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Water Quality Assessment in the Bamoun Plateau, Western-Cameroon: Hydrogeochemical Modelling and Multivariate Statistical Analysis Approach

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Journal of Water Resource and Protection 2021年第2期13卷 112-138页

作者： Zakari Mfonka Amidou Kpoumié Abdou Nasser Ngouh Oumar Farouk Mouncherou daouda nsangou Felaniaina Rakotondrabe Alain Fouépé Takounjou Mounira Zammouri Jules Rémy Ndam Ngoupayou Paul-Désiré Ndjigui Geosciences Natural Resources and Environment Laboratory Department of Earth Sciences Faculty of Science University of Douala Douala Cameroon Geosciences and Sustainable Development Laboratory Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroon National Institute of Cartography Ministry of Scientific Research and Innovation Yaoundé Cameroon Institute for Geological and Mining Research Ministry of Scientific Research and Innovation Yaoundé Cameroon Geosciences of Superficial Formations and Applications Laboratory Department of Earth Sciences Faculty of Science University of Yaoundé I Yaounde Cameroon Center of Water Research and Technologies Geo-Resources Laboratory Faculty of Science University of Tunis El Manar Tunis Tunisia

This study focuses on the geochemical and bacteriological investigation of surface and ground water in the Bamoun plateau (Western-Cameroon). During the period from September 2013 to August 2014, 71 samples were collected from two springs, one borehole, four wells and the Nchi stream for analysis of major elements. In order to obtain the characteristics of the various species of bacteria, 7 samples were selected. The analytical method adopted for this study is the conventional hydrochemical technic and multivariate statistical analysis, coupled with the hydrogeochemical modelling. The results revealed that, water from the zone under study are acidic to basic, very weakly to weakly mineralized. Four types of water were identified: 1) CaMg-HCO3;2) CaMg-Cl-SO4;3) NaCl-SO4 and 4) NaK-HCO3. The major elements were all listed in the World Health Organization guidelines for drinking water quality, except for nitrates which was found at a concentration > 50 mg /l NO-3 in the borehole F401. As for the hydrobiological aspect, the entire sample contained all the bacteriological species except for spring S301 and well P401. According to the hydrogeochemical modelling, the Gibbs model and multivariate statistical tests, the quality of surface and ground water of the Foumban locality is influenced by two important factors: 1) the natural factors characterized by the water-rock interaction, evapotranspiration/crystallization, 2) the anthropogenic factors such as: uncontrolled discharges of liquid and solid effluents of all kinds and without any prior treatment within the ground and the strong urbanization accompanied by lack of sanitation and insufficient care.

关键词： Foumban Surface and Ground Water Water-Rock Interaction Bacteriological Parameters Hierarchical Clustering Analysis Principal Component Analysis

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Influence of Solvent onto Chemical Extraction of America-Type Coconut (Coco nucifera L.) Fbers: Analysis of Physicochemical, Mechanical and Morphological Properties

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Journal of Textile Science and Technology 2024年第3期10卷 64-81页

作者： Delphine Korgai Gandai Zara Haman Djoda Pagore Frederic Memtine Ndong Augustin Abdourhamane nsangou Niraka Blaise Hambate Gomdje Valery National Advanced School of Engineering of Maroua University of Maroua Maroua Cameroon School of Chemical Engineering and Mineral Industries University of Ngaoundere Ngaoundere Cameroon Department of Mechanical Engineering ENSET University of Douala Douala Cameroon

In this study, the natural fibers from Coconuts of the species Coco nucifera L. were Chemically extracted in different solvents such as sodium hydroxide (SH), acetone (AC) and sodium hydroxide-acetone (SHA) for their applications in the textile industries. Structural, morphological and physico-mechanical characterizations such as X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanned electron microscopy (SEM), measurements of density, Young’s modulus, water absorption rate and humidity were evaluated. The XRD and FTIR results show that Coco nucifera L. fibers contains type I cellulose. Mechanical characterizations were also carried out. These results show that by varying the different solvents used, the physico-chemical, mechanical and morphological properties of the fibers change, which implies that the solvent has an influence on the properties of these fibers. The fibers extracted by the sodium hydroxide-acetone mixture have a linear density of 1.636, the percentage of water absorption is 62.428%, the percentage of moisture absorption 9.605% compared to other values in the literature shows that this solvent mixture improves the properties of coconut fibers which contain type I cellulose. The tensile stress is 0.013 GPa, the percentage strain is 49.836% and the Young’s modulus is 0.114 GPa as well as the percentage elongation show that these fibers are elasto-plastic. The values obtained mean that these fibers are suitable for use in textiles.

