Highly textured nanocomposite Nd_9Fe_(84.5)Nb_(0.5)B_6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s^(-1). X-ray diffraction (XRD) shows that these ribbons are preferentially ori...Highly textured nanocomposite Nd_9Fe_(84.5)Nb_(0.5)B_6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s^(-1). X-ray diffraction (XRD) shows that these ribbons are preferentially orientated with the c axis of Nd_2Fe_(14)B phase perpendicular to the surface of the ribbons. The texture of Nd_2Fe_(14)B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed. The texture of Nd_2Fe_(14)B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification, which can be explained by a growth circular cone (GCC). The intensity of the anisotropy can be expressed by the magnitude of the cone generating angle. The supercooling velocity and wheel speed will influence the cone generating angle, which in turn influences the anisotropy. The remanence and maximum energy product in the direction perpendicular to the ribbon surface is much higher than that in the direction parallel with the ribbon surface. High remanence and maximum energy product can be obtained in the direction perpendicular to the ribbon surface. The texture of Nd_2Fe_(14)B phase decreases gradually after annealing above 600 ℃, which is mainly attributed to the precipitation of new α-Fe from Nd_2Fe_(14)B phase with super-saturated Fe. Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd_2Fe_(14)B phase after annealing.展开更多
To study the toxicity of samarium nitrate on male mice＇s testicle tissue, samarium nitrate was administrated to mice at different doses（0, 5, 50, 500, 2000 mg·L^-1） for 3 months. The biochemical index and path...To study the toxicity of samarium nitrate on male mice＇s testicle tissue, samarium nitrate was administrated to mice at different doses（0, 5, 50, 500, 2000 mg·L^-1） for 3 months. The biochemical index and pathological changes were observed. The results show that the construction of testicle, especially in sperms and testis intersitium are broken. LDH enzyme activity in 2000 mg·L^-1 and LDH-X enzyme activity in 500 and 2000 mg·L^- 1dose groups are inhibited obviously. SDH enzyme activity in 50, 500 and 2000 mg·L^-1 dose groups are lower than that in control group, but T-GT enzyme activity is unacted on Sm. With increase of samarium concentration, Na^＋K^＋-ATP, Mg^2＋-ATP enzyme activity tend to ＂promote weakly and inhibited strongly＂, while Ca^2＋-ATPase decrease largely. Subchronic samarium exposure has definite toxicity to gonad of mice.展开更多
文摘Highly textured nanocomposite Nd_9Fe_(84.5)Nb_(0.5)B_6 ribbons were obtained by rapid solidification at wheel speeds from 15 to 20 m·s^(-1). X-ray diffraction (XRD) shows that these ribbons are preferentially orientated with the c axis of Nd_2Fe_(14)B phase perpendicular to the surface of the ribbons. The texture of Nd_2Fe_(14)B phase on the free surface is stronger than that on the contact surface and decreases with increase of wheel speed. The texture of Nd_2Fe_(14)B phase seems to be caused by the preferential growth of the crystal nuclei favorable orientation with their c-axes along the temperature gradient during rapid solidification, which can be explained by a growth circular cone (GCC). The intensity of the anisotropy can be expressed by the magnitude of the cone generating angle. The supercooling velocity and wheel speed will influence the cone generating angle, which in turn influences the anisotropy. The remanence and maximum energy product in the direction perpendicular to the ribbon surface is much higher than that in the direction parallel with the ribbon surface. High remanence and maximum energy product can be obtained in the direction perpendicular to the ribbon surface. The texture of Nd_2Fe_(14)B phase decreases gradually after annealing above 600 ℃, which is mainly attributed to the precipitation of new α-Fe from Nd_2Fe_(14)B phase with super-saturated Fe. Decreasing the annealing temperature or reducing the annealing time is beneficial for preserving the anisotropy of Nd_2Fe_(14)B phase after annealing.
文摘To study the toxicity of samarium nitrate on male mice＇s testicle tissue, samarium nitrate was administrated to mice at different doses（0, 5, 50, 500, 2000 mg·L^-1） for 3 months. The biochemical index and pathological changes were observed. The results show that the construction of testicle, especially in sperms and testis intersitium are broken. LDH enzyme activity in 2000 mg·L^-1 and LDH-X enzyme activity in 500 and 2000 mg·L^- 1dose groups are inhibited obviously. SDH enzyme activity in 50, 500 and 2000 mg·L^-1 dose groups are lower than that in control group, but T-GT enzyme activity is unacted on Sm. With increase of samarium concentration, Na^＋K^＋-ATP, Mg^2＋-ATP enzyme activity tend to ＂promote weakly and inhibited strongly＂, while Ca^2＋-ATPase decrease largely. Subchronic samarium exposure has definite toxicity to gonad of mice.
