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SUMMARY MYC is a highly pleiotropic transcription factor whose deregulation promotes cancer. In contrast, we find that Myc haploinsufficient (Myc+/−) mice exhibit increased lifespan. They show resistance to several age-associated pathologies, including osteoporosis, cardiac fibrosis and immunosenescence. They also appear to be more active, with a higher metabolic rate and healthier lipid metabolism. Transcriptomic analysis reveals a gene expression signature enriched for metabolic and immune processes. The ancestral role of MYC as a regulator of ribosome biogenesis is reflected in reduced protein translation, which is inversely correlated with longevity. We also observe changes in nutrient and energy sensing pathways, including reduced serum IGF-1, increased AMPK activity, and decreased AKT, TOR and S6K activities. In contrast to observations in other longevity models, Myc+/− mice do not show improvements in stress management pathways. Our findings indicate that MYC activity has a significant impact on longevity and multiple aspects of mammalian healthspan.

While manganese oxide (MnO2) has been extensively studied as an electrode material for pseudocapacitors, a clear understanding of its charge storage mechanism is still lacking. Here we report our findings in probing the structural changes of a thin-film model MnO2 electrode during cycling using in operando Raman spectroscopy. The spectral features (e.g., band position, intensity, and width) are correlated quantitatively with the size (Li+, Na+, and K+) of cations in different electrolytes and with the degree of discharge to gain better understanding of the cation-incorporation mechanism into the interlayers of pseudocapacitive MnO2. Also, theoretical calculations of phonon energy associated with the models of interlayer cation-incorporated MnO2 agree with the experimental observations of cation-size effect on the positions of Raman bands. Furthermore, the cation-size effects on spectral features at different potentials of MnO2 electrode are correlated quantitatively with the amount of charge stored in the MnO2 electrode. The understanding of the structural changes associated with charge storage gained from Raman spectroscopy provides valuable insights into the cation-size effects on the electrochemical performances of the MnO2 electrode.

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