Search Results (6,632)

Although amorphous calcium phosphate (ACP) has been extensively employed as a biomaterial in dental and orthopedic fields, its exploration for environmental applications—particularly in potentially toxic element remediation—remains notably limited in the scientific literature. This study reports the rational design of a multifunctional adsorbent by integrating sodium citrate-stabilized ACP (Cit-ACP) nanoparticles into calcium-crosslinked sodium alginate (SA) hydrogel beads for selective Cu²⁺ sequestration from aqueous systems. Comprehensive sorption assessments revealed that equilibrium uptake aligned with the Freundlich isotherm (indicating heterogeneous surface interactions), while kinetic profiles adhered to pseudo-second-order behavior, characteristic of chemisorption-driven processes. Under optimized operational parameters (pH 5.0, 45 °C), the Cit-ACP/SA composite attained an exceptional maximum adsorption amount of 307.76 mg/g. Thermodynamic analysis further confirmed the spontaneity (ΔG° < 0) and endothermic nature (ΔH° > 0) of the process. Multi-technique characterization (XPS, FTIR, XRD, pH trajectory) elucidated a dual-mode adsorption mechanism: (i) ion exchange between aqueous Cu²⁺ and structural Ca²⁺ within both the alginate matrix and ACP framework; and (ii) in situ surface precipitation yielding copper-substituted hydroxyapatite. Owing to its facile aqueous-phase synthesis, superior adsorption performance, biodegradability, macroscopic bead morphology enabling rapid separation, and robust selectivity in complex matrices, the Cit-ACP/SA composite presents a sustainable, scalable, and eco-compatible platform for practical remediation of copper-contaminated wastewater. Full article

The dominance of inexpensive ferrites and high-performance rare-earth-based magnets on the global market causes a significant performance gap between these materials. Fe${}_2$P-based materials are promising rare-earth-free candidates to bridge this gap, offering high magnetization and uniaxial anisotropy. In this study, density functional theory was employed to systematically analyze the influence of Si and Co substitution on the phase stabilities of such Fe${}_{2-y}$Co${}_y$P${}_{1-x}$Si${}_x$ compounds. At 0 K, Si substitution destabilizes the compounds; however, this trend is reversed at elevated temperatures, where Si significantly enhances phase stability. In contrast, Co substitution reduces competition energies at 0 K but promotes instability with increasing temperature. For quaternary Fe${}_{2-y}$Co${}_y$P${}_{1-x}$Si${}_x$ compounds, the combined presence of Si and Co leads to a pronounced expansion of the stability range of the hexagonal crystal structure, in reasonable agreement with available experimental observations. Starting from temperatures above 1000 K, several quaternary compounds exhibit negative competition energies, indicating thermodynamic stability. Among all investigated compositions, Fe${}_{1.84}$Co${}_{0.16}$P${}_{0.84}$Si${}_{0.16}$ stands out, combining particularly low competition energies with a previously reported mean-field Curie temperature of 557 K and a high magnetic hardness factor. These results identify Fe${}_{1.84}$Co${}_{0.16}$P${}_{0.84}$Si${}_{0.16}$ as a highly promising rare-earth-lean hard magnetic material for future applications. Full article

Rice protein has limited gelation properties, restricting its food applications. This study added four polyphenols—catechin (C), epicatechin (EC), tannic acid (TA), and proanthocyanidins (PC)—to rice protein to investigate their effects on gel rheology, in vitro digestibility, and microstructure. Multi-spectroscopy and molecular docking were used to explore interaction mechanisms. During the temperature sweep (95 °C), PC- and TA-composite gels (GRP-PC, GRP-TA) showed storage moduli slightly higher than the pure rice protein gel (GRP), while GRP-C and GRP-EC (C- and EC-composite gels) were similar to GRP. In frequency sweep (25 °C), GRP had the highest modulus, followed by GRP-PC > GRP-TA > GRP-EC > GRP-C. Polyphenols reduced total digestibility (from 77.4% to 67.6–75.2%). All polyphenol-complexed gels showed markedly improved ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activities. C and EC induced loosely crosslinked microstructures, whereas TA and PC formed sheet-like aggregates. Fluorescence quenching was predominantly static, with quenching rates TA > PC > EC > C. Binding constants followed the same order. Thermodynamic parameters (ΔH > 0, ΔS > 0, ΔG < 0) indicated hydrophobic interactions as the driving force. Molecular docking revealed that PC formed the most hydrogen bonds (8) with rice glutelin, followed by TA (4), C (5), and EC (3). These findings provide data support for designing rice protein-based functional foods. Full article

