Search Results (11,845)

The problem of agricultural environmental pollution is increasingly serious, and carbon emissions have become an important form of pollution that must be controlled. This study aims to explore the impact mechanism and heterogeneity of the digital economy on China’s agricultural carbon emission intensity. Based on the panel data of 30 provinces in China from 2012 to 2022, an empirical analysis was conducted using two-way fixed effect models, moderating effect models, and panel threshold models, revealing that the development of the digital economy is significantly and negatively associated with agricultural carbon emission intensity. However, the emission reduction effect is restricted by a complex moderation and threshold framework. Specifically, the improvement of human capital may lead to a decreasing trend in the emission reduction effect of the digital economy, implying the existence of a potential “efficiency rebound” effect. The regional innovation environment can significantly enhance the emission reduction effect of the digital economy, and this effect is most significant when there is both high human capital and a superior innovation environment. In addition, the emission reduction effect of the digital economy exhibits threshold characteristics and is optimal when agricultural technology progress reaches an intermediate level; an institutional environment can play an effective role at the intermediate level, but its independent emission reduction effect tends to be saturated under a highly perfect institutional environment. These findings provide new evidence for understanding the complex relationship between the digital economy and agricultural carbon emissions and provide a theoretical basis and practical guidance for the formulation of differentiated agricultural low-carbon development policies. Full article

Carbon dioxide injection is one of the most advanced and commercially proven methods of enhanced hydrocarbon recovery, and CO₂ injection has been shown to be very effective in conventional oil reservoirs and is gaining attention in gas, unconventional, and coalbed methane reservoirs. The advantages of CO₂ injection lie in the favorable phase properties and interactions with reservoir fluids, such as swelling, reduction in oil viscosity, reduction in interfacial tension, and miscible displacement in favorable cases. But the low viscosity and density of CO₂ compared to the reservoir fluids result in unfavorable mobility ratios and gravity override, resulting in sweep efficiency limitations. This review offers a broad and EOR-centric evaluation of the various CO₂ injection methods for a broad array of reservoir types, such as depleted oil reservoirs, gas reservoirs for the purpose of gas recovery, tight gas/sands, as well as coalbed methane reservoirs. Particular attention will be given to the use of mobility control/sweep enhancement techniques such as water alternating gas (CO₂-WAG), foam-assisted CO₂ injection, polymer-assisted WAG processes, as well as hybrid processes that combine the use of CO₂ injection with low salinity or engineered waterflood. Further, recent developments in compositional simulation, fracture-resolving simulation, hysteresis modeling, and data-driven optimization techniques have been highlighted. Operational challenges such as injectivity reduction, asphaltene precipitation, corrosion, and conformance problems have been reviewed, along with the existing methods to mitigate such issues. Finally, key gaps in the current studies have been identified, with an emphasis on the development of EHR processes using CO₂ in complex and low-permeability reservoirs, enhancing the resistance of chemical and foam methods in realistic conditions, and the development of reliable methods for optimizing the process on the field scale. This review article will act as an aid in the technical development process for the implementation of CO₂ injection projects for the recovery of hydrocarbons. Full article

Despite the economic relevance of climate-transition risk, firm-level carbon exposure often fails to appear as a robustly priced factor when ESG measures and sustainability shocks are conflated. This study examines whether carbon exposure is conditionally priced in European equity returns using a strongly balanced quarterly panel of 238 firms from the MSCI Europe ESG Leaders universe (2018–2024). Total greenhouse gas emissions act as a proxy for carbon exposure, mapped to within-year percentiles and standardized by sector-year. Regressions control for ESG scores and controversies and include firm and quarter fixed effects with firm-clustered, dependence-robust standard errors. The linear carbon coefficient is small and statistically indistinguishable from zero, indicating no stable return premium from within-firm changes in carbon exposure. Functional-form tests reject linearity: quadratic and quintile specifications reveal curvature and a non-monotonic pattern, with return differences concentrated in the middle of the carbon distribution. Conditioning on macro-financial stress, measured by the ECB Composite Indicator of Systemic Stress, yields limited evidence of a uniform carbon penalty. However, high-controversy states are associated with lower returns, while ESG scores show negative associations under dependence-robust inference. Overall, carbon-related pricing appears to be nonlinear and state-dependent, whereas controversy risk is the most robust sustainability predictor of returns. Full article

