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Tianhong Zhou,Hui-Dong Qian,Jung-Tae Lim,Jihoon Park,Yong-Rae Cho,Chul-Jin Choi 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
In our previous work, we studied the influence of Ti and V content in the Sm(Fe0.8Co0.2)12-xTixVx (x = 0.5 - 1.0) alloys. The optimal x for high purity ThMn12 phase was found to be 0.6, and the corresponding remanent magnetization, coercivity, and maximum energy product were 80.6 emu/g, 3379 Oe and 7.29 MGOe, respectively. However, an intergranular phase that could enhance the coercivity was not found in the Sm (Fe0.8Co0.2)10.8Ti0.6V0.6 sample, i.e., the grains of ThMn12-phase were in direct contact. Therefore, in this work, we have introduced Cu-Ga as the intergranular phase to improve the coercivity. First, Sm(Fe0.8Co0.2)10.8Ti0.6V0.6 and Cu-Ga alloys were separately fabricated. The produced alloys were then arc-melted together to produce Sm(Fe0.8Co0.2)10.8Ti0.6V0.6 + x wt.% Cu-Ga (x = 1, 2, 3) alloys. It is noted that an excess of Sm was added to crystallize Sm-Cu-Co-Ga in the alloys. The produced ingots include the ThMn12 and α-Fe phases in the main grains and Sm-Cu-Co-Ga in the grain boundaries. The contents of the α-Fe and Sm-Cu-Co-Ga were dramatically reduced by melt-spinning at the wheel speed of 37 m/s due to the high cooling speed. It was found that the main phase of the melt-spun ribbons is TbCu7 phase. The ribbons were manually ground and pressed under 12.5 GPa to produce high density green bodies. The green bodies were annealed at 800 ℃ for 15 minutes under vacuum conditions, which resulted in a nearly pure ThMn12 phase in the main grains and Sm-Cu-Co-Ga in the grain boundaries. The resulted coercivities of the samples were 3399, 4054, and 4317 Oe for x = 1, 2, and 3, respectively, which are higher than the sample without Cu-Ga. However, compared to the small increase in the coercivity, the remanent magnetization declined to 64, 66 and 60 emu/g, respectively. This degradation resulted in a negative impact on the maximum energy product, which were 4.43, 6.44 and 4.75 MGOe, respectively. Although the intergranular phase was successfully fabricated by introducing the Cu-Ga alloy in this work, it led to the deterioration of the remanent magnetizations and maximum energy products. Thus, it is necessary to further optimize the experimental procedures to improve the magnetic properties. 〈그림 본문참조〉
Tianhong Zhou,Hui-Dong Qian,Jihoon Park,Yong-Rae Cho,Chul-Jin Choi 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
Due to high Fe content, tetragonal SmFe12-based magnets are expected to have a great performance in magnetization and energy density [1]. In order to stabilize their structure, additional elements, such as Ti, V, Nb, Mo, Ta, W, Al or Si, are necessarily substituted. Among these stabilizing elements, Ti is the most effective element that a small amount of Ti can stabilize the structure by replacing only a Fe atom at 8i site [2]. On the other hand, it is reported that V-doped SmFe<sub>12</sub>-based magnets exhibited a larger value of coercivity than V-free magnets [3]. At the same time, the magnetization of the ThMn<sub>12</sub>-type magnets can be enhanced by partially substituting Fe with Co at 8f site in tetragonal structure [4]. Therefore, in this work, we have studied the influence of Ti and V content in the Sm(Fe<sub>0.8</sub>Co<sub>0.2</sub>)<sub>12-2x</sub>Ti<sub>x</su)V<sub>x</sub> (x = 0.5-1.0) alloys. Amorphous ribbons were obtained using melt spinning process, and high density green bodies were produced by pressing the melt-spun ribbons under 12.5 GPa. The green bodies were heat treated at the temperature ranging from 700 to 850℃. At the x from 0.6 to 1.0, we obtained high purity ThMn<sub>12</sub> phase. It was found that the coercivity varies with increasing x contents as can be seen in Fig. 1, while the magnetization decreases due to increasing non-magnetic elements. The optimal x was found to be 0.6, and the corresponding remanent magnetization and maximum energy product were 80.6 emu/g and 7.29 MGOe, respectively. We have also studied the most suitable annealing temperature and Curie temperature for alloys of each component.
( Xianli Niu ),( Shirong Nong ),( Junyuan Gong ),( Xin Zhang ),( Hui Tang ),( Tianhong Zhou ),( Wei Li ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.1
Hepatitis B virus (HBV) genome P-encoded protein HBV DNA polymerase (Pol) has long been known as a reverse transcriptase during HBV replication. In this study, we investigated the impact of HBV Pol on host cellular processes, mainly apoptosis, and the underlying mechanisms. We showed a marked reduction in apoptotic rates in the HBV Pol-expressed HepG2 cells compared to controls. Moreover, a series of assays, i.e., yeast two-hybrid, GST pull-down, co-immunoprecipitation, and confocal laser scanning microscopy, identified the host factor eEF1A2 to be associated with HBV Pol. Furthermore, knockdown of eEF1A2 gene by siRNA abrogated the HBV Pol-mediated anti-apoptotic effect with apoptosis induced by endoplasmatic reticulum (ER) stress-inducer thapsigargin (TG), thus suggesting that the host factor eEF1A2 is essential for HBV Pol’s anti-apoptosis properties. Our findings have revealed a novel role for HBV Pol in its modulation of apoptosis through integrating with eEF1A2.