Synthesis of Perfectly Oriented MAPb0.93Cr0.07Br3 Perovskite Crystals for Thin-Film Photovoltaic Applications

[EN] Wide band gap methylammonium lead halide perovskites (CH3NH3PbX3, X=halogen; CH3NH3: MA) are interesting materials for photovoltaic applications. They have recently gained substantial attention because of their high efficiency, low cost, superior optical properties. The most attractive and representative perovskites are methylammonium lead halides (CH3NH3PbX3,) denoted as MAPbX3, X = Br, Cl, I. usually the optical and structural properties of CH3NH3PbBr3 can be adjusted by introducing other extrinsic ions such as chloride and bromide. In this work, instead of replacing the halogens I or Cl with bromine (Br) as usual, we preferred to act on the post-transition metal (Pb). To this end, we replaced lead with chromium (Cr) which is a transition metal and may have the same oxidation state (+2) as lead. MAPb0.93Cr0.07Br3 thin films were deposited on ITO substrate by the spin coating process. X-ray diffraction analyses indicated the formation of a cubic perovskite with space group Pm3 m. The structural analysis reveals films with (110) and (220) as main peaks. Deposited films showed a strong absorbance in the UV¿vis range. The band gap values were estimated from absorbance measurements. It was found between 1.60 and 1.80 eV. SEM analysis shows a morphology with good coverage and no apparent crystal orientation.Soro, D.; Sidibé, M.; Fassinou, W.; Marí, B.; Sall, T.; Fofana, B.; Boko, A.... (2017). Synthesis of Perfectly Oriented MAPb0.93Cr0.07Br3 Perovskite Crystals for Thin-Film Photovoltaic Applications. International Journal of Innovative Research in Science, Engineering and Technology. IJIRSET (Online). 6(6):10170-10176. doi:10.15680/IJIRSET.2017.0606007S10170101766

Etude de l’activité antifalcémiante d’extraits de racines de Leptadenia hastata Decne. (Asclepiadacae)

L’objectif de cette étude est d’évaluer l’activité antifalcémiante d’extraits de racines de Leptadenia hastata sur des hémoglobines falciformes et d’identifier les principes actifs à l’origine de cette activité. La méthode employée étudie la réversibilité des drépanocytes, en fonction du temps d’incubation des extraits par rapport aux témoins (eau physiologique, phénylalanine et arginine) sur des échantillons de sang de patients drépanocytaires homozygotes. Des concentrations de 0,05; 0,5; 5 et 10 mg/ml de quatre extraits (méthanol, hexane, acétate d’éthyle et méthanol résiduel) ont été mises en contact avec des drépanocytes de type SS après avoir provoqué leur falciformation avec une solution à 2% de métabisulfite de sodium. L’évaluation a été effectuée toutes les 30 minutes pendant 120 minutes. Les différents extraits ont montré une activité dosedépendante sur la réversibilité de la falciformation des globules rouges avec plus de 80% d’inversion en 120 minutes pour l’extrait méthanolique, le plus actif. Un screening phytochimique a permis de faire une corrélation entre les flavonoïdes et l’activité antifalcémiante des extraits de Leptadenia hastata.Mots clés : Drépanocytose, hémoglobine, activité antifalcémiante, Leptadenia hastata, flavonoïdes

Village Baseline Study: Site Analysis Report for Kaffrine – Kaffrine, Senegal

The village baseline study of Toune Mosquée village in the CCAFS benchmark site Kaffrine in Senegal took place from June 2 to 4, 2011. Natural resources in the village are in a progressive state of degradation. The ‘protected’ forest has almost disappeared, the soils have low fertility and are degraded, and crop production is not sufficient to meet the food needs of a family throughout the year. Families must buy food to fill the gap in production. For that they harvest and sell forest products, which creates a vicious cycle of resource degradation. The male and female groups identified 35 organisations operating in the village including informal groups, state services, associations, NGOs and Muslim brotherhoods. While 18 of those work on food security issues, only 4 are involved in the management and protection of natural resources. Very few agricultural extension and training opportunities target women despite the women’s significant role in agriculture and livestock production. Women obtain information on livestock feeding techniques from people and organisations such as the horticultural project, women’s associations, and water and forest services. Men get information on soil inputs and soil fertility management from other farmers, organisations, radio and television, and from community leaders, notably the office of the village chief and the mosque on Fridays. The radio is the form of media most commonly used by the women but few women own a radio

Effects of Ebola epidemic on obstetrical emergencies and outcomes in the region of Kindia, Guinea

Background: Maternal mortality is still high in Guinea despite a decline from 724 to 550 maternal deaths per 100,000 live births between 2012 and 2018. The proportion of births attended by skilled personnel is estimated at 45%. The objective of this study was to assess the effect of Ebola virus disease (EVD) epidemic on the frequency of absolute maternal indications, as well as the outcomes of these interventions for mother and child in the region of Kindia.Methods: This was a longitudinal study using 20 months of retrospective data collected in the pre-Ebola (March to December 2012 and March to December 2013) and intra-Ebola (March to December 2014 and March to December 2015) periods. The proportions of maternal health indicators in both study periods were compared using a significance level of 0.05.Results: A total of 1747 women were included in this study. The proportion of women who received a major obstetric procedure in Kindia regional hospital was 85% in each pre and post Ebola periods. Ebola, however, contributed to a significant increase in maternal deaths.Conclusions: The Ebola epidemic has contributed to a significant increase in maternal deaths in health facilities. Measures encouraging health workers to manage obstetric emergencies during critical periods would be necessary

