Replacement of Dy and substitution of Nd in NdFeB-based permanent magnets by Ce, the most abundant and lowest cost rare earth element, is important because Dy and Nd are costly and critical rare earth elements. The Ce, Co co-doped alloys have excellent high-temperature magnetic properties with an intrinsic coercivity being the highest known for T ≥ 453 K.

No abstract

The ubiquitous solar jets or jet-like activities are generally regarded as an important source of energy and mass input to the upper solar atmosphere and the solar wind. However, questions about their triggering and driving mechanisms are not completely understood. By taking advantage of high temporal and high spatial resolution stereoscopic observations taken by the Solar Dynamic Observatory (SDO) and the Solar Terrestrial Relations Observatory (STEREO), we report an intriguing two-sided-loop jet occurred on 2013 June 02, which was dynamically associated with the eruption of a mini-filament below an overlying large filament, and two distinct reconnection processes are identified during the formation stage. The SDO observations reveals that the two-sided-loop jet showed a concave shape with a projection speed of about 80 -136 km s −1 . From the other view angle, the STEREO ahead observations clearly showed that the trajectory of the two arms of the two-sided-loop were along the cavity magnetic field lines hosting the large filament. Contrary to the well-accepted theoretical model, the present observation sheds new light on our understanding of the formation mechanism of two-sided-loop jets. Moreover, the eruption of the two-sided-loop jet not only supplied mass to the overlying large filament, but also provided a rare opportunity to diagnose the magnetic structure of the overlying large filament via the method of three-dimensional reconstruction.

A series of novel alloys CeFe11−xCoxTi (0 ≤ x ≤ 11) with ThMn12 structure has been successfully prepared by melt-spinning. The Curie temperature Tc increases with Co content x, reaching a maximum of 689 °C at x = 9 and declining to 664 °C at complete Co filling (x = 11). The room temperature saturation magnetization 4πMs and magnetocrystalline anisotropy Ha have been estimated by fitting the first quadrant demagnetization curve with the Stoner-Wohlfarth model. 4πMs first increases with increasing Co up to x = 3, then decrease. Ha has a complex dependence on Co content, which is indicative of a change in the easy magnetization direction from axis to plane and back as the Co content increases.

No abstract

A solar jet on 2014 July 31, which was accompanied by a GOES C1.3 flare and a mini-filament eruption at the jet base, was studied by using observations taken by the New Vacuum Solar Telescope and the Solar Dynamic Observatory. Magnetic field extrapolation revealed that the jet was confined in a fan-spine magnetic system that hosts a null point at the height of about 9 Mm from the solar surface. An inner flare ribbon surrounded by an outer circular ribbon and a remote ribbon were observed to be associated with the eruption, in which the inner and remote ribbons respectively located at the footprints of the inner and outer spines, while the circular one manifested the footprint of the fan structure. It is interesting that the circular ribbon's west part showed an interesting round-trip slipping motion, while the inner ribbon and the circular ribbon's east part displayed a northward slipping motion. Our analysis results indicate that the slipping motions of the inner and the circular flare ribbons reflected the slipping magnetic reconnection process in the fan quasi-separatrix layer, while the remote ribbon was associated with the magnetic reconnection at the null point. In addition, the filament eruption was probably triggered by the magnetic cancellation around its south end, which further drove the slipping reconnection in the fan quasiseparatrix layer and the reconnection at the null point.

We have investigated the thermoelectric properties of alloys of composition CoSi 1−x Ge x for 0 Յ x Յ 0.5. These alloys display Seebeck coefficient in the range of Ϫ80 to −100 V K −1 at room temperature. Despite the rather high Seebeck coefficients, the electrical resistivity of these alloys is metallic in nature. Alloying on the Ge site strongly reduces the lattice thermal conductivity. The combination of high Seebeck coefficient and metallic resistivity leads to very high thermoelectric power factor in these alloys, with the best sample exhibiting a power factor higher than that of state of the art bismuth telluride-based thermoelectric alloys at room temperature.

Naturally occurring carbonates have a wide variation in Mg and Ca contents. Using the density-functional-theory calculations, this study examines the effect of Mg and Ca concentrations on bond lengths and equilibrium fractionation factors of Mg-Ca isotopes among calcite-type carbonate minerals (Mg x Ca 1-x CO 3). Mg content x and Ca content (1-x) of the investigated carbonate minerals range from 1/12 to 1 and from 1/36 to 1, respectively. Concentration of Ca and Mg in carbonates have significant effects on Ca-O and Mg-O bond lengths when x is close to 0, 0.5 or 1. Because equilibrium isotope fractionation factors (10 3 lnα) are mainly controlled by their relevant bond strengths, which can be measured using their average bond lengths, 10 3 lnα of 26 Mg/ 24 Mg and 44 Ca/ 40 Ca between calcite-type carbonate minerals and dolomite also vary dramatically with Mg content, especially when x is close to 0 and 1. For instance, at 300 K, 10 3 lnα of 26 Mg/ 24 Mg between Mg 1/12 Ca 11/12 CO 3 and dolomite (x=0.5) is ~-4.3 ‰, while 10 3 lnα of 44 Ca/ 40 Ca between Mg 23/24 Ca 1/24 CO 3 and dolomite is ~ 6 ‰. Dolomite is enriched in 26 Mg but depleted in 44 Ca relative to all other carbonate minerals, which is consistent with it having the shortest Mg-O bond length and the longest Ca-O bond lengths among all carbonates. At 300 K, a small change of x from 0.5 to 0.6 in dolomite could result in 1‰ variation in 10 3 lnβ of 26 Mg/ 24 Mg. Therefore, the concentration effect in carbonate minerals should be taken into account when applying the isotope fractionation factors of carbonate minerals to understand geochemical processes.