Etude Comparative de Deux Garnitures (Noix de Pain de Singe et de Jujube) Dans une Colonne Garnie: Hydrodynamique et Transfert de Matière

Pour bien comprendre l’efficacité de transfert de matière dans les biofiltres, les paramètres hydrodynamiques et de transfert de matière ont été étudiés pour deux garnitures différentes (noix de pain de singe et de jujube) dans un réacteur triphasé à lit fixe fonctionnant à co-courant gaz-liquide. Dans le cadre de ce travail, après la caractérisation des graines une étude d’hydrodynamique et de transfert de matière de l’oxygène a été faite. Les expériences ont été réalisées au sein d’une colonne en verre cylindrique de 0,1 m de diamètre et 1,5 m de hauteur. Cette dernière a été remplie avec des noix de pain de singe ou de jujube comme matériaux de garnissage. Les résultats obtenus ont montré que les pertes d’énergie ou la chute de pression (P) est 3,1875 cmCE contre 0,725 cmCE en moyenne respectivement pour le pain de singe et le jujube, la rétention liquide dynamique (εLD) est 0,223 contre 0,348 en moyenne respectivement pour le pain de singe et le jujube ainsi que la capacité d’oxygénation (CO) est 70,282 g.m-3 .h-1 contre 163,674 g.m-3 .h-1 en moyenne respectivement pour le pain de singe et le jujube. Au vue de ces résultats, les noix de jujube présentent sur tous les plans, les meilleures caractéristiques pour être utilisés comme matériaux de garnissage en vue des études pilotes ultérieures. To fully understand the mass transfer efficiency in biofilters, hydrodynamics and mass transfer parameters were investigated for two different fillings (monkey bread and jujube) in a three-phase fixed-bed reactor operating at co-flow gas-liquid. As part of this work, after the characterization of seeds a hydrodynamic study and transfer of oxygen mass were made. The experiments were carried out in a cylindrical glass column 0.1 m in diameter and 1.5 m in height. The latter wasfilled with monkey bread or jujube as filling materials. The results obtained showed that the energy losses or the pressure drop (P) is 3.11875 cmCE against 0.725 cmCE on average respectively for monkey bread and jujube, the dynamic liquid retention (εLD) is 0.223 against 0.348 on average respectively for monkey bread and jujube and the oxygenation capacity (OC) is 70.282 gm-3 .h-1 against 163.674 gm-3 .h-1 on average respectively for monkey bread and jujube. As a result, jujube nuts have the best characteristics on all levels for use as packing materials for pilot studies

Détermination du débit de filtration glomérulaire au cours de la drépanocytose au Sénégal: Schwartz, Cockcroft et Gault, MDRD, CKD-EPI ou JSCCS ?

