Allahdin O.,University of Bangui |
Mabingui J.,University of Bangui |
Wartel M.,Lille University of Science and Technology |
Boughriet A.,Lille University of Science and Technology
Applied Clay Science | Year: 2017
Brick was pre-activated with HCl and subsequently coated with ferrihydrite. To assess the potential of this modified brick for Pb2 + removal, adsorption experiments were conducted in a fixed-bed continuous-flow column system. The prediction of breakthrough curves was obtained by using the Thomas model. MINTEQ computations revealed that Pb2 + and Pb(OH)+ are the major species present in the column solution. Potentiometric analysis and electrophoretic mobility measurements provided strong evidence of the surface basicity of coated brick due to the existence of sodic negatively charged sites: > S[sbnd]O− Na+ with S[dbnd]Fe; Si; or Al. Using Environmental Scanning Electron Microscopy (ESEM) equipped with an Energy Dispersive X-Ray Spectroscopy (EDS), micro-analyses showed clearly that Na atoms present in coated brick are preferentially bound to ferrihydrite specimens. The ESEM/EDS technique allowed to further highlight discrete Pb[sbnd]Fe combinations and to contend that Pb2 + ions are better adsorbed onto Fe-rich aggregates than onto SiO2 and alumino-silicates (clays). Before the breakthrough time, the pH in the effluent solution was found to be dependent upon the electrokinetic characteristics of coated brick. After this time, the pH was instead governed by the acidity of not adsorbed lead(II). To support this, simulation calculations relative to the pH evolution in the column medium were made. The addition of a background electrolyte (Na+ NO3 −) led nevertheless to a weaker adsorption capacity of Pb2 + on coated brick, because positively charged Na ion competed favorably at the expense of lead(II) via electrostatic attraction forces. © 2017 Elsevier B.V.
Agency: European Commission | Branch: FP7 | Program: CP-SICA | Phase: HEALTH-2007-3.5-2 | Award Amount: 3.76M | Year: 2009
Inadequate access to and use of research evidence to inform health policy limits the achievement of universal and equitable access to healthcare, hinders quality improvement and makes it difficult to use healthcare resources wisely. Poorly informed decision-making about health policies and systems is one of the reasons why services fail to reach those most in need, health indicators are off track, and it appears unlikely that many countries in Africa will meet the health MDGs. SURE will support improvements in health policies and systems in low and middle-income countries (LMIC) by improving access to and use of policy-relevant syntheses of research evidence that are contextualized and tailored to meet the needs of decision makers. SURE will develop, pilot and evaluate five strategies designed to strengthen access to and use of reliable and timely research syntheses in policymaking: user friendly formats for research syntheses, clearing houses for syntheses and policy relevant research, mechanisms for responding rapidly to policymakers needs for research evidence, methods for organizing and managing deliberative forums involving policymakers, researchers and others, and methods for involving civil society and the public in policy development. SURE will develop capacity for evidence-informed healthcare policy and undertake a comparative evaluation of initiatives between policymakers and researchers using these and other strategies. SURE will collaborate with the Evidence-Informed Health Policy Network (EVIPNet) and the Regional East African Community Health (REACH) Policy Initiativetwo international efforts to improve the use of research evidence in policy and health systems decisions via partnerships between policymakers, researchers and civil society. SURE will use a range of dissemination strategies. Global dissemination will be coordinated by and capitalise on WHO, with the aim of maximising the projects impact on health policy in Africa and othe
Poumaye N.,University of Bangui |
Mabingui J.,University of Bangui |
Lutgen P.,Iwerliewen Fier Bedreete Volleker IFBV |
Bigan M.,University of Lille Nord de France
Chemical Engineering Research and Design | Year: 2012
Moringa seeds can be effective in the treatment of water because they contain a cationic electrolyte. They can then replace the sulfate of alumina or other flocculants. In this study, we opted for the clarification of surface water from the river M'Poko using seeds of Moringa oleifera dried and transformed into powder. In the literature, we can find very different quantities of seeds used. We have used a method of experimental design to optimize the treatment of our samples of raw water with the seeds of Moringa. The experimental design used is a full factorial design that determines the importance of various factors and also the relationship between these factors so as to identify the best conditions to meet the target set by this study, which is to clarify a maximum quantity of raw water from the river. Another problem, met in the use of Moringa, is the important contribution of organic matter in the water treated by this natural coagulant. To avoid a bacterial proliferation, in time, in the water so treated, we used sand/coal filtration, which proved to be very effective. The water, treated by Moringa and filtered, possesses turbidity and a quantity of organic matter corresponding to the required standards. Such water can thus, be disinfected by chlorination for human consumption. © 2012 The Institution of Chemical Engineers.
