Search Results (627)

Iron beneficiation tailings from the Bayan Obo West Mine constitute a low-grade secondary rare-earth resource in which rare-earth minerals are finely disseminated and intricately intergrown with gangue. This study quantified the modes of occurrence of rare-earth minerals and assessed an integrated flowsheet comprising screening, magnetic separation, and flotation. The feed contained 1.32 wt.% rare-earth oxides (REOs), as determined by X-ray fluorescence spectrometry (XRF) and inductively coupled plasma optical emission spectrometry (ICP-OES). X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and automated mineralogy (AMICS) further showed that monazite and bastnäsite hosted 47.39% and 39.19% of the total REOs, respectively. Screening at 74 μm rejected 32.60% of the feed as a coarse fraction containing 0.65 wt.% REOs. Subsequent wet high-intensity magnetic separation reduced the mass entering flotation to 54.35% of the original feed while retaining 74.94% of the feed REOs and increasing the REO grade to 1.82 wt.%. Closed-circuit flotation with one rougher and three cleaner stages yielded a concentrate containing 51.99 wt.% REOs at an overall recovery of 52.38%. Rare-earth minerals accounted for 82.55 wt.% of the concentrate, including 41.65 wt.% monazite and 33.96 wt.% bastnäsite. This study thus demonstrated the feasibility of producing a high-grade rare-earth concentrate from the low-grade, fine-grained iron beneficiation tailings of the Bayan Obo West Mine characterized by complex mineral intergrowths, providing a practical basis for further rare-earth beneficiation and flowsheet optimization. Full article

Two-dimensional GaS_xTe_1−x alloy nanosheets with different compositions were synthesized by chemical vapor deposition using GaS and GaTe powders as precursors. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses confirmed their sheet-like morphology and the uniform distribution of S and Te, while Raman and photoluminescence measurements revealed composition-dependent vibrational and emission characteristics. Te-rich samples exhibited position-dependent emission ranging from the red to the near-infrared region, whereas increasing the S content gradually shifted the emission toward the blue-green region. Among the synthesized samples, GaS_0.9Te_0.1 showed a relatively stable photoluminescence peak near 520 nm and was therefore selected as a fluorescent powder for latent fingermark development. Its performance was evaluated on glass, stainless steel, plastic, and ceramic surfaces and compared with that of silver powder, gold powder, and commercial red fluorescent powder. GaS_0.9Te_0.1 produced clear fluorescent ridge patterns and strong background contrast, particularly on glass, plastic, and white ceramic. The mean contrast across the four substrates reached 25.83, exceeding that of the reference powders. These results demonstrate that GaS_xTe_1−x nanosheets possess tunable optical properties and that GaS_0.9Te_0.1 is a promising fluorescent material for latent fingermark development on non-porous surfaces. Full article

Particulate contamination in oral dosage forms poses significant challenges to product integrity and patient trust, yet these formulations lack the well-defined regulatory limits established for injectables. This review comprehensively analyses existing literature, regulatory guidelines, and analytical techniques to identify primary contamination sources, assess regulatory gaps, and propose science-based mitigation strategies. Key contamination vectors include raw materials, manufacturing equipment, facilities, packaging, personnel activities, utilities, processing aids, cleaning residues, and process design deficiencies. While solid oral dosage forms can encapsulate particulates, liquid formulations present a heightened ingestion risk. To combat these vulnerabilities, advanced analytical techniques—such as Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and X-ray fluorescence—are evaluated alongside emerging artificial intelligence-driven detection and real-time monitoring systems. Because current regulations inadequately address particulate matter in oral dosage forms, this paper introduces a structured decision pathway model to enhance contamination management. Ultimately, regulatory harmonization is essential for patient safety, and future research must focus on refining detection methodologies, risk-based strategies and establishing scientifically justified particulate thresholds. Full article

