Search Results (7,140)

To promote the sustainable application of self-compacting lightweight aggregate concrete (SCLC) in cold regions and mitigate river sand shortages by substitution, this study investigates the impact of manufactured sand (MS) content on its freeze–thaw resistance. However, the micro-damage mechanism and a reliable damage model for MS-SCLC under freeze–thaw conditions remain lacking. Five groups of SCLC with varied manufactured sand content (0%, 30%, 60%, 80%, and 100%) were prepared. This study examined the behavior of SCLC under freeze–thaw conditions, with a focus on its frost durability and microstructural evolution. Furthermore, an SCLC freeze–thaw damage model for the manufactured sand content was established based on the Weibull distribution. Increasing the manufactured sand content conferred benefits on the compressive strength loss rate and relative dynamic elastic modulus; however, it had adverse consequences for the apparent morphology and mass loss rate. In conclusion, the SCLC mixture containing 60% manufactured sand displayed superior frost resistance, demonstrating a mass loss rate of 4.79%, a relative dynamic elastic modulus of 0.624, and a compressive strength loss rate of 38.46% after 200 freeze–thaw cycles. The identified optimal MS content (60%) and the established Weibull-based damage model provide crucial quantitative guidance for designing durable MS-SCLC structures in freeze–thaw environments. Full article

The article is devoted to the issues of designing the exploitation of a seam deposit in the boundary areas of underground mines in terms of minimizing the risk of dynamic phenomena. Its main goal was to attempt to demonstrate the relationship between the method of extracting resources trapped in the boundary pillar and the magnitude of the induced seismicity of the rock mass accompanying this process. The substantive considerations concerned the single-wall model and were divided into two main parts—theoretical and verification. As part of the theoretical piece, based on model studies, a geomechanical assessment of the impact of the working face advance on changes in the stress–strain behaviour occurring in the burst-prone layer in terms of the possible loss of continuity of its original structure was carried out. The starting point for the key analyses were the results of numerical simulations based on the algorithms of S. Knothe and W. Budryk’s theories in combination with classical solutions of the mechanics of deformable bodies. Two variants of mining operations in a two-sided environment of goaf were considered, differing in the direction of progress, the degree of constraint of the start and end of the face advance, and mining circumstances in the vicinity of both sides of the advancing face. As part of the verification piece, the results of model analyses were related to an example polygon of a crossing longwall in one of the functioning, rockburst USCB hard coal mines. The scope of the research included a comparison of the experimentally indicated zones of occurrence of tremor-favourable effort processes in the roof of the seam with the actual location of the seismic phenomena foci recorded during the ongoing exploitation. The considerations included in the work formed the basis for formulating conclusions of a cognitive and applicable nature. Full article

Grain breakage serves as a primary causative factor for microbial infestation and oxidative deterioration, significantly diminishing product value and resulting in substantial grain waste and economic losses. The grain discharging process represents the most extensively involved and primary breakage-inducing stage throughout harvest handling and processing operations. However, impact and impact-induced breakage behavior during grain discharge are still poorly understood. To elucidate the impact-induced breakage behavior during grain discharge, this study first employed the discrete element method (DEM) to numerically simulate the discharging process, thereby quantifying the variation patterns of grain kinematic characteristics (e.g., velocity and attitude). Building upon the simulated kinematic data, a dedicated impact testing platform was constructed to investigate single-grain breakage. This enabled the determination of critical unit mass impact energy (along 90°: 106.4 J kg⁻¹; along 0°: 57.28 J kg⁻¹) and critical breakage velocity (along 90°: 14.59 m s⁻¹; along 0°: 10.70 m s⁻¹) under two extreme impact attitude conditions. By integrating the DEM-derived kinematics with the experimentally obtained breakage thresholds, a breakage probability zoning diagram for both large-scale and small-scale discharge processes was developed. Finally, leveraging this comprehensive understanding of the flow and breakage mechanics, theoretical models were successfully established to predict key engineering design parameters, including mass flow rate, impact force, and impact pressure. All models were validated and demonstrated excellent predictive capabilities. The research result is of guiding significance for the design of relevant parameters of discharge systems to minimize grain breakage loss to the greatest extent possible. Full article

