Search results for "Microscope"
showing 10 items of 1412 documents
Rare earth doped glass–ceramics containing NaLaF4 nanocrystals
2016
Abstract Oxyfluoride glasses 16Na 2 O–9NaF–5LaF 3 –7Al 2 O 3 –63SiO 2 (mol%) activated with 3% terbium, dysprosium, praseodymium and neodymium fluorides have been prepared and studied by differential thermal analysis, cathodoluminescence, X-ray induced luminescence, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. We found out that the presence of crystalline phase enhances the X-ray induced luminescence intensity. X-ray induced luminescence is the most intense for the sample activated with terbium and treated at 700 °C, whereas the praseodymium and neodymium activated samples have the fastest decay times.
Heavy-ion induced single event effects and latent damages in SiC power MOSFETs
2022
The advantages of silicon carbide (SiC) power MOSFETs make this technology attractive for space, avionics and high-energy accelerator applications. However, the current commercial technologies are still susceptible to Single Event Effects (SEEs) and latent damages induced by the radiation environment. Two types of latent damage were experimentally observed in commercial SiC power MOSFETs exposed to heavy-ions. One is observed at bias voltages just below the degradation onset and it involves the gate oxide. The other damage type is observed at bias voltages below the Single Event Burnout (SEB) limit, and it is attributed to alterations of the SiC crystal-lattice. Focused ion beam (FIB) and s…
Analysis of surface characteristics of protaper universal and protaper next instruments by scanning electron microscopy
2017
Background Many new rotary files systems have been introduced, however, limited research has been conducted related to the surface irregularities of these files and if these have any effects on the files themselves. Hence, the aim of the present study was to analyze surface irregularities of the ProTaper® Universal rotary files (PTU) and the ProTaper Next™ rotary files (PTN) before and after instrumentation in curved canals. The main objective was to investigate the nature of these irregularities and how they might influence the use and fracture of rotary files during root-canal treatments. Material and methods The files were examined pre-operatively using a stereomicroscope and scanning el…
Interaction effect of Nd:YAG laser and universal adhesive system for dentin sealing
2020
Made available in DSpace on 2021-06-25T10:46:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Background: To evaluate the influence of the association of the universal adhesive system to different energy densities of the Nd:YAG laser on the hydraulic conductance of dentin. Material and Methods: Fifty bovine dentin discs were made. The samples were stratified into four groups (n = 10) according to the treatment performed; SBU- Adper Single Bond Universal (3M ESPE), SBU_60 - SBU associated with the Nd:YAG laser (60mJ, 10Hz, 0.6W - 47.77 J / cm²), SBU_80 - SBU associated with the Nd:YAG laser (80mJ, 10Hz, 0.8 W - 63.69 J / cm2) and C – dentin without treatment (smear layer). Hyd…
Magnetic and optical properties in degenerated transition metal and Ga co-substituted ZnO nanocrystals
2019
Abstract In order to study the influence of itinerant electrons on magnetic properties of transition metal substituted ZnO nanocrystals, nanopowders containing different amounts of Ga and fixed amounts of Fe, Ni and Mn ions were synthesized. The ions of different transition metals and Ga were successfully introduced into the ZnO structure using solvothermal synthesis method. X-ray diffraction, scanning electron microscopy, hard X-ray photoelectron spectroscopy and Rietveld refinement were used to characterize the synthesized nanocrystals. Optical measurements revealed that Ga substitution can change the light transmittance/absorption in the infrared part of the electromagnetic light spectru…
Comparative study of debris and smear layer removal with EDTA and Er,Cr:YSGG laser.
2018
Background To evaluate in vitro, the ability in removing debris and Smear Layer of 17% EDTA and Er,Cr:YSGG laser. Material and methods 58 unirradicular teeth were instrumented with MTwo® and divided into 3 groups according to irrigation protocol: 17%EDTA, laser and a combination of 17%EDTA and laser. All samples were analyzed in the apical and middle third with Scanning Electron Microscope. The Chi-cuadrado and McNemar tests were used to determine the statistical analysis and data processing and analysis was performed with the statistical package StatGraphics Centurion XVI. Results Debris analysis showed statistical significant differences when compared EDTA vs laser and EDTA vs EDTA+laser …
Composition-related structural, thermal and mechanical properties of Ba1−xSrxTiO3ceramics (0 ≤x≤ 0.4)
2015
The Ba1−xSrxTiO3 (BST) ceramics were prepared by conventional ceramic method. The crystalline structure and morphology were studied by X-ray diffraction and scanning electron microscopy, respectively. Experimental results show that increase of sintering temperature leads to an uncontrolled precipitating of the phase with a lower content of Ti. The dielectric constant and specific heat as a function of composition and temperature were investigated. The increasing concentration of Sr ions leads to a shift of the Curie point below room temperature. To determine the elastic constants (the Young's modulus E, the shear modulus G and the Poisson's ratio v) of BST, a method of measurement of the lo…
Spherical silica agglomerates possessing hierarchical porosity prepared by spray drying of MCM-41 and MCM-48 nanospheres
2003
Hierarchically ordered porous materials possessing both meso- and macropores can be obtained by agglomeration of spherical primary particles of mesoporous MCM-41 and MCM-48 materials using the spray drying technique. A highly interconnected bimodal pore network is obtained due to the intra- and inter-particle pore systems within the micron-sized spherical agglomerates. Further packing of the agglomerates will result in a three-modal hierarchical pore system, where the first level of porosity originates from the ordered mesopores inside the primary particles, the second level is a result of the particle internal porosity, and the third level is due to the voids between the agglomerates. The …
In vitro preliminary study of osteoblast response to surface roughness of titanium discs and topical application of melatonin
2014
Objectives: To observe human osteoblast behavior cultured in vitro on titanium discs (Ti) in relation to surface roughness and melatonin application. Study Design: Human osteoblasts (MG-63) were cultured on 60 Ti6Al4V discs divided into three groups: Group I: discs treated with dual acid etching; Group II dual acid etching and blasting with calcium phosphate particles; Group III (control) machined discs. Surface roughness and topography of the discs were examined with scanning electron microscope (SEM) and confocal laser scanning electron microscope( CLSM). Osteoblast adhesion, proliferation and cell morphology were determined by means of fluorescence microscopy with Image-Pro Plus software…
High-density polyethylene facial implants show surface oxidation in SEM and EDX examination: a pilot study.
2009
Previous histopathological studies on explanted Medpor high-density polyethylene (HDPE) facial implants indicated signs of material destruction and claimed to observe phagocytized HDPE particles within the tissue samples beside the usual type IV reaction with severe fibrosis. We examined new and explanted Medpor material with scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The implant surface of three patient-derived specimens showed significantly higher oxygenation in EDX analysis and morphological changes in SEM compared to the new unused material directly after opening of the package and after 1 year of exposure to air. Our preliminary findings indicate a p…