Search Results (504)

Controlling radical selectivity within nanoreactors remains a formidable challenge due to the inherent high reactivity and short half-lives of reactive species. Herein, we report a novel size-matched nanoconfinement strategy using a cobalt-nickel-layered double hydroxide (CoNi-LDH) nanoreactor for the highly selective generation and stabilization of sulfate radicals (SO₄^∙−) via piezoelectric activation of peroxymonosulfate (PMS). By precisely tailoring the LDH interlayer spacing to 5.27 Å to match the kinetic diameter of SO₄^∙−, the nanoreactor effectively suppresses non-selective side reactions and radical quenching. Consequently, the CoNi-LDH achieves an unprecedented reaction rate (k_obs = 0.40 min⁻¹) and superior defluorination efficiency (78.9%) for fluoroquinolone antibiotics, significantly outperforming non-size-confined counterparts. Mechanistic insights reveal a synergistic pathway where piezo-generated hot electrons, mediated by Ni sites, accelerate the Co²⁺/Co³⁺ redox cycle to ensure long-term catalytic stability. The robustness of this nanoconfined system is further demonstrated by its exceptional tolerance to complex water matrices and its practical operability in a continuous-flow reactor. This study provides a pioneering approach for spatial radical control at the nanoscale to achieve efficient and targeted environmental remediation. Full article

Two mineral-based solid residues, namely coal gangue (CG) and phosphorus tailings (PT), two of the largest solid waste streams in the mining industry, were used as the sole metal feedstocks to fabricate a novel MgCaFeAl layered double hydroxide (LDH-GT) via a 700 °C calcination, acid leaching and hydrothermal coprecipitation route, with simultaneous synthesis of white carbon black from the reaction byproducts. Under optimized conditions (total metal load is 150 mg kg⁻¹, LDH-GT dose is 0.09 g, pH from 6 to 7), the synthesized material achieved concurrent immobilization efficiencies of 76.28%, 99.96%, and 99.95% for Cr (VI), Cd (II) and Ni (II), respectively, within a 24 h reaction period. TCLP leachability decreased by 82 to 91% relative to the untreated soil. After three wetting, drying and freeze–thaw cycles, the leached concentrations of all three metals remained below 0.3 mg L⁻¹, confirming excellent long-term stability. Mechanistic analyses revealed that Cr (VI) was mainly sequestered through interlayer anion exchange and surface complexation, whereas Cd (II) and Ni (II) were immobilized via isomorphic substitution into the LDH lattice, precipitation as carbonates, and incorporation into Fe/Mn oxides. A 7-day mung bean bioassay showed that LDH-GT amendment increased seed germination from 50% to 73%, enhanced root and shoot biomass by 1.1- to 1.6-fold, and decreased plant Cr, Cd, and Ni contents by over 80%. The 16S rRNA sequencing further demonstrated that LDH-GT reversed the decline in microbial α diversity induced by heavy metal stress, restored aerobic chemoheterotrophic and sulfur cycling functional guilds, and reduced pathogenic signatures. This study provides the demonstration of a waste-to-resource LDH that achieves efficient, durable remediation of multi-metal-contaminated soils, offering a scalable route for coupling solid waste valorization with in situ site restoration. Full article

The homogeneous nature of L-proline organocatalysts restricts their application in aldol condensation due to poor recyclability and stability. Herein, L-proline was heterogenized by ionic intercalation into Mg–Al layered double hydroxides (LDHs), yielding a series of proline-intercalated catalysts with tunable layer structures. Co-precipitation and memory-effect reconstruction strategies were employed to regulate interlayer spacing and proline loading. The resulting catalysts exhibited efficient performance in the aldol condensation of furfural with ketones under mild conditions. The reconstructed catalyst re-Mg₄Al₁P achieved a furfural conversion of 88.67% and a total product yield of 85.54% at room temperature, with product selectivity exceeding 95%. Structural characterizations confirmed that proline was stabilized within the LDH interlayers via R–COO—Mg electrostatic interaction while preserving the secondary amine active site. Mechanistic analysis indicated that the reaction proceeded through enamine- or enol-mediated pathways depending on water content, while the layered LDH framework imposed geometric confinement that suppressed side reactions. Catalyst deactivation in aqueous systems was mainly attributed to proline leaching rather than structural collapse. Full article

