Search Results (381)

This study investigated the radiation attenuation characteristics of commonly used dental implant materials across an energy spectrum relevant to dental radiology. Two titanium implants were examined, with densities of 4.428 g/cm³ and 4.51 g/cm³, respectively. The first consisted of 90.39% titanium, 5.40% aluminum, and 4.21% vanadium, while the second comprised 58% titanium, 33% oxygen, 7% iron, 1% carbon, and 1% nitrogen. The third material was a zirconia implant (5Y form) composed of 94.75% zirconium dioxide, 5.00% yttrium oxide, and 0.25% aluminum oxide, exhibiting a higher density of 6.05 g/cm³. Monte Carlo simulations (MCNP6) and XCOM data were utilized to estimate photon source parameters, geometric configuration, and interactions with biological materials to calculate the half-value layer, mean free path, and tenth-value layer at varying photon energies. The results indicated that titanium alloys are well suited for low-energy imaging modalities such as CBCT and panoramic radiography due to their reduced artifact production. While zirconia implants demonstrated superior attenuation at higher energies (e.g., CT), their higher density may induce beam-hardening artifacts in low-energy systems. Future research should validate these simulation results through in vitro and clinical imaging and further explore the correlation between material-specific attenuation and CBCT image artifacts. Full article

Hydroxyapatite (HAP) is the most widely accepted biomaterial for repairing bone tissue defects, demonstrating excellent biocompatibility and bioactivity that promote new bone formation. Zirconia (ZrO₂), known for its strength and fracture toughness, is commonly used to reinforce ceramics. In this study, magnesium oxide (MgO) served as a stabilizer for zirconia, resulting in magnesia partially stabilized zirconia (Mg-PSZ). Both Mg-PSZ and HAP were synthesized via coprecipitation and mixed in specific ratios to create composites through a ceramic method involving mixing, compaction, and sintering at 1100 °C. The samples were characterized using techniques such as X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). Structural analyses confirmed the presence of both monoclinic and tetragonal zirconia phases. Besides, the increased wt.% HAP in the composites produced distinct peaks for hexagonal HAP. Crystallite sizes ranged from 27.45 nm to 31.5 nm, and surface morphology was homogeneous with small pores. Elements such as calcium, phosphorus, magnesium, zirconium, and oxygen were detected in all samples. This research also examined microhardness changes in the materials. The findings revealed enhancement in microhardness for the biocomposite with higher zirconia content, 90Mg-PSZ/10HAP sample, with the smallest average pore size, highlighting its potential for biomedical applications. Full article

Nd–Fe–B permanent magnets are vital for numerous key technologies in strategic sectors such as renewable energy production, e-mobility, defense, and aerospace. Accordingly, the demand for rare earth elements (REEs) enormously increases in parallel to a significant uncertainty in their supply. Thus, research and innovative studies are focus on the investigation of sustainable solutions to the problem and a closed-loop value chain. The present study is based on two benign-by-design approaches aimed at decreasing the recycling loop span by preparing standardized batches of EoL Nd–Fe–B materials to be treated separately depending on their properties, as well as using mechanochemical method for waste processing. The previously reported benefits of both direct recycling and mechanochemistry include significant improvements in processing metrics, such as energy use, ecological impact, technology simplification, and cost reduction. Waste-sintered Nd–Fe–B magnets from motorbikes were collected, precisely sorted, selected, and pre-treated. The study presents a protocol of resource-efficient recycling through mechanochemical processing of non-oxidized sintered EoL magnets, involving the extraction of Nd₂Fe₁₄B magnetic grains and refining the material’s microstructure and particle size after 120 min of high-energy ball milling in a zirconia reactor. The recycled material preserves the main Nd₂Fe₁₄B magnetic phase, while an anisotropic particle shape and formation of a thin Nd/REE-rich layer on the grain surface were achieved. Full article

