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High-quality, large-weight alloy wires (>200 kg per coil) for aerospace fasteners require intermediate annealing prior to final cold drawing, as well as subsequent solution and aging heat treatments, which are critical processes during their manufacturing. However, the evolution of microstructure and mechanical properties during these procedures has not been systematically investigated. In this study, different cooling methods after intermediate annealing were comparatively investigated to clarify their influence on the microstructure evolution, precipitation behavior, and mechanical properties of Al–Zn–Mg–Cu alloy wires. The results revealed that the cold heading performance of alloy wires is determined by the strength–ductility balance, crystallographic texture, and precipitation behavior. Furnace cooling promoted η′ phase coarsening, resulting in lower strength and higher ductility, which enhanced deformation homogeneity and cold heading formability. The near-zero Δr reduced strain localization and cracking susceptibility, whereas higher Δr in water- and air-cooling samples increased anisotropy and cracking tendency. After heat treatment, strength differences became negligible, whereas elongation remained texture dependent, with the weaker texture in the furnace-cooling sample yielding superior ductility. Full article

In this study, the effects of friction stir welding (FSW) parameters on the mechanical properties and formability of pre-hardened (PH) 2219 aluminum alloy welds were systematically investigated through tensile testing and Erichsen tests. Energy dispersive spectrometry (EDS), electron back scatter diffraction (EBSD), and a transmission electron microscope (TEM) were employed to characterize the microstructure of the PH alloy weld joints, revealing the strength–ductility synergy mechanism of the PH welded sheets. Experimental results indicated that with respect to mechanical properties, when the welding rotational speed was fixed at 1000 rpm, increasing the forward speed from 50 mm/min to 150 mm/min reduced the ultimate tensile strength (UTS) by 6.3% and decreased the EL by 21.4%. When the forward speed was fixed at 50 mm/min, increasing the rotational speed from 500 rpm to 1500 rpm resulted in only a 0.4% variation in UTS and maintained a stable EL, demonstrating that forward speed is the dominant parameter affecting mechanical properties. In terms of formability, at a lower forward speed (50 mm/min), the Erichsen value exhibited a single-peak trend with increasing rotational speeds. At higher forward speeds (100 or 150 mm/min), the Erichsen value was insensitive to changes in rotational speed. When the rotational speed was fixed at 1500 rpm, increasing the forward speed from 50 mm/min to 150 mm/min reduced the Erichsen value by 21.3%. Microstructural strengthening mechanism: In the weld zone, the cooperative precipitation of the θ″ and θ′ phases effectively hindered dislocation motion. Simultaneously, the high geometric compatibility factor promoted the activation of multiple slip systems, and dislocation rearrangement subsequently led to the formation of sub-grain boundaries, thereby achieving strength–ductility cooperation. These findings provide theoretical support for the performance-driven welding process design of high-strength aluminum alloy components in aerospace applications. Full article

Based on monthly meteorological observations from 57 stations in Jiangsu Province during 1961–2022, the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated to characterize regional dry–wet variability. Empirical Orthogonal Function (EOF) analysis was applied to extract the dominant spatially coherent dry–wet modes, and cross-wavelet analysis was further employed to examine, in the time–frequency domain, the mode-specific responses to multiscale climate drivers, including the El Niño–Southern Oscillation (ENSO), Sunspot Number (SSN), Arctic Oscillation (AO), and Pacific Decadal Oscillation (PDO). The results show that dry–wet variability in Jiangsu Province is primarily organized by a regionally coherent mode (EOF1, explaining 56.3% of the total variance) and a north–south dipole mode (EOF2, explaining 17.8%), with the zero-value line of EOF2 closely aligned with the Huaihe River–Subei Irrigation Canal climatic transition zone. The temporal coefficient of EOF1 (PC1) exhibits a significant regime shift around 2013, followed by a pronounced wetting trend across the entire region. This change may reflect recent hydroclimatic adjustments in the study area, although the present study does not attempt a formal attribution of the respective thermal and precipitation contributions. In contrast, the temporal coefficient of EOF2 (PC2) undergoes an abrupt change around 1980, indicating a transition of the spatial dry–wet pattern from “southern drought–northern flood” to “southern flood–northern drought,” broadly consistent with an interdecadal climatic transition. Cross-wavelet analysis further reveals that PC1 is closely associated with ENSO at interannual timescales, with a lag of approximately 4–6 months, while its long-term variability shows time–frequency coherence with SSN. PC2 also exhibits time–frequency coherence with SSN at longer timescales, with an apparent phase transition around the 1980s; however, this low-frequency signal should be interpreted cautiously because the underlying physical mechanism remains uncertain. Overall, this study shows that dry–wet variability in Jiangsu Province is organized by two leading spatial modes with distinct temporal evolution and scale-dependent climate linkages. These findings provide new evidence for understanding hydroclimatic variability in monsoon transition zones and offer a basis for spatially differentiated drought–flood risk assessment. Full article

