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Barium lanthanum ferrite and four Mn/Ti substituted materials were synthesized by the sol-gel method. The crystal structure of the materials was studied by a combination of X-ray powder diffraction, electron diffraction, scanning transmission electron microscopy and 57Fe Mössbauer spectrometry. BaLaFe2O6-δ has a cubic perovskite structure and Ba0.7La1.3FeMnO6-δ is distorted perovskite with the R View the MathML source3̅c symmetry, both from electron diffraction and X-ray powder diffraction. However, according to transmission electron microscopy, the crystals of BaLaFeTiO6-δ, BaLaFeTi0.5Mn0.5O6-δ, and BaLaFe0.5Ti0.5MnO6-δ consist of nanodomains with different symmetries (Pm View the MathML source3̅m next to R View the MathML source3̅c due to octahedral tilts), whereas the bulk X-ray powder diffraction patterns for these compounds correspond to the simple cubic structure. 57Fe Mössbauer spectrometry confirms that all materials contain high spin state Fe3+ ions which are strongly influenced by the chemical disorder resulting from various cationic environments.

Iron doped brownmillerite oxides LaSrMn 2− x Fe x O 5 (0 ⩽ x ⩽ 0.5) have been prepared as pure powders by a conventional solid state reaction and studied by X-ray powder diffraction, scanning electronic microscope and Mossbauer spectroscopy. Rietveld analysis of X-ray diffraction patterns confirms that all samples crystallize in the orthorhombic system with Pnma space group and are isotypic with the Ca 2 Fe 1.039 Mn 0.962 O 5 phase. Cell parameters and crystallite size show an anomaly around x = 0.2 which is explained by the partial substitutions of Mn 2+ and Mn 3+ by Fe 3+ and small amounts of Fe 4+ . A detailed analysis of the Mossbauer spectra for all compounds measured at room temperature shows that Fe 3+ ions are located in distorted octahedral and tetrahedral sites. The environment and oxidation states of Mn and Fe are determined by bond valence sum calculations and the results for Fe are compared to the results from the Mossbauer study.

To our knowledge, this is the first study on the influence of water, ethyl acetate and methanol as the extraction solvent upon the bioactive compound composition, antioxidant capacities and enzyme inhibitory activities of Marrubium lutescens isolates. The contents of the total phenolic compounds varied between 9.94 and 54.80 mg gallic acid equivalent/g extract and the level of total flavonoids were between 4.45 and 27.20 mg quercetin equivalent/g extract. Twenty-four compounds were identified using liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Rosmarinic acid, luteolin 7-glucoside, chlorogenic acid, caffeic acid and hyperoside were the primary compounds present for all of the used solvents. The most compounds (23) were detected in the methanol extract. Six antioxidant assays revealed that M. lutescens extracts showed interesting antioxidant activities with a significant variation between the extracts. The results revealed that the highest tyrosinase and α-amylase inhibitory activities was detected in the ethyl acetate extract. This work confirmed that the nature of solvent influenced the levels and the types of the extracted biomolecules. Moreover, the obtained results suggest that M. lutescens may be a source of bioantioxidants for industrial additives. © 2020, © 2020 Taylor & Francis Group, LLC.

International audience; Abstract Wautersiella falsenii is a rarely non-fermenting Gram-negative bacterium and belongs to the Flavobacteriaceae family. This nosocomial pathogen can cause several human infections, especially among immunocompromised patients. Here, we describe the whole genome sequence of a clinical W. falsenii strain isolated from a urine sample of a 35-year-old woman with a urinary tract infection in Tunisia. We investigated its phenotype and genotype. After bacterial identification by the MALDI-TOF method, the whole-genome sequencing of this strain was performed. This isolate was not susceptible to various antibiotics, including β-lactams, aminoglycosides, and quinolones. However, it remains susceptible to imipenem (MIC = 0.25 mg/l), ertapenem (MIC = 0.75 mg/l), and meropenem (MIC = 0.19 mg/l). Interestingly, the E-TEST ® (MP/MPI) showed a reduced MIC of meropenem +/− EDTA (0.064 μg/ml). Besides, the color change from yellow to red in the β CARBA test only after 24 hours of incubation can be interpreted in two ways. On the one hand, as a likely low expression of the gene encoding metallo-β-lactamase. On the other hand, and more likely, it may be a false-positive result because, according to the test manufacturer's recommendations, the test should be read after 30 minutes. Perhaps, therefore, this gene is not expressed in the tested strain. Moreover, the whole-genome sequence analysis demonstrated the presence of a novel chromosomally located subclass B1 metallo-β-lactamase EBR-like enzyme, sharing 94.92% amino acid identity with a previously described carbapenemase produced by Empedobacter brevis , EBR-1. The results also showed the detection of other antibiotic resistance genes and the absence of plasmids. So far, this study is the first report on the detection of W. falsenii in Tunisia. These findings prove that W. falsenii could be a potential reservoir of antibiotic resistance genes, e.g., β-lactamases. Collaborative efforts and effective hygiene measures should be established to prevent the emergence of this species in our health care settings.

