The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristi...The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.展开更多
The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffra...The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.展开更多
Alternative splicing plays important roles in gene regulation and contributes to protein complexity. Previous studies suggest that alternative splicing exists in members of the villin/gelsolin/fragmin superfamily. In ...Alternative splicing plays important roles in gene regulation and contributes to protein complexity. Previous studies suggest that alternative splicing exists in members of the villin/gelsolin/fragmin superfamily. In this study, a ser- ine/argine-rich （SR） protein cDNA with 28kDa protein （LISR28） was isolated from a lily （Lilium Iongiflorum） expression library. Protein domain analysis showed that LISR28 had similar structures to Arabidopsis SR45 （AtSR45）, and LISR28 could complement the phenotype of loss of AtSR45 function. Therefore, overexpression of LISR28 and AtSR45 mutant （atsr45-1） were used in the following experiments. Overexpression of LISR28 in Arabidopsis completely inhibited pollen germina- tion. In contrast, the pollen germination of atsr45-1 was earlier than that of wild-type. In addition, pollen of atsr45-1 contained less F-actin at the corresponding hydration stage during pollen germination compared to that of wild-type. Alternative splicing analysis showed that Arabidopsis villinl （AtVLN1） transcript encoding the full-length protein was increased, and that encoding the truncated protein was decreased in atst45-1. Moreover, the mRNA expression level of other actin-binding proteins （ABPs） abundant in Arabidopsis pollen was also changed in atsr45-1. In conclusion, we hypothesize that LISR28 alters F-actin dynamics probably through its alternative splicing activities to affect directly or indirectly the alternative splicing of AtVLN1 and the expression of different ABPs, which then affects the pollen germination.展开更多
By using TEM, XPS, IR, position annihilation and differential specific heat measurements, the properties and structure of the F-doped (Bi, Pb)-Sr-Ca-Cu-O superconductor have been studied. The results show that the flu...By using TEM, XPS, IR, position annihilation and differential specific heat measurements, the properties and structure of the F-doped (Bi, Pb)-Sr-Ca-Cu-O superconductor have been studied. The results show that the fluorine atoms are homogeneously distributed in superconducting phase and substituted for the oxygen atoms at O(2) crystallographic sites; the Pb-F and Cu-F bonds are formed. F-doping results in the variance of the incommensurate modulation structure, the increase of the point defects and chemical pressure, the enhancement of flux pinning effect and the change of the electronic structure and chemical bond, and greatly improves superconductive properties of the 2223 phase (Bi, Pb)-Sr-Ca-Cu-O.展开更多
文摘The Sr/F co-doped CaP(Sr/F-CaP)coatings were prepared by micro-arc oxidation(MAO)under different voltages to modify the microstructure and corrosion behavior of Mg-4Zn-1Mn alloy.The surface and interface characteristics investigated using scanning electron microscopy(SEM)and energy dispersive X-ray spectrometer(EDS)showed that the MAO coatings displayed uneven crater-like holes and tiny cracks under lower voltage,while they exhibited relatively homogeneous crater-like holes without cracks under higher voltage.The thickness of MAO coatings increased with increasing voltage.The corrosion behavior of Mg-4Zn-1Mn alloy was improved by the MAO coatings.The MAO coatings prepared under 450 V and 500 V voltages possessed the best corrosion resistance with regard to the electrochemical corrosion tests and immersion corrosion tests,respectively.The MAO coatings fabricated under 450-500 V could provide a better corrosion protection effect for the substrate.
文摘The phase and the structure of polycrystal material, which was prepared by calcining the co precipitated fluoride powder of Sr and La with a ratio of 0.69∶0.31 mixed with SrS powder, were investigated by X ray diffraction and electron probe scanning. In the materials, three phases were found, they are Sr 0.69 La 0.31 F 2.31 solid solution phase with a pure SrF 2 cubic structure whose lattice constant is 5.843 ?, SrS single phase with a NaCl cubic structure, and an unknown phase that is produced by the interaction of SrS and co precipitated powder. It was also found that SrS has no influence on the structure of Sr 0.69 La 0.31 F 2.31 solid solution.
基金the National Natural Science Foundation of China，by the National Basic Research Program of China (2013CB126902)to H.R
文摘Alternative splicing plays important roles in gene regulation and contributes to protein complexity. Previous studies suggest that alternative splicing exists in members of the villin/gelsolin/fragmin superfamily. In this study, a ser- ine/argine-rich （SR） protein cDNA with 28kDa protein （LISR28） was isolated from a lily （Lilium Iongiflorum） expression library. Protein domain analysis showed that LISR28 had similar structures to Arabidopsis SR45 （AtSR45）, and LISR28 could complement the phenotype of loss of AtSR45 function. Therefore, overexpression of LISR28 and AtSR45 mutant （atsr45-1） were used in the following experiments. Overexpression of LISR28 in Arabidopsis completely inhibited pollen germina- tion. In contrast, the pollen germination of atsr45-1 was earlier than that of wild-type. In addition, pollen of atsr45-1 contained less F-actin at the corresponding hydration stage during pollen germination compared to that of wild-type. Alternative splicing analysis showed that Arabidopsis villinl （AtVLN1） transcript encoding the full-length protein was increased, and that encoding the truncated protein was decreased in atst45-1. Moreover, the mRNA expression level of other actin-binding proteins （ABPs） abundant in Arabidopsis pollen was also changed in atsr45-1. In conclusion, we hypothesize that LISR28 alters F-actin dynamics probably through its alternative splicing activities to affect directly or indirectly the alternative splicing of AtVLN1 and the expression of different ABPs, which then affects the pollen germination.
文摘By using TEM, XPS, IR, position annihilation and differential specific heat measurements, the properties and structure of the F-doped (Bi, Pb)-Sr-Ca-Cu-O superconductor have been studied. The results show that the fluorine atoms are homogeneously distributed in superconducting phase and substituted for the oxygen atoms at O(2) crystallographic sites; the Pb-F and Cu-F bonds are formed. F-doping results in the variance of the incommensurate modulation structure, the increase of the point defects and chemical pressure, the enhancement of flux pinning effect and the change of the electronic structure and chemical bond, and greatly improves superconductive properties of the 2223 phase (Bi, Pb)-Sr-Ca-Cu-O.
