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Characterization of Sediment from Ourokessoum, North Cameroon: Morphostructural, Mineralogical, and Physicochemical Properties

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Journal of Geoscience and Environment Protection 2024年第9期12卷 51-76页

作者： Atangana Jacqueline Ntsama Kadaguina Doussana Joseph Roland Atenga Essama Akoa Philémon Rémi Etoundi Bilobi Roland Touna Jean pierre Nguetnkam Department of Earth Sciences Faculty of Science University of Yaound I Yaound Cameroon Department of Earth Sciences Faculty of Science University of Ngaoundere Ngaoundr Cameroon College of Civil Engineering and Architecture China Three Gorges University Yichang China Department of Mining Geology School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon

The present study examines the morphological, physicochemical, and mineralogical specificity of clay sediments in the Hamakoussou Basin with the objective of exploring their potential applications. Field data collection was followed by a series of physicochemical and mineralogical tests on the clay samples. Results show that the clay layers, which range in thickness from 11 - 120 cm, exhibit gray, yellowish, or greenish colors. From a physicochemical perspective, these clay layers are found to be basic with a pH ranging from 8.5 for the higher Hama2 layer to 7.6 for the lower Hama1 layer. The sum of exchangeable bases (S) is medium to high with higher values in the Hama1 layer (53.45 meq/100g) and lower values in the Hama3 layer (17.09 meq/100g). Similarly, the cation exchange capacity (CEC) varies from 62.32 meq/100g for the higher Hama1N4 clay layer to 35.6 meq/100g for the lower Hama1N3 clay layer. Mineralogically, the clay materials are primarily composed of smectites, with illite, kaolinite, calcite, quartz, feldspar, hematite, and goethite also present. This study emphasizes the versatility of clay in various industries and scientific domains. It is known for its impermeability, plasticity, and fossil-preserving capabilities, making it a valuable material for economic, practical, and academic applications.

关键词： Morphostructural Sediments Clay Layers Sedimentary Basin Hamakoussou

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Typology and Agroecology of Agroecosystems in Vegetation Dynamics in the Ecotones of the Mbam and Inoubou

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Open Journal of Forestry 2024年第1期14卷 42-66页

作者： Alex Bruno Dong Etchike Lucie Félicité Temgoua Bertine Tiokeng Marie Caroline Momo Solefack Martin Benoit Ngassoum pierre Marie Mapongmetsem Laboratory of Applied Botany Faculty of Sciences of the University of Dschang Dschang Cameroon Department of Forestry Faculty of Agronomy and Agricultural Sciences University of Dschang Dschang Cameroon National School of Agro-Industrial Sciences of the University of Ngaoundéré Ngaoundéré Cameroon Laboratory of Biodiversity and Sustainable Development of the University of Ngaoundéré Ngaoundéré Cameroon

Agroforestry systems strongly characterize the Cameroonian agrarian landscape. Agroforests are among those structuring the ecotones of Mbam and Inoubou in the Central Cameroon region. Numerous works on agroecosystems of Central and South Cameroon, few have come out contribution of the structure of these traditional systems in the dynamics of the vegetation of these forest-savannah ecotones. The present contribution has the overall objective of demonstrating the structural efficiency of agroforests the dynamics of ecotone vegetation, but also in the conservation of biodiversity. To do this, a participatory analysis was carried out with 56 farmers distributed in the five villages of Makénéné. Botanical inventories supplemented socio-economic household surveys. The data collected was subjected to various analyzes (univariate test, analysis of variance, multivariate test, PCA, CAH). The results reveal that 55.2% of agroforests are less than 15 years old and those with an area greater than 1500 m2 predominate (33%). They are mainly young with generally small surface areas. The horizontal structure reveals that the largest diameter classes are those of [20 - 30 cm[ and [10 - 20 cm[ with a very low rate of basal area. Agroforests with trees over 10 m high are dominant in five villages of Makénéné. Two types of structural profiles characterize the agroforestry flora of the area, namely intensive pluristratified home gardens on savannah and intensive pluristratified agroforests under forest-savannah transition vegetation. Principal Component Analysis (PCA) and Ascending Hierarchical Clustering (HAC) show three Agroforest Clusters each. The PCA distribution reveals that woody biomass (Y) is strongly correlated with tree diameter (DBH) and significantly with height (Cluster 2). The age (AAG) (Cluster 1) of these agroforests, on the other hand, remains independent of the density (DST) of these trees (Cluster 3). The agroforests in the Nyokon, Carrière and Mocksud vil

