Search Results (5,360)

This study developed a sustainable high-strength coal gangue backfill material for underground mining applications using coal gangue, fly ash, and cement as primary raw materials, with red mud (RM) as an alternative alkali activator. The mechanical properties of the backfill material were systematically optimized by adjusting coal gangue particle size and alkali activator dosage. The optimized formulation (coal gangue/fly ash/cement = 5:4:1, 3–6 mm coal gangue particle size, 5% RM, which named BF-6-5RM) achieved superior compressive strengths of 8.23 MPa (7 days) and 10.5 MPa (28 days), significantly exceeding conventional backfill requirements and outperforming a CaO-activated reference system (coal gangue/fly ash/cement = 5:4:1, 3–6 mm coal gangue particle size, 2% CaO, which named BF-6-2CaO). Microstructural and physicochemical analyses revealed that both formulations produced calcium silicate hydrate gels (C-S-H gels) and ettringite (AFt) as key hydration products, though BF-6-5RM exhibited a denser microstructure with well-developed ettringite networks and no detectable portlandite (CH), explaining its enhanced early-age strength. Environmental assessments confirmed effective heavy metal immobilization via encapsulation, adsorption, precipitation and substitution, except for arsenic (As), which exceeded Class III groundwater thresholds (DZ/T 0290-2015) due to elevated raw material content, displaying “surface wash-off, diffusion and depletion” leaching behavior. The findings confirm that red mud-based alkali activation is a viable technology for underground backfilling, provided it is coupled with arsenic control strategies like chemical stabilization or the selection of low-arsenic raw materials. This approach not only enables the resource utilization of hazardous industrial waste but also facilitates the production of backfill materials that combine both mechanical strength and environmental compatibility, thereby delivering dual economic and ecological benefits for sustainable mining practices. Full article

Nectar composition varies across plant species and environments, influencing pollinator interactions and honey quality. Reliable methods for nectar discrimination, however, remain limited. Here, we demonstrate the use of Fourier-transform infrared (FTIR) spectroscopy combined with chemometric analysis to differentiate nectar samples of Echium vulgare (E. vulgare) and Hedera helix (H. helix) collected in urban locations. Among eight tested preprocessing strategies, simple approaches such as Savitzky–Golay smoothing or even raw spectra provided the best clustering results. The most discriminative spectral regions were consistently the carbohydrate fingerprint (1200–950 cm⁻¹) and the C–H stretching zone (2935–2885 cm⁻¹). Mean spectra and PCA confirmed that variability between locations arises mainly from carbohydrate-associated bands, while solvent type, biological matrix, and environmental exposure also affect spectral fingerprints. These results highlight FTIR spectroscopy as a rapid, non-destructive, and robust method for nectar discrimination, with potential applications in food authentication, ecological research, and pollinator–plant studies. Full article

A multiscale 3D CFD model of CO₂ methanation over Ni/Al₂O₃ was developed in COMSOL Multiphysics 6.3 for a lab-scale isothermal fixed-bed Sabatier reactor and validated against published data. The multiscale approach integrated bulk convection–diffusion, fluid flow, and pressure distribution with intraparticle diffusion–reaction phenomena coupled with Langmuir–Hinshelwood–Hougen–Watson-based kinetics, thus solving mass-transfer limitations without empirical effectiveness factors. Model validation was carried out by (i) kinetics, (ii) reactor performance, and (iii) hydrodynamics. Simulation results showed strong diffusion-dominated species transport at the bed entrance that lessened downstream as partial pressures decreased and products accumulated, resulting in a diffusion-relieved regime near the outlet. Sensitivity studies identified 320–350 °C and up to 10 bar as favorable conditions for high CH₄ yield. Additionally, slightly H₂-rich feed accelerated approach to equilibrium, while lower flow rates achieved near-complete conversion within the first half of the reactor bed. Simulations were carried out in COMSOL Multiphysics 6.3 on a dual Intel Xeon Platinum 8168 (48 cores at 2.7 GHz) workstation with 512 GB RAM to solve a 12-million-element mesh. The developed framework identifies a practical operating window and quantifies the conversion–throughput trade-off with flow rate, guiding operating condition selection and providing a basis for process intensification and lab-to-pilot scale-up of CO₂ methanation. Full article

