Search Results (122)

One of the most effective methods of improving the properties of aluminium alloys is grain refining using Al-Ti-B master alloys. In contrast, zirconium is a key alloying element, used mainly in 2xxx and 7xxx series aluminium alloys, where it contributes to dispersion enhancement and reduces the rate of dynamic recrystallisation. However, even trace amounts of zirconium—just a few hundredths of ppm—significantly reduce the performance of Al-Ti-B grain refiners, a phenomenon known as ‘Zr poisoning’. This study investigates the impact of holding time and the level of Al-5Ti-1B addition on the microstructure and properties of an AlMgSi(Cu) alloy containing 0.15 wt.% Zr, cast as 7-inch DC billets. The structure and phase distribution were characterised using optical microscopy (OM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Grain size and morphology were evaluated through macrostructure analysis (etched cross-sections and polarised light microscopy), while chemical and elemental distributions were analysed via SEM-EDS and STEM-EDS mapping. Additionally, Brinell hardness measurements were conducted across the billet diameter to assess the correlation between grain size and mechanical properties. The results show that reducing holding time and increasing the Al-5Ti-1B addition improves grain refinement efficiency despite the presence of Zr. The finest grain structure (150–170 μm) and most homogeneous hardness distribution were achieved when the grain refiner was continuously fed during casting at 80 ppm B. These findings are supported by the literature and contribute to a deeper understanding of the Zr poisoning effect and its mitigation through optimized casting practice. Full article

This study aims to enhance the mechanical and wear properties of AZ91 magnesium alloy by reinforcing it with 23 vol.% short carbon fibers (SCFs) aligned in normal (AZ91C-N) and parallel (AZ91C-P) orientations via squeeze-casting. The microstructure and elemental distribution maps were analyzed using an advanced SEM-EDS system. A response surface methodology (RSM) based on a Face-Centered Composite Design (FCCD) was employed to optimize the properties under varying temperature (20–300 °C) and wear load (1–5 N) conditions. The ultimate compressive strength (UCS), yield strength (YS), reduction in height at fracture (Fr), reduction in height at maximum stress (Sr), volume loss, and wear rate were analyzed and optimized. ANOVA confirmed the significant influence of the experimental parameters. A statistical model was developed, with validation showing deviations less than 0.05. The optimized conditions resulted in a UCS of 253 MPa, a YS of 193 MPa, an Fr of 26.1%, an Sr of 21.7%, a volume loss of 0.066 cm³, and a wear rate of 840 cm³/m. The worn surface and surface roughness were also investigated and discussed. The orientation of SCFs significantly influenced wear resistance and surface roughness. This study demonstrates the effectiveness of RSM in optimizing AZ91-SCF composites for high-performance applications. Full article

This study explores the fabrication, structural characteristics, and performance of an innovative porous geopolymer membrane made from waste natural zeolite powder for Pb(II) removal, with potential applications in wastewater treatment. A hybrid geopolymer membrane incorporating polyvinyl acetate (PVAc) (10, 20, and 30 wt.%) was synthesized and thermally treated at 300 °C to achieve a controlled porous architecture. Characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), revealed the disappearance of characteristic C=O and C-H stretching bands (~1730 cm⁻¹ and ~2900 cm⁻¹, respectively), confirming the full degradation of PVAc. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) indicated a total mass loss of approximately 14.5% for the sample with PVAc 20 wt.%, corresponding to PVAc decomposition and water loss. Energy-dispersive spectroscopy (EDS) elemental mapping showed the absence of carbon residues post-annealing, further validating complete PVAc removal. X-ray diffraction (XRD) provided insight into the crystalline phases of the raw zeolite and geopolymer structure. Once PVAc removal was confirmed, the second phase of characterization assessed the membrane’s mechanical properties and filtration performance. The thermally treated membrane, with a thickness of 2.27 mm, exhibited enhanced mechanical properties, measured with a nano-indenter, showing a hardness of 1.8 GPa and an elastic modulus of 46.7 GPa, indicating improved structural integrity. Scanning electron microscopy (SEM) revealed a well-defined porous network. Filtration performance was evaluated using a laboratory-scale dead-end setup for Pb(II) removal. The optimal PVAc concentration was determined to be 20 wt.%, resulting in a permeation rate of 78.5 L/(m²·h) and an 87% rejection rate at an initial Pb(II) concentration of 50 ppm. With increasing Pb(II) concentrations, the flux rates declined across all membranes, while maximum rejection was achieved at 200 ppm. FTIR and EDS analyses confirmed Pb(II) adsorption onto the zeolite-based geopolymer matrix, with elemental mapping showing a uniform Pb(II) distribution across the membrane surface. The next step is to evaluate the membrane’s performance in a multi-cation water treatment environment, assessing the sorption kinetics and its selectivity and efficiency in removing various heavy metal contaminants from complex wastewater systems. Full article

