Search Results (3,222)

In this study, a thermally crosslinking clay-free weak gel water-based drilling fluid based on salt-responsive polymers and crosslinking agents was investigated as a promising and feasible strategy. Firstly, a salt-tolerant polymer was synthesized using N,N-dimethylacrylamide (DMAA), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonopropyl)ammonium hydroxide (DMAPS), and acrylamide (AM). BPEI_10,000 was selected as the thermal crosslinking agent. The optimal crosslinking was achieved at 180 °C and 36% NaCl, with RMFL at 2.0% and BPEI_10,000 at 0.1%. Performance evaluation demonstrated that the crosslinking between RMFL and BPEI_10,000 could enhance the AV, PV, and YP of the RMFL(BPEI_10,000)/CF-WBDFs after aging at 180 °C for 16 h and reduce FL_API. The RMFL(BPEI_10,000)/CF-WBDFs exhibited appropriate shear-thinning behavior, viscoelasticity, thixotropy, and recoverable viscosity under high-temperature, high-salinity, and high-pressure conditions. Mechanism analysis revealed that RMFL and BPEI_10,000 could form a predominantly negatively charged, three-dimensional crosslinking weak gel at high temperatures. The crosslinking weak gel could form dense filter cakes, improving rheological properties and reducing filtration loss of CFWBDFs in high-temperature, high-salinity environments. This paper proposed a novel method to address the technical challenge of rheological performance failure of CFWBDFs, offering valuable insights for subsequent investigations. Full article

The Dibaya Granitic and Migmatitic Complex (DGMC), located in the Kanyiki–Kapangu sector of the Kasaï Shield (Congo–Kasaï Craton, Democratic Republic of the Congo), represents a key exposure of Neoarchean continental crust in Central Africa. Despite its geological importance, information on its petrology, geochronology, geochemistry, and structural evolution remains dispersed across historical studies. This contribution presents a structured geological synthesis based exclusively on previously published cartographic, petrographic, structural, and isotopic data. No new analytical data are introduced; rather, existing datasets are systematically compiled, critically reassessed, and integrated into a coherent tectono-thermal framework. Published Rb–Sr and U–Pb ages indicate high-grade metamorphism and widespread migmatitization at ca. 2.72 Ga, followed by granitoid emplacement at ca. 2.65 Ga. Documented mineral assemblages (garnet–biotite–plagioclase–quartz ± K-feldspar ± amphibole) and the absence of reported high-pressure index minerals support high-temperature, moderate-pressure metamorphism consistent with intracrustal reworking. Reported regional geochemical characteristics suggest high-K calc-alkaline, weakly to moderately peraluminous granitoids derived predominantly from reworking of older TTG-type crust. Structural relationships, particularly along the Malafudi corridor, demonstrate strong coupling between deformation, anatexis, and magma emplacement. Collectively, this synthesis formalizes a Neoarchean intracrustal reworking model and provides a structured analytical basis for future high-resolution petrochronological and geochemical investigations. Although no new quantitative datasets are presented, this study provides the first systematic integration of dispersed geological and isotopic information for the Dibaya Complex, establishing a transparent analytical framework for future high-resolution investigations. Full article

To address the prominent problem of early rutting distress in asphalt pavements under heavy-load traffic in China, this study proposes a composite modifier consisting of direct coal liquefaction residue (DCLR), styrene–butadiene–styrene block copolymer (SBS), and styrene–butadiene rubber (SBR). The preparation process and formula were optimized through single-factor experiments and orthogonal tests. Systematic investigations were conducted on its conventional performance, water damage resistance, aging resistance, fatigue performance, rheological properties, and microscopic mechanism, with comparisons made against base asphalt, single DCLR-modified asphalt, SBS-modified asphalt, and SBS/SBR-modified asphalt. The results indicate that the optimal preparation process for the novel composite high-modulus modified asphalt is as follows: DCLR particle size of 0.3 mm, addition in molten state, shear temperature of 170 °C, shear rate of 5000 r·min⁻¹, shear time of 50 min. The optimal formula is 10% DCLR + 3% SBS + 2% SBR + 3% compatibilizer, with the addition sequence of “DCLR → SBS + compatibilizer → SBR”. This asphalt exhibits a softening point of 77.8 ± 2.1 °C, a Brookfield viscosity at 135 °C of 1.928 ± 0.105 Pa·s, and a grading of 5 for adhesion to aggregates; the rutting factor at 64 °C reaches 10.8 ± 0.9 kPa (6.43 times that of the base asphalt), the creep stiffness at −12 °C is 136 ± 12.5 MPa, and the low-temperature limit temperature is −17 °C; the freeze–thaw splitting strength ratio (TSR) is 94.6 ± 1.8%, and both aging resistance and water damage resistance are significantly superior to those of the control group asphalts (p < 0.05). The novel composite high-modulus modified asphalt showed improved overall laboratory performance and may be suitable for heavy-load traffic and complex climatic conditions, however, field validation is needed. Full article