This study evaluated potentially toxic element (PTEs) contamination (As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) in soil and grapevine leaves across 36 sites in a historical vineyard near Iași, Romania, transitioning toward residential development. Soil samples were analyzed using energy-dispersive X-ray fluorescence (ED-XRF), while leaf tissues collected during the véraison stage (mid-August) underwent microwave-assisted acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). Soil analyses revealed that average concentrations of Cr, Ni, and Pb exceeded national normal legal thresholds, while Cu and As surpassed alert permissible limits. Contamination factor ($CF$) and Geoaccumulation Index ($I_{geo}$) metrics confirmed significant anthropogenic Cu enrichment from historical viticultural treatments. Soil-to-leaf transfer factors ($TF$) approached or exceeded 1 for Cu and Zn, though grapevine was not identified as a hyperaccumulator. Spearman correlation modeling demonstrated a statistical decoupling between soil concentrations and foliar tissue levels for Cu ($r_s=-0.21$) and Zn ($r_s=0.075$), confirming that canopy accumulation is governed by historical agrochemical spraying and atmospheric deposition rather than root-driven uptake. Conversely, Pb ($r_s=0.43$) exhibited a moderate direct soil-to-leaf pathway. The potential ecological risk ($PER$) index indicated moderate-to-considerable cumulative risk, primarily driven by Cu ($E_{Cu}=68.64$) and Cd ($E_{Cd}=59.17$). Human health risk assessments established direct ingestion as the primary exposure pathway, with current non-carcinogenic hazards remaining within tolerable limits ($HI<1$). However, the proposed residential conversion increases exposure risks for vulnerable cohorts, underscoring the necessity of systematic soil screening and remediation prior to land redevelopment. Full article

A multicomponent Ni₅₄Cr₂₈Mo₈Nb₅Ta₅ nickel-based superalloy was produced by vacuum induction melting followed by homogenization, hot forging, solution treatment, and aging to investigate its microstructural and mechanical behavior. The X Ray Fluorescence (XRF) analysis confirmed excellent agreement between the nominal and experimental chemical compositions. The X Ray Diffraction(XRD) combined with Rietveld refinement revealed a microstructure dominated by three closely related to face-centered cubic (FCC) (A1) solid-solution regions with slightly different lattice parameters, indicating local compositional variations. The Scanning Electron Microscopy(SEM)/Energy Dispersive Spectroscopy (EDS) observations showed a generally homogeneous elemental distribution, while optical and electron microscopy identified a dendritic microstructure with elongated interdendritic constituents enriched in refractory elements. Mechanical characterization yielded an average hardness of 497 HV_0.5, a compressive strength of approximately 1950 MPa, and room-temperature yield and ultimate tensile strengths of 1050 MPa and 1320 MPa, respectively. Tensile strength gradually decreased with increasing temperature up to 900 °C, while ductility increased from 16% to 25% total elongation. The results indicate that the alloy develops a stable FCC matrix primarily strengthened by solid-solution hardening, with the measured mechanical performance suggesting an additional contribution from precipitation hardening. This study provides an experimental baseline for the development and optimization of conventionally processed Ni–Cr–Mo–Nb–Ta superalloys for high-temperature applications. Full article

Natural blue calcite is relatively rare, and its coloration and luminescence mechanisms have not been systematically established. In this study, four natural blue calcite samples from China were comprehensively characterized using mineralogical testing, X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), photoluminescence (PL), and electron paramagnetic resonance (EPR). XRD confirms single-phase trigonal calcite (space group R-3c). EPMA detects minor Mg, Fe, Cu, and Sr, with smaller-radius Mg²⁺, Fe²⁺, and Cu²⁺ being the main contributors to the contraction through isomorphous substitution for Ca²⁺. UV-Vis spectra show characteristic absorptions at 270 nm and 340 nm related to lattice defects with a broad emission band centered at 480 nm in the PL spectra. EPR detects a CO₂⁻ radical center (g = 2.003), and the same signal is also observed in the colorless sample. The colorless sample also contains the same CO₂⁻ radicals, indicating that these radicals alone do not account for the blue coloration. A broad 480 nm blue-violet fluorescence band is observed in the four blue samples under 405 nm excitation. These findings provide a spectroscopic and crystallographic basis for distinguishing natural blue calcite from analogous materials and for understanding the origin of its color and luminescence. Full article

This study investigates the effect of adding silicon (Si) and cadmium (Cd) elements to AM60 (Mg) magnesium alloy on its corrosion and tribocorrosion (abrasive wear) properties at pH 2.4. Optical Microscopy (OM), X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), SEM mapping, and SEM line methods were applied to the alloys. Additionally, the effect of Cd addition on the alloys was investigated using potentiodynamic polarization corrosion in a medium containing CH₃COOH (vinegar) at pH 2.4 (acetic acid) and 20 N and 40 N reciprocal abrasive wear tests in the same medium. The hardness of alloy A1 was determined to be 58.6 HV. Hardness increased by 0.92% in alloy A2, 4.18% in alloy A3, and 10.66% in alloy A4, with the hardness increase occurring as Cd content increased. In potentiodynamic corrosion tests, the corrosion rate (CR) increased with increasing Cd content. In abrasive wear tests, Cd addition increased the abrasive wear rate, and the alloys were ranked in order of increasing wear as follows: A1 < A3 < A2 < A4. These results will contribute to the automotive, aerospace, agricultural, construction, and machinery industries operating in acidic environments, as well as to the scientific literature. Full article

