Search Results (22,983)

Self-sustained metal aerogels are emerging as advanced porous materials with a 3D network of nanostructures that are exclusively made of metals. Metal aerogels possess a distinctive combination of metallic nanoparticles with excellent electronic conductivity, and the excellent porosity of the aerogels allows the extensive exposure of electrocatalytic active sites, together with remarkable mass transport networks in a single entity, unlocking widespread application potential ranging from energy storage and conversion to environmental remediation. In this review, we systematically examine the potential of metal aerogels as electrocatalysts for ethanol electro-oxidation. Various synthesis routes, structure–property relationships, and their function as anode electrocatalysts have been critically reviewed. Due to their 3D porous metallic nature, noble metal aerogel catalysts were found to exhibit excellent ethanol oxidation currents, anti-poisoning for reaction intermediates, high mass, and specific activities of 5–20 times those of traditional Pd/C catalysts. In conclusion, it is shown that metal aerogel catalysts exhibit enhanced activity for ethanol electro-oxidation currents over traditional Pd/C catalysts. Despite this, several challenges exist in realizing the commercial applications of metal aerogels, which have been clearly and elaborately stated as future perspectives and research directions in the field of metal aerogel electrocatalysis. Full article

The promising potential of porous metallic materials for railway applications (e.g., conductive materials, materials for braking systems) is due to their unique combination of low density, high specific surface area, and high energy absorption capabilities. Porous multi-phase silicide coatings (FeSi, Si₂CN₄) provide a synergistic effect, doubling surface hardness and establishing a stable diffusion barrier. The article proposes a comprehensive approach to replacing materials for critical railway transport components, involving the development of a base material and a barrier coating. The use of widely available induction-melting components to produce a base material with superior mechanical properties is demonstrated. The material exhibits high static strength and hardness while maintaining acceptable impact toughness and ductility. To enhance wear, corrosion, and scale resistance, technology for forming a barrier layer via silicide coatings is proposed. The coating formation technology enables the regulation of porosity through the formation of nitrogen-containing phases. It is shown that pores can serve as “containers” for fillers that impart functional properties to the coatings (e.g., adjusting the friction coefficient or electrical conductivity). The new base material–barrier coating system can serve as a foundation for the sustainable production of critical rolling stock parts and other devices for railway transportation systems. Full article

Global water pollution driven by industrial and agricultural expansion has resulted in the widespread occurrence of persistent contaminants, particularly pharmaceuticals and heavy metals, in groundwater systems. Conventional treatment methods often prove inefficient, costly, and environmentally unsustainable, highlighting the need for innovative in situ remediation technologies. Permeable Reactive Barriers (PRBs) have emerged as a promising and energy-efficient solution for the long-term purification of contaminated aquifers. Their efficiency arises from passive operation, relying on natural groundwater flow to promote pollutant removal through adsorption, ion exchange, precipitation, and redox-driven transformations. This review emphasizes the superior performance of materials such as Activated Carbon, Biochar, Zeolites, and Zero-Valent Iron (ZVI) in the immobilization and reduction in pharmaceuticals and metal ions. Key challenges to PRB longevity include permeability loss and reactive media depletion due to mineral precipitation and biofouling. Advances in hybrid PRB configurations, coupled with electrokinetic (EK) and bioreactor systems, and predictive modeling, particularly Artificial Neural Networks (ANNs), offer pathways to enhance performance, optimize design, and ensure sustainable operation. Overall, PRBs represent a scalable and environmentally sound approach to groundwater remediation, with future progress relying on the development of multifunctional, regenerable materials and integrated design strategies. Full article

Titanium-based perovskites have garnered significant attention for photocatalytic applications, particularly in the field of environmental remediation through the degradation of synthetic dyes and pharmaceuticals in aqueous solutions. This review paper aims to explore the synthesis methods, crystal structures, photoactivity, and photocatalytic performance of titanium-based perovskites in degrading synthetic dye and pharmaceutical effluents in water. The unique advantages of titanium-based perovskites as photocatalysts, associated with their high redox potentials and excellent optical and electrical properties, are highlighted. Their limitations in visible light absorption and photocatalytic efficiency due to rapid charge carrier recombination are also discussed. Several strategies to overcome these limitations, such as surface modifications of the photocatalysts, metal and non-metal doping, the introduction of structure defects, the formation of heterojunctions with electron-accepting materials, and the deposition of plasmonic metal nanoparticles are systematically examined. This review also provides an overview of the photocatalytic degradation of dyes and pharmaceuticals as emerging contaminants, utilizing titanium-based perovskites as photocatalysts, to highlight their efficiency and potential for real-word applications. By covering research findings, current knowledge, and future perspectives, this review aims to stimulate advancements in the design and application of titanium-based perovskite photocatalysts. Full article

