Partially fluorinated proton exchange membranes based on PVDF\u2013SEBS blends compatibilized with methylmethacrylate block copolymers

This paper reports on a new route to prepare functional polymer blends for fuel cell\u2019s proton exchange membrane applications. Polyvinylidene fluoride (PVDF) and styrene-ethylene/butylene-styrene (SEBS) thermoplastic elastomer were melt blended and extruded into films. Interface modification using poly(methylmethacrylate-butylacrylate-methylmethacrylate) block copolymer (MAM), and two grades of poly(styrene-butadienemethylmethacrylate) block copolymer was used to optimize the blends performance. The films made out of these blends were grafted with sulfonic acid moieties to obtain ionic conductivity leading to semi-fluorinated proton exchange membranes. The effect of varying the nature and concentration of the compatibilizer on the morphology and properties of a 50/50 wt.% PVDF/SEBS blends was investigated. SEM analysis showed that the addition of the block copolymers to the blends affected the morphology significantly and in the best case, that as low as 1 wt.% block copolymer was sufficient to dramatically reduces the segregation scale and improves mechanical properties. The samples were characterized in terms of morphology, microstructure and thermo-mechanical properties and in terms of conductivity, ion exchange capacity (IEC) and water uptake to establish the blends morphology\u2013property relationships. Compatibilized blend membranes showed conductivities up to 3 710\u207b\ub2 S cm\u207b\ub9 at 100% relative humidity, and an IEC = 1.69 meq g\u207b\ub9. Water swelling decreased for compatibilized blend membranes.Peer reviewed: YesNRC publication: Ye

Analyse économique de la compétitivité de la filière tomate dans la région du Souss-Massa (Maroc)

The aim of this study is to evaluate the government’s intervention policies for greenhouse tomato production. The study is based on data collected from a sample of farmers in the Souss-Massa. The choice of the Souss-Massa region was made for several reasons, including the potential of tomato crop production, the share of the greenhouse tomato production in relation to domestic production and the existence of different segments and operators involved in the fresh tomato industry. For this study, we used the Policy Analysis Matrix (PAM) method. Analysis of data showed that tomato production in farms of Souss-Massa region is profitable. It has a comparative advantage and can generate foreign currency. This is due to the lower social costs of tradable inputs and to the fact that actors use many domestic resources in their production systems. Thus, with a Domestic Cost Resources ratio (DRC) below one, the activity is competitive and will be more competitive in case of a decline in social costs of domestic resources. Key words: Tomato, Souss-Massa, policy analysis matrix, reference price, comparative advantageL’objectif de cette étude est l’évaluation des politiques d’intervention de l’État pour la production de la tomate sous serre. L’étude a été basée sur les données collectées auprès d’un échantillon d’agriculteurs de la zone de Souss-Massa. Le choix de la région de Souss-Massa a été fait pour plusieurs raisons, notamment, le potentiel de production des cultures sous serre, l’importance de la part de la production de la tomate sous serre par rapport à la production nationale et l’existence des différents segments et opérateurs qui interviennent dans la filière tomate. Pour cette étude, nous avons utilisé la méthode de la matrice d’analyse des politiques (MAP). L’analyse des données a montré que la production de la filière tomate dans les exploitations de la région de Souss-Massa est rentable. Elle a un avantage comparatif aux prix de référence et peut générer de la devise étrangère. Ceci s’explique par la diminution des coûts sociaux des intrants échangeables et par le fait que les acteurs utilisent beaucoup de ressources domestiques dans leurs systèmes de production. Par conséquent, avec un CRD (Coefficient de coût en Ressources Domestiques) inférieur à l’unité, l’activité est compétitive et elle sera plus compétitive en cas de régression des coûts sociaux (économiques) des ressources domestiques. Mots clés: Tomate, Souss-Massa, matrice d’analyse des politiques, prix de référence, avantage comparati

Les antagonistes naturels d’Heterodera avenae dans diverses conditions de cultures de céréales en Algérie

