The metasedimentary-hosted Nyangoubé gold prospect, northwest Côte d'Ivoire: Geochemical and mineralogical characterization of associated hydrothermal alteration.

The Nyangoubé gold prospect, located in northwestern northwest of Côte d'Ivoire in Africa, is a feature of the Bagoé furrow of the Birimian of the West African Craton. This study is aimed at characterizing the geochemical and mineralogical signatures of hydrothermal alterations associated with the gold mineralization of Nyangoubé gold prospect to provide guidelines for mining exploration. Microscopic petrographic analysis and geochemical characteristics from elemental contents analyzed by X-ray fluorescence (XRF) and inductive coupled-plasma mass spectrometer (ICP-MS) were studied using alteration diagrams and by calculating mass balances and describing thin sections. The results indicate that the host rocks have been affected by silicification, carbonation, sericitization, chloritization, sulphidation and albitization. Hydrothermal alterations associated with the mineralization systems resulted in the destruction of plagioclase in the metasediments studied. The latter was replaced by sericite, chlorite, carbonates, quartz, and sulphides in varying proportions, depending on the intensity of each type of alteration linked to the formation of each mineral. The mass balance calculations show a gradual increase in the concentrations of Au, W, V, As and Pb as well as K2O, CaO, Na2O and Fe2O3 which could be vectoring parameters towards gold mineralization. The mineralogical assemblage as sericite-chlorite-pyrite, chlorite-pyrite±sericite, carbonate-sericite and chlorite-carbonate revealed by hydrothermal alteration trends in the host rocks could also help identify potential gold corridors in the area of study and its peripheries.

Dissociation mechanism of methane hydrate by CaCl2: an experimental and molecular dynamics study.

The formation of gas hydrate is a serious threat to the safe and effective completion of deepwater drilling and transportation operations, although it is considered as a potential energy resource. The inorganic salts are generally used as thermodynamic inhibitors; CaCl2 as a common additive in drilling fluids exhibits unique properties. In this study, we explored the dissociation mechanism of CH4 hydrate in CaCl2 solutions at the macroscopic and microscopic scale using experiment and molecular dynamics (MD) simulation. The experimental results showed that CaCl2 accelerated the dissociation rate of CH4 hydrate. The dissociation rate of CH4 hydrate increased with the increase of CaCl2 concentration at large depressurization pressure and was mainly affected by pressure when the depressurization pressure was lower. MD simulations were used to give an atomic scale interpretation of the macroscopic results obtained from the experiment. The results showed that the addition of CaCl2 destroyed the resistance liquid film formed during CH4 hydrate dissociation, thus accelerating the dissociation process, in good agreement with experimental results. HIGHLIGHTS: • The amount of CaCl2 affects CH4 hydrate dissociation at large depressurization pressure. • The dissociation of CH4 hydrate at low depressurization pressure is dependent on pressure. • Ca2+ destroys effectively the resistance liquid film produced during hydrate dissociation. • MD simulation results are in agreement with those of the experiment.

Fertility after Endoscopic Surgery for Ectopic Pregnancy Management in Point "G" Teaching Hospital, Bamako-Mali.

Endoscopic surgery of ectopic pregnancy is actually the gold standard for the management of fallopian tubal diseases. A survey was conducted to evaluate fertility in patients who underwent endoscopic management for ectopic pregnancy. A retrospective study was conducted at the department of general and endoscopic surgery of the Point "G" teaching hospital, in Bamako, Mali, from January 1st 2007 to December 31, 2016. Forty-eight (48) patients who underwent endoscopic management of tubal ectopic pregnancy and who have been followed up for fertility were included in this study. Statistical tests used were X2 or Fisher test and their confident interval, p <1 % has been considered as statistically significant. The therapeutic score of Pouly was less than 4 in 25.0% (n = 12). The return to fertility was observed among 48.0% of patients (n = 23). The chance of conception was less than 80.0% after the fourth postoperative year (p=0.001). The outcome of pregnancies has been seventeen full-term pregnancies, three ectopic pregnancies and three miscarriages. The occurrence of pregnancy after endoscopic management indicated for ectopic pregnancy is possible. However, many factors can influence the future conception.