Real Space Observations of Magnesium Hydride Formation and Decomposition

The mechanisms of magnesium hydride formation and thermal decomposition are directly examined using in-situ imaging.Comment: 3 pages, 4 figure

La diversité génétique des bananiers plantains cultivés dans la zone Ouest de la Région des Plateaux au Togo

Le bananier représente l’une des cultures les plus importantes dans le monde. Au Togo, la culture de bananiers plantains se fait surtout dans la Région des Plateaux à l’Ouest dans de petites exploitations agricoles ; ce qui a entrainé une faible productivité. Cependant, les variétés de bananiers plantains cultivées ne sont pas bien connues. Un inventaire a été entrepris dans le but de dénombrer les variétés de bananiers plantains cultivés grâce à des paramètres agromorphologiques et aussi de montrer l’intérêt que suscite la valorisation de la culture de cette plante. Au terme de cette étude, cinq (5) variétés de bananiers plantains ont été recensées. La variété ‘Apim’ est la plus productive suivie de la variété ‘Abladzo’. Contrairement aux autres, la variété ‘Taévé’ produit 2 régimes par pied au lieu d’un régime. Le cycle végétatif des bananiers plantains varie de 11 à 15 mois sauf pour la variété ‘Apim’ qui est de 18 mois. Des études de propagation rapide doivent être envisagées pour la sélection des variétés hautement performantes et la production massive du plantain pour les populations locales.© 2013 International Formulae Group. All rights reserved.Mots clés : Togo, bananier plantain, diversité génétique

OCCURRENCE AND CHARACTERISATION OF Xanthomonas axonopodis pv. glycines, CAUSING BACTERIAL PUSTULES ON SOYBEAN IN GUINEA SAVANNA OF BENIN

To improve soybean ( Glycine max L.) production in Benin, knowledge of bacterial diseases is needed. The objective of this study was to establish the disease occurrence and to identify Xanthomonas axonopodis pv.glycines, the causal agent of soybean bacterial pustule. Soybean bacterial pustule disease was studied during the flowering and at pod maturation, in thirty four sites of the main soybean cultivation areas in eight districts of the Guinea Savanna in Benin. Twenty and 10 soybean plants were randomly inspected for incidence and severity, respectively, on two diagonals through the field. Seven isolates from 6 different locations with highest severity, were submitted for virulence tests. The most virulent was characterised by Polymerase Chain Reaction. Bacterial pustules were present in 33 of 34 sites. Incidence and severity per district ranged from 15.8 to 70%, and 6.0 to 26.14%, respectively. Severity was highest at Binassi (34.33%) in Perere and Baka (33.2%) in Parakou. Among the seven strains isolated, UP-PK-S3 from Baka (Parakou) was the most virulent, and was characterised as Xanthomonas axonopodis pv. glycines.Une prospection a \ue9t\ue9 conduite sur la pustule bact\ue9rienne du soja durant la phase de floraison et de formation des gousses sur trente-quatre sites de production du soja localis\ue9s dans 8 Communes de la savane guin\ue9enne du B\ue9nin en 2011. L\u2019objectif \ue9tait d\u2019\ue9tablir la pr\ue9sence de la maladie et d\u2019identifier Xanthomonas axonopodis pv. glycines, l\u2019agent responsable de la pustule bact\ue9rienne du soja. Trois \ue0 six sites ont \ue9t\ue9 prospect\ue9s par commune et sur chaque site 20 et 10 plants sont respectivement inspect\ue9s au hasard sur deux diagonales du champ pour \ue9valuer l\u2019incidence et la s\ue9v\ue9rit\ue9. Sept isolats provenant de 6 diff\ue9rentes localit\ue9s \ue0 fortes valeurs de s\ue9v\ue9rit\ue9s ont \ue9t\ue9 soumis \ue0 un test de virulence et l\u2019isolat le plus virulent a \ue9t\ue9 caract\ue9ris\ue9 par PCR et s\ue9quenc\ue9. Les r\ue9sultats ont montr\ue9 que la pustule bact\ue9rienne \ue9tait pr\ue9sente sur 33 des 34 champs prospect\ue9s. L\u2019analyse statistique de la moyenne d\u2019incidence et de s\ue9v\ue9rit\ue9 par commune a r\ue9v\ue9l\ue9 une variabilit\ue9 de 15,8 \ue0 70% pour l\u2019incidence et de 6,0 \ue0 26,14% pour la s\ue9v\ue9rit\ue9. Parmi les sept souches isol\ue9es, la souche UP-PK-S3 provenant de Baka (Parakou) \ue9tait la plus virulente et a \ue9t\ue9 caract\ue9ris\ue9e comme Xanthomonas axonopodis pv. glycines et pourrait \ueatre utilis\ue9e pour le criblage pour la r\ue9sistance en milieu contr\uf4l\ue9

