Search Results (747)

Direct urea–hydrogen peroxide fuel cells (DUHPFCs) are promising for sustainable power generation, but their performance is governed by highly nonlinear material and operating interactions. This study develops a machine-learning framework employing a multi-output artificial neural network (ANN) to predict cell voltage, power density (PD), and substrate-based energy efficiency (SEE) of DUHPFCs. The ANN exhibits excellent predictive accuracy, achieving coefficients of determination (R²) above 0.995 and normalized root mean square errors (NRMSE) below 1.75 × 10⁻² for all outputs. Model interpretability is enhanced by using Shapley additive explanations and partial dependence plots, which identify current density as the dominant factor affecting DUHPFC performance, followed by temperature and anolyte composition. The ANN is coupled with a multi-objective Pareto-search algorithm optimization (PAO) to resolve the trade-offs among competing performance metrics. Under different optimization objectives, a DUHPFC with an Ni_0.2Co_0.8/Ni-foam anode is predicted to achieve a maximum PD of 45.6 mW/cm² with a low SEE of 2.6% or a maximum SEE of 15.2% with a moderate PD of 40.9 mW/cm². Additionally, a balanced operating regime is identified, achieving a PD of 43.1 mW/cm² and an SEE of 13.9%. Overall, the proposed framework provides an effective decision-support tool for optimizing DUHPFC performance under competing objectives. Full article

Hydrogen is a carbon-free energy carrier that can support decarbonization of the energy and transport systems. Its usage as a fuel in internal combustion engines can abate the pollutants and CO₂ emissions but also presents various challenges. Among these, the formation of under-expanded jets requires proper injector design and accurate control of the injection process. CFD can accelerate the development of hydrogen engine technologies towards market readiness. Low-dissipative density-based schemes are essential to accurately describe the complex flow structures, that affect mixture formation in under-expanded injections. In the present work, the AUSM scheme was implemented in the OpenFOAM library, and successfully used to simulate an experimental hydrogen-into-nitrogen injection. The numerical method, validated against experimental Schlieren images, was compared with the Kurganov–Noelle–Petrova scheme implemented in the current density-based OpenFOAM solver. The numerical results highlighted the reduced dissipation of the AUSM scheme, leading to improved jet penetration and gas mixing. The investigation demonstrated the superior performance of the AUSM scheme, suggesting it as an alternative OpenFOAM solver. Nevertheless, the study identified areas for improvement and critical issues associated with this type of simulations. Full article

The NiCo₂O₄/nickel cobalt sulfide (NiCoS) electrode was constructed on a nickel foam (NF) substrate using a combination of hydrothermal synthesis and constant potential electrodeposition. The NiCo₂O₄ prepared via an in situ hydrothermal method followed by calcination served as an intermediate layer, providing structural support and abundant active sites for the subsequent electrodeposition of the NiCoS top layer. The NiCoS loading amount was optimized by adjusting the deposition time. The optimized NiCo₂O₄/NiCoS electrode delivered an areal specific capacitance (Cs) of 6.94 F cm⁻² at a discharge current density of 2 mA cm⁻² with a coulombic efficiency of 98.85%. It retained 64.52% of its initial capacitance as the current density increased from 2 to 80 mA cm⁻² and exhibited an equivalent series resistance (R_ESR) of 1.06 Ω cm⁻². Furthermore, the NiCo₂O₄/NiCoS electrode retained 88.24% of its initial capacitance after 700 charge/discharge cycles, eventually stabilizing at 81.25% within 4000 cycles. Full article