International audience; In this work, we present the influence of the decoration of TiO(2) nanotubes (TiO(2)-NTs) with Ag silver nanoparticles (Ag-NPs) on the photocatalysis of emerging pollutants such as the antibiotic diclofenac sodium. The Ag-NPs were loaded onto the TiO(2)-NTs by the anodization of metallic titanium foils. Diclofenac sodium is an emerging pollutant target of the pharmaceutical industry because of its negative environmental impact (high toxicity and confirmed carcinogenicity). The obtained Ag-NP/TiO(2)-NT nanocomposites were characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), transmission spectroscopy (TEM), and X-ray photoelectron spectroscopy (XPS). In order to study the photocatalytic behavior of Ag-NPs/TiO(2)-NTs with visible cold LEDs, the possible photocatalytic mechanism of antibiotic degradation with reactive species (O(2)°(-) and OH°) was detailed. Moreover, the Langmuir-Hinshelwood model was used to correlate the experimental results with the optimized catalyst. Likewise, reuse tests showed the chemical stability of the catalyst.

In the present work, we investigate the effect of low phosphorus doped polysilicon thin films. These later are deposited on glass substrates by low pressure chemical vapor Deposition (LPCVD) technique and are in situ doped with phosphine adjunction to silane. Doping levels are reported by the phosphine to silane ratio Γ varying from 0 (undoped layer) to heavily doped layer almost 1.2 × 10–3. Films are characterized by different techniques as Photothermal Deflection Spectroscopy (PDS), photoluminescence measurements and x-ray diffraction of polycrystalline layers. The last one reveals that doping concentration giving modification in crystallite size and presence of microstrain, so a clear reduction in the Eg value was observed for the slightest doped layer (Γ = 3.7 × 10–7) by comparaison with the undoped one ((Γ = 0). Results give evidence of an optimum doping level to obtain higher polysilicon films quality. Polysilicon film quality has been correlated to phosphorus doping levels. Thin film transistors (TFTs) are fabricated on glass substrate using a top gate four mask process at low temperature ( V th and density of states NT within the grain boundaries have their lowest values. Although, the field effect mobility μ records its highest values. Additionally, low doping levels enhances the TFT stability under stress. As a result, the in situ low doping strategy opens the way to manufacture polysilicon electronic devices exhibiting high electrical performances and a rather high stability under stress effects.

International audience; Indoor air pollution is a complex problem that involves a wide range and diversity of pollutants that threaten human health. In this context, significant efforts must be made to improve the quality of indoor air. It is therefore important to start controlling the sources of indoor pollution. However, where eliminating or minimizing sources of emissions is not technically feasible, technologies to reduce them should be used. The present work deals with the photocatalytic depollution of hospitals indoor air, using a continuous photocatalytic process. In order to get closer to real conditions, two model pollutants representing the indoor air of hospitals were chosen as targets; chloroform (CHCl3) and glutaraldehyde (C5H8O2). The photocatalytic oxidation of VOCs alone and their mixture (binary mixing system) has been studied on a pilot scale. Indeed, the experiments were carried out in a continuous planar reactor using a new technology based on the TiO2/optical fiber photocatalyst. The effects of experimental conditions such as air flow rate (4–12 m3.h−1), VOCs inlet concentration (4–40 mg.m−3) and humidity levels (5–90%) were pointed out. The photocatalytic effect of the OF-TiO2 composite was found to be improved under UV irradiation as compared to TiO2. The presence of water molecules in small amounts (less than RH = 30%) can promote the degradation process due to the formation of •OH radicals. Biomolecular Langmuir-Hinshelwood model including mass transfer step has been developed to represent the process behavior. Reusability test show that the optical fiber -based photocatalysts presented good photocatalytic activities towards CHCl3/C5H8O2 removal. © 2021 Elsevier B.V.

Hospital environments constitute the main reservoir of multidrug-resistant bacteria. In this study we aimed to investigate the presence of Gram-negative bacteria in one Northwestern Tunisian hospital environment, and characterize the genes involved in bacterial resistance. A total of 152 environmental isolates were collected from various surfaces and isolated using MacConkey medium supplemented with cefotaxime or imipenem, with 81 fermenter bacteria (27 Escherichia coli, and 54 Enterobacter spp., including 46 Enterobacter cloacae), and 71 non-fermenting bacteria (69 Pseudomonas spp., including 54 Pseudomonas aeruginosa, and 2 Stenotrophomonas maltophilia) being identified by the MALDI-TOF-MS method. Antibiotic susceptibility testing was performed by disk diffusion method and E-Test was used to determine MICs for imipenem. Several genes implicated in beta-lactams resistance were characterized by PCR and sequencing. Carbapenem resistance was detected among 12 isolates, nine E. coli (blaNDM-1 (n = 8), blaNDM-1 + blaVIM-2 (n = 1)) and three P. aeruginosa were carbapenem-resistant by loss of OprD porin. The whole-genome sequencing of P. aeruginosa 97H was determined using Illumina MiSeq sequencer, typed ST285, and harbored blaOXA-494. Other genes were also detected, notably blaTEM (n = 23), blaCTX-M-1 (n = 10) and blaCTX-M-9 (n = 6). These new epidemiological data imposed new surveillance strategies and strict hygiene rules to decrease the spread of multidrug-resistant bacteria in this area.

