Search Results (8,141)

This study investigates the influence of isomorphous substitution of Aluminum by V, Zr, La, and Ni in Beta zeolite frameworks used as supports for Ni-based dry reforming of methane catalysts. The research focuses on how the nature of the incorporated metal affects catalytic activity and long-term stability. Catalysts were synthesized using both co-impregnation and sequential impregnation strategies. Physicochemical characterization—including gas adsorption, X-ray diffraction, transmission electron microscopy, and H₂ temperature-programmed reduction—revealed distinct structural roles for each metal. Results indicate that V primarily occupies T-vacancy sites within the dealuminated Beta framework, whereas Ni resides as charge-compensating extra-framework species or highly dispersed NiO clusters. Zr and La tend to form highly dispersed oxide species or occupy enlarged silanol nests. Notably, the addition of La₂O₃ was found to significantly enhance the long-term stability of the catalysts during the dry reforming of methane process. V-modified catalysts exhibited the highest activity but suffered from low stability; conversely, Zr incorporation offered the best overall performance, balancing high activity with enhanced stability, achieving 85% CO₂ and 75% CH₄ conversion, with no detectable carbon deposition after 98 h on stream. Full article

This study provides a rigorous analysis of the phase stability, mechanical behavior, and surface integrity of a non-equiatomic (FeCoNiCr)₈₅Ga₁₅ high-entropy alloy (HEA). By transitioning from the conventional equiatomic design to a gallium-doped 3d-transition metal matrix, we explore the interplay between lattice distortion and phase separation. Synthesized via vacuum arc melting, the as-cast alloy exhibits a non-homogeneous dendritic morphology consisting of a Cr-Fe-Co rich face-centered cubic (FCC) matrix and Ni-Ga rich body-centered cubic (BCC) interdendritic regions. While global thermodynamic criteria (δ = 3.65, ΔH_mix = −9.28 kJ/mol, and Ω = 2.23) favor single-phase solid solution stability, the Valence Electron Concentration (VEC = 7.46) precisely forecasts this dual-phase structure. Following low-temperature annealing at 250 °C for 24 h, high lattice strain energy drives a significant morphological transformation where the continuous interdendritic network resolves into discrete, phase-separated B2/BCC “islands”. Mechanical and tribological characterizations reveal that this low-temperature thermal activation triggers precipitate hardening; the macro-hardness increases from 146 ± 11 HB to 153 ± 7.5 HB and the micro-hardness rises from 186 ± 4 HV_0.5 to 206 ± 17.5 HV_0.5, yielding enhanced resistance to oxidation-delamination wear. However, electrochemical evaluation in a 3.5 wt.% NaCl solution highlights a fundamental trade-off: the formation of localized galvanic micro-cells between the phase-separated islands and the matrix causes the corrosion current density (i_corr) to increase from ≈10⁻⁹ A/cm² in the as-cast state to ≈10⁻⁶ A/cm² post-heat treatment, accompanied by a heightened susceptibility to localized pitting. These findings elucidate the primary role of electronic structure and minor p-block additions in regulating the lifecycle performance of transition metal HEAs under extreme conditions. Full article

Effective thermal management is crucial for the performance, thermal safety, and lifespan of lithium-ion batteries in electric vehicles (EVs). Thermal management strategies are essential for preventing overheating, thermal imbalance, and the associated risk of thermal runaway. Nanofluids are emerging and attracting considerable attention as potential coolants for high-power energy storage and electronics systems. This review updates and summarizes the most recent advances in nanofluid-based cooling strategies for battery thermal management systems (BTMSs) over the past five years, emphasizing their implications for battery thermal safety. Three main nanofluid-based cooling strategies have been evaluated in depth, including nanofluid-based indirect liquid cooling, nanoparticle-enhanced PCM cooling, and nanofluid-based heat pipe cooling. Various nanofluid formulations, including mono, hybrid, and ternary nanofluids, have been considered and evaluated for their heat dissipation under high charge/discharge and abuse-relevant conditions. Thermal and hydraulic performance characteristics, including maximum temperature, maximum temperature difference, and pressure drop, have been comprehensively evaluated for different nanofluid-based cooling strategies. The findings demonstrated that nanofluids significantly improved heat transfer rates and enhanced temperature control efficiency. In particular, hybrid and ternary nanofluids exhibit superior thermal performance and effectively suppress the escalation of safety-critical temperatures. Beyond summarizing cooling performance, this review further discusses the role of nanofluid-based cooling strategies as functional thermal-control layers within intelligent BTMS architectures. Particular attention is given to their compatibility with sensing networks, BMS-/VCU-level supervisory control, predictive thermal models, actuator responsiveness, fault-warning algorithms, and long-term reliability under realistic driving and fast charging conditions. Therefore, this review provides architecture-oriented insights for developing safe, energy-efficient, and control-ready BTMSs for next-generation high-power and connected EVs. Full article