Pharmacogene sequencing of a Gabonese population with severe Plasmodium falciparum malaria reveals multiple novel variants with putative relevance for antimalarial treatment.

Malaria remains one of the most deadly diseases in Africa, particularly for children. While successful in reducing morbidity and mortality, antimalarial treatments are also a major cause of adverse drug reactions (ADRs). Host genetic variation in genes involved in drug disposition or toxicity constitutes an important determinant of ADR risk and can prime for parasite drug resistance. Importantly however, the genetic diversity in Africa is substantial and thus genetic profiles in one population cannot be reliably extrapolated to other ethnogeographic groups. Gabon is considered a high-transmission country with more than 460,000 malaria cases per year. Yet, the pharmacogenetic landscape of the Gabonese population or its neighboring countries has not been analyzed. Using targeted sequencing, we here profiled 21 pharmacogenes with importance for antimalarial treatment in 48 Gabonese pediatric patients with severe Plasmodium falciparum malaria. Overall, we identified 347 genetic variants of which 18 were novel and each individual was found to carry 87.3±9.2 SD variants across all analyzed genes. Importantly, 16.7% of these variants were population-specific, highlighting the need for high-resolution pharmacogenomic profiling. Between one in three and one in six individuals harbored reduced activity alleles of CYP2A6, CYP2B6, CYP2D6 and CYP2C8 with important implications for artemisinin, chloroquine and amodiaquine therapy. Furthermore, one in three patients harbored at least one G6PD deficient allele, suggesting considerably increased risk of hemolytic anemia upon exposure to aminoquinolines. Combined, our results reveal the unique genetic landscape of the Gabonese population and pinpoint the genetic basis for inter-individual differences in antimalarial drug response and toxicity

Surface and Particle-Size Effects on Hydrogen Desorption from Catalyst-Doped MgH2

With their high capacity, light-metal hydrides like MgH2 remain under scrutiny as reversible H-storage materials, especially to develop control of H-desorption properties by decreasing size (ball-milling) and/or adding catalysts. By employing density functional theory and simulated annealing, we study initial H2 desorption from semi-infinite stepped rutile (110) surface and Mg31H62 nanoclusters, with(out) transition-metal catalyst dopants (Ti or Fe). While Mg31H62structures are disordered (amorphous), the semi-infinite surfaces and nanoclusters have similar single, double, and triple H-to-metal bond configurations that yield similar H-desorption energies. Hence, there is no size effect on desorption energetics with reduction in sample size, but dopants do reduce the H-desorption energy. All desorption energies are endothermic, in contrast to a recent report

The effect of iron re-deposition on the corrosion of impurity-containing magnesium

This article provides a contribution towards the mechanistic understanding of surface phenomena observed during the corrosion of Mg-based substrates particularly in the low anodic polarization range. The concept considers the recent literature explaining cathodic hydrogen evolution from noble acting areas even during global anodic polarization. Heavy metal impurities in the ppm range or intermetallics are always present even in highly pure magnesium. Their potential effect was investigated here in more detail. The experimental results contribute to understanding the role of iron impurities in dark area formation and suggest a way for linking the observed phenomena to the recent literature. The shown enhanced cathodic activity of dark areas especially at the corrosion front and the superfluous hydrogen are linked to an iron re-deposition mechanism due to iron reduction. The proposed mechanism is based on the results obtained from innovative characterisation techniques using magnetic fields, diffraction experiments and transmission electron microscopy, which show the formation of iron rich zones, especially at the corrosion front offering "in statu nascendi" metallic Fe films acting as active cathodes for hydrogen reduction

