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Experimental and Theoretical Investigations on Copper Corrosion Inhibition by Cefixime Drug in 1M HnO3Solution

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Journal of Materials Science and Chemical Engineering 2021年第5期9卷 11-28页

作者： n’guessan yao silvère diki nagnonta Hippolyte Coulibaly Ollo Kambiré Albert Trokourey Laboratoire de Constitution et Réaction de la Matière UFR SSMT Université Félix Houphou&#235 t-Boigny Abidjan C&#244 te d’Ivoire UFR Sciences et Technologies Université de Man Man C&#244 te d’Ivoire

Cefixime, a third-generation semi-synthetic cephalosporin antibiotic was used as a copper corrosion inhibitor in 1M HnO3 solution. The study was conducted through the weight loss technique at 298 - 318 K and theoretical studies based on quantum chemistry. The studied drug inhibited the corrosion of copper in 1M HnO3 over the cefixime concentration range (0.02 - 2 mM). The inhibition efficiency increased with an increase in the inhibitor concentration to reach 91.07% at 2 mM, but decreased with an increase in temperature. The thermodynamic functions related to the adsorption of cefixime on the copper surface and that of the metal dissolution were computed and analyzed. The results point out spontaneous adsorption, mainly through a physisorption mechanism following Langmuir adsorption isotherm model and an endothermic dissolution process. Quantum chemical calculations were also performed at B3LYP level with 6-31G (d, p) basis set and lead to molecular descriptors such as EHOMO (energy of the highest occupied molecular orbital), ELUMO (energy of the lowest unoccupied molecular orbital), ΔE (energy gap) and μ (dipole moment). The global reactivity descriptors such as χ (electronegativity), χ (global hardness), S (global softness), and ω (electrophilicity index) were derived using Koopman’s theorem and analyzed. The local reactivity parameters, including Fukui functions and dual descriptors were determined and discussed. Experimental and theoretical results were found to be in good agreement.

关键词： Cefixime Corrosion Langmuir Quantum Chemistry Weight Loss

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Electrochemical Study of the Synergistic Effect of Two Copper Corrosion Inhibitors, nicotinic Acid (nAC) and nicotinamide (nAM) in Two Different Media

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Open Journal of Physical Chemistry 2019年第4期9卷 193-203页

作者： Yapi Serge Brou nagnonta Hippolyte Coulibaly n’guessan yao silvère diki Juan Creus Albert Trokourey Laboratoire de Chimie Physique (LCP) Université Félix Houphouët-Boigny d’Abidjan Abidjan Côte d’Ivoire Laboratoire des Sciences de l’Ingénieur pour l’Environnement (LaSIE) UMR 7356 CnRS Université de La Rochelle La Rochelle France

Inhibitive properties of nAC and nAM as well as their mixture have been investigated in two different corrosive media through potentiodynamic polarization and electrochemical impedance spectroscopy at 298 K. These electrochemical measurements indicate that the inhibition efficiency increases with the concentration for each of the inhibitors used separately as well as for their mixture. In both cases, the combination behaves as mixed type inhibitor with a great cathodic tendency. naCl 3.5% highlights an antagonist effect of nAM which reduces the effectiveness of nAC whereas HnO3 1M shows a synergistic effect between them.

关键词： nAC nAM Antagonist Effect Synergistic Effect

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7-(2-Ethyltiophenyl) Theophylline as Copper Corrosion Inhibitor in 1M HnO3

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Journal of Materials Science and Chemical Engineering 2018年第8期6卷 31-49页

作者： Ouédraogo Augustin Akpa Sagne Jacques diki n’guessan yao silvère Diomande Gbe Gondo Didier Coulibaly nagnonta Hippolyte Trokourey Albert Laboratoire de Chimie Physique Université Félix Houphou&#235 t-Boigny Abidjan C&#244 te d’Ivoire Laboratoire de Chimie Organique et Substances naturelles Université Félix Houphou&#235 t-Boigny Abidjan C&#244 te d’Ivoire

