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Abstract Persulfides (RSS^–) and thioselenides (RSSe^–) play important roles in biological S and Se transfer reactions, and their interactions with Lewis acidic moieties exert control over reactivity. Here, we report the synthesis and reactivity of mononuclear Zn²⁺persulfide and thioselenide complexes from a unified synthetic strategy of using isolable dichalcogenide precursors. Highlighting the benefits of replacing S with Se, we use⁷⁷Se NMR spectroscopy to reveal the effects of Lewis acid coordination (K⁺, Na⁺, Zn²⁺) on the electronic environment of the terminal Se of the thioselenide (R–S_β–Se_α^–). Coordination of RSSe^–to Zn²⁺polarizes the Se─S bond, rendering the internal sulfur atom (R–S_β–Se_α^–) susceptible to nucleophilic attack and resulting in selenide (Se^2–) release. We also prepared a mononuclear Zn²⁺persulfide complex and probed differences in persulfide nucleophilicity when compared to the parent thiolate. Alkylation of the Zn²⁺persulfide is considerably faster than the Zn²⁺thiolate, supporting the proposed nucleophilicity enhancement of persulfides due to the α‐effect, and providing new insights into persulfide reactivity when coordinated to metals. Taken together, these investigations highlight the utility of small molecule synthetic models in advancing insights into the biological chemistry of metal dichaclogenides. 

Hydrogen selenide (H2Se) is an emerging bioregulator and precursor to essential selenium-containing biomolecules. We show that aryl isoselenocyanates (ISeC-R) release H2Se upon activation by cysteine, and that electronic substitution can modulate release profiles. We also demonstrate applications to live cell imaging, expanding available tools for investigating H2Se chemical biology. 

Abstract Specific ions can be intercalated into functional materials using the electrolyte gating technique, which has been widely used to regulate channel conductance in transistors and develop low‐power neuromorphic devices. However, in these devices, fundamental exploration of ion intercalation‐induced structural phase transitions remains largely overlooked and rarely explored. Here, the lithium‐based electrolyte gating technique is used to probe the collective interactions between ions, lattices, and electrons in a van der Waals ferroelectric semiconductor α‐In₂Se₃. Using a polymer electrolyte as the lithium‐ion reservoir and α‐In₂Se₃as the channel material, the intercalated lithium concentration via a gate electric field is modulated. This manipulation drives a phase transition in α‐In₂Se₃from a ferroelectric semiconductor to a dirty metal and finally to a metal, accompanied by a structural transformation. Concurrently, with enhanced intercalation, the ferroelectric hysteresis window progressively narrows and eventually disappears, indicating the evolution from switchable to non‐switchable polarization. This study represents a promising platform for the artificial construction of correlated material systems, enabling a systematic investigation into the interaction of ferroelectricity and electronic conduction using ion intercalation. 

Abstract Gelatinous zooplankton serve diverse ecological roles in shelf food webs—from grazers to predators. However, their spatial niches are poorly resolved, especially at detailed taxonomic levels, due to conventional techniques that are unable to measure distributions at fine spatial scales. Seasonal in situ imaging transects across the dynamic northern Gulf of Mexico demonstrated that taxonomic diversity of gelatinous zooplankton increases with stratification and habitat heterogeneity. Taxa displayed low spatial niche overlap (~ 10%, Schoener'sD), independent of season (stratified, river‐influenced, and well mixed), and even when associated with similar water mass properties. This suggests that oceanography structures the distributions of gelatinous organisms and water mass preferences, but ecological interactions among taxa generate distinct taxon‐specific spatial niches. Although automated image classification algorithms currently prioritize broad taxonomic groups, detailed identifications and improved resolution of interactions (predator–prey, competition, etc.) may underlie a predictive framework for gelatinous abundances and diversity. 

Abstract M₅X₄MXenes, a subclass of 2D transition metal carbides, have attracted attention as the thickest 2D material synthesized. Early studies show their promising electrocatalytic activity but overlooked how metal composition and interlayer spacing affect hydrogen evolution reaction (HER). To address this gap, three M₅X₄MXenes, Mo₄VC₄, (TiTa)₅C₄, and (TiNb)₅C₄, are systematically studied and their interlayer spacing and composition modulated through ion exchange with tetramethyl ammonium (TMA⁺vs. Li⁺), providing new insights into their HER activity. These findings reveal that TMA⁺‐intercalated Mo₄VC₄exhibits superior HER activity, achieving areal and gravimetric overpotentials of 172 and 90 mV, respectively, due to its composition (presence of Mo) and expanded interlayer spacing that enhances proton accessibility. The Li⁺exchange increases the overpotential to 212 and 131 mV at 10 mA areal and gravimetric current density, respectively, as reduced interlayer spacing restricts access to active Mo sites. In contrast, (TiNb)₅C₄and (TiTa)₅C₄display higher overpotentials, making them more suitable for supercapacitor or aqueous battery applications due to the wider electrochemical window. This study provides critical insights into the interplay between metal composition and interlayer engineering in M₅X₄MXenes, establishing TMA‐Mo₄VC₄as a promising candidate for sustainable hydrogen production. 

Abstract Hydrogen sulfide (H₂S) and nitric oxide (NO) are important gaseous biological signaling molecules that are involved in complex cellular pathways. A number of physiological processes require both H₂S and NO, which has led to the proposal that different H₂S/NO⋅ crosstalk species, including thionitrite (SNO⁻) and perthionitrite (SSNO⁻), are responsible for this observed codependence. Despite the importance of these S/N hybrid species, the reported properties and characterization, as well as the fundamental pathways of formation and subsequent reactivity, remain poorly understood. Herein we report new experimental insights into the fundamental reaction chemistry of pathways to form SNO⁻and SSNO⁻, including mechanisms for proton‐mediated interconversion. In addition, we demonstrate new modes of reactivity with other sulfur‐containing potential crosstalk species, including carbonyl sulfide (COS). 

Abstract In Earth history, our understanding of how large‐bodied herbivores shape a variety of ecosystem processes is limited by the quality of paleoecological proxies for herbivore composition and abundance. Fecal stanols are lipids that can be produced by microbes within animal digestive systems and that could remedy this dearth of proxies. We used two multi‐decadal herbivore exclosures in Kruger National Park, South Africa, to constrain whether and how biomarker signatures preserve signals of herbivore abundance. Soil samples and dung counts were collected along transects across crests, mid‐slopes, and sodic sites inside and outside exclosures. Soils were analyzed for steroid (sterols and stanols) concentrations and distributions. We found that stanol concentrations were significantly greater in sodic soils outside exclosures, where herbivore dung densities were greatest. In contrast, sterol concentrations did not differ between treatments. Ratios of stanol isomers to sterols, which account for both compound degradation and source, increased strongly with herbivore dung counts. Finally, while herbivore species compositions influenced steroid distributions, total herbivore abundance was their strongest predictor. Further calibration is needed, but this work provides strong preliminary evidence that wild herbivore populations are quantitatively recorded by fecal biomarker distributions.