Search Results (190)

Given the increasing frequency, severity, and socioecological impacts of wildfires, there is an urgent need for robust frameworks to better characterize fire behavior and flammability patterns across ecosystems to support early warning, mitigation, and management strategies. However, flammability remains difficult to quantify and scale, as it involves multiple interacting components that are typically measured at the bench scale. This study aimed to establish empirical links between spectral information, plant traits, and flammability metrics, and to scale these relationships to satellite imagery to translate these metrics into a spatial context. We combined laboratory spectroscopy, plant trait measurements including leaf mass per area, carbon, and cellulose, and combustion experiments using a simple and reproducible burning device. In total, 84 samples were collected and analysed, allowing us to characterise how spectral signatures relate to vegetation traits and fire behaviour. Spectral indices were developed to estimate plant traits, which were subsequently used as predictors in flammability models. These models were then transferred to Environmental Mapping and Analysis Program (EnMAP) hyperspectral imagery to derive spatial estimates across eucalypt forests and grasslands of the Australian Capital Territory (ACT). Spectral information distinguished fuel types and captured variability of the plant traits, while these traits showed associations with combustion behaviour. Based on these links, the best-performing model predicted the rate of temperature increase, a combustibility metric, in eucalypt forests (R² = 0.70; Root Mean Square Error = 32.48 °C/s). In contrast, grassland models showed limited predictive performance, likely due to weaker relationships between plant traits and flammability metrics. Overall, this study demonstrates a practical and scalable approach for deriving flammability maps from hyperspectral and in situ data, highlighting the potential of plant-trait-based remote sensing. The resulting maps should not be interpreted as standalone fire risk products, but rather as a characterization of the structural and biochemical drivers of flammability. The main constraint of this work is the limited sample size. Future research should expand spatial and temporal coverage to better capture vegetation variability and enable the inclusion of independent validation datasets. Exploring alternative combustion protocols and testing more advanced spectral modelling approaches for trait estimation would provide additional insights. Full article

Potassium nitrate and sorbitol (KNSB) is a promising low-cost solid propellant for aerospace, characterized by stable combustion and a low pressure exponent. However, its application is constrained by a deficiency in detailed numerical simulation studies for solid rocket motors (SRMs). This study develops a comprehensive numerical model for a KNSB SRM, incorporating dynamic mesh techniques to simulate real-time burning surface regression. Steady-state internal flow field analysis proves to be well-validated by literature data, with combustion pressure and thrust errors of 7.7% and 3.2%, respectively. Increasing oxidizer mass fraction from 57.5% to 70% leads to a significant temperature rise of 22.15%. Dynamic simulations reveal that thrust and pressure initially increase after ignition but later decline as the regressing surface reduces gas generation below the nozzle exhaust rate. Comparison with literature yields an average thrust error of 4.9%, with simulated trends matching documented behavior well. This research provides a robust reference for performance prediction and supports further development of KNSB SRMs. Full article

Magnesium potassium phosphate cement (MKPC) is a promising bone repair material but suffers from excessively rapid setting time (typically within minutes) that limits clinical application. This study systematically investigates trimagnesium phosphate (TMP) as a candidate retarding additive for MKPC. TMP was used to partially replace dead-burned magnesium oxide at replacement levels of 0%, 10%, and 15% by mass. The effects of TMP content, water-to-cement ratio (0.17–0.23), and magnesium-to-phosphate molar ratio (4–10) on setting time, fluidity, hydration kinetics, compressive strength, and microstructure were comprehensively evaluated. Results show that TMP effectively extends the setting time from 9–13 min (without TMP) to 10–19 min, providing a working window that may be suitable for biomedical applications requiring extended handling time. Notably, 10% TMP incorporation enhances early compressive strength, with 1-day strength reaching 35.2 MPa compared to 28.5 MPa for control samples. Hydration heat analysis reveals TMP moderates the acid-base reaction kinetics through its slower dissolution rate compared to MgO. Microstructural characterization shows TMP promotes the formation of denser K-struvite crystals with refined microstructure. The optimal TMP dosage of 10% achieves a balanced performance, extending setting time while improving early strength and microstructural densification. These findings establish TMP as an effective retarder for developing MKPC-based materials with potential for biomedical applications, pending further biological validation. Full article

