The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that th...The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field.For the Al-Cu and Ni-Mn-Ga alloys,the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10μm/s and 5μm/s.Further,the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated.Numerical results reveal that the rotary thermoelectric(TE)magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field.This flow will induce the formation of the ring-like macro-segregation and structure.Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results.Therefore,the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.展开更多
Sodium molybdate was reduced to produce ring-like compounds in the presence of carboxylic acids. Compound 1: Na8(H2O)28(H3O)+{Na(DMSO)2[MoVI10MoV8O52(OH)4(CH3C- OO)2]}11H2O (C8H103O102Na9S2Mo18, Mr = 3829.85), where ...Sodium molybdate was reduced to produce ring-like compounds in the presence of carboxylic acids. Compound 1: Na8(H2O)28(H3O)+{Na(DMSO)2[MoVI10MoV8O52(OH)4(CH3C- OO)2]}11H2O (C8H103O102Na9S2Mo18, Mr = 3829.85), where the {Mo18} ring is built up by two acetic acids connecting two {Mo9} building blocks and the 1-D chain of 1 is formed through the coordinated sodium cations. Crystal data: triclinic, space group P, a = 11.3228(2), b = 15.4170(2), c = 16.7209(3) ? a = 113.006(1), b = 108.455(1), g = 92.430(1), V = 2501.98(7) 3, Z = 1, Dc = 2.542 g/cm3, F(000) = 1854, (MoKa) = 2.381 mm-1, T = 293(2) K, final R = 0.0532 and wR = 0.1203 for 7291 observed reflections with I > 2(I) from 8775 independent reflections. Compound 2: Na8(H2O)22(H3O)+{Na(DMSO)2[MoVI10MoV8O52(OH)4(C2H5COO)2]}10H2O (C10H93O94Na9- S2Mo18, Mr = 3715.79). Crystal data: monoclinic, space group C2/m, a = 18.044(1), b = 25.944(2), c = 10.4087(6) ? b = 106.613(2), V = 4669.3(5) 3, Z = 2, Dc = 2.643 g/cm3, F(000) = 3584, (MoKa) = 2.542 mm-1, T = 293(2) K, final R = 0.0536 and wR = 0.1621 for 4617 observed reflections with I > 2(I) from 5398 independent reflections. Similar to 1, the {Mo18} ring is built up by two {Mo9} building blocks that are connected up by two propanoic acids and these {Mo18} rings are further linked into a two-dimensional layer through the coordinated sodium cations.展开更多
Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Her...Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Here we identified five allelic mutants sb1-1/2/3/4/5 that related to branch development of rice.In these mutants,the branch meristem fate was prolonged sharply,resulting in delay of transition from branches to spikelets,and then increased the numbers of branches and spikelets per panicle.SB1 encodes a nuclear RING-like domain protein of SHI/LRP/SRS family and strongly expressed in branch meristems.The results of protein interaction and chromatin immunoprecipitation further suggested that SB1 directly repressed the expression of DEP1,TAW1,MOC1 and IPA1 by interacting with a co-repressor complex to affect acetylation level of histone H3 on target regions.Thus,we proposed that SB1 is a transcription repressor of branch meristem activity by widely and negatively regulating a series of genes that maintain branch meristem fate.展开更多
At the late stage of transitional boundary layers, the nonlinear evolution of the ring-like vortices and spike structures and their effects on the surrounding flow were studied by means of direct numerical simulation ...At the late stage of transitional boundary layers, the nonlinear evolution of the ring-like vortices and spike structures and their effects on the surrounding flow were studied by means of direct numerical simulation with high order accuracy. A spatial transition of the flat-plate boundary layers in the compressible flow was conducted. Detailed numerical results with high resolution clearly represented the typical vortex structures, such as ring-like vortices and so on, and induced ejection and sweep events. It was verified that the formation of spike structures in transitional boundary layers had close relationship with ring-like vortices. Especially, compared to the newly observed positive spike structure in the experiments, the same structure was found in the present numerical simulations, and the mechanism was also studied and analyzed.展开更多
The conclusion based on transmission electron microscopy, "the tightly packed ring-like nucleoid of the Deinococcus radiodurans R1 is a key to radioresistance", has instigated lots of debates. In this study,...The conclusion based on transmission electron microscopy, "the tightly packed ring-like nucleoid of the Deinococcus radiodurans R1 is a key to radioresistance", has instigated lots of debates. In this study, according to the previous research of PprI’s crucial role in radioresistance of D. radiodurans, we have attempted to examine and compare the nucleoid morphology differences among wild-type D. ra-diodurans R1 strain, pprI function-deficient mutant (YR1), and pprI function-complementary strains (YR1001, YR1002, and YR1004) before and after exposure to ionizing irradiation. Fluorescence mi-croscopy images indicate: (1) the majority of nucleoid structures in radioresistant strain R1 cells ex-hibit the tightly packed ring-like morphology, while the pprI function-deficient mutant YR1 cells carrying predominate ring-like structure represent high sensitivity to irradiation; (2) as an extreme radioresistant strain similar to wild-type R1, pprI completely function-complementary strain YR1001 almost displays the loose and irregular nucleoid morphologies. On the other hand, another radioresistant pprI partly function-complementary strain YR1002’s nucleiods exhibit about 60% ring-like structure; (3) a PprI C-terminal deletion strain YR1004 consisting of approximately 60% of ring-like nucleoid is very sensi-tive to radiation. Therefore, our present experiments do not support the conclusion that the ring-like nucleoid of D. radiodurans does play a key role in radioresistance.展开更多
基金the financial supports from National foundation of Science(Nos.51690164 and 51805321)Shanghai Science and Technology Committee Grant(Nos.19XD1401600 and 19010500300)
文摘The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field.For the Al-Cu and Ni-Mn-Ga alloys,the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10μm/s and 5μm/s.Further,the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated.Numerical results reveal that the rotary thermoelectric(TE)magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field.This flow will induce the formation of the ring-like macro-segregation and structure.Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results.Therefore,the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.