La détermination du Débit de Filtration Glomérulaire (DFG) est importante chez les drépanocytaires du fait qu’ils constituent un groupe de patients chez lesquels des atteintes rénales sont fréquemment décrites notamment l’hyperfiltration glomérulaire. Dès lors, à une époque où les calculateurs en ligne proposent simultanément différentes formules de détermination du DFG, il serait important d’évaluer au sein d’une population noire africaine drépanocytaire l’équivalence entre ces formules qui ont été développées et validées sur des populations caucasiennes et afro-américaines à DFG normal ou diminué. Ainsi cette étude avait pour but d’évaluer l’interchangeabilité des différentes formules de détermination du DFG en les appliquant à des drépanocytaires. Des enfants et adultes sénégalais drépanocytaires homozygotes ont été alors recrutés et leur DFG calculé. La fréquence de l’hyperfiltration glomérulaire et celle de l’insuffisance rénale ont été calculées à partir des résultats obtenus avec les formules de Schwartz et du CKD-EPI. La concordance des différentes formules a été évaluée avec la méthode Bland-Altman. Au total 56 adultes et 62 enfants ont été inclus dans l’étude. L’insuffisance rénale a été notée chez 1,78% des adultes et 9,68% des enfants ; l’hyperfiltration glomérulaire chez 66,10% des adultes et 25,8% des enfants. Par rapport aux formules de référence (CKD-EPI, Schwartz), tous les biais relevés étaient significativement différents de zéro à l’exception de celui de Cockcroftet Gault qui était statistiquement nul. Les limites de concordance étaient toutes inacceptablement larges par rapport aux limites attendues à l’exception de celles du CKD-EPI sans ajustement sur la race. Ainsi, la formule de Schwartz n’était pas interchangeable avec celle du JSCCS chez les enfants, tout comme celle du CKD-EPI ne l’était pas non plus avec celles du JSCCS, de Cockcroft, du MDRD ou du CKD-EPI sans ajustement sur la race chez les adultes drépanocytaires.   English title: Determination of glomerular filtration rate in sickle cell disease in Senegal: Schwartz, Cockcroft and Gault, MDRD, CKD-EPI or JSCCS? Determination of Glomerular Filtration Rate (GFR) is important in patients living with sickle cell disease (SCD) because they constitute a group of patients where kidney dysfunction is frequently described, in particular glomerular hyperfiltration. Therefore, at a time when online calculators simultaneously propose different formulas to estimate GFR, it would be important to evaluate in a black African population living with SCD the equivalence between these formulas which have been developed and validated on Caucasian and African American populations with normal or decreased GFR. Thus, the aim of this study was to evaluate interchangeability of different GFR formulas in a group of patients living with SCD. Homozygous Senegalese sickle cell children and adults were then recruited and their GFR computed using Schwartz and JSCCS in children, Cockcroft and Gault, CKD-EPI with and without adjustment for ethnicity, MDRD and JSCCS formulas in adults. The frequency of glomerular hyperfiltration and renal failure was computed based on the results generated using Schwartz and CKD-EPI formulas. The agreement between formulas was assessed with BlandAltman method. A total of 56 adults and 62 children were included in this study. Renal failure was observed in 1.78% of adults and 9.68% of children; glomerular hyperfiltration in 66.10% of adults and 25.8% of children. Compared with reference formulas (CKD-EPI, Schwartz), all biases found were significantly different from zero except for Cockcroft and Gault formula bias, which was statistically zero. The limits of agreement were all unacceptably wide compared with the expected limits with the exception of CKD-EPI without adjustment for ethnicity. Thus, Schwartz formula would not be interchangeable with JSCCS formula in children, nor was the CKD-EPI formula interchangeable with the JSCCS, Cockcroft and Gault, MDRD or CKD-EPI without adjustment for ethnicity formulas in adults living with sickle cell anemia

Optimization of cristal violet adsorption by calcium silicate waste material

In this study, calcium silicate waste material was used as adsorbent of crystal violet in batch mode. The calcium silicate was synthesised from fluosilicic acid (FSA), which is a by-product of phosphoric acid manufacture. The obtained calcium silicate was characterised by X-ray fluorescence spectroscopy. The response surfaces, through the Box-Behnken model were used to model and optimize various adsorption parameters namely, the initial concentration of CV (A: 10–100 mg/L), the contact time (B: 5–50 min), the dose of adsorbent (C: 1–5 g/L) and the pH (D: 3–10). The removal efficiency of CV (97.86%), after statistical analysis, was obtained under the following optimal conditions: an adsorbent dose of 3.349 g/L, an initial CV concentration of 58 mg/L, a pH of 6.87 and a contact time of 30.49 min. The study of the four factors effects highlighted a positive effect on the removal of crystal violet. The interactions between adsorption time (B) and pH (D) and between adsorbent dose (C) and pH (D) were significantly important. However, an intermediate situation was noticed in the case of the interaction between adsorbent dose (C) and crystal violet concentration (A), where the lines cannot be considered parallel but do not cross each other in the analysed area either. The analysis of the residues showed that they are normally distributed and fluctuate in a random pattern. The adsorption kinetics were well described by the pseudo second order model and the equilibrium data were in agreement with the Langmuir isotherm model with a maximum adsorption capacity of 277.78 mg/g

Modelling and Optimizing the Removal of Methylene Blue by a Mixture of Titaniferous Sand and Attapulgite Using Complete Factorial Design

This paper focuses on the removal of methylene blue by adsorption using a mixture of titaniferous sand and attapulgite. The different adsorbents were characterized by X-ray fluorescence spectroscopy and their different parameters such as pH, zero charge potential, and specific surface area were determined. The experiments performed were optimized and modeled by a full 2-level and 4-factor design. The four factors are the ratio of titaniferous sand and attapulgite, the concentration of methylene blue, pH, and time. These vary from 4 to 19, 20 to 100 mg/L, 2 to 9, and 30 to 150 min respectively. The study of the effects of the different factors showed that the effect of methylene blue concentration and pH significantly influence the adsorption capacity and removal efficiency of the dye. The optimum parameters (adsorbent ratio, adsorbate concentration, pH and time) obtained for the adsorption capacity through the desirability function are: 19, 100mg/L, 9 and 150min. Those obtained for the yield are: 4, 100mg/L, 9, 150min. The pseudo second order adsorption kinetics gave an equilibrium adsorption capacity qe (calculated) = 7.6863 mg/g which is almost equal to that obtained experimentally qe (exp) = 7.3562 mg/g. This shows that the pseudo second order kinetic model is the adequate mathematical model to describe the methylene blue adsorption phenomenon on the mixture of titaniferous sand and attapulgite. The thermodynamic study showed that the methylene blue adsorption reaction is exothermic, non-spontaneous, and the degree of disorder of the particles at the adsorbing surface decreases

