Search Results (11,202)

The plugging of fractured gas reservoirs with severe lost circulation during oil and gas drilling and production has long been challenged by technical issues such as low plugging strength and short effective duration. This paper reports the preparation of a high-strength supramolecular gel plugging agent via micellar copolymerization based on the synergistic effects of hydrophobic association and hydrogen bonding. Systematic optimization determined the optimal synthesis formula: acrylamide (AM) 12%, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) 2%, stearyl methacrylate (SMA) 0.4%, sodium dodecyl sulfate (SDS) 1.5%, and potassium persulfate 0.3%, with a reaction temperature of 60 °C. Performance evaluations revealed that the gel possesses a controllable gelation time (120 min) and excellent viscoelastic recovery properties. At a compressive strain of 87%, the compressive stress reached 1.43 MPa while maintaining structural integrity. Swelling behavior analysis indicated that the gel follows a non-Fickian diffusion mechanism, with its swelling process governed by the synergistic interplay of water molecule diffusion and polymer network relaxation. Core plugging experiments demonstrated that the gel achieved plugging efficiencies exceeding 95% for cores with permeabilities ranging from 0.18 to 0.90 μm², with a maximum breakthrough pressure gradient of up to 11.48 MPa/m. These results highlight the gel’s efficient and broad-spectrum plugging capability for fractured lost circulation zones. This preliminary study provides experimental foundations for the material design and performance optimization of supramolecular gel-based long-lasting plugging agents for severe lost circulation gas reservoirs, and further field-scale validation is required for engineering application. Full article

Transparent heaters intended for skin-contacting applications must simultaneously satisfy optical transparency, mechanical compliance, thermal uniformity, and operational safety under biologically relevant temperature ranges. Here, we evaluate the applicability of a TiO₂/Ag/SiO₂ (TAS) dielectric–metal–dielectric transparent heater as a functional biomaterial platform for wearable and skin-integrated thermal systems. By systematically optimizing each layer thickness of the TAS structure, the heater achieves high visible-light transmittance (average of 86.6%) together with low sheet resistance on the order of 7.7 Ω/sq for low-voltage operation. The TAS heater demonstrates rapid and reproducible Joule-heating behavior, showing fast thermal response with short thermal time constants and spatially homogeneous temperature distributions without localized hot spots. Stable electrothermal performance is maintained under repeated on/off cycling and during cyclic mechanical bending down to small radii, confirming excellent mechanical stability under repeated bending relevant to wearable applications. Importantly, direct on-skin evaluations conducted by attaching the device to a human elbow reveal conformal contact, uniform heating at therapeutically relevant temperatures (50–70 °C), and stable operation under dynamic bending and extension. The absence of thermal inhomogeneity during motion highlights the intrinsic stability of the TAS architecture for skin-interfaced use. Given the high optical visibility, mechanical compliance, thermal uniformity, and electrothermal stability, the proposed TAS architecture represents a promising functional biomaterial platform for wearable thermotherapy, skin-mounted healthcare devices, and human-interactive thermal systems operating under continuous mechanical deformation and direct skin contact. Full article

Well spacing and reinjection rate are two critical parameters controlling the efficiency and sustainability of hot dry rock geothermal development. Taking the Yangbajing geothermal field in Tibet as the geological setting, permeability experiments were conducted on fractured rock masses under multiple operating conditions, and a three-dimensional fully coupled thermo-hydro-mechanical numerical model was established to systematically evaluate the effects of different well spacing–reinjection rate combinations on heat extraction performance. The experimental results show that axial stress is the dominant factor governing specimen deformation and seepage characteristics. Permeability decreases with increasing axial stress, exhibiting an initial sharp decline followed by a gradual reduction. The effect of temperature varies with axial stress level. Under low to moderate axial stress, permeability decreases monotonically with increasing temperature, whereas under high axial stress, it first decreases and then increases. The simulation results indicate that the production temperature remains relatively stable during the early stage of exploitation and subsequently declines, with the rate of decline increasing significantly as the reinjection rate increases or the well spacing decreases. In addition, an exponential positive relationship is identified between well spacing and the optimal reinjection rate. When a 10% decline in production temperature is adopted as the shutdown criterion, the optimal reinjection rate increases from 60 m³/h to 150 m³/h as the well spacing increases from 500 m to 800 m. Based on the simulation results, the theoretical installed capacity of the first deep reservoir in the Yangbajing geothermal field is preliminarily estimated to reach 31.8 MW. Full article

