Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on ...Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on dislocation behavior is unclear.Here,using tensile testing,in-situ microscopy and nanomechanical testing,the behavior of dislocations in dilute Nb-Si alloys,containing from 0 at.%to 0.8 at.%Si,is investigated.We show that the hardness,strength and strain hardening rate increase from two to four times,while the uniform elongation in tension only reduces 50%as the Si content increases.Dislocations evolve from complex entangled patterns in Nb to parallel long-straight screw dislocation-dominated structures in Nb-Si alloys.In-situ indentation reveals that the origins of the marked harden-ing in Nb-Si alloy are the reduction of dislocation mobility and cross-slip propensity.Large densities of dislocation debris-superjogs and loops introduced throughout the sample during warm rolling and an-nealing are found to provide active internal dislocation sources,which explain the minimal ductility loss seen in these Nb-Si alloys.These findings can help guide the alloy design of high-performance refractory materials for extreme temperature applications.展开更多
Objective During 2003-2005, an outbreak of meningitis due to Neisseria meningitidis serogroup C occurred in China. With the aim to find strain clues result in the final epidemics, the ancestral strain 053442, a clinic...Objective During 2003-2005, an outbreak of meningitis due to Neisseria meningitidis serogroup C occurred in China. With the aim to find strain clues result in the final epidemics, the ancestral strain 053442, a clinical isolate, and a carrier strain 053426 with different gene type were analyzed. Methods Clinical strain 053442 and carrier strain 053426 were cultured on GC agar plates under the same condition. Two-dimensional electrophoresis was performed using the pH 3–10 nonlinear IPG strips of 24 cm length, and all the protein spots were identified by matrix-assisted laser desorption/ionization time of flight spectrometry. Results 502 and 380 protein spots were identified in 053426 and 053442 respectively, relating to 266 and 202 different genes covering a wide range of cellular functions. The express volume and number of proteins involved in energy metabolism, protein synthesis and amino acid biosynthesis in 053426 were higher than in 053442. Virulence factor Opa, Opc and a series of proteins involved in pilus assembly and retraction were identified in 053442, which appear to be of primary importance in colonization and invasion of human cells. Compared to 053442, virulence protein species were less in 053426, with lower express volumes too. No Opa and Opc were detected in 053426. Conclusion The different protein expression profiles of the clinical strain 053442 and carrier strain 053426 in the present study provide some clues of the different pathogenicity of the two strains, which may account for result in the final epidemics.展开更多
基金supported by the National Natu-ral Science Foundation of China(Nos.51971170 and 51922082)the Shaanxi Science&Technology Innovation Project(No.2022QFY10-03)+1 种基金the assistance of Dr.Ping-Jiong Yang during the earlier stage of this project.S.O.and S.S.were supported by the Ministry of Education,Culture,Sport,Sci-ence and Technology of Japan programs(Nos.JPMXP1122684766,JPMXP1020230325,and JPMXP1020230327)JSPS KAKENHI(No.JP23H00161).S.S.was supported by JSPS KAKENHI(Nos.21K14042 and 22H05283).S.S.and S.O.wish to thank Dr.Tomo-hito Tsuru for discussions regarding NNP creation.
文摘Niobium(Nb)is sensitive to even minute quantities of silicon(Si)solutes,which are known to induce pronounced hardening.However,the underlying mechanism for hardening remains elusive since the ef-fect of Si solutes on dislocation behavior is unclear.Here,using tensile testing,in-situ microscopy and nanomechanical testing,the behavior of dislocations in dilute Nb-Si alloys,containing from 0 at.%to 0.8 at.%Si,is investigated.We show that the hardness,strength and strain hardening rate increase from two to four times,while the uniform elongation in tension only reduces 50%as the Si content increases.Dislocations evolve from complex entangled patterns in Nb to parallel long-straight screw dislocation-dominated structures in Nb-Si alloys.In-situ indentation reveals that the origins of the marked harden-ing in Nb-Si alloy are the reduction of dislocation mobility and cross-slip propensity.Large densities of dislocation debris-superjogs and loops introduced throughout the sample during warm rolling and an-nealing are found to provide active internal dislocation sources,which explain the minimal ductility loss seen in these Nb-Si alloys.These findings can help guide the alloy design of high-performance refractory materials for extreme temperature applications.
基金supported by a grant (the Key Technologies R&D Program 2005BA711A09) from the Ministry of Science and Technology, of China
文摘Objective During 2003-2005, an outbreak of meningitis due to Neisseria meningitidis serogroup C occurred in China. With the aim to find strain clues result in the final epidemics, the ancestral strain 053442, a clinical isolate, and a carrier strain 053426 with different gene type were analyzed. Methods Clinical strain 053442 and carrier strain 053426 were cultured on GC agar plates under the same condition. Two-dimensional electrophoresis was performed using the pH 3–10 nonlinear IPG strips of 24 cm length, and all the protein spots were identified by matrix-assisted laser desorption/ionization time of flight spectrometry. Results 502 and 380 protein spots were identified in 053426 and 053442 respectively, relating to 266 and 202 different genes covering a wide range of cellular functions. The express volume and number of proteins involved in energy metabolism, protein synthesis and amino acid biosynthesis in 053426 were higher than in 053442. Virulence factor Opa, Opc and a series of proteins involved in pilus assembly and retraction were identified in 053442, which appear to be of primary importance in colonization and invasion of human cells. Compared to 053442, virulence protein species were less in 053426, with lower express volumes too. No Opa and Opc were detected in 053426. Conclusion The different protein expression profiles of the clinical strain 053442 and carrier strain 053426 in the present study provide some clues of the different pathogenicity of the two strains, which may account for result in the final epidemics.
