The peak fields of HT-7U TF/PF coils are designed at 5.8 T and 4.5 T, respectively. The superconducting (SC) NbTi/Cu strands for the coils have a quite low copper fraction (0.58). To increase the ratio of the limiting...The peak fields of HT-7U TF/PF coils are designed at 5.8 T and 4.5 T, respectively. The superconducting (SC) NbTi/Cu strands for the coils have a quite low copper fraction (0.58). To increase the ratio of the limiting current Vs. critical current for the cable in conduit conductor (CICC), the first-stage subcable consists of several copper strands twisted around a SC composite one. The copper strand diameter is different from the SC one. Based on Bottura's CICC design approach we take the product of total copper cross-section and wetted perimeter as one of the key design parameters to meet with stability margin requirement. The product reaches 114 cm3 for 15.5 kA TF CICC at operating temperature of 4.2 K and 139 cm3 for 15 kA PF CICC at 3.8 K to obtain stability margins of 280 and 700 mJ/cm3, respectively.展开更多
The conjugation of SUMO (small ubiquitin-like modifier) to protein substrates is a reversible process (SUMOylation/deSUMOylation) that regulates plant devel- opment and stress responses. The essential metal copper...The conjugation of SUMO (small ubiquitin-like modifier) to protein substrates is a reversible process (SUMOylation/deSUMOylation) that regulates plant devel- opment and stress responses. The essential metal copper (Cu) is required for normal plant growth, but excess amounts are toxic. The SUMO E3 ligase, SIZI, and SIZ1- mediated SUMOylation function in plant tolerance to excess Cu. It is unknown whether deSUMOylation also contributes to Cu tolerance in plants. Here, we report that OTSI, a protease that cleaves SUMO from its substrate proteins, participates in Cu tolerance in Arabidopsis thaliana (Arabi- dopsis). OTS1 loss-of-function mutants (otsl-2 and otsl-3) displayed increased sensitivity to excess Cu. Redox homeostasis and the balance between SUMOylation and deSUMOylation were disrupted in the otsl-3 mutant under excess Cu conditions, The otsl-3 mutant accumulated higher levels of Cu in both shoots and roots compared to wild type. Specific Cu-related metal transporter genes were upregu- lated due to the loss-of-function of OTS% which might explain the high Cu levels in otsl-3. These results suggest that the SUMOylation/deSUMOylation machinery is acti- vated in response to excess Cu, and modulates Cu homeostasis and tolerance by regulating both Cu uptake and detoxification. Together, our findings provide insight into the biological function and regulatory role of SUMOylation/deSUMOylation in plant tolerance to Cu.展开更多
China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed...China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed the non-argent Lanthanum-tellurium-copper alloy as a substitute for industry argent-copper. In our research, we were able to successfully apply rare earth lanthanum to copper alloy. The defects as porosity, inclusion, etc. originating from nonvacuum melting processing were controlled. Fine grain was obtained. Meanwhile, the comprehensive properties of the copper alloy, such as strength, conductivity and thermal conductivity were improved. The research results in increasing conductivity and thermal conductivity by 5% and 15%, respectively, while the tensile strength is increased by 6% higher than Ag-Cu alloy. The anti-electric corrosion property is good, and there is no argent-cadmium steam population originating from the electric arc effect. The addition of lanthanum further reduces the content of oxygen and hydrogen. The optimum quantity of the addition of RE lanthanum in the copper alloy is 0.010% - 0.020% .展开更多
Pure copper tensile bars were produced by conventional die casting(HPDC) and vacuum-assist die casting(VADC) processes. Porosity and mechanical properties were investigated by using optical microscopy(OM), scanning el...Pure copper tensile bars were produced by conventional die casting(HPDC) and vacuum-assist die casting(VADC) processes. Porosity and mechanical properties were investigated by using optical microscopy(OM), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), X-ray computed tomography(XCT) and tensile tester. Results show that porosities including gas porosity and shrinkage porosity could be observed in copper castings. Since the application of vacuum could reduce filling related gas entrapment and facilitate solidification due to the increased heat transfer between metal and die, both number and size of the entrapped gases, as well as shrinkage porosities were significantly reduced in vacuum-assist die castings of pure copper. The porosity fraction decreased from 2.243% to 0.875% compared with that of the conventional die casting. Besides, mechanical properties were improved significantly, i.e., by 15% for ultimate tensile strength and three times for elongation.展开更多
