Search

Due to the issues related to the evolution of the seabed, the determination of the retreat or advancement of the ocean has been the subject of numerous scientific studies. Coastal areas are among the most dynamic places on the planet. Most of the coasts in the world are affected by the phenomenon of coastal erosion, in particular the coast of Benin. On the coast of Benin and in the Gulf of Guinea in general, the dynamics of the coastline is not a recent phenomenon but its scale has increased over the last decades. This erosion is the consequence of the impact of the swells. Identifying the causes of seabed dynamics in coastal areas is essential to understanding the physics of the phenomenon. This work emphasizes the different parameters that influence the morphodynamic evolutions of the beach and the coastline in this coastal area. The study is based on data obtained from the IRHOB (Institute of Halieutic and Oceanographic Research of Benin) of the CBRST (Benin Center for Scientific and Technical Research) on swells. This data was recorded with a time interval of 5 minutes; this allowed us to model the evolution of the coastline of the Benin coast. The results obtained show the major causes of the dynamics of the seabed on this coast in recent years.

The thermal characteristics of a typha-starch composite have been determined in this study in order to improve thermal comfort of the buildings in tropical environments. From six samples of this mixture of granulometry (0.425 mm; 1.25 mm and 1.70 mm), the kinetics of the water desorption have been characterized and the thermal properties of these materials were also studied. The results obtained indicate that the samples have a high rate of water desorption recorded in the first ten and fifteen days with proportions in loss of water which vary from 7% to 18.75%. The thermal conductivity obtained for samples without a binder (starch) varies from 0.1046 W.m−1K−1 to 0.1242 W.m−1K−1 and from 0.094 W.m−1K−1 to 0.5345 W.m−1K−1 for the composites. The thermal diffusivity evolves between 9.010−8 m².s−1 and 3.77.10−7m².s−1. In view of these results and according to the American National Standards Institute (ANSI 208, 1999), all the samples prepared except the formulation (0.425 mm + 20% starch) have good thermal properties for improving thermal comfort of buildings and the composite fraction (typha 1.70 mm + 20% starch) seems to be the optimal composition. The latter could be recommended as a local available insulation material to be integrated into the buildings in tropical environments in the form of sub-ceiling, instead of the widely used Isorel insulation panels (k = 0.82 W.m−1K−1) and plywood panels (k = 1.08 W.m−1K−1) of higher thermal conductivities and cost. For the first time in Africa, such a combination of local materials (Typha-amidon) used to improve energy efficiency has been demonstrated on the roof of the building envelope. The resulting scientific advances are linked to the originality of the formulation and the proportions of each material used to obtain the best composite. The development impacts of its implementation are directly linked to Sustainable Development Goals 1, 2, 7, 8, 14 and 15 (SDGs), as well as the African Union's Agenda 2063.

The characteristics of the wind vertical profile over the coast of Cotonou during wind convective diurnal cycle were explored in this study. Wind data at 10 m above the ground and the radiosonde data in the lower 60 m of the surface boundary layer were used over the period from January 2013 to December 2016. Based on Monin–Obukhov theory, the logarithmic and power laws have allowed characterizing the wind profile. The error estimators of the Root Mean Square Error (RMSE) and the Mean Absolute Error (MAE) were, respectively, evaluated at 0.025; 0.016 (RMSE; MAE) and 0.018; 0.015. At the site of Cotonou, the atmosphere is generally unstable from 09:00 to 18:00 MST and stable for the remainder of the time. The annual mean value of the wind shear coefficient is estimated at 0.20 and that of the ground surface roughness length and friction velocity are, respectively, of 0.007 m, 0.38 m·s−1. A comparative study between the wind extrapolation models and the data was carried out in order to test their reliability on our study site. The result of this is that whatever the time of the year is, only the models proposed (best fitting equation) are always in good agreement with the data unlike the other models evaluated. Finally, from the models suitable for our site, the profile of wind convective diurnal cycle was obtained by extrapolation of the wind data measured at 10 m from the ground. The average wind speed during this cycle is therefore evaluated to 8.07 m·s−1 for August which is the windiest month and to 4.98 m·s−1 for the least windy month (November) at 60 m of the ground. Considering these results, we can so consider that the site of Cotonou coastal could be suitable for the installation of wind turbines.

