Search Results (71,084)

The precipitation of nanoscale HfO₂ plays a critical role in the high-temperature creep properties of Fe-Cr-Al electrical heating alloys. However, the atomic-scale initial nucleation and growth mechanisms remain unclear, hindering the precise design of precipitates based on Hf microalloying. In this study, classical molecular dynamics simulations implemented in LAMMPS were employed to investigate the formation and evolution of Hf-O clusters at 1773 K, 1873 K, and 2000 K. The Fe-Cr-Al-Hf-O system was described by hybrid potential functions, whose reliability was verified by lattice-parameter calculations in good agreement with literature values. The simulation results demonstrate that Hf atoms and O atoms attract each other, forming stable Hf-O clusters. At higher temperatures, the diffusion capabilities of Hf and O atoms are enhanced, the number of Hf-O bonds grows, and the size of the largest cluster expands, indicating that elevated temperatures promote cluster growth. The calculated diffusion activation energy of Hf and O atoms indicates that increasing temperature promotes O atom diffusion more significantly. Analysis of the cluster radius of pair gyration and average atomic energy reveals that Hf-O clusters formed at 1873 K exhibit more compact and stable structural characteristics. Radial distribution function analysis further revealed that the atomic arrangement of neighboring atoms in Hf-O clusters closely resembles the relaxed HfO₂ crystal structure at the same temperature, indicating that Hf-O clusters serve as critical nucleation cores promoting the precipitation of HfO₂ crystals. This study elucidates the dynamic formation mechanism and structural evolution of Hf-O clusters in Fe-Cr-Al alloys at the atomic scale, providing valuable guidance for the optimized design of precise control over HfO₂ nanoprecipitates. Full article

The growing need for lightweight, multifunctional, and high-performance structures in the automotive, aerospace, electronics, and medical industries has driven the development of advanced joining technologies for polymers and metal-polymer combinations. Among these, ultrasonic welding (USW) and friction stir spot welding (FSSW) have emerged as promising solid-state techniques capable of producing reliable joints with minimal thermal degradation and enhanced interfacial bonding. This review focuses on recent developments in USW and FSSW of thermoplastics, fiber-reinforced composites, and hybrid metal–polymer systems, with a particular emphasis on process mechanics, microstructural evolution, and joint performance. The mechanisms of heat generation, material flow behavior, and consolidation are discussed in relation to key process parameters, including applied pressure, rotational speed, vibration amplitude, plunge depth, and dwell time. Microstructural transformations such as polymer chain orientation, recrystallization, interfacial diffusion, and defect formation are analyzed to establish process–structure–property relationships. Mechanical performance metrics, including lap shear strength, fatigue resistance, impact behavior, and environmental durability, are critically compared across different materials and welding methods. Furthermore, recent advances in numerical and thermo-mechanical modeling, in situ process monitoring, and data-driven optimization are discussed to highlight pathways toward predictive and scalable manufacturing. Current industrial applications and existing limitations such as challenges in automation, thickness constraints, and hybrid material compatibility are also evaluated. Finally, key research gaps and future directions are identified to improve joint reliability, sustainability, and broader industrial adoption of advanced solid-state welding technologies. Full article

The mechanical response of 7xxx aluminum alloys is strongly influenced by both alloy chemistry and the resulting microstructure. In this study, the effect of precipitate characteristics on the fatigue behavior of three 7xxx aluminum alloys with different total amounts of main alloy elements was systematically investigated. Quantitative microstructural characterization was performed under T6 and T74 heat-treatment conditions by combining scanning electron microscopy, transmission electron microscopy, and electron backscatter diffraction. Meanwhile, hardness measurements, room-temperature tensile tests, and fatigue crack growth experiments were carried out to evaluate the mechanical behavior. The results show that, within the present alloy set, the over-aged condition and the alloys with higher overall alloying levels exhibited lower fatigue crack growth rates, which correlated with the coarsening of intragranular precipitates. Such microstructural evolution is suggested to facilitate dislocation motion and thereby reduce fatigue damage associated with dislocation pile-up in the present alloy set. In this work, three typical 7xxx aluminum alloys with different alloying levels were systematically investigated under T6 and T74 conditions. A statistical criterion was established to distinguish GPII zones from η′ precipitates, and a model linking precipitate characteristics to fatigue crack growth behavior was further developed. The present study aims to provide a quantitative framework for understanding and predicting the fatigue behavior of 7xxx aluminum alloys with different total amounts of main alloy elements. Full article