Urban underground construction in water-rich sandy strata produces large quantities of high-fluidity pipe-jacking spoil whose high water content, residual conditioning agents and heavy metal contaminants make conventional dewatering and landfilling increasingly unsustainable under carbon peaking and neutrality targets. This study explores a low-carbon route that converts such spoil into CO₂ foamed concrete through a coupled alkali activation–CO₂ foaming process. Ground granulated blast furnace slag and fly ash are used as geopolymer precursors, while a CO₂-based aqueous foam is introduced as both a pore-forming phase and carbon source. Single-factor tests and an L16(4⁴) orthogonal design are conducted to quantify the effects of CO₂ concentration, foam volume fraction, geopolymer dosage and alkali activator content on fluidity, setting time and compressive strength. Scanning electron microscopy (SEM) is employed to examine pore structure, gel morphology, carbonate precipitation and the interfacial transition zone around spoil particles. The results identify an optimum mix window (CO₂ 60–80%, foam 70–80%, geopolymer ≈ 20% and alkali activator ≈ 10% of solids) that delivers a fluidity above 210 mm, 28-day strength exceeding 3.0 MPa and a uniform closed-pore network. A multi-scale mechanism is proposed in which physical foaming, chemical carbonation and spoil particle immobilization act synergistically to form a dense gas–solid–soil composite suitable for in situ backfilling. Full article

Tight oil reservoirs developed by volume fracturing commonly suffer from insufficient energy replenishment and rapid production decline. Although CO₂ huff-n-puff can enhance oil recovery, it is prone to early gas channeling through fracture-dominated high-permeability channels, and its effectiveness decreases with successive cycles. To clarify the coupled effects of fracture morphology and foam on CO₂ huff-n-puff performance, comparative experiments of multi-cycle CO₂ huff-n-puff and foam-assisted CO₂ huff-n-puff were conducted on fractured tight cores from the Xinjiang Mahu reservoir, combined with offline low-field NMR T₂ analysis. The results show a clear first-cycle dominant effect, and better reservoir properties lead to higher initial recovery and slower decline in subsequent cycles. Cross fractures increase the final oil recovery by 81.1%, 83.4%, and 73.2% for the three reservoir types, respectively, whereas excessively large fracture apertures reduce recovery because of intensified gas channeling. Foam further improves oil recovery, with 0.6% giving the optimum performance and increasing final recovery by 20.11%, 14.79%, and 8.36% in Type-I, Type-II, and Type-III reservoirs, respectively. NMR results indicate that foam mainly enhances the mobilization of remaining oil in medium and large pore–throat systems by blocking preferential flow channels and enlarging the effective swept volume. This study provides an experimental basis for parameter optimization and mechanistic understanding of foam-assisted CO2 huff-n-puff in fractured tight reservoirs. Full article

To mitigate the interlayer defects and weak interfacial adhesion inherent in FFF-printed parts, thereby facilitating subsequent supercritical foaming applications, a microwave-assisted interlayer healing strategy is developed for FFF-printed, supercritical CO₂-foamed thermoplastic polyurethane (TPU) by incorporating aminated helical multi-walled carbon nanotubes (AS-MWCNTs). Owing to their unique helical morphology, AS-MWCNTs exhibit enhanced microwave absorption and localized heating capability, enabling selective thermal activation at interlayer regions within the foamed architecture. Microwave irradiation induces localized softening of the TPU matrix and promotes polymer chain mobility and interdiffusion across layer interfaces, while preserving the cellular morphology and bulk foamed structure. By optimizing AS-MWCNT loading, substantial improvements in interlayer bonding strength, energy absorption, and overall mechanical performance are achieved. This work provides an effective strategy to restore interlayer integrity in supercritical CO₂-foamed, additive manufactured elastomers and offers insights into the design of microwave-responsive, self-healing cellular materials. Full article

