Search Results (173)

A recently proposed method called “controlled swelling of monolithic films” was implemented to prepare ultra-high-molecular-weight polyethylene (UHMWPE) ultrafiltration membranes. For the first time, the effect of UHMWPE molecular weight (MW) on the structure and properties of the membranes prepared via this special case of thermally induced phase separation was studied in detail. The morphology and properties of the membranes were studied using SEM, DSC, liquid–liquid displacement porometry, and standard methods for the evaluation of mechanical properties, permeance, rejection, and abrasion resistance. High-quality membranes with a tensile strength of 5.0–17.8 MPa, a mean pore size of 25–50 nm, permeance of 17–107 L m⁻² h⁻¹ bar⁻¹, rejection of model contaminant (blue dextran) of 72–98%, and great abrasion resistance can be prepared only if the MW of the polymer in the initial monolithic film is sufficiently high. The properties of the membranes can effectively be controlled by changing the MW of the polymer and the mass fraction of the latter in the swollen film. Shrinkage is responsible for the variation in the membrane properties. The membranes prepared from a higher-MW polymer are more prone to shrinking after the removal of the solvent. Shrinkage decreases before rising again and minimizes with an increase in the polymer content in the swollen film. Full article

Metallurgical equipment foundations exposed to prolonged 300–500 °C environments are subject to explosion risks, necessitating materials that are resistant to thermo-shock-coupled loads. This study investigated the real-time dynamic compressive behavior of high-performance concrete (HPC) reinforced with steel fibers (SFs), polypropylene fibers (PPFs), polyvinyl alcohol fibers (PVAFs), and their hybrid systems under thermo-shock coupling using real-time high-temperature (200–500 °C) SHPB tests. The results revealed temperature-dependent dynamic responses: SFs exhibited a V-shaped trend in compressive strength evolution (minimum at 400 °C), while PPFs/PVAFs showed inverted V-shaped trends (peaking at 300 °C). Hybrid systems demonstrated superior performance: SF-PVAF achieved stable dynamic strength at 200–400 °C (dynamic increase factor, DIF ≈ 1.65) due to synergistic toughening via SF bridging and PVAF melt-induced pore energy absorption. Microstructural analysis confirmed that organic fiber pores and SF crack-bridging collaboratively optimized failure modes, reducing brittle fracture. A temperature-adaptive design strategy is proposed: SF-PVAF hybrids are prioritized for temperatures of 200–400 °C, while SF-PPF combinations are recommended for 400–500 °C environments, providing critical guidance for explosion-resistant HPC in extreme thermal–industrial settings. Full article

To address the challenges of concrete construction in polar regions, this study investigates the feasibility of fabricating cement-based materials under severely low temperatures using electric-induced heating curing methods. Cement mortars incorporating fly ash (FA-CM), ground granulated blast furnace slag (GGBS-CM), and metakaolin (MK-CM) were cured at environmental temperatures of −20 °C, −40 °C, and −60 °C. The optimal carbon fiber (CF) contents were determined using the initial electric resistivity to ensure a consistent electric-induced heating curing process. The thermal profiles during curing were monitored, and mechanical strength development was systematically evaluated. Hydration characteristics were elucidated through thermogravimetric analysis (TG), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) to identify phase compositions and reaction products. Results demonstrate that electric-induced heating effectively mitigates the adverse effect caused by the ultra-low temperature constraints, with distinct differences in the strength performance and hydration kinetics among supplementary cementitious materials. MK-CM exhibited superior early strength development with strength increasing rates above 10% compared to the Ref. specimen, which was attributed to the accelerated pozzolanic reactions. Microstructural analyses further verified the macroscopic strength test results that showed that electric-induced heating curing can effectively promote the performance development even under severely cold environments with a higher hydration degree and refined micro-pore structure. This work proposes a viable strategy for polar construction applications. Full article

