Results for “NdHf” | Engineering Papers

DOE OSTI2020

Materials Data on NdHf by Materials Project

HfNd crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Nd is bonded to six equivalent Nd and six equivalent Hf atoms to form NdNd6Hf6 cuboctahedra that share corners with eighteen equivalent NdNd6Hf6 cuboctahedra, edges with six equivalent NdNd6Hf6 cuboctahedra, edges with twelve equivalent HfNd6Hf6 cuboctahedra, faces with eight equivalent NdNd6Hf6 cuboctahedra, and faces with twelve equivalent HfNd6Hf6 cuboctahedra. All Nd–Nd bond lengths are 3.38 Å. All Nd–Hf bond lengths are 3.41 Å. Hf is bonded to six equivalent Nd and six equivalent Hf atoms to form HfNd6Hf6 cuboctahedra that share corners with eighteen equivalent HfNd6Hf6 cuboctahedra, edges with six equivalent HfNd6Hf6 cuboctahedra, edges with twelve equivalent NdNd6Hf6 cuboctahedra, faces with eight equivalent HfNd6Hf6 cuboctahedra, and faces with twelve equivalent NdNd6Hf6 cuboctahedra. All Hf–Hf bond lengths are 3.38 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Plastome evolution in annual Brachypodium species reveals widespread heteroplasmy and chloroplast capture, lineage-specific codon usage bias, and low positive selection

Comparative genomics and plastome phylogenomics have advanced significantly in recent years, highlighting the diversity, possible admixture, and non-neutral evolution of the predominantly considered non-recombinant chloroplast genomes in angiosperms. The grass genus Brachypodium serves as a powerful model for studying evolutionary processes in monocots. We analyzed 287 plastomes across the native circum-Mediterranean range of the three annual Brachypodium species ( B. distachyon, B. stacei, B. hybridum ), focusing on their structural variation, selection patterns and phylogenomic relationships. Our analyses confirmed the differentiation of the S and D plastomes, inherited respectively from the diploid progenitor species B. stacei and B. distachyon . We identified novel structural rearrangements and indels, and unique repeat motifs, along with widespread heteroplasmy, particularly in ancestral B. hybridum -D plastotypes. SNP diversity varied among plastotypes, reflecting population dynamics and evolutionary histories, with B. hybridum -D plastotypes showing the highest normalized diversity and B. hybridum -S the lowest. Positive selection was detected in 29 plastid genes by Tajima’s neutrality test, and in nine genes by site and branch-site evolutionary models, including matK, ndhF, rbcL, and rpoC2. Phylogenomic analyses revealed well-supported clades corresponding to the S and D plastome lineages, with frequent chloroplast capture events and long-distance dispersals shaping their evolutionary trajectories.

allopolyploidy↗