Silver nanoparticles (AgNP), which have a wide range of applications in technical and biological fields, are produced in hundreds of tons annually and are eventually released into water, air, and soil. In this study, the effects of AgNPs on Phanerochaete chrysosporium, a white-rot fungus that plays a key role in wood waste degradation, were investigated. The AgNP were synthesized at high temperature with gallic acid under different pH conditions: near-neutral pH (~7.5), notation AgNP@GA-1, and alkaline pH (~10.5), notation AgNP@GA-2, focusing on their ability to cope with oxidative stress. The samples were characterized by fine granularity (particle diameter of 12 and 11 nm, respectively), specific plasmonic features (characteristic band at 425 and 408 nm), hydrodynamic diameter of 93 and 133 nm, respectively, and Zeta potential of −34 to −44 mV, which gave them stability over a period of three months. The fungal cultures exposed to AgNP concentrations of 40–100 µL/mL (approximately 4–11 µg/mL) presented superoxide dismutase (SOD) activity, which increased by approximately 45% at 40 µL/mL for AgNP@GA-1 after 7 days, whereas AgNP@GA-2 decreased SOD activity by up to 40% at 60 µL/mL. Both AgNP types strongly stimulated catalase (CAT) biosynthesis, with two- to three-fold increased activity on the 7th day at 100 µL/mL. CAT activity remained significantly elevated for AgNP@GA-1 on the 14th day at 60–80 µL/mL, whereas for AgNP@GA-2 it decreased by 40–60% compared with the control. Variations in malondialdehyde content indicated moderate lipid peroxidation, suggesting relatively low cytotoxic effects on fungal cells. Overall, the results demonstrate that P. chrysosporium exhibits adaptive biochemical responses to AgNP-induced oxidative stress while maintaining metabolic functionality, highlighting the potential compatibility of AgNPs with white-rot fungi involved in environmental wood waste biodegradation processes. Full article

Concrete is accelerating its transition towards green and low-carbon development, but its performance throughout its entire life cycle is significantly influenced by environmental changes, which remains a key technical challenge currently faced. The effects of early-age concrete tensile damage on thermal conductivity and moisture transport properties, as well as their coupling mechanism, remain unclear, leading to severe cracking. To explore the cracking mechanism of early-age concrete under the coupled conditions of environment and damage and to evaluate its performance throughout its lifecycle, this article conducts comparative experiments on the performance of concrete under high temperature, varying humidity, and damage conditions in the early age stage. The variation law of temperature, humidity, and strain of concrete is studied, and the evolution of microstructure and composition of concrete is explored. The response of porosity to ambient humidity exhibits opposite trends between restrained and unrestrained specimens, with rates of change of +0.0353%/RH and −0.0245%/RH, respectively. Furthermore, the study identified a critical turning point in ambient relative humidity (50% RH), which significantly alters the degree of hydration (Ca/Si ratio) of the concrete. The research results may provide theoretical and technical support for cracking risk assessment and crack control throughout the entire life cycle of concrete thin-walled structures. Full article

Lithium-ion batteries (LIBs) are pivotal for energy storage in electric vehicles and renewable systems, but how to effectively monitor their conditions and ensure their operational reliability is still a concern today. This study employs electrochemical impedance spectroscopy (EIS) to systematically investigate the evolution of impedance characteristics in nickel–cobalt–manganese oxide (NCM) lithium-ion batteries (LIBs) under varying states of charge (SOCs), states of health (SOHs), temperatures, and mechanical compression displacements. Results reveal that higher SOC and temperature reduce impedance by enhancing ion kinetics and interfacial activity, with $R_{ct}$ (charge transfer resistance) exhibiting a U-shaped dependence on SOC, minimized at 40–60%. As SOH declines from 100% to 80%, $R_{SEI}$ (SEI film resistance) and $R_{ct}$ increase progressively, reflecting SEI thickening and electrode degradation. Mechanical compression (0–8 mm) elevates all resistances, particularly $R_{ct}$ at high SOC, due to structural deformation and hindered diffusion. DRT (distribution of relaxation times) spectra highlight amplified low-frequency peaks with aging and low SOC, underscoring diffusion limitations. These findings elucidate multi-scale failure mechanisms, from interfacial polarization to structural instability, providing a framework for non-invasive health monitoring and lifetime prediction. Full article

