After the development of Nd–Fe–B magnets, rare-earth magnets are now essential components in many fields of technology, because of their ability to provide a strong magnetic flux. There are two, ...well-established techniques for the manufacture of rare earth magnets: powder metallurgy is used to obtain high-performance, anisotropic, fully dense magnet bodies; and the melt-spinning or HDDR (hydrogenation, disproportionation, desorption and recombination) process is widely used to produce magnet powders for bonded magnets. In the industry of sintered Nd–Fe–B magnets, the total amount of production has increased and their dominant application has been changed to motors. In particular, their use for motors in hybrid cars is one of the most attractive applications. Bonded magnets have also been used for small motors, and the studies of nanocomposite and Sm–Fe–N magnets have become widespread. This paper reviews the current status and future trend in the research of permanent magnets.
•TbCu7-type phase crystallized in annealed ribbons.•Coercivity of annealed ribbons increased with longer annealing time and cooling time.•A maximum coercivity of 695 kA⋅m−1 was obtained with the ...proper Sm composition and annealing conditions.•Nb and B became enriched at grain boundaries and the compositions of both elements increased with increasing annealing time.•Bonded magnet fabricated from Sm-Fe-Co-Nb-B melt-spun ribbons exhibited good magnetic properties and small temperature coefficient of remanence and coercivity.
The effects of annealing conditions on magnetic properties, phase, and microstructural changes in Sm-Fe-Co-Nb-B melt-spun ribbons were investigated, and the dependence of magnetic properties on Sm and B composition was also investigated. SmxFe80.9−(x+y)Co16.4Nb2.7By amorphous ribbons were prepared by melt-spinning and then annealing. After annealing at 625 °C, the Sm6.2Fe66.4Co16.4Nb2.7B8.3 ribbons exhibited crystallization of hard-magnetic TbCu7-type phase, and the coercivity increased as the annealing time was increased to 9 h. The grain size of the TbCu7-type phase as estimated from transmission electron microscopy (TEM) images was 20–50 nm for ribbons annealed for 9 h. Three-dimensional atom probe (3DAP) analysis revealed that Nb and B became enriched at grain boundaries and tended to condense at the grain boundaries with increasing annealing time. Non-magnetic Nb and B enrichment at the grain boundaries in fine TbCu7-type grains thus promotes magnetic decoupling between TbCu7-type phases and suppresses domain wall propagation, resulting in high coercivity. Composition dependence on magnetic properties was investigated. Optimum annealing time tended to increase with increasing Sm content. The Sm6.7Fe65.9Co16.4Nb2.7B8.3 ribbons exhibited a maximum coercivity of 695 kA⋅m−1 by annealing at 625 °C for 21 h and subsequent slow cooling at a cooling rate of 4 °C⋅h−1. As B content decreased, coercivity decreased and remanence increased. The Sm6.2Fe68.7Co16.4Nb2.7B6.0 ribbons exhibited a high σr of 100 A⋅m2⋅kg−1 and moderate HcJ of 540 kA⋅m−1 after optimal annealing. An isotropic bonded magnet was fabricated from this ribbon. The bonded magnet exhibited high magnetic properties of Br = 0.82 T, HcJ = 538 kA⋅m−1, and (BH)max = 98 kJ⋅m−3, and small temperature coefficients of α(Br) = −0.06%⋅°C−1 and β(HcJ) = −0.27%⋅°C−1.
Anisotropic Nd-Fe-B hydrogenation disproportionation desorption recombination powder with high corrosion resistance was prepared by phosphoric acid treatment. The treated samples baked at ...temperatures higher than 250 °C exhibited high corrosion resistance. In addition, the change ratio of coercivity before and after the anticorrosion test was within 5%. Microstructural observations indicated the formation a uniform phosphate layer with a small amount of Nd oxide at high baking temperature.