Fixation is a necessary step in bamboo leaf powder processing and plays a decisive role in determining its color, aroma, and taste. It is irreplaceable for maintaining quality, stability, and forming unique sensory characteristics. In this study, optimal conditions for steamed bamboo leaf powder (SBL), baked bamboo leaf powder (BBL), and blanched bamboo leaf powder (BCBL) were determined by measuring chlorophyll content, color parameters, and enzyme inactivation. In addition, volatile organic compounds (VOCs) in bamboo leaf powder processed with different fixation methods were analyzed using gas chromatography–mass spectrometry (GC-MS), gas chromatography–olfactometry (GC-O), and relative odor activity value (ROAV). Steaming for 120 s, baking for 60 s, and blanching for 30 s effectively preserved color, with a* values of −1.37, −1.44, and −1.62, all superior to untreated bamboo leaf powder (UBL). Among them, BCBL showed the best color stability, with the lowest color difference (ΔE = 0.66) compared with fresh bamboo leaves (FBLs). Results showed that BBL retained the highest VOC abundance (15.67% of FBLs), followed by SBL (5.73%) and BCBL (5.48%). Hexanal, nonanal, linalool, and α-ionone were identified as key aroma contributors, forming green, fresh, and floral notes. Sensory differences were evident: SBL exhibited strong seaweed-like and roasted notes, BCBL showed partial loss of characteristic aromas, while BBL preserved grass, fruity, and woody attributes. These findings highlight the significant influence of fixation methods on aroma-active compounds and color stability, providing a theoretical basis for producing bamboo leaf powder with superior sensory quality. Full article

This study aimed to systematically characterize the pyrolysis characteristics and combustibility of six typical tree species across different altitude gradients in southwestern Yunnan, providing references for fuel management and selection of potential fire-resistant species in this region. Thermogravimetric analysis (heating rate: 20 °C·min⁻¹, air atmosphere) was employed to obtain TG-DTG curves of bark, branches, and leaves. The Coats–Redfern integral method was applied to calculate kinetic parameters, and principal component analysis was conducted for comprehensive combustibility evaluation. The results demonstrated the following: (1) The pyrolysis process of all species underwent the following four distinct stages: moisture evaporation, holocellulose decomposition, lignin decomposition, and ash formation. Among these, holo-cellulose decomposition constituted the primary mass loss stage. Significant differences in pyrolysis characteristics were observed among different plant parts, with leaves and bark exhibiting lower initial pyrolysis temperatures; (2) The activation energy ranged from 56.05 to 86.41 kJ·mol⁻¹ across different components, with branches requiring the highest energy for pyrolysis; (3) Principal component analysis based on multiple indicators yielded the following comprehensive combustibility ranking: Pinus yunnanensis > Betula alnoides > Lithocarpus henryi > Quercus acutissima > Cunninghamia lanceolata > Myrica rubra; and (4) The combustibility assessment results integrating multiple variables (total mass loss rate, stage-specific mass loss, activation energy, and ash content) showed significant differences from the analysis based solely on activation energy, verifying the necessity of a multi-dimensional comprehensive evaluation. Full article

