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Petrology of Spinel-Lherzolite Xenoliths from Mazéléand Others Northen Xenoliths Localities of Cameroon Volcanic Line: Exchange Reactions and Equilibrium State

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Open Journal of Geology 2024年第5期14卷 629-653页

作者： Nguihdama Dagwai kamgang pierre Mbowou Gbambié Isaac Bertrand Chazot Gilles Ngounouno Ismaïla Department of Life and Earth Sciences Higher Teachers&#8217 Training College University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Science University of Yaound&#233 1 Yaound&#233 Cameroon Department of Mineral Prospecting and Exploration Technologies School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Ocean Geosciences Laboratory European University Institute of the Sea (IUEM) Brest France

The alkaline volcanism of the Cameroon Volcanic Line in its northern domain has raised many fresh enclaves of peridotites. The samples selected come from five (05) different localities (Liri, in the plateau of Kapsiki, Mazélé in the NE of Ngaoundéré, Tello and Ganguiré in the SE of Ngaoundéré and Likok, locality located in the west of Ngaoundé). The peridotite enclaves of the above localities show restricted mineralogical variation. Most are four-phase spinel-lherzolites, indicating that this is the main lithology that forms the lithospheric mantle below the shallow zone. No traces of garnet or primary plagioclase were detected, which strongly limits the depth range from which the rock fragments were sampled. The textures and the wide equilibrium temperatures (884˚C - 1115˚C) indicate also entrainment of lherzolite xenoliths from shallow depths within the lithosphere and the presence of mantle diapirism. The exchange reactions and equilibrium state established in this work make it possible to characterize the chemical composition of the upper mantle of each region and test the equilibrium state of the phases between them. Variations of major oxides and incompatible elemental concentrations in clinopyroxene indicate a primary control by partial melting. The absence of typical “metasomatic” minerals, low equilibration temperatures and enriched LREE patterns indicate that the upper mantle below septentrional crust of Cameroun underwent an event of cryptic metasomatic enrichment prior to partial melting. The distinctive chemical features, LREE enrichment, strong U, Ce and Pr, depletion relative to Ba, Nb, La, Pb, and T, fractionation of Zr and Hf and therefore ligh high Zr/Hf ratio, low La/Yb, Nb/La and Ti/Eu are all results of interaction of refractory peridotite residues with carbonatite melts.

关键词： Xenoliths Upper Mantle Northern Region Adamawa Cameroon Volcanic Line Exchange Reaction

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Pure forsterite in Nyiragongo lavas: evidence for subsolidus oxidation of volcanic rocks

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Acta Geochimica 2022年第1期41卷 12-23页

作者： Innocent Badriyo Agama Gilles Chazot pierre kamgang Departement Des Sciences de la Terre Faculte Des SciencesUniversitede YaoundeIB.P.812YaoundeCameroon Laboratoire Geosciences Ocean Institut Universitaire Europe´en de la MerUniversitede Brest(UBO)UMR 6538Place Copernic29280 PlouzaneFrance Observatoire Volcanologique de Goma B.P.484GomaNord-KivuDemocratic Republic of the Congo

Some volcanic rocks from Nyiragongo volcano in the Democratic Republic of Congo contain highly oxidized olivine *** olivines crystals are made of two phases,dark olivine on backscattered electron images of pure forsterite composition and grey Mg-poor areas made of olivine and iron-rich *** of the initial composition confirms that they are primary olivine with late separation of two different olivine *** forsterite is enriched in SiO_(2) but contains lower amounts of CaO than Fe-rich areas,in agreement with expected partitioning of these elements related to the composition of the ***-rich oxides formed around or inside the olivine crystals during the separation process and confirm a highly oxidized environment during their *** propose that this separation occurred during subsolidus recrystallization under high fO_(2) conditions of the olivine crystals after cooling of the volcanic *** provides evidences for circulation of iron-rich fluids or gas inducing deuteritic processes occurring in the large volcanic cone of the Nyiragongo,in relation with the presence of a shallow magma chamber connected to a large and permanent lava lake.

