Hg(II) trace electrochemical detection on gold electrode: Evidence for chloride adsorption as the responsible for the broad baseline

Investigations were performed in order to clarify the origin of the broad baseline observed during Hg(II) trace electrochemical detection on gold electrode in the presence of Cl- anions. The influence of Cl- concentration on the shape of the voltammograms was studied in the presence and in the absence of Bovine Serum Albumin (BSA) in order to bring out adsorption/desorption processes. On the basis of these experiments, and contrary to what has been proposed by several authors in the literature, it was proved that the broad baseline does not result from calomel (Hg2Cl2) formation but is rather related to an interaction between Cl- and polycrystalline Au electrode surface. The evolution of the shape of the baseline was also studied in the presence of other halide anions, namely F-, Br-, and I-. The latter two were found to induce a broad baseline similar to that recorded in the presence of Cl-. Finally, it was shown that BSA addition is not suitable for Hg(II) detection since it prevents Hg(0) deposition onto the electrode surface

Key Performance Indicators (KPIs) as Agents for Balancing Industry Needs and Biodiversity Conservation in Manufacturing

The manufacturing industry has a significant negative impact on animals and their habitats. This paper explores the potential of sustainable manufacturing practices to mitigate these impacts. We conducted a comprehensive study of key performance indicators (KPIs) and their influencing factors for sustainability in manufacturing for small and medium-sized enterprises (SMEs) in India. Our findings suggest that KPIs such as social innovation, health and safety, green innovation, waste management, energy conservation, customer lifetime values, and net profit margin are all important factors in sustainability. We also found that these KPIs have high reliability, with Cronbach’s alpha of 0.8 and McDonald’s index of 0.75. Our research provides a framework for assessing sustainability in manufacturing and identifies opportunities for SMEs to reduce their negative impact on animals and their habitat

Laura Sigg: Investigating the Speciation, Bioavailability and Ecotoxicology of Trace Metals in Natural Waters

Laura Sigg is an internationally renowned expert in the aquatic geochemistry and ecotoxicology of trace metals. During her outstanding career as a researcher at Eawag, the Swiss Federal Institute of Aquatic Science and Technology, and adjunct professor at the Department of Environmental Systems Science of ETH Zurich, she pioneered the development of new theoretical concepts as well as practical methods for the assessment of the speciation, fate and effect of trace metals in the hydrosphere (Fig. 1). During his stay in Toulouse as invited professor some years ago, George Luther III proposed us to edit a special issue of Aquatic Geochemistry to honor our colleague Laura Sigg, who serves as a long-term associate editor of this journal. We were very happy to take up this challenge and invited people to submit original manuscripts to a special issue focusing on the fields of speciation, bioavailability and ecotoxicology of trace metals in natural waters. After being educated in chemistry with Paul W. Schindler at the University of Bern, where she learned the precision and rigor of experimental work and how to assess and synthetize ideas, Laura Sigg moved to Zurich and worked for her PhD with Werner Stumm. She started the first part of her career with ground-breaking research on thermodynamic models for adsorption processes at the solid–water interface and published two highly influential papers which became classics in this field (Stumm et al. 1980; Sigg and Stumm 1981)

Influence of the gold nanoparticles electrodeposition method on Hg(II) trace electrochemical detection

Gold nanoparticles (AuNPs) were deposited on Glassy Carbon (GC) substrate by using three electrochemical techniques: Cyclic Voltammetry (CV), Chronoamperometry (CA) and Potentiostatic Double-Pulse (PDP). For each electrodeposition method, the resulting AuNPs-modified electrodes were characterized by CV in H2SO4 and Field Emission Gun Scanning Electron Microscopy (FEG-SEM). CA was found to be the best electrodeposition mode for controlling the morphology and the density of AuNPs. The modified electrodes were used for low Hg(II) concentration detection using Square Wave Anodic Stripping Voltammetry (SWASV). AuNPs obtained by CA afforded the best amperometric response while involving the lowest amount of charge during the electrodeposition step (QAu(III)). This analytical response is correlated to both the smallest particle size (ca. 17 nm in diameter) and the highest particle density (332 particles μm−2), thus displaying high electrode effective surface area. In these optimal conditions, using a Hg(II) preconcentration time of 300 s, the nanosensor array exhibited a linearity range from 0.80 to 9.9 nM with a sensitivity of 1.16 μA nM−1. A detection limit of 0.40 nM (s/n = 3) was reached

