Search Results (9,140)

Global demand for sustainability drives interest in bioenergy from sustainable feedstock. Agro-industrial waste such as brewer’s spent grains (BSG) is an important by-product of brewing. This study provides a comprehensive review of the current technologies of BSG for energy recovery and BSG-based materials for energy storage applications. The latest scientific progress, not only from conventional processes on anaerobic digestion, combustion, gasification, pyrolysis, torrefaction, and hydrothermal liquefaction but also from several integrated technologies, pretreatment methods, and additives/catalysts regarding the improvement of energy efficiency and process sustainability, was reviewed. In addition, the co-feedstock practices (co-combustion, anaerobic co-digestion, hydrothermal co-liquefaction, anaerobic co-fermentation) and co-production were examined. AD of BSG yields about 302 NL CH₄/kg COD, generating roughly 0.39 kWh of electricity/kg BSG and 1.71 MJ of thermal energy/kg BSG. Ultrasonic pretreatment enhances methane production up to four times (107 L CH₄/kg TVS) and reduces CO₂ emissions by 0.083 t CO₂eq/t BSG. Anaerobic co-digestion of BSG with other brewery waste increased the yield up to 88 mL CH₄/g TVS, generated approx. 0.348 kWh/kg TVS electricity, and reduced emissions by 0.114 kg CO₂eq/kg TVS. Bioethanol yields can reach 72%, while biohydrogen generation was up to 5154 mL H₂/g glucose. BSG pyrolysis provides up to 71.8% bio-oil, and its calorific value is 18–25 MJ/kg. BSG-derived activated biocarbon has a notable surface area (1792 m²/g) for lithium–sulfur batteries. The assessment showed that BSG’s transformation into bioenergy and energy storage materials aligns with waste reduction and sustainable development goals. However, future research on combined alternative wastes, integrated technologies, green nanotechnology, and artificial intelligence technology could lead to optimal performance and facilitate their industrial application. Full article

The introduction of sustainable practices into waste management can have a favorable environmental impact, increase resource value, and yield economic gains. Hydrothermal technologies have strong potential for the production of up-cycled ingredients from biowaste (amino acids, sugars, phenols, pharmacologically active compounds, etc.), enabling high energy recovery (50–80%) from biowaste with net-negative carbon emissions. This review discusses the use of subcritical and supercritical water technologies for sustainable valorization of biowaste and conversion of biomass into high-value chemicals and biofuels. The potential for the extraction/generation of bioactive compounds from plant and animal waste is presented, emphasizing the efficiency, compound stability, and bioactivity of the fractions obtained. The possibilities of simultaneous extraction of added-value compounds and hydrolysis of feedstock biopolymers by these technologies are elaborated. The review further addresses the production of biofuels through hydrothermal carbonization for solid fuels, hydrothermal waste liquefaction for liquid fuels, and supercritical water gasification for gaseous fuels. The paper highlights the environmental and economic advantages of technologies based on sub- and supercritical water over conventional chemical and fermentative routes, emphasizing their contribution to a circular bioeconomy by converting biowaste into value-added products and sustainable energy sources. Full article

This research examines the hydrothermal corrosion behaviour of ceramic matrix composites (CMCs) under highly alkaline conditions (pH > 11.5) in the framework of a deep geological repository for high-level radioactive waste (HLW). The study focuses on the degradation of alumina powder and fibres, key constituents of an oxide/oxide CMC material. Accelerated ageing experiments were conducted in a highly alkaline aqueous environment (pH > 11.5, T = 70 °C for 220 days and T = 150 °C for 30 days). The research used a cross-disciplinary approach integrating thermodynamic calculations and physicochemical analyses to determine the degradation mechanisms of alumina powder and fibres induced by contact with the aqueous ageing solution. Characterisation of the aged alumina powders and fibres revealed the presence of unaltered alumina, hydrated alumina, amorphous phases, and calcium carbonate precipitates from the aqueous solution. Thermodynamic calculations indicate (1) the hydrolysis of alumina to diaspore and (2) the formation of an aluminosilicate phase and calcium carbonate. However, experimental results reveal kinetic limitations, such as the preferential formation of boehmite over diaspore, and morphology-dependent degradation pathways (protective-layer formation on fibres and partial dissolution of powders). Full article

