Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collecte...Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collected.Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin.Insulin, glucagon, somatostatin, nestin, and cytokeratin 19 (CK19) of pancreatic tissues were observed by immunohistochemistry.Results At 9 weeks of gestation, pancreatic epithelial cells began to co-express insulin, glucagon, somatostatin, and CK19 before migration.Islet cells gradually congregated along with the increase of aging, and at 14 weeks of gestation histological examination showed islet formation.At 12 weeks of gestation, nestin-positive cells could be seen in the pancreatic mesenchyme.During early embryogenesis, islet cells of pancreatic ducts co-expressed insulin, glucagon, and somatostatin.During pancreatic regeneration after damage, nestin expression of islet cells increased.Conclusion In the early stage of embryogenesis, islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration.During tissue regeneration, pancreatic stem cells may differentiate and proliferate to form pancreatic islet.展开更多
One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannameL Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol (D1, D...One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannameL Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol (D1, D2, D3 and D4 with 0, 0.5%, 1% and 2% cholesterol, respectively) were fed to triplicate groups of L. vannamei shrimp (mean initial wet weight 0.8 mg) for 27 days. After the trial, shrimp fed the D1 diet had the best growth performance (final body weights: FBW; weight gain: WG; specific growth rate: SGR), while there was no significant difference between diet treatments with respect to survival. The whole body crude protein level in the shrimp decreased with the increase in dietary cholesterol levels, while the whole body crude lipid level in shrimps in the D4 diet treatment was significantly higher (P 〈 0.05) than in other diet treatments. Dietary analysis indicated that the D1 diet contained 0.92% cholesterol prior to supplementation, which may have satisfied the dietary cholesterol requirement of post-larval L. vannamei; excess dietary cholesterol may thus lead to adverse effects on the growth performance of post-larval shrimp.展开更多
BACKGROUND Paraganglioma/pheochromocytoma and medullary thyroid carcinoma can coexist and are often found in multiple endocrine neoplasia(MEN). However,very few cases highlight papillary thyroid carcinoma. We present ...BACKGROUND Paraganglioma/pheochromocytoma and medullary thyroid carcinoma can coexist and are often found in multiple endocrine neoplasia(MEN). However,very few cases highlight papillary thyroid carcinoma. We present herein a rare case of head and neck paraganglioma associated with papillary thyroid carcinoma.CASE SUMMARY A 51-year-old man presented to our department with right-sided neck swelling and hypertension. Physical examination showed neck masses with obvious pulsation. Concentrations of serum calcium, phosphorus, parathormone, thyroid stimulating hormone, free thyroxine, and calcitonin were within normal limits.Enhanced computed tomography revealed an irregular solid nodule, located in the carotid artery bifurcation. A low-density nodule of the thyroid isthmus with a spot-like dense shadow was also detected. The diagnosis of carotid body tumor was raised and an ultrasound-guided fine needle aspiration biopsy of the thyroid nodule revealed papillary thyroid carcinoma. The patient underwent surgery for lesion excision, total thyroidectomy, and neck dissection, and the pathology was reported as paraganglioma and papillary carcinoma. Genetic studies showed negative results for germline mutation of succinate dehydrogenase subunit D on 11q23. He was treated with ^(131)I after surgery and remained disease-free so far.CONCLUSION The presence of concomitant paraganglioma and thyroid papillary carcinoma could be either coincidental or a result of an unknown mutation.展开更多
The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centere...The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centered-cubic and body-centered-cubic phases,presenting similar mechanical behavior as the as-cast state.The yield and tensile strengths of the alloys could be dramatically enhanced to^1205 MPa and^1318 MPa after 50%rolling reduction,respectively.A power-law relationship was discovered between the strain-hardening exponent and rolling reduction.The tensile strengths of this dual-phase HEA with different cold rolling treatments were predicted,mainly based on the Hollomon relationship,by the strain-hardening exponent,and showed good agreement with the experimental results.展开更多
Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatm...Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatment time.Boronizing remarkably improved the surface hardness from HV 188 to HV 1265 after treating at 900°C for 9 h.Moreover,boronizing enhanced the yield strength of HEAs from 195 to 265 MPa but deteriorated the tensile ductility.Multiple crackings in the boride layers significantly decreased the plasticity.The insufficient work-hardening capacity essentially facilitated the plastic instability of the boronized HEAs.With decreasing substrate thickness,the fracture modes gradually transformed from dimples to quasi-cleavage and eventually to cleavage.展开更多