关键词： Chemical Extraction Cellulose Coco nucifera L. Fibers Elasto-Plastic Textiles

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Post-orogenic transients and relict landforms of the Bafoussam–Mamfe region(West-Cameroon Highland margin)

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Journal of Mountain Science 2022年第8期19卷 2180-2201页

作者： Pascal Landry WABO DEFO Sébastien OWONA Moussa nsangou NGAPNA Christian BALLA ATEBA Christian MWABANUA MUTABI The University of Douala Faculty of ScienceDepartment of Earth SciencesDouala 24157Cameroon The University of Lubumbashi Faculty of ScienceDepartment of GeologyLubumbashi 1825Democratic Republic of Congo

The Bafoussam-Mamfe Region(BMR)belongs to the Western Cameroon Highland margin,an amalgam of transient landscape that evolved from the interactions between tectonics,lithology and climate *** area is tectonically active and shows differential tectonic uplift,contrasting relief,variations in erosion rates,in river incision,and in channel *** order to appraise the BMR tectono-geomorphic evolution,it is essential to understand relationships between internal and external processes and their geomorphic expression at a river basin *** this purpose,we use drainage texture(Dt),stream frequency(Fs),drainage density(Dd),asymmetry factor(AF),the transverse topographic symmetry factor(TTSF),the mean of mountain front sinuosity per unit(Smf),concavity factor(Cf),hypsometry integral(HI)and streamlength gradient index(SL-index)based on 30 m Digital Elevation Models(DEM)and field *** results reveal considerable variations in geology,relief,topography and geomorphic indices values differentiated into three geomorphic units;the Mamfe unit developed on the Mamfe Cretaceous basin,the Nguti and Bafoussam high plateau units build up on the Precambrian granito-gneissic basement overlaid by a volcanic *** stepped(longitudinal and normalized)river profiles and complex hypsometric curves show the lithostructural control of the hydrographic ***(from~1.21 to~4.59),Fs(from~0.26 to~1.91),Dd(from~0.66 to~1.71)geomorphic indice values indicate a part of lithologic control on this morphology while the AF(from~1.16to~24.91),TTSF(from~0.20 to~0.71),Smf(U2=1.11 and U3=1.19),Cf(from~-20.91 to~78.93),HI(from~0.12 to~0.52)and SL-index designate the active tectonics as the main factor that had controlled the morphology of this same *** results pinpoint the combined post-Pan-African to Recent tectonic features,lithologic heterogeneities and the differential erosion processes as main factors that have controlled the BMR *** results highlight how

关键词： Geomorphic indices Tectonic,Lithology Differential erosion Bafoussam-Mamfe Cameroon

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Lithostructural controls in Douala-Buea Region landscape (SW Cameroon margin):Insights from morphometric analysis

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Journal of Mountain Science 2021年第1期18卷 68-87页

作者： Christian BALLA ATEBA Sébastien OWONA Moussa nsangou NGAPNA Véronique MANGA TSIMI DieudonnéMINYEM Joseph MVONDO ONDOA Department of Earth Sciences Faculty of Sciencethe University of DoualaDouala 24157Cameroon Department of Earth Sciences Faculty of Sciencethe University of Yaounde IYaounde 812Cameroon Department of Mines and Quarries Faculty of Mining and Petroleum Industriesthe University of MarouaMaroua 814Cameroon

The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field *** area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea *** Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/*** Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic *** Kumba Unit matches with the southernmost volcanic Western Cameroon High *** Buea Unit corresponds to the Mount Cameroon *** relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to *** drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another *** results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active *** drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the ***,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole

关键词： Morphometric indices Lithological control Structural control Morphological units Douala-Buea Region SW Cameroon margin

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Work Done on a Coherently Driven Quantum System

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Journal of Quantum Information Science 2015年第3期5卷 89-102页

作者： Issofa nsangou Lukong Cornelius Fai Mesoscopic and Multilayer Structures Laboratory Faculty of Science Department of Physics University of Dschang Yaounde Cameroon

We calculate the work done by a Landau-Zener-like dynamical field on two- and three-level quantum system by constructing a quantum power operator. We elaborate a general theory applicable to a wide range of closed-quantum system. We consider the dynamics of the system in the time domain ]-tLZ,tLZ[ (where is the LZ transition time in the sudden limit) where the external pulse changes its sign and its action becomes relevant. The statistical work is evaluated in a period [0,T] where T ≤tLZ. Our results are observed to be in good qualitative agreement with known results.