Perception endogène de l’influence des changements climatiques sur la pêche dans la basse vallée de l’Ouémé (Sud Bénin)

Les perceptions endogènes des pêcheurs de l’influence des changements climatiques sur la pêche dans la basse vallée de l’Ouémé ont été étudiées. Ces perceptions ont été recueillies à l’aide d’un questionnaire administré à 266 pêcheurs d’au moins 20 ans d’expérience, exerçant la pêche dans Aguégués, Dangbo, Adjohoun et Bonou. Il s’agit des autochtones dont 43,98% de pêcheur-agriculteurs 35,71% d’agriculteurpêcheurs, 18,42% de pêcheurs reconvertis en exploitants de sable fluvial, 1,13% reconvertis en transport fluvial et 0,75% reconvertis en trafic d’essence. La modélisation des tendances évolutives (1971 et 2013) de la pluviométrie annuelle, de la température et de la lame d’eau écoulée a été réalisée avec le logiciel Minitab 1.4., en utilisant l’analyse des séries chronologiques. Une analyse factorielle des correspondances (AFC) a servi à décrire les déterminants des perceptions. Les pêcheurs ont signalé une augmentation de la température et une diminution de la pluviométrie. Ils ont fait cas des crues sévères, des inondations persistantes et de la baisse des rendements des captures. Leurs perceptions sont corroborées par l’analyse des données hydrométéorologiques et les statistiques de pêche. Une régression logistique binaire avec le model Proc logit du logiciel SAS 9.2 a montré que le sexe influence significativement (p<0,001) au seuil de 5% la perception des pêcheurs, de même que leur appartenance religieuse (p<0,1) au seuil de et 10%.Mots clés : Perceptions des pêcheurs, changements climatiques, basse vallée de l’Ouémé

Ni coated LiH nanoparticles for reversible hydrogen storage

Lithium is a material of choice for batteries, but it has also the potential to store energy with high density as a hydrogen storage material, i.e. via the formation of its hydride (LiH). However, the high thermodynamic stability of LiH has so far precluded the use of lithium as an effective hydrogen storage material owing the high temperature 700 °C for hydrogen release. Herein, we report on a novel method to enable the reversible storage of hydrogen with lithium under mild conditions of pressure (6 MPa) and temperature (350 °C). Through the catalytic hydrogenation of lithium, LiH particles were restricted to a few nanometres (<4 nm). Further coating with nickel chloride enabled the formation of a Ni shell at the surface of the LiH nanoparticles leading to their effective stabilization for hydrogen release and uptake with fast kinetics - full hydrogen release/uptake was achieved in less than 50 min at 350 °C. This demonstrates that the properties of LiH are particle size dependent and thus offers new avenues to achieve high energy storage lithium based devices. Copyright © 2016, Hydrogen Energy Publications, LLC

Nanoconfined lithium aluminium hydride (LiAlH4) and hydrogen reversibility

Lithium aluminium hydride (LiAlH4) is a promising hydrogen storage material with a storage capacity of 10.6 mass % H2. However, its practical use is hampered by the lack of direct rehydrogenation routes. In this study, we report on the confinement of LiAlH4into the nanoporosity of a high surface area graphite resulting in a remarkable improvement of its hydrogen storage properties. Nanoconfined LiAlH4started hydrogen desorption near 135 °C and after full dehydrogenation at 300 °C limited rehydrogenation was observed at the same temperature and 7 MPa of hydrogen pressure. Rehydrogenation took place through the formation of Li3AlH6with some limited rehydrogenation back to LiAlH4indicating the existence of different (de)hydrogenation paths upon nanoconfinement as compared to the known dehydrogenation path of bulk LiAlH4