Search Results (3,215)

The rheological behavior and low-temperature curing kinetics of poly(ethylene glycol fumarate)–acrylic acid systems initiated by benzoyl peroxide/N,N-dimethylaniline have been investigated for the first time with a focus on the development of thermosetting binders with controllable properties. It has been established that both composition and temperature have a significant effect on rheological behavior and kinetic parameters. Rheological studies revealed non-Newtonian flow behavior and thixotropic properties, while oscillatory tests demonstrated structural transformations during curing. Increasing the temperature was found to accelerate gelation, whereas a higher polyester content retarded the process, which is crucial for controlling the pot life of the reactive mixture. DSC analysis indicated that isothermal curing at 30–40 °C can be satisfactorily described by the Kamal autocatalytic model, whereas at 20 °C, at later stages, and at higher polyester contents, diffusion control becomes significant. The thermal behavior of cured systems was investigated using thermogravimetry. Calculations using the isoconversional Kissinger–Akahira–Sunose and Friedman methods confirmed an increase in the apparent activation energy for thermal decomposition, suggesting a stabilizing effect of poly(ethylene glycol fumarate) in the polymer structure. The studied systems are characterized by controllable kinetics, tunable viscosity, and high thermal stability, making them promising thermosetting binders for applications in composites, construction, paints and coatings, and adhesives. Full article

Although known as a cool-season vegetable, leeks (Allium ampeloprasum L. var. porrum) are particularly susceptible to sudden temperature drops during the seedling stage. While melatonin’s mitigating effect on abiotic stresses has been observed in many plants, very few studies have investigated its effects on leek seedlings under cold stress. In this study, leek seedlings grown under ideal conditions were sprayed with melatonin at concentrations of 0, 1, 2, 4, and 8 µM on the 45th and 60th days. Morphological data were recorded on the 74th day, and the following day, cold stress was applied at 0 °C for 0, 2, 4, 6, and 24 h. On the 76th day, the first biochemical analyses (antioxidant capacity, total phenolic content, total flavonoid content, and total soluble protein content) were performed. After a three-week growth period under ideal conditions, morphological measurements and biochemical analyses were repeated. According to the findings, treatments with 4 and 8 μM melatonin prevented cold-induced changes in the plants’ morphological data. It was determined that concentrations of 1 and 2 µM melatonin were more effective on biochemical contents. According to the study’s findings, melatonin treatment mitigated the harmful effects of cold stress on leeks. The results obtained indicate that melatonin is a promising tool for increasing plants’ resistance to cold stress. Full article

Long-term greenhouse operations face a critical challenge in the form of soil quality degradation, yet the key intervention periods and underlying mechanisms of this process remain unclear. This study aims to quantify the effects of greenhouse lifespan on the evolution of soil quality and to identify critical periods for intervention. We conducted a systematic survey of greenhouse operations in a representative area of Yunnan Province, Southwest China, and adopted a space-for-time substitution design. Using open-field cultivation (OF) as the control, we sampled and analyzed soils from vegetable greenhouses with greenhouse lifespans of 2 years (G2), 5 years (G5), and 10 years (G10). The results showed that early-stage greenhouse operation (G2) significantly increased soil temperature (ST) by 8.38–19.93% and soil porosity (SP) by 16.21–56.26%, promoted nutrient accumulation and enhanced aggregate stability compared to OF. However, as the greenhouse lifespan increased, the soil aggregates gradually disintegrated, particle-size distribution shifted toward finer clay fractions, and pH changed from neutral to slightly alkaline, exacerbating nutrient imbalances. Compared with G2, G10 exhibited reductions in mean weight diameter (MWD) and soil organic matter (SOM) of 2.41–5.93% and 24.78–30.93%, respectively. Among greenhouses with different lifespans, G2 had the highest soil quality index (SQI), which declined significantly with extended operation; at depths of 0–20 cm and 20–40 cm, the SQI of G10 was 32.59% and 38.97% lower than that of G2, respectively (p < 0.05). Structural equation modeling (SEM) and random forest analysis indicated that the improvement in SQI during the early stage of greenhouse use was primarily attributed to the optimization of soil hydrothermal characteristics and pore structure. Notably, the 2–5 years was the critical stage of rapid decline in SQI, during which intensive water and fertilizer inputs reduced the explanatory power of soil nutrients for SQI. Under long-term continuous cropping, the reduction in MWD and SOM was the main reason for the decline in SQI. This study contributes to targeted soil management during the critical period for sustainable production of protected vegetables in southern China. Full article

