High temperature performance of magnesium alloys can be tailored by either grain size or precipitates in the grain interior.In this study,exceptional creep resistance was successfully acquired in a RE-free cast Mg-Al-...High temperature performance of magnesium alloys can be tailored by either grain size or precipitates in the grain interior.In this study,exceptional creep resistance was successfully acquired in a RE-free cast Mg-Al-Ca-Ti(AC51Ti)alloy.Microalloying of Ti(0.01 wt.%)has been found to be beneficial to the improvement of the tensile creep resistance in a RE-free cast Mg-5Al-0.35Mn-(1Ca)(AC51)alloy,showing a low state creep rate(SCR)of 2.70×10^(−9)s^(−1)at 200℃/50 MPa,which is even better than that of many reported RE-containing Mg alloys.The presence of trace Ti contributes to the substantial refinement and more uniform distribution of Al_(2)Ca precipitates in the matrix.At the same time,the microalloying of Ti improves the solubility of Al and Ca in the matrix.It is reasonable to believe that the microalloying of Ti induced re-organization of Al_(2)Ca precipitates,dissolved a larger amount of Al and Ca atoms into magnesium lattice,and increased the possibility of interaction between GB/dislocations and precipitates,which strongly correlates with the high temperature properties.The creep strengthening mechanisms primarily attributed to both second phase strengthening and solid solution strengthening were separately proposed based on the experimental investigations.展开更多
This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical sl...This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.展开更多
Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of composites.However,the relationship between hetero-deformation induced(HDI)strain hardening and dislocation activity ca...Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of composites.However,the relationship between hetero-deformation induced(HDI)strain hardening and dislocation activity caused by heterogeneous structures in the magnesium matrix composite remains unclear.In this study,a dual-heterogeneous TiC/AZ61 composite exhibits significantly improved plastic elongation(PEL)by nearly one time compared to uniform FG composite,meanwhile maintaining a high strength(UTS:417 MPa).This is because more severe deformation inhomogeneity in heterogeneous structure leads to more geometrically necessary dislocations(GNDs)accumulation and stronger HDI stress,resulting in higher HDI hardening compared to FG and CG composites.During the early stage of plastic deformation,the pile-up types of GND in the FG zone and CG zone are significantly different.GNDs tend to form substructures in the FG zone instead of the CG zone.They only accumulate at grain boundaries of the CG region,thereby leading to obviously increased back stress in the CG region.In the late deformation stage,the elevated HDI stress activates the new〈c+a〉dislocations in the CG region,resulting in dislocation entanglements and even the formation of substructures,further driving the high hardening in the heterogeneous composite.However,For CG composite,〈c+a〉dislocations are not activated even under large plastic strains,and only〈a〉dislocations pile up at grain boundaries and twin boundaries.Our work provides an in-depth understanding of dislocation variation and HDI hardening in heterogeneous magnesium-based composites.展开更多
This study aims to achieve a synergy of strength and ductility in magnesium-based nanocomposite materials through the design of a dual-heterostructure. Utilizing ball milling and hot extrusion, a nano-TiC/AZ61 composi...This study aims to achieve a synergy of strength and ductility in magnesium-based nanocomposite materials through the design of a dual-heterostructure. Utilizing ball milling and hot extrusion, a nano-TiC/AZ61 composite featuring particle-rare coarse grain (CG) and particle-rich fine grain (FG) zones was successfully fabricated. Experimental results demonstrated that compared with the homogeneous structure, the dual-heterostructure composite achieved a significant increase in elongation by 116 % and a remarkable 165 % improvement in the strength-ductility product (SDP), while maintaining a high ultimate tensile strength (UTS) of 417±4 MPa. This substantial performance enhancement is primarily attributed to the additional strain hardening induced by hetero-deformation-induced (HDI) strain hardening and crack-blunting capabilities, as elucidated by microstructural characterization and crystal plasticity finite element modeling (CPFEM). Notably, the strain hardening contribution from the CG zones at the early stage of deformation (≤ 45 % of total plastic deformation amount) is minimal but increases significantly during the subsequent deformation stages. The dislocation increment rate in CG zones (219 %) is observed to be more than double that in FG zones (95 %), attributed to the large grain size and low dislocation density in CG zones, which provide more space for dislocation storage. In addition, the aggravated deformation inhomogeneity as deformation progresses leads to an increase in geometrically necessary dislocations (GNDs) generation near the heterogeneous interface, thereby enhancing HDI hardening. Fracture mechanism analysis indicated that the cracks mainly initiate in the FG region and are effectively blunted upon their propagation to the CG region, necessitating increased energy consumption and indicating higher fracture toughness for the dual-heterostructure composites. This study validates the effectiveness of the dual-heterostructure design in magnesium-based composites, providing a novel understanding of the deformation mechanism through both experimental analysis and CPFEM, paving the way for the development of high-performance, lightweight structural materials.展开更多