The integration of salt removal and structural consolidation remains a major challenge in heritage brick conservation. This research proposes a preliminary experimental setup for a dual-function microbial strategy using a single bacterium, Stutzerimonas stutzeri D1, capable of sequential denitrification (biocleaning) and ureolysis-driven microbially induced calcium carbonate precipitation (biocementation). After the pre-check assessment, which compared standalone, simultaneous, and sequential metabolic configurations, sequential denitrification followed by ureolysis (A→B) optimized functional compatibility, achieving 90.1% nitrate removal within 48 h and the highest precipitation rate during the biocementation phase. Application on authentic demolition waste (solid fired-clay brick specimens) demonstrated highly efficient nitrate reduction, alkalization (from pH value of 6.4 to 9.12), surface mineral deposition confirmed by visual inspection, SEM imaging, and XRD analysis. Furthermore, reduced water absorption (by 30%) and improved compressive strength (by 25%) for only 72 h of this dual treatment indicate a promising and holistic approach in the field of construction biotechnology of heritage brick conservation. These pioneer findings demonstrate that metabolic sequencing governs compatibility in dual-function bacterial systems and validate a sustainable, single-strain platform for combined biocleaning and biocementation of historic brick masonry structures. Full article

Graphene oxide (GO) was employed as an additive to improve the electrochemical activity of zinc oxide (ZnO) used as both a photoelectrocatalyst for water splitting and an electrochemical sensor for detection of diclofenac. To comprehend the influence of a small amount of GO on the electrochemical activity of ZnO, a series of ZnO/xGO (x = 0, 0.1, and 0.5) particles was synthesized by microwave processing of Zn(OH)₂ precipitate in the presence of 0.1 and 0.5 wt.% of previously prepared GO. The phase composition and crystal structure ordering of ZnO/xGO particles were investigated by XRD and Raman spectroscopy. The optical properties were studied by UV–Vis DRS and PL spectroscopy. The particle morphology was inspected by FE–SEM while the textural properties were analyzed by the low-temperature nitrogen adsorption–desorption method. The (photo)electrocatalytic and electrochemical sensing activities were examined on the ZnO/rxGO modified glassy carbon electrodes (GCEs) prepared by in situ reduction of the ZnO/xGO modified GCEs for 120 s. The electro- and photoelectrocatalytic activity of ZnO/rxGO modified GCEs for water splitting was tested in dark conditions and after 60 min under illumination, respectively, employing linear sweep voltammetry in 0.1 M NaOH and 0.1 M H₂SO₄ as electrolytes. The electrochemical sensing activity of ZnO/rxGO modified GCEs was tested for detection of diclofenac in aqueous solution. The improvement in the electrochemical activity of ZnO was correlated with the added amount of GO, structural defects, and particle morphology. Full article

Under the context of global change, forest cover, as a critical component of terrestrial ecosystems, exerts a profound influence on regional ecological security and sustainable development through its spatiotemporal evolution. Current research on forest cover change primarily focuses on pattern description and single-factor driver analysis, with insufficient in-depth exploration of the interactions among multiple factors and their associated nonlinear mechanisms. To address this gap, this study focuses on the Wumeng Mountain area, a typical ecologically fragile karst region in Southwest China. By comprehensively employing methods such as Theil–Sen Median trend analysis, land use transfer matrix, standard deviation ellipse, and spatial autocorrelation analysis, this study systematically reveals the spatiotemporal evolution characteristics of forest cover from 1985 to 2024. On this basis, an integrated eXtreme Gradient Boosting–SHapley Additive exPlanations (XGBoost-SHAP) model is introduced to construct an indicator system comprising 16 driving variables, including elevation, slope, aspect, temperature, precipitation, soil type, soil pH, soil thickness, soil organic matter, soil moisture content, GDP, population, distance from water, distance from railway, distance from grade highway, and distance from government. This model quantifies the influence intensity of each driving factor on forest change. The main findings are as follows: (1) From 1985 to 2024, the forest cover rate in the Wumeng Mountain area significantly increased from 54.7% to 60.2%, exhibiting a “high-low-high” heterogeneous spatial distribution pattern along the northeast-southwest axis; (2) Forest increase primarily originated from the conversion of cropland and grassland, with contribution rates reaching 93.58% and 5.9%, respectively, indicating an overall trend of “increase in low-value areas and decrease in high-value areas”; (3) Forest cover change is driven by both natural and anthropogenic factors, with dominant driving factors exhibiting phased replacement over time. Overall, this is manifested as long-term stable constraints exerted by natural background factors, alongside strong disturbances from anthropogenic factors such as social-economic, and transportation-related activities. Natural factors remain the primary driving force behind changes in forest cover. The core findings of this study elucidate the complex driving factors of forest change in karst mountainous areas, thereby providing scientific support for the precise management of regional forest resources, the planning of ecological restoration projects, and the implementation of sustainable development strategies. Full article

