Search Results (452)

A fly ash-based artificial aggregate with a compressive strength of >60 MPa was prepared via cement activation and alkali activation using >75% fly ash as the principal raw material. The mechanical properties of concrete prepared using this aggregate and the characteristics of the interfacial transition zone (ITZ) were compared with those of concrete containing natural aggregate. The results indicated that the compressive strength of concrete prepared using artificial aggregate was lower than that of concrete prepared using natural aggregate by about 19.0–27.6%. Scanning electron microscopy (SEM) revealed that the cement paste bonded tightly to the surface of the natural aggregate; the width of ITZ was 20–30 µm. The ITZ between the cement paste and the fly ash-based artificial aggregate exhibited a relatively loose structure at 28 d, with a width of 30–40 µm; however, the ITZ became narrower and denser at 90 d. EDS indicated that the principal hydration products were calcite crystals and C-S-H gel in the ITZ of natural aggregate concrete and artificial aggregate concrete. According to nanoindentation tests, for both cement pastes with natural and artificial aggregates, the elastic modulus of the ITZ at 28 d was >10 GPa, and it increased slightly at 90 d. The ITZ between the alkali-activated paste and limestone exhibited a relatively dense structure, with a width of 20–30 µm. The ITZ between the alkali-activated paste and the fly ash-based artificial aggregate exhibited a relatively loose structure with numerous pores at 28 d and had a width of 30–40 µm; however, the ITZ became narrower and denser at 90 d. The principal hydration products were N-A-S-H and C-A-S-H in the two kinds of aggregate concrete. Whether the alkali-activated paste contained natural aggregate or artificial aggregate, the elastic modulus of the ITZ at 28 d was 5–6 GPa, and it increased rapidly to >10 GPa by 90 d. The performance of ITZ is primarily influenced by the matrix materials, while also being influenced by aggregates and curing conditions. Qualitative and quantitative analyses revealed the formation mechanisms of artificial and natural aggregates in different matrices. Through continuous hydration and polymerization reactions, artificial aggregates gradually form narrower and denser interfacial transition zones with different matrices, especially in alkali-activated matrices. The continuously improved performance of the ITZ makes it less prone to forming cracks between the ITZ and the artificial aggregate. This study provides an important theoretical basis for the application of fly ash-based artificial aggregates, which can also be used to produce high-strength concrete. Full article

To support the achievement of the carbon peaking and carbon neutrality goals and promote the resource utilization of industrial solid waste, a ternary solid waste composite cementitious material was prepared by blending ground granulated blast-furnace slag (GGBFS), fly ash (FA), and carbide slag (CS) with cement. The optimal mix ratio was determined through single-factor experiments and response surface methodology. The synergistic hydration mechanism was elucidated using microstructural characterization techniques, including XRD, FTIR, TG-DTG, and SEM. The composite material was then applied to a semirigid base course, and its mechanical properties and durability were systematically evaluated. The results indicate that the optimal levels of FA, GGBFS, and CS investigated in the single-factor experiments are 20–40%, 30–50%, and 2–6%, respectively. The optimal mix ratio of the ternary solid waste composite is 21.0% FA, 36.3% GGBFS, and 5.7% CS. The underlying microstructural mechanism is that carbide slag creates a highly alkaline environment, which activates the pozzolanic activity of GGBFS and fly ash, leading to the formation of hydration products dominated by C-(A)-S-H gel. With increasing curing age, the gel structure evolves from a loose and disordered state to a dense and ordered state, ultimately forming a compact microstructure based on a highly polymerized C-(A)-S-H gel matrix. The 7-day unconfined compressive strength of the stabilized gravel using the solid waste-based composite cementitious material reached 5.93 MPa, and the 28-day drying shrinkage coefficient was reduced by 18.3% compared with that of cement-stabilized gravel. After 18 freeze–thaw cycles, the compressive strength increased by 2.4%, with the pore structure characterized by a “macropores decreasing, micropores increasing” refinement pattern. After 18 wetting–drying cycles, the cumulative strength loss was 11.26%, outperforming cement-stabilized gravel. Combined with SEM observations, these performance improvements are attributed to the densely intertwined hydration products, particularly C-S-H gel, which effectively fill the voids between aggregate particles and significantly enhance the volume stability, freeze–thaw resistance, and wetting–drying durability of the stabilized gravel. The application of this cementitious material in a semirigid base course demonstrates excellent mechanical and durability properties, providing a theoretical basis and technical support for the widespread application of industrial solid waste in road engineering. Full article

