Search results for "Electron microscope"
showing 10 items of 784 documents
Lamination of swampy-rivulets Rivularia haematites stromatolites in a temperate climate
2001
Abstract Swampy-rivulets Rivularia haematites (D.C.) Agardh stromatolites were collected from the same site on the Plateau de Langres (Chaugey, France) over a seven year period. Specimens were studied in thin sections, in culture media under varying conditions of temperature and illumination, and by scanning electron microscope (SEM) in order to investigate the processes of calcification and lamination. New SEM observations confirm the polycrystalline structure of the ‘lamellae’ reported by the authors and show that the crystals composing these lamellae are elongate and aligned in the same direction as the filaments linked by them. The lamellae were also isolated in transverse sections unde…
Evaluation of apical preparations performed with ultrasonic diamond and stainless steel tips at different intensities using a scanning electron micro…
2011
Objective: The objective of our study is to analyse (with the help of scanning electron microscopes) the quality of the dental root surface and the appearance of dental cracks after performing apical preparations using two diffe-rent types of ultrasonic tips. Study design: We used 32 single-rooted teeth that underwent a root canal and apical resection. Afterwards, the teeth were divided into 4 groups of 8 teeth each, with preparations of the apical cavities in the following manner: Group 1: stainless steel ultrasonic tip at 33KHz. Group 2: stainless steel ultrasonic tip at 30KHz. Group 3: diamond ultrasonic tip at 30KHz. Group 4: diamond ultrasonic tip at 33 KHz. The quality of the root sur…
Effect of diode laser irradiation on root surfaces in vitro.
2002
The objective of this study was to evaluate possible morphological alterations of root surfaces after GaAlAs-diode laser (809 nm) irradiation under standardized in vitro conditions.Root specimens obtained from extracted periodontally diseased teeth were scaled and root planed with curettes followed by air-powder abrasive treatment prior to lasing. The variable parameters were power output (0.5-2.5 W) and exposure time (10-30 sec per specimen). Additionally, the effect of a saline solution and a human blood film on the root surface was investigated. The root segments were analyzed by means of a reflected light microscope. Photographs before and after irradiation were taken and evaluated. The…
Lateral reorganization of plasma membrane is involved in the yeast resistance to severe dehydration
2010
International audience; In this study, we investigated the kinetic and the magnitude of dehydrations on yeast plasma membrane (PM) modifications because this parameter is crucial to cell survival. Functional (permeability) and structural (morphology, ultrastructure, and distribution of the protein Sur7-GFP contained in sterol-rich membrane microdomains) PM modifications were investigated by confocal and electron microscopy after progressive (non-lethal) and rapid (lethal) hyperosmotic perturbations. Rapid cell dehydration induced the formation of many PM invaginations followed by membrane internalization of low sterol content PM regions with time. Permeabilization of the plasma membrane occ…
A facile method to determine pore size distribution in porous scaffold by using image processing
2015
Abstract Image processing permits scientists to investigate morphological properties of three-dimensional structures starting from their bi-dimensional gray-scale representation. In many cases porous structure with complex architecture has to be designed in order to attempt specific properties such in the case of scaffold for tissue engineering. Traditional morphological characterization, like scanning electron microscopy, should be coupled with quantitative information such as pore size distribution (PSD) in order to get a deeper understanding of the influence of the porous structure on tissue regeneration processes and on other related applications, it is remarkable to study a quantitativ…
Photocrosslinkable polyaspartamide/polylactide copolymer and its porous scaffolds for chondrocytes
2017
With the aim to produce, by a simple and reproducible technique, porous scaffolds potentially employable for tissue engineering purposes, in this work, we have synthesized a methacrylate (MA) copolymer of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) and polylactic acid (PLA). PHEA-PLA-MA has been dissolved in organic solvent at different concentrations in the presence of NaCl particles with different granulometry, and through UV irradiation and further salt leaching technique, various porous scaffolds have been prepared. Obtained samples have been characterized by scanning electron microscopy and their porosity has been evaluated as well as their degradation profile in aqueous medium in…
Enhanced photocatalytic performance of novel electrospun BN/TiO 2 composite nanofibers
2017
International audience; High activity boron nitride/titanium dioxide (BN/TiO2) composite nanofiber photocatalysts were synthesized for the first time via the electrospinning technique. The as-spun nanofibers with a controlled ratio of boron nitride nanosheets (BN) were calcined under air at 500 °C for 4 hours. Their morphological, structural and optical properties were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), BET surface area, Fourier-transform infrared (FTIR), Raman spectroscopy, UV-Visible spectrophotometry and room temperature photoluminescence (PL). The effect of loading different BN sheet amounts on the photocat…
XRMA analysis and X-ray diffraction analysis of dental enamel from human permanent teeth exposed to hydrogen peroxide of varying pH
2019
Background This in vitroinvestigation shows how 3.3% H2O2, at different pH-values affects the enamel. Material and Methods A number of fifteen human premolars were used. The enamel of the coronal half in six of the teeth, were exposed by H2O2. Nine teeth were prepared to enamel powder. The enamel was exposed to 3.3% H2O2, at six different pH-values (pH range 4.5 - 7.0). Analyses of the topography of enamel performed by scanning electron microscope (SEM) and the chemical composition of enamel by X-ray microanalysis (XRMA). X-ray powder diffraction (XRD) analysed the crystallinity in enamel powder. Results The exposure to H2O2 at pH5.5 resulted in a decrease of O in the exposed enamel, and ch…
Growth and characterisation of MnTe crystals
2001
We report on the low temperature growth of MnTe crystals by means of travelling solution methods. Two different processes are considered; a classical THM process using a low temperature presynthesised MnTe ingot, and a modified THM process, in which an increasing length of solvent zone collects the tellurium that was added to the stoichiometric charge to decrease the reaction temperature. Ingots from the two methods are analysed by means of scanning electron microscopy, X-ray diffractometry, resistivity, susceptibility and optical absorption measurements.
Studies on atomic layer deposition of IRMOF-8 thin films
2015
Deposition of IRMOF-8 thin films by atomic layer deposition was studied at 260–320 C. Zinc acetate and 2,6-naphthalenedicarboxylic acid were used as the precursors. The as-deposited amorphous films were crystallized in 70% relative humidity at room temperature resulting in an unknown phase with a large unit cell. An autoclave with dimethylformamide as the solvent was used to recrystallize the films into IRMOF-8 as confirmed by grazing incidence x-ray diffraction. The films were further characterized by high temperature x-ray diffraction (HTXRD), field emission scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), time-of-flight elastic recoil detection analysis (TOF-…