关键词： Power Operator Statistical Work Landau-Zener Model Level Crossing

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DFT Study of Geometrical and Vibrational Features of Sulfur Containing Amino Acids in Hydrated Media： L-Cysteine and L-Methionine

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Journal of Chemistry and Chemical Engineering 2013年第9期7卷 850-871页

作者： Mama nsangou Jonathan Koyambo-Konzapa Jean Jules Fifen Department of Physical Sciences Higher Teacher's Training College University of Maroua Maroua P.O. Box 46 Cameroon Centre for Atomic Molecular Physics and Quantum Optics Faculty of Science University of Douala Douala P.O. Box 8580Cameroon Department of Physics Faculty of Science University of Ngaoundere Ngaoundere P. O. Box 454 Cameroon

Geometry optimization at the B3LYP/6-31＋＋G＊ level of theory has been undertaken on clusters containing L-Met （L-methionine） or L-Cys （L-cysteine） surrounded by eight water molecules. The comparison of the structural parameters of L-Met and L-Cys with X-ray experimental values is in good agreement within 4.8%. This result shows that the privileged positions of water molecules and the possible hydrogen bonding network formed around the backbone of both AAs （amino acids） are adequate. Subsequent calculations of the harmonic vibrational modes followed by a post-processing treatment enable us to assign the vibrational modes of L-Met and L-Cys surrounded explicitly by eight water molecules. The frequencies of the assigned modes are in good agreement with available IR （infra red） and Raman values within 5%.

关键词： DFT (density functional theory) 6-3 1++G(d) sufur containing amino-acids methionine cysteine explicit solvation.

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DFT Study of the Solvent Effects on the Structure, UV-Vis Spectra and the Antioxidant Activity of Caffeic Acid Phenethyl Ester and Some of Its Derivatives

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Journal of Chemistry and Chemical Engineering 2013年第10期7卷 910-923页

作者： Olivier Holtomo Mama nsangou Jean Jules Fifen Ousmanou Motapon Laboratory of Fundamental Physics Faculty of Science University of Douala Douala P. O. Box 24157 Cameroun Department of Physics Faculty of Science University of Bamenda Bamenda P. O. Box 39 Cameroon Department of Physical Sciences Higher Teacher's Training College University of Maroua Maroua P. O. Box 46 Cameroon Department of Physics Faculty of Science University of Ngaoundere Ngaoundere P. O. Box 454 Cameroon

In this study, the antioxidative （3-methyl-2-butenyl caffeate）, BC efficiency of CAPE （caffeic acid phenethyl ester） and four of its derivatives （MBC （benzoic caffeate）, P3HC （phenethyl-3-hydroxy-cinnamate） and P4HC （phenethyl-4-hydroxy-cinnamate）） are compared in vacuum and in seven solvents. It turned out that the AA （antioxidant activity） in increasing order was P3HC 〈 P4HC 〈 CAPE 〈 MBC. Effects of solvents on the structure and the antioxidant activity of P3HC, P4HC, BC, MBC and CAPE, were studied at 133LYP/6-31G （d, p） then B3LYP/6-3 I＋G （d, p） level of theory using the conductor polarized continuum model methods. Thermodynamically, the authors showed that solvent effects on bond dissociation enthalpy are very weak （within 25 kJ/mol）, but sufficient to influence hydrogen bonds, O-H bond lengths and showed the preferential sites of hydrogen atom cleavage. In addition, solvent notably influences and changes the nature of the scavenging process of ROS （reactive oxygen species）, favouring by this way the HHAT （homolytic hydrogen atom transfer） in non polar solvents, the SPLET （sequential proton loss electron transfer） in polar solvents. Moreover, in chloroform and for the five molecules studied the SET-PT （sequential electron transfer proton transfer） mechanism is preferred compared to the HHAT, because in this solvent the IP is lower than the BDE. TD-DFT calculations revealed that solvent induce a bathochromic effect （red-shift of the wavelengths） coupled to hyperchromic or hypochromic effects.

关键词： CAPE HHAT (homolytic hydrogen atom transfer) SPLET (sequential proton loss electron transfer) SET-PT TD-DFT CPCM B3LYP/6-31+G (d p) B3LYP/6-31+G (d p).

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Thermodynamic Parameters of Central Spin Coupled to an Antiferromagnetic Bath: Path Integral Formalism

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Journal of Applied Mathematics and Physics 2021年第1期9卷 133-145页

作者： Christian Platini Fogang Kuetche nsangou Issofa Mathurin Esouague Ateuafack Lukong Cornelius Fai Research Unity of Condensed Matter Electronics and Signal Processing Department of Physics Faculty of Science University of Dschang Dschang Cameroon Department of Research Development Innovation and Training SpaceKola Yaounde Cameroon Department of Electrical and Electronic Engineering College of Technology University of Buea Buea Cameroon

A path-integral representation of central spin system immersed in an antiferromagnetic environment was investigated. To carry out this study, we made use of the discrete-time propagator method associated with a basic set involving coherent states of Grassmann variables which made it possible to obtain the analytical propagator which is the centerpiece of the study. In this study, we considered that the environment was in the low-temperature and low-excitation limit and was split into 2 subnets that do not interact with each other. The evaluation of our system was made by considering the first neighbor approximation. From the formalism of the path integrals, it is easy to evaluate the partition function and thermodynamic properties followed from an appropriate tracing over Grassmann variables in the imaginary time domain. We show that the energy of the system depends on the number of sites n when β → 0.

