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Restoration or Rehabilitation of the Faleme River Affected by Mining Activities: What Methods?

Journal of Water Resource and Protection 2024年第4期16卷 233-263页

作者： mor diop Ibrahima Mall Elhadji Mamadou Sonko Tidiane diop Birane Niane Cheikh Mbow Environmental Sciences Institute (ISE) Cheikh Anta Diop university of Dakar Dakar Senegal Higher School of Mines Geology and Environment Amadou Mahtar Mbow University of Diamniadio (UAM) Dakar Senegal Department of Chemical Cheikh Anta Diop university of Dakar Dakar Senegal Departmentof Engineering Sciences Iba Der Thiam University of Thi&#232s Thi&#232s Senegal

The Faleme River, a West Africa long transboundary stream (625 km) and abundant flow (>1100 million m3) is affected by severe erosion because of mining activities that takes place throughout the riverbed. To preserve this important watercourse and ensure the sustainability of its services, selecting and implementing appropriates restorations techniques is vital. In this context, the purpose of this paper was to present an overview of the actions and techniques that can be implemented for the restoration/rehabilitation of the Faleme. The methodological approach includes field investigation, water sampling, literature review with cases studies and SWOT analysis of the four methods presented: river dredging, constructed wetlands, floating treatment wetlands and chemical precipitation (coagulation and flocculation). The study confirmed the pollution of the river by suspended solids (TSS > 1100 mg/L) and heavy metals such as iron, zinc, aluminium, and arsenic. For the restoration methods, it was illustrated through description of their mode of operation and through some case studies presented, that all the four methods have proven their effectiveness in treating rivers but have differences in their costs, their sustainability (detrimental to living organisms or causing a second pollution) and social acceptance. They also have weaknesses and issues that must be addressed to ensure success of rehabilitation. For the case of the Faleme river, after analysis, floating treatment wetlands are highly recommended for their low cost, good removal efficiency if the vulnerability of the raft and buoyancy to strong waves and flow is under control.

关键词： Faleme River River Restoration Constructed Wetlands Dredging Floating Treatment Wetlands Coagulation-Flocculation

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Development and Application of Water Quality Index (WQI) for the Evaluation of the Physico-Chemical Quality of Groundwater in Gold Mining Areas of Southeastern Senegal

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Journal of Water Resource and Protection 2023年第2期15卷 33-50页

作者： mor diop Ibrahima Mall El Hadji Mamadou Sonko Tidiane diop Liengsy Badji Cheikh Mbow Environmental Sciences Institute (ISE) Cheikh Anta Diop University Dakar Senegal Amadou Mahtar Mbow University of Diamniadio (UAM) Dakar Senegal Department of Chemical Cheikh Anta Diop University Dakar Senegal Faculty of Medicine Pharmacy and Dentistry Cheikh Anta Diop University Dakar Senegal

Water is the most essential requirement for life. It provides a variety of purposes such as a source of water supply for drinking, domestic and industrial use, irrigated agriculture, livestock, and mining activities. Evaluating the status of water quality from traditional approaches does not guarantee the whole overview of the water quality situation. Therefore, developing a tool that can convert multiple parameters data into information that is understandable by both technical and non-technical personnel is vital. In this context, the purpose of this paper was to develop, calculate, and apply a water quality index for assessing the suitability (for drinking purposes) of groundwater in the gold mining areas in south-eastern Senegal. The development of this index based on WHO water quality guidelines followed the five standards steps i.e., parameters selection, sub-index formation, parameters weighting and sub-index aggregation and evaluation. Finally, the WQI summarized twelve key water quality parameters into 05 simple terms (excellent, good, medium, poor, and very poor) which is more relevant for reporting to managers and the public in a consistent manner. Thus, it was observed in the study area, that the water quality indexes in artisanal and industrial mining areas are either poor or very poor while in the reference stations (where there are no mining activities) WQI are either good or excellent. This situation was attributed to the effects of mining activities in such zones which contribute to the pollution of groundwater with heavy metals, nitrates, and suspended solids.

