Search Results (639)

The prediction of drying kinetics in hygroscopic biological materials remains challenging due to the strong coupling between internal moisture diffusion, evolving surface wettability, material deformation and thermolabile bioactive compounds degradation. In this context, periodic temperature variations are inherent to many industrial and solar drying systems, yet most experimental and modeling studies evaluate product quality under constant-temperature conditions. This work provides a demonstration that periodic drying can alter quality degradation pathways in ways that may not be captured by constant-temperature experiments. A coupled non-isothermal lattice Boltzmann method (LBM) model for heat and moisture transport was integrated with a Weibull kinetic formulation to describe the degradation of total carotenoids, total polyphenols, and antioxidant activity in carrot slices. Validation against experimental data across 50–70 °C demonstrates excellent agreement (R² > 0.96 for moisture ratio; quality retention within ±2% of the literature values). Seven drying scenarios were systematically evaluated: constant temperature (60 °C), fast and slow periodic oscillations, high-amplitude cycles, a mixed strategy combining constant initial drying with subsequent oscillations, and two intermittent ON/OFF profiles. Results reveal that while total polyphenol degradation within the present model is constrained to ~13.3% retention under the adopted kinetic parameters, carotenoid and antioxidant retention are highly sensitive to temperature history. The mixed strategy (60 °C for 2 h followed by 50–60 °C oscillations) achieves the highest quality retention (TC: 51.6%, AA: 34.4%) while requiring the lowest energy input (0.512 kJ), outperforming constant drying (TC: 48.8%, AA: 32.9%, 0.563 kJ). Conversely, high-amplitude intermittent drying (70/25 °C) accelerates carotenoid degradation (TC: 46.7%) despite shorter drying time (8.81 h), and low-amplitude intermittent cycling (65/55 °C) yields the poorest mean quality (31.4%) with the highest energy consumption (0.583 kJ). The framework reveals that oscillation frequency critically determines quality outcomes: slow cycles (8 h period) marginally improve retention, while fast cycles (2 h) offer no benefit over constant drying. These findings provide quantitative insights toward the design of drying strategies, demonstrating that optimal strategies must account for the coupling between temperature history and moisture-dependent vulnerability, with the mixed strategy emerging as the best-performing strategy among the tested scenarios. Full article

The DIGIT experiment was launched at the Tournemire Underground Research Laboratory (URL) with the aim of determining the effects of temperature on the transfer of tracers mimicking the most mobile radionuclides in the Toarcian clay rock. The properties of this rock are similar to those of the host rocks being considered for a future deep geological repository for high-level radioactive waste (HLW). The experiment involves the monitoring of the interaction between a test water doped with stable halides and deuterium at constant concentration, and the porewater of the Toarcian clay rock under constant ambient conditions, as well as at higher temperature induced by artificial heating. This experiment seeks to partially address questions regarding the potential spread of contaminants during the thermal phase of HL waste packages. Specifically, the in situ experiment aims to evaluate the role of scale effects, thermodiffusion, a process that combines Fick’s law, the Soret effect, and convection in the transfer of radionuclides. This paper is the second part of a companion paper dedicated to predictive calculations and the installation of the experimental device. It presents the main experimental and modeling results obtained since the beginning of the installation and after 20 months of heat at 70 °C. The test was carried out in five phases, finishing with a sampling campaign: a phase 0 called “initial conditions”, followed by a pure diffusion phase (5 months), then three phases in a heated period lasting 1 year and 8 months. In total, 47 rock cores were analyzed, with approximately 170 samples tested by four diffusion methods (radial, outgoing, through and in vapor-phase) to determine the tracer concentrations in the porewater, their water content and their diffusive transport parameters. The results show a decrease in tracer concentrations with distance from the test zone, in the directions parallel and perpendicular to the stratification. The anisotropy of the medium results in greater migration in the direction parallel to the stratification. Thermal properties also confirm anisotropy with a higher thermal conductivity in the direction parallel to the stratification. Finally, an activation energy of 22.9 ± 1.7 kJ·mol⁻¹ could be proposed by NMR for deuterium, indicating diffusion behavior following an Arrhenius law between 30 and 70 °C. The experimental data allowed for the calibration of a 2D axisymmetric numerical model using the commercial finite element software COMSOL Multiphysics^®. The Fick’s law corrected by an Arrhenius law best reproduces the penetration of deuterium and anions. The Soret effect, integrated into certain scenarios, is only significant for anions’ migration, using a fitted Soret coefficient of 0.1 K⁻¹, as proposed in the literature for the Callovo-Oxfordian, the host rock of the Cigéo project in the east of France. The calibration of the simulated data with the experimental data allowed for the characterization of damaged and/or disturbed zones evolving over time. Simulations over 150 years, the duration of the thermal maximum for HLW packages, show that advection—modeled by Darcy’s law—would have a negligible role in this context due to the low permeability of the upper Toarcian. In conclusion, the DIGIT test showed that, for the Upper Toarcian clay rocks at the Tournemire URL in France, diffusion, corrected for the effect of temperature, is the mechanism that characterizes the transport of radionuclide analogues. The study showed that thermodiffusion has a limited influence on deuterium migration but remains significant for anions in the case of a coupling between temperature correction and thermodiffusion. The test also highlighted the impact of temperature on the spatiotemporal development of a damaged and/or disturbed zone. These new and relevant results in the field will need to be confirmed later through additional experiments. Full article

