Search Results (1,400)

The dynamic process of water depletion plays a critical role in both surface coalbed methane (CBM) development and underground gas extraction, reshaping water–rock interactions and inducing complex permeability responses. Addressing the limited understanding of the coupling mechanism between heterogeneous pore water evolution and permeability during dynamic processes, this study simulates reservoir transitions across four zones (prospective planning, production preparation, active production, and mining-affected zones) via centrifugal experiments. The results reveal a pronounced scale dependence in pore water distribution. During low-pressure stages (0–0.54 MPa), rapid drainage from fractures and seepage pores leads to a ~12% reduction in total water content. In contrast, high-pressure stages (0.54–3.83 MPa) promote water retention in adsorption pores, with their relative contribution rising to 95.8%, forming a dual-structure of macropore drainage and micropore retention. Multifractal analysis indicates a dual-mode evolution of movable pore space. Under low centrifugal pressure, D₋₁₀ and Δα decrease by approximately 34% and 36%, respectively, reflecting improved connectivity within large-pore networks. At high centrifugal pressure, an ~8% increase in D₀−D₂ suggests that pore-scale heterogeneity in adsorption pores inhibits further seepage. A quantitative coupling model establishes a quadratic relationship between fractal parameters and permeability, illustrating that permeability enhancement results from the combined effects of pore volume expansion and structural homogenization. As water saturation decreases from 1.0 to 0.64, permeability increases by more than 3.5 times. These findings offer theoretical insights into optimizing seepage pathways and improving gas recovery efficiency in dynamically evolving reservoirs. Full article

In this study, a shape-changeable 3D scaffold with photothermal effects was developed to address the clinical challenges of complex bone defects. The multifunctional construct was fabricated via in situ polymerization combined with a gas foaming technique, creating hierarchical porous architectures that mimic the native bone extracellular matrix. By incorporating polydopamine (PDA)-modified amorphous calcium phosphate (CA) into poly(propylene glycol) (PPG)- and poly(ԑ-caprolactone) (PCL)-based polyurethane (PU). The obtained scaffolds achieved osteoinductive potential for bone tissue engineering. The surface PDA modification of CA enabled efficient photothermal shape conversion under near-infrared (NIR) irradiation, facilitating non-invasive remote control of localized hyperthermia. The optimized scaffolds exhibited interconnected porosity (approximately 70%) with osteoconductive pore channels (200–500 μm), resulting in good osteoinduction in cell culture, and precise shape-memory recovery at physiological temperatures (~40 °C) under NIR for minimally invasive delivery. The synergistic effect of osteogenesis promotion and photothermal transition demonstrated this programmable scaffold as a promising solution for integrated minimally invasive bone repair and defect reconstruction. Full article

To address the challenges of low KCl recovery and high collector consumption during flotation at low temperature, a novel approach with utilizing a compound collector consisting of octadecylamine hydrochloride (ODA) and alcohols (butanol, octanol, and dodecanol) to enhance low-temperature KCl flotation recovery was proposed in this study. The flotation performance and underlying mechanisms of this novel amine–alcohol compound collector were investigated through combination of micro-flotation tests, contact angle measurements, and molecular dynamics simulations. The results revealed that KCl flotation recovery decreased with declining temperature using single ODA as the collector, and the maximum KCl flotation recovery was approximately 40% with an ODA concentration of 1 × 10⁻⁵ mol/L at the temperature of 0 °C. Moreover, amine–alcohol compound collector shows different KCl flotation recovery; among them, dodecanol (DOD) presents the best performance at 25 °C with an ODA concentration of 3 × 10⁻⁶ mol/L. The KCl flotation recovery initially increased and then gradually decreased with increasing the DOD concentration, and 90% KCl recovery was achieved with a DOD concentration of 1.5 × 10⁻⁵ mol/L (DOD:ODA = 5:1 in mole) under 25 °C. Furthermore, this compound collector exhibited high selectivity for KCl/NaCl flotation. Mechanism studies indicated that the trend in contact angle changes on the KCl crystal surface closely mirrored the trend in flotation recovery. Molecular dynamics simulations demonstrated that at 0 °C, the presence of DOD resulted in a higher diffusion coefficient for ODA molecules compared to the system without DOD. Additionally, the water molecules in System 3 exhibited a lower diffusion coefficient and a greater number of hydrogen bonds. This novel compound collector offers a potential solution for improving KCl recovery and reducing ODA consumption during low-temperature flotation. It holds significant theoretical and practical implications for advancing low-temperature KCl flotation technology. Full article

