Search Results (814)

Building facades and construction materials are continuously exposed to airborne particulate matter, organic pollutants, and microbial colonization, which cause progressive soiling, aesthetic degradation, and structural deterioration while imposing high maintenance and energy burdens. Photocatalytic titanium dioxide (TiO₂) has emerged as the most widely studied material for imparting self-cleaning functionality to building surfaces, owing to its ability to mineralize adsorbed contaminants under solar irradiation and to modulate surface wettability. This narrative review provides a structured account of TiO₂-based self-cleaning coatings for building materials, organized around three complementary themes: surface mechanisms, performance metrics, and outdoor durability. We first rationalize the two intertwined self-cleaning mechanisms—photocatalytic oxidative degradation and photoinduced superhydrophilicity—and their combination with physically repellent (superhydrophobic/superamphiphobic) wetting states. We then survey the principal coating-design strategies, including morphology and facet engineering, SiO₂-TiO₂ composites, metal/non-metal doping and heterojunction construction for visible-light activation, and dual-functional photocatalytic–superhydrophobic systems, and their integration into cementitious substrates, natural stone and cultural heritage, and transparent glass/photovoltaic surfaces. The quantitative metrics used to benchmark self-cleaning performance—water contact angle, dye photodegradation, NO_x and VOC abatement, and antimicrobial activity—are critically discussed together with the limitations of standardized laboratory tests. Finally, we analyze the weathering-induced deactivation pathways (photocatalyst leaching, surface contamination by soluble salts, and UV aging of organic matrices) and the emerging strategies for durable coatings, including inorganic binders, light-driven hydration, and defect- and heterojunction-engineered photocatalysts. The review concludes with an outlook on the open challenges that must be addressed to translate these coatings from laboratory demonstrations to long-lived, large-scale building applications. Full article

Nickel coatings were deposited onto the surfaces of red mud, Al₂O₃, and Fe₂O₃ particles via an electroless plating technique. The nickel-coated particles (1.5 wt.%) were subsequently incorporated into a ZL109 aluminum alloy matrix to fabricate three types of composites using a stir-casting process, followed by a T6 heat treatment consisting of solution treatment at 515 °C for 8 h, water-bath quenching at 90–100 °C, and artificial aging at 175 °C for 12 h. The microstructural morphology and phase identification were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Furthermore, the high-temperature tensile properties of the fabricated alloys were evaluated at 350 °C and 400 °C. The results showed that the addition of 1.5 wt.% nickel-coated red mud led to a more uniform distribution of eutectic silicon and an increase in the content of the Al₅Cu₂Mg₈Si₆, Al₇Cu₄Ni, and Al₂Cu strengthening phases. These microstructural changes significantly enhanced the high-temperature tensile performance of the alloy. At 350 °C and 400 °C, the alloy reinforced with 1.5 wt.% nickel-coated red mud achieved tensile strengths of 97.8 MPa and 86.2 MPa, respectively. The combination of an appropriate amount of nickel-coated red mud and a suitable heat treatment process effectively improves the high-temperature stability and tensile properties of the ZL109 aluminum alloy, which could be attributed to the synergistic strengthening effect arising from the precipitation of high-temperature stable phases and the Orowan mechanism. Full article

