Search Results (2,632)

The antimicrobial activity of multicomponent, magnetron-sputtered glass coatings was evaluated against phytopathogenic fungi (Botrytis cinerea, Fusarium oxysporum, Cladosporium fulvum, Alternaria solani) and the chromista Phytophthora infestans, with Aspergillus fumigatus included as a model opportunistic pathogen. Fourteen Cu-based multicomponent coatings were deposited on glass using multi-alloy targets composed of Sn, Zn, Al, Ni, Fe, Ti, Mn, Nb, or Co in two high-transmittance variants (≥85% and ≥88%). Antimicrobial activity was assessed in two assays: (A) spore survival after 24–72 h contact, and (B) hyphal growth over 7 days following coating exposure under light and dark conditions. Spore viability decreased after incubation on high-Cu coatings, which showed inhibition for most strains, particularly B. cinerea, F. oxysporum, and P. infestans. The effects on spore germination were independent of the direct transmittance value of the coated glass. Hyphal growth was generally less affected by a high Cu content for most strains. Hyphal growth of F. oxysporum, C. fulvum, A. solani and B. cinerea was reduced by up to 30% on selected multicomponent coatings. For most strains, hyphal growth showed no inhibition after light incubation on coatings. However, light-dependent effects were observed for A. solani, A. fumigatus and P. infestans, while B. cinerea and C. fulvum showed reduced sensitivity during the first two days. High-Cu coatings were most effective at inhibiting spore germination, whereas hyphal growth on multicomponent coatings may respond to different ions. Therefore, high-Cu, two-component coatings may be recommended for practical greenhouse applications. Full article

Heavy metals in urban dust, derived from anthropogenic activities and natural sources, are considered potentially toxic elements for human health. The city of Puebla, located in Central Mexico, is one of the ten largest metropolitan cities in Mexico. Near this city is the Popocatépetl volcano, which contributes heavy metals through the emission of ash. The objectives of this study were to evaluate heavy metal contamination in urban dust and volcanic ash from the city of Puebla, and to determine the associated human health risks. Heavy metals were analyzed using an XRF spectrometer. The level of contamination was established according to the contamination factor, the geoaccumulation index and the contaminant load index. Furthermore, non-carcinogenic risk indices (HIs) were calculated to evaluate the health risk. The results revealed the presence of 18 elements (Ca, Cr, Cu, Fe, K, Mn, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ti, Y, V, Zn and Zr), with the highest concentrations found for most in urban dust samples, while Rb, Ca and K showed higher concentrations in ash samples. High levels of Sb and Sn contamination were found in 90 to 100% of the dust and ash samples, while Cr, Cu, Ni, Pb and Zn showed considerable levels of contamination in 60 to 90% of the samples. According to the US EPA thresholds, the health risk assessment indicated safe levels (HI < 0.25) for Cu, Fe, Mn, Ni, Pb, Sn, V and Zn in the urban dust and volcanic ash samples, while some of the samples exceeded the safety threshold (HI > 1) for Cr and Sb with respect to the child population in the city of Puebla. These results must be taken into consideration by environmental and government authorities, and the degree of pollution should be reduced accordingly. Full article