This paper presents a non-contact depth detection method for corrugated heat exchanger plates, aiming to improve measurement efficiency and accuracy. The system integrates a line laser sensor with a precision linear guide rail, enabling continuous acquisition of high-resolution 2D surface profiles as the sensor moves along the plate. To reduce data redundancy while preserving geometric features, a multi-stage data reduction strategy is proposed. This strategy combines the angle–chord height criterion with spline-based filtering to identify key regions of curvature and eliminate unnecessary point cloud data. For depth extraction, a two-stage feature recognition algorithm is designed. First, a coarse analysis locates candidate peaks and valleys by identifying local extrema in the reduced 2D data. Then, a fine detection process is applied: local B-spline fitting is performed near each candidate point, and a binary search algorithm is used to accurately determine the spline extrema. By computing the vertical distance between precisely located peaks and valleys, the system rapidly extracts the corrugation depth parameters. This method achieves a high balance between speed and precision, offering a practical and reliable solution for automated surface morphology inspection in heat exchanger manufacturing. Full article

Wastewater heat recovery has emerged as a vital strategy for building energy conservation, due to its significant potential and the inherent thermal stability of sewage as a heat source. Enhancing synergy between such waste heat and other clean energy sources is a key research focus. This study developed a solar-assisted sewage-source coupled heating system for a Chinese university dormitory and established a multiobjective optimization framework integrating economic, environmental, and energy efficiency indicators via a combined weighting approach of the Analytic Hierarchy Process and Entropy Weight Method. Optimization was conducted using the Hooke–Jeeves algorithm, Particle Swarm Optimization algorithm, and the Hooke–Jeeves–Particle Swarm Optimization hybrid algorithm (shorten as HJ–PSO), with subsequent comparative performance analysis. The HJ–PSO hybrid performed best: 24% lower operating costs, a 4.8-year shorter dynamic payback period, 26.35% fewer carbon dioxide emissions, 38.65% lower overall energy consumption, and an 11.18% higher system coefficient of performance. Supported by relevant policies, the system is low-carbon and economically viable, enabling grid peak shaving. This research provides theoretical and engineering references for renewable energy heating systems. Full article

The sucrose synthase (SUS) gene family plays a pivotal role in plant carbon metabolism, growth, and development. In this study, we identified 65 SUS genes across six Brassica species (B. rapa, B. nigra, B. oleracea, B. juncea, B. napus, and B. carinata), and systematically analyzed their structural characteristics, evolutionary history, and expression profiles. Phylogenetic analysis classified these genes into three subfamilies (SUSI, SUSII, and SUSIII). SUS4 orthologs (from SUSI subfamily) are completely lost in Brassica, and total SUS gene numbers are just 6–7 in Brassica diploid species, though the SUSIII subfamily exhibits significant expansion in Brassica polyploid species. Selection pressure analysis (Ka/Ks) revealed that the Brassica SUS family has primarily undergone purifying selection, although certain members show evidence of adaptive evolution. Comprehensive expression profiling and qRT-PCR validation demonstrated the functional diversification of BnSUS genes in tissue specificity and responses to hormonal and abiotic stimuli. SUSI genes BnSUS1-1/2/3/4 are predominantly expressed in vegetative tissues and flowers; SUSII genes BnSUS2-1/2 and BnSUS3-1/2 are reproductive-organ-specific, while SUSIII genes BnSUS5-1/2 and BnSUS6-1/2/3/4 show young-plant-specific weak expression. BnSUS family genes are generally upregulated by ABA, TZ and GA but downregulated by IAA, ACC, BL and JA. Salt, drought, freezing and cold mainly upregulate the BnSUS family, heat downregulates it, and osmotic stress exerts both effects. Correspondingly, Brassica SUS promoters are enriched with light-responsive (G-box, Box-4), hormone-responsive (ABRE, CGTCA-motif) and anaerobic-induction (ARE) elements. Functional characterization demonstrated that the ABA-responsive gene BnSUS3-2 significantly improved tolerance to osmotic and ionic stresses by promoting root growth in transgenic A. thaliana seedlings. These findings underscore the essential roles of BnSUS genes in maintaining cellular homeostasis and provide a theoretical foundation for the genetic improvement of carbon metabolism and stress resilience in Brassica crops. Full article

Urbanization and climate change intensify urban heat islands and air pollution; therefore, street canyon building planning that accounts for road orientation, shading, thermal environment, and ventilation is crucial. This study uses numerical simulations to investigate how non-uniform wall and road heating affects airflow and pollutant dispersion in street canyons under varying Richardson numbers (Ri) and heating scenarios (windward wall, leeward wall, road surface). The results indicate that large wall–atmosphere temperature differences combined with low incoming wind speed (high Ri) make thermal buoyancy a dominant control on canyon flow and pollutant transport. Heating of the leeward wall and road surface enhances ventilation and pollutant removal (prominently when the Ri ≥ 0.49), whereas heating of the windward wall suppresses dispersion and increases concentrations (prominently when the Ri ≥ 0.12). For a north–south street, diurnal solar heating produces strong micro-environmental contrasts. With easterly winds, morning heating of the windward wall elevates pollutant levels, while afternoon heating of the leeward wall promotes dispersion and lowers concentrations. Specifically, compared with the isothermal condition, the turbulent exchange rate at the top of the street canyon is enhanced to 1.71~6.86 times, while the convective exchange rate is suppressed to 58%~83% in the morning and enhanced to 1.21~1.92 times. These findings suggest that urban planning should limit windward wall temperature rises via shading and greening; thus, single-sided sidewalk and greening layouts on the windward side are recommended. Full article

