Search Results (111)

Ti150 has potential applications in aeroengine components. However, the lack of research on its flame resistance, combustion behavior, and mechanisms makes it difficult to assess the risk of “titanium fire” and leaves fire protection design without theoretical support. This study aimed to determine the combustion resistance of Ti150 and elucidate its combustion behavior and mechanisms to address these issues. Through comparative Promoted Ignition-Combustion (PIC) tests between Ti150 and TC11 alloys, microstructural characterization, and thermodynamic/kinetic analyses, the following conclusions were drawn. Ti150 alloy exhibited a higher critical oxygen pressure and a higher ignition temperature but a significantly faster burning velocity, compared with TC11 alloy. The relationship between pressure and ignition temperature was in good agreement with the modified Frank-Kamenetskii ignition model. The ignition activation energy of Ti150 alloy was determined to be 118.41 kJ/mol, which was approximately 21% higher than that of TC11 alloy (97.72 kJ/mol). Moreover, post-combustion microstructural observations of Ti150 alloy revealed a higher oxygen content in the melting zone and an enrichment of Zr at the solid–liquid interface, both of which contribute to the higher burning velocity of Ti150 alloy compared with TC11 alloy. Full article

This study investigates the structural performance of bolted T-joints in steel elements exposed to elevated temperatures, with a focus on the influence of fire-resistant coatings. A total of 36 T-joint specimens were tested under four different temperature levels (300 °C, 450 °C, 600 °C, and 900 °C), incorporating three IPE section sizes and three fire-resistant paint thicknesses (200 µm, 400 µm, and 600 µm). The experimental program aimed to evaluate the combined effects of temperature, cross-sectional geometry, and coating thickness on the axial load-bearing capacity and deformation characteristics of T-joints. To examine the influence of web geometry, T-sections were designed in accordance with Eurocode 3, and the flange-to-web thickness ratios (tf/tw) were varied between 1.52 and 1.58. Results showed that applying 200 µm and 400 µm coatings at 300 °C and 450 °C improved the axial load capacity by approximately 10% and 20%, respectively, compared to uncoated specimens. However, effective fire protection at higher temperatures (600 °C and 900 °C) required a minimum coating thickness exceeding 400 µm. Finite Element Models developed using ABAQUS (2017) were designed to predict post-fire load–displacement behavior, stiffness degradation, and failure modes. Predictions were validated against experimental results, with deviations ranging from 0.97% to 9.73% for maximum load and 1.18% to 42.13% for energy dissipation, confirming the model’s reliability in simulating the thermo-mechanical response of steel joints under fire exposure. Full article

Wildfire behavior and post-fire effects are strongly modulated by terrain, yet the relative influence of individual topographic factors on burn severity remains incompletely quantified at landscape scales. The Composite Burn Index (CBI) provides a field-calibrated measure of severity, but large-area analyses have been hampered by limited plot density and cumbersome data extraction workflows. In this study, we paired 6150 CBI plots from 234 U.S. wildfire events (1994–2017) with 30 m SRTM DEM, extracting mean elevation, slope, and compass aspect within a 90 m buffer around each plot to minimize geolocation noise. Topographic variables were grouped into ecologically meaningful classes—six elevation belts (≤500 m to >2500 m), six slope bins (≤5° to >25°), and eight aspect octants—and their relationships with CBI were evaluated using Tukey HSD post hoc comparisons. Our findings show that all three factors exerted highly significant influences on severity (p < 0.001): mean CBI peaked in the 1500–2000 m belt (0.42 higher than lowlands), rose almost monotonically with steepness to slopes > 20° (0.37 higher than <5°), and was greatest on east- and northwest-facing slopes (0.19 higher than south-facing aspects). Further analysis revealed that burn severity emerges from strongly context-dependent synergies among elevation, slope, and aspect, rather than from simple additive effects. By demonstrating a rapid, reproducible workflow for terrain-aware severity assessment entirely within GEE, the study provides both methodological guidance and actionable insights for fuel-management planning, risk mapping, and post-fire restoration prioritization. Full article