关键词： Nyiragongo Olivine Forsterite Oxidation

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The Bafoussam volcanic series:origin and evolution of the volcanism along the Cameroon volcanic line

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Acta Geochimica 2022年第6期41卷 1049-1068页

作者： Philippe Essomba Gilles Chazot Nicaise Blaise Tchuimegnie Ngongang Arnaud Agranier pierre kamgang HervéBellon Philippe Nonnotte pierre Wotchoko Innocent Badriyo Département Des Sciences de La Terre FacultéDes SciencesUniversitéde YaoundéIB.P.812YaoundéCameroun Geo-Ocean CNRSIfremerUMR6538Univ Brest29280PlouzaneFrance Département Des Sciences de La Terre FacultéDes SciencesUniversitéde DoualaDoualaCameroun Department of Geology Higher Teacher Training CollegeUniversity of BamendaBambiliBamendaCameroon Département de Séismologie et Géologie Observatoire Volcanologique de Goma-RDCGomaRépublique Démocratique du Congo

The Bafoussam area in western Cameroon is part of the central Cameroon Volcanic Ligne(CVL).This study presents the mineralogy,major and trace element compositions,Sr-Pb-Hf isotopes,and new K-Ar geochronological data about mafic and felsic volcanic *** rocks belong to two different series:A transitional series made of basalts,basaltic andesite,and trachytes and an alkaline mafic series with basalts,hawaiites,and *** age data show that the transitional series belongs to the oldest part of the CVL and was emplaced between 47 and 35 *** alkaline volcanism is younger,with ages ranging from10 to 4.5 *** evolution in both series is accomplished through a fractional crystallization process,with the removal of olivine and clinopyroxene,while plagioclase does not seem to be a major crystallizing *** the samples are enriched in incompatible trace elements,but the rocks from the alkaline series have more fractionated REE patterns and high Nb content compared to the transitional mafic *** lavas have lower initial^(87)Sr/^(86)Sr and higher^(176)Hf/^(177)Hf and Pb isotopic ratios than the transitional *** La/Nb and high^(87)Sr/^(86)Sriratio are among chemical characteristics that show that some samples from the transitional series have interacted with a crustal component during their evolution in the *** cannot be used for discussing the mantle source of the volcanic rocks from this *** elements show that primary magmas for both series formed in a garnet-bearing mantle source,with higher partial melting degrees(3-5%)for the transitional magmas than for the alkaline magmas(<2.5%).Combining trace elements and isotopic ratios,we show that the Bafoussam lavas formed from two different mantle *** magmas formed from a pyroxenite-bearing enriched mantle with low Pb isotopic *** mantle source is present in all the oldest lavas from the *** magmas formed from an HIMU-like mantle sourc

关键词： Cameroon Volcanic Line Bafoussam Mafic volcanic rocks Felsic volcanic rocks Mantle source

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Climate-influenced vector-borne diseases in Africa: a call to empower the next generation of African researchers for sustainable solutions

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贫困所致传染病(英文) 2024年第2期13卷 1-10页

作者： Obame-Nkoghe Judica?l Agossou Adjoavi Esse Mboowa Gerald kamgang Basile Caminade Cyril Duke Dawn C. Githeko Andrew Karanja Ogega Obed M. Elloué Nestor Engone Sarr Fatou Bintou Nkoghe Dieudonné Kengne pierre Ndam Nicaise T. Paupy Christophe Bockarie Moses Otomo Patricks Voua Molecular and Cellular Biology Laboratory (LabMC) Biology Department University of Science and Technology of Masuku BP Franceville Gabon Ecology and Health Research Unit Interdisciplinary Center for Medical Research of Franceville BP Franceville Gabon Department of Zoology and Entomology Faculty of Natural and Agricultural Sciences University of the Free State Private Bag x13 Phuthaditjhaba Republic of South Africa Laboratory of Pharmacology and Improved Traditional Medicines Department of Animal Physiology Faculty of Science and Technology University of Abomey-Calavi BP Cotonou Benin The African Center of Excellence in Bioinformatics and Data-Intensive Sciences Infectious Diseases Institute College of Health Sciences Makerere University P. O Box Kampala Uganda Africa Centers for Disease Control and Prevention African Union Commission Roosevelt Street P.O. Box WKAddis Ababa Ethiopia Centre for Research in Infectious Diseases P.O. Box Yaoundé Cameroon Earth System Physics Department The Abdus Salam International Centre for Theoretical Physics Trieste Italy Africa Research Excellence Fund Charterhouse Street London EC1MHR UK Community Health Support Program P.O. Box Kisumu Kenya The African Academy of Sciences Nairobi Kenya Center for Phylosophical Studies and Research (CERP) Omar Bongo University (UOB) BP Libreville Gabon UMRED Health Training and Research Unit University of Iba Der Thiam of Thiès BP Thiès Senegal National Parasitic Diseases Control Program Ministry of Health Libreville Gabon MIVEGEC Univ. Montpellier CNRS IRD Montpellier France MERIT IRD Paris Cité University Paris France Department of Parasitology Noguchi Memorial Institute for Medical Research University of Ghana LG Accra Ghana School of Community Health Sciences Njala University Bo Sierra Leone