The Gebel Shalman-Wadi Biarn (GSh-WB) area in Egypt’s South Eastern Desert hosts NYF-type rare-metal pegmatites with significant U, Th, Nb-Ta, and REEs mineralization. This study integrates field observations, petrography, mineralogy, whole-rock geochemistry, and gamma-ray spectrometry to characterize these pegmatites and evaluate their economic potential. The pegmatites occur as veins, dykes, and zoned pockets hosted entirely within syenogranites. Petrography, pegmatites, and syenogranites are primarily composed of K-feldspar, albite, and quartz with trace amounts of biotite and muscovite. The environmental scanning electron microscope (ESEM) revealed the presence of the following minerals: autunite, kasolite, thorite, monazite-(Ce), parisite, xenotime-(Y), ferrocolumbite, hydroxyplumbobrtafite, aeschynite-(Y), and zircon, which are the major U-Th, Nb-Ta, and REE-bearing minerals. Additionally, gold, cassiterite, wolframite, pyrrhotite, chalcopyrite, and brass alloy were identified as sources of precious and base metals. Both groups’ chondrite-normalized REE patterns, which display slightly elevated LREE patterns and negative Eu anomalies, point to fractional crystallization involving plagioclase fractionation. Consequently, pegmatite and syenogranites are believed to have mostly formed from the partial melting of a reconstituted juvenile crust and its weathered sediments associated with Neoproterozoic magmatism. The marginally positive Ce anomaly in the (GSh-WB) pegmatites (1.02–0.98) may be associated with monazite crystallization resulting from enhanced fractionation. The Th and U levels range from 101 to 28.6 ppm and from 51 to 5.8 ppm, respectively. The magnitude of the tetrad effect in the rare earth elements of the analyzed rocks exceeds one (T1 = 1.12–1.02, T3 = 0.92–1.08, and T1,3 = 1.01–1.05), suggesting an M-type tetrad effect. The presence of this tetrad effect is indicative of granite that has been significantly altered by hydrothermal processes and is extensively fractionated. Chondrite-normalized REE patterns of the pegmatites (average ΣREE = 439 ppm) and their host syenogranites (average ΣREE = 192 ppm) show similar trends characterized by enrichment of light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs) and pronounced negative Eu anomalies (Eu/Eu* = 0.09–0.22). These features, together with negative Sr and Ba anomalies, likely reflect extensive fractional crystallization of feldspars and feature anorogenic rocks. Spectrometric analysis reveals eU values of 2.0–288 ppm and eTh values of 7.0–455 ppm in pegmatite samples, with eU/eTh ratios (0.49–0.39) exceeding the typical continental crust value of 0.25, indicating uranium enrichment. Both magmatic and hydrothermal processes contributed to the observed radioactivity. The spatial distribution of uranium shows lithological and structural controls. The GSh-WB pegmatites represent a potential target for uranium exploration. Full article

Anaerobic digestion (AD) of lignocellulosic biomass is often constrained by biomass recalcitrance, limiting methane recovery. This study investigated whether low-temperature dilute-acid hydrothermal pretreatment could enhance methane production from pine nut shells (PNSs), a lignin-rich and underutilized agro-industrial residue, and whether derivative-based kinetic landmarks could provide a more systematic characterization of batch AD performance. Methane production was significantly improved by dilute sulfuric acid and hydrothermal pretreatments. The highest methane yield (201.8 mL CH₄ g⁻¹ VS) was achieved under the combined 100 °C hydrothermal and 2.5% H₂SO₄ condition, representing approximately 1.8-fold and 3.3-fold increases compared with hydrothermal-only and untreated PNSs, respectively. Enhanced performance was attributed to hemicellulose solubilization, lignin disruption, and improved substrate accessibility. In contrast, excessive acid severity resulted in process instability, associated with total volatile fatty acid accumulation and pH reduction. The Modified Logistic Model (MLM) was further used to derive five kinetic landmarks (PAA, PAM, PI, PDM, and PDA) describing phase-specific features of cumulative methane production curves. While these landmarks provide a model-based framework for comparing batch AD kinetics, their nearly constant normalized yields primarily reflect the geometry of the fitted logistic function rather than independent biological invariants. Overall, the results identify 100 °C hydrothermal pretreatment with 2.5% H₂SO₄ as an effective moderate-severity strategy for enhancing methane recovery from PNSs and demonstrate the utility of MLM-derived landmarks as comparative descriptors of phase-resolved methane production. Full article