As a typical steel-concrete composite structure, Concrete-Filled Steel Tubular (CFST) structures utilize the synergistic mechanical advantages of steel and concrete, showing good performance in bearing capacity, ductility and fire resistance, and becoming important in modern buildings. However, CFST structures may suffer hazards like fire, which causes performance degradation affecting subsequent seismic behavior. To study seismic performance of fire-damaged CFST column-steel beam joints, low-cycle repeated loading experiments were carried out on 3 specimens: 2 exposed to different fire temperatures and 1 ambient temperature control. Tests examined hysteretic behavior, ductility, energy dissipation, bearing capacity and stiffness degradation under post-fire axial compression ratios. Results show fire-damaged specimens had similar ductile failure modes to the control. Despite high temperatures, they maintained relatively full hysteretic curves and strong energy dissipation, but with reduced bearing capacity, increased deformation, nonlinear ductility growth, and more significant degradation at higher temperatures. Full article

Wildfires have become increasingly frequent and destructive environmental hazards, especially in boreal ecosystems facing prolonged droughts and temperature extremes. This study presents an integrated spatio-temporal framework that combines Spatio-Temporal Density-Based Spatial Clustering of Applications with Noise (ST-DBSCAN), Fire Radiative Power (FRP), and the differenced Normalized Burn Ratio (ΔNBR) to characterize the dynamics and ecological impacts of large-scale wildfires, using the extreme 2023 Quebec fire season as a case study. The analysis of 80,228 VIIRS fire detections resulted in 19 distinct clusters across four fire zones. Validation against the National Burned Area Composite (NBAC) showed high spatial agreement in densely burned areas, with Intersection over Union (IoU) scores reaching 62.6%. Gaussian Process Regression (GPR) revealed significant non-linear relationships between FRP and key fire behavior metrics. Higher mean FRP was associated with both longer durations and greater burn severity. While FRP was also linked to faster spread rates, this relationship varied by zone. Notably, Fire Zone 2 exhibited the most severe ecological impact, with 83.8% of the area classified as high-severity burn. These findings demonstrate the value of integrating spatial clustering, radiative intensity, and post-fire vegetation damage into a unified analytical framework. Unlike traditional methods, this approach enables scalable, hypothesis-driven assessment of fire behavior, supporting improved fire management, ecosystem recovery planning, and climate resilience efforts in fire-prone regions. Full article

Natural carbonate stones such as limestones and marbles are widely used in heritage and contemporary architecture, yet their durability is increasingly threatened by wildfire-related thermal stress. Since water transport plays a key role in stone deterioration, understanding how high temperatures affect hydric behavior is critical for conservation. This study investigates thirteen Portuguese carbonate lithotypes (including marbles, limestones, a travertine, and a breccia) exposed to temperatures of 300 °C and 600 °C. Capillary absorption and open porosity were measured, alongside Leeb hardness (HL) and ultrasonic pulse velocity (UPV), to evaluate their predictive capacity for post-fire moisture behavior. Results show that thermal exposure increases porosity and capillary uptake while reducing mechanical cohesion. Strong correlations between UPV and hydric parameters across temperature ranges highlight its reliability as a non-invasive diagnostic tool. HL performed well in compact stones but was less consistent in porous or heterogeneous lithologies. The findings support the use of NDT tests, like UPV and HL, for rapid post-fire assessments and emphasize the need for lithology-specific conservation strategies. Full article