Laser-based powder bed fusion of metals (PBF-LB/M) is one of the most promising additive manufacturing technologies to fabricate complex-structured metal parts. However, its corresponding applications have been limited by technical bottlenecks and increasingly strict industrial requirements. Process optimization, a scientific issue, urgently needs to be solved. In this paper, a three-phase transient model based on the level-set method is established to examine the heat transfer and melt pool behavior in PBF-LB/M. Surface tension, the Marangoni effect, and recoil pressure are implemented in the model, and evaporation-induced mass and thermal loss are fully considered in the computing element. The results show that the surface roughness and density of metal parts induced by heat transfer and melt pool behavior are closely related to process parameters such as laser power, layer thickness, scanning speed, etc. When the volumetric energy density is low, the insufficient fusion of metal particles leads to pore defects. When the line energy density is high, the melt track is smooth with low porosity, resulting in the high density of the products. Additionally, the partial melting of powder particles at the beginning and end of the melting track usually contributes to pore formation. These findings provide valuable insights for improving the quality and reliability of metal additive manufacturing. Full article

Plant roots influence various soil physical properties by altering the soil structure and pore configuration; however, a detailed understanding of these effects remains limited. In this study, we applied a relatively simple approach for segmenting plant roots and soil constituents using X-ray computed tomography (CT) images to evaluate root-induced changes in soil structure. The method combines manual initialization with a layer-wise automated region-growing approach, enabling the extraction of the root systems of soybean, Italian ryegrass, and Guinea grass. The method utilizes freely available software with a simple interface and does not require advanced image analysis skills, making it accessible to a wide range of researchers. The soil particles, pore water, and pore air were segmented using a Kriging-based thresholding technique. The segmented four-phase images allowed for the quantification of the volume fractions of soil constituents, pore size distributions, and coordination numbers. Furthermore, by separating the rhizosphere and bulk soil, we found that the root presence significantly reduced solid fractions and increased water content, particularly in the upper soil layers. Macropores and fine pores were observed near the roots, highlighting the complex structural impacts of root growth. While further validation is needed to assess the method’s applicability across different soil types and imaging conditions, it provides a practical basis for visualizing and quantifying root–soil interactions, and could contribute to advancing our understanding of how plant roots influence key soil hydraulic and thermal properties. Full article

In order to clarify the pore evolution and coupling characteristics with hydrocarbon charging in the deep-buried ultra-tight sandstone reservoirs of the second member of Xujiahe Formation (hereinafter referred to as the Xu 2 Member) on the eastern slope of the Western Sichuan Depression, this study integrates burial history and thermal history with analytical methods including core observation, cast thin section analysis, scanning electron microscopy, carbon-oxygen isotope analysis, and fluid inclusion homogenization temperature measurements. The Xu 2 Member reservoirs are predominantly composed of lithic sandstones and quartz-rich sandstones, with authigenic quartz and carbonates as the main cementing materials. The reservoir spaces are dominated by intragranular dissolution pores. The timing of reservoir densification varies among different submembers. The upper submember underwent compaction during the Middle-Late Jurassic period due to the high ductility of mudstone clasts and other compaction-resistant components. The middle-lower submembers experienced densification in the Late Jurassic period. Late Cretaceous tectonic uplift induced fracture development, which enhanced dissolution in the middle-lower submembers, increasing reservoir porosity to approximately 5%. Two distinct phases of hydrocarbon charging are identified in the Xu 2 Member. The earlier densification of the upper submember created unfavorable conditions for hydrocarbon accumulation. In contrast, the middle-lower submembers received hydrocarbon charging prior to reservoir densification, providing favorable conditions for natural gas enrichment and reservoir formation. Three sweet-spot reservoir development patterns are recognized: paleo-structural trap + (internal source rock) + source-connected fracture assemblage type, paleo-structural trap + internal source rock + late-stage fracture assemblage type, and paleo-structural trap + (internal source rock) + source-connected fracture + late-stage fracture assemblage type. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