7-(2-ethyltiophenyl) theophylline was used as copper corrosion inhibitor in 1M HnO3 solution. The study was performed using mass loss, scanning electron microscopy (SEM) and Density Functional Theory (DFT) methods. The results show that the inhibition efficiency increases up to 91.29% with increase of the inhibitor concentration (from 0.05 to 5 mM) but decreases with raising temperature of the solution. Copper dissolution was found to be temperature and 7-(2-ethyltiophenyl) theophylline concentration dependent. The thermodynamic functions related to the adsorption of the molecule on the copper surface and that of the metal dissolution were determined. The results point out a spontaneous adsorption and an endothermic dissolution processes. Adsorption models including Langmuir, El-Awady and Flory-Huggins isotherms were examined. The results also suggest spontaneous and predominant physical adsorption of 7-(2-ethyltiophenyl) theophylline on the metal surface which obeys Langmuir isotherm model. Further investigation on the morphology using scanning electron microscopy (SEM) has confirmed the existence of a protective film of inhibitor molecules on copper surface. Furthermore, the global and local reactivity parameters of the studied molecule were analyzed. Experimental and theoretical results were found to be in good agreement.

关键词： Corrosion 7-(2-Ethyltiophenyl) Theophylline Mass Loss SEM DFT

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Empirical Analysis of China's Trade and Investment Impact on Africa's Economic Growth:The Importance of Good Governance

Empirical Analysis of China's Trade and Investment Impact on...

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作者： n'guessan yao Ba Kandiosky Romaric 东北财经大学

学位级别：硕士

It is crystal clear that developing the business environment is a key aspect for attracting both national and international investors to a country,which would ultimately lead to an economic *** a matter of fact,no investor will take the risk to move to a country that is politically unstable,bureaucratic,and highly corrupted economies with inefficient and nontransparent government *** a government that is socially accountable in providing services and sensitive to the needs of its citizens will ultimately create a democratic climate leading to inclusive growth and human *** whole word was surprised by the way China shifted gradually within thirty years in terms of *** from an under-developed and poor country,China is today one of the largest exporters of manufactured goods and consequently one of the most powerful countries in the *** at the world stage has not only brought visibility but also drawn the attention and interest of many other countries keen to know and learn how it is possible to make such a *** these countries many African countries still behind from an economic perspective have raised interest and knowing their enormous potentiality China has also tied solid *** can find the origins of trade and investment between China and Africa back in the 1950s,but China being the largest trade partner of Africa dates from *** year *** can see an increase in the total merchandise trade of China and Africa from $9 billion in 2000 to $254.3 billion in ***,from a foreign direct investment(FDI)perspective,there is also a remarkable increase regarding Chinese outward FDI flows to Africa from merely the $74.8 million it was in 2003 to a big jump of $4.2 billion in 2020,and this is part of what made China the largest developing country in terms of investment in *** known as the cradle of humankind,Africa is the place where humankind originated but has for long year

关键词： Investment Trade Africa China FDI good governance

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Study of the Viscosity and Specific Gravity of the Ternary Used Frying Oil (UFO)-Bioethanol-Diesel System

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Journal of Materials Science and Chemical Engineering 2024年第4期12卷 53-66页

作者： Konan Edmond Kouassi Abollé Abolle n’guessan Luc Brou David Boa n’guessan Raymond Kre Kouassi Benjamin yao Laboratoire de Thermodynamique et Physico-Chimie du Milieu (LTPCM) UFR-SFA UNA Abidjan C&#244te d&#8217Ivoire Laboratoire de Physiques Fondamentales et Appliqué es (LPFA) UFR-SFA UNA Abidjan C&#244te d&#8217Ivoire Laboratoire des Procé d&#233s Industriels de Synth&#232se de l&#8217Environnement et des Energies Nouvelles (LAPISEN) de l&#8217Institut National Polytechnique F&#233lix Houphou&#235t Boigny de Yamoussoukro Yamoussoukro C&#244te d&#8217Ivoire

Fossil fuels cover around 80% of global energy consumption. However, the problems linked to their use justify the choice of using biofuel. In order to reduce as much as possible, diesel rate, an increase in the number of additives may be considered. Thus, in this work, the study of the used frying oil (UFO), bioethanol and diesel ternary system was undertaken. It emerges from this study that the addition of bioethanol reduces the viscosity and the density of the ternary system and permits a 90% substitution rate for diesel between the UFO and bioethanol. Finally, the percentage of oil becomes 40% after adding alcohol compared to the binary diesel crude vegetable oil mixture where this rate is 30%.