关键词： Water Quality Index Groundwater Gold Mining Pollution Heavy Metals

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AC Back Surface Recombination Velocity in n+-p-p+Silicon Solar Cell under Monochromatic Light and Temperature

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Journal of Electromagnetic Analysis and Applications 2021年第5期13卷 67-81页

作者： Mame Faty Mbaye Fall Idrissa Gaye Dianguina Diarisso Gora diop Khady Loum Nafy diop Khalidou Mamadou Sy mor Ndiaye Gregoire Sissoko Ecole Polytechnique de Thiès Thiès Sénégal Institute of Technology University of Thiès Thiès Sénégal Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

Excess minority carrier’s diffusion equation in the base of monofaciale silicon solar cell under frequency modulation of monochromatic illumination is resolved. Using conditions at the base limits involving recombination velocities Sf and Sb, respectively at the junction (n+/p) and back surface (p+/p), the AC expression of the excess minority carriers’ density δ (T, ω) is determined. The AC density of photocurrent Jph (T, ω) is represented versus recombination velocity at the junction for different values of the temperature. The expression of the AC back surface recombination velocity Sb of minority carriers is deduced depending on the frequency of modulation, temperature, the electronic parameters (D (ω)) and the thickness of the base. Bode and Nyquist diagrams are used to analyze it.

关键词： Silicon Solar Cell AC Back Surface Recombination Velocity Temperature Bode and Nyquist Diagrams

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Assessment of Obstetric Evacuations: Received during the Year 2020 at the Touba Ndamatou Public Health Hospital Establishment

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Open Journal of Obstetrics and Gynecology 2022年第6期12卷 528-540页

作者： Babacar Biaye Mouhamadou Wade Daba diop Abdou Karim Diallo mor Ndiaye Alioune diop Awa Ndiaye Mamadou Sene Abdoul Aziz Diouf Mamour Gueye Université Cheikh Anta diop Dakar Senegal

The counter-referral system is particularly important for care during pregnancy, childbirth and the post-partum period as it facilitates access to emergency obstetric and neonatal care. It allows people to access care that is not likely to be provided at the base and to manage certain complications arising in emergency settings. We therefore looked at the evaluation of obstetric evacuations from the Touba Ndamatou public health. Methodology: This was a retrospective study of descriptive and analytical type extending over a period of 12 months from January 1, 2020 to December 31, 2020 at the public hospital health establishment (PHHE) of Touba Ndamatou. Results: One thousand five hundred and sixty (1560) patients evacuated for obstetrical reasons were collected out of a total admission of 5560, i.e., a frequency of 28%. The average age of the patients was 25.54 years. The mean gestation was 3.24 pregnancies. The average parity was 3.04 deliveries. Almost all of our patients (99%) were married. Slightly more than one in two women (53.6%) had performed at least 2 or 3 Prenatal consultations. 80% of parturients had traveled a distance of less than 20 km. 623 patients came by their own means (54.6%). Evacuation was provided by an ambulance in 509 patients, i.e., 44.6%. Arterial hypertension and its complications were the frequent reason for evacuations with approximately one in four patients (26.2%). Only 3.6% of patients had qualified personnel on board being evacuated. In our series, 13 deaths were recorded, i.e., 1.1% of cases. The distance traveled seemed not to influence the future of the mother (p = 0.51). The non-accompaniment of the patient during the evacuation by a medical staff seemed to influence the prognosis of the mother (p = 0.031). Fetal morbidity was higher among evacuees not accompanied by medical personnel. The state of apparent death was observed in the majority of cases in patients received over a distance of more than 20 km. Conclusion: Evacuation

关键词： Evacuation Pregnancy Senegal

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Lamella Silicon Solar Cell under Both Temperature and Magnetic Field: Width Optimum Determination

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Journal of Electromagnetic Analysis and Applications 2020年第4期12卷 43-55页

作者： Dibor Faye Sega Gueye mor Ndiaye Mamadou Lamine Ba Ibrahima Diatta Youssou Traore Masse Samba diop Gora diop Amadou Diao Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

