Search Results (5,428)

Nanostructured Co₃O₄ was synthesized via a sol–gel approach employing the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]TfO) and subsequently evaluated as a high-performance anode material for lithium-ion batteries. Ionic liquids, distinguished by their low volatility, high thermal stability, and tunable chemical properties, represent a greener alternative to conventional organic solvents for the synthesis of functional nanomaterials. The electrochemical performance of the as-prepared material was systematically assessed through galvanostatic charge–discharge cycling, cyclic voltammetry, and rate capability tests. The Co₃O₄ electrode exhibited a high reversible capacity of approximately 1100 mAh g⁻¹ after 50 cycles at a current density of 200 mA g⁻¹, along with excellent coulombic efficiency approaching ~100% after the initial cycles. Furthermore, the material demonstrated strong rate capability, delivering about 600 mAh g⁻¹ at 1 C, and recovering its capacity upon returning to lower current densities. The improved electrochemical performance is primarily attributed to the nanoscale architecture induced by the ionic liquid-assisted synthesis, which facilitates rapid lithium-ion transport and effectively buffers volume variations during repeated cycling. Notably, the ionic liquid serves a dual function as both a green reaction medium and a structure-directing agent, enabling precise control over the material’s morphology and properties. This study demonstrates a versatile strategy for the rational design of potential transition-metal oxide anodes, paving the way for high-performance electrode materials. The findings contribute to the development of next-generation lithium-ion batteries tailored for clean and sustainable energy storage applications. Full article

Pearlitic wheel steel subjected to thermal–mechanical fatigue (TMF) during braking can undergo catastrophic fracture. This study clarifies the microstructural evolution governing the macroscopic cyclic hardening/softening behavior of pearlitic wheel steel under thermal–mechanical fatigue (TMF) with a constant mechanical strain range of −0.4% to +0.2%. At lower temperature amplitudes (200–500 °C), the geometrically necessary dislocation (GND) density reaches 20.4 × 10¹⁴/m² during initial cycles, corresponding to cyclic hardening due to dislocation pile-ups at cementite lamellae interfaces. With increasing cycles, the GND density decreases to 12.3 × 10¹⁴/m², concurrent with softening arising from lamellar bending/fracture, partial spheroidization, and dynamic recrystallization of ferrite. At higher temperature amplitudes (200–730 °C), the GND density decreases from 8.8 × 10¹⁴/m² to 3.5 × 10¹⁴/m², reflecting sustained cyclic softening dominated by thermally activated mechanisms, including cementite spheroidization and dislocation annihilation. The resulting softened microstructure consists of ferrite grains, intragranular dispersed cementite, and chain-like coarse cementite at boundaries. Unlike previous studies that focused on single loading conditions (e.g., thermal fatigue, rolling contact fatigue, or wear), the present work addresses the more complex TMF scenario and quantitatively elucidates the interplay between mechanical response and microstructural evolution in pearlitic steel. This work provides theoretical guidance for the development of a fatigue life prediction model for pearlitic wheels under braking. Full article

Cod liver oil is a rich source of polyunsaturated fatty acids (PUFAs) but is highly susceptible to oxidative degradation, limiting its use in topical formulations. This study aimed to develop stable cod liver oil nanoemulsions for topical application and to evaluated the influence of surfactant ratio (lecithin/PEG-15 hydroxystearate: 2.5:1 and 1:1, w/w), emulsification method (ultrasonication or high-pressure homogenization), and vitamin E acetate supplementation on their physicochemical properties and oxidative stability. Eight nanoemulsions were characterized in terms of droplet size, polydispersity, ζ-potential, vitamin E acetate encapsulation efficiency, oxidative stability, film-forming capacity and cytocompatibility. Among the investigated formulations, F4 (2.5:1 lecithin/PEG-15 hydroxystearate, high-pressure homogenization, with vitamin E acetate) exhibited the most favorable characteristics, including a mean droplet size of 67.95 nm, ζ-potential of −63.12 mV and vitamin E acetate encapsulation efficiency of 32.59%. The formulation demonstrated good physicochemical stability under thermal, mechanical and photostability testing, improved oxidative stability, transient film-forming behavior with an initial occlusive effect, and no cytotoxicity toward human dermal fibroblasts. These findings indicate that nanoemulsion performance depends on the combined influence of formulation composition and processing conditions, with F4 representing a promising topical carrier for cod liver oil intended for interaction with the stratum corneum. Full article

