Experimentswere performed to explore the impact of sulfur nanoparticles(SNPs)on growth,Cu accumulation,and physiological and biochemical responses of oilseed rape(Brassica napus L.)inoculated with 5 mg/L Cu-amended MS...Experimentswere performed to explore the impact of sulfur nanoparticles(SNPs)on growth,Cu accumulation,and physiological and biochemical responses of oilseed rape(Brassica napus L.)inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure.Cu exerted severe phytotoxicity and inhibited plant growth.SNPs application enhanced the shoot height,root length,and dry weight of shoot and root by 34.6%,282%,41.7%and 37.1%,respectively,over Cu treatment alone,while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde(MDA)levels in shoots and roots were decreased by 37.6%,35%,28.4%and 26.8%.Further,the increases in superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX),glutathione reductase(GR)and glutathione S-transferase(GST)enzyme activities caused by Cu stress were mitigated in shoots(10.9%–37.1%)and roots(14.6%–35.3%)with SNPs addition.SNPs also positively counteracted the negative effects on shoot K,Ca,P,Mg,Mn,Zn and Fe contents and root K,Ca,Mg and Mn contents from Cu exposure alone,and significantly promoted the nutrients accumulation in plant.Additionally,in comparison with common bulk sulfur particles(BSPs)and sulfate,SNPs showed more positive effects on promoting growth in shoots(6.7%and 19.5%)and roots(10.9%and 15.1%),as well as lowering the shoot Cu content(40.1%and 43.3%)under Cu stress.Thus,SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.展开更多
As a copper(Cu)transport ATPase,ATP7A plays an important role in maintaining Cu homeostasis in the body,but the developmental and physiological roles of atp7a in zebrafish embryogenesis are rarely studied.In this stud...As a copper(Cu)transport ATPase,ATP7A plays an important role in maintaining Cu homeostasis in the body,but the developmental and physiological roles of atp7a in zebrafish embryogenesis are rarely studied.In this study,normal morphological phenotypes of atp7a^(−/−)homozygous zebrafish were observed at both embryonic and adult stages,however,atp7a^(−/−)larvae exhibited delayed touch response and obvious transcriptome changes.Compared with the WT(wild type),differentially expressed genes(DEGs)in atp7a^(−/−)larvae showed the enrichment in gene ontology(GO)terms related to several processes including ATPase activity,oxidoreductase activity,active transmembrane transporter activity,ion binding,and the citrate cycle.Furthermore,decreases in both ATP content and Na+/K+-ATPase activity in atp7a^(−/−)embryos and larvae were unveiled.57 overlapping DEGs were found both in WT stressed with Cu and in WT mutated with atp7a,and GO term analysis indicated the enrichment in the genes related to neurexin family protein binding and neuronal cell-cell adhesion.Moreover,42 overlapping DEGs in Cu stressed WT and Cu stressed atp7a^(−/−)were identified.GO term analysis showed an enrichment in the genes related to heme binding,implying that Cu was independent of the integral function of atp7a to affect heme binding.In addition,genes involved in the negative regulation of angiogenesis were down-regulated in atp7a^(−/−)mutants with and without Cu stress,which failed to occur in WT,implying that the integral function of atp7a is required for maintaining the normal expression of angiogenesis genes.The integrative data in this study demonstrated that atp7a is required for ion transport and angiogenesis,and for Cu-induced neurexin family protein binding defects,rather than for Cu-induced heme binding defects,during zebrafish embryogenesis.These findings provide possible clues for human diseases with ATP7A dysfunction and imbalanced Cu homeostasis.展开更多
To study the mechanism of Cu toxicity on wheat,the characteristics of Cu stress in pivotal growth periods of wheat were explored by field planting methods.The results showed that at the tillering stage,the concentrati...To study the mechanism of Cu toxicity on wheat,the characteristics of Cu stress in pivotal growth periods of wheat were explored by field planting methods.The results showed that at the tillering stage,the concentrations of Cu in the leaf cell fluid were significantly higher than those in the cell wall,and the Cu was primarily enriched in cell fluid.At the jointing and heading stages,the Cu concentration in the leaf cell wall was significantly higher than that in the cell fluid,and the main enrichment was transferred to the cell wall.During the above three growth stages,no Cu was discovered in leaf organelles.Further studies showed that the total soluble protein content in wheat leaves at the tillering and jointing stages showed a trend of first rising and then falling with increased Cu dosage.At the heading stage,under low and medium Cu stress,the total soluble protein content showed no remarkable change.Malondialdehyde(MDA)content at the tillering stage increased with the increase of Cu concentration in the soil,while MDA content did not change noticeably at the jointing and heading stages.At the tillering and heading stages,the low concentrations of Cu increased peroxidase(POD)activity.The POD activity decreased gradually with the increased Cu concentration.However,at the high concentrations of Cu,there was no significant difference in the activity of POD.At the jointing stage,the POD activity did not change significantly under the low Cu stress while it was evidently inhibited under high Cu stress.Based on the above studies,further analyses on the correlation between canopy spectral characteristics and the Cu accumulation at different growth stages of leaf cells were performed,and a new combined index SIPI/NDVI705 performed well in Cu content prediction.The results showed that at different growth stages,different sensitive spectral characteristic parameters should be used to predict the Cu content in leaf cells.展开更多
