Search Results (12,813)

To mitigate the spatiotemporal mismatch between renewable energy supply and building heating demand, this study proposes a novel non-pressurized shell-and-tube latent heat storage (NP-LHS) device coupled with an air-source heat pump (ASHP) system. To overcome the inherent low thermal conductivity of organic phase change materials (PCMs), the thermal performances of plain, corrugated, and finned tubes were systematically compared using both computational fluid dynamics (CFD) simulations and full-scale experiments. Numerical results indicate that the optimal tube spacing ratio ranges from 1.0 to 1.5. Among the evaluated geometries, the finned tube configuration exhibited superior comprehensive performance. It achieved an exceptionally high PCM volume fraction of 92.5% and dramatically reduced the complete melting time to 180 min—significantly faster than both corrugated (280 min) and bare tubes—while attaining a higher terminal temperature. Full-cycle dynamic experiments further demonstrated that integrating the finned tube NP-LHS into the ASHP system yielded a peak-shaving power reduction rate of 98.0%, effectively maintaining indoor thermal comfort. These findings conclude that expanding the conductive surface area via fins is practically more effective than inducing fluid turbulence for low-conductivity PCMs in non-pressurized storage applications. Full article

Wheat starch serves as a major dietary carbohydrate. Optimizing its structural and functional properties is essential for developing health foods. In the present study, microwave-assisted heat–moisture treatment (MHT) was applied to modify wheat starch and the effects of the physical treatments on its structure and digestibility were investigated. X-ray diffraction analysis revealed that the crystallinity of wheat starch slightly decreased after MHT. Ion chromatography revealed changes in the chain length distribution of wheat starch after modification, with a continuous increase in short-chain components over treatment time. MHT enhanced the enzymatic resistance of wheat starch, which resulted in a resistant starch content of 36.89% after 1.5 h of MHT. Excess heat disrupted the ordered structure of starch when the treatment was extended to 2 h, leading to a slight reduction in enzymatic resistance. The study provided a theoretical basis for designing functional starch ingredients through low water content physical treatment. Full article

Mullite fiber materials are widely used in high-temperature thermal insulation applications, especially in aerospace thermal protection systems, due to their excellent thermal stability and low thermal conductivity. However, the material exhibits poor resistance to infrared radiative heat transfer at elevated temperatures. Accordingly, a dual-opacifier system composed of TiO₂ and K₂Ti₆O₁₃ binary whiskers was proposed as an effective strategy for enhancing thermal insulation performance. MF/TiO_2w and MF/TiO_2w/K₂Ti₆O_13w were fabricated in this study using a sol–gel method combined with in situ whisker growth. The results show that upright and interlaced K₂Ti₆O₁₃ and TiO₂ whiskers were uniformly grown on the fiber surface, contributing to a high infrared reflectance of 97.7% in the wavelength range of 2.5–10 μm. Under a front-side temperature of 1000 °C, the modified mullite fiber-based material exhibits a backside temperature of 177.8 °C, corresponding to a reduction of 71.8 °C compared with the original sample (249.6 °C), demonstrating significantly enhanced thermal insulation performance. In addition, the composite exhibits an ultralow density of less than 0.20 g/cm³. The as-prepared thermal insulation material shows a high rebound rate of 76.5% at a strain of 30%, indicating good elasticity. The results demonstrate that the developed composite exhibits excellent infrared shielding and structural stability, confirming that the binary whisker strategy effectively enhances the thermal insulation performance of the mullite fiber-based materials, highlighting its potential for high-temperature aerospace applications. Full article

