Search Results (7,191)

This research investigates the formation of an amorphous phase in a non-equiatomic aluminum-based alloy, Al₈₂Fe₁₂Cu₂Nb₂Co₂, synthesized via mechanical alloying. By utilizing minor additions of Nb, Co, and Cu, structural stability and “chemical complexity” effects are achieved in a matrix dominated by a single element (82% Al). Thermodynamic analysis reveals that a moderately negative mixing enthalpy (ΔHₘᵢₓ = −6.89 kJ/mol) and elevated configurational entropy (ΔSₘᵢₓ = 5.420 J/mol·K) are the primary thermodynamic drivers of amorphization, supplemented by a transitional-regime atomic size mismatch (δ = 4.82%). The evolution of the structure, morphology, and magnetic properties of mechanically alloyed amorphous Al₈₂Fe₁₂Cu₂Nb₂Co₂ as a function of milling time was systematically investigated using X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and a vibrating sample magnetometer. Full article

This study investigates the influence of various manganese sources—specifically MnCO₃, Mn₃O₄, and MnO₂—on the performance of lithium manganese iron phosphate (LMFP) synthesized through a combined spray-drying and chemical vapor deposition (CVD) strategy. The synthesis protocol involved the initial formation of a precursor through the co-sintering of manganese, phosphorus, iron, and dopant sources via CVD, followed by secondary spray-drying and carbon thermal reduction with Li₂CO₃ and carbon additives. Morphological analysis via Scanning Electron Microscopy (SEM) and laser diffraction indicates that Mn₃O₄-derived LMFP possesses highly spherical secondary structures comprising well-crystallized, uniformly distributed primary particles. Elemental mapping via Energy Dispersive Spectroscopy (EDS) confirms a homogeneous distribution of stoichiometric elements without localized segregation, alongside the successful lattice integration of dopants. In contrast, the MnCO₃-derived samples exhibited deleterious carbon accumulation on the primary particle surfaces. Consequently, the Mn₃O₄-based LMFP demonstrated superior electrochemical kinetics, delivering a remarkable initial discharge capacity of 148.9 mAh g⁻¹ at 1C, with an exceptional capacity retention of 97.9% after 100 cycles. These findings underscore the critical role of precursor selection in optimizing the interfacial and bulk properties of high-performance LMFP cathodes. Full article

To address the slow curing and low early strength of conventional modified epoxy emulsified asphalt repair materials, this study introduced steel slag aggregate into epoxy emulsified asphalt mixtures. Experimental techniques including heat absorption–heat transfer rate tests, Marshall stability tests, COMSOL numerical simulation, and scanning electron microscopy (SEM) were adopted to analyze rapid and uniform heating under microwave radiation. The influence of steel slag’s chemical composition, content, and particle size on epoxy curing, asphalt demulsification, and early strength of the mixture was systematically examined. Results show that steel slag containing Fe and Mg elements exhibits higher microwave absorption efficiency. When its content exceeds 15%, the heating rate increases by approximately 0.335 °C/s under the tested conditions. Particles sized 0.6~2.36 mm show better wavelength matching with the applied microwave frequency (2.45 GHz), thereby enhancing absorption. After 140 s of microwave radiation, the core temperature of the mixture reaches 110 °C, which is the appropriate temperature to achieve rapid epoxy curing and synchronous asphalt demulsification. These two processes synergistically form a continuous network structure, thereby improving the compactness and initial laboratory Marshall stability of the mixture. Nevertheless, this study has several limitations. The microwave absorption efficiency depends strongly on the specific mineralogy and Fe/Mg content of steel slag, both of which may vary with source. The conclusions are based on laboratory-scale tests under fixed microwave power and mixture proportions. Despite these limitations, the results demonstrate that steel slag can serve as an effective microwave-absorbing component in epoxy emulsified asphalt mixtures, enabling rapid curing and demulsification to accelerate early strength development. Full article

