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We aimed to investigate SARS-CoV-2 emerging lineage harboring variants in receptor binding domain (RBD) of spike protein in Japan. Total nucleic acids were subjected to whole genome sequencing on samples from 133 patients with coronavirus disease (COVID-19). We obtained the SARS-CoV-2 genome sequence from these patients and examined variants in RBD. As a result, three patients were infected with SARS-CoV-2 harboring E484K mutation in January 2021. These three patients were relatives; one was in the 40s, and two were younger than 10 years old. They had no history of staying abroad and were living in Japan. This strains were classified into GR clade (GISAID), 20B clade (Nextstrain) and R.1 lineage (PANGO). As of March 5, 2021, the R.1 lineage have been identified in 305 samples and dominantly observed in the USA (44%, 135 / 305) and Japan (28%, 84 / 305) from the GISAID database. During the period between October 26, 2020 and February 23, 2021, the frequency of the R.1 lineage was 0.97% (84 / 8,629) of the total confirmed data in Japan and 0.15% (135 / 90,450) in the USA. Although SARS-CoV-2 R.1 lineage was not globally predominant as of March 2021, further analysis is needed to determine whether R.1 variant will disappear or expand in the future.

Disappearance of long-range atomic order in 10-nm-sized L10-FePd (Fe-58 at%Pd) nanoparticles has been studied by electron diffraction using a specimen heating stage attached to a transmission electron microscope. Ordered structure is kept at lowest up to 949 K, while the intensity of superlattice reflection abruptly drops at 982 K. The transformation temperature decreases by about 80 K compared to that of the bulk alloy of Fe-58 at%Pd. Nanobeam electron diffraction from a particle shows a particle size dependence of the transformation temperature and the intensity of 110 superlattice reflection largely decreases below about 15 nm in diameter at 983 K. However, a weak intensity remains in the 110 superlattice reflection even at 983 K, which is attributed to short-range order in the nanoparticles. © 2006 The Japan Institute of Metals.

Two-dimensionally dispersed L10-FePt nanoparticles as small as 12 nm with orientation was fabricated by electron-beam evaporation and post-annealing at 873 K. After a prolonged annealing at 873 K for 86.4 ks, the increase of coercivity was almost saturated and coercivity reached 434 kAm -1 at 300 K, which is very small compared to recent reports on FePt nanoparticles with sizes larger than 20 nm. Long-range order parameter of the fabricated nanoparticles was determined by electron diffraction at 200 kV taking the multiple scattering into consideration. Obtained order parameter remained 0.55 ± 0.02 for the nanoparticles with an axial ratio c/a of 0.961 ± 0.003. The low degree of order is thought to be responsible for the small coercivity. Effect of Debye-Waller factor on the order parameter was discussed.