Search Results (282)

The recycling of waste into materials is a form of recovery that offers a double advantage, such as eco-sustainable sanitation and the availability of new ecological construction materials in Civil Engineering. The present study aimed to develop a composite eco-material based on sand, soil and recycled plastic waste melted using a Scheffler solar concentrator (SSC). Then, two types of mix were formulated: a sand/PW mix with ratios of 75/25, 70/30, 65/35 and 60/40, and a sand/soil/PW mix with a ratio of 60/30/10. The SSC enabled an internal melting temperature of 172.42 °C to be reached. Specimens measuring 4 × 4 × 16 cm³ were made and tested using 3-point bending, compression, capillary absorption and thermal tests. The best mechanical resistance was obtained with the 65/35 ratio of the sand/PW mix, with average values of 12.15 MPa in 3-point bending and 23.96 MPa in compression. This composite eco-material had a water absorption rate of 0.4% and a thermal diffusivity of 0.36 mm²/s. On the other hand, the sand/PW/laterite mix had a mechanical strength of 10.1 MPa in 3-point bending and 22.83 MPa in compression, with a water absorption rate of 2.3% and a thermal diffusivity of 0.44 mm²/s. In addition to these initial results, we plan to analyze the effect of thermal shock or wetting-drying cycles on the durability of this composite eco-material. As these properties comply with the established standards, the sand/soil/recycle HPDE composites can be used for applications such as pavers and tiles for interior flooring, and hollow and solid blocks. Full article

Adjustable steam ejectors exhibit significant adaptability to various operating conditions. However, the coupling regulation mechanism between ejector performance and the internal flow field remains insufficiently understood, thereby limiting further optimization. The novelty of this study lies in elucidating the ejector’s performance regulation mechanism by examining the influence of spindle position on non-equilibrium condensation in wet steam. This approach clarifies the flow–thermal–phase-change coupling mechanism and interprets the resulting condensation suppression and shock wave dynamics. In this study, the effects of operating conditions and spindle position on ejector performance were quantitatively characterized. The flow-field evolution was further analyzed through key flow-field variables (pressure, Mach number, temperature, and condensate mass fraction). Moreover, the relationship between ejector performance and flow characteristics was investigated. The flow–thermal–phase-change coupling analysis reveals that the spindle effectively regulates steam ejector performance, internal thermodynamic behavior, and phase-transition processes by adjusting the equivalent throat diameter. Under a representative operating condition, compared with the baseline position (d_t = 5.66 mm), moving the spindle in the positive x-axis direction (to d_t = 5 mm) decreased the equivalent throat diameter and the motive-fluid mass flow rate by 11.7% and 22.6%, respectively. Consequently, the distance between adjacent shock waves gradually decreased along the flow direction (by approximately 14.1%), and the global maximum Mach number decreased sharply from 2.0 to 1.6 (a 20% reduction). The jet core was significantly shortened, while both the intensity and number of shock waves in the diffuser were reduced. Additionally, the local backflow near the wall of the mixing chamber’s contraction section was suppressed, resulting in a weaker temperature rise in the backflow region. The fluid temperature approached the outlet temperature more gradually, while the average flow-field temperature increased. Meanwhile, the condensate mass fraction in the mixing chamber was significantly reduced (from 0.1 to 0), and the entrainment ratio was enhanced. This configuration is suitable for applications requiring low discharge pressure, high motive pressure, or high suction pressure. Conversely, moving the spindle in the negative x-axis direction enlarged the equivalent throat diameter, which generated higher Mach numbers and stronger shock waves. This enlarged throat configuration enhances the ejector’s resistance to elevated discharge pressure and increases the critical discharge pressure, making it more suitable for high discharge pressure, low motive pressure, or low suction pressure conditions. Full article

Auxiliary bearings in vertical magnetic suspension systems can suffer thermal damage and impact-induced failure during rotor drop events caused by instability. This study aims to clarify the coupled effects of collision, frictional heating, and transient heat transfer on auxiliary bearing response. Dynamic, thermodynamic, and finite element models were established to analyze impact behavior, frictional heating, and temperature-field evolution, and were validated using rotor-drop measurements of impact force, rotor displacement, and outer-ring temperature together with post-test damage observations. The results show that severe impact and friction rapidly convert rotor kinetic energy into thermal energy, producing a non-uniform temperature field in the auxiliary bearings. The highest temperature occurs in the inner ring, followed by the rolling elements and outer ring, with peak temperatures of 169.59 °C, 154.66 °C, and 94.79 °C, respectively. Owing to gravity, gyroscopic motion, and rotor inclination during drop, the upper auxiliary bearing experiences greater impact loads, a faster speed increase, and a higher peak temperature rise than the lower bearing. Experimental evidence, including thermal discoloration, wear positions, and component damage, agrees with the simulated high-temperature regions. These results support thermal-shock-resistant design, structural optimization, and operational safety assessment of auxiliary bearings. Full article