Objectives: This study assessed the effectiveness of a cognitive behavioral therapy (CBT)-based fine dust education program, grounded in the Health Belief Model (HBM), on elementary students’ fine dust knowledge, related behaviors, and mental health (depression, anxiety, stress, sleep quality). Methods: From September to November 2024, 95 students (grades 4–6) living near a coal-fired power plant in midwestern South Korea were assigned to either an intervention group (n = 44) or a control group (n = 51). The intervention group completed a three-session CBT-based education program; the control group received stress management education. Assessments were conducted at weeks 1, 2, 4, and 8 using standardized mental health and behavior scales (PHQ: Patient Health Questionnaire, GAD: Generalized Anxiety Disorder Assessment, PSS: Perceived Stress Scale, ISI: Insomnia Severity Index). Results: A chi-square test was conducted to compare pre- and post-test changes in knowledge and behavior related to PM2.5. The intervention group showed significant improvements in seven fine dust-related knowledge and behavior items (e.g., PM2.5 awareness rose from 33.3% to 75.0%; p < 0.05). The control group showed limited gains. Regarding mental health, based on a mixed-design ANCOVA, anxiety scores significantly declined over time in the intervention group, with group and interaction effects also significant (p < 0.05). Depression scores showed time effects, but group and interaction effects were not significant. No significant changes were observed for stress, sleep, or group × PM2.5 interactions. Conclusions: The CBT-based education program effectively enhanced fine dust knowledge, health behaviors, and reduced anxiety among students. It presents a promising, evidence-based strategy to promote environmental and mental health in school-aged children. Full article

In the Mediterranean region, the high frequency of fire events is combined with climatic conditions that hinder vegetation recovery. This underscores the urgent need for a post-fire restoration of natural ecosystems and implementation of emergency rehabilitation measures to prevent further degradation. In this study, we investigated the performance of three types of erosion control structures (log dams, log barriers, and wattles), two years after fire, in three Mediterranean areas that were burnt by severe forest fires in 2021. The wooden structures’ ability to infiltrate precipitation was evaluated by 100 infiltration experiments in 25 plots, one and two years after the wildfires. The unsaturated hydraulic conductivity K was determined at two zones formed between consecutive wooden structures, i.e., the erosion zone (EZ) where soil erosion occurs, and the deposition zone (DZ) where the soil sediment is accumulated. These zones showed significant differences concerning their hydraulic behavior, with DZ presenting enhanced infiltration ability by 130 to 300% higher compared to EZ, during both years of measurements. The findings suggest that the implementation of emergency restoration actions after a wildfire can highly affect the burned forest soils’ ability to infiltrate water, preventing surface runoff and erosion, whereas specific structures such as the log dams can be even more effective. Full article

In protected areas of the Brazilian savannas (Cerrado), Land Surface Phenology (LSP) is influenced by both precipitation and fire, but the nature of these relationships remains unexplored. Here, we assessed the impacts of precipitation and fire on LSP metrics derived from the Normalized Difference Vegetation Index (NDVI) at Emas National Park (ENP). Using TIMESAT, along with the 250-m Moderate Resolution Imaging Spectroradiometer (MODIS) MOD13Q1 and 30-m Harmonized Landsat Sentinel (HLS) products, we investigated these effects in both grassland and woodland areas. To evaluate the effects of precipitation, we identified the driest and wettest seasonal cycles between 2002 and 2023 and analyzed the relationships between accumulated rainfall during the rainy season and each of the 13 TIMESAT metrics. To assess the effects of fire, three major events were examined: 1 September 2005 (affecting 45% of the park’s area), 12 August 2010 (90%), and 10 July 2021 (21%). The burned grassland area and the subsequent vegetation recovery following the 2021 event were analyzed in detail using a non-burned control site and LSP metrics extracted from the HLS product, covering both pre- and post-disturbance cycles. The results indicated that the metrics most positively correlated to precipitation were Amplitude (AMP), End of Season (EOS), Large and Small Seasonal Integrals (LSI and SSI), and Rate of Increase at the Beginning of the Season (RIBS). The highest correlation coefficients were found in woodland areas, which were less affected by fire disturbance than grassland areas. Similar trends were observed in the behavior of AMP, EOS, and SSI in response to both precipitation and fire, with fire exerting a stronger influence. By decoupling the fire effects from rainfall influence using the control site, we identified Base Level (BL), SSI, EOS, AMP, and Values at the End and Start of the Season (VES and VSS), as the metrics most sensitive to fire and subsequent vegetation recovery in burned areas. The effects of fire were evident for most metrics, both during the disturbance cycle and in the post-fire cycle. Our study underscores the importance of combining MODIS and HLS time series to understand vegetation phenology in the Cerrado. Full article

