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Modeling the Drying Kinetics of Earth Bricks Stabilized with Cassava Flour Gel and Amylopectin

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Geomaterials 2019年第1期9卷 40-53页

作者： mondésir ngoulou Raymond Gentil Elenga Louis Ahouet Stevina Bouyila Serge Konda Laboratoire des Matériaux et énergies (LME) Faculty of Sciences and Technics Marien Ngouabi University Brazzaville Congo Bureau de Contrâ le du Batiment et Travaux Publics (BCBTP) Brazzaville Congo

Earth bricks could contribute to alleviate the housing shortage in the world, thanks to their low cost, easy production, and low environmental impact. However, to manufacture bricks with required properties, many raw soils must be ameliorated. In Central and Eastern Africa, the waste water of the cassava processing is used to improve earth brick mechanical properties. This technique is interesting, because it is sustainable, low-cost and easy to implement. But, studies on this stabilization method are scarce, in particular on the drying kinetics of these bricks. Now, it is important to know the drying duration, because the earth brick’s strength is strongly correlated to its moisture content. Thus, this study aims to quantify and to model the effect of adding cassava flour gel and amylopectin on the drying kinetics of earth bricks. Depending on the soil nature, the drying duration decreases from 7% to 25% for a stabilizer content of 20%. For the five models used, the coefficient of determination is superior to 0.997 and the chi square is inferior to 3 × 10−4. In average, the best model is Khazaei, followed in order by Avrami-Page, diffusion, Yong and Peleg. The effective coefficient of diffusion of water is about 4 × 10−5 m⋅s−2. The parameter T of the Khazaei’s model is strongly correlated to the drying duration and the stabilizer content, and their relationships have been deduced.

关键词： Earth Brick Stabilization Drying Kinetics Modeling Cassava Starch

NaOH Activation of Raw Soils: Effect of NaOH Content on the Drying Kinetic and Its Modelling

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Geomaterials 2019年第2期9卷 55-66页

作者： Stevina Bouyila Raymond Gentil Elenga Louis Ahouet mondésir ngoulou Serge Konda Laboratoire des Matériaux et Energies (LME) Faculty of Sciences and Technics Marien Ngouabi University Brazzaville Congo Bureau de Contrô le du Batiment et Travaux Publics (BCBTP) Brazzaville Congo

NaOH activation of soils is an affordable and promising way to improve mechanical properties of earthen bricks. If for well-activated geopolymers, the hard polymeric network limits the influence of water on mechanical properties, for the weakly activated one, as non-calcined raw clayey soils, the influence of water on these properties would be more critical. This work aims to determine the effect of sodium hydroxide concentration on the drying kinetics of bricks made with raw clayey soils, and to model this kinetics. The results show that the drying kinetics is governed by the diffusion of water due to the absence of free water. The drying duration increases linearly with the increasing of NaOH content, while the volumetric shrinkage decreases, probably thanks to the reduction of the material porosity during the formation of the zeolitic structures. Besides, the drying duration is strongly and negatively correlated with the initial drying rate (−0.97) and bricks did not show visible cracks. Among the five parametric models tested, the Khazaei’s model is the best in terms of all statistical criteria considered. For all models used, the coefficient of determination is ranged from 0.993 to 0.999, and the evolution of the models’ parameters is in accordance with that of the drying kinetics observed.

关键词： Earthen Brick Stabilization Alkaline Activation Modeling Geopolymer Drying Kinetics

Assessment of Trends in the Development of the It Market

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Open Journal of Applied Sciences 2023年第7期13卷 1111-1118页

作者： Conrad Onesime Oboulhas Tsahat ngoulou A. Ndzeli Ecole Nationale Supérieure Polytechnique Université Marien Ngouabi Brazzaville Republic of the Congo

The demand for information technology in a new way forced us to reconsider our views on the state of the information and communication technology market. The analysis of the trend in the development of the information space is necessary for the formation of a scenario for the formation of a stable information and communication industry in the hotel state. The article proposes the structure of the IT market, defines the role of its main parts and concludes about their impact on the further development of the IT industry. A brief overview of the components of the modern IT market is presented. The greatest influence is provided by cloud solutions, the Internet of Things market and digital products in the field of artificial intelligence. Observation of changes in the IT market allows us to predict further events related to digitalization. In conclusion, possible ways of developing the IT market are given.