Objective:To identify promising biomarkers for the pathogenesis of major depressive disorder(MDD).Methods:Microarray chips of MDD patients,including the GSE98793,GSE52790,and GSE39653 datasets,were obtained from the G...Objective:To identify promising biomarkers for the pathogenesis of major depressive disorder(MDD).Methods:Microarray chips of MDD patients,including the GSE98793,GSE52790,and GSE39653 datasets,were obtained from the Gene Expression Omnibus database.The biological processes and pathways related to MDD were investigated using the GO and KEGG pathway tools.Weighted gene coexpression network analysis was conducted to identify modules related to MDD.The hub genes associated with MDD were obtained via protein-protein interaction analysis.Finally,the expression of hub genes in the hippocampal tissues of depression-like rats was detected by reverse transcription-polymerase chain reaction and Western blotting.Results:A total of 658 differentially expressed genes were identified from the Gene Expression Omnibus datasets;thus,these genes and the GSE98793 dataset were used to conduct weighted gene coexpression network analysis.A total of 244 module-related genes were identified and these genes were highly correlated with MDD.These genes were involved in the Ras signaling pathway,regulation of the actin cytoskeleton,and axon guidance according to the KEGG analysis.Hub genes,including MAPK14,SOCS1,TLR2,PTK2B,and GRB2,were obtained via protein-protein interaction analysis.All these hub genes showed better diagnostic efficiency in the GSE52790,GSE39653,and GSE98793 datasets.In vivo experiments revealed that compared with those in control rats,SOCS1 and MAPK14 expression was significantly decreased;while GRB2,TLR2,and PTK2B expression was increased in the hippocampi of depression-like rats.Conclusions:Our study demonstrates that GRB2,TLR2,SOCS1,PTK2B,and MAPK14 are promising hub genes,and targeting these five genes may be an effective treatment strategy for MDD.展开更多
A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µ...A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µm.There were 1609 tension twins identified including adequate(51%)anomalous twins(Schmid factor m<0).Twin variant selection exhibited almost no grain size or strain rate effects.Most twin variants(74%)correlated well with the proposed normalized Schmid factor(mnor).The Luster-Morris parameter(m′)values failed to correlate with the twin transmission,while 96%of transmitted pairs exhibited large mnor or normalized m′(m′nor)values.Twin transmission occurred more frequently at lower grain boundary misorientation angles(10°-30°).The active anomalous twins correlated well with m of the prismatic slip.The present work provided a statistical perspective that,the mnor and m′nor can correlate the anomalous twinning rather than m and m′.The local condition also played a critical role in anomalous twinning behavior.展开更多
Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the ...Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the high frequency of lightning;on the other hand,the vulnerability of people in developing countries is also an influencing factor.Through case analysis and summary,this paper expounds on lightning injury s mechanism and clinical manifestations.It points out that lightning injury is mainly related to heart problems and the impact on the nervous system,rather than burns,which usually cause fewer consequences.Medical treatment needs to pay attention to the order and principles of treatment.Implementing CPR and auxiliary AED is the most effective way to save lives.Attention should be paid to the practical and effective treatment and nursing of lightning stroke sequelae.Finally,combined with the situation of lightning casualties in China,the existing problems are put forward during the process of early treatment,post-hospital treatment,and nursing observation,which provides an objective basis for the cognition of the scientific nature of the lightning injury.展开更多
Furfuryl ethyl ether(FEE)is considered as one of the most important candidates for biofuels due to its high-octane number.However,it is still challenging to produce FEE via the biomass-based route under mild condition...Furfuryl ethyl ether(FEE)is considered as one of the most important candidates for biofuels due to its high-octane number.However,it is still challenging to produce FEE via the biomass-based route under mild conditions.Here,we developed a photoinduced catalytic transfer hydrogenation(CTH)process for the efficient production of FEE through the reduction etherification of furfural(FF)using Na_(4)W_(10)O_(32)(NaDT),Pd/C,and ethanol as the hydrogen atom transfer(HAT)catalyst,hydrogenation catalyst,and the H donor,respectively.Notably,the introduction of brominated benzene(PhBr)as an additive significantly promoted the yield of FEE to 92.7%.A series of experiments and characterization results indicated that the attachment and detachment of Br atoms on Pd/C catalyst surface effectively regulate the balance between H^(+)sites and Pd sites in the NaDT+Pd/C catalytic system.The balance facilitates the preferential acetalization of FF catalyzed by H^(+)sites,followed by hydrogenation to efficiently produce FEE catalyzed by Pd sites.This photoinduced CTH process exhibits good stability and recyclability as well as universality for the transformation of various organic substrates under mild conditions.展开更多