We look at the link between climate change and vector-borne diseases in low- and middle-income countries in Africa. The large endemicity and escalating threat of diseases such as malaria and arboviral diseases, intensified by climate change, disproportionately affects vulnerable communities globally. We highlight the urgency of prioritizing research and development, advocating for robust scientific inquiry to promote adaptation strategies, and the vital role that the next generation of African research leaders will play in addressing these challenges. Despite significant challenges such as funding shortages within countries, various pan-African-oriented funding bodies such as the African Academy of Sciences, the Africa Research Excellence Fund, the Wellcome Trust, the U.S. National Institutes of Health, and the Bill and Melinda Gates Foundation as well as initiatives such as the African Research Initiative for Scientific Excellence and the Pan-African Mosquito Control Association, have empowered (or are empowering) these researchers by supporting capacity building activities, including continental and global networking, skill development, mentoring, and African-led research. This article underscores the urgency of increased national investment in research, proposing the establishment of research government agencies to drive evidence-based interventions. Collaboration between governments and scientific communities, sustained by pan-African funding bodies, is crucial. Through these efforts, African nations are likely to enhance the resilience and adaptive capacity of their systems and communities by navigating these challenges effectively, fostering scientific excellence and implementing transformative solutions against climate-sensitive vector-borne diseases.

关键词： Climate change Vector-borne diseases Africa Environmental justice Research and development Pan-African funding initiatives

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Cavity optomechanics with directionally squeezed light

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 181-182页

作者： pierre Meystre Department of Physics and College of Optical Sciences University of ArizonaTucson 85721USA

It is well understood that the Heisenberg uncertainty principle imposes a fundamental limit on the precision of quantum *** way to get around this difficulty is to exploit quantum states that minimize the uncertainty on the observable of interest,increasing in the process the uncertainty on the conjugate *** states of the electromagnetic field.

关键词： field observable quantum

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Spinel-Bearing Lherzolite Xenoliths from Hossere Garba(Likok,Adamawa-Cameroon):Mineral Compositions and Geothermobarometric Implications

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International Journal of Geosciences 2014年第12期5卷 1435-1444页

作者： Nguihdama Dagwai Chazot Gilles kamgang pierre Mbowou Gbambie Isaac Bertrand Ngounouno Ismaila Ecole Normale Supérieure Universite de MarouaMarouaCameroun Universite Europeenne de Bretagne BrestFrance Departement des sciences de la Terre Faculte de SciencesUniversite de Yaounde IYaoundeCameroun Ecole de Géologie et d’Exploitation Miniere(EGEM) Departement de Mines et de la GeologieUniversite de NgaoundereMeigangaCameroun