Coke is an essential raw material in the blast furnace (BF) ironmaking process. Its moisture content significantly impacts BF ironmaking production. This study employs a coupled Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) approach to simulate the drying process of wet coke within a coke silo (CS) dryer. Initially, the model was validated by comparing numerical results with experimental data from the literature. Subsequently, it investigated the gas flow dynamics, heat and mass transfer characteristics, and differences in drying behaviour across distinct dryer zones. Finally, the effects of inlet gas velocity and inlet gas temperature on the drying process were systematically quantified. Simulation results reveal that the bottom of the CS dryer exhibits a low-velocity laminar state, while the middle and upper regions display intense gas flow motion. Consequently, the bottom region exhibits insufficient particle drying in comparison to other zones, with the average particle moisture content decreasing by less than 20%. Under the continuous heat exchange between the hot gas and the particles, the moisture content of the particles decreases rapidly. Based on the drying rate behaviour, the drying process exhibits the following three different stages: the pre-heating period, the constant-rate period, and the falling-rate period. Compared to zones 1 and 3, zone 2 exhibits higher temperatures due to its high heat transfer efficiency, which significantly promotes a reduction in particle moisture content. An increase in inlet gas velocity enhances the particle drying rate and heat flux, accelerates moisture reduction, and raises the temperature. The impact of inlet gas velocity is most pronounced after the constant-rate period, with particle drying uniformity decreasing as the inlet gas velocity increases, consequently leading to a decline in drying quality. Increasing inlet gas temperature significantly increases particle temperature and heat flux throughout the drying period and accelerates the high-rate drying stage. These findings provide fundamental insights for further understanding and studying the coke drying process. Full article

Background/Objective: Sleep is a vital determinant of human health, where both its quantity and quality directly impact physical and mental well-being. Thermoregulation plays a pivotal role in sleep quality, as the body’s ability to regulate temperature varies across different sleep stages. This study examines the effects of a novel real-time temperature adjustment (RTA) mattress, which dynamically modulates temperature to align with sleep stage transitions, compared to constant temperature control (CTC). Through polysomnographic (PSG) assessments, this study evaluates how adaptive thermal regulation influences sleep architecture, aiming to identify its potential for optimizing restorative sleep. Methods: A prospective longitudinal cohort study involving 25 participants (13 males and 12 females; mean age: 39.7 years) evaluated sleep quality across three conditions: natural sleep (Control), CTC (33 °C constant mattress temperature), and RTA (temperature dynamically adjusted: 30 °C during REM sleep; 33 °C during non-REM sleep). Each participant completed three polysomnography (PSG) sessions. Sleep metrics, including total sleep time (TST), sleep efficiency, wake after sleep onset (WASO), and sleep stage percentages, were assessed. Repeated-measures ANOVA and post hoc analyses were performed. Results: RTA significantly improved sleep quality metrics compared to Control and CTC. TST increased from 356.2 min (Control) to 383.2 min (RTA, p = 0.030), with sleep efficiency rising from 82.8% to 87.3% (p = 0.030). WASO decreased from 58.2 min (Control) and 64.6 min (CTC) to 49.0 min (RTA, p = 0.067). REM latency was notably reduced under RTA (110.4 min) compared to Control (141.8 min, p = 0.002). The REM sleep percentage increased under RTA (20.8%, p = 0.006), with significant subgroup-specific enhancements in males (p = 0.010). Females showed significant increases in deep sleep percentage under RTA (12.3%, p = 0.011). Conclusions: Adaptive thermal regulation enhances sleep quality by aligning mattress temperature with physiological needs during different sleep stages. These findings highlight the potential of RTA as a non-invasive intervention to optimize restorative sleep and promote overall well-being. Further research could explore long-term health benefits and broader applications. Full article

In steel continuous casting, the secondary cooling zone is usually equipped with air-mist nozzles. Spray nozzle clogging is a common problem that reduces cooling efficiency and affects product quality. This study uses a 3D CFD model to investigate its impact on heat transfer. The model includes the full-size caster geometry and actual nozzle layout to analyze the effect of clogging on the cooling process. The solidification process is modeled using the enthalpy-porosity method. Spray cooling is defined through empirical HTC correlations on the slab surface. The study focuses on how nozzle clogging changes the surface temperature, cooling rate, and metallurgical length (ML). Simulation results show that clogging raises the local surface temperature by about 100 K and increases the ML. More clogged nozzles lead to a longer ML. Clogging near the meniscus has a stronger impact, showing that early-stage cooling plays an important role in solidification. Even a single clogged nozzle can increase the ML by 3.2%, highlighting the significant effect of nozzle clogging on the casting process. Full article

