Efficience de trois méthodes géophysiques d'investigation latérale dans la mise en évidence de contacts entre des formations géologiques du Protérozoïque inférieur du Burkina Faso Evaluation of the efficiency of three geophysical methods for the determination of natural contacts between Lower Proterozoic geological formations of Burkina Faso

International audienceDans les zones de socle cristallin du Protérozoïque inférieur (Birimien) du Burkina Faso, les réserves d'eau souter-raine sont liées aux zones de faiblesse (failles, filons, contacts géologiques). Trois méthodes géophysiques (résistivité électrique, bipôle électromagnétique MaxMin et V.L.F./EM16) ont été conjointement utilisées pour évaluer leur efficience dans l'identification et la localisation précise du contact entre les granitoïdes et les schistes volcano-sédimentaires du bassin versant de Bidi d'une part et d'autre part, entre schistes et amphibolites à Kièbelga, dans la province du Yatenga. Dans les cas étudiés, le bipôle électromagnétique MaxMin en bobines horizontales (fréquence de 3250 hertz avec une séparation des bobines de 100 m) s'est révélé être le plus efficace. In the Lower Proterozoic (Birimian) crystalline basement of Burkina Faso, underground water resources are found associated with zones of weakness (faults, sills, geological contacts). Three geophysical methods (electrical resistivity, electromagnetism bipole MaxMin and V.L.F./EM16) have been used in order to prove their efficiency to precisely locate the geological contacts between: 1) granitoids and volcanosedimentary schists of the Bidi catchment basin and, 2) schists and amphibolites at Kièbelga, in the Yatenga province. We show that the MaxMin electromagnetic bipole technique with a 3520 hertz frequency and 100 m coils separation is the most efficient method in both cases

Hygienic status assessment of dish washing waters, utensils, hands and pieces of money from street food processing sites in Ouagadougou (Burkina Faso)

During investigations on street food vendors’ materials, seventy samples of three types of dish washing water (E1, E2, E3), eighty-five pieces of money, eighty utensils were collected for microbiological assessment. Hands microbiological status of one hundred twenty-five consumers andseventy sellers were also assessed. The analysis revealed that 100% of E1 washing waters were very impure, while, 44.5% of second washing water (E2) were impure, 44.5% very impure and 11% acceptable. 45.45% of E3 washing water were acceptable, 27.27% impure and 27.27% very impure. The spoons and the dinner plates were sometimes contaminated with unacceptable levels (above 102) of different bacteria such as, coliforms and Staphylococcus aureus (P 0.05). Knives microbiological examination revealed presence of numerous bacteria (8.6 x 105 cfu/knife) such as coliforms, S. Aureus, Salmonella and Shigella. Pieces of money analysis revealed presence of coliforms and S. aureus. These data showing pathogen bacteria in food vending sites indicates hygiene monitoring failure

Composition and antimicrobial activities of the leaf and flower essential oils of Lippia chevalieri and Ocimum canum from Burkina Faso

The essential oils of the air dried leaves and flowers of Lippia chevalieri Moldenke and Ocimum canum Sims from Burkina Faso were analysed by GC-MS. Essential oil of the leaves of L. chevalieri is composed mainly of thymol (27.4%), p-cymene (21.1%), and 2-phenyl-ethyl-propionate (12.6%), whilethe oils from flower is composed of b-elemene (33%), ethyl cinnamate (30.3%) and a-amorphene (12.4%). O. canum leaves and flowers oils consisted mainly in 1,8-cineole (60.1%) and cis, transpiperitol (68.5%), respectively. The antimicrobial activities of the essential oils were evaluated against 9 bacteria by agar diffusion method. The leaves of both plants showed higher activity than their flowers. The leaves of L. chevalieri were active against Gram negative and Gram positive bacteria whereas only Gram positive bacteria were sensitive to the essential oil of the O. canum leaves. Flower essential oilsdid not show any significant activity

