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1. Polysaccharide‐based H₂S donors: Thiol‐ene functionalization of amylopectin with H₂S ‐releasing N ‐thiocarboxyanhydrides

   https://doi.org/10.1002/pol.20240262  

   Chinn, Abigail F; Williams, Noah R; Miller, Kevin M; Matson, John B (September 2024, Journal of Polymer Science)

   Abstract Polymeric donors of gasotransmitters, gaseous signaling molecules such as hydrogen sulfide, nitric oxide, and carbon monoxide, hold potential for localized and extended delivery of these reactive gases. Examples of gasotransmitter donors based on polysaccharides are limited despite the availability and generally low toxicity of this broad class of polymers. In this work, we sought to create a polysaccharide H₂S donor by covalently attachingN‐thiocarboxyanhydrides (NTAs) to amylopectin, the major component of starch. To accomplish this, we added an allyl group to an NTA, which can spontaneously hydrolyze to release carbonyl sulfide and ultimately H₂S via the ubiquitous enzyme carbonic anhydrase, and then coupled it to thiol‐functionalized amylopectin of three different molecular weights (MWs) through thiol‐ene “click” photochemistry. We also varied the degree of substitution (DS) of the NTA along the amylopectin backbone. H₂S release studies on the six samples, termed amyl‐NTAs, with variable MWs (three) and DS values (two), revealed that lower MW and higher DS led to faster release. Finally, dynamic light scattering experiments suggested that aggregation increased with MW, which may also have affected H₂S release rates. Collectively, these studies present a new synthetic method to produce polysaccharide H₂S donors for applications in the biomedical field. 

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2. Generalized T _e ([O iii ])– T _e (He i ) Discrepancies in Ionized Nebulae: Possible Evidence of Case B Deviations and Temperature Inhomogeneities

   https://doi.org/10.3847/1538-4357/adc67a  

   Méndez-Delgado, J E; Skillman, E D; Aver, E; Morisset, C; Esteban, C; García-Rojas, J; Kreckel, K; Rogers, N_S J; Rosales-Ortega, F F; Arellano-Córdova, K Z; et al (June 2025, The Astrophysical Journal)

   Abstract The physics of recombination lines in the Heisinglet system is expected to be relatively simple, supported by accurate atomic models. We examine the intensities of Heisingletsλ3614, λ3965, λ5016, λ6678, and λ7281 and the triplet Heiλ5876 in various types of ionized nebulae and compare them with theoretical predictions to test the validity of the “Case B” recombination scenario and the assumption of thermal homogeneity. Our analysis includes 85 spectra from Galactic and extragalactic Hiiregions, 90 from star-forming galaxies, and 218 from planetary nebulae, all compiled by the Deep Spectra of Ionized Regions Database Extended (DESIRED-E) project. By evaluating the ratios Heiλ7281/λ6678 and Heiλ7281/λ5876, we determineT_e(Hei) and compare it with direct measurements ofT_e([Oiii]λ4363/λ5007). We find thatT_e(Hei) is systematically lower thanT_e([Oiii]) across most objects and nebula types. Additionally, we identify a correlation between the abundance discrepancy factor (ADF(O²⁺)) and the differenceT_e([Oiii]) –T_e(Hei) for planetary nebulae. We explore two potential explanations: photon loss fromn¹P → 1¹Stransitions and temperature inhomogeneities. Deviations from “Case B” may indicate photon absorption by Hirather than Heiand/or generalized ionizing photon escape, highlighting the need for detailed consideration of radiative transfer effects. If temperature inhomogeneities are widespread, identifying a common physical phenomenon affecting all ionized nebulae is crucial. Our results suggest that both scenarios can contribute to the observed discrepancies. 

