Élimination du phénol par deux plantes aquatiques : Juncus fontanesii (Gay) et Lemna minor L.

L'élimination du phénol et de ses dérivés, substances organiques toxiques, fait appel à différents processus physico-chimiques ou biologiques. Certaines plantes aquatiques ont la capacité de déplacer des produits chimiques en les métabolisant, en les évaporant ou en les dégradant. Il faut, toutefois, rester à des concentrations inférieures aux seuils de toxicité des espèces employées.Dans le présent travail, deux plantes aquatiques: le Jonc de Desfontaines (Juncus fontanesii) de la famille des Joncacées et la Lentille d'eau (Lemna minor) de la famille des Lemnacées, ont été testées pour éliminer le phénol. Le travail a été effectué sans addition d'éléments nutritifs ni acclimatation prélable, pour des concentrations variant de 8 à 48 mg/l et pour deux densités surfaciques de la biomasse végétale fraîche : 2,8 et 5,6 kg/m2.Les deux espèces se sont révélées aptes à éliminer totalement le phénol avec des cinétiques différentes. Un phénomène de relargage, important dans le cas de l'emploi de J. fontanesii, a pu être observé. Une comparaison de ce type d'élimination à celui dû aux micro-organismes nous a permis, par utilisation des boues activées, d'aboutir à l'ordre de performance suivant : J. fontanesii > L. minor (faibles densités) > micro-organismes avec barbottage d'air > micro-organismes sous des conditions atmosphériques > témoins (sans plantes) > L. minor (fortes densités) > micro-organismes sous des conditions anaérobies.Phenols are considered as toxic organic compounds. They can be treated by different physico-chemical or biological processes. These products can be oxidized by chemicals such as H2O2, TiO2, O3, etc. The performance of the process depends on pH, temperature and phenol/oxidant ratio. Otherwise, they can be transformed biologically by enzymes, fungi, yeast or plants. Considerable work has already been done with regard to uptake of phenol by aquatic plants.In our study two aquatic plants: Juncus fontanesii, a rooted species from Joncaceae family and Lemna minor, floating species from Lemnaceae family, have been selected to study their ability to remove phenol from static phenolic solutions. The initial concentration of phenol varied from 8 to 48 mg/l. The density of biomass (wet weight) ranged from 2.8 to 5.6 kg/m2. Experiences were carried out without acclimation and without addition of nutritive elements. Controls (without plants) were prepared with the same concentrations. Under these conditions, the results of quantitative analyses show that J. fontanesii is able to remove phenol more rapidly than L. minor and can release a fraction of it to the medium particularly in the first ten hours of contact.It has been observed that phenol uptake is sensitive to the density of biomass and the initial concentration. In order to examine more closely the effect of these variables, we have carried out experiments where the initial concentration was kept constant (8 mg/l) and biomass density varied. When the density of biomass increases, the kinetic uptake of phenol by J. fontanesii increases too; however, it decreases in the presence of L. minor. In fact, at high densities, L. minor covers fully the surface of the water and causes a screen effect, such that diffusion of atmospheric oxygen into the medium is limited. In addition, L. minor has a short root system, so the amount of oxygen that enters the solution is negligible. Elimination of phenol by L. minor is rapid when the density of biomass ranges from 0.7 to 1.4 kg/m2. For both plants, we have noticed the existence of a maximum time limit of degradation and an optimal density beyond which there is no improvement in elimination.Phenol can be degraded by micro-organisms. In order to elucidate this pathway, an investigation was undertaken using activated sludges in the following situations: under atmospheric conditions, under anaerobic conditions and with bubbling air intermittently.The comparison of obtained results shows that the rate and kinetics of the elimination decrease in the following order: J. fontanesii > L. minor (low densities) > micro-organisms with air bubbling > micro-organisms under atmospheric conditions > controls (without plants) > L. minor (high densities) > micro-organisms under anaerobic conditions

The brezis-ekeland-nayroles minimization principle with mixed finite element method for elastoplastic dynamic problems