Green soybeans, or edamame (Glycine max L. Merril), serve as a superior source of phytochemicals and other nutritive substances and are commonly used as ingredients and additives in food products due to their polyphenols’ functional properties and antioxidant activity. Hence, it is very important to use a process to extract compounds with functional roles from plants as efficiently as possible. In this study, we sought to identify the optimal conditions for extracting genistein, belonging to the aglycone subgroup of isoflavones, from edamame using the cold plasma (CP) and enzyme method. Additionally, the impact of various drying techniques (spray-drying and freeze-drying) and storage conditions on the crude genistein extract powder was evaluated. The findings showed that the maximum values for the total phenolic content (TPC), total flavonoid content (TFC), and genistein (22.5 ± 0.23 mg of gallic acid equivalents (GAE)/100 g; 15.3 ± 0.13 mg of catechin equivalents (CAE)/100 g; and 12.6 ± 0.10 mg/100 g, respectively) were achieved under optimal pretreatment conditions using a CP gas flow rate of 5 L/min for 30 min, followed by enzymatic treatment at a specific enzyme concentration of 2.0% (v/v) for 240 min of incubation. Moreover, a scanning electron microscopy (SEM) analysis demonstrated that the CP and enzyme treatment induced significant structural changes, as evidenced by the presence of deeper pores on the surface of the powder granules. Spray-drying demonstrated a superior efficacy compared to freeze-drying for encapsulating the crude isoflavone extract. This study’s results also demonstrated that storage at 4 °C significantly stabilized the TPC, TFC, and genistein content and the antioxidant activity while preserving the physical properties (solubility and color) of the crude extract powder for up to 45 days. In summary, cold plasma pretreatment and enzymatic treatments offer practical solutions by enhancing the efficiency of non-thermal extraction processes, thereby increasing the yield of bioactive compounds, maintaining quality, and diminishing reliance on traditional, harsh methods. The elevated genistein content in the crude extract powder indicates its prospective application as a functional ingredient in various food and nutraceutical contexts. Full article

Despite their high porosity and wide applicability, silica xerogels face mechanical strength limitations for high-performance applications. This study presents an ambient-pressure sol-gel strategy utilizing calcium-glycerol synergy to produce robust xerogels with enhanced properties. Physicochemical analyses reveal that controlled Ca²⁺ incorporation (optimal at 6 wt.%) accelerates gelation kinetics while establishing a hybrid network through ionic complexation and hydrogen bonding. The resulting xerogels achieve exceptional compressive strength (30.8 MPa) while maintaining uniform mesoporosity (50–90 nm pore size). Remarkably, the as-prepared silica xerogels demonstrate outstanding thermal insulation, maintaining a 220 °C temperature differential in 300 °C environments. These results prove that the ambient-pressure sol-gel strategy utilizing calcium-glycerol synergy can enhance the mechanical performance and thermal insulation performance of silica xerogels with the dual actions of Ca²⁺-induced network reinforcement via silanol coordination and glycerol-mediated stress relief during ambient drying. Overall, this work can offer a scalable, energy-efficient approach to produce high-performance silica xerogels with huge potential in building envelopes and aerospace systems. Full article

Polyethersulfone (PES) has been widely used to fabricate hollow-fiber ultrafiltration membranes due to its good oxidative, thermal, and hydrolytic stability. Typical PES hollow-fiber membranes with a single bore have limited strength and may break under uneven pressure and vibration during membrane backwashing. Multi-channel hollow-fiber membranes have stronger breaking force due to their larger cross-sectional area, but fabricating them remains challenging due to the difficulty in controlling the phase inversion process. This study uses the vapor-induced phase separation (VIPS) method to fabricate a seven-channel PES hollow-fiber membrane, and the air gap and air relative humidity can help in membrane morphology control. Moreover, carboxylic graphene quantum dots (CGQDs) are first used in ultrafiltration membranes to increase membrane porosity and hydrophilicity. We found that the membrane prepared with a 7.5% CGQD mass fraction, a 10 cm air gap, and 99% relative humidity had the highest flux and porosity; the membrane pore size distribution was concentrated at 72 nm, and the pure water flux could reach 464 L·m⁻² h⁻¹·bar⁻¹. In the long-term filtration performance test, the membrane can reject more than about 15% TOC and 84% turbidity at 50 L·m⁻² h⁻¹ flux, confirming its stability for water purification applications. Full article