Perovskite-type oxides are among the most promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their mixed ionic–electronic conductivity and compositional flexibility. Many high-performance cathodes rely on Sr substitution at the A-site, often associated with surface segregation and long-term degradation. In this work, we explore an alternative strategy based on defect engineering and phase interactions in Sr-free composites. Perovskite-fluorite composites based on LaFe_0.8Co_0.2O₃ were synthesized through a one-pot route designed to promote the formation of a perovskite phase and a limited amount of fluorite-type ceria. This approach allows the introduction of small fractions of Ce into the perovskite lattice, favoring the cooperative coexistence with La-doped CeO₂. Structural, microstructural and spectroscopic characterization indicates that Ce influences the crystallization pathway and composite defect chemistry. Variations in lattice parameters and Raman features suggest modifications of perovskite structure consistent with defect formation and lattice distortion. Reduction properties and electrical conductivity measurements indicate that Ce incorporation in the perovskite and oxide interaction affect charge transport and oxygen mobility. The electrochemical results demonstrate that the optimal trade-off between activation energy (Ea) and polarization resistance (Rp) is achieved for the sample, with a nominal cerium content, Ce/(La + Ce) of 0.16. Moreover, the electrochemical properties are found to correlate with the nominal cerium content, which regulates defect chemistry and the resulting composite composition. Overall, results suggest that the one-pot synthesis promotes beneficial interactions between the perovskite and ceria phases, allowing the development of Sr-free ferrite-based materials with enhanced functional properties, minimizing the amount of ceria in the composite. Full article

Power electronic DC–DC conversion stages play a pivotal role in photovoltaic (PV) energy conversion. Here, maximum power point tracking (MPPT) is necessary to regulate the operating point of the converter with high bandwidth and robustness in the presence of irradiance and temperature disturbances. This paper proposes an MPPT scheme based on an Intelligent Wave Algorithm (IWA) for a PV source connected to a flyback DC–DC converter. The proposed IWA is formulated as a population-based metaheuristic that updates the converter’s duty cycle to maximize PV power while reducing the oscillations commonly observed in classical methods. A unified MATLAB/Simulink test bench has been developed in which multiple MPPT algorithms—Perturb and Observe (P&O), Incremental Conductance (InC), Particle Swarm Optimization (PSO), Harris Hawks Optimization (HHO) and the proposed IWA—are implemented in parallel flyback subsystems that share the same PV module and converter parameters. The simulation results show that the IWA method achieved consistent convergence to the maximum power point more rapidly than both classical and advanced meta-heuristic methods, obtaining 12.5% better response time and 8.9% better steady-state output power than the method closest to it. Overall, the findings suggest that combining a flyback converter with IWA-based maximum power point tracking (MPPT) improves the efficiency and stability of energy harvesting, making this approach suitable for low- to medium-power photovoltaic (PV) applications within modern power electronics conversion systems. Full article

This study aimed to characterize corn (CS), wolf fruit (WF), and butterfly lily (BL) starches; to develop bioactive coatings from pure starches and their binary and ternary blends; and to evaluate the synergistic effects of these formulations on the physiological quality of common bean seeds. Films were prepared by thermocompression (80 °C, 6 min, 3 t) of film-forming solutions obtained via microwave processing and formulated using a simplex-centroid mixture design. The starches were characterized in terms of amylose content, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Rapid Visco Analyser, while the films were evaluated for thickness, water solubility, and water vapor permeability. The film-forming solutions were applied as coatings, and seed physiological quality was assessed through germination, first count, seedling length, and dry mass. BL exhibited higher gelatinization temperatures and produced films with adequate thickness and moderate permeability, indicating greater structural stability. The CS:BL blend produced films with balanced hydration, promoting rapid and uniform water uptake. Coatings based on BL and CS:BL showed the highest germination percentages, whereas CS:WF resulted in lower physiological performance. These results demonstrate that film properties directly influence seed vigor and germination. BL, alone or blended with CS, represents a promising starch-based material for seed coating, promoting high physiological quality and environmentally friendly characteristics. Full article

