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Electrochemical Analysis of Zirconiumin Aqueous and Organic Media

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American Journal of Analytical Chemistry 2024年第2期15卷 99-118页

作者： Paul Mendy Démo Koita Theodore Tzedakis Cheikhou Kane codou Guèye mar-diop Ecole Supérieure Polytechnique Université Cheikh Anta DIOP Dakar Sénégal Laboratoire de Génie Chimique Université de Toulouse III—Paul Sabatier Toulouse France

For the challenging nature of the zirconium environment analysis, this study consists to analyze the electrochemical behavior of Zirconium in both aqueous and organic media. To that end first the electrolytic media was selected on the basis of the Pourbaix potential-pH diagram, which provides informations on the predominance of Zr(IV) ion and Zr in aqueous media. In aqueous media, analyzes were first carried out in acidic media then in basic media. Studies have thus revealed that the acidic environment is not favourable for the electrochemical analysis of zirconium. Voltammograms obtained in an acidic environment show no zirconium detection signal;this is due to the strong presence of H+ ions in the solution. We have also observed in acidic media the phenomenon of passivation of the electrode surface. In aqueous alkaline media (pH = 13), we have drawn in reduction several Intensity-Potential curves by fixingsome technical parameterslike scanning speed, rotation speed of the electrode. The obtained voltammograms show cathodic waves, starting from -1.5 V/DHW and attributed to the reduction of Zr (IV) to Zr (0). The last phase of this study focused on the electrochemical analysis of zirconium in an organic media. In this media, several intensity-potential curves were plotted in reduction and in cyclic voltammetry with various parameters. Through several reduction analysis, the Zr (IV) was reduced to Zr (0) to the potential of -1.5 V/DHW. The electrochemical analysis of zirconium in organic media seems globally easier to achieve thanks to its large solvent window (i.e. dimethylformamide (DMF) solvent window > 6 V).

关键词： Zirconium Electrochemical Reduction Cyclic Voltammetry Voltammogram Dymethylformamide

Nutritional Potential of Two Leafy Vegetables Leptadenia hastataDecne and Senna obtusifoliaLink Consumed in Senegal

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Food and Nutrition Sciences 2018年第2期9卷 77-85页

作者： Nicolas Cyrille Ayessou Mady Cissé Mathieu gueye Cheikh Ndiaye codou mar diop 1Laboratoire d’Electrochimie et des Procédés Membranaires Centre d’Etudes sur la Sécurité Alimentaire et les Molécules Fonctionnelles-Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Laboratoire d’Electrochimie et des Procédés Membranaires Centre d’Etudes sur la Sécurité Alimentaire et les Molécules Fonctionnelles-Ecole Supérieure Polytechnique Université Cheikh Anta Diop Dakar Senegal Institut Fondamental d’Afrique Noire Cheikh Anta diop Département de Botanique et Géologie Université Cheikh Anta Diop Dakar Senegal Laboratoire des Biotoxines et Contrô le des Aliments Institut de Technologie Alimentaire (ITA) Route des Pères Maristes Dakar Senegal

This study focused on two woody leafy vegetables Leptadenia hastata Decne and Senna obtusifolia Link, commonly consumed in Senegal. Leaves were col-lected from three regions. Then, proximate analyses and micronutrients were carried out to evaluate their nutritional values. Results revealed that protein level of S. obtusifolia (SO) is richer (21.75%) than Leptadenia hastata (LH) (18.16%). The cellulose and carbohydrate contents of the two vegetable’s leaves are in the same order except those of LH from Widou which are less rich in cellulose (8.31%) and richest in carbohydrate (6.35%). These leaves are also good sources of various mineral elements and especially iron. Leaves of LH appear to be richer in iron and magnesium, while SO appears to be richer in calcium. Vitamin C intakes of SO leaves are better than those of LH and respectively range from 142 to 196.5 and 22.5 to 159.5 mg/100 g. According to the use of this leafy vegetable by the populations, a domestication opportunity is thus justified to ensure availability and accessibility of these significant sources of micronutrients.