Maintaining effective fluid-loss control in water-based drilling fluids under coupled high-salinity, high-temperature, and high-density conditions remains a critical challenge in deep and ultra-deep drilling operations. In this study, a low-molecular-weight polymer fluid-loss additive (LM-ASQF) was synthesized via redox-initiated copolymerization of acrylamide, dimethyldiallylammonium chloride, and sodium allyl sulfonate. The synthesis route and proposed polymer structure were further illustrated to clarify the incorporation of amide, quaternary ammonium, and sulfonate functional units within the LM-ASQF molecular architecture. The polymer exhibited a controllable number-average molecular weight of 18.2–29.4 kDa with a unimodal distribution. Thermal analysis confirmed that no main-chain-dominated degradation occurred below 220 °C, indicating structural stability under high-temperature conditions. In drilling-fluid systems containing NaCl, CaCl₂, and mixed salts (0–20%), LM-ASQF maintained stable rheological properties, with apparent viscosity ranging from 26.1 to 41.6 mPa·s, while the API fluid loss was controlled within 5.8–11.2 mL. After thermal aging at 220 °C for 16 h, the API fluid loss remained below 13 mL in both freshwater and mixed-salt systems. In high-density systems (1.80–2.40 g/cm³), the drilling fluids preserved continuous rheological structures and showed no abrupt increase in filtration. Mechanistically, fluid-loss control was primarily attributed to synergistic interfacial adsorption of amide groups, hydration stabilization induced by sulfonate functionalities, and particle rearrangement-driven filter-cake densification, rather than viscosity enhancement through long-chain entanglement. This mechanism enables effective filtration control without excessive viscosity increase, thereby maintaining rheological compatibility under complex conditions. These results demonstrate that the low-molecular-weight design strategy provides a reliable approach for achieving stable fluid-loss control in water-based drilling fluids under high salinity, elevated temperature, and high-density conditions. Full article

In polymer selective laser sintering (SLS), powder acts as a support material during additive manufacturing, generating significant amounts of un-sintered powder exposed to prolonged thermal cycles. Although partial reuse with virgin powder is common practice, material degradation eventually renders the powder unsuitable for further SLS processing. This study investigates a sustainable approach for valorising SLS waste powder through its conversion into filament feedstock for fused filament fabrication (FFF). Polyamide 12 filaments containing 0, 2, 3, and 4 wt.% multi-walled carbon nanotubes (MWCNTs) were produced by twin-screw extrusion to tailor the electrical conductivity of the polymer matrix. The filaments were processed by FFF to manufacture specimens for thermal, mechanical, and electrical characterization. Differential scanning calorimetry revealed the influence of reprocessing on the thermal behaviour of the reused material and resulting filaments, while thermogravimetric analysis demonstrated improved thermal stability with increasing MWCNT content. Tensile testing showed increased Young’s modulus (up to 9.4%), despite an initial drop, and tensile stress at break (up to 56.3%) with Full article

The reliance on a single evaluation parameter represents a major limitation in traditional geothermal reservoir assessment models, hindering accurate and effective evaluation of geothermal extraction performance. Moreover, mechanical deformation induced by cold fluid injection exerts a significant influence on both fluid flow behavior and geothermal energy recovery. In this study, a thermo-hydraulic–mechanical (THM)-coupled single-fracture model is developed based on the physical properties of the solid matrix and the seepage characteristics of the fluid, using a finite-element framework for heat and mass transfer. This model enables a multi-parameter evaluation of geothermal extraction efficiency as well as reservoir rock deformation. The simulation results indicate that reservoir temperature decreases progressively from the injection well to the production well, resulting in a gradual decline in the outlet temperature after an initial stable production period of approximately 200 days. The presence of a preferential “fastest flow path” between the injection and production wells plays a critical role in sustaining the stable production phase, whereas the development of a tongue-shaped isotherm pattern is a primary factor responsible for the reduction in outlet temperature during the later stages of extraction. In addition, thermally induced rock deformation further modifies geothermal extraction efficiency, mainly through its effects on reservoir permeability and top vertical displacement. Overall, this study provides reliable and effective fundamental data for geothermal exploitation in specific geological reservoirs, thereby supporting the role of geothermal energy as a viable supplement to fossil fuel resources. Full article