O3-type layered transition-metal oxides are widely regarded as promising cathode materials for sodium-ion batteries due to their intrinsically high sodium content and favorable energy density. Nevertheless, their practical rate capability is hindered by sluggish Na⁺ transport and relatively high diffusion barriers. To address this issue, elemental substitution has emerged as an effective modification strategy. In this work, fluorine (F), characterized by strong electronegativity and a small ionic radius, is introduced to partially substitute oxygen in the bulk lattice of O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ (NNFM). First-principles calculations demonstrate that F incorporation leads to an expansion of the interlayer spacing along the c-axis and a weakening of Na–O interactions, both of which facilitate Na⁺ migration. Among the considered configurations, Mn-adjacent substitution exhibits the lowest formation energy, indicating enhanced thermodynamic stability. Furthermore, electronic structure analysis reveals a reduced band gap (from 0.515 eV to 0.342–0.356 eV) and strengthened O-2p/Mn-3d orbital hybridization, contributing to improved electronic conductivity. These findings provide atomistic insights into F-induced modulation mechanisms and suggest an effective pathway for optimizing Na⁺ transport in O3-type cathodes. Full article

Decarbonizing maritime transport requires hydrogen storage technologies that are efficient, safe, and compatible with fuel cell systems. This study evaluates three hydrogen storage technologies (compressed hydrogen (CH₂), liquid hydrogen (LH₂), and metal hydrides (MH)) based on five key criteria: safety, autonomy, environmental impact, cost, and implementation feasibility. Applying two multi-criteria decision-making (MCDM) methods, Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), the alternatives are systematically ranked to identify the most suitable option. Both methods consistently highlight compressed hydrogen as the most viable storage solution, offering a good balance of safety, infrastructure maturity, and economic performance. Liquid hydrogen, despite its superior autonomy, is limited by high energy and infrastructure costs. Metal hydrides, although safer and more compact in terms of volumetric density, are limited by low gravimetric efficiency at the system level due to the additional weight of the storage material and associated components. Full article

Processing of nickel ores is a key aspect of modern metallurgy due to the growing demand for nickel in stainless steel, battery production, and advanced materials. The depletion of high-grade sulfide ores has shifted attention toward oxidized (lateritic) nickel ores, which are characterized by complex mineralogy and low metal content. This study presents a comparative review of major processing technologies, including pyrometallurgical, hydrometallurgical, and hybrid approaches, with particular emphasis on their applicability to Kazakhstan’s limonitic laterites with high iron and low nickel content. The analysis shows that the most suitable processing routes for such ores include atmospheric acid leaching (AL), high-pressure acid leaching (HPAL), metallothermic reduction, and combined flowsheets integrating thermal and leaching stages. Among these, AL and hybrid approaches are identified as the most promising under resource-constrained conditions. Despite recent technological progress, challenges remain related to energy consumption, economic feasibility, and environmental impact. The study highlights the importance of developing energy-efficient and low-carbon technologies, including hydrogen-based reduction, and provides practical recommendations for selecting and adapting processing methods for Kazakhstan. Full article

The continuous research progress in materials science has enabled the development of advanced nano-materials, including carbon nano-tubes, graphene and metal oxides with specialized properties, which can fundamentally affect the mechanical, thermal and tribological properties of conventional materials when used in the reinforcing phase [...] Full article