Research practices and support needs of Language and Literature faculty at the University of Utah

ReportThis report investigates the research practices and support needs of Language and Literature scholars at the University of Utah

Sources et cheminements des polluants

Dans l’environnement, un ensemble complexe de processus chimiques, physiques, biologiques et géologiques régule le cycle des éléments et des composés chimiques. La composition des eaux, qui résulte de ces processus, est naturellement contrôlée par l’altération des minéraux qui consomme du CO2 atmosphérique et l’activité des organismes vivants. Les activités anthropiques génèrent des contaminants véhiculés dans les différents compartiments interdépendants: eaux, biosphère, atmosphère, sol et roches). Pour comprendre le cheminement des composés dans les eaux, il faut tenir compte du trajet des eaux dans chaque compartiment et des relations entre les compartiments. Les processus physico-chimiques sont associés aux échanges entre les phases dissoutes et solides particulaires , aux interactions avec les organismes, ainsi qu’aux processus physiques. Ceux-ci sont plus ou moins fortement perturbés par les activités humaines, dont l’expansion et l’intensification accroissent la dispersion des polluants dans les milieux naturels. Il en est ainsi des flux de certains polluants qui peuvent être très largement supérieurs aux flux d’éléments naturels libérés par l’érosion chimique et les interactions avec les organismes

Adsorption of Copper, Nickel, and Cadmium on Goethite in the Presence of Organic Ligands

Adsorption of copper, cadmium and nickel at low concentrations on goethite was studied in the presence of the simple organic ligands oxalate, salicylate, and pyromellitate. The experimental metal adsorption behavior was compared to calculations with a surface complexation model to evaluate the most important interactions. Oxalate mostly decreased Cu and Ni adsorption at high pH-values by competition between solution and surface complexation but had no effect on Cd adsorption. Cu adsorption in the presence of oxalate below pH 6 could best be described by defining a ternary complex of type A (surface-metal-ligand). Salicylate had only minor effects on metal adsorption. The adsorption of Cu in the presence of salicylate above pH 5 could be explained by a ternary complex of type A. Pyromellitate increased the adsorption of Cu and Cd in the acidic pH-range, likely by formation of ternary surface complexes of type B (surface-ligand-metal

Anne Feunteun (2015) Des enfants et des langues à l’école. Les Éditions Didier, collection Langues & didactique, Paris ; 310 pp.

Vingt années de travail comme didacticienne, praticienne, formatrice et chercheure en France et en Europe sur la place des langues à l’école et leur enseignement aux enfants ont permis à Anne Feunteun de publier cet ouvrage en 2015. Elle y rassemble des connaissances référencées sur les travaux de recherche réalisés en DDLC et présente une synthèse diachronique des dynamiques de mise en œuvre de cet enseignement. Des enfants et des langues à l’école s’apparente à un état de l’art prenant appu..

L'appropriation de la notion de plurilinguisme : étude de cas sur les conceptions initiales d'étudiants - futurs enseignants à l'école primaire en France