This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the s...This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the sparrow search algorithm(SSA).Eleven features were extracted from the microstructures(e.g.,grain size(GS),maximum pole intensity(I_(max)),degree of texture dispersion(μ),radius of maximum pole position(r),and angle of maximum pole position(A)),mechanical properties(e.g.,tensile yield strength(TYS),ultimate tensile strength(UTS),elongation-to-failure(EL),and strength difference(∆S))and test conditions(e.g.,sheet thickness(t)and punch speed(v))in the data collected from the literature and experiments.Pearson correlation coefficient and exhaustive screening methods identified ten key features(not including UTS)as the final inputs,and they enhanced the prediction accuracy of Index Erichsen(IE),which served as the model’s output.The newly developed SSA-XGBoost model exhibited an improved prediction performance,with a goodness of fit(R^(2))of 0.91 compared with traditional machine learning models.A new dataset(four samples)was prepared to validate the reliability and generalization capacity of this model,and below 5%errors were observed between predicted and experimental IE values.Based on this result,the quantitative relationship between the key features and IE values was established via Shapley additive explanation method and XGBoost feature importance analysis.I_(max),TYS,EL,r,GS,andΔS showed a crucial influence on the IE of 10 input features.This work offers a reliable and accurate tool for the prediction of the stretch formability of AZ31 magnesium alloys and provides insights into the development of high-formable magnesium alloys.展开更多
The grain-scale tension-compression(T-C)asymmetric slip behavior and geometrically necessary dislocation(GND)density in an aged and twin-free Mg-10Y sheet were statistically studied using slip trace analysis and elect...The grain-scale tension-compression(T-C)asymmetric slip behavior and geometrically necessary dislocation(GND)density in an aged and twin-free Mg-10Y sheet were statistically studied using slip trace analysis and electron backscatter diffraction(EBSD)analysis.A significantly asymmetric slip activity,i.e.,higher tensile slip activity and proportion of non-basal slip,was manifested.Prismatic〈a〉(37.1%)and basal〈a〉(27.6%)slips dominated the tensile deformation,followed by pyramidalⅡ〈c+a〉slip(20.0%).While during compression,basal〈a〉slip(61.9%)was the most active slip mode,and only 6.9% pyramidalⅡ〈c+a〉slip was observed.The critical resolved shear stress(CRSS)ratio was estimated based on~800 sets of the identified slip traces,which suggested that the CRSS_(pyrⅡ)/CRSS_(bas)for compression was~3 times than that of tension.The pyramidalⅡ〈c+a〉slip was more active when the slip plane was under tension than under compression,which was consistent with the calculated asymmetric CRSS_(pyrⅡ)/CRSS_(bas).The activity of multiple slip,cross slip and slip transfer,as well as the GND density were also T-C asymmetric.This work thoughtfully demonstrated the T-C asymmetric slip behavior and plastic heterogeneity in Mg alloys which was believed to be responsible for the macroscopic T-C asymmetry when twinning was absent.The present statistical results are valuable for validating and/or facilitating crystal plasticity simulations.展开更多
The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the m...The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the material’s strength.The formation mechanism of the dual-precipitates was investigated,and the evolution of precipitate orientation was confirmed.A combined SEM,EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation.The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region.Subsequently,the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates.The TAD sample containing dual-precipitates exhibited a 99.1%increase in TYS,equivalent to an increase of 108 MPa,compared to unregulated samples A.According to Orowan calculations,the theoretical strength increment from the three strengthening mechanisms was 113 MPa,closely matching the experimental increment of 108 MPa.Notably,the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.展开更多
AIM:To investigate the association between pre-miR- 146a C/G polymorphism and gastric cancer risk. METHODS:We performed a hospital-based,case-control study using polymerase chain reaction-restriction fragment length p...AIM:To investigate the association between pre-miR- 146a C/G polymorphism and gastric cancer risk. METHODS:We performed a hospital-based,case-control study using polymerase chain reaction-restriction fragment length polymorphism method in 608 individuals(304 gastric cancer patients and 304 age and sex matched cancer-free controls).RESULTS:The frequencies of pre-miR-146a C/G genotypes in the case group were significantly different from those in the control groups(P=0.037).Compared with CC genotype carriers,subjects with the variant genotypes(GC+GG)had a 58%increased risk of gastric cancer(adjusted OR=1.58,95%CI:1.11-2.20,P= 0.009).Moreover,a higher gastric cancer risk was especially evident in younger individuals aged≤58 years, nonsmokers,and males(adjusted OR=1.76,95%CI: 1.08-2.87,P=0.024;adjusted OR=1.55,95%CI: 1.06-2.28,P=0.025;adjusted OR=1.53,95%CI: 1.04-2.27,P=0.033;respectively). CONCLUSION:Pre-miR-146a C/G polymorphism might be associated with an elevated risk of gastric cancer in Chinese population.展开更多