Although species identification is crucial for land-snail eggs, limited effort has been made to identify the species responsible for producing the eggs. In this study, we used laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) to measure 54 elements in both the eggshells and adult shells of Bradybaena ravida and Cathaica fasciola and we used scanning electron microscope (SEM) to analyze the microstructure of the eggshells of the two species. Our results reveal that while the concentrations of Sr, Na, Mg, P, and Ba in the adult shells of the two species are not distinct, they are distinct or partially distinct between their eggshells, indicating that these elements have the potential to differentiate the eggs of the two species. Moreover, the eggshells of C. fasciola exhibit a blocky morphology without cavities, whereas those of B. ravida, while also blocky, contain irregular cavities. These distinct elemental and microstructural characteristics enable the effective differentiation of the eggs of B. ravida and C. fasciola. Our study demonstrates the feasibility of a critical microscopic methodology for identifying land-snail eggs at the genus/species level, thereby facilitating deeper exploration of their value in understanding biological, climatic, and ecological changes. Full article

This article presents the results of the development of an antibacterial coating based on polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) fibers with embedded silver nanoparticles. Silver nanoparticles were synthesized via the use of PEG, which acts as a reducing agent for Ag⁺ ions and a stabilizer for the colloidal system. The resulting sols were pink, dark purple, and orange color. The viscosity of the compositions, which increased with increasing PEG and AgNO₃ concentrations, was studied. The sizes of the synthesized silver nanoparticles were determined via dynamic light scattering. For all compositions, monomodal particle size distributions were obtained with characteristic sizes of 50.75, 58.73, 13.54 and 28.21 nm. The highest ζ-potential value for the silver nanoparticles was ‒15.5 mV, indicating their stability. The electrical conductivity of the compositions increased with increasing molar concentration of AgNO₃. The resulting PVP-PEG compositions with silver nanoparticles demonstrated resistance to pathogenic bacteria such as Staphylococcus aureus and Escherichia coli. A portable electrospinning device was developed at the Mendeleev University of Chemical Technology of Russia to apply the compositions to the skin and form a protective coating of PVP-PEG fibers with an antibacterial effect. Fiber formation was confirmed by scanning electron microscopy. The incorporation of silver into the fiber structure was confirmed by the results of elemental analysis and surface mapping of the samples. Full article

Yellow and pink calcite samples from the Huanggangliang and Xilingol mining areas in Inner Mongolia were investigated to elucidate the relationships among chemical composition, unit-cell parameters, coloration, and luminescence. Electron probe micro-analysis, laser ablation inductively coupled plasma mass spectrometry, X-ray diffraction, infrared spectroscopy, Raman spectroscopy, UV-Vis absorption spectroscopy, and photoluminescence measurements show that samples of yellow and pink calcite differ significantly in impurity incorporation and optical behavior. Yellow calcite is relatively enriched in Mg and rare earth elements, especially Y and Ce, whereas pink calcite contains markedly higher Mn and Fe contents. The pink calcite has smaller lattice parameters and unit-cell volume, consistent with greater substitution of Ca²⁺ by smaller-radius cations. Spectra reveal that the pink coloration is mainly related to Mn-associated absorption bands at 402 and 527 nm, whereas the yellow color is attributed to weak impurity- and defect-related absorption. Under ultraviolet excitation, yellow calcite exhibits a broad blue–white emission centered at ~470 nm, whereas pink calcite shows an intense orange–red emission near 625 nm characteristic of Mn²⁺. Variable-temperature photoluminescence further demonstrates that the pink calcite has higher thermal stability, with a thermal-quenching activation energy of 0.218 eV, compared with 0.074 eV for the yellow calcite. These results demonstrate that trace element incorporation plays a key role in regulating the coloration and luminescence of calcite and provide useful insight into the optical behavior of carbonate minerals. Full article