关键词： Biofuel UFO-Bioethanol-Diesel Ternary Density Viscosity

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Parkia biglobosa (Mimosaceae) Leaves, Fruits’ Pulp, and Barks of Stem and Root Phytochemicals Contents and Their Antioxidant Activities

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Journal of Biosciences and Medicines 2022年第4期10卷 48-62页

作者： Ange-Mariette Touré Tagouèlbè Tiho n’guessan Jean-Claude yao Amissa Augustin Adima Department of Water Forests and Environment National Polytechnic Institute Félix Houphou&euml t Boigny Yamoussoukro C&ocirc te d’Ivoire Laboratory of Animal Science Department of Agriculture and Animal Resources National Polytechnic Institute Félix Houphou&euml t Boigny Yamoussoukro C&ocirc te d’Ivoire Laboratory of Industrial Processes Synthesis Environment and New Energies National Polytechnic Institute Félix Houphou&euml t Boigny Yamoussoukro C&ocirc te d’Ivoire

More and more Parkia biglobosa plants’ stem barks, and roots are collected for traditional medicine uses. This work aimed to quantify Parkia biglobosa plant parts total polyphenols, total flavonoids contents and their antioxidant activities. The hypothesis was that the plant parts would have different phytochemical contents. So, leaves, stem barks, root barks and mature fruit pulp were collected. Alongside the leaves, the stem and root barks were sliced, air-dried at room temperature for 30 days. Thereafter, the samples were crushed and sieved. Following this, the powders were extracted with distilled water by maceration and decoction. As a result, the decoction was more efficient than the maceration. Leaves had the highest total polyphenol content (14.68), followed by stem barks (11.69), and root barks (9.09 ± 0.43 mg GAE/g) (0.0001 ≤ p ≤ 0.0002). However, for total flavonoid contents, the stem barks were better than the other parts. Indeed, stem barks delivered 0.74 and were followed by leaves for 0.6, and root bark for 0.49 ± 0.02 mg EQ/g (0.0001 ≤ p ≤ 0.0169). Finally, the antioxidant activities were 3.07 and 2.86 ± 0.1 μmol T.E/g, respectively for stem bark, and leaves (p = 0.0532). In conclusion, there is no need to debark the stems, because, in decoction, leaves and stem barks would have the same efficacy.

关键词： Parkia biglobosa Total Polyphenols Total Flavonoids Antioxidant Activity

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Impacts of Field Harvesting and Conservation Practices on the Physical Quality of Yam “Kponan” (Dioscorea cayenensis-rotundata) of Côte D’Ivoire

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Open Journal of Applied Sciences 2022年第12期12卷 1979-1994页

作者： Yapo Hypolithe Kouadio Kouakou nestor Kouassi Daouda nimaga yao Denis n’dri n’guessan Georges Amani Laboratory of Food Biochemistry and Technology of Tropical Products Department of Food Science and Technology NANGUI ABROGOUA University Abidjan C&ocirc te D’Ivoire Swiss Center for Scientific research in Cô te d’Ivoire (CSRS-CI) Abidjan C&ocirc te D’Ivoire Agronomic Forestry and Environmental Engineering Department University of Man Man C&ocirc te D’Ivoire