We propose a modification of the Hamiltonian formalism which can be used for dissipative systems, the Brezis-Ekeland-Nayroles principle. The formalism is specialized to the standard plasticity in small strains and dynamics. We apply it to solve the classical problem of a thin tube in plane strain subjected to an internal pressure. The continuum is discretized with mixed finite elements

The emergence of quantum capacitance in epitaxial graphene

We found an intrinsic redistribution of charge arises between epitaxial graphene, which has intrinsically n-type doping, and an undoped substrate. In particular, we studied in detail epitaxial graphene layers thermally elaborated on C-terminated $4H$-$SiC$ ($4H$-$SiC$ ($000{\bar{1}}$)). We have investigated the charge distribution in graphene-substrate systems using Raman spectroscopy. The influence of the substrate plasmons on the longitudinal optical phonons of the $SiC$ substrates has been detected. The associated charge redistribution reveals the formation of a capacitance between the graphene and the substrate. Thus, we give for the first time direct evidence that the excess negative charge in epitaxial monolayer graphene could be self-compensated by the $SiC$ substrate without initial doping. This induced a previously unseen redistribution of the charge-carrier density at the substrate-graphene interface. There a quantum capacitor appears, without resorting to any intentional external doping, as is fundamentally required for epitaxial graphene. Although we have determined the electric field existing inside the capacitor and revealed the presence of a minigap ($\approx 4.3meV$) for epitaxial graphene on $4H$-$SiC$ face terminated carbon, it remains small in comparison to that obtained for graphene on face terminated $Si$. The fundamental electronic properties found here in graphene on $SiC$ substrates may be important for developing the next generation of quantum technologies and electronic/plasmonic devices.Comment: 26 pages, 8 figures, available online as uncorrected proof, Journal of Materials Chemistry C (2016

Effet du chrome niacinate sur la tolérance au glucose chez le rat wistar

Le chrome est un oligoélément essentiel à l’homéostasie du métabolisme glucidique qui pourrait également être impliqué dans l’étiologie de l’athérosclérose. Trois lots de rats Wistar males (n= 30, âgé de 2 mois) traités quotidiennement et pendant 28 jours. Les Contrôles ont reçu du sérum physiologique (1µL/g/j, ip), groupe II a reçu la dexaméthasone (DEX : 0,2 mg/kg/j, ip) et les rats du groupe III ont reçu le même régime que le groupe II avec une supplémentation en CrN à partir du 7 ème jour de l’expérimentation (CrN : 30 mg/kg/j, PO). A la fin de l’expérimentation, les rats sont sacrifiés et les paramètres biochimiques sont dosés. Les résultats montrent une augmentation du poids corporel des rats témoins par apport aux groupes traités par la DEX. La supplémentation en CrN n’a pas corrigé l’élévation de la glycémie et de l’insulinémie engendré par la DEX, de même l’ajout du CrN n’influe pas sur la variation des taux de la triglycéridémie et de la cholestérolémie entrainés par la DEX. Il est notamment observé que l’addition du CrN n’a pas d’effet notable sur la fonction hépatique et la fonction rénale.Mots-clés : chrome, diabète, glycémie, dexaméthasone.Effect of chromium niacinate on glucose tolerance at wistar rat Chromium is an essential trace element in the homeostasis of glucose metabolism could also be involved in the etiology of atherosclerosis. Three groups of male Wistar rats (n= 30, age 2 months) treated daily for 28 days. Controls received saline (1µl/g/day, ip), group II received dexamethasone (DEX: 0, 2 mg/kg/day, ip) and the rats of group III received the same treatment as the group II with supplementation CrN from the 7 day of the experiment (CrN: 30 mg/kg/day, PO). At the end of the experiment, the rats were sacrificed and biochemical parameters were measured. The results show an increase in the body weight of control rats contribution to the DEX treated groups. CrN supplementation did not correct the elevation of blood glucose and insulin caused by DEX. The addition of CrN does not affect the rate of change in triglycerides and cholesterol trained by DEX. It is particularly noted that the addition of CrN has no significant effect on liver and kidney functions.Keywords : chromium, diabetes, glucose, dexamethasone

Proper Orthogonal Decomposition Analysis of an Airfoil Performances under a Small Vortical Gust