Cohesive soil in the reservoir area is vulnerable to natural disasters because of its poor erosion resistance and low strength. Therefore, it needs to be reinforced. Microbially induced calcium carbonate precipitation (MICP) is a sustaibable soil reinforcement technique with low energy consumption and no pollution. Different combinations of Bacillus subtilis bacterial solution (BS) concentrations and cementing solution (CS) concentrations were set to perform MICP solidification treatment. The characterization of cohesive soil before MICP was carried out by means of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and Laser Particle Size Analyzer (LPSA). The results showed that the unreinforced soil showed an amorphous state with low strength and the particle size distribution was dominated by powder particles. However, with the addition of BS concentrations and CS concentrations, SEM results showed that spherical and rhombohedral minerals filled the pores of the cohesive soil, which increased the content of precipitations and enhanced the cementitious characteristics. When the concentrations of CS or BS were fixed, CaCO₃ content, deviatoric stress, shear strength, cohesive force, and internal friction angle all showed a trend of first increasing and then decreasing with the increase in CS or BS concentration. The optimal combination of CS and BS concentration was 1.5 mol/L and OD₆₀₀ = 1.8. Thermochemical analyses showed an improved thermal stability of the reinforcing cohesive soil, with the lowest mass loss (32%) and the highest pyrolysis temperature (812 °C) of the samples at the optimal combination of BS and CS concentration. This study is expected to improve the understanding of the MICP reinforcement process and contribute to the optimal design of future biologically mediated soil amendments, promoting bioremediation. Full article

Sulfation is a common strategy to enhance the acidity and modify the adsorption properties of metal–organic frameworks (MOFs), yet its impact on the coordination and accessibility of active sites remains unclear. In this study, we investigate two structurally related systems—sulfated UiO-66 (UiO-66-SO₄) and sulfated tetragonal zirconia (S-ZrO₂)—by FTIR spectroscopy with probe molecules. Isotope exchange experiments on S-ZrO₂ reveal that dehydration above 250 °C induces tridentate SO₄ coordination, while hydration leads to a reversible transition to a bidentate coordination mode. In UiO-66-SO₄, sulfates are coordinated in a bidentate fashion to Zr₆O₆ clusters, significantly affecting the accessibility of Zr sites in defective pores. This coordination prevents CO adsorption but allows acetonitrile adsorption even after room temperature activation. Unlike S-ZrO₂, due to its lower thermal stability, UiO-66-SO₄ cannot be evacuated at high temperatures and dehydration at 250 °C does not induce tridentate coordination. The presence of H-bonded hydroxyls in UiO-66-SO₄ after activation at 250 °C supports this coordination model, indicating the formation of OH-coordinated Zr sites that are inaccessible to CO but interact with stronger bases like acetonitrile. Overall, this study provides new insights into the coordination chemistry of sulfated UiO-66 and highlights that sulfation can tune acidity and adsorption in MOFs for potential catalytic and adsorption applications. Full article

The salt layer, characterized by its low permeability and excellent damage self-healing properties, is an ideal geological body for CO₂ geological storage. However, the relatively high permeability of mudstone interlayers may reduce the safety of CO₂ long-term storage in bedded salt caverns. This study establishes a thermal–hydraulic–mechanical (THM) coupled physical and mathematical model for CO₂ geological storage in the Huaian salt cavern, analyzes the factors affecting CO₂ flow behavior, and proposes measures to enhance the safety of CO₂ storage in salt caverns. The results indicate that the permeability of both salt layers and mudstone interlayers is influenced by stress-induced deformation within the salt cavern. From the salt cavern edge to the simulation boundary, the permeability and volume strain exhibit a trend of rapid decline, followed by a gradual increase, and an eventual stabilization or slight reduction. The seepage velocity, pore pressure, and flow distance of CO₂ in the mudstone interlayer are significantly higher than those in the salt layer, leading to CO₂ migration along the interfaces between the mudstone and salt layer. With the increase in storage time, the permeability of the mudstone interlayer gradually decreases, while the permeability of the salt layer shows a general tendency to increase. The elevated storage pressure reduces the permeability of the mudstone interlayer, while increasing the permeability of the salt layer, and enhances the seepage velocity in both the mudstone and salt layers. To enhance the safety of CO₂ long-term storage in bedded salt caverns, it is recommended to minimize the presence of mudstone interlayers during site selection and cavern construction, optimize the storage pressure, and strengthen monitoring systems for potential CO₂ leakage. Full article