Yam “Kponan” (Dioscorea cayenensis-rotundata) is a popular staple food in Côte d’Ivoire. However, its rapid decay during conservation prevents regular supply of markets. The objective of this study was therefore to assess the impact of field cultivation and conservation practices on some physical quality parameters of “Kponan”. To this end, “Kponan” yam from three production areas (Bondoukou, Bouna, Kouassi-Kouassikro) was cultivated in each area. At maturity, physical parameters of yams at harvest and after 3 months of storage in field were analyzed. The results showed that injury was the most significant deterioration in yam harvest. The rate of injured yams was highest for hoe-harvested in Kouassi-Kouassikro area (16.67% - 22.22%) regardless of the origin of the cuttings. The main damage observed after the 3 months of storage was rots (22.86% - 60.00%) and weight loss (8.57% - 42.86%). However, yams stored in pits in Bouna zone had less damage (40% - 48.87%) than those stored under straw huts in Bondoukou locality (100%) and at shade under a tree in Kouassi-Kouassikro area (100%). In conclusion, the physical quality of “Kponan” in field is most affected by abusive use of herbicides during weeding and clearing, hoe harvesting and storage in the shade under a tree.

关键词： “Kponan” Yam Post-Harvest Loss Cultivation Practices Conservation Practices Physical Quality

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Sequential Analysis in the Identification of 3rd Order System Tract in the Abidjan Margin

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Open Journal of Applied Sciences 2024年第6期14卷 1474-1489页

作者： Blandine Akissi Egoran n’guessan Donald Ahoure Fori yao Paul Assalé Sylvain Mondé Loukou Victor n’da UFR Marine Sciences San Pedro University San Pedro Cte dIvoire UFR of Sciences and Technologies Alassane Ouattara Bouak Laboratory of Plant Biology and Earth Sciences Bouak Cte dIvoire UFR/STRM Flix Houphout Boigny de Cocody Abidjan Cte dIvoire PETROCI Consultant at the Center for Analysis and Research Department of Sequential Stratigraphy Abidjan Cte dIvoire

The use of sequential stratigraphy concept, based on well logs, sedimentology, and biostratigraphy, has shed light on the complex mechanisms controlling sedimentary accumulations. Consequently, identifying these mechanisms allows us to predict the hydrocarbon generation potential of source rocks. In the Ivorian offshore sedimentary basin, certain studies have contributed to understanding and characterizing the petroleum system. However, these previous works did not integrate biostratigraphic data to highlight sedimentary facies. This study, conducted on two wells in the Abidjan margin, is crucial as it helps us comprehend the geometry of fossil sediments in relation to sea level variations. It will also aid in reconstructing the basin-filling history and predicting the distribution of rocks capable of trapping oil, determining lowstand systems tracts (reservoir rocks), transgressive systems tracts, and highstand systems tracts (cap rocks). Lithological analysis revealed predominantly clayey sedimentation with sandy layers. Well log data facilitated the delineation of formation boundaries and highlighted reservoirs consisting of sands, sandstones, limestones, and occasionally intercalated shales. Integrating these analysis results with biostratigraphic interpretations based on foraminifera and palynomorphs revealed that the traversed formations were deposited in a transitional environment ranging from Coniacian to Maastrichtian ages. Applying sequential stratigraphy concept from well logging resolved dating issues encountered in microfossil-poor or microfossil-free zones. The results of the Coniacian-Maastrichtian age sequential subdivision were aligned with the chart.

关键词： Sequence Stratigraphy Systems Tracts Senonian Côte d’Ivoire

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Improvement of Cashew Apple Juice (Anacardium occidentaleL.) by Association with Passion Fruit Juice (Passiflora edulis)

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Food and nutrition Sciences 2021年第7期12卷 787-804页

作者： Marc Adou yao Désiré Adjouman Kouadio Olivier Kouadio Achille Fabrice Tetchi n’guessan Georges Amani UFR des Sciences et Technologies des Aliments Université Nangui Abrogoua Abidjan C&ocirc te d’Ivoire Centre Suisse de recherches Scientifiques en Cô te d’Ivoire (CSRS-CI) Abidjan CCentre Suisse de Recherches Scientifiques en C&ocirc te d’Ivoire (CSRS-CI) Abidjan C&ocirc te d’Ivoirete d’Ivoire

