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Assessment of Groundwater Quality for Drinking and Irrigation Uses in the Samba dia Area, Central West Senegal

Journal of Water Resource and Protection 2023年第4期15卷 130-148页

作者： amadou Sarr Seyni Ndoye Axel Laurel Tcheheumeni Djanni Serigne Faye Département de Géologie Faculté des Sciences et Techniques Université Cheikh Anta Diop Dakar Fann Sénégal Département de Génie Civil Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Fann Sénégal

In the Sahelian zone in Africa, groundwater is the main source of drinking water for domestic, industrial, and agricultural uses. The groundwater of the Samba dia sandy aquifer was assessed for understanding processes controlling the hydrogeochemistry and its drinking and irrigation suitability, on the basis of various water quality parameters. For the present study, thirty-three groundwater samples were collected in wells of the study area during the dry season in March 2021 and subjected to analysis for chemical characteristics (major ions), pH, electrical conductivity (EC), and total dissolved solids (TDS). Gibbs plot depicts that the process of ionic exchange is mainly due to the dissolution of water-rock interaction. The Piper diagram indicates a largely dominant sodium chloride facies with 70% of the groundwater samples followed by calcium chloride facies (18%) than calcium bicarbonate facies (12%). Analytical results of hydrogeochemical parameters of groundwater samples reveal that the majority of samples are within the World Health Organization safety range for drinking water. TDS and electrical conductivity (EC) values of groundwater indicate that 70% and 61% are safe for drinking water, respectively. Sodium percentage (% Na), Sodium Adsorption Ratio (SAR) values, and Ca/Mg ratio were calculated and compared with the standard guideline values recommended by the World Health Organization and agricultural water standards. This study shows that the groundwater in the area is mostly chemically suitable for drinking and irrigation, although some wells at the edge of the area exhibit signs of progressive salinization and traces of pollution.

关键词： Samba dia Groundwater Hydrogeochemistry Suitability Drinking Irrigation

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Acute Bilirubin Encephalopathy: A Propos of 151 Cases Collected during a Multicentric Study in Senegal

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Open Journal of Pediatrics 2023年第1期13卷 50-62页

作者： Serigne Tawa Ndiaye Yaye Joor K. B. Dieng Papa Moctar Faye Mohameth Mbodj Sofietou Dieye Khadim Bop Papa Souley Sow amadou Sow Ndeye Fatou Sow Ibrahima diop Aziz Faye Sadio Konate Ibrahima diagne Mousatapha Ndiaye Ousmane Ndiaye Centre Hospitalier National D’Enfants Albert Royer Dakar Senegal Centre Hospitalier Municipal Abass Ndao Dakar Senegal Gaston Berger University Saint Louis Senegal Cheikh Anta diop University Dakar Senegal

Introduction: Bilirubin encephalopathy is a debilitating complication of severe neonatal unconjugated bilirubin jaundice. The aim of this study was to determine the frequency of occurrence of this complication and to describe the diagnostic and prognostic aspects in Senegal. Materials and Methods: This was a multicenter, descriptive and analytical study conducted in 32 neonatal units of various levels, with retrospective (January to December 2020) and prospective (January to August 2021) collection. All neonates hospitalized for acute bilirubin encephalopathy were included. The diagnostic criteria were the presence of jaundice associated with neurological signs (muscle tone disorders, abnormal movements, convulsions, etc.), with no other obvious etiology found. The data were entered and analyzed using SPSS version 23 software. The significance threshold was retained for a p-value Results: We registered 151 patients. The mean age was 6 days and the sex ratio was 2.5 (clear male predominance). The majority of newborns were from Dakar (51%). Twenty-two (22%) were premature and 32% had low birth weight. Half of the newborns (50%) came from home and 87% were exclusively breastfed. The average time to consult was 3 days. Neurological signs were dominated by decreased primitive reflexes (74%), abnormal movements (59%) and lethargy (50%). Dehydration (30%) and anemia (26%) were often associated. The mean bilirubin level was 416 umol/l. Neonatal infections (19%) and Rhesus (16.7%) and ABO (8.7) incompatibility were the main causes. One third (33%) of patients had received intensive phototherapy and only 2% had received exchange blood transfusion. The case fatality was 48.9%. Conclusion: Bilirubin encephalopathy remains a major concern in Senegal. It is associated with high mortality and numerous neurological sequelae. Progress in terms of early detection and appropriate management is urgently needed on a national scale.