An analytical model of frictional heat transfer during the uniform sliding of two layers is proposed. One layer is composed of a functionally graded material (FGM) with a thermal conductivity coefficient that varies exponentially across its thickness, while the second layer is homogeneous, with constant thermophysical properties. The thermal problem of friction is formulated as an initial boundary value problem of heat conduction, accounting for the thermal contact conductance and convective heat exchange with the environment. An exact solution for constant friction power was obtained using the Laplace integral transform, supplemented by an asymptotic form for the initial stage of heating. Based on these analytical solutions, a comprehensive study was carried out for a frictional system comprising a ceramic–metal FGM composite in contact with a homogeneous friction material. A dimensional analysis allowed for both a qualitative and quantitative investigation into the influence of contact conductance, convective heat exchange, layer thickness and the FGM gradient parameter on the temperature evolution and distribution, as well as the time to reach the steady state. It was demonstrated that the implementation of an appropriately graded material can substantially improve thermal operating conditions by enhancing heat dissipation into the material bulk and intensifying convective cooling. Full article

Methane oxy-combustion is a promising carbon capture pathway due to the high CO₂ concentration in the exhaust; however, combustion in pure oxygen produces excessively high flame temperatures that impair ignition and operational stability. To mitigate these effects, steam dilution is commonly applied, but it significantly prolongs ignition delay time (IDT). To address these limitations, hydrogen enrichment is proposed as a reactivity-enhancement strategy. The objective of this study is to quantify the combined effects of steam dilution and hydrogen enrichment on ignition behaviour, carbon species formation, and flame temperature in methane oxy-combustion, considering both ignition onset and equilibrium combustion states. A detailed numerical investigation is conducted using zero-dimensional constant-pressure simulations with detailed chemical kinetics implemented in Cantera, formulated in mixture-fraction space. IDT, CO/CO₂ formation, and adiabatic flame temperature are analysed over steam dilution levels of 0–40%, hydrogen enrichment up to 5% by mass, and initial temperatures between 1050 and 1200 K. The model is validated against experimental data for adiabatic flame temperature and key radical species. Results demonstrate that steam dilution effectively reduces the peak adiabatic flame temperature (by more than 300 K at 40% steam) and enhances the CO₂ mass fraction in the equilibrium state near the stoichiometric mixture fraction, but increases IDT by approximately 100–200% across the mixture-fraction range. Hydrogen enrichment strongly counteracts this inhibition, reducing IDT by up to one order of magnitude under high steam dilution (30–40%) while simultaneously suppressing CO. At the stoichiometric mixture fraction, H₂ addition decreases equilibrium CO₂ formation, indicating a trade-off between enhanced ignition reactivity and ultimate carbon conversion under equilibrium conditions. The use of steam dilution as a temperature-control strategy and hydrogen enrichment as a reactivity enhancer identifies a favourable mixture-fraction window. Full article