This study investigates the elastic anisotropy and thermodynamic properties of the L1₂-type ScAl₃ phase under extreme conditions (0–1500 K and 0–50 GPa) using first-principles calculations. The elastic constants were determined using a precise stress–strain method, with polycrystalline moduli derived via the Voigt–Reuss–Hill (VRH) approximation. A systematic analysis was conducted to characterize the elastic anisotropy of Young’s modulus, shear modulus, and Poisson’s ratio. Results demonstrate that ScAl₃ is mechanically stable and exhibits near-perfect elastic isotropy (A^U = 0.0001). Thermodynamic analysis via the quasi-harmonic Debye–Grüneisen model reveals that the phase maintains its structural integrity and significant heat resistance up to 1500 K, despite thermal softening. These findings provide theoretical insights into the physical nature of ScAl₃ intermetallics and offer quantitative guidance for the design and thermal treatment of Sc-reinforced aluminum alloys in high-temperature aerospace applications due to their superior combination of strength and toughness. Full article

To address the resource waste caused by the ineffective recycling of large quantities of red mud, this study proposes an innovative technical route consisting of red mud sintering followed by smelting in a small blast furnace or solid-waste smelting furnace for pyrometallurgical iron extraction. Under optimized process conditions—binary basicity of 4.97, a raw material composition of 78.27% wet-based red mud, 15.67% quicklime, and 6.05% fuel, with a solid fuel consumption of 121 kg/t—the produced sinter meets the feeding requirements of blast furnace smelting. The results indicate that the liquid phase generated during red mud sintering mainly consists of composite oxides in the CaO–Al₂O₃–SiO₂ system; calcium aluminosilicate (Ca₂Al₂SiO₇) was detected and inferred to be a potential bonding phase in the sinter matrix. Thermodynamic analysis shows that the Gibbs free energy of Ca₂Al₂SiO₇ is lower than that of calcium ferrite, indicating that its formation is thermodynamically more favorable. The formation amount of this phase is closely related to the Ca/Al ratio, while temperature has a limited influence. In addition, Na₂O can react with CaO·2 Al₂O₃ to form a low-melting-point phase, which significantly reduces the sintering temperature and enhances the fluidity of the liquid phase. These findings provide a new theoretical basis for the sintering of high-alumina ores and offer technical support for the efficient utilization of red mud as well as energy conservation and emission reduction. Full article

Glaucoma is a complex condition with an unknown exact cause, but it involves progressive damage to the optic nerve. This damage is primarily driven by high eye pressure, poor blood flow, and oxidative stress, a process linked to cell ageing and inflammation that harms the retina. Recent research highlights that these issues stem from structural changes in the eye’s drainage system and visual pathways, which can be analysed through the lens of engineering thermodynamics. This study proposes a thermal explanation for the physiological processes linking ocular behaviour to inflammatory ion flux alterations. We develop a thermal model demonstrating that temperature increases are tied to the mechanical work necessary for maintaining water flux in the anterior ocular chamber. We show that these changes alter the membrane potential and tissue pH, resulting in elevated intraocular pressure. By clarifying the temperature–pressure effect, this research establishes a theoretical framework to study the developments of future glaucoma therapies. Full article

The lamprophyre dikes and multi-generational pyrite and arsenopyrite developed in the Jinshan gold deposit in the West Qinling metallogenic belt provide critical evidence for understanding the role of mantle-derived magmatism in gold mineralization processes. In this study, we conducted zircon U-Pb dating of lamprophyre to constrain the timing of magmatic activity and the mineralization age, and performed EMPA and LA-ICP-MS analyses on sulfides from the main metallogenic stage (Py II–III, Apy II–III) and lamprophyre-hosted pyrite (Py L) to constrain the formation conditions and metal sources of the Jinshan deposit. The results show that the mantle-derived magmatism represented by lamprophyre yields an age of 206 ± 2 Ma, which provides a lower-limit constraint on the timing of gold mineralization, corresponding to the subduction-to-extension transition period in the region. Stage II mineralization occurred at 270–320 °C with logƒS₂ of −9 to −5, dominantly as Au-HS complexes, indicating medium-temperature hydrothermal conditions with low sulfur fugacity, consistent with microscopic mineral assemblages and thermodynamic simulations. Systematic δ³⁴S variations reveal: stage II values (9.24–5‰) indicate granitic/Devonian sedimentary sources; Py L values (2.19–3.6‰) reflect mantle contributions; stage III signatures (−2.3–1.93‰) record late meteoric water mixing. Complementary δ⁵⁶Fe data show that Py II (0.2–0.3‰) and Py L (0.58–0.68‰) preserve magmatic fingerprints, while negative values of Py III (−2.29 to −0.71‰) document increasing sedimentary Fe incorporation. Combined with geochronology, S-Fe isotopes, and physicochemical constraints, we propose that the Jinshan gold deposit formed in a tectonic setting transitioning from compression to extension during the Late Indosinian (ca. 237–201 Ma). Mineralization was initiated by the partial melting of the metasomatized mantle, where hydrous magmas efficiently extracted Au and volatiles. These components ascended through transcrustal faults, with Au partitioning into exsolved fluids that precipitated gold through immiscibility and boiling in secondary structures. Full article