The transition to a circular economy requires the safe management of sewage sludge through nutrient and energy recovery. However, pharmaceuticals and personal care products (PPCPs) present a significant challenge. These compounds tend to accumulate in sludge via sorption, shifting the environmental burden from the aqueous phase to the sludge. This manuscript provides a comprehensive review of the scientific literature on technical alternatives for valorizing sewage sludge and removing emerging contaminants. The study evaluates the limitations of conventional biological methods, such as anaerobic digestion and composting, which exhibit variable efficacy and are often insufficient to degrade some commonly used pharmaceuticals. On the contrary, thermal treatments (pyrolysis, gasification, and hydrothermal processes) are considered robust alternatives capable of achieving the high removal of chemical compounds. Furthermore, the article emphasizes the innovative potential of utilizing carbon-based byproducts (biochar and hydrochar) as adsorbents, catalysts, or soil amendment to enhance the removal of PPCPs within the treatment infrastructure itself. The integration of advanced thermal technologies is essential to mitigate the risks of contaminant transfer to the food chain and ensure a safe and sustainable nutrient cycle. Full article

This Communication reports limited engineering screening data on polymer liner candidates for flexible composite pipes used in oil and gas service. Three exposure conditions were considered: hydrothermal aging in superheated water, thermal-oxidative aging in dry air, and hydrocarbon-medium exposure. Superheated-water immersion for up to 1000 h, dry-air aging for 168 h, and 7-day hydrocarbon exposure were used to describe changes in tensile properties, Shore hardness, mass, and thickness. Complete replicate records were available only for the thermal-oxidative aging dataset; therefore, most hydrothermal and hydrocarbon-medium results are reported as descriptive summary data. In the recorded data, EPDM formulation CL-2-1 retained approximately 89% of its tensile strength after 1000 h in superheated water. Sample L showed a smaller mean tensile-strength decrease than Sample Z after 168 h at 150 °C in dry air. In the hydrocarbon-medium summary data, XL95A/05B-S1 showed lower mass increase and smaller tensile-strength and yield-stress decreases than PERT XRT70H across the tested temperature range. The Communication provides case-specific screening evidence and identifies the need for replicated testing, statistical analysis, longer aging series, and structural characterization before general material-selection or durability conclusions are made. Full article

Zeolite morphology strongly determines its performance. Herein, Silicalite-1 was synthesized in a low-template system (TPA⁺/Si = 0.007) via a synergistic strategy using potassium bisulfate and seed suspension. The seeds supply abundant structural units to reduce nucleation barrier and accelerate crystallization, while KHSO₄ facilitates silicate polycondensation and suppresses non-MFI impurities. Sulfate ions selectively adsorb on specific crystal facets via hydrogen bonding and induce preferential crystal growth along the c-axis. The c-axis size of Silicalite-1 can be precisely regulated by adjusting dosages of seeds and KHSO₄. Well-defined plate-like crystals were obtained under the conditions of K⁺/Si = 0.25, a seed content of 2.42 wt%, and hydrothermal treatment at 180 °C for 8 h. Scale-up synthesis in a 2 L autoclave verifies its industrial potential. The product exhibits excellent adsorption capacity and cyclic stability toward methylene blue. This work provides a low-cost and green route for morphology-controlled synthesis of MFI-type zeolites. Full article

