Search Results (10,568)

Microsegregation in cast materials is important to their solidification, solid-state transformation, microstructure and material properties. This work studies quantitatively the microsegregation of Si, Mn, Cu, Sn, and P in graphitic cast irons using an electron microprobe with wavelength dispersive spectrometry. The alloys contain [mass%] C: 3.86, Si: 2.59, Mn: 0.64, P: 0.03, S: 0.01, Sn: 0.098, Cu: 0.84, Mg: 0.065, include graphite morphologies ranging from ductile iron to compacted graphite iron and solidified with a solidification time of 10 min. Concentration maps are presented, showing that microsegregation patterns provide detailed information about the solidification chronology of the metal matrix. Sequencing the measurements into concentration profiles showed that, despite large differences in microstructure and cooling curve characteristics, the severity of microsegregation was similar in the studied materials. Scheil simulation of concentration profiles provided decent prediction of concentration profiles, given appropriate thermodynamic data. Numerical simulation of isothermal diffusion suggested that, for about 10 min of solidification time, diffusion in austenite mainly affected the last 10% of the matrix to freeze. Effective partition coefficients extracted from the concentration profiles varied slightly through solidification. The estimated mean effective partition coefficients for the first 90% of the alloy to freeze are ${\overline{k}}_{Si}^{\gamma /L}=1.124\pm 0.006$, ${\overline{k}}_{Mn}^{\gamma /L}=0.696\pm 0.008$, ${\overline{k}}_P^{\gamma /L}=0.15\pm 0.03$, ${\overline{k}}_{Sn}^{\gamma /L}=0.50\pm 0.02$, ${\overline{k}}_{Cu}^{\gamma /L}=1.35\pm 0.01$, where $\pm$ indicates standard deviation. Full article

The steel industry is currently grappling with the dual environmental challenges of massive steel slag accumulation and carbon emissions. To address the limitations of traditional carbonation processes—namely slow reaction kinetics and insufficient mechanical properties—this study proposes a novel rapid carbonation enhancement method coupling microwave thermal field intensification, silicon carbide (SiC) physical absorption, and potassium silicate chemical activation. The effects of microwave heating parameters on the performance of carbonated steel slag blocks were systematically investigated. The results indicate a significant synergistic effect between the microwave thermal effect and the alkali-activated system. Under the conditions of a 0.14 liquid-to-solid ratio and microwave heating at 90 °C for 45 min, the compressive strength reached a peak of 48.82 MPa (a 44.7% increase over the conventional treatment group). Microstructural characterization revealed the reinforcement mechanism: the introduction of SiC and potassium silicate solution (K₂SiO₃) under microwave heating promotes a denser distribution of carbonation products. Synchronized with alkali activation, this effect promotes the in-situ growth of dense calcite crystals within a gel network, thereby significantly optimizing the pore structure (e.g., reducing the average pore size to 43 nm), and enhancing strength through synergistic effects. This research is subject to further energy and life-cycle assessments, and this approach holds potential for CO₂ mineralization and the recycling of steel slag. Full article

Precision glass molding is an economical and resource-efficient method for manufacturing precision optics in a replicative way, offering advantages over conventional manufacturing methods, particularly for complex geometries. However, challenges arise due to different thermal expansion coefficients between the mold and the glass, which lead to shape deviations during the cooling process and require high compensation efforts. This study investigates the machining behavior during ultra-precision grinding of an innovative MAX phase composite whose coefficient of thermal expansion can be specifically adapted to that of glass. The aim is to evaluate the influences of varying process parameters and material configurations on surface integrity and the suitability of ultra-precision grinding for mold manufacturing in the context of precision glass molding. Systematic grinding tests were carried out and complemented by force measurements. The resulting surfaces were characterized using optical measurement technology and atomic force microscopy; in addition, the edge zone was analyzed using transmission electron microscopy. The results confirm the basic suitability of ultra-precision grinding for the MAX phase composite but point to potential subsurface damage that could limit its usability in precision glass molding. Full article