We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results sho...We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results showed that Cu tolerance in Hippochaete ramosissimum varied significantly between different populations; the tolerance of plants living in Cu polluted areas for extended periods of time exceeded that of plants living in unpolluted areas.SOD and POD activities in highly Cu tolerant plants increased noticeably following exposure to Cu. This indicates that maintaining and increasing the two kinds of protective enzyme activities are the primary foundations of plant tolerance. However, no change in CAT activity was demonstrated following Cu exposure. In summary, there existed considerable differences in physiological metabolism between different populations of Hippochaete ramosissimum following exposure to Cu.展开更多
Alumina dispersion strengthened copper composite (nano-Al2O3/Cu composite) was recently emerged as a kind of potentially viable and attractive engineering material for applications requiring high strength, high ther...Alumina dispersion strengthened copper composite (nano-Al2O3/Cu composite) was recently emerged as a kind of potentially viable and attractive engineering material for applications requiring high strength, high thermal and electrical conductivities and resistance to softening at elevated temperatures. The nano-Al2O3/Cu composite was produced by internal oxidation. The microstructures of the composite were analyzed by the TEM and its hot deformation behavior was investigated by means of continuous compression tests performed on a Gleeble 1500 thermo-simulator. Making use of the modified algorithm-Levenberg-Marquardt (L-M) algorithm BP neural network, a model for predicting the flow stresses during hot deformation was set up on the base of the experimental data. Results show that the microstructures of the composite are characterized by uniform distribution of nano-Al2O3 particles in Cu-matrix. The sliding of dislocations is the main deformation mechanism. The dynamic recovery is the main softening mode with the flow stress decreasing gently from 500℃ to 850 ~C. The recrystallization of Cu-matrix can be retarded late into as high as 850 ℃, when it happens only partially. The well-trained BP neural network model can accurately describe the influence of the temperature, strain rate, and true strain on the flow stresses, therefore, it can precisely predict the flow stresses of the composite under given deforming conditions and provide a new way to optimize hot deforming process parameters.展开更多
Abstract[Objective]This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucumber seedlings,and therefore to elucidate the microb...Abstract[Objective]This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucumber seedlings,and therefore to elucidate the microbial mechanism of grafting for increasing cucumber plants tolerance to Cu stress[Method]Four treatments:(1)ungrafted seedlings+test soil(U0);(2)ungrafted seedlings+test soil+CuSO4·5H2O(U1);(3)grafted seedlings+test soil(G0);(4)grafted seedlings+test soil+CuSO4·5H2O(G1)were set in the pot culture experiment.The contents of free amino acids,organic acids,phenolic acid and sugars,microbial population and enzyme activity in the four treatment were measured,respectively.[Result]The secretion of amino acids and organic acids were increased under Cu stress.The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val.At the same time,the secretion of oxalic acid,malic acid,acetic acid,citric acid,cinnamic acid,ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as well.Therefore,more Cu2+were restricted in soil by chelating,complexing and precipitation with root exudates,and its toxicity was decreased.The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere,whereas basal respiration and metabolic quotient were significantly lower.Under Cu stress,the numbers of actinomyces and nitrogen fixing bacteria decreased and the number of fungi increased significantly,whereas there was no significant difference in amounts of bacteria.The numbers of bacteria,actinomyces,and nitrogen fixing bacteria in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere,but the number of fungi was opposite.The activities of soil urease,phosphatase,sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere.[Conclusion]These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress,and as a result,the adaptability of cucumber to Cu stress was improved.展开更多