AIM： To evaluate the impact of the ITGA2 gene polymorphism on gastric cancer risk. METHODS： A hospital-based case-control study was conducted, including 307 gastric cancer patients and 307 age- and gender-matched co...AIM： To evaluate the impact of the ITGA2 gene polymorphism on gastric cancer risk. METHODS： A hospital-based case-control study was conducted, including 307 gastric cancer patients and 307 age- and gender-matched control subjects. The genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism assay. RESULTS： The frequencies of the wild and variant genotypes in cases were significantly different from those of controls （P = 0.019）. Compared with individuals with the wild genotype CC, subjects with the variant genotypes （CT ＋ IT） had a significantly higher risk of gastric cancer （adjusted odds ratio = 1.57, 95% CI = 1.13-2.17, P = 0.007）. In stratified analyses, the elevated gastric cancer risk was especially evident in older individuals aged 〉 58 years, nonsmokers and rural subjects. Further analyses revealed that the variant genotypes were associated with poor tumor differentiation and adjacent organ invasion in the sub-analysis of gastric cancer patients. CONCLUSION： The ITGA2 gene C807T polymorphism may be associated with an increased risk of gastric cancer, differentiation and invasion of gastric cancer.展开更多
The as-cast and as-extruded Mg–9Li–1Al–xCa alloys(x=0,0.2;wt%)were prepared by a simple alloying process followed by hot extrusion with an extrusion ratio of 28.2.The microstructures of the as-cast and as-extruded...The as-cast and as-extruded Mg–9Li–1Al–xCa alloys(x=0,0.2;wt%)were prepared by a simple alloying process followed by hot extrusion with an extrusion ratio of 28.2.The microstructures of the as-cast and as-extruded Mg–9Li–1Al–xCa alloys were observed to investigate the effect of calcium(Ca)element on the Mg–9Li–1Al(LA91)alloy,and the crystallographic calculations between Al_(2)Ca and the matrix(α-Mg andβ-Li phases)were examined on the basis of the edge-to-edge matching model.The experimental results indicate that the addition of 0.2 wt%Ca into LA91 alloy reduce the size of theα-Mg phases in the as-cast alloy and that ofβ-Li phases in the as-extruded alloy due to the Al_(2)Ca particles distributed inside the matrix.Crystallographic calculation results suggested that there is a good crystallographic matching between the matrix and Al_(2)Ca,which confirmed that Al_(2)Ca particles can act as a heterogeneous nucleation site for bothα-Mg andβ-Li phases and were effective grain refiners for LA91 alloy.展开更多
The existing engineering empirical life analysis models are not capable of considering the constitutive behavior of materials under contact loads;as a consequence,these methods may not be accurate to predict fatigue l...The existing engineering empirical life analysis models are not capable of considering the constitutive behavior of materials under contact loads;as a consequence,these methods may not be accurate to predict fatigue lives of roll-ing bearings.In addition,the contact stress of bearing in operation is cyclically pulsating,it also means that the bear-ing undergo non-symmetrical fatigue loadings.Since the mean stress has great effects on fatigue life,in this work,a novel fatigue life prediction model based on the modified SWT mean stress correction is proposed as a basis of which to estimate the fatigue life of rolling bearings,in which,takes sensitivity of materials and mean stress into account.A compensation factor is introduced to overcome the inaccurate predictions resulted from the Smith,Watson,and Topper(SWT)model that considers the mean stress effect and sensitivity while assuming the sensitivity coefficient of all materials to be 0.5.Moreover,the validation of the model is finalized by several practical experimental data and the comparison to the conventional SWT model.The results show the better performance of the proposed model,especially in the accuracy than the existing SWT model.This research will shed light on a new direction for predicting the fatigue life of rolling bearings.展开更多
基金funded by the National Natural Science Foundation of China(Grant numbers U22A20187,52374405,52371177).
文摘High temperature performance of magnesium alloys can be tailored by either grain size or precipitates in the grain interior.In this study,exceptional creep resistance was successfully acquired in a RE-free cast Mg-Al-Ca-Ti(AC51Ti)alloy.Microalloying of Ti(0.01 wt.%)has been found to be beneficial to the improvement of the tensile creep resistance in a RE-free cast Mg-5Al-0.35Mn-(1Ca)(AC51)alloy,showing a low state creep rate(SCR)of 2.70×10^(−9)s^(−1)at 200℃/50 MPa,which is even better than that of many reported RE-containing Mg alloys.The presence of trace Ti contributes to the substantial refinement and more uniform distribution of Al_(2)Ca precipitates in the matrix.At the same time,the microalloying of Ti improves the solubility of Al and Ca in the matrix.It is reasonable to believe that the microalloying of Ti induced re-organization of Al_(2)Ca precipitates,dissolved a larger amount of Al and Ca atoms into magnesium lattice,and increased the possibility of interaction between GB/dislocations and precipitates,which strongly correlates with the high temperature properties.The creep strengthening mechanisms primarily attributed to both second phase strengthening and solid solution strengthening were separately proposed based on the experimental investigations.
基金supported by the National Natural Science Foundation of China(No.52171125)the Sichuan Science and Technology Program(No.2024NSFSC0193).
