Metals in advanced nuclear reactors,such as W,often experience microcracks.However,the synergistic effects of high temperature,stress,and specialized structures can improve the self-healing ability of these metals.Mic...Metals in advanced nuclear reactors,such as W,often experience microcracks.However,the synergistic effects of high temperature,stress,and specialized structures can improve the self-healing ability of these metals.Microcrack healing is closely related to crack surface conditions.The order and disorder degree of crack surface atoms may affect crack stability.In this study,first-principles calculations,ab initio molecular dynamics,and surface thermodynamic theory were used to investigate the stability of grain boundary(GB)cracks at 0,293,and 373 K.We compared the energy densities,crack attraction energies,and atomic diffusion behaviors of crack surfaces atΣ3 GBs with those atΣ5 GBs.Adsorption on the nanocrack surface determines the critical nanocrack width.It was found that AlΣ3(111)nanocracks heal at high temperatures,and this healing behavior is closely related to the crack surface energy.Meanwhile,the GB cracks of W heal in an orderly manner at 573 and 1203 K.BY contrast,the GB cracks of Ti remain unhealed.Finally,a high-temperature nanocrack expansion model was developed and used to predict crack behavior under applied stress at different temperatures.展开更多
In this study,spent WO_(3)/V_(2)O_(5)-TiO_(2) catalysts used for selective catalytic reduction were treated by a hydrometallurgical process to comprehensively recover valuable metallic elements,such as W,V,and Ti.Al a...In this study,spent WO_(3)/V_(2)O_(5)-TiO_(2) catalysts used for selective catalytic reduction were treated by a hydrometallurgical process to comprehensively recover valuable metallic elements,such as W,V,and Ti.Al and Si impurities were preferentially removed by selective micro wave-assisted alkali leaching.W and V were leached by enhanced high-pressure leaching with efficiencies estimated at 95% and 81%.The leaching of W and V followed the nuclear shrinkage model controlled by the combination of product layer diffusion and interfacial chemical reaction.A synergistic extraction was applied to separate W and V using an extractant mixture of di-(2-ethylhexyl)phosphoric acid P204 and the primary amine N1923.The extraction efficiencies of V and W reached 86.5% and 6.3%,respectively,with a separation coefficient(V/W) of 95.30.The product was precipitated after extraction to yield ammonium paratung state(APT) and NH_(4)VO_(3).The TiO_(2)catalyst carrier residue meets commercial specifications for reuse.This comprehensive recovery process with the characteristics of high-pressure leaching and synergistic extraction realizes the resourceful utilization of the spent catalysts.展开更多
Objective To study the prevalence of different types of neural tube defects （NTDs） in Luliang Prefecture, Shanxi province, where the prevalence of NTDs is unusually high and the correlation between NTDs prevalence a...Objective To study the prevalence of different types of neural tube defects （NTDs） in Luliang Prefecture, Shanxi province, where the prevalence of NTDs is unusually high and the correlation between NTDs prevalence and patterns. Methods A surveillance population-based birth defects was performed in Luliang Prefecture, Shanxi province. Results The results of our study showed that the prevalence of NTDs was 2-fold higher in Luliang Prefecture than in other areas of Shanxi province. Unusual patterns of NTDs were found, however, multiple NTDs were relatively common in Luliang Prefecture, accounting for over 13% of all NTDs cases in China. Conclusion The prevalence of NTDs is associated with its patterns.展开更多
Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these ...Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these pathogens in epidemiology, consequence of birth defects, and the possible mechanisms in the progress of birth defects, and the interventions to prevent or treat these pathogens?infections are described. The infections caused by rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. are common, yet they are proved to be fatal during the pregnant period, especially during the first trimester. These infections may cause sterility, abortion, stillbirth, low birth weight, and affect multiple organs that may induce loss of hearing and vision, even fetal deformity and the long-term effects. These pathogens?infections may influence the microenvironment of placenta, including levels of enzymes and cytokines, and affect chondriosome that may induce the progress of birth defect. Early diagnosis of infections during pregnancy should be strengthened. There are still many things to be settled, such as the molecular mechanisms of birth defects, the effective vaccines to certain pathogens. Birth defect researches in terms of etiology and the development of applicable and sensitive pathogen detection technology and methods are imperative.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12175323,11832019,and 11705264)project supported by the State Key Laboratory of Powder Metallurgy,Central South University,Guangdong Basic and Applied Basic Research Foundation(2023A1515012692)the National Natural Science Foundation of China Original Exploration Project(12150001).