This work deals with determining the optimum thickness of the lamella wafer of silicon solar cell. The (p) base region makes up the bulk of the thickness of the wafer. This thickness has always been a factor limiting the performance of the solar cell, as it produces the maximum amount of electrical charges, contributing to the photocurrent. Determining the thickness of the wafer cannot be only mechanical. It takes into account the internal physical mechanisms of generation-diffusion-recombination of excess minority carriers. They are also influenced by external factors such as temperature and magnetic field. Under these conditions, magneto transport equation is required to be applied on excess minority carrier in lamella base silicon solar cell. It yields maximum diffusion coefficient which result on Lorentz law and Umklapp process. Then from photocurrent, back surface recombination velocity expressions are derived, both maximum diffusion coefficient and thickness dependent. The plot of the back surface recombination calibration curves as function of lamella width, leads to its maximum values, trough intercept points. Lamella optimum width is then obtained, both temperature and magnetic field dependent and expressed in relationships to show the required base thickness in the elaboration process.

关键词： Silicon Vertical Junction Back Surface Recombination Velocity Magnetic Field Temperature Lamella Width

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Back Illuminated N/P/P+Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

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Energy and Power Engineering 2021年第5期13卷 207-220页

作者： Mamadou Sall Dianguina Diarisso Mame Faty Mbaye Fall Gora diop mor Ndiaye Khady Loum Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology Cheikh Anta Diop University Dakar Senegal University Institute of Technology University of Thiès Thiès Sénégal Ecole Polytechnique de Thiès Thiès Sénégal

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

关键词： Bifacial Silicon Solar Cell AC Recombination Velocity-Base Thickness Short-Wavelength

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n+-p-p+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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Compressive Pericardial Teratoma about a Case at Regional Hospital of Saint Louis/Senegal

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Journal of Biosciences and Medicines 2022年第6期10卷 1-7页

作者： Serigne mor Beye Cheikh Ahmadou Bamba Samb Aicha Ndichout Ndeye Rokhaya diop Khadimu Rassoul diop Ansoumana Condé Joseph Salvador Mingou Jean Baptiste Mathieu Sy Adama Kane Departement of Cardiology Regional Hospital of Saint Louis City Senegal Departement of Radiology Regional Hospital of Saint Louis City Senegal

Introduction: Cardiac tumors in children are rare. Most are discovered in children under one year of age. Echocardiography is the basic examination for the screening, it allows their detection from the fetal stage. Observation: She was a 14-year-old patient with no known history of pathology. She was admitted to our department for the exploration of dyspnea and chest pain. At her admission, she had stable hemodynamics. At cardiac auscultation, heart sounds were muffled. The EKG recorded a sinus rhythm, and negative T-waves from V1 to V4. The chest X-ray showed cardiomegaly and a dense, rounded, heterogeneous left hilar opacity, well limited. Echocardiography objected to a great intrapericardial mass in front of the left cardiac cavities compressing part of the left atrium and left ventricle associated with an important pericardial effusion. The CT scan found a heterogeneous pericardial suspected myxoma mass. The pathological examination confirmed pericardial teratoma. The patient had an excision of the pericardial mass. The evolution after surgery was favorable. Conclusion: Intra-pericardial teratomas are benign tumor. Complete removal of the tumor is curative and without recurrence.

关键词： Teratoma Pericardium Saint-Louis

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Profiling Hepatitis B Viral Load: Treatment and Epidemiological Implications in a West African Hospital

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Advances in Infectious Diseases 2022年第4期12卷 703-714页

作者： Papa Silman Diawara mor Ngom Maguette Ndoye Mamadou Wague Gueye Sokhna M. Daffe Nata Dieng Ibrahima Diallo Bécaye Fall Macoura Gadji Moustapha diop Pape Samba Ba Yankhoba diop Federation of Laboratories Principal Hospital of Dakar Dakar Senegal Hematology Department Dakar Principal Hospital Dakar Senegal Hepato-Gastro-Enterology Department Dakar Principal Hospital Dakar Senegal Department of Biological Hematology & Oncology-Hematology (HBOH) National Blood Transfusion Center (CNTS)/FMPOS-UCAD Dakar Senegal Infectious Diseases Department Dakar Principal Hospital Dakar Senegal

