Search results for "Titani"
showing 10 items of 931 documents
Fracture resistance and the mode of failure produced in metal-free crowns cemented onto zirconia abutments in dental implants.
2019
The purpose of the investigation was to analyze fracture resistance and mode of failure of zirconium oxide (zirconia) abutments placed on dental implants bearing crowns of different esthetic materials: zirconia, lithium disilicate (LDS), and nano-ceramic resin, for replacing single teeth in the anterior sector. Eighty implant-abutment-crown units were divided into four groups: Group T-MC (control): 20 metal-ceramic crowns cemented onto titanium abutments; Group Z-Z: 20 zirconia crowns on zirconia abutments; Group Z-LD: 20 lithium disilicate crowns on zirconia abutments; and Group Z-NCR: 20 nano-ceramic resin crowns on zirconia abutments. Specimens underwent a fatiguing process (dynamic load…
A comparison between photocatalytic and catalytic oxidation of 2-Propanol over Au/TiO2-CeO2 catalysts
2016
Abstract Photocatalytic and catalytic oxidation of 2-propanol, representative of volatile organic compounds (VOC’s), were compared over mixed TiO 2 –CeO 2 -based catalysts. The effect of different amounts of CeO 2 and the presence of gold (1 wt%) on TiO 2 was investigated. In the photocatalytic oxidation CeO 2 had a negative effect on the performance towards the alcohol conversion of both TiO 2 –CeO 2 and Au/TiO 2 –CeO 2 catalysts, being Au/TiO 2 the most active system. On the contrary mixed TiO 2 –CeO 2 and Au/TiO 2 –CeO 2 samples showed a higher catalytic oxidation efficiency for 2-propanol conversion compared to the single oxides. In this case Au/CeO 2 catalyst had the best performance. …
Mechanical performance of experimental acrylic resins modified by nanoparticles after chemical and mechanical degradation.
2020
Background Different materials have been incorporated into the polymethylmethacrylate matrix to improve its performance. The aim of this study was to evaluate the degree of conversion (DC), the flexural strength (FS), the elasticity modulus (EM), and the effect of exposure to food-simulating liquids prior to brushing simulation on the gloss loss (GL) of experimental acrylic resins modified by nanoparticles. Material and methods Three different types of nanoparticles; silicon oxide (SiO2), cerium oxide (CeO2) and titanium oxide (TiO2) were added to a poly (methylmethacrylate) matrix, in proportions of 0.5wt%, 1wt% and 3wt% each, forming nine experimental groups. The acrylic resin was also te…
The Effect of Taper and Apical Diameter on the Cyclic Fatigue Resistance of Rotary Endodontic Files Using an Experimental Electronic Device
2021
The aim of this study was to analyze the effect of the taper and apical diameter of nickel&ndash
Chemical Vapour Deposition of Pure Titanium Using a Heated Wire Reactor and TiI4
2017
Master's thesis Renewable Energy ENE500 - University of Agder 2017 An experimental reactor system has been optimized throughout a series of experiments for making titanium tubes from an electrically heated titanium coil filament by a chemical vapour deposition method, based on the original van Arkel-de Boer -process. The titanium is thermally decomposed on the filament from vapourized titanium tetraiodide in a method not seen in similar experiments. The small-scale reactor is built for this purpose, and the associated systems and methods are developed to maintain the optimal conditions for a continuous metal deposition. A filament current control system is made of an Arduino micro-controlle…
Reactivity between molybdenum and TiO2(110) surfaces: evidence of a sub-monolayer mode and a multilayer mode
2005
Small amounts of molybdenum (from 0.03 to 1.3 eqML) were deposited on non-stoichiometric TiO 2 (1 1 0) surface. The deposits were investigated by means of LEED and X-ray/UV photoemission using synchrotron radiation. For the smallest coverage (<0.2 eqML), deposition leads to oxidation of molybdenum into species close to Mo 4+ .In such a case, states appearing in TiO 2 band gap are mainly due to reduced titanium. For higher coverages, metallic behaviour of molybdenum is observed. This phenomenon was explained, thanks to first principle calculations, as a decrease of the Mo-O interactions for the benefit of the Mo-Mo interactions as the surface molybdenum atom density increases.
ChemInform Abstract: A Straightforward Route to Homoallyl-Homocrotylamines Promoted by a Titanium Complex.
2013
This publication also contains theoretical studies and calculations concerning the reaction.
Syntheses, Structure, and Reactivity of Chiral Titanium Compounds: Procatalysts for Olefin Polymerization
2001
Titanium complexes with chelating alkoxo ligands have been synthesised with the aim to investigate titanium active centres in catalytic ethylene polymerisation. The titanium complexes cis-[TiCl2(η2-maltolato)2] (1, 89 %), and cis-[TiCl2(η2-guaiacolato)2] (2, 80 %) were prepared by direct reaction of TiCl4 with maltol and guaiacol in toluene. The addition of maltol to [Ti(OiPr)4] in THF results in the formation of species [Ti(OiPr)2(maltolato)2] (3, 82 %). The titanium compound cis-[Ti(OEt)2(η2-maltolato)2] (4, 74 %) was obtained by the transesterification reaction of species 3 with CH3CO2Et. When compound 4 is dissolved in THF a dinuclear species [Ti2(μ-OEt)2(OEt)4(η2-maltolato)2] (5, 45 %)…
Stamping of monomeric SAMs as a route to structured crystallization templates: patterned titania films.
2000
Gold-coated glass slides have be patterned by using self-assembled monolayers (SAM) of alkane thiols. Through the use of a special thiol terminated with a styrene monomer, microstructures of 5 to 10 microm width and 70 A height have been formed on the surface by graft polymerization of styrene. These patterned gold slides have then been used to template the precipitation of thin titania films from ethanolic solutions of titanium isopropoxide to create microstructured architectures in the film. Plasmon resonance spectra have established the presence of different steps in the process and have been used to follow the kinetics of the precipitation of titania on the surface. The structured TiO2 …
Preparation and photoactivity of nanocrystalline TiO2 powders obtained by thermohydrolysis of TiOSO4
2013
Nanocrystalline TiO2 photocatalysts were synthesized in mild conditions by thermohydrolysis of TiOSO4 in water at 100 °C and post-calcination treatment at various temperatures. The TiO2 powders were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, specific surface area determinations, scanning electron microscopy and electron paramagnetic resonance measurements. The photoactivity of the samples was tested employing the photodegradation of 4-nitrophenol in liquid–solid regimen and the photooxidation of gaseous 2-propanol. The best results were obtained with the powder calcined at 600 °C for 10 h. Surprisingly, the not calcined sample was the most active for the abatement…