Alkyd resins (ARs) represent a significant development in synthetic polymers, being among the oldest ones and playing a crucial role in numerous applications, especially within the coating sector. The trend is moving towards replacing non-renewable resources in the production of ARs with bio-based alternatives, with the goal of creating more sustainable binder materials as part of the transition to a bioeconomy. 2,5-Furandicarboxylic acid (FDCA) serves as a promising biomass-derived “building block” to replace non-renewable petroleum-derived aromatic diacids and anhydrides in AR synthesis. Various vegetable oils, including sunflower seed (SFO) and linseed oils (LSO), were utilized along with pentaerythritol (P) and glycerol (G) as polyols. FTIR and ¹H NMR spectroscopies were conducted for the verification of alkyd structures. The synthesized ARs were assessed for their physico-chemical properties, including acid value, hydroxyl value, color, density, and viscosity. The performance of the resulting alkyd coatings, which are crucial for their commercial applications, was examined. Key factors such as drying time, hardness, adhesion, wettability, chemical and corrosion resistance, and UV stability were analyzed. All synthesized FDCA-based alkyd coatings demonstrate outstanding adhesion, good thermal stability up to 220 °C, and barrier properties for steel with |Z|_0.02Hz ~10⁶–10⁷ Ohm cm⁻², which render them suitable for the processing requirements of indoor coating applications. The higher temperature at 50% mass loss (T₅₀) for SFO-P (397 °C) and LSO-P (413 °C) as compared to SFO-G (380 °C) and LSO-G (394 °C) indicated greater resistance to thermal breakdown when pentaerythritol was used as a polyol. Replacing glycerol with pentaerythritol in FDCA-based ARs resulted in a viscosity increase of 1.2–2.4 times and an enhancement in hardness from 2H to 3H. FDCA-based ARs exhibited decreased tack-free time, enhanced thermomechanical properties, and similar hardness as compared to phthalic anhydride-based ARs, underscoring the potential of FDCA as a sustainable alternative to phthalic anhydride in the formulation of ARs, integrating a greater proportion of renewable components for wood coating applications. Full article

With the rapid development of infrastructure and the need to protect natural ecosystems, manufactured sand is used to replace river sand in concretes. To compare the deterioration patterns of concretes made with different sands, C50 specimens using basalt (C50X), tuff (C50N), and granite (C50H) manufactured sands and river sand (C50T) were prepared, then tested outdoors by full burial in a sulfate saline soil and indoors by accelerated freeze–thaw in a sulfate solution. The outdoor experiments indicate that C50X deteriorated the slowest, whereas the resistance to mass loss ranking was: C50X > C50H > C50N > C50T. In the indoor freeze–thaw experiments, C50X also performed best, retaining 51% relative dynamic modulus of elasticity (RDME) after 450 cycles. X-ray diffraction and scanning electron microscopy showed that C50T was weakened by abundant MgSO₄·7H₂O crystals, while C50X formed a denser matrix that limits salt-crystallization expansion. Moreover, a GM(1,1)-Markov model was developed to forecast long-term durability. For C50X, the model predicted an estimated service life of 68 months in the outdoor environment, at which point it is projected to reach the 5% mass loss failure threshold. Separately, it forecasted that the RDME would remain above 41% after 450 indoor freeze–thaw cycles. Full article

A new experiment was conducted to determine the corrosion rates of different geometric structures (vertical plate, horizontal plate, cube, and sphere) with the same surface area of pure magnesium in a saltwater immersion environment of 3.5% NaCl for 108 h, illustrating a clear geometry effect arising from local boundary layer water flow. Magnesium was chosen as an idealized material because of its small electrochemical potential. The different corrosion mechanisms were analyzed and quantified by measuring the surface roughness (localized corrosion) via laser profilometry, mass loss (general corrosion) by weighing specimens, localized and intergranular corrosion via Scanning Electron Microscopy and Optical Microscopy, and total corrosion via hydrogen measurements. Although the corrosion rates were very similar at the beginning of the tests, the vertical and horizontal plates gave corrosion rates greater than the cube and sphere shortly after the tests started. Water circulation induced by hydrogen gas bubbles caused a greater corrosion rate at the edges of the plates and cube. These results indicate that a structure’s geometric edges should be made smoother to lessen corrosion effects in design. Also, when one is designing for corrosion resistance of a structural component, our results demonstrate that the designer must consider the fluid dynamics in the boundary value problem surrounding the structural component, since the geometric shape changes the corrosion rate. Full article

Wood is a renewable and sustainable environmentally friendly building material. With proper design, it can help buildings achieve lower carbon emissions. However, since wood is a flammable material, its combustion performance in fires has attracted attention. In modern timber structures, glulam is a widely used engineered wood product. Thus, in this paper, glulam specimens made of four kinds of commonly used soft-wood species were used to compare their combustion performance, and the cone calorimeter method was employed. The indicators including time to ignition, heat release rate per unit area, total heat release per unit area, specific extinction area per unit mass, mass of residue, yield of CO and yield of CO₂ were evaluated and compared. The results showed that all the glulam specimens would experience cracking wood and adhesive layer. The time to ignition and peak mass loss rate of the four softwood species in the study was positively correlated with their density. Among these species, Spruce exhibited the highest peak heat release rate and the highest peak CO₂ yield but lowest smoke production, while Douglas fir had a relatively late CO production time and the lowest mass loss percentage, Larch had the lowest heat release rate and total heat release. This study provides fundamental data for the selection of wood structural materials and for future research on wood flame-retardant treatments. Full article