关键词： Information Technologies IT Market Trend Digitalization Software Products

Antibiotic Resistance Phenotypes of <i>Enterobacteriaceae</i>Isolated from Household Wastewater in Brazzaville, Republic of Congo

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Advances in Microbiology 2021年第1期11卷 27-36页

作者： Rachel Moyen Tarcisse Baloki ngoulou Etienne Nguimbi Gabriel Ahombo Laboratory of Cellular and Molecular Biology Sciences and Techniques Faculty University Marien NGOUABI Brazzaville Congo

Household wastewater is a source of pollution and can present health risks when discharged into the environment. Thus, samples of household wastewater from a few neighborhoods in Brazzaville were analyzed for microbiological quality. The various samples were cultured for isolation on solid media using conventional microbiological methods. The bacteria isolated were identified by the Enterobacter System gallery. Sensitivity tests were performed using the standard antibiotic susceptibility test by diffusion on Mueller Hinton medium. At the end of the analysis, 51 Enterobacteriaceae were isolated and identified. They included: 8 (15.68%) Escherichia coli, 8 (15.68%) Salmonella spp., 8 (15.68%) Shigella spp., 8 (15.68%) Klebsiella spp., 5 (9.80%) Enterobacter aerogenes, 8 (15.68%) Enterobacter cloacae, 3 (5.90%) Arizona spp., 3 (5.90%) Proteus spp. The results obtained show that the bacteria tested showed total resistance to the following antibiotics: amoxicillin, amoxicillin + clavulanic acid, cloxacillin and nalidixic acid. On the other hand, imipenem, cefuroxime, cefotaxime, cefftriazone and kanamycin were the most active antibiotics with low levels of resistance. The low resistance rates observed for imipenem, cefotaxime, cefuroxime and cefftriazone show that these antibiotics can be used for the treatment of infections caused by household wastewater bacteria.

关键词： Antibiotic Therapy Enterobacteriaceae Sewage Households

The Role and Place of Artificial Neural Network Architectures Structural Redundancy in the Input Data Prototypes and Generalization Development

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Journal of Computer and Communications 2024年第7期12卷 1-11页

作者： Conrad Onésime Oboulhas Tsahat ngoulou-A-Ndzeli Béranger Destin Ossibi Ecole Nationale Suprieure Polytechnique Universit Marien Ngouabi Brazzaville Republic of Congo

Neural Networks (NN) are the functional unit of Deep Learning and are known to mimic the behavior of the human brain to solve complex data-driven problems. Whenever we train our own neural networks, we need to take care of something called the generalization of the neural network. The performance of Artificial Neural Networks (ANN) mostly depends upon its generalization capability. In this paper, we propose an innovative approach to enhance the generalization capability of artificial neural networks (ANN) using structural redundancy. A novel perspective on handling input data prototypes and their impact on the development of generalization, which could improve to ANN architectures accuracy and reliability is described.

关键词： Multilayer Neural Network Multidimensional Nonlinear Interpolation Generalization by Similarity Artificial Intelligence Prototype Development

Prospects of Using Low-Code in the Creation of Automated Systems

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Open Journal of Applied Sciences 2023年第10期13卷 1864-1869页

作者： Conrad Onesime Oboulhas Tsahat ngoulou-A-NDZELI Patrick Aurélien Ampiri Kwai Ecole Nationale Supérieure Polytechnique Université Marien Ngouabi Brazzaville Republic of Congo

Ever-changing market conditions and a rapidly changing IT landscape call for fast and cheap ways to meet software demands. In order to tackle these problems, low-code development platforms (LCDPs) have emerged. These platforms are designed with the idea to limit recurring traditional hand-coding and programming. This article provides a theoretical overview of low-code solutions. The advantages and disadvantages of using LCDP in the creation of automated systems are considered. In conclusion, a conclusion is formulated about the prospects of using low-code technology.