Late Mesozoic magmatic rocks are widely exposed in the northern Great Xing’an Range, a key region recording Phanerozoic crustal growth along the eastern Central Asian Orogenic Belt (CAOB). This study integrates petrology, LA–ICP–MS zircon U–Pb geochronology, zircon Hf isotopes, and whole-rock geochemistry for Late Mesozoic granitic subvolcanic intrusions in the Huoluotai area, northern Great Xing’an Range. Zircon U–Pb dating yields crystallization ages of 143.4 ± 1.2 Ma for the felsite and 138.8 ± 2.0 Ma for the rhyolite porphyry, documenting early Early Cretaceous emplacement. Geochemical data reveals that the investigated felsite and rhyolite porphyry exhibit high SiO₂, K₂O and total alkali (K₂O + Na₂O) contents, coupled with low MgO, Mg^#, Ni, Sr and Yb values, and thus belong to shoshonitic I-type granites. The samples are enriched in large-ion lithophile elements (LILIs; e.g., Rb, K, U) and light rare earth elements (LREEs), with depletion of high-field-strength elements (HFSEs; e.g., Nb, Ta, P, Ti) and heavy rare earth elements (HREEs), accompanied by pronounced negative Eu anomalies, typical of crust-derived magmas. Zircon ε_Hf(t) values range from −2.25 to +1.57 for the felsite (T_DM2 = 1092–1334 Ma) and −0.65 to +3.58 for the rhyolite porphyry (T_DM2 = 960–1229 Ma). Zircon Hf isotopic features demonstrate that the primary magmas were mainly derived from Mesoproterozoic juvenile crust, accompanied by variable mixing with ancient sialic crustal components. The felsite and rhyolite porphyry formed in a post-collisional extensional setting, constraining the final closure of the eastern Mongol–Okhotsk Ocean to earlier than ~144 Ma. By contrast, Late Jurassic (150–146 Ma) Mo-mineralization-related granitoids in this area are Na-rich adakites with high Sr and low Yb, generated during oceanic subduction. The remarkable geochemical transition from 150–146 Ma subduction-related Na-rich adakites to 143–139 Ma post-collisional K-rich granites restricts a tectonic transition from compression to extension at ~145 Ma in the northern Great Xing’an Range. Full article

The Youjiang Basin is located in the southwestern margin of the South China Block and at the junction between the South China and Indochina Blocks at the eastern end of the Tethyan tectonic domain. The processes responsible for Triassic magmatism in the basin are crucial to understanding the closure of the Paleo-Tethys Ocean. This study presents the geochemistry and zircon U-Pb-Hf isotopes of granites from the Pingxiang area in the southwestern Youjiang Basin. The granites belong to the high-K and peraluminous series with A/CNK ratios of 1.16–1.38. They have high SiO₂ and K₂O contents and moderate Al₂O₃ content with moderately fractionated REE patterns (La_N/Yb_N = 6.35–7.83) and negative Ba, Sr, P and Ti anomalies, consistent with peraluminous A₂-type granites. The granites have LA-ICP-MS zircon U-Pb ages of 243–241 Ma, with negative εHf_(t) values ranging from −13.22 to −6.52 and T_DM2 model ages from 1654 to 2073 Ma. They were formed by partial melting of Paleoproterozoic metasedimentary rocks in an extensional setting. Combined with existing data, we suggest that the 243–241 Ma extensional event is related to the subduction-to-collision transition likely induced by slab breakoff during the closure of the Paleo-Tethys Ocean. Full article

Cellulose insulation paper used in oil-immersed power transformers is vulnerable to molecular chain loosening and aging-product transport under thermal and electrical stresses. Nanomodification is a promising route for improving insulation-paper stability, but the atomistic mechanisms by which KH550-grafted oxide nanoparticles regulate cellulose structure and aging-molecule mobility under an external electric field remain insufficiently clarified, particularly when the role of oilpaper insulation aging and oil-contact environments is considered. In this work, pristine cellulose and cellulose modified with KH550-grafted SiO₂ and Al₂O₃ nanoparticles were investigated using molecular dynamic simulations at 343 K under a uniform electric field of 0.01 V/Å (100 kV/mm) applied along the Z-axis. Based on the MSD and apparent transport-parameter results, nanomodification reduced the MSD-derived apparent coefficients of H₂O and CO₂ by 33.7–51.9%. The external field produced apparent directional transport bias, with Z/X apparent-coefficient ratios of 2.21 for H₂O and 2.02 for CO₂ in pristine cellulose. These ratios decreased to 1.62 and 1.51, respectively, in the KH550–Al₂O₃ model. Interfacial interaction energy analysis showed that the KH550–SiO₂ interface became more strongly bound under the field (−240.50 to −252.13 kcal/mol), whereas the KH550–Al₂O₃ interface remained nearly unchanged (−541.65 to −538.81 kcal/mol). Because the two nanomodified systems use different nanoparticle loadings and KH550 grafting ratios, cross-system differences are interpreted as model-specific outcomes rather than effects attributable only to nanoparticle chemistry. These results indicate that KH550-grafted nanoparticles may help maintain cellulose packing under the modeled conditions and suppress aging-molecule mobility in the simulated cellulose matrix, while the conclusions should be interpreted as atomistic simulation evidence rather than direct proof of long-term transformer reliability. Full article

