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Journal of Minerals and Materials Characterization and Engineering 2020年第5期8卷 377-392页

作者： Ndoumou Belinga Rémy Legrand Meva’a Lucien Ouagne pierre Betene Ebanda Fabien noah pierre marcel Atangana Ateba Jean Laboratoire de Mécanique (LME) UFD SI Université de Douala Douala Cameroun Laboratoire d’Ingénierie Civile et Mécanique Université de Yaoundé I Yaoundé Cameroun Laboratoire Génie de Production (LGP) ENI de Tarbes Tarbes France

In this research work, fiber extracted from the bark of Cola lepidota (CL) plant, grown in the flora of Southern part of Cameroon, was investigated for composites reinforcement. The investigation was carried via evaluation of water absorption capacity, moisture content, real density, porosity, chemical composition, chemical structure and thermal behaviour. It was discovered that the new fiber has relatively low moisture content and water absorption capacity similar to those of other investigated natural fibers such as flax, sisal, coconut, hemp and jute. Its porosity was found appropriate for composite production and the fiber was found to be thermally stable up to 230°C, with maximum degradation temperature of 325°C. The main constituents of the fibre include cellulose, hemicellulose and lignin. In conclusion, based on the properties investigated, this fiber is considered suitable for composite manufacture.

关键词： Cola lepidota Fiber Thermal Stability Physico-Chemical Characteristics FTIR-ATR Liber Stem

Elaboration and Characterization of a Plaster Reinforced with Fibers from the Stem of Cola lepidota for Industrial Applications

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World Journal of Engineering and Technology 2022年第4期10卷 824-842页

作者： Zogo Tsala Simon Armand noah pierre marcel Anicet Ayissi Zacharie Merlin Betene Ebanda Fabien Nkenne Youmba Judide Kenmogne Fabien Atangana Ateba Department of Civil Engineering ENSET University of Ebolowa Ebolowa Cameroon Department of Mechanical Engineering ENSET University of Douala Douala Cameroon Laboratory of Mechanics University of Douala Cameroon Douala Cameroon Laboratory of Energy Materials Modelisation and Method University of Douala Douala Cameroon Department of Civil Engineering ENSET University of Douala Douala Cameroon

Current environmental and eco-design issues require the use of environmentally friendly materials. These make up a large share of the building materials market. Natural fibers are already used in various types of materials, such as plastics, concrete and lime-based products. They exhibit different attributes like the right combination of mechanical, thermal and acoustic properties, allowing these types of materials to be used for different applications. The main disadvantage associated with plaster is its fragility, especially under mechanical stress. Therefore, it becomes interesting to study different methods that could improve the mechanical properties of plaster. The addition of fibers to the plaster to obtain a composite material is already recognized as a means of improving the behavior of the product, in particular after the rupture of the matrix. The aim of this work was to study the effects of the addition of natural fibers from the stem of Cola lepidota (CL), on the physical properties and the mechanical behavior of the composite matrix. This study highlights the effects of fiber size and volume fraction. It has been shown that the mass of composites decreases as the percentage and length of fibers increases. The mechanical properties of composite materials are also discussed. Even at low addition rates, CL stem fibers achieved slightly higher values of flexural properties.

关键词： Cola lepidota Vegetable Fiber Plaster Composite Retting Characterization

Elaboration and Characterization of Composite Materials Reinforced by Papaya Trunk Fibers (Carica papaya) and Particles of the Hulls of the Kernels of the Winged Fruits (Canarium schweinfurthii) with Polyester Matrix

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Journal of Minerals and Materials Characterization and Engineering 2020年第5期8卷 341-352页

作者： Ze Eric Parfait noah pierre marcel Nnomo Elobi Didine Nfor Clins Wiryikfu Betene Ebanda Fabien Ngahiyi Abbé Claude Valery Atangana Ateba Local Materials Promotion Authority Yaoundé Cameroon Department of Mechanical Engineering Higher Technical Teacher Training College Douala University of Douala Douala Cameroon Department of Industrial Construction Technology National Advanced School of Engineering of Douala University of Douala Douala Cameroon Laboratory of Civil Engineering and Mechanics Department of Mechanical Engineering National Advanced School of Engineering Yaoundé University of Yaoundé I Yaoundé Cameroon Mechanical Laboratory Higher Technical Teacher Training College Douala University of Douala Douala Cameroon

