<p>In the present study, adsorption experiments were carried out to investigate the removal of rhodamine B from an aqueous solution using chemically activated carbon from corn cobs, a cheaper adsorbent. The characteristics of carbon were determined using X-ray diffraction, SEM, iodine number, pHpzc, and the Boehm titration method. The results show that the prepared activated carbon is amorphous, microporous, and generally acidic on the surface. The kinetic study of the adsorption of rhodamine B on this carbon was carried out, and the rate of sorption was found to conform to pseudo-second-order kinetics with 80 min as equilibrium time. The equilibrium adsorption revealed that the experimental data fitted better to the Langmuir isotherm model for removing rhodamine B. The interaction rhodamine B-activated carbon is mainly chemisorption type. The optimal conditions of rhodamine B removal onto the carbon of this study are mass of carbon = 0.3 g and pH = 3.15. The maximum monolayer adsorption capacity for rhodamine B removal was found to be 5.92 mg.g^-1. This study has shown that the prepared activated carbon makes it possible to effectively clean up wastewater contaminated by rhodamine B with a removal efficiency of up to 99.60% for 300 mg of AC in 25 mL of the rhodamine B solution (5 mg.L^-1).</p>

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Introduction: Cutaneous squamous cell carcinoma encompasses about 16% of scalp tumors. They can arise de novo or more often mark the evolution of lesions considered as non-invasive precursors: actinic keratoses and Bowen's disease more rarely, they occur on a burn scar (Marjolin's ulcer). We report a case of invasive squamous cell carcinoma on a burn scar (Marjolin's Ulcer) operated with reconstruction by advancement flap completed by a skin graft performed at the Sominé Dolo hospital in Mopti (Mali). A 62-year-old Malian man consulted for a scalp ulceration that had been evolving for 10 years. The lesion began with small trailing erosion that appeared on a burn scar. There was no notion of initial trauma and the patient had no particular history. Physical examination found a large ulceration (6×4 cm) of parietal seat on the scalp with a fibrinous bottom and a sclerotic border. There was a large left latero -cervical mass measuring 13 x 6 cm. The computed tomography of the skull did not find any bone lesions and that of the latero -cervical mass was in favor of adenopathy. Histological examination of a biopsy fragment confirmed the diagnosis of invasive squamous cell carcinoma. Deep resection removing the tumor with the periosteum exposing the parietal bone was performed. Reconstruction by advancement-rotation flap supplemented by a skin graft was performed. The management of squamous cell carcinoma is based on surgery, which is the reference treatment, against which other treatments must be compared. On the scalp, Rotation-advancement flaps are the preferred one-stage surgical repair technique.

This study showed that the oxidation of rhodamine B by the Fenton process is a very fast method because the reaction takes place within the first 20 minutes. The mixture of Fe2+ and H2O2 produces hydroxide radicals responsible for the degradation of rhodamine B. The study of pH influence on the rhodamine B oxidation reveals that for maximum oxidation of rhodamine B, the pH must be less than or equal to 2. For pH > 2, there is a decrease in rhodamine B oxidation. This is due to side reactions that occur if the concentration of Fe2+ is high. This reduces the amount of oxidized rhodamine B. We note that the oxidation of rhodamine B is faster for low concentrations than for high concentrations of rhodamine B. According to our results, for a maximum oxidation of 5 mg / L of rhodamine, it takes 8.4.10−4 mg / L of Fe2+, 3.10−3 M of H2O2 and pH = 2. This work also showed that the presence of inorganic ions strongly slows down the rate of degradation of rhodamine in the following order: Cl− ˂ NO3− ˂ SO42− ˂ PO43−.

Lake Fitri is the second largest lake ecosystem in terms of area after Lake Chad. The purpose of this study was to assess the socioeconomic, technical and environmental aspects of fishing and to determine some physico-chemical characteristics of the waters from Lake Fitri in Chad. Surveys were carried out from March 03 to April 08 and from July 10 to August 06, 2019 among 400 fishermen, processors and merchants from four islands of Lake Fitri where there is a high level of fishing activity. Standard methods were applied for the physico-chemical analysis of the water. The results revealed that fishing was mainly practiced by 74%, 10%, 15% and 1% respectively of Chadians, Nigeriens, Nigerians and Cameroonians. Marketing is carried out by 60% of Chadians, 20% of Nigerians and 20% of Nigerians. The study found a use of a variety of fishing gear and techniques, including 26% of longlines, 16% of standing nets, 25% of nets with polystyrene floats and 39% of nets. Financial contributions show that fishing represents a significant source of currency for this department. The water of the 4 islands of Lake Chad had mean pH, temperature and conductivity values of 8.90 ± 0.66, 25.61 ± 1.75 °C and 363.26 ± 75.41 mS/cm respectively. Water turbidity ranged from 0.33 to 0.90 with a mean of 0.55 ± 0.17 NTU, dissolved oxygen ranged from 13.46 to 19.17 mg/L with a mean of 17.04 ± 1.68 mg/L. There was a significant difference between the values for temperature, turbidity and dissolved oxygen (p<0.0001), but no difference was observed for pH and electrical conductivity. Catches remain below the potential indicated by the FAO for water bodies of this type (between 100 and 750 kg.ha-1 .year-1), which shows that there may be room for increasing fish production of this lake. The very lax management and use of fishing gear (traps) observed in these sites could constitute a threat to the maintenance of biodiversity and the productivity of natural ecosystems.