Creating secondary flows that encourage fluid interchange between hot and cold regions is frequently necessary to improve convective heat transfer in compact channels. A well-known passive method for enhancing mixing and boosting thermal performance in laminar regimes is the use of vortex generators (VGs), which create streamwise and transverse vortices. Laminar forced convection in a rectangular channel with rectangular wing vortex generators with triangular tips is investigated numerically in this work. The primary goal is to assess the impact of the number of tips per wing on pressure drop and heat transfer enhancement at a fixed angle of attack (α). This study examines a single row of rectangular wing vortex generators (VGs) with triangular tips and systematically evaluates how variations in tip number influence not only the global Nusselt number and friction factor but also the three-dimensional vortex structure distribution along the channel. This approach contrasts with many previous studies that primarily focus on global performance indices or on classical delta-type VGs. ANSYS Fluent’s finite volume method is used to solve three-dimensional stable, laminar, incompressible flow and heat transfer. Two Reynolds numbers, Re = 456 and Re = 911, are simulated for different triangular-tip configurations at a fixed angle of attack of α = 30°. To connect flow structures to heat transfer behavior, area-averaged Nusselt numbers and friction factors are calculated for each case, and vortex cores and their spatial locations are examined. The findings demonstrate that heat transfer improvement is directly and significantly impacted by the VG tip arrangement. The trade-off between heat gains and pressure losses is highlighted by the fact that some tip configurations produce stronger, more persistent vortices and higher Nusselt numbers at the expense of an increased friction factor. The conclusions are limited to laminar flow conditions at α = 30°, Reynolds numbers of 456 and 911, and the investigated one-, two-, and three-tip configurations. Full article

To meet the requirements for passive heat dissipation and self-cleaning of aluminum alloy enclosures used in 5G base-station active antenna units (AAUs), a scalable surface modification strategy involving sandblasting, NaOH etching, and PFTEOS grafting was developed for 6061 aluminum alloy. Microscale rough structures were first constructed by sandblasting, and hierarchical micro/nano structures composed of microscale pits and nanoscale plate-like/coral-like features were subsequently formed through NaOH etching and boiling-water treatment. Finally, a low-surface-energy PFTEOS layer was grafted onto the structured surface to achieve superhydrophobicity. The effects of sandblasting pressure and etching time on surface morphology, chemical composition, wettability, and infrared emissivity were systematically investigated. The results show that sandblasting enhanced infrared emissivity by increasing surface roughness and promoting optical trapping, while NaOH etching further improved emissivity through the formation of hierarchical micro/nano structures and infrared-active AlOOH/Al₂O₃ phases. After PFTEOS grafting, the surface wettability changed from hydrophilic to superhydrophobic, while the high infrared emissivity was maintained. Compared with the untreated aluminum alloy, the modified surface exhibited a remarkable increase in water contact angle from 80.10° to 153.63° and infrared emissivity from 0.0102 to 0.8951. Moreover, the water contact angle remained above 150° after continuous water-jet impact, indicating good preliminary resistance to hydraulic shear. This work provides a feasible surface-engineering route for integrating high infrared emissivity and self-cleaning capability on aluminum alloy surfaces for outdoor thermal management applications. Full article

Autophagy and apoptosis are two evolutionarily conserved catabolic processes that play important roles in maintaining cellular homeostasis and in determining cell fate when cells are exposed to various stresses in vivo. The interaction between autophagy and apoptosis has been studied extensively in cancer research, and it has been shown to affect cancer initiation and tumor formation, disease progression, therapeutic resistance, and overall survival. Autophagy typically functions as a cytoprotective mechanism in cancer cells subjected to metabolic, hypoxic, or therapeutic stress, whereas apoptosis primarily functions as an intrinsic programmed cell death pathway. While apoptosis and autophagy function as distinct pathways, there is significant molecular crosstalk, allowing cells to modulate their behavior from survival to death depending on the severity and duration of exposure to a given stressor and the cellular environment. This review examines the molecular landscape of the autophagy–apoptosis interplay in cancers, with special attention paid to the major signaling pathways involved and their biological outcomes in oncology. We examine the molecular mechanisms and signal transduction pathways involved in the crosstalk between autophagy and apoptosis in cancer. In particular, we focus on several key proteins that regulate this crosstalk, including kinases, caspases, heat shock proteins and transcription factors. Furthermore, we describe the major signal transduction pathways that regulate this crosstalk, including the PI3K/Akt/mTOR, MAPK, unfolded protein response, oxidative stress, and calcium signaling pathways. Additionally, we discussed how dysregulation of these pathways contributes to cancer progression and treatment resistance. Finally, we summarized the use of currently available therapeutic agents targeting the crosstalk between autophagy and apoptosis, including FDA-approved drugs and natural products, with the potential to enhance the effectiveness of anticancer treatments. A better understanding of this complex process will allow the development of new, precision-based, combination cancer therapies. Full article