文摘This work investigated the effects of grain size(GS)on individual slip mode activities and the corresponding Hall-Petch coefficients in a rolled basal-textured pure Mg sheet under uniaxial tension using statistical slip trace analysis and electron backscatter diffraction.The studied regions covered a total of 1150 grains,in which 136 sets of slip traces were identified and analyzed in detail.The basalslip always dominated the deformation,whose frequencies decreased(from 81.0%to 62.5%)with increasing GS(from 10 to 85μm).The prismaticslip activity increased from 10.8%(10μm)to 27.5%(85μm),while that for pyramidal II<c+a>slip was almost constant.Critical resolved shear stress(CRSS)ratios were estimated based on the identified slip activity statistics,and then the Hall-Petch coefficients(k)of individual slip modes were calculated.The k value for prismaticslip(194 MPa·μm^(1/2))was lower than that for pyramidal II<c+a>slip(309 MPa·μm^(1/2)),which implies that pyramidal II<c+a>slip was more GS sensitive.Twinning activity exhibited a positive correlation with GS,though it remained limited partly due to the unfavorable loading direction.The macroscopic Hall-Petch relationship was divided into two regions,i.e.,the k value(753 MPa·μm^(1/2))for the coarse-grain region(30-85μm)was significantly larger than that(118 MPa·μm^(1/2))of the fine-grain region(10-30μm),which could be attributed to the transition of predominant deformation mechanisms from slip to slip combined twinning with increasing GS.This work provides detailed and quantitative experimental data of the GS effects on individual slip activities of Mg and provides new insights into the Hall-Petch relationship for individual slip modes.
基金support from the National Natural Science Foundation of China(No:52061040)China Postdoctoral Science Foundation(No:2021M692512)+1 种基金Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province(No:2023CL01)Open Projects of Key Laboratory of Advanced Technologies of Materials,Ministry of Education China,Southwest Jiaotong University(No:KLATM202003).
文摘Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of composites.However,the relationship between hetero-deformation induced(HDI)strain hardening and dislocation activity caused by heterogeneous structures in the magnesium matrix composite remains unclear.In this study,a dual-heterogeneous TiC/AZ61 composite exhibits significantly improved plastic elongation(PEL)by nearly one time compared to uniform FG composite,meanwhile maintaining a high strength(UTS:417 MPa).This is because more severe deformation inhomogeneity in heterogeneous structure leads to more geometrically necessary dislocations(GNDs)accumulation and stronger HDI stress,resulting in higher HDI hardening compared to FG and CG composites.During the early stage of plastic deformation,the pile-up types of GND in the FG zone and CG zone are significantly different.GNDs tend to form substructures in the FG zone instead of the CG zone.They only accumulate at grain boundaries of the CG region,thereby leading to obviously increased back stress in the CG region.In the late deformation stage,the elevated HDI stress activates the new〈c+a〉dislocations in the CG region,resulting in dislocation entanglements and even the formation of substructures,further driving the high hardening in the heterogeneous composite.However,For CG composite,〈c+a〉dislocations are not activated even under large plastic strains,and only〈a〉dislocations pile up at grain boundaries and twin boundaries.Our work provides an in-depth understanding of dislocation variation and HDI hardening in heterogeneous magnesium-based composites.
基金support from the China Scholarship Council(No.202107000038)support from the National Natural Science Foundation of China(Nos.52004227,52061040,and 12222209)the China Postdoctoral Science Foundation(No:2021M692512).
文摘This study aims to achieve a synergy of strength and ductility in magnesium-based nanocomposite materials through the design of a dual-heterostructure. Utilizing ball milling and hot extrusion, a nano-TiC/AZ61 composite featuring particle-rare coarse grain (CG) and particle-rich fine grain (FG) zones was successfully fabricated. Experimental results demonstrated that compared with the homogeneous structure, the dual-heterostructure composite achieved a significant increase in elongation by 116 % and a remarkable 165 % improvement in the strength-ductility product (SDP), while maintaining a high ultimate tensile strength (UTS) of 417±4 MPa. This substantial performance enhancement is primarily attributed to the additional strain hardening induced by hetero-deformation-induced (HDI) strain hardening and crack-blunting capabilities, as elucidated by microstructural characterization and crystal plasticity finite element modeling (CPFEM). Notably, the strain hardening contribution from the CG zones at the early stage of deformation (≤ 45 % of total plastic deformation amount) is minimal but increases significantly during the subsequent deformation stages. The dislocation increment rate in CG zones (219 %) is observed to be more than double that in FG zones (95 %), attributed to the large grain size and low dislocation density in CG zones, which provide more space for dislocation storage. In addition, the aggravated deformation inhomogeneity as deformation progresses leads to an increase in geometrically necessary dislocations (GNDs) generation near the heterogeneous interface, thereby enhancing HDI hardening. Fracture mechanism analysis indicated that the cracks mainly initiate in the FG region and are effectively blunted upon their propagation to the CG region, necessitating increased energy consumption and indicating higher fracture toughness for the dual-heterostructure composites. This study validates the effectiveness of the dual-heterostructure design in magnesium-based composites, providing a novel understanding of the deformation mechanism through both experimental analysis and CPFEM, paving the way for the development of high-performance, lightweight structural materials.
