Search results for "Microscopy"
showing 10 items of 3390 documents
Dental anatomy portrayed with microscopic volume investigations
1993
The clinical treatment of the root canal of teeth--called endodontics--assumes a precise idea of the spatial arrangement of the anatomy of teeth and their inner structure. By using computer-assisted data acquisition from filmed sequences of histologic serial sections and a special kind of magnetic resonance microscope--the Stray Field Imaging (STRAFI)--volume investigations were carried out using special functions of a newly developed 3D software. Possible applications and future perspectives are discussed.
Theoretical and practical aspects of chemical functionalization of carbon nanofibers (CNFs): DFT calculations and adsorption study
2011
The nitric acid-functionalized commercial carbon nanofibers (CNFs) were comprehensively studied by instrumental (XRD, BET, SEM, TGA) and theoretical (DFT calculations) methods. The detailed surface study revealed the variation in the characteristics of functionalized CNFs, such as a decreased (up to 34%) surface area and impacted structural, electronic and chemical properties. The effects of functional groups were studied by comparison with pristine nanofibers. The results showed that the C-C bond lengths of the modified CNFs varied significantly. Chemical functionalization altered the frontier orbitals of the pristine material, and therefore altered the nature of their interactions with ot…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…
Enhanced extraction of astragalosides from Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment.
2010
The optimal conditions for extraction of astragalosides III and IV (AGs III and IV) in Radix Astragali by negative pressure cavitation-accelerated enzyme pretreatment were studied on the basis of a Box-Behnken design and response surface methodology. Experimental results showed that negative pressure, amount of enzyme and incubation temperature were the main factors governing the enzyme pretreatment of Radix Astragali. The optimum parameters were obtained as follows: negative pressure -0.08 Mpa, amount of enzyme 1.48% (w/w of materials) and incubation temperature 45 degrees C. Under the optimal conditions, the maximal extraction yields of AGs III and IV were 0.103 and 0.325 mg/g, which were…
Effect of chemical and biological surfactants on activated sludge of MBR system: Microscopic analysis and foam test
2015
Abstract A bench-scale MBR unit was operated, under stressing condition, with the aim of stimulating the onset of foaming in the activated sludge. Possible synergies between synthetic surfactants in the wastewater and biological surfactants (Extra-Cellular Polymeric Substances, EPSs) were investigated by changing C/N ratio. The growth of filamentous bacteria was also discussed. The MBR unit provided satisfactory overall carbon removal overall efficiencies: in particular, synthetic surfactants were removed with efficiency higher than 90% and 95% for non-ionic and ionic surfactants, respectively. Lab investigation suggested also the importance to reduce synthetic surfactants presence entering…
The use of lightweight expanded clay aggregate (LECA) as sorbent for PAHs removal from water.
2012
Author's version of an article in the journal: Journal of Hazardous Materials. Also available from the publisher at: http://dx.doi.org/10.1016/j.jhazmat.2012.03.038 Lightweight expanded clay aggregate (LECA) has been explored as a sorbent for the removal of PAHs (phenanthrene, fluoranthene and pyrene) from water. The efficacy of LECA as a sorbent for PAHs was assessed using contact time, mass of sorbent and sorption isotherms in a series of batch experiments. Maximum (optimum) sorption was reached at 21 h after which the amount of PAHs sorbed remained almost constant. Batch experiments were conducted by shaking a 100 ml solution mixture of individual PAHs (containing 0.02 mg/L) with LECA. T…
Ultrastructural Pathology of Anaplastic and Grade II Ependymomas reveals Distinctive Ciliary Structures - Electron Microscopy Redux
2015
Ependymoma tumors likely derive from the ependymal cells lining the CNS ventricular system. In grade II ependymomas, tumor cells resemble typical ependymocytes, while anaplastic ependymomas are poorly differentiated. We studied three grade II and one anaplastic ependymoma, focusing on the ciliary structures. To unambiguously characterize the ultrastructure and number of cilia, we performed electron microscopy serial section analysis of individual cells. Differentiated ependymomas contained large basal bodies and up to three cilia, and lacked centrioles. Anaplastic ependymoma cells showed instead two perpendicularly oriented centrioles and lacked cilia or basal bodies. These findings could c…
Comparison of the whole slide imaging and conventional light microscopy in the grading of oral epithelial dysplasia: a multi-institutional study
2020
Made available in DSpace on 2021-06-25T11:48:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Background: Whole Slide Imaging (WSI) is an alternative method to light microscopy (LM). However, few studies have compared the diagnostic agreement between WSI and LM, especially to grade oral epithelial dysplasia (OED). The purpose of this study was to evaluate the variability in grading OED by the World Health Organization grading system, using WSI and conventional LM, and to investigate whether the access to clinical information, and psychologic or phy…
Structure and composition heterogeneity of a FeAl alloy prepared by one-step synthesis and consolidation processing and their influence on grain size…
2006
Abstract This paper aims to characterize a bulk dense FeAl (47 at.%) alloy synthesized and consolidated by one-step current-activated pressure-assisted processing of nanocrystalline elemental powders. The end-product was analyzed using a combination of scanning (SEM) and transmission electron microscopies (TEM), electron back-scattering diffraction (EBSD) as well as electron probe microanalysis (EPMA). Special attention was paid to verify the grain size (32–89 nm) previously determined by X-ray diffraction peak profile analysis. It has been found that this material displays equiaxed grains (0.8–4 μm in size) and contains limited structural defects like subgrains and dislocations. The EPMA r…
Interaction of the Vibrio cholerae cytolysin (VCC) with cholesterol, some cholesterol esters, and cholesterol derivatives: a TEM study.
2002
The Vibrio cholerae cytolysin (VCC) 63-kDa monomer has been shown to interact in aqueous suspension with cholesterol microcystals to produce a ring/pore-like heptameric oligomer approximately 8 nm in outer diameter. Transmission electron microscopy data were produced from cholesterol samples adsorbed to carbon support films, spread across the holes of holey carbon films, and negatively stained with ammonium molybdate. The VCC oligomers initially attach to the edge of the stacked cholesterol bilayers and with increasing time cover the two planar surfaces. VCC oligomers are also released into solution, with some tendency to cluster, possibly via the hydrophobic membrane-spanning domain. At th…