关键词： Leptadenia hastata Senna obtusifolia Woody Leafy Vegetables Nutritional Values Domestication

Removal of Methyl Violet in Aqueous Solution on Activated Carbon Based on Saba senegalensis Shell Residues

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Journal of Geoscience and Environment Protection 2023年第5期11卷 197-208页

作者： Mouhamed Ndoye Mamadou Faye Cheikhou Kane Adama diop mar codou Guèye diop Water Energy Environment and Industrial Processes Laboratory Ecole Superieure Polytechnique (ESP) Dakar Senegal Cheikh Anta diop University Dakar Senegal

Adsorption on activated carbon is one of the most widely used methods for the removal of dyes. The objective of this study is to valorize the shells of Saba senegalensis from local product in Senegal in the form of activated carbon and to test its effectiveness for the removal of methyl violet. The study was carried out in batch mode for a maximum duration of one hour with 100 mL of solution treated at 600 rpm. The results reveal that the granulometry 500 μm gives the best yield with an adsorption rate of 95%, a mass of adsorbent of 0.2 g gives an adsorption capacity of 20 mg/g, the contact time of one hour with a capacity of 5 mg/g. The study also showed that the adsorption process of methyl violet is described by the pseudo-second order kinetic model with correlation coefficient of 0.99. Two adsorption isotherms were studied, and the results revealed that the Freundlich model better describes the adsorption of methyl violet on Saba senegalensis shell residue-based activated carbon (SSSRAC). The results indicate that SSSRAC could be used as a low-cost alternative for the removal of textile dyes such as methyl violet.

关键词： Methyl Violet Adsorption Activated Carbon Saba senegalensis Shell

Traditional Mead “Bessoudioury” from Senegal: Process and Characterization

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Food and Nutrition Sciences 2018年第12期9卷 1424-1433页

作者： Oumar Ibn Khatab Cisse Bou Ndiaye Papa Guedel Faye Nicolas Cyrille Ayessou Mathieu gueye Mady Cisse codou mar diop Ecole Supérieure Polytechnique Cheikh Anta Diop University Dakar Sénégal Centre d’Etudes sur la Sécurité Alimentaire et les Molécules Fonctionnelles (CESAM) Dakar Sénégal Institut Fondamental d’Afrique Noire (IFAN) Cheikh Anta Diop University Dakar Sénégal

Mead is a beverage obtained by alcoholic fermentation of honey, with an ethanol content of 8% to 18% by volume. In Africa, mead manufacturing methods rely on heating honey and adding extracts of fruits, herbs or spices. “Bessoudioury” mead is then prepared according to the traditional process of the Bassari and Bedick peoples of Kedougou (Senegal). This work on “Bessoudioury” aims to describe and characterize the manufacturing processes. It was also to evaluate the chemical and microbiological characteristics. The study focused on three Kedougou production sites. The manufacturing process of “Bessoudioury” includes a honey heating, a formulation step by adding wine of either Borassus aethiopicum mart. or Elaeis guineensis. This step is followed by a fermentation’s one during two days. Wine is considered as the essential sources of yeasts for the production of alcohol. “Bessoudioury” has an ethanol content of 8% (v/v). Moulds and Streptococcus were not detected in this mead. According to its polyphenols content, this mead has a nutritional interest, but the process deserves to be reviewed to preserve nutrients.

关键词： Honey Mead Fermentation Bessoudioury

Impact of Extraction Method on Physicochemical Characteristics and Antioxidant Potential of Adansonia digitataOil

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Food and Nutrition Sciences 2018年第8期9卷 937-955页

作者： Mady Cissé Alioune Sow Patrick Poucheret Delphine margout Nicolas Cyrille Ayessou Papa Guédel Faye Mama Sakho codou mar gueye diop Laboratoire de Formation Continue en Industries Agroalimentaire (LFCIA) ESP-UCAD Centre d’Etudes sur la Sécurité alimentaire et les Molécules fonctionnelles (CESAM-RESCIF) ESP-UCAD Dakar Senegal UMR Qualisud Université de Montpellier CIRAD Montpellier Supagro Université Avignon Université La Réunion Montpellier France