This study (Part B) examines the potential utilization of municipal solid waste (MSW) ash, produced in a semi-industrial incinerator in Israel, as a partial substitute for cement and natural sand in industrial concrete mixtures. The ash was produced at the temperature range 600–850 °C, and the ash was characterized using XRD and SEM to determine its mineralogical composition and morphology. The results indicate that ash composition is dominated by calcium-rich phases, with hatrurite (Ca₃SiO₅) representing approximately 51–66 wt.% of the identified crystalline phases, along with calcite, MgO, and silica phases. The ash consists of irregular, porous particles with a broad distribution. Concrete performance was evaluated in both fresh and hardened states. In terms of fresh concrete properties, it is observed that concrete containing ash showed improved workability, better workability retention, and better concrete density compared to concrete without ash. In terms of hardened concrete properties, the use of MSW ash as a partial sand replacement preserved the mechanical performance of the concrete, with compressive strength remaining within approximately 2% of the reference mixture. These findings suggest that semi-industrially produced MSW ash is more suitable as a fine aggregate replacement than as a supplementary cementitious material and represents a promising route for reducing landfill disposal and promoting circular economy practices in the construction industry. Full article

Magnesium ammonium phosphate cement (MAPC) exhibits rapid setting, high early strength, and potential resistance to elevated temperatures, making it a promising material for rapid repair and fire-resistant applications. Gold tailings (GT), which contain thermally stable Si- and Al-rich components, show potential for improving the high-temperature performance of MAPC. However, the mechanisms by which GT affects the residual performance and phase evolution of MAPC after exposure to elevated temperatures remain insufficiently understood. In this study, GT was used to replace the total binder in MAPC mortar at mass replacement levels of 0%, 10%, 20%, and 30%, while the MgO/NH₄H₂PO₄ mass ratio in the remaining binder was kept constant. The effects of GT content on the workability of MAPC mortar, as well as its visual appearance, mechanical properties, mass loss rate, phase evolution, and microstructure after exposure to elevated temperatures, were investigated. The results showed that GT incorporation shortened the setting time and reduced the fluidity and room-temperature strength. After exposure to elevated temperatures, the GT-containing specimens exhibited higher strength retention and lower mass loss rates. After exposure to 1000 °C, the compressive strength of the specimen containing 30% GT reached 15.37 MPa, which was approximately 44.0% higher than that of the specimen without GT. Its flexural strength retention and mass loss rate were 47.42% and 9.84%, respectively. XRD and SEM results indicated that the formation of high-temperature residual phases, including Mg₃(PO₄)₂, Mg₂SiO₄, and aluminosilicates, may contribute to the improvement of the residual matrix structure after exposure to elevated temperatures. Overall, GT incorporation improved the residual mechanical properties of MAPC after exposure to elevated temperatures, and the specimen containing 30% GT showed comparatively superior performance within the experimental scope of this study. These findings provide a reference for the resource utilization of GT in MAPC-based heat-resistant repair materials. Full article

An Al₂O₃/AlN stack deposited via Atomic Layer Deposition (ALD) methods as a gate insulator for silicon carbide (4H-SiC) has been investigated, focusing on the effects of different Al₂O₃ deposition processes on the nitride layer. In particular, dielectric stacks, consisting of a 10 nm AlN interface (001)-oriented layer directly grown on a 4H–SiC substrate and in 20 nm of additional amorphous Al₂O₃ layers were synthesized in sequential deposition runs by thermal ALD (T-ALD) or plasma-enhanced ALD (PEALD) methods. The evolution of the phenomena occurring at the Al₂O₃/AlN interfaces has been established by in situ ellipsometry measurements. Strong effects of the oxygen plasma because of the O-Al-N bond formation have been clearly observed and corroborated by ex situ structural and electrical characterizations, especially in the case of the plasma-enhanced Al₂O₃ process. In particular, the Al₂O₃/AlN bilayer grown by the Al₂O₃ T-ALD method exhibited good insulating behavior and an 8.7-high dielectric constant was measured. By contrast, the Al₂O₃/AlN bilayer grown by the Al₂O₃ PEALD method demonstrated poor insulating properties. Full article