Thermal regulation of electrode materials offers an effective strategy for optimizing electrochemical kinetics in phosphate-based energy-storage systems. In this work, cobalt phosphate (Co₃(PO₄)₂) (CoP) electrodes were directly synthesized on nickel foam through a hydrothermal route and subsequently annealed at different temperatures (300, 400, and 500 °C) to investigate the influence of thermal treatment on structural evolution and supercapacitive behavior. X-ray diffraction confirmed the formation of crystalline CoP, while FESEM analysis revealed a strong dependence of morphology on annealing temperature, with CoP-400 exhibiting a well-developed interconnected plate-like architecture favorable for ion transport. XPS and elemental mapping verified the successful incorporation and uniform distribution of Co, P, and O species. Electrochemical investigations demonstrated that annealing temperature critically governs charge-storage behavior, ion diffusion, and mass transport properties. Among all electrodes, CoP-400 exhibited the best electrochemical performance, delivering a high areal capacitance of 28.62 F/cm² at 20 mA/cm², together with the highest ionic diffusion coefficient, lowest equivalent series resistance (0.39 Ω), and dominant diffusion-controlled charge-storage contribution (89%). Furthermore, CoP-400 retained 84.44% capacitance after 12,000 cycles. An asymmetric supercapacitor assembled using CoP-400//AC achieved an areal capacitance of 302 mF/cm², an energy density (ED) of 0.094 mWh/cm², and excellent cycling stability. These findings highlight annealing-engineered CoP as a promising electrode material for high-performance asymmetric supercapacitors. Full article

Optimizing nitrogen management is essential for maintaining high spring maize yield while mitigating nitrous oxide (N₂O) emissions in irrigated areas. However, the interactive effects of total nitrogen application rate and starter nitrogen proportion on yield and N₂O emissions remain insufficiently quantified. Reliable assessment of these interactions requires well-calibrated DeNitrification–DeComposition (DNDC) simulations, yet existing calibration studies often emphasize crop parameters while neglecting soil parameters critical for soil hydrothermal dynamics and N₂O production. In this study, field data from shallow-buried drip-irrigated spring maize in Tongliao during 2024–2025 were used to conduct Extended Fourier Amplitude Sensitivity Test (EFAST) sensitivity analysis on 12 crop and 13 soil parameters of the DNDC model. Sensitive parameters were calibrated using the differential evolution algorithm, and 64 nitrogen management scenarios were simulated by combining eight total nitrogen application rates (100, 150, 200, 250, 300, 350, 400, and 450 kg N ha⁻¹) with eight starter nitrogen proportions (0%, 15%, 25%, 30%, 35%, 40%, 45%, and 50% of the total nitrogen rate). The results showed that DNDC outputs were jointly controlled by crop and soil parameters, among which maximum yield, leaf carbon-to-nitrogen ratio, stem fraction, grain carbon-to-nitrogen ratio, thermal degree days for maturity, grain fraction, soil organic carbon (SOC) decrease rate below topsoil, soil clay content, soil porosity, wilting point and depth of top soil with uniform SOC content were dominant. Compared with the conventional crop-parameter calibration, the sensitivity-screened parameter set improved the simulation of both cumulative N₂O emissions and yield. Across the 64 scenarios, cumulative N₂O emissions ranged from 0.42 to 4.87 kg [N]/ha, while simulated maize yield ranged from 1597 to 6347 kg [C]/ha. N₂O emissions increased with total nitrogen rate, whereas yield increased initially and then reached a plateau. Increasing the starter nitrogen proportion did not substantially enhance yield but increased N₂O emission risk under high nitrogen rates. Overall, the scenario with 300 kg/ha and no nitrogen applied at sowing achieved a relatively high yield of 5519 kg [C]/ha while maintaining a low cumulative N₂O emission of 0.98 kg [N]/ha and was therefore identified as the preferred trade-off strategy under shallow-buried drip irrigation. This study provides an EFAST–DNDC framework for optimizing nitrogen management to sustain spring maize yield while reducing N₂O emissions in the West Liaohe Plain. Full article

Based on eddy covariance data collected during March to June 2021 in the Gurbantunggut Desert, this study analyzed desert methane (CH₄) flux dynamics. Results show the following: (1) The desert functions as a weak methane sink from March to June in the growing season, with its CH₄ flux showing a U-shaped diurnal variation pattern. The absorption peak occurred in June, reaching −79.1 mg·m⁻²·month⁻¹. (2) Diurnally, CH₄ flux correlated negatively with soil temperature (Tsoil), vapor pressure deficit, and photosynthetically active radiation (r_Tsoil = −0.58, r_VPD = −0.49, r_PAR = −0.49), positively with soil water content (SWC) and relative humidity (RH) (r_RH = 0.53, r_SWC = 0.28). (3) Fixed-effects regression isolated individual and interactive effects of SWC and Tsoil, yielding the model: CH₄ = −0.002 − 0.017SWC − 0.00004Tsoil − 0.002(SWC × Tsoil). The model highlights CH₄ flux sensitivity to hydrothermal factors and underscores the importance of their interaction for accurate flux estimation and understanding arid zone carbon cycle-climate feedbacks. Full article