The transition from conventional silica nanoparticle (SiNP) production based on purified alkoxysilanes and high-temperature flame hydrolysis of silicon tetrachloride to renewable and waste-derived silicon resources requires more than precursor substitution. It requires a mechanistic understanding of how feedstock mineralogy, silicon speciation, impurity chemistry, and processing history propagate through dissolution, nucleation, condensation, gelation, aging, drying, and pore evolution to determine material performance, environmental burden, and manufacturing feasibility. Although previous reviews have established the technical feasibility of producing silica from secondary resources, their predominant organization by feedstock, synthesis route, or application provides limited ability to explain why nominally similar processes generate materials with markedly different structural and functional properties. This review addresses these through a resource-pull, feedstock-to-function framework that links resource chemistry and process design to critical material attributes, application-specific specifications, sustainability, and scale-up requirements. Agricultural residues, industrial by-products, geothermal resources, waste glass, and fluorosilicate streams are critically compared according to silicon form and phase, reactivity, impurity profile, compositional variability, purification demand, and attainable product quality. Particular attention is given to waste-derived alkaline silicate systems, in which molecular, oligomeric, and colloidal silica coexist and therefore require characterization beyond bulk SiO₂ concentration. Established and emerging processing strategies, including controlled combustion and alkaline extraction, alkali fusion, ambient-pressure drying, microwave and mechanochemical activation, biogenic and biomimetic templating, and continuous processing, are evaluated according to their mechanistic effects, technological maturity, structural control, and demands for energy, reagents, water, solvents, effluent treatment, and capital. Across these routes, gelation and aging emerge as critical transfer stages through which feedstock composition is translated into network connectivity, pore architecture, shrinkage behavior, and ultimately functional performance. Evidence from secondary-source aerogels further shows that properly controlled waste-derived systems can attain BET surface areas of approximately 350–500 m² g⁻¹, within the textural range of many alkoxide-derived materials, indicating that feedstock variability, impurity management, and process control are more important constraints than an inherently lower performance ceiling. On this basis, this review proposes a minimum evidence framework comprising feedstock traceability, intermediate-speciation and colloidal characterization, silicon mass balance, gelation and aging metrics, application-specific qualification criteria, performance-normalized life cycle and techno-economic assessment, process analytical control, and staged pilot validation. Collectively, these principles provide a mechanistically grounded basis for moving sustainable silica synthesis beyond isolated proof-of-concept demonstrations toward reproducible, scalable, application-matched, and commercially credible manufacturing platforms. Full article

Primary implant stability arises from mechanical engagement at placement, and insertion torque is not a direct measure of osseointegration. This retrospective single-centre study included 101 MultiNeO titanium implant placements in 55 adults treated between April 2023 and January 2026. Four experienced operators placed implants subcrestally using a W&H Implantmed SI-1023, a bone-resistance-adapted drilling protocol, and a programmed target of 35 N·cm. Associations with recorded torque were assessed using a patient-clustered Gaussian generalized estimating equation adjusted for sex, age, anatomical sector, implant length and diameter, hard-tissue augmentation, and placement timing. The mean torque was 31.63 ± 5.57 N·cm; the median was 35 N·cm (Q1–Q3, 30–35). Recorded torque was 3.25 N·cm higher for implants placed in women than for those placed in men (95% CI 1.20–5.31; p = 0.002). Relative to maxillary anterior/premolar sites, mandibular molar sites showed higher torque (β = 4.02; p = 0.001), whereas mandibular anterior/premolar sites showed lower torque (β = −5.41; p = 0.013). Implant length had a modest adjusted association (β = 0.93 N·cm/mm; p = 0.022); age, diameter, augmentation, and placement timing did not. The concentration of recorded values at 35 N·cm reflects a clinical target rather than the device limit. These exploratory associations do not establish an intrinsic sex effect or predict osseointegration, and residual confounding due to unmeasured bone characteristics remains possible. Full article