The use of hydrogen as an energy carrier represents a promising alternative for mitigating climate change. However, its practical application requires achieving a high degree of purity throughout the production process. In this study, the influence of the type of catalytic support on H₂ production via steam glycerol reforming was evaluated, with the objective of obtaining syngas with the highest possible H₂ concentration. Three types of support were analyzed: two natural materials (zeolite and dolomite) and one metal oxide, alumina. Alumina and dolomite were coated with Ni at different loadings, while zeolite was only evaluated without Ni. Reforming experiments were carried out at a constant temperature of 850 °C, with continuous monitoring of H₂, CO₂, CO, and CH₄ concentrations. The results showed that zeolite yielded the lowest H₂ concentration (51%), mainly due to amorphization at high temperatures and the limited effectiveness of physical adsorption processes. In contrast, alumina and dolomite achieved H₂ purities of around 70%, which increased with Ni loading. The improvement was particularly significant in dolomite, owing to its higher porosity and the recarbonation processes of CaO, enabling H₂ purities of up to 90%. Full article

In 2024, the global average temperature reached 1.55 °C above the pre-industrial level for the first time. However, we could still keep the long-term global average temperature below 2 °C if all possible measures are taken to mitigate greenhouse gases. It is widely accepted that methane (CH₄) mitigation can slow global warming in the near term. Among all approaches toward this goal, the utilization of aerobic methanotrophs, which are natural catalysts for the conversion of CH₄, emerges as a promising solution. Previously, we identified a candidate for CH₄ mitigation, Methylotuvimicrobium buryatense 5GB1C, which exhibits a greater growth rate and CH₄ consumption rate than other known methanotrophs at 500 ppm CH₄. In this study, we address aspects of the practical applications of this methanotroph for CH₄ mitigation. We first examined temperature and medium conditions to optimize M. buryatense 5GB1C growth at 500 ppm CH₄. The results show that M. buryatense 5GB1C has a broad optimal temperature range for growth at 500 ppm, from 15 °C to 30 °C, and that its growth rate is consistently improved by 20–30% in 10-fold-diluted medium. Next, to demonstrate the feasibility of CH₄ removal at low concentrations by this methanotroph, we applied it in a laboratory-scale packed-bed column reactor for the treatment of 500 ppm CH₄ and tested different packing materials. The column reactor experiments revealed a maximum elimination capacity of 2.1 g CH₄ m⁻³ h⁻¹ with 2 mm cellulose beads as the packing material. These results demonstrate that with further technological innovation, this methanotroph has the potential for real-world methane mitigation. Full article

To evaluate the effect of nitrogen and hydrogen on the corrosion resistance of diamond-like carbon (DLC) coatings, potentiodynamic tests were carried out on DLC coatings deposited under various reactive atmosphere compositions on martensitically hardened 34CrAlNi steel. In order to replicate actual operating conditions of steel components, the tests were conducted both in a reference 3.5% NaCl solution and in natural mine waters, which are in direct contact with mining gearbox mechanisms. Although it is generally assumed that the addition of other elements tends to deteriorate the corrosion resistance of amorphous carbon coatings, such doping simultaneously improves adhesion to metallic substrates, and enhanced adhesion in turn contributes to improved corrosion resistance. Variation in the proportions of the doping elements altered the damage morphology on the sample surface, as well as the corrosion current density, corrosion potential, and polarization resistance. Improvements in corrosion resistance parameters correlated with the quality of the coating–substrate adhesion, evaluated in accordance with the VDI3918 standard. The most favorable properties were obtained for coatings deposited under a gas composition of N₂:CH₄:H₂ with a ratio of 3:4:2. Full article

Shape memory polymer composites (SMPCs) are an intelligent class of materials capable of self-actuation, offering promising applications in diverse stimuli-responsive material systems. This study developed epoxy-based SMPCs reinforced with carbon–aramid fibers at a 15:85 ratio, with their glass transition temperature (T_g) tailored by incorporating 5 wt.% (SMPC-5) and 10 wt.% (SMPC-10) polyethylene glycol (PEG-600). Dynamic mechanical analysis (DMA) confirmed that PEG addition effectively reduced the T_g from 89.79 °C in the neat composite (SMPC-P) to 70.28 °C in SMPC-5 and 59.34 °C in SMPC-10. Incorporating 5 wt.% PEG enhanced storage and loss moduli, whereas excessive plasticization at 10 wt.% reduced stiffness. Infrared spectroscopy analysis revealed shifts and increased intensities in hydroxyl (OH), aliphatic C-H, and carbonyl (C=O) groups, indicating enhanced intermolecular interactions and bond formation. Tensile testing showed that the carbon–aramid filler significantly improved tensile strength and stiffness, with SMPC-10 achieving the highest tensile strength (233.59 MPa) and SMPC-5 the highest Young’s modulus (14.081 GPa). These results highlight the complementary role of carbon–aramid reinforcement and PEG plasticization in tuning thermomechanical behavior, providing baseline insights for designing SMPCs with tailored actuation and reliable structural performance. Full article