To address the issues of temperature rise accumulation, structural vibration, and air gap degradation that occur during the long-term operation of Anode Saturable Reactors used in high-voltage direct-current (HVDC) converter valves, electromagnetic-structural and electromagnetic-thermal multi-physics coupling analysis models were established using COMSOL Multiphysics software. The monitorable quantities capable of characterizing defects in Anode Saturable Reactors were systematically investigated from three aspects: vibration signals, thermal signals, and electrical signals. First, a one-way electromagnetic-structural coupling vibration model was established to analyze the vibration characteristics under normal operation, loose core conditions, and polyurethane hardening conditions. Second, an electromagnetic-thermal coupling model was established to compare the core loss and temperature rise distribution between the defect-free condition and the condition with reduced air gap defects. Finally, the effects of air gap reduction on electrical parameters such as unsaturated inductance and frequency sweep impedance were analyzed. The results indicate that the dual-peak characteristics and residual vibration of vibration signals can reflect the looseness of the iron core, while thermal aging of the polyurethane filling material further weakens the system’s damping capacity, intensifying vibration impact on the core and structural components. A reduction in air gap leads to an increase in local core loss of approximately 47.9%, giving rise to local hot spots. For the shell-type ASR investigated in this study, the temperature rise of the reactor casing remains almost unchanged. The unsaturated inductance and the impedance value near 10 kHz are highly sensitive to air gap variations and can serve as effective feature quantities for online monitoring. Full article

Gas-assisted steam explosion (GASE) disrupts raw material structures and promotes active release, but its effects on the nutritional quality and flavor of edible fungi remain unclear. Therefore, this study assessed the influence of GASE on the nutritional quality and flavor characteristics of Pleurotus eryngii. Using the sample as the raw material, we selected the GASE process parameters through single-factor experiments combined with response surface methodology and confirmation experiments. Subsequently, changes in nutrient contents and volatile/non-volatile flavor profiles were quantitatively characterized under these processing conditions. The results indicated that the selected parameters effectively disrupted the cell wall structure of the sample, resulting in a loose and porous microstructure. Consequently, the levels of protein, polysaccharides, amino acids and vitamins were significantly altered. In terms of flavor, this process modified the relative odor activity values of key aroma compounds, including volatile aldehydes and pyrazines, while also affecting the distribution of non-volatile metabolites. This led to the enrichment of flavor compounds such as nucleotides and their derivatives, and organic acids. This study confirmed that GASE technology can effectively enhance the nutritional quality and flavor characteristics of the mushroom by regulating its microstructure and metabolite composition. Full article

This study reports the physicochemical characterization and structure–property relationships of rigid sheep wool/phenolic novolac panels developed as bio-based thermal insulation for building envelopes. Mixed Polish sheep wool was washed, mechanically opened, and formed into nonwoven mats, then impregnated with either neat or flame-retardant novolac resin to obtain lightweight boards with a fiber content of about 50 wt%. Elemental analysis, ICP-OES, FTIR spectroscopy, and laser and electron microscopy were used to evaluate the fiber composition, keratin structure, morphology, and fiber–matrix interfaces. Mechanical performance under three-point bending and shear, differential scanning calorimetry, thermogravimetric analysis, and transient hot-probe thermal-conductivity measurements were applied to link microstructure with functional behavior. Novolac impregnation transformed the compliant wool mat into self-supporting panels, increasing the flexural modulus to the 0.8–1.4 GPa range and flexural strength to approximately 48–52 MPa, while the shear modulus and work to failure rose by more than an order of magnitude relative to the loose wool reference. Thermal conductivity remained in a typical range for natural-fiber insulations (λ = 0.061 W·m⁻¹·K⁻¹ for the wool mat and 0.071–0.074 W·m⁻¹·K⁻¹ for the composites), although higher than that of expanded polystyrene. DSC and TGA confirmed that wool fibers remain thermally stable up to about 200–220 °C, that the novolac resin cures around 140 °C, with typical phenolic reaction enthalpies, and that both formulations generate high char residues of roughly 60–80 wt% at 600 °C under nitrogen, evidencing a strong charring propensity rather than directly quantifying fire resistance. Overall, the results position sheep wool/novolac panels between conventional bio-based insulation and structural composites and highlight their potential as sustainable, circular insulation materials for energy-efficient building envelopes. Full article