Increasing global demand for animal-based protein has created a critical environmental management challenge regarding manure accumulation in intensive livestock production. Gasification offers a sustainable solution by converting organic residues into renewable synthetic gas (syngas) and carbon-rich biochar. This study systematically evaluated the performance of three major types of animal waste—dairy manure, poultry litter, and swine manure—against a lignocellulosic control (wood veneer waste) in a top-lit updraft (TLUD) gasifier. Three airflow rates (10, 15, and 20 L min⁻¹) were studied. The results indicated that increasing airflow significantly elevated the gasifier flame front temperatures, with poultry litter achieving the highest peak temperature (825.5 °C), followed by swine manure and dairy manure (753.7 and 727.0 °C, respectively) at 20 L min⁻¹ airflow. While dairy manure exhibited the fastest linear burning rate (25.7 mm/min), poultry litter demonstrated the highest mass consumption rate (32.8 g/min). Feedstock chemistry drove distinct reaction pathways in syngas composition. Poultry litter emerged as the superior feedstock for H₂ production, achieving a peak H₂ concentration of 10.78% at 20 L min⁻¹, which attributed to a synergistic combination of outstanding temperature, moisture content and catalytic alkali metals that promoted steam reforming and water–gas shift reactions. CO production was dominated by wood veneer (17.6%), which was driven by the dominance of elemental carbon and fixed solid (FS) content that favored partial oxidation and a Boudouard reaction. These findings suggest that while airflow regulates thermal kinetics, the specific energy profile of the produced syngas is fundamentally determined by the physiochemical properties of the biomass precursor. Full article

This study investigates how outlet pressure influences the fire suppression performance of a compressed air foam system (CAFS), with the aim of supporting system optimization and engineering applications. An experimental apparatus for foam performance testing is used to measure changes in foam flow rate, expansion, initial velocity, initial momentum, and drainage time at different outlet pressures. On the basis of relevant theoretical models, the factors causing discrepancies between model predictions and experimental results are examined, and the models are then refined. How the outlet pressure of CAFS affects foam performance is thereby clarified. The results show that foam flow rate increases as outlet pressure increases. At higher pressures, shear-thinning and intensified gas–liquid mixing affect the foam. As a result, the growth of flow rate in the range of 0.01–0.03 MPa is significantly higher than that in the range of 0.06–0.10 MPa. Both initial velocity and initial momentum increase significantly with increasing pressure, whereas the expansion decreases. Within the outlet pressure range of 0.01–0.10 MPa, the initial velocity increases from 1.23 m/s to 6.65 m/s, the initial momentum rises from 4.6 kg·m/s to 34.1 kg·m/s, and the expansion decreases from 9.2 to 5.4, indicating reduced foam stability. Drainage time and drained mass vary non-monotonically with outlet pressure. The longest drainage time and the smallest drained mass occur at 0.06 MPa. Fire suppression performance improves as outlet pressure increases. A higher outlet pressure enables the foam solution to penetrate the flame zone more effectively and to cover the surface of the burning material. In addition, changes in foam properties enhance the thermal insulation and smothering effects of the foam layer, as well as its heat absorption and cooling capacity. These effects together improve the efficiency of fire source cooling. Full article

