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A multi-component mixed acid was prepared by simulating the composition of exhaust gas recirculation condensate, and the effects of the multi-component mixed acid solution on the mechanical properties, apparent morphology and thermal stability of silicone rubber, fluororubber and ethylene-acrylate rubber were investigated. The results showed that after corrosion, the mechanical properties and surface morphology of fluororubber and ethylene-acrylate rubber remained good, while cracks appeared on the surface of silicone rubber and its tensile strength and elongation at break decreased significantly by 86.6% and 90.3%, respectively. Thermal stability of fluororubber remained good, while the initial decomposition temperature of ethylene-acrylate rubber and silicone rubber increased.

For the first time site-specific doping of silver into a spherical Au 25 nanocluster has been achieved in [Au 19 Ag 6 (MeOPhS) 17 (PPh 3 ) 6 ] (BF 4 ) 2 (Au 19 Ag 6 ) through a dual-ligand coordination strategy. Single crystal X-ray structural analysis shows that the cluster has a distorted centered icosahedral Au@Au 6 Ag 6 core of D 3 symmetry, in contrast to the I h Au@Au 12 kernel in the well-known [Au 25 (SR) 18 ] - (R = CH 2 CH 2 Ph). An interesting feature is the coexistence of [Au 2 (SPhOMe) 3 ] dimeric staples and [P-Au-SPhOMe] semi-staples in the title cluster, due to the incorporation of PPh 3 . The observation of only one double-charged peak in ESI-TOF-MS confirms the ordered doping of silver atoms. Au 19 Ag 6 is a 6e system showing a distinct absorption spectrum from [Au 25 (SR) 18 ] - , that is, the HOMO-LUMO transition of Au 19 Ag 6 is optically forbidden due to the P character of the superatomic frontier orbitals., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)