The as-formed and post-deformed microstructures in both electroformed and spin-formed copper liners of shaped charge were studied by optical microscopy(OM), electron backscattering Kikuchi patterns(EBSP) technique and...The as-formed and post-deformed microstructures in both electroformed and spin-formed copper liners of shaped charge were studied by optical microscopy(OM), electron backscattering Kikuchi patterns(EBSP) technique and transmission electron microscopy(TEM). The deformation was carried out at an ultra-high strain rate. OM analysis shows that the initial grains of the electroformed copper liner are finer than those of the spin-formed copper liners. Meanwhile, EBSP analysis reveals that the fiber texture exists in the electroformed copper liners, whereas there is no texture observed in the spin-formed copper liners before deformation. Having undergone high-strain-rate deformation the grains in the recovered slugs, which are transformed from both the electroformed and spin-formed copper liners, all become small. TEM observations of the above two kinds of post-deformed specimens show the existence of cellular structures characterized by tangled dislocations and subgrain boundaries consisting of dislocation arrays. These experimental results indicate that dynamic recovery and recrystallization play an important role in the high-strain-rate deformation process.展开更多
The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate solution.The main parameters,such as ammonia and ammonium sulphate concentrations,particle size,solid-t...The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate solution.The main parameters,such as ammonia and ammonium sulphate concentrations,particle size,solid-to-liquid ratio and reaction temperature,were chosen in the experiments.The results show that the increase of temperature,concentrations of ammonia and ammonium sulphate is propitious to the leaching rate of copper ore.The leaching rate increases with the decrease of particle size and solid-to-liquid ratio.The leaching rate is controlled by the diffusion through the ash layer and the activation energy is determined to be 25.54 kJ/mol.A semi-empirical equation was proposed to describe the leaching kinetics.展开更多
Various optical luminescence spectroscopic techniques were used to characterize the high T_c superconductor YBa_2Cu_3O_x.The emission bands reveal that Cu^(3+) coexist with Cu^(2+) and Cu^+ in this material.
The influence of fabrication on the tensile and fatigue behavior of copper films manufactured by 3 kinds of fabrication methods was investigated. The tensile and high cycle fatigue tests were performed using the test ...The influence of fabrication on the tensile and fatigue behavior of copper films manufactured by 3 kinds of fabrication methods was investigated. The tensile and high cycle fatigue tests were performed using the test machine developed by authors. Young's moduli (72, 71 and 69 GPa, respectively) are lower than the literature values (108-145 GPa), while the yield strengths were as high as 358, 350 and 346 MPa, respectively and the ultimate strengths as 462, 456 and 446 MPa, respectively. There is not much difference in the tensile properties of the 3 kinds of films. There is little difference in the fatigue properties of the 3 kinds of films but one of them has shorter fatigue life than others in high cycle region and longer fatigue life than others in low cycle region.展开更多
The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leachi...The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leaching were considered. In the first stage, effects of flotation parameters including collector type, collector dosage, and pH and pulp density were examined. The results showed that over 80% copper recovery was achieved under the optimized flotation conditions while nickel recovery was lower than 30% due to its co-ex-istence with gangue minerals of pyrrhotite, pyrite and other clay minerals. In the second stage, key parameters, particularly concentration of sulfuric acid, temperature, pressure and leaching time were investigated to test the leaching efficiency of copper and nickel from the flotation concentrate with high pressure oxidative leaching (HPOL). A comparison was made between the leaching efficiencies of copper and nickel from flotation concentrates and mine tailing.展开更多
The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated. The results show that the microstructure of the as-cast high chr...The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated. The results show that the microstructure of the as-cast high chromium cast irons consists of retained austenite, martensite and M7C3 type eutectic carbide. When copper is added into high chromium cast irons, austenite and carbide contents are increased. The increased addition of copper content from 0% to 1.84% leads to the increase of austenite and carbide from 15.9% and 20.0% to 61.0% and 35.5%, respectively. In the process of sub-critical treatment, the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process, which causes the secondary hardening of the alloy under sub-critical treatment. High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.展开更多
文摘The peak fields of HT-7U TF/PF coils are designed at 5.8 T and 4.5 T, respectively. The superconducting (SC) NbTi/Cu strands for the coils have a quite low copper fraction (0.58). To increase the ratio of the limiting current Vs. critical current for the cable in conduit conductor (CICC), the first-stage subcable consists of several copper strands twisted around a SC composite one. The copper strand diameter is different from the SC one. Based on Bottura's CICC design approach we take the product of total copper cross-section and wetted perimeter as one of the key design parameters to meet with stability margin requirement. The product reaches 114 cm3 for 15.5 kA TF CICC at operating temperature of 4.2 K and 139 cm3 for 15 kA PF CICC at 3.8 K to obtain stability margins of 280 and 700 mJ/cm3, respectively.