2219 aluminum alloy is widely used in aerospace components because of its high specific strength, excellent fracture toughness, and resistance to stress corrosion cracking. Accurate characterization of its hot deformation behavior is important for the numerical simulation and process design of ring rolling. In this study, isothermal compression tests were carried out on a thermal–mechanical simulator at temperatures of 380–460 °C and strain rates of 0.01–10 s⁻¹ to investigate the hot deformation behavior of 2219 aluminum alloy. The effects of deformation temperature and strain rate on flow stress evolution were analyzed based on the experimental results. A strain-compensated Arrhenius-type constitutive model was developed to describe the flow stress behavior over a wide strain range. The material constants, including the stress exponent, stress level parameter, activation energy for hot deformation, and structure factor, were determined by regression analysis, and their strain dependence was expressed as polynomial functions of true strain. The model was evaluated by comparing predicted and experimental flow stress values, giving an average absolute error of 4.78%. The results indicate that the developed model can describe the combined effects of temperature, strain rate, and strain with good accuracy, and can be used for numerical simulation and process optimization in hot ring rolling. Full article

Urban areas in arid environments are increasingly affected by the urban heat island (UHI) effect, which intensifies thermal stress, disrupts ecological balance, and poses challenges for sustainable urban development. Understanding and predicting spatiotemporal variations in land surface temperature (LST) and land use dynamics is therefore critical for effective urban planning. This study develops a predictive framework for Riyadh, Saudi Arabia, using long-term Landsat time series data (1993–2023) and deep learning models to evaluate urban thermal patterns via the Urban Thermal Field Variation Index (UTFVI). Artificial Neural Networks (ANNs) with six hidden layers for LST and seven for UTFVI forecast future trends up to 2043. The results indicate that urban areas expanded by 521.62 km², increasing from 8.73% to 19.56% between 1993 and 2023, and are projected to reach 1509.40 km² (25.28%) by 2043, while vegetation coverage declined from 0.771% to 0.674%. The highest average summer LST increased from 56.73 °C in 1993 to 59.89 °C in 2023 and is predicted to rise to 60.79 °C by 2033 and 61.52 °C by 2043. Winter temperatures exhibited a comparable upward trend, rising from 30.75 °C to 32.33 °C in 2023 and projected to reach 34.48 °C by 2043. UTFVI analysis revealed a substantial expansion of weak thermal field zones, which covered 2778 km² in 2023 and are expected to reach 3018.44 km² (57%) by winter 2043, accompanied by a marked contraction of strong thermal field areas. The ANN models achieved a high predictive performance, with RMSE values of 0.759 (summer) and 0.789 (winter) for UTFVI and correlation coefficients of 0.91 and 0.89, respectively. Projections further indicate that, by 2043, approximately 39.31% of the study area will experience summer temperatures between 48 °C and 53 °C, compared to 5.59% in 2023. These findings highlight the accelerating interaction between urban growth and thermal intensification in arid cities. The proposed modeling framework provides a robust decision-support tool for urban planners and policymakers to mitigate UHI impacts and promote climate-resilient and sustainable urban development. Full article

In fundamental physics, sensors operating below liquid helium temperatures are highly vulnerable to vibrations, which can affect the sensitivity, for example, of high-performance particle detectors. Pulse-tube refrigerators, while generating vibrations lower than those of conventional systems, may still introduce several disturbances. Hence, flexible thermal connections are a commonly used mechanical solution to mitigate these undesirable effects. Among the materials that can be used, ultra-high-purity aluminum (UHP-Al) has attracted the attention for low-amplitude-vibration cryogenic applications, including gravitational wave interferometry, quantum information systems, precision space instrumentation, and cryogenic resonators. Thus, the aim of the paper is the characterization of the mechanical and microstructure properties of three UHP-Als (i.e., 5N—99.999 wt%, 5N5—99.9995 wt% and 6N—99.9999 wt%) intended for the production of thermal flexible connections with low stiffness, specifically designed to reduce vibration transmission in cryogenic environments. Mechanical properties were evaluated through standard tensile tests from room (+25 °C) to low temperature (i.e., −150 °C), providing insights into yield strength, ultimate tensile strength, elongation and elastic modulus. In addition, the dynamic elastic modulus of material loads, at cryogenic conditions (i.e., about −180 °C), was determined by measuring the natural resonance frequency, thereby assessing the material’s response to vibrational. Moreover, an extensive microstructural analysis was conducted using electron backscatter diffraction and x-ray diffraction. The correlation between the observed microstructure and the elastic properties was systematically examined. The results underscore the pivotal role of microstructural characteristics in dictating the elastic behavior of UHP Als. Eventually, the analysis provides valuable guidelines for the materials employment inside cryogenic systems, where severe vibration control is critical to maintain high operational performance. Full article