Carbon fiber-reinforced resin matrix composites (CFRC) are extensively used in aerospace, automotive manufacturing, and sports equipment. However, the brittle nature of the resin matrix causes CFRC to exhibit severe vibrations and noise under dry friction conditions. Enhancing the intrinsic damping properties of the resin matrix serves as a fundamental and effective strategy to mitigate vibration and noise radiation in composite components. This study systematically investigates high-temperature co-curing damping composites using co-curing technology, aiming to improve the mechanical performance and damping characteristics of traditional fiber-reinforced epoxy resin composites. A novel carbon fiber-reinforced terminal carboxyl nitrile epoxy pre-polymer composite material demonstrates both stable chemical properties and excellent high-temperature resistance. Through formulation adjustments, the curing temperature and time of epoxy resin are matched with those of the terminal carboxyl nitrile epoxy pre-polymer. The performance of epoxy carbon fiber composites was evaluated through tensile tests, flexural tests, impact tests, infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, scanning electron microscopy, and X-ray diffraction. Results show that blending epoxy resin with terminal carboxyl nitrile liquid rubber enhances energy dissipation by increasing intermolecular friction and hydrogen bonding interactions. The damping ratio of epoxy resin-based carbon fiber composites reaches as high as 1.67%. Tensile strength, flexural strength, and impact strength reach 1968 MPa, 1343 MPa, and 127 kJ/m², respectively. The addition of terminal carboxylated nitrile liquid rubber facilitates the formation of continuous friction membranes, enhancing friction stability. Tensile tests demonstrate that carbon fiber composites containing 25% terminal carboxylated nitrile liquid rubber outperforms other formulations. As evidenced by impact tests, the performance of the prepared composites is superior to that of other configurations. Dynamic mechanical analysis indicates that the 25% rubber-containing composites exhibit enhanced damping characteristics and higher loss modulus. Experimental results confirm that this study advances the development of functional composites for vibration reduction and noise control applications. Full article

Urban wetlands on the Qinghai–Tibetan Plateau are increasingly recognized as potentially important components of city-scale carbon budgets; however, their CO₂ flux dynamics and associated environmental drivers remain insufficiently quantified, particularly under high-altitude urban conditions. In this study, we addressed this knowledge gap by conducting continuous eddy covariance observations at Haihu Wetland Park in Xining City, China. Carbon fluxes were monitored throughout 2023 using the Huangshui Park Station flux tower. We quantified the temporal dynamics of gross primary productivity (GPP), ecosystem respiration (Re), and net ecosystem exchange (NEE), and systematically assessed their responses to key environmental drivers across multiple temporal scales. GPP and Re exhibited unimodal seasonal patterns, with substantially higher values during the growing season. NEE showed pronounced diel cycling, with nighttime CO₂ release and daytime uptake, and shifted seasonally between net source and net sink states. At the daily scale (n = 365), Pearson correlations showed that air temperature (T_a), 5 cm soil temperature (T_s5) and volumetric soil water content (SWC) exhibited the strongest associations with the flux components, whereas photosynthetic photon flux density (PPFD) showed moderate associations and precipitation was weak. At the monthly scale (n = 12), Mantel tests further highlighted a dominant thermal control on GPP and Re (T_a and T_s5), whereas precipitation showed additional associations with Re and NEE. Overall, the ecosystem acted as a net CO₂ sink in 2023 (annual NEE = −292.25 g C m⁻² yr⁻¹ under our sign convention), with uptake concentrated in the first eight months of the year. Under the combined effects of multiple environmental factors, plateau urban wetlands functioned as a strong carbon sink, and the results of this study provide a data basis for improving the accuracy of carbon budget estimates for this type of ecosystem. Full article

Subsoil (30–100 cm) soil organic carbon (SOC) is a poorly constrained but potentially significant component of terrestrial carbon budgets. While controls on subsoil SOC are likely to differ from those affecting topsoil, few studies have quantified them. This study quantified subsoil (30–100 cm) SOC stocks and identified the controls on its spatial distribution across perennial grazing systems in northeast New South Wales, Australia. SOC was measured to 1 m depth across 54 long-term perennial pasture grazing paddocks on nine farms. A Random Forest regression model was then used to determine the relationship between subsoil SOC and drivers represented by the scorpan model of soil formation. Subsoil SOC contributed ~50% of total SOC stocks in the top metre of soil, with a median of 65.8 t ha⁻¹ stored in subsoil. Our study found that drivers of SOC input and turnover (subsoil total nitrogen, 10–30 cm SOC content, and climate), as well as pedogenic processes influencing SOC stabilisation (weathering index), were the most important factors in the determination of subsoil SOC content. This contrasts with previous findings where abiotic factors linked to parent material and soil properties were the major controls on subsoil SOC distribution and highlights links between both input and stabilisation in perennial grazing systems. Full article

