Papers by Keyword: MX

Abstract: In the study, the Mx gene promoter, exon 1, exon 2, and exon 14 and intron 13 in eight Chinese local chicken breeds were examined. Amino acid 631 in the GED region was tested in eight Chinese local chicken breeds and two exotic breeds. The frequency of allele A was 0.1259 and the frequency of allele G was 0.8741. Meanwhile, induction of expression of the Mx gene in chicken embryo fibroblasts was analyzed in the local chicken breed, Beijing-you and the exotic breed, White Leghorn.The semi-quantitative and quantitative results showed that the expression of the Mx gene in White Leghorn was significantly different under different induction conditions. There was also a difference in the genotypic distribution of S631N in two breeds: allele A/G was 0.8471/0.1529 and 0.1613/0.8387 in White Leghorn and Beijing-you chickens, respectively. We speculate that the difference in the genotypic distribution has an effect on Mx gene expression.

Abstract: The Cu-containing austenitic heat-resistant steel 18Cr-9Ni-3CuNbN has been widely used as superheater and reheater tube material for modern ultra-super-critical (USC) power plants in the world. High temperature structure stability is considered to be an important factor for long-term service. Long-term aging at 650°C for this steel was conducted from 100 to 10,000hours. Effect of aging time on microstructure was studied by means of SEM, TEM and 3DAP (three dimensional atom probe). Micro-hardness tests were carried out after aging at 650°C for different times to be considered as a representative of strength. Experimental results show that Cu-rich phase, MX and M23C6 are major strengthening precipitates in this steel. With on increasing of aging time, fine nano-size Cu-rich phase particles precipitate in the grains and its size is in the range of several nanometers to 35nm till 10,000h at 650°C. The fraction of MX also increases with aging time and its average size is about 100nm till 10,000h. Carbide M23C6 mainly precipitates at grain boundaries and coarsens quickly. Investigation results show that the most important strengthening effect for 18Cr-9Ni-3CuNbN steel is contributed by Cu-rich phase and MX in the grains and M23C6 carbide at the grain boundaries.

Abstract: Creep deformation mechanism of the steels with a different matrix, α (ferrite), α’ (martensite) and γ (austenite), and precipitates such as MX and M23C6 has been analyzed using positron annihilation lifetime measurement. The positron annihilation lifetime has been found to be a very useful tool for evaluating the characteristic creep damage of the steels with different microstructure and the corresponding microstructural evolution during creep deformation. The creep deformation process of the α steel is heterogeneous, while the α’+M23C6 steel exhibits gradual changes in the creep rate in both transient and acceleration creep regions with the largest off-set strain, implying the homogeneous creep deformation. The α’+M23C6+ MX steel is in between the α and α’+M23C6 steels. The homogeneous creep deformation takes place in the γ steel.