The growing accumulation of coal combustion by-products necessitates the development of sustainable approaches for their utilization in construction materials. This study investigates the production of sintered fly ash aggregate (SFAA) using hydraulic ash waste from the Kyzylorda Combined Heat and Power plant and evaluates its suitability as a coarse aggregate for lightweight cementitious composite. Hydraulic fly ash and clay from the Talsuat deposit were pelletized and sintered at 1100 °C. The physicochemical, mineralogical, and microstructural characteristics of the raw materials and produced aggregate were examined using X-ray fluorescence, X-ray diffraction, scanning electron microscopy with energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The developed aggregate exhibited a bulk density of 1118 kg m⁻³, water absorption of 5.4%, crushing strength corresponding to grade M200, and frost resistance of at least F35. Mineralogical analysis revealed quartz and mullite as the predominant crystalline phases, while microstructural observations confirmed the formation of a stable porous aluminosilicate matrix. Chemical durability tests in alkaline, chloride, and sulfate media demonstrated high resistance to aggressive environments. Lightweight cementitious composite produced with the aggregate achieved an average density of 1657 kg m⁻³, compressive strength of 3.87 MPa, and water absorption of 16.0%, corresponding to density grade D1600 and strength class B3.5. The results confirm the feasibility of converting hydraulic ash waste into a durable lightweight aggregate suitable for structural-insulating lightweight cementitious composite, contributing to waste valorization, conservation of natural resources, and sustainable construction practices. Full article

This study investigates the hydrometallurgical recovery of valuable metals from copper shaft furnace dust (SFD), a complex industrial waste containing approximately 40 wt.% Zn, 16 wt.% Pb, and 1 wt.% Cu. In contrast to conventional inorganic leaching processes that rely on aggressive acids and bases, this research explores the use of deep eutectic solvents (DESs) as eco-friendly and selective lixiviants. Deep eutectic solvents based on choline chloride combined with citric acid and lactic acid were evaluated as leaching media for metal recovery from SFD. The effects of temperature, leaching time, stirring intensity, and the DES:SFD ratio on metal extraction were systematically investigated. Analytical characterization of the raw material, leaching residues, and pregnant leach solutions was performed using Atomic Absorption Spectroscopy (AAS), X-ray Fluorescence Spectrometry (XRF), and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM–EDS). The experimental results demonstrated efficient recovery of Zn, Pb, Cu, and Sn under mild leaching conditions. For the citric acid–choline chloride system, the highest extraction efficiency was obtained at 60 °C using a DES:SFD ratio of 30, whereas increasing the temperature to 70–80 °C did not significantly improve metal extraction. The lactic acid–choline chloride system exhibited different leaching behaviour, with the highest recoveries achieved after short leaching times. These findings indicate that DES-based systems represent a promising, sustainable alternative for the selective leaching of heavy metals such as Zn, Pb, Cu, and Sn, from metallurgical secondary raw materials, contributing to the development of greener circular economy practices. Full article

The escalating global accumulation of plastic waste (PW) poses a critical obstacle to environmental sustainability, necessitating the development of viable valorization strategies. Pyrolysis process offers a thermo-chemical conversion pathway capable of transforming waste plastics into a potentially functional liquid product. This work presents a systematic and comprehensive investigation of the physicochemical, wettability, thermal stability, rheological, and tribological properties of pyrolysis oil (i.e., pyro-oil) derived from virgin linear low-density polyethylene (LLDPE) pellets to mimic the behavior of common polymers in such thermo-chemical conversion processes. Pyro-oil was produced under controlled slow pyrolysis conditions in a fixed-bed reactor at 700 °C, and its properties were benchmarked against tire-derived pyro-oil and a commercial engine oil. Chemical and structural characterization was conducted via Fourier transform infrared spectroscopy (FTIR), wavelength dispersive X-ray fluorescence (WDXRF), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Wettability was evaluated through temperature-dependent contact angle measurements, and thermal stability was assessed by thermogravimetric analysis (TGA). Rheological profiling of the plastic pyro-oil was investigated using a rheometer apparatus at different temperatures. Lastly, the tribological properties of plastic pyro-oils at various temperatures were examined using a tribometer instrument in a ball-on-disk configuration. Results demonstrate that plastic-derived pyro-oil exhibits a hydrocarbon-dominant chemical composition similar to that of tire pyro-oil and engine oil. Its absolute viscosity is nearly similar to that of the tire pyro-oil and is lower than that of engine oil across different temperatures. Tribological testing revealed that the plastic pyro-oil results in lower friction at elevated temperatures compared to both tire pyro-oil and commercial engine oil. However, the thermal examinations showed that plastic pyro-oil has lower thermal stability than tire pyro-oil and engine oil. Overall, these findings indicate that plastic pyro-oil holds promise as a functional lubricant for low-load and moderate-temperature industrial applications, positioning PW pyrolysis as a viable contributor to circular economy strategies in the lubricants sector. Full article