The flow stress behavior of high-purity Al-Cu-Mg alloy under hot deformation conditions was studied by Gleeble-1500,with the deformation temperature range from 300 to 500 °C and the strain rate range from 0.01 to...The flow stress behavior of high-purity Al-Cu-Mg alloy under hot deformation conditions was studied by Gleeble-1500,with the deformation temperature range from 300 to 500 °C and the strain rate range from 0.01 to 10 s-1. From the true stress-true strain curve, the flow stress increases with the increasing of strain and tends to be constant after a peak value, showing dynamic recover, and the peak value of flow stress increases with the decreasing of deformation temperature and the increasing of strain rate.When the strain rate is 10 s-1 and the deformation temperature is higher than 400 °C, the flow stress shows dynamic recrystallization characteristic. TEM micrographs were used to reveal the evolution of microstructures. According to the processing map at true strain of 0.7, the feasible deformation conditions are high strain rate(>0.5 s-1) or 440-500 °C and 0.01-0.02 s-1.展开更多
The effect of stress on the microstructure and properties of an Al-Cu-Mg-Ag alloy under-aged at 165 ℃ for 2 h during thermal exposure at 200 ℃ was investigated. The tensile experimental results show that the remaine...The effect of stress on the microstructure and properties of an Al-Cu-Mg-Ag alloy under-aged at 165 ℃ for 2 h during thermal exposure at 200 ℃ was investigated. The tensile experimental results show that the remained tensile strength of both specimens at room temperature after being exposed at 200 ℃ with and without applying stress rises firstly, and then drops with the increasing of exposure time. The peak value of the remained strength reaches 439 MPa for non-stress-exposure for 10 h, and 454 MPa after being exposed with stress loaded for 20 h at 220 MPa. The elongation change is similar to that of strength. After being exposed for 100 h, specimen exposed at 220 MPa still remains a tensile strength of 401 MPa, larger than that exposed without applying stress. TEM shows that the microstructure of under-aged alloy is dominated by - phase mainly and a little θ′ phase. The θ′ and - phases are believed competitive with increasing exposure time. The width of precipitation free zone(PFZ) increases and the granular second phase precipitates at grain-boundary correspondingly. It is shown that the mechanical properties of alloy decrease slightly and present good thermal stability after thermal exposure at 200 ℃ and 220 MPa for 100 h.展开更多
The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator....The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.展开更多
The thermal boundary condition has very important effects on the accuracy of thermal stress calculation of a water-cooled W/Cu divertor. In this paper, phase-change heat transfer was simulated based on the Euler homog...The thermal boundary condition has very important effects on the accuracy of thermal stress calculation of a water-cooled W/Cu divertor. In this paper, phase-change heat transfer was simulated based on the Euler homogeneous phase model, and local differences of liquid physical properties were considered under one-sided high heating conditions. The steady-state temperature field and thermal stress field under nonuniform thermal boundary conditions were obtained through numerical calculation. By comparison with the case of traditional uniform thermal boundary conditions, the results show that the distribution of thermal stress under nonuniform thermal boundary conditions exhibits tbe same trend as that under uniform thermal boundary conditions, but is larger in value. The maximum difference of maximum von Mises stress is up to 42% under the highest heating conditions. These results provide a valuable reference for the thermal stress caleulat.ion of water-cooled W/Cu divertors.展开更多
The glutathione S-transferases gene family plays an important regulatory role in growth and development,and responses to environmental change.In this study,six complete GST genes(Mp GST1,Mp GST2,Mp GST3,MpGST4,Mp GST5...The glutathione S-transferases gene family plays an important regulatory role in growth and development,and responses to environmental change.In this study,six complete GST genes(Mp GST1,Mp GST2,Mp GST3,MpGST4,Mp GST5,and Mp GST6)were cloned from the gametophytes of brown alga Macrocystis pyrifera.Subsequent bioinformatics analysis showed that these six genes encoded proteins with 202,216,288,201,205,and 201 aa,respectively.Moreover,Mp GST3 differs from the other GST genes.Phylogenetic analysis suggested that MpGST3 belongs to the Ure2p type GST.Domain analysis suggested that the other GSTs from M.pyrifera belong to the soluble GST family and form an independent branch with the GSTs found in the other macroalgae,suggesting that a new GST type was formed during macroalgal evolution.GST genes were upregulated in M.pyrifera when 2.5 mg L^(-1)Cu ions were added to the medium.Six GST genes were integrated into the genome of Synechococcus elongatus PCC 7942,and their functions were verified by measuring light absorbance,photosynthetic pigment content,and photosynthetic parameters of the transformed strains under 0.3 mg L^(-1)Cu ion stress.The results showed much higher levels of various parameters in the transformed strains than in the wild strain.The transformed strains(with the MpGST genes)showed significantly enhanced resistance to Cu ion stress,while the wild strain almost died.The results of this study lay a theoretical foundation for further research on the Cu ion stress resistance function of GSTs in M.pyrifera.展开更多