Post-earthquake fires (PEFs) represent a complex, cascading hazard in which seismic damage creates ignition conditions that can overwhelm urban infrastructure and severely compromise structural integrity. Despite growing scholarly attention, the literature on PEFs remains fragmented across disciplines, lacking a consolidated understanding of structural vulnerabilities, urban-scale impacts, and response strategies. This study presents a systematic and thematic synthesis of 54 peer-reviewed articles, identified through a PRISMA-guided screening of 151 publications from the Web of Science Core Collection. By combining bibliometric mapping with thematic clustering, the review categorizes research into key methodological domains, including finite element modeling, experimental testing, probabilistic risk analysis, multi-hazard frameworks, urban simulation, and policy approaches. The findings reveal a dominant focus on structural fire resistance, particularly of seismically damaged concrete and steel systems, while highlighting emerging trends in sensor-based fire detection, AI integration, and urban resilience planning. However, critical research gaps persist in multi-hazard modeling, firefighting under partial collapse, behavioral responses, and the integration of spatial, infrastructural, and institutional factors. This study proposes an interdisciplinary research agenda that connects engineering, urban design, and disaster governance to inform adaptive, smart-city-based strategies for mitigating fire risks in seismic zones. This work contributes a comprehensive roadmap for advancing post-earthquake fire resilience in the built environment. Full article

This study investigates the mineralogical, chemical, and fusibility characteristics of feldspar samples collected from eight pegmatitic bodies in central Portugal. The primary aim was to evaluate their suitability for use in ceramic applications, driven by the need to valorize local georesources, reduce dependence on imported raw materials, and contribute to the sustainability and competitiveness of the Portuguese ceramic sector. Samples were analyzed by X-Ray Diffraction (XRD), X-ray Fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Firing tests were performed to assess fusibility, whiteness, and visible impurity behavior. Results indicate that seven of the eight samples were dominated by a combination of microcline and albite, with minor amounts of quartz and muscovite. Crystallinity indices varied across samples, reflecting differences in mineral order and thermal reactivity. Chemical compositions showed acceptable levels of SiO₂ and Al₂O₃, and total alkali contents (Na₂O + K₂O) between 10% and 16%, aligning with industrial standards for ceramic raw materials. The Fe₂O₃ contents were below 0.3% in most samples, suggesting favorable conditions for whiteness upon firing. Loss on ignition (LOI) values were generally low, except for one sample rich in muscovite. Fusibility behavior varied significantly between samples, with albite-rich samples showing lower melting points and better flow characteristics, while microcline-dominant samples required higher temperatures for vitrification but contributed to structural stability. The K₂O/Na₂O ratio presented values favoring earlier softening and fluxing. Whiteness revealed that samples with low Fe₂O₃ and TiO₂ content, particularly those with low mica content, achieved the best aesthetic outcomes post-firing. Full article

To investigate the seismic performance of steel tube-reinforced concrete (ST-RC) columns after fire on one side, this study employs numerical simulation and theoretical analysis methods. A numerical analysis model of ST-RC columns post-fire is established using ABAQUS to simulate and analyze their seismic performance under cyclic loading. The characteristics of the hysteresis curves of ST-RC columns after fire on one side under cyclic loading are described in detail. Comparisons are made between the skeleton curves, ductility, stiffness degradation, and energy dissipation capacity of ST-RC columns under three conditions: unexposed to fire, exposed to fire on all sides, and exposed to fire on one side. Finally, multiple influencing factors, including heating time, slenderness ratio, section size, core area ratio, external concrete strength, reinforcement ratio, and load ratio, are selected for parametric analysis of the ductility coefficient, stiffness, and viscous damping coefficient. Mathematical formulas for the ductility coefficient, stiffness, and viscous damping coefficient of ST-RC columns after fire on one side under cyclic loading are derived through regression analysis. The results show that the seismic performance of ST-RC columns is attenuated after fire on one side, and the ductility and initial stiffness of ST-RC columns decreases by 5.62% and 24.69%, respectively, compared with those without fire. The energy dissipation capacity of the ST-RC column increases significantly when it enters the plastic deformation stage under the action of reciprocating load. Full article