Agency: European Commission | Branch: FP7 | Program: CP | Phase: SPA.2010.1.1-04 | Award Amount: 3.64M | Year: 2011
Deforestation and degradation are estimated to contribute about 20% of global greenhouse gas emissions. A group of developing countries initiated a process at the UNFCCC Conference of Parties (COP-11) in 2005 to address the issue of reducing emissions from deforestation and degradation (REDD), that would be implemented as a post-Kyoto Protocol mechanism. Countries have been encouraged to develop REDD Pilot Projects to assess the feasibility of such a mechanism. Earth Observation in combination with in-situ data are important tools for forest cover and land use monitoring in the REDD process. The current proposal REDDAF aims to develop pre-operational forest monitoring services in two Congo Basin countries that are actively involved in the REDD process. The users in both Cameroon and Central African Republic require such services and will actively participate in project implementation. The main activities proposed are: Stakeholder Analysis: country specific user requirements to identify the needs of stakeholders in terms of instituting REDD projects. Carbon stock accounting: research and development of methods for improved EO/ in-situ data applications to estimate areal extent of deforestation and forest degradation as well as biomass per unit area. The historical changes in forest cover will be used to establish a reference baseline. Based on these research efforts pre-operational processing chains will be developed. Technology Transfer/Capacity Building to the country: activities to ensure that project results, methodologies and lessons learned are provided in a manner to best support the work of national and regional counterparts. The services and products that will be delivered to the user community include forest cover maps and forest cover change maps for 1990-2000 and 20002009/10 (land use changes based on six IPCC compliant land use classes); degradation maps, biomass maps and the relevant digital datasets.
Wango S.P.,University of Bangui |
Josens G.,Roosevelt University
African Zoology | Year: 2011
Two species of Cubitermes coexist in the grassy Loudetia Savanna of Bondoé, in the Central African Republic, namely C. sankurensis (Wasmann, 1911) and C. ugandensis (Fuller, 1923) Despite the obvious size difference between individuals their nests have the same general shape but there are significant, though small, differences in height, diameter, number of caps, surface and volume. The closest correlations between these five parameters can be seen between the surface and the volume of the nests. The regressions between these two parameters are identical for both species; the addition of a first cap decreases the volume/surface ratio but a second or third cap does not alter this ratio further. Three apparent age classes have been attributed to the nests based on their external appearance: recent, eroded, and dilapidated. The great density (1297 nests/ha) and abundance of the nests that are dilapidated but still occupied by a declining population clearly suggests that the pressure from predation is weak. This study suggests that the environmental conditions are more influential than the species in shaping the mounds and tentative population dynamics of the termite mounds of Bondoé are outlined.