The flow stress behavior of Al-3.5Cu-1.5Li-0.25(Sc+Zr) alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator. Compression tests were prefor...The flow stress behavior of Al-3.5Cu-1.5Li-0.25(Sc+Zr) alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator. Compression tests were preformed in the temperature range of 653-773 K and in the strain rate range of 0.001-10 s-1 up to a true plastic strain of 0.7. The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature,and decreases with increasing temperature at a given imposed strain rate. The relationship between the flow stress and the strain rate and the temperature was derived by analyzing the experimental data. The flow stress is in a hyperbolic sine relationship with the strain rate,and in an Arrhenius relationship with the temperature,which imply that the process of plastic deformation at an elevated temperature for this material is thermally activated. The flow stress of the alloy during the elevated temperature deformation can be represented by a Zener-Hollomon parameter with the inclusion of the Arrhenius term. The values of n,α and A in the analytical expressions of flow stress σ are fitted to be 5.62,0.019 MPa-1 and 1.51×1016 s-1,respectively. The hot deformation activation energy is 240.85 kJ/mol.展开更多
Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction ...Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction of β phase. The training method of cooling with load can induce a lot of martensite prone to stabilize, thus cause large residual deformation, wide hysteresis and small TWME. Training with constant load can produce STWME larger than 8% with the least residual deformation. By training procedure of martensite reorientation below M f followed by thermal cycling, the TWME is relatively large with very small residual deformation and with comparatively narrow hysteresis of two way memory. The obtained two way memory curve after such training is not a closed loop, and the obtained TWME is not stable. However, these can be improved by thermal cycling. Training with martensite reorientation below M f and thermal cycling under relatively low constant stress throughout the whole training procedure is the optimum way of obtaining TWME, and more than 1.7% TWME can be obtained. The thermomechanical history of the sample has a pronounced effect on the training result. Thermomechanical cycling has a softening effect on martensite. [展开更多
The microstructure of surface peeling in finish rolled Cu-0.1Fe-0.03P sheetis analyzed by scanning electron microscope and energy dispersive spectroscope. Fe-rich areas ofdifferent contents are observed in the matrix....The microstructure of surface peeling in finish rolled Cu-0.1Fe-0.03P sheetis analyzed by scanning electron microscope and energy dispersive spectroscope. Fe-rich areas ofdifferent contents are observed in the matrix. The stress distributions and strain characteristicsat the interface between Cu matrix and Fe particle are studied by elastic-plastic finite elementplane strain model. Larger Fe particles and higher deforming extent of finish rolling are attributedto the intense stress gradient and significant non-homogeneity equivalent strain at the interfaceand accelerate surface peeling of Cu-0.1Fe-0.03P lead frame sheet.展开更多
基金supported by the Social Developmental Project of Jiangsu Province(No.BE2018715)the National Natural Science Foundation of China(No.41907135)the Independent Research Program of Public Welfare Institutes in Jiangsu Province(No.BM2018021-6)
文摘Experimentswere performed to explore the impact of sulfur nanoparticles(SNPs)on growth,Cu accumulation,and physiological and biochemical responses of oilseed rape(Brassica napus L.)inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure.Cu exerted severe phytotoxicity and inhibited plant growth.SNPs application enhanced the shoot height,root length,and dry weight of shoot and root by 34.6%,282%,41.7%and 37.1%,respectively,over Cu treatment alone,while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde(MDA)levels in shoots and roots were decreased by 37.6%,35%,28.4%and 26.8%.Further,the increases in superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX),glutathione reductase(GR)and glutathione S-transferase(GST)enzyme activities caused by Cu stress were mitigated in shoots(10.9%–37.1%)and roots(14.6%–35.3%)with SNPs addition.SNPs also positively counteracted the negative effects on shoot K,Ca,P,Mg,Mn,Zn and Fe contents and root K,Ca,Mg and Mn contents from Cu exposure alone,and significantly promoted the nutrients accumulation in plant.Additionally,in comparison with common bulk sulfur particles(BSPs)and sulfate,SNPs showed more positive effects on promoting growth in shoots(6.7%and 19.5%)and roots(10.9%and 15.1%),as well as lowering the shoot Cu content(40.1%and 43.3%)under Cu stress.Thus,SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.