Infrared-selective stealth films, which concurrently offer high visible transmittance, suppressed infrared emission, and selective thermal dissipation, have emerged as compelling candidates for infrared protection and thermal-target stealth. However, traditional multilayer architectures are predominantly designed through empirical trial-and-error protocols, which inherently hinder the synergistic optimisation of multiband spectral performance and yield suboptimal parameter-tuning efficiency. To circumvent this bottleneck, we introduce a reinforcement learning (RL)-driven multi-objective optimisation framework that automates the design of composite thin-film configurations. The optimised multilayer film structure consists of TiO₂/ITO/Ag/ZnO/SiO₂, with layer thicknesses of 180, 656, 10, 33.75 and 50 nm, respectively. Spectral characterisation reveals a weighted average visible transmittance of 79.77% over the 0.38–0.78 μm range, alongside blackbody-weighted average emissivities of 33.93%, 72.93%, and 19.94% in the 3–5, 5–8, and 8–14 μm bands, respectively. Consequently, the spectral profile exhibits high visible transparency, deep suppression of emissivity within the atmospheric windows (3–5 and 8–14 μm), and markedly elevated emissivity in the non-atmospheric band (5–8 μm). Analysis of the electromagnetic field distribution and power-loss density along the thickness direction reveals that the energy transmission and dissipation behaviours across distinct bands are synergistically governed by multilayer interference, interfacial multiple reflections, and lossy interlayer coupling mechanisms. Furthermore, angle-resolved infrared-emissivity analysis calibrated against the normal-incidence FDTD spectrum confirms that the structure retains robust polarisation adaptability and pronounced spectral selectivity at incidence angles up to 80°. The above results demonstrate the effectiveness of the reinforcement learning-driven optimisation framework for the automated co-design of multiband spectral responses. Moreover, the uncovered multilayer interference and loss-coupling mechanisms furnish a solid physical foundation for further performance refinement and rational design of transparent stealth coatings. Full article

The purpose of this paper is to determine the influence of the stearic acid and methyl esters on the properties of protective coatings applied to reinforced concrete objects. The evaluation of protective effectiveness included compositional analysis (XRD, XRF), surface properties (contact angle, surface energy, UV resistance), soiling resistance, roughness, and surface morphology (SEM). The scanning microscopy SEM images showed a relatively uniform distribution of resin on the concrete surface. The lateral dimensions of the epoxy-rich surface domains ranged from 8 μm to 40 μm. All analysed samples exhibited a very similar chemical composition, in which SiO₂ was the dominant component. In situ tests were conducted on an operating reinforced-concrete cooling tower. Among the investigated coating systems, ER1 + SA exhibited the highest observed mean apparent static water contact angle (CA) of 131°. A strong inverse empirical relationship was observed between the apparent contact angle and average surface roughness. UV ageing caused small numerical decreases in contact angle for most systems. After one year of operation, the ER2 epoxy coating modified with methyl esters was the best-preserved of the analysed variants. Full article

Hydrogen permeation barriers (HPBs) are essential to the development of both hydrogen and nuclear fusion energy. However, their structural stability and barrier efficiency under extreme conditions are scarcely reported, despite their significant importance to practical applications. Here, we experimentally investigated the effect of Li₄SiO₄ corrosion and deuterium aging on the structure and performance of an α-Al₂O₃ composite hydrogen permeation barrier coating under simulated fusion conditions. The results demonstrate that this coating could retain its dense and defect-free structure after corrosion with Li₄SiO₄ powders at 550 °C for 2 days, exhibiting good tritium breeder compatibility. Moreover, after the deuterium aging test for 6 months, its phase composition and microstructure show no significant changes, maintaining a compact and crack-free matrix strongly bonded to the substrate. After 6-month aging, the hydrogen permeation resistance of the α-Al₂O₃ composite coating at 500 °C is still 1450 times higher than that of the steel substrate without any aging. This work provides critical insights into designing highly reliable hydrogen permeation barrier coatings and understanding their performance evolution under harsh fusion environments. Full article

