Nafion-clay nanocomposite membranes: Morphology and properties

A series of Nafion-clay nanocomposite membranes were synthesized and characterized. To minimize any adverse effects on ionic conductivity the clay nanoparticles were H⁺ exchanged prior to mixing with Nafion. Well-dispersed, mechanically robust, free-standing nanocomposite membranes were prepared by casting from a water suspension at 180 °C under pressure. SAXS profiles reveal a preferential orientation of Nafion aggregates parallel to the membrane surface, or normal plane. This preferred orientation is induced by the platy nature of the clay nanoparticles, which tend to align parallel to the surface of the membrane. The nanocomposite membranes show dramatically reduced methanol permeability, while maintaining high levels of proton conductivity. The hybrid films are much stiffer and can withstand much higher temperatures compared to pure Nafion. The superior thermomechanical, electrochemical and barrier properties of the nanocomposite membranes are of significant interest for direct methanol fuel cell applications.     

Industrial clarification of anthocyanin‐rich grape pomace extracts by crossflow membrane filtration

A comparative study on the clarification of anthocyanin‐rich grape pomace extracts was carried out by tubular, hollow fibre and spiral wound industrial crossflow membrane units. Three polysulfone membranes were tested: a 500‐kDa molecular mass cut‐off (MMCO), and a 0.2‐ and 0.6‐μm pore size cut‐offs (PSCO). The 500‐ kDa MMCO and the 0.2‐μm PSCO membranes produced particle‐free extracts, while the 0.6‐μm membrane showed deficient clarification. The 500‐kDa MMCO membrane produced up to 3.7% loss of most of the individual anthocyanins, while the 0.6‐ and 0.2‐μm PSCO membranes produced up to 2% only of some of the anthocyanins with higher molecular masses. Permeate steady fluxes of up to 53 L h^?1 m^?2 were obtained. Particles with sizes of 0.5–1.5 μm and the macromolecular anthocyanin–tannin complexes had a major impact on membrane performance. The obtained results are scalable to industrial installations.     

Policies to improve the local impact from hydrocarbon extraction: Observations on West Africa and possible lessons for Central Asia

The paper offers specific inputs to the debate on local content promotion in the oil industries of West Africa and Central Asia. To this end, we document the international experience with local content promotion to derive best practices in the field. We then use a case study approach to devise a simple analytical framework for rationalizing the selection of viable sectors for local content promotion, in an attempt to make operational one of the best practice principles (efficiency) developed before. By proposing specific rules regarding the acceptability of a project, the analysis seeks to add rigor and address distortions on localization outcomes from rent-seeking. The emphasis is not on supporting efforts to “pick winners” and subsidize them through a range of by and large discredited instruments. Rather, the paper focuses on the specific public inputs the government would have to provide to support an otherwise market-driven process.     

Analytical study of the thermal behaviour and stability of a small satellite

In this work the thermal analysis of a small satellite orbiting around the Earth has been approached by direct integration of the heat balance equations of a two-node reduced model, obtaining a linearized second order ODE problem, similar in form to the classical case of the forced vibration of a damped system. As the thermal loads (solar radiation, albedo, etc.) are harmonic, the problem is solved by means of Fourier analysis methods. Research on that field can be directly applied to the analysis of thermal problems and the results obtained are satisfactory. Working on the frequency domain streamlines the analysis, simplifies the study and facilitates the experimental testing. The transfer functions are obtained for the two-node case but the study can be extended to an n-node model.     

Making a better interconnection through modeling

Introduces a simple technique for implementing nonuniform coupled transmission lines with frequency-dependent parameters into SPICE. The proposed method relies on the analog behavioral modeling option, which bypasses the problems of circuit synthesis and the need to develop sophisticated techniques for analysis of these kind of structures. We describe basic principles that serve to construct the model, derive a generalized model of characteristics typical of an n-conductor nonuniform lossy coupled transmission line system, establish the relationship between the S-parameters and the voltage-dependent voltage sources of the model, and deal with the implementation of the developed model to each port. Examples that illustrate the advantages of the model and concordance with previously published results are also presented     

Multi-Layered Films Containing a Biomimetic Stimuli-Responsive Recombinant Protein

Electrostatic self-assembly was used to fabricate new smart multi-layer coatings, using a recombinant elastin-like polymer (ELP) and chitosan as the counterion macromolecule. The ELP was bioproduced, purified and its purity and expected molecular weight were assessed. Aggregate size measurements, obtained by light scattering of dissolved ELP, were performed as a function of temperature and pH to assess the smart properties of the polymer. The build-up of multi-layered films containing ELP and chitosan, using a layer-by-layer methodology, was followed by quartz-crystal microbalance with dissipation monitoring. Atomic force microscopy analysis permitted to demonstrate that the topography of the multi-layered films could respond to temperature. This work opens new possibilities for the use of ELPs in the fabrication of biodegradable smart coatings and films, offering new platforms in biotechnology and in the biomedical area.     

