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Gold nanoclusters are known for their good biocompatibility and low cytotoxicity;with encapsulated metal atoms gold nanoclusters can not only have more stable structures than hollow clusters,but also change their own chemical and physical properties,which is of great importance to the applications of actinide elements in nuclear medicine with much reduced potential cytotoxicity.In this study,we designed the uranium-encapsulated structure U@Au14 based on a typical Au14-cage structure and found that the existence of the U atom indeed makes the Au14 structure more stable.Analysis of the electron structure shows that the two single-occupied orbitals in the system mainly originate from the Sf shell of the U atom after charge transfer.This provides a theoretical basis for future syntheses of actinide doped gold inanoclusters,and thus should facilitate biomedical applications of such nanostructures in radio-labeling,nanodrug carrier and so forth.Meanwhile,effective cleanup of radioactive waste remains one of the fundamental challenges in nuclear sciences due to the ever growing concern on the safety of nuclear power.Carbon nanotubes have recently shown encouraging promises in their potential capability of U atom adsorption and removal.We used first-principle density functional theory (DFT) to illustrate the adsorption and interactions between U atoms and the inner/outer surfaces of a single-walled carbon nanotube.Our DFT calculations showed that when U atoms were adsorbed on each of the CNT surfaces,the ground electronic states were quintet.However,U atoms showed a differential adsorption mode depending on its binding sites,either the bridge sites on the inner surface or the hole sites on the outer surface.The interior adsorption was more stable with adsorption energy of l eV greater than that of the external one,which is explained by their different ground state electronic structures.Further analysis on the density of states indicated that the internal adsorption had larger bonding area between the U atoms and CNT,supporting the stronger internal adsorption.