Despite many advantages, the many technologies studied to eliminate astringency from cashew apple juice are not all accessible and not adopted by processors due to the lack of financial means to access these sophistic... 详细信息

Despite many advantages, the many technologies studied to eliminate astringenn>cy from cashew apple juice are not all accessible and not adopted by processors due to the lack of financial means to access these sophisticated technologies. Thus, the formulation of mixed juice based on cashew apple juice and passion fruit juice has proved to be a way of adding value to the cashew apple, a co-product of the production of the nut. After the formulation of the mixed juice in different proportions and the sensory evaluation, it appears that the juice of formulation E is more appreciated by the tasters. Indeed, this juice has preferred sensory characteristics in terms of color (6.90), flavor (5.47), odor (6.42), settling (6.28) and overall acceptance (6.53). These characteristics are similar to those of passion fruit juice in terms of color, odor, and overall acceptance, where the latter obtained scores of 6.94, 7.17 and 6.00 respectively;and also, to those of cashew apple juice in terms of flavor and decanting, where the latter obtained scores of 5.19 and 6.14 respectively. Therefore, the addition of passion fruit juice to cashew apple juice results in a new product that is more appreciated when mixed with proportions of 90 mL of passion fruit juice and 10 mL of cashew apple juice. For example, passion fruit juice, due to its color, flavor, and odor, has helped reduce the pronounced astringency of raw cashew apple juice. Ultimately, formulation E is recommended to improve the organoleptic value of cashew apple juice.

关键词： Cashew nut Cashew Apple Juice Passion Fruit Juice Sensory Analysis

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Mother-to-Child HIV Transmission Factors in Exposed Children at University Hospital Center of Treichville (Abidjan, Cote d’Ivoire)

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Open Journal of Obstetrics and Gynecology 2017年第12期7卷 1198-1208页

作者： Edouard n’guessan Jean Marc Lamine Dia Mouhideen Oyelade Ignace yao Privat Guié Simplice Anongba Department of Obstetrics and Gynecology University Hospital of Treichville Abidjan Cote d’Ivoire

Background: The elimination of HIV transmission from mother to child is currently possible. Cote d’Ivoire, which has a 4.6% HIV prevalence among women, is one of 22 pilot countries for the elimination of mother-to-child transmission of HIV. Since 2015, Cote d’Ivoire has adopted new strategies according to the WHO B+ guidelines. Objective: To identify factors associated with mother-to-child HIV transmission in children born of seropositive mothers managed at Treichville university hospital. Material and methods: A case-control study was conducted in the obstetrics department at Treichville university hospital, between January 2013 and December 2015. It involved children born to mothers infected with HIV, whose first PCR (Polymerase Chain reaction) result was available during this period. A standardized questionnaire on data related to exposed children and their mother was used. Factors associated with mother-to-child HIV transmission were investigated using logistic regression. results: A total of 214 HIV-exposed children were included in the study with a sex ratio of 0.9. The majority of the children were born by vaginal route (52.8%) and received post-exposure prophylaxis (88.3%) and replacement feed (51.9%). Their mothers received antiretroviral therapy during pregnancy in 45.3% of the cases. The first PCR was performed at the sixth week of life in 52.3% of cases. The prevalence of HIV infection in exposed children was 7.5% (95% CI = 4.5% - 11.8%). In multivariate analysis, the absence of antiretroviral prophylaxis in children [aOR = 4.3, 95% (1.2 to 15.6), p = 0.03], the mixed feed [aOR = 3.8, 95% (1.1 - 13.1), p re to take antiretroviral regimen during pregnancy [aOR = 8.0, 95% CI (1.9 - 32.4), p re associated with mother-child HIV transmission. Conclusion: The mother-to-child HIV transmission rate remains high in our practice. Strategies to reduce situations that do not comply with current recommendations should be considered to pr

关键词： HIV-Exposed Children Mother-to-Child Transmission DBS/PCR

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