Niche and interspecific association are important components of community ecology and are of great significance for revealing the mechanisms of community assembly and its stability. In this study, the woody plant communities of Betula platyphylla Sukaczev forests in the Niyang River Basin of southeastern Qinghai–Tibet Plateau were taken as the research object. The niche, interspecific association, and community stability of dominant tree species in B. platyphylla forests were analyzed using the Levins index (B_L), Shannon index (B_S), Pianka index (O_ik), Schoener index (C_ik), variance ratio (VR), chi-square test, association coefficient (AC), Spearman rank correlation, and M. Godron stability methods. The results showed that a total of 71 woody plant species were recorded across 48 plots, mainly belonging to Rosaceae, Ericaceae, and Caprifoliaceae. B. platyphylla, Quercus aquifolioides Rehder & E. H. Wilson, Sorbus rehderiana Koehne, and Berberis gyalaica Ahrendt had relatively large niche breadths, indicating strong resource utilization ability and a wide range of spatial adaptation. They were the main constructive species and dominant species of B. platyphylla forest communities in this basin. The overall niche overlap of woody plant communities was relatively low, indicating relatively obvious differentiation in resource utilization among different species. Interspecific association analysis showed that the dominant species in the tree layer exhibited an overall significantly positive association, whereas those in the shrub layer exhibited an overall non-significantly positive association. The associations between species pairs were mainly non-significant, and the overall interspecific association was weak. Most species showed a relatively independent distribution pattern, reflecting weak interspecific competition within the community. Community stability analysis showed that the Euclidean distance between the tree layer and the theoretical stability point (20, 80) was 20.17, whereas that of the shrub layer was 27.98, indicating that the tree layer was more stable than the shrub layer. Overall, the community may not yet have reached a fully stable state. The results provide important references for biodiversity conservation, vegetation restoration, and sustainable forest management in alpine canyon ecosystems. Future studies should incorporate environmental factors such as soil properties and hydrothermal conditions to further reveal the ecological mechanisms driving community succession and stability. Full article

Hydrothermal alteration mapping is a critical component of porphyry copper exploration because alteration assemblages provide important vectors toward mineralization. This study presents a systematic evaluation of supervised machine learning algorithms for delineating hydrothermal alteration zones using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) short-wave infrared (SWIR) surface reflectance data (AST_07XT). The investigation focuses on the Nain region within the central Urumieh–Dokhtar Magmatic Arc (UDMA), Iran, a major metallogenic belt hosting numerous porphyry copper systems. Representative spectral endmembers corresponding to Al–OH-bearing and Mg–OH-bearing hydrothermal alteration minerals were extracted using Minimum Noise Fraction (MNF), Pixel Purity Index (PPI), and n-dimensional visualization techniques. These endmembers were subsequently used to train and evaluate a comprehensive suite of supervised machine learning classifiers, including linear, kernel-based, tree-based, ensemble, probabilistic, boosting, and neural-network algorithms for pixel-wise hydrothermal alteration mapping. Model performance was evaluated using multiple statistical metrics, including overall accuracy (OA), average accuracy (AA), precision, recall, F1-score, Cohen’s kappa coefficient, area under the ROC curve (AUC), spatial cross-validation accuracy, uncertainty analysis, and spatial agreement analysis. Among the evaluated classifiers, SVM_Linear, SVM_RBF, LDA, and MLP achieved the highest classification performance, with overall accuracies exceeding 94% and strong spatial consistency between classified maps. The resulting alteration maps display spatially coherent distributions of Al–OH and Mg–OH minerals that are consistent with established hydrothermal alteration zoning models in porphyry–epithermal systems. The mapped hydrothermal alteration zones show strong spatial correspondence with known mineralized areas and alteration patterns within the Urumieh–Dokhtar Magmatic Arc, confirming the geological reliability of the classification results. Uncertainty analysis further indicates high model confidence across most alteration zones, with higher uncertainty values mainly restricted to transitional and spectrally heterogeneous regions. The results demonstrate that integrating ASTER SWIR imagery with supervised machine learning algorithms provides a robust, scalable, and transferable framework for regional-scale hydrothermal alteration mapping and mineral exploration in porphyry copper provinces. Full article

