Search results for "Surfaces"
showing 10 items of 2837 documents
3 D digitization of specular metallic surfaces by means of infrared imaging
2012
For the past twenty years, the need for three-dimensional digitization of manufactured objects has increased significantly and consequently, many experimental techniques and commercial solutions have been proposed. However, difficulties remain for the acquisition of optically non cooperative surfaces, such as transparent or specular ones. Since the working principle of conventional scanners is based on the acquisition of the diffuse part of the reflection, transparency and specular reflections may cause outliers. To address highly reflective metallic surfaces, we propose the extension of a non conventional technique that was originally dedicated to glass objects, called “Scanning from Heati…
3D acquisition system for transparent objects
2010
This thesis deals with a new automated tridimensional inspection system for transparent surfaces, based on polarization analysis. We first present an extension of the ‘Shape from Polarization’ method for transparent surfaces. After being reflected, an unpolarized light wave becomes partially linearly polarized, depending on the surface normal and on the refractive index of the media it impinges on. Hence, by measuring the polarization parameters of the reflected light, the surface normals are computed. The ambiguity concerning the normal orientation is solved here with a multispectral lighting system. Finally, the description of the whole acquisition prototype is given as well as some exper…
Immobilization of single-stranded DNA fragments to solid surfaces and their repeatable specific hybridization : covalent binding or adsorption ?
2004
Abstract The different steps of the immobilization process of single-stranded DNA (ssDNA) on surfaces by means of chemical grafting have been investigated using systematic measurements of grafting and hybridization densities by means of radioactive labelling. The immobilization by chemical grafting to a dense monomolecular layer of N-hydroxysuccinimidyl ester reactive functions attached to silica plates was performed from a dilute solution of amino-terminated oligonucleotides (10 μmol/l). The slow evaporation of the solvent allowed to increase the DNA grafting density by a factor of 10. A precise control of the rinsing process that followed the immobilization reaction allowed the discrimina…
Switch in Relative Stability between cis and trans 2-Butene on Pt(111) as a Function of Experimental Conditions: A Density Functional Theory Study
2018
International audience; The adsorption of cis and trans 2-butenes on Pt(111) has been studied as a function of hydrogen coverage OH by means of calculations based on density functional theory (DFT) with the inclusion of dispersion forces. All hydrogen coverages have been considered, from 0 to 1.00 monolayer (ML). For each case, the di-sigma and pi adsorption geometries of the olefins have been compared at a surface coverage of theta(C4H8) = 0.11 ML. Calculations of the Gibbs free energies of these systems have identified the most stable 2-butene isomer (cis or trans) as a function of coverage, temperature, and pressure. In particular, focus was placed on two sets of conditions, namely, one …
Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment
2016
The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…
Simulations on the mechanism of CNT bundle growth upon smooth and nanostructured Ni as well as θ-Al2O3 catalysts
2011
Abstract In the current study, we have performed ab initio DFT calculations on the gradually growing 2D periodic models of capped single-wall carbon nanotubes (SW CNTs) upon their perpendicular junctions with the Ni(111) substrate, in order to understand the peculiarities of the initial stage of their growth on either smooth or nanostructured catalytic particles. Appearance of the adsorbed carbon atoms upon the substrate follows from the dissociation of CVD hydrocarbon molecules, e.g., CH4: (CH4)ads → (CH)ads+3Hads and (CH)ads → Cads+Hads. (Since the effective growth of CNTs upon Ni nanoparticles occur inside the nanopores of amorphous alumina, we have also simulated analogous surface react…
Fast blue B functionalized silica-polymer composite to evaluate 3,5-dihy-droxyhydrocinnamic acid as biomarker of gluten intake
2021
Celiac disease is an immune-mediated systemic disorder elicited by gluten and related prolamines in genetically susceptible individuals. The current treatment is a strict and lifelong gluten-free diet. However, compliance with the gluten-free diet is not always adequate and many food products contain low concentrations of gluten. The determination of dietary transgressions is a challenge for patients, physicians and dietitians. Alkylresorcinols (AR) have been proposed as sensitive and specific biomarkers of gluten consumption. In this work silica-polymer composites doped with fast blue B reagent (FB) have been used to estimate alkylresorcinols in biological samples. The proposed colorimetri…
Description of Solid-to-Solid Redox Processes Based on the Voltammetry of Immobilized Particles Methodology: A Logistic Approximation
2022
A semiempirical model to describe the voltammetry of nontopotactic solid-to-solid redox processes occurring in the voltammetry of immobilized particles (VIMP) electrochemistry is described. It is applied to the reduction of solid metal compounds to the corresponding metal in contact with suitable electrolytes. The model is based on the assumption that the transferred charge is a logistic function of the applied potential, a situation that applies for reversible redox processes involving strongly adsorbed reactants. The model satisfactorily applies to reproduce linear potential scan curves recorded for graphite electrodes modified with different lead compounds (PbO, PbCl2·2H2O, lead-tin yell…
Asymmetric synthesis of functionalized tetrahydrofluorenones via an NHC-catalyzed homoenolate Michael addition
2018
The first example of an N-heterocyclic carbene-catalyzed asymmetric desymmetrization of enal-tethered cyclohexadienones via an intramolecular homoenolate Michael addition/esterification reaction is described. This new protocol offers a direct entry to various functionalized tetrahydrofluorenones with three contiguous stereocenters in high yields, good diastereoselectivities and excellent enantioselectivities.
Synergistic enhancement via plasmonic nanoplate-bacteria-nanorod supercrystals for highly efficient SERS sensing of food-borne bacteria
2017
Bio-sensing techniques utilizing metallic nanoparticles as a probe have gained more and more attention and play today an important role in the detection of bacteria. To date, although several sensing materials have been tested, there is still a long way to go to achieve a fast, low-cost, ultrasensitive and multifunctional substrate suitable for a universal biosensor for detection of bacterial cells. Here, we report a novel probe design based on anisotropic plasmonic nanoparticles organized to a biocompatible 3D bio-inorganic scaffold, i.e., nanoplate-bacteria-nanorod supercrystals (NBNS) with extremely high surface-enhanced Raman spectroscopic (SERS) activity as a model of synergistic plasm…