The mitogen-activated protein kinase(MAPK)cascade is important in stress signal transduction and plant development.In the present study,we identified a rice(Oryza sativa L.)mutant with reduced fertility,Oryza sativa m...The mitogen-activated protein kinase(MAPK)cascade is important in stress signal transduction and plant development.In the present study,we identified a rice(Oryza sativa L.)mutant with reduced fertility,Oryza sativa mitogen-activated protein kinase 6(osmapk6),which harbored a mutated MAPK gene.Scanning and transmission electron microscopy,quantitative RT-PCR analysis,TUNEL assays,RNA in situ hybridization,longitudinal and transverse histological sectioning,and map-based cloning were performed to characterize the osmapk6 mutant.The gene OsMAPK6 was expressed throughout the plant but predominantly in the microspore mother cells,tapetal cells,and microspores in the anther sac.Compared with the wild type,the total number of microspores was reduced in the osmapk6 mutant.The formation of microspore mother cells was reduced in the osmapk6 anther sac at an early stage of anther development,which was the primary reason for the decrease in the total number of microspores.Programmed cell death of some tapetal cells was delayed in osmapk6 anthers and affected exine formation in neighboring microspores.These results suggest that OsMAPK6 plays pivotal roles in microspore mother cell formation and tapetal cell degradation.展开更多
Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a com...Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a complex service condition,which widely exists in the field of national defense,military and industrial application.Therefore,the dynamic deformation behavior of the Cu-20Ag alloy was investigated by Split Hopkinson Pressure Bar(SHPB)with the strain rates of 1000-25000 s^(-1),high-speed hydraulic servo material testing machine with the strain rates of 1-500 s^(-1).The effect of strain rate on flow stress and adiabatic shear sensitivity was analyzed.The results show that the increase of strain rate will increase the flow stress and critical strain,that is to say,the increase of strain rate will reduce the adiabatic shear sensitivity of the Cu-20Ag alloy.The Cu-Ag interface has obvious orientation relationship with;(111)_(Cu)//(111)_(Ag):(^(-)111)_(Cu)//(^(-)111)_(Ag):(^(-)200)_(Cu)//(^(-)200)_(Ag) and [0^(-)11]_(Cu)//[0^(-)11]_(Ag) with the increase of strain rate.The increase of strain rate promotes the precipitation of Ag and increases the number of interfaces in the microstructure,which hinders the movement of dislocations and improves the stress and yield strength of the Cu-20Ag alloy.The concentration and distribution density of dislocations and the precipitation of Ag were the main reasons improve the flow stress and yield strength of the Cu-20Ag alloy.展开更多
In this paper,a novel Cu-1.5 Ni-1.1 Co-0.6 Si-0.1 Cr(wt.%)alloy with high strength and electrical conductivity was designed.After aging,excellent properties of 857±12 MPa yield strength,300±8 HV microhardnes...In this paper,a novel Cu-1.5 Ni-1.1 Co-0.6 Si-0.1 Cr(wt.%)alloy with high strength and electrical conductivity was designed.After aging,excellent properties of 857±12 MPa yield strength,300±8 HV microhardness,42.8±2.5%IACS conductivity,and 7±0.5%elongation were obtained.According to the atomic structure,part of Ni atoms in Ni_(2)Si can be replaced by Co atoms to form nano-precipitates(Ni,Co)_(2)Si.The alloy’s high strength and conductivity are mainly attributed to the fine and uniformly distributed(Ni,Co)_(2)Si and Cr nano precipitates.The alloy strength was also enhanced by twins,dislocations,and grain refining strengthening.Based on the investigations of deformation microstructure and the orientation relationship between the(Ni,Co)_(2)Si precipitates and the Cu matrix,the main reason for elongation increase is attributed to the formation of deformation twins and the small lattice mismatch strain at the coherent interfaces of precipitates and the Cu matrix.展开更多
基金This work was supported by the National Natural Science Foundation of China(31771750,31730063)National Key Research and Development Project(2017YFD0100201,2017YFD0100202)Natural Science Foundation of Chongqing,China(cstc2018jcyjAX0424).
