Modélisation d’une torche plasma thermique de forte puissance à électrode creuse pour son utilisation en haut fourneau

International audienceDans un contexte d’épuisement des ressources naturelles, de limitation de leurs émissions de CO2 et de réduction de leurs coûts de production d’acier par l’utilisation des Hauts fourneaux, les sidérurgistes ont imaginés de faire évoluer les Hauts fourneaux existants. Ils constituent des installations de base de l’industrie sidérurgique et la première étape de la production d’acier à l’échelle mondiale à partir d’un minerai de fer (70% de la production mondiale d’acier) [1]. Une des pistes pour leur optimisation est l’injection de gaz réducteur chaud au Haut fourneau [2], proposé dans le cadre du projet ADEME IGAR. Ce projet regroupe plusieurs partenaires industriels et académiques : AcelorMittal, Europlasma, Basis Electronique de Puissance, l’Institut de Mécanique des Fluides de Toulouse, l’Institut de mécanique et d’ingénierie de Bordeaux, le laboratoire CORIA, le laboratoire thermique énergétique des procédés et le Laboratoire Plasma et Conversion d’Energie. Il vise à réaliser la validation préindustrielle de l’injection de gaz réducteur chaud en Haut-Fourneau dans un objectif d’adaptation de la production sidérurgique aux enjeux de la transition énergétique et de l’empreinte carbone. Pour cela un des éléments clef consiste à tester un système de torches à plasma permettant de chauffer et de réformer les gaz sidérurgiques, et d’autre part le fonctionnement d’une tuyère de Haut-Fourneau spécifiquement conçue pour l’injection du gaz ainsi produit avec de l’oxygène pur et du charbon broyé. L’objectif premier étant de réduire significativement les émissions de gaz à effet de serre (essentiellement du CO2).Dans le cadre de ce projet, mes travaux au sein du LAPLACE consistent en une modélisation tridimensionnelle et à l’optimisation de l’hydrodynamique interne des torches à cathode creuse dans l’objectif de développer des torches de puissance plus élevée. Nos résultats seront confrontés aux caractérisations expérimentales du jet de plasma réalisées par l’Institut de Mécanique et d’Ingénierie de Bordeaux (I2M).Je présenterais le fonctionnement du Haut fourneau ainsi que la démarche qui va être menée dans le cadre de mes travaux de modélisation ainsi que les premiers résultats

Нові підходи в керуванні процесами електронно-променевого зварювання

The Gambia Estuary, a “normal” estuary with a decreasing salinity gradient from the mouth towards the head, is moderately exploited by small-scale fisheries and does not receive any severe pollution from either agriculture or industrial activities. Neither the Gambia River nor its estuary are artificially impounded. As the last large West African estuary free of major human disturbance, it is of considerable interest for comparative studies on the effect of major environmental perturbations in West African estuarine ecosystems. The aquatic environment and fish communities of the Gambia Estuary (about 250 km long) were studied by purse seine sampling at different periods in the river cycle, covering all hydro-climatic seasons that are characteristic of West African estuaries. Emphasis was placed on the diversity, composition, structure and distribution of fish assemblages in relation to fluctuations in physico-chemical factors such as water temperature, salinity and turbidity. Results on the aquatic environment, mainly the salinity range (from freshwater to 39) and dissolved oxygen (never a limiting factor for fish in the estuary) and on the main characteristics of the fish fauna (high diversity of life cycles, all the ecological categories represented) indicated that the Gambia Estuary was free of major climatic perturbation and reinforced the choice of this system as a reference for the study of the effects of major perturbations on estuarine tropical fish communities

International equatorial electrojet year : the African sector

International audienceThis paper presents the IEEY project in the African sector. The amount of our interpreted data is presently too short to allow proper scientific conclusions. Nevertheless, fist typical results illustrate our network possibilities. Some preliminary observations are briefly pre- , sented for their interest towards immediate research goals

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Prolifération de Cissus quadrangularis L. dans le Parc National des Iles-de-la-Madeleine, Sénégal

National parks are representative protected areas of natural ecosystems of a country. The introduction of alien plants in natural systems present a risk to biodiversity conservation, particularly where protected areas are islands. In the past few years , Cissus quadrangularis, a plant species from Indo-Malaysian, introduced in Senegal around 19th century, has developed signs that warry the authorities of Madeleine Islands National Park (MINP) of over 45 hectares. The present work was undertaken to evaluate the status on the distribution of C. quadrangularis and provide the information on the impact of that species on the ecosystems in this country part. The phytosociological surveys highlighted eight plant communities. From digital image (Quickbird) of 1 meter resolution, the main facies of occupancy were mapped and the areas occupied by C. quadrangularis were estimated. The surface of occurrency (5.7 ha) of plant stands population represent 27.2 % of the total area of the islands (20.9 ha). This plant is threats to biodiversity of the Park. It is urgent to find and implement appropriate measures to control the spread of the plant in the park

Modeling of a high power thermal plasma torch with hollow electrode for its use in blast furnace

International audienc

Nutrition support for HIV-TB co-infected adults in Senegal, West Africa: A randomized pilot implementation study.