With increasing wildfire severity and duration driven by climate change, accurately predicting fire behavior over extended time frames is critical for effective management and mitigation of such wildfires. Fire propagation models play a pivotal role in these efforts, providing simulations that can be used to strategize and respond to active fires. This study examines the fire area simulator (FARSITE) model’s performance in simulating recent wildfire events that persisted over 24 h with limited firefighting intervention in mostly remote access areas across diverse ecosystems. Our findings reveal key insights into a prolonged wildfire scenarios potentially informing improvements in operational fire management and long-term predictive accuracy, as the area comparisons indexes showed reasonable results between the detected fires from the fire information for resource management systems (FIRMSs) in the first 24 h of the fire and the following days. A case study of a recent wildfire in Madeira Island highlights the integration of real-time weather predictions and post-event weather data analysis. This analysis underscores the potential of combining accurate forecasts with retrospective validation to improve predictive capabilities in dynamic fire environments, which guided the development of a software platform designed to analyse ongoing wildfire events in real-time, leveraging image satellite data and weather predictions. Full article

The Orinoquía region of Colombia includes diverse ecosystems such as riparian forests and seasonal savannas, which play vital roles as biodiversity reservoirs. However, increased fire activity, driven by both natural and anthropogenic pressures, poses mounting threats to these ecosystems. Despite their importance, the effects of fire on faunal communities, especially in transitional habitats, are not well understood. Understanding biodiversity responses to fire across different recovery stages is essential for conservation planning. This study aimed to assess the effects of fire occurrence and recovery time on dung beetle communities as an indicator of ecosystem resilience. We analyzed taxonomic responses—including species richness, abundance, and Hill diversity indices (D₀, D₁, D₂)—as well as functional traits such as guild richness, biomass, and food relocation behavior, across riparian forest–savanna ecotones under varying fire histories. Our results indicate that recent fires (≤1 year) and high fire frequencies (4–5 events) negatively affect species diversity and abundance. Dominance by a few disturbance-tolerant species, such as Digitonthophagus gazella, was observed in burned savannas, while forest habitats supported both rare and dominant taxa. Despite taxonomic declines, functional redundancy was maintained, largely due to the prevalence of small-bodied species. However, we observed a general resilience effect in which core species contributed to postfire community reassembly. Functional redundancy was maintained, with small dung beetles dominating the biomass and guild composition. The conservation status of transitional habitats, particularly the forest–savanna ecotone, played a critical role in postfire dung beetle community restructuring. The presence of resilient assemblages highlights the importance of dung beetles in sustaining key ecosystem functions following fire events. These findings underscore the potential of dung beetles as bioindicators for postfire monitoring and emphasize the need for improved fire management strategies in sensitive ecosystems. Full article

The potential contribution of the ion channels that control the excitability of the midline and intralaminar nuclei of the thalamus to the modulation of behaviors has not been well studied. In this study, we used both global genetic deletion (knock-out, KO) and thalamus-specific molecular knock-down (KD) approaches to investigate the role of thalamic Ca_V3.1 T-type calcium channels (T-channels) in fear learning and fear responses. Previously, we have shown that the dominant subtype of T-channels in the central medial nucleus of the thalamus (CMT) is the Ca_V3.1 isoform and that CMT neurons from Ca_V3.1 KO animals have decreased burst firing. By specifically knocking down Ca_V3.1 T-channels in the CMT using the shRNA approach, we also reduced burst firing without affecting the tonic firing mode of the transfected neurons. We report that global Ca_V3.1 KO animals showed stronger freezing behaviors during both the conditioning and testing phases of contextual fear conditioning, while CMT-specific Ca_V3.1 KD mice only had stronger fear responses during testing. In contrast, the cue-mediated fear responses were similar between Ca_V3.1 KO and Ca_V3.1 KD mice and the controls. Our findings validate thalamic Ca_V3.1 T-channels as a potential new target for the development or treatment of different psychiatric diseases, such as post-traumatic stress disorder, schizophrenia, anxiety, and substance abuse disorders. Full article