Lignin is one of the most abundant biopolymers in nature. The major challenge in lignin depolymerization lies in the formation of complex mixtures that require extensive downstream separation. Selective depolymerization strategies aim to overcome this limitation by promoting controlled bond cleavage while suppressing undesired secondary reactions. In this work, a series of rare-earth-free, perovskite-type mixed metal oxides with general compositions Zn_xNi_1–xTiO₃ and Cu_yNi_1–yTiO₃ were synthesized and evaluated as heterogeneous catalysts for the base-catalyzed depolymerization of lignin. Among the investigated materials, CuTiO₃ exhibited superior catalytic performance, enabling the formation of vanillin as the dominant monomer with high selectivity. The selected catalyst was further characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. The combined effects of key reaction parameters, including temperature, pressure, lignin-to-catalyst ratio, NaOH concentration, and reaction time, were systematically investigated using response surface methodology (RSM). Under the optimized conditions (154 °C, 0.3 MPa, lignin-to-catalyst ratio of 24.5:1, 10 mL of 0.5 M NaOH, and 12 h reaction time), a monomer yield of 11.5 ± 0.46% with ~81% GC-selectivity toward vanillin was achieved. These findings demonstrate that perovskite-type titanates can serve as robust and reusable catalysts. Full article

The transition toward a sustainable hydrogen economy requires the development of advanced materials capable of efficient hydrogen storage and energy conversion. In this work, we present a comprehensive first-principles investigation of the structural, electronic, elastic, and thermoelectric properties of cubic perovskite hydrides XMoH₃ (X = Na, K, and Rb) using the density functional theory within the generalized gradient approximation combined with the Boltzmann transport theory. The calculated gravimetric hydrogen storage capacities are 2.48 wt%, 2.19 wt%, and 1.64 wt% for NaMoH₃, KMoH₃, and RbMoH₃, respectively, indicating moderate storage potential. Elastic analysis confirms mechanical stability and reveals predominantly brittle-to-intermediate behavior with mixed bonding characteristics. Electronic band structures and density of states demonstrate metallic conductivity, driven mainly by Mo-d orbital contributions near the Fermi level, which may facilitate charge transport and hydrogen mobility. Thermoelectric analysis shows temperature-dependent electrical and thermal conductivities, with KMoH₃ and NaMoH₃ exhibiting relatively higher power factors at elevated temperatures, although the overall figure of merit (ZT < 0.3) remains below the threshold for high-performance thermoelectric applications. Despite these limitations, the combined properties of structural stability, metallic conductivity, and moderate hydrogen storage capacity highlight the potential of XMoH₃ compounds as multifunctional materials for integrated hydrogen storage and thermal energy recovery systems. This study provides fundamental insights into the design of perovskite hydrides and underscores their relevance as tunable platforms for future sustainable energy technologies. Full article

The composition of partially ionised plasmas is investigated for densities and temperatures at which the free electrons are degenerate. Based on a quantum statistical approach, the effect of Pauli blocking is addressed. Specifically, one- and two-electron ions are studied. Approximations for deriving an in-medium Schrödinger equation for the ionization potential are indicated. New results regarding the degree of ionisation and the Mott effect are presented. Standard codes for plasma properties do not take Pauli blocking effects into account and are therefore unable to explain the experiments in the high-density regime, where the electrons are degenerate. Full article