关键词： Icterus Encephalopathy Phototherapy Lethality

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Effects of the Nature of Boundaries Conditions and Their Truncation Errors on the Distribution of Minority Carriers in Silicon Solar Cell

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Journal of Modern Physics 2022年第3期13卷 315-322页

作者： Mamadou Bamba Sene Mountaga Boiro Alioune Faye amadou diao Cheikh Mbow Solid State Physics and Materials Sciences Laboratory Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal Fluid Mechanics and Applied Dynamics System Laboratory Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal

In this work, the effects of boundaries conditions and truncation errors in the distribution of minority carriers in the semiconductor are studied. It is a one-dimensional digital study of a polycrystalline silicon solar cell under polychromatic illumination in a dynamic state. Starting from the Boltzmann equation of semiconductors, the author establishes the general equation of particle transport. Assumptions made on the latter allow it to give the equation of distribution of minority carriers in a general way in its case to be studied. This dimensioned distribution equation reveals the parameters of influences on the distribution of carriers. It obtains a partial derivative equation for the carrier distribution function. The boundary conditions are then discretized to order one and then to order two. By considering boundary conditions and the nature of the carriers, the author numerically resolves the discretized general equation by assessing the influence of the nature of the boundary conditions and truncation errors and the influence of the discretization step on the density of the charge carriers by setting certain parameters and varying others. The work ends with a conclusion and logical follow-up to this work.

关键词： Transport Equation Load Carrier Densities Implicit Scheme Semiconductor Discretization

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Study of the Impact of Grid Disconnections on the Production of a Photovoltaic Solar Power Plant: Case of diamniadio Power Plant

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Journal of Power and Energy Engineering 2023年第6期11卷 16-25页

作者： amadou Ndiaye Mohamed Cherif Aidara Amy Mbaye Mamadou Lamine Ndiaye Laboratoire Eau-Energie-Environnement-Procédés Industriels (L3EPI) Ecole Supérieure Polytechnique Université Cheikh Anta Diop (UCAD) Dakar Senegal

Today, renewable energy projects connected to the interconnected network, with powers of the order of tens of megawatts, are more and more numerous in sub-Saharan Africa. And financing these investments requires a reliable amortization schedule. In the context of photovoltaic systems connected to the interconnected electricity grid, the quintessence of damping is the amount of energy injected into the grid. Thus it is fundamental to know the parameters of this network and their variation. This paper presents an evaluation of the impact of power grid disturbances on the performance of a solar PV plant under real conditions. The CICAD photovoltaic solar plant, connected to the Senelec distribution network, with an installed capacity of 2 MWp is the study setting. An energy audit of the plant is carried out. Then the percentage of each loss is determined: voltage drops, module degradation, inverter efficiency. The duration of each disconnection is measured and recorded daily. The corresponding quantity of lost energy is thus calculated from meteorological data (irradiation, temperature, wind speed, illumination) recorded by the measurement unit in one-minute steps. The observation period is three months. The total duration of disconnections related to the instability of the electrical network during the study period is 46.7 hours. The amount of energy lost is estimated at 22.6 MWh. This represents 2.4% of the actual calculated production.

关键词： Photovoltaic Power Plant Disconnections Network Evaluation Lost En-ergy

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Difficulties in the Management of Systemic Autoimmune Diseases in Saint-Louis Du Senegal through the Analysis of a Series of 70 Observations

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Open Journal of Internal Medicine 2021年第4期11卷 258-264页

作者： diatou G. dia amadou D. dia Nafissatou diagne Awa C. Ndao Cheikh T. Tall Blaise M. Ngouamba Gaston Berger Saint-Louis University Dakar Senegal Cheikh Anta diop University Dakar Senegal Saint-Christopher University Dakar Senegal Department of Internal Medecine Saint-Louis Sénégal