Magnetite is extensively developed within various alteration zones of the mining district. Some magnetite is closely associated with copper mineralization, possessing significant research value. The Duobuza Cu (Au) deposit is a typical porphyry-type deposit within the Bangong Co-Nujiang metallogenic belt and was the first porphyry Cu-Au deposit discovered in the Duolong copper–gold ore district. Currently, this deposit contains copper resources exceeding 3 million tons @0.46%, with associated gold resources exceeding 80 tons @0.19 g/t. This study focuses on magnetite from the Duobuza deposit. Through field geological logging and microscopic identification combined with electron microprobe analysis (EMPA) and in situ LA-ICP-MS testing, mineralogical and mineral chemical research on magnetite is conducted. This research aims to elucidate the genesis of magnetite in the Duobuza deposit and its implications for mineral exploration. Five magnetite types with different occurrences can be distinguished in the Duobuza deposit: Mt₁ is magmatic magnetite; Mt₂, Mt₃, Mt₄, and Mt₅ are hydrothermal magnetite, with Mt₅ being closely associated with copper mineralization. Mt₁ is relatively enriched in Ti, V, Al, and Cr but depleted in Mn and Si; Mt₂ is relatively enriched in Ti and Al but depleted in Si and Cr; Mt₃ is relatively enriched in Al but depleted in Mg; Mt₄ is relatively enriched in Ti, Al, V, Zn, and Mn; and Mt₅ is relatively enriched in Mg, Si, Ti, Al, Mn, and Zn but depleted in Cr. Based on the Al + Mn vs. Ti + V discrimination diagram, magnetite formed in a medium- to high-temperature environment, with hydrothermal magnetite Mt₄ forming at the lowest temperature. Vanadium (V) content can be used to estimate the oxygen fugacity (fO₂) during mineralization. Mt₁ exhibits the highest V content, indicating relatively low oxygen fugacity, whereas Mt₄ shows the lowest V content, suggesting relatively high oxygen fugacity. Mt₅ has a higher V content compared to other early-stage hydrothermal magnetites, suggesting that a lower fO₂ formation environment favors the precipitation of metal sulfides in the mining district. Trace element analysis of magnetite from the Duobuza, Bolong, and Naruo mining districts reveals that magnetite from all three deposits is enriched in Si and Al and depleted in Ca and Ni. Magmatic magnetite from the Naruo and Duobuza deposits exhibits similar elemental distribution patterns. Hydrothermal magnetite from the Duobuza deposit shows significantly higher Ti and V contents compared to magnetite from the Bolong and Naruo deposits. Full article

Modern materials science is focused on the development of steels with a range of performance characteristics, including high strength, wear resistance, corrosion resistance, and long-term performance in various conditions. Special attention is paid to the control of the microstructure of steels at the crystallization stage, which allows for the improvement of metal properties without significantly increasing the cost of the manufacturing process. One of the promising methods of microstructural engineering is the modification of steels with dispersed particles of refractory compounds, such as titanium carbide (TiC), zirconium carbide (ZrC), and tungsten carbide (WC). However, the processes of dissolution, dissociation, and interaction of such ceramic particles with the metal melt, as well as their influence on the formation of the microstructure and properties under the conditions of non-equilibrium crystallization, which is typical for centrifugal casting, are not sufficiently studied for austenitic stainless steels. In this work, the influence of dispersed carbide particles of TiC, ZrC, and WC, which are introduced into the melt of austenitic stainless steel (Cr ≈ 18%, Ni ≈ 10%) during centrifugal casting, on the redistribution of alloying elements, the formation of the microstructure, and the mechanical properties of the material is investigated. Special attention is paid to the kinetic nature of the dissolution and interaction of the carbides with the melt, as well as the directional distribution of elements across the cross-section of the billets. The study includes the analysis of the distribution of Ti, W, and Zr across the cross-section of the centrifugally cast billets, the study of the microstructure and phase composition of the inclusions using SEM/EDS, and mechanical testing. It is found that the implementation of dispersion hardening leads to an increase in the tensile strength by up to ~22% compared to the initial alloy (from 496 to 612 MPa), while the impact strength decreases by 5–25% (from 110 to 82 J/cm²) depending on the type and quantity of the introduced particles. The analysis of microhardness shows the presence of a gradient of local properties across the cross-section of the centrifugally cast billets, with microhardness values ranging from ~110 to 195 HV0.5. For the modified samples, the relative difference between the inner and outer zones is ~5–20%, reflecting the combined effect of non-equilibrium solidification, redistribution of alloying elements, formation and spatial distribution of secondary phases, and local structural heterogeneity. These results confirm the possibility of controlling the distribution of properties within a single billet. Full article

In this work, an A-site deficient perovskite, (La_0.3Sr_0.6Ce_0.1)_0.9Co_0.1Ti_0.9O_3−δ (LSCCoT) was applied as an additional catalytic layer on Ni–YSZ anode for biogas-fuelled SOFC. Under reducing conditions, the formation of well-dispersed, socketed Co nanoparticles was observed due to the cobalt exsolution from the perovskite lattice. The structural and microstructural characterization confirmed phase stability of the perovskite after high-temperature reduction in hydrogen and the presence of exsolved nanoparticles on the grains’ surface. Electrical conductivity measurements showed thermally activated semiconducting behavior in air (E_a = 0.582 ± 0.121 eV) and a strongly enhanced conductivity with weak temperature dependence in hydrogen (E_a = 0.057 ± 0.001 eV). Single-cell tests performed under a CH₄/CO₂ (60/40 vol%) biogas mixture revealed a 30% increase in maximum power density at 800 °C compared to the reference cell. During 100 h of operation, the modified cell exhibited reduced performance degradation, improved internal reforming activity, and a more stable outlet gas composition. Full article