Population ageing is reshaping the use and evaluation of everyday urban green spaces, especially in old urban districts where nearby public spaces support walking, resting, exercise, and social contact. Conventional age-friendly assessments often emphasise whether formal infrastructure is provided, but facility provision alone does not ensure experiential fit with older adults’ functional capacities, daily routines, and social practices. This exploratory multiple-case study examines user-initiated informal adaptations in three neighbourhood-scale green spaces in Gulou District, Nanjing, China. Facility audits, approximately 30 h of non-participant observation, semi-structured interviews with 36 older users, and 220 valid questionnaires were combined through cross-case coding and qualitative triangulation. Three adaptation types were identified: supplementary, modifying, and appropriative adaptations. These practices were interpreted as context-dependent behavioural signals potentially associated with safety and convenience, ergonomic support and material-thermal comfort, social accessibility and spatial accommodation, and social support. Adaptation patterns varied descriptively across sites and age groups in relation to facility conditions, spatial organisation, activity intensity, and user characteristics. The findings suggest that, when interpreted alongside facility audits, interviews, and site context, older adults’ everyday adaptations may help identify possible mismatches between formal provision and actual use, offering a low-cost interpretative perspective for inclusive, incremental, and socially sustainable green-space renewal. Full article

Polysaccharides-based bioactive films are regarded as a promising strategy to delay fruit spoilage. β-cyclodextrins (CD) was incorporated into pullulan/Astragalus extract (AE) bioactive films (CD-AE-P) to systematically investigate its effect on multi-scale structures features, physicochemical properties, migration behavior, anti-browning efficacy, and aroma substances in sliced apples. With increasing CD content, a slight blue shift was observed in O-H stretching vibration peak; CD-AE-P films retained an amorphous structure, as evidenced by the disappearance of scattering peak at 0.075 < q < 0.25 nm⁻¹, and they exhibited smoother, continuous fractured surfaces with sparsely distributed protrusions. Meanwhile, CD incorporation contributed to the preservation of macromolecular thermal stability and induced an initial increase followed by a decrease in storage modulus (E′), with CD15-AE-P sample exhibiting the highest Tg value. Although the hydrophilicity increased marginally in the films upon adding CD, WVP decreased progressively, reaching a 23.3% reduction in CD25-AE-P relative to CD0-AE-P. Furthermore, total migration from the films was significantly suppressed by CD incorporation, and the anti-browning effect on sliced apples was extended; notably, treatment with CD25-AE-P effectively preserved the aroma substances of sliced apples during storage. These results demonstrate that CD serves as an effective functional carrier to modulate the effective release of bioactive compounds in active food packaging systems. Full article

The presence of pharmaceuticals in treated wastewater has become an environmental concern due to their persistence, biological activity, and incomplete removal in conventional wastewater treatment systems. In this study, a g-C₃N₄/rGO nanocomposite was synthesized via thermal polycondensation of melamine in the presence of reduced graphene oxide and evaluated as a photocatalyst for the degradation of selected pharmaceuticals in membrane bioreactor (MBR)-treated wastewater. The obtained materials were characterized using Fourier-transform infrared spectroscopy (FTIR–ATR), X-ray diffraction (XRD), nitrogen adsorption–desorption measurements (BET), Raman spectroscopy, scanning electron microscopy (SEM), and UV–Vis spectroscopy to evaluate their chemical structure, crystallinity, textural properties, morphology, and optical characteristics. Photocatalytic experiments were performed under UV irradiation using real wastewater spiked with carbamazepine, diclofenac, ibuprofen, and sulfamethoxazole at an initial concentration of 50 mg/L, selected to ensure reliable quantification under laboratory conditions. The complete removal of diclofenac and sulfamethoxazole was achieved within 30 min of treatment, while the presence of the nanocomposite enhanced the degradation efficiency of ibuprofen and carbamazepine by approximately 19% and 13%, respectively, compared to UV irradiation alone. The obtained results demonstrate the applicability of the investigated g-C₃N₄/rGO system for pharmaceutical degradation in real wastewater matrices and indicate its potential as a preliminary photocatalytic post-treatment approach. Full article