A binder-free Co₃O₄ nanoneedle electrode grown directly on nickel foam (Co₃O₄@NF) was fabricated by hydrothermal synthesis followed by calcination and evaluated for electrocatalytic nitrate reduction to ammonium. The integrated three-dimensional architecture combines the catalytic activity of Co₃O₄ with the high conductivity and open porosity of nickel foam, thus exposing abundant active sites, shortening electron-transfer pathways, and facilitating mass transport. Among the electrodes prepared at different calcination temperatures, Co₃O₄@NF calcined at 400 °C delivered the best performance. Under the optimal conditions of −1.4 V vs. Ag/AgCl, pH 7, and an initial NO₃⁻-N concentration of 50 mg L⁻¹, the electrode achieved 83.4% nitrate removal within 480 min together with 98.7% ammonium selectivity. Electrochemical measurements revealed a markedly enlarged electrochemically active surface area and reduced charge-transfer resistance after Co₃O₄ loading. Mechanistic analyses via TBA quenching experiments and DFT calculations revealed that both the direct pathway and the hydrogen-assisted indirect pathway were operative, with the indirect pathway being dominant due to its lower free energy barrier while maintaining negligible nitrite accumulation. The electrode also showed good cycling stability and retained high ammonium selectivity in real water matrices. These results demonstrate that binder-free Co₃O₄ nanoneedles supported on nickel foam constitute a promising cathode architecture for coupling nitrate removal with ammonia recovery. Full article

This study synthesized a novel Fe₃O₄/biochar composite (Fe₃O₄@BC) characterized by a porous structure and a high electron-donating capacity. The effect of Fe₃O₄@BC on ammonia emission and nitrogen loss during electric-field-assisted composting was investigated, and its underlying mechanism in nitrogen transformation was elucidated. Results demonstrated that the addition of an appropriate amount of Fe₃O₄@BC reduced cumulative NH₃ emission and total nitrogen loss by 30.00% and 4.03%, respectively. The favorable changes in gas emissions could be attributed to Fe₃O₄@BC-mediated modulation of key core microbial taxa. Under the electric-field-coupled condition, Fe₃O₄@BC addition significantly promoted the proliferation of Actinobacteria, such as Thermobifida and Corynebacterium, during the high-temperature phase, while concurrently suppressing the activity of Firmicutes. The shift in core microbial communities optimized key nitrogen transformation processes, including ammonification and nitrification, ultimately leading to reduced NH₃ emission. This study highlights the application potential of Fe₃O₄@BC in enhancing nitrogen retention and mitigating emissions during composting. Full article

Proteases, enzymes that catalyze the hydrolysis of peptide bonds in peptides and proteins, have widespread industrial applications, particularly in milk coagulation for cheese production. Microbial enzymes have been employed as alternatives to animal rennet, offering advantages such as cost-effectiveness, availability, and compliance with dietary, cultural, and religious requirements. Solid-state fermentation (SSF) is widely employed for microbial enzyme production because of its low operational costs, reduced water and energy requirements, high product concentrations, and the ability to utilize agro-industrial residues as low-cost substrates, thereby contributing to both process sustainability and waste valorization. We report the production and characterization of a novel milk-clotting protease produced by Trichoderma koningii FFT13. The protease was produced by SSF using wheat bran as the substrate, an agro-industrial residue. It was classified as a chymotrypsin-like serine protease and exhibited a specific caseinolytic activity of 9861 U/mg. The enzyme coagulated both reconstituted skim milk and pasteurized whole milk in the presence or absence of calcium. Coagulation was enhanced by increasing temperature, reaction time, enzyme concentration, and calcium levels. Scanning electron microscopy revealed destabilization of casein micelles, their progressive aggregation, and the formation of a well-defined gel network, confirming the effectiveness of the protease in milk coagulation. Therefore, these results demonstrate that the chymotrypsin-like protease from T. koningii is a promising enzyme for milk coagulation, with potential application in cheese production. The enzyme obtained constitutes an alternative to traditional coagulants, overcoming limitations related to animal rennet while potentially offering additional advantages in terms of process sustainability and industrial scalability. Full article