This study introduces a novel, two-stage extraction system that combines Ohmic-Accelerated Steam Distillation (OASD) with Supercritical CO₂ Extraction (SSCO₂) to efficiently recover bioactive compounds from plant-based wastes with varying cell wall complexities. Brewer’s spent grain (BSG) and cocoa shell were selected as representative models for soft and rigid cell wall structures, respectively. The optimized extraction process demonstrated significantly enhanced efficiency compared to traditional methods, achieving recovery rates in BSG of 89% for antioxidants, 91% for phenolic acids, and 90% for polyphenolic compounds. Notably, high yields of p-coumaric acid (95%), gallic acid (94%), ferulic acid (82%), quercetin (87%), and resveratrol (82%) were obtained with minimal cellular structural damage. For cocoa shells, despite their lignin-rich, rigid cell walls, recovery rates reached 73% for antioxidants, 79% for phenolic acids, and 74% for polyphenolic compounds, including chlorogenic acid (94%), catechin (83%), vanillin (81%), and gallic acid (94%). Overall, this hybrid technique significantly improved extraction efficiency by approximately 60% for BSG and 50% for cocoa shell relative to conventional approaches, highlighting its novelty, scalability, and potential for broad application in the sustainable valorization of diverse plant-based waste streams. This research presents a green and efficient platform suitable for valorizing agri-food by-products, supporting circular economy goals. Further studies may explore scale-up strategies and economic feasibility for industrial adoption. Full article

To overcome poor catalyst recovery and inefficient mass transfer in photocatalytic water treatment, this study presents novel Triply Periodic Minimal Surface (TPMS) photocatalytic reactors (PCRs) fabricated via Stereolithography (SLA) 3D printing. Five TiO₂-loaded reactors (Fischer-Radin-Dunn (FRD), Neovius (N), Diamond (D), I-graph Wrapped Package (IWP), Gyroid (G)) with hierarchical porosity were designed. Using methylene blue (MB) as the target pollutant, the photocatalytic degradation performance of TPMS-PCRs is evaluated and Computational Fluid Dynamics (CFD) hydrodynamic simulations are conducted to analyze their flow characteristics under both horizontal and rotational flow fields. The catalytic efficiency of TPMS reactors is influenced not only by pore characteristics, specific surface area, and inter-pore connectivity, but also by the flow velocities on both the reactor surface and within its internal channels. The FRD-type TPMS-PCR loaded with 2.5 wt% TiO₂ exhibited optimal photocatalytic performance, achieving 95.36% degradation efficiency under rotational flow within 2.5 h, compared to 88.2% under horizontal flow. Remarkably, after five degradation cycles, its efficiency further improved to 96.7%, demonstrating its excellent stability. The rotational flow field enhanced the average flow velocity by approximately sixfold compared to horizontal flow, with the D-type reactor reaching a maximum surface velocity of 5.3 × 10⁻² m/s. Full article

In 2020, a high-intensity wildfire burned over 35,000 ha in the Santa Cruz Mountains of California, including over 1700 ha of old-growth coast redwood forest. This event created a unique opportunity to evaluate post-fire succession. We compared vegetation recovery in high versus low/moderate severity burned areas using data collected one year and four years following the fire. Random plot sampling was conducted at Big Basin Redwoods State Park to assess the regeneration of trees, shrubs, and herbaceous species. Descriptive and inferential statistical analyses were used to assess recovery over time and across burn severities. Results indicate significant increases in shrub cover and richness over time, with a positive association between shrub recruitment and high-severity fire. Notably, the fire-adapted species blue blossom (Ceanothus thyrsiflorus Eschsch.), which was not recorded one year following the fire, dominated the shrub layer after four years, particularly in higher severity areas. Herbaceous species also exhibited an increase in cover and richness over time, though a substantial portion of that increase was based on non-native species recruitment. Analysis did not indicate a significant relationship between fire severity and herbaceous species recovery, however. The regeneration of tree species occurred both through seedling recruitment and basal sprouting. The recruitment of basal sprouts was prolific following the fire, particularly for coast redwood. The number of basal sprouts declined significantly during the time frame of this study, as the sprouts became larger and began to self-thin. Seedling abundance, on the other hand, exhibited an approximately 30-fold increase. Seedling recruitment was primarily driven by coast redwood (Sequoia sempervirens [Lamb. ex D.Don] Endl) and Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) and was positively correlated with low/moderate fire severity. These findings underscore the complex interactions shaping post-fire forest dynamics and highlight the importance of understanding such patterns to inform management strategies that support the resiliency of coast redwood forests in an era of increasing wildfires. Full article