Satellite remote sensing increasingly supports water quality monitoring, yet the temporal transferability of machine learning (ML) models remains insufficiently tested, particularly in coastal shallow lakes subject to hydrological variability. This study evaluates the predictive robustness of satellite-based ML models for electrical conductivity (EC), turbidity (TUR), water temperature (WT), and dissolved oxygen (DO) in Vrana Lake, Croatia. A total of 409 in situ measurements collected during 2023–2024 and 2025 were paired with Sentinel-2 and Landsat 8–9 imagery. Pearson, Spearman, and Kendall correlation analyses were applied for parameter-specific band selection using original, inverse, quadratic, and logarithmic feature transformations. Seventeen regression algorithms were evaluated under six training–testing split strategies, including strict temporal projection. WT exhibited high robustness (R² ≈ 0.90 under temporal projection) due to its strong dependence on thermal bands, while DO achieved moderate temporal stability (R² = 0.51) using log-transformed predictors. EC and TUR demonstrated substantial performance degradation under temporal separation (R² = 0.14 and −4.62, respectively), reflecting sensitivity to distribution shifts. For parameters showing sufficient stability, interpretable band-based retrieval equations were derived using the most strongly correlated spectral predictors. These findings highlight the importance of temporally structured validation and demonstrate that model complexity does not guarantee operational robustness in shallow, dynamically evolving lake systems. Full article

Psocids are difficult to manage using insecticides, hence the need for alternatives including biological control. Evaluation of data from two separate studies was conducted. One study investigated the potential of Cheyletus eruditus (Shrank) (Trombidiformes: Cheyletidae) and Cheyletus malaccensis Oudemans to manage Liposcelis decolor (Pearman) (Psocodea: Liposcelididae), whereas the other investigated the potential of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) to do the same. Temperature and relative humidity conditions were similar in both studies. However, the five predator–prey (P-P) ratios for the mites (0:20, 1:20, 2:20, 4:20 and 10:20) were different from those of X. flavipes (0:240, 1:240, 2:240, 3:240 and 5:240). The three predators demonstrated significant prey suppression; however, the level of control by X. flavipes was higher compared to the mites. At optimal prey conditions of 32 °C and 75% RH, all predators maintained high suppression. Temperature significantly influenced progeny production, with high reproduction observed at 20 and 24 °C for the Cheyletus spp. and at 28 and 32 °C for X. flavipes. Relative humidity of 63% was detrimental to Cheyletus spp. progeny production. While the results from this evaluation for the purpose of comparison should be interpreted cautiously, the different performances of the predators provide valuable insights for biological control of stored-product psocids. Full article

As a promising solution to lubrication failure in space environments where conventional oils suffer from splashing and leakage, magnetic fluids (MFs) offer significant potential. This study synthesized a perfluoropolyether (PFPE)-based MF tailored for space applications, demonstrating low-temperature fluidity at −40 °C, low saturated vapor pressure (3.37 Pa at 75 °C), and high stability (>6 months). To evaluate its lubrication effect, four magnetic thrust ball bearing structures were designed, with magnetic fields optimized via simulation. A magnetic field-controllable lubrication test bench was constructed accordingly. Comparative tests under varying friction conditions revealed that MF lubrication extended bearing service life. Specifically, the bearings lubricated with 7.5 wt.% MF exhibited the longest service life, which was doubled compared to the service life of the bearings lubricated with the carrier liquids. When compared to bearings without the application of a magnetic field, the service life of bearings lubricated with MFs of the same mass fraction increased by a factor of 3 to 4. This initial finding suggests the viability of using MFs in space lubrication applications. Full article