With the growing demand for strategic metals and the gradual depletion of traditional metal ore deposits, coal and coal-bearing strata are regarded as potential sources of rare metals; consequently, research into the characteristics of associated elements in coal-bearing strata has become one of the primary avenues of searching for new alternative resources. To investigate the sedimentary environmental characteristics and controlling factors of the coal-bearing strata along the southern margin of the Junggar Basin, coal seams 9–15 of the Xishanyao Formation in Sulphur Gully (Early Middle Jurassic) were selected as the subject of this study. This study employed analytical techniques including industrial analysis, total sulphur analysis, X-ray powder diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to determine the mineralogical and elemental geochemical characteristics of coal samples from Seylangou mining area, specifically from coal seams 9–15 and their overlying and underlying strata. Based on analyses of elemental ratios such as Al₂O₃/TiO₂, Sr/Ba, Rb/Sr, Ni/Co and V/(Ni + V), the source of material during the deposition of this deposit was identified, and the characteristics of the depositional environment, as indicated by palaeosalinity, palaeoclimate and redox conditions, were revealed. The results indicate that the macroscopic coal-rock types of coal seams 9–15 at the Sulphur Gully Coal Mine on the southern margin of the Junggar Basin are predominantly semi-dull to dull, with small amounts of filamentous coal and lustrous coal. The average proportion of the vitrinite group in the coal is 42.75%, the inertinite group is 51.40%, and the liptinite is 2.25%. The average content of inorganic matter in the coal is 3.60%, and the average maximum reflectance of the vitrinite group is 0.651%. The coal represents a transitional stage from low-rank to medium-rank coal, corresponding to a metamorphic stage of Grade I–II. The coal is classified as a bituminous coal with medium total moisture, very low ash, medium-volatile matter, medium-to-high fixed carbon and very low sulphur. The minerals in the coal seam are predominantly kaolinite, calcite and quartz. The major elements in the ceiling of the coal seam are dominated by SiO₂, followed by Al₂O₃; the coal itself is dominated by CaO, SiO₂ and Al₂O₃; and the base plate of the coal seam is dominated by Al₂O₃. The trace elements Cs and Bi are relatively enriched in the coal seam ceiling; Sr is relatively enriched in the coal; whilst Li, Cr and other elements are highly enriched in the coal seam base plate. The source rocks of the coal and the roof consist of deposits of felsic igneous rock (dacite), whilst the source rocks of the floor consist of deposits of intermediate igneous rock (andesite). The depositional environment ranges from marine brackish water at the base to transitional slightly brackish water and then to terrestrial freshwater at the top; the depositional climate was cold and arid, and the depositional environment was oxidising. This study provides valuable insights for further research into the elemental geochemical characteristics, sediment sources and depositional environments of the Xishanyao Formation coal seams in Liuhuangou, Xinjiang. Full article

This study investigates the enhancement of AA6082/Al₂O₃ aluminum metal matrix nanocomposites (AMMNCs) through powder metallurgy combined with systematic process optimization. Ultrasound-assisted dispersion and Taguchi design L9 orthogonal array were employed to improve nanoparticle distribution and optimize fabrication parameters. The effect of Al₂O₃ content and ultrasonication time (UT) on hardness and compressive strength was analyzed using S/N ratio and ANOVA. Characterization was performed using X-ray Diffraction (XRD) and scanning electron microscopy (SEM). The result shows that Al₂O₃ content had the most significant influence on both hardness (82.25%) and compressive strength (81.08%), followed by UT. The optimal condition produced a maximum hardness of 31.9 HV and compressive strength of 205.53 MPa. Regression models demonstrated strong predictive accuracy (R² > 85%). Overall, the study highlights the effectiveness of parameter optimization in improving nanocomposite performance and provides valuable guidance for advanced material design. Full article

Innovations in nanomaterial science, engineering and printing technologies have increasingly driven advances in electrochemical sensing. Screen-printed electrodes (SPEs) have become a versatile, low-cost, and scalable solution for developing portable electrochemical detection platforms. However, their analytical performance remains intrinsically limited by surface area, electron transfer efficiency, and the immobilization of biomolecules. Recent developments in nanostructured materials, ranging from two-dimensional (2D) materials such as graphene, MXenes, and transition metal dichalcogenides, to one-dimensional nanostructures and hybrid nanocomposites, have transformed the signal transduction landscape of SPE-based electrochemical sensors. Integration of nanomaterials into SPEs has successfully transformed their analytical capabilities, but the diversity of materials and modification strategies has made it difficult to consolidate current knowledge in the field. Strategies that integrate nanomaterials via ink formulation, surface modification, or in situ growth have yielded sensors with unprecedented sensitivity, reproducibility, and selectivity across various chemical and biological targets. This review offers a cross-material synthesis of how nanomaterial engineering transforms the electrochemical performance of SPEs. By integrating insights across morphology, interfacial chemistry, and device-level behavior, it establishes a unified perspective that has been missing from the current literature and clarifies the design principles driving next-generation SPE-based sensing platforms. Full article