Hemp seed protein hydrolysate (HSPH), despite its high digestibility and solubility, exhibits severely impaired gelation properties due to extensive hydrolysis, thereby limiting its food applications. This study analyzed the effect of homogeneously incorporating commercial hemp seed protein concentrate (HSPC) into HSPH on physicochemical and structural properties of the resultant composite gels. As the HSPC concentration increased from 100 to 150 mg/mL, the composite gels exhibited a significant enhancement in hardness (p < 0.05), increasing from 1.63 to 5.74 N, along with an improvement in water-holding capacity (WHC) from 45.52 to 55.46 g/g. Concurrently, the storage modulus (G′) and gelation temperature increased, with the latter rising from 65 to 78 °C. SDS-PAGE analysis suggested that the enhanced composite gel properties were attributed to its high-molecular-weight protein fractions (10–15 kDa and 40–50 kDa) of HSPC, which functioned as the primary structural components of the gel network. In addition, the formation of denser yet irregular microstructures was observed by scanning electron microscopy (SEM) analysis when HSPC incorporation increased from 0 to 200 mg/mL. Fourier-transform infrared (FTIR) further suggested that these improvements were due to increases in β-turn and random coil contents by approximately 9.60 and 7.73%, respectively. These findings provided insights into the utilization of HSPH and HSPC in plant-based foods and contributed to food security and sustainable agriculture. Full article

Lithium-ion batteries require cathode materials with high capacity and cycling stability. Li₃V₂(PO₄)₃ (LVP) offers a theoretical capacity of 197 mAh/g but suffers from poor electronic conductivity. In this study, a Li₃V₂(PO₄)₃/carbon (LVP/C) composite was synthesized via a citric acid-assisted sol–gel method. The effects of pyrolysis temperature (700–1000 °C) and citric acid-to-salt ratio (1:1, 0.5:1, 0.25:1) were systematically investigated. The optimal composite was obtained at 900 °C with a 1:1 ratio. This material exhibited a well-crystallized monoclinic structure (space group P2₁/c) with unit cell volume of 890.61 ų. The amorphous carbon coating provided a specific surface area of 33.03 m²/g. Electrochemically, the optimal LVP/C_1:1 composite delivered an initial specific capacity of 114 mAh/g at C/10 rate—twice that of samples with lower carbon content. It also demonstrated 100% capacity retention after 25 cycles with favorable coulombic efficiency (67%) and reduced charge-transfer resistance. These results show that pyrolysis at 900 °C with a 1:1 citric acid-to-salt ratio provides an optimal balance between crystallinity, carbon coating uniformity, and electrochemical performance for high-performance LVP/C composite cathodes. Full article

This study examines technological change in Longquan celadon from the Dayao kiln-site area by asking three related questions: how body and glaze compositions changed from the Southern Song to the Yuan and Ming periods; how these compositional changes relate to glaze color and microstructure; and how firing-temperature data from representative ceramic bodies help to clarify firing practice within the sampled kiln sequence. Twenty celadon sherds from Jincun Dayao Bentou, Dayao Shantoucheng, Dayao Mulianyan, and Zhulongcun Panchuangkou were analyzed by energy-dispersive X-ray fluorescence spectroscopy (EDXRF), CIE $L^{*}{a}^{*}{b}^{*}$ color measurement, scanning electron microscopy (SEM), and high-temperature dilatometry. The results show that the Yuan-associated bodies in this sampled assemblage contain higher ${\mathrm{Al}}_2{\mathrm{O}}_3$ and ${\mathrm{K}}_2\mathrm{O}$ and lower ${\mathrm{SiO}}_2$ than the Southern Song and Ming groups, indicating a strengthened aluminum- and potassium-rich body system. Glaze chemistry records a staged rebalancing of the flux system: from the high-calcium condition represented by Northern Song reference glazes, through a transitional Southern Song state, to a stronger calcium-alkali character in the Yuan period, followed by a partial return toward a more calcium-rich recipe in the Ming period. Color measurement indicates that the Yuan samples generally have lower $b^{*}$ values, reflecting a reduced yellow component and a more bluish-green tendency; their relatively lower $L^{*}$ values also correspond to a darker glaze appearance, although this difference is less pronounced than that observed for $b^{*}$. SEM observations of four representative cross-sections show glass-dominated glazes, anorthite-bearing body–glaze interlayers, and mullite-bearing bodies; the two Yuan representatives have thicker glaze layers and local phase separation, suggesting that their darker and more bluish appearance was produced by the combined effects of glaze chemistry, thickness, and microstructure. Firing-temperature data obtained from high-temperature dilatometry show that the representative samples were fired within a high-temperature range, while the variation between the two Yuan specimens suggests greater flexibility in firing practice during this period. Taken together, the data suggest that Longquan celadon underwent a non-linear technological reorganization, with the Yuan phase forming a key interval of compositional, microstructural, visual, and firing-related reconfiguration. Full article