基金This work was supported by the National Key R&D Program of China(2022YFF1000302)by the project of the Knowledge Innovation Program of Wuhan-Basic Research 2022020801010223by the National Natural Science Foundation of China(Program No.32070807 to J-X.L).
文摘As a copper(Cu)transport ATPase,ATP7A plays an important role in maintaining Cu homeostasis in the body,but the developmental and physiological roles of atp7a in zebrafish embryogenesis are rarely studied.In this study,normal morphological phenotypes of atp7a^(−/−)homozygous zebrafish were observed at both embryonic and adult stages,however,atp7a^(−/−)larvae exhibited delayed touch response and obvious transcriptome changes.Compared with the WT(wild type),differentially expressed genes(DEGs)in atp7a^(−/−)larvae showed the enrichment in gene ontology(GO)terms related to several processes including ATPase activity,oxidoreductase activity,active transmembrane transporter activity,ion binding,and the citrate cycle.Furthermore,decreases in both ATP content and Na+/K+-ATPase activity in atp7a^(−/−)embryos and larvae were unveiled.57 overlapping DEGs were found both in WT stressed with Cu and in WT mutated with atp7a,and GO term analysis indicated the enrichment in the genes related to neurexin family protein binding and neuronal cell-cell adhesion.Moreover,42 overlapping DEGs in Cu stressed WT and Cu stressed atp7a^(−/−)were identified.GO term analysis showed an enrichment in the genes related to heme binding,implying that Cu was independent of the integral function of atp7a to affect heme binding.In addition,genes involved in the negative regulation of angiogenesis were down-regulated in atp7a^(−/−)mutants with and without Cu stress,which failed to occur in WT,implying that the integral function of atp7a is required for maintaining the normal expression of angiogenesis genes.The integrative data in this study demonstrated that atp7a is required for ion transport and angiogenesis,and for Cu-induced neurexin family protein binding defects,rather than for Cu-induced heme binding defects,during zebrafish embryogenesis.These findings provide possible clues for human diseases with ATP7A dysfunction and imbalanced Cu homeostasis.
基金This work was supported by the National Natural Science Fund of China(41471279)。
文摘To study the mechanism of Cu toxicity on wheat,the characteristics of Cu stress in pivotal growth periods of wheat were explored by field planting methods.The results showed that at the tillering stage,the concentrations of Cu in the leaf cell fluid were significantly higher than those in the cell wall,and the Cu was primarily enriched in cell fluid.At the jointing and heading stages,the Cu concentration in the leaf cell wall was significantly higher than that in the cell fluid,and the main enrichment was transferred to the cell wall.During the above three growth stages,no Cu was discovered in leaf organelles.Further studies showed that the total soluble protein content in wheat leaves at the tillering and jointing stages showed a trend of first rising and then falling with increased Cu dosage.At the heading stage,under low and medium Cu stress,the total soluble protein content showed no remarkable change.Malondialdehyde(MDA)content at the tillering stage increased with the increase of Cu concentration in the soil,while MDA content did not change noticeably at the jointing and heading stages.At the tillering and heading stages,the low concentrations of Cu increased peroxidase(POD)activity.The POD activity decreased gradually with the increased Cu concentration.However,at the high concentrations of Cu,there was no significant difference in the activity of POD.At the jointing stage,the POD activity did not change significantly under the low Cu stress while it was evidently inhibited under high Cu stress.Based on the above studies,further analyses on the correlation between canopy spectral characteristics and the Cu accumulation at different growth stages of leaf cells were performed,and a new combined index SIPI/NDVI705 performed well in Cu content prediction.The results showed that at different growth stages,different sensitive spectral characteristic parameters should be used to predict the Cu content in leaf cells.
