Center for International Research on Deep Earth Drilling and Resource Development(No.DEDRD-2023-02).
文摘During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.
基金supported by the National Natural Science Foundation of China(52474419,52374395)Natural Science Foundation of Shanxi Province(20210302123135,202303021221143)+3 种基金Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province(202104021301022,202204021301009)Central Government Guided Local Science and Technology development projects(YDZJSX20231B003,YDZJSX2021A010)The Ministry of Science and Higher Education of the Russian Federation for financial support under the Megagrant(No.075-15-2022-1133)the National Research Foundation(NRF)grant funded by the Ministry of Science and ICT(2015R1A2A1A01006795)of Korea through the Research Institute of Advanced.
文摘In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referred to as M1 and M2 samples,respectively).The creep tests were performed on these samples at the temperature range of 150-200℃,and the stress level range of 50-100 MPa.The creep properties and fracture behavior of AZ31 extruded sheets with mixed-grain microstructures were studied.Results showed that the creep properties of the M2 sample always outperformed that of the M1 sample and M1 and M2 samples’creep was dominated by dislocation movement.The creep rate of M2 samples(1.5×10^(-7)±1.1×10^(-10) s^(-1))is an order of magnitude lower than that of M1 samples(4.8×10^(-6)±8.1×10^(-10) s^(-1))at 200℃under 50 MPa The high activity of basal slip and softening mechanism in the M1 sample significantly accelerated creep,resulting in a relatively high creep rate.Moreover,the stress concentration within the M1 sample caused by deformation incompatibility,increased the initiation and propagation of voids,ultimately leading to fracture and poorer creep performance.However,the numerous<10µm fine grains surrounding deformed coarse grains in the M2 sample facilitated better coordination of deformation through dislocation slip,effectively slowing down the initiation of voids during the creep process.Meanwhile,the strain was uniformly distributed within each grain,mitigating stress concentration,inhibiting voids propagation,and contributing to the superior creep resistance of the M2 sample.
基金the support of the Key Research and Development Program of Shaanxi Province,China(No.2021GXLH-Z-049)。
文摘The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.
基金Supported by National Key Research and Development Program of China,No.2021YFA1100600 and No.2022YFA1104400.
文摘BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.
基金supported by the National Natural Science Foundation of China(No.52071037).
文摘Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending strains using electron backscatter diffraction and optical microscopy.The results show that the Mg–Er–Zr extruded sheet has excellent bending properties,with a failure bending strain of 39.3%,bending yield strength,and ultimate bending strength of 75.1 MPa and 250.5 MPa,respectively.The exceptional bending properties of the Mg–Er–Zr extruded sheets are primarily due to their fine grain size and the formation of rare-earth(RE)textures resulting from Er addition.Specifically,the in-grain misorientation axes(IGMA)and the twinning behaviors in various regions of the specimen during bending were thoroughly analyzed.Due to the polarity of the tensile twins and their low activation stress,a significant number of tensile twins are activated in the compression zone to regulate plastic deformation.The addition of Er weakens the basal texture of the sheet and reduces the critical resolved shear stress difference between non-basal slip and basal slip.Consequently,in the tensile zone,the basal and non-basal slips co-operate to coordinate the plastic deformation,effectively impeding crack initiation and propagation,and thereby enhancing the bending toughness of the Mg–Er–Zr sheet.