Zr-based bulk metallic glass matrix composites (BMGMCs) with a composition of Zr60.0Ti14.7Nb5.3Cu5.6Ni4.4- Be10.0 (at%) were fabricated by an innovative process, i.e., semisolid processing plus Bridgman solidifica...Zr-based bulk metallic glass matrix composites (BMGMCs) with a composition of Zr60.0Ti14.7Nb5.3Cu5.6Ni4.4- Be10.0 (at%) were fabricated by an innovative process, i.e., semisolid processing plus Bridgman solidification. Different morphologies, distributions, and volume fractions of the crystalline phases can be achieved by tailoring the withdrawal velocity. The largest fi-acture strain of Zr60.0Ti14.7Nb5.3Cu5.6Ni4.4Be10.0 (at%) composites with the withdrawal velocity of 1.0 mm/s was found to be 16.7%. The mechanism of plasticity improvement is mainly attributed to the interpenetrated structure of the crystalline phase, which greatly confines the rapid propagation of shear bands.展开更多
Two-dimensional polyacrylamide gel assisted laser desorption/ionization electrophoresis (2D-PAGE) and matrixtandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS), incorporated with online database searching,...Two-dimensional polyacrylamide gel assisted laser desorption/ionization electrophoresis (2D-PAGE) and matrixtandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS), incorporated with online database searching, were performed to investigate differential proteins of breast cancer and adjacent normal breast tissues. Considering that serum albumin is abundantly presented in normal control samples, 15 differential spots detected in 11 out of 12 (91.7%) breast cancer samples were identified by online SIENA-2DPAGE database searching and MALDI-TOF/TOF-MS analysis. The results indicate that pathological changes of breast cancer are concerned with augmentation of substance metabolism, promotion of proteolytic activity, decline of activity of some inhibitors of enzymes, and so on. Some important proteins involved in the pathological process of breast cancer with changed expression may be useful biomarkers, such as alpha-l-antitrypsin, EF- 1-beta, cathepsin D, TCTP, SMT3A, RPS12, and PSMA1, among which SMT3A, RPSl2, and PSMA1 were first reported for breast cancer in this study.展开更多
High-/medium-entropy stainless alloys(HESAs/MESAs)are a new kind of alloys with great potential to combine excellent properties from high-/medium-entropy alloys(HEAs/MEAs)and stainless steels.A CrFeNi MESA was chosen ...High-/medium-entropy stainless alloys(HESAs/MESAs)are a new kind of alloys with great potential to combine excellent properties from high-/medium-entropy alloys(HEAs/MEAs)and stainless steels.A CrFeNi MESA was chosen to investigate its microstructures and mechanical behaviors.After homogenization,the strength and ductility of CrFeNi MESAs with single-phase face-centered-cubic(fcc)structure were higher compared with those of Fe_(100−x-y)Cr_(x)Ni_(y)austenitic stainless steels.Cr-rich body-centered-cubic(bcc)precipitates and heterogeneous structure were introduced by cold rolling and annealing at 800℃.Rolling at 700℃ results in higher dislocation density and the occurrence of lamellar Cr-rich bcc precipitates.High-density dislocations and fcc grains with heterogeneous structure,together with Cr-rich bcc precipitates,contribute to a yield strength improvement of about 50 MPa,and appreciable tensile yield strength of~540 MPa and fracture strain of~20%are obtained.It reveals that not only compositional variations but also grain size and phase structure tuning can be utilized for achieving desired mechanical properties.展开更多
The corrosion behavior study was conducted on a novel Fe77 Mo5P9C7.5 B1.5 in-situ metallic glass matrix composite (MGMC). This composite sample was developed by introduction of bcc a-Fe dendrites as reinforcing phas...The corrosion behavior study was conducted on a novel Fe77 Mo5P9C7.5 B1.5 in-situ metallic glass matrix composite (MGMC). This composite sample was developed by introduction of bcc a-Fe dendrites as reinforcing phase. The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304L and 2304L stainless steels. The corrosion resistance of MGMCs in H2SO4 solution shows inferior to that of other Fe-based alloys. Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs. The possible underlying reasons can be the inhomogeneity induced by the precipitation of a-Fe dendrites in the MGMCs.展开更多