Wildland fires, including surface and crown fires, present significant challenges for ecosystems and forest management. Accurate fire modelling is crucial for risk assessment and mitigation strategies. The Fire Dynamics Simulator (FDS) v6.8.0, developed by the National Institute of Standards and Technology (NIST), is a physics-based model that simulates fire behaviour by incorporating advanced physics and chemistry. However, its reliability requires thorough validation. This study validates FDS 6.8.0’s performance in modelling both surface fires and single tree burning. Two separate simulation sets were conducted. For surface fires, pine needle fuel beds were used at a laboratory scale to examine fire behaviour on slopes of 0°, 10°, and 20°. The results were validated against experimental data. A burning Douglas fir tree was simulated, and the results were compared with experimental measurements. The surface fire simulations at 0° and 10° slopes showed strong agreement with experimental data. In single-tree burning, both experimental and simulated results exhibited similar trends, with a rapid increase to a peak mass-loss rate (MLR) followed by a gradual decline. Validating FDS 6.8.0 forms an essential first step toward supporting the investigation of complex wildland fire behaviour, such as surface-to-crown fire transition, canyon fire, and dynamic escalation, using the same FDS version. Full article

Recent measurements performed by the LUNA(Laboratory for Underground Nuclear Astrophysics) collaboration between 2019 and 2024 have provided the most precise direct determinations to date of several key reaction rates in the NeNa cycle, specifically the ²⁰Ne(p,γ)²¹Na and the ²²Ne(p,γ)²³Na reactions, as well as its bridge to the MgAl cycle, i.e., the ²³Na(p,γ)²⁴Mg reaction. Despite their improved accuracy, these updated rates are not yet consistently incorporated into widely used nuclear reaction network compilations. We explore the astrophysical impact of adopting the new LUNA rates by performing nucleosynthesis calculations, focusing on the case of ²⁶Al nucleosynthesis and considering four different stellar environments: low-mass AGB stars, massive stars, very massive stars and core-collapse supernovae. Our results show substantial sensitivity of ²⁶Al production to the revised rates. In the AGB model, the surface ²⁶Al abundance decreases by up to 30%, while in the massive star model, the ²⁶Al abundance in the C-burning shell increases by 51%. In contrast, the impact on both the ²⁶Al yields ejected by very massive stars and on the explosive nucleosynthesis in the supernova model is negligible. These findings have direct implications for galactic chemical evolution, the global budget of ²⁶Al, and theoretical predictions of the ⁶⁰Fe/²⁶Al ratio, which will be critically tested by forthcoming γ-ray observations from missions such as the Compton Spectrometer and Imager (COSI). Full article

Combustion duration is a fire behaviour feature relevant for both the effects and management of fire. We burned small-scale laboratory fuel beds (n = 135) of eight fuel types and developed empirical models to describe variation in flame residence and burn-out times, and fuel mass fraction loss rates during flaming and non-flaming combustion; each fuel sample was ignited at once and burned as a pile. Surface area-to-mass ratio of the fuel particles, by itself, allowed accurate prediction of all combustion properties with better performance than surface area-to-volume ratio. Fuel bed structure was also shown to have an influence, fuel load being the variable that further improved all predictions. This work provides evidence that surface area-to-mass ratio is an adequate descriptor of the combustion characteristics of forest fuel beds. Our expectation is that this approach will assist future modelling efforts to obtain simple empirical models to predict the combustion features of free-spreading fires in a wide range of vegetation types. Full article

Background: Weight extremes are linked to morbidity, yet their impact on burn outcomes remains underinvestigated. Prior studies suggest an ‘obesity paradox’, showing survival benefits and better functional outcomes in obese patients. Methods: This study used the global real-world database TriNetX to assess the association between body mass index (BMI) and clinical outcomes in adult burn patients, categorized using WHO definitions. After 1:1 propensity score matching for demographics, burn severity, and smoke inhalation injury, clinical outcomes were analyzed over a six-month period following burn injury. Outcomes included mortality, sepsis, pneumonia, acute kidney injury (AKI), cardiovascular events, graft complications, skin infections, and psychological impairment. Results: After matching, 9736 patients were included in the underweight versus normal weight comparison, 72,274 in overweight versus normal weight, 71,195 in obesity versus normal weight, and 9732 in underweight versus obesity. Underweight patients were associated with higher mortality and increased risks of sepsis, pneumonia, cardiovascular events, and psychological impairment. Overweight and obese patients showed higher survival rates and overall better clinical outcome associations. Conclusions: These findings are consistent with the previously described ‘obesity paradox’ in burn care and identify underweight burn patients as a distinct high-risk subgroup. Full article