This study investigated the relationship between Mn segregation, damping capacity, and mechanical properties of a Mn–Cu damping alloy after aging at different temperatures. The results showed that after aging, the alloy underwent spinodal decomposition, forming Mn-segregated regions, while α-Mn precipitates appeared at the grain boundaries. The microstructure resulting from spinodal decomposition promoted martensitic transformation, created twin boundaries, and enhanced damping capacity. As the aging temperature increased, the Mn content in the Mn-rich regions gradually rose, thereby raising the martensitic transformation temperature. The twin density first increased and then decreased, which may be attributed to the precipitation and broadening of the α-Mn phase along the grain boundaries of the Mn-rich regions when the aging temperature was too high. At an aging temperature of 425 °C, the tanδ reaches a maximum of 0.05, and the martensitic transformation temperature reaches 100 °C, at which point the tanδ remains 0.04. After aging at 425 °C, a preferred orientation along <001> develops. The [001] orientation has the largest Schmid factor, which is most favorable for the reversible motion of twin boundaries under external stress, thus achieving the highest energy dissipation. To summarize, by promoting the creation of fine {011} twins by means of spinodal decomposition and by increasing the [001] oriented grain fraction through texture development, aging enhances the damping properties of the Mn–Cu alloy. In particular, the aging at 425 °C can provide the best combination of the microstructure and texture conditions, providing the highest damping performance in a wide temperature range. Full article

Climate change is intensifying extreme climatic events such as warming and drought. This study investigated the physiological and growth responses of Quercus variabilis, a major broadleaf plantation species in South Korea, to warming and drought under open-field conditions. From July to August 2024, one-year-old seedlings were exposed to factorial treatments of temperature (ambient: TC; +3 °C: T3; +5 °C: T5) and precipitation (ambient: PC; drought: DR). Gas exchange was measured twice (early: 12 July; late: 16 August) during the treatment period. In the early phase of the experiment, net photosynthetic rate (P_n) was 11.4% lower in DR than in PC, whereas differences were no longer significant in the late phase. Stomatal conductance (g_s) was significantly affected by the interaction between temperature and precipitation. These results suggest that the decline in photosynthesis was driven by non-stomatal limitations such as photosystem II impairment or reduced Rubisco activity, despite maintained or enhanced stomatal conductance. Consequently, intrinsic water-use efficiency (iWUE) during the late phase was 24.3% lower in T5 than in TC. Root collar diameter (RCD) was more sensitive to drought than height growth. Shoot (stem + leaf) biomass was 23.7% higher in T5 than in T3, and root biomass was 20.5% higher in T5 than in TC. However, the root-to-shoot (R/S) ratio did not differ significantly among temperature and precipitation treatments. These findings suggest that Q. variabilis seedlings exhibit physiological plasticity and maintain relatively stable biomass allocation under short-term warming and drought conditions. Full article

Heat-resistant Al–Zr conductors are limited by the strength–conductivity trade-off and by long aging schedules required to stabilize Al₃Zr-based precipitates. This work investigates the combined effect of scandium addition (0–0.30 wt.%) and ultrasonic treatment (UST) during melt processing on Al–0.3Zr–xSc alloys. UST was applied at 710 °C before casting; phase-equilibrium analysis and quantitative measurements of intermetallic distribution, grain size, electrical conductivity, and tensile properties were performed before and after 25 h aging. Grain refinement shows a clear Sc-dependent threshold: UST refines the Sc-free alloy to ~177 μm, whereas 0.05 wt.% Sc causes abnormal coarsening (~396 μm). Increasing Sc to 0.10–0.20 wt.% produces pronounced refinement (~110 to ~82 μm), and the refined grain structures are retained after aging. At 0.20 wt.% Sc, the aged alloy achieves >100 MPa tensile strength while recovering approximately 58% IACS (International Annealed Copper Standard). Overall, the results reveal a composition-dependent synergy between Sc microalloying and UST that enables microstructure control and an improved strength–conductivity balance, with potential to contribute to more efficient processing strategies for heat-resistant aluminum conductors. Full article