Statistical copolymers containing both carboxylate and hydroxyl functions have been synthesized in order to promote the dispersion of alumina suspensions in addition to the binding of pressed green disc-shaped specimens. In aqueous suspensions, the carboxylate groups are responsible for maintaining a high adsorption of the copolymer onto the alumina surface particles, thus increasing surface charges promoting a high electrostatic stabilization. The hydroxyl functions, which are not preferentially adsorbed on the surface i) participate in the steric stability of the suspension and, ii) confer a high mechanical resistance to green powder compacts compared to specimens classically shaped with 3 wt% of commercial polyvinyl alcohol and 1 wt% polyethylene glycol. Indeed, tensile stress to rupture evaluated by diametral compression is always greater than 3.5 MPa. The transition temperature of synthesized copolymers ranges from -10 to 57 °C, makes it possible to confer a plastic character to the organic system and to reach a high relative green density (around 63%) after compaction under 190 MPa at room temperature. Moreover, the effect of various molecular weights (from 11000 to 47000) on properties of spray-dried granules and of pressed compacts has been studied. A narrow spray-dried granule size distribution of corresponds to an optimal content of added copolymer, which in turn results in an optimal density of compacted parts. Optimal density values of the compacted parts follow the same trend as the highest particle size distribution corresponding to the optimal added copolymer content. The optimal values of densities correspond to an added amount of 1, 1.5 and 2 wt% respectively of high, medium and low copolymer's molecular weight.

International audience; Scaling process is the main problem encountered in industrial plants using water. Several factors, (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition),can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main component of scaling. In addition, some foreign ions added can considerably modified the scaling rates. In thiswork, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (≥ 1mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solutioncontaining 5 mg/L and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation moree fficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonatenucleation by changing the morphology of CaCO3 crystals

International audience; To deal with the contamination of the water environment, which represents an arena for microorganisms and antibiotics, a photocatalytic process has been proposed due to its high efficiency and non-toxicity. This review discusses and investigates antibiotics and antibiotic-resistant bacteria (ARB) removal and inactivation with their associated genes through photocatalysis technique as an efficient and ecofriendly advanced oxidation process (AOP) photocatalysis. The paper summarizes recent studies that dealt with both pollutants and their process parameters, optimal operating conditions, used semiconductor photocatalysts and their corresponding removal efficiency. Thus, it suggests that photocatalysis can offer impressive treatment efficiencies for both organic and microbial pollutants simultaneously. The review also states that both antibiotics and bacteria have a destroying effect against each other, where antibiotics have antimicrobial activity and bacteria have microbial degradation. This phenomenon creates a hybrid system for each pollutant (photocatalysis-bacteria, photocatalysis-antibiotic, bacteria-antibiotic), which accelerates the purification and disinfection of the polluted water caused by pathogens and hazardous pollutants using green and safe technology. Moreover, the reaction mechanism was detailed in order to define the role of reactive oxygen species (ROS). Likewise, photocatalysis coupling with other AOP techniques in this context was discussed to achieve more promising results. The main contribution of this review is to explain the relationship between antibiotics, microbial contaminants and photocatalysis. It also introduces a new area of study and concludes with an outlook on future research topics, such as viral disinfection. © 2021 Elsevier Ltd

International audience; Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity. 16S rRNA, rpoA and pheS gene sequencing, as well as the 16S-23S rRNA intergenic spacer analyses, were combined to identify strain Q1 as a strain of Enterococcus lactis. The bacteriocin produced by E. lactis Q1 is thermostable, active in the pH range from 4.0 to 9.0 and has a bactericidal mode of action. The enterocin P structural gene was detected by specific PCR in strain E. lactis Q1, which is in good agreement with SDS-PAGE data of the purified bacteriocin. A lack of significant antibiotic resistance genes and virulence determinants was confirmed by specific PCRs. This work provides the first description of an enterocin P producer E. lactis strain isolated from a fresh shrimp. Based on its safety properties (absence of haemolytic activity, virulence factors and antibiotic resistance genes), this strain has the potential to be used as a natural additive or adjunct protective culture in food biopreservation and/or probiotic culture.