Spinel-bearing lherzolite xenoliths from the Hossere Garba (1272 m.a.s.l) volcano on the Adamawa Plateau, is located in Likok village, at about 35 km to WSW of Ngaoundere. These xenoliths (~11 cm size) have been sampled into the host basaltic lava flows from the NE flank of the Hossere Garba volcano. These xenoliths characterized by porphyroclastic texture consisted of olivine (~55 vol.%), orthopyroxene (~19 vol.%) and clinopyroxene (~21 vol.%) crystals. Spinel crystals (~5 vol.%) are red brown and interstitial between the crystals of olivine and pyroxenes. CaO contents are low (<0.08 wt%) in olivine and similar to those estimated (CaO: 0.05 - 0.1 wt%) for the mantle origin. The values of AlVI/AlIV ratio range between 1.1 and 1.3 for the Cr-diopside crystals from Hossere Garba xenoliths. The constant value of the volumes V(Cell) and V(M1) for clinopyroxene compositions, indicates the similar pressures. Hossere Garba represents a residual sequence issued from partial melting of a mantle source. Similar compositions have been recorded in minerals of ultramafic xenoliths from other ultramafic xenoliths domains of the Cameroon Line and the Adamawa Plateau.

关键词： Xenoliths lherzolite Geothermobarometry Likok Adamawa

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Decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes:Statistical molecular fragmentation model and DFT calculations

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Journal of Environmental Sciences 2024年第1期135卷 433-448页

作者： Xiang Meng pierre Désesquelles Lejin Xu Department of Nuclear Engineering and Technology School of Energy and Power EngineeringHuazhong University of Science&TechnologyWuhan 430074China CNRS Laboratoire de Physique des Gaz et des PlasmasUniversitéParis-SaclayOrsay 91405France State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The treatment and disposal of radioactive waste are presently facing great *** ion exchange resins have become a focus of attention due to their high production and serious environmental *** this paper,a simplified model of cationic exchange resin is proposed,and the degradation processes of cationic resin monomer initiated by hydroxyl radicals(·OH)are clarified by combining statistical molecular fragmentation(SMF)model and density functional theory(DFT)*** prediction of active sites indicates that the S-O bonds and the C-S bond of the sulfonic group are more likely to react during the *** meta-position of the sulfonic group on the benzene ring is the most active site,and the benzene ring without the sulfonic group has a certain *** C11-C14 and C17-C20 bonds,on the carbon skeleton,are the most easily *** is also found that dihydroxy addition and elimination reactions play a major role in the process of desulfonation,carbon skeleton cleavage and benzene ring *** decomposition mechanisms found through the combination of physical models and chemical calculations,provide theoretical guidance for the treatment of complex polycyclic aromatic hydrocarbons.

关键词： Cationic exchange resin Statistical molecular fragmentation model Density functional theory Hydroxyl radical Decomposition mechanism

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Study of Multi-Origin Hazards and Assessment of Associated Risks in the Lefo Caldera (Bamenda Volcano, Cameroon Line)

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International Journal of Geosciences 2014年第11期5卷 1300-1314页

作者： Zangmo Tefogoum Ghislain Nkouathio David Guimolaire Kagou Dongmo Armand Gountie Dedzo Merlin kamgang pierre Department of Earth Sciences Faculty of Sciences University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Sciences University of Dschang Dschang Cameroon Department of Life and Earth Science High Teacher Training College University of Maroua Maroua Cameroon Department of Earth Sciences Faculty of Science University of Yaounde 1 Yaounde Cameroon

The Bamenda Volcano (BV) (2621 m) is a stratovolcano situated in the Cameroon Line (CL). BV includes Mount Lefo (2534 m) which is situated on its southern slopes and contains one elliptical caldera (3 × 4 km). This caldera is propitious to farming and breeding activity. Despite these profitable assets, Lefo caldera (LC) is an amphitheater of the occurrence of multi-origin hazards that have direct or indirect impacts on the biodiversity and human patrimony. The most present hazards are those of meteorological origin. Numerous combined factors (steepest slopes, heavy rainfalls, weathered state of volcanic products…) rule these hazards. These factors gave rise to the occurrence of landslides, gullies erosion and rock falls which occur precisely on caldera northern and eastern rims. Hazards of anthropogenic origin are based on the destruction of the vegetation cover by the population for dealing, firewood and building issues. Moreover, during the breeding activity, the cattle covers the caldera throughout the day;this unevens the topography and destroys the meadow. Hazards of volcanological origin are not yet occurring in LC;but the recent Lake Monoun (1984) and Nyos (1986) CO2 eruptions, mount Cameroon eruptions (1999 and 2000) and mount Oku Lake event (2011) which are close to the BV and, the age of 0 Myr of basalt, constitutes a subject of controversy toward the reactivation of the Cameroonian hotspot faults. The assessment of risks in LC was based on the average income of breeding activity and house investment. The economy of LC is valued at about US$527472.527. The level of such risk will be important in case of loss of human beings and the destruction of geomorphosites’ values. In order to reduce the level of looses in this zone, hazard and risks maps are provided in this paper as well as some recommendations.