Giles-Vernick T.,Institute Pasteur Paris |
Traore A.,Center National Of Recherche Et Of Formation Sur Le Paludisme And Groupe Of Recherche Action En Sante Ouagadougou |
Bainilago L.,University of Bangui
Medical Anthropology Quarterly | Year: 2016
This comparative study explores incertitude about hepatitis B (HBV) and its implications for childhood vaccination in Bangui, Central African Republic, and the Cascades region, Burkina Faso. Anthropological approaches to vaccination, which counter stereotypes of "ignorant" publics needing education to accept vaccination, excavate alternative ways of knowing about illness and vaccination. We build on these approaches, evaluating different kinds of incertitude (ambiguity, uncertainty, ignorance) about infancy, HBV, health protection, and vaccination. Using interviews and participant observation, we find that Bangui and Cascades publics framed their incertitude differently through stories of infancy, illness, and protection. We locate different forms of incertitude within their historical contexts to illuminate why vaccination practices differ in the Cascades region and Bangui. A more nuanced approach to incomplete knowledge, situated in political, economic, and social histories of the state and vaccination, can contribute to more appropriate global health strategies to improve HBV prevention. © 2016 American Anthropological Association.
Favier C.,Montpellier University |
Aleman J.,Montpellier University |
Aleman J.,CIRAD - Agricultural Research for Development |
Bremond L.,Montpellier University |
And 3 more authors.
Global Ecology and Biogeography | Year: 2012
Aim To describe patterns of tree cover in savannas over a climatic gradient and a range of spatial scales and test if there are identifiable climate-related mean structures, if tree cover always increases with water availability and if there is a continuous trend or a stepwise trend in tree cover. Location Central Tropical Africa. Methods We compared a new analysis of satellite tree cover data with botanical, phytogeographical and environmental data. Results Along the climatic transect, six vegetation structures were distinguished according to their average tree cover, which can co-occur as mosaics. The resulting abrupt shifts in tree cover were not correlated to any shifts in either environmental variables or in tree species distributions. Main conclusions A strong contrast appears between fine-scale variability in tree cover and coarse-scale structural states that are stable over several degrees of latitude. While climate parameters and species pools display a continuous evolution along the climatic gradient, these stable structural states have discontinuous transitions, resulting in regions containing mosaics of alternative stable states. Soils appear to have little effect inside the climatic stable state domains but a strong action on the location of the transitions. This indicates that savannas are patch dynamics systems, prone to feedbacks stabilizing their coarse-scale structure over wide ranges of environmental conditions. © 2011 Blackwell Publishing Ltd.
Ouedraogo D.-Y.,CIRAD - Agricultural Research for Development |
Beina D.,University of Bangui |
Picard N.,British Petroleum |
Mortier F.,CIRAD - Agricultural Research for Development |
And 2 more authors.
Forest Ecology and Management | Year: 2011
In the Congo Basin where most timber species are light-demanding, the low logging intensities commonly implemented (1-2 trees harvested ha -1) do not provide sufficient canopy gaps to ensure species regeneration. The regeneration of light-demanding timber species may therefore benefit from more intensive logging, or from post-harvest treatments such as thinning by poison girdling that increases light penetration. Little is known of the impact of post-harvest treatments on the floristic composition of tropical moist forests. This study therefore aimed to assess the effects of low and high selective logging (≃2.33 and 4.73 trees harvested ha -1, and ≃4.96 and 9.16m 2ha -1 of basal area removed (logging+damage), respectively) - followed or not by thinning (≃21.14 trees thinned ha -1, and ≃6.57m 2ha -1 of basal area removed) - on the floristic composition of a tropical moist forest in the Central African Republic, from 7 to 23 years after logging.We analyzed abundance data for 110 tree genera recorded every year for 14 years in 25 one-hectare permanent subplots. We used multivariate analysis to detect floristic variations between treatments and we assessed changes in floristic composition throughout the period. We compared floristic composition recovery between thinned and unthinned subplots, using unlogged subplots as a reference characterizing the pre-logging floristic composition.Logging and thinning had little impact on the floristic composition of the subplots as quantified 7 to 23 years later, though they did increase the proportion of pioneer species. Surprisingly, additional thinning at both logging levels failed to further distance floristic composition from that of the unlogged subplots, though it did increase disturbance intensity. Floristic composition recovery appeared to be facilitated when thinning was associated with logging. Thinning seemed to favor the growth and survival of non-pioneer species, to the detriment of pioneer species. These non-pioneer species could either be non-pioneer light demanders or shade-bearers. One explanation for this is that thinning by tree-poison girdling increased light availability without causing major damage to the forest, and thus increased the growth and survival of advance regeneration. The resulting enhanced competition then reduced the survival of pioneer species. © 2011 Elsevier B.V.