Tailings storage facility (TSF) failures have caused severe casualties and economic losses. This study used Enhanced Small Baseline Subset InSAR (E-SBAS-InSAR) and 88 Sentinel-1A images to retrieve the 2022–2024 surface deformation time series of the Shiguilong TSF, located in the Fe–Cu polymetallic metallogenic belt of the middle–lower Yangtze River. The reliability of the results was assessed through consistency comparisons with Small Baseline Subset InSAR (SBAS-InSAR) and Persistent Scatterer InSAR (PS-InSAR). A time-series decomposition model was applied to extract seasonal deformation components and analyze their lagged responses to temperature and intense rainfall events. The results show that: (1) E-SBAS-InSAR achieved a monitoring-point density nearly 7 times higher than SBAS-InSAR, enabling dense and long-term deformation characterization; (2) subsidence at Shiguilong continued to increase, with cumulative subsidence reaching −76.8 mm and a maximum annual mean subsidence rate of −22.78 mm/yr; (3) deformation was mainly controlled by long-term consolidation of loose tailings and creep of dam–tailings materials, while seasonal factors induced stage-dependent fluctuations; (4) seasonal deformation showed lagged responses of 6 days to temperature variations and 2 days to intense rainfall events, with rainfall exerting a more pronounced influence. This work is significant for TSFs monitoring under complex surface conditions. Full article

To investigate the deterioration of compressive property of traditional concrete in a high-temperature environment, uniaxial compression tests were conducted on concrete at various high temperatures. Combined analytical techniques—scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric-mass spectrometry (TG-MS)—were used to analyze the degradation mechanism. The experimental results indicate that high temperature has a strong temperature-dependent effect on concrete’s compressive strength. As temperature increases (400 °C, 600 °C, 800 °C), concrete’s compressive strength decreases. These decreases are 27.52%, 56.6%, and 80.76% relative to room temperature, respectively. This phenomenon is attributed to the direct link between concrete’s microstructure and its macroscopic mechanical properties—driven by thermal stresses generated during heating and the decomposition of cement hydration products. Temperatures above 400 °C trigger microcrack formation, and microcracks propagate more rapidly with increasing temperature. At temperatures further increasing to 600 °C, fewer cementitious materials are left decomposable; even stable calcium carbonate starts to decompose. At temperatures of 800 °C or more, decarburization occurs, rendering the concrete microstructure loose and porous. Partial separation of aggregates from the paste causes a near-total loss of compressive strength. Full article