Hydrogen-induced crack growth initiation, in metallic structures, is studied under constant temperature and chemical equilibrium, by employing Chemical Equilibrium Fracture Mechanics (CEFM). The conditions of small-scale, contained and large-scale hydrogen embrittlement are introduced and the areas of material deterioration, together with the distributions of stress and hydrogen concentration, including hydride volume fraction, are derived analytically. It is shown that the shape of the material deterioration zone is identical for embrittlement caused either by hydrogen in solid solution or by hydride precipitation; the size depends on the strength of the asymptotic crack-tip field, which develops by the mechanical loading in the hydrogen-free structure, as well as on the average hydrogen content absorbed by the structure. It is also shown that a linear relation exists between a power of the threshold of crack-growth initiation and the logarithm of hydrogen content, depending on the extent of hydrogen embrittlement and material elastic-plastic deformation. These linearity trends, which are derived by the present analysis, are confirmed by published experimental fracture mechanics measurements on several non-hydride- and hydride-forming alloys, including α/β hydride-forming alloys. The present study promotes structural integrity assessments, without reliance on complicated coupled numerical analysis of material deformation, hydrogen diffusion and hydride precipitation. Full article

In apple (Malus × domestica Borkh), temperature during flowering strongly influences ovule viability and reproductive success, particularly under changing climate conditions. Five apple cultivars—‘Red Aroma’, ‘Discovery’, ‘Elstar’, ‘Rubinstep’, and ‘Summerred’—were exposed to constant temperatures (8 °C, 12 °C, and 16 °C) in the days following anthesis to evaluate ovule degeneration. At six time points after anthesis, fluorescence-stained ovules were visually categorized to assess ovule vitality and degeneration stages. Ovule viability decreased in a highly temperature-dependent manner across all cultivars. High percentages of viable ovules were observed at 8 °C and 12 °C, whereas ovule senescence was significantly accelerated at 16 °C, leading to a rapid loss of viability. Based on fluorescence intensity, ovule degeneration is irreversible once initiated and involves both physiological and morphological changes at higher temperatures. The cultivar ‘Elstar’ exhibited the slowest loss of ovule viability, while the other cultivars showed more rapid degeneration. These findings demonstrate that both temperature and genetic background affect ovule viability, making this stage of the reproductive process crucial in the context of future climate change. Full article

This study presents the first experimental data on the chemical equilibrium and kinetics of two self-catalytic reactions of trifluoroacetic acid (TFA) with 2,2,2-trifluoroethanol (TFE-ol) and TFA with propan-1-ol (P-ol), in which TFA acts simultaneously as a reactant and a catalyst. The results show that at an initial molar ratio of TFA/P-ol = 1/9 in the temperature range from 30 to 80 °C and the reaction rate coefficient k₁ changes over the course of the reaction. Notably, for the TFA/TFE-ol system (at an initial reactant ratio of TFA/TFE-ol = 1/9 and 5/5 and a temperature of 50 °C), the reaction rate coefficient k₁ remains constant. A new model describing the kinetics of the reaction with a variable rate coefficient is proposed, which accurately fits the experimental data for the TFA/P-ol reaction. Full article

This paper reports initial experimental results related to the preparation of colored anodic titania thin layers using various deep eutectic solvent (DES)-based formulations. Electrolytes based on choline dihydrogen citrate–oxalic acid–ethylene glycol (1:1:1 molar ratio), choline chloride–oxalic acid (1:1 molar ratio) and choline chloride–lactic acid (1:2 molar ratio) eutectic mixtures were investigated. The anodization has been performed at constant voltage in a range of 10–100 V for various periods of time between 1 and 5 min at room temperature under mild stirring. A brief description of anodization procedures, as well as of some characteristics, from appearance and morphological viewpoints, is presented. A quantitative analysis of color characteristics in relation to the DES-based electrolyte and applied voltage using the CIELAB system is also discussed. The achieved chromatic scale follows this order of colors: golden—blue—light blue—light blue/green—pink—violet. This depends on the applied potential and the DES-based electrolyte. The films present a relatively high brightness and color saturation. The hue vs. anodization voltage diagrams suggest an almost linear dependence of the oxide growth measured against the applied voltage. The corrosion performance has been assessed through continuous immersion tests in (i) 0.5 M NaCl for 240 h and (ii) Hank’s biological solution for 96 h with intermediate visual examinations and recording corrosion potential, as well as potentiodynamic polarization curves and impedance spectra at open circuit potential. Different corrosion performances are discussed considering the aggressive medium involved and the used DES-based systems. Full article