This paper investigates the performance of a non-symmetric airfoil in a perturbed flow for a low Reynolds number by creating small vortical structures. A newly designed two-dimensional numerical tool is used to examine the interaction between the NACA 23015 airfoil and the vortex shedding from a square cylinder. Different airfoil position ratios are numerically simulated concerning the square cylinder G/D (D: square cylinder diameter), the channel centerline T/d (d=D/2), and the vortices scale size D/c (c: airfoil chord length). Results show that the maximum values of the lift and drag aerodynamic coefficients are influenced by the airfoil’s lateral and longitudinal positions. The Proper Orthogonal Decomposition (POD) method is used to identify the most energetic flow structures. For all simulated scenarios, it was found that the first two modes reflect the dominating coherent structures in the flow field. The results also show that a leading-edge vortex is formed over the airfoil. The observed phenomena of symmetric and antisymmetric shedding vortex mechanisms essentially depend on the lateral distance of the airfoil T/d and the vortex scale size D/c. However, the spectral analysis demonstrates that the shedding frequency mainly depends on the gap distance G/D

Tunisian olive oils geographical origin discrimination using the potentiometric fingerprints recorded by an electronic tongue

The development of fast and cost-effective analytical techniques for EVOO authentication is a challenging task. Moreover, if a specific meteorological or geographical factor affects different geographical regions similarly, olive oils geographical discrimination may be a hard task using conventional analytical techniques [1]. E-noses and/or voltammetric E-tongues have already been applied to assess olive oils' geographical origin, mainly to discriminate different countries or quite different regions of the same country [2].This work was financially supported by POCI- 0 1-0 145-FEDER-006984-Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 --CQVR, Project UID/BI0/04469/2013--CEB and Project UID/AGR/00690/2013--CIMO all funded by FEDER, through COMPETE2020, and by national funds through. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRHIBD/104038/2014 ).info:eu-repo/semantics/publishedVersio

Electrochemical taste sensor for unmasking extra-virgin olive oils adulterated with rancid or winey-vinegary olive oils

Olive oils may be commercially classified, in a decrease order of quality and economic value, as extra-virgin (EVOO), virgin (VOO) or lampante (LOO) olive oils, being quite prone to frauds. Thus legal protection regulations have been approved by the European Union Commission [1,2], being required the fulfilment of several physicochemical and sensory thresholds [3,4]. Unfortunately, the mixture of expensive olive oils with low quality oils aiming fraudulent economic revenue is still a common practice difficult to detect. In this work, a potentiometric electronic tongue (E-tongue) was used to detect adulteration of an EVOO with different added levels (2.5%, 5%, 10%, 20% and 40%; v/v) of an LOO with an intense sensory defect (rancid or wineyvinegary). Previously, similar electrochemical devices, also comprising lipid polymeric sensor membranes, showed to be able to give qualitative and/or quantitative responses towards basic taste sensations (acid, bitter, salty, sweet, and umami), positive sensory attributes (bitter, fruity, green and pungency) or defects (e.g., butyric, musty, putrid, winey-vinegary and zapateria) [5-8]. The E-tongue coupled with linear discriminant technique (based on the signal profiles of 19 or 20 E-tongue sensors, chosen using a simulated annealing meta-heuristic variable selection algorithm, for rancid and wineyvinegary adulterations, respectively) allowed to semi-quantitatively distinguish olive oils with different adulteration levels (repeated K-fold crossvalidation predictive correct classifications of 84±10% and 94±8% for rancid and winey-vinegary adulterations, respectively). The preliminary results showed the practical potential of the E-tongue as a taste device for the successful detection of EVOOs adulterated with LOO containing organoleptic defects.This work was financially supported by POCI- 01–0145-FEDER-006984–Associate Laboratory LSRE-LCM, Project UID/QUI/00616/2013 –CQVR, Project UID/BIO/04469/2013 – CEB and Project UID/AGR/00690/2013 –CIMO all funded by FEDER, through COMPETE2020, and by national funds through. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant SFRH/BD/104038/2014.info:eu-repo/semantics/publishedVersio