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Identification of major sources controlling groundwater geochemistry in Mount Makabaï in the Far-North of Cameroon(the northernmost part of the Pan-African Belt)

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Acta Geochimica 2023年第2期42卷 266-289页

作者： Merlin Gountiédedzo désirétsozué Amidou Kpoumié Aubin Nzeugang Nzeukou department of Life and Earth Sciences Higher Teachers’Training CollegeUniversity of MarouaP.O.Box.55MarouaCameroon department of Earth Sciences Faculty of ScienceUniversity of MarouaP.O.Box.814MarouaCameroon

The present work focuses on the volcanic basement rock geochemistry of Mount Makabaï(MarouaCameroon city)in relation to groundwater *** were centered on an approach involving an association of several methods such as geological cartography,hydrogeology,and *** rock samples,four disturbed soil samples,three undisturbed soil samples,and 20 samples of groundwater in 10 wells were collected during fieldwork and prepared for laboratory *** exhibit porphyritic,aphyric,and subaphiric *** phenocryst phases are mainly olivine,clinopyroxene,and *** on whole rock major element chemical compositions,the Makabaï samples,plotted on Na_(2)O+K_(2)O versus SiO_(2)diagram,are mugearite,hawaiite,and *** ratio of(MgO+CaO)/(Na_(2)O+K_(2)O)exceeds unity and shows dominance of alkaline Earth metals(MgO:2.99-4.48%;CaO:6.19-9.80%)relatively to alkali metals(Na_(2)O:2.27-4.46%;K_(2)O:2.09-2.51%).Exchangeable base contents are high,mostly represented by Ca and Mg,whose contents vary from 14.6 to 35.28 cmol(+)kg^(-1)and from 3.28 to9.48 cmol(+)kg^(-1)*** CECclayis likewise high,fluctuating between 116.80 and181.38 cmol(+)kg^(-1),values in line with the presence of 2:1 clay minerals represented in the study area by *** the water samples,the Ca2+and Na+contents are generally higher than K^(+)and Mg^(2+),reflecting the relative abundance of Na_(2)O and CaO oxides to K_(2)O and MgO oxides in rocks where different waters were *** waters of Makabaï are acidic to neutral(6.3≤pH≤7.4)and weakly to highly mineralized(110.0≤EC≤1190.0μS/cm).Hydro-geochemical classification by using the Piper diagram revealed two water types:(1)CaMg-HCO_(3)(40%)and(2)CaMg-Cl or CaMg-SO4(60%).The average content of ions in all the analyzed samples was HCO_(3)^(-)>>NO_(3)^(-)>SO_(4)^(2-)>Cl-for anions and Ca^(2+)>>Mg^(2+)>Na^(+)>K^(+)for *** mechanisms governing ionic constituents of groundwater in

关键词： Mount Makabaï-Maroua city Far-North Cameroon Bedrock minerals Groundwater-rock-soil interaction Crystalline basement

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Local Initiatives of Land Rehabilitation in the Sudano-Sahelian Region: Case of <i>Hardé</i>Soils in the Far North Region of Cameroon

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Open Journal of Soil Science 2014年第1期4卷 6-15页

作者： désiré tsozué Bertand Roger Haiwe Jean Louleo Jean Pierre Nghonda department of Environmental Sciences High Institute of the Sahel University of Maroua Maroua Cameroon National Institute of Cartography Yaoundé Cameroon.

Local initiatives of hardé soils rehabilitation in Maroua region have been analyzed. Fieldwork consisted of conducting observations and surveys beside farmers in two study sites, Mizileng and Zokok. Investigations on perception of land degradation signs by farmers show that appearance of encrusted surfaces and loss of vegetation cover are signs more expressed in both study sites. Causes expressed include acceleration of water and wind erosion processes, excessive falling of trees, inappropriate farming techniques and climatic hazards. The main consequences are declining of crop yields, lack of farming land and loss natural pastures. Rehabilitation actions undertaken by local communities surveyed include earth dikes, tillage including cart or hoe ploughing, application of organic matter, integrating farming techniques such as fallowing, association and rotation of crop, and lastly, parking of animals on plots to be rehabilitated. Populations assert in their majority perceive in six months to three years signs of real change on planning plots. Constraints to those rehabilitation actions include material requirements that are mostly not available or accessible to farmers in the study area and access to land. Globally, there is no integration of local knowledge in the implementation of projects and consequences are localized and ephemeral efficiency, but also not conclusive results. Implementation of an innovation in rural areas must take into account the factors of ownership and inscribe in a well-defined trajectory. This trajectory must be dynamic and reflexive where local knowledge will cope with expert knowledge to ensure impact and sustainability of innovation.

