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ZrO2 Nanoflowers Decorated with Graphene Quantum Dots for Electrochemical Immunosensing
摘要： In present work, hybrid nanostructures of graphene quantum dots decorated zirconia (GQDs@ZrO2) synthesized by facile one-pot hydrothermal method and utilized as an efficient electrochemical sensing probe. The hydrothermal method involved carbonization of citric acid into GQDs and growth of ZrO2 NPs, simultaneously. The electron microscopic images visualized nanoflower structure of GQDs@ZrO2 nanostructures having an average diameter of 17–3.5 nm. X-ray photoelectron spectroscopic, zeta potential, UV-visible and fluorescence characterizations have validated the existence of ZrO2 NPs and GQDs in the synthesized GQDs@ZrO2 nanostructures. The GQDs@ZrO2 hybrid prevented re-stacking of GQDs and provided adequate availability of functional groups and high electron transport rate, which resulted in improved electrochemical biosensing performance. The oxygen moieties associated with the GQDs@ZrO2/ITO electrode offer an excellent environment for covalent attachment of antibodies. Fabricated BSA/anti-OTA/GQDs@ZrO2/ITO immunosensor revealed enhanced biosensing parameters such as detection range of 1–20 ng/mL, the sensitivity of 5.62 μA mL/ng cm2, limit of detection of 0.38 ng/mL and an average of 95% recovery of ochratoxin-A from the spiked coffee sample.
关键词： Biosensor,Ochratoxin A,Electrochemical,Graphene Quantum Dots,Zirconia
更新于2025-09-19 17:13:59
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Effects of Milling Time, Zirconia Addition, and Storage Environment on the Radiopacity Performance of Mechanically Milled Bi2O3/ZrO2 Composite Powders
摘要： Mineral trioxide aggregate (MTA) typically consists of Portland cement (75 wt.%), bismuth oxide (20 wt.%), and gypsum (5 wt.%) and is commonly used as endodontic cement. Bismuth oxide serving as the radiopacifying material reveals the canal filling effect after clinical treatment. In the present study, bismuth/zirconium oxide composite powder was prepared by high energy ball milling of (Bi2O3)100?x (ZrO2)x (x = 5, 10, 15, and 20 wt.%) powder mixture and used as the radiopacifiers within MTA. The crystalline phases of the as-milled powders were examined by the X-ray diffraction technique. The radiopacities of MTA-like cements prepared by using as-milled composite powders (at various milling stages or different amount of zirconia addition) were examined. In addition, the stability of the as-milled powders stored in an ambient environment, an electronic dry box, or a glove box was investigated. The experimental results show that the as-milled powder exhibited the starting powder phases of Bi2O3 and ZrO2 and the newly formed δ-Bi7.38Zr0.62O2.31 phase. The longer the milling time or the larger the amount of the zirconia addition, the higher the percentage of the δ-Bi7.38Zr0.62O2.31 phase in the composite powder. All the MTA-like cements prepared by the as-milled powder exhibited a radiopacity higher than 4 mmAl that is better than the 3 mmAl ISO standard requirement. The 30 min as-milled (Bi2O3)95(ZrO2)5 composite powder exhibited a radiopacity of 5.82 ± 0.33 mmAl and degraded significantly in the ambient environment. However, storing under an oxygen- and humidity-controlled glove box can prolong a high radiopacity performance. The radiopacity was 5.76 ± 0.08 mmAl after 28 days in a glove box that was statistically the same as the original composite powder.
关键词： mineral trioxide aggregates,radiopacity,bismuth oxide,mechanical milling,zirconia
更新于2025-09-19 17:13:59
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Zirconia quantum dots for a nonvolatile resistive random access memory device
摘要： We propose a nonvolatile resistive random access memory device by employing nanodispersion of zirconia (ZrO2) quantum dots (QDs) for the formation of an active layer. The memory devices comprising a typical sandwich structure of Ag (top)/ZrO2 (active layer)/Ti (bottom) are fabricated using a facile spin-coating method. The optimized device exhibits a high resistance state/low resistance state resistance difference (about 10 Ω), a good cycle performance (the number of cycles larger than 100), and a relatively low conversion current (about 1 μA). Atomic force microscopy and scanning electron microscope are used to observe the surface morphology and stacking state of the ZrO2 active layer. Experimental results show that the ZrO2 active layer is stacked compactly and has a low roughness (Ra=4.49 nm) due to the uniform distribution of the ZrO2 QDs. The conductive mechanism of the Ag/ZrO2/Ti device is analyzed and studied, and the conductive filaments of Ag ions and oxygen vacancies are focused on to clarify the resistive switching memory behavior. This study offers a facile approach of memristors for future electronic applications.