Agrivoltaic systems, which enable simultaneous crop production and solar photovoltaic (PV) electricity generation on the same land, can support climate mitigation, food security, and rural development. Leguminous crops like beans are globally important, yet there is limited performance studies on diverse agrivoltaic trials. This limits appropriate policy guidance. To overcome these limitations, this study assessed organic green bush bean performance under thirteen PV configurations with varying transparency and spectral properties, comparing both agricultural outcomes against national yields and policy standards. The results in vegetative metrics indicated that blue-spectrum thin-film and intermediate-transparency c-Si modules supported growth near German productivity thresholds. Although no agrivoltaic system matched national average yields, combining crop and energy revenues revealed substantial benefits: the 44%—transparent c-Si configuration generated 340% more total revenue than traditional farming, and the blue 70%—transparent thin-film system achieved 94% of national yield but 164% of conventional farm revenue per acre. Electricity generation gains outweighed modest crop reductions, highlighting strong synergies between food and energy. The results of this study highlights the potential of agrivoltaic systems to enhance land-use efficiency, support renewable energy expansion, and improve rural economic resilience, while underscoring the need for multi-year trials and site-specific controls to validate long-term sustainability outcomes. Full article

Retroviruses, after their genomes are integrated into the host genome, replicate through host cell replication. In this hitchhiking phase, their only way of increasing their fitness is to encourage the host cell to have unregulated, rapid cell replication. The v-Src gene in avian sarcoma virus and the v-sis gene in the simian sarcoma virus were originally mined from the host genome by the virus to increase host cell replication rate, with the corresponding host cellular counterparts c-Src (non-receptor tyrosine kinase) and c-sis (platelet-derived growth factor). The resulting out-of-control replication ultimately would lead to cancer. The battle between the host and the retroviruses left many retroviral corpses known as endogenous retroviruses, and the host occasionally domesticates retroviral genes. The syncytins (whose fusogenic function is crucial for the trophoblast fusion and the formation of a syncytium during placenta morphogenesis) and suppressyn (which serves the dual function of regulating syncytialization and host resistance against retroviruses) are examples of successful domestication. Syncytin-1 and suppressyn have each been “domesticated” independently multiple times by different mammalian lineages. Molecular phylogenetics is an essential tool for tracing the evolutionary trajectories of such genetic exchanges between retroviruses and their hosts and for determining the direction of the genetic exchange. Full article

Asymmetric SiC membranes with surface pore sizes ranging from 0.12 to 0.31 μm at a constant open porosity of approximately 42% were fabricated by dip-coating SiC support followed by sintering from 1700 to 2000 °C. The effect of membrane structural constants (hydraulic resistance (k₁), pore size exponent (k₂), and shape factor (k₃)) on PWP were evaluated by comparing the symmetric and asymmetric structures. In addition, the experimentally determined values of PWP were quantitatively analyzed by comparing with theoretically predicted values obtained using the Kozeny–Carman (K–C) and Hagen–Poiseuille (H–P) models. Despite having a smaller pore size, the asymmetric membranes exhibited high PWP (1257-3883 LMH) due to decreased flow resistance (low k₁), enhanced pore size effect (high k₂), and improved flow network (high k₃) as compared to symmetric membranes. The hydrophilicity of the prepared membranes improved remarkably, with increasing average surface roughness (102.3 nm to 161.0 nm) due to an increase in pore size, which also caused a decrease in water contact angle (WCA) from approximately 27.44° to 21.67° with increasing sintering temperature (1700–2000 °C). Furthermore, the prepared membrane separation performance was found to be affected by its pore size, and the 1900 °C sintered SiC membrane showed optimal gradient profile and pore structure, demonstrating its practical reusability and scalability for O/W wastewater treatment. Full article