基金supported by the National Natural Science Foundation of China(No.81774281 and No.82474303)the Natural Science Foundation of Hunan Province(2023JJ30888)the leading national joint discipline of Chinese and Western medicines to the Chinese Medicine Department,Xiangya Hospital,CSU.
文摘Objective:To identify promising biomarkers for the pathogenesis of major depressive disorder(MDD).Methods:Microarray chips of MDD patients,including the GSE98793,GSE52790,and GSE39653 datasets,were obtained from the Gene Expression Omnibus database.The biological processes and pathways related to MDD were investigated using the GO and KEGG pathway tools.Weighted gene coexpression network analysis was conducted to identify modules related to MDD.The hub genes associated with MDD were obtained via protein-protein interaction analysis.Finally,the expression of hub genes in the hippocampal tissues of depression-like rats was detected by reverse transcription-polymerase chain reaction and Western blotting.Results:A total of 658 differentially expressed genes were identified from the Gene Expression Omnibus datasets;thus,these genes and the GSE98793 dataset were used to conduct weighted gene coexpression network analysis.A total of 244 module-related genes were identified and these genes were highly correlated with MDD.These genes were involved in the Ras signaling pathway,regulation of the actin cytoskeleton,and axon guidance according to the KEGG analysis.Hub genes,including MAPK14,SOCS1,TLR2,PTK2B,and GRB2,were obtained via protein-protein interaction analysis.All these hub genes showed better diagnostic efficiency in the GSE52790,GSE39653,and GSE98793 datasets.In vivo experiments revealed that compared with those in control rats,SOCS1 and MAPK14 expression was significantly decreased;while GRB2,TLR2,and PTK2B expression was increased in the hippocampi of depression-like rats.Conclusions:Our study demonstrates that GRB2,TLR2,SOCS1,PTK2B,and MAPK14 are promising hub genes,and targeting these five genes may be an effective treatment strategy for MDD.
基金supported by the National Natural Science Foundation of China(Nos.52171125,52071178)。
文摘A statistical analysis of the twinning behavior in a basal-textured Mg sheet under hard orientation loading was performed at strain rates of 1×10^(-5) and 1×10^(-1) s^(-1) with grain sizes of 70 and 20µm.There were 1609 tension twins identified including adequate(51%)anomalous twins(Schmid factor m<0).Twin variant selection exhibited almost no grain size or strain rate effects.Most twin variants(74%)correlated well with the proposed normalized Schmid factor(mnor).The Luster-Morris parameter(m′)values failed to correlate with the twin transmission,while 96%of transmitted pairs exhibited large mnor or normalized m′(m′nor)values.Twin transmission occurred more frequently at lower grain boundary misorientation angles(10°-30°).The active anomalous twins correlated well with m of the prismatic slip.The present work provided a statistical perspective that,the mnor and m′nor can correlate the anomalous twinning rather than m and m′.The local condition also played a critical role in anomalous twinning behavior.
文摘Currently,the number of lightning casualties and casualty rates have significantly reduced in developed countries,but there has been no significant reduction in developing countries.On the one hand,this is due to the high frequency of lightning;on the other hand,the vulnerability of people in developing countries is also an influencing factor.Through case analysis and summary,this paper expounds on lightning injury s mechanism and clinical manifestations.It points out that lightning injury is mainly related to heart problems and the impact on the nervous system,rather than burns,which usually cause fewer consequences.Medical treatment needs to pay attention to the order and principles of treatment.Implementing CPR and auxiliary AED is the most effective way to save lives.Attention should be paid to the practical and effective treatment and nursing of lightning stroke sequelae.Finally,combined with the situation of lightning casualties in China,the existing problems are put forward during the process of early treatment,post-hospital treatment,and nursing observation,which provides an objective basis for the cognition of the scientific nature of the lightning injury.
文摘Furfuryl ethyl ether(FEE)is considered as one of the most important candidates for biofuels due to its high-octane number.However,it is still challenging to produce FEE via the biomass-based route under mild conditions.Here,we developed a photoinduced catalytic transfer hydrogenation(CTH)process for the efficient production of FEE through the reduction etherification of furfural(FF)using Na_(4)W_(10)O_(32)(NaDT),Pd/C,and ethanol as the hydrogen atom transfer(HAT)catalyst,hydrogenation catalyst,and the H donor,respectively.Notably,the introduction of brominated benzene(PhBr)as an additive significantly promoted the yield of FEE to 92.7%.A series of experiments and characterization results indicated that the attachment and detachment of Br atoms on Pd/C catalyst surface effectively regulate the balance between H^(+)sites and Pd sites in the NaDT+Pd/C catalytic system.The balance facilitates the preferential acetalization of FF catalyzed by H^(+)sites,followed by hydrogenation to efficiently produce FEE catalyzed by Pd sites.This photoinduced CTH process exhibits good stability and recyclability as well as universality for the transformation of various organic substrates under mild conditions.