Background: Low cardiac output syndrome (LCOS) is a significant cause of postoperative morbidity and mortality in children with congenital heart disease. Prophylactic levosimendan is increasingly used to prevent LCOS, but its superiority to other strategies remains unproven. Based on the pharmacokinetics of levosimendan, we hypothesize that preoperative administration is beneficial for preventing LCOS in a specifically at-risk population. Methods: This is a retrospective single-center cohort study in a tertiary pediatric intensive care unit. All patients under one year of age undergoing surgery for congenital heart disease using cardiopulmonary bypass and receiving levosimendan within 24 h before or after surgery were included and classified into two groups: preoperative and postoperative administration. Results: Overall, 107 patients were included. Fifty-three patients (49.5%) received levosimendan before surgery, with significantly lower mortality, fewer LCOS markers, and lower LCOS scores compared to patients receiving levosimendan after surgery. Although not significant, the use of extracorporeal membrane oxygenation, renal replacement therapy, and temperature control was also lower in the preoperative group. There was no difference in mechanical ventilation duration and length of stay. Conclusions: Preoperative administration of levosimendan seems associated with a lower incidence of LCOS and reduced mortality in high-risk children with congenital heart surgery. Full article

With the expansion of global oil and gas resource exploration and development into deep and ultra deep layers, the efficient development of deep carbonate rock fracture cave reservoirs has become the key to ensuring energy security. However, this type of reservoir commonly faces high temperatures, high salinity, and extremely strong heterogeneity, leading to increasingly severe water content spikes caused by dominant water flow channels. Although the existing traditional inorganic plugging agent has good temperature resistance, it has the defects of great brittleness and easy cracking, while the organic polymer gel is prone to degradation failure under high temperature and high salt environments. In order to solve the above problems, a new biochar-enhanced inorganic composite gel system was constructed by using biochar prepared from agricultural and forestry waste pyrolysis as a functional enhancement component. Through rheological testing, high-temperature and high-pressure mechanical experiments, long-term thermal stability evaluation, and dynamic sealing experiments of fractured rock cores, the reinforcement and toughening laws and rheological control mechanisms of biochar on inorganic matrices were systematically studied. Research has found that a biochar content of 0.5 wt% can significantly improve the micro pore structure of the matrix. By utilizing its micro aggregate filling effect and interfacial chemical bonding, the compressive strength of the solidified body can be increased to over 2 MPa, and there is no significant decline in strength after aging at 130 °C for 30 days. More importantly, the unique “adsorption slow-release” mechanism of biochar effectively stabilizes the hydration reaction kinetics at high temperatures, extending the solidification time of the system to 15 h and solving the problem of flash condensation in deep well pumping. This system exhibits excellent shear thinning characteristics and crack sealing ability, and presents a unique “yield reconstruction” toughness sealing feature. This study elucidates the multidimensional strengthening mechanism of biochar in inorganic cementitious materials, providing technical reference for stable oil and water control in deep fractured reservoirs. Full article

This study systematically investigates the synergistic effects of the pre-stretching deformation and aging temperature on the precipitation behavior and mechanical properties of an Al-Cu-Li alloy. The results indicate that increasing the pre-stretching deformation significantly refines and increases the number density of T₁ and θ′ phases while optimizing the grain boundary precipitate morphology, thereby enhancing the fracture toughness and fatigue resistance without compromising the high strength. In contrast, elevating the aging temperature promotes the coarsening of the T₁ phase, inhibits θ′ precipitation, and coarsens the grain boundary precipitates, leading to a deteriorated damage tolerance. By matching 3.5~4.5% pre-stretching with 145~155 °C aging, a synergistic optimization of ultra-high strength and damage tolerance can be achieved. Full article

Radio Frequency Fingerprinting (RFF) would be a promising Physical Layer Security (PLS) solution for the Internet of Things (IoT) that requires robust, low-overhead security techniques. However, practical implementation of RFF may pose challenges, in particular, performance instability and ethical-regulatory conflicts. Based on authors’ previous research, this paper elaborates these challenges in potential deployment of a resilient and compliant RFF system. First, we analytically show how hardware-induced feature drift, primarily driven by device aging and temperature variations, degrades RFF performance. We then critically survey existing temperature variation and aging models, one of which is being studied by one of the authors’ research team. We look into this from a purely hardware-design perspective, and then compensation methods for an RFF perspective. This reveals a significant gap: current techniques are insufficient to maintain the long-term, high-accuracy RFF for real-world IoT security requirements. Finally, we introduce inherent privacy risks by enabling device tracking. This property conflicts with General Data Protection Regulation (GDPR) mandates, raising significant regulatory challenges and privacy risks. Overall, this work highlights the key technical and legal challenges that must be addressed for RFF to evolve into a robust, privacy-compliant and deployable security primitive for IoT and future wireless systems. Full article