文摘The mitogen-activated protein kinase(MAPK)cascade is important in stress signal transduction and plant development.In the present study,we identified a rice(Oryza sativa L.)mutant with reduced fertility,Oryza sativa mitogen-activated protein kinase 6(osmapk6),which harbored a mutated MAPK gene.Scanning and transmission electron microscopy,quantitative RT-PCR analysis,TUNEL assays,RNA in situ hybridization,longitudinal and transverse histological sectioning,and map-based cloning were performed to characterize the osmapk6 mutant.The gene OsMAPK6 was expressed throughout the plant but predominantly in the microspore mother cells,tapetal cells,and microspores in the anther sac.Compared with the wild type,the total number of microspores was reduced in the osmapk6 mutant.The formation of microspore mother cells was reduced in the osmapk6 anther sac at an early stage of anther development,which was the primary reason for the decrease in the total number of microspores.Programmed cell death of some tapetal cells was delayed in osmapk6 anthers and affected exine formation in neighboring microspores.These results suggest that OsMAPK6 plays pivotal roles in microspore mother cell formation and tapetal cell degradation.
基金financially supported by the Innovation Leading Project of Henan Province (No. 191110210400)the Key Scientific Research Projects of Colleges and Universities in Henan Province (No. 19A430012)+3 种基金the Luoyang Science and Technology Major Project (No. 1901006A)the Henan Outstanding Talents Innovation Fund (182101510003)National Key R&D Plan (No. 2016YFB0301400)National Key R&D Plan (No.2017YFB0306400)
文摘Copper alloy is widely used in high-speed railway,aerospace and other fields due to its excellent electrical conductivity and mechanical properties.High speed deformation and dynamic loading under impact load is a complex service condition,which widely exists in the field of national defense,military and industrial application.Therefore,the dynamic deformation behavior of the Cu-20Ag alloy was investigated by Split Hopkinson Pressure Bar(SHPB)with the strain rates of 1000-25000 s^(-1),high-speed hydraulic servo material testing machine with the strain rates of 1-500 s^(-1).The effect of strain rate on flow stress and adiabatic shear sensitivity was analyzed.The results show that the increase of strain rate will increase the flow stress and critical strain,that is to say,the increase of strain rate will reduce the adiabatic shear sensitivity of the Cu-20Ag alloy.The Cu-Ag interface has obvious orientation relationship with;(111)_(Cu)//(111)_(Ag):(^(-)111)_(Cu)//(^(-)111)_(Ag):(^(-)200)_(Cu)//(^(-)200)_(Ag) and [0^(-)11]_(Cu)//[0^(-)11]_(Ag) with the increase of strain rate.The increase of strain rate promotes the precipitation of Ag and increases the number of interfaces in the microstructure,which hinders the movement of dislocations and improves the stress and yield strength of the Cu-20Ag alloy.The concentration and distribution density of dislocations and the precipitation of Ag were the main reasons improve the flow stress and yield strength of the Cu-20Ag alloy.
基金supported by the Open Cooperation Project of Science and Technology of the Henan Province(No.182106000018)the Henan University Scientific and Technological Innovation Talent Support Program(No.18HASTIT024)+2 种基金the National Natural Science Foundation of China(No.U1704143)the National Natural Science Foundation of China(No.U1502274)the support from the Government of the Russian Federation(2020-220-08-6662)。
文摘In this paper,a novel Cu-1.5 Ni-1.1 Co-0.6 Si-0.1 Cr(wt.%)alloy with high strength and electrical conductivity was designed.After aging,excellent properties of 857±12 MPa yield strength,300±8 HV microhardness,42.8±2.5%IACS conductivity,and 7±0.5%elongation were obtained.According to the atomic structure,part of Ni atoms in Ni_(2)Si can be replaced by Co atoms to form nano-precipitates(Ni,Co)_(2)Si.The alloy’s high strength and conductivity are mainly attributed to the fine and uniformly distributed(Ni,Co)_(2)Si and Cr nano precipitates.The alloy strength was also enhanced by twins,dislocations,and grain refining strengthening.Based on the investigations of deformation microstructure and the orientation relationship between the(Ni,Co)_(2)Si precipitates and the Cu matrix,the main reason for elongation increase is attributed to the formation of deformation twins and the small lattice mismatch strain at the coherent interfaces of precipitates and the Cu matrix.