International audience

Sorption isotherms remain a major tool to describe and predict the mobility of pollutants in natural and anthropogenic environments, but they are typically determined by independent batch experiments. In the present study, the sequestration of As(III), Cr(VI) and competitive As(III)-Cr(VI) on/in 6L-ferrihydrite, siderite and goethite nanostructured minerals was reinvestigated using stirred flow-through reactor experiments. Herein, sorption isotherms were particularly determined from breakthrough curves for inert and reactive tracers monitored simultaneously in a single percolation experiment. In complement, X-ray absorption spectroscopy (XAS) was used to identify As sorption sites on 6L-ferrihydrite and goethite. As expected, the minerals have high potential to remove As and Cr from water (siderite = ferrihydrite (about 60 mg/g) > goethite (20 mg/g)). As and Cr sorption isotherms were modelled with a Langmuir model, and with a sigmoidal Hill model in the case of the competitive sorption. XAS measurements have revealed that As(III) was partially oxidized (up to 22%) in the competitive system with chromate oxyanion Cr(VI). As(III) sorbed on ferrihydrite and goethite adopted edge-sharing and corner sharing complex geometries. Nowadays, a new class of adsorbing phases is being developed for wastewater treatment, including engineered nanostructured materials and nanocomposites. The use of flow through reactor experiments as a high throughput method, combined with XAS, should be considered as efficient screening methods to test their sorbing properties on various contaminants.

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International audience; The contamination of the marine environment by organic pollutants is a matter of great concern. Bizerte Lagoon is the second largest lagoon in Tunisia, and is known for different industry and fishing activities. The objective of this work is to investigate the distribution of seven polychlorinated biphenyls (PCBs) and nine organochlorine (OCPs) pesticides in water samples collected from the Lagoon of Bizerte. Extraction of water samples was performed by liquid–liquid extraction with hexane. Gas chromatography with 63Ni electron capture detector was used to perform qualitative and quantitative determinations. The average concentrations of OCPs were 0.42 and 14.92 ng L−1. For PCBs the concentrations range between 3 and 10.4 ng L−1. The predominant PCB congeners in the surface water were PCB 28 (0.2–1.4 ng L−1) and PCB 52 (0.8–3.5 ng L−1). The most widespread OCPs were DDTs with a concentration varied between ND and 8.51 ng L−1, heptachlor (ND and 7.83 ng L−1), and endrin (ND and 1.51 ng L−1). These concentrations are generally similar to the background levels from the Mediterranean Sea.

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Cyclic voltammetry ( CV ) and electrochemical impedance spectroscopy ( EIS ) were used to characterize the tarnished thin layer of silver deposited on glass. Instead of natural tarnishing in air environment, an acceleration of tarnishing process was realized by immersion of Ag covered glass in 10 μM K 2 S medium. The X-ray photoelectron spectroscopy ( XPS ) shows that tarnishing product formed on the silver surface consisted of Ag 2 S and Ag 2 O. As electrochemical characterization, the measurements were carried out in aerated 0.5 M Na 2 SO 4 solution adjusted at pH 10. The impedance spectra collected in sulphate medium at the open-circuit potential show one capacitive loop in parallel with a high resistance, which reflects a blocking electrode behaviour. However, the equivalent electrical circuit, R s -(CPE// R ) is insufficient to reproduce the experimental results correctly. To minimize the dispersion between the experimental and fitted data, the CPE contribution is replaced by two normal power-law distributions of the local resistivity to interpret the tarnishing process in K 2 S medium with respect to the immersion time. These distributions are associated with the Ag 2 S and Ag 2 O layers.

Use of lactic acid bacteria (LAB) as probiotics may provide an alternative to the use of antibiotics in aquaculture. Lstrains isolated from wild fish viscera and skin were evaluated for bacteriocin production and safety aspects (lack of antibiotic resistance, production of virulence factors). 16S rRNA gene sequences revealed the presence of Enterococcus faecium (13 isolates) and Lactococcus lactis (3 isolates) from fish samples. Pulsed-field gel electrophoresis analyses of the 13 enterococci isolates showed that they were all clustered, with greater than 95% similarity. However, RAPD analysis revealed significant molecular diversity between enterococci strains. Six enterococci strains were chosen and evaluated for their antibacterial activities. These strains produced a bacteriocin-like substance and exhibited a broad spectrum of inhibition against pathogenic bacteria isolated from diseased fish, including Streptococcus parauberis, Vagococcus spp., and Carnobacterium maltaromaticum, and in particular against the Gram-negative bacteria Flavobacterium frigidarium, Vibrio pectenicida, V. penaeicida, and Photobacterium damselae. The inhibition activity towards bacterial indicator strains was at a maximum when bacteria were grown at 37 degrees C. However, bacteriocin production was observed at 15 degrees C after 12 h of incubation. Only structural genes of enterocins A and B were detected by PCR in the 6 enterococci strains, suggesting the production of these enterocins. In addition, these strains did not harbor any virulence factors or any significant antibiotic resistance, and they tolerated bile. Our results suggest that enterococci are an important part of the bacterial flora of fish and that some strains have the potential to be used as probiotics.