Introduction: Systemic Autoimmune Diseases (SAID) long considered very rare in Africa are increasingly the subject of publications. The objective of this work is to identify the difficulties in the management of these pathologies in an internal medicine department in northern Senegal by analyzing the epidemiological, clinical-biological, therapeutic and evolutionary aspects of SAID. Methods: This was a descriptive cross-sectional study carried out in the internal medicine department of the Saint-Louis University Hospital Center. Included were all the files of patients followed in outpatient and/or hospitalization for autoimmune diseases according to the criteria of the American College of Rheumatology, during the period from January 2017 to December 2020. The data were analyzed using SPSS software version 21.0. As the study was descriptive, no statistical test was performed. Results: Out of 3800 patients, 70 presented SAID, i.e. a hospital prevalence of 1.8%. Polyarthritis was the first reason for consultation in 97% followed by skin manifestations in 8%. The patients had positive anti-nuclear autoantibodies in 88% of cases. Rheumatoid arthritis was the predominant condition (71%) followed by systemic lupus erythematosus (SLE) (15%) and undifferentiated autoimmune diseases in 10%. Eleven percent (11%) of patients had an associated autoimmune disease. Corticosteroids were used in the treatment of these conditions in 97% of cases and methotrexate was the most prescribed immunosuppressant (54%). Thirty-two percent (32%) of patients are lost to follow-up. Conclusion: SAID are diverse and under diagnosed;they are characterized by diagnostic delay above all linked to access to specialists and sometimes to the high cost of paraclinical examinations, in particular immunology. Treatment remains based primarily on corticosteroid therapy and conventional immunosuppressants in the face of the unavailabi

关键词： Systemic Autoimmune Diseases Polyarthritis Systemic Lupus Erythematosus Saint-Louis Du Senegal

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Diffusion Coefficient at Resonance Frequency as Applied to n+/p/p+ Silicon Solar Cell Optimum Base Thickness Determination

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Journal of Electromagnetic Analysis and Applications 2020年第10期12卷 145-158页

作者： amadou Mar Ndiaye Sega Gueye Mame Faty Mbaye Fall Gora diop amadou Mamour Ba Mamadou Lamine Ba Ibrahima diatta Lemrabott Habiboullah Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal Ecole Polytechnique de Thiès Thiès Sénégal Département Génie Electrique Ecole Supérieure Polytechnique de Nouakchott Nouakchott Mauritanie

The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (D(ω, B), in the (p) base leads to maximum values (Dmax) at resonance frequencies (ωr). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, ωr and B, are then established, and will be data for industrial development of low-cost solar cells for specific use.

关键词： Silicon Solar Cell Resonance Frequency Magnetic Field Recombination Velocity Base Thickness

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Northeastern Tropical Atlantic SST and Sahel Rainfall Variability

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Atmospheric and Climate Sciences 2023年第4期13卷 431-454页

作者： Dahirou Wane Abdou Lahat Dieng Coumba Niang amadou T. Gaye Laboratoire de Physique de l’Atmosphère et de l’Océan Siméon Fongang Ecole Supérieure Polytechnique Université Cheikh Anta Diop de Dakar (LPAO-SF/ESP/UCAD) Dakar Senegal

The SST variability during the summer period in the northeastern tropical Atlantic region (NTA) is characterized by an alternation of warming/cooling which represents 87% of the total variability. The aim of this paper is to study the atmospheric responses as well as the precipitation associated with these oceanic conditions. Based on Reynolds’s SST from 1982 to 2019, a normalized Northern Tropical Atlantic index (NTAI) is computed into the region between 15° - 25°W;12° - 16°N and a composite analysis is then performed. It is shown that the NTAI is significantly correlated with the SST’s first principal component mode (PC1) in this region. Moreover, the composite of SST anomalies and atmospheric parameters exhibits a strong local ocean-atmosphere interaction which highly impacts the large-scale atmospheric circulation in West Africa, particularly in the western Sahel. An in-depth analysis shows that the atmospheric response to the warm (cold) SST is a cyclonic (anticyclonic) circulation in the lower layers near the West Africa Coast. This cyclonic (anticyclonic) circulation strengthens/reduces the moisture transport towards the continent in the low levels. In the middle layers of the atmosphere (500 hPa), the warm (cold) composite is associated with a decrease (increase) in the intensity of the African Easterly Jet (AEJ) whereas, in the upper atmosphere (200 hPa), the strengthening (weakening) of the Tropical Easterly Jet (TEJ) is observed. With regard to the composite precipitation field, a positive/negative SST anomaly is associated with significantly enhanced/reduced rainfall in the western Sahelian region. It is found that this relationship (correlation) increases as we are closer to the coasts.