关键词： Low-Code Coding Automated Systems Low-Code Development Platform

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复合外源蛋白酶对牛肉嫩化的效果及优化研究

复合外源蛋白酶对牛肉嫩化的效果及优化研究

作者：刘诚（ngoulou Mfera Jaures Timpar）安徽农业大学

学位级别：硕士

肉的嫩度是消费者评价肉及肉制品质量好坏以及反复购买的关键因素。目前,如何改善肉的嫩度仍是研究的热点。本文采用响应面的方法来探究木瓜蛋白酶(P)、菠萝蛋白酶(B)和无花果蛋白酶(F)以及三种酶复配对牛肉质构特征、理化性质及肌肉微... 详细信息

肉的嫩度是消费者评价肉及肉制品质量好坏以及反复购买的关键因素。目前,如何改善肉的嫩度仍是研究的热点。本文采用响应面的方法来探究木瓜蛋白酶(P)、菠萝蛋白酶(B)和无花果蛋白酶(F)以及三种酶复配对牛肉质构特征、理化性质及肌肉微观结构的影响。以嫩化时间、嫩化温度和酶活力为单因素,以牛肉剪切力为响应值,运用Design-Expert 8.06软件对得到的单因素结果建立回归方程,结果如下:1、通过三种蛋白酶的单因素实验发现木瓜蛋白酶嫩化效果最好,单因素结果为:最佳作用时间、温度以及酶活力分别为:15 h、12℃以及20 U/g。响应面优化结果表明木瓜蛋白酶最佳嫩化条件为:嫩化时间15.26h、嫩化温度为12.48℃、酶活力24.09 U/g。2、实验进一步对三种蛋白酶进行复合(B+P、B+F、F+P、B+F+P),采用单因素实验发现复合酶(木瓜蛋白酶和菠萝蛋白酶复合,B+P)嫩化效果最好。单因素结果为:最佳作用时间、温度以及酶活力分别为9h、8℃以及20U/g。响应面优化结果表明:所有注射B+P组显著减少牛肉的剪切力值和硬度(P<0.05),最佳嫩化条件为:B+P:24.10 U/g、嫩化时间是:9.27 h、嫩化温度为:8.45℃,在此条件下,牛肉的剪切力值为1.304 kg.f。3、为了进一步确认获得最优的外源蛋白酶对牛肉嫩度的改善效果,实验选取具有高活性的木瓜蛋白酶(酶活力:24.09U/g)和复合蛋白酶(B+P:24.10U/g)注射到牛肉中(嫩化时间和嫩化温度分别按照结果1和2的嫩化时间和嫩化温度)。研究结果表明:与空白处理组相比,所有处理组均可显著改善牛肉的剪切力和硬度(P<0.01)。菠萝蛋白酶和木瓜蛋白酶复配组(B+P)活性最高,达到24.10U/g。系水力和水分含量显著变高(P<0.05)。然而,牛肉的pH值显著降低。扫描电子显微结果表明:处理组肌肉结构组织松散,肌纤维之间空隙变大,肌束松散,说明牛肉经注射的酶处理后能使肌纤维断裂,细胞膜降解,从而可以有效地改善牛肉的嫩度。同时实验结果也表明响应面法(RMS)在改善牛肉嫩度方面具有良好的适用性和可行性。

关键词：外源酶响应面法牛肉嫩度质构、理化性质显微结构

Evaluation of the Bioremediation Potential and Antimicrobial Activity of Pseudomonas and Bacillus Bacteria Isolated from Landfills in Brazzaville, Congo

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Journal of Biosciences and Medicines 2023年第8期11卷 129-140页

作者： Adriana Préfina Nzoumba Pandi Saturnin Nicaise Mokemiabeka Joël Prince Bidounga Tarcisse Baloki ngoulou Rachel Moyen Laboratory of Cellular and Molecular Biology Faculty of Science and Technology Marien Ngouabi University Brazzaville Congo