Conducting a safety simulation assessment of gas release from the vent mast during the design stage holds significant importance for ship design and system operation safety on LNG-powered vessels. Based on a large-scale practical LNG-powered vessel, this paper employs the CFD method to carry out a safety assessment of the natural gas dispersion, and proposes an optimization design method to address the issue where the vent mast height of large-scale LNG-powered vessels fails to meet specifications. The influencing factors of gas dispersion are discussed. The simulation results indicate that the vent mast height, wind direction, and wind velocity significantly affect the gas dispersion behavior. A lower vent mast height results in a greater risk of flammable gas clouds accumulating on the deck surface. Hazards analysis of the 6 m vent mast condition with windless suggests that a cryogenic explosion hazard zone is formed on the deck centered around the mast position, with the maximum gas concentration reaching 30% and the minimum temperature below −55 °C. The gas cloud spreads along the wind direction, and the extension distance is positively correlated with wind speed. With the increase in wind velocity, the height and volume of flammable gas clouds decrease. When the wind speed is 15 m/s, the volume of the flammable gas cloud is less than half of that at 5 m/s and less than one-tenth of that at 0 m/s. Higher wind velocity can notably promote gas diffusion. Full article

Coal serves as a cornerstone and stabilizer for China’s energy security; utilizing it in a clean and efficient manner aligns with the current national energy situation. The moisture content of coal is a crucial factor affecting its calorific value and separation efficiency. Therefore, enhancing the drying rate while simultaneously reducing the moisture content in coal is essential to improve separation efficiency. This paper primarily investigates the drying and separation characteristics of wet fine coal particles within a gas–solid fluidized bed system. A hot gas–solid fluidized bed was employed to study the particle fluidization behavior, heat–mass transfer, and agglomeration drying properties under varying airflow temperatures. The results indicate that as the airflow temperature increases, the minimum fluidization velocity tends to decrease. Additionally, with an increase in bed height, the particle temperature correspondingly decreases, leading to weakened heat exchange capability in the upper layer of the bed. Faster heating rates facilitate rapid moisture removal while minimizing agglomeration formation. The lower the proportion of moisture and magnetite powder present, the less force is required to break apart particle agglomerates. The coal drying process exhibits distinct stages. Within a temperature range of 75 °C to 100 °C, there is a significant enhancement in drying rate, while issues such as particle fragmentation or pore structure collapse are avoided at elevated temperatures. This research aims to provide foundational insights into effective drying processes for wet coal particles in gas–solid fluidized beds. Full article

Temperature is a key factor in regulating interfacial behaviors and enhancing oil recovery during low-salinity water flooding in tight sandstone reservoirs. This study systematically investigates the synergistic mechanisms of temperature and salinity on ion exchange, wettability alteration, interfacial tension, and crude oil desorption. The experimental results show that elevated temperature significantly strengthens the oil–water–rock interactions induced by low-salinity water, thereby improving oil recovery. At 70 °C, the release of divalent cations such as Ca²⁺ and Mg²⁺ from the rock surface is notably enhanced. Simultaneously, the increase in interfacial electrostatic repulsion is evidenced by a shift in the rock–brine zeta potential from −3.14 mV to −6.26 mV. This promotes the desorption of polar components, such as asphaltenes, from the rock surface, leading to a significant change in wettability. The wettability alteration index increases to 0.4647, indicating a strong water-wet condition. Additionally, the reduction in oil–water interfacial zeta potential and the enhancement in interfacial viscoelasticity contribute to a further decrease in interfacial tension. Under conditions of 0.6 PW salinity and 70 °C, non-isothermal core flooding experiments demonstrate that rock–fluid interactions are the dominant mechanism responsible for enhanced oil recovery. By applying a staged injection strategy, where 0.6 PW is followed by 0.4 PW, the oil recovery reaches 34.89%, which is significantly higher than that achieved with high-salinity water flooding. This study provides critical mechanistic insights and optimized injection strategies for the development of high-temperature tight sandstone reservoirs using low-temperature waterflooding. Full article