Biochar activation is critical for producing high-performance adsorbents; however, conventional activation methods are energy-intensive and difficult to control, particularly when air is used as an activating agent. This study investigates CO₂–air co-activation in a laboratory-scale fluidized bed reactor as an energy-efficient alternative. Experiments were conducted at 750–850 °C under varying gas flow rates with a constant CO₂/O₂ ratio. Optimal properties were achieved at 800 °C and 0.2–0.3 L/min CO₂, yielding a maximum BET surface area of 479 m²/g, a micropore contribution of 42%, and controlled carbon conversion (~25–35% yield). Aspen Plus equilibrium simulations also confirm that CO₂-only activation remains endothermic (heat duty up to +0.07 kW), air-only activation becomes strongly exothermic (down to −0.13 kW), while the CO₂–air mixture exhibits near-thermoneutral to mildly exothermic behavior (+0.13 to −0.10 kW), thereby reducing external energy demand potentially by approximately 60–70% compared with CO₂-only activation and significantly improving process stability. These results demonstrate that CO₂–air co-activation offers a practical route to produce high-quality activated biochar with controlled porosity and improved energy efficiency. Full article

Against the backdrop of global climate change, climate warming and increasing nitrogen deposition are profoundly altering carbon (C) and nitrogen (N) cycling in terrestrial ecosystems. Short-term observations are critical for capturing the initial response trajectories of soil C-N dynamics to environmental stress, providing timely insights into early-stage adaptation mechanisms that underpin long-term ecosystem stability. This study investigated the interactive effects of these drivers on soil C and N transformation rates, component dynamics, and their coupling relationships in a warm steppe and a warm shrub grassland within the forest–steppe ecotone of northwestern Liaoning Province. We employed field-controlled experiments using open-top chambers for warming in combination with four nitrogen addition gradients. Results showed warming plus high N addition increased soil total N but reduced net N mineralization, supporting the “N saturation hypothesis”. Though N addition generally suppressed the C conversion rate, low-level N (5 g N m⁻² a⁻¹) mitigated C loss and enhanced it under warming. Soil organic C and microbial biomass C drove C transformation. Warm shrub grassland’s stable mineral-associated organic C pool rose 640.5% (stronger resilience), while warm steppe’s C/N turnover depended on seasons (greater vulnerability); C/N transformations were synchronized in the steppe but independent in shrubland. Full article

A breakthrough has been achieved in shale gas exploration of the Lower Carboniferous Shale in the Yaziluo Rift Trough, Dianqiangui Basin, with Well SY-1 yielding a daily gas production of 1.1 × 10⁴ m³. To clarify the main controls and evolutionary patterns of shale pore structure, shale samples from different sedimentary environments were analyzed using TOC content, X-ray diffraction (XRD), low-pressure gas adsorption (CO₂ and N₂), and field emission-scanning electron microscopy (FE-SEM). The results show that shale from the basin sedimentary environment (BSE) exhibits the highest TOC, is dominated by siliceous minerals (quartz + feldspar), and contains minor carbonate minerals (calcite + dolomite). Shale from the upper slope sedimentary environment (USSE) has the lowest TOC and is rich in carbonate minerals. The lower slope sedimentary environment (LSSE) shows intermediate compositions. From BSE to USSE, pore volume and specific surface area decrease, while fracture development increases. A quantitative model for volumes of organic pores, clay mineral-associated pores, and brittle mineral-associated pores was established. Organic pores dominate in BSE shale (65.42%), followed by clay mineral-associated and brittle mineral-associated pores, while inorganic pores dominate in USSE shale (63%). Pore structure in BSE and LSSE is primarily controlled by TOC content, with pore volume and surface area increasing with TOC content, while mesopore development is influenced by organic matter type and mineral compositions. In USSE, pore structure is mainly governed by inorganic minerals, with clay minerals promoting pore volume and surface area development, whereas brittle minerals facilitate the preservation of macropores. Evolutionary models of pore development were established for these distinct sedimentary environments. Full article