Iris sanguinea features upright, stiff leaves, making it an excellent cut-foliage material, with its tall leaf architecture greatly enhancing ornamental value in landscaping. However, during the leaf expansion phase, plants frequently exhibit loose foliage arrangement, excessive spreading, and compromised mechanical strength, culminating in lodging and a concomitant decline in ornamental quality. Plant height in I. sanguinea is strongly regulated by phytohormones. This study showed that exogenous GA at concentrations of 50 mg·L⁻¹, 100 mg·L⁻¹, and 200 mg·L⁻¹ increased seedling height by 5.7%, 8.8%, and 12.7%, respectively, through foliar spraying on I. sanguinea seedlings grown ex vitro in a greenhouse; conversely, PAC treatment at equivalent concentrations suppressed growth by 19.3%, 21.0%, and 22.2%, respectively. Two pivotal GA signaling components, GAI and GID1a, were isolated from I. sanguinea. Subcellular localization confirmed that both IsGAI and IsGID1a proteins localize to the nucleus. Overexpression vectors pCAMBIA1300-IsGAI-GFP and pCAMBIA1300-IsGID1a-GFP were constructed and expressed in Arabidopsis thaliana. Transgenic lines overexpressing IsGAI showed significantly reduced plant height, hypocotyl elongation, and bolting, whereas IsGID1a overexpression promoted these traits. Exogenous GA application partially reversed the dwarf phenotype induced by IsGAI overexpression and further potentiated the height enhancement observed in IsGID1a-overexpressing lines. This study identifies two key genes controlling plant height and provides a theoretical basis and genetic resources for precisely engineering plant architecture in I. sanguinea. This is especially important for developing dwarf varieties with enhanced ornamental and agronomic traits, offering significant potential in the landscaping and cut flower industries. Full article

Arundo donax L. is a significant energy crop and perennial grass, with its efficient conversion holding substantial implications for the utilization of agricultural biomass resources. However, the distinct effects of acid and alkali pretreatments on its lignocellulose degradation patterns and structural modifications remain inadequately characterized. This study utilized Arundo donax L. as raw material to compare the effects of dilute sulfuric acid and sodium hydroxide pretreatments on its component degradation and structural modifications. Single-factor experiments were conducted, and the mechanisms were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. The results indicated that dilute sulfuric acid pretreatment primarily degraded hemicellulose (up to 85.8%) with limited lignin removal (<13%), whereas sodium hydroxide pretreatment effectively removed lignin (66.8%). XRD analysis revealed that crystallinity after dilute acid treatment was significantly higher than that of untreated samples (p < 0.05). Sodium hydroxide treatment induced a concentration-dependent non-monotonic change in crystallinity: the crystallinity index (CrI) peaked at a 1% concentration, was significantly lower at 3% and 4%, and showed intermediate values at 2% and 5%. The apparent crystallite size remained at 3.0–3.3 nm, suggesting that both pretreatments primarily targeted amorphous regions. FTIR analysis confirmed that alkali treatment more thoroughly disrupted ester bonds and lignin. SEM images revealed that alkali-treated fiber bundles were more loosely packed with relatively smoother surfaces. In acid treatment, 100 °C was identified as the critical temperature for a significant increase in crystallinity, whereas in alkali treatment, temperature had no significant effect on crystallinity. Full article

The problem of industrial waste disposal is becoming increasingly pressing. For a long time, one of the primary methods of managing hazardous industrial waste was to dispose of it for long periods (decades) in engineered landfills. However, over time, due to various climatic, geological, and other changes, landfills begin to cause significant harm to the environment and human health. Old landfills, many built in the mid-20th century, pollute the air, soil, and groundwater. Therefore, the issue of decommissioning “old” landfills is becoming increasingly pressing. This study aimed to develop technological solutions for the safe extraction and processing of hazardous liquid waste from an aged industrial landfill. An integrated treatment chain was designed, comprising extraction, multi-barrier water treatment, vacuum evaporation, and lithification. Optimal lithification compositions were identified: for the salt concentrate–sludge–spent media mixture, a ratio of 68.2% sorbent D, 28.0% salt concentrate, and 3.8% dewatered sludge/spent media yielded a loose granular geocomposite; for oil-containing waste, the optimal ratio using lime and opoka was 1:0.9:0.5 (bottom sediments/CaO/opoka). Biotesting confirmed that the lithified waste is Hazard Class V (non-hazardous), whereas the untreated waste is Class III (moderately hazardous). The resulting geocomposite is suitable for on-site technical reclamation, closing the material cycle. Full article