关键词： Agroforests Agroecosystem Center Cameroon Dynamics Agroecology Typology

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Diatom and Diatomite: Different Focus on Natural Media to Material Science Path

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American Journal of Analytical Chemistry 2024年第1期15卷 1-29页

作者： Secou Sall Vasiliki Papaefthimiou Thierry Dintzer Fabrice Vigneron Eric Brendlé pierre Petit Tom Ferte Saliha Haddoum Sana Labidi Corinne Petit ICPEES UMR-CNRS 7515 Strasbourg University Strasbourg France Adscientis Wittelsheim France ICS CNRS UPR 22 Strasbourg France IPCMS UMR CNRS 7504 Strasbourg University Strasbourg France Ecole Nationale Polytechnique El-Harrach Algeria

Bio-silica issued from diatom, a microalgae, is attracted increasing attention in material science thanks to its peculiar nanoarchitecture and related properties with versatile applications. The present work is a deep analysis on morphological and chemical properties of bio-silica issued from fossil origin (diatomaceous earth) and living one (algal paste). An optimization in purification protocol was performed to obtain multiparous bio-silica from its raw media with keeping its original shape entirely. Multiple characterization methods as scanning electronic microscopy (SEM), infrared spectroscopy, x-ray diffraction (DRX), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption and inverse gas chromatography (IGC), were used to check the purification protocol efficiency as well as to gather accurate information on morphology and chemical composition of diatom material obtained in large amount.

关键词： Diatom Diatomite Bio-Silica Purification Frustule

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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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备用电池的扩展运用

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国外铁道机车与动车 2024年第2期 46-48页

作者： [美]pierre Prenleloup 李梦斐(译) 不详

镍电池最早装载于地铁车辆用作车载备用电源,当车辆需要紧急牵引时,镍电池也可提供动力,相较于安装独立的电池包,其具有很好的成本优势。

关键词： Saft公司 MSX电池莫斯科-2020车队

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Prevalence of Hepatitis C Virus and Associated Risk Factors among Inmates at New Bell Prison, Douala, Cameroon

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Open Journal of Epidemiology 2019年第2期9卷 119-128页

作者： mathurin pierre kowo Firmin Ankouane Andoulo Larry Tangie Ngek Daniel Tchamdeu Sizimboue Antonin Ndjitoyap Ndam Buno Ela Ondo Servais Eloumou Bagnaka Rocard Djanteng Elie-Claude Ndjitoyap Ndam Oudou Njoya Department on Internal Medicine and Specialities Faculty of Medicine and Biomedical Sciences University of Yaoundé I Yaoundé Cameroon Université des Montagnes Banganté Cameroon Faculty of Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon Medical Center New Bell Prison Douala Cameroon