基金the National Key Basic Research Plan of China (973-2004CB418503) National Natural Science Foundation of China (Grant No. 30470270) Natural Science Research Foundation of Anhui Province (Grant No.03043501).
文摘We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results showed that Cu tolerance in Hippochaete ramosissimum varied significantly between different populations; the tolerance of plants living in Cu polluted areas for extended periods of time exceeded that of plants living in unpolluted areas.SOD and POD activities in highly Cu tolerant plants increased noticeably following exposure to Cu. This indicates that maintaining and increasing the two kinds of protective enzyme activities are the primary foundations of plant tolerance. However, no change in CAT activity was demonstrated following Cu exposure. In summary, there existed considerable differences in physiological metabolism between different populations of Hippochaete ramosissimum following exposure to Cu.
基金Henan Innovation Project for University Prominent Research Talents (2007KYCX008)Henan Major Science and Technol-ogy Project (0523021500)+1 种基金Henan University of Science and Technology Major Pre-research Foundation (2005ZD003)Henan University of Science and Technology Personnel Scientific Research Foundation
文摘Alumina dispersion strengthened copper composite (nano-Al2O3/Cu composite) was recently emerged as a kind of potentially viable and attractive engineering material for applications requiring high strength, high thermal and electrical conductivities and resistance to softening at elevated temperatures. The nano-Al2O3/Cu composite was produced by internal oxidation. The microstructures of the composite were analyzed by the TEM and its hot deformation behavior was investigated by means of continuous compression tests performed on a Gleeble 1500 thermo-simulator. Making use of the modified algorithm-Levenberg-Marquardt (L-M) algorithm BP neural network, a model for predicting the flow stresses during hot deformation was set up on the base of the experimental data. Results show that the microstructures of the composite are characterized by uniform distribution of nano-Al2O3 particles in Cu-matrix. The sliding of dislocations is the main deformation mechanism. The dynamic recovery is the main softening mode with the flow stress decreasing gently from 500℃ to 850 ~C. The recrystallization of Cu-matrix can be retarded late into as high as 850 ℃, when it happens only partially. The well-trained BP neural network model can accurately describe the influence of the temperature, strain rate, and true strain on the flow stresses, therefore, it can precisely predict the flow stresses of the composite under given deforming conditions and provide a new way to optimize hot deforming process parameters.
基金Supported by Shandong Modern Agricultural Technology & Industry System
文摘Abstract[Objective]This study to aimed to investigate the effects of Cu stress on root exudates and microbial activities in rhizosphere of grafted and ungrafted cucumber seedlings,and therefore to elucidate the microbial mechanism of grafting for increasing cucumber plants tolerance to Cu stress[Method]Four treatments:(1)ungrafted seedlings+test soil(U0);(2)ungrafted seedlings+test soil+CuSO4·5H2O(U1);(3)grafted seedlings+test soil(G0);(4)grafted seedlings+test soil+CuSO4·5H2O(G1)were set in the pot culture experiment.The contents of free amino acids,organic acids,phenolic acid and sugars,microbial population and enzyme activity in the four treatment were measured,respectively.[Result]The secretion of amino acids and organic acids were increased under Cu stress.The amino acids secretions of grafted seedlings roots were obviously higher than ungrafted seedlings except for Phe and Val.At the same time,the secretion of oxalic acid,malic acid,acetic acid,citric acid,cinnamic acid,ρ-hydroxybenzoic acid and benzoic acid of grafted seedlings were significantly higher than ungrafted seedlings as well.Therefore,more Cu2+were restricted in soil by chelating,complexing and precipitation with root exudates,and its toxicity was decreased.The soil microbial biomass C and N in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere,whereas basal respiration and metabolic quotient were significantly lower.Under Cu stress,the numbers of actinomyces and nitrogen fixing bacteria decreased and the number of fungi increased significantly,whereas there was no significant difference in amounts of bacteria.The numbers of bacteria,actinomyces,and nitrogen fixing bacteria in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere,but the number of fungi was opposite.The activities of soil urease,phosphatase,sucrase and catalase in grafted cucumber rhizosphere were significantly higher than those in ungrafted cucumber rhizosphere.[Conclusion]These indicated that the soil microbial environment and soil enzymes activities were improved by grafting under Cu stress,and as a result,the adaptability of cucumber to Cu stress was improved.