Polycyclic Aromatic Hydrocarbon (PAH) Contents of Four Species of Smoked Fish from Different Sites in Senegal

Polycyclic aromatic hydrocarbons (PAHs) are compounds resulting from any incomplete combustion process. These are pollutants that have proven toxicity due to their carcinogenic nature and can contaminate food during traditional smoking methods. Their highly toxic effect on human health requires monitoring of their levels in food products and the development of appropriate analytical methods for their determination. Thus, this study was conducted to assess the level of PAHs contamination of four (4) species of smoked fish (Arius heudelotii, Sardinella aurita, Ethmalosa fimbriata, and Sardinella maderensis) which were sampled in seventeen (17) localities in Senegal. The compounds targeted in this study were benzo(a)pyrene (B(a)P), benzo(a)anthracene (B(a)A), benzo(b)fluoranthene (B(b)F), and chrysene (Chr). The QuEChERS method was used for the extraction of PAHs, and their contents were quantified by gas chromatography (GC) coupled with mass spectroscopy (MS). The validation method was performed in accordance with the French standard NF V03-110 (2010). Satisfactory linearity (R2 > 0.999), LOD (0.05–0.09 μg/kg), LOQ (0.19–0.24 μg/kg), and precision (1.33–3.13%) of the four PAHs were obtained. The results of analysis in the 17 localities showed that all samples are contaminated by the four (4) PAHs with great variability of the contents between the different species and their origin. The B(a)P and ∑4PAHS contents in the samples ranged from 1.7 to 33 µg/kg and from 4.8 to 1082.3 µg/kg, respectively. Twelve (12) samples showed high levels of B(a)P, ranging from 2.2 to 33 µg/kg, thus exceeding the maximum authorized level (2 µg/kg). Fourteen (14) samples showed an overall ∑4PAHS content varying from 14.8 to 1082.3 µg/kg, which is above the maximum authorized limit (12 µg/kg). The principal component analysis showed that sardinella (Sardinella aurita and Sardinella maderensis) have very low levels of B(a)P, B(b)F, B(a)A, and Chr contents. However, high ∑4PAHS contents characterize smoked fish of the Kong species (Arius heudelotii), from Cap Skiring, Diogne, Boudody, and Diaobé, and of the Cobo species (Ethmalosa fimbriata) from Djiffer. Thus, based on the authorized limits for PAHs in smoked fish, it appears that smoked fish of the sardinella species are less carcinogenic for human consumption

Dégradation du cristal violet par électro-oxydation sur électrodes de Ti/TiO2 et Ti/TrO2-RuO2 : étude de l’influence des paramètres opératoires sur l’efficacité du procédé

Ce travail est une comparaison des capacités d’électro-oxydation du cristal violet sur des électrodes de Ti/TiO2 et Ti/IrO2-RuO2. Les résultats révèlent que le dépôt d’oxyde de métaux semi-conducteurs sur un support métallique adéquat tel que le titane permet d’améliorer l’activité électrochimique de ces électrodes. De même que l’influence des paramètres opératoires que sont la densité de courant (4,4, à 6,6 mA∙cm-2), la concentration de l’électrolyte (0,5 à 1,5 g∙L-1), la concentration initiale du colorant (2,5 x 10-5 à 10-4 M) et la surface d’électrode (4,55, 5,85 et 7,15 cm2) sur l’efficacité du traitement serait liée à la nature de l’électrode. Le suivi de la demande chimique en oxygène (DCO) au cours de l’électrolyse montre que Ti/IrO2-RuO2 possède le meilleur rendement épuratoire, puisqu’il permet d’atteindre un taux de réduction de la DCO de 92 % comparativement à un taux de 83 % enregistré dans le cas de Ti/TiO2 au bout de 2 h de traitement.The degradation of crystal violet in aqueous solution has been studied by an electro-oxidation process using Ti/TiO2 and Ti/IrO2-RuO2 anode electrodes. The study reveals that the deposition of metal oxide on a suitable metal support, such as pure titanium, improves the electrochemical activity of the electrodes. Different operating parameters were investigated such as current density (4.4 to 6.6 mA∙cm-2), initial concentration of dye (2.5 x 10-5 to 10-4 M), supporting electrolyte concentration (0.5 to 1.5 g∙L-1) and electrode surface (4.55, 5.85 and 7.15 cm2). The best performances of the electrolytic system were recorded using Ti/IrO2-RuO2 and 92% of COD could be removed in 2 h. By comparison, a maximum of 83% of COD could be removed using Ti/TiO2 for a similar imposed treatment time of 2 h