The rising demand for clean water has reinforced the importance of thin-film composite TFC polyamide membranes in desalination and wastewater treatment. While improvements often target the selective layer, these can sometimes reduce stability or selectivity. An alternative approach is to tailor the porous support, particularly through the incorporation of nanomaterials such as metal oxides, carbon-based nanomaterials, metal–organic frameworks (MOFs), zeolites, and cellulose-based materials, to improve overall membrane performance. The modification of membrane substrates through the incorporation of nanofillers has demonstrated notable advantages, including enhanced hydrophilicity, improved mechanical stability, and increased porosity. These improvements collectively contribute to higher permeability, reduced internal concentration polarization and enhanced separation performance in FO, NF, and RO applications. The review starts by clearly distinguishing substrate modification, in which nanomaterials are localized in the porous support, from interlayer modification, which involves constructing a distinct layer between the support and selective layer. This concise review highlights current developments in the nanomaterial-based support modification of polyamide TFC membranes; it summarizes nanomaterials selections, incorporation techniques, and resulting property changes. Current challenges and potential research opportunities are also discussed. Full article

The mechanical performance of Zr–Nb dual-phase alloys is strongly influenced by the metastable β (body-centered cubic, BCC) phase and its crystallographic orientation, yet the underlying deformation mechanisms remain unclear. In this work, molecular dynamics (MD) simulations were conducted to investigate the compressive behavior of nanolayered Zr–Nb alloys with varying loading directions and BCC layer thickness (T_BCC). The results reveal that interfacial coordinated strain governs the activation of various deformation modes. When the loading conditions promote strain compatibility at the interface between the hexagonal close-packed (HCP) and BCC phases, significant plasticity in the BCC phase assists the nucleation of stacking faults (SFs) and the activation of high critical resolved shear stress (CRSS) <c + a> slip systems in the HCP phase, leading to enhanced strength–ductility synergy of the material. In addition, T_BCC induces a non-monotonic peak stress response, with a transition thickness of ~10.96 nm. Below this threshold, stress-induced phase transformation in the BCC phase is the dominant mechanism for strengthening. Above this thickness, increased interlayer spacing enhances dislocation interactions and spatial effects, resulting in improved strain hardening and plastic stability. These findings clarify the competition between transformation-induced and dislocation-mediated strengthening and provide atomic-scale guidance for the microstructural design of high-performance Zr–Nb alloys. Full article

3D printing represents a promising fabrication technology for silica-based ceramic cores, which are essential components in the casting of turbine blades, but it is faced with poor high-temperature dimensional stability. Herein, alumina nanopowder was utilized as a modifier agent in digital light processing (DLP) 3D printing of silica-based ceramic cores, and systematic investigations were conducted on the microstructure and properties of ceramic cores throughout sintering and casting dependent on the content of alumina nanopowder (0–1.0 wt.%). Alumina nanopowder increased the sintering barrier of fused silica, significantly reducing the shrinkage in sintering and simulated casting, while improving high-temperature dimensional stability. Even though the alumina nanopowder led to decreased room-temperature and high-temperature flexural strengths attributed to inhibited densification and crystallization, the strengths met investment casting requirements after PVA solution strengthening. Excessive alumina nanopowder (0.8–1.0 wt.%) resulted in poor interlayer bonding and particle spalling, unfavorable to the structural integrity in casting. The optimal alumina content was 0.6 wt.%, which balanced sintering shrinkage of 1.86%, shrinkage of 4.41% after simulated casting, room-temperature flexural strength of 11.13 MPa, high-temperature flexural strength of 31.29 MPa, high-temperature creep deformation of 0.55 mm, and surface roughness of 1.815 μm. This research proposes an effective strategy for the optimization of 3D-printed silica-based ceramic cores in the manufacture of complex hollow turbine blades. Full article