Heat-treatable aluminum alloys are widely used in aerospace and automotive industries for high-performance structural applications. However, their processing through conventional fusion-based additive manufacturing is limited by solidification-related defects, such as hot cracking, porosity, and elemental segregation. To overcome these limitations, friction-based additive manufacturing (FBAM) has emerged as a promising solid-state alternative. FBAM primarily includes friction stir additive manufacturing (FSAM), additive friction stir deposition (AFSD), friction screw extrusion additive manufacturing (FSEAM), and friction rolling additive manufacturing (FRAM), which differ in feedstock form and process configuration. In these processes, feed material is consolidated through frictional heat generated below the melting temperature, enabling the formation of refined equiaxed microstructures while minimizing solidification defects. Despite these advantages, significant challenges persist in processing heat-treatable aluminum alloys, particularly the 2xxx, 6xxx, and 7xxx series. These include non-uniform microstructure and mechanical properties along the build direction; precipitation instability; process-induced defects, such as tunnel formation; and mechanical properties that are often inferior to those of the corresponding base materials (BMs). Reported FBAM builds generally exhibit equiaxed ultrafine grains below 1 μm; however, the strength and microhardness of heat-treated alloy builds commonly remain around 70–75% of the corresponding BM. Following post-heat treatment, microhardness can be nearly fully recovered, whereas UTS typically reaches about 80–85% of BMs, often with an associated ductility reduction of nearly 50%. This review critically analyzes research reported over the past decade on FBAM processing of heat-treatable aluminum alloys, covering FSAM, AFSD, FSEAM, and FRAM. The key challenges related to microstructural evolution and mechanical performance are systematically discussed for each alloy series. Furthermore, mitigation strategies proposed in the literature, including process parameter optimization, in-process cooling, post-heat treatment, and nanoparticle reinforcement (e.g., SiC, TiC, Ni and ZrO₂), are evaluated. Finally, existing research gaps are identified, and future directions are proposed to support the development of robust, scalable, and high-performance FBAM processes for heat-treatable aluminum alloys. Full article

Interleukin-13 receptor α2 (IL-13Rα2) has traditionally been considered a decoy receptor; however, its cellular functions beyond the immune system remain unclear. We aimed to investigate the role of IL-13Rα2 in C2C12 myoblast proliferation and differentiation. IL-13Rα2 expression was knocked down in C2C12 cells using siRNA. Myogenic differentiation was evaluated by myosin heavy chain (MyHC) immunostaining and by quantifying the expression of myogenic regulatory and fusion-related genes. Myoblast proliferation was assessed using BrdU incorporation and cell number analyses, and signaling events induced by IL-13Rα2 knockdown were analyzed via immunoblotting and immunocytochemical analysis. IL-13Rα2 knockdown did not alter myogenic differentiation or the expression of fusion-associated genes. In contrast, IL-13Rα2 knockdown significantly increased BrdU incorporation and cell number, accompanied by increased Akt phosphorylation and decreased ERK phosphorylation. Cyclin D1 and cyclin-dependent kinase 4 (CDK4) levels were also increased. Akt inhibition abolished the enhanced proliferation and normalized Cyclin D1/CDK4 levels, whereas ERK activation did not further modify the knockdown-associated phenotype. These findings demonstrate that IL-13Rα2 negatively regulates myoblast proliferation by modulating the Akt–Cyclin D1–CDK4 signaling pathway, while being dispensable for myogenic differentiation. Full article

The valorization of phosphogypsum (PG), a byproduct of phosphoric acid production, along with waste glass (WG) and silica fume (SF) into value-added materials has attracted growing attention in recent years. The present study aims to synthesize three types of porous geopolymers (GD, GDP, and GDG) using Tunisian clay and locally available mineral wastes, and to investigate their potential as low-cost adsorbents for the removal of methylene blue (MB) dye from aqueous solutions. The physicochemical characteristics of the raw precursors and the resulting porous geopolymers were analyzed using various techniques, including FTIR, XRD, BET, and SEM. Variations in Si/Al, Na/Al, and Ca/Al ratios play a critical role in the geopolymer structure. The high Ca/Al ratio in GDP (porous geopolymer from calcined clay and phosphogypsum) promotes the formation of C-A-S-H, leading to increased macroporosity, which favors adsorption capacity despite the presence of a more heterogeneous morphology. The results indicated that the maximum adsorption capacity (Qmax) for MB dye was obtained for the GDP sample, reaching 68 mg/g. Adsorption experiments revealed the successful removal of MB dye by geopolymers, with the Langmuir isotherm and pseudo-second-order kinetic models adequately describing the adsorption process. The MB uptake by geopolymers was facilitated by weak physicochemical interactions, including electrostatic attraction, hydrogen bonding, and π–π interactions. This study proposes a simple and effective alkali activation strategy that combines different industrial wastes within a single geopolymer system, resulting in improved porosity and adsorption efficiency. Overall, the findings highlight the potential of these waste-derived geopolymers as promising and sustainable adsorbents for wastewater treatment applications. Full article