文摘Metals in advanced nuclear reactors,such as W,often experience microcracks.However,the synergistic effects of high temperature,stress,and specialized structures can improve the self-healing ability of these metals.Microcrack healing is closely related to crack surface conditions.The order and disorder degree of crack surface atoms may affect crack stability.In this study,first-principles calculations,ab initio molecular dynamics,and surface thermodynamic theory were used to investigate the stability of grain boundary(GB)cracks at 0,293,and 373 K.We compared the energy densities,crack attraction energies,and atomic diffusion behaviors of crack surfaces atΣ3 GBs with those atΣ5 GBs.Adsorption on the nanocrack surface determines the critical nanocrack width.It was found that AlΣ3(111)nanocracks heal at high temperatures,and this healing behavior is closely related to the crack surface energy.Meanwhile,the GB cracks of W heal in an orderly manner at 573 and 1203 K.BY contrast,the GB cracks of Ti remain unhealed.Finally,a high-temperature nanocrack expansion model was developed and used to predict crack behavior under applied stress at different temperatures.
基金financially supported by Beijing Natural Science Foundation (No. 2222049)the National Natural Science Foundation of China (Nos. 52025042 and 51621003)National Key R&D Program of China (No. 2018YFC1901700)。
文摘In this study,spent WO_(3)/V_(2)O_(5)-TiO_(2) catalysts used for selective catalytic reduction were treated by a hydrometallurgical process to comprehensively recover valuable metallic elements,such as W,V,and Ti.Al and Si impurities were preferentially removed by selective micro wave-assisted alkali leaching.W and V were leached by enhanced high-pressure leaching with efficiencies estimated at 95% and 81%.The leaching of W and V followed the nuclear shrinkage model controlled by the combination of product layer diffusion and interfacial chemical reaction.A synergistic extraction was applied to separate W and V using an extractant mixture of di-(2-ethylhexyl)phosphoric acid P204 and the primary amine N1923.The extraction efficiencies of V and W reached 86.5% and 6.3%,respectively,with a separation coefficient(V/W) of 95.30.The product was precipitated after extraction to yield ammonium paratung state(APT) and NH_(4)VO_(3).The TiO_(2)catalyst carrier residue meets commercial specifications for reuse.This comprehensive recovery process with the characteristics of high-pressure leaching and synergistic extraction realizes the resourceful utilization of the spent catalysts.
基金supported by the Major State Basic Research and Development Program of China "973 Program" (No.2007CB511901)special for National Postdoctoral fund (200801016)+2 种基金National Health Baby Promotion Program (No. FP2000NO13)Education Ministry Key Program (No. 02185)National Yangzi Scholar Program, 211 and 985 Projects of Peking University (No. 20020903)
文摘Objective To study the prevalence of different types of neural tube defects （NTDs） in Luliang Prefecture, Shanxi province, where the prevalence of NTDs is unusually high and the correlation between NTDs prevalence and patterns. Methods A surveillance population-based birth defects was performed in Luliang Prefecture, Shanxi province. Results The results of our study showed that the prevalence of NTDs was 2-fold higher in Luliang Prefecture than in other areas of Shanxi province. Unusual patterns of NTDs were found, however, multiple NTDs were relatively common in Luliang Prefecture, accounting for over 13% of all NTDs cases in China. Conclusion The prevalence of NTDs is associated with its patterns.
基金the National Natural Science Foundation of China(No. 21102179)Fundamental Research Funds for the Central Universities(No.JKZ2011011) for the financial support
文摘Received 2 December 2012 Received in revised form 21 December 2012 Accepted 27 December 2012 Available online 4 February 2013
基金This work was supported by grants 2001CB5103 from the National "973" Programm of Ministry of Scientific and Technology of China 30025042, 30070790 from National Natural Science Foundation of China 02158, "985","211"projects of Ministry of Education and Peking University
文摘Intrauterine infection is an important cause of some birth defects worldwide. The most common pathogens include rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. General information about these pathogens in epidemiology, consequence of birth defects, and the possible mechanisms in the progress of birth defects, and the interventions to prevent or treat these pathogens?infections are described. The infections caused by rubella virus, cytomegaloviurs, ureaplasma urealyticum, toxoplasma, etc. are common, yet they are proved to be fatal during the pregnant period, especially during the first trimester. These infections may cause sterility, abortion, stillbirth, low birth weight, and affect multiple organs that may induce loss of hearing and vision, even fetal deformity and the long-term effects. These pathogens?infections may influence the microenvironment of placenta, including levels of enzymes and cytokines, and affect chondriosome that may induce the progress of birth defect. Early diagnosis of infections during pregnancy should be strengthened. There are still many things to be settled, such as the molecular mechanisms of birth defects, the effective vaccines to certain pathogens. Birth defect researches in terms of etiology and the development of applicable and sensitive pathogen detection technology and methods are imperative.