Under the constraints of the “dual carbon” goals, accurately depicting the full life cycle carbon footprint of green hydrogen and its derivatives and quantifying the potential for emission reduction is a prerequisite for hydrogen energy policy and investment decisions. This paper constructs a unified life cycle model, covering the entire process from “wind and solar power generation–electrolysis of water to producing hydrogen-synthesis of methanol/ammonia-terminal transportation”, and includes the manufacturing stage of key front-end equipment and the negative carbon effect of CO₂ capture within a single system boundary, and also presents an empirical analysis. The results show that the full life cycle carbon emissions of wind power hydrogen production and photovoltaic hydrogen production are 1.43 kgCO₂/kgH₂ and 3.17 kgCO₂/kgH₂, respectively, both lower than the 4.9 kg threshold for renewable hydrogen in China. Green hydrogen synthesis of methanol achieves a net negative emission of −0.83 kgCO₂/kgCH₃OH, and the emission of green hydrogen synthesis of ammonia is 0.57 kgCO₂/kgNH₃. At the same time, it is predicted that green hydrogen, green ammonia, and green methanol can contribute approximately 1766, 66.62, and 30 million tons of CO₂ emission reduction, respectively, by 2060, providing a quantitative basis for the large-scale layout and policy formulation of the hydrogen energy industry. Full article

Understanding the formation mechanisms of three-phase products during biomass pyrolysis is essential for optimizing thermochemical conversion and enhancing the efficient utilization of renewable resources. In this study, wheat straw (WS) and pine sawdust (PS) were selected as representative feedstocks to investigate the thermal decomposition behavior and evolution characteristics of gas, liquid (tar), and solid (char) products during pyrolysis. Thermogravimetric analysis and kinetic modeling revealed that PS exhibited higher activation energy (75.44 kJ/mol) than WS (65.63 kJ/mol), indicating greater thermal resistance. Tar yield increased initially and then declined with temperature, peaking at 700 °C (37.79% for PS and 32.82% for WS), while the composition shifted from oxygenated compounds to polycyclic aromatic hydrocarbons as temperature rose. FTIR analysis demonstrated that most functional group transformations in char occurred below 400 °C, with aromatic structures forming above 300 °C and stabilizing beyond 700 °C. Gas product evolution showed that WS produced higher CO and H₂ yields due to its composition, with CH₄ generated in relatively lower amounts. These findings provide insights into biomass pyrolysis mechanisms and offer a theoretical basis for targeted regulation of product distributions in bioenergy applications. Full article

This work presents an innovative approach to enhancing the performance of concrete with reclaimed asphalt pavement (RAP) aggregates using titanium dioxide (TiO₂) nanoparticles. Traditional limestone coarse aggregates were partially replaced with 30% and 50% RAP aggregates; a subset of mixtures containing RAP aggregates was treated with TiO₂ nanoparticles. The rheological, mechanical, and long-term properties of concrete, along with changes in its chemical composition following the addition of RAP and TiO₂, were evaluated. Results revealed that using 30% and 50% RAP in concrete mixtures reduced their compressive strength by 18% and 27%, respectively. However, using TiO₂ in those mixtures enhanced their compressive strength by 8.7% and 6.3%. Moreover, concrete with 50% RAP exhibited an 85% increase in water absorption (the highest among all mixtures) compared to the control. TiO₂ treatment was most beneficial in the 30% RAP mixture, reducing its water absorption by 32.5% compared to its untreated counterpart. Additionally, the 30% RAP mixture treated with TiO₂ showed the highest resistance to sulfates among modified mixtures, as its compressive strength decreased by 10.4% compared to a decrease of 23% in the strength of the untreated 30% RAP mixture. Statistical analysis using single-factor ANOVA showed that integrating RAP aggregates with or without the presence of TiO₂ particles would significantly affect the concrete properties in terms of their population means. The t-test analysis, on the other hand, proved sufficient evidence that the mean values of the 30% RAP mixture treated with TiO₂ would not differ significantly from the control in terms of its slump and water absorption properties. The chemical structure analysis revealed an increase in the Si-O-Si and Si-O functional groups when using TiO₂ in RAP mixtures, suggesting improved hydration activity and accelerated C-S-H formation in the treated RAP mixtures. Moreover, distinct C-H peaks were witnessed in concrete with untreated RAP aggregates, resulting from the aged asphalt coating on the RAP, which weakened the bond between the RAP and the cementitious matrix. Full article