Recent hydrothermal extremes threaten soybean productivity in rainfed systems of Southeastern Europe, but single-location field datasets require cautious interpretation. This study evaluated cultivar-level soybean yield variability in large-scale rainfed field trials near Osijek, eastern Croatia, during 2020–2025 and compared the climatic context of the adverse 2024 and 2025 seasons. Grain yield, adjusted to 13% moisture, was analyzed across years and maturity groups (MGs) using ANOVA, Fisher’s LSD mean separation, ANCOVA/linear trend analysis, and exploratory climate–yield correlations. Daily station data for 2024–2025 were used to calculate extreme-temperature indices. ANOVA showed a highly significant year effect on yield (p < 0.001), whereas MG and Year × MG were not significant. Fisher’s LSD separated 2023 and 2021 as the highest-yielding years, 2024 as intermediate, and 2022 and 2025 as the lowest-yield group. ANCOVA indicated a significant negative common temporal trend (−0.155 t ha⁻¹ year⁻¹; p < 0.001). Yield was positively associated with June–August precipitation (Pearson r = 0.885; n = 6). The 2024 season showed a stronger heat-related signal, whereas 2025 showed a stronger precipitation-deficit signal. The results should be interpreted within the limits of a site-specific, unbalanced field-trial dataset. Full article

Nickel ferrite (NiFe₂O₄) is one of the most studied inverse-spinel ferrites because it combines moderate saturation magnetization, comparatively high electrical resistivity, chemical stability, and broad synthesis flexibility. Yet the literature shows that the measured structure and magnetism of NiFe₂O₄ are not intrinsic constants; they evolve strongly with dimensionality, size, thickness, strain state, cation distribution, surface spin disorder, and synthesis pathway. This review develops a unified theoretical and literature-based interpretation of how dimensionality reshapes the structural and magnetic behavior of NiFe₂O₄ across bulk ceramics, nanoparticles, one-dimensional nanostructures, polycrystalline thin films, and ultrathin epitaxial films. The review is anchored in the two uploaded nickel ferrite attachments and expanded using internet-sourced journal literature on spinel inversion, surface effects, mechanochemical synthesis, sputtered and pulsed laser deposited thin films, and epitaxial ultrathin-film anomalies. The central novelty of this article is the formulation of a dimensionality-dependent framework in which the observed magnetic response is governed by a competition among three coupled factors: (i) the cation-distribution function, which controls the A–B superexchange balance and therefore the net ferrimagnetic moment; (ii) the microstructural coherence function, which measures how crystallinity, strain, defects, and anti-phase boundaries preserve or degrade exchange continuity; and (iii) the surface/interface spin-order parameter, which quantifies the loss or reconfiguration of magnetic order at free surfaces and buried interfaces. Within this framework, bulk NiFe₂O₄ behaves as a near-equilibrium inverse spinel with relatively stable magnetization, whereas nanoscale NiFe₂O₄ experiences strong spin canting and finite-size suppression due to the growing fraction of disordered surface spins. Thin films introduce a distinct regime in which strain, texture, anti-phase boundaries, substrate mismatch, and growth kinetics determine both anisotropy and magnetization. In ultrathin epitaxial films, off-equilibrium cation redistribution and interface-controlled electronic reconstruction may even generate magnetization values far above bulk expectations. The review also compares major synthesis routes—solid-state reaction, sol–gel, co-precipitation, hydrothermal growth, reactive milling, combustion, pulsed laser deposition, and radio-frequency sputtering—and explains why each route biases the final dimensionality-dependent properties differently. A set of word-style equations is provided to formalize spinel inversion, finite-size suppression, anisotropy scaling, coercivity trends, and superparamagnetic crossover. Beyond summarizing the field, the review proposes a regime map linking dimensionality to characteristic structural defects and magnetic signatures, and it identifies unresolved questions concerning the true origin of enhanced magnetization in ultrathin NiFe₂O₄, the interplay between anti-phase boundaries and strain, and the distinction between intrinsic inversion changes and extrinsic substrate artifacts. The resulting article offers a submission-ready, originality-focused review that positions dimensionality as the master variable governing structure–magnetism correlations in nickel ferrite. Full article