A systematic first-principles density functional theory (DFT) study was performed using the Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (GGA) functional combined with ultrasoft pseudopotentials (USPPs), as implemented in the CASTEP code. The PBE-GGA functional was chosen because it provides a well-balanced description of both metallic and covalent bonding characteristics at the Fe/Ti₃SiC₂ interface. To elucidate the interfacial bonding mechanisms and heterogeneous nucleation behavior of Ti₃SiC₂ particles in iron-based composites. The structural stability, work of adhesion, interfacial energy, and electronic properties of the Fe(111)/Ti₃SiC₂(0001) interface were comprehensively investigated. A total of eighteen interface models were constructed, encompassing six distinct Ti₃SiC₂(0001) terminations: C(TiC), C(TiSi), TiC(TiC), TiC(TiSi), TiSi, and Si, and three stacking sequences (OT, MT, and HCP). The results demonstrate that the C(TiC)-terminated interface with HCP stacking exhibits the highest work of adhesion (9.25 J·m⁻²) and the lowest interfacial energy, thus representing the most thermodynamically stable configuration. Analysis of the partial density of states (PDOS) and charge density difference reveals that this exceptional stability originates from strong covalent bonding between Fe 3d and C 2p orbitals at the interface, accompanied by pronounced charge accumulation in the interfacial region. Furthermore, the work of adhesion of this interface substantially exceeds that of the fcc-Fe/fcc-Fe melt interface, confirming the high potency of Ti₃SiC₂ particles as heterogeneous nucleation substrates for Fe grains. These findings provide an atomistic framework for understanding the enhanced nucleation and robust interfacial cohesion observed in Fe/Ti₃SiC₂ composite coatings, and offer theoretical guidance for the design of advanced iron-based MAX phase composites. Full article

We used thermodynamic modeling methods to calculate the stability of auroselenide AuSe_(s) in hydrothermal solutions at different temperatures (25–350 °С), pressures (1–165 bar), salinities (0–5 m NaCl), and acidity–alkalinity (0.00001–0.1 m НCl or NaОН). Gold selenide dissolves congruently in near-neutral solutions. In acidic chloride solutions, AuSe_(s) dissolves incongruently to form selenium Se_(s,l), and in alkaline solutions, to form gold Au_(s). Gold selenide has a low solubility at temperatures of 25–200 °С. With increasing temperature, the solubility of AuSe_(s) increases and at 350 °С the concentration of dissolved gold in highly acidic solutions (without NaCl) reaches 10⁻⁶ m, while in near-neutral and alkaline solutions, it varies from 2·10⁻⁷ to 6·10⁻⁷ m. At concentrations of NaCl and HCl higher than 0.01 m, the solubility of AuSe_(s) increases by half an order of magnitude owing to the formation of gold chloride complexes. In low acidic, near-neutral, and alkaline solutions, gold hydroxocomplex is predominant. We constructed diagrams for the Au–Se–Н₂О system at various temperatures (25, 100, 200 and 300 °С), which show the stability fields of AuSe_(s), Au_(s) + AuSe_(s), Se_(s,l) + AuSe_(s) and Au_(s) on lg ƒO₂–pH. Gold chalcogenides are characteristic minerals of epithermal deposits. The relationships of auroselenide with native selenium and native gold and other minerals in the Au-Ag ores of the Gaching ore occurrence (Kamchatka Peninsula, Russia) and the Bleïda Far West Au-Pd deposit (Morocco) were studied. It was revealed that auroselenide occurs in the peripheral parts of native gold grains, and, less often, in the form of inclusions and intergrowths with other gold chalcogenides in the core of native gold grains. The presence of solidified microdroplets of composition ranging from Te_0.97Se_0.03 to Te_0.71Se_0.28S_0.01 and Se_0.58Te_0.41S_0.01 in the ore minerals at these and other golddeposits suggests participation of chalcogens existing at temperatures of 217–449 °C. The formation of auroselenide and other gold chalcogenides is likely with a decrease in temperature and neutralization of highly acidic or highly alkaline solutions, or with the participation of melts or chalcogen gas particles. The results of thermodynamic calculations are confirmed by the data on the composition of mineral associations with auroselenide from gold deposits. The presence of auroselenide in the ores from Au-Ag epithermal and other gold deposits with Au–Se–Te–S mineralization is predicted. Full article