International audience; The ability of exogenous compatible solutes, such as proline, to counteract cadmium (Cd) inhibitory effects in young date palm plants (Phoenix dactylifera L. cv Deglet Nour) was investigated. Two-year-old date palm plants were subjected for five months at different Cd stress levels (0, 10 and 30mg CdCl2kg(-1) soil) whether supplied or not with exogenous proline (20mM) added through the irrigation water. Different levels of Cd stress altered plant growth, gas exchanges and chlorophyll content as well as water status, but at different extent among them. In contrast, an increase of antioxidant enzymes activities of Cd-treated plants in association with high amounts of proline content, hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS) and electrolyte leakage (EL) were observed. Interestingly, exogenous proline mitigated the adverse effects of Cd on young date palm. Indeed, it alleviated the oxidative damage induced by Cd accumulation and established better levels of plant growth, water status and photosynthetic activity. Moreover, proline-treated plants showed high antioxidant enzymes activities (superoxide dismutase, catalase and glutathione peroxydase) in roots and leaves as compared to Cd-treated plants

International audience; This paper discusses two possible ways of intensifying the electrocoagulation treatment of water contg. phosphate. The first one consists of controlling the chem. compn. of the water by continuous adjustment of the pH. The second aspect focuses on electrode connection modes, and the four different modes were tested monopolar in series, in parallels and independents, and finally bipolar. Expts. were conducted in a small batch reactor contg. water with 100 mg P​/L using electrodes of aluminum. Several elec. connections were used for the water treatment under favorable operating conditions detd. by a study and presented in a previous paper. The influence of pH adjustment was conducted using different adjustment step times (no adjustment, every 30, 10 and 5 min)​. The kinetics of the treatment was found to be accelerated by continuous adjustment of the pH. The choice of the electrode connection modes was found to strongly affect the efficiency of the treatment, the Faradic yield, and the consumption of energy. The monopolar in parallels connection mode was found to be the most economic, whereas bipolar in parallels was found to favor a higher kinetic rate of treatment.

Treatment of water containing phosphate by electrocoagulation has been studied in a laboratory batch reactor. The effect of operating parameters on both phosphate removal efficiency and pH evolution has been investigated. Influence of distance between electrodes, current density, initial pH, temperature and conductivity has been extensively studied in a wide range of values. The results show that the removal efficiency depends on the electrical charges; the same efficiency is obtained with low current density with long time of treatment, or higher current intensity with short treatment time. The time evolution of the pH during the treatment strongly depends on the operating conditions but the final pH is more or less the same due to the buffering effect of Al ( OH ) 3 / Al ( OH ) 4 - mixture. Effects of the temperature, often disregarded in the literature shows that treatment rate is strongly increased with temperature whereas conductivity near 1 mS/cm is enough to ensure reasonable treatment rate. The electrical energy consumption (around 4 Kw/m3) is acceptable to achieve 90% of conversion but lower current density is preferable because of the lower voltage drop.

International audience; The effluent and washed ore show that treatment of ore enrichment is not aggressive. The results are supported by the projection factor, which clearly show the relationships between different elements and mineralogical composition of the effluents and washed ore.The results are a high concentration of 26-35% P2O5 (fluorapatite), but it remains carbonates (calcite anddolomite) in low quantity. The apatite show significant REE contents that can be by-product of phosphoric acid. Silicates and carbonates are the major part of effluents. The sulphate and fluoride contents are of the order of 3%, and the Na2O content varies between 1 and 1.5%, we observed a good correlation between F-P2O5-Na2O-P2O5 and P2O5-SO3.The levels of Cd, Zn, Cr, V, Ni, Sc, Nb and Cu are from the laundry reject. The maximum values of these elements are in the effluent from the M'DHILLA laundry.The Cd and Zn are found in high concentrations in the solid effluent. The high Cr content is linked with hydrocyclones in chromed steel. The washed phosphate ore was strongly depleted in heavy metals, which were concentrated in the fine fraction released into the hydric network and are thus the main cause of pollution in the region.