Foaming technology can effectively reduce the viscosity of polymer-modified asphalt and significantly decrease energy consumption during pavement construction, making it an effective approach for achieving low-carbon pavement construction and maintenance. However, mechanically foamed asphalt relies on specialized equipment and requires strict parameter control. Although water-based foaming methods using zeolites or ethanol can alleviate these issues to some extent, they still present disadvantages such as significant variability in foaming performance and potential risks during transportation and construction. Therefore, this study investigates the feasibility of using crystalline hydrates with high water of crystallization for micro-foamed asphalt. Three types of micro-foamed SBS-modified asphalt (MFPA) were prepared using hydrates with different contents of water of crystallization. Physical property tests, foaming characteristic parameters, viscosity–temperature analysis, Fourier transform infrared spectroscopy (FTIR), adhesion tensile tests, scanning electron microscopy (SEM), and fluorescence microscopy were conducted to evaluate their effects on the physical and chemical properties, viscosity reduction performance, adhesion, and compatibility of SBS-modified asphalt. Furthermore, dynamic shear rheometer (DSR) tests, bending beam rheometer (BBR) tests, fatigue life modeling, and morphological analysis were employed to investigate the rheological properties, fatigue life, and bubble evolution behavior of the MFPA system. The results indicate that utilizing the thermal decomposition characteristics of crystalline hydrates with high water of crystallization (Na₂SO₄·10H₂O, Na₂HPO₄·12H₂O, and Na₂CO₃·10H₂O) to release H₂O and CO₂ in SBS-modified asphalt for micro-foaming is a short-term reversible physical viscosity reduction process. The maximum expansion ratio (ERmax) of MFPA reaches 8–10, the half-life (HL) remains stable at approximately 180 s, and the foaming index (FI) peak is about 1160. The construction temperature can be reduced by 10–15%, and the viscosity reduction effect remains stable within 60 min. Compared with unfoamed SBS-modified asphalt, the compatibility, rutting resistance, and fatigue life of MFPA increase by approximately 65%, 32%, and 30%, respectively, while the low-temperature performance decreases by 18%. Under the same short-term and long-term aging conditions, MFPA exhibits better aging resistance. Specifically, its rutting resistance increases by 37%, and fatigue resistance improves by 30% compared with aged SBS-modified asphalt, while the low-temperature performance remains essentially unchanged. Full article

Geothermal energy is a clean, renewable, and baseload-stable resource of strategic importance for carbon neutrality. Hot dry rock (HDR) reservoirs are characterized by high temperatures, great depths, and abundant reserves. However, their extremely low natural permeability requires artificial fracturing to establish effective heat exchange networks. Conventional hydraulic fracturing in enhanced geothermal systems (EGS) faces major challenges under HDR conditions, including excessive water consumption, strong water–rock interactions, and elevated induced seismicity risks, limiting its engineering applicability. Waterless or low-water fracturing technologies offer alternative stimulation pathways due to their distinctive physicochemical properties. Existing reviews have mainly addressed individual aspects, such as specific fracturing media or proppant transport, without systematically integrating recent advances in supercritical CO₂ fracturing, foam fracturing, liquid nitrogen fracturing, and hybrid-fluid fracturing technologies, or comprehensively evaluating their engineering implications. This review systematically analyzed the fracturing mechanisms, heat exchange performance, environmental risks, and HDR-specific engineering challenges of these technologies. Results indicate that waterless/low-water fracturing technologies enhance heat extraction efficiency by generating complex fracture networks while mitigating seismic and reservoir damage risks. However, large-scale application requires further advances in the high-temperature stability of fracturing media, material durability, multiphase flow control, and field validation. Full article