The increasing frequency of high-temperature episodes associated with climate change poses challenges to crop productivity. Stress priming could help to mitigate these effects, with the capacity to enhance plant resilience through metabolic adjustments and memory mechanisms. We evaluated the efficacy of the Stress Memory Encoder biofertilizer (SME, TIMAC Agro) as a seed treatment to induce heat stress (HS) memory in soybean plants [Glycine max (L.) Merrill]. In Experiment 1, plants with SME (0, 2, and 4 mL kg⁻¹) were exposed to HS (35 °C for 48 h) at V3 and V6 vegetative stages. The 4 mL kg⁻¹ dose at V6 under HS consistently improved photosynthetic traits and reductions in reactive oxygen species and lipid peroxidation. Non-enzymatic antioxidants were detected to this dose at V3. Multivariate analysis revealed patterns consistent with dose-dependent physiological adjustments and potential memory acquisition. In Experiment 2, plants treated with SME were exposed to HS (34 °C for 48 h) consecutively (V3 + V6). The SME-primed plants had a higher expression of transcript factors and genes related to HS. Overall, the findings indicate that SME may act as a priming agent capable of inducing somatic memory and enhancing adaptive responses to HS in soybean. Full article

This review examines sorghum digestibility from molecular structure to clinical implications, focusing on compositional factors, processing methods, and health outcomes. We evaluate how sorghum’s unique protein–starch interactions influence digestibility and explore emerging technologies that can modulate these properties for targeted nutritional benefits. Cooked sorghum generally has lower digestibility than raw sorghum and other cereals due to heat-induced protein–starch cross-linking and the formation of disulfide bonds by sorghum proteins (kafirins), which restrict enzymatic access. Enzyme inhibitors in sorghum further reduce starch hydrolysis. This reduced digestibility may negatively impact malnourished individuals and those relying on sorghum as a dietary staple. However, it can be advantageous to individuals with diabetes by lowering postprandial blood glucose levels. Sorghum consumption may also beneficially influence the gut microbiome. Certain processing methods have been shown to significantly enhance digestibility while preserving beneficial bioactive compounds. Improving digestibility through these strategies may enhance sorghum’s value for vulnerable populations while maintaining its metabolic advantages. Balancing increased nutrient bioavailability with preservation of beneficial functional properties is critical for optimizing sorghum as a health-promoting grain across diverse populations. Full article

Fuel cell-based combined heat and power (CHP) systems enable cascade conversion of hydrogen chemical energy into electricity and heat, providing an effective pathway to enhance overall energy utilization efficiency. In this study, a system-level simulation model for a proton exchange membrane fuel cell CHP waste heat recovery system is developed, incorporating stack waste heat, auxiliary component heat dissipation, catalytic combustion heat, and air-source heat pump upgrading. The multi-source coupling characteristics and the effects of key operating parameters on system performance are quantitatively investigated. The results show that within the current density range of 0.2–1.2 A/cm², the fuel cell stack is the dominant heat source, with heat generation increasing linearly with current density. The catalytic combustion unit acts as a marginal heat source, contributing less than 2% of total heat. The performance of the heat pump system is primarily influenced by ambient temperature and compressor speed. The system energy distribution exhibits significant load dependence: as current density increases, the stack heat contribution rises from 35% to 78%, and the primary source of auxiliary power consumption shifts from the heat pump compressor to the stack air compressor. Although the heat pump COP continues to decline, the system COP first increases and then stabilizes. Sensitivity analysis indicates that ambient temperature improves CHP efficiency by 18% while increasing compressor speed enhances thermal efficiency by 51.7%, but reduces electrical efficiency by 25.2%, resulting in an overall CHP efficiency improvement of 11.0%. In contrast, cathode inlet pressure has a nearly neutral impact on system performance (<0.7% fluctuation). Full article