With the continuous expansion of ultra-deep and deep well drilling toward complex geological formations, the performance stability of water-based drilling fluids and wellbore stability under ultra-high temperature and high-salinity conditions have become critical challenges. High temperature and salt contamination can induce the degradation or failure of drilling fluid additives, while the development of pores and fractures in complex formations further increases the risk of filtrate invasion. Conventional polymer and inorganic plugging agents often suffer from insufficient thermal stability, poor salt tolerance, or limited adaptability to complex pore structures. In this study, an organic–inorganic hybrid gel microsphere plugging agent (HGP) with a core–shell structure was developed by in situ polymerization of AMPS, styrene (St), and sodium styrene sulfonate (SSS) on KH570-modified nano-SiO₂. The hybrid microspheres consisted of a rigid SiO₂ core and a flexible polymer shell, providing synergistic thermal stability, mechanical strength, and deformation capability. Structural characterization confirmed the successful formation of the designed organic–inorganic hybrid structure. After aging at 240 °C, HGP maintained stable morphology and dispersion characteristics, while exerting minimal influence on drilling fluid rheological properties. The addition of 3 wt% HGP reduced API fluid loss by approximately 30% and decreased sand bed invasion by approximately 50% after high-temperature aging. Under 35 wt% NaCl and 5 wt% CaCl₂ contamination, HGP maintained effective filtration control, reducing fluid loss by more than 50% compared with the base fluid. Furthermore, HGP achieved core plugging efficiencies above 94% and reduced mud cake permeability by over 70%, demonstrating superior plugging performance compared with polymer microspheres NF-1 and SiO₂ particles. The enhanced performance was considered to arise from the synergistic effects of stable dispersion, pore-throat bridging, deformation filling, and structural stabilization. This study provides a rigid–flexible hybrid strategy for designing high-performance plugging agents for ultra-high temperature and high-salinity water-based drilling fluids. Full article

Alkali-activated mortars (AAMs) have emerged as sustainable alternatives to conventional hydraulic cement (HC) matrices produced with natural sand. In this context, interest in the valorization of industrial by-products to develop eco-efficient construction materials has gained crucial academic and industrial attention. This study investigates the feasibility of producing AAMs incorporating copper slag (CS) as an artificial fine aggregate (AFA) to partially or completely replace natural sand. Moreover, the binder matrix was formulated using 80% CS and 20% HC as precursors, activated with different alkaline solutions (Na₂SiO₃ + NaOH) at activator-to-precursor mass ratios ranging from 0.15 to 0.35. Concurrently, CS was incorporated as AFA at volumetric replacement levels of 0%, 25%, 50%, 75%, and 100%. The AAMs were evaluated in terms of workability, physical performance (i.e., bulk density, water absorption, and void content), and mechanical performance. The results demonstrate that the workability of the AAMs increased with higher AFA dosages, reaching a maximum improvement of 23.8% compared with the AAM without AFA. The bulk density of the AAMs increased monotonically with increasing AFA content (consistent with the higher density of AFA with respect to natural sand), whereas water absorption and void content decreased progressively. Although all AAMs exhibited significantly lower compressive strengths than M1 at 7 and 28 days, the differences progressively decreased with curing age. At 56 and 90 days, M5 and M6, incorporating 75% and 100% AFA, respectively, achieved mean compressive strengths that were not statistically different from those of M1, indicating that the mixtures with the highest AFA contents maintained later-age mechanical performance within the variability of the conventional reference mortar. The study demonstrates the feasibility of the synergistic utilization of CS as both precursor and AFA in AAMs. This dual-pathway valorization closes materials loops and advances circular economy principles within the construction sector. Full article

