The Ngwi area, along the central Cameroon shear zone (CCSZ), features two-mica granite and hornblende-biotite granite intrusive into paragneisses and amphibolites. This work provides insights into the kinematic evolution and emplacement mechanism of the Ngwi pluton, highlighting the complex tectonic history of the region, with implications for understanding the Pan-African tectonics. Structural data analysis reveals: (i) D1 flattening (similar to 622-613 Ma) defined by NW- to WNW-striking S1 foliation in paragneisses; (ii) D2 sinistral shearing (similar to 613-590 Ma) with NE-SW to NNE-SSW and NW-SE rotational evolution, developed S2 foliation in host-rocks and Sm2 magmatic fabric in pluton; (iii) D3 dextral shearing (similar to 585-540 Ma) with NE-SW to ENE-WSW and NW-SE rotational evolution, induced a mylonitic fabric towards the pluton margins. Microstructural and kinematic data analysis suggest the Ngwi pluton emplaced into a high-strain sheared crustal domain during the D2-D3 phases, with a continuous evolution from magmatic to solid-state deformation (i.e., 700 degrees C <= T <= 300 degrees C) under high-grade amphibolite to low-grade greenschist conditions. The pluton's emplacement likely occurred within tension gashes opened in the paragneiss host rocks under a sinistral transpressive tectonics along the CCSZ, consistent with similar shear zones in Chad, Central African Republic and northeastern Brazil.
The aim of this study was to evaluate the potential of iroko inner bark as a naturally occurring, pre-impregnated, unidirectional fibrous preform for producing added-value, biobased composite materials. To this end, the secondary phloem was separated from the rest of the bark and then consolidated using a hot compression moulding process similar to that employed for processing sheet moulding compounds (SMCs) in the composites industry. An experimental procedure was also employed to extract the latex from the secondary phloem. Thermal and FTIR analyses suggested that the latex was primarily composed of proteins and polyisoprenes. The microstructure of the resulting composites was characterised using synchrotron-based 3D X-ray computed tomography. 3D images revealed significant consolidation of the secondary phloem induced by the compression moulding process. To evaluate the practical interest of these composites in specific engineering applications, experiments were carried out to analyse their mechanical performance, surface wettability, and hygroscopic behaviour in environments with high relative humidity. Mechanical tests revealed significant anisotropy, with high longitudinal stiffness and strength inherited from their intricate quasi-ordered fibrous architecture. The proposed approach allows biobased composite materials with interesting end-use properties to be produced without the use of any supplementary oil-based resin matrix.
This study investigates the reinforcement potential of Borassus aethiopum (BA) fruit shells in an epoxy matrix, with particular emphasis on the influence of particle size and filler loading on the physico-mechanical properties of the resulting bio-composites. Raw BA shells were characterized using scanning electron microscopy (SEM), X-ray micro-computed tomography, Vickers micro-indentation (HV0.1), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Microstructural observations revealed a functionally graded and interlaced fibrous architecture typical of highly lignified lignocellulosic tissues. The three-dimensional micro-tomographic analysis highlighted a highly heterogeneous surface morphology with altitude variations ranging from -111 & micro;m to +134 & micro;m and peak-to-valley amplitudes exceeding 200 & micro;m. These topographical features indicate a hierarchical organization of thick fiber bundles resulting in a naturally rough surface that can promote mechanical interlocking with polymer matrices. The shells also exhibited a heterogeneous micro-hardness distribution and an actual density ranging from 1.21 to 1.36 g & centerdot;cm-3. Bio-composites were fabricated using three particle size distributions: T1 (0.5-1.25 mm), T2 (1.25-2.5 mm), and T3 (2.5-4 mm), at filler loadings of 60, 70, and 80 %. Mechanical characterization through three-point bending tests and Shore D hardness, together with water absorption measurements, demonstrated that particle size strongly governs composite performance. The highest mechanical efficiency was obtained for 70 % T3 particles, yielding a modulus of elasticity of 8.7 +/- 2.14 GPa, whereas 80 % T1 composites exhibited the lowest stiffness (2.87 +/- 0.94 GPa) and the highest water uptake. These findings demonstrate that larger particles improve stiffness and dimensional stability, while smaller particles increase hygroscopic sensitivity. .
Aframomum citratum, a little-studied aromatic plant from Cameroon, produces essential oils rich in monoterpenes, yet their industrial use remains limited by low extraction yields. This study investigated spontaneous solid-state fermentation (SSSF) as a pretreatment to enhance essential oil recovery, combined with response surface methodology (RSM via Box-Behnken Design, BBD) and artificial neural networks (ANNs) to model and optimize the extraction yield. A 15-run experimental design was employed to evaluate the effects of fermentation time, moisture content, and hydrodistillation time. The ANN model (3-5-1 architecture using tansig and purelin transfer functions) showed slightly higher predictive performance than the quadratic RSM model (R2 = 0.98 vs 0.97), reflecting its ability to capture nonlinear relationships among process variables. Model robustness was further evaluated using leave-one-out cross-validation (LOOCV), which confirmed stable predictive behavior for both approaches. Optimization using the RSM desirability function predicted a maximum oil yield of 1.73
This study developed pre-cooked plantain semolina through controlled steaming (20 and 40 min at 100°C), convective drying (12 h at 50°C), and hammer milling, followed by size fractionation into ultrafine (US), fine (FS), and coarse (CS) semolina. Processing variables and particle size significantly influenced the physicochemical, functional, and engineering properties. Particle size distribution (D50 = 201.6–699.9 µm) governed the proximal composition, with lipids (up to 11.65