Polyolefins are widely used polymers, with an annual global production of hundreds of millions of tons. Because they are the simplest hydrocarbon polymers, their intrinsic non-polar properties limit further applications. Coordination–insertion copolymerization of an olefin with other monomers, mediated by transition metal catalysts, is the most efficient way to synthesize polar and multi-functionalized polyolefins with enhanced material performance. Previous reviews have primarily focused on the structural design of a specific catalyst or on binary copolymerization of an olefin with a particular comonomer. However, the transition-metal-catalyzed ternary coordination–insertion polymerization of olefin monomers remains scarce. In this contribution, early transition-metal catalysts, such as Ti, Zr, Hf, and V, are employed for the terpolymerization of all-hydrocarbon or non-polar monomers to access advanced polyolefin materials with high performance. By contrast, late transition metal catalysts based on Ni and Pd, as well as rare-earth metal catalysts ligated by Sc and Y, enable the terpolymerization of olefins with a variety of heteroatom-containing monomers. Their strong tolerance empowers the development of polyolefins with multiple functionalities, thereby distinguishing these systems. The catalyst structure, catalytic process, and mechanism studies are summarized, along with the microstructure and functionality of the polymerization products, by classifying the types of termonomers employed. Full article

Responses to cutaneous injury differ fundamentally across developmental stages in several mammal species. During early human gestation, when the fetus is less than 24 weeks old, wounds are capable of restoring normal tissue architecture without forming fibrotic scars. In contrast, postnatal and adult injuries typically resolve through the process of fibrosis. This divergence reflects coordinated differences in epidermal and dermal compartments, inflammatory signaling, extracellular matrix (ECM) composition, mechanical cues, and gene regulation. Recent studies have demonstrated that dermal fibroblasts are no longer considered a uniform population but instead arise from distinct developmental lineages with stable functional identities. Engrailed-1-negative fibroblasts (ENFs) predominate in early fetal skin in mice and support regenerative repair, while Engrailed-1-positive fibroblasts (EPFs) emerge later in development and are the principal contributors to fibrotic matrix deposition following injury. The developmental shift between these fibroblast populations coincides with the loss of scar-free healing capacity. This review examines the current understanding of fibroblast lineage specification, with particular emphasis on the roles of mechanotransduction, extracellular matrix cues, and epigenetic regulation. Elucidating how these lineage-encoded programs are established and maintained may enable strategies to reprogram adult fibroblasts toward a fetal-like regenerative state and thereby promote scar-free tissue repair. Full article

Nickel-titanium (NiTi) alloys are attractive for functional and biomedical applications due to their shape memory effect, superelasticity, and favorable corrosion resistance and biocompatibility. In this work, the influence of strut size on the compressive response of laser-based powder bed fusion (PBF-LB/M) fabricated NiTi ortho-octahedral porous scaffolds was systematically investigated using combined experiments and finite element simulations. Four scaffold designs with identical unit-cell size (2 mm) but different strut sizes (280, 320, 360, and 400 μm) were fabricated, and their forming quality and deformation behaviors were examined. The as-built scaffolds exhibited high geometric fidelity to the CAD models and stable manufacturability across the investigated parameter range. Quasi-static compression tests revealed a typical three-stage response (linear-elastic regime, plateau/collapse regime, and densification), with both elastic modulus and compressive strength increasing markedly with strut size. Specifically, the modulus increased from 1.17 to 4.28 GPa and the compressive strength increased from 155 to 564 MPa as the strut size increased from 280 to 400 μm. A pronounced oscillatory plateau was observed for the 280 μm scaffolds, indicating progressive layer-by-layer collapse, whereas larger struts promoted a shear-band-dominated failure mode characterized by an approximately 45° fracture zone. Explicit quasi-static simulations reproduced the experimentally observed collapse sequence and demonstrated that stress preferentially concentrates at nodal junctions, with load transfer dominated by struts aligned with the loading direction. The agreement between experiments and simulations confirms the predictive capability of the proposed modeling framework and provides mechanistic insights into geometry-controlled failure. These findings establish a structure-property-failure relationship for PBF-LB/M-fabricated NiTi octahedral scaffolds and offer practical guidance for tailoring stiffness, strength, and collapse mode through strut-size design. Full article