Aluminum–lithium (Al-Li) alloys have attracted great interests in aerospace, solid propellants, and explosives industries. However, the practical use of Al-Li remains challenging because of instability during storage. Poor corrosion resistance and passivation of the Al-Li alloys are ascribed to the surface cracking of the oxidation layer. Using a variety of ab initio quantum chemistry methods, the cracking mechanisms of Al/Li/O oxides induced by H₂O, LiOH, and Li₂O have been revealed theoretically by means of Al₄O₆ and Al₈O₁₂ cluster models. All six reactions are shown to be highly exergonic dissociative adsorption processes. In terms of the Gibbs free energy profiles, the adsorption energy and reactivity are in the order Li₂O > LiOH > H₂O, which is independent of sizes of clusters. However, cluster size does have an impact on the adsorption energies of H₂O, LiOH, and Li₂O. For the reactions of H₂O, the energetic routes are dominated by proton transfer and followed by the O-Al bond cleavage to generate trench or protrusion structures. However, proton transfer is inhibited considerably by the O-Li interaction. As the Li atom migrates to form various Li-O coordinates along with the O-Al bond cleavage, the alumina clusters are cracked stepwisely through the interlayer O-Al bond association or displacement. The edge Al sites are always less reactive than the topmost surface Al. The Li atoms are prone to migrate from the edge to the surface as accompanied by the O-Al bond rearrangement. Present calculations provide a deep understanding of the oxidation behavior of the Al-Li alloys and present new insights towards increasing storage stability. Full article

As a representative digital additive construction material, three-dimensional printed concrete (3DPC) imposes a synergistic rheological requirement on fresh cementitious mixtures, namely “pumpability–extrudability–buildability,” throughout the forming process. Rheological parameters and their temporal evolution not only govern the stability of the material during pumping, nozzle extrusion, and layer-by-layer deposition, but also directly determine interlayer interfacial integrity, geometric fidelity, and the development of macroscopic mechanical performance. This paper provides a systematic review of the regulation strategies and evolutionary characteristics of 3DPC rheology, with particular emphasis on how raw material composition, printing parameters, and multiscale evolution mechanisms influence yield stress, plastic viscosity, and thixotropic behavior. The time-dependent evolution of rheological properties is elucidated across multiple length scales, encompassing microscopic particle interactions and hydration-induced bridging, mesoscopic aggregate force-chain networks and particle migration, and macroscopic shear stimulation coupled with temperature–humidity effects. On this basis, it is further highlighted that existing models and characterization frameworks remain insufficient to capture the time-dependent structural evolution under realistic printing conditions. Therefore, the establishment of unified characterization standards, together with in situ rheological measurements and multiscale simulations, is urgently required to enable the coordinated optimization of material design and printing processes and to facilitate engineering-scale implementation. Full article

The strength of Xigeda strata decreases significantly upon contact with water, and the shear strength between sandstone and mudstone layers is lower than that within the individual layers. Therefore, the interlayer dip angle plays an important role in determining the failure mode of rainfall-induced landslides. To investigate the effect of interlayer dip angle on the mechanical response of Xigeda sandstone–mudstone slopes under rainfall conditions, a total of five model slope tests were conducted. Different ratios of model materials were selected for the sandstone and mudstone, and artificial rainfall with intensities representative of the Panxi region was simulated using a calibrated rainfall device. A combination of photography and instrument measurements was employed to study the seepage field, deformation field, and slope failure characteristics at five interlayer dip angles. It is shown that when the interlayer dip angle is smaller than the slope angle, an increase in the interlayer dip angle accelerates the movement of the wetting front along the weak interlayer plane. At the same time, this increase shortens the time to the occurrence of abrupt displacement and increases the corresponding displacement magnitude, which makes slope failure prediction more challenging. The shoulders of all slopes experienced displacement earliest and exhibited the largest displacement amplitude. The slope failure mode transitioned from shallow surface sliding to interlayer sliding. When the interlayer dip angle surpassed the slope angle, the weak interlayer plane was no longer the dominant control surface. Slope stability was thereby moderately enhanced, with the failure mode shifting to through-layer sliding. Full article