Sulfur–soybean oil polymers with tunable thermal insulation properties were synthesized via inverse vulcanization of elemental sulfur and soybean oil and reinforced with biochar (BC) derived from spent barley biomass. Biopolymer films (F-BPs) with sulfur contents ranging from 20 to 80 wt% were prepared, and biochar-filled biocomposites (F-BP-Cs) were obtained using different filler loadings and processing routes. Their structural, morphological, thermal, mechanical, and surface properties were systematically analyzed to establish structure–property relationships, with particular focus on thermal transport behavior. Differential scanning calorimetry (DSC) revealed that sulfur contents ≤50 wt% favored the chemical incorporation of elemental sulfur into the polymer network via covalent bonding, significantly reducing the presence of free crystalline sulfur in the material. SEM images and porosity analysis revealed that BC incorporation and processing conditions significantly affected microstructural connectivity and air-filled porosity. As a result, F-BP-C materials exhibited low thermal conductivities, reaching values of ~0.033–0.039 W/(m·K), comparable to commercial insulating materials such as cork and polymeric foams. This reduction was attributed to increased structural disorder, high interfacial density, and enhanced phonon scattering within the heterogeneous polymer–BC–air system. These findings demonstrate the potential of these biocomposites as sustainable thermal insulating materials derived from industrial and agricultural waste. Full article

This study demonstrates the application of Laser-Induced Breakdown Spectroscopy (LIBS) for the elemental analysis of agricultural soils in South Punjab, Pakistan. Soil degradation due to intensive farming, imbalanced fertilizer use, and declining organic matter has reduced crop productivity in the region. To address this, rapid and accurate soil diagnostics are essential. LIBS, coupled with Calibration-Free analysis (CF-LIBS), was employed to quantitatively determine the concentrations of major and trace elements—including calcium, silicon, iron, aluminum, magnesium, titanium, potassium, sodium, lithium, and barium—without requiring chemical standards. Plasma characterization was performed using the Boltzmann plot method, yielding temperatures between 7750 and 9000 K, and electron number densities were derived from Stark-broadened spectral profiles. The results reveal significant spatial variability in elemental composition, reflecting differences in land use and irrigation sources. This work confirms LIBS as a versatile, efficient, and reliable tool for soil health assessment, offering a practical solution for monitoring soil nutrients and supporting sustainable agricultural management in resource-limited settings. Full article

The city of Veracruz preserves buildings mainly constructed during the 16th and 17th centuries, where carved madreporic coral was used as ashlar and as a component in mortars. These historic structures, now part of Mexico’s built heritage, show various degrees of deterioration caused by erosion and prolonged exposure to environmental elements. Restoration using original materials is currently nearly impossible due to ecological restrictions protecting coral reefs. In this context, and under the principles of the tailor-made technique, the present research revisits physico-mechanical and chemical studies conducted on the corals used in the construction of one of the most representative buildings in the city. The results were compared with those obtained from the formulation of experimental mortars using readily available materials—such as air lime, siliceous aggregates, and calcium carbonate—with the aim of reproducing the physical, mechanical, and chemical properties observed in the original corals. Laboratory tests allowed evaluation of their compatibility and performance, seeking to develop alternative materials that enable conservation interventions without compromising the integrity of the base material or the historic structures. The design of mortars is intended to be used in the restoration processes of buildings that are part of the built historical heritage. This is the starting point for understanding the characteristics of the mortar and its compatibility with the substrate, which could be used for repairing stone blocks and for preparing new mortars for masonry and plastering, since research on restoration mortars has largely overlooked this type of building with coral masonry due to its rarity. Therefore, this research is of particular interest. The mixtures formulated with calcareous sand were the most compatible with the reference coral material, while those made with silica sand exhibited properties superior to the corals, and marine sands showed very poor behavior, potentially compromising the integrity of the buildings. In physical–mechanical tests, formulations that include calcareous sand and silica sand (2 mm) demonstrated behavior closest to that of coral, consistent with chemical analysis results, where mortars formulated with calcareous sand registered the highest contents of CaO and portlandite. Mercury intrusion porosimetry indicated that the mortar formulated with silica sand (2 mm) has a porosity only 4.07% lower than that of the coral, while mortars formulated with calcareous sand and lime paste are between 11.17% and 16.87% lower. Therefore, one of the mixtures that stands out as the best option due to its similarity in physical–mechanical and chemical results is the composite that is not found at the extremes of the results obtained in the various tests carried out. The use of calcareous sand, as previously mentioned, enhances its behavior and affinity with the coral masonry, as demonstrated in the tests. Full article