The pollution of ecosystems as a result of urbanization, industrialization and poor agricultural practices is becoming increasingly alarming. This has a major impact on health and the economy. This pollution causes illness in humans and animals, even at low levels of exposure, leading to endocrine disorders, congenital malformations, cardiovascular disease, nervous system damage and cancer. They are a brake on redevelopment because of the threats they pose, generally causing an anaerobic environment by blocking the diffusion of air into the soil pores, thus affecting the microbial communities living there and preventing the infiltration of water necessary for plant growth. In an ecosystem subjected to various disturbances, changes can be observed in ecosystem structure and function, including loss of aesthetic values, changes in biomass or productivity, and changes in species composition. These include loss of aesthetic values, changes in biomass or productivity, and altered species composition, as a result of habitat loss, disruption of food webs and variations in macro- and micro-climatic environmental conditions. Respect for the environment is becoming a major concern in today’s society. To remedy this, the concept of biological control was used as an alternative, with the selection of microorganisms of bioremediator interest. Twenty (20) isolates, including 10 (50%) from the Pseudomonas genus and 10 (50%) from the Bacillus genus, were isolated from landfills, identified and tested to assess their biofertilization (phosphate solubilization) and depollution (hydrocarbon degradation) potential, and to inhibit the growth of certain microorganisms. The results showed that all Pseudomonas and Bacillus isolates solubilized inorganic phosphate, although this activity was higher in Bacillus. All Bacillus inhibited the growth of all the pathogens included in this study, while Pseudomonas only inhibited the growth of E. coli. With regard to their ability to degrade hydroca

关键词： Bioremediation Environment Pseudomonas and Bacillus

Hydrolytic and Antimicrobial Activities of Bacteria Isolated from Fermented Peppers Sold in Markets at Brazzaville, Republic of the Congo

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Journal of Biosciences and Medicines 2024年第9期12卷 215-234页

作者： Faly Armel Soloka Mabika Elgie Viennechie Gatsé Ngo Itsouhou Tarcisse Baloki ngoulou Mérite Berthelie Mouanda Nzoussi Nguimbi Etienne Laboratory of Cell and Molecular Biology Faculty of Sciences and Techniques Marien Ngouabi University Brazzaville Republic of the Congo Unit of Molecular Microbiology and Bioinformatics Faculty of Sciences and Techniques Marien Ngouabi University Brazzaville Republic of the Congo

Microorganisms are omnipresent in all environments and play mainly the role of transformers, thanks to the multiple enzymes they are able to produce. In order to valorize fermented foods in the Republic of the Congo, this work aimed to characterize and study some properties of microorganisms isolated from samples of peppers sold in three markets of Brazzaville. A numeration of the total aerobic mesophilic flora (TAMF) was made in a solid medium, allowing the evaluation of each sample’s microbial concentration. The microbial mass varied from 2.8 × 105 CFU/g for the Ouénzé sample to 1.8 × 104 CFU/g for the Total sample and 2 × 104 CFU/g for the Moungali market sample. The evaluation of the enzymatic properties of the Bacillus isolates showed that 68.42% were capable of producing cellulases and 78.94% were capable of producing amylases and proteases. Antimicrobial activities revealed that 63.15% of the isolates were able to secrete inhibitory substances against E. coli and Staphylococcus aureus. Molecular analysis by PCR amplification, sequencing of the 16S rRNA gene and BLAST bioinformatics analysis provides newly identified bacteria strains with new accession numbers in GenBank: Bacillus thuringiensis MBCBR322 (OP474008), Bacillus megaterium MBCBJ1822 (OP476493), Bacillus thuringiensis MBCBR222 (OP476494), Priestia megaterium MBCBJ2022 (OP476495) and Lactobacillus paraplantarum MBCBR1522 (OP476496). Multiple sequences alignment of identified sequences with their homologs of GenBank has shown high similarities. The phylogenetic inference assay has provided the two groups of strains observed in this study, and the two groups are very coherent with the phylogeny of the reference.

关键词： Antimicrobial Activity Hydrolytic Activity Sequencing Pepper Brazzaville