Search results for "visual_art"
showing 10 items of 2987 documents
Effect of Fiber-Reinforced Composite and Elastic Post on the Fracture Resistance of Premolars with Root Canal Treatment—An In Vitro Pilot Study
2020
(1) Background: To analyze the fracture resistance of endodontically upper premolar teeth restored with glass fiber reinforced posts, glass fiber elastic posts, conventional composite resin (CR) and glass fiber reinforced composite (FRC) resins as restorations. (2) Methods: Seventy premolars were submitted to root canal treatment and restored with the following restorative materials (n = 10): A. FRC posts restored with resin
Salt spray fog ageing of hybrid composite/metal rivet joints for automotive applications
2017
Abstract The present experimental investigation aims to investigate the effect of salt-fog exposition on the mechanical behaviour of composite/metal riveted joints. To this aim, two kinds of joint were exposed to salt-fog environmental conditions according to ASTM B117 standard, for fifteen weeks. In particular, two composite laminates (i.e. glass fibre and carbon fibre/epoxy composites) were used as composite substrate joined with the metal substrate (i.e. aluminium alloy Al 6060). Single-lap shear tests were carried out in order to evaluate the evolution of the mechanical performances and the damage mechanisms of the riveted joints during the ageing exposition. The results evidence that t…
Pickering Emulsions Based on Wax and Halloysite Nanotubes: An Ecofriendly Protocol for the Treatment of Archeological Woods
2020
A novel green protocol for the consolidation and protection of waterlogged archeological woods with wax microparticles has been designed. First, we focused on the development of halloysite nanotubes (HNTs) based Pickering emulsions using wax as the inner phase of the oil-in-water droplets. The optimization of the preparation strategy was supported by both optical microscopy and scanning electron microscopy, which allowed us to show the morphological features of the prepared hybrid systems and their structural properties, i.e., the distribution of the clay at the interface. Also, the dependence of the overall dimensions of the prepared systems on the halloysite content was demonstrated. Micr…
Heavy Metals in Mollusc Shells: A Quick Method for their Detection
2015
It is known for a long time that calcified tissues secreted by aquatic or terrestrial invertebrates – such as mollusc shells – have the ability to concentrate large amounts of pollutants, in particular heavy metals. In the present paper, we have found an extremely rapid and easy procedure to qualitatively detect the putative presence of heavy metals in shells, without having to use sophisticated techniques such as Wavelength Dispersive Spectroscopy, atomic adsorption spectroscopy or ICP-MS. Our method rests on the capacity of the silver enhancement chemicals that are traditionally used in immunogold localization experiments to increase the size of heavy metal nanoparticles, whatever the che…
Aging resistance of bio-epoxy jute-basalt hybrid composites as novel multilayer structures for cladding
2017
Abstract Aging resistance of jute reinforced laminates is compared with two jute/basalt hybrid laminates prepared with different stacking sequences (i.e., sandwich and intercalated configuration). To this aim, composites are exposed to cyclic conditions comprising hygrothermal stress and UV radiation to promote an accelerated aging, for a period of 84 days. Specimens of each laminate are tested after 14, 28, 56 and 84 days, respectively. Quasi-static flexural tests, Charpy impact tests and dynamic mechanical tests are performed according to international ASTM and ISO standards. Furthermore, scanning electron microscopy and differential scanning calorimetry are used to evaluate the morpholog…
Wettability of MXene and its interfacial adhesion with epoxy resin
2021
Abstract The surface energies of MXene nanofillers critically affect the mechanical properties and durability of any polymer-based devices and composites to which these fillers are applied. In this context, this study comprehensively investigates Ti3C2Tz MXenes prepared via the hydrochloric acid/lithium fluoride etching of Ti3AlC2. The surface energy values of 10-layer MXene coatings were evaluated to be between 47.98 and 64.48 mJ/m2 as per contact-angle measurements. The wettability properties were found to depend on the number of coating layers and the liquids used. Additionally, the coating roughness was evaluated by using atomic force microscopy. The effectiveness of MXenes as a reinfor…
A biomimetic approach to ameliorate dental hypersensitivity by amorphous polyphosphate microparticles.
2016
Abstract Objective Dental hypersensitivity has become one of the most common and most costly diseases in the world, even though those maladies are very rarely life threatening. Using amorphous microparticles, fabricated from the natural polymer (polyphosphate), we intend to reseal the dentinal tubules exposed and reduce by that the hypersensitivity. Methods Amorphous microparticles (termed aCa-polyP-MP) were prepared from Na-polyphosphate (polyP) and CaCl 2 , then incubated with human teeth. The potential of the microparticles to plug the dentinal tubules was determined by microscopic and spectroscopic techniques. Results We demonstrate that, in contrast to polyP, the aCa-polyP-MP efficient…
Corrosion behaviour of heavily deformed pearlitic and brass-coated pearlitic steels in sodium chloride solutions
2014
Abstract The influence of plastic deformation and galvanic coupling on the microstructure and corrosion behaviour of pearlitic steel and brass-coated pearlitic steel was investigated in sodium chloride solution at 25 °C. Microstructural changes were quantified using scanning electron microscopy coupled with EBSD. Chemical and electrochemical modifications were evaluated using XPS, ZRA, the electrochemical microcell technique and the weight loss method. From these experiments, the influence of microstructural changes on the electrochemical parameters and the corrosion rate was discussed.
Ultra-low density metallic foams synthesized by contact glow discharge electrolysis (CGDE) for laser experiments★
2018
International audience; The goal of this work is to realize metallic foams synthesized by contact glow discharge electrolysis with specific characteristics. In this paper, we show the results of our studies, consisting in investigating parameters that influence the foams characteristics. Thus, the morphology of metallic foams is examined through scanning electron microscopy (SEM) observations with the acid nature. Moreover, the evolution of the mass and the volume of metallic foams with two experimental parameters (overvoltage and gold concentration) is also investigated. The acid nature affects the foams microscopic structure highlighted by the SEM observations, but for now no valid explan…
Structural and Electric Properties of Sodium Lithium Niobate Ceramic Solid Solution Li0.08Na0.92NbO3
2011
A lead-free solid solution Li0.08Na0.92NbO3 was prepared by a two-stage hot-pressing technology. The structure and morphology of Li0.08Na0.92NbO3 were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The studies of electric conductivity were performed depending on temperature and frequency of electric measuring field on heating and cooling processes. These measurements revealed that the a.c. conductivity changed with the frequency according to the formula: σ(ω)=σ dc +Aω n where n < 1. These results were discussed considering the conduction mechanism as a type of polaron hopping.