Fresh market blueberry (Vaccinium spp.) fruits are fragile and experience numerous impacts during harvest, packing, and shipping. Mechanical harvest of southern highbush blueberries (SHB) is being increasingly implemented due to rising costs and limited availability of labor. As new commercial cultivars become available, questions arise among growers as to their suitability for mechanical harvest. Early spring harvests in growing areas in the southeastern U.S. routinely occur when ambient temperatures exceed 30 °C. A series of experiments was conducted over a decade to determine the effects of mechanical impacts on fruit quality. These experiments employed a 60 cm drop height to induce bruising under three scenarios encountered during commercial harvest and handling. (1) Harvest interval: Nonimpacted ‘Star’ and ‘Sweetcrisp’ fruits had higher soluble solids content to titratable acidity ratios (SSC:TA) after a 7-day interval (Harvest 2) as compared with those from the initial Harvest 1. Impacted ‘Star’ blueberries from Harvest 2 were 70–100% softer during 14-d storage at 1 °C/85% relative humidity than those from Harvest 1, whereas ‘Sweetcrisp’ fruits were less affected by the harvest delay (30–40% increase in soft fruit). (2) Pulp temperature at impact: There were no differences in bruise severity for ‘Meadowlark’, ‘Colossus’, or ‘Sentinel’ due to pulp temperature at impact. Overall, impacted fruits consistently exhibited greater weight loss (3% to 9%), were softer, and had more severe bruising compared with nonimpacted controls. (3) Delays between harvest and impact: Delay-to-impact (5 or 24 h) did not affect weight loss for ‘Meadowlark’ (0.57% to 0.62%) during 4 d of storage at 5 °C. ‘Colossus’ and ‘Sentinel’, held overnight at 22 °C, lost approximately 35% to 45% more fresh weight after the 24 h delay to impact compared with those fruits with the 5 h delay to impact. Impacted blueberries exhibited significantly more severe bruising (38.5% to 84.4%) than control fruits (1.0% to 8.3%). ‘Sentinel’ was softer at harvest than the other cultivars and had the highest amount of severe bruising (82.7%), followed by ‘Meadowlark’ (52.67%) and ‘Colossus’ (42.57%). Flavor profiles varied by cultivar, with SSC:TA ratios ranging from 18 (‘Colossus’) to 21 (‘Meadowlark’) to 44 (‘Sentinel’). Immediately after impact at 15 °C, 20 °C, or 30 °C, the respiration rate (RR) for ‘Meadowlark’ increased as compared with the control fruit. RR for fruits at 5 °C or 10 °C remained fairly constant during the 8 h measurement period. These findings highlight the interactions of harvest interval, pulp temperature, and delay to impact on the postharvest quality of several commercially grown, SHB cultivars over this extended period of time. These three factors must be considered in order to develop effective strategies for mechanical harvest under the warm spring conditions encountered in the subtropical growing conditions in the southeastern U.S.A. Full article