Full genome sequence and sfRNA interferon antagonist activity of Zika virus from Recife, Brazil

Background: The outbreak of Zika virus (ZIKV) in the Americas has transformed a previously obscure mosquito-transmitted arbovirus of the Flaviviridae family into a major public health concern. Little is currently known about the evolution and biology of ZIKV and the factors that contribute to the associated pathogenesis. Determining genomic sequences of clinical viral isolates and characterization of elements within these are an important prerequisite to advance our understanding of viral replicative processes and virus-host interactions. Methodology/Principal findings: We obtained a ZIKV isolate from a patient who presented with classical ZIKV-associated symptoms, and used high throughput sequencing and other molecular biology approaches to determine its full genome sequence, including non-coding regions. Genome regions were characterized and compared to the sequences of other isolates where available. Furthermore, we identified a subgenomic flavivirus RNA (sfRNA) in ZIKV-infected cells that has antagonist activity against RIG-I induced type I interferon induction, with a lesser effect on MDA-5 mediated action. Conclusions/Significance: The full-length genome sequence including non-coding regions of a South American ZIKV isolate from a patient with classical symptoms will support efforts to develop genetic tools for this virus. Detection of sfRNA that counteracts interferon responses is likely to be important for further understanding of pathogenesis and virus-host interactions

Tailoring interfacial effect in multilayers with Dzyaloshinskii-Moriya interaction by helium ion irradiation

We show a method to control magnetic interfacial effects in multilayers with Dzyaloshinskii–Moriya interaction (DMI) using helium (He+) ion irradiation. We report results from SQUID magnetometry, ferromagnetic resonance as well as Brillouin light scattering results on multilayers with DMI as a function of irradiation fluence to study the effect of irradiation on the magnetic properties of the multilayers. Our results show clear evidence of the He+irradiation effects on the magnetic properties which is consistent with interface modification due to the effects of the He+ irradiation. This external degree of freedom offers promising perspectives to further improve the control of magnetic skyrmions in multilayers, that could push them towards integration in future technologies

Aggravation de l’anémie et polymorphisme de l’haptoglobine au cours de la drépanocytose au Sénégal

La drépanocytose homozygote s’accompagne d’une augmentation de l’hémoglobine (Hb) plasmatique, susceptible d’exposer les hématies à un stress oxydant. L’haptoglobine présente trois phénotypes majeurs (Hp1-1, Hp 2-1 et Hp 2-2) susceptibles de fixer l’hémoglobine extracellulaire avec une efficacité différente. L’objectif de ce travail est de voir si la connaissance du phénotype d’Hp pouvait constituer un élément prédictifde l’anémie sévère. Pour cela, il a été recruté 68 drépanocytaires  homozygotes, âgés de 5 à 31 ans. Pour chaque patient, un témoin de même sexe et de même âge ± 2 ans a été recruté. Le phénotypage de l’Hp a été réalisé par électrophorèse sur gel de polyacrylamide. Les résultats du dosage de l’Hb font ressortir que les taux d’Hb sont significativement différentes chez les patients comparées à celles des témoins (p = 0,001). Lorsque la répartition a été faite en fonction du phénotype d’Hp, une différence statistiquement significative a étéretrouvée entre le phénotype Hp1-1 et le phénotype Hp2-2 (p < 0,001) chez les patients et non chez les témoins. Les résultats de cette étude préliminaire suggéreraient que la connaissance du phénotype d’Hp seraitun facteur prédictif de l’anémie sévère au cours de la drépanocytose.Mots clés : Drépanocytose, anémie, phénotypes d’haptoglobine

Coastal Observations of Weather Features in Senegal during the AMMA SOP-3 Period

During 15 August through 30 September 2006, ground and aircraft measurements were obtained from a multi-national group of students and scientists in Senegal. Key measurements were aimed at investigating and understanding precipitation processes, thermodynamic and dynamic environmental conditions, cloud, aerosol and microphysical processes and spaceborne sensors (TRMM, CloudSat/Calipso) validation. Ground and aircraft instruments include: ground based polarimetric radar, disdrometer measurements, a course and a high-density rain gauge network, surface chemical measurements, a 10 m flux tower, broadband IR, solar and microwave measurements, rawinsonde and radiosonde measurements, FA-20 dropsonde, in situ microphysics and cloud radar measurements. Highlights during SOP3 include ground and aircraft measurements of squall lines, African Easterly Waves (AEWs), Saharan Air Layer advances into Senegal, and aircraft measurements of AEWs -- including the perturbation that became Hurricane Isaac