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Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the core reactions of a series of advanced modern energy and conversion technologies, such as fuel cells and metal–air cells. Among all kinds of oxygen electrocatalysts that have been reported, single‐atom catalysts (SACs) offer great development potential because of their nearly 100% atomic utilization, unsaturated coordination environment, and tunable electronic structure. In recent years, numerous SACs with enriched active centers and asymmetric coordination have been successfully constructed by regulating their coordination environment and electronic structure, which has brought the development of atomic catalysts to a new level. This paper reviews the improvement of SACs brought by atom‐level interface engineering. It starts with the introduction of advanced techniques for the characterizations of SACs. Subsequently, different design strategies that are applied to adjust the metal active center and first coordination sphere of SACs and then enhance their oxygen electrocatalysis performance are systematically illustrated. Finally, the future development of SACs toward ORR and OER is discussed and prospected. [ABSTRACT FROM AUTHOR]

To date, viroids have been found to naturally infect only plants, resulting in substantial losses for some crops. Whether viroids or viroid‐like RNAs naturally infect non‐plant hosts remains unknown. Here the existence of a set of exogenous, single‐stranded circular RNAs, ranging in size from 157 to 450 nucleotides, isolated from the fungus Botryosphaeria dothidea and nominated B. dothidea RNAs (BdcRNAs) is reported. BdcRNAs replicate autonomously in the nucleus via a rolling‐circle mechanism following a symmetric pathway. BdcRNA infection induces symptoms, because BdcRNAs can apparently modulate, to different degrees, specific biological traits (e.g., alter morphology, decrease growth rate, attenuate virulence, and increase or decrease tolerance to osmotic and oxidative stress) of the host fungus. Overall, BdcRNAs have genome characteristics similar to those of viroids and exhibit pathogenic effects on fungal hosts. It is proposed that these novel fungus infecting RNAs should be termed mycoviroids. BdcRNA(s) may be considered additional inhabitants at the frontier of life in terms of genomic complexity, and represent a new class of acellular entities endowed with regulatory functions, and novel epigenomic carriers of biological information. [ABSTRACT FROM AUTHOR]

B Viroid-Like RNAs b In article number 2204308, Wenxing Xu, Kaili Dong, and co-workers characterize a novel class of viroid-like RNAs naturally infecting a filamentous fungus I Botryosphaeria dothidea i isolated from apple and termed as mycoviroids. Novel Viroid-Like RNAs Naturally Infect a Filamentous Fungus (Adv. Sci. 3/2023) This is the first report of infectious viroid-like RNAs (or exogenous small circular RNAs) in a life kingdom (fungi) other than plants. [Extracted from the article]