Healthcare-associated infections (HAIs) remain a significant global challenge, affecting approximately 7% of patients in developed countries and over 10% in developing regions, according to the World Health Organization. Medical textiles, particularly hospital bed linens and pillowcases, play a critical role in the transmission of pathogenic microorganisms due to their porous structure and moisture-retaining properties, which support microbial survival and proliferation, including bacteria such as Staphylococcus aureus and Escherichia coli. Conventional disinfection methods, including laundering and thermal treatments, provide only temporary protection, leading to rapid recontamination during use. In recent years, various antimicrobial agents and functionalization techniques have been developed to impart long-lasting antiseptic properties to textile materials. However, these approaches differ significantly in terms of antimicrobial efficiency, durability, cost-effectiveness, and environmental impact, making the selection of optimal strategies challenging for practical healthcare applications. This review provides a comprehensive comparative analysis of antimicrobial agents used in healthcare textile functionalization, including metal-based nanoparticles, organic compounds, and bio-based materials. In addition, it evaluates key modification methods such as coating, padding, and in situ synthesis, with particular emphasis on their influence on antimicrobial performance, wash durability, and practical applicability. Furthermore, this review discusses major challenges associated with the use of antiseptic coatings, including toxicity, environmental concerns, and economic limitations. Based on the analysis, promising directions for the development of safer, cost-effective, and durable antimicrobial textile systems are highlighted, offering valuable insights for future research and real-world healthcare applications. Full article

With the progressive decline of tailpipe emissions, non-exhaust sources such as brake wear are becoming an increasingly important contributor to traffic-related particulate matter in urban environments. In this context, improving real-world characterization of brake wear particles is essential for air-pollution assessment, source apportionment, and the development of cleaner and more sustainable road transport systems. Here, we investigated the emissions levels, particle size distribution and elemental composition of particles released during harsh real-world braking events by a single light-duty vehicle braking system equipped with an original manufacturer (OEM) non-asbestos organic (NAO) pad formulation. Using a direct on-vehicle sampling system combined with real-time particle sizing and high-resolution microscopy, we observed that particle emissions remained close to background levels at speeds up to 100 km/h, but rose sharply at 120 km/h, reaching 3.7 × 10⁷ #/cm³ in the 8–10 nm size range. This increase suggests that higher speeds are associated with elevated particle emissions, likely due to the higher braking temperatures reached at increased vehicle speeds. The emitted particles were mainly spherical agglomerates rich in iron, titanium, barium, zirconium, and sulphur, consistent with NAO pad formulations. Our results show that the investigated NAO pad system can deteriorate under thermal stress, potentially leading to higher levels of nanoparticle emissions compared to low-metallic or semi-metallic pads investigated under similar conditions. These findings provide real-world evidence relevant to urban air quality research, support the refinement of non-exhaust emissions inventories, and highlight the importance of thermally resilient friction-material formulations for mitigating residual particulate emissions in increasingly cleaner transport systems. Full article

The MnP family of binary compounds presents an intriguingly simple platform to mix-and-match elemental components. Replacement on the transition metal or pnictogen site can alter magnetism, electronic correlations, and electrical properties. Here we report low-temperature properties of CoP, including measurements at magnetic fields exceeding 30 T, revealing de Haas–van Alphen oscillations and a nearly two orders of magnitude increase in resistance. When viewed together with prior work, it is possible to put together a global picture of the role of different atoms in variations in magnetic ordering, lattice coherence, and topological band structure features in this material family. Full article

Tube boilers are extensively employed in oil and gas refineries, as well as in petroleum, energy, and power generation industries, where they serve critical functions in local steam-generation units and combined-cycle gas turbine (CCGT) plants. However, these boilers are prone to defects arising from waterside corrosion (e.g., thinning of U-bend tubes), fireside corrosion, and material degradation caused by stress or creeping. Among these issues, wall thinning of tube bends is particularly severe, as it results in localized metal loss, reduced structural integrity, and an elevated risk of tube rupture or failure under high-temperature and high-pressure operating conditions. Such failures can significantly compromise boiler safety and efficiency, potentially leading to forced outages, costly unplanned repairs, or catastrophic damage if not detected in time. The current condition-monitoring policy for U-bends relies on scheduled preventive maintenance and unscheduled corrective interventions. In practice, this involves randomly checking approximately 10–20% of the tubes through spot scanning, partial scanning, or full scanning, with repairs typically carried out only after an undetected failure occurs. Such maintenance strategies generally require plant shutdowns, making the process time-consuming, labor-intensive, and ultimately not cost-effective. This paper reviews existing solutions, technologies, and research addressing the problem, and introduces femtosecond laser micromachined fiber optic sensors as a transformative approach for real-time monitoring of wall thickness reduction in U-bend boiler tubes, thereby opening pathways for further research. Full article