252 Search Results

Target of rapamycin (TOR) and sucrose non-fermenting 1–related protein kinase 1 (SnRK1) are conserved regulators of plant growth and metabolism and are often portrayed as functionally antagonistic under nutrient limitation. However, how this relationship operates across different nutrient contexts remains poorly defined. Here, we generated an Arabidopsis dual-reporter line that enables simultaneous monitoring of TOR and SnRK1 activities and profiled their dynamics under carbon and nitrogen perturbations. We found that TOR and SnRK1 activities\r\noverall exhibit a negative relationship during the transition from carbon starvation to carbon abundance; however, their temporal dynamics during that transition do not support a strictly inversemore » correlation. Under dark conditions, TOR activity is gradually repressed, while SnRK1 is initially repressed in the early hours and subsequently activated during extended darkness. During nitrogen starvation, TOR activity is progressively repressed, whereas SnRK1 is activated during early hours and then becomes repressed. In vitro, recombinant SnRK1a1 directly\r\ninhibits the activity of immunoprecipitated TOR (IP-TOR), whereas IP-TOR does not directly affect SnRK1a1 activity. Together, these results support a nutrient dependent model in which TOR and SnRK1 are coordinated primarily by cellular metabolic status.\r\n« less

Nitrous oxide (N₂O) is a potent and persistent greenhouse gas, with rising atmospheric concentrations driven in part by inefficient use of synthetic nitrogen (N) fertilizers in agriculture. Predicting soil N₂O emissions is challenging due to high spatial and temporal variability arising from complex soil biogeochemical processes. Process-based ecosystem models and standalone machine learning (ML) approaches without extensive site-specific calibration often miss high-emission episodes. Here, we show how an Ensemble Modeling System (EMS) based on outputs from an ensemble of ecosystem models coupled to an ensemble of ML models can improve predictions and understanding of N₂O fluxes from US cropland. Trainedmore » and validated on ~12,000 N₂O chamber measurements at 17 US Midwest sites (six crops, 35 management practices), the EMS accurately predicted daily fluxes of N₂O at both training (R² = 0.84, RMSE = 16.4 g N ha⁻¹ d⁻¹) and held-out testing sites (R² = 0.84, RMSE = 6.2 g N ha⁻¹ d⁻¹). Analyses identified six dominant N₂O drivers: soil organic carbon (SOC), NH₄⁺, NO₃^-, water-filled pore space, temperature, and aboveground biomass production. Wet, warm soils produced large N₂O peaks only with sufficient SOC and mineral N; in low-SOC soils, fluxes remained low. Incorporating these drivers into process-based models might significantly improve their predictive capacity. The EMS demonstrates a strong potential to predict N₂O fluxes at unseen sites, enabling more reliable regional inventories, improved gap-filling where measurements are sparse, and enhanced understanding of mechanisms to advance targeted mitigation strategies in food, feed, and bioenergy crops.« less

Polysulfides are poorly retained within porous cathodes and readily diffuse into the electrolyte over time, leading to the well-known shuttle effect that undermines the reversibility of Li-S batteries. Here, in this study, we demonstrate that catalytic disproportionation of polysulfides provides an effective pathway to suppress this process by rapidly converting dissolved species into solid sulfur and sulfides, thereby preventing their migration into the electrolyte. Fundamentally, the sluggish kinetics of sulfur redox reactions are responsible for the accumulation and redistribution of soluble polysulfides in the bulk electrolyte. By accelerating these kinetics, catalyzed disproportionation not only confines sulfur within the conductive cathodemore » matrix but also promotes the homogeneous precipitation of Li₂S₂/Li₂S, which enhances electrochemical reversibility and cycling stability. Using nitrogen-doped carbon (NC800) as a model catalyst, we reveal its ability to drive a pseudo-16-electron reduction pathway, leading to a single dominant Li₂S product and uniform deposition within the porous framework. In contrast, a non-catalytic carbon (KB) yields multiple polysulfide intermediates and heterogeneous deposition. The mechanistic insights provided here highlight the pivotal role of catalytic disproportionation in reshaping sulfur redox pathways and offer a rational strategy for mitigating polysulfide shuttling in practical Li-S pouch cells.« less

