Cost-Effectiveness of Nirmatrelvir/Ritonavir in COVID-19 Patients at High-Risk for Progression in Spain.

The objective was to estimate the cost-effectiveness of nirmatrelvir/ritonavir (NMV/r) in treating adults with COVID-19 at high-risk of developing severe COVID-19 who do not require supplemental oxygen, compared to no treatment, from the Spanish National Health System (NHS) perspective. A decision-tree for the first year followed by a two-state Markov model with annual cycles for a lifetime horizon was developed. A cohort of 1000 high-risk, symptomatic COVID-19 patients entered the decision-tree for each comparator, divided into hospitalized patients, considering their level of care, and outpatients, for whom only symptom duration was considered.

General theory for packing icosahedral shells into multi-component aggregates.

Multi-component aggregates are being intensively researched in various fields because of their highly tunable properties and wide applications. Due to the complex configurational space of these systems, research would greatly benefit from a general theoretical framework for the prediction of stable structures, which, however, is largely incomplete at present. Here we propose a general theory for the construction of multi-component icosahedral structures by assembling concentric shells of different chiral and achiral types, consisting of particles of different sizes.

Coalescence-induced shape transformations in Pd and AuPd clusters.

The coalescence of pure Pd and Pd-rich AuPd nanoparticles is studied by molecular dynamics simulations. The collision of icosahedral nanoparticles with face-centered-cubic truncated octahedral ones is considered. These structures are considered because they have been experimentally shown to be the most stable for AuPd nanoalloys and for pure Pd clusters.

Tetrahedral Clusters Stabilized by Alloying.

A family of nanoclusters of tetrahedral symmetry is proposed. These clusters consist of symmetrically truncated tetrahedra with additional hexagonal islands on the four facets of the starting tetrahedron. The islands are placed in stacking fault positions.

Sudden collective atomic rearrangements trigger the growth of defect-free silver icosahedra.

The growth of Ag clusters on amorphous carbon substrates is studied by X-ray scattering experiments, whose final outcome is imaged by electron microscopy. The real-time analysis of the growth process at room temperature shows the formation of a large majority of icosahedral structures by a shell-by-shell growth mode which produces smooth and nearly defect-free structures. Molecular dynamics simulations supported by calculations reveal that the shell-by-shell mode is possible because of the occurrence of collective displacements which involve the concerted motion of many atoms of the growing shell.