Although a high prevalence of HCV infection in correctional facilities has been well reported in several countries around the world, there has been no such data from Cameroon. The aim of this study was to determine the prevalence and factors associated with viral hepatitis C seropositivity among prisoners incarcerated at the New Bell Central Prison in Douala. From the 2nd to the 27th of July 2018, 940 inmates selected using a systematic random sampling method were interviewed to collect data on sociodemographic status, duration of incarceration, number of incarcerations and risk factors for HCV transmission. Blood samples were collected for screening of anti-HCV antibodies via HEPA-SCAN HCV CARD Test. Positive samples had a confirmatory ELISA test. Data were analysed using EPI DATA 4.***.0.0 software. Statistical significance was set at a p < 0.05. Of the 940 prisoners selected, 94.1% (884) were males. The mean age of the study population was 33.81 ± 10.35 years (extremes: 14 and 74 years). HCV prevalence was 4.4% (40). The use of non-injectable illicit drugs (OR 2.87 95% CI 1.44 - 5.73) (p = 0.002) but not injectable illicit drugs (OR 1.91 95% CI 0.43 - 8.41) (p = 0.42), male homosexuality (OR 17.45 95% CI 7.58 - 40.13) (p < 0.001), sharing of needles (OR 3.45 95% CI 1.59 - 7.83) (p = 0.001), past history of tattooing or piercing (OR 5.94 95% CI 2.80 - 12.16) (p < 0.001) and age ≥ 50 (OR 4.069;95% CI 1.9 - 8.68) (p = 0.003) were significantly associated with HCV antibodies positivity. Inmates in New Bell Central Prison accumulate risk factors for viral hepatitis C, thus contributing to the high prevalence in this setting. Control strategies and programs that reach this particular population should urgently be implemented.

关键词： Prevalence Risks factors Hepatitis C Prisoners

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在不同文化间架起沟通的桥梁

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紫禁城 2024年第3期350卷 120-125页

作者：皮埃尔·雷诺(pierre Rainero) 杨锐(译) 卡地亚

卡地亚,创立于一八四七年的法国巴黎,是皇室御用珠宝商。同时作为一家有着深厚历史和自身文化的国际品牌,卡地亚一直积极推动与支持全球艺术与文化交流,与法国凡尔赛宫和故宫博物馆两座世界级艺术殿堂都保持着长久而密切的关系,多次参... 详细信息

卡地亚,创立于一八四七年的法国巴黎,是皇室御用珠宝商。同时作为一家有着深厚历史和自身文化的国际品牌,卡地亚一直积极推动与支持全球艺术与文化交流,与法国凡尔赛宫和故宫博物馆两座世界级艺术殿堂都保持着长久而密切的关系,多次参与支持展现中西方文化相互影响的展览。

关键词：国际品牌卡地亚凡尔赛宫艺术殿堂艺术与文化中西方文化珠宝商相互影响

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Associated Factors with Early Sexual Intercourse among In-School Adolescents in Brazzaville

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Open Journal of Pediatrics 2024年第5期14卷 898-907页

作者： Aymar pierre Gildas Oko Dumez Ngoma Judicaël Kambourou Eryx Darius Mbou Essie Neli Yvette Ngakengni Lynda Tchidjo Ngamo Georges Marius Moyen Faculty of Health Sciences Marien Ngouabi University of Brazzaville Brazzaville Congo Department of Pediatrics Teaching Hospital Center of Brazzaville Brazzaville Congo

Background: Early sexual intercourse (ESI) is a global public health problem. In Congo, associated factors with ESI have been under-studied. Objective: To analyse factors associated with early sexual intercourse among in-school adolescents in Brazzaville. Method: A cross-sectional analytic study with three-stage random sampling was carried out from March 2 to June 2, 2022 in Brazzaville secondary and high schools. Adolescents in the selected schools were interviewed about their sexual and social behaviour, and their family and school environment. Multivariate analysis using logistic regression was used to identify factors associated with ESI. The significance level of the p-value was set at 5% and the confidence interval at 95%. Results: Of a total of 1100 adolescents surveyed, 800 (72.7%) had ESI, 98% of them were female. The main reason for early initiation of sexual intercourse was curiosity (81.8%). Non-use of condoms and multiple sexual partnerships were noted respectively in 98.7% and 68.7% of adolescents who had experienced ESI. Female gender (p Conclusion: The prevalence of ESI is high, and the factors identified in this study may help to reduce it.

