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Metal clusters, such as iron-sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins. Herein we report the formation and crystal structure of a planar square tetranuclear silver cluster when silver ions were mixed with human copper chaperone Atox1. Quantum chemical studies reveal that two Ag 5s

Partitioning of americium from lanthanides (Ln) present in used nuclear fuel plays a key role in the sustainable development of nuclear energy. This task is challenging because of the chemical similarities between Am(III) and Ln(III). Oxidization of Am(III) to Am(VI) has the potential to facilitate separations in principle, but rapid reduction of Am(VI) back to Am(III) by radiolysis products and organic reagents required for the traditional solvent extraction/solid extraction processes hampers practical redox-based separations. Herein, we report a nanoscale polyoxometalate (POM) cluster with a vacancy site compatible with the selective coordination of hexavalent actinides (238U, 237Np, 242Pu, and 243Am) over trivalent lanthanides in nitric acid media. This cluster is the most stable Am(VI) species in aqueous media observed to date. Ultrafiltration-based separation of nanoscale Am(VI)-POM clusters from hydrated lanthanide ions by commercially-available, fine-pored membranes enables the development of a once-through americium/lanthanide separation strategy that is highly efficient, rapid, environmentally benign, and requires minimal energy input.

Unstable thermal stratification, quantified by the Richardson number (Ri) herein, has important effects on pollutant dispersion. In this study, the impacts of unstable thermal stratification on airflow and pollutant dispersion around a rectangular building are investigated through large eddy simulation (LES), in which a wide range of Richardson numbers (−1.5–0) is considered. Increasing instability enhances the removal of pollutant near the ground with strengthened advection and turbulence, and thus results in lower normalized pollutant concentration near the ground and higher concentration around the building height. Meanwhile, the streamwise length of the recirculation region behind the building decreases by 32% when Ri decreases from 0 to −1.5, which further enhances pollutant dispersion behind the building. In terms of pollutant dispersion behind the building where the recirculation region emerges, the advection flux of concentration plays a crucial role, which is nearly four times the turbulent diffusion flux in magnitude when Ri ​= ​−1.5. On the other hand, near the boundaries of the recirculation region, turbulent diffusion flux is non-negligible in transporting the pollutant along the concentration gradient. With lower stability, the proportions of fluctuation energy of velocity and concentration in the low-frequency range decrease behind the building compared to those in the high-frequency range.