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Curvature, Hybridization and Contamination of Carbon Nanostructures Analysis Using Electron Microscopy and XANES Spectroscopy

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Materials Sciences and Applications 2014年第2期5卷 95-103页

作者： rolant eba medjo bridinette thiodjio sendja Jeannot Mane Mane Department of Mathematics and Physical Sciences Ecole Nationale Supérieure Polytechnique (National Advanced School of Engineering) University of Yaoundé I Yaoundé Cameroon Department of Mathematics and Physical Sciences Ecole Nationale Supérieure Polytechnique (National Advanced School of Engineering) University of Yaoundé I Yaoundé Cameroon Basical Scientist teaching (ESB) Department Training School of Secondary Technical School Teachers (ENSET) University of Douala Douala Cameroon Physics Department Faculty of Science University of Douala I Douala Cameroon

the ability to control the nanoscale shape of carbon nanostructures during wide-scale synthesis process is an essential goal in research for Nanotechnology applications. this paper reports a significant progress toward that goal. Variant CVD has been used for the synthesis of the samples studied. Curvature, hybridization and contamination are analyzed using Electron Microscopies and XANES spectroscopy. the investigations of the results show that four types of samples are obtained. they are carbon nanotubes (CNts), carbon nanofibers (CNFs), carbon nanowalls (CNWs) and carbon nanoparticles (CNPs). Almost all of them have catalyst nanoparticles (metal) on top in top growth model or on base in base growth model and encapsulated or adsorbed in sidewalls. the orientation of tubular carbon nanomaterials depends on operating parameters. they are classified in three groups: the poorly oriented, the medium oriented and the highly oriented. their contamination (radicals, atoms and molecules) and hybridization are intrinsically related to the curvature of their graphene layers. XANES spectroscopy allows quantitative characterization of nanomaterials.

关键词： Carbon Nanostructures XANES Spectroscopy Electron Microscopy Characterization Contamination

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theoretical Investigation of X-Ray Absorption near Edge Spectroscopy (XANES) Angular Dependence of Aligned Carbon Nanotubes Grown by DC HF CVD Process

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Materials Sciences and Applications 2015年第5期6卷 373-390页

作者： bridinette thiodjio sendja.rola.t eba medjo Jeannot Mane Mane Germain Hubert Ben-Bolie Pierre Owono Ateba Ecole Nationale Supérieure Polytechnique (National Advanced School of Engineering) Department of Mathematics and Physical Sciences University of Yaoundé I Yaounde Cameroon Physics Department Faculty of Science University of Douala Douala Cameroon Physics Department Faculty of Science University of Yaoundé I Yaounde Cameroon

Carbon nanotubes (CNts) grown on plain substrates SiO2/Si(100) by a direct current and hot filaments catalytic chemical vapor deposition process have been studied by synchrotron X-ray absorption near edge spectroscopy (XANES) technique to theoretically investigate the angular-dependence of carbone (C) K-edge π* and σ* transitions. Experimental XANES spectra show that π* resonance increases with the incidence angle from normal to grazing incidence angle while σ* resonance decreases. this has been explained by the sine-square and cosine-square dependencies of π* and σ* intensities, respectively. these results were confirmed by theoretical XANES curves of highly oriented pyrolytic graphite (HOPG) and CNts plotted versus incidence angle. It has been shown that π* and σ* transitions strongly depend on the nature of polarized light (linearly or circularly). At the linear polarized light, π* resonance is a preference as well as at right-circular polarized. At the left-circular polarized light, σ* resonance is a preference. the π* intensities are high at parallel orientation and the σ* intensities are low at normal orientation. the smallest π* intensity is noticed at normal orientation, where the π* orbitals are supposed to be lying parallel to the surface plane for perfectly aligned HOPG or CNts. this explains the incomplete extinction of π* intensity. We noticed at parallel orientation a region where any π* and σ* transitions did not expect because of the lack of polarization light.