基金funded by the National Natural Science Foundation of China(No.52204407)the Natural Science Foundation of Jiangsu Province,China(No.BK20220595)+1 种基金the China Postdoctoral Science Foundation(No.2022M 723689)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(No.SJCX23_1913).
文摘This study involved the development of an interpretable prediction framework to access the stretch formability of AZ31 magnesium alloys through the combination of the extreme gradient boosting(XGBoost)model with the sparrow search algorithm(SSA).Eleven features were extracted from the microstructures(e.g.,grain size(GS),maximum pole intensity(I_(max)),degree of texture dispersion(μ),radius of maximum pole position(r),and angle of maximum pole position(A)),mechanical properties(e.g.,tensile yield strength(TYS),ultimate tensile strength(UTS),elongation-to-failure(EL),and strength difference(∆S))and test conditions(e.g.,sheet thickness(t)and punch speed(v))in the data collected from the literature and experiments.Pearson correlation coefficient and exhaustive screening methods identified ten key features(not including UTS)as the final inputs,and they enhanced the prediction accuracy of Index Erichsen(IE),which served as the model’s output.The newly developed SSA-XGBoost model exhibited an improved prediction performance,with a goodness of fit(R^(2))of 0.91 compared with traditional machine learning models.A new dataset(four samples)was prepared to validate the reliability and generalization capacity of this model,and below 5%errors were observed between predicted and experimental IE values.Based on this result,the quantitative relationship between the key features and IE values was established via Shapley additive explanation method and XGBoost feature importance analysis.I_(max),TYS,EL,r,GS,andΔS showed a crucial influence on the IE of 10 input features.This work offers a reliable and accurate tool for the prediction of the stretch formability of AZ31 magnesium alloys and provides insights into the development of high-formable magnesium alloys.
基金supported by the National Natural Science Foundation of China(No.52171125)the Sichuan Science and Technology Program(No.2024NSFSC0193)。
文摘The grain-scale tension-compression(T-C)asymmetric slip behavior and geometrically necessary dislocation(GND)density in an aged and twin-free Mg-10Y sheet were statistically studied using slip trace analysis and electron backscatter diffraction(EBSD)analysis.A significantly asymmetric slip activity,i.e.,higher tensile slip activity and proportion of non-basal slip,was manifested.Prismatic〈a〉(37.1%)and basal〈a〉(27.6%)slips dominated the tensile deformation,followed by pyramidalⅡ〈c+a〉slip(20.0%).While during compression,basal〈a〉slip(61.9%)was the most active slip mode,and only 6.9% pyramidalⅡ〈c+a〉slip was observed.The critical resolved shear stress(CRSS)ratio was estimated based on~800 sets of the identified slip traces,which suggested that the CRSS_(pyrⅡ)/CRSS_(bas)for compression was~3 times than that of tension.The pyramidalⅡ〈c+a〉slip was more active when the slip plane was under tension than under compression,which was consistent with the calculated asymmetric CRSS_(pyrⅡ)/CRSS_(bas).The activity of multiple slip,cross slip and slip transfer,as well as the GND density were also T-C asymmetric.This work thoughtfully demonstrated the T-C asymmetric slip behavior and plastic heterogeneity in Mg alloys which was believed to be responsible for the macroscopic T-C asymmetry when twinning was absent.The present statistical results are valuable for validating and/or facilitating crystal plasticity simulations.
基金National Natural Science Foundation of China(52374405)Joint Innovaion Fund Project of Lanzhou Jiaotong University and Corresponding Supporting University(LH2024018)State Key Laboratory Open Project(Q110824Q02001)。
文摘The orientation of precipitates was regulated by an improved twinning-aging-detwinning(TAD)process in Mg-Sn sheets.A structure with specific proportions of dual-precipitates was regulated,significantly enhancing the material’s strength.The formation mechanism of the dual-precipitates was investigated,and the evolution of precipitate orientation was confirmed.A combined SEM,EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation.The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region.Subsequently,the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates.The TAD sample containing dual-precipitates exhibited a 99.1%increase in TYS,equivalent to an increase of 108 MPa,compared to unregulated samples A.According to Orowan calculations,the theoretical strength increment from the three strengthening mechanisms was 113 MPa,closely matching the experimental increment of 108 MPa.Notably,the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.