To investigate the interlayer contact mechanism of foamed cold-recycled asphalt mixture under static loads, a three-layer asphalt pavement discrete element model (DEM) was established, with the surface layer composed of asphalt concrete-13 (AC-13), asphalt concrete-20 (AC-20) and asphalt-treated base-25 (ATB-25) foamed cold-recycled asphalt mixture and cement-stabilized macadam as the base. Based on mortar theory, the pavement was divided into coarse aggregate, asphalt mastic and air void phases, and the Burgers Model, Linear Parallel Bond Model and Linear Model were adopted to characterize the bonding of asphalt-aggregate, cement contact interface and subgrade-surface layer, respectively. Static loads of 0.7 MPa, 1.1 MPa, 1.5 MPa and 1.9 MPa were applied to analyze the mechanical responses of asphalt-based and cement-based pavement systems from tensile strain, vertical compressive stress and vertical displacement. Results showed that mechanical indices of the pavement increase monotonically with static load and present obvious layered distribution. The cement-stabilized macadam base provides rigid support, significantly reducing tensile strain (TS) and vertical displacement (VD) of asphalt layers, while the asphalt-based system has flexible stress transfer and superior stress dissipation in the bottom layer. The two systems exhibit respective structural advantages, with the cement-based system outstanding in deformation control and the asphalt-based system suitable for flexible stress adaptation working conditions. Full article

Three-dimensional printing (3DP) has gained increasing attention in construction as a means of addressing labor shortages and improving efficiency. Various studies have investigated fiber-reinforced mortars for 3DP. However, only a few studies have examined mixture design strategies aimed at controlling early structural build-up, and the relationships between early structural build-up, printability, and interlayer stability remain largely unexplored. This study aimed to establish a practical method for evaluating the static yield stress and early buildability of 3DP mortars under construction-site conditions. Vane shear and 15-stroke flow tests were conducted to assess the static and dynamic behavior of mortars incorporating polyvinyl alcohol (PVA) fibers, and their compressive and flexural strengths were also evaluated. According to the results, the vane shear test sensitively captured the rheological changes associated with variations in fiber content and superplasticizer dosage. The addition of PVA fibers increased the maximum shear stress of the mortar, resulting in atypical static yield stress development compared to fiber-free mortars. While the 15-stroke flow test further elucidated flowability, the vane shear test revealed a stronger correlation between mechanical properties and overall buildability. Thus, vane shear testing can be reliably used to assess early-age structural build-up and interlayer stability in 3DP mortars for optimizing print performance. Full article

MXenes are high-performance pseudocapacitive materials known for their excellent conductivity, large surface area and fast redox reactions occurring at the surface. Despite these advantages, their practical application is hindered by the tendency of MXene nanosheets to aggregate and restack, which significantly compromises cycling stability. In this work, post-delamination metal-ion intercalation was employed to successfully expand the interlayer spacing of Ti₃C₂ while simultaneously optimizing its surface functional groups. Benefiting from the enlarged interlayer spacing and improved surface chemistry, the Mn-intercalated MXene (Mn–MXene) delivers a high specific capacitance of 285 F g⁻¹ at a scan rate of 10 mV s⁻¹ in 1 M H₂SO₄ electrolyte, which represents a 26% enhancement compared with pristine Ti₃C₂. Notably, Mn–MXene exhibits nearly 100% capacitance retention after 3000 cycles. Full article

Photocatalytic processes have been studied as promising solutions to mitigate the impact of pollutants on aquatic environments. Here, the enhancement of photocatalytic performance and stability of titanate nanostructures (TNS), a well-established photocatalyst, were investigated through Sr modification. Structural characterization confirmed Sr in-corporation in the crystalline structure, mainly in the interlayers. The sample Sr(5%)TNS, synthesized with 5% (wt.), exhibited fine lamellar morphology, different from the elongated nanowires of pristine TNS. The photocatalytic performance of the Sr-modified sample was studied for the removal of a model pollutant, caffeine, under UV-Vis and visible irradiation. A clear enhancement in the caffeine removal rate was observed using Sr(5%)TNS as a photocatalyst, when compared with the pristine material. Further improvement in the photocatalytic performance was obtained by combining Sr(5%)TNS with graphitic-like carbon nitride (g-C₃N₄) as a novel composite film. This proved to be a promising strategy for enhancing both the visible-light photocatalytic efficiency and the stability of the films, while also facilitating their reuse. Various configurations of the hybrid system were tested, and the best results for caffeine degradation and catalyst robustness were achieved with a 4:1 ratio of Sr(5%)TNS to g-C₃N₄. Mechanisms for charge transfer in irradiated Sr(5%)TNS particles, and in Sr(5%)TNS/g-C₃N₄ composite films are proposed and discussed. Full article