This study systematically investigates the influence of annealing time on the microstructure and mechanical properties of a (CoCrNi)_93.5Al₃Ti₃C_0.5 medium-entropy alloy. Following hot-rolling, the alloy was subjected to annealing treatments at 900 °C for 10 min (HA900-10) and 60 min (HA900-60). Microstructural characterization revealed that both alloys contained three types of precipitates: intergranular M₂₃C₆ and MC-type carbides, as well as γ′ phase. The HA900-10 specimen exhibited a low degree of recrystallization, whereas prolonged annealing promoted partial recrystallization, leading to the formation of a slightly heterogeneous structure (HA900-60). Additionally, the extended annealing facilitated the intragranular precipitation of nanoscale γ′ phase. Room-temperature tensile tests demonstrated that the HA900-10 and HA900-60 specimens achieved yield strengths of 1276 MPa and 1202 MPa, with total elongations reaching 26% and 28%, respectively. Quantitative strengthening analysis indicated that the strength of HA900-10 primarily originated from dislocation and grain boundary strengthening. For HA900-60, an additional significant contribution arose from the dislocation shearing mechanism induced by the intragranular γ′ precipitates. Analysis of the deformation mechanisms revealed that planar slip, assisted by the formation of stacking faults, dominated the room-temperature deformation, thereby ensuring sustained work-hardening capacity. This research provides a theoretical foundation for tailoring the microstructure and properties of multi-phase medium-entropy alloys through annealing process control. Full article

CoCuNiTi HEACs reinforced by different diamond contents were prepared on the surface of 45 steel substrate by laser cladding. Their phase composition, microstructure, elemental composition, and wear/corrosion resistance were investigated using XRD, OM, SEM, EDS, a friction and wear testing machine, and an electrochemical workstation, respectively. The results show that after adding diamond, the phase composition of the sample transforms from the original dual-phase structure of the FCC main phase and BCC to the dual-phase structure of the BCC main phase and FCC. With an increase in the diamond content, the diffraction peak intensity of the alloy phases first increases and then decreases. This behavior is related to the significant enhancement of the alloy phase crystallinity with low diamond addition and the intensified crystal lattice distortion caused by excessive diamond addition. The CoCuNiTi + x Diamond (C) (x = 0, 0.5, and 1.0 wt.%) high-entropy alloys have a dendritic structure. After the addition of diamond, no hole defects were observed in the microstructure, and the dendritic structure was significantly refined. Ti and C are enriched in the primary phase, Cu is enriched in the interdendrite regions, and Co exhibits the highest concentration in the dendrite regions. The segregation coefficients of Ni in all three alloys are relatively small. As the diamond content increases, the friction coefficient of the samples decreases significantly. The 1 wt.% diamond sample exhibits the best wear resistance, primarily owing to the combined effects of superhard phase strengthening, solid solution strengthening, and fine grain strengthening resulting from diamond addition. The sample with 0.5 wt.% diamond addition has the lowest self-corrosion current density, highest polarization resistance, and lowest annual corrosion rate, indicating the best corrosion resistance. This performance is mainly attributed to the refinement of the microstructure, reduction in defects, and formation of a dense passivation film caused by the addition of a small amount of diamond. Full article

The 0.006Pb(Mn_1/3Ta_2/3)O₃-0.114Pb(Ni_1/3Ta_2/3)O₃-0.43PbZrO₃-0.45PbTiO₃ lead-based ceramics (PMT-PNT-PZT) were synthesized via the solid-state reaction at different sintering temperatures to study their effects on phase structure, microstructure, and electrical properties. The maximum mechanical quality factor (Q_m) and relative permittivity (ε_r) were achieved at the sintering temperature of 1200 °C. The piezoelectric constant d₃₃ of 400 pC/N was obtained at 1180 °C, which is attributed to the high grain density and the significant contribution from the remanent polarization and permittivity product (P_rε_r = 39,115 μC/cm²). Compared with commercial PZT4 ceramics, the present composition sintered at 1180 °C exhibits an optimal balance between d₃₃ and Q_m, together with the superior figure of merit (FOM = 2.04 × 10⁵ pC/N). Furthermore, it demonstrates excellent temperature stability in electromechanical coupling performance. Full article