The aim of this study was to develop an experimental self-etch dental adhesive (SE) by synthesizing graphene oxide–functionalized zirconia (GO-ZrO₂) and hydroxyapatite–functionalized zinc (HA-Zn) as inorganic powders together with bis-GMA _(0–2) (bisphenol A-glycidyl methacrylate) oligomers as main components of the organic matrix. The adhesive was compared to the current gold standard adhesive Clearfill SE Bond 2 (CSE) using cytotoxicity assays, shear bond strength (SBS) tests, and resin–dentin interface analyses. Cytotoxicity assays with human gingival fibroblasts (HGF-1) revealed reduced cell viability at early time points but indicated favourable biocompatibility and potential cell proliferation at later stages. SBS values for the experimental adhesive were comparable to CSE after 24 h of storage while aging did not significantly affect its bond strength. However, SBS exhibited more consistent resin tag formation and higher Weibull modulus values post-aging. A scanning electron microscopy (SEM) analysis highlighted differences in resin tag formation, suggesting the experimental adhesive relies more on chemical bonding than micromechanical interaction. The experimental adhesive demonstrated promising potential clinical properties and bond durability due to the integration of GO-ZrO₂ and HA-Zn fillers into the adhesive. Full article

The present study aims to investigate a Pd catalyst on a complex multi-oxide medium-entropy support interlayer La₂O₃-CeO₂-ZrO₂-Al₂O₃ and its possible use as catalysts for methane abatement applications. The low-temperature N₂-adsorption, XRD, TEM, XPS, TPD, and TPR techniques were used to characterize the catalyst. The palladium deposition on the supports leads to the formation of PdO. After the catalytic tests, the metal-Pd phase was observed. The complete oxidation of methane on Pd/La-Ce-Zr-Al catalyst takes place at temperatures above 250 °C, and in the presence of water vapor, the reaction temperature increases to about 70 °C. The careful choice of constituent oxides provides a balance between structural stability and flexibility. The alumina and lanthanum oxide ensure the high specific surface area, while the simultaneous presence of zirconia and ceria leads to the formation of a mixed-oxide phase able to interact with palladium ions by incorporating and de-incorporating them at different conditions. The mechanism of Mars–van Kerevelen was considered as the most probable for the reaction of complete methane oxidation. The possibility of the practical application of Pd-modified La-Ce-Zr-Al catalyst is evaluated. The use of a mix of multiple rare and abundant oxides makes the proposed catalyst a cost-effective alternative. Full article

Nanotopography refers to the intricate surface characteristics of materials at the sub-micron (<1000 nm) and nanometer (<100 nm) scales. These topographical surface features significantly influence the physical, chemical, and biological properties of biomaterials, affecting their interactions with cells and surrounding tissues. The development of nanostructured surfaces of polymeric nanocomposites has garnered increasing attention in the fields of tissue engineering and regenerative medicine due to their ability to modulate cellular responses and enhance tissue regeneration. Various top-down and bottom-up techniques, including nanolithography, etching, deposition, laser ablation, template-assisted synthesis, and nanografting techniques, are employed to create structured surfaces on biomaterials. Additionally, nanotopographies can be fabricated using polymeric nanocomposites, with or without the integration of organic and inorganic nanomaterials, through advanced methods such as using electrospinning, layer-by-layer (LbL) assembly, sol–gel processing, in situ polymerization, 3D printing, template-assisted methods, and spin coating. The surface topography of polymeric nanocomposite scaffolds can be tailored through the incorporation of organic nanomaterials (e.g., chitosan, dextran, alginate, collagen, polydopamine, cellulose, polypyrrole) and inorganic nanomaterials (e.g., silver, gold, titania, silica, zirconia, iron oxide). The choice of fabrication technique depends on the desired surface features, material properties, and specific biomedical applications. Nanotopographical modifications on biomaterials’ surface play a crucial role in regulating cell behavior, including adhesion, proliferation, differentiation, and migration, which are critical for tissue engineering and repair. For effective tissue regeneration, it is imperative that scaffolds closely mimic the native extracellular matrix (ECM), providing a mechanical framework and topographical cues that replicate matrix elasticity and nanoscale surface features. This ECM biomimicry is vital for responding to biochemical signaling cues, orchestrating cellular functions, metabolic processes, and subsequent tissue organization. The integration of nanotopography within scaffold matrices has emerged as a pivotal regulator in the development of next-generation biomaterials designed to regulate cellular responses for enhanced tissue repair and organization. Additionally, these scaffolds with specific surface topographies, such as grooves (linear channels that guide cell alignment), pillars (protrusions), holes/pits/dots (depressions), fibrous structures (mimicking ECM fibers), and tubular arrays (array of tubular structures), are crucial for regulating cell behavior and promoting tissue repair. This review presents recent advances in the fabrication methodologies used to engineer nanotopographical microenvironments in polymeric nanocomposite tissue scaffolds through the incorporation of nanomaterials and biomolecular functionalization. Furthermore, it discusses how these modifications influence cellular interactions and tissue regeneration. Finally, the review highlights the challenges and future perspectives in nanomaterial-mediated fabrication of nanotopographical polymeric scaffolds for tissue engineering and regenerative medicine. Full article

