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Villeneuve-la-Rivière, France

Essadki A.H.,Ecole Superieure de Technology de Casablanca | Nikov I.,ProBioGEM | Delmas H.,ENSIACET
Canadian Journal of Chemical Engineering

A detailed study of the effects of individual bubbles at high gas flow-rate has shown, that the dominant influence on skin friction over a solid sphere is the bubble volume in compared to bubble frequency. Nevertheless the bubble frequency is very important in case of low gas flow-rate. Referring to bubbles produced by a gas distributor, statistical and spectral analyses were performed to study the influence of bubbling on exposure time and magnitude of fluctuations. Referring to a calibrated bubble train, the existence of critical frequency is demonstrated. A bubble with larger volume and a mobile, oscillatory surface generates larger velocity gradient. In the case of gas distribution, histograms of the velocity gradient for a 2mm glass sphere creating bubble coalescence reveal the maximum exceeds 48000s -1 in the front zone and 2000s -1 in the rear zone (θ=180°). For 5mm plastic spheres creating bubble break-up, the maximum of the velocity gradient is only 8100s -1 for the front part of the sphere and 2000s -1 in the rear zone. © 2011 Canadian Society for Chemical Engineering. Source

Picot L.,University of La Rochelle | Ravallec R.,ProBioGEM | Martine F.-P.,French National Center for Scientific Research | Vandanjon L.,University of Nantes | And 18 more authors.
Journal of the Science of Food and Agriculture

BACKGROUND: Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides. RESULTS: The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classesbeingfoundinseveral fractions. Peptides containing Pro, Hyp, Aspand Gluwere concentrated in the UF and NFretentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin-likepeptideswerepresent in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene-related peptide (CGRP)-like peptides demonstrated an increase in CGRP-like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin-converting enzyme (ACE)-1 inhibitory activity, which were not increased by UF and NF fractionation. CONCLUSION: Fractionation of an FPH using membrane separation, with a molecular weight cut-off adapted to the peptide composition, may provide an effective means to concentrate CGRP-like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut-off of the membrane only, as is currently done in the literature. © 2010 Society of Chemical Industry. Source

Net S.,Lille University of Science and Technology | Dumoulin D.,Lille University of Science and Technology | El-Osmani R.,Lille University of Science and Technology | Delcourt V.,Lille University of Science and Technology | And 2 more authors.
Applied Geochemistry

Extraction and analysis of organic pollutants from matrices such as sediment constitute an essential step in environmental research. However, the extraction for quantitative analysis can turn out to be difficult because these compounds are present in trace levels and can be strongly bound to the sorbent matrix. Consequently, accuracy of environmental analyses mainly depends on the efficiency and the robustness of the extraction step. In this work, a sequential ASE extraction procedure was applied to the extraction of polycyclic aromatic and aliphatic hydrocarbons (PAHs, Me-PAHs and n-alkanes) in sediment samples. The extraction protocol was developed for 26 PAHs, including the 16 PAHs of the United-States Environmental Protection Agency (EPA) priority list, for 17 alkylated PAHs homologues and for 29 n-alkanes (from n-C12 to n-C40). A set of 30 experiments was carried out for the determination of the optimal extraction conditions. The four parameters studied were pressure, temperature, extraction time and nature of the solvent. Extracts were analyzed by gas chromatography (GC-MS and GC-FID) after clean-up and concentration. The optimal extraction conditions selected for pressure, temperature, extraction time and nature of solvent were respectively 14MPa, 160°C, 24min and hexane/acetone (1/1 v/v). The analytical procedure was validated by comparing predicted and experimental values of sediment samples and by analyzing standard reference material. The validated method was then applied to establish a depth profile contamination in the sediment of the DeÛle River in Northern France. © 2013 Elsevier Ltd. Source

d'Haese R.,Ecole Nationale Superieure de Chimie de Lille | Pawlowski L.,Ecole Nationale Superieure de Chimie de Lille | Bigan M.,ProBioGEM | Jaworski R.,Ecole Nationale Superieure de Chimie de Lille | Martel M.,University Of Lille1
Surface and Coatings Technology

Fine, hydroxyapatite (HA) powder, synthesized using calcium nitrate and diammonium nitrate was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto titanium substrates. The deposition process was optimized using statistical design of 2n experiments with two variables: spray distance and electric power input to arc plasma. The sprayed coatings were soaked in simulated body fluid (SBF) for the periods of 3, 7, 14, 28, and 60 days at controlled temperature of 37 °C. The reference intensity ratio (RIR) method basing onto X-ray diffraction (XRD) data was used to determine quantitatively the phase composition of as-sprayed and soaked deposits. Electron probe microanalysis (EPMA) enabled to make the profiles of calcium to phosphorus atomic ratio along a line though the coatings' cross sections. Raman spectroscopy of selected samples enabled to localize the different crystal phases in sprayed coatings. The coatings included some porosity and have two characteristic zones: (i) dense zone corresponding to the lamellas, observed usually in thermally sprayed coatings; (ii) sintered zone containing fine hydroxyapatite grains which correspond to the fine solids from the suspension which were agglomerated in the cold regions of plasma jet and sintered on the substrate. The soaking in SBF homogenizes the morphology of coatings. The sintered zone disappears and the pores get filled by the reprecipitated calcium phosphates. © 2009 Elsevier B.V. All rights reserved. Source

Ashraf M.,GEMTEX | Dumont F.,University of Valenciennes and HainautCambresis | Campagne C.,French National Graduate School of Textile Engineering | Champagne P.,University of Valenciennes and HainautCambresis | And 3 more authors.
Journal of Engineered Fibers and Fabrics

ZnO nanorods were grown on polyester fabric by hydrothermal process. The seeding of fabric to grow ZnO nanorods was necessary because they did not grow without seeding. An air plasma treatment was carried out on polyester fabric to generate polar groups which could attach ZnO seeds. ZnO nanorods were grown on these seeds. The generation of polar groups was confirmed by XPS analysis. The morphology of nanorods was characterized with SEM and TEM. The quantity of ZnO deposited on fabric in the form of nanorods was estimated to be 5.6% w/w by atomic absorption spectroscopy. Two Gram negative bacteria; Escherichia coli and Pseudomonas aeruginosa and a Gram positive; Staphyloccocus aureus were used for antibacterial activity evaluation by qualitative method. E. coli and S. aureus were used for quantitative assessment by using NF ISO 20743: 2009 Transfer Method. It was noted that the functionalized fabric prevented the growth of bacteria not only on and below the fabric but also in the immediate proximities for all three bacteria. It was also observed that the fabric was more effective against Gram positive as compared to Gram negative bacteria. Moreover, it was shown that UV pre-activation of functionalized fabric enhanced the antibacterial activity. Source

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