Obesity is a complex, multifactorial disease wherein the excessive accumulation of adipose tissue leads to adverse health outcomes, such as diabetes, cardiovascular disease and musculoskeletal disorders. Obesity also impacts both the risk and the clinical prognosis of heart failure (HF). The accumulation of adipose tissue results in metabolic dysregulation, including increased levels of pro-inflammatory cytokines and adipokines. These alterations are strongly associated with the development and progression of HF. Another significant comorbidity in patients with HF is sarcopenia, characterized by progressive loss of muscle mass and strength, affecting the quality of life. The study aims to critically synthesize the mechanisms by which modern pharmacological treatments—sodium-glucose cotransporter-2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dual GIPR/GLP-1R agonists—modulate body mass composition, and to analyze the specific implications of these changes (e.g., visceral fat reduction versus lean mass loss) for heart failure (HF) prognosis and management. Full article

Sarcopenia, the loss of skeletal muscle mass and function, is a common and critical comorbidity in patients with conditions frequently managed by interventional radiologists, such as liver cirrhosis and hepatocellular carcinoma (HCC). Interventional radiologists are well positioned to incorporate opportunistic screening for this condition during routine preprocedural cross-sectional imaging. This review summarizes the current evidence on how sarcopenia influences patient outcomes and informs procedural planning across a spectrum of interventional radiology (IR) procedures. In transarterial embolizations for HCC, sarcopenia is a robust independent predictor of increased mortality, with meta-analyses suggesting it may also predict a lower tumor response rate. Even earlier stages of muscle loss (pre-sarcopenia) are associated with worse survival, and dynamic changes in muscle mass post-treatment can serve as a biomarker for tumor progression. For patients undergoing transjugular intrahepatic portosystemic shunt, pre-procedural sarcopenia and myosteatosis are strong, independent predictors of both mortality and the development of post-procedural hepatic encephalopathy, with the presence of both conferring the highest risk. In the context of pre-surgical portal vein embolization, sarcopenia is consistently associated with impaired volumetric liver growth, although this does not always translate to worse short-term surgical outcomes, as functional liver regeneration may be preserved. Following percutaneous liver tumor ablation, sarcopenia is a powerful predictor of overall mortality, while its role in predicting tumor recurrence remains an area of active investigation. Finally, in non-oncologic interventions for peripheral arterial disease, sarcopenia is highly prevalent and is associated with worse functional status, higher mortality, and a significantly increased risk of major amputation after endovascular therapy. In conclusion, sarcopenia is a powerful and readily available biomarker that provides crucial prognostic information—often independent of standard clinical scores—across a wide spectrum of IR procedures. The consistent evidence supports integrating sarcopenia evaluation into routine practice to enhance risk stratification, improve patient counseling, and guide multidisciplinary treatment planning. Full article

Far-infrared imaging is a powerful tool in night vision and temperature measurement, with broad applications in military, astronomy, meteorology, industrial, and medical fields. However, conventional imaging lenses face challenges such as large size, heavy weight, and difficulties in miniaturization, which hinder their integration and use in applications with strict requirements for mass and volume, such as drone-based observation and imaging. To address these limitations, we designed a dual-plane diffractive optical lens optimized for the 10.9–11.1 μm wavelength band with a 0.2 μm bandwidth. By optimizing parameters including focal length, spot size, and field of view, we derived the phase distribution of the lens and converted it into the surface sag. To enhance diffraction efficiency and minimize energy loss, the lens was fabricated using a continuous phase surface on single-crystal Germanium. Finally, an imaging system was constructed to achieve clear imaging of various samples, demonstrating the feasibility of both the device and the system. This approach shows great potential for applications requiring lightweight and miniaturized solutions, such as infrared imaging, machine vision, remote sensing, biological imaging, and materials science. Full article