Colombia generates large volumes of lignocellulosic residues from agriculture, forestry, and agro-industrial activities. Much of this material is landfilled, openly burned, or left to decompose. These practices drive greenhouse-gas emissions (methane and CO₂), particulate air pollution, water contamination, and pest proliferation. Therefore, this study focuses on the design, simulation, exergetic and economic analysis of lignocellulosic biorefinery schemes in Colombia using corn stover (CS) as feedstock. This approach thus turns an environmental liability into valuable resources. Mass and energy balances obtained from Aspen Plus V10^® were used to calculate exergy efficiency. Economic indicators were provided by the Aspen Process Economic Analyzer (APEA) V10^® software. The first scenario (SCE01) included xylitol, lignin, carbon dioxide, biogas, and biofertilizer production along with in situ ethanol co-production; for scenario 2 (SCE02), a cogeneration (CHP) stage using biogas and biofertilizer as fuel was added; in scenario 3 (SCE03), the ethanol production of scenarios 1 and 2 was replaced by glutamic acid production. The exergy efficiency results were as follows: SCE01 (60.1%), SCE02 (36.8%), SCE03 (37.5%). The largest exergy losses were found in the CHP system. In terms of economic viability, all scenarios showed favorable economic parameters. SCE03 showed better results with an Internal Rate of Return (IRR) of 28.01% and a Net Present Value (NPV) of USD 985.1 M compared to SCE01 (27.48%; USD 769.1 M) and SCE02 (27.13%; USD 643.1 M). In light of these results, the SCE03 approach represents the most attractive investment opportunity, with the potential to integrate the social and environmental pillars of sustainability by fostering rural economic development and CO₂ capture. Optimization strategies can be readily adopted to enhance the overall efficiency of the proposed model, enabling it to serve as a benchmark for scaling and comparing alternative lignocellulosic waste valorization pathways at a national level. Full article

The characteristics of litter combustion have a significant impact on the spread of surface fires in the central Yunnan Province, a high-risk forest fire zone. The burning behavior of individual and mixed-species litter samples from five dominant tree species (Pinus yunnanensis Franch., Keteleeria evelyniana Mast., Quercus variabilis Blume., Quercus aliena var. acutiserrata, and Alnus nepalensis D. Don.) was assessed in this study using cone calorimeter tests. Fern fronds and fine branches were included in additional tests to evaluate their effects on specific combustion parameters, such as Fire Performance Index (FPI), Flame Duration (FD), Time to Ignition (TTI), Mass Loss Rate (MLR), Residual Mass Fraction (RMF), Peak Heat Release Rate (PHRR), and Total Heat Release (THR). There were remarkable differences in the burning properties of the three types of litter (broadleaf, pine needles, and short pine needles). The THR and PHRR values of P. yunnanensis were the highest, whereas the PHRR of the other species varied very little. Short pine needle litter showed incomplete combustion and a long flame duration. When measured against pure pine needle litter, mixtures of P. yunnanensis and broadleaf litter showed lower PHRR. When set side by side to pure pine needle litter, P. yunnanensis and broadleaf litter showed lower PHRR. THR rose when fine branches were included, underlining the significance of fine woody fuels in fire behavior. The insertion of ferns increases the percentage of unburned biomass, prolongs TTI, and dramatically reduces PHRR. Full article