关键词： Resistive switching,Spin coating,Memory device,Zirconia quantum dot
更新于2025-09-19 17:13:59
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Effect of different laser types on bonding strength of CAD/CAM-customized zirconia post to root canal dentin: an experimental study
摘要： In clinical dentistry, the strength of bonding zirconia posts to root canal dentinal walls currently needs enhancement, and laser application can be an important contribution owing to its features that accommodate adjustable modifications on dental materials. Herein, the effect of different laser treatments applied to dentin surfaces on the strength of bonding zirconia posts to root canal dentinal walls is evaluated by using the pull-out bond strength test in a laboratory setting. A total of 40 single-rooted permanent mandibular premolar teeth that were freshly extracted were used here. The root canal preparation steps were performed using the crown-down technique. Custom-made zirconia posts were produced using CAD/CAM technology. Prior to the application of resin cement, the internal surfaces of the root canals were irradiated using Nd:YAG, Er:YAG, and KTP lasers. Pull-out tests were performed on each specimen by using a universal testing machine. One-way analysis of variance and Tukey post hoc tests were used to compare the pull-out bond strength data. The bond strengths of the laser-treated specimens were greater than those of the untreated controls (p < 0.05). While the value of the pull-out bond strength after Nd:YAG laser treatment was significantly higher than the values obtained after the applications of the Er:YAG and KTP lasers (p < 0.05), the pull-out bond strength after Er:YAG laser treatment was considerably greater than that after KTP laser treatment (p < 0.05). The bond strength between the root canal dentin and the CAD/CAM custom-made zirconia post was improved upon using all the laser modalities in current laboratory settings, among which, application of the Nd:YAG laser was the most successful.
关键词： KTP laser,Zirconia post,Nd:YAG laser,Dentin treatment,Er:YAG laser,Pull-out bond strength
更新于2025-09-19 17:13:59
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[IEEE 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Manama, Bahrain (2019.4.15-2019.4.17)] 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Numerical Study of Laser Hole Cutting in Zirconia Toughened Alumina Plate
摘要： The main cause of cracks formation in laser cut holes is due to thermal stress. These formed cracks alter the mechanical properties of work material and degrade the cut hole quality. Therefore thermal analysis of laser cut holes become essential. Laser cutting of structural ceramic possess extra constraints due to their brittle nature. In present paper, laser cutting of hole in Zirconia Toughened Alumina ceramic plate is simulated to investigate the temperature and stress profile. The numerically predicted results show that maximum temperature of 3300 °C is developed near the cut hole region whereas maximum stress of 5 GPa is observed.
关键词： Laser cutting,Zirconia Toughened Alumina,Temperature,Stress
更新于2025-09-12 10:27:22
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Effect of repeated laser surface treatments on shear bond strength between zirconia and veneering ceramic
摘要： Statement of problem. Delamination failure may occur between ceramic frameworks and veneering ceramics, shortening the lifetime of ?xed dental prostheses in load-bearing areas. Purpose. The purpose of this in vitro study was to compare the effect of different repeating CO2 laser treatment methods and conventional approaches on the shear bond strength of zirconia frameworks and veneering ceramics. Material and methods. Zirconia disks (N=110) were prepared and divided into 5 groups: milling without surface treatment (group M), airborne-particle abrasion (group APA), single laser treatment (group LX1), 2 laser treatments (group LX2), and 3 laser treatments (group LX3). The specimens in the ?rst 2 groups were treated before the framework was coated using the spraying technique. Specimens in the remaining groups were coated with veneering ceramic using the spraying process, and then subjected to laser treatment. Surface roughness and topography, interface properties, phase transformation, shear bond strength, and fracture modes were investigated. Outcomes were analyzed using a pro?lometer, a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), a stereomicroscope, and a universal testing machine for mechanical testing. Results. The XRD showed that phase transformation from tetragonal to monoclinic occurred after airborne-particle abrasion. This phenomenon was not observed in laser-treated specimens. Groups LX2 and LX3 had the highest surface roughness values, 1.18 ±0.23 mm and 1.21 ±0.22 mm, among all groups, and group LX3 had the highest shear bond strength values for unaged and aged conditions, 32.08 ±2.45 MPa and 31.43 ±2.07 MPa. The mixed-fracture mode was the most common type of fracture observed. Conclusions. The results indicated that the shear bond strength between the zirconia framework and veneering ceramic was higher after laser surface treatments than after milling alone or after airborne-particle abrasion. Laser treatment methods, particularly LX2 and LX3, could be considered reliable approaches for zirconia surface treatment.