The development of fast-charging lithium-ion batteries urgently requires high-performance anode materials. In this paper, through an ultrafast carbothermal shock (CTS) strategy, titanium niobium oxide (TiNb₂O₇, TNO) with an optimized structure was successfully synthesized within 30 s. By regulating the synthesis temperature to 1200 °C, the TNO-1200 material was obtained. Its lattice parameters (a-axis: 17.6869 Å) and unit-cell volume (796.83 ų) were significantly expanded compared to the standard structure (a-axis: 17.51 Å, volume ~790 ų), which widened the lithium-ion migration channels. Rietveld refinement and atomic position analysis indicated that the partial overlap of Ti/Nb atoms and the cooperative displacement of oxygen atoms induced by CTS reduced the lithium-ion diffusion energy barrier. Meanwhile, the cation disorder suppressed the polarization effect. Electrochemical tests showed that after 3000 cycles at a current density of 10 C, the specific capacity of TNO-1200 reached 125 mAh/g, with a capacity retention rate of 98%. EDS mapping confirmed the uniform distribution of elements and the absence of impurity phases. This study provides an efficient synthesis strategy and theoretical basis for the design of high-performance fast-charging battery materials through atomic-scale structural engineering. Full article

This study reports the synthesis, characterization, and catalytic performance of a series of catalysts of Ru supported on CeO₂-Y₂O₃ composites (Ru/CeYX; X = 0, 33, 66, and 100 wt.% Y₂O₃) for CO₂ hydrogenation. Supported material modification (Y₂O₃-CeO₂), by the Y₂O₃ incorporation, allowed a change in selectivity from methane to RWGS of the CO₂ hydrogenation reaction. This change in selectivity is correlated with the variation in the physicochemical properties caused by Y₂O₃ addition. X-ray diffraction (XRD) analysis confirmed the formation of crystalline fluorite-phase CeO₂ and α-Y₂O₃. High-resolution transmission electron microscopy (HR-TEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping revealed the formation of a homogeneous CeO₂-Y₂O₃ nanocomposite. As the Y₂O₃ content increased, the specific surface area, measured by BET, showed a decreasing trend from 106.3 to 51.7 m² g⁻¹. X-ray photoelectron spectroscopy (XPS) of Ce3d indicated a similar Ce³⁺/Ce⁴⁺ ratio across all CeO₂-containing materials, while the O1s spectra showed a reduction in oxygen vacancies with increasing Y₂O₃ content, which is attributed to the decreased surface area upon composite formation. Catalytically, the addition of Y₂O₃ influenced both conversion and selectivity. CO₂ conversion decreased with increasing Y₂O₃ content, with the lowest conversion observed for Ru/CeY100. Regarding selectivity, methane was the dominant product for Ru/CeY0 (pure CeO₂), while CO was the main product for Ru/CeY33, Ru/CeY66, and Ru/CeY100, indicating a shift towards the reverse water–gas shift (RWGS) reaction. The highest RWGS reaction rate was observed with the Ru/CeY33 catalyst under all tested conditions. The observed differences in conversion and selectivity are attributed to a reduction in active sites due to the decrease in surface area and oxygen vacancies, both of which are important for CO₂ adsorption. In order to verify the surface species catalytically active for RWGS, the samples were characterized by FTIR spectroscopy under reaction conditions. Full article

The Earth abounds in water resources; however, only 0.4% of the freshwater resources are suitable for drinking. The scarcity of freshwater resources has a severe impact on the sustainable development of human society. Desalination is regarded as one of the most effective solutions. In this study, a research approach integrating materials and devices was utilized to synthesize manganese oxide-coated carbon nanospheres (CS@MnO₂). Experimental results demonstrated that the system, by combining the distinctive performance merits of the CS@MnO₂ material and the balanced desalination features, exhibited outstanding desalination performance. In the EDS elemental mapping analysis, the relatively feeble signal of carbon was ascribed to the encapsulation of MnO₂ on the outer surface of CS. Through computational TGA analysis, the mass fraction of carbon in CS@MnO₂-2 was determined to be approximately 51.2%. The excellent hydrophilicity of the material facilitated the permeation of the salt solution throughout the electrode, thereby enhancing the capacitance. CS@MnO₂-2 manifested a high salt adsorption capacity of 27.42 mg g⁻¹ and the fastest electrosorption rate of 7.81 mg g⁻¹ min⁻¹. During 50 adsorption desorption cycles, the adsorption capacity showed good results. The adsorption kinetics and adsorption isotherm fitting indicated that the desalination process involved electrostatic and multilayer adsorption. This study holds great significance for reducing the cost of desalinated water and guaranteeing a sustainable supply of freshwater resources. Full article