Focusing on the R&D demand for green earthen building materials in coastal high-temperature and high-humidity areas, this study explores the biocolonization control mechanism of raw earth–rubble walls, taking the traditional raw earth–rubble walls of ancient buildings in Sanfang Qixiang, Fuzhou, as the research subject. FTIR, XRD, Raman, and SEM-EDS combined technologies were employed for characterization. The results show that the raw earth is rich in proteins, amino acids, and other nutrients, which provide the nutritional basis for plant growth. The raw earth and rubble share homologous mineral components. The rubble is fired from raw earth mixed with iron minerals such as hematite, with carbonaceous substances generated during the firing process. Iron, carbon, and potassium released from the weathered rubble may inhibit the growth of plant roots. The raw earth is relatively looser than the rubble, and the two form a dense–loose alternating structure. Combined with the secondary calcification mechanism in the raw earth, this structure resists the expansion and cracking of the wall and improves the viscosity and hardness of the wall. It is concluded that in a high-temperature and high-humidity environment, the raw earth first releases nutrients to promote plant growth. As time progresses, the relevant substances released by the rubble continuously inhibit root growth. Combined with the structural characteristics of the wall with high firmness and crack resistance, plants growing on the wall will not damage the wall structure. This finding provides a theoretical basis for the biocolonization control mechanism of raw earth–rubble walls and also offers practical references for the protection and sustainable reuse of raw earth buildings in similar areas. Full article

In energy conversion semiconductor devices, radiation damage is directly related to the long-term stability of β-voltaic batteries. In this study, single-crystalline silicon P⁺NN⁺ devices and P⁺-silicon materials with SiO₂ surface passivation were irradiated using a ~70 keV accelerator electron beam in a nitrogen atmosphere for 2 min, 10 min, 1 h, 6 h, and 12 h. The tritium-voltaic output decreased rapidly within the first 2 min of electron beam irradiation and then decayed slowly. After 1 h of irradiation, both the output short-circuit current (Isc) and open-circuit voltage (Voc) remained stable. The effects of the damage were analyzed using typical samples irradiated for 1 h. Neutron reflectometry (NR) was employed as the primary characterization method, while X-ray photoelectron spectroscopy (XPS)—combined with Ar⁺ etching—and secondary ion mass spectrometry (SIMS) were used to verify radiation-induced structural changes at the SiO₂ surface and SiO₂/Si interface. It was found that nitrogen atoms from the atmosphere penetrated the SiO₂ layer to a depth of approximately 5–10 nm, forming a non-stoichiometric SiON structure, without further diffusion into deeper layers. Irradiation significantly increased the thickness of the SiO₂/Si interface transition layer to about 14–18.5 nm, and the SiO₂ structure within this layer became relatively loose. It can be inferred that tritium-voltaic batteries using SiO₂-surface-passivated single-crystalline silicon P⁺NN⁺ devices as energy-conversion units and packaged in a nitrogen atmosphere can stably provide power for 10 years, with an Isc reduction of no more than 12% and a Voc reduction of no more than 6%, excluding the spontaneous decay of tritium. Full article

Biomass represents a vital and sustainable resource for developing renewable materials with the potential to replace petroleum-based chemicals. Paulownia wood has high cellulose content and a loose wood structure, giving it natural advantages as a biomass material. Therefore, in this study, Paulownia wood was selected as a lignocellulosic feedstock. An integrated pretreatment process combining a deep eutectic solvent (DES) with an organic solvent was employed to efficiently remove lignin and hemicellulose, yielding cellulose-enriched residues. Subsequently, high-intensity ultrasonication was applied to convert the residues into cellulose nanofibers and nanocrystals. Using the extracted cellulose and nanocellulose, a dual-crosslinked network composite hydrogel was fabricated. The structural, mechanical, thermal, swelling, and conductive properties of the hydrogel were systematically investigated. The results show that, compared with the blank group hydrogel, the addition of nanocellulose increased the maximum tensile strength and tensile strain of the composite hydrogel by approximately 113% and 81%, respectively; meanwhile, the compressive strengths of the nanocellulose-based hydrogels (0.04575–0.09060 MPa) are higher than that of the blank group hydrogel (0.04235 MPa), confirming that the incorporation of nanocellulose significantly enhances the mechanical strength and elasticity of the hydrogel. The introduction of an AlCl₃/ZnCl₂ solvent system imparts appreciable electrical conductivity. Furthermore, the composite hydrogel maintains structural integrity after full swelling, indicating good dimensional stability and reusability. This work not only presents a green and efficient strategy for valorizing Paulownia biomass but also offers a novel design route for high-performance conductive hydrogel materials, highlighting their potential application in areas such as flexible electronics and energy storage. Full article