Mining wastewater contains complex mixtures of regulated and emerging contaminants that challenge treatment technologies. This study evaluates the bioremediation potential of 10 phytoplankton species, including Chlorella vulgaris, and the aquatic fern Salvinia natans for removing contaminants from synthetic and mine outflow water. Batch screening experiments were conducted using synthetic wastewater containing regulated elements, rare earth elements (REEs), or selected organic flotation reagents, followed by validation using acidic mine outflow water from a decommissioned mine (Romania). All tested phytoplankton species and Salvinia natans showed high removal efficiencies for several priority elements, including Pb, Ag, Cr, Th, U, and multiple REEs. Organic flotation reagents were efficiently removed by all phytoplankton species. Chlorella vulgaris and Salvinia natans emerged as high-performing species and were further evaluated in mine outflow, where species-specific and matrix-dependent removal behavior was observed. Here, Chlorella vulgaris showed a higher average removal. Time-resolved analyses indicated a rapid initial removal followed by equilibrium phases, suggesting biosorption and bioaccumulation mechanisms. Li and Se showed limited removal capacities across all species. Photosynthetic pigment analysis revealed stress responses in Salvinia natans under acidic, multielement exposure. Overall, phycoremediation and phytoremediation represent effective low-chemical treatment strategies with potential for integration into a complementary mining wastewater treatment workflow. Full article

Direct welding of fused silica to pure titanium (Ti) foil using conventional methods faces significant challenges, such as poor interfacial wettability, insufficient joint strength, and the need for interlayers or surface pretreatments. Existing femtosecond (fs) laser welding techniques for these materials often require high-energy millijoule (mJ)-level pulses or alloy interlayers. Moreover, reports on direct microjoule (μJ)-level fs laser welding of Ti foil to fused silica remain scarce. This study successfully demonstrates a direct welding process for pure Ti foil and fused silica using μJ-level fs laser pulses under ambient conditions, achieving joints with a maximum shear strength of 9.19 MPa. Microstructural analysis revealed an elemental interdiffusion region at the weld interface, supported by mechanical interlocking effects. X-ray photoelectron spectroscopy (XPS) confirmed the occurrence of interfacial chemical reactions, forming titanium silicide (TiSi₂) and titanium oxide (TiO₂). Additionally, a 24 h water immersion test of a square sealed cavity revealed outstanding hermeticity, with no water ingress. This work provides a simple, efficient, and robust solution for high-strength, additive-free bonding of fused silica to Ti foil under low-energy processing conditions. Full article

Amyloid-β (Aβ) protein, a cleavage product of the amyloid precursor protein (APP), is the main component of neuritic plaques in Alzheimer’s disease (AD), and its accumulation has been considered as the molecular driver of Alzheimer’s pathogenesis. Aβ has been a primary target for therapy since the amyloid cascade theory was put forth, with methods designed to prevent the generation of Aβ. The APP 5′-untranslated region (UTR) mRNA encodes a functional structured iron-responsive element (IRE) that represents a potential target for small molecule inhibitors as an anti-amyloid therapy for AD. Here, we offer a comprehensive strategy that uses RNA-targeted binding to inhibit APP translation. The IRE family is among the few 3-D mRNA regulatory elements with a known 3-D structure. Accordingly, we exploit these structural and functional characteristics as our strategy to target APP IRE structured mRNA to identify anti-amyloid drugs. The mRNA encoding proteins involved in iron metabolism are regulated by this family of similar nucleotide sequences. Post-transcriptional control of cytoplasmic mRNA is a rapidly developing area of biomedicine. Across animals, evolutionarily conserved IRE mRNAs serve as a model system for 3-D mRNAs. IRE mRNAs have shown great promise for chemical manipulation of mRNA and protein expression in biological systems by yielding “proof of principle” data for small molecules targeting mRNA structures. A novel approach to identifying RNA-directed therapeutics to regulate APP expression and Aβ-peptide generation for AD treatments is exemplified by APP 5′-UTR-directed small molecule inhibitors. Full article