The escalating energy crisis and global warming drive the demand for all-season self-regulating functional textiles. This study presents a Janus smart textile that combines phase change energy storage with active and passive heating modes, electromagnetic interference shielding, and self-cleaning capabilities. The front surface incorporates phase change temperature regulation and thermochromic properties, while the back surface is spray-coated with a transition metal carbide to establish a continuous conductive network. In the low-temperature state, the black surface enhances solar absorption for efficient heating; as the temperature rises, the surface turns white to increase solar reflection and suppress overheating. This mechanism, combined with phase change energy storage, enables the textile to mitigate environmental temperature fluctuations. The MXene layer on the back provides efficient Joule heating and cycling stability under driving voltages of 3 to 5 volts, along with electromagnetic interference shielding dominated by absorption loss. The front hybrid coating further imparts hydrophobic self-cleaning performance. This study offers a strategy for synergistic active and passive thermal management, demonstrating application potential in intelligent outdoor gear and specialized protective outer layers. Full article

Nine sets of fin parameter combinations, including a plain tube control group, were modeled. Simulations were performed under steady-state conditions using the EWT Realizable k-ε turbulence model, with benzene and water as working fluids, while accounting for temperature-dependent thermophysical properties. Flow field distribution, temperature profile, Nusselt number, and pressure drop in the shell side of the heat exchanger were analyzed. Response surface methodology was employed to systematically evaluate the coupled effects of fin height and fin spacing on thermal performance. The results indicate that annular fins significantly enhance heat transfer by inducing secondary flow and disrupting the thermal boundary layer. Compared to the smooth tube, the finned tubes increased the Nusselt number (Nu) by up to 28.6% and the total heat transfer rate by 13.55%, while the pressure drop (ΔP) increased by approximately 9.81% to 16.5%. The analysis revealed that fin height is the dominant factor affecting performance, whereas fin spacing plays a regulatory role. As the fins became taller or denser, the temperature field evolved from stable stratification to intense mixing and eventually to local disorder. The study identified an optimal parameter range for engineering applications. A fin height of 2–3 mm combined with a spacing of 10–15 mm achieves the best balance between heat transfer enhancement and flow resistance. Specifically, the combination of h = 3 mm and s = 10 mm yielded the highest Energy Efficiency Coefficient (EEC) of 1.567. This configuration is recommended for large-flow, pressure-drop-sensitive systems, such as those found in petrochemical plants or long-distance heat transmission applications. Full article

Electro-thermal improvement is critical for β-Ga₂O₃ power devices to mitigate self-heating while maintaining high-voltage capability. Here, we propose a β-Ga₂O₃ cage-integrated slanted-fin MOSFET (C-SFMOSFET). By optimizing the cage-to-fin and cage-to-drain distances, the cage sequence simultaneously strengthens channel depletion and enhances heat dissipation in the gate-to-drain region. Compared with the baseline slanted-fin MOSFET (SFMOSFET), the proposed 4-cage C-SFMOSFET achieves a 1.75× higher Baliga’s figure of merit and reduces the peak junction temperature by 8 °C at 0.55 W/mm. These results indicate that the proposed device layout can effectively improve device-level electro-thermal performance and further exploit the inherent advantages of ultra-wide-bandgap β-Ga₂O₃. Full article

Hybrid MTMS–silica aerogels incorporating calcium silicate hydrate (C–S–H), the primary hydration product in cementitious systems, were synthesized via sol–gel processing followed by freeze-drying. The influence of C–S–H loading on pore structure, density, wettability, and thermal transport was investigated. The lowest thermal conductivity (0.068 W/m·K) and tap density (0.30 g/cm³) were obtained at 10% C–S–H loading (wM-CSH10), while the thermal conductivity increases to approximately 0.075–0.082 W/m·K at higher C–S–H content. All samples exhibit mesoporous structures with pore diameters in the range of 10–21 nm. Increasing C–S–H content progressively densified the network, reduced mesopore volume, and enhanced high-temperature mass retention up to 540 °C. FTIR analysis confirmed Si–O–Ca interfacial interactions, while nitrogen adsorption demonstrated persistent mesoporosity across all compositions. Thermal conductivity showed a positive correlation with density, indicating that bulk densification governs heat transport in the hybrid system. Beyond structural modification, the incorporation of C–S–H introduces chemical and microstructural features relevant to cement-based materials, suggesting potential compatibility with cementitious matrices. The results highlight the compositional trade-off between insulation efficiency and structural stability and demonstrate the potential of C–S–H-modified MTMS–silica aerogels for future integration into cement-based composites. These findings provide fundamental insight into their possible use in thermal insulation applications, such as building envelope systems (walls, façades, and roofs used for thermal insulation). Full article

