Metal-ceramic joining has slowly but steadily become an important manufacturing step. The evolution of joining processes has allowed ceramics to be used in combination with metals in a number of hybrid devices from traditional light bulbs and seals to improved cutting tools and modern monitoring and measuring electronic devices. New joining methods and newer approaches to conventional methods have been developed aiming at joints characterized by improved reliability, and interfaces capable of withstanding high-temperature resistance with minimum residual stresses. A summary of recent improvements on alternative approaches to ceramic-metal joining as well as new developments on brazing are presented herein. The present review also focuses on recent advances towards brazing metallized ceramics and the selection of filler alloys, since in a scenario that includes joining by laser and direct bonding with liquid transient phases, brazing continues to be by far the most widely used approach to joining as a result of its low-cost and possibility to join intricate geometries for large-scale production. Finally, methods to evaluate the mechanical strength and residual thermal stresses are presented in addition to alternative approaches to minimize residual stresses and, consequently, improve joint reliability.

No abstract

Morphological, cell, and protein characterization of platelet rich fibrin provides a better understanding of the clinical effects and improvement of clinical guidelines for several medical applications. Once well physicochemical and biologically characterized, the use of an injectable platelet rich fibrin can be extended to other applications in the field of orthopedics, periodontics, and implant dentistry on the repairing process of both soft and mineralized tissues.

A complimentary combination of experimental work and first principle calculations, based on the Density Functional Theory (DFT) method, has been used to increase our limited understanding of the enhanced photocatalytic activity of PbMoO 4 powders with predominant (111), (100), (011), and (110) facets.In this work, PbMoO 4 powders were prepared by the co-precipitation method and processed on a hydrothermal reactor at 100 o C/10 minutes. The variation of different types of modifier such as acetylacetone (acac) or polyvinylpyrrolidone (PVP) is found to play a crucial role in controlling the particle size and morphology of products and their photocatalytic properties.The structure and morphology of these crystals were characterized by X-ray diffraction (XRD), micro-Raman (MR) spectroscopy, field-emission gun scanning electron microscopy (FEG-SEM), and ultraviolet visible (UV-vis) absorption spectroscopy. Furthermore, the assynthesized PbMoO 4 micro-octahedrons without presence of (001) surface exhibit enhanced activity for the photodegradation of rhodamine B (RhB) under ultraviolet-visible light irradiation.Based on the theoretical and experimental results, we provide a complete assignment of the micro-Raman spectra of PbMoO 4 , while a growth mechanism for the formation of PbMoO 4 micro-octahedrons was systematically discussed, and a schematic illustration of the probable formation of morphologies in the whole of the synthetic process was also proposed, which reveals that the high photocatalytic activity is attributed to the absence of (001) facet.

The main aim of this study was to evaluate the influence of porosity, microstructure, and chemical composition on the wear and compressive strength of dental glass-ionomer or resin composite. Cylindrical samples (6 9 4 mm) were prepared from a nano-hybrid resin composite (Grandio Ò SO/RC, VOCO), a resin-modified glass ionomer (Vitremer TM /VI, 3 M-ESPE) and a conventional glass ionomer (Ionofil Ò Molar/CO, VOCO). Porosity and topography of the materials were evaluated by optical and scanning electron microscopy (SEM). Roughness was evaluated by R a and R t parameters at 0.1 mm/s under cutoff of 0.8 mm. Then, compressive tests were performed at 1 mm/min. Wear tests were carried out at 20 N, 2.5 mm of displacement, at 1 Hz for 90 min in artificial saliva solution. The results were statistically analyzed with a one-way ANOVA and Tukey's test (p \ 0.05). Resin composite revealed a significantly lower porosity (1.21 ± 0.20 %) than glass-ionomer restoratives (5.69-7.54 %) as well as lower values of R a and R t roughness (p \ 0.05). Also, resin composite showed significantly higher values of mechanical strength (334 ± 15.9 MPa) compared to conventional (78.78 ± 13.30 MPa) or modified glass ionomer (169.50 ± 20.98 MPa) (p \ 0.05). For maximal depth of wear, resin composite also showed significantly lower values than glass ionomer (p \ 0.05). Homogeneous wear morphology was noticed by SEM analyses on glass ionomers in opposition to resin composite. Glass ionomers showed a poor mechanical behavior associated to a high porosity and wear rate when compared to resin composite.

No abstract

No abstract

No abstract