Bisphenol-A (BPA) and butylparaben (BP) are recognized as emerging contaminants due to their extensive use in plastics and personal care products, posing significant risks to ecosystems and human health. Understanding their transport behavior is vital for predicting environmental fate and designing mitigation measures. This study quantifies the diffusion coefficients of BPA and BP under infinite dilution conditions to simulate realistic environmental scenarios. Laboratory experiments employed a UV-Visible spectrophotometer to monitor concentration changes over time at four initial BP concentrations (0.0005–0.0025 M) and at temperatures between 294.85 K and 304.15 K. Experimental data show that BP concentrations at lower initial values (0.0005 M and 0.00075 M) remained constant, indicating minimal diffusion. Theoretical estimations using the Stokes–Einstein equation yielded diffusion coefficients at 299.38 K of 1.51 × 10⁻¹³ m²/s for BP and 8.47 × 10⁻¹⁴ m²/s for BPA. The Wilke–Chang equation estimated higher values: 1.21 × 10⁻¹⁰ m²/s for BP and 1.18 × 10⁻¹⁰ m²/s for BPA at the same temperature. Results confirm that temperature increases enhance diffusion, while molecular size differences cause BP to diffuse faster than BPA. The robust experimental dataset produced here supports the refinement of predictive models for contaminant mobility. These insights are critical for risk assessment and for developing targeted strategies to minimize the persistence and spread of endocrine-disrupting chemicals in aquatic and terrestrial systems. Full article

The impact modification of polyamide 6 (PA6) using maleic anhydride grafted ethylene/1-octene copolymers (EOR-g-MAH) is well-established, yet the isolated influence of intrinsic modifier parameters—specifically octene content $c_{\mathrm{o}\mathrm{c}\mathrm{t}}$ and molecular weight $MW$—remains insufficiently understood due to confounding microstructural effects. This study presents a systematic approach to decouple these variables by maintaining constant grafting degree, modifier content, and compound morphology. A series of PA6/EOR-g-MAH compounds was prepared with controlled variations in $c_{\mathrm{o}\mathrm{c}\mathrm{t}}$ (8–15 mol%) and $MW$ (34–42 kg/mol). Instrumented Charpy impact testing across a temperature range from −40 °C to +23 °C enabled quantification of crack initiation and propagation energies ($E_{\mathrm{i}\mathrm{n}\mathrm{i}\mathrm{t}}$ and $E_{\mathrm{p}\mathrm{r}\mathrm{o}\mathrm{p}}$), providing mechanistic insight into the brittle–ductile transition. Complementary thermal, rheological, and tensile analyses of the modifiers revealed how $c_{\mathrm{o}\mathrm{c}\mathrm{t}}$ governs cavitation behavior and low-temperature toughness, while $MW$ in particular influences particle integrity and energy dissipation at elevated temperatures. The results demonstrate that targeted adjustment of $c_{\mathrm{o}\mathrm{c}\mathrm{t}}$ and $MW$ allows for the precise tuning of brittle–ductile transition temperature (BDTT) and impact resistance. The compound containing a high-$MW$ modifier with intermediate $c_{\mathrm{o}\mathrm{c}\mathrm{t}}$ (13 mol%) exhibited the most favorable balance of toughness and strength retention at elevated temperatures. These findings offer design principles for engineering thermoplastics with enhanced performance across broad service conditions. Full article

Module- and pack-level mechanical design of lithium-ion batteries in electric vehicles is a primary driver of swelling-induced stack pressure and spatially varying ageing. Current practice remains largely empirical or data-driven and configuration-specific, limiting the ability to predict how design changes translate into local pressure heterogeneity and state-of-health (SOH) loss. This motivates a compact chemo-mechanical model that maps packaging boundary conditions to pressure, swelling, and SOH evolution with few interpretable parameters. This study introduces finite-element-ready constitutive laws that couple reversible and irreversible swelling to SOH and through-thickness pressure, covering three boundary cases reported in literature: constant pressure, thickness clamp after an initial preload, and flexible support. Parameters are identified from different published datasets, and the model is validated against independent constraint scenarios. Good quantitative agreement is shown with averaged RMSE of 1.16% for SOH and 0.16 [MPa] for pressure evolution. Variance-based sensitivity analysis shows SOH uncertainty dominated by the damage-law parameters of the proposed constitutive relationship, whereas pressure evolution is primarily controlled by irreversible swelling and the non-linear through-thickness stiffness, indicating calibration priorities for engineering design studies. The framework is intended for fast comparative analyses of individual cells under a controlled environment. Further extensions, including SOC-dependent mechanics, refined hysteresis, temperature, and C-rate variations require dedicated datasets and are left for future work. Full article