关键词： Angular Dependence XANES Normal Incidence Grazing Incidence Carbon Nanotubes Intensity

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Alignment of Vertically Grown Carbon Nanostructures Studied by X-Ray Absorption Spectroscopy

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Materials Sciences and Applications 2014年第13期5卷 966-983页

作者： Jeannot Mane Mane Francois Le Normand rolant eba medjo Costel Sorin Cojocaru Ovidiu Ersen Antoine Senger Carine Laffon bridinette thiodjio sendja César Mbane Biouele Germain Hubert Ben-Bolie Pierre Owono Ateba Philippe Parent IPCMS UMR 7504 CNRSStrasbourgFrance Ecole Nationale Supérieure Polytechnique(National Advanced School of Engineering) Department of Mathematics and Physical SciencesThe University of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of DoualaDoualaCameroon LURE UMR CNRSCentre Universitaire Paris SudOrsayFrance

X-Ray Absorption Spectroscopy (XAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. they are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. the morphology and the nature of these carbon nanostructures are characterized by SEM, tEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNts), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty π* and σ* states occur. A full lineshape analysis of the XAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of π* and σ* transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... this degree of alignment shows good agreement with SEM observations. thus CNts films display degrees of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

关键词： X-Ray Absorption Spectroscopy Carbon Nanostructures(CNts,CNFs,CNWs,CNPs) Plasma-and Hot Filaments-Enhanced Catalytic Chemical Vapor Deposition Geometrical Model Angular Dependence

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Quantifying post logging biomass loss using satellite images and ground measurements in Southeast Cameroon

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Journal of Forestry Research 2016年第6期27卷 1415-1426页

作者： Richard Sufo Kankeu Denis Jean Sonwa ichard eba’a Atyi Noelle Marlène Moankang Nkal Center for International Forestry Research (CIFOR) PO Box 2008 Messa Yaounde Cameroon University of Maine-Lemans Avenue Olivier Messiaen72085 Le Mans France FASA University of Dschang PO Box 222 DschangCameroon

Forest logging in the Congo Basin has led to forest fragmentation due to logging infrastructures and felling gaps. In the same vein, forest concessions in the Congo Basin have increasing interest in the REDD＋ mechanism. However, there is little information or field data on carbon emissions from forest degradation caused by logging. to help fill this gap, Landsat 7 and 8 and SPOt 4 images of the East Region of Cameroon were processed and combined with field measurements （measurement of forest roads widths, felling gaps and log yards） to assess all disturbed areas. Also, measurements of different types of forest infrastructures helped to highlight emission factors. Forest contributes to 5.18 % of the degradation of the annual allowable cut （AAC）（84.53 ha） corresponding to 4.09 % of forest carbon stock （6.92 t ha^-1）. Felling gaps constitute the primary source of degradation, represented an estimated area of 32.41 ha （2 % of the cutting area） far ahead of primary roads （18.44ha） and skid trails （16.36 ha）. Assessment of the impact of degradation under the canopy requires the use of high resolution satellite images and field surveys.

关键词： Forest logging Eastern Cameroon Carbon Satellite images REDD+

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Spatial Availability of Nitrogen and Pesticides in the Surface Layers of Agricultural Soils of tropical Hydrosystems in the Wet Season: Case of the BéréWatershed in Côte d’Ivoire (West Africa)

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Journal of Agricultural Chemistry and Environment 2021年第2期10卷 143-168页

作者： Mian Germain eba Kouakou Sylvain Akpo Pétémanangnan Jean-Marie Ouattara tiangoua Koné Lacina Coulibaly Environment and Aquatic Biology Laboratory Nangui Abrogoua University Abidjan C&ocirc te d’Ivoire Central Environment Laboratory Ivorian Antipollution Center Abidjan C&ocirc te d’Ivoire Department of Chemistry University of Man Man C&ocirc te d’Ivoire

the objective of this study was to assess the contribution of the spatial organization of cropping systems and the physicochemical properties of surface layers of the agricultural zones soils in tropical hydrosystems to the spatial availability of nitrogen and pesticides during the wet season, such as the Béré watershed (BW) in C?te d’Ivoire. For this purpose, after mapping the spatial distribution of the BW cropping systems based on the likelihood classification methodology of satellite images of the study area, 27 samples from the 0 - 20 cm horizon of the soil surface layers of the agricultural areas were taken during the wet and agricultural season of the year 2016. the Kjeldahl method has been used to evaluate the total nitrogen concentration and high-performance liquid chromatography (HPLC) chain made it possible for the analysis of pesticide residues in the soil solutions. Geostatistical analysis and processing of spatial data and physicochemical and agrochemical soil parameters revealed that two major agricultural areas stand out in the BW, namely the Béré upstream watershed (BUW) dominated at 32.65% by annual croppings (maize, cotton, rainfed or lowland rice, market gardening, etc.) and the Béré downstream watershed (BDW) by large areas of perennial croppings (cashew nuts, cocoa, etc.), i.e. 21.47%. Agricultural soils in BW are usually of the moderately desaturated ferralitic type with a low acid pH and a quite strong temperature, such as those of tropical soils’ characteristics. However, agricultural soils in the BUW are characterized by higher proportions of sand and coarse sand. the parameters such as total porosity, cation exchange capacity, clay, organic matter, silt, fine silt, coarse silt, and potassium ions, are higher in the soils of the agricultural area of the BDW. Moreover, soils in the agricultural areas of the BUW are less rich in total nitrogen (0.84 g·k

