Objective: The airborne-particle abrasion of zirconia with alumina particle (APA) has been reported to result in the durable bonding of appropriate adhesive luting systems. However, whether a delay between APA and the application of the adhesive luting material might affect the resulting bond strength and its durability is unknown.
Methods: A total of 140 disc-shaped zirconia specimens were divided according to the elapsed time between the APA of zirconia and its bonding into 5 test groups (15 min, 1 h, 4 h, 24 h, and 72 h). The specimens were airborne-particle abraded with 50-μm AlO, and then stored at room temperature according to the test group (n = 28/group). Surface free energy (SFE) was measured for 12 specimens per group using a goniometer. For each group 16 Plexiglas tubes filled with composite resin were bonded to the zirconia specimens with an adhesive luting resin (Panavia 21). Tensile bond strength (TBS) was tested for subgroups of 8 specimens after water storage for 3 days and for 150 days with 37,500 thermal cycles.
Results: SFE decreased significantly within 24 h after APA. TBS after 3 days of water storage ranged from 38.3 (1 h) to 28.4 MPa (24 h) and after 150 days with thermocycling from 38.3 (15 min) to 24.8 MPa (24 h).
Significance: Based on these results, the time between the APA of zirconia and the application of adhesive materials should be minimized when bonding nonretentive zirconia restorations clinically.
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http://dx.doi.org/10.1016/j.dental.2020.12.010 | DOI Listing |
Environ Sci Technol
January 2025
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China.
Cadmium (Cd) isotopes have recently emerged as novel tracers of Cd sources and geochemical processes. Widespread clay minerals play a key role in Cd migration due to their strong adsorption capacity, but the mechanism of Cd isotope fractionation during adsorption onto clay minerals is poorly understood. Here, we experimentally investigated the adsorption mechanisms of Cd on montmorillonite (2:1) and kaolinite (1:1) by using extended X-ray absorption fine structure (EXAFS) spectroscopy.
View Article and Find Full Text PDFSci Rep
January 2025
State Key Laboratory of Structure Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, 116024, China.
The biocompatible autonomous self-healing hydrogels have great potential in biomedical applications. However, the fairly weak tensile strength of the hydrogels seriously hinders their application. Here, we introduced chitosan (CS) into the polyvinyl alcohol (PVA)-tannic acid (TA) hydrogel and investigated the effects of the CS content, as CS can not only form reversible H bonds with PVA and TA but also form reversible electrostatic interactions with TA.
View Article and Find Full Text PDFNat Commun
January 2025
Key Laboratory of Automobile Materials, Ministry of Education, Department of Materials Science and Engineering, Jilin University, 130022, Changchun, China.
Correlating the bond strength with the macro strength of metals is crucial for understanding mechanical properties and designing multi-principal-element alloys (MPEAs). Motivated by the role of grain boundaries in the strength of metals, we introduce a predictive model to determine the grain-boundary energies and strength of metals from the cohesive energy and atomic radius. This scheme originates from the d-band characteristics and broken-bond spirit of tight-binding models, and demonstrates that the repulsive/attractive effects play different roles in the variation of bond strength for different metals.
View Article and Find Full Text PDFJ Dent
January 2025
DDS, MS, PhD, Department of Dentistry, Federal University of Rio Grande do Norte, Natal, Brazil. Electronic address:
Objective: To evaluate the influence of different cleaning methods, surface treatments, and aging on the repair bond strength to a CAD/CAM glass-ceramic.
Materials And Methods: Forty-eight lithium disilicate CAD/CAM ceramic blocks were fabricated, sintered, and embedded in acrylic resin. After contamination with human saliva, they were divided according to the factors "Cleaning method" (Control-water/air spray, Air-particle abrasion with AlO, Ivoclean cleaning paste), "Surface treatment" (5% Hydrofluoric acid-HF + Silane, Monobond Etch & Prime-MEP), and "Aging" (thermocycling, no thermocycling).
Chemistry
January 2025
China University of Geosciences, Faculty of Materials Science and Chemistry, CHINA.
Pd cocatalysts show great potential for the photocatalytic production of H2O2. However, the catalytic efficiency of Pd cocatalyst is limited due to the strong adsorption of O2, which promotes O-O bond cleavage and thus reduces selectivity for the two-electron O2 reduction reaction. Considering that adjusting the electron density of Pd can predominately optimize Pd-Oads bond strength, in this work, electron-rich Pd sites are constructed by introducing Bi2Se3 middle layer between Pd cocatalysts and (010) facet of BiVO4 using an in-situ selenization strategy.
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