Animal bone was employed as raw material to prepare hierarchical porous carbon by KOH activation. Rare metal selenium(Se) was encapsulated into hierarchical porous carbon successfully for the cathode material of Li...Animal bone was employed as raw material to prepare hierarchical porous carbon by KOH activation. Rare metal selenium(Se) was encapsulated into hierarchical porous carbon successfully for the cathode material of Li–Se battery, achieving the transformation of waste into energy,protecting environment and reducing the spread of the disease. Animal bone porous carbon(ABPC) acquires a specific surface area of 1244.7903 m^2·g^-1 and a pore volume of 0.594184 cm^3·g^-1. The composite Se/ABPC with 51 wt%Se was tested as a novel cathode for Li–Se batteries. The results show that Se/ABPC exhibits high specific capacity,good cycling stability and current-rate performance; at 0.1C,the composite Se/ABPC delivers a high reversible capacity of 705 mAh·g^-1 in the second cycle and 591 mAh·g^-1 after 98 cycles. Even at the current density of 2.0C, it can still maintain at a reversible capacity of 485 mAh·g^-1. The excellent electrochemical properties benefit from the high electron conductivity and the carbon with unique hierarchical porous structure. ABPC can be a promising carbon matrix for Li–Se batteries.展开更多
The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and...The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and rainwater.The results showed that the average value of the frictional coefficients and micro-hardness ascended with increasing the normal load,while the wear rate showed a trend of decline under the dry condition.The electrochemical test results showed that the surface of samples was pitting corroded in the rainwater.The matrices were corroded first.Then the dendrites were exposed,leading to the damage of the surface.Both the frictional coefficients and wear rate of the composite in the rainwater were larger than those under the dry condition,primarily owing to the corrosion of chloride ions on the worn surface.The wear mechanisms of composites were mainly adhesive wear,accompanied by the abrasive wear under the dry condition and corrosive wear in the rainwater.The composites have higher wear resistance both under the dry condition and rainwater due to the lower wear rate.展开更多
A systematic research on the tribological characteristics of Ti48Zr20Nb12Cu5Be15 metallic glass matrix composites was performed under different normal loads in dry condition and simulated seawater. The wear rate decre...A systematic research on the tribological characteristics of Ti48Zr20Nb12Cu5Be15 metallic glass matrix composites was performed under different normal loads in dry condition and simulated seawater. The wear rate decreased with the increase in normal load under dry and simulated seawater conditions. The friction coefficient was lower in the dry condition than in the simulated seawater. The composite showed better wear resistance at lower loads (3, 5 and 10 N) hut poor wear resistance at higher loads (15 and 17 N) in the simulated seawater. The analysis of the worn surface illustrated that the wear mechanism in dry condition was plastic deformation, adhesive wear and abrasive wear at 3 and 5 N, while it was abrasive wear and adhesive wear at 10, 15 and 17 N. The wear mechanism in simulated seawater was abrasive wear, plastic deformation and adhesive wear at 3 N, adhesive wear at 10 N, and abrasive wear at 5, 15 and 17 N. At the same time, the corrosion occurred during wear tests in the simulated seawater.展开更多
The addition of hexagonal-close-packed(hcp)non-rare-earth elements Zr,Ti and Co,to the 10-component hep rare-earth-based high-entropy alloys(HEAs)with a composition of ScYLaNdGdTbDyHoErLuX(X=Zr,Co and Ti)was investiga...The addition of hexagonal-close-packed(hcp)non-rare-earth elements Zr,Ti and Co,to the 10-component hep rare-earth-based high-entropy alloys(HEAs)with a composition of ScYLaNdGdTbDyHoErLuX(X=Zr,Co and Ti)was investigated.The enthalpy of mixing between elements was found to have a significant effect on the formation of phases.The addition of Co combines with elements that had a strong chemical affinity to form intermetallic compounds by the effect of enthalpy.Ti was added with all elements with poor chemical affinity and exhibited rejection to form a phase alone.These were the two terminal manifestations of the role of enthalpy over entropy.Part of Zr was soluble in the matrix under the action of entropy,while the other part had a greater affinity for Sc than the other elements to form a precipitate under the action of enthalpy.This was the result of the local balance between the effect of enthalpy and entropy.The solid solution of the elements had different degrees of strengthening effect,among which Zr had the most excellent strengthening effect from 185 to 355 MPa,so the solid solution strengthening model and precipitation strengthening model were proposed to predict the strength of the alloy with the addition of Zr effectively.展开更多
