Double Helix of Icosahedra Structure and Spin Glass Magnetism of the δ-Co2.5Zn17.5-xMnx (x = 0.4-3.5) Pseudo-Binary Alloys.

We have synthesized δ-Co2.5Zn17.5-xMnx (x = 0.4-3.5) pseudo-binary alloys of 10 different compositions by a high-temperature solid-state synthetic route, determined their crystal structures and the Mn substitution pattern, and estimated the existence range of the δ-phase. The alloys crystallize in two chiral enantiomorphic space groups P62 and P64, where the basic atomic polyhedron of the chiral structure is an icosahedron and the neighboring icosahedra share vertices to form an infinitely long double helix along the hexagonal axis (like in the δ-Co2.5Zn17.5 parent binary phase). The alloys are pure δ-phase up to the Mn content x ≈ 3.5. The Mn atoms partially substitute Zn atoms at particular crystallographic sites located on the icosahedra. The study of magnetism was performed on the Co2.5Zn17.1Mn0.4 alloy with the lowest Mn content. Contrary to the expectation that structural chirality may induce the formation of a nontrivial magnetic state, a spin glass state with no relation to the structural chirality was found. The magnetic sublattice contains all of the necessary ingredients (randomness and frustration) for the formation of a spin glass state. Typical out-of-equilibrium dynamic phenomena of a spin system with broken ergodicity were detected below the spin freezing temperature Tf ≈ 8 K.

Mutational spectra of SARS-CoV-2 orf1ab polyprotein and signature mutations in the United States of America.

The pandemic COVID-19 outbreak has been caused due to SARS-CoV-2 pathogen, resulting in millions of infections and deaths worldwide, the United States being on top at the present moment. The long, complex orf1ab polyproteins of SARS-CoV-2 play an important role in viral RNA synthesis. To assess the impact of mutations in this important domain, we analyzed 1134 complete protein sequences of the orf1ab polyprotein from the NCBI virus database from affected patients across various states of the United States from December 2019 to 25 April 2020. Multiple sequence alignment using Clustal Omega followed by statistical significance was calculated. Four significant mutations T265I (nsp 2), P4715L (nsp 12), and P5828L and Y5865C (both at nsp 13) were identified in important nonstructural proteins, which function either as replicase or helicase. A comparative analysis shows 265 T→I, 5828 P→L, and 5865Y→C are unique to the United States and not reported from Europe or Asia; while one, 4715 P→L is predominant in both Europe and the United States. Mutational changes in amino acids are predicted to alter the structure and function of the corresponding proteins, thereby, it is imperative to consider the mutational spectra while designing new antiviral therapeutics targeting viral orf1ab.