Fractured lost circulation remains a major drilling challenge due to low compatibility between conventional plugging materials and fractures. By utilizing thermosetting resin emulsification and high-temperature crosslinking coalescence, this study developed a temperature-activated nanomaterial enhanced liquid–solid phase transition plugging emulsion. The system adapts to varying fracture apertures, forming plugging particles with a broad size distribution and high strength upon thermal activation. The structural characteristics, mechanical properties, and fracture-plugging performance of the plugging particles were systematically investigated. Results demonstrate that the optimized system, comprising 8 wt.% emulsifier, 0.16 wt.% dispersant, 0.4 wt.% crosslinker, 0.4 wt.% viscosifier, 70 wt.% distilled water, and 2 wt.% nano-silica (all percentages relative to epoxy resin content), can produce particles with a size of 1–5 mm at formation temperatures of 80–120 °C. After 16 h of thermal aging at 180 °C, the particles exhibited excellent thermal stability and compressive strength, with D(90) degradation rates of 3.07–5.41%, and mass loss of 0.63–3.40% under 60 MPa. The system exhibits excellent injectability and drilling fluid compatibility, forming rough-surfaced particles for stable bridging. Microscopic analysis confirmed full curing in 140–180 min. Notably, it sealed 1–5 mm fractures with 10 MPa pressure, enabling adaptive plugging for unknown fracture apertures. Full article

A comprehensive understanding of the denitration kinetics of nitrocellulose-based propellants is crucial for optimizing combustion performance and achieving controllable fabrication. However, most existing studies rely on a single kinetic model, which is restricted by formulation composition and grain geometry, limiting their general applicability. In this work, the denitration rate was quantified using the change in explosion heat, introducing an energy-based characterization approach instead of traditional mass-loss measurements. Three kinetic models (the shrinking-core, pseudo-homogeneous, and Avrami models) were employed to identify the rate-controlling step. The shrinking-core model provided the most accurate description of the process. At moderate reagent concentrations (8 wt.% and 12 wt.%) and temperatures (65–75 °C), denitration was primarily reaction-controlled, while at higher temperatures (80 °C), internal diffusion resistance became significant. The apparent activation energy ranged from 69.8 to 73.7 kJ·mol⁻¹, confirming that chemical reaction is the dominant mechanism. This study refines the kinetic understanding of nitrocellulose denitration and provides theoretical guidance for the controlled fabrication of gradient nitrocellulose propellants with tunable progressive-burning behavior. Full article

The use of artificial oxygenation to counteract the effects of hypoxia and improve living standards in high-altitude, low-oxygen settings is widespread. A recognized consequence of this intervention is that it elevates the risk of fire occurrence. In this study, we simulated a real fire environment with low-pressure oxygen enrichment in a plateau area. A new multi-measuring apparatus was constructed by integrating an electronic control cone heater and a low-pressure oxygen enrichment combustion platform to enable the simultaneous measurement of multiple parameters. The combined effects of varying oxygen concentrations and thermal irradiance on the combustion behavior of wood plastic composites (WPCs) under specific low-pressure conditions were investigated, and alterations in crucial combustion parameters were examined and evaluated. Increasing the oxygen concentration and heat flux significantly reduced the ignition and combustion times. For instance, at 50 kW/m², the ignition time decreased from 75 s to 16 s as the oxygen concentration increased from 21% to 35%. This effect was suppressed by higher heat fluxes. Compared with low oxygen concentrations and low thermal radiation environments, the ignition time of the material under high oxygen concentrations and high thermal radiation conditions was shortened by more than 78%, indicating that its flammability is enhanced under extreme conditions. Higher oxygen concentrations enhanced the heat feedback to the fuel surface, which accelerated pyrolysis and yielded a more compact flame with reduced dimensions and a color transition from blue-yellow to bright yellow. This intensified combustion was further manifested by an increased mass loss rate (MLR), elevated flame temperature, and a decline in residual mass percentage. The combustion of WPCs displayed distinct stage characteristics, exhibiting “double peak” features in both the MLR and flame temperature, which were attributed to the staged pyrolysis of its wood fiber and plastic components. Full article