To address the challenges of rapid water loss and insufficient long-term inhibition efficiency of conventional inhibitors in the high-temperature environments of deep goafs, a novel, environmentally friendly Deep Eutectic Inhibitor (DEI) was synthesized. This DEI utilizes citric acid (Ca) and proline (Pr) as the hydrogen bond donor and acceptor, respectively, with ascorbic acid (VC) and propyl gallate (PG) serving as antioxidants. A moisture retention evaluation model based on Fick’s law of diffusion was established to systematically investigate the liquid-domain stability of the DEI across a temperature range of 30 °C to 120 °C. The results demonstrate that the DEI exhibits superior moisture retention capabilities under high-temperature conditions, with the relative moisture retention peaking in the 80–110 °C range. Mechanistically, the formation of a robust hydrogen bond network effectively counteracts moisture evaporation driven by thermal kinetic energy. Furthermore, the DEI demonstrated significant inhibition effects on four coal samples with varying degrees of metamorphism. Tests on oxidative heat release characteristics revealed that DEI treatment delayed the initial oxidation temperature of the coal. Kinetic analysis further indicated that during the critical oxidation stage (200–300 °C), the apparent activation energy of the treated coal samples increased by 10.28–18.9 kJ/mol, effectively suppressing the spontaneous combustion process. This study contributes to the development of high-efficiency and eco-friendly fire prevention materials for coal mines. Full article

High-concentration carbon monoxide (CO) produced by incomplete methane combustion in underground explosions is the primary cause of post-explosion fatalities, with typical concentrations (2–4%) far exceeding human tolerance limits. Unsupported Co₃O₄ catalysts were synthesized via a hydrothermal route and evaluated for post-explosion CO elimination under realistic mine-atmosphere conditions. The phase-pure spinel catalyst (crystallite size ~18 nm, S_BET = 68.5 m²/g) exhibited exceptional low-temperature activity with T₅₀ = 43 °C and T₉₀ = 59 °C under 10% O₂, and an apparent activation energy of 63 kJ/mol, substantially outperforming commercial Hopcalite (T₅₀ = 95 °C). In 20 L explosion vessel tests simulating 11% CH₄ combustion at a catalyst loading of 200 g/m³, CO was reduced from 2.85% to 0.32% (89% reduction), extending the escape time factor to k_es = 1.62. Continuous operation at 70 °C for 120 h maintained CO conversion above 96%, and three consecutive explosion cycles produced only a modest ~2% decline in activity, with post-test XRD confirming retention of the spinel phase. Mechanistic studies combining in situ DRIFTS and CO-TPD identify a Mars–van Krevelen pathway driven by surface Co³⁺ sites and reactive lattice oxygen. Full article

Heat stress is a significant problem in dairy production that has detrimental effects on milk production, animal well-being and reproductive function. These effects are predicted to worsen due to climate change. With a focus on South African production systems, this review assesses the potential of combining precision livestock farming (PLF) and genomic selection (GS) technology to identify, measure and reduce heat stress in dairy cattle. In addition to PLF tools like wearable sensors, rumen boluses, infrared thermography, GPS- and weather-based decision-support systems, pertinent literature was reviewed to evaluate genomic approaches such as heritability estimates and genome-wide association studies identifying selection signatures for thermotolerance. While advances in genomic techniques have improved the identification of thermotolerance markers and the accuracy of breeding values for heat tolerance, evidence from recent studies shows that PLF technologies can accurately detect early physiological and behavioural indicators of heat stress in real time. The ability to select climate-resilient animals under realistic farm conditions is improved by combining high-resolution phenotypic data from PLF systems with genetic data. Overall, the review concludes that combining PLF and GS provides a useful and complementary approach to enhance the detection of heat stress, facilitate well-informed management choices and hasten the development of thermotolerant dairy cattle, all of which contribute to more sustainable dairy production under rising temperatures. Full article