关键词： Agrochimical Products Soils Contamination Water Resources Pollution West Africa tropical Hydrosystems Béré Watershed Côte d’Ivoire

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十六型大疱性表皮松解病临床鉴别、治疗和产前诊断

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国际遗传学杂志 1982年第6期05卷 314-315页

作者： Gedde-Dahl t ,李光泽

近十几年,对大癌性表皮松解病(EB)的认识有相当大的提高。已经报道了十六型遗传性EB。Gedde-Dahl等认为至少有九种不同的先天性EB,另外还有后天性EB。各型EB的电镜检查有相似处,但临床表现和预后却不同。现对隐性遗传的EB Herl-its(R-EB... 详细信息

近十几年,对大癌性表皮松解病(EB)的认识有相当大的提高。已经报道了十六型遗传性EB。Gedde-Dahl等认为至少有九种不同的先天性EB,另外还有后天性EB。各型EB的电镜检查有相似处,但临床表现和预后却不同。现对隐性遗传的EB Herl-its(R-eba-GH)已能做出产前诊断。本

关键词：产前诊断皮肤活检 eba 表皮松解胎儿皮肤原纤维 EBD 羊水细胞 EBS

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辽宁彰武地区青铜时代石器分析与聚落形态研究

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边疆考古研究 2017年第2期 109-124页

作者：丁山中国人民大学考古文博系

一、引言长期以来,人们一直认为中国东北地区专门化的游牧部族出现在青铜时代晚期(公元前1200~前600年)。理论上,专门化游牧人群与定居化农业者之间的互动,对该地域社会复杂性的增加有促进作用。然而,能够证明中国东北地区游牧经济萌芽... 详细信息

一、引言长期以来,人们一直认为中国东北地区专门化的游牧部族出现在青铜时代晚期(公元前1200~前600年)。理论上,专门化游牧人群与定居化农业者之间的互动,对该地域社会复杂性的增加有促进作用。然而,能够证明中国东北地区游牧经济萌芽的聚落和生计证据尚显不足,导致游牧者与农业者之间互动的理论缺乏材料支持。本研究旨在探究以下两个问题的答案:(1)在青铜时代晚期气候变得温暖干燥的条件下,对于有些社区而言。

关键词：青铜时代聚落形态痕迹证据 eba 痕迹分析

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家庭近乎完美量表中文版的信效度分析

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心理与行为研究 2012年第3期10卷 236-240页

作者：邓晶晶王子健齐振亚杨丽天津大学心理研究所天津300072 密苏里大学咨询心理所美国密苏里州哥伦比亚市65211

在大学生群体中选取三个样本进行集体施测。选取500名大学生作为样本一,使用家庭近乎完美量表中文版、自尊量表、一般自我效能感量表和Beck抑郁问卷对其施测,对数据进行验证性因素分析、内部一致性信度分析和效标效度分析;六周后在样本... 详细信息

在大学生群体中选取三个样本进行集体施测。选取500名大学生作为样本一,使用家庭近乎完美量表中文版、自尊量表、一般自我效能感量表和Beck抑郁问卷对其施测,对数据进行验证性因素分析、内部一致性信度分析和效标效度分析;六周后在样本一中随机抽取71名大学生作为样本二,使用家庭近乎完美量表对其施测,对数据进行重测信度分析;另选取500名大学生作为样本三,使用家庭近乎完美量表中文版、近乎完美量表修订版的中文修订版和Frost多维完美主义量表对其施测,对数据进行聚合效度和区分效度分析。结果表明,家庭近乎完美量表中文版的各项信效度指标均达到心理测量学要求,可以作为一个有效的测量工具在中国文化背景的人群中使用。

关键词：家庭近乎完美量表信度效度

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