Chromium (Cr) contamination poses severe risks to plant health and soil quality, requiring sustainable remediation methods. This study explored the synthesis of zirconia nanoparticles (PF-ZrO₂ NPs) from Sonchus asper extract and assessed their potential to alleviate Cr toxicity in Chinese cabbage (Brassica rapa var. pekinensis). The characterization of nanoparticles was performed through XRD, SEM, and FTIR analyses, confirming their crystalline nature, structure, and surface chemistry. The results indicated significant declines in plant growth, chlorophyll content, biomass, and nutrient uptake under Cr stress (treatments T2 and T4), accompanied by elevated oxidative stress indicators (H₂O₂, MDA) and Cr accumulation. The application of PF-ZrO₂ NPs (T3 and T5) notably reduced shoot Cr concentrations (by 58.94% and 35.90%) and improved the chlorophyll level (by 5.41% and 14.41%). Additionally, nanoparticles increased antioxidant enzyme activity (SOD, POD, CAT) and improved soil properties (pH, cation exchange capacity, nutrient retention). These findings suggest green-synthesized PF-ZrO₂ NPs are effective, environmentally friendly candidates for Cr remediation in contaminated soils. Full article

In this work, a novel potential thermal barrier coating material entropy-stabilized titanium–aluminum oxide (La_0.25Ce_0.25Nd_0.25Sm_0.25)Ti₂Al₉O₁₉ (META) was successfully synthesized by the solid-state reaction method, and its thermophysical properties, phase stability, infrared emissivity, mechanical properties, and CMAS corrosion resistance were systematically investigated. The results demonstrated that META exhibits low thermal conductivity at 1100 °C (1.84 W·(m·K)⁻¹), with a thermal expansion coefficient (10.50 × 10⁻⁶ K⁻¹, 1000–1100 °C) comparable to yttria-stabilized zirconia (YSZ). Furthermore, META displayed desirable thermal stability, high emissivity within the wavelength range of 2.5–10 μm, and improved mechanical properties. Finally, META offers superior corrosion resistance due to its excellent infiltration inhibiting. The bi-layer structure on the corrosion surface prevents the penetration of the molten CMAS. Additionally, doping small-radius rare-earth elements thermodynamically stabilizes the reaction layer. The results of this study indicate that (La_0.25Ce_0.25Nd_0.25Sm_0.25)Ti₂Al₉O₁₉ has the potential to be a promising candidate for thermal barrier coating materials. Full article

Using nanomaterials to replace part of cement is one of the effective ways to enhance the performance of cement-based materials. In this study, the response surface analysis method was used to design an experiment. Through tests on the mechanical properties, the coefficient of water saturation, the shrinkage properties, and the high-temperature calcination of cement-based materials, the effects of three factors, namely, the substitution amount of nano-zinc oxide for cement, the substitution amount of nano-zirconia for cement, and the water–cement ratio, on cement-based materials under different conditions were compared and analyzed. The lower limit of the compressive strength of the cement-based materials increased by 88.17%, and the upper limit increased by 15.14% by using nano-zinc oxide and nano-zirconia to replace part of the cement. The compressive strength of cement-based materials with a nano-zinc oxide content in the range of 0.4–0.6% was low because of the low content of CSH. The coefficient of water saturation decreased with an increase in age, and the coefficient of water saturation of high-performance concrete was low. Nano-zirconia had a significant effect on the mass loss of autogenous shrinkage and the mass loss of drying shrinkage. When the substitution amount of nano-zinc oxide was 0.4–0.8%, the mass loss was large. In summary, with its unique microscopic characteristics, nanomaterials could significantly improve the performance of cement-based materials with regards to their mechanical properties, durability, workability, and other aspects. Full article