Unconventional oil reservoirs are tight and often host micro-nano pores, and huff and puff is usually adopted for such reservoirs, mainly utilizing the mechanism of spontaneous imbibition. The penetration depth into the matrix during imbibition is one of the key influencing factors of oil recovery. In circumstances where a water phase is present in the reservoir, the injected oil displacement agent may not directly contact the oil phase, but instead needs to diffuse and migrate to the oil–water interface to adjust the capillary force, thereby affecting the imbibition depth. Therefore, the diffusion law of the oil displacement agent can indirectly affect the oil recovery by imbibition. In this study, microfluidic experiments were conducted to investigate the diffusion of nano oil displacement agents at different pore sizes (100 μm). The results show that the concentration distribution of nano oil displacement agents near the injection end was uniform during the diffusion process, and the concentration showed a decreasing trend with increasing depth. As the pore size decreased, the diffusion coefficient also decreased, and the diffusion effect deteriorated. There was a lower limit of pore size that allowed diffusion at approximately 15.66 μm. The diffusion law of the nano oil displacement agent in porous media obtained in this study is of great significance for improving the recovery rate of unconventional oil and gas resources. Full article

The Diaoyu Islands Folded-Uplift Belt consists of metamorphic basement, magmatic rocks and Paleogene series in the Eastern Depression Zone of the East China Sea Basin which was deformed and uplifted by magma emplacement. The emplacement of the magma resulted in an unclear understanding of the Paleogene geomorphy in the paleo-uplift, further affecting the analysis of the eastern boundary and the sedimentary environment of Paleogene prototype basin in the Eastern Depression Zone. To explore the Paleogene geomorphy and magma emplacement process of the Diaoyu Islands Folded-Uplift Belt, we conducted a detailed interpretation of 2-D seismic profiles and identified nearshore subaqueous fans and fan deltas within the deformed strata. The development scale of them helps to determine the approximate location of the Paleogene eastern boundary of the Eastern Depression Zone. We integrated the boundary location with gravity, magnetic, and well data to obtain the Paleogene geomorphy of the Diaoyu Islands Folded-Uplift Belt. Our results indicate that the subduction direction of the Pacific Plate was almost perpendicular to the Eurasian Plate during the late Eocene, leading to the development of numerous left-lateral strike-slip faults within the East China Sea Basin, further forming channels within the paleo-uplift, which connected the Eastern Depression Zone and the ocean. In the Early Oligocene, the subduction rate of the Pacific Plate abruptly increased, resulting in large-scale and significant exhumation of the paleo-uplift, and the Eastern Depression Zone had transformed into a lacustrine sedimentary environment. Furthermore, due to the continuous retreat of the Pacific Plate, the extension center of the back-arc basin moved to the eastern margin of the Eastern Depression Zone in the late Oligocene. This work provides a method for recovering the geomorphology of complex tectonic units in back-arc basins based on fine seismic interpretation, solving the key problem that constrained the recovery of boundaries and sedimentary environment of the prototype basin. Full article

Light-emitting diodes (LEDs) are made up of precious metals, e.g., gallium. These elements can be recovered and reused, reducing the need for new raw materials. Proper recycling prevents harmful substances in LEDs, such as lead and arsenic, from contaminating the environment. Recycling LEDs uses less energy compared to producing new ones, leading to lower carbon emissions. The valuable metal gallium faces the challenge of supply and demand due to the surge in its demand, the difficulty of separating it from minerals, and processing issues during extraction. In this review, we describe the methods for recycling gallium from LEDs by using different techniques such as pyrolysis (95% recovery), oxalic acid leaching (83.2% recovery), HCL acid leaching of coal fly ash (90–95% recovery), subcritical water treatment (80.5% recovery), supercritical ethanol (93.10% recovery), oxidation and subsequent leaching (91.4% recovery), and vacuum metallurgy separation (90% recovery). Based on our analysis, hydrometallurgy is the best approach for recovering gallium. It is reported that approximately 5% of the waste from LEDs is adequately recycled, whereas the total gallium potential wasted throughout production is over 93%. By recycling LEDs, we can minimize waste, conserve resources, and promote sustainable practices. Thus, recycling LEDs is essential for strengthening a circular economy. Full article