基金the National Natural Science Foundation of China (20073048),NSF of Fujian province (2002F015) and the Chinese Academy of Sciences
文摘Sodium molybdate was reduced to produce ring-like compounds in the presence of carboxylic acids. Compound 1: Na8(H2O)28(H3O)+{Na(DMSO)2[MoVI10MoV8O52(OH)4(CH3C- OO)2]}11H2O (C8H103O102Na9S2Mo18, Mr = 3829.85), where the {Mo18} ring is built up by two acetic acids connecting two {Mo9} building blocks and the 1-D chain of 1 is formed through the coordinated sodium cations. Crystal data: triclinic, space group P, a = 11.3228(2), b = 15.4170(2), c = 16.7209(3) ? a = 113.006(1), b = 108.455(1), g = 92.430(1), V = 2501.98(7) 3, Z = 1, Dc = 2.542 g/cm3, F(000) = 1854, (MoKa) = 2.381 mm-1, T = 293(2) K, final R = 0.0532 and wR = 0.1203 for 7291 observed reflections with I > 2(I) from 8775 independent reflections. Compound 2: Na8(H2O)22(H3O)+{Na(DMSO)2[MoVI10MoV8O52(OH)4(C2H5COO)2]}10H2O (C10H93O94Na9- S2Mo18, Mr = 3715.79). Crystal data: monoclinic, space group C2/m, a = 18.044(1), b = 25.944(2), c = 10.4087(6) ? b = 106.613(2), V = 4669.3(5) 3, Z = 2, Dc = 2.643 g/cm3, F(000) = 3584, (MoKa) = 2.542 mm-1, T = 293(2) K, final R = 0.0536 and wR = 0.1621 for 4617 observed reflections with I > 2(I) from 5398 independent reflections. Similar to 1, the {Mo18} ring is built up by two {Mo9} building blocks that are connected up by two propanoic acids and these {Mo18} rings are further linked into a two-dimensional layer through the coordinated sodium cations.
基金supported by the National Natural Science Foundation of China(Grant No.31971919)the National Key Program for Research and Development of China(Grant No.2017YFD0100202)+1 种基金the Project Sponsored by Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyjjqX0020)Chongqing Graduate Research and Innovation Project funding in China(Grant No.CYS20123)。
文摘Inflorescence structure of rice,including the number and length of branches,and the density of the spikelet,can greatly affect the number of grains per panicle,which is one of the key factors in yield compositions.Here we identified five allelic mutants sb1-1/2/3/4/5 that related to branch development of rice.In these mutants,the branch meristem fate was prolonged sharply,resulting in delay of transition from branches to spikelets,and then increased the numbers of branches and spikelets per panicle.SB1 encodes a nuclear RING-like domain protein of SHI/LRP/SRS family and strongly expressed in branch meristems.The results of protein interaction and chromatin immunoprecipitation further suggested that SB1 directly repressed the expression of DEP1,TAW1,MOC1 and IPA1 by interacting with a co-repressor complex to affect acetylation level of histone H3 on target regions.Thus,we proposed that SB1 is a transcription repressor of branch meristem activity by widely and negatively regulating a series of genes that maintain branch meristem fate.
基金supported by the National Natural Science Foundation of China (Grant No. 10772082)AFOSR (Grant No. FA9550-08-1-0201)
文摘At the late stage of transitional boundary layers, the nonlinear evolution of the ring-like vortices and spike structures and their effects on the surrounding flow were studied by means of direct numerical simulation with high order accuracy. A spatial transition of the flat-plate boundary layers in the compressible flow was conducted. Detailed numerical results with high resolution clearly represented the typical vortex structures, such as ring-like vortices and so on, and induced ejection and sweep events. It was verified that the formation of spike structures in transitional boundary layers had close relationship with ring-like vortices. Especially, compared to the newly observed positive spike structure in the experiments, the same structure was found in the present numerical simulations, and the mechanism was also studied and analyzed.
基金Supported by the National Basic Research Program of China (Grant No. 2004CB19604)the National Natural Science Foundation of China (Grant No. 30330020)the National Science fund for Distinguished Young Scholars (Grant No. 30425038)
文摘The conclusion based on transmission electron microscopy, "the tightly packed ring-like nucleoid of the Deinococcus radiodurans R1 is a key to radioresistance", has instigated lots of debates. In this study, according to the previous research of PprI’s crucial role in radioresistance of D. radiodurans, we have attempted to examine and compare the nucleoid morphology differences among wild-type D. ra-diodurans R1 strain, pprI function-deficient mutant (YR1), and pprI function-complementary strains (YR1001, YR1002, and YR1004) before and after exposure to ionizing irradiation. Fluorescence mi-croscopy images indicate: (1) the majority of nucleoid structures in radioresistant strain R1 cells ex-hibit the tightly packed ring-like morphology, while the pprI function-deficient mutant YR1 cells carrying predominate ring-like structure represent high sensitivity to irradiation; (2) as an extreme radioresistant strain similar to wild-type R1, pprI completely function-complementary strain YR1001 almost displays the loose and irregular nucleoid morphologies. On the other hand, another radioresistant pprI partly function-complementary strain YR1002’s nucleiods exhibit about 60% ring-like structure; (3) a PprI C-terminal deletion strain YR1004 consisting of approximately 60% of ring-like nucleoid is very sensi-tive to radiation. Therefore, our present experiments do not support the conclusion that the ring-like nucleoid of D. radiodurans does play a key role in radioresistance.