关键词： Hazards Risk Anthropogenic Activities Lefo Caldera

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Re-evaluation of recent research on metabolic utilization of energy in poultry: Recommendations for a net energy system for broilers

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Animal Nutrition 2024年第1期16卷 62-72页

作者： Jean Noblet Aye-Cho Tay-Zar Shu-Biao Wu Pairat Srichana pierre Cozannet pierre-Andre Geraert Mingan Choct INRAE Charoen Pokphand Foods Public Company Limited (CPF) School of Environmental and Rural Science University of New England Adisseo France S.A.S.

Different energy systems have been proposed for energy evaluation of feeds for domestic animals. The oldest and most commonly used systems take into account the fecal energy loss to obtain digestible energy(DE), and fecal, urinary and fermentation gases energy losses to calculate metabolizable energy(ME). In the case of ruminants and pigs, the net energy(NE) system, which takes into account the heat increment associated with the metabolic utilization of ME, has progressively replaced the DE and ME systems over the last 50 years. For poultry, apparent ME(AME) is used exclusively and NE is not yet used widely. The present paper considers some important methodological points for measuring NE in poultry feeds and summarizes the available knowledge on NE systems for poultry. NE prediction equations based on a common analysis of three recent studies representing a total of 50 complete and balanced diets fed to broilers are proposed; these equations including the AME content and easily available chemical indicators have been validated on another set of 30 diets. The equations are applicable to both ingredients and complete diets. They rely primarily on an accurate and reliable AME value which then represents the first limiting predictor of NE value. Our analysis indicates that NE would be a better predictor of broiler performance than AME and that the hierarchy between feeds is dependent on the energy system with a higher energy value for fat and a lower energy value for protein in an NE system. Practical considerations for implementing such an NE system from the commonly used AME or AMEn(AME adjusted for zero nitrogen balance) systems are presented. In conclusion, there is sufficient information to allow the implementation of the NE concept in order to improve the accuracy of feed formulation in poultry.

关键词： Poultry Feed evaluation Net energy Energy system

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A Review on Sources,Extractions and Analysis Methods of a Sustainable Biomaterial:Tannins

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Journal of Renewable Materials 2024年第3期12卷 397-425页

作者： Antonio Pizzi Marie-pierre Laborie Zeki Candan LERMAB University of LorraineFaculty of SciencesBlvd des AiguillettesNancy54000France Chair of Forest Biomaterials Institute of Earth and Environmental SciencesUniversity of FreiburgFreiburgGermany Freiburg Materials Research Center Alberst Ludwig University of FreiburgFreiburg79104Germany Department of Forest Products Engineering Faculty of ForestryIstanbul UniversitySariyerIstanbul34473Turkey

Condensed and hydrolysable tannins are non-toxic natural polyphenols that are a commercial commodity industrialized for tanning hides to obtain leather and for a growing number of other industrial applications mainly to substitute petroleum-based *** are a definite class of sustainable materials of the forestry *** have been in operation for hundreds of years to manufacture leather and now for a growing number of applications in a variety of other industries,such as wood adhesives,metal coating,pharmaceutical/medical applications and several *** review presents the main sources,either already or potentially commercial of this forestry by-materials,their industrial and laboratory extraction systems,their systems of analysis with their advantages and drawbacks,be these methods so simple to even appear primitive but nonetheless of proven effectiveness,or very modern and *** constitutes a basic but essential summary of what is necessary to know of these sustainable *** doing so,the review highlights some of the main challenges that remain to be addressed to deliver the quality and economics of tannin supply necessary to fulfill the industrial production requirements for some materials-based uses.

关键词： Tannins flavonoids sources extraction methods analysis methods

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