关键词： veneering ceramic,laser treatment,zirconia,shear bond strength,surface roughness
更新于2025-09-12 10:27:22
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Low-power laser-induced absorption in YSZ ceramics through formation of F-centers
摘要： Infrared lasers, especially those having a wavelength of either 10.6 μm or 1.06 μm are of great technological importance. Unfortunately, many dielectric materials, such as common ceramics absorb very poorly the latter wavelength since it falls within their large bandgap. However, some materials do not follow this general trend and strongly absorb moderate-energy-density (10–100 J/cm2) laser radiation of both types, although their bandgap extends into the infrared far beyond 1 μm and contains no intrinsic energy levels. The present study was motivated by the observation that IR-laser melting of some of these oddly behaving materials seems to be accompanied by appearance of strong visible absorption. The evolution of the optical properties and crystal structure of one of them, YSZ, as well as that of alumina, having a regular behavior, was studied by optical microscopy, SEM, XRD, Raman spectroscopy, optical spectroscopy and DRIFTS. As a result, it was shown for the first time that the melting of YSZ by 1.06 μm laser radiation is only possible due to F-centers forming in the tetragonal structure of the material, giving rise to a broad absorption continuum, which covers the entire bandgap of the material, including that wavelength, and when F-centers generation is inhibited, melting does not occur anymore. In order to explain that phenomenon, the possibility of multiple energy levels arising within the band gap because of F-center coupling and anisotropy was studied theoretically. Thus, a simple model was constructed, representing F-center clusters as coupled potential wells with variable separations between them and variable effective electron mass due to anisotropy. The model with just two wells produced multiple energy states distributed throughout the bandgap of the material, thus offering support for said hypothesis.
关键词： Absorption,Blackening,Zirconia,F-center,Ceramics,Laser
更新于2025-09-12 10:27:22
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Surface Micro patterning of Aluminium Reinforced Composite for Aerospace Applications through High Energy Pulse Laser Peening
摘要： Aluminium (Al) Composites have universal engineering applications because of their higher strength to weight ratio, ductility, and formability. However, in diverse applications, mechanical properties such as hardness, corrosion, wear, and fatigue resistance are the prerequisite at closer surface regions. Such localised changes without impacting various surface treatment approaches can attempt the bulk phase. Laser shock peening is an advanced surface engineering technique, which has been successfully applied to improve the surface morphology and microstructure of the material. In this work, we are focusing on improving the surface properties of Al7075 reinforced with SiC and Zirconia through laser peening technique. The hardened layer was evaluated using surface integrity with optical microscopy, energy dispersive spectroscopy, scanning electron microscope (SEM) and analysis of microhardness. Process parameters and resulting microstructures of Aluminium composite are summarised, along with the impact of laser peening on surface properties. Research results indicated that laser peening shows a significant influence on the final condition of the surface layer of Aluminium composite.
关键词： Zirconia,Aluminium Metal Matrix Composites,SiC,SEM,Laser peening
更新于2025-09-12 10:27:22
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Influence of Er,Cr:YSGG Laser Irradiation on the Push-Out Bond Strength of Zirconia and Glass Fiber Posts with Radicular Dentin
摘要： Objective. This in vitro study was designed to evaluate the influence of an Er,Cr:YSGG laser on the bond strength of zirconia and glass fiber posts with root dentin. Materials and methods. Ninety extracted single-rooted human teeth were randomized into 6 groups (n = 15/group) on the basis of different posts (zirconia/glass fiber) and Er,Cr:YSGG laser tips (axial and radial). Specimens were prepared for push-out testing with the help of a cutting machine; six slices (2 on each cervical, middle, and apical) of approximately 1 mm thickness were sectioned for all roots on a plane perpendicular to the long axis of the post. All specimens were placed into a universal testing machine with a defined 0.5 mm/min crosshead speed until the maximum failure load was obtained. Results. The highest mean push-out bond strength of the glass fiber and zirconia groups was achieved with laser treatment. The highest push-out bond strength was achieved with the axial fiber tip (7.63 ± 1.22 MPa), and the lowest was achieved with a radial fiber tip of the glass fiber group (6.98 ± 0.96 MPa). ANOVA showed a statistically significant difference between the groups (p ? 0.041). The mean push-out bond strength was found to be higher with an axial fiber tip for both cervical and apical segments in the glass fiber and zirconia groups (p < 0.05). The independent t-test resulted in the overall highest mean push-out bond strength in the apical segments (p ? 0.026). Conclusion. Within the limits of the present in vitro research study, an enhancement in the push-out bond strength of resin cement, mainly in the cervical region of the root canal, was achieved after irradiation with an Er,Cr:YSGG laser using an axial fiber tip.
关键词： root dentin,push-out bond strength,Er,Cr:YSGG laser,glass fiber posts,zirconia posts
更新于2025-09-12 10:27:22
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Synthesis, Characterization,and Photocatalytic activity of Silver nanoparticledoped Phosphomolybdic acid supportedZirconia
摘要： An ecofriendly solid acid catalyst was synthesized by impregnating phosphomolybdic acid on zirconia followed by doping with Silver nanoparticles to form composite. We report here, the synthesis, characterization and photocatalytic behavior of AgNPs doped Keggin Ions/ Zirconia which is synthesized by wet impregnation method. The resulting nanocomposite was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. The photocatalytic activity of the catalyst was evaluated for the degradation of azo dye under the Visible light irradiation. In the photoreaction study, it is found that photocatalytic activity increases by doping the noble metal silver nanoparticles on PMA/ZrO2 surface to form the composite.
关键词： Phosphomolybdic acid,Zirconia,Methylene blue dye,Photocatalytic activity
更新于2025-09-12 10:27:22