Crystal molecular structure of 3-(anthracen-2′-yl)-ortho-carborane was determined by single crystal X-ray diffraction study at 100 K. The asymmetric cell unit contains two enantiomeric pairs of molecules, in one of which the intramolecular dihydrogen bond CH...HB is formed with the participation of the C(1)H hydrogen of the anthracene substituent, and in the other with the participation of the C(3)H hydrogen. In all molecules, the polycyclic aromatic and carborane fragments are rotated relative to each other in such a way that the C-C bond of the ortho-carborane cage is approximately parallel to the plane of the aromatic substituent. According to quantum chemical calculations, the minimum energy corresponds to the formation of an intramolecular dihydrogen bond C(1)H...HB(4/7), whereas the C(3)H...HB(4/7) bond is formed rather as a result of intermolecular interactions in the crystal lattice. Full article

Temperature-induced instability in early-age rheology poses a major challenge to the pumpability and application of robotic plastering mortars. This study systematically investigates the temperature-dependent effects of a high-viscosity (75,000 mPa·s) hydroxyethyl methyl cellulose (HEMC) on the rheological properties and early microstructural evolution of mortars at 5 °C, 20 °C, and 40 °C. Mortars with HEMC dosages from 0 to 0.25 wt% were tested using rheological measurements, ultrasonic pulse velocity (UPV), and complementary microstructural analyses (XRD, FTIR, and SEM–EDS). Results show that HEMC reduced the initial static yield stress while monotonically increasing plastic viscosity, with the thickening effect more pronounced at higher temperatures. Notably, at 40 °C, the initial plastic viscosity of a 0.25% HEMC mix reached 14.4 Pa·s, a 133% increase compared to the control group. HEMC also effectively retarded the time-dependent increase in yield stress and stabilized plastic viscosity, thereby mitigating the adverse influence of elevated temperature. UPV confirmed that HEMC delayed microstructural formation, in agreement with the observed retardation of hydration reactions. At 40 °C, a 0.10% HEMC dosage postponed the percolation threshold from 67 min to 150 min, highlighting its strong retardation effect. Microstructural tests further revealed that HEMC delayed CH formation, refined C–S–H gels, and reduced the crystallinity of AFt, supporting the rheological and ultrasonic findings. A statistically significant, moderate-to-strong correlation (r = 0.88, R² = 0.77, p < 0.001) was established between static yield stress and UPV, indicating that macroscopic rheological resistance responds to microstructural evolution. Based on these results, the recommended HEMC dosages to achieve stable rheological performance are 0.05–0.10% at 5 °C, 0.10–0.15% at 20 °C, and 0.15–0.20% at 40 °C. Full article

Density functional theory (DFT) calculations were employed to examine how carbon defects, symbiosis, and sulfur influence the wettability of coal pyrite by analyzing H₂O adsorption on distinct surface configurations. The comparison results of adsorption energy, Mulliken population, charge density, and electronic state density of water molecules on the surface of pyrite doped with carbon atoms show that the presence of carbon doping reduces the negative value of the adsorption energy of water molecules on the pyrite surface, the C atoms on the pyrite surface form weaker C-H bonds with the H atoms in the water molecules, the Fe-O bond strength weakens, and the thermodynamic trend weakens. And the bond of the pyrite surface with adsorbed carbon changes from an Fe-O bond to an Fe-C-O bond. The adsorption of water molecules on the pyrite surface is weakened, and there is a weaker thermodynamic trend. This is because the adsorption of carbon atoms changes from hydrophilic to nearly hydrophobic. The physical adsorption of sulfur atoms changes the adsorption energy of water molecules on the pyrite surface from negative to positive, and the bond changes from an Fe-O bond to an Fe-S-O bond, indicating that the adsorption intensity of water molecules on the pyrite surface with adsorbed sulfur is weakened, and there is no thermodynamic trend. The pyrite surface with adsorbed sulfur changes from hydrophilic to hydrophobic. Under the same impurity atom doping or adsorption concentration, the influence of sulfur on the adsorption of water molecules on the surface of pyrite is the greatest, followed by the adsorbed carbon, and the weakest is the carbon atom doping. Macroscopically, the overall hydrophobicity of the surface of coal-bearing pyrite covered with sulfur is greater than that of pyrite containing adsorbed carbon and even greater than that of coal-bearing pyrite doped with carbon atoms. Full article