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3. The ICOS OTCpCO₂ instrument intercomparison

   https://doi.org/10.1002/lom3.10727  

   Steinhoff, Tobias; Gkritzalis, Thanos; Jones, Steve; Macovei, Vlad A; Neill, Craig; Schuster, Ute; Akl, John; Arruda, Ricardo; Atamanchuk, Dariia; Barry, Mark; et al (August 2025, Limnology and Oceanography: Methods)

   Abstract In 2021, the Ocean Thematic Centre of the European Research Infrastructure “Integrated Carbon Observation System” conducted an international partial pressure of carbon dioxide (pCO₂) instrument intercomparison. The goal was to understand how different types of instrumentation for the measurement of oceanpCO₂compare to each other. During the two‐week long experiment, we installed various instruments in a tank facility using natural sea water (North Sea). These included direct air–water equilibration systems and membrane‐based flow‐through instruments along with submersible sensors and instruments that are normally installed on buoys and autonomous surface vehicles. In situ instruments were installed inside the tank and the flow‐through instruments were fed the same water using a pumping system. We changed the temperature (between 10°C and 28°C) and the seawaterpCO₂(between 250 and 800μatm) to observe instrument responses over a wide range. Since there is no reference for surface oceanpCO₂measurements, we agreed on a set of instruments serving as intercomparison reference. All data from the different instruments were then compared against the intercomparison reference during periods of stable temperature andpCO₂. The study provides important information to enhance future ocean carbon monitoring networks, but makes no direct recommendation for the use of any specific sensor. A major finding is that equilibration through direct air–water contact appears to be more consistent and independent of external factors than equilibration through a membrane or photometric detection. We found several instruments with no temperature measurements at the location of equilibration or with uncalibrated temperature sensors introducing significant uncertainty in the results. 

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4. Chemical composition tuning induced variable and enhanced dielectric properties of polycrystalline Ga_2‐2xW_xO₃ ceramics

   https://doi.org/10.1002/eng2.12300  

   Zade, Vishal B.; Rajkumar, Mohan R.; Broner, Ron; Ramana, Chintalapalle V. (January 2021, Engineering Reports)

   null (Ed.)
5. Climate drivers alter nitrogen availability in surface peat and decouple N₂ fixation from CH₄ oxidation in the Sphagnum moss microbiome

   https://doi.org/10.1111/gcb.16651  

   Petro, Caitlin; Carrell, Alyssa A.; Wilson, Rachel M.; Duchesneau, Katherine; Noble‐Kuchera, Sekou; Song, Tianze; Iversen, Colleen M.; Childs, Joanne; Schwaner, Geoff; Chanton, Jeffrey P.; et al (June 2023, Global Change Biology)

   Abstract Peat mosses ( Sphagnum spp.) are keystone species in boreal peatlands, where they dominate net primary productivity and facilitate the accumulation of carbon in thick peat deposits. Sphagnum mosses harbor a diverse assemblage of microbial partners, including N 2 ‐fixing (diazotrophic) and CH 4 ‐oxidizing (methanotrophic) taxa that support ecosystem function by regulating transformations of carbon and nitrogen. Here, we investigate the response of the Sphagnum phytobiome (plant + constituent microbiome + environment) to a gradient of experimental warming (+0°C to +9°C) and elevated CO 2 (+500 ppm) in an ombrotrophic peatland in northern Minnesota (USA). By tracking changes in carbon (CH 4 , CO 2 ) and nitrogen (NH 4 ‐N) cycling from the belowground environment up to Sphagnum and its associated microbiome, we identified a series of cascading impacts to the Sphagnum phytobiome triggered by warming and elevated CO 2 . Under ambient CO 2 , warming increased plant‐available NH 4 ‐N in surface peat, excess N accumulated in Sphagnum tissue, and N 2 fixation activity decreased. Elevated CO 2 offset the effects of warming, disrupting the accumulation of N in peat and Sphagnum tissue. Methane concentrations in porewater increased with warming irrespective of CO 2 treatment, resulting in a ~10× rise in methanotrophic activity within Sphagnum from the +9°C enclosures. Warming's divergent impacts on diazotrophy and methanotrophy caused these processes to become decoupled at warmer temperatures, as evidenced by declining rates of methane‐induced N 2 fixation and significant losses of keystone microbial taxa. In addition to changes in the Sphagnum microbiome, we observed ~94% mortality of Sphagnum between the +0°C and +9°C treatments, possibly due to the interactive effects of warming on N‐availability and competition from vascular plant species. Collectively, these results highlight the vulnerability of the Sphagnum phytobiome to rising temperatures and atmospheric CO 2 concentrations, with significant implications for carbon and nitrogen cycling in boreal peatlands. 

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