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Dumbbell- and bola-shaped amphiphiles are commonly expected to self-assemble into vesicles with condensed hydrophobic domains due to the dominant hydrophobic interaction. In this work, we examined the assemblies of the dumbbell-shaped AC60-AC60 amphiphile, with two carboxylic acid-functionalized fullerenes (AC60) polar head groups linked by an organic tether, and found that they assemble into hollow, spherical blackberry-type structures with porous surfaces, judged by their smaller assemblies in organic solvents with higher polarity and in aqueous solutions with high pH. We attribute the formation of blackberry structures to the organic tether that may be too short to fill up a condensed hydrophobic domain, as confirmed by all-atom simulations. This is further proved by noticing that several bola-type macromolecules with hydrophilic polyethylene glycol (PEG) chain being the linker and no hydrophobic components, AC60-PEG-AC60, can also self-assemble into hollow, spherical assemblies and demonstrate similar pH response as the assemblies from AC60-AC60 dumbbells. Therefore, we conclude that the driving force of the self-assembly for these dumbbell- or bola-shaped molecules is counterion-mediated attraction from the two AC60 head groups rather than the hydrophobic interaction due to the organic linkers. The so-formed blackberry structures here, as well-studied before in other systems, possess porous surfaces, making these charged amphiphiles a valuable model for designing stable nanocontainers with controllable porosity to the change of environment. 

La Niña climate anomalies have historically been associated with substantial reductions in the atmospheric CO₂growth rate. However, the 2021 La Niña exhibited a unique near-neutral impact on the CO₂growth rate. In this study, we investigate the underlying mechanisms by using an ensemble of net CO₂fluxes constrained by CO₂observations from the Orbiting Carbon Observatory-2 in conjunction with estimates of gross primary production and fire carbon emissions. Our analysis reveals that the close-to-normal atmospheric CO₂growth rate in 2021 was the result of the compensation between increased net carbon uptake over the tropics and reduced net carbon uptake over the Northern Hemisphere mid-latitudes. Specifically, we identify that the extreme drought and warm anomalies in Europe and Asia reduced the net carbon uptake and offset 72% of the increased net carbon uptake over the tropics in 2021. This study contributes to our broader understanding of how regional processes can shape the trajectory of atmospheric CO₂concentration under climate change.

 

Geostationary satellite reveals the asymmetrical impact of heatwaves on plant diurnal photosynthesis at the continental scale. 

The timing and progression of the spring thaw transition in high northern latitudes (HNL) coincides with warmer temperatures and landscape thawing, promoting increased soil moisture and growing season onset of gross primary productivity (GPP), heterotrophic respiration (HR), and evapotranspiration (ET). However, the relative order and spatial pattern of these events is uncertain due to vast size and remoteness of the HNL. We utilized satellite environmental data records (EDRs) derived from complementary passive microwave and optical sensors to assess the progression of spring transition events across Alaska and Northern Canada from 2016 to 2020. Selected EDRs included land surface and soil freeze‐thaw status, solar‐induced chlorophyll fluorescence (SIF) signifying canopy photosynthesis, root zone soil moisture (RZSM), and GPP, HR, and ET as indicators of ecosystem carbon and water‐energy fluxes. The EDR spring transition maps showed thawing as a precursor to rising RZSM and growing season onset. Thaw timing was closely associated with ecosystem activation from winter dormancy, including seasonal increases in SIF, GPP, and ET. The HR onset occurred closer to soil thawing and prior to GPP activation, reducing spring carbon (CO₂) sink potential. The mean duration of the spring transition spanned ∼6 ± 1.5 weeks between initial and final onset events. Spring thaw timing and maximum RZSM were closely related to active layer thickness in HNL permafrost zones, with deeper active layers showing generally earlier thawing and greater RZSM. Our results confirm the utility of combined satellite EDRs for regional monitoring and better understanding of the complexity of the spring transition.

 

Abstract Historically, humans have cleared many forests for agriculture. While this substantially reduced ecosystem carbon storage, the impacts of these land cover changes on terrestrial gross primary productivity (GPP) have not been adequately resolved yet. Here, we combine high-resolution datasets of satellite-derived GPP and environmental predictor variables to estimate the potential GPP of forests, grasslands, and croplands around the globe. With a mean GPP of 2.0 kg C m −2  yr −1 forests represent the most productive land cover on two thirds of the total area suitable for any of these land cover types, while grasslands and croplands on average reach 1.5 and 1.8 kg C m −2  yr −1 , respectively. Combining our potential GPP maps with a historical land-use reconstruction indicates a 4.4% reduction in global GPP from agricultural expansion. This land-use-induced GPP reduction is amplified in some future scenarios as a result of ongoing deforestation (e.g., the large-scale bioenergy scenario SSP4-3.4) but partly reversed in other scenarios (e.g., the sustainability scenario SSP1-1.9) due to agricultural abandonment. Comparing our results to simulations from state-of-the-art Earth System Models, we find that all investigated models deviate substantially from our estimates and from each other. Our maps could be used as a benchmark to reduce this inconsistency, thereby improving projections of land-based climate mitigation potentials.