To investigate the impact of underground multiple stress disturbances on the long-term stability of cemented tailings backfill (CTB), this study conducted experiments under different disturbance levels (20–80% of static strength) and frequencies (1–4 times). By comprehensively utilizing mechanical testing, wave velocity monitoring, digital image correlation (DIC), and scanning electron microscopy (SEM), the “heterogeneous” evolution mechanism of macro-micro damage was revealed. The results indicate that disturbance level and frequency exert distinctly different driving effects on the deterioration of CTB, rather than a simple linear superposition. Specifically, low-frequency disturbance produces a compaction strengthening effect, microscopically promoting the generation of Ca(OH)₂ and ettringite (increased Ca/Si ratio). In contrast, the combination of high disturbance and high frequency induces free water extrusion and inhibits hydration, leading to an advanced damage threshold based on energy evolution and the accelerated coalescence of microcracks, which favors the formation of C-S-H gel (decreased Ca/Si ratio). Within this heterogeneous mechanism, the disturbance level acts as the dominant controlling factor. This study clarifies the nonlinear mechanical and chemical evolution paths under composite disturbances, providing theoretical support for the dynamic stability control of backfill in deep multi-step mining. Full article

A novel sodium-oxide-fluxed slag is applied in the aluminothermic reduction of manganese ore. The slag’s high Al₂O₃ solubility facilitates the recycling of Al₂O₃ through hydrometallurgical processes, where NaAlO₂ serves as a water-leachable compound. Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. In addition, CO₂ emissions in aluminium production via the electrochemical Hall–Héroult process can be reduced if the process electricity is sourced from non-fossil fuels. The unique Na₂O-fluxed MnO₂ ore formulation includes a small quantity of carbon reductant to ensure rapid pre-reduction to MnO. This approach negates the need for a pre-roasting step. Feed mixture variations with different collector metal additions (Si, Cr, Cu) were made to improve alloy–slag separation efficiency. The collector metals may influence the chemistry of the slag. This work compares the phase chemistry of slags formed during aluminothermic reduction to equilibrium phase chemistries calculated for the Na₂O-SiO₂-Al₂O₃-MnO-CaO system. The slag phase morphology consists of distinct alumina-rich strands (1.5% to 2.1%) embedded within a Na₂O-SiO₂-Al₂O₃-MnO-CaO glass matrix. The alumina-rich strands appear molten, indicating that the processing temperatures were higher than their liquidus temperatures (1537 °C to 1655 °C), as high as 1921 °C and 2053 °C. These findings contribute to sustainable practices in the circular economy through the production of low-carbon ferro-manganese complex alloys. Full article

Carbon nanotube (CNT)-reinforced composites are promising advanced materials due to their exceptional mechanical properties. This paper presents a comprehensive investigation of the mechanical behavior of CNT/epoxy composites through theoretical modeling and experimental validation. An equivalent cylindrical fiber model was developed to transform CNTs into effective reinforcement phases, enabling the application of classical composite mechanics. Three reinforcement configurations were analyzed: two unidirectional short fiber models (aligned and staggered) and a three-dimensional four-directional braided long-fiber model. The effects of geometric parameters, including the diameter-to-thickness ratio (D/t) and fiber aspect ratio, on the effective elastic moduli were systematically evaluated. Static and dynamic compression experiments were conducted using an MTS 810 testing system and a Split Hopkinson Pressure Bar (SHPB) to examine the influence of loading rate, vacuum treatment, and reinforcement type (CNT, SiC, and hybrid SiC/CNT) on composite strength. The results indicated that 3 wt% CNT reinforcement increases the Young’s modulus by 30% under static loading and enhanced the dynamic compressive strength under impact loading. The vacuum degassing process significantly affected composite quality, with insufficient vacuum leading to strength degradation due to void formation. Theoretical predictions using Mori–Tanaka and dilute methods showed good agreement with experimental results at low reinforcement volume fractions. Scanning electron microscopy revealed uniform CNT dispersion and provided insights into failure mechanisms, including CNT pull-out and breakage. This work contributes to the understanding of structure–property relationships in CNT-reinforced polymer composites and provides guidelines for achieving their optimal design. Full article