Gem-quality garnets exhibit significant potential for U-Pb geochronological applications due to their advantageous characteristics, including high closure temperatures (750–850 °C), optical transparency, chemical homogeneity, and low inclusion content. This study focuses on the gem-quality yellow-green grossular garnet variety (commonly termed Mali garnet), a unique gemstone exclusively occurring in contact metamorphic deposits of Western Africa’s Republic of Mali. Despite its mineralogical significance, fundamental aspects, including precise age determination and chromophore mechanisms of Mali garnet, remain poorly constrained. Here, we conducted standard gemological characterization, spectroscopic analyses (UV–Vis, FTIR, and Raman), electron probe microanalysis (EPMA), micro-X-ray fluorescence (μ-XRF) elemental mapping, and in situ trace element and laser ablation U-Pb geochronological analysis on Mali garnets. The spectral data and chemical composition studies reveal that the coloration of Malian garnets is primarily attributed to the presence of iron and chromium. Our U-Pb geochronological results yield a crystallization age of 197 ± 3 Ma for the Mali garnet samples. The robustness of garnet U-Pb systems in preserving crystallization ages through multiple thermal events supports their application to Precambrian polymetamorphic terranes, where zircon systems are frequently reset. Full article

To investigate the inevitable aging of composite insulators under the coupled effects of electrical, thermal, ice, and fog stresses, as well as to explore their aging mechanisms and residual strength prediction methods, this study collected operational insulator samples from four environmental regions: Tibet, Yunnan, Hunan Xuefeng Mountain, and Anhui/Chongqing. Mechanical properties, including tensile strength, elongation at break, and shear resistance, were tested. The results indicate that the degradation of mechanical performance in composite insulation components can be attributed to the synergistic interaction of operational environments and material characteristics, with the aging behavior of high-temperature vulcanized (HTV) silicone rubber exhibiting significant non-linearity. Based on existing research, molecular dynamics simulations were employed to construct microstructural models at different aging stages, and it was verified that main chain scission, reduced system density, and changes in the elemental chemical environment during aging are closely related to the degradation of material mechanical properties. Based on hyper-elastic constitutive theory and fracture mechanics, a quantitative method for assessing the comprehensive aging degree was proposed, with “service years” and “operational altitude” as the core dimensions. A negative exponential model was established to describe the strength degradation of silicone rubber materials. This model enables the non-destructive estimation of the residual mechanical strength of in-service insulators in complex regions without power interruption, providing a decision-making framework for grid operation and maintenance. Full article

This study investigates the effect of complex nanomodification combined with the simultaneous application of magnetic fields and mechanical vibration on the structure formation and performance properties of medium-alloy steel 40CrNi3MoV. Improving the structural homogeneity and operational characteristics of such steels remains an important task due to their widespread use in components operating under severe loading and wear conditions. The introduction of the nanostructured modifier InSteel-7 at a concentration of 0.03%, together with simultaneous magnetic and vibrational treatment of the melt, resulted in pronounced structural homogenization and grain refinement. Quantitative metallographic analysis using Thixomet Pro image analyzer revealed a significant refinement of the dendritic structure, with the secondary dendrite arm spacing decreasing from 73.9 μm to 27.9 μm. X-ray phase analysis confirmed the preservation of phase composition while indicating increased structural uniformity of the BCC matrix. Energy-dispersive spectroscopy and elemental micro-mapping demonstrated high chemical purity of the alloy and a uniform distribution of the modifier components. The combined treatment significantly improved the mechanical and tribological characteristics of the material. The average hardness increased from 390 HV to 510 HV, while tribological tests showed a reduction in wear track depth from 5.16 μm to 0.87 μm and a decrease in surface roughness from Ra 2.13 μm to 0.20 μm, indicating enhanced wear resistance. Full article