Background: There is only limited research on the coronal cementum of a tooth, and the mechanisms of its forming process are not well-defined. This report presents a coronal cementum on the occlusal surfaces of enamel in an impacted wisdom tooth in a human, which is not nearly the cervical portion. Materials and Methods: The tooth (Tooth #1) was derived from a 46-year-old female. Histological analysis, including hematoxylin and eosin (HE) and toluidine blue (TB) staining, and Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometer (SEM-EDS) analysis of the extracted tooth were conducted. Radiographic examination showed that Tooth #1 was horizontally impacted in the maxilla and had the apex of a single root placed between the buccal and palatal roots of Tooth #2. Results: Coronal cementum was distributed widely on the enamel, and reduced enamel epithelium was also found with enamel matrix proteins histologically. The formation of acellular cementum was observed to be more predominant than that of the cellular cementum in Tooth #1. SEM showed that the occlusal cementum connected directly with enamel. Calcium mapping revealed an almost similar occlusal cementum and enamel. In addition, the spectrum of elements in coronal cementum resembled the primary cementum according to SEM-EDS. Discussion: Thus, coronal cementogenesis in impacted human teeth might be related to the existence of reduced enamel epithelium. Full article

The aim of this study was to systematically analyze the influence of potential and the Co(II)–Ru(III) molar ratio on the electrochemical behavior of the Co–Ru system during codeposition from acidic chloride electrolytes. The equilibrium speciation of the baths was investigated spectrophotometrically and compared with theoretical calculations based on the stability constants of Co(II) and Ru(III) complexes. The codeposition of the metals was characterized using electroanalytical methods, including cyclic voltammetry, chronoamperometry, and anodic stripping linear voltammetry. The alloys obtained at different potentials were analyzed for their elemental composition (EDS, mapping), phase composition (XRD), and surface morphology (SEM). The morphology and composition of the alloys were mainly dependent on the deposition potential, which controlled the cobalt incorporation. Ruthenium–rich alloys were produced at potentials of −0.6 V and −0.7 V (vs. SCE). In these conditions, cobalt anomalously codeposited due to the formation of the CoOH⁺ intermediate, triggered by the intense hydrogen evolution on the ruthenium sublayer. Bulk cobalt electrodeposition began at a potential of around −0.8 V, resulting in the formation of cobalt-rich alloys. The early stages of the electrodeposition were investigated using different nucleation models. A transition from 2D progressive nucleation to 3D instantaneous nucleation at around −0.8 V was identified as being caused by cobalt incorporation. This was well correlated with electroanalytical data, partial polarization curves of alloy deposition, elemental mapping analysis, and the structure of the deposits. Full article

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced breakdown spectroscopy (LIBS) and laser ablation time-of-flight mass spectrometry (LA-TOF-MS). In this work, LIBS methodology was employed using three different configurations: standard LIBS, LIBS with an applied magnetic field, and LIBS with both an applied magnetic field and target sample heating within an optimal temperature range. Elements from the REE group, specifically lanthanum (La), cerium (Ce), and neodymium (Nd), were identified and quantified. To detect, quantify, and validate the results from LIBS and LA-TOF-MS, we utilized an array of analytical techniques—Energy-Dispersive X-ray Spectroscopy (EDX), Energy-Dispersive X-ray Fluorescence Spectrometer (ED-XRF), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Interestingly, the quantitative results for REEs (La, Ce, and Nd) in the ore samples obtained using the LIBS technique with various configurations were found to be in agreement with those from LA-TOF-MS, EDX, XRF, and ICP-OES. In addition, LIBS enables detailed microchemical imaging, allowing the map of the spatial distribution of elements within the mineral–ore matrix. The high-resolution microscale elemental mapping of REEs was accomplished using the emission lines Ce (II) at 446.0 nm, La (II) at 492.1 nm, and Nd (II) at 388.8 nm. By integrating multiple analytical techniques, our study enabled the construction of a complete elemental distribution map, providing new insights into the geochemical processes and mineral composition of rare earth ores, while advancing geochemistry and contributing valuable data for rare earth resource exploration. Full article

