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Earth-abundant manganese-based oxides have shown promise to replace costly noble-metal-based catalysts in state-of-the-art proton exchange membrane fuel cells and electrolyzers. However, the practical utilization of Mn-based oxides in these acidic technologies has been severely hindered by their dissolution at low pHs. Designing Mn-based oxides with enhanced durability in acid requires a fundamental understanding of the physical origin of their instability. In this work, combining dissolution kinetic studies and first-principles calculations, we systematically quantified the dissolution of Mn-based oxides in acid and identified intrinsic material descriptors that govern their acid stability. We found that lowering the Mn oxidation states in Mn-based oxides to decrease Mn-O covalency and weaken Mn-O bonds led to greater driving forces for critical reaction steps, including protonation, vacancy formation, and ion solvation, rendering poorer stability and faster dissolution kinetics upon exposure to acid. Such correlations for the stability of oxides in acid were further validated by a computational screening of 1000 Mn-based oxides. Notably, limiting the fraction of ionic substituents in oxides and using metal substituents with greater electronegativity/acidity were found to stabilize Mn-based oxides against dissolution in acid. These findings establish new guiding principles to design and optimize oxides with enhanced durability in acid for clean energy applications.

BACKGROUND: Previous research on body image distress mainly relied on samples that were small, generally homogeneous in age or sex, often limited to one geographical region, and were characterized by a lack of comprehensive analysis of multiple psychosocial domains. The research presented in this paper extends the international literature using the results of the web-based Global Health and Wellbeing Survey 2015. The survey included a large sample of both men and women aged ≥16 years from Australia, Canada, New Zealand, the United Kingdom, or the United States. OBJECTIVE: The main objectives of this study are to examine body image distress across the adult life span (≥16 years) and sex and assess the association between body image distress and various psychosocial risk and protective factors. METHODS: Data were extracted from the Global Health and Wellbeing Survey 2015, a web-based international self-report survey with 10,765 respondents, and compared with previous web-based surveys conducted in 2009 and 2012. RESULTS: The body image distress of young Australians (aged 16-25 years) significantly rose by 33% from 2009 to 2015. In 2015, 75.19% (961/1278) of 16- to 25-year-old adults reported body image distress worldwide, and a decline in body image distress was noted with increasing age. More women reported higher levels of body image distress than men (1953/3338, 58.51% vs 853/2175, 39.22%). Sex, age, current dieting status, perception of weight, psychological distress, alcohol and other substance misuse, and well-being significantly explained 24% of the variance in body image distress in a linear regression (F15,4966=105.8; P<.001). CONCLUSIONS: This study demonstrates the significant interplay between body image distress and psychosocial factors across age and sex.