In this work we determine the physical and mechanical properties of local composites reinforced with papaya trunk fibers (FTP) on one hand and particles of the hulls of the kernels of the garlic (PCNFA) in the other hand. The samples are produced according to BSI 2782 standards;by combining fibers and untreated to polyester matrix following the contact molding method. We notice that the long fibers of papaya trunks improve the tensile/compression characteristics of composites by 45.44% compared to pure polyester;while the short fibers improve the flexural strength of composites by 62.30% compared to pure polyester. Furthermore, adding fibers decreases the density of the final composite material and the rate of water absorption increases with the size of the fibers. As regards composite materials with particle reinforcement from the cores of the winged fruits, the particle size (fine ≤ 800 μm and large ≤ 1.6 mm) has no influence on the Young’s modulus and on the rate of water absorption. On the other hand, fine particles improve the flexural strength of composite materials by 53.08% compared to pure polyester;fine particles increase the density by 19% compared to the density of pure polyester.

关键词： Physical and Mechanical Characterization Composite Fibers Papaya Tree Trunk Particles Shells Kernels Garlic Fruits

Prevalence of Hepatitis B and Associated Factors in the Garoua Central Prison, Cameroon: A Cross-Sectional Study

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Open Journal of Gastroenterology 2024年第5期14卷 174-183页

作者： Mohamadou Abdou Galdima Adamou Dodo Balkissou Guy Roger Nsenga Djapa Winnie Tatiana Bekolo Nga Gilles Aghoagni Antonin Wilson Ndjitoyap Ndam Ali Abas Mathurin pierre Kowo Firmin Ankouane Andoulo Dominique noah noah Oudou Njoya Servais Albert Fiacre Eloumou Bagnaka Faculty of Medicine and Biomedical Sciences University of Garoua Garoua Cameroon Garoua Regional Hospital Garoua Cameroon Faculty of Medicine and Pharmaceutical Sciences University of Dschang Dschang Cameroon Faculty de Medicine and Pharmaceutical Sciences University of Douala Douala Cameroon Faculty of Health Sciences University of Buea Buea Cameroon Faculty of Medicine and Biomedical Sciences University of Yaound&#233 1 Yaound&#233 Cameroon

Introduction: Hepatitis B virus (HBV) infection is a major public health problem in Cameroon. Garoua city is the headquarters of the North Region of Cameroon, where the HBV prevalence is among the highest of the country. The aim of this study was to determine the prevalence of HBsAg carriage and associated factors among persons incarcerated in the Garoua Central Prison. Methods: It was a cross-sectional study conducted from July 1 to July 31, 2023 at the Garoua Central prison. We included all prisoners willing to participate in the study and who gave their verbal consent. We collected data using a pre-established data entry form and we used rapid test for blood screening for HBV surface antigen (HBs Ag) with ELISA confirmation. Data were analyzed using the R® software for Windows. After the univariate analysis, we selected associated variables to HBV infection with p-value p-value was set at 5%. Results: We included 1389 prisoners out of which 97.6% were male. The median age (IQR) of the study population was 28 (23 - 35) years. The median (IQR) duration of incarceration was 12 (6 - 26) months and the mean (±sd) number of incarcerations was 1.24 (±0.6). HBV prevalence was estimated at 14.8% (95% CI: 13.0 - 16.7). Upon uni- and multivariate analysis, no risk factor was significantly associated with viral hepatitis B infection in our study population. Conclusion: The prevalence of Hepatitis B was high in the Garoua Central Prison, but there were no additional risk factors for HBV infection. There is a need to include the Garoua Central Prison and by the way other prisons in the country in the chronic viral hepatitis care program.