Ni thick films have a wide range of applications in mechanical areas for anti-corrosion, anti-friction and protection purposes, and are also extensively employed in the chip packaging field. Yet, the deposition of Ni thick films is still faced with many problems in deposition efficiency, dense structure and adhesion to the substrate. RF magnetron sputtering was employed to deposit on polished Ti substrate up to 10.8 µm thick Ni films at a high deposition rate (45 nm/min) in Ar atmosphere plus a small amount of H₂. Vacuum annealing was performed at 400 °C for 5 h. To characterize the adhesion via friction and scratch test, different loads were applied on both surfaces of as-sputtered and post-annealed Ni thick films, and results were comparatively analyzed. The films have high purity, compact structure, smooth surface and strong adhesion strength. Post-annealed samples showed better and stable adhesion of Ni thick films to the substrate surface. Full article

Medium-entropy alloys (MEAs) with a simple phase structure and nanoprecipitates have excellent mechanical properties and considerable potential for advanced structural applications. The current study investigated the effect of boron microalloying and thermomechanical treatment on the microstructure evolution and mechanical properties of Co₄₃Cr₁₅Ni₃₀Al₅Ti₇ and (Co₄₃Cr₁₅Ni₃₀Al₅Ti₇)_99.7B_0.3 MEAs. X-ray diffraction analysis revealed a single phase of face-centered cubic (FCC) structure in all as-cast samples. After cold rolling and recrystallization annealing were completed, a clear ordered FCC (L1₂) phase was observed concurrently with the FCC matrix. In the alloy doped with 0.3 at.% B, the grain size was refined from 600 to 200 nm. TEM analysis revealed a nano-sized L1₂ phase coherently embedded in the FCC matrix. Analysis of the mechanical properties of boron-doped MEA samples revealed that cold rolling to 80% thickness followed by annealing at 900 °C for 2 h and aging at 750 °C for 4 h yielded the best mechanical performance. Among all samples, the alloy doped with 0.3 at.% boron achieved an optimal combination of mechanical properties (yield strength: 1817 MPa; ultimate tensile strength: 2313 MPa; ductility: 14.5%). Full article

This study compared the mechanical and thermal properties of new and retrieved multizone rhodium-coated superelastic nickel-titanium (NiTi) archwires across anterior and posterior segments. Using three-point bending tests, Scanning Electron Microscopy with Energy-Dispersive Spectroscopy analysis, and multiple linear regression, it was found that the posterior segments of new wires generated forces 0.50–0.80 N higher than those of anterior or retrieved specimens. While anterior segments exhibited higher austenite start and finish temperatures (by 6.15 °C and 5.21 °C, respectively) compared to posterior segments, these temperatures remained below average intraoral levels, and clinical retrieval did not significantly alter transformation temperatures. However, retrieved wires produced lower overall forces, likely due to surface cracking identified through microscopy. Ultimately, while posterior segments consistently generate higher forces than anterior segments, the observed reduction in force over time and the risk of surface degradation led to the conclusion that these archwires are not recommended for tooth movements exceeding 2 mm. Full article

This study evaluated changes in the number of cycles to fracture (NCF) of Nickel–Titanium (NiTi) files after repeated use in simulated canals and investigated the potential relationship with stress-induced martensite (SIM) transformation effect. A total of 225 ProTaper Ultimate (PTUL) files were divided into three groups: Group 1 consisted of new files, Group 2 comprised files used to shape two resin simulated canals, and Group 3 consisted of files used to shape four canals. The simulated resin canals with a 16 mm length of J-shaped with 35° curvature were prepared using PTUL Slider, Shaper, F1, F2, and F3 files sequentially. After instrumentation, the cyclic fatigue resistance of each sequential file was assessed in a 35° curved steel canal by rotating at 400 rpm using a custom-made device. Statistical analysis was performed using one-way ANOVA with Tukey’s post hoc test or Kruskal–Wallis with Dunn’s test with Bonferroni correction for parametric and non-parametric data, respectively. Slider and Shaper maintained stable NCF across all groups (p > 0.05). In contrast, F1 showed a transient increase (117.7%) after two uses but declined significantly (91.6%) after four uses (p < 0.05). F2 and F3 demonstrated progressive NCF reductions (F2: 72.9%; F3: 71.5% after four uses), with F3 showing the most pronounced decline (p < 0.05). Repeated use of NiTi files reduced their cyclic fatigue resistance in a file-specific manner, with larger finishing files most affected. The distinctive F1 pattern suggests potential preload-related or SIM transformation effects that warrant further metallurgical investigation. Full article