Urea electrolysis has emerged as a promising alternative to conventional water electrolysis for hydrogen production, owing to low electrical energy consumption as well as organic wastewater. However, the practical implementation of this approach is primarily constrained by the lack of cost-effective and efficient electrocatalysts. Thus, the development of earth-abundant, non-precious metal-based bifunctional electrocatalysts toward both the hydrogen evolution reaction (HER) and the urea oxidation reaction (UOR) is of critical importance. In this context, nanostructured, reduced nickel-cobalt tungstate supported on Ni foam is fabricated as a binder-free, freestanding electrode via a two-step hydrothermal process followed by partial thermal reduction. By systematically tuning the precursor concentrations of Ni, Co, and W, the morphology and electronic structure of the material are effectively modulated. The introduction of oxygen vacancies through partial thermal reduction plays a key role in enhancing charge transport properties. The optimized NiCo@W_0.5/NF electrode exhibits a porous, flower-like architecture and demonstrates excellent bifunctional electrocatalytic activity toward both UOR and HER, accompanied by improved mass transport behavior. When employed as both the anode and cathode for overall urea electrolysis, NiCo@W_0.5/NF requires a low cell voltage of only 1.68 V to achieve a current density of 100 mA cm⁻² and delivers impressive operational stability in an optimized electrolyte composed of 3 M KOH and 0.33 M urea. These results indicate that NiCo@W_0.5/NF is a highly promising and efficient bifunctional electrode material for urea assisted hydrogen production. Full article

CoNi layered double hydroxides (CoNiLDHs) were successfully synthesized on nickel foam (NF) using a hydrothermal method. X-ray diffraction (XRD) analysis confirmed the formation of a well-defined hydrotalcite-like phase, including a strong (003) peak, indicating layered stacking. Scanning electron microscopy (SEM) revealed a 3D hierarchical nanosheet structure resembling flower-like arrays, which was further supported by EDS mapping showing a uniform distribution of Co, Ni, and O. Electrochemical studies demonstrated excellent OER activity, with a low overpotential of 188 mV at 10 mA/cm² and a Tafel slope of 97.48 mV/dec, inferring rapid reaction kinetics. Furthermore, the material exhibited a significant electrochemical surface area (ECSA) compared to bare NF. Chronoamperometry over 24 h confirmed the operational durability catalyst, stabilizing around 7–8 mA/cm², validating its potential as a cost-effective and efficient OER electrocatalyst in alkaline media. Full article

The glioma tumor microenvironment (TME) exhibits profound heterogeneity that drives tumor progression and therapy resistance. By integrating single-cell RNA sequencing (eleven samples) and spatial transcriptomics (two samples), the cellular components of the glioma microenvironment were deconvoluted, revealing tumor-associated foam cells (TAFCs) as the most abundant and centrally connected subtype. The high expression of two prognostic candidate genes, growth differentiation factor 8 (GDF-8, also known as myostatin, MSTN) and transcription factor 12 (TCF12), in TAFCs was found to be correlated with poor overall survival. These two genes were associated with M2 macrophage infiltration, altered cholesterol homeostasis, and immunosuppressive signaling. Regulatory network and pathway analyses, based on computational motif enrichment and co-expression analysis, linked them to ribosome, Notch signaling, DNA repair, and cell-cycle pathways. Pseudotime trajectories revealed dynamic expression during differentiation. Additionally, drug sensitivity prediction analysis demonstrated that MSTN expression was significantly associated with sensitivity to paclitaxel and VE-822, while TCF12 expression showed potential associations with sensitivity to cytarabine, olaparib, Wee1 inhibitor, paclitaxel, and VE-822. Logistic regression analysis combining clinical parameters with MSTN and TCF12 expression effectively achieved risk stratification for glioma, with higher composite scores predicting worse 2- and 3-year survival outcomes. Calibration curves demonstrated high consistency between nomogram-predicted overall survival probabilities and actual observed outcomes. Immunofluorescence confirmed upregulated expression of MSTN and TCF12 in glioma tissues and their co-localization with macrophages. In conclusion, this study identified TAFCs as the central cells in the glioma microenvironment, with their signature genes MSTN and TCF12 representing candidate immunometabolic signatures associated with macrophage-mediated immunosuppression and metabolic reprogramming in glioma, suggesting their potential as biomarkers for patient stratification and as targets for immunometabolic therapies. Full article