关键词： Associated Factors Early Sex Adolescents Brazzaville

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A Review on Complex System Engineering

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Journal of Systems Science & Complexity 2020年第6期33卷 1755-1784页

作者： PARREND pierre COLLET pierre ECAM Strasbourg-Europe 2Rue de MadridSchiltigheimFrance University of Strasbourg StrasbourgFrance

Complexity is commonly summarized as‘the actions of the whole are more than the sum of the actions of the parts’.Understanding how the coherence emerges from these natural and artificial systems provides a radical shift in the process of thought,and brings huge promises for controlling and fostering this *** authors define the term‘Complex System Engineering’to denote this approach,which aims at transferring the radical insights from Complex System Science to the pragmatic world of engineering,especially in the Computing System Engineering domain.A theoretical framework for Complex System Engineering is built by the morphogenetic engineering framework,which identifies a graduation of models,in growing order of generative *** implementation of Complex System Engineering requires a portfolio of operational solutions:The authors therefore provide a classification of Complex System application approaches to answer this challenge and support the emergence of Complex System Engineers capable of addressing the issues of an ever more connected world.

关键词： Complex networks complex software engineering complex systems design structure matrix emergent engineering evolutionary algorithms organically grown architectures

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Clinical Aspects and Precipitating Factors of Hepatic Encephalopathy Associated with Cirrhosis in a Cameroonian Population

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Open Journal of Gastroenterology 2019年第11期9卷 228-238页

作者： mathurin pierre kowo Edgar Kenne Yimagou Firmin Ankouane Andoulo Antonin Wilson Ndjitoyap Ndam Bonaventure Jemea Servais Albert Fiacre Eloumou Bagnaka Patricia Ouamba Guekam Larissa Pessidjo Eric Tchoumi Leuwat Dominique Noah Noah Oudou Njoya Faculty of Medicine and Biomedical Sciences The University of Yaoundé I Yaoundé Cameroon Research Laboratory on Viral Hepatitis and Health Communication Yaoundé Cameroon Internal Medicine Unit Yaounde University Teaching Hospital Yaoundé Cameroon Gastroenterology Unit Central Hospital Yaoundé Cameroon Faculty of Medicine and Pharmaceutical Sciences The University of Douala Douala Cameroon

Background: Hepatic Encephalopathy (HE), a common complication of cirrhosis, is associated with a pejorative prognosis. This study aims to describe the clinical presentation, precipitating factors and outcome of HE. Methods: This was a cross-sectional multicenter inpatient study in cirrhotic patients admitted for HE in four tertiary hospitals in Yaoundé (Cameroon) from December 2016 to May 2017. The diagnosis of HE was based on West Haven clinical criteria. The diagnosis of cirrhosis was made using clinical and/or biological, endoscopic and/or ultrasonography signs. Results: A total of 53 patients with HE (mean age: 49.9 ± 18.9 years, 35 Males) were included. The frequency of hospital admission for HE was 4.9%. HE grade III was the most common (37.7%), followed by grades I and II (26.4% and 26.4%, respectively). Grade IV was present in 9.4% of cases. According to the Child-Pugh score, 72.1% of the patients were at stage C and 27.9% at stage B. The main precipitating factors found were: constipation (38.5%), hyponatremia (35.9%), hepatocellular carcinoma (HCC) (31.7%), herbal medicine (28.3%), hypokalemia (25.6%), gastrointestinal bleeding (22.6%) and ascitic fluid infection (spontaneous bacterial peritonitis) (13.8%). In 5.7% of cases, no factor was identified. Mortality rate during hospitalization was 45.3% and was significantly associated with stage III (RR = 11.1;95% CI: 1.9 - 64.5;p = 0.003) and IV (RR = 24;95% CI: 1.6 - 40.9;p = 0.01) of HE;Child-Pugh C score (RR = 15.2;95% CI: 1.7 - 30.1;p = 0.003) and hypokalemia (RR = 12.2;95% CI: 1.3 - 19;p = 0.01). Conclusion: HE is a common complication during cirrhosis with a poor prognosis. In the majority of cases, a precipitating factor could be determined.

关键词： Hepatic Encephalopathy Liver Cirrhosis West Haven Criteria Child-Pugh Cameroon

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