基金supported by the National Transgenic Major Project of China (2016ZX08009-003-002 to H.L.)the National Natural Science Foundation of China (31600201 to H.Z+1 种基金 31470342 and 31670235 to H.L.)the National Basic Research Program of China (2015CB150100 to H.L)
文摘The conjugation of SUMO (small ubiquitin-like modifier) to protein substrates is a reversible process (SUMOylation/deSUMOylation) that regulates plant devel- opment and stress responses. The essential metal copper (Cu) is required for normal plant growth, but excess amounts are toxic. The SUMO E3 ligase, SIZI, and SIZ1- mediated SUMOylation function in plant tolerance to excess Cu. It is unknown whether deSUMOylation also contributes to Cu tolerance in plants. Here, we report that OTSI, a protease that cleaves SUMO from its substrate proteins, participates in Cu tolerance in Arabidopsis thaliana (Arabi- dopsis). OTS1 loss-of-function mutants (otsl-2 and otsl-3) displayed increased sensitivity to excess Cu. Redox homeostasis and the balance between SUMOylation and deSUMOylation were disrupted in the otsl-3 mutant under excess Cu conditions, The otsl-3 mutant accumulated higher levels of Cu in both shoots and roots compared to wild type. Specific Cu-related metal transporter genes were upregu- lated due to the loss-of-function of OTS% which might explain the high Cu levels in otsl-3. These results suggest that the SUMOylation/deSUMOylation machinery is acti- vated in response to excess Cu, and modulates Cu homeostasis and tolerance by regulating both Cu uptake and detoxification. Together, our findings provide insight into the biological function and regulatory role of SUMOylation/deSUMOylation in plant tolerance to Cu.
基金Project supported by the National Scientific and Technological Achievements Spread Project (2004EC00299)Science and Technology Type Middle and Small Business Technique Invention Fund (04C26225121390)
文摘China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed the non-argent Lanthanum-tellurium-copper alloy as a substitute for industry argent-copper. In our research, we were able to successfully apply rare earth lanthanum to copper alloy. The defects as porosity, inclusion, etc. originating from nonvacuum melting processing were controlled. Fine grain was obtained. Meanwhile, the comprehensive properties of the copper alloy, such as strength, conductivity and thermal conductivity were improved. The research results in increasing conductivity and thermal conductivity by 5% and 15%, respectively, while the tensile strength is increased by 6% higher than Ag-Cu alloy. The anti-electric corrosion property is good, and there is no argent-cadmium steam population originating from the electric arc effect. The addition of lanthanum further reduces the content of oxygen and hydrogen. The optimum quantity of the addition of RE lanthanum in the copper alloy is 0.010% - 0.020% .
文摘Pure copper tensile bars were produced by conventional die casting(HPDC) and vacuum-assist die casting(VADC) processes. Porosity and mechanical properties were investigated by using optical microscopy(OM), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), X-ray computed tomography(XCT) and tensile tester. Results show that porosities including gas porosity and shrinkage porosity could be observed in copper castings. Since the application of vacuum could reduce filling related gas entrapment and facilitate solidification due to the increased heat transfer between metal and die, both number and size of the entrapped gases, as well as shrinkage porosities were significantly reduced in vacuum-assist die castings of pure copper. The porosity fraction decreased from 2.243% to 0.875% compared with that of the conventional die casting. Besides, mechanical properties were improved significantly, i.e., by 15% for ultimate tensile strength and three times for elongation.