关键词： Hepatitis B Prison Associated factors Cameroon

Study of the Relative Variations of the Thermal Properties and Crystallinity of Blends (PP/EPR)/Calcium Carbonate

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Modeling and Numerical Simulation of Material Science 2021年第1期11卷 19-33页

作者： pierre marcel Anicet noah Fabien Betene Ebanda Louis-Max Ayina Ohandja Ateba Atangana Laboratory of Mechanics ENSET University of Douala Douala Cameroon Department of Mechanical Engineering ENSET University of Douala Douala Cameroon

The objective of this paper is to investigate the relative variations of the constants of the thermal properties and the degree of crystallinity of the mixtures (PP/EPR)/Calcium carbonates elaborated with the Micro Bivis. We have strengthened the basic copolymer PP/EPR of a low level (5%) by three calcium carbonates models socal312, socal322v, Winnofil spm. We then subjected the different mixtures obtained, two cycles of a thermal loading under differential scanning calorimetry DSC. We finally focused on the thermal properties of isotactic polypropylene (TfP, TcP, ΔHfP, ΔHcP) and we calculated the degree of crystallinity of the mixtures. Reducing the energy cost of implementing mixtures is one of the objectives of this work. We quantified the relative variations of the above properties with those of the base copolymer. It shows that at a low loading rate of calcium carbonate, there is a decrease in the enthalpies of crystallization during the second exothermic cycle, with values that can reach 5.53 J/gPP for the basic copolymer PP/EPR. During the second endothermic cycle, there is an overall increase in isotactic polypropylene melting temperature values for all the blends as well as for the basic copolymer PP/EPR. There is evidence that calcium carbonates are useful for lowering the melting energy of isotactic polypropylene, even at a low loading rate for the majority. The number of endothermic cycles accentuates this phenomenon which is linked to the presence in our composites, of a so-called confined amorphous phase.

关键词： DSC PP/EPR CaCO3 Crystallinity Micro Bivis

Implementation and Evaluation of Certain Properties of a Polymer Matrix Composite Material Reinforced by Fibrous Residues of Saccharum officinarumin View of an Applicability Orientation

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Journal of Minerals and Materials Characterization and Engineering 2021年第2期9卷 206-225页

作者： Marie Josette Ndengue Merlin Zacharie Ayissi pierre marcel Anicet noah Fabien Betene Ebanda Atangana Ateba Department of Mechanical Engineering ENSET University of Douala Douala Cameroon Laboratory of Mechanics University of Douala Douala Cameroon Laboratory of Energy Materials Modelisation and Method University of Douala Douala Cameroon National Higher Polytechnic School University of Douala Douala Cameroon

This study examines the implementation and characterization of a polymer matrix composite material reinforced by sugarcane residues. The aim of the study is to enhance the abundantly produced sugarcane bagasse in the form of residues in the processing plants of said sugar cane. The composite material developed takes into account the size parameters and mass load rate of the reinforcement, the variations of which are between 2.5 mm and 4 mm respectively for the first parameter and 10% to 25% for the second. The load on the test tube during the test has a random orientation. The composite is polyester matrix. The cold compression moulding technique was used in the production of the various samples. Physical properties such as the rate of water absorption and the density of the composite are assessed. The three-point bending tests are carried out with the aim of inducing Young’s modulus from the elaborate samples. Analysis of physical properties shows that water absorption increases with the rate of residue load. The average water absorption rate of bagasse fibres is estimated at 8% for the 2.5 mm fiber size and 12% for the 4 mm fiber size for all composites. Mechanical characterization by bending tests reveals a fragile behavior of the samples tested. Young’s modulus decreases when the load rate of fibrous residues increases regardless of the size of the fibers.