A study was carried out to determine the diversity of the microflora associated with the cereal cyst nematode, Heterodera avenae, in four cereal production regions of Algeria. The isolation was mainly targeted toward fungi associated to cyst nematodes. The isolation resulted in the identification of six fungi: Fusarium sp., Penicillium spp., Verticillium spp., Rhizomucor spp., Rhizopus spp.and Ulocladium spp. In all the prospected regions, Fusarium sp. is most frequently associated with cysts. The highest diversity is observed at Dahmouni with the genera Aspergillus spp., Ulocladium spp., Rhizopus spp. and Rhizomucor spp. The in vitro test showed that the metabolites of Fusarium spp., Penicillium spp.and Aspergillus spp. parasitize the eggs at a high rate and thus constitute potential agents for the control of H. avenae. Keywords: Antagonists, fungi, bacteria, metabolites, cyst nematode, biological controlUn travail de recherche a été conduit pour mettre en évidence la diversité de la microflore associée au nématode à kyste des céréales, Heterodera avenae, dans quatre régions céréalières d’Algérie. L’isolement des micro-organismes associés a visé principalement les champignons inféodés aux kystes. L’isolement a abouti à l’identification de six champignons: Fusarium spp., Penicillium spp., Verticillium spp., Rhizomucor spp., Rhizopus spp. et Ulocladium spp. Dans toutes les régions prospectées, Fusarium sp. est le plus fréquemment associé aux kystes. La diversité la plus élevée est observée à Dahmouni avec les genres Aspergillus spp., Ulocladium spp., Rhizopus spp. et Rhizomucor spp. L’essai in vitro a montré que les métabolites de Fusarium spp., Penicillium spp.et Aspergillus spp. parasitent à un taux élevé les œufs et constituent ainsi des agents potentiels de lutte contre H. avenae. Mots-clés: Antagonistes, champignons, bactéries, métabolites, nématode à kyste, lutte biologiqu

Preparation and Characterization of Semi-fluorinated Composite PEM with Phosphotungstic Acid Immobilized on Clays Using Melt Processing Technologies

Peer reviewed: YesNRC publication: Ye

Monitoring of host suitability and defense-related genes in wheat to Bipolaris sorokiniana

Spot blotch caused by Bipolaris sorokiniana is a destructive disease of wheat worldwide. This study investigated the aggressiveness of B. sorokiniana isolates from different wheat-growing areas of Bolu province in Turkey on the cultivar Seri-82. Host susceptibility of 55 wheat cultivars was evaluated against the most aggressive isolate. Our results indicated that the cultivars Anafarta and Koç-2015 were the most resistant. A specific and sensitive qPCR assay was developed for detecting the pathogen in plant tissues and evaluating wheat plants with different resistance levels. Three primer sets, BsGAPDHF/BsGAPDHR, BsITSF/BsITSR, and BsSSUF/BsSSUR, were designed based on glyceraldehyde-3-phosphate dehydrogenase, internal transcribed spacers, and 18S rRNA loci of B. sorokiniana with detection limits of 1, 0.1, and 0.1 pg of pathogen DNA, respectively. The qPCR assay was highly sensitive and did not amplify DNA from the other closely related fungal species and host plants. The protocol differentiated wheat plants with varying degrees of resistance. The assay developed a useful tool for the quantification of the pathogen in the early stages of infection and may provide a significant contribution to a more efficient selection of wheat genotypes in breeding studies. In the present study, expression levels of PR proteins, phenylalanine ammonia-lyase, catalase, ascorbate peroxidase, and superoxide dismutase enzymes were upregulated in Anafarta (resistant) and Nenehatun (susceptible) cultivars at different post-infection time points, but more induced in the susceptible cultivar. The results showed considerable variation in the expression levels and timing of defense genes in both cultivars

Sulfonated Styrene-(ethylene-co-butylene)-styrene/Montmorillonite Clay Nanocomposites: Synthesis, Morphology, and Properties

Sulfonated styrene-(ethylene-butylene)-styrene triblock copolymer (SSEBS) was synthesized by reaction of acetyl sulfate with SEBS. SSESB-clay nanocomposites were then prepared from hydrophilic Na-montmorillonite (MT) and organically (quaternary amine) modified hydrophobic nanoclay (OMT) at very low loading. SEBS did not show improvement in properties with MT-based nanocomposites. On sulfonation (3 and 6 weight%) of SEBS, hydrophilic MT clay-based nanocomposites exhibited better mechanical, dynamic mechanical, and thermal properties, and also controlled water–methanol mixture uptake and permeation and AC resistance. Microstructure determined by X-ray diffraction, atomic force microscopy, and transmission electron microscopy due to better dispersion of MT nanoclay particles and interaction of MT with SSEBS matrix was responsible for this effect. The resulting nanocomposites have potential as proton transfer membranes for Fuel Cell applications