基金the National Key R&D Program of China(No.2018YFA0707300)the National Natural Science Foundation of China(Nos.51904206,52105390,51905372,51805359)+3 种基金the China Postdoctoral Science Foundation(No.2020M670705)the Natural Science Foundation of Shanxi Province,China(No.201801D221130)the Major Program of National Natural Science Foundation of China(No.U1710254)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province,China(No.2019L0258).
基金Project(51301209) supported by the National Natural Science Foundation of ChinaProject(201191107) supported by Science and Technology Plan of Xinjiang Province,China
文摘The flow stress behavior of high-purity Al-Cu-Mg alloy under hot deformation conditions was studied by Gleeble-1500,with the deformation temperature range from 300 to 500 °C and the strain rate range from 0.01 to 10 s-1. From the true stress-true strain curve, the flow stress increases with the increasing of strain and tends to be constant after a peak value, showing dynamic recover, and the peak value of flow stress increases with the decreasing of deformation temperature and the increasing of strain rate.When the strain rate is 10 s-1 and the deformation temperature is higher than 400 °C, the flow stress shows dynamic recrystallization characteristic. TEM micrographs were used to reveal the evolution of microstructures. According to the processing map at true strain of 0.7, the feasible deformation conditions are high strain rate(>0.5 s-1) or 440-500 °C and 0.01-0.02 s-1.
基金Project(2005CB623705-04) supported by the National Basic Research Program of China
文摘The effect of stress on the microstructure and properties of an Al-Cu-Mg-Ag alloy under-aged at 165 ℃ for 2 h during thermal exposure at 200 ℃ was investigated. The tensile experimental results show that the remained tensile strength of both specimens at room temperature after being exposed at 200 ℃ with and without applying stress rises firstly, and then drops with the increasing of exposure time. The peak value of the remained strength reaches 439 MPa for non-stress-exposure for 10 h, and 454 MPa after being exposed with stress loaded for 20 h at 220 MPa. The elongation change is similar to that of strength. After being exposed for 100 h, specimen exposed at 220 MPa still remains a tensile strength of 401 MPa, larger than that exposed without applying stress. TEM shows that the microstructure of under-aged alloy is dominated by - phase mainly and a little θ′ phase. The θ′ and - phases are believed competitive with increasing exposure time. The width of precipitation free zone(PFZ) increases and the granular second phase precipitates at grain-boundary correspondingly. It is shown that the mechanical properties of alloy decrease slightly and present good thermal stability after thermal exposure at 200 ℃ and 220 MPa for 100 h.
基金the National Basic Research Program of China(No.2005CB623705)
文摘The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s^-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.
基金supported by National Magnetic Confinement Fusion Science Program of China(No.2010GB104005)
文摘The thermal boundary condition has very important effects on the accuracy of thermal stress calculation of a water-cooled W/Cu divertor. In this paper, phase-change heat transfer was simulated based on the Euler homogeneous phase model, and local differences of liquid physical properties were considered under one-sided high heating conditions. The steady-state temperature field and thermal stress field under nonuniform thermal boundary conditions were obtained through numerical calculation. By comparison with the case of traditional uniform thermal boundary conditions, the results show that the distribution of thermal stress under nonuniform thermal boundary conditions exhibits tbe same trend as that under uniform thermal boundary conditions, but is larger in value. The maximum difference of maximum von Mises stress is up to 42% under the highest heating conditions. These results provide a valuable reference for the thermal stress caleulat.ion of water-cooled W/Cu divertors.