Soil carbon plays a crucial role in the global carbon cycle. Changes in land use can determine whether carbon is stored or is emitted into the atmosphere as carbon dioxide, which has broad implications for the human and Earth systems. These feedbacks to the carbon cycle and their socio-economic drivers are modelled by many global multisector dynamics models to project future possibilities for the human-Earth system. One notable model of this class is the Global Change Analysis Model (GCAM), which uses a simplified process to model soil organic carbon (SOC) content after land-use transition across 384 land units. While themore » current GCAM soil carbon framework is based on scientific principles, it has not been tested against experimental data. This work examines rates of SOC change from GCAM input data. Specifically, first order rate constants derived from model inputs were compared to values from two syntheses to assess GCAM’s accuracy. Welch’s t-tests and linear models were used to determine if rate constants were consistent across all tested geographical areas and land-use transition types. While we found that there was general agreement on the direction and magnitude (i.e., rate) of SOC change, the rate constant derived from GCAM and empirical values differed strongly in a subset of specific instances. These results indicate that GCAM’s current SOC dynamics during land use transition successfully capture broad patterns of change in this critical carbon pool, but should be interpreted with caution at finer spatial scales. One potential cause of these discrepancies is our highly aggregated variable, soil timescale, which could be made more granular to improve accuracy. When using economically rooted multisector dynamics models, such as GCAM, it is critical to understand such model limitations for representing specific Earth system processes.« less

This study investigates secondary electron emission (SEE) characteristics of reticulated foams using direct measurements and analytical modeling. Total SEE was quantified, revealing suppression of up to 44% in carbon foam structures compared to planar graphite surfaces. An optimal geometric configuration was identified and supported by analytical models. SEE angular dependence experiments showed diverse behaviors: fiber-like behavior and directional dependence for pore and ligaments on the mm scale, with fuzz-like characteristics when the foam features are between 10–100 µm. Electron energy analyzer measurements showed that carbon foams preferentially suppress inelastic backscattered electrons (BSEs) more so than true secondary electrons (SEs). Themore » analysis indicated a larger fraction of low-energy SE generation in foams compared to flat surfaces due to increased emission from curved fiber ligaments and tertiary SEs from high-energy BSEs. These findings have implications for design and optimization of materials with tailored electron emission properties for applications like plasma-facing components, spacecraft materials, and accelerator surfaces.« less

The stable carbon isotope signature (δ¹³C) of methane (CH₄) is used to discriminate between biological, thermogenic, and abiotic sources. Methanogens, or methane producing archaea, inhabit a broad range of chemical conditions. Many of these environments are replete in dissolved inorganic carbon (DIC), causing isotopically depleted δ¹³C biogenic CH₄. However, some extreme environments inhabited by methanogens, such as serpentinising systems, exhibit low carbon dioxide (CO₂) availability, replete H₂, and isotopically enriched δ¹³C CH₄ that is outside the known biogenic range. We measured the δ¹³C of CO₂, biomass, lipids, and CH₄ during hydrogenotrophic methanogenesis under hydrogen replete conditions with a limited carbonmore » pool to investigate carbon isotope dynamics at complete DIC consumption. As theory predicts, we found that the final, accumulated methane δ¹³C values closely reflect the δ¹³C of the initial DIC supply, and that methane is more ¹³C enriched than biomass and lipids. This provides the first experimental evidence that methanogens can achieve complete carbon consumption and thus can produce accumulated CH₄ products that isotopically reflect the initial CO₂. These data show that the range of possible δ¹³C values from biogenic methane needs to be expanded for natural environments impacted by extreme carbon limitation.« less

Oxygen-terminated diamond has a wide breadth of applications, which include stabilizing near-surface color centers, semiconductor devices, and biological sensors. Despite the vast literature on characterizing functionalization groups on diamond, the chemical composition of the shallowest portion of the surface (<1 nm) is challenging to probe with conventional techniques like XPS and FTIR. In this work, we demonstrate the use of angleresolved XPS to probe the first ten nanometers of both oxygen and hydrogen terminated (100) single-crystalline diamond grown via chemical vapor deposition (CVD). With the use of consistent peakfitting methods, the peak identities and relative peak binding energies were identifiedmore » for sp² carbon, ether, hydroxyl, carbonyl, and C−H groups for both of these diamond surface terminations. For the oxygen-terminated sample, we also quantified the thickness of the sp² carbon layer situated on top of the bulk sp³ diamond bonded carbon to be 0.3 ± 0.1 nm, based on the analysis of the Auger electron spectra and D-parameter calculations. These results indicate that the majority of the oxygen is bonded to the sp² carbon layer on the diamond, and not directly to the sp³ diamond bonded carbon.« less