The article presents the research findings on a collection of ceramic crucibles excavated at the Koksharovka-1 hillfort, known as one of the most significant archaeological sites of the Medieval epoch (7th–13th centuries) in the Russian Far East. This study represents an investigation of melting crucibles as a distinct category of metalworking ceramics discovered in the research area. The study is based on an integrated approach combining traditional archaeological analysis with physicochemical methods, including scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), X-ray fluorescence spectroscopy (XRF), Raman spectroscopy, electron probe microanalysis (EPMA), and computed microtomography (micro-CT). The research found that the morphological and technological properties of the crucibles were consistent with their function as containers for metal heat treatment. Traces of copper-based alloys as well as gold and silver processing were detected as a result of the crucible examination. For the first time, archaeological evidence of silver and gold metalworking in the Russian Far East during the Medieval epoch has been obtained. Full article

Background/Objectives: Plant-mediated silver nanoparticles (AgNPs) are promising components for oral biomaterials because of their antimicrobial potential; however, their biological behavior depends strongly on the phytochemical matrix, physicochemical characteristics, and exposure concentration. This study aimed to evaluate silver nanoparticles formulations synthesized using turmeric powder-derived Curcuma longa ethanolic and aqueous extracts, with emphasis on physicochemical characterization, antibacterial activity against oral-relevant Gram-positive bacteria, cytocompatibility toward human gingival fibroblasts (HGF-1), and acute in ovo vascular compatibility. Methods: AgCUR-EtOH NPs and AgCUR-H₂O NPs were synthesized using CUR-EtOH and CUR-H₂O extracts as reducing and stabilizing matrices. The resulting formulations were characterized by UV–visible spectroscopy (UV-Vis), dynamic light scattering (DLS), zeta-potential analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined against Streptococcus mutans, Streptococcus oralis, and Staphylococcus aureus. Cytocompatibility was evaluated in HGF-1 human gingival fibroblasts after 24 h exposure to 1–10 µg/mL using complementary viability, lysosomal, mitochondrial, and fluorescence-based assays. Acute vascular irritation was assessed using the hen’s egg test–chorioallantoic membrane (HET-CAM) assay. Results: Both formulations exhibited broad, polydisperse hydrodynamic distributions and negative apparent zeta potentials. AgCUR-H₂O NPs showed a lower Z-average diameter than AgCUR-EtOH NPs under their respective solvent-specific measurement conditions. XRD pattern revealed heterogeneous crystalline compositions dominated by residual AgNO₃, together with weaker contributions consistent with metallic Ag and a possible minor oxidized silver phase. FTIR spectra demonstrated extract-derived organic functional groups and prominent nitrate-associated bands. TEM/EDX confirmed Ag-containing nanostructures with approximate size ranges of 15–175 nm for AgCUR-EtOH NPs and 15–150 nm for AgCUR-H₂O NPs. S. mutans was the most susceptible microorganism, with MIC values of 9 and 7 µg/mL and MBC values of 88 and 62 µg/mL for AgCUR-EtOH NPs and AgCUR-H₂O NPs, respectively. AgCUR-H₂O NPs consistently showed lower MIC and MBC values against all tested strains, but also produced a more pronounced concentration-dependent reduction in HGF-1 viability. At 10 µg/mL, cell viability was 71.88% for AgCUR-EtOH NPs and 52.14% for AgCUR-H₂O NPs. Both formulations showed low acute irritation potential in ovo, with irritation scores of 1.06 and 0.69, respectively. Conclusions: The two CUR-AgNP formulations exhibited distinct physicochemical, antibacterial, and cellular response profiles under the tested conditions. At equivalent concentrations expressed as total dried formulation mass, AgCUR-H₂O NPs yielded lower MIC and MBC values against the tested bacterial strains, whereas AgCUR-EtOH NPs produced a less pronounced reduction in HGF-1 viability. Because the powders were not quantitatively normalized for total silver, extract-derived organic fraction, or residual precursor content, these differences cannot be attributed exclusively to nanoparticle properties or to the extraction solvent and should not be interpreted as evidence of the intrinsic superiority of either formulation. Both formulations showed low acute vascular irritation. Further quantitative compositional, silver-release, and biofilm assessments are required before incorporation into oral biomaterial platforms. Full article