Accurate determination of sulfate content in phosphogypsum (PG) and cement-based materials is crucial for understanding the corrosion mechanisms of cement-based materials, developing corrosion models, establishing durability design methods, and implementing maintenance strategies. To overcome the limitations of traditional gravimetric and EDTA titration methods in accurately quantifying low-concentration SO₄²⁻ in PG and cement-based materials, an IoT-enabled conductometric titration system was developed to improve precision and automation. First, the principle of conductivity titration is introduced, in which Ba(NO₃)₂ is used as the titrant. Second, a method for eliminating the effects of H⁺, Cl⁻, and Ca²⁺ ions is proposed. The impact of the titration rate, volume of liquid to be measured, titrant concentration, and other interfering ions on the results is discussed. Finally, the conductivity titration method was successfully applied to determine sulfate content in PG and cement-based materials. The results demonstrate that the self-developed conductivity titrator exhibits high testing accuracy, with a standard deviation of 0.013 for 15 repeated titrations, a coefficient of variation of 0.52%, and a recovery rate between 103.2% and 103.9%. The optimal solution volume to be determined was 5 mL. Ba(NO₃)₂, at approximately twice the sulfate concentration, enhances endpoint sensitivity and minimizes precipitation interference. Ag₂O and CO₂ significantly reduce the interference from H⁺, Cl⁻, and Ca²⁺ ions by generating weakly conductive substances, such as H₂O, AgCl, Ag₃PO₄, CaF₂, and CaCO₃. Conductometric titration demonstrated accurate SO₄²⁻ quantification in PG and cement-based materials, enabling standardized protocols. This approach provides both theoretical and technical support for rapid sulfate detection in complex systems, with significant implications for both industry and academia. For the industry, it offers a reliable and standardized method for sulfate detection, enhancing quality control and process efficiency. For academia, it establishes a foundation for further research in civil engineering and environmental material analysis, contributing to both practical applications and theoretical advancements. Full article

The steam flooding–gravity drainage technology has become one of the effective alternative development methods in the middle and later stages of thin-layer ultra-viscous oil steam throughput, with predicted recovery rate of over 50%. Currently, there is a lack of relevant technical research on the composite swallowing and spitting preheating stage. This is in response to the slow preheating of the oilfield and the large differences in connectivity between injection and production wells. The dynamic analysis method was used to analyze the key factors that restrict the efficient connectivity of steam throughput preheating. Based on this, a series steam throughput preheating efficient connectivity technologies were proposed. Physical simulation, numerical simulation, and other methods were used to characterize and demonstrate the technical principles and operating of the efficient connectivity technology. The research results were successfully applied to the super-viscous oil reservoirs of the Fengcheng oilfield in Xinjiang. The results show that the main factors severely limiting the balanced and rapid connectivity between injection and production wells are the limited radius of steam coverage, low utilization degree oil layers, and frequent unilateral steam breakthroughs. The reservoir expansion transformation has improved the reservoir properties along the horizontal section, increasing the utilization rate of the horizontal section from 51% to 90%, achieving rapid connectivity injection and production wells, and shortening the conventional throughput preheating cycle by 3–4 cycles. The group combination steam injection method achieved a centralized increase in thermal energy, with the inter-well connectivity changing from unidirectional to a broader area The reasonable steam injection intensity was 15 t/m, the regional temperature field increased from 83 °C to 112 °C, and the steam area expanded by approximately 10 m. The multi-medium composite technology achieved a dual increase in steam coverage and profile utilization, with the steam coverage radius increasing by 15 m and the oil reservoir profile utilization increasing by more than 30%. The temporary plugging and fracturing of the reservoir achieved the sealing of inherited breakthrough channels, directing the steam to unused areas, increasing the utilization rate to 89.2%, and shortening the throughput preheating cycle by 3 cycles. This series of technologies has achieved remarkable results in actual application in super-heavy oilfield, which has certain reference significance for the efficient and low-carbon development of heavy oil steam throughput reservoir turning into drive and release. Full article

As a novel energy storage technology, seawater batteries exhibit significant application potential across various domains, including marine exploration, underwater communication, and island power supply. However, the deep-sea low-temperature environment adversely affects the performance of seawater battery systems. This paper proposes a seawater metal–air battery system equipped with a preheater (SMAB-P). This innovative system establishes stable natural circulation and utilizes the high-temperature seawater within the system to preheat the incoming low-temperature seawater, thereby effectively enhancing battery performance. It was found that, compared with the SMAB system without a preheater, when achieving a heat recovery rate of 100% the average temperature of seawater in the electrode plate area of the SMAB-P system can be increased by 54%. Consequently, the electrical conductivity of seawater within the system can be increased by approximately 20%, leading to a significant reduction in ohmic losses and an enhancement in the load voltage of the battery. Furthermore, increasing either the height or width of the electrode plate can enhance self-driven force and circulation flow rate, as well as both average and maximum temperatures of seawater in the electrode plate area to some extent. Reducing the annular space of the preheater can significantly increase the seawater temperature within the system, but excessive reduction may hinder the effective replacement of fresh seawater in the system. It is also noted that seawater velocity in the electrode plate channels remains relatively low and evenly distributed while exhibiting very small temperature variation. Full article