In the steel industry, reheating furnaces are a significant source of carbon emissions. Co-firing natural gas and ammonia in reheating furnaces reduces carbon emissions and mitigates ignition difficulties and the limited flammability range of ammonia. This research develops a three-dimensional model for combustion, fluid dynamics, and heat transfer in a reheating furnace to investigate slab heating and emission with a natural gas/ammonia blended fuel. Numerical results demonstrate that, under constant calorific value conditions, the average temperature of the discharged slab decreases following ammonia blending, with the greatest temperature differential of 110 K achieved at a 10% ammonia blending ratio. Moreover, as the ammonia blending ratio increases from 0 to 40%, the mass fraction of CO first rises and subsequently declines, ultimately decreasing by 18%. Meanwhile, the CO₂ emissions at the outlet decrease by 17.6% to 40.7%. The mass fraction of unburned NH₃ rises to 0.0271, whilst NO_x emissions diminish from 49.47 ppm to 14.23 ppm. These changes are attributed to the low combustion efficiency and burning rate of ammonia, coupled with the reduced furnace temperature during ammonia-blended combustion, which weakens radiative heat transfer. Thus, optimizing the equivalence ratio along with applying hydrogen can improve the thermal efficiency of the reheating furnace. This study provides insight into the operational characteristics of a full-scale walking-beam reheating furnace operating under natural gas-ammonia co-firing conditions, providing theoretical guidance for enhancing the thermal efficiency of furnaces. Full article

Yellow eels were sampled by electrofishing in 1979, 1980, and 1981 in Vester Vedsted Stream, Denmark, which has as its outlet to the North Sea. Yellow eels were aged by burning the otoliths. The gender of the eels was not specified, and they varied from 6.5 to 48.5 cm in length. The ages varied from 0+ to 10+ years. The annual growth rate Δ varied from 3.4 cm for the youngest eels to 2.2 cm for eels over 10 years old, with a mean of 3.1 cm. Body mass wet weight was correlated to energy content (kcal), with an annual mean growth rate Δ of 5.33 kcal. In contrast to body length, the annual growth rate Δ of energy content (kcal) increased with age. Von Bertalanffy growth trajectory (cm) of length-at-age was calculated, and L∞ = 118.4 cm. Annual natural mortality M was calculated, and M was significantly dependent on body mass, i.e., high M at low body mass vs. low M at high body mass. The biological production was calculated to be 13.5 g wet weight m⁻² per year. A total of 780 eel stomachs were analyzed, 287 (37%) of which were empty. Mass (wet weight, g) of food content increased more than proportionally with eel body mass. Chironomid larvae, Ephemeroptera nymphs, Simulium larvae, and Gammarus pulex were the dominant food taxa, followed by Trichoptera larvae. The size of Chironomid larvae, Ephemeroptera nymphs, and Simulium larvae prey was independent of the length of the eel, whereas the size of Gammarus pulex increased with increased eel length. 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

In this study, we evaluate a phosphorus-based fire retardant (HR Prof) on Norway spruce using Simultaneous Thermal Analysis (STA: TG/DTG/DSC), Gas Chromatography–Mass Spectrometry (GC–MS), and bench-scale mass-loss measurements. Relative to the untreated reference, HR Prof re-routes decomposition toward earlier dehydration and transient char, simplifies the evolved gas mixture in the 150–250 °C range, and reduces burning intensity during 600 s of radiant exposure. Across 150/200/250 °C, identified components fell from 20/24/51 (reference) to 5/9/9 (HR Prof); no phosphorus-containing volatiles were detected in this window. Mass-loss tests showed a lower average burning rate (0.107 vs. 0.156%·s⁻¹) and a smaller cumulative loss at 600 s (64.2 ± 9.5% vs. 93.7 ± 2.1%; one-way ANOVA, p < 0.05 for percentage loss). STA was conducted in air; the transient char formed at an intermediate temperature is oxidized near ~600 °C, explaining the low final residue despite earlier charring. A count-based Poisson model corroborated the significant reduction in volatile component richness for HR Prof (p < 0.001). The cross-method correspondences—earlier condensed-phase dehydration/char → leaner volatile pool → lower and flatter burning-rate profiles—support a condensed-phase-dominated protection mechanism within the conditions studied. Full article