关键词： SST-Rain Sahel Rainfall Senegal Rainfall Ocean-Atmosphere Interaction

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n<sup>+</sup>-p-p<sup>+</sup>Silicon Solar Cell Base Optimum Thickness Determination under Magnetic Field

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Journal of Electromagnetic Analysis and Applications 2020年第7期12卷 103-113页

作者： Cheikh Thiaw Mamadou Lamine Ba Mamour amadou Ba Gora diop Ibrahima diatta Mor Ndiaye Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n+-p-p+ under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.

关键词： Silicon Solar Cell Magnetotransport Surface Recombination Velocity Base Thickness

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Electrical Modeling of a Silicon Photovoltaic Solar Cell: Comparative Study of Models Characterizing the Photovoltaic Solar Cell

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Open Journal of Applied Sciences 2023年第10期13卷 1787-1795页

作者： Mamadou Bamba Sene Almoustapha Samoura Saliou Diouf amadou diao Cheikh Mbow Solid State Physics and Materials Sciences Laboratory Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal Laboratory for the Use of Rays X (LUX) Dakar Senegal Fluid Mechanics and Applied Dynamics System Laboratory Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal

In this article we make a detailed study and a presentation of the different models of circuit’s equivalent to silicon-based photovoltaic solar cells. Starting from a real solar cell and real phenomena from the manufacture of the cell to the production of current by the cell. A comparison of the models with a real experimental method is carried out. The comparison is based on an overlay of the results. The study allowed us to choose the most suitable model. We are interested in the losses by leaks and the losses due to the development of the cell. In fact, we studied the influence of the shunt resistance on the current-voltage characteristic and the electrical power.

关键词： Current Characteristic-Voltage Photon Current Electric model Photocurrent Photo Voltage Electric Power Semiconductor

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Micropropagation from Juvenile Material of Annona senegalensis Pers.

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Agricultural Sciences 2022年第3期13卷 448-466页

作者： Oumar Ba amadou Lamine Ndoye Abraham Dieme Mame Ourèye Sy Laboratoire Campus de Biotechnologies Végétales Département de Biologie Végétale Faculté des Sciences & Techniques Université Cheikh Anta Diop Dakar Sénégal Laboratoire Mixte International-Adaptation des Plantes et Microorganismes associes aux Stress Environnementaux (LMI-LAPSE) IRD ISRA UCAD Dakar Sénégal

Annona senegalensis is a savannah species present in the wild in tropical and sub-tropical African regions. It is used by the local populations for its many economic, pharmacological, nutritional and ecological interests. However, the strong pressure exerted on this species as well as the increasing degradation of the ecosystems, in which it evolves, seriously compromise its sustainability and development. Conventional methods of vegetative propagation are not sufficient to ensure its durable regeneration and the renewal of endemic populations in Senegal. In this context, it was undertaken in vitro propagation, from 30 days old juvenile seedlings. Thus, axillary, cotyledonary and apical nodes were in vitro cultured in Murashige and Skoog (1962) medium (MS), with different concentrations of cytokinins and/or auxins. BAP used alone at 2 mg•L−1 proved to be more beneficial for micropropagation of different types of explants compared to Kinetin used alone or in combination with BAP, especially for axillary and cotyledonary nodes. The BAP-NAA combination allowed to have a better elongation of newly formed shoots. For shoots of apical and cotyledonary nodes origin, a rhizogenic induction of 5 days, with IBA at 25 mg•L−1, resulted in a better rooting rate with, respectively, 75% (for 2.22 roots) and 66.67% (for 4.17 roots). For newly formed shoots of axillary origin, a 24-hour rooting induction with IBA at 50 mg•L−1 gave a rooting rate of 58.33% (for 2.4 roots). After 30 days of acclimatization, the survival rate was 75% for the young plants from the apices and 83.33% for those originating from the cotyledonary and axillary nodes. This protocol can therefore be adopted for the in vitro clonal propagation of A. senegalensis juvenile material.

关键词： Annona senegalensis Micropropagation Juvenile Material 6-Benzylaminopurine 1-Naphthaleneacetic Acid Indole-3-Butyric Acid

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