基金supported by the National Key R&D Program of China(No.2018YFD0900305)the National Natural Science Foundation of China(No.31770393)+5 种基金the Major Scientific and Technological Innovation Project of Shandong Provincial Key Research and Development Program(No.2019JZZY020706)the Central Public-Interest Scientific Institute Basal Research Fund,CAFS(Nos.2020TD 19 and 2020TD27)the China Agriculture Research System(CARS-50)the Taishan Scholars Funding of Shandong Provincethe Taishan Scholars Funding and Talent Projects of Distinguished Scientific Scholars in AgricultureYoung Taishan Scholars Program to DONG Xu。
文摘The glutathione S-transferases gene family plays an important regulatory role in growth and development,and responses to environmental change.In this study,six complete GST genes(Mp GST1,Mp GST2,Mp GST3,MpGST4,Mp GST5,and Mp GST6)were cloned from the gametophytes of brown alga Macrocystis pyrifera.Subsequent bioinformatics analysis showed that these six genes encoded proteins with 202,216,288,201,205,and 201 aa,respectively.Moreover,Mp GST3 differs from the other GST genes.Phylogenetic analysis suggested that MpGST3 belongs to the Ure2p type GST.Domain analysis suggested that the other GSTs from M.pyrifera belong to the soluble GST family and form an independent branch with the GSTs found in the other macroalgae,suggesting that a new GST type was formed during macroalgal evolution.GST genes were upregulated in M.pyrifera when 2.5 mg L^(-1)Cu ions were added to the medium.Six GST genes were integrated into the genome of Synechococcus elongatus PCC 7942,and their functions were verified by measuring light absorbance,photosynthetic pigment content,and photosynthetic parameters of the transformed strains under 0.3 mg L^(-1)Cu ion stress.The results showed much higher levels of various parameters in the transformed strains than in the wild strain.The transformed strains(with the MpGST genes)showed significantly enhanced resistance to Cu ion stress,while the wild strain almost died.The results of this study lay a theoretical foundation for further research on the Cu ion stress resistance function of GSTs in M.pyrifera.
基金Project(2002AA305104) supported by the National High-Tech Research and Development Program of China
文摘The flow stress behavior of Al-3.5Cu-1.5Li-0.25(Sc+Zr) alloy during hot compression deformation was studied by isothermal compression test using Gleeble-1500 thermal-mechanical simulator. Compression tests were preformed in the temperature range of 653-773 K and in the strain rate range of 0.001-10 s-1 up to a true plastic strain of 0.7. The results indicate that the flow stress of the alloy increases with increasing strain rate at a given temperature,and decreases with increasing temperature at a given imposed strain rate. The relationship between the flow stress and the strain rate and the temperature was derived by analyzing the experimental data. The flow stress is in a hyperbolic sine relationship with the strain rate,and in an Arrhenius relationship with the temperature,which imply that the process of plastic deformation at an elevated temperature for this material is thermally activated. The flow stress of the alloy during the elevated temperature deformation can be represented by a Zener-Hollomon parameter with the inclusion of the Arrhenius term. The values of n,α and A in the analytical expressions of flow stress σ are fitted to be 5.62,0.019 MPa-1 and 1.51×1016 s-1,respectively. The hot deformation activation energy is 240.85 kJ/mol.
文摘Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction of β phase. The training method of cooling with load can induce a lot of martensite prone to stabilize, thus cause large residual deformation, wide hysteresis and small TWME. Training with constant load can produce STWME larger than 8% with the least residual deformation. By training procedure of martensite reorientation below M f followed by thermal cycling, the TWME is relatively large with very small residual deformation and with comparatively narrow hysteresis of two way memory. The obtained two way memory curve after such training is not a closed loop, and the obtained TWME is not stable. However, these can be improved by thermal cycling. Training with martensite reorientation below M f and thermal cycling under relatively low constant stress throughout the whole training procedure is the optimum way of obtaining TWME, and more than 1.7% TWME can be obtained. The thermomechanical history of the sample has a pronounced effect on the training result. Thermomechanical cycling has a softening effect on martensite. [
基金This project is supported by 863 Program of China (N0.2002AA331112)Doctoral Foundation of Northwestern Polytechnical University.
文摘The microstructure of surface peeling in finish rolled Cu-0.1Fe-0.03P sheetis analyzed by scanning electron microscope and energy dispersive spectroscope. Fe-rich areas ofdifferent contents are observed in the matrix. The stress distributions and strain characteristicsat the interface between Cu matrix and Fe particle are studied by elastic-plastic finite elementplane strain model. Larger Fe particles and higher deforming extent of finish rolling are attributedto the intense stress gradient and significant non-homogeneity equivalent strain at the interfaceand accelerate surface peeling of Cu-0.1Fe-0.03P lead frame sheet.