关键词： Local Initiative Hardé Soils Land degradation Rehabilitation Cameroon

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Ethics of Human Resources Management in the Cameroonian Health System, Medical Nomadism and the Ineffectiveness of the Fight against High Blood Pressure

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Health 2024年第1期16卷 9-21页

作者： Jean Ndibi Abanda Anicet Onana Akoa désiré Tchoffo Ulrich dama Pierre Yassa Yoniene Faculty of Health Sciences University of Lisala (CIREP-UNILIS) Lisala Democratic Republic of the Congo National Order of Medical and Sanitary Professions Yaounde Cameroon School of Health Sciences Catholic University of Central Africa Yaounde Cameroon World Health Organization Maroua Cameroon Faculty of Medicine University Simon Kimbangu Kinshasa Democratic Republic of the Congo

Context/objectives: The fight against Chronic Non-Communicable diseases (NCds) is a long-term undertaking, which requires available, motivated and well-managed human resources (HR). The administrative management of skills on both qualitative and quantitative levels is one of the essential functions of a health system. To better implement policies of fight against High Blood Pressure (HBP) and other chronic diseases, it is important to establish strategies to retain health personnel. This loyalty requires favorable working conditions and consideration of the contribution-reward couple. Good working conditions are likely to reduce the phenomenon of medical nomadism;conversely, poor HR management can contribute to their exodus towards exotic “green pastures”, thus leading to an additional crisis in the Cameroonian health system. The fight against HBP is a complex, multifaceted and multifactorial reality that requires appropriate management model for all types of resources mainly HR. The main objective of this research is to show the impact of poor management of human resources in Cameroon health system on medical nomadism and the ineffectiveness of the fight against High Blood Pressure. Method: A cross-sectional descriptive survey among five hundred (500) health facilities in the center region of Cameroon has been conducted. A stratified probabilistic technique has been used, and the number of health facilities to be surveyed has been determined using the “sample size estimation table” of depelteau. The physical questionnaires have been printed and then distributed to data collectors. After data collection, the latter were grouped during processing in Excel sheets. The Chi-square test was used for data with a qualitative value and that of Kolmogorov-Sminorf for data with a quantitative value to assess the normality and reliability of data. The Crochach’s Alpha reliability test allowed us to have a summary of the means and variances and then to search for intragroup cor

关键词： Ethics Human Resources Management Cameroonian Health System Medical Nomadism Ineffectiveness High Blood Pressure

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Effect of Size and Initial Water Content on the Effective diffusion Coefficient during Convective drying of Sweet Potato Cut into Cubic and Cylindrical Shapes

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Journal of Materials Science and Chemical Engineering 2024年第6期12卷 71-82页

作者： Ibrango Abdoul Salam Ouoba Kondia Honoré Bama désiré Traoré Yssa Zongo Karim Ouedraogo Salifou Laboratoire de Matriaux de lHliophysique et Environnement (La.M.H.E.) Unit de Formation et de Recherche en Sciences. Exactes et Appliques (UFR/SEA) Universit Nazi BONI de Bobo-Dioulasso Bobo-Dioulasso Burkina Faso

In this article, we investigated the influence of size and initial water content on the effective diffusion coefficient of sweet potatoes samples cut into cubic and cylindrical shapes. The sizes of the cubic samples are 0.5, 1, 1.5, 1.75, 2, 2.5 and 3 cm edge with a respective initial water content of 2.7, 3.76, 3.48, 2.68, 3.28, 2.17 and 2.29 kg/kgms. For cylindrical samples, the radius is set at 0.5 cm and sample heights are 1, 1.5, 2, 2.5, 3, 3.5 and 4 cm with respective water contents of 2.2, 3.19, 2.85, 2.1, 2.17, 2.39 and 2.03 kg/kgms. The effective diffusion coefficients of cubic samples are of the order of 10−10 and 10−9 m2∙s−1 grew with sample edge. As for the cylindrical samples, the effective diffusion coefficients were of the order of 10−9 m2∙s−1 and there was no linear correlation between cylinder height and their effective diffusion coefficient. As for the examination of the initial water content on the effective diffusion coefficient, it turned out that the initial water content had no influence on the effective diffusion coefficient of the sweet potato samples.