BackgroundFood insecurity can contribute to poor adherence to both tuberculosis treatment and HIV antiretroviral therapy (ART). Interventions that target food insecurity have the potential to increase treatment adherence, improve clinical outcomes, and decrease mortality. The goals of this study were to compare the feasibility, acceptability, and potential impact of implementing two different forms of nutrition support for HIV-TB co-infected adults in the Casamance region of Senegal.MethodsWe conducted a randomized pilot implementation study among HIV-TB co-infected adults initiating treatment for TB (ClinicalTrials.gov Identifier: NCT03711721). Subjects received nutrition support in the form of a local food basket or Ready-to-Use Therapeutic Food (RUTF), distributed on a monthly basis for six months.ResultsA total of 178 monthly study encounters were completed by 26 HIV-TB co-infected adults; 14 received food baskets and 12 received RUTF. For both the food basket and RUTF, 100% of subjects obtained the supplement at every study encounter, transferred the supplement from the clinic to their household, and consumed the supplement. The food basket had greater acceptability and was more likely to be shared with members of the household. Adherence to TB treatment and ART exceeded 95%, and all outcomes, including CD4 cell count, hemoglobin, nutritional status, and food security, improved over the study period. All subjects completed TB treatment and were smear negative at treatment completion. The total cost of the local food basket was approximately $0.68 per day versus$0.99 for the RUTF.ConclusionThe implementation of nutrition support for HIV-TB co-infected adults in Senegal is feasible and may provide an effective strategy to improve adherence, treatment completion, and clinical outcomes for less than 1 USD per day. Further studies to determine the impact of nutrition support among a larger population of HIV-TB co-infected individuals are indicated

Prevalence, predictors, and management of advanced HIV disease among individuals initiating ART in Senegal, West Africa

Abstract Background The WHO guidelines for the management of advanced HIV disease recommend a package of care consisting of rapid initiation of antiretroviral therapy (ART), enhanced screening and diagnosis of tuberculosis (TB) and cryptococcal meningitis, co-trimoxazole prophylaxis, isoniazid preventive therapy (IPT), fluconazole pre-emptive therapy, and adherence support. The goals of this study were to determine the prevalence of advanced HIV disease among individuals initiating ART in Senegal, to identify predictors of advanced disease, and to evaluate adherence to the WHO guidelines. Methods This study was conducted among HIV-positive individuals initiating ART in Dakar and Ziguinchor, Senegal. Clinical evaluations, laboratory analyses, questionnaires and chart review were conducted. Logistic regression was used to identify predictors of advanced disease. Results A total of 198 subjects were enrolled; 70% were female. The majority of subjects (71%) had advanced HIV disease, defined by the WHO as a CD4 count < 200 cells/mm3 or clinical stage 3 or 4. The median CD4 count was 185 cells/mm3. The strongest predictors of advanced disease were age ≥ 35 (OR 5.80, 95%CI 2.35–14.30) and having sought care from a traditional healer (OR 3.86, 95%CI 1.17–12.78). Approximately one third of subjects initiated ART within 7 days of diagnosis. Co-trimoxazole prophylaxis was provided to 65% of subjects with CD4 counts ≤350 cells/mm3 or stage 3 or 4 disease. TB symptom screening was available for 166 subjects; 54% reported TB symptoms. Among those with TB symptoms, 39% underwent diagnostic evaluation. Among those eligible for IPT, one subject received isoniazid. No subjects underwent CrAg screening or received fluconazole to prevent cryptococcal meningitis. Conclusions This is the first study to report an association between seeking care from a traditional healer and presentation with WHO defined advanced disease in sub-Saharan Africa. Given the widespread use of traditional healers in sub-Saharan Africa, future studies to further explore this finding are indicated. Although the majority of individuals in this study presented with advanced disease and warranted management according to WHO guidelines, there were numerous missed opportunities to prevent HIV-associated morbidity and mortality. Programmatic evaluation is needed to identify barriers to implementation of the WHO guidelines and enhanced funding for operational research is indicated