24 research outputs found
Essai de germination et de croissance de Artemisia annua L. au Niger
Lâessai a Ă©tĂ© conduit Ă la pĂ©piniĂšre de lâINRAN de Niamey et Ă la cuvette de lâINRAN de Kollo, et a portĂ© sur la germination, croissance, dĂ©veloppement de Artemisia annua (lâhybride F2 et M), plante qui a des vertus anti-paludique. Cette Ă©tude a pour objectif dâĂ©valuer les meilleures conditions de culture de artemisia annua et le meilleur substrat pour son adaptation. Le Niger, pays dâendĂ©mie du paludisme, maladie qui constitue la premiĂšre cause de morbiditĂ© et de mortalitĂ©. Face Ă cette menace, les autoritĂ©s ont optĂ© pour lâutilisation des dĂ©rivĂ©s dâartĂ©misinine comme molĂ©cule de choix dans la prise en charge du paludisme comme lâa recommandĂ© lâOMS. Les tests de la levĂ©e en pĂ©piniĂšre ont Ă©tĂ© effectuĂ©s dans un bac Ă semis et un germoir en planche. Les plants ont Ă©tĂ© repiquĂ©s aprĂšs levĂ©e dans des pots avec trois types de substrats (substrat dunaire,substrat de bas fond et substrat de sable du fleuve) afin de dĂ©terminer le meilleur substrat pour la culture de la plante en pĂ©piniĂšre. Il ressort des rĂ©sultats obtenus que le substrat de bas fond offre les meilleurs valeurs pour la hauteur, le diamĂštre au collet et le nombre de feuilles que les substrats dunaire et du fleuve. Les plants ont Ă©tĂ© transfĂ©rĂ©s sur le site de Kollo et transplantĂ©s sur terre ferme. Pour la biomasse câest la variĂ©tĂ© F2 qui a enregistrĂ©e les meilleurs rendements mĂȘme si au niveau de la hauteur, elle enregistre les valeurs les plus basses comparativement Ă la variĂ©tĂ© M. Cette Ă©tude a montrĂ©e que Artemisia annua peut sâadapter au Niger et son introduction offre Ă la population un moyen supplĂ©mentaire de lutte contre le paludisme.Mots clĂ©s : Artemisia annua, artemisinine, paludisme, Niger
Iron oxide minerals in dust-source sediments from the Bodélé Depression, Chad: Implications for radiative properties and Fe bioavailability of dust plumes from the Sahara
Atmospheric mineral dust can influence climate and biogeochemical cycles. An important component of mineral dust is ferric oxide minerals (hematite and goethite) which have been shown to influence strongly the optical properties of dust plumes and thus affect the radiative forcing of global dust. Here we report on the iron mineralogy of dust-source samples from the BodĂ©lĂ© Depression (Chad, north-central Africa), which is estimated to be Earthâs most prolific dust producer and may be a key contributor to the global radiative budget of the atmosphere as well as to long-range nutrient transport to the Amazon Basin. By using a combination of magnetic property measurements, Mössbauer spectroscopy, reflectance spectroscopy, chemical analysis, and scanning electron microscopy, we document the abundance and relative amounts of goethite, hematite, and magnetite in dust-source samples from the BodĂ©lĂ© Depression. The partition between hematite and goethite is important to know to improve models for the radiative effects of ferric oxide minerals in mineral dust aerosols. The combination of methods shows (1) the dominance of goethite over hematite in the source sediments, (2) the abundance and occurrences of their nanosize components, and (3) the ubiquity of magnetite, albeit in small amounts. Dominant goethite and subordinate hematite together compose about 2% of yellow-reddish dust-source sediments from the BodĂ©lĂ© Depression and contribute strongly to diminution of reflectance in bulk samples. These observations imply that dust plumes from the BodĂ©lĂ© Depression that are derived from goethite-dominated sediments strongly absorb solar radiation. The presence of ubiquitous magnetite (0.002-0.57 wt. %) is also noteworthy for its potentially higher solubility relative to ferric oxide and for its small sizes, including PM<0.1m. For all examined samples, the average iron apportionment is estimated at about 33% in ferric oxide minerals, 1.4 % in magnetite, and 65% in ferric silicates. Structural iron in clay minerals may account for much of the iron in the ferric silicates. We estimate that the mean ferric oxides flux exported from the BodĂ©lĂ© Depression is 0.9 Tg/yr with greater than 50% exported as ferric oxide nanoparticles (<0.1m). The high surface-to-volume ratios of ferric oxide nanoparticles once entrained into dust plumes may facilitate increased atmospheric chemical and physical processing and affect iron solubility and bioavailability to marine and terrestrial ecosystems
Impact of long-term treatment of onchocerciasis with ivermectin in Kaduna State, Nigeria: first evidence of the potential for elimination in the operational area of the African Programme for Onchocerciasis Control.
BACKGROUND: Onchocerciasis can be effectively controlled as a public health problem by annual mass drug administration of ivermectin, but it was not known if ivermectin treatment in the long term would be able to achieve elimination of onchocerciasis infection and interruption of transmission in endemic areas in Africa. A recent study in Mali and Senegal has provided the first evidence of elimination after 15-17 years of treatment. Following this finding, the African Programme for Onchocerciasis Control (APOC) has started a systematic evaluation of the long-term impact of ivermectin treatment projects and the feasibility of elimination in APOC supported countries. This paper reports the first results for two onchocerciasis foci in Kaduna, Nigeria. METHODS: In 2008, an epidemiological evaluation using skin snip parasitological diagnostic method was carried out in two onchocerciasis foci, in Birnin Gwari Local Government Area (LGA), and in the Kauru and Lere LGAs of Kaduna State, Nigeria. The survey was undertaken in 26 villages and examined 3,703 people above the age of one year. The result was compared with the baseline survey undertaken in 1987. RESULTS: The communities had received 15 to 17 years of ivermectin treatment with more than 75% reported coverage. For each surveyed community, comparable baseline data were available. Before treatment, the community prevalence of O. volvulus microfilaria in the skin ranged from 23.1% to 84.9%, with a median prevalence of 52.0%. After 15 to 17 years of treatment, the prevalence had fallen to 0% in all communities and all 3,703 examined individuals were skin snip negative. CONCLUSIONS: The results of the surveys confirm the finding in Senegal and Mali that ivermectin treatment alone can eliminate onchocerciasis infection and probably disease transmission in endemic foci in Africa. It is the first of such evidence for the APOC operational area
GEOMETRICAL INVESTIGATION FOR THE ELECTRICAL CHARACTERIZATION OF T700/M21 CFRP COMPOSITE DURING CURING
International audienceno abstrac
CURE MONITORING OF CFRP: ELECTRICAL IMPEDANCE ANALYSIS
International audienceno abstrac
CURE MONITORING OF CFRP: ELECTRICAL IMPEDANCE ANALYSIS
International audienceno abstrac
GEOMETRICAL INVESTIGATION FOR THE ELECTRICAL CHARACTERIZATION OF T700/M21 CFRP COMPOSITE DURING CURING
International audienceno abstrac