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旋量理论及其在材料力学中的应用

力学与实践 2024年

作者：黄行蓉李敏 Jean-pierre LAINE 北京航空航天大学中法工程师学院/国际通用工程学院北京航空航天大学航空科学与工程学院

旋量理论是为力学量身定制的数学工具，在描绘刚体运动时表现出独特优势。基于材料力学中的平截面假设，构件的截面运动可分解为形心位移以及截面绕形心的旋转，从而可将截面运动视为刚体运动，故可采用旋量理论刻画构件截面的运动和受... 详细信息

旋量理论是为力学量身定制的数学工具，在描绘刚体运动时表现出独特优势。基于材料力学中的平截面假设，构件的截面运动可分解为形心位移以及截面绕形心的旋转，从而可将截面运动视为刚体运动，故可采用旋量理论刻画构件截面的运动和受力。该描述方式在数学形式上具有统一性，在物理现象上能对应实际受载和变形的一般性，可将力学问题转变成基于旋量运算法则求解的数学问题。本研究期望能为我国材料力学教学提供新视角和新思路。

关键词：旋量理论材料力学数学工具

Total Fat, Fatty Acid Composition, Tocopherol and Tocotrienol Profiles in Fermented Beans of Ten Controlled Pollinated Cocoa (Theobroma cacao L.) Hybrids from Cameroon

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American Journal of Plant Sciences 2024年第5期15卷 359-373页

作者： Martin Paul Arnaud Mbida Simon Perrez Akoa Ronelle Fabiola Mbia Manga Ndjaga Jude Martine Louise Ondobo Onomo pierre Effa Department of Biochemistry Faculty of Science University of Yaounde I Yaounde Cameroon Laboratory of Plant Physiology and Biochemistry Department of Biological Science Higher Teacher&#8217s Training College University of Yaounde I Yaounde Cameroon Department of Food Science and Technology Faculty of Agriculture and Veterinary Medecine University of Buea Buea Cameroon National Technology Development Committee Ministry of Scientific Research and Innovation Administrative Center Yaounde Cameroon Department of Agriculture and Agropastoral Higher Technical Teacher&#8217s Training College University of Ebolowa Ebolowa Cameroon

This study aimed to discriminate ten Cameroonian cocoa hybrids according to their total fat, fatty acid composition, tocopherol and tocotrienol profiles. Six cocoa clones from the gene banks of the Cameroon Cocoa Development Corporation were used to create hybrids. The determination of fatty acid composition was carried out by using a gas chromatography (GC) apparatus coupled by a flame ion detector (FID). Tocopherol and tocotrienol analysis was performed by upper high-performance liquid chromatography (UHPLC). Information on the impact of the genotype on the cocoa fat composition was provided. The major fatty acids (FA) in fermented samples are stearic (34.57%), palmitic (26.13%), oleic (34.13%) and linoleic (3.16%) acids. (35.05% to 35.6%). SCA12 × ICS40, SCA12 × SNK13, SNK13 × T79/501 have the least hard cocoa butters. Tocopherols analysis showed a predominance of γ-tocopherols (94.64 ± 1.51 to 292.16 ± 3.17 µg∙g−1), whereas only a small amount of β and δ-tocopherol (from 0.46 to 2.78 µg∙g−1 and 0.12 to 5.82 respectively) was observed. No γ-tocotrienol was found in fermented samples. A differentiation in terms of total fat and tocopherol content was observed amongst hybrids with the same mother-clone, suggesting an impact of pollen on these compounds.

关键词： Cocoa Hybrids Lipid Composition UHPLC GC-FID

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极端天气增多露天音乐会应加强应急预案

商业周刊（中文版） 2024年第10期 28-31页

作者： Kendra pierre-Louis 逸思(译) 不详

户外活动面临的极端天气威胁逐年增加,高温、暴风雨、野火烟雾、龙卷风都有可能导致人员伤亡。安娜·克拉拉·贝内维德斯(Ana Clara Benevides)在失去意识前,很可能是感到了呼吸困难。2023年11月17日,泰勒·斯威夫特(Taylor Swift)在里... 详细信息

户外活动面临的极端天气威胁逐年增加,高温、暴风雨、野火烟雾、龙卷风都有可能导致人员伤亡。安娜·克拉拉·贝内维德斯(Ana Clara Benevides)在失去意识前,很可能是感到了呼吸困难。2023年11月17日,泰勒·斯威夫特(Taylor Swift)在里约热内卢尼尔顿桑托斯体育场举行演唱会,现场观众人数达到6万名,热浪袭人,“体感温度”高达59摄氏度。

关键词：斯威夫特极端天气体感温度克拉拉呼吸困难桑托斯龙卷风暴风雨

Perception and Management of Hemorroid Disease at the CSREF of the Commune Bamako Mali

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Surgical Science 2024年第2期15卷 89-97页

作者： Tounkara Cheickna Diarra Mohamed Hassimy Diarra Issaka Sanogo Keita Bakary Dembele Bakary Tientigui Traore Alhassane Togo pierre Adégné Lassana Kante Department of General Surgery The Cs Ref of Commune I of Bamako Bamako Mali Department of General Surgery The Gabriel TOURE University Hospital in Bamako Bamako Mali

This work was a prospective transversal study over 6 (six) months from May 2 to December 31, 2017 at the Reference Health Center of Commune I and the Chérif la Confessional Health Center in Bamako. The aim was to study the knowledge, attitudes and behavioral practices linked to hemorrhoids in Commune I of the Bamako district, to evaluate the frequency of hemorrhoidal disease, to determine the knowledge, attitudes and behavioral practices linked to hemorrhoids among patients, their companions and traditional therapists in Commune I of the district of Bamako and the factors which influence the motivations and decisions to resort to medical-surgical care and traditional medicine in patients suffering from hemorrhoids in order to analyze the results of the management of hemorrhoidal disease at Cs Ref CI. We collected 36 patients with hemorrhoidal disease, 25 caregivers and 15 traditional hemorrhoidal disease therapists. The sex ratio was 1.25 for patients;6.5 for traditional therapists and 1.5 for accompanying people. The average age of the patients was 32.75 years;49 years for traditional therapists and 28.76 years for those accompanying them. 55.6% of patients claim to know about hemorrhoidal disease;100% of traditional therapists and 80% of accompanying people. The dietary factor of hemorrhoidal disease was mentioned by 90% of patients;66.7% of traditional therapists and 100% of caregivers. Most patients initially resorted to traditional treatment out of fear of surgery and its after-effects. The patients were treated medically and surgically.

关键词： Hemorrhoidal Disease Caregivers Traditional Therapists Patients Surgery CS Ref CI

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

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

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

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

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