Giles-Vernick T.,Institute Pasteur Paris |
Traore A.,Center National Of Recherche Et Of Formation Sur Le Paludisme And Groupe Of Recherche Action En Sante |
Bainilago L.,University of Bangui
Medical Anthropology Quarterly | Year: 2016
This comparative study explores incertitude about hepatitis B (HBV) and its implications for childhood vaccination in Bangui, Central African Republic, and the Cascades region, Burkina Faso. Anthropological approaches to vaccination, which counter stereotypes of “ignorant” publics needing education to accept vaccination, excavate alternative ways of knowing about illness and vaccination. We build on these approaches, evaluating different kinds of incertitude (ambiguity, uncertainty, ignorance) about infancy, HBV, health protection, and vaccination. Using interviews and participant observation, we find that Bangui and Cascades publics framed their incertitude differently through stories of infancy, illness, and protection. We locate different forms of incertitude within their historical contexts to illuminate why vaccination practices differ in the Cascades region and Bangui. A more nuanced approach to incomplete knowledge, situated in political, economic, and social histories of the state and vaccination, can contribute to more appropriate global health strategies to improve HBV prevention. © 2016 by the American Anthropological Association
Pepin J.,Université de Sherbrooke |
Labbe A.-C.,University of Montréal |
Mamadou-Yaya F.,University of Bangui |
Mbelesso P.,University of Bangui |
And 4 more authors.
Clinical Infectious Diseases | Year: 2010
Background. The simultaneous emergence of human immunodeficiency virus (HIV)-1 group M and HIV-2 into human populations, circa 1921-1940, is attributed to urbanization and changes in sexual behavior. We hypothesized that the initial dissemination of HIV-1, before sexual transmission predominated, was facilitated by the administration, via reusable syringes and needles, of parenteral drugs against tropical diseases. As proxies for highly lethal HIV-1, we investigated risk factors for hepatitis C virus (HCV) and human T cell lymphotropic virus 1 (HTLV-1) infections, blood-borne viruses compatible with prolonged survival, in an area known in 1936-1950 as the most virulent focus of African trypanosomiasis. Methods. Cross-sectional survey of individuals 55 years and older in Mbimou land and Nola, Central African Republic. Dried blood spots were used for HCV and HTLV-1 serologic testing and nucleic acid detection. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were measured by logistic regression. Results. The only risk factor for HCV genotype 4 infection was treatment of trypanosomiasis before 1951 (OR, 3.13; 95% CI, 1.38-7.09). HTLV-1 infection was associated with having received ≥2 injections of pentamidine for trypanosomiasis chemoprophylaxis (adjusted OR, 2.03; 95% CI, 1.01-4.06) and with transfusions (adjusted OR, 2.82; 95% CI, 1.04-7.67). From historical data, we predicted that 59% of Mbimous 65 years and older would report treatment for trypanosomiasis before 1951; only 11% did so. Conclusions. Treatment of trypanosomiasis before 1951 may have caused iatrogenic HCV transmission. Population-wide half-yearly intramuscular pentamidine for trypanosomiasis chemoprophylaxis in 1947-1953 may have caused iatrogenic HTLV-1 transmission. These and other interventions against tropical diseases could have iatrogenically transmitted SIV cpz, jump-starting the HIV-1 epidemic. The excess mortality among patients with trypanosomiasis treated before 1951 supports this hypothesis. © 2010 by the Infectious Diseases Society of America. All rights reserved.