More on a holographic dual of QCD SAKAI, Tadakatsu; SUGIMOTO, Shigeki
Progress of theoretical physics,
11/2005, Letnik:
114, Številka:
5
Journal Article
A near‐future, 2‐K warming climate simulation comprising over 3,000 years of ensemble simulations was performed using 60‐km global and 20‐km regional atmospheric models. Even in the +2‐K climate, ...indices of extreme precipitation and dryness increased significantly in the extratropics compared with the historical climate. Mean precipitation increases in the rainy season and decreases in the dry season, indicating that the seasonal precipitation range becomes amplified with global warming. The intensification of precipitation and dryness from +2 to +4 K was also robust in the mean for climatological wet and arid regions. Around Japan, which was classified as a wet region, the regional atmospheric model predicts that the extreme hourly precipitation in the future climate becomes more extreme on hot days, but slightly weaker on cold days. This extreme precipitation has a high sensitivity to air temperature exceeding 7%/K.
Plain Language Summary
Our study shows the precipitation changes in the near‐future around the 2040s, +2‐K climate. Even in the +2‐K climate, both extreme precipitation and dryness in the extratropics increase significantly. These results urge to plan for adaptation to extreme weather in the near future. The 2‐K warming climate simulation was performed with over 3,000 years of ensemble member using 60‐km global and 20‐km regional atmospheric models. A large number of ensemble data elucidated statistically significant increment of the precipitation extremes, moreover the amplifying of the seasonal precipitation range. The data are helpful to investigate the climate in the near‐future containing mixed uncertainty both internal variation and effects of future scenario. It would provide valuable information for policy‐making, planning of mitigation, and adaptation for extreme weather events, such as flooding or droughts in the near‐future climate.
Key Points
High‐resolution large‐ensemble simulations are performed to assess precipitation change under the +2‐K climate
Even in the +2‐K climate, both extreme precipitation and dryness in the extratropics increase significantly compared with the historical climate
The tendency for the seasonal precipitation range to amplify becomes robust with global warming from the +2‐K to +4‐K climate
•An adequate maximum field exists in the LAFS method for determination of Js and Ha.•Adequate field (Hs) for LAFS corresponds to magnetic anisotropy fields of samples.•The results of the ordinary ...LAFS and that of Czerlinsky LAFS agree under the Hs.•The measured results of ferrite and of our ThMn12 magnets proved our conclusion.•Newly prepared ThMn12 magnets show the better magnetic properties than Nd2Fe14B.
The law of approach to ferromagnetic saturation (LAFS) method is required for the accurate measurement of the magnetic properties of magnetically isotropic materials. In this study, we examined the accuracy of the following two LAFS methods for determining the saturation polarization (Js) and anisotropy field (Ha) of isotropic magnets: (1) the method based on the relationship between polarization (J) and applied field (H; 1/H2); and (2) the method based on the relationship between susceptibility (dJ/dH) and 1/H3. We used an isotropic magnet prepared from a commercial ferrite magnet powder with well-known magnetic properties and low Ha as a standard magnet for evaluating the two LAFS methods. Then, we measured the Js and Ha values of our -Ti0.7 compounds with a ThMn12 structure, (Nd0.8Zr0.2)(Fe0.9Co0.1)11.3Ti0.7N1.5 and (Sm0.9Zr0.1)(Fe0.8Co0.2)11.3Ti0.7, including in the high-temperature region (>373 K), where the reduction of Ha was observed. Finding the adequate maximum magnetic fields, where the Js and Ha values obtained by the two LAFS methods agree well, is important for the proper application of the method to isotropic magnet samples. The results of the LAFS methods revealed that the Js values of the new compounds are similar at RT, but higher than that of the Nd2Fe14B phase in the high-temperature region. Because the -Ti0.7 compounds are almost α-(Fe,Co)-phase-free, their Ha values are also higher than that of Nd2Fe14B over the whole temperature region.