In this study, the effect of extraction processes on the physicochemical characteristics and antioxidant potential of baobab (Adansonia digitata L.) seed oil was evaluated. The oils were extracted, on the one hand, by cold pressing, and on the other hand, with three types of organic solvents (acetone, chloroform, n-hexane). The recorded results indicated that the extraction yield of baobab oil was significantly impacted by both the extraction method and the polarity of the solvent used. In addition, chloroform provides the best extraction yield (40.12 ± 0.607). However, extraction by cold pressure preserves at best the physicochemical and bioactive properties of the extracted oils. Indeed, the pressing oil contains a content of phenolic compounds (0.047 ± 0.0024 mgEAG/g of oil) and a very high radical scavenging activity (DPPH) (31.71% ± 0.61%). For the various oils extracted, the minimum and maximum values were 0.50 and 3.17 mEq?kg-1;56.26 and 99.113 mgI2?100 g-1;1.457 and 1.465;205.37 and 233.587 mgKOH/g respectively for the peroxide, iodine, refractive and saponification values. The color parameters (L*, a* and b*) of the oils also differ depending on the nature of the organic solvent used. Principal component analysis (PCA) and correlation analysis were performed on the physicochemical properties and the antioxidant potential of the extracted oils. Therefore, the results suggest the mixed use of acetone and hexane to obtain oil comparable to that extracted by cold pressing.

关键词： Adansonia digitata L. Oil Extraction Biochemical Characteristics

Antioxidant Activity of Hydro-Acetonic, Hydro-Methanolic and Aqueous Leaf and Bark Extracts of Sclerocaria birrea(A. Rich.) Hochst

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Food and Nutrition Sciences 2021年第5期12卷 429-438页

作者： Lahat Niang Seid Ali Mahamat Nicolas Cyrille Ayessou Mady Cisse codou mar diop Laboratory of Electrochemistry and Membrane Processes (LEPM) ESP-UCAD Dakar Sénégal Center for Studies on Food Safety and Functional Molecules (CESAM-RESCIF) ESP-UCAD Dakar Sénégal Adam Barka University Abeche Tchad

Bioactive compounds in plants are associated with the reduction of chronic diseases. The free radical scavenging activity of different extracts of a medicinal plant, Sclerocarya birrea, has been investigated using the DPPH test, ABTS test and FRAP. Three extracts were prepared from the leaves and bark: hydro-methanolic, hydro-acetonic and aqueous. Phytochemical screening was carried out the standard methods followed by the determination of the polyphenol by Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 and statistical significance was set at p 0.05. Evolution of percent inhibition (PI) as well as the IC50 of the extracts was obtained using the Origin Pro 8.5 software and Microsoft Excel. The results show that the bark extracts

关键词： Sclerocarya birrea Antioxidant Activity DPPH ABTS Total Phenolic

Phytochemical Screening, Total Phenolic and Antioxidant Activity of Numerous Extracts from Leaves and Bark of Bauhinia rufescensLam

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Food and Nutrition Sciences 2021年第6期12卷 544-556页

作者： Seid Ali Mahamat Niang Lahat Ayessou Nicolas Cyrille Cisse Mady diop codou mar Adam Barka University Abeche Tchad Water Energy Environment and Industrial Processes Laboratory (LE3PI) ESP-UCAD Dakar Sénégal Center for Studies on Food Safety and Functional Molecules (CESAM-RESCIF) ESP-UCAD Dakar Sénégal

Researches for natural antioxidants that play an important role in the prevention of diseases linked to free radicals have increased in recent years. In this study, antioxidant activity of Bauhinia rufescens Lam which is a medicinal plant was investigated. The methanol extract, acetone extract and water extract of leaf and trunk bark had antioxidant activity. Three methods were used: 2,2-diphenyl-1picryl-hydrazyl (DPPH), 2,2’-Azino-bis-(3-ethylbenzoth iazoline-6-sulfonic acid) (ABTS) and ferric ion reducing power (FRAP) by spectrophotometry. Phytochemical screening was carried out followed by the quantification of the total phenolic by the Folin-Ciocalteu method. The analysis of variance (ANOVA) with the STATISTICA 7.1 software revealed significant differences (p 0.05). Percentage inhibition (PI) and IC50 of the extracts were obtained using the OriginPro 8.5 software. These tests show that the bark is as rich in total phenolic as the leaves. The DPPH test shows that at 2.5 mg/ml, the bark and

关键词： Bauhinia rufescens Lam Total Phenolic Antioxidant Activity

Monitoring of Anthocyanins and Colour in Electrochemically Processed Hibiscus sabdariffaJuice

