Alexis Valery

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The abandoned “Monte-Fresco” rock phosphate mine in Táchira, Venezuela, was sampled to study the biodiversity of phosphate-solubilizing microorganisms (PSM). Rhizosphere and bulk soils were sampled from colonizer plant species growing at a mined site where pH and soluble P were higher than the values found at a near by unmined and shrubby soil. Counting and(More)
The diffraction patterns acquired with a transmission electron microscope (TEM) contain Bragg reflections related to all the crystals superimposed in the thin foil and crossed by the electron beam. Regarding TEM-based orientation and phase characterisation techniques, the nondissociation of these signals is usually considered as the main limitation for the(More)
The spatial resolution and the indexing quality obtained with an automated orientation and phase mapping tool are analyzed for different Transmission Electron Microscope (TEM) illumination settings. The electron probe size and convergence angle are studied for two TEM configuration modes referred as microprobe and nanoprobe modes. Using a 10μmC2 aperture in(More)
The problem of bacteria characterization from images acquired in microscopy is considered. The proposed approach consists of four consecutive steps: 1) images enhancement; 2) segmentation based on Watershed algorithm; 3) optimization of the initial segmentation; 4) bacteria quantification using a template matching procedure. Additionally, a modified version(More)
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