The microstructures and tension properties of Fe_(50)Mn_(20)Cr_(20)Ni_(10) medium entropy alloy(MEA)were investigated,which was produced by vacuum induction melting and subsequently was homogenized at 1200 C for 6 h.M...The microstructures and tension properties of Fe_(50)Mn_(20)Cr_(20)Ni_(10) medium entropy alloy(MEA)were investigated,which was produced by vacuum induction melting and subsequently was homogenized at 1200 C for 6 h.Microstructure characterization shows the single-phase solid solution with face-centered cubic structure by means of transmission electron microscopy and scanning electron microscopy combined with energy disperse spectroscopy.Our Fe-MEA has an ultimate tensile strength of 550±10 MPa and a high strain hardening exponent,n,of 0.41 as well as a higher ductility(60%)than those of CrMnFeCoNi alloy.The single-phase solid solution deforms plastically via dislocations and twins.Twin boundaries associated with deformation twinning impede dislocation motion,enhancing the strain hardening capacity.This article focuses on the insights into the concept of Fe-MEAs and provides a potential direction for the future development of high entropy alloys and MEAs.展开更多
文摘Objective To explore the mechanisms of differentiation and development of pancreatic endocrine cells as well as pancreatic regeneration.Methods Human embryonic pancreatic tissue at 7-14 weeks of gestation was collected.Diabetes mellitus rat model was induced with 65 mg/kg of streptozotocin.Insulin, glucagon, somatostatin, nestin, and cytokeratin 19 (CK19) of pancreatic tissues were observed by immunohistochemistry.Results At 9 weeks of gestation, pancreatic epithelial cells began to co-express insulin, glucagon, somatostatin, and CK19 before migration.Islet cells gradually congregated along with the increase of aging, and at 14 weeks of gestation histological examination showed islet formation.At 12 weeks of gestation, nestin-positive cells could be seen in the pancreatic mesenchyme.During early embryogenesis, islet cells of pancreatic ducts co-expressed insulin, glucagon, and somatostatin.During pancreatic regeneration after damage, nestin expression of islet cells increased.Conclusion In the early stage of embryogenesis, islet cells of primary pancreatic ducts can be differentiated to multipotential endocrine cells before migration.During tissue regeneration, pancreatic stem cells may differentiate and proliferate to form pancreatic islet.
基金supported by Fund of National Modern Industrial Technology System of Shrimp (nycytx-46)Special Scientific Research Funds for Central Non-profit Institutes, South China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences (2009TS29, 2010YD02, 2010TS04 and 2011YD01)+2 种基金 the Project of Science and Technology of Guangdong Province(2011A020202007)the Project of Key Science and Technology of Hainan Province (ZDXM20100028)the State 863 Project (2012AA10A409)
文摘One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannameL Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol (D1, D2, D3 and D4 with 0, 0.5%, 1% and 2% cholesterol, respectively) were fed to triplicate groups of L. vannamei shrimp (mean initial wet weight 0.8 mg) for 27 days. After the trial, shrimp fed the D1 diet had the best growth performance (final body weights: FBW; weight gain: WG; specific growth rate: SGR), while there was no significant difference between diet treatments with respect to survival. The whole body crude protein level in the shrimp decreased with the increase in dietary cholesterol levels, while the whole body crude lipid level in shrimps in the D4 diet treatment was significantly higher (P 〈 0.05) than in other diet treatments. Dietary analysis indicated that the D1 diet contained 0.92% cholesterol prior to supplementation, which may have satisfied the dietary cholesterol requirement of post-larval L. vannamei; excess dietary cholesterol may thus lead to adverse effects on the growth performance of post-larval shrimp.
文摘BACKGROUND Paraganglioma/pheochromocytoma and medullary thyroid carcinoma can coexist and are often found in multiple endocrine neoplasia(MEN). However,very few cases highlight papillary thyroid carcinoma. We present herein a rare case of head and neck paraganglioma associated with papillary thyroid carcinoma.CASE SUMMARY A 51-year-old man presented to our department with right-sided neck swelling and hypertension. Physical examination showed neck masses with obvious pulsation. Concentrations of serum calcium, phosphorus, parathormone, thyroid stimulating hormone, free thyroxine, and calcitonin were within normal limits.Enhanced computed tomography revealed an irregular solid nodule, located in the carotid artery bifurcation. A low-density nodule of the thyroid isthmus with a spot-like dense shadow was also detected. The diagnosis of carotid body tumor was raised and an ultrasound-guided fine needle aspiration biopsy of the thyroid nodule revealed papillary thyroid carcinoma. The patient underwent surgery for lesion excision, total thyroidectomy, and neck dissection, and the pathology was reported as paraganglioma and papillary carcinoma. Genetic studies showed negative results for germline mutation of succinate dehydrogenase subunit D on 11q23. He was treated with ^(131)I after surgery and remained disease-free so far.CONCLUSION The presence of concomitant paraganglioma and thyroid papillary carcinoma could be either coincidental or a result of an unknown mutation.