关键词： Effective diffusion Coefficient Initial Water Content Sweet Potato Cubic Cylindrical

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Pattern of Potential Laboratory Markers for COVId-19 in Eastern Sudan

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Open Journal of Epidemiology 2024年第3期14卷 508-516页

作者： Nazik sir El Khatim Bakhit Suliman Mohammed Omer Abaker Gibreel Mervat sir El Khatim Bakhit Suliman department of Clinical Chemistry College of Medical Laboratory Science Eastern Sudan University of Medical Science and Technology Port Sudan Sudan dean of the Secretariat of Academic Affairs Port Sudan Ahlia University Port Sudan Sudan Cardiology department Cath Lab Fujaira Hospital Fujaira UAE

Background: Coronavirus disease 2019 (COVId-19) is a recent global health crisis. One of the major issues of COVId-19 is its unpredictable manifestations and serious outcomes. Many hematological parameters are thought to change dramatically during the course of the disease. These include white blood cells, red blood cells, and platelets. This study aimed at evaluating certain laboratory results;peripheral blood lymphopenia, relative neutrophilia, high neutrophil-lymphocyte ratio, and elevated C-reactive protein as potential laboratory markers of COVId-19 in Eastern Sudanese patients. Methods: We, retrospectively, aimed at the evaluation of peripheral blood leucocytes count, neutrophil-lymphocyte ratio NLR and C-reactive protein (CRP) levels in confirmed COVId-19 eastern Sudanese patients during the course of the disease. Results: The mean total leucocytes count, % neutrophils count, absolute neutrophils count and C-reactive protein (CRP) were significantly higher (P. value = 0.000) in COVId-19 patients than in the control group while the mean % lymphocytes count and % mixed cells count were found to be significantly lower in COVId-19 patients than in the control group (P. value 0.000). Conclusion: Peripheral blood leucocyte alterations (simultaneous presence of lymphopenia, relative neutrophilia and high neutrophil lymphocyte ratio (NLR) along with elevated CRP levels may be valuable biomarkers associated with COVId-19 in Port Sudan city, Red Sea state, Sudan. These markers might be important in prediction, inspection of disease progression and prognosis.

关键词： COVId-19 SARS 2 WBCs CRP NLR Port Sudan

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Experimental Assessment of the Thermal Performance of Two Corrugated Metal Roofs

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Open Journal of Applied Sciences 2024年第9期14卷 2374-2392页

作者： Kouamé Jean-Louis Kouakou Ekoun Paul Magloire Koffi Bi Tra désiré Zinla Prosper Gbaha Laboratoire des Procds Industriels de Synthse de lEnvironnement et des Energies Nouvelles Institut National Polytechnique Felix Houphout-Boigny Yamoussoukro Cte dIvoire

This experimental study is a contribution to the search for solutions to reduce indoor heat gain through sheet metal roofing in hot weather. It has evaluated the thermal impact of two different sheet metal roofs inside of two identical test buildings in sunny weather and cloudy weather conditions. Test building 1 has a single sheet corrugated roof and the building 2 is covered with roof made from top to bottom with corrugated sheet metal, a 12 mm thick serpentine copper tube in which water is circulated, a sheet of aluminium foil acting as a heat reflector, a 4 cm thick polystyrene panel and a 1.5 cm thick plywood. A maximum reduction of 15.1˚C in the temperature of the inner face of the test Building 2 roof was obtained comparatively to the temperature of the inner face of the test Building 1 roof consisting of a single sheet of metal at the warmest hours. In addition, the simple corrugated sheet metal roof of the test building generates high and varied temperatures inside the building. Whereas the proposed heat recovery roof favours low and relatively uniform temperatures inside the building. The proposed sheet metal roof construction technique is very effective in reducing the heat gain through the roof considerably;thus improving the thermal comfort inside sheet metal roofed dwellings. Hot water has been produced by recovering heat from the metal sheet of the roof of test building 2. The temperature of the hot water produced reached of 39˚C. This study could be also an alternative for the reduction of energy consumption due to the use of mechanical means for cooling of sheet metal roofed houses and the reduction of the use of fossil fuels for domestic hot water production.