This study addresses high water cut and low recovery in bottom-water sandstone reservoirs by optimizing CO₂ and N₂ foam flooding parameters. The key innovation is the pioneering application of fractal dimension to quantitatively characterize water coning morphology during composite gas flooding. A numerical simulation assessed composite gas type, injection gas ratio, sequence, speed, volume, and injection–production ratio. Fractal dimension quantified water coning. Optimal conditions were: 2:1 injection gas ratio (CO₂ then N₂ foam), 140 t/d injection speed, 0.31 PV volume, and 1:3.2 injection–production ratio. This achieved 39.52% recovery over 15 years—a 4.89% increase, adding 3.17 × 10⁴ t of oil. Fractal dimension fell to 1.672. Sensitivity analysis showed the injection gas ratio most affects oil output. The injection volume best suppresses water coning. The injection speed has low sensitivity. Key interactions exist between volume, gas type, and injection–production ratio. Injection gas ratio, volume, and injection–production ratio are crucial for development control. The proposed methodology presents a viable strategy for enhancing oil recovery in similar reservoirs, with broader implications for advancing CO₂ utilization and supporting carbon management objectives in the petroleum industry. Full article

We report the facile synthesis of hierarchical spiked cobalt selenide (Co_0.85Se) microcrystals grown on nickel foam (NF) via a hydrothermal method followed by selenization. Derived from cobalt hydroxyl fluoride (Co(OH)F) microcrystals, the resulting Co_0.85Se structures exhibit a robust architecture with well-defined spikes that offer abundant active sites and promote efficient charge transfer, thereby enhancing their electrocatalytic bifunctional activity toward the oxygen evolution reaction (OER) and urea oxidation reaction (UOR). The Co_0.85Se/NF electrode delivers low overpotentials of 357 mV for OER and 236 mV for UOR at 100 mA cm⁻². Furthermore, it exhibits a small Tafel slope (34.3 mV dec⁻¹) and excellent durability for 24 h at 100 mA cm⁻² during UOR. This simple and cost-effective strategy highlights the potential of hierarchical spiked Co_0.85Se microcrystals as highly efficient electrocatalysts for urea-assisted OER and related sustainable energy conversion applications. Full article

As surface-active functional compounds, defoamers play a pivotal role in seawater desalination processes. In this study, a polyether-modified silicone compound was synthesized, and its structure was confirmed through FITR and ¹H-NMR characterization. Using this compound as the main component, a more effective and stable composite defoamer product was obtained through a co-optimization method. The particle size of the defoamer ranged from 600 to 700 nm in aqueous systems, and the surface tension could be reduced to 27.46 mN/m, thereby exhibiting superior defoaming and antifoaming properties. Additionally, the defoamer demonstrated good compatibility with commonly used scale inhibitors and was non-corrosive to equipment. Industrial testing further confirmed its efficacy in controlling foam during seawater desalination effectively. Full article

The integrated valorization of whey into multifunctional food ingredients is constrained by sequential processing routes and the need for purified lactose and protein fractions. The simultaneous enzymatic conversion of lactose and whey proteins in a single reactor remains underexplored despite the frequent co-formulation of galacto-oligosaccharides (GOS) and whey protein hydrolysates in functional foods. This study evaluated the feasibility of a one-pot enzymatic system using native whey as the sole substrate for the concurrent production of GOS and antioxidant peptide fractions. A batch process combining β-galactosidase from Aspergillus oryzae and Alcalase^® was assessed through a 3² factorial design, analyzing the effects of pH (4.5–6.5) and temperature (40–60 °C) on GOS yield and degree of protein hydrolysis. The system enabled simultaneous transgalactosylation and proteolysis under mildly acidic conditions without significant mutual enzyme inhibition. Multi-response optimization identified pH 6.0 and 59.5 °C as the optimal conditions, yielding 25.7 ± 0.2% GOSs and 10.5 ± 0.3% protein hydrolysis. The antioxidant capacity and emulsifying and foaming properties were strongly dependent on pH, temperature, and reaction time. The results demonstrate that native whey can be directly transformed into a multifunctional ingredient through a one-pot enzymatic strategy, offering a simplified valorization approach. Full article