First Description of the Extended Spectrum-Beta-Lactamase Gene blaCTX-M-109 in Salmonella Grumpensis Strains Isolated from Neonatal Nosocomial Infections in Dakar, Senegal.

Nosocomial infections are very common in African hospitals, particularly in neonatal units. These infections are most often caused by bacteria such as Escherichia coli, Klebsiella spp and Staphylococcus spp. Salmonella strains are rarely involved in nosocomial infections. Here, we report the first description of S. Grumpensis in neonatal infections in Senegal. Seventeen Salmonella strains were isolated from hospitalized infants' stool samples. The following resistance phenotype was described in strains: AMXRTICRCFR FOXRCFXRCTXRCAZRIMPSATMRNARNORRCIPRTMRGMRTERSXTR. All isolates were susceptible to imipenem, 15 out of 17 produced an extended spectrum ß-lactamase (ESBL). blaOXA-1, blaSHV-1, blaTEM-1, blaCTX-M1 genes were detected in strains 8, 13, 5 and 8, respectively. blaCTX-M1 sequencing revealed the presence of blaCTX-M-109. Thirteen of the 17 Salmonella Grumpensis strains were analyzed by PFGE. These 13 isolates belonged to a single pulsotype and were genotypically identical. This is the first report of neonatal S. Grumpensis infections in Senegal, and the first report of blaCTX-M-109 in the genus Salmonella

First Detection of the West Nile Virus Koutango Lineage in Sandflies in Niger

West Nile virus (WNV), belonging to the Flaviviridae family, causes a mosquito-borne disease and shows great genetic diversity, with at least eight different lineages. The Koutango lineage of WNV (WN-KOUTV), mostly associated with ticks and rodents in the wild, is exclusively present in Africa and shows evidence of infection in humans and high virulence in mice. In 2016, in a context of Rift Valley fever (RVF) outbreak in Niger, mosquitoes, biting midges and sandflies were collected for arbovirus isolation using cell culture, immunofluorescence and RT-PCR assays. Whole genome sequencing and in vivo replication studies using mice were later conducted on positive samples. The WN-KOUTV strain was detected in a sandfly pool. The sequence analyses and replication studies confirmed that this strain belonged to the WN-KOUTV lineage and caused 100% mortality of mice. Further studies should be done to assess what genetic traits of WN-KOUTV influence this very high virulence in mice. In addition, given the risk of WN-KOUTV to infect humans, the possibility of multiple vectors as well as birds as reservoirs of WNV, to spread the virus beyond Africa, and the increasing threats of flavivirus infections in the world, it is important to understand the potential of WN-KOUTV to emerge

Emergence of Crimean–Congo Hemorrhagic Fever Virus in Eastern Senegal in 2022

Crimean–Congo hemorrhagic fever (CCHF), the most widespread tick-borne viral human infection, poses a threat to global health. In this study, clinical samples collected through national surveillance systems were screened for acute CCHF virus (CCHFV) infection using RT-PCR and for exposure using ELISA. For any CCHF-positive sample, livestock and tick samples were also collected in the neighborhood of the confirmed case and tested using ELISA and RT-PCR, respectively. Genome sequencing and phylogenetic analyses were also performed on samples with positive RT-PCR results. In Eastern Senegal, two human cases and one Hyalomma tick positive for CCHF were identified and a seroprevalence in livestock ranging from 9.33% to 45.26% was detected. Phylogenetic analyses revealed that the human strain belonged to genotype I based on the available L segment. However, the tick strain showed a reassortant profile, with the L and M segments belonging to genotype I and the S segment belonging to genotype III. Our data also showed that our strains clustered with strains isolated in different countries, including Mauritania. Therefore, our findings confirmed the high genetic variability inside the CCHF genotypes and their introduction to Senegal from other countries. They also indicate an increasing CCHF threat in Senegal and emphasize the need to reinforce surveillance using a one-health approach