As a solid-state welding technique, friction stir welding (FSW) has many advantages over conventional fusion welding. Its applications in the manufacturing and joining of parts in aerospace, automotive, and shipbuilding have significantly increased. Friction heat generation is the fundamental driver of the FSW process. It governs material flow, microstructural evolution, mechanical properties, and residual stresses. Understanding the effect of heat generated on the joint quality is essential for process parameter optimization, ensuring defect-free welds and high-quality joints. Thus, evaluating the thermal history of the FSW process is a key requirement for effective analysis. This comprehensive review critically discusses research studies published over the past three decades (1991–2025) that have examined different approaches to predict and measure heat generation in FSW. A total of 136 highly relevant articles were selected from the Scopus database and systematically analyzed. The effects of various welding parameters on heat generation, microstructural evolution, and joints’ mechanical properties have been reported. Different heat generation prediction and measurement techniques, such as analytical models, finite element models (FEM), and experimental methods have been discussed in terms of their feasibility, accuracy, advantages, disadvantages, and cost. The evolution, state of the art of analytical models and FEM over the last three decades are analyzed and future research directions are outlined. Finally, the correlation between process parameters, heat generated, microstructural development, and mechanical performance of the welded joints for various workpiece materials is investigated. This review provides a critical and comparative perspective that highlights the strengths and limitations of each method, offering practical guidance for researchers and industry practitioners. Full article

Quercetagetin (QG), a principal flavonol from marigold (Tagetes erecta L.), is recognized for its potent antioxidant properties. However, its efficacy in mitigating intestinal injury under heat stress (HS) conditions remains unclear. We investigated the protective effects of QG using a mouse model of HS (41 °C, 70% humidity). Mice received oral QG (100 mg/kg/day) or saline for seven consecutive days before and during HS exposure. We assessed jejunal histopathology, oxidative stress markers, inflammatory cytokines, gene expression, and gut microbiota composition via 16S rRNA sequencing. QG supplementation significantly ameliorated HS-induced jejunal damage. It enhanced the activities of superoxide dismutase (SOD) and catalase (CAT) while reducing malondialdehyde (MDA) and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). QG downregulated the mRNA expression of heat shock proteins (Hsp70, Hsp90) and upregulated antioxidant-related genes (SOD1, GPX4, CAT, NQO1, Nrf2). Furthermore, QG preserved intestinal barrier integrity by upregulating tight junction proteins (Occludin, Zo-1, Claudin). 16S rRNA analysis revealed that QG significantly reshaped the gut microbiota, marked by an increased relative abundance of Lactobacillus and a decrease in potentially harmful taxa such as Allobaculum, Oscillibacter, and Colidextribacter. QG effectively alleviates HS-induced intestinal injury by enhancing antioxidant capacity, suppressing inflammation, and modulating the gut microbiota. These findings provide a scientific basis for the potential application of QG as a functional feed additive to improve animal health under heat stress conditions. Full article

Classrooms in severe cold regions face the dual challenge of ensuring high-quality daylighting while minimizing heating energy consumption. To address this challenge, this study develops a data-driven workflow that integrates building performance simulation, multi-objective optimization and a classification-based surrogate model, aiming to explore integrated improvements in daylighting and heating energy consumption in university classrooms. The results show that: (1) multi-objective optimization significantly enhances overall performance. Daylighting performance improves, with Spatial Daylight Autonomy (sDA) and Useful Daylight Illuminance (UDI) increasing by 0.15 and 10.67%, respectively, and Daylight Glare Probability (DGP) decreasing by 16.35%. Meanwhile, Heating Energy Consumption (E_h) is reduced by 6.20 kWh/m²; (2) SHAP analysis further identifies classroom depth, height, and glazing option as key design parameters influencing integrated daylight–thermal performance; (3) the MLP classification model achieves stable predictive accuracy, with accuracy, recall, and F1-score exceeding 0.95, demonstrating strong generalization ability. This study provides quantitative insights into the relationship between spatial parameters and daylight–thermal performance, offering researchers a method for rapidly evaluating design schemes at the early design stage. Full article