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Food and Nutrition Sciences 2021年第11期12卷 1073-1087页

作者： Khady Ndiaye Cheikhou Kane Omar Ben Khatab Cisse Nicolas Ayessou codou mar diop Laboratoire d’électrochimie et des Procédés Membranaires ESP/UCAD Dakar Sénégal Laboratoire de Formation Continue en Industrie Agroalimentaire ESP/UCAD Dakar Sénégal

The vital role of anthocyanins in Hibiscus sabdariffa L. is now known to most consumers. The richness of anthocyanins in antioxidants, vitamin C, minerals, etc., provides Hibiscus juice with proven nutritional qualities. The health requirements of recent years have made food products with added preservatives or processed at high temperatures less popular, thus explaining the new orientations towards innovative and interdisciplinary technologies. Anthocyanins from Hibiscus sabdariffa L. are, however, sensitive to degradation factors such as temperature, light, enzymes and also oxygen. The instability of anthocyanins has long been a subject of research using classic techniques such as heat treatment, the results of which are often limited by the rapid degradation and above all the destruction of the nutritional and organoleptic qualities of the product. Oxygen dissolved in juices is so far treated by bubbling with an inert gas or by adding other molecules such as preservatives which can cause a lot of health damage. The electrochemical approach is a new stabilisation technique that reduces the dissolved oxygen in the juice, cold and without the addition of other molecules. The electrolysis of Hibiscus juice was carried out by noble electrodes (Platinum and Stainless Steel) with a well-characterised Time/Potential or Time/Intensity couple. The electroreduced samples and the control were then stored at 4°C, 25°C and 37°C for more than 6 months. Monitoring of anthocyanins in the first month, of the samples and the control, showed a significant difference of 10% between the electroreduced extract and the untreated control at 37°C, which had previously been problematic for the heat treatment and even for the other membrane techniques. Oxygen reduction on the platinum electrode/ECS allowed the retention of more than 10% of anthocyanins after 4 weeks of storage at 25°C and 37°C. At 4°C, a sign

关键词： Monitoring Anthocyanin Colour Oxygen Stabilisation Electrochemical Nafion Membrane Ratio

Impact of Extraction on Biochemical Properties and Antioxidant Potential of Momordica charantia L. Seeds’ Oil

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Food and Nutrition Sciences 2022年第2期13卷 147-164页

作者： Balde Samba Ayessou Nicolas Cyrille Khadim Niane Bou Ndiaye Mady Cisse codou mar diop Centre d’Etude sur la Sécurité Alimentaire et les Molécules fonctionnelles (CESAM) Université Cheikh Anta DIOP de Dakar Fann Sénégal

In this study, the influence of provenance and extraction methods on the physicochemical properties and the antioxidant potential of M. charantia seeds oil were evaluated. The oil is obtained on the one hand by cold extraction with hexane and on the other hand by hot extraction with soxhlet. The results obtained show that the extraction yield is significantly impacted by the extraction methods and the origin of the seeds. In addition, the soxhlet extraction gives a higher oil yield (32.07 ± 0.01). Cold extraction has made it possible to obtain oils with less attenuated physicochemical characteristics. Indeed, the acid numbers are high in the oils extracted by soxhlet (5.92 ± 0.25;4.25 ± 0.62 and 13.86 ± 0.83) than in those cold extracted with very low peroxide for all the oils obtained. On the other hand, the iodine and refractive indices are high in oils obtained cold (91.58 ± 0.85;100.74 ± 0.03 and 102.08 ± 0.28) (1.53 ± 0.01;1.52 ± 0.01 and 1.52 ± 0.01) with low saponification indices. The polyphenol concentrations and the anti-free radical activity are higher with the oils obtained cold (0.086 ± 0.001;0.08 ± 0.000 and 0.09 ± 0.01 mgEAG/g of oil) and (DPPH) (55.75% ± 1.16%;55.03% ± 0.72% and 56.35% ± 0.45%). The color parameters (L*, a* and b*) of the different oils extracted also vary depending on the extraction method used. Principal Component Analysis (PCA) and correlation analysis were performed on the physicochemical properties and the antioxidant potential of the extracted oils. Therefore, the results suggest cold extraction to obtain a good quality and oxidation resistant oil.

关键词： Momordica charantia Oil Antioxidant Potential Extraction