Field transfer of periphytic diatom communities to assess short-term structural effects of metals (Cd,Zn) in rivers

Short-term effects of metal pollution were assessed by transferring periphytic diatom communities developed on artificial substrates from a reference site to a site polluted by heavy metals (around 15 microg Cd L(-1) and 800 microg Zn L(-1)), located in neighbouring streams. Metal sensitivity of mature assemblages (aged 1 month) was evaluated by studying changes in diatom density and taxonomic composition 2 and 4 weeks after the transfer. Resident communities of both sites were simultaneously collected on similar artificial substrates, in order to compare short-term effects of metals within transferred communities with long-term effects observed at the polluted site. Field transfer induced a marked shift of community structure towards that of the resident community of the polluted site: diatom density rapidly decreased after the transfer, from 35,000+/-4000 to 15,000+/-300 cells cm(-2) after 2 weeks, and taxonomic composition changed. Relative abundances of species characteristic of the reference site rapidly decreased, e.g. Nitzschia dissipata and Gomphoneis minuta, whereas species characteristic of the polluted site progressively increased within transferred communities, e.g. Gomphonema parvulum, Pinnularia sp. or Fragilaria crotonensis. The structure of periphytic diatom communities could therefore be an indicator of metal pollution, with marked taxonomic changes being identified within reference assemblages after only 2 weeks under relatively low metal exposure.     

Influence of Suspension Plasma Spraying Process Parameters on TiO2 Coatings Microstructure

The study aimed at optimizing the suspension plasma spraying of TiO₂ coatings obtained using different suspensions of fine rutile particles in water solution onto aluminum substrates. The experiments of spraying were designed using a 2³ full factorial plan. The plan enabled to find the effects of three principal parameters, i.e. electric power input to plasma, spray distance, and suspension feed rate onto microstructure of coatings, content of anatase phase and size of anatase crystals in the coatings. The microstructure of deposits was observed with scanning electron microscope (SEM) and optical microscope and their composition was characterized using energy dispersive spectrometry (EDS). The observations were made on the coatings surface and their cross-sections. The latter made it possible to determine the coatings thicknesses to be in the range from 8 to 33 μm.

Nickel adsorption by magnetic alginate microcapsules containing an extractant

The adsorption of heavy metals on biomaterials was investigated by studying the potential of alginate microcapsules containing an extractant (Cyanex 272) and magnetic nanoparticles (gamma-Fe2O3) for the adsorption of nickel (II) from aqueous solutions. A two-stage kinetics behaviour was observed with 70% of the maximum sorption capacity achieved within 8 h. An increase in nickel removal with increase in pH occurred, the maximum uptake capacity being around 0.42 mmol g-1 at pH 8. The adsorption isotherm (pH about 5.3) was obtained in a wide range of initial nickel concentrations; the experimental data were fitted by a Langmuir model and the qmax value was estimated to be 0.52 mmol g-1. Moreover, including magnetic particles in the microcapsules allowed easy isolation of the beads from the aqueous solutions after the sorption process. Magnetic microcapsules are then suitable for the development of efficient biosorbents for removal and recovery of heavy metals from wastewater using magnetic separation.     

Room temperature electrical manipulation of giant magnetoresistance in spin valves exchange-biased with BiFeO3

Magnetoelectric multiferroics are attractive materials for the development of low-power electrically controlled spintronic devices. Here we report the optimization of the exchange bias as well as the giant magnetoresistance effect (GMR) of spin valves deposited on top of BiFeO(3)-based heterostructures. We show that the exchange bias can be electrically controlled through a change in the relative proportion of 109° domain walls and propose solutions toward a reversible process.     

Exfoliated polymer nanocomposites by in situ coprecipitation of layered double hydroxides in a polymer matrix

Polyvinylalcohol (PVA) nanocomposites were prepared by a “one step” method based on the coprecipitation of layered double hydroxide (LDH) platelets in the polymer aqueous solution. The PVA/LDH nanocomposites displayed an exfoliated morphology and the concentration of LDH in the nanocomposite was evaluated by IR analysis. Moreover, it was shown that the PVA/LDH nanocomposites had an improved photostability over PVA, which makes this material a good candidate for coating applications. Further optimization will be considered to tune the polymer/LDH properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Addressing Fragment of Mitogaligin: First Insights into Functional and Structural Properties

Mitogaligin is a mitochondrion‐targeting protein involved in cell death. The sequence of the protein is unrelated to that of any known pro‐ or antiapoptotic protein. Mitochondrial targeting is controlled by an internal sequence from residues 31 to 53, and although this sequence is essential and sufficient to provoke cell death, the precise mechanism of action at the mitochondrial membrane remains to be elucidated. Here, by focusing on the [31–53] fragment, we first assessed and confirmed its cell cytotoxicity by microinjection. Subsequently, with the aid of membrane models, we evaluated the impact of the membrane environment on the 3D structure of the peptide and on how the peptide is embedded and oriented within membranes. The fragment is well organized, even though it does not contain a canonical secondary structure, and adopts an interfacial location. Structural comparison with other membrane‐interacting Trp‐rich peptides demonstrated similarities with the antimicrobial peptide tritrpcidin.     

Evolution of interleukin-15 for higher E. coli expression and solubility

Directed evolution was used to generate IL-15 mutants with increased solubility and cytoplasmic over-expression in Escherichia coli. A protein solubility selection method was used in which the IL-15 gene was expressed as an N-terminal fusion to chloramphenicol acetyltransferase (CAT) as reporter protein. Clones that grew in the presence of high concentrations of chloramphenicol were then screened by ELISA to assay the binding activity of the IL-15-CAT fusion to the IL-15Rα Sushi domain. Two variants of IL-15, M38 and M253, containing five mutations and one mutation respectively, were selected with a dramatic improvement in solubility; the soluble concentration in cell culture was 12- to 18-fold higher, respectively, than for WT IL-15. Characterization of their binding to IL-15Rα and their ability to stimulate the T-cell growth response showed that M38 binds as strongly as native IL-15 to IL-15Rα and acts as an effective agonist of IL-15.     

An Ontology-Based Approach to Personalized Situation-Aware Mobile Service Supply

Mobile devices such as personal digital assistants (PDAs) and mobile phones are in widespread use already today and converging to mobile smart phones. They enable users to access a wide range of services and information without guidance through their actual demands. Especially during mass events like the Olympic Games 2008 in Beijing—which was initially the context of our work—a large service space is expected to support all mobile visitors, being athletes, journalists, or spectators. Current approaches tackling such problems are location based, meaning that a user's location is central to service provision, and even context-aware, meaning that, beyond location, characteristics of a user's environment are taken into account. Such information obviously helps to deliver relevant information at the right time to the mobile users. Going one step further, a situation-aware system abstracts from the context dimensions by translating specific contexts into logical situations. Knowing the situation end users are in allows the system to better identify the information to be delivered to them and to choose the appropriate services with regard to their scope, which is referred to as service roaming. Even though many context frameworks have been introduced in the past few years, what is usually missing is the notion of characteristic features of contexts that are invariant during certain time intervals. This paper presents these concepts in the context of a platform development, namely FLAME2008, which is able to support its mobile users with personalized situation-aware services in push and pull mode.