This study investigates the removal efficiency of Cu²⁺ from wastewater using a composite hydrogel made of carbon nanotubes (CNTs), sodium alginate (SA), and polyacrylic acid (PAA) prepared by free radical polymerization. The CNTs@SA/PAA hydrogel’s structure and properties were characterized using SEM, TEM, FTIR, XRD, rheology, DSC, EDS, elemental mapping analysis, and swelling. The adsorption performance for Cu²⁺ was tested in batch adsorption experiments, considering the pH, dosage, initial concentration, and contact time. The optimal conditions for Cu²⁺ removal were pH 5.0, an adsorbent dosage of 500 mg/L, and a contact time of 360 min. The adsorption followed pseudo-second order kinetics. Isotherm analyses (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Sips, Toth, and Khan) revealed that the Freundlich isotherm best described the adsorption, with a maximum capacity of 358.52 mg/g. A thermodynamic analysis indicated that physical adsorption was the main interaction, with the spontaneity of the process also demonstrated. This study highlights the high efficiency and environmental friendliness of CNT@SA/PAA composites for Cu²⁺ removal from wastewater, offering a promising approach for water treatment. Full article

Underground hydrogen storage (UHS) is one potential solution that could provide a steady source of clean energy to the globe. Given their infrastructure, depleted hydrocarbon reservoirs may be a suitable storage option. However, ensuring wellbore integrity is a significant challenge when storing hydrogen in such reservoirs. In this study, 3.81 × 7.62 cm cement samples were cured for 12 and 18 months and were cyclically exposed to hydrogen for three 28-day cycles at 10.34 MPa and 50 °C. The pressure increment was achieved at the rate of 2.06 MPa/hr. The cement’s porosity, permeability, and ultrasonic velocity were tested before and after each cycle. To investigate the changes in the surface structure and elemental composition, scanning electron microscopy (SEM) was conducted. The results illustrate increased porosity and permeability, but the ultrasonic velocity changes were insignificant. The SEM images do not exhibit any change in the microstructure. However, energy dispersive spectroscopy (EDS) mapping exhibited mineral dissolution. This study demonstrates how cyclic exposure to hydrogen will affect the integrity and the sealing ability of aged cement, which will be an essential factor to consider while repurposing existing oil and gas wells to hydrogen injectors or producers for UHS applications in depleted hydrocarbon reservoirs. Full article

In the 19th century, the weighting of silk with metal salts, such as tin, was a common practice to enhance certain properties of silk fabrics and compensate for the weight loss incurred during the degumming process. This technique induces both physical and chemical modifications to the fibres, contributing to their long-term degradation, which requires thorough investigation. This study aims to examine the structural changes in silk fibres caused by the accumulation of metal salts from the tin-weighting process, using mock-up samples prepared through successive loading with weighting agents using a traditional tin-phosphate treatment method. Unweighted and tin-weighted silk samples were compared using scanning electron (SEM) micrographs, which presented the dispersed nanoparticles on the fibres, while through energy-dispersive X-ray spectroscopy (EDS) elemental mapping, the presence and uniform distribution of the weighting agents were confirmed. Fourier-transform infrared spectroscopy (FTIR) analysis revealed structural changes in tin-weighted silk samples compared to untreated ones, including shifts in amide bands, altered water/hydroxyl and skeletal stretching regions, and increased skeletal band intensities suggesting modifications in hydrogen bonding, β-sheet content, and structural disorder without significantly impacting the overall crystallinity index. X-ray diffraction (XRD) analysis of both pristine and tin-weighted silk samples revealed significant alterations, predominantly in the amorphous regions of the silk upon weighting. These structural changes were further examined using small-angle X-ray scattering (SAXS) and small- and wide-angle X-ray scattering (SWAXS), which provided detailed insights into modifications occurring at the nanometre scale. The analyses suggested disruptions in β-sheet crystals and intermolecular packing, especially in the amorphous regions, with increasing amounts of tin-weighting. Contact angle analysis (CA) revealed that the tin-phosphate-weighting process significantly impacted silk surface properties, transforming it from moderately hydrophobic to highly hydrophilic. These changes indicate that the incorporation of tin-phosphate nanoparticles on and within silk fibres could restrict the flexibility of polymer chains, impacting the physical properties and potentially the degradation behaviour of silk textiles. By studying these structural changes, we aim to deepen our understanding of how tin-weighting impacts silk fibre structure, contributing valuable insights into the longevity, conservation, and preservation strategies of silk textiles in the context of cultural heritage. Full article

