Effects of fish farming on flavonoids in Posidonia oceanica

This work is a first approach to flavonoid responses (total proanthocyanidins and total and simple flavonols) in Posidonia oceanica in function of nutrient enrichment (aquaculture activities - fish farming), in the western Mediterranean Sea (Calvi-Corsica-France). The first result is the presence of total and simple flavonoids in P. oceanica. The second result shows an increase in total proanthocyanidin and total flavonol concentrations near cages, which would be linked to the high grazing pressure induced by meadow enrichment. Concerning simple flavonols, only quercetin shows a response to fish farming, which could be due to its strong antioxidant capacity. The presence of fish farming, which causes variations in environmental parameters, could affect the functioning of P. oceanica meadows. Flavonoid concentrations in P. oceanica seem to be a possible bioindicator of nutrient enrichment for the management of the littoral environment.     

Caractérisation d'une pratique d'enseignement des mathématiques : Le cours dialogué

Résumé

L'objet de cet article est de caractériser une pratique d'enseignement des mathématiques que nous nommons cours dialogué, observée dans des classes ordinaires à la fin du collège en France (élèves de 13 à 15 ans) et que nous pensons plus largement utilisée. Pour cela, différentes composantes du contrat didactique sont utilisées en association avec une étude des interactions didactiques observées dans la classe. La méthode d'étude et les composantes du contrat didactique ainsi que les variables des interactions utilisées sont présentées dans les paragraphes 2 et 3 de l'article. Ensuite, ces outils sont utilisés pour analyser une séquence sur la proportionnalité, ce qui permet de dégager les caractéristiques du cours dialogué, notamment en termes de contrat didactique et de fonctions des interactions, par comparaison avec d'autres types d'enseignement mieux connus, la transmission directe du savoir et la transmission du savoir par des situations.     

A GC–FID Method to Determine Styrene in Polystyrene Glasses

The styrene levels of polystyrene (PS) glasses from the most consumed brands of disposable glasses intended for water and coffee in Brazil were determined. A GC–FID method was developed and validated, showing good precision and accuracy. The method was successfully used to determine styrene in 11 PS glass brands. The styrene levels ranged from 1.68 to 43.69 mg/100 g glass, depending on the kind of polymer, thickness, and glass brand. It could be used to control the content of styrene in the polymer. The migration of styrene from the glasses into water and 20 % ethanol was not detected.     

Polychlorinated biphenyls and hydroxylated polychlorinated biphenyls in plasma of bottlenose dolphins (Tursiops truncatus) from the Western Atlantic and the Gulf of Mexico

Polychlorinated biphenyls (PCBs) and hydroxylated metabolic products (OH-PCBs) were measured in plasma collected from live-captured and released bottlenose dolphins (Tursiops truncatus) from five different locations in the Western Atlantic and the Gulf of Mexico in 2003 and 2004. In 2004, the sum (sigma) of concentration of PCBs in plasma of dolphins sampled off Charleston, SC [geometric mean: 223 ng/g of wet weight (w.w.)] was significantly higher (p<0.05) than concentrations detected in animals from the Indian River Lagoon, FL (sigmaPCBs: 122 ng/g w.w.) and the Sarasota Bay, FL (sigmaPCBs: 111 ng/g w.w.). The PCB homolog profiles were similar among locations. Concentrations of OH-PCBs were significantly higher (p<0.05) in plasma of dolphins from Charleston, SC (sigmaOH-PCBs for 2003: 126 ng/g w.w.; 2004: 138 ng/g w.w.) than animals from Florida (sigmaOH-PCBs ranged from 6 to 47 ng/g w.w.) and Bermuda (8.3 ng/g w.w.); however, concentrations in the Charleston samples did not differ from animals captured in Delaware Bay, NJ (57 ng/g w.w.). The sigmaOH-PCBs constituted 2-68% of the total PCB concentrations in plasma. Dichloro- to nonachloro-OH-PCBs were quantified using high-resolution gas chromatography mass spectrometry, but only around 20% of OH-PCBs could be identified by comparison to authentic standards. Results from this study show that OH-PCB are important environmental contaminants in dolphins and suggest that PCBs, decades after their ban, may still constitute a threat to wildlife.     

Application of magnetic iron oxide nanoparticles prepared from microemulsions for protein purification

BACKGROUND: Magnetic nanoparticles are of immense interest for their applications in biotechnology. This paper reports the synthesis of magnetic iron oxide nanoparticles from two different water‐in‐oil microemulsion systems (ME‐MIONs), their characterization and also their use in purification of coagulant protein. RESULTS: ME‐MIONs have demonstrated to be an efficient binder in the purification of Moringa oleifera protein when compared with the superparamagnetic iron oxide nanoparticles prepared from coprecipitation in aqueous media. The size and morphology of the ME‐MIONs were studied by transmission electron microscopy (TEM) while the structural characteristics were studied by X‐ray diffraction (XRD). The microemulsion magnetic iron oxide nanoparticles (ME 1‐MION and ME 2‐MION) obtained have a size range 7–10 nm. The protein and ME‐MIONs interaction was investigated by Fourier transform infrared spectroscopy (FT‐IR); the presence of three peaks at 2970, 2910 and 2870 cm^?1 respectively, confirms the binding of the protein. The purification and molecular weight of the coagulant protein was 6.5 kDa as analyzed by SDS‐PAGE. CONCLUSION: The ME‐MIONs have the advantage of being easily tailored in size, are highly efficient as well as magnetic, cost effective and versatile; they are, thus, very suitable for use in a novel purification technique for protein or biomolecules that possess similar characteristics to the Moringa oleifera coagulant protein. Copyright © 2011 Society of Chemical Industry     