基金the Natural Science Foundation of Shanxi Province,China(Nos.201901D111105 and 201901D111114)Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi Province,China(2019)+2 种基金the Opening Project of the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(No.KFJJ20-13M)the Graduate Science and Technology Innovation Fund Project of Shanxi Province,China(No.2019BY044)the State Key Lab of Advanced Metals and Materials of China(No.2020-Z09).
文摘The evolution of the microstructure and tensile properties of dual-phase Al0.6CoCrFeNi high-entropy alloys(HEAs)subjected to cold rolling was investigated.The homogenized Al0.6CoCrFeNi alloys consisted of face-centered-cubic and body-centered-cubic phases,presenting similar mechanical behavior as the as-cast state.The yield and tensile strengths of the alloys could be dramatically enhanced to^1205 MPa and^1318 MPa after 50%rolling reduction,respectively.A power-law relationship was discovered between the strain-hardening exponent and rolling reduction.The tensile strengths of this dual-phase HEA with different cold rolling treatments were predicted,mainly based on the Hollomon relationship,by the strain-hardening exponent,and showed good agreement with the experimental results.
基金National Key Laboratory for Remanufacturing,Academy of Armored Forces Engineering(No.61420050204)the Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi,China(No.2019BY044)Jinxiong Hou would like to acknowledge the financial support from the Graduate Science and Technology Innovation Fund Project of Shanxi,China(No.2019BY044).
文摘Using thermochemical treatments,boronized layers were successfully prepared on Al0.25CoCrFeNi high-entropy alloys(HEAs).The thickness of the boronized layers ranged widely from 20 to 50μm,depending on the heat treatment time.Boronizing remarkably improved the surface hardness from HV 188 to HV 1265 after treating at 900°C for 9 h.Moreover,boronizing enhanced the yield strength of HEAs from 195 to 265 MPa but deteriorated the tensile ductility.Multiple crackings in the boride layers significantly decreased the plasticity.The insufficient work-hardening capacity essentially facilitated the plastic instability of the boronized HEAs.With decreasing substrate thickness,the fracture modes gradually transformed from dimples to quasi-cleavage and eventually to cleavage.
基金financial support of the National Natural Science Foundation of China (Nos. 51101110 and 51105267)the Youth Science Foundation of Shanxi Province, China (Nos. 2012021018-1 and 2012021013-1)the Research Project Supported by Shanxi Scholarship Council of China (Nos. 2012-032 and 2012-030)
文摘Zr-based bulk metallic glass matrix composites (BMGMCs) with a composition of Zr60.0Ti14.7Nb5.3Cu5.6Ni4.4- Be10.0 (at%) were fabricated by an innovative process, i.e., semisolid processing plus Bridgman solidification. Different morphologies, distributions, and volume fractions of the crystalline phases can be achieved by tailoring the withdrawal velocity. The largest fi-acture strain of Zr60.0Ti14.7Nb5.3Cu5.6Ni4.4Be10.0 (at%) composites with the withdrawal velocity of 1.0 mm/s was found to be 16.7%. The mechanism of plasticity improvement is mainly attributed to the interpenetrated structure of the crystalline phase, which greatly confines the rapid propagation of shear bands.
文摘Two-dimensional polyacrylamide gel assisted laser desorption/ionization electrophoresis (2D-PAGE) and matrixtandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS), incorporated with online database searching, were performed to investigate differential proteins of breast cancer and adjacent normal breast tissues. Considering that serum albumin is abundantly presented in normal control samples, 15 differential spots detected in 11 out of 12 (91.7%) breast cancer samples were identified by online SIENA-2DPAGE database searching and MALDI-TOF/TOF-MS analysis. The results indicate that pathological changes of breast cancer are concerned with augmentation of substance metabolism, promotion of proteolytic activity, decline of activity of some inhibitors of enzymes, and so on. Some important proteins involved in the pathological process of breast cancer with changed expression may be useful biomarkers, such as alpha-l-antitrypsin, EF- 1-beta, cathepsin D, TCTP, SMT3A, RPS12, and PSMA1, among which SMT3A, RPSl2, and PSMA1 were first reported for breast cancer in this study.