Driven by the demand for high-quality housing, fourth-generation residential buildings—known internationally as “Vertical Forest” and in China as “Urban Forest Garden”—have developed rapidly. Initially built in mild southern regions, they have recently expanded to colder northern areas, with over 50 projects underway in provinces such as Shanxi, Hebei, Shaanxi, and Gansu. Several cities have introduced design standards and incentives, and the China Association for Standardization of Engineering Construction has issued the “Design Standards for Urban Forest Garden Housing.” However, in cold regions, where winters are long and cold and summers are short and hot, there is a lack of systematic quantitative research on how balcony design affects building carbon reduction, energy efficiency, and indoor thermal comfort. To address this research gap, this paper poses the following research questions: (1) In fourth-generation residential buildings in cold regions, how do different combinations of balcony orientations affect annual energy consumption and indoor thermal comfort? (2) Which balcony configurations offer the best balance between carbon reduction, energy efficiency, and thermal comfort? Based on statistical analysis of terrace configurations from more than 40 projects, 12 typical configuration models were identified. Using Ladybug and Honeybee tools on the Grasshopper platform, building energy consumption and indoor thermal comfort were simulated. Multi-objective trade-off analysis was performed using the Pareto front method. In this study, indoor thermal comfort was evaluated using the PMV (Predicted Mean Vote) index. PMV is an index proposed by Professor Fanger that comprehensively reflects human thermal sensation, taking into account air temperature, humidity, wind speed, mean radiant temperature, human metabolic rate, and clothing thermal resistance. Its typical range is −3 (cold) to +3 (hot); in this study, the comfort zone was defined as −1 ≤ PMV ≤ 1. Key findings: (1) The southwest + south terrace configuration shows the highest annual energy consumption, exceeding the lowest (northwest + west) by 2.7%, indicating that south-facing terraces are less favorable for carbon reduction. (2) The best thermal comfort is achieved with east, west, and south orientations. Compared to the least comfortable combination (southwest + northwest), the difference in PMV comfort percentage reaches 2.4%. (3) The Pareto front reveals that beyond a certain comfort level, energy consumption increases sharply. The west + south and east + south combinations yield the highest thermal comfort (49.4%) while maintaining relatively low energy consumption (17.98 kWh/m²). Therefore, in cold regions, fourth-generation residential designs should prioritize terrace combinations integrating south-facing and side-facing orientations and avoid pure corner configurations to balance winter solar gain and summer shading. Full article

A simplified design framework for narrowband terahertz thermal emitters based on a resonant Salisbury-type structure is investigated numerically. The structure consists of a metallic backreflector, a dielectric spacer, and a thin resonant layer with a Lorentz-type dielectric response. Using the transfer matrix method, we show that matching the intrinsic resonance of the resonant layer with an interference resonance of the Salisbury structure enables selective enhancement of a single emissivity peak without requiring time-consuming full-wave optimization at the initial design stage. The influence of spacer thickness, refractive index, and resonance strength on the spectral response is analysed, providing simple guidelines for tuning the emission frequency and suppressing parasitic peaks. A realistic implementation based on a graphene metamaterial layer on a silicon spacer is also investigated using finite-element simulations to demonstrate the applicability of the proposed design concept. The obtained emissivity and thermal emission spectra show that the approach can be used for the efficient design of spectrally selective terahertz thermal emitters in the 10–40 THz range. Full article

This work investigates the potential of additive manufacturing (AM) technologies for prototyping and developing functional components in thermal systems, with particular emphasis on thermal and mechanical performance. The study focuses on two complementary prototyping strategies: (i) the use of metal-filled polymer filaments in Fused Deposition Modeling (FDM), also known as Material Extrusion (MEX) according to ISO/ASTM 52900:2022, and (ii) a hybrid approach combining polymer 3D printing with conductive coating and electrochemical copper deposition. While metal-filled filaments provide a rapid and low-cost solution for early-stage prototyping, their mechanical properties remain similar to those of the polymer matrix, limiting their applicability in load-bearing structures. In contrast, the hybrid method enables the fabrication of hollow metallic geometries with improved thermal and electrical conductivity. This approach is more time-consuming and process-intensive and is therefore considered a subsequent stage in the prototyping workflow following initial MEX-based design iterations. Compared with conventional polymer-based MEX, several AM approaches enable the development and fabrication of fully metallic or metal-functional structures, including Powder Bed Fusion (PBF), Directed Energy Deposition (DED), and hybrid polymer–metal methods based on electroplating. Furthermore, understanding mechanical properties such as tensile strength is essential for assessing the applicability of AM materials in energy system components. The results contribute to bridging the gap between rapid prototyping and the implementation of advanced AM technologies in thermal-related applications. Full article

