The effects of reaction temperature and calcium oxide addition on the content and forms of nitrogen and phosphorus in the thermal solvent extraction products of municipal sludge were systematically investigated. In addition, the LCA method was introduced for the first time into this process. Three quantitative indicators including nitrogen extraction efficiency (NEE), phosphorus enrichment factor (PEF), and phosphorus bioavailability conversion ratio (AP/TP) were constructed. By combining experimental data with the Ecoinvent database, the carbon emissions, net energy consumption, and substitution emission reduction benefits of nitrogen and phosphorus recovery under different operating conditions were quantified. The optimal conditions were identified as 300 °C with a CaO dosage of 4 g/100 g sludge, under which both NEE and PEF reached their maximum values. Below this temperature, the thermal solvent extraction reaction was dominated by pyrolysis, whereas at higher temperatures, decomposition and condensation were prone to occur, leading to the formation of polycyclic aromatic hydrocarbons or graphitized structures. With increasing temperature and CaO dosage, the conversion of protein nitrogen to pyridinic nitrogen, pyrrolic nitrogen, and quaternary ammonium compounds was promoted, and these nitrogen species possess enhanced thermal stability. The proportion of apatite phosphorus in the residue increased from 44.6% to 72.6%. A net carbon emission of 389.5 kg CO2-eq/t dry sludge was obtained, which is considerably lower than that of direct sludge incineration.
Phase-change thermal management at nanoscale interfaces is strongly influenced by interfacial energy transport, bubble nucleation, and fluid–surface interactions. The combined use of nanofluids, nanostructured surfaces, and external electric fields provides a promising strategy for boiling heat transfer enhancement, but the underlying atomic-scale coupling mechanism remains insufficiently understood. In this study, molecular dynamics simulations were performed to investigate electric-field-regulated boiling of copper nanofluids on a nanostructured Cu–graphene hybrid surface. Two nanoparticle radii, 1.985 and 2.708 nm, were considered under a fixed particle-number configuration, corresponding to different nanoparticle volume fractions. The results show that the smaller-particle system exhibits earlier nucleation and a stronger later-stage thermal response than the larger-particle system, which may be associated with enhanced particle mobility, more uniform energy redistribution, and easier activation of preferential nucleation regions at the heterogeneous interface. The electric-field effect is strongly dependent on the nanoparticle configuration. For the larger-particle system, the sinusoidal field provides the most evident enhancement, whereas the DC fields show limited or slightly adverse effects. For the smaller-particle system, electric fields do not necessarily advance nucleation onset, but they improve later-stage energy uptake, fluid temperature, and evaporation intensity. Increasing the frequency of the sinusoidal field from 0.05 to 0.3 THz progressively advances nucleation and promotes bubble growth within the investigated range. Local energy mapping and nanoparticle trajectory analysis suggest that the observed enhancement arises from electric-field-induced modulation of interfacial water structure, energy redistribution, and particle–fluid interactions near the heterogeneous Cu–graphene interface. These findings provide atomistic insights into the coupled regulation of nanofluid boiling heat transfer by surface nanostructures and external electric fields.
Refractory high-entropy alloys (RHEAs) have excellent mechanical properties at high temperatures and show significant application potential in extreme environments such as aerospace and nuclear reactors. The inherent high-entropy effect, sluggish diffusion effect, lattice distortion effect, and “cocktail” effect of RHEAs endow them with high strength, excellent oxidation resistance, corrosion resistance, and wear resistance, demonstrating stronger competitive advantages compared to traditional alloys. However, the alloy composition and preparation methods significantly affect the high-temperature mechanical properties and oxidation resistance of refractory high-entropy alloys. This work systematically reviews the effects of different elements and preparation processes on the mechanical properties and oxidation resistance, investigating the mechanisms of mechanical property enhancement, oxidation behavior, and failure mechanisms of RHEAs. Furthermore, this study compares the microstructure and mechanical properties of the same RHEAs prepared using different techniques, analyzing the influence of the processing method on their structure and performance.
With the increasing demand for high-frequency motor drives, FeSiAl soft magnetic composites (SMCs) have attracted attention because of their low core loss and isotropic magnetic behavior. However, their practical application is still limited by the trade-off between permeability and energy dissipation. In this work, an acetic acid passivation strategy was used to form an aluminium acetate precursor on FeSiAl particle surfaces, followed by hot-press sintering at 750–1050 °C to investigate the effect of sintering temperature on the insulating layer, microstructure, and electromagnetic properties of FeSiAl/Al2O3 powder cores. The results show that the precursor-derived oxide layer evolves from loose γ-Al2O3 to denser α-Al2O3 with increasing temperature, while excessive sintering at 1050 °C causes deterioration and local disruption of the insulating layer, accompanied by degradation of the core–shell structure. The sample sintered at 950 °C exhibits the best overall performance, with a permeability of 30.5, a saturation magnetisation of 177.9 emu/g, a total core loss of 547.3 kW/m3 at 30 mT and 200 kHz, and a DC-bias retention above 70
This research investigates the effects of Eu3+ doping on the structural, magnetic, and magnetocaloric properties of La0.67−xEuxBa0.33MnO3 (x = 0, 0.05, 0.10) prepared by the sol–gel method. All samples crystallized in the single phase of rhombohedral R−3c structure. Increased doping induces lattice distortion, lengthening the Mn–O bond and reducing the Mn–O–Mn bond angle, which weakens the double-exchange interaction and thereby reduces the Curie temperature TC and the magnetic entropy change. The composition with x = 0.05 (TC = 312 K) exhibits a maximum magnetic entropy change of 2.18 J kg−1 K−1 under the magnetic field of 2 T, showing superior near room temperature magnetocaloric performance to many other reported manganites. Furthermore, the doping introduces quenched disorder, leading to the formation of Griffiths-like phases. Critical behavior analysis reveals a crossover from mean-field model to non-universal behavior for x = 0.10, which is attributed to local magnetic inhomogeneities and Griffiths-like phases that broaden the magnetic transition and consequently flatten the magnetic entropy change curve.