In this paper, the effects of 4 wt.% of silicon on the microstructure and mechanical properties of AM50 magnesium alloys fabricated by the casting method are presented. New AM50/Si material and the base AM50 alloy were gravity cast into a metal mould under the same conditions for comparison. Analyses of the alloys’ microstructures were carried out by light microscopy (with differential interface contrast), scanning electron microscopy (with an energy dispersive X-ray spectrometer), as well as X-ray diffraction (XRD). In as-cast conditions, both materials were composed of α-Mg solid solution, α + γ eutectic (where γ is Al₁₂Mg₁₇), Al₈Mn₅ intermetallic phases and discontinuous γ precipitates. The AM50/Si material also consisted of the Mg₂Si phase. This structural constituent appeared in the form of primary crystals with regular polygonal morphology and an α + Mg₂Si eutectic in the form of “Chinese script”. In the microstructure of the AM50/Si material, the Mn₃SiAl₉ ternary phase was also identified. The detailed analyses presented in this paper revealed that the new ternary Mn₃SiAl₉ structural compound caused a reduction in the volume fraction of the Al₈Mn₅ phase but did not completely replace it. These two phases formed competitively. The fabricated material exhibited higher tensile and compression strength as well as yield strength in comparison with the AM50 alloy. Additionally, analyses of the fracture surfaces of the AM50/Si material carried out using scanning electron microscopy (SEM) were presented. Full article

The inherent drying shrinkage of geopolymers restricts their widespread application in concrete crack repair, particularly for medium-to-wide cracks that demand stringent workability and penetrability. This study systematically investigates the effects of three single-component expansive agents (MgO, CaO, and CSA) on the fresh properties, mechanical performance, and microstructural evolution of a slag-fly ash-based geopolymer. The optimal modified formulation was subsequently evaluated for remediating preinduced concrete cracks (2.0, 2.5 and 3.0 mm apertures) and benchmarked against ordinary Portland cement and epoxy resin. The results indicate that while CaO and CSA severely compromise paste fluidity and induce rapid setting, MgO modification provides an exceptional operational window. An 8 wt.% MgO dosage (MG8) induces only a marginal 3.73% reduction in paste fluidity and maintains stable initial and final setting times, thereby preserving excellent workability retention and enabling precise construction scheduling. Microstructural analyses (XRD, SEM, and MIP) reveal that the precipitation of micro expansive Mg(OH)₂ effectively suppresses the 28-day drying shrinkage to 0.23%, while facilitating the attainment of a robust compressive strength of 44.1 MPa and preserving a highly favorable strength development trajectory. In the structural repair phase, the MG8 demonstrated outstanding compressive strength recovery, peaking at 28.80 MPa for 2.0 mm cracks, which significantly outperformed both the cement and epoxy resin repaired groups. Conversely, the epoxy resin repaired specimens exhibited superior splitting tensile strength due to the inherent elongation properties of the flexible macromolecular polymer. Comprehensive durability assessments revealed that the MG8 repair system exhibits exceptional resistance against freeze–thaw cycles and sulfate/chloride attacks, ensuring long-term structural integrity that significantly outperforms conventional materials. Overall, this work presents a viable and durable geopolymer-based alternative to traditional materials, aiming to ensure timely and reliable remediation concrete cracks that do not cause structural damage. Full article

The preparation of new magnetic materials is important because of their potential application in various electronic components. In the present work, the synthesis of glass-crystalline materials in the system Na₂O-MnO-SiO₂-Fe₂O₃ prepared by applying melt-quenching is reported. The phase composition as studied by X-ray diffraction and Raman spectroscopy reveals the precipitation of monophase Mn_xFe_3−xO₄ based solid solutions. The microstructure is studied by scanning electron and optical microscopy and shows bulk crystallization and the presence of polygon-shaped as well as of dendritic crystals, depending on the iron oxide concentration and used raw materials. Mössbauer spectra show that in the amorphous matrix the Fe ions are mainly present as Fe³⁺ in tetrahedral coordination and as Fe³⁺ in a solid solution with the composition Mn_xFe_3−xO₄. The simultaneous presence of MnFe₂O₄ (jacobsite) and a Mn-containing solid solution based on Fe₃O₄ (magnetite) is suggested. The room temperature magnetic properties were studied by vibrating sample magnetometer and reveal ferrimagnetic properties for all investigated glass-crystalline materials. Full article