The sustainable utilization of multiple reclaimed pavement materials is a critical pathway toward green highway construction. This study investigates the performance and synergistic mechanisms of cold-recycled mixtures incorporating both Reclaimed Asphalt Pavement (RAP) and Reclaimed Cement-Stabilized Base (RCSB), using emulsified asphalt as the primary binder. A comprehensive experimental program was conducted to evaluate the effects of reclaimed material proportions, mixing sequences, and curing ages on the mechanical strength, moisture susceptibility, and high-temperature stability of the mixtures. Microscopic characterization via Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS) were employed to elucidate the Interfacial Transition Zone (ITZ) evolution. Results indicate that an optimal RCSB incorporation range of 20–40% establishes a robust “stone-to-stone” rigid skeleton, significantly enhancing the splitting strength (up to 0.87 MPa) and durability (Splitting Strength Ratio, TSR > 91%). SEM observations confirm the formation of a dense interpenetrating network structure within this range, where cement hydration products and asphalt films achieve optimal chemo-physical bonding. Exceeding 40% RCSB leads to a moisture-starved state and a sharp decline in dynamic stability due to insufficient binder coating. Micro-morphological characterization reveals that the transition from macro-interfacial debonding to a robust cohesive failure mode is the fundamental driver for the performance peak at 20–40% RCSB. SEM observations confirm the formation of a dense interpenetrating network structure, where cement hydration products successfully anchor into the asphalt film. This optimized ITZ effectively eliminates the stress concentration and aggregate crushing seen in high-RAP mixtures, thereby ensuring superior mechanical integrity. Furthermore, a pre-wetting mixing sequence ensures a high-energy mineral surface that promotes the heterogeneous nucleation of cement. SEM results show that this prevents the competitive adsorption between cement and asphalt, transforming the ITZ from a friable, loose state into a densified crystalline adhesive matrix. Full article

The widespread presence of ciprofloxacin (CIP) in aquatic environments threatens ecological and public health, yet conventional treatment processes fail to remove such persistent contaminants. Conventional solvothermal synthesis of Bi-doped g-C₃N₄ photocatalysts involves complicated procedures and low productivity. Herein, we employ a single-step, template-free and solvent-free green calcination method to construct Bi³⁺-modified g-C₃N₄ with strong Bi-N coordination interactions. A series of Bi/g-C₃N₄ photocatalysts with Bi-doping mass ratios of 0.09–0.34 wt% was prepared, and the structure–performance relationship as well as the surface–interface reaction mechanism for ciprofloxacin (CIP) degradation were systematically elucidated. Experimental results confirm that Bi³⁺ incorporates into the lattice via Bi-N coordination bonds with nitrogen in the g-C₃N₄ framework, which narrows the band gap, suppresses photogenerated carrier recombination, and constructs a loose porous morphology beneficial for increasing specific surface area and active sites. Under optimal conditions, 15Bi/g-C₃N₄ achieves 97.6% degradation of 15 mg L⁻¹ CIP within 90 min, which is 13.7% higher than that of pristine g-C₃N₄. The effects of catalyst dosage, initial pH, CIP concentration, common coexisting ions, and different real water matrices on the degradation performance were systematically investigated. Radical quenching experiments combined with ESR characterization confirm that h⁺ is the dominant reactive species responsible for CIP degradation. This green, simple and scalable method yields uniform products, and the resulting materials exhibit high efficiency, economic feasibility and environmental safety, demonstrating promising potential for antibiotic wastewater treatment. Full article