International audience; Electrochemical impedance spectroscopy was used to study the degradation behavior of thin multilayer stacks; Si3N4/Ag/Si3N4.Measurements were carried out in 0.5 M Na2SO4 adjusted at pH 10. The impedance data collected at the open circuit potentialwere analyzed with a physical model where all elements are clearly defined. The results suggest a constant phase element behaviorat the electrolyte dielectric interface assigned to an in-depth distribution of local resistivity through the dielectric layer induced bythe electrolyte penetration. To explain the electrochemical behavior of the thin silver layer, a localized corrosion in a delaminatedzone between the upper dielectric and the silver layers was adopted. The localized corrosion was found to be related to the granularstructure of the silver layer in which pores are formed between the grains of silver. This model is equivalent to a recently developeddouble porosity or pore-in-pore model.

http://www.mattech-journal.org; International audience; The electroless nickel plating on a conductive or insulating substrate is a widely used technique in various industries. The different deposition processes are relatively complex, and depend on several factors such as pH, temperature, composition of nickel baths and nature of the substrate. This review presents the effect of these parameters on the quality of the nickel deposit. Then, it focuses on the nickel electroless plating of plastics, and details the different stages of pre-treatment of this kind of material. During the different steps, toxic chemical products such as sulfochromic acid have always been used. To replace such products, environmentally friendly processes have been developed. Recent work on this topic as well as the effectiveness of the proposed methods are discussed at the end of this review.; Le dépôt chimique de nickel sur un substrat conducteur ou isolant est une technique très utilisée dans diverses activités industrielles. Les différents procédés de dépôt sont relativement complexes et dépendent de plusieurs facteurs tels que le pH, la température, la composition des bains de nickelage et la nature du substrat. Cette synthèse bibliographique présente les effets de ces paramètres sur la qualité du dépôt de nickel chimique. Elle met ensuite l’accent sur le nickelage chimique des matières plastiques et détaille les différentes étapes de pré-traitement de ce type de matériau. Au cours des différentes étapes, des produits toxiques tels que l’acide sulfochromique sont toujours utilisés. Afin de remplacer ces produits et répondre aux contraintes environnementales, plusieurs procédés respectueux de l’environnement ont éteé´laborés. Les derniers travaux sur ce thème ainsi que l’efficacité des méthodes proposées sont discutés en fin de revue.

Neroli essential oil is extracted from the fragrant blossoms of the bitter orange tree. It is one of the most widely used floral oils in perfumery. In this study chemical composition and in vitro antimicrobial and antioxidant activities of neroli oil are investigated. The essential oil of fresh Citrus aurantium L. Flowers (Neroli oil) cultivated in North East of Tunisia (Nabeul) were analyzed by GC-FID and GC-MS. About 33 compounds were identified, representing 99% of the total oil. Limonene (27.5%) was the main component followed by (E)-nerolidol (17.5%), alpha-terpineol (14%), alpha-terpinyl acetate (11.7%) and (E, E)-farnesol (8%). Antimicrobial activity was determined by Agar-well-diffusion method against 6 bacteria (3 Gram-positive and 3 Gram-negative), 2 yeasts and 3 fungi. Neroli oil exhibited a marked antibacterial activity especially against Pseudomonas aeruginosa. Moreover, Neroli oil exhibited a very strong antifungal activity compared with the standard antibiotic (Nystatin) as evidenced by their inhibition zones. Antioxidant activity determined by ABTS assay showed IC50 values of 672 mg L(-1). Finally, this study may be considered as the first report on the biological properties of this essential oil. The results of this study have provided a starting point for the investigations to exploit new natural substances present in the essential oil of C. aurantium L. flowers.