基金support of the Natural Science Foundation of Shanxi Province,China(Nos.201901D111105,201901D111114)Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi(2019)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology,No.KFJJ20-13 M).
文摘High-/medium-entropy stainless alloys(HESAs/MESAs)are a new kind of alloys with great potential to combine excellent properties from high-/medium-entropy alloys(HEAs/MEAs)and stainless steels.A CrFeNi MESA was chosen to investigate its microstructures and mechanical behaviors.After homogenization,the strength and ductility of CrFeNi MESAs with single-phase face-centered-cubic(fcc)structure were higher compared with those of Fe_(100−x-y)Cr_(x)Ni_(y)austenitic stainless steels.Cr-rich body-centered-cubic(bcc)precipitates and heterogeneous structure were introduced by cold rolling and annealing at 800℃.Rolling at 700℃ results in higher dislocation density and the occurrence of lamellar Cr-rich bcc precipitates.High-density dislocations and fcc grains with heterogeneous structure,together with Cr-rich bcc precipitates,contribute to a yield strength improvement of about 50 MPa,and appreciable tensile yield strength of~540 MPa and fracture strain of~20%are obtained.It reveals that not only compositional variations but also grain size and phase structure tuning can be utilized for achieving desired mechanical properties.
基金Item Sponsored by National Natural Science Foundation of China(51401141)Science Foundation of Shanxi Province of China(2013011010-1)Youth Science Foundation of Shanxi Province of China(2014021017-3)
文摘The corrosion behavior study was conducted on a novel Fe77 Mo5P9C7.5 B1.5 in-situ metallic glass matrix composite (MGMC). This composite sample was developed by introduction of bcc a-Fe dendrites as reinforcing phase. The corrosion behavior of this composite was compared to its monolithic counterpart and other Fe-based alloys such as 304L and 2304L stainless steels. The corrosion resistance of MGMCs in H2SO4 solution shows inferior to that of other Fe-based alloys. Experiments suggest that Fe-BMGs samples possess better corrosion resistance property than that of Fe-MGMCs. The possible underlying reasons can be the inhomogeneity induced by the precipitation of a-Fe dendrites in the MGMCs.
基金financially supported by the National Natural Science Foundation of China(Nos.51272156,21373137 and 21333007)the City Committee of Science and Technology Project of Shanghai(No.14JC1491800)the New Century Excellent Talents in University(Nos.NCET-13-0371)
文摘Animal bone was employed as raw material to prepare hierarchical porous carbon by KOH activation. Rare metal selenium(Se) was encapsulated into hierarchical porous carbon successfully for the cathode material of Li–Se battery, achieving the transformation of waste into energy,protecting environment and reducing the spread of the disease. Animal bone porous carbon(ABPC) acquires a specific surface area of 1244.7903 m^2·g^-1 and a pore volume of 0.594184 cm^3·g^-1. The composite Se/ABPC with 51 wt%Se was tested as a novel cathode for Li–Se batteries. The results show that Se/ABPC exhibits high specific capacity,good cycling stability and current-rate performance; at 0.1C,the composite Se/ABPC delivers a high reversible capacity of 705 mAh·g^-1 in the second cycle and 591 mAh·g^-1 after 98 cycles. Even at the current density of 2.0C, it can still maintain at a reversible capacity of 485 mAh·g^-1. The excellent electrochemical properties benefit from the high electron conductivity and the carbon with unique hierarchical porous structure. ABPC can be a promising carbon matrix for Li–Se batteries.