The timing and nature of the tectonic transition from Neo-Tethyan subduction to India-Asia collision along the NW Himalaya remain debated, particularly regarding the relationship between continental arc and post-collisional magmatism in the Karakoram and Kohistan batholiths. We present zircon U-Pb ages, whole-rock geochemistry, and zircon trace-element data from three granitoid samples from the Attabad Lake area (Karakoram Batholith) and the Nomal area (Kohistan Batholith). Zircon U-Pb dating yields crystallization ages of 103.4 ± 1.7 Ma for the Karakoram diorite, and 46.10 ± 0.79 Ma and 43.59 ± 0.88 Ma for the Kohistan enclave and host quartz monzonite, respectively. The Karakoram diorite shows LREE enrichment [(La/Yb)_N = 5.93–78.52] and positive zircon Ce anomalies (Ce/Ce* = 9.00–18.70), features broadly consistent with crystallization from an oxidized, subduction-related magma. In contrast, the Kohistan quartz monzonite exhibits elevated SiO₂ (65.01–66.35 wt%), low Mg# (25.9–27.2), and a flat to slightly negative Eu anomaly (Eu/Eu* = 0.94), which may reflect crustal melting during post-collisional extension. The enclave displays mantle-like signatures with high Sr (1623 ppm) and a positive Eu anomaly (Eu/Eu* = 1.14), suggesting a mafic recharge event. Zircon Th/U ratios (>0.1) and magmatic REE patterns support a magmatic origin for the dated zircons. These results are compatible with, but do not independently establish, previously proposed regional models. They provide additional local constraints that point to spatially heterogeneous magmatic evolution along the NW Himalayan syntaxis, with continental arc magmatism in the Attabad Lake area during the mid-Cretaceous and a transition to post-collisional extension in the Nomal area during the Eocene. Full article

Jarosite-type residues generated during zinc hydrometallurgical processing represent a significant environmental liability and a latent source of valuable metals (Zn, Pb, Ag). In this study, the thermal decomposition and mineralogical evolution of an industrial ammonium jarosite residue were investigated to 600–1400 °C. The behavior of the as-received residue was compared against a designed flux-assisted formulation comprising 45 wt% jarosite, 40 wt% Na₂CO₃, and 15 wt% SiC. The conventional roasting of pure jarosite forms refractory zinc ferrite (ZnFe₂O₄) and releases SO₂ above 800 °C, while the flux-assisted route stabilized the sulfur as Na₂SO₄ and CaSO₄, decreasing toxic gas emissions. Concurrently, the reducing effect of the SiC significantly inhibited bulk zinc ferrite formation up to 1200 °C and favored the partial reduction of iron to magnetite (Fe₃O₄). Thermodynamic assessment using FactSage reasonably matches experimental results by X-ray diffraction and SEM-EDS measurements. The thermodynamic evaluation predicts the formation of elemental silver available for subsequent pickup by a collector metal and a liquid slag phase at approximately 1000 °C for the flux-assisted jarosite samples. The ammonium jarosite flux-assisted roasting strategy enhances the potential for metal recovery while increasing environmental sulfur fixation in the slag, aligning with sustainable circular economy principles in non-ferrous metallurgy. Full article

Understanding singlet oxygen (¹O₂) generation in plasmon-coupled photosensitiser systems is important for the design of photodynamic nanomaterials. In this study, silica nanoparticles decorated with satellite silver nanoparticle–photosensitiser conjugates (SiO₂–Ag–dye) were prepared using three representative photosensitisers: Rose Bengal (RB), protoporphyrin IX (PpIX), and coumarin-3-carboxylic acid (C3CA). ¹O₂ generation measurements showed lower singlet oxygen quantum yields (Φ_Δ) for all nanoparticle-bound dyes than for the corresponding free dyes. Among the investigated systems, SiO₂–Ag–PpIX retained approximately 80% of the ¹O₂ generation activity observed for the corresponding free dye (Φ_Δ = 0.45 ± 0.04), whereas SiO₂–Ag–RB (Φ_Δ = 0.31 ± 0.15) and SiO₂–Ag–C3CA (Φ_Δ = 0.12 ± 0.02) retained only approximately 40% of the corresponding free-dye activity. These results suggest that the photophysical behaviour and ¹O₂ generation efficiency of Ag-based dye–nanoparticle systems depend strongly on the immobilised photosensitiser. The findings provide insight into the interactions between plasmonic nanostructures and photosensitisers and may assist the future design of photodynamic nanomaterials. The present study should be regarded as a proof-of-concept demonstration of dye-dependent plasmonic modulation of ¹O₂ generation. Evaluation of practical photodynamic performance, photostability, and reusability will be the subject of future studies. Full article