基金Supported by National Natural Science Foundation of China,No.30873099Natural Science Foundation of Jiangsu Province,No.BK2006525+1 种基金No.08KJB320004"333 Project"and"Qinglan Project"Funds for the Young Academic Leader of Jiangsu Province to Wang B
文摘AIM:To investigate the association between pre-miR- 146a C/G polymorphism and gastric cancer risk. METHODS:We performed a hospital-based,case-control study using polymerase chain reaction-restriction fragment length polymorphism method in 608 individuals(304 gastric cancer patients and 304 age and sex matched cancer-free controls).RESULTS:The frequencies of pre-miR-146a C/G genotypes in the case group were significantly different from those in the control groups(P=0.037).Compared with CC genotype carriers,subjects with the variant genotypes(GC+GG)had a 58%increased risk of gastric cancer(adjusted OR=1.58,95%CI:1.11-2.20,P= 0.009).Moreover,a higher gastric cancer risk was especially evident in younger individuals aged≤58 years, nonsmokers,and males(adjusted OR=1.76,95%CI: 1.08-2.87,P=0.024;adjusted OR=1.55,95%CI: 1.06-2.28,P=0.025;adjusted OR=1.53,95%CI: 1.04-2.27,P=0.033;respectively). CONCLUSION:Pre-miR-146a C/G polymorphism might be associated with an elevated risk of gastric cancer in Chinese population.
基金Supported by The National Natural Science Foundation of Chi-na,No. 30873099Nanjing Medical University start-up research fund for Wang XRthe Natural Science Foundation of education Department,Jiangsu Province,No. 08KJB320004
文摘AIM： To evaluate the impact of the ITGA2 gene polymorphism on gastric cancer risk. METHODS： A hospital-based case-control study was conducted, including 307 gastric cancer patients and 307 age- and gender-matched control subjects. The genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism assay. RESULTS： The frequencies of the wild and variant genotypes in cases were significantly different from those of controls （P = 0.019）. Compared with individuals with the wild genotype CC, subjects with the variant genotypes （CT ＋ IT） had a significantly higher risk of gastric cancer （adjusted odds ratio = 1.57, 95% CI = 1.13-2.17, P = 0.007）. In stratified analyses, the elevated gastric cancer risk was especially evident in older individuals aged 〉 58 years, nonsmokers and rural subjects. Further analyses revealed that the variant genotypes were associated with poor tumor differentiation and adjacent organ invasion in the sub-analysis of gastric cancer patients. CONCLUSION： The ITGA2 gene C807T polymorphism may be associated with an increased risk of gastric cancer, differentiation and invasion of gastric cancer.
基金The authors are grateful for the financial supports from National Natural Science Foundation of China(51171212)Chongqing Science and Technology Commission(CSTC2012JJJQ50001,CSTC2013jcyjC60001,cstc2012ggB 50003)+1 种基金The National Science and Technology Program of China(2013DFA71070)the Fundamental Research Funds for the Central Universities(CDJZR13138801).
文摘The as-cast and as-extruded Mg–9Li–1Al–xCa alloys(x=0,0.2;wt%)were prepared by a simple alloying process followed by hot extrusion with an extrusion ratio of 28.2.The microstructures of the as-cast and as-extruded Mg–9Li–1Al–xCa alloys were observed to investigate the effect of calcium(Ca)element on the Mg–9Li–1Al(LA91)alloy,and the crystallographic calculations between Al_(2)Ca and the matrix(α-Mg andβ-Li phases)were examined on the basis of the edge-to-edge matching model.The experimental results indicate that the addition of 0.2 wt%Ca into LA91 alloy reduce the size of theα-Mg phases in the as-cast alloy and that ofβ-Li phases in the as-extruded alloy due to the Al_(2)Ca particles distributed inside the matrix.Crystallographic calculation results suggested that there is a good crystallographic matching between the matrix and Al_(2)Ca,which confirmed that Al_(2)Ca particles can act as a heterogeneous nucleation site for bothα-Mg andβ-Li phases and were effective grain refiners for LA91 alloy.
基金This study is financially supported by the National Natural Science Foundation of China(Grant No.51875089).
文摘The existing engineering empirical life analysis models are not capable of considering the constitutive behavior of materials under contact loads;as a consequence,these methods may not be accurate to predict fatigue lives of roll-ing bearings.In addition,the contact stress of bearing in operation is cyclically pulsating,it also means that the bear-ing undergo non-symmetrical fatigue loadings.Since the mean stress has great effects on fatigue life,in this work,a novel fatigue life prediction model based on the modified SWT mean stress correction is proposed as a basis of which to estimate the fatigue life of rolling bearings,in which,takes sensitivity of materials and mean stress into account.A compensation factor is introduced to overcome the inaccurate predictions resulted from the Smith,Watson,and Topper(SWT)model that considers the mean stress effect and sensitivity while assuming the sensitivity coefficient of all materials to be 0.5.Moreover,the validation of the model is finalized by several practical experimental data and the comparison to the conventional SWT model.The results show the better performance of the proposed model,especially in the accuracy than the existing SWT model.This research will shed light on a new direction for predicting the fatigue life of rolling bearings.