This study presents the electrochemical characterization of a novel, binder-free, plasma-treated aluminum/carbon electrode (“Surge”) using lithium metal half-cells. The low operating potential near 0 V vs. Li/Li${}^{+}$ enables the investigation of the electrode’s charge storage mechanisms and stability limits. We compare its electrochemical behavior in coin cells (CR2032) against two reference configurations: (i) the Surge electrode with a thin copper backer (Surge + Cu-backer) and (ii) a commercial graphite electrode on an aluminum current collector (C-REF). The Surge electrode demonstrated ultra-high initial specific capacities of up to approximately 4500 mAh/g (cycle 1) with Coulombic efficiencies exceeding 85% after the formation cycle. The observed capacity significantly exceeds the theoretical value for Li-Al alloying (993 mAh/g), indicating that lithium plating within the porous carbon scaffold contributes substantially to the total charge storage. However, this high performance was limited to approximately 8 to 9 stable cycles. Post-cycling analysis via scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDX) revealed a dominant failure mechanism: partial dissolution and consumption of the Al current collector leading to material redistribution. Quantitative EDX analysis showed a decrease in Al content from 45 at.% to 12 at.% alongside an increase in oxygen content from 8 at.% to 38 at.%, suggesting extensive Al-oxide formation. Critically, in the absence of a backer, Al-containing material deposited onto the stainless-steel cell components. The Cu backer served to redirect these deposits, improving current collection and modestly extending the short-term durability to approximately 1800 mAh/g at cycle 14 (approximately 75% capacity retention). In contrast, the C-REF control cell reached only approximately 1000 mAh/g (cycle 4) before failing within 5 to 6 cycles, underscoring the inherent instability of bare Al at low potentials. This characterization study establishes the Surge architecture as a successful proof-of-concept for ultra-high capacity charge storage and identifies Al dissolution as the dominant degradation mechanism. Future optimization must focus on stabilizing the Al substrate through protective interphases, alloying, or electrolyte engineering. Full article

In modern aerospace cockpits, the display and control console (DCC) serves as a critical human–machine interface. Light weight is particularly important in this industry, especially for key equipment such as the DCC. To address the excessive weight of aluminum alloy DCCs while achieving desirable mechanical properties and vibration-damping performance, this study developed a Carbon Fiber Reinforced Polymer (CFRP) DCC; its superior performance was verified through finite element analysis (FEA) and a vibration test. Compared with conventional aluminum alloy structures, the newly designed DCC achieves approximately a 40% weight reduction while meeting all rigidity, strength, and vibration requirements. This study successfully demonstrates the feasibility of using CFRP to replace aluminum alloy in aircraft DCC and provides a systematic design methodology for similar structures. Full article

This study investigates the deposition of amorphous silicon carbon nitride (a-SiCN) films using a microwave sheath–voltage combination plasma (MVP) source under duty-cycle-controlled deposition conditions. Duty ratios of 10, 30, 50, and 70% resulted in substrate temperatures of 180, 600, 980, and 1040 °C, respectively. The deposition rate reached a maximum of approximately 208 μm/h at a duty ratio of 30%. The atomic ratios of C, N, and Si remained nearly constant for duty ratios from 30% to 70%. X-ray diffraction confirmed that all films were amorphous. Raman spectra revealed features characteristic of amorphous carbon (a-C) for duty ratios of 30% or higher, suggesting the incorporation of a-C-like structures into the a-SiCN matrix. The film hardness increased as the duty-cycle-controlled deposition conditions shifted from 10% to 50% (180 to 980 °C), reaching a maximum of 22.65 ± 6.78 GPa at a duty ratio of 50%, and then decreased at 70% (1040 °C). These variations in hardness are suggested to be associated with coupled changes in hydrogen incorporation, C–N bonding, and the evolution of sp²-rich carbon clustering (graphite-like short-range ordering) under elevated temperature and ion-bombardment conditions. Full article