Background: Chronic hepatitis B virus (HBV) infection is one of the largest public health problems with nearly 350 million chronic carriers and 500,000 deaths each year. These deaths are most often associated with disease progression to cirrhosis or hepatocellular carcinoma, which some studies have shown is associated with long-term viral replication in chronic carriers. Viral load quantification, a key element of disease management, is expensive and difficult to access. Viral load plays a crucial role in patient classification and treatment initiation. Four years after the implementation of viral load platform, the objective of this study was to assess viral load profile in HBs chronic carriers in a sub-Saharan Hospital and to determine the potential impact of this distribution on preventive and therapeutic strategies against hepatitis B infection. Materials and Method: The study was carried out between April 2016 and October 2020 in the laboratory of the PRINCIPAL Hospital in Dakar. All patients referred for HBV DNA viral load testing following a positive AgHBs test were included. Incomplete medical records were excluded from the study. Only the first quantification test performed on each patient is recorded. DNA extraction was performed with COBAS AmpliPrep (Roche Molecular Systems, Inc., Branchburg, NJ, USA). Amplification was performed using COBAS TaqMan48 (Roche Molecular Systems, Inc., Branchburg, NJ, USA). Data were collected from the laboratory’s computer system and entered into Microsoft Excel (2007). Statistical analyzes were performed using Epi-Info 7 software. Results: A total of 3002 patients, 76.1% (2285/3002) men and 33.9% (717/3002) women, were included in the study. Young adults were most represented among the subjects (23.2%) and (20.1%) in the age groups 25 - 30 and 30 - 35. The majority (52.7%) of patients had viral loads between 20 and 2000 IU. Patients with undetectable viral loads and patients with viral loads below 20 IU comprised 14.6% and

关键词： Hepatitis B Viral Load Senegal Treatment

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Hepatitis B in Senegalese Blood Donors: Low Prevalence after Five Blood Donations?

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Advances in Infectious Diseases 2022年第3期12卷 422-432页

作者： Papa Silman Diawara Mamadou Wague Gueye Sokhna M. Daffe mor Ngom Maguette Ndoye Nata Dieng Ibrahima Diallo Bécaye Fall Macoura Gadji Moustapha diop Pape Samba Ba Yankhoba diop Federation of Laboratories Principal Hospital of Dakar Dakar Senegal Hematology Department Dakar Principal Hospital Dakar Senegal Hepato-Gastro-Enterology Department Dakar Principal Hospital Dakar Senegal Department of Biological Hematology & Oncology—Hematology (HBOH) National Blood Transfusion Center (CNTS)/FMPOS-UCAD Dakar Senegal Infectious Diseases Department Dakar Principal Hospital Dakar Senegal

Background: Over the past two decades, blood transfusion safety has made significant advances in the fight against infectious diseases. However, hepatitis B is still a problem in blood banks due to its high endemicity in Senegal. In this context, we proposed to first determine the prevalence of HBs antigen (HBsAg) in regular and new blood donors. Second, to determine the influence of the number of blood donations on the prevalence of hepatitis B. Materials and Method: We conducted a retrospective transversal study using data from all blood donations received at the Principal Hospital of Dakar Blood bank from July 2007 to December 31, 2021. Hepatitis B testing was carried out with Automaton E411 (Roche Diagnostics). For all donors, information on age, sex, hepatitis B serology, and the number of donations was collected through the lab’s computer system. Data entry and statistical analysis were performed with Epi-info version 7. Results: HBsAg carriers were identified in 4311 primary donors, corresponding to a prevalence of 12.39% (IC 95% = 12.04 - 12.74). The prevalence of the HBsAg antigen was higher in men (12.9%) than in women (6.85%). Men are twice as likely to be infected with HBV as women (OR = 2.00 (IC 95% = 1.85 - 2.17)). The highest prevalence (12.4%) was found in young adults (23 - 29) years old. After 10 donations, the prevalence of the HBs antigen was stable at around 1%. Individuals with a single blood donation and individuals with 2 to 5 blood donations are 9 and 7 times more likely to carry the HBs antigen than regular donors (more than 10 blood donations), respectively. Conclusion: Our results demonstrate the endemic nature of hepatitis B in Senegal. On the other hand, the non-negligible prevalence of the virus in first-time donors reminds us of the need for continuous improvement in donor selection. These first-time donors, particularly young adults, are important indicators of transmission of the virus to the general population. This study also demo

关键词： First-Time Donor Regular Donor Hepatitis B Prevalence

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