Silicon nitride ceramics exhibit excellent structural strength and electromagnetic wave transmission performance, yet demonstrate significant thermal shock instability under extreme conditions. Boron nitride (BN), on the other hand, possesses outstanding thermal shock resistance and electromagnetic wave transmission properties but exhibits relatively lower structural strength. Compositing these two materials holds promise for developing an integrated material that combines high-temperature load-bearing capacity with wave transmission capability. This study employed spark plasma sintering (SPS) technology to systematically investigate how varying BN content affects the sintering densification process and microstructural evolution of Si₃N₄/BN composite ceramics. Furthermore, we elucidated the mechanisms by which material composition and processing parameters influence key mechanical properties, dielectric characteristics, and other multifunctional attributes of the composites, providing a theoretical foundation for synergistic optimization design. The results indicate that BN incorporation suppresses both the phase transition from α-Si₃N₄ to β-Si₃N₄ during sintering and the growth of elongated β-Si₃N₄ crystals: the former hinders densification while the latter promotes it, resulting in a dual competitive mechanism that initially increases followed by decreases in sintered density. The effects of BN content on elastic modulus and fracture toughness align with trends in sintering density, whereas hardness, flexural strength, dielectric constant, and dielectric loss all show a monotonically decreasing trend with increasing BN content. Full article

Thermophilic cyanobacteria successfully colonize thermal gradients within hot springs, implying evolved mechanisms to cope with temperature-induced oxidative stress. Although polyphosphate (polyP) is known to contribute to oxidative stress resistance, its specific role in thermophilic cyanobacteria remains poorly understood. To address this, this study established a temperature gradient (30–70 °C) and used phloretin (polyP synthesis inhibitor) plus exogenous polyP to investigate polyP metabolism, redox homeostasis, photosynthetic function, and growth of Thermosynechococcus sp. FJSJ-1 from hot spring. The results show that temperature fluctuations specifically induce polyP accumulation, whereas inhibiting polyP synthesis sharply elevates reactive oxygen species (ROS) and overloads intrinsic defenses including superoxide dismutase, catalase, glutathione, and heat shock proteins. Crucially, exogenous polyP rescued phloretin-induced oxidative damage and growth inhibition. PolyP mitigates oxidative damage not by direct ROS scavenging but by integrating and reinforcing endogenous antioxidant network. This protective effect in turn safeguards photosystem II from oxidative attack, thereby preserving photosynthetic pigment stability, phycobiliprotein content, and electron transport efficiency. Taken together, polyP contributes to temperature adaptability in Thermosynechococcus sp. FJSJ-1 by coordinating antioxidant defense. This study elucidates a key molecular strategy for thriving across temperature ranges in geothermal ecosystems, advancing microbial adaptation knowledge and providing a theoretical basis for engineering thermotolerant strains for bioremediation and biofuel production. Full article

This paper presents the development, fabrication, and characterization of a droplet-based microfluidic platform designed for precise local thermal treatment of cancer cells, with prospective chemical targeting as a future application. The workflow begins with a finite element model (FEM) using COMSOL Multiphysics 6.0 to characterize coupled hydrodynamic and thermal behavior, specifically analyzing temperature distributions across single-phase and three-phase regimes. Following the simulation, work has progressed to the fabrication of a microfluidic device and the characterization of its platinum heat source and temperature detector to ensure precise thermal control. To replicate realistic biochemical conditions, experiments have employed a three-phase configuration of oil, water, and fluorescent BSA solution. In the final stage, DX5-GFP MES-SA cancer cells have replaced the BSA solution to complete the measurements. To ensure reagent homogenization and consistent cellular exposure, a serpentine channel design was utilized to induce Dean vortices, which significantly enhanced internal mixing within the droplets. Fluorescence-loss experiments demonstrated that localized heating above ~60 °C induces irreversible thermal damage in both model proteins (fluorescent BSA) and cancer cells, establishing a proof-of-concept basis for precise thermal regulation at the single-droplet level. By deactivating specific thermo-sensitive proteins responsible for drug resistance, this integrated approach to thermal and hydrodynamic optimization enhances the efficacy of chemical stimuli and provides a robust platform for investigating the modulation of cellular defense mechanisms in future biotechnological applications. The platform holds significant potential for advancing precision oncology by enabling systematic, single-cell-level investigation of heat-shock-mediated drug sensitization, with long-term implications for overcoming multidrug resistance in aggressive cancer therapies. Full article