The key to metallic fuel development is the fabrication of uranium metal and alloys into fuel forms. U-Nb alloys are one of the best candidates for a metallic fuel alloy with high-temperature strength sufficient to support the core, acceptable nuclear properties, good fabricability, and compatibility with usable coolant media. Melt processing has been a key component of the metallic fuel cycle, and process models require thermophysical parameters at elevated temperatures, particularly above the melting temperatures, regarding which experimental data are scarce, for accurate simulations and process development. By means of ab initio density-functional theory (DFT) quantum molecular dynamics (QMD), we have calculated the main thermophysical parameters—the density, thermal expansion coefficient, specific heat, thermal conductivity, melting temperature, latent heat of fusion, and viscosity—used in the modeling of the U-6 wt.% Nb alloy casting. The melting temperature of the U-6 wt.% Nb alloy at ambient pressure is obtained by means of QMD simulations using the Z-method. The ambient volume change and latent heat of melting of U-6 wt.% Nb are also derived from QMD simulations in conjunction with analytical fitting for the energy and pressure. The thermal conductivity for the solid U-Nb alloy is calculated from the semi-classical Boltzmann transport equation combined with an estimate of the electron relaxation time obtained from DFT simulations. Full article

Before launch, cryogenic propellant tanks experience a pre-pressurization stage during which their thermodynamic behavior is sensitive to operating conditions and external disturbances. For liquid hydrogen (LH2) storage tanks, small-amplitude oscillations may modify interfacial transport and phase change, thereby influencing pressure evolution and mass distribution. In this study, a computational fluid dynamics (CFD) model that accounts for gas–liquid interfacial phase change and environmental heat leakage is developed to investigate the thermodynamic response of an LH2 tank subjected to slight external oscillation during pre-pressurization. The effects of oscillation amplitude, inlet gas temperature, mass flow rate, and initial ullage gas fraction on temperature distribution, pressure development, and phase mass variation are analyzed. The results indicate that increasing the oscillation amplitude from 0.006 m to 0.014 m delays the pressurization time from 4.72 s to 5.04 s, while higher inlet temperatures (e.g., 330 K vs. 280 K) shorten the time to reach the target pressure but weaken interfacial condensation, resulting in a slower recovery of liquid hydrogen mass. Raising the inlet mass flow rate from 0.20 kg/s to 0.40 kg/s reduces the time to reach the preset pressure by approximately 56%, and larger initial ullage gas fractions (ullage height from 1 m to 6 m) significantly prolong the pressurization time and produce a wider high-temperature region. These quantitative results clarify the coupled oscillation-thermodynamic effects and can support optimization of LH2 tank operation during pre-pressurization. Full article

This study presents an AI-assisted thermodynamic and computational fluid dynamics (CFD) evaluation of a β-type Stirling engine to improve its thermal efficiency and indicated power output. The engine performance was investigated using Restricted Dimensions Thermodynamics (RDT), the Schmidt thermodynamic model, and three-dimensional CFD simulations under various operating and geometric conditions. Key parameters including rotational speed, phase angle, piston diameter, displacer stroke, porosity, and charged pressure were systematically analyzed to determine their influence on engine behavior. A feed-forward artificial neural network (ANN) trained using the Levenberg–Marquardt optimization algorithm was integrated with CFD-generated datasets to predict engine performance and accelerate the optimization process. The AI-assisted optimization was coupled with the Variable Step-size Simplified Conjugate Gradient Method (VSCGM) to identify near-optimal operating conditions while reducing computational cost. Simulation results demonstrated that the optimization process improved the indicated power from 180.33 W to 185.44 W and increased thermal efficiency from 10.32% to 11.54%. The results also showed close agreement between predicted and experimental pressure–temperature profiles, confirming the reliability of the proposed methodology. Furthermore, CFD analyses revealed that increasing piston diameter and optimizing porosity enhanced heat transfer and pressure distribution within the engine chambers, resulting in improved thermodynamic performance. The proposed AI-driven framework provides a reliable and computationally efficient approach for the design and optimization of advanced β-type Stirling engines operating under realistic thermal conditions. Full article