关键词： Composite Polymer Bagasse Young Modulus Saccharum officinarum

Elaboration and Characterization of a Hybrid Composite Material with Two Particles of the Same Size: Coco Shells and Palm Shells

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Open Journal of Composite Materials 2020年第4期10卷 77-91页

作者： pierre marcel Anicet noah Ebanda Fabien Betene Suzie Viviane Obame Beassoum Allasra Martin Christian Bindjeme Ateba Atangana Laboratory of Mechanics ENSET University of Douala Douala Cameroon Department of Mechanical Engineering ENSET University of Douala Douala Cameroon

This work aims to develop and characterize a hybrid composite material with two particles of the same size. As reinforcing particles, the hulls of palm nuts and coconut are chosen. Hybrid composite material composites in the form of specimens were produced by molding at 10%, 20% and 30% mass fractions in various sizes (0.63 mm, 1.25 mm and 2.5 mm). The samples were physically characterized (water absorption rate, moisture content, actual, theoretical and apparent density) and mechanical in 3-point flexion. The main results are: the highest and minimum water absorption rate are respectively 3.57% and 0.67% for respectively particle sizes 1.25 mm (sample P10C30) and 0.67% in the size of 0.63 mm (sample P10C10). The moisture content varies from 0.64 to 7.14% respectively for the P20C20 (2.5 mm) and P10C30 (2.5 mm) samples. The maximum and minimum real density are 1340,518 Kg/m3 and 1055.981 Kg/m3, for respectively the composites of particles sizes 1.25 mm (P20C10) and 0.63

Physico-Chemical and Thermal Characterization of Some Lignocellulosic Fibres: Ananas comosus(AC), Neuropeltis acuminatas(NA) and Rhecktophyllum camerunense(RC)

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Journal of Minerals and Materials Characterization and Engineering 2020年第4期8卷 205-222页

作者： Achille Désiré Omgba Betene Fabien Ebanda Betene Florian Martoïa pierre J. J. Dumont Ateba Atangana pierre marcel Anicet noah Department of Mechanical Engineering ENSET University of Douala Douala Cameroon Laboratory of Mechanics University of Douala Douala Cameroon University of Lyon INSA-Lyon CNRS UMR5259 LaMCoS Lyon France

This paper focuses on the study of the physical, biochemical, structural, and thermal properties of plant fibres of Rhecktophyllum camerunense (RC), Neuropeltis acuminatas (NA) and Ananas comosus (AC) from the equatorial region of Cameroon. The traditional use of these fibres inspired researchers to investigated their properties. This study aims at improving the state of knowledge with a view to diversifying applications. The fibres are extracted by retting. Then, their apparent density was measured following the ASTM D792 standard and their water moisture absorption and moisture content were also evaluated. Their molecular structure was studied by ATR-FTIR spectroscopy. A quantitative analysis of the biochemical composition was performed according to the analytical technique for the pulp and paper industry (TAPPI). A TGA/DSC analysis was also performed. The results reveal that the AC, NA and RC fibres have densities of 1.26 ± 1.06, 0.846 ± 0.13 and 0.757 ± 0.08 g·cm-3 respectively. They are also hydrophilic with a water absorption rate of 188.64 ± 11.94%, 276.16% ± 8.07% and 198.17% ± 20%. They have a moisture content of 12.21%, 10.36% and 9.37%. The studied fibres exhibit functional groups that are related to the presence of hemicellulose, pectin, lignin and cellulose. The cellulose crystallinity index was found to be 67.99%, 46.5% and 59.72% respectively. The fibres under study have the following chemical composition: an extractive content of 3.07%, 14.77% and 8.74%;a pectin content of 4.15%, 7.69% and 3.45%;a hemicellulose content of 4.90%, 15.33% and 7.42%;a cellulose content of 68.11%, 36.08% and 65.15%;a lignin content of 12.01%, 25.15% and 16.2%;and an ash content of 0.27%, 1.53% and 0.47% respectively. The thermal transitions observed on the thermograms correlate with the TAPPI chemical composition. It is observed that these fibres are thermally stable up to temperatures of 200°C, 220°C and 285°C. These results ma

关键词： Lignocellulosic Fibre Rhecktophyllum camerunense Neuropeltis acuminatas Ananas comosus Biochemical Composition Cellulose Crystallinity Index Thermal Behaviour

State of Knowledge on Starch as an Alternative Solution to Petrochemical Resources—A Review