With the large-scale integration of renewable energy through power electronic inverters,
modern power systems are gradually transitioning to low-inertia systems. Grid-forming
inverters are prone to power overshoot and frequency deviation when facing external
disturbances, threatening system stability. Existing methods face two main challenges in
dealing with complex disturbances: neural-network-based approaches have high computational
burdens and long response times, while traditional linear algorithms lack sufficient
precision in adjustment, leading to inadequate system response accuracy and stability. This
paper proposes an innovative coordinated adaptive control strategy for virtual inertia and
damping. The strategy utilizes a Radial Basis Function neural network for the adaptive
regulation of virtual inertia, while the damping coefficient is adjusted using a linear algorithm.
This approach provides refined inertia regulation while maintaining computational
efficiency, optimizing the rate of change in frequency and frequency deviation. Simulation
results demonstrate that the proposed control strategy significantly outperforms traditional
methods in improving system performance. In the active power reference variation
scenario, frequency overshoot is reduced by 65.4%, active power overshoot decreases by
66.7%, and the system recovery time is shortened. In the load variation scenario, frequency
overshoot is reduced by approximately 3.6%, and the maximum frequency deviation is
reduced by approximately 26.9%. In the composite disturbance scenario, the frequency
peak is reduced by approximately 0.1 Hz, the maximum frequency deviation decreases by
35%, and the power response improves by 23.3%. These results indicate that the proposed
method offers significant advantages in enhancing system dynamic response, frequency
stability, and power overshoot suppression, demonstrating its substantial potential for
practical applications. Full article

In the present research, a novel magnetic adsorbent was developed via the sol–gel method by coating CuFe₂O₄ nanoparticles on biochar sourced from brewed tea waste. The synthesized adsorbent was utilized for the removal of Ni(II) ions from aqueous media. The adsorption efficiency of Ni(II) ions was assessed under crucial experimental conditions such as initial solution pH, contact time, adsorbent dosage, and initial Ni(II) concentration. The adsorbent exhibited rapid adsorption kinetics, achieving equilibrium in approximately 15 min, and maintained high efficiency across a wide pH range. Adsorption experiments were conducted for Ni(II) solutions at their natural pH (5.6) to minimize chemical usage and enhance process simplicity. An impressive maximum adsorption capacity of 232.6 mg g⁻¹ was recorded, outperforming many previously reported adsorbents. Furthermore, desorption studies demonstrated nearly 100% recovery of Ni(II) ions using 1.0 M HCl solution, indicating excellent regeneration potential of the adsorbent. Additionally, the prediction performance of an artificial neural network (ANN) model was evaluated to predict Ni(II) removal efficiency based on experimental variables, showing strong agreement with experimental data. Isotherm and kinetic models were also applied to the data to estimate the adsorption mechanisms. These findings demonstrate the promise of CuFe₂O₄-modified tea waste biochar for sustainable water treatment applications. Full article

Conventional reports on wildfire damage focus on damage to built structures and life loss without capturing the long-term loss of many environmental benefits provided by natural capital. The assessment of the full cost of a wildfire event can be very challenging and time-consuming due to its broad range of impacts traversing decades. Two major wildfires, the 2021 Caldor Fire and 2022 Mosquito Fire, impacted rural communities and burned nearly 30 percent of the approximately 1 million acres of forests and private timber lands in the Upper American River Watershed (UARW) in California’s Sierra Nevada headwaters. The UARW provides a stock of natural capital that provides a flow of environmental benefits, or ecosystem goods and services, including California statewide water supply that was not recognized in the conventional reporting to properly inform decisions and investments for mitigation and recovery. Leveraging new tools available through the recent valuation of the UARW’s ecosystem goods and services, this study provides a first look at the magnitude of damage to the headwaters’ ecosystem from wildfires and, thus, informs proactive, adaptive management actions and post-disaster recovery and restoration. Using burn severity data and per-acre estimates of ecosystem goods and services, we estimate natural capital damage of over USD 14.8 billion across an optimistically estimated period of 20 years. Several recovery time horizons are used to evaluate the sensitivity of the analysis. These findings provide important benchmarks and a viable approach for all levels of government and private entities responsible for allocating resources, mitigating wildfire risks, and improving watershed health. Full article