The thesis leaves an empirical report on the difficulties felt(experienced) by Tunisian pupils in final year and students in first year of university in touch with the notion of integral. It aims at studying these difficulties, at proposing a different teaching in final year of high school and at validating it by a didactic engineering. The first part is an epistemological and historic study of the articulations between the notions of area, integral and primitive. From these epistemological marks, and to refine the report of the difficulties underlined in the introduction, the second part questions the program and the official manual worker. The third led with students in first year of university informs about the knowledge which guard the new holders of high school diploma of the notions of area, integral and primitive. The engineering analyzed in the third part articulates around three questions: how to calculate the area of a surface polygonale? How to calculate the area of a surface not polygonale? How to calculate the integral of a continuous function? Three proposed situations center each around one of the questions by articulating them., La thèse part d’un constat empirique sur les difficultés éprouvées par des élèves tunisiens en classe terminale et des étudiants en première année d’université en rapport avec la notion d’intégrale. Elle vise à étudier ces difficultés, à proposer un enseignement différent en terminale et à le valider par une ingénierie didactique.La première partie est une étude épistémologique et historique des articulations entre les notions d’aire, d’intégrale et de primitive. A partir de ces repères épistémologiques, et pour affiner le constat des difficultés soulignées dans l’introduction, la seconde partie questionne le programme et le manuel officiel. Les objectifs généraux du programme accordent une place importante à la démarche expérimentale mais ceci est en contradiction avec les objectifs spécifiques à l’intégrale, que la thèse analyse comme privilégiant l’aspect calculatoire de l’intégrale. Cependant il semble qu’une approche problématisant la notion d’intégrale en partant d’une définition provisoire de la notion d’aire reste compatible avec le programme et conforme aux objectifs généraux. Ce n’est pas la démarche choisie par le manuel officiel qui ne rend pas suffisamment compte des liens entre aire, intégrale et primitive et sous-utilise les registres graphique et géométrique. L’analyse de la thèse est que le manuel vise surtout à faire acquérir des habitudes d’action en rapport avec le calcul de primitives. De façon à préparer l’ingénierie, la seconde partie mène aussi trois enquêtes. L’une porte sur les connaissances d’élèves de terminale sur la notion d’aire avant qu’ils n’abordent la notion d’intégrale. La seconde interroge des d’enseignants de la même classe sur leurs approches pour enseigner la notion d’intégrale. La troisième menée auprès d’étudiants en première année d’université renseigne sur les connaissances que gardent les nouveaux bacheliers des notions d’aire, d’intégrale et de primitive.L’ingénierie analysée dans la troisième partie s’articule autour de trois questions : Comment calculer l’aire d’une surface polygonale ? Comment calculer l’aire d’une surface non polygonale ? Comment calculer l’intégrale d’une fonction continue ? Les trois situations proposées se centrent chacune autour d’une des questions en les articulant. L’analyse a priori se base sur une étude de la structuration du milieu dans les tâches proposées et sur les opérations sémiotiques en jeu. L’analyse a posteriori étudie les contenus travaillés, ainsi que la logistique didactique déployée, notamment la répartition des rôles entre enseignants et élèves analysée en termes de contrats à différents niveaux et les incidents critiques. Elle permet notamment d’apprécier le potentiel adidactique de chacune des situations et le fait qu’elles sont adaptées à la majorité des élèves. L’ingénierie constitue ainsi un projet alternatif à celui que propose le manuel, et valide la possibilité de mettre en œuvre un enseignement rendant compte des liens entre aire, intégrale et primitive, et s’appuyant sur les registres graphique et géométrique pour complémenter les registres analytiques et formels. Les cadres théoriques principaux sont la théorie des situations avec les notions de milieux, de contrats et d’ingénierie didactique, et les registres sémiotiques. L’approche anthropologique est mobilisée pour l’étude des contenus et certains concepts liés à la double approche trouvent leur utilité dans l’analyse a posteriori de l’activité de la classe.

International audience; The influence of SO(4)(2-) ions on electrodeposition of two allotropic forms of CaCO(3) was studied in artificial underground Tunisian water. The study was performed using electrochemical, gravimetric, and optical methods. Chronoamperometric measurements confirmed the inhibiting effect of SO(4)(2-) ions, especially for concentrations higher than 2 x 10(-2) mol L(-1). The nucleation-growth process was observed by means of an optical microscope positioned behind a transparent electrode. The crystal growth of calcite and vaterite was recorded optically in situ, and image analysis software was used to characterize the instantaneous nucleation process and the growth rate of the crystals. Increased sulfate concentrations were found to modify the calcite morphology, whereas, the crystalline structure evolution of vaterite was found to be independent of the sulfate ion concentration. The use of coupled techniques allowed quantification of the influence of the SO(4)(2-) ions on the crystallization process of CaCO(3).

International audience; Nice Future Campus is today the first student virtual ID card encompassing a portfolio of mobiquitous NFC services within the SIM card (as a secure element): access control, mobiquitous payment inside the Campus, mobiquitous library, ticketing/couponing, public transport and Campus information with social networking. The three standardized NFC modes are implemented in this portfolio of services. This research project was conducted under contract with the Ministry of Industry (IPER) with a consortium of private companies.; Nice Future Campus (NFC) est aujourd’hui la première carte étudiante virtuelle multiservice mobiquitaire en Europe, embarquée dans un téléphone mobile NFC. Ce projetcomprend un bouquet de services embarqués dans la carte SIM d’un mobile NFC : gestion de tickets et coupons (utilisation du téléphone portable de la même façon qu’un ticket), contrôle d’accès, paiement au restaurant universitaire, bibliothèque mobiquitaire, transport public etinformations sur le campus avec accès aux réseaux sociaux via le mobile. Les trois modes du standard NFC sont expérimentés dans ce bouquet de services. Ce projet a été conduit dans le cadre d’un contrat IPER avec le ministère de l’Industrie et un consortium d’industriels avec un copilotage par le MBDS.