Ozonation is an emergent green technology that modifies the chemical composition and bioactivity of natural oils, creating new opportunities for functional and biomedical use. In this study, the chemical changes and in vitro activities of lettuce (Lactuca sativa) oil before and after ozonation were evaluated. Gas chromatography–mass spectrometry (GC–MS) revealed an increase in both the number and diversity of constituents in ozonated oil, with (Z)-13-docosenamide and trans-13-octadecenoic acid as predominant components. Fourier-transform infrared (FTIR) spectra showed overall similarity between native and ozonated oils, but with three additional characteristic bands in the ozonated sample. Bioassays demonstrated that ozonation enhanced anti-Helicobacter pylori activity (inhibition zone 21.3 ± 0.3 mm), supported bactericidal effects, and improved antibiofilm and antihemolytic properties. The antioxidant capacity of ozonated oil was modestly increased (IC₅₀ = 3.95 ± 0.4 µg/mL), while butyrylcholinesterase inhibition was more markedly enhanced (IC₅₀ = 2.58 ± 0.6 µg/mL), compared to that of the non-ozonated oil (IC₅₀ = 6.14 ± 0.3 µg/mL and IC₅₀ = 4.38 ± 0.4 µg/mL, respectively). Molecular docking suggested strong interactions of major ozonation-derived compounds with human BuChE and H. pylori urease, providing mechanistic support for the observed activities. Overall, these results indicate that ozonation modestly but consistently enhances the biological potential of lettuce oil through compositional shifts, highlighting its promise for development as a safe functional food ingredient with possible biomedical applications. Full article

This study reports on the synthesis, structural characterization and gas sorption studies of a homometallic 2D Cd²⁺ MOF and two heterometallic 3D Cd²⁺/Ca²⁺ and Cd²⁺/Sr²⁺ -MOFs based on the angular tetracarboxylic ligand 3,3′,4,4′-sulfonyltetracarboxylic acid (H₄STBA). The homometallic 2D Cd²⁺ MOF with the formula [NH₂(CH₃)₂]⁺₂[Cd(STBA)]²⁻_n·nDMF·1.5nH₂O—(1)_n·nDMF·1.5nH₂O was synthesized from the reaction of CdCl₂·H₂O and 3,3′,4,4′-diphthalic sulfonyl dianhydride (3,3′,4,4′-DPSDA) with stoichiometric ratio of 1:1.3 in DMF/H₂O (5/2 mL) at 100 °C. The two heterometallic Cd²⁺/Ca²⁺ and Cd²⁺/Sr²⁺ compounds were prepared from analogous reactions to this afforded (1)_n·nDMF·1.5nH₂O with the difference that the reaction mixture also contained AE(NO₃)₂ (AE²⁺ = Ca²⁺ or Sr²⁺) and, in particular, from the reaction of AE(NO₃)₂, CdCl₂·H₂O and 3,3′,4,4′-DPSDA with stoichiometric ratio 1:1.1:1.4 in DMF/H₂O (5/2 mL) at 100 °C. Notably, compounds [CdCa(STBA)(H₂O)₂]_n·0.5nDMF—(2)_n·0.5nDMF and [CdSr(STBA)(H₂O)₂]_n·0.5nDMF—(3)_n·0.5nDMF are the first heterometallic compounds Mⁿ⁺/AE²⁺ (M = any metal ion) reported containing ligand H₄STBA. The structure of (1)_n·nDMF·1.5nH₂O comprises a 2D network based on helical 1D chain secondary building unit (SBU) [Cd²⁺(STBA)⁴⁻)]²⁻. The 2D sheets are linked through hydrogen bonding interactions, giving rise to a pseudo-3D structure. On the other hand, compounds (2)_n·1.5nH₂O and (3)_n·1.5nH₂O display 3D microporous structures consisting of a helical 1D chain SBU [Cd²⁺AE²⁺(STBA)⁴⁻)]. All three compounds contain rhombic channels along c axes. The three MOFs exhibit an appreciable thermal stability, up to 350–400 °C. Gas sorption measurements on activated materials (2)_n and (3)_n revealed moderate BET surface areas of 370 m²/g and 343 m²/g, respectively, along with CO₂ uptake capacity of 2.58 mmol/g at 273 K. Full article