High Resolution Electron Microscopy of Radiation Defects in Ordered Alloys Induced by 1 MeV Electrons

Radiation defects induced by 1 MeV electrons in Zr_3Al, Au_3Cd and Au_3Mn have been investigated by high voltage high resolution electron microscopy. For the Ll_2 type intermetallic compound Zr_3Al, the changes in contrast of the superstructure images with electron irradiation suggest that the replacement disordering occurs in atom rows parallel to the incident beam. Neither dislocation loops nor voids are observed in the specimens damaged to 0.5 dpa. In the Au-Cd alloys, dislocation loops smaller than one nm in radius are identified at the electron irradiation of 2×10^ cm^. As for the Au-Mn alloys, dislocation loops are formed with preferential displacement of Mn atoms rather than Au atoms. The image contrast of irradiated Zr_3Al is discussed in comparison with the images computated by the multislice method

Real-space observation of short-period cubic lattice of skyrmions in MnGe

Emergent phenomena and functions arising from topological electron-spin textures in real space or momentum space are attracting growing interest for new concept of states of matter as well as for possible applications to spintronics. One such example is a magnetic skyrmion, a topologically stable nanoscale spin vortex structure characterized by a topological index. Real-space regular arrays of skyrmions are described by combination of multi-directional spin helixes. Nanoscale configurations and characteristics of the two-dimensional skyrmion hexagonal-lattice have been revealed extensively by real-space observations. Other three-dimensional forms of skyrmion lattices, such as a cubic-lattice of skyrmions, are also anticipated to exist, yet their direct observations remain elusive. Here we report real-space observations of spin configurations of the skyrmion cubic-lattice in MnGe with a very short period (~3 nm) and hence endowed with the largest skyrmion number density. The skyrmion lattices parallel to the {100} atomic lattices are directly observed using Lorentz transmission electron microscopes (Lorentz TEMs). It enables the first simultaneous observation of magnetic skyrmions and underlying atomic-lattice fringes. These results indicate the emergence of skyrmion-antiskyrmion lattice in MnGe, which is a source of emergent electromagnetic responses and will open a possibility of controlling few-nanometer scale skyrmion lattices through atomic lattice modulations

Magnetic Domain of Fe

Magnetic flux in soft magnetic alloy Fe 73:5 Cu 1 Nb 3 Si 13:5 B 9 was investigated by electron holography coupled with a thickness mapping method. First the reconstructed phase image of a soft magnetic material with a simple wedge shape was simulated, and the contribution of both magnetic flux and inner potential to the reconstructed phase image was estimated. In the experiment, the magnetic flux was evaluated by removing the effect of inner potential with thickness mapping. The magnetic flux density of Fe 73:5 Cu 1 Nb 3 Si 13:5 B 9 obtained was 1.21 T which agreed well with that of a bulk specimen (1.28 T)

糖尿病誘発性慢性腎疾患モデル動物―尿細管障害バイオマーカーによる検討―

Diabetes-induced chronic kidney disease（ DCKD） is a serious health problem. Therefore, modalities for preventing/improving DCKD are required. The aim of this study was to establish an animal model of DCKD. Four five-week-old male OLETF and LETO rats were used as experimental and control animals, respectively. After both rats were raised 17 months, collections of urine, blood and bilateral kidneys were performed. Urinary biomarkers for renal proximal tubule injury, monocyte chemoattractant protein-1（ MCP-1） and kidney injury molecule-1（ KIM-1）, were measured by the Bio-Plex system. OLETF rats showed a significant increase in blood glucose, Hb A1c, creatinine, blood urea nitrogen（ BUN）, kidney/body weight ratio, glomerular area, 24 h-urine volume, urinary protein concentrations, MCP-1 and KIM-1 compared with LETO rats. There was a positive correlation not only between BUN and MCP-1 or KIM-1 but also between urinary protein concentrations and MCP-1 or KIM-1. These results indicate that the present OLETF rats have both glomerular and proximal tubular injury. Thus, the aged male OLETF rats with long-term diabetes may become a potent animal model for examining effects of exercise/dietary therapies on DCKD