Diese Studie untersucht die anfängliche Auffassung des Konzepts der Mehrsprachigkeit in der Ausbildung von zukünftigen Lehrkräften der ersten Stufe an einem Institut national supérieur du professorat et de l’éducation (Inspé) in Frankreich.  Sie stützt sich auf die Ergebnisse eines Fragebogens, der an drei Studierendengruppen im Rahmen des Moduls „Didaktik der Sprachen und Kulturen“ unterbreitet wurde. Direkte und indirekte Fragen zielen darauf ab, die Vorstellungen der Studierenden zum Konzept Mehrsprachigkeit hervorzurufen und Versuche zu initiieren, diesen Begriff zu definieren. Der Fragebogen erfasst außerdem die jeweils studierten Fremdsprachen der Studierenden, deren künftige berufliche Aufgabe darin besteht, im Primarbereich zum Unterricht einer fremden Sprache und Kultur beizutragen. Schließlich wird untersucht, welches Unterrichtsmodell die Studierenden anhand von real erlebten und übertragbaren Situationen bevorzugen. Die Analyse der Gesamtheit der Daten ermöglicht es, Anforderungen an die Lehrerausbildung neu zu hinterfragen und neue Perspektiven anzuvisieren, und somit die Reflexion über Ausbildungsfragen zu bereichern.This study examines the initial conception of the notion of plurilingualism in the training of future primary school teachers in an Institut national supérieur du professorat et de l’éducation (Inspé) in France. It is based on the results of a questionnaire administered to students in three groups of a language-culture didactics module. Direct and indirect questions aim to bring out the students' representations of the notion of plurilingualism on the one hand, and their attempts to define this notion one the other. The questionnaire also asks students about their language of specialisation as future professionals whose task will be to participate in the teaching of a foreign language-culture in primary school. Finally, we wanted to see which teaching model the respondents prefer, based on real-life and transferable situations. The analysis of the data collected enables us to re-examine training issues and to project some perspectives to improve our reflection on training.L’étude présentée a pour but d’interroger la conception initiale de la notion de plurilinguisme en formation de futurs enseignants du premier degré dans un Institut national supérieur du professorat et de l’éducation (Inspé) en France. Elle prend appui sur les résultats d’un questionnaire administré aux étudiants de trois groupes d’un module de didactique des langues-cultures. Des questions directes et indirectes visent à faire émerger d’une part les représentations des étudiants sur la notion de plurilinguisme, et d’autre part leurs tentatives de définition de cette notion. Le questionnaire interroge aussi les étudiants sur leur langue de spécialité en tant que futurs professionnels dont la mission consistera à participer à l’enseignement d’une langue-culture étrangère à l’école primaire. Enfin, nous avons voulu voir quel modèle d’enseignement préfèrent les répondants à partir de situations vécues et transposables. L’analyse des données recueillies permet de réinterroger des enjeux de formation et de projeter quelques perspectives pour enrichir la réflexion sur la formation

Effect of the presence of pyrite traces on silver behavior in natural porous media

In order to better understand the fate of the toxic element Ag(I), sorption of Ag(I) was studied from batch experiments, at different pHs (2–8) and at 298K. A pure quartz sand (99.999% SiO2) and “natural” quartz sand (99% SiO2, and traces of Fe, Al, Mn (hydr)oxides, of clays and of pyrite) were used as sorbents. The Ag(I) sorption behavior depends strongly on pH with isotherm shapes characteristic of Langmuir-type relationship for initial Ag concentration [Ag(I)], range between 5.0×10−7 and 1.0×10−3M. Even if the Ag (I) sorption capacity on pure quartz sand is very low compared to the natural quartz sands, its affinity is rather high. From speciation calculations, several sites were proposed: at pHi 4, 6 and 8, the first surface site is assumed to be due to iron (hydr)oxides while the second surface site is attributed to silanols. At pHi 2, sorption of Ag(I) was assumed to be on two surface sites of iron (hydr)oxides and a third surface site on silanol groups. Even if the sand is mainly composed of silica, the trace minerals play an important role in sorption capacity compared to silica. The conditional surface complexation constants of Ag(I) depend on pH. On the other hand, it is shown that the Ag speciation depends strongly on the history of “natural” quartz sand due to initial applied treatment, little rinsing or longer washing. In the presence of low amount of pyrite, strong complexes between Ag(I) and sulfur compounds such as thiosulfates due to oxidative dissolution of pyrite are formed what decreases Ag sorption capability. SEM–EDS analyses highlighted the surface complexation–precipitation of Ag2S and Ag(0) colloids which confirmed the important role of pyrite on Ag(I) speciation