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ABSTRACT We describe the synthesis and characterization of supramolecular networks based on charge‐assisted hydrogen bonding interactions of guanidinium and oxyanion functionalities. Although they are constructed entirely of small‐molecule components, these materials display properties such as a glass transition and time‐ and temperature‐dependent viscoelastic rheological behavior. These properties can be tuned by the choice of each network component:T_gvaries by over 50°C in the studied networks, and relaxation times scaled with changes toT_g. However, these supramolecular materials are inherently degradable and thermally reversible as no covalent macromolecular structure is formed. 

Summary Microalgae adapted to near‐zero temperatures and high light levels live on snowfields and glaciers worldwide. Snow algae have red‐colored pigments that darken snow surfaces, lowering its albedo and accelerating snowmelt. Despite their importance to the cryosphere, we know little about controls on snow algal productivity and biomass.Here, we characterize photophysiology from diverse natural field‐collected populations of alpine snow algae from the North Cascades of Washington, USA, where the major red‐bloom producing generaChlainomonas,Sanguina, andRosettawere present. We tested short‐term physiological responses of snow algae to light (0–3000 μmol m⁻² s⁻¹) and CO₂levels (0–1600 ppm), allowing us to determine the saturating light and CO₂levels for snow algal community net photosynthesis.All snow algal communities surveyed were adapted to extremely high light levels (3000 μmol m⁻² s⁻¹). In addition, photosynthesis rates of all the snow algal communities responded strongly to increasing CO₂levels. At current atmospheric CO₂levels (420 ppm), snow algal net photosynthesis rates were onlyc.50% saturated.Together, these results suggest the primary productivity of important bloom‐forming snow algal communities in alpine ecosystems will likely rise as atmospheric CO₂concentrations increase, regardless of potential changes in available light levels. 

Continuous centrifugation of the reaction mixture can impact the trajectory of a palladium-catalyzed C–H arylation reaction in which catalytically relevant nanoparticles are formingin situfrom a molecular precatalyst. 

Investigating electron transfer behavior under external electric fields in molecular electronics is crucial for understanding the function of each component and for improving molecular design. Notably, the one-electron transfer is inevitable in molecular wires and switches, for which traditional density functional theory (DFT) and long-range corrected self-consistent-charge density functional tight binding (LC-DFTB) meet significant challenges. Inspired by previous studies on constrained configuration interaction schemes, we present restriction-based configuration interaction (RCI) LC-DFTB, a novel extension of LC-DFTB to deliver an accurate description of one-electron transfer under external electric fields. This approach retains the low cost of LC-DFTB while accurately capturing charge-resonance, localization versus delocalization, and field-induced response in large, structurally complex systems. We demonstrate its performance on a benzene assembly and a polyfluorene, showing that RCI-LC-DFTB efficiently describes the effects of molecular conformation and applied bias on electron localization and transfer. Our method thus provides a robust, scalable tool for the design of molecular electronic and organic photovoltaic materials. 

Abstract Intraspecific trait variation (ITV) is an increasingly important aspect of biodiversity and can provide a more complete perspective on how abiotic and biotic processes affect individuals, species' niches and ultimately community‐level structure than traditional uses of trait means. Body size serves as a proxy for a suite of traits that govern species' niches. Distributions of co‐occurring species body sizes can inform niche overlap, relate to species richness and uncover mechanistic drivers of diversity.We leveraged individual‐level body size (length) in freshwater fishes and environmental data from the National Ecological Observatory Network (NEON) for 17 lakes and streams in the contiguous United States to explore how abiotic and biotic factors influence fish species richness and trait distributions of body size. We calculated key abiotic (climate, productivity, land use) and biotic (phylogenetic diversity, trait diversity, community‐level overlap of trait probability densities) variables for each site to test hypotheses about drivers of ITV in body size and fish diversity.Abiotic variables were consistently important in explaining variation in fish body size and species richness across sites. In particular, productivity (as chlorophyll) was a key variable in explaining variation in body size trait richness, evenness and divergence, as well as species richness.This study yields new insights into continental‐scale patterns of freshwater fishes, possible only by leveraging the paired high frequency, in situ abiotic data and individual‐level traits collected by NEON. 

Abstract Chlainomonas(Chlamydomonadales, Chlorophyta) is one of the four genera of snow algae known to produce annual pink or red blooms in alpine snow. NoChlainomonasspecies have been successfully cultured in the laboratory, but diverse cell types have been observed from many field‐collected samples, from multiple species. The diversity of morphologies suggests these algae have complex life cycles with changes in ploidy. Over 7 years (2017–2023), we observed seasonal blooms dominated by aChlainomonasspecies from late spring through the summer months on a snow‐on‐lake habitat in an alpine basin in the North Cascade Mountains of Washington, USA. The Bagley LakeChlainomonasis distinct from previously reported species based on morphology and sequence data. We observed a similar collection of cell types observed in otherChlainomonasspecies, with the addition of swarming biflagellate cells that emerged from sporangia. We present a life cycle hypothesis for this species that links cell morphologies observed in the field to seasonally available habitat. The progression of cell types suggests cells are undergoing both meiosis and fertilization in the life cycle. Since the life cycle is the most fundamental biological feature of an organism, with direct consequences for evolutionary processes, it is critical to understand how snow algal life cycles will influence their responses to changes in their habitat driven by climate warming. For microbial taxa that live in extreme environments and are difficult to culture, temporal field studies, such as we report here, may be key to creating testable hypotheses for life cycles. 

Abstract Suzuki−Miyaura cross‐coupling reactions are used to modify the tyrosine residues onBombyx morisilkworm silk proteins using a water‐soluble palladium catalyst. First, model reactions using tyrosine derivatives are screened to determine optimal reaction conditions. For these reactions, a variety of aryl boronic acids, solvents, buffers, and temperature ranges are explored. Qualitative information on the reaction progress is collected via high‐performance liquid chromatography (HPLC), mass spectrometry (MS), and nuclear magnetic resonance (NMR). Optimized reactions are then applied to silk proteins. It is demonstrated the ability to modify silk fibroin in solution by first iodinating the tyrosine residues on the protein, and then carrying out Suzuki‐Miyaura reactions with a variety of boronic acid derivatives. Modification of silk is confirmed with NMR, ion‐exchange chromatography (IEC), UV‐vis, and infrared spectroscopy (IR).