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Journal of Minerals and Materials Characterization and Engineering 2023年第2期11卷 49-62页

作者： Jonas Peequeur Essome Mbang pierre marcel Anicet noah Laurent Libog Téclaire Ngoup Michel Mbere Taoga Fabien Betene Ebanda Laboratory of Mechanical ENSET University of Douala Douala Cameroon Department of Mechanical Engineering National Advanced School of Engineering University of Yaoundé I Yaoundé Cameroon Laboratory of Mechanics and Materials Adapted (LAMMA) ENSET University of Douala Douala Cameroon

The use of plastics from petrochemical resources poses environmental impacts, and one of the alternative solutions is the use of starch. The objective of this present work has been to present the literature on starch, and to highlight the debate in the development of composite films. The approach adopted was to present the state of the art on starch and thermoplastic starch matrix composites. The work shows that starch is available worldwide and can be used in the manufacture of biodegradable plastics;the debate remains on the reinforcement of thermoplastic starch to improve its physical and mechanical properties poor;then researchers must diversify the reinforcements to see the impact on the properties of thermoplastic starch.

关键词： Plastics Starch Composite Films Thermoplastic Starch Biodegradable

Physical-Chemical and Mechanical Characterization of the Bast Fibers of Triumfetta cordifolia***. from the Equatorial Region of Cameroon

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Journal of Minerals and Materials Characterization and Engineering 2020年第4期8卷 163-176页

作者： Armel Edwige Mewoli César Segovia Fabien Betene Ebanda Atangana Ateba pierre marcel Anicet noah Benoit Ndiwe Abel Emmanuel Njom Department of Mechanical Engineering ENSET University of Douala Douala Cameroon Laboratory of Mechanics University of Douala Cameroon Douala Cameroon CETELOR University of Lorraine CETELOR/27 rue Philippe SEGUIN Epinal France Laboratory of Mechanics Materials and Modelization National School of AGRO-Industrial Sciences (ENSAI) Physics Application and Engineering Ngaoundere University Ngaoundere Cameroon Laboratory of Mechanics Materials Structures and Integrated Manufacturing National Advanced School of Engineering University of Yaounde 1 Yaounde Cameroon

The project consists in the implementation of a biocomposite based on tannin resin and natural rubber matrices with the bast fibres of Triumfetta cordifolia ***.“Okong” from the equatorial region of Cameroon as reinforcement. A study of this still little known fibre is necessary. This paper evaluates the physico-chemical and mechanical characteristics of the fibers. The fibers are extracted by us. A series of experiments is conducted for this purpose: morphological observation with a scanning electron microscope (SEM);density evaluation with a helium pycnometer;absorption rate evaluation according to the protocol available in the literature, Fourier Transform Infrared Spectrometry (FT-IR), chemical composition evaluation according to ASTM 1972 and ASTM 1977 standards, thermogravimetric analysis (TGA) and tensile tests on fiber bundles according to NF T25-501-3. The results show that the fiber is made up of several elementary fibers with oval cross-sections. A density of 1.477g/cm3 close to that of hemp. These fibers have a water absorption rate of 342.5%, which correlates with the presence of free hydroxyl functional groups obtained from the spectrometry study (FT-IR). Chemical analysis reveals that the fiber is made up of celluloses (44.4%), hemicelluloses (30.8%), lignins (18.9%), pectins (3.3%), waxes (0.5%) and minerals (2.1%). In addition, we learn that the fibers studied dehydrate at 11.49%, showinga notable thermal stability around 235°C with a peak thermal decomposition of cellulose located at 420°C. In terms of mechanical behaviour, the results reveal that the fibers offer a Young’s modulus in traction of 12.4 ± 6.9 GPa, a tensile strength of 526 ± 128 MPa and an elongation at break of 2.25%. The information thus obtained makes it possible to place these fibers in the same fiber group as flax and jute. They could therefore be used for the same types of applications. They also inform us that these fibers can withstand the temperat

关键词： Triumfetta cordifolia Fibers Morphology Chemical Analysis Thermal Degradation Mechanical Behavior