The growing demand for carbon-based energy materials requires sustainable alternatives to fossil fuels. This study explored the production and characterization of char obtained from refuse-derived fuel (RDF) and biomass blended pellets in varying proportions (0%, 15%, 25%, 50%, and 100% RDF). The objective was to evaluate their potential as high-energy-density solid fuels while addressing operational challenges related to ash behavior. Chars were produced at 400 °C for one hour in a muffle furnace in closed crucibles. A set of analytical techniques (calorimetry, infrared spectroscopy, thermogravimetry, inductively coupled plasma, and X-ray fluorescence) was employed to assess physicochemical properties. RDF content strongly affected mass yield, energy yield, and thermochemical behavior. Among the tested formulations, char with 50 and 25% of RDF (C_RDF50:BW50 and C_RDF25:BW75) ignited at lower temperatures (≈150 °C) and showed high flammability (C) values (1.97–2.03 × 10⁻⁵), indicating greater flammability. They also reached higher combustion temperatures (716–746 °C), suggesting improved thermal stability during the final combustion stage. Both chars presented increased high heating values (18–19 MJ/kg, dry basis) and a few surface functional groups. This supports a lower devolatilization rate, meaning that although ignition is easy, combustion remains stable and controllable. All chars showed very high acid–base indices, indicating a strong tendency for ash melting. However, low slag viscosity and alkalinity values suggest viscous, poorly mobile slag, reducing adhesion and buildup on reactor surfaces. This study combines thermogravimetric combustion analysis with ash chemistry–based slagging and fouling indices to provide an integrated assessment of the operational behavior of RDF–biomass-derived char fuels. The results highlight the technical feasibility of chars produced from RDF and biomass blended pellets, whose thermal properties make them promising candidates for use as solid fuels. Full article

With the advancement of smart education and carbon neutrality goals, optimizing Indoor Environmental Quality (IEQ) while minimizing energy consumption is critical. Traditional PID or rule-based strategies struggle with the strong non-linearity and time delays of photothermal coupling in high-density classrooms. This paper proposes an adaptive closed-loop control framework fusing Digital Twin (DT) and Deep Reinforcement Learning (DRL). A high-fidelity multi-physics model is constructed as a virtual testbed, utilizing the Proximal Policy Optimization (PPO) algorithm to learn multi-objective strategies. The trained agent is deployed to an edge gateway for real-time inference. Experimental results from a field study distinguish this work from pure simulations. Results demonstrate that compared to PID baselines, the proposed strategy reduces energy consumption by 28.4% while maintaining thermal comfort (PMV) and visual comfort compliance. Furthermore, the variance of PMV is reduced by 66.7%, and system recovery time under stochastic disturbances is shortened by 31.4%. Full article

The valorization of agro-industrial residues through fermentation processes represents a sustainable approach to producing high-value bioproducts, such as microbial organic acids and fermentation-derived anti-browning agents, including kojic acid and kojic acid-rich fermented extracts. In this study, melon waste (non-commercial-quality or damaged fruit) was evaluated as an alternative carbon source (whole fruit) for kojic acid (KA) production by Aspergillus oryzae (ATCC 10124) under submerged fermentation. The effects of process variables such as pH, temperature, and nitrogen and carbon availability on KA synthesis were analyzed, and biomass growth and product formation were described using logistic and Luedeking–Piret kinetic models. Under optimal conditions (pH 5.5, 36 °C, 2.5 g/L melon dry matter, 2.5 g/L yeast extract, 100 rpm), KA production reached 1.64 g/L at a final time of 120 h. Kinetic analysis showed moderate fungal growth (μ_max = 0.058 h⁻¹; X_max = 0.81 g/L), with KA formation following a mixed growth-associated pattern as described by the Luedeking–Piret model (α = 1.26 g KA/g X; β = 0.024 h⁻¹), indicating sustained production during the stationary phase. The KA-rich fermented extract was subsequently applied as an anti-browning treatment on spineless prickly pear (Opuntia ficus-indica) cladodes. Short immersion times (0.5–1.0 min) in a 2 g/L KA solution significantly preserved luminosity (L*) and limited total color change (ΔE ≤ 5) during 4 days of storage at 28 °C, compared with water-treated controls, which exhibited accelerated darkening (ΔE ≈ 9–15). Prolonged immersion times induced tissue damage and color deterioration, indicating an optimal exposure window. These results demonstrate the feasibility of valorizing melon waste to obtain a KA-rich extract and support its potential application as a natural anti-browning agent in fresh-cut vegetables within a circular agrifood framework. Full article