In this study, the tensile properties, low-cycle fatigue behavior, and microscopic fatigue-failure mechanisms of 316H stainless steel in the temperature range of 600–800 °C were systematically investigated by means of tensile tests, high-temperature low-cycle fatigue tests, and scanning electron microscopy (SEM) analysis of fatigue fracture surfaces. Based on experimental data fitting, a life prediction model for the material in the high-temperature regime was established. The results indicate that the mechanical behavior of 316H stainless steel under both static and cyclic loading is significantly influenced by temperature and strain amplitude. Compared with its room-temperature properties, at 800 °C, the elastic modulus of 316H stainless steel decreases by approximately 30%, the tensile strength drops by about 60%, while the elongation after fracture increases by roughly 100%. Within the temperature range of 600–800 °C, the fatigue performance deteriorates with the increasing temperature, and the cyclic hardening rate accelerates as the temperature rises. The fracture mode in the instantaneous fracture zone of the fatigue fracture surface transitions from predominantly transgranular fracture to a mixed mode of transgranular and intergranular fracture as the temperature increases to 800 °C. Under higher strain amplitudes (around 0.6%), 316H stainless steel exhibits Masing behavior and dynamic strain aging (DSA). Correspondingly, the crack-initiation mode on the fatigue fracture surface shifts from a single surface source to multiple surface sources. A three-parameter model was employed to fit the strain–amplitude versus fatigue–life relationships of 316H stainless steel in the 600–800 °C range, showing good agreement with the experimental data, with most data points falling within a factor-of-two error band. Full article

In recent decades, ion-adsorption-type rare earth element (iREE) deposits have been widely documented in the weathering crusts of granitic and volcanic rocks and their geological characteristics and genetic mechanisms extensively studied. Ion-adsorption-type REE mineralization was documented for the first time in the weathered crust overlying the epimetamorphic rocks in Ningdu County, China. In contrast to well-documented granite-derived weathering profiles, investigations of epimetamorphic rocks as protoliths for such REE deposits remain limited, particularly regarding the mineralogy of REE-bearing phases and the geochronology and geochemistry of their parent rocks. To address this gap, the present study combines comprehensive petrographic and mineralogical analyses of REE-mineralized Shenshan Formation phyllites with the U–Pb dating of zircon and apatite and trace element geochemical investigations. U–Pb zircon and apatite geochronology yields a protolith age of ca. 785 Ma for Shenshan Formation metamorphic rocks, consistent with mid-Neoproterozoic magmatism. REE-bearing minerals in the Shenshan Formation phyllites comprise allanite-(Ce), apatite, cerianite-(Ce), monazite-(Ce), rhabdophane-(La), rutile, Y-bearing thorianite and xenotime-(Y). Among these, apatite is the most abundant and likely the principal source of ionic REEs in the deposit. Ti-in-zircon thermometry indicates crystallization temperatures of 641–749 °C (mean ~704 °C), reflecting a prolonged magmatic–hydrothermal evolution. This extended history chiefly controlled the differentiation and redistribution of rare earth elements (REEs), thus governing their availability for subsequent supergene enrichment. Zircon-based oxygen fugacity (fO₂) estimates a range from −31.4 to −9.9 (mean −17.9), consistent with reduced magmatic conditions. Trace element correlation diagrams for zircon and apatite indicate that the intrusion underwent an extensive fractional crystallization of accessory phases (zircon, monazite, apatite, titanite, rutile) and plagioclase. The distribution patterns of trace elements further suggest that the Shenshan Formation protolith formed in a continental margin arc or arc-related orogenic belt setting, with geochemical signatures characteristic of an S-type granite. The Shenshan Formation phyllites in southern Jiangxi exhibit high REE abundances and host a labile assemblage of weatherable REE-bearing minerals, providing an optimal material framework for ion-adsorption-type REE deposits and indicating substantial mineralization potential. Full article