Pragmatic evaluation of fin height and fin width combined variation impact on the performance of junctionless transistors

Journal of Computational Electronics - This work performs a pragmatic evaluation of the different junctionless devices architectures with channel lengths down to 30&nbsp;nm on their electrical...     

Behavioral Effects of Basal Forebrain Cholinergic Lesions in Young Adult and Aging Rats.

The interactive effects of age and cholinergic damage were assessed behaviorally in young and middle-aged rats. Rats were lesioned at either 3 or 17 months of age by injection of 192 IgG-saporin immunotoxin into the medial septum and the nucleus basalis magnocellularis, and they were then tested on a range of behavioral tasks: a nonmatching-to-position task in a T-maze, an object-recognition task, an object-location task, and an open-field activity test. Depending on the task used, only an age or a lesion effect was observed, but there was no Age X Lesion interaction. Middle-aged and young rats responded to the cholinergic lesions in the same manner. These results show that in the middle-aged rats in which cholinergic transmission was affected, additional injury to the system was not always accompanied by major cognitive dysfunctions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Liquid vapour phase change on a single nucleation site: Heat and mass transfer

In this paper experimental results of heat and mass transfer variations during a single vapour bubble growth are carried out. The vapour bubble was created in a FC-72 liquid, on a downward facing heating element maintained at constant heating power. Heat flux and temperature measurements combined with image processing enable us to study the influence, on heat transfer, of the level of liquid subcooling, the heating power applied on the nucleation surface and the nucleation surface’s inclination. It was found that the phase change heat flux (i.e. the difference between the flux of evaporation and the flux of condensation) and the total heat flux (measured with fluxmeter and due to convection, conduction and phase change) decreased in the same order of magnitude when the level of subcooling was increased. When the heating power increased, the total heat flux increased whereas the phase change heat flux varied in a non-significant way. It was also found that the total heat flux depends on the nucleation surface inclination, whereas, for small angles, the phase change heat flux didn’t change. The analysis of those results lead to the conclusion that during boiling the liquid motions due to the bubble growth and departure play an important role in the heat transfer enhancement.     

Role of the tyrosine corner motif in the stability of neocarzinostatin

Although the immunoglobulin-like ß-sandwich fold hasno specifically conserved function, some common structural featureshave been observed, in particular a structural motif, the tyrosinecorner. Such a motif was described in neocarzinostatin (NCS),a bacterial protein the structure of which is very similar tothat of the immunoglobulin domain. Compared with the other ß-sheetproteins, the NCS ‘tyrosine corner’ presents non-standardstructural features. To investigate the role of this motif inthe NCS structure and stability, we studied the properties ofa mutant where the H bond interaction had been eliminated byreplacing the tyrosine with a phenylalanine. This mutation costs4.0 kcal/mol showing that the NCS ‘tyrosine corner’is involved in protein stability as in the other Greek key proteins.This destabilization is accompanied by remote structural effects,including modification of the binding properties, suggestingan increase in the internal flexibility of the protein. Witha view to using this protein for drug targeting, these resultsalong with those obtained previously allow us to define clearlythe limitations of the modifications that can be performed onthis scaffold. Received December 3, 2002; revised June 6, 2003; accepted September 3, 2003.     

Control of Lipase Enantioselectivity by Engineering the Substrate Binding Site and Access Channel

Lipase from Burkholderia cepacia (BCL) has proven to be a very useful biocatalyst for the resolution of 2‐substituted racemic acid derivatives, which are important chiral building blocks. Our previous work showed that enantioselectivity of the wild‐type BCL could be improved by chemical engineering of the substrate's molecular structure. From this earlier study, three amino acids (L17, V266 and L287) were proposed as targets for mutagenesis aimed at tailoring enzyme enantioselectivity. In the present work, a small library of 57 BCL single mutants targeted on these three residues was constructed and screened for enantioselectivity towards (R,S)‐2‐chloro ethyl 2‐bromophenylacetate. This led to the fast isolation of three single mutants with a remarkable tenfold enhanced or reversed enantioselectivity. Analysis of substrate docking and access trajectories in the active site was then performed. From this analysis, the construction of 13 double mutants was proposed. Among them, an outstanding improved mutant of BCL was isolated that showed an E value of 178 and a 15‐fold enhanced specific activity compared to the parental enzyme; thus, this study demonstrates the efficiency of the semirational engineering strategy.