Interpretation of Geological and Gravity Data from the Bamiléké Plateau (West-Cameroon): Implication for the Understanding of Its Underground Lithotectonic Geometry

The Bamiléké Plateau represents a key domain in the understanding of the geodynamics associated with the central Cameroon shear. The study aimed to highlight the subsurface architecture of the plateaus basement setting with focus on high potential areas for hydrogeological and mining development projects. To this end, geological field observations were carried out. Since the structures sought were near-surface, a separation approach based on the upward continuation method was applied to the Bouguer anomaly grid. A set of processing techniques, including vertical derivative or DZ, analytical signal or SA and categorization of gravity signatures, was applied to generate the residual map. The synthesis geological model, obtained from analysis and interpretation of the various transformed maps and 2.5D modeling of two gravity profiles P1 and P2 highlights the following features: 1) intrusions of steep-sided granitic batholiths from Dschang to Bandjoun (profile P1), increasing in width from NW (Dschang) to SE (Bandjoun);2) larger volume batholiths with moderate sides located at Bafang and Bangangté (profile P1). These plutonic massifs were weakened by brittle deformation, which favored the emplacement of phonolite or anorthosite dykes within them. The emplacement of these dykes was accompanied by compressional faults with high dip between Dschang and Bandjoun and extensional faults with medium dip between Bafang and Bangangté. These fault zones (trending N85E to N95E) are ideal for hydrogeological investigations in a basement setting, as well as a series of dyke networks that could potentially be preferred zones for the circulation and accumulation of useful substances. The resulting geological sections P1 and P2 highlight the influence of granitic intrusions in the geological system of the study area, as well as the structural control associated with the various dyke intrusions. All the models obtained can serve as fundamental references for hydrogeological and mining exploration project on the Bamiléké Plateau.

An Efficient Adaptive Iteratively Reweighted l1 Algorithm for Elastic lq Regularization

In this paper, we propose an efficient adaptive iteratively reweighted l1 algorithm (A-IRL1 algorithm) for solving the elastic lq regularization problem. We prove that the sequence generated by the A-IRL1 algorithm is convergent for any rational and the limit is a critical point of the elastic lq regularization problem. Under certain conditions, we present an error bound for the limit point of convergent sequence.

Temporal and Oscillatory Behavior Observed during Methanol Synthesis on a Cu/ZnO/Al_{<span style="font-family:Verdana;">2</span>}<span style="font-family:Verdana;">O</span>_{<span style="font-family:Verdana;">3</span>}<span style="font-family:Verdana;">(60:30:10) Catalyst

The rate of Methanol synthesis over a Cu/ZnO/Al2O3 (60:30:10) catalyst has been measured using CO2/H2 (10:90) and CO/CO2/H2 (10:10:80) streams at 433, 443, 453, 463 and 473 K. Using the CO2/H2 stream, it requires 12 × 103 s to achieve steady-state performance;this time reduces to 5.4 × 103 s on increasing the temperature to 463 K. Using the CO/CO2/H2 stream, steady State performance is not achieved even after 14.4 × 103 s at 433 K but is achieved after 9 × 103 s at 463 K. Significant deviations from steady state behavior (~40% of steady state) are observed only at 453 K and only using the CO2/H2 feed when gas chromatography (GC) is the analysis system. When the reactor output is connected directly into a flame ionization detector (FID), oscillation is observed at all temperatures studied using a CO2/H2 stream. Injection of CO into the CO2/H2 stream, which is synthesizing methanol at 473 K, produces a sharply spiked increase in the rate of methanol synthesis followed by an oscillatory relaxation to steady state behavior. At 433 and 443 K, the injection of CO into the CO2/H2 stream again produces the sharply spiked increase in the rater of methanol synthesis, which returns to the baseline value without oscillations.

Visible Light Hydrogen Evolution over <i>α</i>-MoO</span>_{<span style="font-family:Verdana;">3</span>}<span style="font-family:Verdana;">and <i>α</i>-MoO</span>_{<span style="font-family:Verdana;">3</span>}<span style="font-family:Verdana;">/ZnO Hetero-Junction

MoO3 and 5% MoO3/ZnO were prepared by impregnation method using (NH4)6Mo7O24, 4H2O as precursor and ZnO as support. The prepared samples were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), infra red (FTIR) and UV-Vis diffuse reflectance (DRS) spectroscopies and photo-electrochemistry. The XRD pattern showed that the MoO3 powder treated at 700°C is a single-phase crystallizing in an orthorhombic structure with a direct optical transition (2.70 eV). The hetero-junction 5% MoO3/ZnO was photo-electrochemically characterized to assess its feasibility for H2 production under visible light. The capacitance potential (C-2 f(E)) characteristic of MoO3 plotted in Na2SO4, (0.1 M) electrolyte indicates n-type conduction with a flat band potential of -0.54 VSCE. The photocatalytic activity was performed for the photoreduction of water to hydrogen under visible light illumination. The best performance occurs at pH ~ 7 with an evolved volume of 5.9 mL.