Condensate oil, due to its inherent physical and chemical properties, can accelerate the spontaneous combustion of corrosion products in storage tanks during transportation or storage, posing significant risks to the safety and sustainability of energy infrastructure. While prior research has primarily examined crude oil or reactive sulfur effects on tank corrosion, the mechanistic role of condensate oil in promoting corrosion product ignition remains unclear. To address this knowledge gap, this study investigates the impact of condensate oil on simulated tank corrosion product compounds (STCPCs) through a combination of microstructural analysis (XRD and SEM) and thermal behavior characterization (TG-DSC). The results reveal that condensate oil treatment markedly increases STCPC surface roughness, inducing crack formation and pore proliferation. These structural changes may enhance the adsorption of O₂ and condensate oil, thereby amplifying STCPC reactivity. Notably, condensate oil reduces the thermal stability of STCPC, increasing its spontaneous combustion propensity. DSC analysis further demonstrates that condensate oil introduces additional exothermic peaks during oxidative heating, releasing heat that accelerates STCPC ignition. Moreover, condensate oil lowers the apparent activation energy of STCPC by 1.44 kJ/mol and alters the dominant reaction mechanism. These insights advance the understanding of corrosion-induced spontaneous combustion and highlight critical sustainability challenges in petrochemical storage and transportation. By elucidating the hazards associated with condensate oil, this study provides actionable theoretical guidance for improving the safety and environmental sustainability of energy logistics. Future work should explore mitigation strategies, such as corrosion-resistant materials or optimized storage conditions, to align industrial practices with sustainable development goals. Full article

The Loess Plateau region of China has an anomalous climate and frequent geological disasters. Hipparion laterite in seasonally frozen regions exhibits heightened susceptibility to freeze–thaw (F-T) cycling, which induces progressive structural weakening and significantly elevates the risk of slope instability through mechanisms including pore water phase transitions, aggregate disintegration, and shear strength degradation. This study focuses on the slip zone Hipparion laterite from the Nao panliang landslide in Fugu County, Shaanxi Province. We innovatively integrated F-T cycling tests with ring-shear experiments to establish a hydro-thermal–mechanical coupled multi-scale evaluation framework for assessing F-T damage in the slip zone material. The microstructural evolution of soil architecture and pore characteristics was systematically analyzed through scanning electron microscopy (SEM) tests. Quantitative characterization of mechanical degradation mechanisms was achieved using advanced microstructural parameters including orientation frequency, probabilistic entropy, and fractal dimensions, revealing the intrinsic relationship between pore network anisotropy and macroscopic strength deterioration. The experimental results demonstrate that Hipparion laterite specimens undergo progressive deterioration with increasing F-T cycles and initial moisture content, predominantly exhibiting brittle deformation patterns. The soil exhibited substantial strength degradation, with total reduction rates of 51.54% and 43.67% for peak and residual strengths, respectively. The shear stress–displacement curves transitioned from strain-softening to strain-hardening behavior, indicating plastic deformation-dominated shear damage. Moisture content critically regulates pore microstructure evolution, reducing micropore proportion to 23.57–28.62% while promoting transformation to mesopores and macropores. At 24% moisture content, the areal porosity, probabilistic entropy, and fractal dimension increased by 0.2263, 0.0401, and 0.0589, respectively. Temperature-induced pore water phase transitions significantly amplified mechanical strength variability through cyclic damage accumulation. These findings advance the theoretical understanding of Hipparion laterite’s engineering geological behavior while providing critical insights for slope stability assessment and landslide risk mitigation strategies in loess plateau regions. Full article