Insect populations are increasingly exposed to concurrent climate warming and agrochemical contamination, yet how these stressors interact to influence reproductive performance remains poorly understood. Because fertility can constrain population growth before survival declines, understanding how environmental stress affects reproduction is essential for predicting demographic responses. Here, we investigated how elevated temperatures and sublethal imidacloprid exposure during development and early-life interact with the insecticide resistance locus Cyp6g1 to influence male reproductive performance in Drosophila melanogaster. Males were reared from embryo to adulthood under factorial combinations of temperature and insecticide exposure, and mating behaviour and fertilisation success were subsequently quantified under benign assay conditions. Early-life heat reduced fertilisation success in a genotype-dependent manner, with a pronounced collapse observed in insecticide-susceptible males. Sublethal insecticide exposure modified this thermal response, restoring fertilisation success in susceptible males and producing non-additive interactions between thermal and agrochemical stress. In contrast, although mating frequency varied across treatments, it did not show the pronounced decline observed in fertilisation success, indicating that behavioural engagement does not necessarily predict functional reproductive output. These results suggest that environmental stress experienced during early-life can reshape reproductive performance, potentially through genotype-dependent shifts in physiological investment. Considering developmental stress history and genetic variation will therefore be important for predicting insect population responses to climate warming and environmental contamination. Full article

Thermotolerant methylotrophic yeast Ogataea parapolymorpha is a promising host for high-temperature bioprocesses, yet the effects of carbon source and exogenous carbohydrates on their heat response remain poorly understood. We investigated how growth on glucose, glycerol, or methanol, short-term thermoadaptation (45 °C, 2 h), and supplementation with trehalose, sucrose, maltose, or xylose affect thermotolerance (55 °C, 30 min) and intracellular trehalose content. Thermoadaptation increased survival on all carbon sources and was accompanied by substantial trehalose accumulation in glucose- and glycerol-grown cells, but only minor trehalose accumulation in methanol-grown cells. Carbohydrate supplementation improved survival only in methanol-grown cultures. Under these conditions, trehalose, sucrose, and maltose increased intracellular trehalose levels, whereas xylose enhanced survival without a comparable increase in trehalose. These results show that the heat-stress response of O. parapolymorpha is strongly carbon source-dependent and that the protective effects of carbohydrate supplementation in methanol-grown cells cannot be explained by trehalose accumulation alone. Full article

Phenolic compounds contribute to the color, flavor, and functionality of foods but are often degraded during conventional heat treatments, prompting interest in non-thermal techniques. Thermal methods produce heat-driven changes that are more directly interpretable, whereas non-thermal methods require compound-resolved interpretation because higher post-treatment signals may reflect release from bound pools rather than true preservation. This review evaluates liquid chromatography–mass spectrometry (LC–MS) evidence on how ultrasound, high-pressure processing, pulsed electric fields, and cold plasma reshape polyphenol fingerprints across food matrices (2021–early 2026). Ultrasound and high-pressure processing preserve constitutive structures while increasing measurable phenolics through cell disruption and bound-pool release. Pulsed electric fields show similar release behavior but may shift toward oxidative losses when electroporation increases enzyme contact or downstream operations amplify degradation. Cold plasma introduces reactive oxygen and nitrogen species, with the clearest LC–MS/MS evidence for oxidation and nitration. In fresh-cut tissues, stress responses elevate phenylpropanoid products. Bulk assays such as total phenolic content (TPC) cannot separate preservation from release or true chemical conversion alone. LC–MS offers the compound-level detail needed to understand how each non-thermal technique changes polyphenol structure and functionality across food matrices. Full article

To investigate how natural inulin (FI) influences the quality of heat-induced beef myofibrillar protein (BMP) gels, BMP gel systems were prepared with graded FI concentrations (1%, 2%, 3%, 4%, and 5%). Texture analysis (TA), low-field nuclear magnetic resonance (LF-NMR), rheological measurements, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) were used to systematically characterise changes in gel properties, water migration and distribution, microstructure, and protein secondary structure. The results showed that the improvement in gel quality produced by inulin was concentration-dependent. FI at addition levels of 1–2% promoted the ordered intermolecular cross-linking of beef myofibrillar proteins, thereby facilitating the formation of a homogeneous and compact three-dimensional gel network, as confirmed by SEM and CLSM observations. Notably, 2% FI was identified as the optimal addition level for the BMP gel system. Compared with the control group, this treatment produced the highest relative β-sheet content (82%) among all groups, optimised the internal water distribution of the gel by reducing the proportion of free water, enhanced the water-holding capacity of the gels (p < 0.05), and preserved the elasticity-dominated solid-state characteristics of the BMP gel system (tan δ < 1), indicating that FI improved gel strength without changing its fundamental properties. These findings provide an important theoretical basis and practical technical parameters for the development of functional beef products with both desirable texture and high dietary fibre content. Full article