Profil de résistance des agents étiologiques des diarrhées isolés au Tchad

La résistance aux antibiotiques des entéropathogènes impliqués dans les maladies diarrhéiques est une préoccupation d’ampleur mondiale. C’est pourquoi la présente étude était entreprise en vue de tester la sensibilité de ces microorganismes aux antibiotiques couramment utilisés au Tchad. Les selles des patients ont été prélevées dans des flacons stériles et analysées selon les procédures standards de microbiologie dans le laboratoire de Bactériologie de l’Hôpital Général de Référence Nationale de N’Djamena (HGRN). L’isolement et l’identification des entéropathogènes dans les selles étaient réalisés, en utilisant les milieux Hektoen, EMB (éosine bleu de méthylène), TCBS (thiosulfate, citrate, bile, saccharose) (BioRad) et la galerie API® 20E et API® 20 NE (BioMérieux). L’antibiogramme a été effectué selon la méthode de Kirby Bauer en utilisant le milieu Mueller-Hinton. Le test antigénique était réalisé conformément aux instructions de Kaufmann-White. Au total, les selles de 1164 patients ont été analysées, desquelles 275 entéropathogènes étaient isolés, identifiés et testés aux antibiotiques. Parmi les souches d’entérobactéries étudiées, les Escherichia coli étaient résistants de 70% aux Bêta-lactamines. Les Vibrio cholerae O 1 en particulier ont exprimé un taux de résistance de 15,30% à l’ampicilline, 100% à l’amoxicilline + acide clavulanique et triméthoprime/cotrimoxazole, 98,90% à l’acide nalidixique et 12,56% à la ceftriaxone. Ces résultats attestent de la circulation des entéropathogènes résistants aux antibiotiques usuels au Tchad.Mots clés : Diarrhée, entéropathogène, antibiotique, résistance, HGRN, Tchad

Prevalence of Escherichia coli virulence genes in patients with diarrhoea in Ouagadougou, Burkina Faso

Objective: Diarrhoeagenic E. coli (DEC) strains are important causes of diarrhoea in the developing world and, to a lesser extent, inthe developed world. In this study, we investigated the prevalence of the virulence genes specific for five major pathogroups of diarrheagenic Escherichia coli (DEC) in primary cultures from diarrhoeagenic patients in Burkina Faso.Methodology: From September 2016 to Mars 2017, a total of 211 faecal samples from diarrhoeagenic patients from urban hospitals of Ouagadou, Burkina Faso have been analysed. A 16-plex PCR was used to detect simultaneously, the five major DEC pathotypes (enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), Shiga toxin-producing E. coli (STEC), enteroaggregative E. coli (EAEC) and enteroinvasive E. coli (EIEC)).Results: At least one diarrhoeagenic E. Coli pathotype was detected in 31 samples (14.7%) in children and adults with diarrhoea. EAEC was the most common pathotype detected 9.5% (20/211), followed by EIEC2.4% (05/211) and STEC 0.5% (01/211). More than one DEC pathotype were detected in 2.4% (05/211) patients. EPEC and ETEC were not detected in single infection but in co-infection with others pathotypes.Conclusion: DEC, especially enteroaggregative, may be important responsible of diarrhoeas in Burkina Faso from all ages patient.Key Words: Diarrhoeagenic Escherichia coli, 16-plex PCR, Burkina Faso, human diarrhoeas stool

Frequent burning promotes invasions of alien plants into a mesic African savanna

Fire is both inevitable and necessary for maintaining the structure and functioning of mesic savannas. Without disturbances such as fire and herbivory, tree cover can increase at the expense of grass cover and over time dominate mesic savannas. Consequently, repeated burning is widely used to suppress tree recruitment and control bush encroachment. However, the effect of regular burning on invasion by alien plant species is little understood. Here, vegetation data from a long-term fire experiment, which began in 1953 in a mesic Zimbabwean savanna, were used to test whether the frequency of burning promoted alien plant invasion. The fire treatments consisted of late season fires, lit at 1-, 2-, 3-, and 4-year intervals, and these regularly burnt plots were compared with unburnt plots. Results show that over half a century of frequent burning promoted the invasion by alien plants relative to areas where fire was excluded. More alien plant species became established in plots that had a higher frequency of burning. The proportion of alien species in the species assemblage was highest in the annually burnt plots followed by plots burnt biennially. Alien plant invasion was lowest in plots protected from fire but did not differ significantly between plots burnt triennially and quadrennially. Further, the abundance of five alien forbs increased significantly as the interval (in years) between fires became shorter. On average, the density of these alien forbs in annually burnt plots was at least ten times as high as the density of unburnt plots. Plant diversity was also altered by long-term burning. Total plant species richness was significantly lower in the unburnt plots compared to regularly burnt plots. These findings suggest that frequent burning of mesic savannas enhances invasion by alien plants, with short intervals between fires favouring alien forbs. Therefore, reducing the frequency of burning may be a key to minimising the risk of alien plant spread into mesic savannas, which is important because invasive plants pose a threat to native biodiversity and may alter savanna functioning