Agaricus macrosporus as a potential bioremediation agent for substrates contaminated with heavy metals

This study investigated the potential use of the mushroom Agaricus macrosporus for bioextraction of heavy metals from contaminated substrates. Mushrooms were grown (1) in a non‐contaminated control substrate, (2) in a substrate with added Cd (10 mg per kg dw), and (3) in a multi‐contaminated substrate (Cd, Hg and Pb each at 10 mg kg^?1; Cu and Zn each at 20 mg kg^?1). Metal contents were determined in fruiting bodies by anodic stripping voltammetry (ASV). In the control substrate, three production waves (‘breaks’) were obtained, compared with only two in the contaminated substrates; however, total biomass in the Cd‐contaminated substrate was similar to that in the control substrate, and only 40% lower (ie still considerable) in the Hg‐containing multi‐contaminated substrate. Within each break, metal contents were higher in young than in adult individuals. Metal contents were also higher in the hymenophore than in other parts of the fruiting body. The metal content data indicate that A macrosporus effectively extracted Cd, Hg and Cu (though not Pb) from the contaminated substrates. Of particular interest is the tolerance and extraction of Hg, in contrast with plants. These results suggest that fungi such as A macrosporus may be effective for bioremediation of metal‐contaminated substrates, though bearing in mind that in many contaminated environments cultivation of mushrooms of this type may be difficult. Copyright © 2005 Society of Chemical Industry     

Mercury in edible mushrooms and underlying soil: Bioconcentration factors and toxicological risk

Wild growing mushrooms are a popular delicacy in many countries, but some species accumulate high levels of toxic heavy metals, e.g., mercury, both in unpolluted and mildly polluted areas. In this study, we examined the accumulation capacity of mercury in edible mushrooms in relation to certain factors and their possible toxicological implications. Total concentrations of mercury were determined by an anodic stripping voltammetric technique using a gold disc as the working electrode in 238 samples of the fruiting bodies of 28 wild growing edible mushrooms species and the underlying soil. The mushrooms were collected from different sites in the province of Lugo (NW Spain). The hymenophore (H) and the rest of the fruiting body (RFB) were analysed separately. The highest mean mercury concentrations (mg/kg dry weight) were found in Boletus pinophilus (6.9 in H and 4.5 in RFB), Agaricus macrosporus (5.1 in H and 3.7 in RFB), Lepista nuda (5.1 in H and 3.1 in RFB) and Boletus aereus (4.6 in H and 3.3 in RFB), while the lowest was found in Agrocybe cylindrica (0.34 in H and 0.26 in RFB) and Fistulina hepatica (0.30 in H and 0.22 in RFB). All mushroom species accumulated mercury (BCF > 1) in relation to the underlying soils. There were no statistically significant differences between the mercury levels in the hymenophore and in the rest of the fruiting body. The total mercury concentrations were compared to data in the literature and to levels set by legislation. It was concluded that consumption of the majority of the studied mushrooms is not a toxicological risk as far as mercury content is concerned, although the species B. pinophilus, A. macrosporus, L. nuda and B. aereus should be consumed in low amounts.     

Recent developments in data mining and soft computing for JET with a view on ITER

In order to handle the vast amount of information collected by JET diagnostics, which can exceed 10 Gbytes of data per shot, a series of new soft computing methods are being developed. They cover various aspects of the data analysis process, ranging from information retrieval to statistical confidence and machine learning. In this paper some recent developments are described. History effects in the plasma evolution leading to disruptions have been investigated with the use of Artificial Neural Networks. New image processing algorithms, based on optical flow techniques, are being used to derive quantitative information about the movement of objects like filaments at the edge of JET plasmas. Adaptive filters, mainly of the Kalman type, have been successfully implemented for the online filtering of MSE data for real time purposes.     

Cyclohexene hydrogenation with molybdenum disulfide catalysts prepared by ex situ decomposition of ammonium thiomolybdate-cetyltrimethylammonium thiomolybdate mixtures

Ammonium tetrathiomolybdate (ATTM) is treated with cetyltrimethylammonium chloride (CTAC) using several ATTM/CTAC ratios. Reaction of ATTM with the limiting reagent CTAC gives the carbon-containing compound cetyltrimethylammonium tetrathio-molybdate (CTAT), resulting in different ATTM–CTAT mixtures or precursors which are then decomposed in N₂ at 723 K, yielding mesoporous samples with surface areas of over 260 m²/g. Analysis by XRD and electron microscopy correspond to a well dispersed MoS₂–2H phase. The activity of the catalysts is tested in a batch reactor for cyclohexene hydrogenation, where those prepared from ATTM–CTAT precursors are up to seven times more active than the catalyst obtained by thermal decomposition of pure ATTM. The enhanced catalytic activity of these catalysts is attributed to a sulfide phase containing structural carbon.