Our planet is currently facing dual challenges of global warming and energy crisis. The heavy reliance of the energy sector on fossil fuels significantly contributes to the accumulation of greenhouse gases, such as CH₄ and CO₂, in the environment atmosphere, exacerbating global warming. Stabilized zirconia-based material offer a promising solutions to address both challenges. As a catalytic support material, active sites incorporated stabilized-zirconia can facilitate the conversions of greenhouse gases like CH₄ and CO₂ into syngas (H₂ and CO). This reaction is popularly known as dry reforming of methane (DRM). Additionally, stabilized zirconia-based materials act as solid-state electrolyte in fuel cells enabling the electrochemical conversion of H₂ and O₂ to generate electricity. Both processes require high-temperature stability and oxide ionic conductivity, making “Ca, Mg, Sc, Y-stabilized zirconia” an optimal choice. In DRM, the key factors influencing catalytic efficiency include metal–support interaction, reducibility, and basicity. Meanwhile, for solid oxide fuel cells, performance is governed by factors such as size-fit, charge imbalance, dopant miscibility, ion conducting phases, densification, electrolyte thickness, and grain boundary volume. This compressive review explores the dual functionality of “Ca, Mg, Sc, Y-stabilized zirconia” as a catalyst’support for DRM and as an solid electrolyte for fuel cells. The most promising research outcomes are highlighted, and future research directions are outlined. By bringing together the catalytic and fuel cell research communities, this study aims to advance sustainable energy technologies and contribute to mitigating environmental and energy crisis through the development of stabilized zirconia-based materials. Full article

This study assessed the changes in the mechanical and surface properties of the transition zone in multilayered translucent monolithic zirconia subjected to long-term hydrothermal aging. A total of 360 disk-shaped specimens (diameter: 15.0 mm; thickness: 1.2 mm) were prepared using conventional (3Y-TZP in LT; ZL, 4Y-TZP in MT; ZM) and multilayered translucent zirconia (5Y-TZP in MT Multi; ZT, 3Y/5Y-TZP in Prime; ZP) among IPS e.max ZirCAD blocks. Specimens were divided into three groups (n = 30) and aged in the autoclave at 134 °C under 0.2 MPa for 0 h (control group), 5 h (first aged group), and 10 h (second aged group). The mechanical and surface properties of the transition zone in the multilayered translucent zirconia were investigated, followed by statistical analysis (α = 0.05). Before and after aging, ZL (1102.64 ± 41.37 MPa) and ZP (1014.71 ± 139.86 MPa) showed the highest biaxial flexural strength (BFS); ZL showed the highest Weibull modulus (31.46) and characteristic strength (1121.63 MPa); and ZT exhibited the highest nanoindentation hardness (20.40 ± 1.80 GPa) and Young’s modulus (284.90 ± 20.07 GPa). After aging, ZL (116.75 ± 9.80 nm) exhibited the highest surface roughness (Ra); the monoclinic phase contents in ZL and ZP increased; and surface uplifts, microcracks, and irregular defects caused by phase transformation appeared on ZL and ZP surfaces. The 3Y/5Y-TZP transition zone exhibited flexural strength, Vickers hardness, phase distribution changes, and surface microstructure changes similar to those of 3Y-TZP before and after aging; however, the surface roughness was lower than that of 3Y-TZP and higher than those of 4Y-TZP and 5Y-TZP after aging. The mechanical and surface characteristics, excluding BFS and Vickers hardness, were influenced by the yttrium oxide content in each zone and the aging process. Full article