High-performance thermal protection materials are urgently required in harsh thermal environments, such as hypersonic vehicles, the thermal runaway of energy batteries and high-temperature equipment. Conventional aerogels only exhibit passive thermal insulation and fail to resist instantaneous high-temperature attack. Herein, a cooling material of ammonium oxalate (AO) was introduced to achieve efficient, active endothermic protection. A cellular isolation effect induced by graphene nanosheets combined with anti-solvent crystallization was adopted to significantly decrease the size of AO crystals by over 93%. Based on superfine morphology and the constructed conduction network, the decomposition rate and heat absorption capacity of obtained graphene-doped AO powders (GdAPs) are improved by 41.2% and 30.4%, respectively. The mechanisms of morphology regulation and enhanced heat absorption are explored specifically in this study. Furthermore, GdAPs are embedded in phenolic resin to prepare thermal protection composite materials. Benefiting from their nearly complete thermal decomposition, GdAPs serve as a sacrificial template to generate discrete micropores in pyrolyzed resin. So, the as-prepared carbon aerogels (CAs) with a regulable microstructure exhibit an extremely low thermal conductivity of 0.056 W/(m·K), which is lower than those of reported CAs with the same density. Based on the above advantages, a synergistic endothermic-insulating thermal protection material is reported for the first time, and its heating rate is only 28.6% of that of commercial silica aerogel under identical high-temperature shock. Therefore, a new accessible strategy is demonstrated to provide high-efficiency thermal protection for resisting both abrupt and prolonged high temperature. Full article

Physical energy-based therapies are non-invasive adjunctive interventions that deliver mechanical, electromagnetic, light, or radiofrequency/thermal energy to tissues with the aim of reducing symptoms and improving tolerance of active rehabilitation. Osteoarthritis (OA) is a heterogeneous whole-joint disorder in which cartilage degeneration, subchondral bone remodeling, synovitis, peri-articular tissue dysfunction, neuromuscular impairment, and pain sensitization may interact to produce pain, stiffness, and activity restriction. As conservative therapy for OA, education, progressive therapeutic exercise, weight management when indicated, and self-management remain the core of care. Nevertheless, some patients cannot fully participate in exercise because of pain, fear of movement, load intolerance, comorbidity, or limited access to supervised rehabilitation. This narrative review synthesizes evidence published mainly between 2016 and 2026 for extracorporeal shock wave therapy (ESWT), photobiomodulation/low-level laser therapy (PBMT/LLLT), pulsed electromagnetic field therapy (PEMF), transfer energy capacitive and resistive/capacitive–resistive electric transfer (TECAR/CRET) therapy, body weight support and aquatic unloading strategies, and mechanosonic vibration therapies. The available literature suggests that ESWT and PBMT/LLLT may provide short- to mid-term pain and function benefits in selected patients with knee OA when parameters are aligned with evidence-supported dosing windows. PEMF and vibration therapies show promising but less consistent effects because protocols, devices, sham conditions, and populations vary. TECAR/CRET and unloading approaches are best interpreted as enabling tools that may reduce guarding, improve walking tolerance, or increase the quality of therapeutic exercise, rather than stand-alone disease-modifying treatments. Current national and society guidelines consistently prioritize exercise, education, and weight management; most of the modalities reviewed here are absent from guidelines or are supported only indirectly, which justifies cautious wording and individualized use. A practical application model is, therefore, time-limited and goal-oriented: identify the barrier to rehabilitation, select a modality with a plausible mechanism and published protocol, monitor pain and functional response, and discontinue the modality if it does not improve participation in active care. Full article