关键词： Metal Roof Corrugated Time Lag decrement Factor

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Coordination of Regulation devices for damping Power Oscillations in a dynamic disturbance Context: A Fuzzy Logic-Based Approach Applied to the Electrical Grid of the Republic of Congo

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Journal of Power and Energy Engineering 2024年第1期12卷 44-60页

作者： Mavie Grace Mimiesse davy Rostand Souamy Loembe Smaël Magloire Elombo Motoula désiré Lilongo-Boyenga Laboratoire du Génie É lectrique et &#201lectronique &#201cole Nationale Supérieure Polytechnique Université Marien NGOUABI Brazzaville Congo Institut Supérieur d’Architecture Urbanisme Batiment et Travaux Punlics Université Dénis SASSOU-N’GUESSO Kintelé Congo

This article presents a fuzzy logic-based approach to coordinate the control devices of the power system, such as Power System Stabilizers (PSS) and Static Synchronous Compensators (STATCOM), to damp power oscillations caused by dynamic disturbances. At first, we used the Lyapunov method to study the dynamic stability of the power grid in the Republic of Congo. This method allowed us to analyze the eigenvalues of the state variable matrix and highlight the eigenvalues in the complex plane. Secondly, we proposed a fuzzy logic-based controller to account for uncertainties existing near the thresholds. The inputs to this controller are the generator speed and generator rotor angle. We demonstrated the effectiveness and feasibility of this fuzzy control by applying it to the power grid of the Republic of Congo, with three power stabilizers and two STATCOMs. .

关键词： Fuzzy Logic STATCOM PSS Lyapunov Republic of Congo

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Life Cycle Assessment of Cashew Nutshell Briquettes Produced in Côte d’Ivoire

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Open Journal of Applied Sciences 2024年第9期14卷 2411-2430页

作者： Bi Tra désiré Zinla Ekoun Paul Magloire Koffi Kamenan Blaise Koua Kpeusseu Angeline Kouambla Epse Yeo Prosper Gbaha Laboratoire des Procds Industriels de Synthse de lEnvironnement et des Energies Nouvelles Institut National Polytechnique Felix Houphout-Boigny Yamoussoukro Cte dIvoire Laboratoire des Sciences de la Matire de lEnvironnement et de lEnergie Solaire Unit de Formation et de Recherche des Sciences des Structures de la Matire et de Technologie Universit Felix Houphout-Boigny Abidjan Cte dIvoire

Now one of the main cash crops in Côte d’Ivoire, the cashew tree feeds an entire industrial sector based on the processing of its fruit. This processing generates a large volume of waste, consisting of cashew nutshells, the management of which poses environmental problems. With the aim of replacing charcoal and firewood with more environmentally friendly fuels, several studies are currently being carried out into the optimal use of cashew shells in fuel briquettes. To assess the environmental sustainability of these briquettes, this study calculates the environmental impacts associated with their life cycle, compares them with those of charcoal and firewood, and identifies the processes that contribute most to environmental pollution, with a view to improving them. Analysis of the results showed that cashew nutshell briquettes emit a range of pollutants over their life cycle that damage the environment and are responsible for the 7 impact categories considered: acidification, eutrophication, freshwater aquatic ecotoxicity, global warming, human toxicity, photochemical oxidation and terrestrial ecotoxicity potential. However, they are more environmentally friendly than charcoal and firewood for 5 impact categories: freshwater aquatic ecotoxicity, global warming, human toxicity, photochemical oxidation and terrestrial ecotoxicity potential. The 3 elementary processes, i.e. transport of biomass raw materials, production, and combustion of briquettes, emit pollutants that contribute most to the creation of environmental impact categories. The most relevant pollutants are nitrogen oxides (NOx), sulphur oxides (SOx) and particulate matter (PM).