Background: Young adulthood represents a critical period for the emergence of early metabolic disturbances, potentially influenced by dietary shifts toward convenience and ultra-processed foods. However, evidence linking dietary patterns and cooking practices with objective metabolic biomarkers in Romanian university students remains limited. Methods: This cross-sectional study included 693 students aged 18–24 years at the Victor Babeș University of Medicine and Pharmacy, Romania (June–July 2025). Dietary habits, food preferences, and cooking practices were assessed using a structured online questionnaire, while anthropometric and biochemical data were obtained from university health records. The primary outcome was glycated hemoglobin (HbA1c), a marker of average blood glucose levels over the previous 2–3 months. Prediabetes was defined as HbA1c 5.7–6.4%. Dietary patterns were identified using k-means clustering based on fast-food consumption frequency, main meal of the day, fruit and vegetable intake frequency, and predominant cooking method. Multivariable regression models assessed associations between dietary variables and glycemic or lipid outcomes. Results: Prediabetes prevalence was 21.1% (diabetes: 1.4%). Three dietary patterns were identified: health-conscious (prediabetes 15.4%), mixed (20.0%), and fast-food oriented (27.3%; χ² p = 0.003). Fast-food consumption frequency was independently associated with higher prediabetes risk (OR = 1.78 per category; 95% CI 1.38–2.30; p < 0.001) and higher HbA1c levels (β = 0.147; p < 0.001), while fruit and vegetable intake showed an inverse association with HbA1c (β = −0.109; p < 0.001). A dose–response relationship was observed between fast-food frequency and both HbA1c and prediabetes prevalence (p-trend < 0.001). An interaction between high-temperature cooking methods and frequent fast-food consumption was observed for HbA1c (p = 0.023). BMI and sex were the strongest predictors of lipid outcomes, although fast-food intake was associated with higher triglyceride levels (p = 0.034). Conclusions: Among Romanian university students, dietary patterns characterized by frequent fast-food consumption were associated with higher HbA1c levels and greater prediabetes prevalence. A high-temperature cooking method was associated with higher glycemic levels when combined with frequent fast-food intake. These findings suggest that early dietary behaviors during university years may be relevant for metabolic risk profiles in young adults. Full article

The commercialization of V-based catalysts for the selective catalytic reduction of NOx by NH₃ (NH₃-SCR) is hindered by their narrow operating temperature window, insufficient low-temperature (LT) activity, and severe SO₂-to-SO₃ oxidation. To bridge this gap, we herein introduced Nb and hexagonal BN into a VW/TiO₂ system to simultaneously enhance its LT SCR activity, suppress undesired side reactions, and improve durability. Nb incorporation promoted V⁵⁺/V⁴⁺ redox cycling and enhanced lattice oxygen mobility, thus reducing the apparent activation energy and suppressing SO₂ oxidation at elevated temperatures. However, excessive Nb loading induced NH₃ oxidation and N₂O formation. This drawback was mitigated by introducing BN as a dispersion promoter, which helped secure high catalytic performance at a reduced Nb content. The VWNb/Ti-BN catalyst achieved superior NOx conversion and N₂ selectivity over a wide temperature range and benefited from notably suppressed NH₃ oxidation and SO₂-to-SO₃ oxidation. Kinetic analysis revealed that Nb primarily lowered the reaction energy barrier via redox property enhancement, whereas BN accelerated surface reaction turnover by stabilizing and dispersing active acidic sites, markedly increasing the turnover frequency without reducing the activation energy. In situ spectroscopic analysis confirmed the accelerated consumption of adsorbed NH₃ species and enhanced formation of reactive NOx intermediates, indicating SCR pathway enhancement. After aging in the presence of SO₂ and H₂O, the best-performing honeycomb-type monolithic catalyst retained and NOx conversion of >80%, demonstrating excellent long-term durability under practical conditions. A composition-aware machine learning model based on log-ratio-transformed variables quantitatively identified the synergistic balance among V, Nb, W, BN, and TiO₂ as the dominant factor governing LT SCR performance. Thus, this work provides valuable mechanistic insights and a strategy for designing wide-temperature-window SCR catalysts with improved activity, selectivity, and resistance to sulfur poisoning. Full article

In this study, 1.5Y-2.2Ca-TZP materials were obtained by hot pressing of a mixed and milled blend of 3Y-TZP and 4.4Ca-TZP powders. The materials were sintered at temperatures between 1250 °C and 1400 °C and characterized with respect to mechanical properties, microstructure, phase composition and stability against low-temperature degradation. In the tested range, the bending strength of the TZP decreases with increasing sintering temperature from 1300 MPa to 1050 MPa while the toughness shows a rising trend from 5 MPa√m to 8 MPa√m. The grain size distribution in the microstructure is broad with average grain sizes increasing from 150 nm to 250 nm with rising sintering temperature. LTD tests revealed high aging resistance for TZP sintered at 1300 °C. The Y-Ca-co-stabilized TZP equilibrates the properties of Ca-TZP and Y-TZP. Full article