Nutritional properties of enriched local complementary flours

Abstract: This study aimed to identify the nutritional, functional, sensory and microbiological profile of experimental nutritional flours, produced with local products in Burkina Faso. The raw materials included maize (Zea mays), millet (Pennisetum glaucum) and rice (Oryza sativa). Local ingredients were pulps of Adansonia digitata and Parkia biglobosa and seeds of Cucurbita maxima and Moringa oleifera. Three formula were developed, the first (F1) with maize, the second (F2) with rice and the last (F3) with millet. Each of these cereals was mixed with predetermined portions of seeds and pulps in order to obtain enriched flour. Nutritional, microbiological and functional analysis and the acceptability criteria of these enriched flours were assessed and compared to Misola (F4), the existing local complementary flour. The fat content of experimental flours were respectively in the first (F1), second (F2) and third formula (F3) 15.91±0.01%, 11.82±0.02% and 17.02±0.02%. The carbohydrate range was 65.46±0.06%, 70.81±0.01% and 64.51±0.01% for F1, F2 and F3, while the energetic value is higher than recommended (453.07±0.05, 424.56±0.03 and 458.96±0.05 kcal respectively for F1, F2 and F3). Functional characteristics indicated the good viscosity (117, 119 and 121 mm/30 sec for F1, F2 and F3) least gelation (9, 6 and 7%) and water absorption capacity (2, 4 and 1 g/g). Trained sensory evaluation panellists gore the enriched flour porridge a score of acceptable. These enriched flours have great potential as a weaning food in resource-poor and technologically under-developed countries

Biomass burning fuel consumption rates: a field measurement database

Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peerreviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha 1 with a standard deviation of 2.2),tropical forest (n = 19, FC = 126 +/- 77),temperate forest (n = 12, FC = 58 +/- 72),boreal forest (n = 16, FC = 35 +/- 24),pasture (n = 4, FC = 28 +/- 9.3),shifting cultivation (n = 2, FC = 23, with a range of 4.0-43),crop residue (n = 4, FC = 6.5 +/- 9.0),chaparral (n = 3, FC = 27 +/- 19),tropical peatland (n = 4, FC = 314 +/- 196),boreal peatland (n = 2, FC = 42 [42-43]),and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e. g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole biomes. Comparing the compiled FC values with co-located Global Fire Emissions Database version 3 (GFED3) FC indicates that modeling studies that aim to represent variability in FC also within biomes, still require improvements as they have difficulty in representing the dynamics governing FC

Effects of customized climate services on land and labor productivity in Burkina Faso and Ghana

Climate services favor adopting strategies to increase agricultural productivity, enhance sustainable development, and adapt to unavoidable climate variability and change. However, for climates services to be effective, they must be accessible and suitable to user needs. This study investigated the effects of customized climate services (CCS) on land and labor productivity. Portraying the case of CCS delivered in the districts of Bolgatanga (Northern Ghana), Dano and Ouahigouya (western and northern Burkina Faso) in West Africa, it used: i) historical panel data of daily rainfall, yields, agricultural input, and output prices; ii) cost statements of farm operations and iii) other survey data from beneficiaries of on-farm demonstrations (pilot sites). Different results were found across farmers on the demonstrator sites, with Dano and Bolgatanga recording the best land and labor productivity. Strong and positive effects were observed in Dano, where land productivity increased by 200% and labor productivity doubled despite consecutive pluviometric extremes such as heavy rain events and prolonged dry spells in the 2017 and 2018 cropping seasons. Further investigation showed that CCS was particularly favorable to land and labor productivity of farmers who were committed to the advisory given by the CCS providers. Therefore, as perishable goods, the success of CCS applications would require thorough coproduction, delivery, and monitoring for their effectiveness in improving land and labor productivity for agriculture in semi-arid regions of West Africa

Facile Hydrogen Evolution Reaction on WO3Nanorods

Tungsten trioxide nanorods have been generated by the thermal decomposition (450 °C) of tetrabutylammonium decatungstate. The synthesized tungsten trioxide (WO3) nanorods have been characterized by XRD, Raman, SEM, TEM, HRTEM and cyclic voltammetry. High resolution transmission electron microscopy and X-ray diffraction analysis showed that the synthesized WO3nanorods are crystalline in nature with monoclinic structure. The electrochemical experiments showed that they constitute a better electrocatalytic system for hydrogen evolution reaction in acid medium compared to their bulk counterpart