Dans le contexte de l'implantation de zones tampons pour limiter les flux de phytosanitaires transférés entre les parcelles agricoles et le milieu aquatique, cet article présente les résultats de simulations de l'efficacité d'une bande enherbée à limiter le ruissellement via HYDRUS 2D, un logiciel représentant les écoulements variablement saturés dans le sol. L'originalité du travail est de considérer une grande variété de caractéristiques de bandes enherbées, dans différents contextes agro-pédo-climatiques : La Morcille dans le Beaujolais viticole, aux sols très perméables, le Pays de Caux, aux sols très battants, et La Jaillière en Loire-Atlantique, aux sols fréquemment engorgés. Les résultats permettent de dégager de grandes tendances par type de milieu, tout en soulignant la nécessité de raisonner le dimensionnement de ces dispositifs au cas par cas. Quelques facteurs clés sont identifiés, qui permettent, sans passer par une simulation complète, de donner un ordre de grandeur de l'efficacité d'une bande enherbée à dissiper le ruissellement à partir de ses caractéristiques propres et de celles du ruissellement entrant. / Vegetated strips can be useful in order to limit pesticides fluxes transfered from agricultural fields towards surface waters. However, these structures must be judiciously positioned and well proportioned to be really efficient. In this article, we assess the efficiency of vegetative strips to limit surface runoff in contrasted situations, representative of different parts of France. The modelling tool is HYDRUS 2D, which represents variably saturated flow in soil. Three agro-pedo-climatic situations were investigated: 1 - La Morcille, in a vineyard area near Lyon, with very permeable soils and intensive runoff events, 2 Le Pays de Caux, where soils are very sensible to hortonian surface runoff, and 3 La Jaillière, near Brittany, where soils are often hydromorphic. Results show different trends for each ensemble of scenario, representative of a given agricultural area. They also get prominence to the fact that it remains necessary to design each vegetative strip individually, taking into account the very local context. The more influent variable were identified ; this allows to give an order of magnitude of the efficiency of a vegetative strip to limit surface runoff, without a complete simulation, given its own characteristics and those of incoming runoff.

Impact écotoxicologique des composés organiques présents dans les boues d’épuration valorisées par épandage sur les sols agricoles. 3ème Séminaire d’Écotoxicologie de l’INRA

http://www.mattech-journal.org; International audience; The electroless nickel plating on a conductive or insulating substrate is a widely used technique in various industries. The different deposition processes are relatively complex, and depend on several factors such as pH, temperature, composition of nickel baths and nature of the substrate. This review presents the effect of these parameters on the quality of the nickel deposit. Then, it focuses on the nickel electroless plating of plastics, and details the different stages of pre-treatment of this kind of material. During the different steps, toxic chemical products such as sulfochromic acid have always been used. To replace such products, environmentally friendly processes have been developed. Recent work on this topic as well as the effectiveness of the proposed methods are discussed at the end of this review.; Le dépôt chimique de nickel sur un substrat conducteur ou isolant est une technique très utilisée dans diverses activités industrielles. Les différents procédés de dépôt sont relativement complexes et dépendent de plusieurs facteurs tels que le pH, la température, la composition des bains de nickelage et la nature du substrat. Cette synthèse bibliographique présente les effets de ces paramètres sur la qualité du dépôt de nickel chimique. Elle met ensuite l’accent sur le nickelage chimique des matières plastiques et détaille les différentes étapes de pré-traitement de ce type de matériau. Au cours des différentes étapes, des produits toxiques tels que l’acide sulfochromique sont toujours utilisés. Afin de remplacer ces produits et répondre aux contraintes environnementales, plusieurs procédés respectueux de l’environnement ont éteé´laborés. Les derniers travaux sur ce thème ainsi que l’efficacité des méthodes proposées sont discutés en fin de revue.

International audience; AgxO/Ag/TiO2 photoactive thin films were produced by different modes of magnetron sputtering (namely, DCMS and HiPIMS). The spectral and microstructural properties of the Ag-AgxO/TiO2 thin films were studied by Diffuse Reflection Spectroscopy (DRS) and X-ray Photoemission Spectroscopy (XPS). The atomic deposition of TiO2 and Ag in the thin sputtered film were studied by TEM. AgxO/Ag/TiO2 exhibited fast photocatalytic volatile organic compounds (VOCs) degradation and bacterial inactivation under low visible light intensity. The Langmuir Hinshelwood model was applied to highlight the photocatalytic performance of the AgxO/Ag/TiO2 catalyst. The oxidative states of Ag-AgxO/TiO2 were studied by XPS. Deconvolution of the Ag3d peak of the AgxO/Ag/TiO2 thin films showed the presence of AgO and metallic Ag. It is suggested that the mechanism involving the degradation of VOCs on AgO/Ag/TiO2 catalysts is due to the transfer of holes from AgO to TiO2 via the AgO/Ag/ TiO2 heterojunction. The electrostatic interaction between both semiconductors allows this charge transfer. In addition, the contribution of reactive oxygen species (ROS) in bacterial inactivation at the interface of AgO/Ag/ TiO2 thin film was also examined. Light-induced interfacial charge transfer (IFCT) between AgO and TiO2 leading to pollutants oxidation appears to require low photons' energy and can oxidize pollutants even at high concentrations. The sputtered coatings have also been studied for repetitive reuse, showing the sustainable activity of the prepared materials.