关键词： LCA Briquettes Cashew Nutshell Biomass Environmental Impact

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Mobility of Major and Trace Elements during the Bauxitization Processes in Ngaoundal Area (Adamawa Cameroon): Implication on Mining Perspectives

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Open Journal of Geology 2024年第1期14卷 81-100页

作者： André Sini Harouna Boukari Ondoa Augustin désiré Balla djetenbe Beral Salomon Wangmené Awé Simon djakba Basga Jean Pierre Nguetnkam department of Mining Engineering School of Geology and Mining Engineering University of Ngaoundere Ngaoundere Cameroon department of Mining Engineering and Environment School of Mining Industry and Geology University of Abdou-Moumouni Niamey Niger department of Earth Sciences Faculty of Science University of Ngaoundere Ngaoundere Cameroon department of Mining Engineering Saint Jerome Polytechnic Saint Jerome Catholic University Institute of Douala Douala Cameroon Institute of Agricultural Research for development (IRAd) Garoua Cameroon

This study was focused to assess major and trace elements in bauxitic duricrusts from Ngaoundal and its surroundings in order to establish their mining interest. To this end, fieldworks, mineralogical and geochemical analyses were carried out. Four facies of duricrust were identified and characterized from the summit to the top of the slope of the Ngaoundal mountain: scoriaceous, pisolitic, nodular and massive. Mineralogical and geochemical analyses performed on 16 samples, revealed a significant concentration of Al2O3 mainly in the scoriaceous facies (over 45% in grade), moderate in Fe2O3 (averaging 23.69%) and SiO2 (averaging 21.7%). Trace elements were generally low, excluding Cr (421 ppm on average), Zr (327 ppm on average and V (213 ppm on average). In addition, the limited quantities of alkalis (Na2O, K2O) and alkaline earths metals (MgO, CaO) coupled with the very high values of Chemical Index of Alteration (CIA) and Mineralogical Index of Alteration (MIA), (more than 99%) attest to the intense weathering of the studied materials. Allitization and monosiallitization constituted the crystallochemical phenomena that have led to the development of bauxitic minerals. More than 90% of gibbsite in scoriaceous facies, 52.21% - 76.01% of kaolinite in pisolitic facies and more than 40% of hematite in nodular facies were quantified. The relationships between the constitutive components indicated their interdependency during the bauxitization phenomenon. The mineralogical and geochemical properties highlighted the mining interest of the studied duricrusts to be valorized.

关键词： duricrust Bauxitization Phenomenon Mineralogical and Geochemical Characterization Major and Trace Elements Mining Potential

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Lighting up aggregate emission of perylene diimide by leveraging polymerization-mediated through-space charge transfer and π-π stacking

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Science China Chemistry 2024年

作者： Suiying Ye désirée Füglistaller Tian Tian Anjay Manian Sudhir Kumar Celine Nardo Andrew J.Christofferson Salvy P.Russo Chih-Jen Shih Jean-Christophe Leroux Yinyin Bao Institute of Pharmaceutical Sciences Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 3 Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences ETH Zurich Vladimir-Prelog-Weg 1-5 ARC Centre of Excellence in Exciton Science School of Science RMIT University School of Science STEM College RMIT University

The molecular engineering of fluorescent organic/polymeric materials, specifically those emitting in the deep red to near-infrared spectrum, is vital for advancements in optoelectronics and biomedicine. Perylene diimide(PdI), a well-known fluorescent scaffold, offers high thermal and photophysical stability but suffers from fluorescence quenching in solid or aggregate states due to intense π-π interactions. To mitigate this, simple and versatile methods for strong PdI aggregate emission without extensive synthetic demands are highly desirable but still lacking. Here, we report a straightforward strategy to enhance the solid-state emission of PdI by introducing certain degree of through-space charge transfer(TSCT) via controlled radical polymerization,which can efficiently distort the typical face-to-face PdI stacking, enabling greatly enhanced deep red emission. This is achieved by growing electron-donating star-shape styrenic(co)polymers from a multidirectional electron-accepting PdI initiator. The incorporation of polycyclic aromatic monomers further shifted the emission into the near-infrared region, albeit with a reduced intensity. Overall, the emission of the PdI-based TSCT polymers can be systematically manipulated by leveraging the balance between PdI stacking and the TSCT degree, as confirmed by both experimental study and theoretical calculations. Our approach circumvents complex synthetic procedures, offering highly emissive materials with large Stokes shifts and showing broad potential for optoelectronic technology.

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