Quantifying the carbon (C) uptake of Miscanthus × giganteus (M × g) in both aboveground and belowground structures (e.g., net primary productivity (NPP)) and differences among methodological approaches is crucial. Our objectives were to directly measure Mxg NPP and evaluate the effects of nitrogen application, location, and belowground biomass sampling methods. We hypothesize that increased nitrogen application increases the overall NPP of M × g and that quantifying rhizome biomass using excavations will produce the lowest variability between replicates. We collected biomass from mature M × g stands from three locations in Iowa with three nitrogen application rates and onemore » site in Illinois. We destructively sampled at two time points, when rhizome mass is anticipated to be at a minimum (initial) and anticipated to be at its maximum (peak). Biomass was collected from1×1m quadrats in which one in-clump and one beside-clump cores were collected and then excavated to 30 cm depth to extract all rhizomes. We found that aboveground M × g NPP ranged from 15.4 Mg Da ha^–1 year^–1 to 36.4 Mg Da ha^–1 year^–1 and belowground M × g NPP ranged from 4.4 Mg Da ha^–1 year–1 to 19.6 Mg Da ha^–1 year–1. M × g NPP varied across sites, fertilization, and calculation assumptions. Aboveground NPP (yield) was on average 68.7% of the total NPP. Root-to-shoot ratios at peak biomass decreased with nitrogen application rate, from an average of 1.9 for 0 N plots to 0.89 for 224 N fertilized plots. There was more variation in core data than from excavations; however, when in-clump and beside-clump cores were averaged together, core and excavation averages were not different. Overall, these results show that the range of mature M × g NPP is driven by aboveground productivity, influenced by nitrogen application and site. Our results provide useful data to constrain agro-ecosystem models and provide crucial insights for future perennial belowground sampling.« less

This study presents numerical investigations of the trapping characteristics of fold-and-thrust belt structures, defining three carbon capture and storage (CCS) play types that could be used to store commercial volumes (millions of tonnes) of CO₂. Specifically, we present simulations of CO₂ storage in three fold-and-thrust belt models comprising a thrust-ramp, duplex, and thrust-fold geometry. To constrain these play types in realistic geology, each model is based on a study site, including a novel investigation of a greenfield saline reservoir in Virginia, USA, being considered for commercial carbon storage and two well-characterized petroleum fields: the Wilburton field in Oklahoma, USA, andmore » the Incahuasi field in Bolivia. Our results provide insight into several key parameters, such as the long-term security of injected CO₂ in these geologies and injection strategies for maximizing storage efficiency while reducing pressure-related risk. These results improve the understanding of CCS in fold-and-thrust belt storage sites globally by describing general storage parameters that may be applied to site-specific projects. We find that thrust-ramp geometries may securely trap CO₂ through solubility and hydrodynamic trapping under suitable reservoir conditions, duplex structures may store some quantities of CO₂ but are pressure-constrained, and that thrust-ramp structures may store large quantities of CO₂ by maximizing fetch volume, which simultaneously lowers geomechanical risk by reducing pressure buildup along zones of weakness.« less

All-solid-state lithium–metal batteries hold great promise because of their high energy density stemming from using an energy-dense lithium–metal anode. However, mitigating the dendritic lithium–metal growth, originating from heterogeneous lithium–metal deposition, is a priority to suppress short-circuit and extend cycle life. This study employs direct current (DC) magnetron sputter coating to deposit tin (Sn) and carbon (C) on a stainless steel (SUS) current collector to achieve uniform lithium–metal plating and improve cycling performance. In particular, we evaluated and compared two dual buffer layer designs, consisting of Sn and C: (1) a thin C layer is deposited on the Sn metal layermore » (SUS/Sn/C), and (2) the Sn metal layer is deposited on the thin C layer (SUS/C/Sn). This study demonstrated that the SUS/Sn/C buffer layer is more effective in suppressing lithium dendrite growth and improving cycling stability than the SUS/C/Sn buffer layer. The SUS/Sn/C buffer layer shows stable Li-plating/stripping cycling over 450 cycles without noticeable short-circuit. Ex situ and in situ characterization confirm the role of the SUS/Sn/C dual buffer layer: (i) the Sn metals result in a uniform lithium–metal deposition on the current collector and (ii) the carbon layer acts as a physical barrier to suppress the lithium dendrite growth toward the solid electrolyte because of its lithiophobic nature.« less