Harmless treatment significantly raises the alumina content of secondary aluminum dross (SAD), laying the foundation for the preparation of MgAl₂O₄ (MA) refractory bricks from SAD by doping MgO. Relevant research on different molding methods, as well as the effects of binder types and dosages on the physical properties (such as compressive strength, thermal conductivity, and thermal shock resistance) of sintered bricks, remains inadequate. In this study, 15 wt% MgO was first added to make the Al₂O₃/MgO mass ratio of SAD close to the theoretical value of 2.53 for MA formation, and the SAD-MgO premix was used as raw material. The influence of molding methods and binders on the properties of sintered bricks was investigated. The results indicate that dry pressing outperforms casting in physical performance. When calcium lignosulfonate (CL) was used as the binder for dry pressing, the average compressive strength reached a maximum of 102.12 MPa, the corresponding thermal conductivity was 2.24 W/(m·K), and the sample withstood 11 thermal shock cycles. Binder dosage experiments showed that the optimal CL addition was 5 wt%, and the recommended upper limit was 10 wt%. This work provides a new perspective for the high-value utilization of SAD in the preparation of spinel refractory bricks. Full article

Grey cast iron brake discs remain standard in automotive braking systems due to their favourable thermal conductivity and mechanical strength. However, increasingly stringent environmental regulations, including Euro 7, necessitate enhanced surface durability to reduce particulate emissions and mitigate corrosion-related degradation. In this context, laser metal deposition (LMD) offers a promising route to engineer wear-resistant coating systems with tailored microstructures. This study investigates phase formation and microstructural evolution in a 316L/430L-WC multilayer coating deposited on grey cast iron (GJL) brake discs and subjected to brake-shock testing to replicate thermomechanical load cycles representative of real braking conditions. X-ray diffraction (XRD) performed on the interlayer region between the 316L and 430L-WC layers revealed clear evidence of σ-phase formation, indicating intermetallic transformations facilitated by thermal cycling. Microstructural characterization using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) identified localized enrichment of Cr- and Fe-rich regions that support the XRD-based interpretation of σ-phase development. These results provide insights into phase transformations and elemental diffusion in LMD-fabricated brake-disc coatings. The findings advance the understanding of thermally induced transformations in multilayer steel systems and support the optimization of LMD coatings for high-temperature and wear-intensive applications through advanced analytical evaluation. Full article

Thermal shock resistance is a critical parameter for evaluating the long-term service reliability of protective coatings in high-temperature molten-salt environments. In this study, Al₂O₃–Y₂O₃ composite coatings containing 0, 2, 5, and 8 wt.% Y₂O₃ were fabricated on 316L stainless-steel substrates by atmospheric plasma spraying (APS). Their phase constitution, microstructure, mechanical properties, and thermal shock resistance were systematically investigated. The results showed that, with increasing Y₂O₃ content, the relative content of α-Al₂O₃ gradually increased, whereas the coating densification, microhardness, and fracture toughness first increased and then decreased. After 200 thermal shock cycles, the thermal shock resistance of the Al₂O₃–Y₂O₃ composite coatings followed the order of 5 wt.% Y₂O₃ > 2 wt.% Y₂O₃ > 8 wt.% Y₂O₃ > 0 wt.% Y₂O₃, indicating that the addition of an appropriate amount of Y₂O₃ significantly improves the thermal shock resistance of the coatings. Analysis of the failure mechanism further revealed that the addition of an appropriate amount of Y₂O₃ enhanced phase stability and optimized the coating microstructure, thereby improving the crack-propagation resistance and ultimately enhancing the thermal shock resistance. In contrast, excessive Y₂O₃ weakens this beneficial effect because of increased microstructural heterogeneity and a higher defect density. Full article

The thermal shock resistance (TSR) of refractories is a critical determinant of the service life and operational safety of high-temperature industrial equipment in metallurgy, building materials, and chemical engineering. This paper systematically reviews the state-of-the-art research on the evaluation of TSR for refractories. On the theoretical level, the evolutionary logic from classical thermoelastic theory to energy-based damage theory, brittleness evaluation criteria, and the dimensional analysis-based R_Π theory is delineated, with a comparative analysis of the applicability of various criteria in dense versus porous material systems. Regarding evaluation methodologies, the strengths and limitations of conventional thermal cycling tests, splitting tests (notably Brazilian and wedge splitting), and specialized techniques such as ultrasonic pulsing and nano-indentation are scrutinized. Furthermore, the application of non-destructive monitoring technologies, such as Digital Image Correlation (DIC) and Acoustic Emission (AE), for in-situ damage capture is discussed. Additionally, the potential of machine learning in performance prediction and inverse material design is explored. Finally, it is posited that future research should focus on promoting the development of multiscale, standardized, and intelligent evaluation frameworks to meet the requirements of harsh operating environments in emerging fields such as green metallurgy. Full article