Today, we observe at the population level, that the improvement in comfort is accompanied by an increase in the electrical energy required. The predicted exhaustion of fossil energy resources maintains some speculation. Their unequal geographical distribution justifies the energy dependence of Benin overlooked from outside. So it is urgent to explore the various sources of renewable energy available to Benin. In this work, using measurements made ​​by the Millennium Challenge Account (MCA-Benin) as part of the extension of the port of Cotonou, with Boussinesq equations (Peregrine) and Stokes waves dispersion relation, we characterized the variations of various swell parameters (height, wavelength, velocities) in the shoaling zone on the study site and proceeded to estimate variations in wave energy power from deep waters to the bathymetric breaking point. Finally, the zone with high energy power (where the conversion of this energy into electrical energy would be profitable) of these waves is highlighted on the site, the local water depth at the point of breaking waves is evaluated and results obtained allowed to justify the very energetic character take by these swells on this coast when they are close to the beach.

Abstract E. coli and most other diderm bacteria (those with two membranes) have an inner membrane enriched in glycerophospholipids (GPLs) and an asymmetric outer membrane (OM) containing GPLs in its inner leaflet and primarily lipopolysaccharides in its outer leaflet. In E. coli, this lipid asymmetry is maintained by the Mla system which consists of six proteins: the OM lipoprotein MlaA extracts GPLs from the outer leaflet, and the periplasmic chaperone MlaC transfers them across the periplasm to the inner membrane complex MlaBDEF. However, GPL trafficking still remains poorly understood, and has only been studied in a handful of model species. Here, we investigate GPL trafficking in Veillonella parvula, a diderm Firmicute with an Mla system that lacks MlaA and MlaC, but contains an elongated MlaD. V. parvula mla mutants display phenotypes characteristic of disrupted lipid asymmetry which can be suppressed by mutations in tamB, supporting that these two systems have opposite GPL trafficking functions across diverse bacterial lineages. Structural modelling and subcellular localisation assays suggest that V. parvula MlaD forms a transenvelope bridge, comprising a typical inner membrane-localised MCE domain and, in addition, an outer membrane ß-barrel. Phylogenomic analyses indicate that this elongated MlaD type is widely distributed across diderm bacteria and likely forms part of the ancestral functional core of the Mla system, which would be composed of MlaEFD only.

Fermentation has been used for centuries to enhance the sensory and nutritional qualities and the antioxidant content of plant-based foods, making them beneficial for health. This study aims to investigate the microbiological and nutritional qualities of fermented porridges produced in northern Benin. Various nutritional tests and the identification of different microorganisms have gained insights into eight porridges produced in 9 localities of northern Benin. Lactic acid bacteria have the highest proportion among all microorganisms in fermented porridges, followed by the total mesophyll aerobic flora. E. coli, thermotolerant coliforms, and molds are not present in all porridges analyzed. Recorded data suggested that porridges have a variable microbial load depending on the collection municipalities. The dry matter of the eight types of porridge varies greatly, with akloui having 27.03 ± 3.83 g/100 g and fourra having 48.63 ± 3.83 g/100 g. The total ashes also differ significantly, with bita having 39.36 ± 4.67 g/100 g and sagagnèga having 63.19 ± 4.67 g/100 g. It is worth noting that all fermented porridges have a pH lower than 5, and the titratable acidity ranges from 0.01 ± 0.00 g to 0.02 ± 0.00 g. The brix degree varies from 0.46 ± 0.54 to 4.4 ± 0.54. The beta-carotene values of the 8 types of porridge vary from 0.037 ± 0.018 mg/g to 0.138 ± 0.018 mg/g, while the total sugars range from 1.926 ± 0.877 to 5.773 ± 0.877 g/100 g. The lipid content, when present, varies from 0.226 ± 0.029% to 0.408 ± 0.029%. Finally, the protein percentage of the porridge ranges from 7.061 ± 0.779 to 12.419 ± 0.779.