This study investigates the wear behavior and multi-technique characterization of 3D printed thermoplastic polyurethane (TPU) intended for friction layers in transmission belts used in pharmaceutical manipulators. Two flexible TPU grades—TPU 51A and TPU 60A—were printed using fused deposition modeling (FDM) with varying printing temperatures (255–265 °C for 51A; 225–235 °C for 60A) and layer counts (three or four layers). Specimens were evaluated for Shore A hardness, wear resistance (mass loss using a Baroid lubricity tester under dry sliding against carton), tensile properties, crystallinity (XRD), chemical structure (FTIR), thermal stability (TGA), and scanning electron microscopy (SEM). The results show that printing parameters significantly influence the mechanical and tribological behavior of the materials. For TPU 51A, increasing the printing temperature to 265 °C and using four layers led to a substantial reduction in cumulative mass loss, although hardness decreased. In contrast, for TPU 60A, higher printing temperature and layer count increased hardness but also resulted in higher wear. Tensile tests indicated that specimens printed with fewer layers exhibited higher yield strength and strain, indicating improved interlayer bonding. XRD analysis confirmed the predominantly amorphous nature of the printed samples, with a reduction in crystallinity compared to the raw filaments. FTIR spectra showed no significant chemical degradation during printing, while thermogravimetric analysis revealed good thermal stability up to approximately 250–260 °C. The results demonstrate that wear behavior is governed by a combination of hardness, interlayer cohesion, and microstructural organization rather than crystallinity alone. Among the investigated conditions, TPU 51A printed at 265 °C with four layers exhibited the most favorable balance between wear resistance and mechanical properties, highlighting its suitability for friction layer applications. Full article

Landslides occurring on reservoir banks in steep, high-gradient canyon areas pose a significant risk of surge disasters when they slide into the water. This can endanger the lives and property of downstream residents and damage coastal infrastructure. Therefore, researching the formation mechanisms, disaster evolution, and risk assessment of the landslide-surge disaster chain in such areas is essential. This paper takes the Laowuchang landslide in the Shuibuya Reservoir area of the Qingjiang River, China, as its research object. Using GeoStudio 2018 software, it evaluates the landslide’s stability under varying reservoir water levels and rainfall conditions. For potential unstable scenarios identified, a full-chain numerical simulation of the landslide–tsunami disaster was conducted based on the Tsunami Squares method, with a focus on analyzing the wave characteristics during generation, propagation, and run-up processes. Furthermore, the paper assesses the risk of landslide–tsunami disasters in the Laowuchang landslide area. The research findings indicate that: (1) Under the long-term continuous river incision, limestone of the Triassic Daye Formation slides along weak interlayers, inducing large-scale collapses. Subsequently, part of the landslide mass is transported by water, while most accumulates in the near-shore area of the Qingjiang River, ultimately shaping the present morphology of the landslide. (2) The Laowuchang landslide is stable under static water levels of 375 m and 400 m, with corresponding safety factors of 1.137 and 1.167, respectively. Under combined static water level and heavy rainfall conditions, the slope stability decreases significantly, with safety factors of 1.034 and 1.064, respectively. Under reservoir drawdown conditions, the slope tends to be unstable, with a safety factor of 1.047. (3) Numerical simulation results indicate that if the Laowuchang landslide fails into water by the speed of 12 m/s and with a volume of 2 million m³, the maximum initial wave height can reach 15.9 m. The tsunami’s affected range spans 10 km upstream and downstream from the landslide mass, with four houses and one substation within a 2 km up and downstream falling into high-risk areas. If abnormal increases in landslide displacement occur, relocation and risk avoidance measures should be implemented. The findings of this study provide a scientific basis for the prevention and response to landslide–tsunami disasters in similar high and steep canyon terrains. Full article