基金Item Sponsored by National Natural Science Foundation of China(51371122,51401141)Program for the Innovative Talents of Higher Learning Institutions of Shanxi Province of China(2013)Youth Science Foundation of Shanxi Province of China(2014021017-3)
文摘The tribological properties of the in-situ dendrite-reinforced metallic glass matrix composite(Ti42Zr22V14-Cu5Be17)prepared by copper mould casting were analyzed at different normal loads under the dry condition and rainwater.The results showed that the average value of the frictional coefficients and micro-hardness ascended with increasing the normal load,while the wear rate showed a trend of decline under the dry condition.The electrochemical test results showed that the surface of samples was pitting corroded in the rainwater.The matrices were corroded first.Then the dendrites were exposed,leading to the damage of the surface.Both the frictional coefficients and wear rate of the composite in the rainwater were larger than those under the dry condition,primarily owing to the corrosion of chloride ions on the worn surface.The wear mechanisms of composites were mainly adhesive wear,accompanied by the abrasive wear under the dry condition and corrosive wear in the rainwater.The composites have higher wear resistance both under the dry condition and rainwater due to the lower wear rate.
基金The authors would like to acknowledge the financial support of National Natural Science Foundation of China (No. 51401141).
文摘A systematic research on the tribological characteristics of Ti48Zr20Nb12Cu5Be15 metallic glass matrix composites was performed under different normal loads in dry condition and simulated seawater. The wear rate decreased with the increase in normal load under dry and simulated seawater conditions. The friction coefficient was lower in the dry condition than in the simulated seawater. The composite showed better wear resistance at lower loads (3, 5 and 10 N) hut poor wear resistance at higher loads (15 and 17 N) in the simulated seawater. The analysis of the worn surface illustrated that the wear mechanism in dry condition was plastic deformation, adhesive wear and abrasive wear at 3 and 5 N, while it was abrasive wear and adhesive wear at 10, 15 and 17 N. The wear mechanism in simulated seawater was abrasive wear, plastic deformation and adhesive wear at 3 N, adhesive wear at 10 N, and abrasive wear at 5, 15 and 17 N. At the same time, the corrosion occurred during wear tests in the simulated seawater.
基金financially supported by the Natural Science Foundation of Shanxi Province,China (Nos. 201901D111105 and 201901D111114)the Key Research and Development Program of Shanxi Province (No.202102050201008)+1 种基金the National Science Foundation,United States (Nos.DMR-1611180 and 1809640)the U.S.Army Research Office (Nos.W911NF-131-0438 and W911NF-19-2-0049)
文摘The addition of hexagonal-close-packed(hcp)non-rare-earth elements Zr,Ti and Co,to the 10-component hep rare-earth-based high-entropy alloys(HEAs)with a composition of ScYLaNdGdTbDyHoErLuX(X=Zr,Co and Ti)was investigated.The enthalpy of mixing between elements was found to have a significant effect on the formation of phases.The addition of Co combines with elements that had a strong chemical affinity to form intermetallic compounds by the effect of enthalpy.Ti was added with all elements with poor chemical affinity and exhibited rejection to form a phase alone.These were the two terminal manifestations of the role of enthalpy over entropy.Part of Zr was soluble in the matrix under the action of entropy,while the other part had a greater affinity for Sc than the other elements to form a precipitate under the action of enthalpy.This was the result of the local balance between the effect of enthalpy and entropy.The solid solution of the elements had different degrees of strengthening effect,among which Zr had the most excellent strengthening effect from 185 to 355 MPa,so the solid solution strengthening model and precipitation strengthening model were proposed to predict the strength of the alloy with the addition of Zr effectively.
基金the Natural Science Foundation of Shanxi Province,China(Nos.201901DI11105 and 201901D111114)Transformation of Scientific and Technological Achievements Programs of Higher Education Institutions in Shanxi(2019)+2 种基金State Key Lab of Advanced Metals and Materials of China(Grant No.2020-Z09)the opening project of the State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)the opening project number is KFJJ20-13M.
文摘The microstructures and tension properties of Fe_(50)Mn_(20)Cr_(20)Ni_(10) medium entropy alloy(MEA)were investigated,which was produced by vacuum induction melting and subsequently was homogenized at 1200 C for 6 h.Microstructure characterization shows the single-phase solid solution with face-centered cubic structure by means of transmission electron microscopy and scanning electron microscopy combined with energy disperse spectroscopy.Our Fe-MEA has an ultimate tensile strength of 550±10 MPa and a high strain hardening exponent,n,of 0.41 as well as a higher ductility(60%)than those of CrMnFeCoNi alloy.The single-phase solid solution deforms plastically via dislocations and twins.Twin boundaries associated with deformation twinning impede dislocation motion,enhancing the strain hardening capacity.This article focuses on the insights into the concept of Fe-MEAs and provides a potential direction for the future development of high entropy alloys and MEAs.