Silica–zirconia nanoparticles were successfully synthesised using the precipitation process. The surface area and shape of the Si-ZrO₂ nanoparticles were investigated using BET, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (HRTEM). The HRTEM results demonstrate that silica was successfully integrated into ZrO₂ nanoparticles with a mixture of nanorod and nanosphere shapes. The element analysis (EDX) reveals the presence of silica (14.61%) and zirconia (1.18%) nanoparticles, as well as oxygen (83.65) on the surface. The BET results demonstrate a larger surface area of 185 m²/g and pore volume (0.14 cm³/g). The XRD measurements confirmed the transition of amorphous silica into the monoclinic phase of the zirconia nanoparticles. The electrochemical characteristics of the silica–zirconia nanoparticles were tested in a potassium chloride solution. With a large specific surface area and an appropriate pore size distribution, a pair of broad and symmetric redox peaks were centred at −0.15 V and 0.6 V. Full article

This study reports the preparation of a novel hybrid composite and its application in adsorption. For this composite preparation, zirconia (ZrO₂) was precipitated onto an integrated framework of reduced graphene oxide (rGO) and black cumin (BC) seeds. Characterization using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy confirmed the successful incorporation of ZrO₂ nanoparticles (5–20 nm) into the integrated carbon framework of rGO and seed powder. The microscopic analysis further revealed that the ZrO₂ NPs were dispersed throughout the integrated rGO-BC framework. Using the rGO-BC@ZrO₂ composite, methylene blue dye was decontaminated from water through a batch adsorption process. The rGO-BC@ZrO₂ composite achieved 96% MB adsorption at an adsorbent dose of 2.0 g/L, and nearly 100% when the adsorbent concentration was 3.0 g/L. Modeling of the experimental adsorption values was also established to verify the adsorption viability and mechanism. Thermodynamic modeling confirmed the feasibility and spontaneity of the present batch adsorption process. Isotherm modeling, which showed its compatibility with the Freundlich isotherm, suggested multilayer adsorption. rGO-BC@ZrO₂ demonstrated good persistence and reusability for methylene blue for up to five consecutive adsorption cycles. Thus, this study presents optimistic results regarding water purification. Full article

Niobium–graphene oxide–zirconia-toughened alumina (ZTA) composites were produced by wet mixing and spark plasma sintering. The microstructure and mechanical properties of this novel composite have been studied. The results show that niobium particles are homogeneously dispersed in the ZTA matrix. Raman spectroscopy confirmed the thermal reduction in graphene oxide during sintering. The presence of ductile metal and graphene flakes leads to an increase in the crack resistance value of the ZTA matrix. The developed composites demonstrate a fracture toughness of 16 MPa∙m^1/2, which is three times higher than ZTA ceramic composites. The high toughness values found in this new composite are a consequence of the strong interaction between the simultaneous action of several toughening mechanisms, specifically involving crack trapping, crack blunting, crack renucleation, and the bridging mechanisms of the metallic and graphene particles. Moreover, this increase has also occurred due to the enhancement of the transformability of zirconia in ceramic–metal composites. Full article

This manuscript explores the removal of eosin yellow dye, a toxic color substance contributing to water pollution, from aqueous solutions. For this purpose, iron-zirconia binary oxide (Fe₂O₃-ZrO₂) was functionalized with eugenol oil, a natural phenolic aromatic compound extracted from the clove plant. The functional groups developed in the binary oxide were confirmed by Fourier transform infrared spectroscopy (FT-IR), and its crystal structure was determined via X-ray diffraction (XRD). The grain size analyzed by the XRD pattern was found to be 45 nanometers. The morphological analysis revealed nanoparticles of quasi-spherical type with a size ranging from 4 to 5 nanometers. The consistency between SEAD and XRD further confirmed that the material formed was iron-zirconia binary oxide. The obtained material, which was insoluble in water, was used as an adsorbent. Through the adsorption study of eosin yellow dye, the maximum monolayer adsorption capacity of approximately 91.0 mg/g at 27 °C and pH = 7.0 for the functionalized adsorbent was determined. The process was exothermic, feasible, and spontaneous. At a dose of 1.0 g/L, the adsorbent was responsible for removing more than 90% of eosin yellow with 10–70 mg/L initial concentration, while about 56% removal was achieved at a higher concentration of 150 mg/L at 27 °C and pH = 7.0. These results highlight the potential of functionalized Fe₂O₃-ZrO₂ as an effective adsorbent for water purification applications. Full article