基金Project(571014569) supported by the National Natural Science Foundation of China
文摘The as-formed and post-deformed microstructures in both electroformed and spin-formed copper liners of shaped charge were studied by optical microscopy(OM), electron backscattering Kikuchi patterns(EBSP) technique and transmission electron microscopy(TEM). The deformation was carried out at an ultra-high strain rate. OM analysis shows that the initial grains of the electroformed copper liner are finer than those of the spin-formed copper liners. Meanwhile, EBSP analysis reveals that the fiber texture exists in the electroformed copper liners, whereas there is no texture observed in the spin-formed copper liners before deformation. Having undergone high-strain-rate deformation the grains in the recovered slugs, which are transformed from both the electroformed and spin-formed copper liners, all become small. TEM observations of the above two kinds of post-deformed specimens show the existence of cellular structures characterized by tangled dislocations and subgrain boundaries consisting of dislocation arrays. These experimental results indicate that dynamic recovery and recrystallization play an important role in the high-strain-rate deformation process.
基金Project(2007CB613601) supported by the National Basic Research Program of ChinaProject(10C1095) supported by the Foundation of Hunan Educational Committee,China
文摘The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate solution.The main parameters,such as ammonia and ammonium sulphate concentrations,particle size,solid-to-liquid ratio and reaction temperature,were chosen in the experiments.The results show that the increase of temperature,concentrations of ammonia and ammonium sulphate is propitious to the leaching rate of copper ore.The leaching rate increases with the decrease of particle size and solid-to-liquid ratio.The leaching rate is controlled by the diffusion through the ash layer and the activation energy is determined to be 25.54 kJ/mol.A semi-empirical equation was proposed to describe the leaching kinetics.
文摘Various optical luminescence spectroscopic techniques were used to characterize the high T_c superconductor YBa_2Cu_3O_x.The emission bands reveal that Cu^(3+) coexist with Cu^(2+) and Cu^+ in this material.
文摘The influence of fabrication on the tensile and fatigue behavior of copper films manufactured by 3 kinds of fabrication methods was investigated. The tensile and high cycle fatigue tests were performed using the test machine developed by authors. Young's moduli (72, 71 and 69 GPa, respectively) are lower than the literature values (108-145 GPa), while the yield strengths were as high as 358, 350 and 346 MPa, respectively and the ultimate strengths as 462, 456 and 446 MPa, respectively. There is not much difference in the tensile properties of the 3 kinds of films. There is little difference in the fatigue properties of the 3 kinds of films but one of them has shorter fatigue life than others in high cycle region and longer fatigue life than others in low cycle region.
文摘The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leaching were considered. In the first stage, effects of flotation parameters including collector type, collector dosage, and pH and pulp density were examined. The results showed that over 80% copper recovery was achieved under the optimized flotation conditions while nickel recovery was lower than 30% due to its co-ex-istence with gangue minerals of pyrrhotite, pyrite and other clay minerals. In the second stage, key parameters, particularly concentration of sulfuric acid, temperature, pressure and leaching time were investigated to test the leaching efficiency of copper and nickel from the flotation concentrate with high pressure oxidative leaching (HPOL). A comparison was made between the leaching efficiencies of copper and nickel from flotation concentrates and mine tailing.
文摘The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated. The results show that the microstructure of the as-cast high chromium cast irons consists of retained austenite, martensite and M7C3 type eutectic carbide. When copper is added into high chromium cast irons, austenite and carbide contents are increased. The increased addition of copper content from 0% to 1.84% leads to the increase of austenite and carbide from 15.9% and 20.0% to 61.0% and 35.5%, respectively. In the process of sub-critical treatment, the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process, which causes the secondary hardening of the alloy under sub-critical treatment. High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.