Heat stress (HS) has emerged as a major environmental stressor, inducing oxidative stress and hepatic steatosis and impairing production performance and health in laying hens, with limited evidence-based nutritional interventions available. This study investigated the hepatoprotective effects of dietary silibinin (SIL) against chronic HS. In a 10-week trial, 252 43-week-old Hy-Line Brown hens were exposed to daily HS (32 ± 1 °C, temperature–humidity index [THI] > 73) and fed either a basal diet or one supplemented with 100 mg/kg SIL. SIL significantly increased laying rate (p < 0.05) and improved albumen height, Haugh units, and shell strength by week 8 (p < 0.05). Histological analysis showed a 48% reduction in non-alcoholic fatty liver disease (NAFLD) activity score, with significantly decreased hepatic triglyceride content (p < 0.05); Oil Red O staining confirmed reduced lipid droplet accumulation. SIL restored redox balance by increasing plasma, hepatic total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-Px) (p < 0.05), increasing hepatic catalase (CAT) and glutathione (GSH) levels while decreasing malondialdehyde (MDA) (p < 0.05). Untargeted plasma metabolomics identified 11 key metabolites related to 2-oxoglutarate and purine metabolism, while hepatic transcriptomics revealed 835 differentially expressed genes primarily in the PPAR signaling and fatty acid biosynthesis pathways. SIL suppressed de novo lipogenesis via downregulation of ACACA and FASN, and enhanced β-oxidation through upregulation of CPT1A and ACSL1 (p < 0.05). Molecular docking indicated favorable binding affinities between SIL and these targets, which was further supported by corresponding changes in protein expression via Western blotting. Correlation analysis revealed a consistent alignment between the upregulation of ACSL1/CPT1A and improvement in performance and antioxidant status, suggesting a coordinated metabolic shift. These findings emphasize the potential of SIL as a sustainable animal nutrition antioxidant additive, which can alleviate HS-induced lipid disorders in the liver of laying hens. Importantly, these hepatoprotective effects were demonstrated exclusively under chronic heat stress conditions; further studies incorporating a normothermic baseline are required to distinguish stress-specific mitigation from general metabolic stimulation. Full article

Aiming at the urgent heat dissipation demands of high-power, high-integration electronic devices, Cu/Al composite heat sinks combine the high thermal conductivity of copper and the lightweight advantage of aluminum, becoming a mainstream solution for advanced thermal management systems. The significant physicochemical differences between Cu and Al, however, make high-quality joining a technical bottleneck. In this study, flux-free ultrasonic brazing with a Zn-based filler metal was used to join 6061 aluminum alloy and industrial pure copper. Gradient heat treatment (55–300 °C) was subsequently applied to systematically investigate its effect on the microstructure, microhardness, and thermal properties of the joints. The results show that the as-brazed joint exhibited excellent bonding (97.3% bonding rate) and shear strength (95.24 MPa). The weld seam consisted of Zn solid solution, Cu solid solution, and Al-Cu-Zn ternary compounds. Heat treatment did not induce new phases but led to the coarsening of Zn-Al-Cu compounds and aggregation of the eutectic structure, reducing grain boundaries. Consequently, the microhardness at the weld center varied non-monotonically, and the thermal conductivity of the joint showed an overall increasing trend with rising heat treatment temperature. This enhancement is attributed to reduced phonon scattering at diminished grain boundaries. This study clarifies the heat treatment–microstructure–thermal properties relationship, providing important guidance for the thermal performance optimization of Cu/Al composite heat sinks. Full article