关键词： Path Integral Grassmann Algebra Antiferromagnetic Environment Partition Function

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Geochemical characterization of the metasedimentary rocks of the Yaounde Group within the southernmost North Equatorial tectonic belt:insights into geodynamic evolution

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Acta Geochimica 2023年第6期42卷 1017-1034页

作者： Simon Pierre Mbola Ndzana Moise Christian Balla Ateba Germain Marie Monespérance Mboudou Moussa nsangou Ngapna Jean Paul Sep Nlongang Solange Ipan Moise Bessong Jean Bosco Olinga Joseph Mvondo Ondoa Sébastien Owona Paul Bilong Department of Earth Sciences Faculty of ScienceUniversity of YaoundéIP.O.Box:812Yaounde´Cameroon Institute for Geological and Mining Research P.O.Box:4110NlongkakYaounde´Cameroon Department of Earth Sciences Faculty of ScienceUniversity of DoualaP.O.Box:24157DoualaCameroon Department of Geology Faculty of ScienceThe University of BueaP.O.Box:67BueaCameroon

The Proterozoic metasedimentary rocks of the Yaounde Group on the northern edge of the Congo Shield in Central Africa were investigated to understand their provenance and depositional ***,geochemistry,and field evidence helped to subdivide the metasediments into paragneiss,mica schist,chlorite schist,and quartzite which were derived from greywacke,shale,quartz arenite,litharenite *** are immature with some mature samples,moderately weathered and reworked Neo-and Post-Archean *** earth element signatures(Chondrite Eu/Eu^(*)≤1),enrichment of light rare earth elements over the heavy ones,and the La/Sc ratio(>0.7)are compatible with those of the intermediate and felsic sources from the upper continental *** metasediments were deposited in the continental arc setting and have evolved during Proterozoic times according to the Wilson cycle to form the West Gondwana including NE Brazil.

关键词： West Gondwana North Equatorial orogenic belt Yaounde Group Neoproterozoic basin Geochemistry of metasedimentary rocks Geodynamic evolution

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In Vitro Evaluation of the Antifungal Activity of Essential Oils of Thymus vulgaris and Cymbopogon citratus on Some Strains of Sclerotinia sclerotiorum, Agent Responsible for White Rot of Beans

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Agricultural Sciences 2023年第8期14卷 1068-1086页

作者： Serge Bertrand Mboussi Alain Heu Abdou Nourou Kone nsangou Jules Patrice Ngoh Dooh Zachée Ambang Laboratory of Biotechnology University Institute of Technology University of Douala Douala Cameroon Department of Agriculture and Agropastoral Higher Technical Teachers Training College Ebolowa Cameroon Applyied Botanic Research Unit Department of Plant Biology University of Dschang Dschang Cameroon Department of Biological Sciences Faculty of Sciences University of Maroua Maroua Cameroon Biotechnology Laboratory Phytopathology and Microbiology Unit University of Yaoundé I Yaoundé Cameroon

The present work was aimed to the study of the antifungal activity of essential oils of two aromatic plants against three strains of Sclerotinia sclerotiorum responsible for white rot of bean. The two essential oils (EO) of the studied plants: Thymus vulgaris (HET) and Cymbopogon citratrus (HEC), used at different concentrations: C1 (0.75 ml/ml), C2 (1.5 ml/ml) and C3 (3 ml/ml) presented significant inhibitory activities on the three tested fungal strains namely Bia 1, Bia 2, and Njo 2. Two control treatments (T-: containing no antifungal substance and T+: synthetic fungicide) were also used. The antifungal activity here is related to the inhibition of mycelial growth especially with high concentrations of essential oils. Thus, against S. sclerotiorum, HET showed the highest activity comparable to that of T+ (100% inhibition) at all concentrations on the Bia 1 and Bia 2 strains and at concentration C3 on the Njo 2 strain compared to that of HEC, which certainly inhibited the mycelial growth of the different strains considerably (with a maximum of 78.15% on the Njo 2 strain) but not completely. According to their sensitivity, the Bia 2 strain showed a higher sensitivity to essential oils than the others while the Njo 2 strain was more aggressive. On the basis of MIC50 and MIC90 obtained on the Njo 2 strain, the HET turns out to be the most efficient with respective lower values of (1.73 and 23.34 ml/ml) against (4.76 and 26.03 ml/ml) for the HEC. These EO could thus be exploited as biodegradable antifungal substances, likely to control white rot of bean.

关键词： S. sclerotiorum T. vulgaris C. Citratrus Essential Oils Antifungal Activity Inhibition

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