With the development of shipping to harsh marine environment, it is very important to understand the transient behavior of a marine diesel engine in high sea conditions. Wave-induced hull motion will lead to severe load fluctuations and air-fuel ratio imbalance. In this study, an integrated simulation platform coupled with environmental loads, hull dynamics, propeller characteristics and a high-fidelity thermodynamic engine model was constructed to explore the response characteristics of the propulsion system. The model integrates a zero-dimensional multi-zone combustion method, turbocharger dynamic characteristics and an incremental PID governor, and has been verified based on the bench test data of TBD234V12 diesel engine and the 20 m Wigley standard ship. The simulation results under the sea conditions from level 7 to 9 show that the transient load has a nonlinear amplification effect. Specifically, from sea state 7 to sea state 9, the engine load fluctuation range expands by 2.0 times, while the main peak amplitude of speed fluctuation increases by 3.7 times. Furthermore, the peak exhaust pressure rises by 1.8 times, and the exhaust temperature fluctuation amplitude broadens by 35%. Frequency domain analysis further identified the low-frequency energy concentration phenomenon in the exhaust pressure spectrum and the precursor characteristics of compressor surge. The research results quantify the deterioration law of thermodynamic stability and mechanical stress under wave disturbance, and provide an important reference for the formulation of an engine robust control strategy and fatigue life assessment under high sea conditions. Full article

The development of offshore wind energy in tropical cyclone-prone regions requires analytical frameworks that capture non-stationary climate dynamics. This study presents a multi-scale spectral approach to characterize Atlantic tropical cyclone variability and assess implications for offshore wind resilience in the Caribbean Basin. The methodology integrates Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) to resolve temporal variability in sea surface temperature, cyclone frequency, and intensity, complemented by two-dimensional kernel density estimation (KDE) and non-stationarity analysis. Using NOAA and National Hurricane Center datasets, results identify dominant periodicities at annual and ENSO (2–7 year) scales, a post-1995 spectral energy shift associated with the positive AMO phase, and a thermodynamically consistent energy corridor along 12–16° N. A statistically significant change point in 1987 (Pettitt test, p < 0.05) is detected, although spatial displacement is not significant. An integrated Wind Risk Index highlights the central-western Caribbean as a high-exposure zone overlapping offshore wind development areas. Exceedance analysis shows that 39.8% of observations surpass 25 m/s, 6.0% exceed 50 m/s, and 1.3% approach 70 m/s, indicating relevant design considerations. These findings support the need for non-stationary, multi-scale approaches in offshore wind risk assessment under tropical cyclone influence. Full article

The accumulation of ice on power lines severely affects the safety of power systems. Conventional ice melting methods suffer from poor flexibility and adaptability, accompanied by high power consumption. As a novel technical approach, distributed ice melting deploys modular and movable ice melting units at key sections of overhead ground wires, which generate heat on site according to the actual icing conditions of icing segments, and imposes high requirements on the miniaturization of ice melting equipment as well as the regulation strategy of ice melting current. This study proposes a distributed ice melting method for overhead ground wires based on AC power supply, which can adjust the current in accordance with the specific demands of wire protection and ice melting for different line sections. The feasibility and effectiveness of the proposed method are verified through thermodynamic simulations and experimental tests. The de-icing method injects power–frequency AC into the overhead ground wire through a Scott transformer combined with a series capacitor reactive power compensation structure, enabling on-demand regulation by adjusting capacitor switching strategies and transformer operating modes. This approach balances efficiency and flexibility. Based on a reactive power compensation capacity current control strategy and thermodynamic analysis, an electro-thermal-fluid field coupling simulation model for the experimental ground wire was developed. The current regulation strategies for different environmental and operating conditions were calculated and validated. The simulation results show that, under different conditions, the adjustable current effective values of the de-icing system in this model range from 101 to 380 A (line maintenance current), 304 to 622 A (critical de-icing current), and 661 to 1121 A (maximum de-icing current). Field tests demonstrate that this method can stably achieve AC de-icing and current control. For the experimental JLB40-150 model ground wire, adjusting the injected current to 350 A enables safe operation under line maintenance conditions, with a limit not exceeding 400 A. This paper provides a more efficient, flexible, controllable, and widely applicable method for the de-icing of overhead ground wires. Full article