Herein, this study has examined the influence of Zn²⁺ sources during a biogenic-mediated pathway to synthesize ZnO nanoparticles with highly desirable solar-responsive catalytic properties. Salts of nitrate, acetate and chloride have been utilized. The ZnO powders underwent characterization using diverse analytical tools, including XRD, FTIR, Raman, BET, SEM, TEM with EDS/elemental mapping and UV-vis absorption/emission spectroscopic analyses. Accordingly, precursors have proved to affect crystallinity, morphology, surface characteristics, optical properties and the photocatalytic degradation of methylene blue (MB) model pollutant. It was observed that ZnO derived from zinc acetate precursor (Z-AC NPs) exhibits very fast photocatalytic degradation of MB at pH 11 with superior kinetic estimates of 0.314 min⁻¹ and t_1/2 = 2.2 min over many of recent reports. In contrast, the chloride precursor is not recommended along with the employed biogenic route. The intriguing findings could be directly correlated to the decreased crystal size, augmented surface area, the hexagonal morphology of the crystals, high potency in absorbing visible photons, high efficacy in separating photogenerated charge carriers and producing high amounts of ^•OH radicals. Further testing of Z-AC NPs in photocatalytic remediation of water samples from Dumat Aljandal Lake in Aljouf, Saudi Arabia, contaminated with MB and pyronine Y (PY) dyestuffs, showed high dye photodegradation. Therefore, this work could lead to an extremely fast avenue for decontaminating wastewater from hazmat dyestuff. Full article

A novel graphene-based composite, 5-methyl-1,3,4-thiadiazol-2-amine (MTA) covalently functionalized graphene oxide (GO-MTA), was rationally developed and used for the selective sorption of Ga³⁺ from aqueous solutions, showing a higher adsorption capacity (48.20 mg g⁻¹) toward Ga³⁺ than In³⁺ (15.41 mg g⁻¹) and Sc³⁺ (~0 mg g⁻¹). The adsorption experiment’s parameters, such as the contact time, temperature, initial Ga³⁺ concentration, solution pH, and desorption solvent, were investigated. Under optimized conditions, the GO-MTA composite displayed the highest adsorption capacity of 55.6 mg g⁻¹ toward Ga³⁺. Moreover, a possible adsorption mechanism was proposed using various characterization methods, including scanning electron microscopy (SEM) equipped with X-ray energy-dispersive spectroscopy (EDS), elemental mapping analysis, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Ga³⁺ adsorption with the GO-MTA composite could be better described by the linear pseudo-second-order kinetic model (R² = 0.962), suggesting that the rate-limiting step may be chemical sorption or chemisorption through the sharing or exchange of electrons between the adsorbent and the adsorbate. Importantly, the calculated q_e value (55.066 mg g⁻¹) is closer to the experimental result (55.60 mg g⁻¹). The well-fitted linear Langmuir isothermal model (R² = 0.972~0.997) confirmed that an interfacial monolayer and cooperative adsorption occur on a heterogeneous surface. The results showed that the GO-MTA composite might be a potential adsorbent for the enrichment and/or separation of Ga³⁺ at low or ultra-low concentrations in aqueous solutions. Full article

Human mesenchymal stromal cells (hMSCs), whether used alone or together with three-dimensional scaffolds, are the best-studied postnatal stem cells in regenerative medicine. In this study, innovative composite scaffolds consisting of a core–shell architecture were seeded with bone-marrow-derived hMSCs (BM-hMSCs) and tested for their biocompatibility and remarkable capacity to promote and support bone regeneration and mineralization. The scaffolds were prepared by grafting three different amounts of gelatin–chitosan (CH) hydrogel into a 3D-printed polylactic acid (PLA) core (PLA-CH), and the mechanical and degradation properties were analyzed. The BM-hMSCs were cultured in the scaffolds with the presence of growth medium (GM) or osteogenic medium (OM) with differentiation stimuli in combination with fetal bovine serum (FBS) or human platelet lysate (hPL). The primary objective was to determine the viability, proliferation, morphology, and spreading capacity of BM-hMSCs within the scaffolds, thereby confirming their biocompatibility. Secondly, the BM-hMSCs were shown to differentiate into osteoblasts and to facilitate scaffold mineralization. This was evinced by a positive Von Kossa result, the modulation of differentiation markers (osteocalcin and osteopontin), an expression of a marker of extracellular matrix remodeling (bone morphogenetic protein-2), and collagen I. The results of the energy-dispersive X-ray analysis (EDS) clearly demonstrate the presence of calcium and phosphorus in the samples that were incubated in OM, in the presence of FBS and hPL, but not in GM. The chemical distribution maps of calcium and phosphorus indicate that these elements are co-localized in the same areas of the sections, demonstrating the formation of hydroxyapatite. In conclusion, our findings show that the combination of BM-hMSCs and PLA-CH, regardless of the amount of hydrogel content, in the presence of differentiation stimuli, can provide a construct with enhanced osteogenicity for clinically relevant bone regeneration. Full article