In recent years, hybrid materials have been widely applied in the cultural heritage conservation field, especially to preserve color pigments. Among these, one of the most problematic (in terms of conservation science) is the red pigment cinnabar/vermilion. The challenge of this work was to prepare a hybrid coating consisting of a fluorinated polymer (known to protect cinnabar/vermilion), further modified with an inorganic filler based on anatase TiO₂. The latter is suitable because it is functionalized with quenchers, the particles are well above the nanoscale (≥200 nm in diameter), and it was added to the polymer matrix in small quantities. These characteristics made it suitable as a hybrid coating for protecting natural cinnabar, as demonstrated by the results obtained through a multi-analytical approach, based on multispectral imaging, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), contact angle, spectrophotometry and mechanical tests, which were applied to evaluate the performances of the hybrid coating on laboratory specimens (after aging) and original samples. The experimental results provide insight into both the physicochemical decomposition mechanism of natural cinnabar under laboratory-simulated aging conditions and the benefits of the coating. In particular, the treatment did not induce electrochemical changes in the mercury, which remained in its oxidized state (+2) rather than being further reduced to elemental mercury (Hg⁰), the species responsible for the blackening of cinnabar/vermilion (also combined with meta-cinnabar). In the oxidized form (Hg²⁺), the protein binder was altered, yet the application of the hybrid coating did not cause further physicochemical changes (i.e., red shift) to the Hg²⁺/egg-based binder system. This was also reflected in the color properties, which underwent no significant alteration. Finally, the mechanical tests yielded satisfactory results, particularly regarding water vapor permeability and treatment efficiency (even eight months after the initial application, although studies on the same samples are still ongoing). The hybrid coating was ultimately applied to original samples collected at Poggio Spaccasasso (Tuscany, Italy), which could be representative of prehistoric artworks based on natural cinnabar and traces of prehistoric adhesives made from beeswax, natural oils, and plant resins. Full article

This study presents the first technical examination of Ring Around the Rosie (ca. 1908), an easel painting by the Greek artist Symeon Savvidis (1859–1927). Despite Savvidis’ significance within Greek modernism, little is known about his materials and working practices from a scientific perspective. To address this gap, the painting was analysed using VNIR hyperspectral imaging (HSI), portable Raman spectroscopy, and handheld energy dispersive X ray fluorescence (h-EDXRF). The integration of imaging, molecular, and elemental data enabled the identification of several pigment classes, including cobalt blue, ultramarine, lead chromates, ochres, lead white, and a tentative Cu-As green pigment, while also providing information on their spatial distribution across the surface. HSI classification and the examination of a representative NIR image revealed relationships among the coloured passages and suggested the widespread use of a cobalt-containing background paint. The results further indicate that several compositional elements may have been applied directly over previously, although the absence of stratigraphic information prevents definitive conclusions regarding paint layering and mixtures. Overall, the study demonstrates the value of combining HSI, Raman spectroscopy, and h-EDXRF for the non-invasive investigation of artists’ materials and highlights the contribution of technical studies to a broader understanding of Savvidis’ artistic practice and modern Greek painting traditions. Full article

Urban mining is gaining importance as demand for critical metals continues to rise. Waste light-emitting diode (LED) lamps are a valuable secondary source of gallium, rare earth elements, precious metals, and base metals, yet accurately quantifying these metals remains challenging. In this work, various LED waste streams from a lamp recycler were subjected to critical metal characterization. The strengths and weaknesses of established metal assay techniques were evaluated to advance the determination of gallium, rare earth elements (Ho, Lu, Tb, Y, Er, Nd, Ce), and precious metals (Au, Ag, Pt, Pd) in LED waste. Metal assays, including alkaline fusion, four-acid digestion, aqua regia, a fire assay, and energy-dispersive X-ray fluorescence, were compared, and precision was assessed using a newly created LED lamp reference material and OREAS465. A metal-analysis-driven approach was developed to quantify the reduction in mining through recycling LED lamps using the rock-to-metal ratio metric. The economic value of LED waste streams, together with their recyclability and grindability, was assessed. The results indicate that LED strips can contain up to 147,484 g/t Cu, 452 g/t Ga, 367 g/t Lu, 89 g/t Tb, and 95 g/t of precious metals. Recycling one tonne of waste LEDs can offset mining 75.5 tonnes of rock and primary ore. The estimated economic value of mixed LED waste was USD 3351 per tonne, increasing to USD 4089 per tonne after physical separation. The results demonstrate the importance of robust analytical methods for accurate metal accounting and provide a stronger foundation for assessing the recycling potential of LED waste. Full article