The present work aimed to obtain antibacterial wound dressings using bacterial cellulose (BC) as a support, to improve wound treatment and reduce the incidence of infections. To enhance the antibacterial activity of the synthesized dressings, the introduction of ZnO nanoparticles into the BC network by precipitation was pursued. The method chosen to develop ZnO NPs was green synthesis, an ecological and sustainable method for obtaining nanomaterials using plant extracts as reducing agents or stabilizers. Thus, the chosen plants were Ginger rhizomes, Bay leaves, and Rose hips, in both fresh and dry form, due to the natural benefits they possess, and the Soxhlet method was used to obtain the plant extracts desired to be used in the synthesis. The composite dressings were developed in two distinct sample series, differentiated by the immersion time of BC in the precursor Zn²⁺ solution. The samples in the first series were obtained by precipitation in a mixture of Zn²⁺ solution and natural extract, whereas the samples in the second series were obtained by successive immersion in Zn²⁺ solution and then in natural extract, which demonstrated a considerable difference. The best antimicrobial activity tested against Gram-negative bacterium Escherichia coli was recorded for the composite material obtained in the presence of fresh rose hip extract, an aspect most likely related to the morphological and crystalline features of the ZnO phase, but also to the phytochemical profile of the extract used. Such eco-friendly materials represent valuable candidates for wound dressing applications due to their ability to support wound healing, relief burns, and skin irritation, provide antimicrobial protection, promote skin regeneration and reduce scarring, protect sensitive skin, and act as a barrier against external contaminants. Full article

CoNiV medium-entropy alloy (MEA) composite coatings reinforced with 40 wt.% tungsten carbide (WC/W₂C) particles were fabricated on carbon steel via laser cladding under nominal heat inputs ranging from 75 to 150 J/mm. The phase constituents and microstructural evolution were investigated, revealing that the coatings were primarily composed of an FCC matrix, retained WC/W₂C particles, and in situ formed V-rich and VWC₂ carbides. While the phase compositions remained generally consistent, the features of the reinforcement architecture varied with the extent of WC/W₂C dissolution governed by laser heat inputs. At low heat inputs, limited particle dissolution yielded sparsely distributed in situ carbides, whereas excessive dissolution at high heat inputs promoted the agglomeration of dense and coarse carbides, driving the microhardness to peak at 570.5 HV_0.5. However, the coating deposited at 150 J/mm exhibited compromised wear resistance due to the fragmentation and detachment of these coarse carbides, which intensified abrasive wear. In contrast, moderate dissolution at intermediate heat input (100 J/mm) facilitated the formation of fine in situ carbides in interparticle regions. This resulted in a homogeneous multiscale synergistic reinforcement microstructure that endowed the coating with optimal wear performance. By precisely controlling heat input to regulate in-situ precipitation, this study established a solid foundation for tailoring wear resistance and expanding the application of composite coatings. Full article

Monitoring air quality is crucial for understanding and improving public health. There is interest in developing ultra-sensitive, low-power, cost-effective sensors. This work demonstrates that structural modulation of Sn nanoparticles through controlled deposition and oxidation enables a transition from metallic to semiconducting percolative networks, significantly enhancing NO₂ sensing performance at room temperature. The proposed percolation-driven sensing mechanism provides a new framework for understanding charge transport and gas interaction in nanostructured metal oxide systems. The nanoparticles are deposited near the percolation threshold for electrical conduction and, upon exposure to air, consist of a tin core and an amorphous Sn₃O₄ surface. Post-deposition heating in air at 320 °C for two hours forms SnO and Sn₃O₄ on top of the gold electrodes and polycrystalline SnO in the tetragonal litharge phase, known as Romarchite, on the glass between the electrodes. Both as-deposited and heat-treated sensors were capable of detecting NO₂ at room temperature, with a limit of detection in the parts-per-billion range. A percolation model is used to explain their operating currents, in which NO₂ reacts at nanoparticle gaps and intra-grain boundaries to form charge-depletion regions that primarily determine their resistance. Heat treatment has also been found to cause disproportionation of SnO, resulting in tin-rich precipitates and increasing the operating current to the milliampere range. These precipitates, although oxidized on their surfaces when exposed to air, may serve as bridges that reduce the total resistance of the percolating paths. Full article