This study presents a numerical investigation of a slit fin-enhanced phase change material (PCM)-based battery thermal management system (BTMS) for an 18650 cylindrical LiNi_xCo_γMnzO₂ lithium-ion battery. The proposed design modifies the conventional solid rectangular external fins by introducing four longitudinal slit fins with uniformly distributed rectangular through-thickness slot cutouts along the fin height. This modification increases the PCM-fin interfacial contact area and creates additional natural convective heat dissipation pathways from the PCM region to the ambient environment while maintaining the same BTMS envelope, PCM thickness, fin count, housing geometry, and material selection as the validated rectangular-fin baseline. The lumped-capacitance thermal model was used for battery heat generation, while the enthalpy-porosity approach was employed to model PCM melting. Simulations were performed in ANSYS Fluent 2024/R2 at 1C, 3C, 5C, and 7C discharge rates at an ambient temperature of 308.15 K. Paraffin wax PCM with a latent heat of approximately 240,000 J/kg was used. The rectangular fin model was first validated against the baseline study, achieving an average cell wall temperature error of 1.03% and a maximum error of 1.47% at 5C, while the total temperature and liquid fraction deviations remained below 0.73%, confirming the reliability of the numerical model. Mesh independence and temporal convergence studies further confirmed that the selected 0.50 mm polyhedral mesh and 0.5 s time step provided accurate and stable results. The results demonstrate that the slit fin geometry provides metric-dependent improvements in PCM utilization, thermal protection duration, and high-rate latent-heat activation rates. At 1C, both configurations remained well below the 318.15 K safety threshold, but the slit fin configuration maintained approximately 0.7 K lower total temperature at 2500 s and delayed PCM melting by about 300 s compared with rectangular fins, preserving more latent heat capacity for later thermal loading. At 3C, the slit fin design extended the thermal protection duration from 1650 s to 2500 s, corresponding to a 51.5% improvement, and increased PCM latent heat utilization from LF = 0.42 to LF = 0.49, representing a 16.7% increase. At 5C, slit fins initiated PCM melting approximately 3.5 times earlier, around 100 s, compared with 350–400 s for rectangular fins, and reached LF = 0.50 at 620 s, whereas rectangular fins reached only LF = 0.37 at 1480 s. This corresponds to approximately 2.87 times faster PCM utilization and 35.1% greater PCM melting. At 7C, the slit fin system again showed stronger PCM engagement, corresponding to 35.7% greater PCM utilization. Temperature and liquid fraction contours confirmed that the slit openings intensify localised PCM melting near the heat source, improve heat spreading through the PCM domain, and support natural convection-assisted melting. Overall, the slit-fin geometry provides a geometry-based enhancement for PCM utilization and thermal protection without changing system size or material selection for PCM-based BTMSs, improving latent heat utilization and thermal protection without increasing system size, PCM volume, or material complexity. Full article

Indoor badminton venues are common mass-fitness spaces in China, but their acoustic environment remains underexamined relative to lighting, thermal comfort, and functional facilities. This study uses grounded theory to examine how users perceive acoustic conditions within the broader experience of indoor badminton venues. A total of 4721 raw online reviews for seven purposively selected venues in five Chinese cities were collected, and 3937 valid reviews remained after preprocessing. A hybrid text-processing procedure combining DeepSeek-V3-assisted term pre-screening and Python (3.11) jieba segmentation identified 74 core high-frequency terms; all grounded theory coding was conducted manually in NVivo 15. Open, axial, and selective coding generated 32 initial categories, six main categories, and an Indoor Badminton Venue User Experience Perception Model. Acoustic-related categories were then extracted to construct an Acoustic Environment Perception Mechanism Sub-Model. The results show that noise level was directly mentioned in only 45 reviews but was indirectly embedded in sport atmosphere, time-based flow, and user experience, indicating a latent perceptual role. Moderate sound may be interpreted as a vibrant sport atmosphere, whereas crowd overload and reverberant spatial conditions may shift perception toward chaotic noise. The findings provide qualitative evidence for integrating user-centered acoustic considerations into the design and operation of mass-leisure sports venues. Full article

Yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) were fabricated by atmospheric plasma spraying (APS). Three CMAS powders with different compositions (CMAS-1, CMAS-2, CMAS-3) were selected, and corrosion tests were carried out at 1200 °C, 1250 °C, and 1300 °C. The relationships among CMAS viscosity, melting point, and reaction tendency with YSZ coatings were investigated. The results show that CMAS-3 possesses the highest viscosity yet the lowest melting point, CMAS-1 has the lowest viscosity but the highest melting point, and CMAS-2 falls between the two. Quantitative penetration depth measurements reveal that higher viscosity leads to slower infiltration, while a lower melting point enables earlier infiltration onset. At elevated temperatures, all CMAS compositions achieve complete penetration, indicating that the differences in melting point and viscosity become less critical when the temperature is sufficiently high. Corrosion tests reveal that CMAS-3 exhibits the strongest reaction tendency with YSZ coatings, while CMAS-1 shows the weakest. This indicates that the infiltration behavior is governed by a dual control of melting point and viscosity—melting point determines the onset of infiltration, while viscosity controls the penetration rate. This study provides an experimental basis for the design of CMAS-resistant coatings and the evaluation of their environmental adaptability. The key finding is that the melting point plays a dominant role in initiating CMAS infiltration, while viscosity primarily regulates the penetration rate. Full article