Camelina (Camelina sativa) is an oilseed crop of increasing importance, valued not only for its adaptability to diverse environmental conditions and potential for sustainable agriculture but also for its economic advantages, including low input requirements and suitability for biofuel production and niche markets. This study examines the relationship between camelina yield and climatic variables—specifically temperature and precipitation—based on a ten-year field experiment conducted in Poland. To capture the temporal dynamics of weather conditions, Functional Data Analysis (FDA) was applied to daily temperature and precipitation data. The analysis revealed that yield variability was strongly influenced by the length of the vegetative period and specific weather patterns in April and July. Higher yields were recorded in years characterized by moderate spring temperatures, elevated temperatures in July, and evenly distributed rainfall during the early generative growth stages. The Maximal Information Coefficient ($\mathrm{M}\mathrm{I}\mathrm{C}$) confirmed the relevance of these variables, with the duration of the vegetative phase showing the strongest correlation with yield. Cluster analysis further distinguished high- and low-yield years based on functional weather profiles. The FDA-based approach provided clear, interpretable insights into climate–yield interactions and demonstrated greater effectiveness than traditional regression models in capturing complex, time-dependent relationships. These findings enhance our understanding of camelina’s response to climatic variability and support the development of predictive tools for resilient, climate-smart crop management. Full article

In this study, the solidification behavior of 310S stainless steel was systematically investigated by combining high-temperature confocal laser scanning microscopy (HT-CLSM), microstructural characterization, and thermodynamic calculations. The focus was on the formation and transformation of ferrite, secondary-phase precipitation, and elemental segregation behavior, with comparisons made with 304 stainless steel. The effects of an Al addition and cooling rate were also explored. The results show that the solidification sequence of 310S stainless steel is L → L + γ → L + γ + δ → δ + γ, in which austenite nucleates early and grows rapidly, followed by the precipitation of a small amount of δ-ferrite in the later stages of solidification. In contrast, 304 stainless steel solidifies according to L → L + δ → L + δ + γ → δ + γ, with a rapid δ → γ transformation occurring after solidification. Compared with 304, 310S stainless steel exhibits a reduced ferrite fraction and a significantly increased σ phase content. The σ phase primarily precipitates directly from δ-ferrite (δ → σ), while M₂₃C₆ preferentially forms at grain boundaries and δ/γ interfaces, where δ-ferrite not only provides fast diffusion pathways for Cr but also nucleation sites. The solidification segregation sequence in 310S stainless steel is Cr > Ni > Fe, with Cr and Ni showing positive segregation and Fe showing negative segregation. The addition of Al does not alter the solidification mode of 310S stainless steel but refines austenite grains, reduces interdendritic solute enrichment, decreases segregation, lowers both the size and fraction of ferrite, and suppresses the precipitation of σ and M₂₃C₆ phases. This effect is mainly attributed to the reduction of δ/γ interfaces, which weakens the preferred nucleation sites for M₂₃C₆. Increasing the cooling rate enhances non-equilibrium solute segregation, promotes ferrite formation, inhibits the δ → γ transformation, and ultimately retains more ferrite; the intensified segregation further accelerates the δ → σ transformation. Full article

Argynnis hyperbius (Lepidoptera: Nymphalidae), as an important environmental indicator species, has shown a gradual decline in its species richness amid intensifying climate change and increasing environmental pressures. Screening for optimal reference genes is fundamental to studying their physiological and adaptive changes using RT-qPCR technology. In this study, 10 commonly used reference genes (ACT, α-TUB, AK, GAPDH, EF1α, BTF3, RPS3, RPL10, RPL32, and RPL27) were selected, and their expression stability under different developmental stages, genders, and temperature treatments was evaluated using the RefFinder website. The results indicated that selecting a pair of reference genes could achieve the most reliable normalization analysis under all experimental conditions. Specifically, AK and EF1α were the most stably expressed reference genes across different developmental stages; ACT and RPL32 showed the most stable expression in different adult sexes; and EF1α and RPL27 exhibited stable expression under different temperature treatments. Additionally, this study used EF1α and RPL32, the most stable reference genes from all results, to normalize and analyze the relative transcription levels of HSP90 under different temperatures, revealing significant differences between the 4 °C group and both the 26 °C and 37 °C groups. The findings of this study will significantly improve the reliability of RT-qPCR detection and lay a foundation for in-depth research on the gene expression, physiology, and biochemical mechanisms of A. hyperbius. Full article