A detailed numerical optimization of side-pumped cerium- and neodymium-codoped yttrium aluminum garnet (Ce:Nd:YAG) solar laser architectures was performed using Zemax^® and LASCAD^TM, aiming for both high-power multimode and TEM₀₀-mode performances. Multiple rod configurations and laser resonator geometries were evaluated to maximize absorbed pump power, improve mode overlap, and ensure thermal stability. For multimode operation, the optimal design was a four-rod cross side-pumped configuration employing 4.0 mm diameter, 25 mm length rods, which numerically delivered a solar laser output power of 134 W (resulting in a collection efficiency of 49.1 W/m² and solar-to-laser conversion efficiency of 4.91%), representing a 1.50-times improvement over the best previously reported value of 89.29 W. For TEM₀₀-mode generation, the best performance was obtained with a three-rod horizontal side-pumped configuration using 2.5 mm diameter, 34 mm length rods, achieving a collection efficiency of 21.1 W/m² and solar-to-laser conversion efficiency of 2.11%, surpassing the record 16.49 W/m² reported in earlier literature. Thermal analyses revealed low peak temperatures, reduced thermally induced stress, and minimized refractive-index gradients in both architectures, confirming that multirod side pumping significantly improves the thermal environment and enables stable operation at high absorbed pump powers. These results demonstrate that carefully engineered multirod geometries can simultaneously enhance collection efficiency, beam quality, and thermal robustness, highlighting multirod side-pumped solar lasers as a promising pathway for further power scaling and next-generation high-performance solar laser systems. Full article

Reverse osmosis concentrate (ROC) contains relatively high levels of refractory organic pollutants, posing significant challenges due to its difficult treatment and high environmental risks. Therefore, efficient and convenient removal strategies are essential. In this study, a self-developed iron-modified activated carbon fiber (Fe-ACF) was employed as an adsorbent to remove organic pollutants from ROC. Additionally, response surface methodology (RSM) was applied to model the adsorption process, identify and evaluate key influencing parameters, and optimize operational conditions. The adsorption mechanisms and regeneration stability of Fe-ACF were also investigated. Kinetic analysis revealed that the adsorption process is predominantly governed by chemisorption, with intraparticle diffusion identified as the primary rate-limiting step. Isothermal adsorption studies demonstrated that the Langmuir–Freundlich model best describes the adsorption behavior, yielding a theoretical maximum adsorption capacity of 12.21 ± 0.80 mg/g. Thermodynamic analysis confirmed that the adsorption process is spontaneous, endothermic, and driven by an increase in entropy. The RSM optimization identified pH as the dominant factor. The optimal adsorption conditions were a pH of 4.18, a temperature of 34.63 °C, a stirring speed of 547.91 rpm, and an adsorbent dosage of 1.55 g/L. The adsorption mechanism involves hydrogen bonding, π–π interactions, surface complexation, and electrostatic forces. Fe-ACF exhibits competitive regeneration stability and structural integrity. In summary, Fe-ACF demonstrates significant potential as a treatment material for ROC. Full article

Copper oxide nanoparticles (CuONPs) have received considerable attention because of their wide range of applications, particularly in the development of antimicrobial materials for medical, environmental, and industrial purposes. However, conventional synthesis routes often involve the use of toxic chemicals and environmentally harmful conditions. To overcome these limitations, green synthesis strategies have been developed as sustainable alternatives through the use of natural reducing and stabilizing agents. In this study, Citrus sinensis leaf extract, which exhibits high antioxidant capacity, was investigated for green synthesis of CuONPs, followed by their subsequent incorporation into a chitosan polymeric matrix. The optimal synthesis conditions were achieved at a pH of 7.0 using copper(II) acetate monohydrate (Cu(CH₃COO)₂·H₂O) at a concentration of 10.0 g L⁻¹ and a calcination temperature of 300 °C. The resulting CuONPs exhibited a heterogeneous morphology, with average particle sizes ranging from 20 to 30 nm, and demonstrated satisfactory antimicrobial activity against Escherichia coli and Staphylococcus aureus. The incorporation of these NPs into chitosan yielded composite materials with enhanced antimicrobial performance, highlighting the added value of polymer–NP hybrid systems. Although these composite materials were not evaluated under realistic operational conditions, the optimized green protocol provides a robust methodological basis for future studies targeting water disinfection and other environmentally relevant technologies. Full article