In protected carbon fibre-reinforced polymer laminates subjected to simulated lightning strike, while thermal effects mostly affect the topmost UD plies, damage in the bulk, where temperatures can be far from the ablation temperatures of the composite constituents, is mainly the result of the explosion of the lightning protection layer, the supersonic plasma expansion shock waves, and the magnetic forces. In this work, previously validated three-dimensional models are applied to the analysis of lay-up and stacking sequence effects on the mechanical damage induced by simulated lightning strike on carbon/epoxy multi-directional laminates and compared with experimental observations in the literature. This work demonstrates that those observations can be replicated by the proposed models, predicting the effect of lay-up and stacking sequence not only on the orientation of mechanical damage, but also on its size. In addition, no effect on damage depth is predicted, which is also in agreement with available experimental observations. Finally, the models predict that laminates with thicker ply blocks have larger mechanical damage projected areas, which is also in agreement with experimental observations in the literature. While the previous literature had focused on the effect of the lay-up and stacking sequence on thermally induced damage, this work is a first attempt to predict those effects on the mechanical resistance, which in the future will be key to assessing lightning damage tolerance in protected composite laminates. Full article

Low-temperature conditioning is a key procedure in the flexibility evaluation of waterproofing membranes and directly affects the reliability of subsequent performance assessments. However, the internal unsteady-state heat transfer kinetics and the thermal gradient evolution mechanisms in multi-layer composite membranes under transient cold shocks require further investigation. Focusing on commonly utilized 3 mm and 4 mm thick SBS (Styrene–Butadiene–Styrene)-modified bitumen waterproofing membranes as subjects, this study investigated the internal dynamic temperature fields and microstructural response of bituminous waterproofing membranes under standard low-temperature flexibility testing conditions. By accurately pre-embedding micro-temperature sensors in situ at the interface between the surface layer and the reinforcement matrix, the transient thermal response profiles of specimens with varying specifications in a −25 °C liquid environment were quantified. Simultaneously, a three-dimensional transient heat conduction finite element model was established to elucidate the dynamic evolution of internal spatial temperature gradients. The congruence between experimental and numerical results demonstrates that upon exposure to extreme cold, composite membranes of different thicknesses exhibit a pronounced “surface-to-core” heat transfer lag effect. The cooling rate maximized within the initial 10 min of exposure. Conversely, the internal interface layer—acting as a high-thermal-resistance zone and the most unfavorable point for heat conduction—necessitated 10~20 min of nonlinear thermal dissipation to stabilize at the target ambient temperature. This study clarifies the transient thermal response and temperature-field evolution laws of bituminous waterproofing membranes, providing a robust theoretical framework for elucidating low-temperature embrittlement mechanisms and informing the material design and application of waterproofing projects in cold regions. Full article

Waste heat recovery from automotive exhaust gases represents an important strategy for improving vehicle energy efficiency. This study experimentally investigates the performance of a thermoelectric generator (TEG) system based on TEC1-12706 modules running under different cold-side cooling conditions and incorporating a Hot Rolled Steel (HRS) protective layer on the hot side. The HRS plate was used to ensure uniform heat distribution and protect the thermoelectric module against thermal shocks generated by a 250 °C heat source. Four cooling regimes were experimentally analyzed: natural convection and forced airflows equivalent to 40, 60, and 90 km/h. The results proved that increasing airflow intensity significantly improved the temperature difference across the module, from approximately 16 ± 2 °C under natural convection to nearly 40 ± 2 °C at the highest airflow velocity. Correspondingly, the steady-state voltage generated increased from approximately 0.25 ± 0.01 V to over 0.60 ± 0.01 V under an 82 Ω resistive load. The measured hot-side temperature remained below 75 °C in all experimental conditions, confirming the thermal protection capability of the HRS layer. The experimental data also revealed a near-linear relationship between voltage and temperature difference, consistent with the Seebeck effect. The proposed configuration shows the feasibility of combining thermal protection and forced convection cooling to improve the stability and electrical performance of thermoelectric waste heat recovery systems intended for low-power automotive auxiliary applications. Full article