Compact and efficient absorption refrigeration systems can effectively utilize waste heat and renewable energy when operated in a boiling-desorption mode, which maximizes the desorption rate. Hydrophobic membranes play a critical role in microchannel membrane-based generators; however, limited research has addressed bubble cross-membrane removal dynamics under boiling-desorption conditions, particularly the influence of membrane hydrophobicity. In this study, a two-phase flow bubble-removal model was developed to accurately represent boiling-desorption behavior. Numerical simulations were performed to investigate the effects of membrane hydrophobicity and heating power on bubble dynamics, wall temperature, venting rate, and channel pressure drop. Results show that bubble venting proceeds through four stages: nucleation and growth, liquid-film rupture with deformation, lateral spreading, and sustained vapor removal. Hydrophobicity effects become most significant from the third stage onwards. Increased hydrophobicity reduces wall temperature, with greater reductions at higher heat fluxes, and enhances venting performance by increasing total vapor removal and reducing removal time. Channel pressure fluctuations comprise high-frequency components from bubble growth and low-frequency components from venting-induced flow interruptions, with relative contributions dependent on hydrophobicity and heat flux. These findings provide new insights into bubble-removal mechanisms and offer guidance for the design and optimization of high-performance microchannel membrane-based generators. Full article

Canthaxanthin is a significant carotenoid that is synthesized by specific microorganisms. It has multiple functions and has been utilized in food and feed supply chains. This research focused on improving canthaxanthin production by Paracoccus bogoriensis PH1, an orange-pigmented bacterium isolated from hot springs. Canthaxanthin production was optimized in flask-scale cultures by varying the pH, temperature, nutritional sources, aeration rates, and agitation techniques. Flask culture cultivation indicated that canthaxanthin production by this strain was influenced by pH stress mechanisms, resulting in the establishment of a two-stage pH control (pH-shift) technique to enhance cell mass and pigment production. The optimum flask conditions were refined for application in a 1 L bioreactor. An optimized cultivation procedure was established utilizing a Polypeptone Sucrose Yeast Extract (PPSYE) medium, with a pH transition from 7 to 11, incubation at 40 °C, agitation at 250 rpm, and aeration at 2 vvm for 48 h. This process resulted in a 3.12-fold increase in total carotenoid content and a 1.61-fold increase in canthaxanthin production, achieving 0.84 ± 0.06 mg/L compared to pre-optimized flask cultures in TSYEB medium (pH 7 at 37 °C, 72 h). Purified canthaxanthin from P. bogoriensis PH1 exhibited antioxidant activity in the ABTS assay. Full article

Deep coalbed methane (CBM) resources possess significant potential. However, their development is challenged by geological characteristics such as high in situ stress and low permeability. Furthermore, existing production strategies often prove inadequate. In order to achieve long-term stable production of deep coalbed methane reservoirs and increase their final recoverable reserves, it is urgent to construct a scientific and reasonable drainage system. This study focuses on the deep CBM reservoir in the Daning-Jixian Block of the Ordos Basin. First, a thermal–hydraulic–mechanical (THM) multi-physics coupling mathematical model was constructed and validated against historical well production data. Then, the model was used to forecast production. Finally, key control measures for enhancing well productivity were identified through production strategy adjustment. The results indicate that controlling the bottom-hole flowing pressure drop rate at 1.5 times the current pressure drop rate accelerates the early-stage pressure drop, enabling gas wells to reach the peak gas production earlier. The optimized pressure drop rates for each stage are as follows: 0.15 MPa/d during the dewatering stage, 0.057 MPa/d during the gas production rise stage, 0.035 MPa/d during the stable production stage, and 0.01 MPa/d during the production decline stage. This strategy increases peak daily gas production by 15.90% and cumulative production by 3.68%. It also avoids excessive pressure drop, which can cause premature production decline during the stable phase. Consequently, the approach maximizes production over the entire life cycle of the well. Mechanistically, the 1.5× flowing pressure drop offers multiple advantages. Firstly, it significantly shortens the dewatering and production ramp-up periods. This acceleration promotes efficient gas desorption, increasing the desorbed gas volume by 1.9%, and enhances diffusion, yielding a 39.2% higher peak diffusion rate, all while preserving reservoir properties. Additionally, this strategy synergistically optimizes the water saturation and temperature fields, which mitigates the water-blocking effect. Furthermore, by enhancing coal matrix shrinkage, it rebounds permeability to 88.9%, thus avoiding stress-induced damage from aggressive extraction. Full article