Ammonia has great potential as a clean energy alternative and can contribute to reducing carbon emissions from conventional fossil fuels. To investigate the combustion characteristics of ammonia-doped natural gas and to evaluate its feasibility for practical applications, this study experimentally and numerically examined the temperature and pressure variations of ammonia-doped natural gas mixtures under different initial pressures. In addition, the combustion products corresponding to different ammonia doping ratios were simulated and analyzed. The results indicate that, with increasing ammonia doping ratio, both combustion temperature and pressure decrease to varying degrees. Under atmospheric pressure, the combustion temperature generally decreases by approximately 25%, while the peak pressure reduction reaches up to 87.85% in certain cases. Furthermore, under negative pressure conditions, a relatively low ammonia doping ratio enhances the combustion intensity of the mixture, and the peak combustion temperature occurs at lower ammonia concentrations. From an environmental perspective, the variation in combustion products with ammonia doping ratio was further analyzed. The results show that the CO concentration in the combustion products decreases progressively by approximately 71.11% as the ammonia doping ratio increases. In contrast, the NO concentration increases to a maximum value and then remains nearly constant, whereas the NO₂ concentration initially increases and subsequently decreases after reaching a peak value of 0.813 ppm. Overall, these findings provide experimental and theoretical support for understanding the combustion characteristics of mixed gaseous fuels and offer a scientific basis for the application and safety assessment of ammonia-doped natural gas. Full article

This study investigates the application of soybean peroxidase (SBP), an enzyme extracted from a soybean processing byproduct, for the decolourization and oxidative treatment of three industrial azo dyes: Acid Orange 7 (AO7), Acid Orange 20 (AO20), and Reactive Black 5 (RB5), each at a concentration of 50 µM. These dyes are widely used in textile, paper, and leather industries and persist in wastewater. Optimization experiments were conducted at room temperature (approximately 22 °C) to examine the effects of pH, SBP activity, and hydrogen peroxide (H₂O₂) concentration. Optimal degradation conditions were identified as: pH 3.5, 0.075 U/mL SBP, and 0.0375 mM H₂O₂ for RB5; pH 3.0, 0.5 U/mL SBP, and 0.0375 mM H₂O for AO7; and pH 3.0, 0.0025 U/mL SBP (200-fold less than for the isomeric AO7) and 0.0625 mM H₂O₂ for AO20. Under these conditions, dye conversion was very rapid, reaching >97% decolouration in 30 s. The initial first-order rate constants and half-lives were ≥10.7 min⁻¹ and ≤0.065 min (AO7), ≥7.3 min⁻¹ and ≤0.095 min (AO20), and ≥8.5 min⁻¹ and ≤0.081 min (RB5). When normalized to enzyme activity, AO7 showed the highest catalytic efficiency. These findings support the use of SBP as a low-cost, eco-friendly, and effective biocatalyst for the rapid treatment of dye-containing industrial wastewater. Full article

This study experimentally investigates the residual axial compression behavior of circular glass fiber-reinforced polymer (GFRP) tube-confined concrete short columns (CFGFT) after exposure to elevated temperatures. A total of 27 specimens were fabricated and tested under axial compression, with key parameters including GFRP tube wall thickness (5, 8, and 10 mm), exposure temperature (100, 150, 200, and 300 °C), and constant temperature duration (60 and 120 min). The results show that the load–displacement responses of CFGFT short columns after elevated temperature exposure exhibit distinct two-stage characteristics, culminating in brittle failure at the ultimate axial capacity. Wall thickness significantly influences the failure modes of the specimens, while elevated temperatures increase the occurrence of unfavorable failure modes. Temperature is identified as the primary factor governing the degradation of residual axial capacity and initial stiffness, with performance deterioration becoming more pronounced at temperatures exceeding 200 °C. In contrast, the effect of constant temperature duration within the range of 60–120 min is relatively limited. Based on the experimental results, a simplified binary quadratic regression model incorporating the coupled effects of temperature and wall thickness is proposed to predict the post-fire axial capacity reduction factor (Kr), with a coefficient of determination (R²) of 0.901. These findings provide experimental evidence and a practical predictive approach for the fire-resistant design and post-fire safety assessment of CFGFT members. Full article