Some patients have noted a foul odor during radiation therapy sessions, but the cause of the odor remains unknown. Since we suspected that this phenomenon is due to ozone generated by ionizing ...radiation, this experimental study measured ozone concentrations in the treatment room and in a coiled polyvinyl chloride (PVC) tube placed within the radiation field.
We measured ozone concentrations using an ultraviolet absorption method and an ozone monitor. A PVC tube (inner diameter 7 mm, outer diameter 10 mm) was used to mimic the environment of the nasal cavity. The tube (790 cm) was coiled and set between two 4-cm-thick (for X-rays) or 2-cm-thick (for electron beams) water-equivalent solid phantoms. The sampling tube of the ozone monitor was inserted into the PVC tube, and the joint was sealed to prevent environmental air contamination. To measure ozone concentrations in the atmosphere, the sampling tube supplied with the unit was used. A linac was used on a full-sized treatment field (40 cm × 40 cm at a source-to-axis distance of 100 cm). The effect of an electron beam on ozone concentrations was also evaluated with a full-sized treatment field (40 cm × 40 cm at a source-to-surface distance of 100 cm).
Ozone levels in the treatment room were undetectable before the start of daily treatment but reached 0.008 parts per million (ppm) or more at 1 h after the start of treatment. Concentrations then remained nearly constant at 0.010-0.015 ppm throughout the day. The maximum ozone concentration in the PVC tube was only 0.006 ppm, even when it was irradiated at 2400 monitor units/min. Depending on the X-ray dose rate, the concentration increased to a maximum of 0.010 ppm with oxygen flowing into the other end of the tube at 1.5 L/min. Ozone concentrations in the PVC tube did not differ significantly between X-ray and electron-beam irradiation.
Only traces of ozone were found in the PVC tube that was used to mimic the nasal passages during radiation, these concentrations were too low for human perception. However, ozone concentrations did reach potentially detectable levels in the treatment room.
The spin injection efficiencies in epitaxial Co2MnSi (CMS)/Pt thin films were investigated in spin pumping configuration. The inverse spin Hall (effect) voltage significantly depends on the ...post-annealing temperature Ta of CMS, which shows one order larger values than those of Fe and CoFe at Ta = 400 °C. The effective spin mixing conductance derived by the analytical model reaches 6.5 × 1019 m−2. Our findings suggest that the Co-based Heusler alloys could be promising material candidates as the spin injection source with spin pumping.
In human skin, the serine proteases kallikrein-related peptidase (KLK)5 and KLK7 degrade corneodesmosome proteins, leading to desquamation. Serine protease activity of the skin is tightly regulated ...by the interplay between such proteases and serine protease inhibitors, including lymphoepithelial Kazal-type related inhibitor (LEKTI), encoded by SPINK5; secretory leucocyte peptidase inhibitor (SLPI); and elafin. Expression of KLK5 and KLK7 is controlled and upregulated by stimulants such as calcium, 1,25-dihydroxyvitamin D
1,25(OH)
VD
and retinoic acid (RA).
To understand the effect of calcium, 1,25(OH)
VD
and RA on the expression of serine protease inhibitors in epidermal keratinocytes.
We stimulated normal human epidermal keratinocytes (NHEKs) with high calcium, 1,25(OH)
VD
or RA, and then analysed the expression of serine protease inhibitors using quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay and immunocytofluorescence. We also analysed trypsin- and chymotrypsin-like serine protease activities in stimulated NHEKs.
High calcium, but not 1,25(OH)
VD
or RA, significantly induced the expression of LEKTI, SLPI and elafin at both transcript and protein levels in NHEKs. These inductions were time- and dose-dependent. The activities of trypsin- and chymotrypsin-like serine proteases were significantly up- and downregulated by high calcium, respectively, in NHEKs.
High calcium, but not 1,25(OH)
VD
or RA, increases the expression of serine protease inhibitors in epidermal keratinocytes. Our findings contribute to the understanding of the mechanisms by which serine protease activities are regulated by serine proteases and related inhibitors in epidermal keratinocytes.
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