Browsing by Author "Salifu, A.A."
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Item Crystallization of linde type a nanomaterials at two temperatures exhibit differential inhibition of HeLa cervical cancer cells in vitro(Trans Tech Publications Ltd, 2016) Tiburu, E.K.; Fleischer, H.N.A.; Aidoo, E.O.; Salifu, A.A.; Asimeng, B.O.; Zhou, H.This work reports evidence of the synthesis of zeolite A at two different temperatures (60 °C and 105 °C) from kaolin. XRD spectral analysis revealed percent crystallinity of 74 ± 2 and 71 ± 3 in LTA60 and LTA105 respectively. The average crystallize size of LTA60 and LTA105 was also estimated using Scherrer's equation to be 57 nm. FTIR analysis showed signature peaks characteristics of zeolite A in the two materials, except the appearance of absorbance peak at 2380 cm-1 in the LTA60 spectrum which was not observed in LTA105. Nitrogen porosity measurements of LTA60 and LTA105 gave the following parameters: average pore width of 2.45 and 1.01 nm respectively for LTA60 and LTA105, surface areas of 19.18 and 8.00 m2/g and pore volume of 0.012 and 0.002 cm3/g in that order. The influence of the materials on HeLa cancer cell growth was also investigated and the results showed differential inhibitory effects with LTA60 revealing pronounced inhibitory effects compared to LTA105 after 72 hours of cell incubation. This studies highlighted the importance of crystallization conditions that could influence the physicochemical parameters including structure, porosity, size, and morphology of zeolite materials on cell activity. The work also provided unique opportunities for utilizing natural deposits of kaolin globally to fabricate biomimetic materials for various biological applications. © 2016 Trans Tech Publications, Switzerland.Item Fracture and Toughening of Mycelium-based Biocomposites(Materials & Design, 2024) Etinosa, P.O.; Salifu, A.A.; Osafo, S.; et al.This study presents a combined experimental and analytical study of the fracture behavior and toughening mechanisms of bioprocessed mycelium-based biocomposites. The composites comprise hemicellulose hemp ducts (as nutritional and reinforcing components) intertwined with increasing weight percentages of laterite particles. Single-edge notched fracture experiments and in-situ observations of crack growth were used to explore the ef fects of varying proportions of laterite on the composite resistance-curve behavior. The toughening mechanisms, fracture modes, and crack-microstructure interactions were also elucidated. Since crack-bridging and crack deflection were observed to be the dominant toughening mechanisms, they were modeled using fracture me chanics approaches. Crack-bridging was shown to dominate the toughening at lower weight fractions of laterite (0–20 wt%). However, as the laterite content increases (20–40 wt%), a combination of crack-bridging and crack deflection was observed. Finally, at higher laterite weight fractions (>40 wt%), crack-tip shielding occurred primarily via crack deflection. The fracture mechanics predictions of resistance-curve behavior are shown to be consistent with the experimental measurements. The results suggest that mycelium-based and mycelium-laterite composites can be engineered with tunable fracture toughness. The implications of the results are also discussed for the development of sustainable building materials.Item Iron and silver nanostructures: Biosynthesis, characterization and their catalytic properties(Nano-Structures & Nano-Objects, 2020-04-20) Ohemeng, P.O.; Dankyi, E.; Darko, S.; Yaya, A.; Salifu, A.A.; Ahenkorah, C.; Apalangya, V.A.Finding suitable plant extracts that exert precise control over both the shape and size of nanoparticles remains a challenge in the synthesis of metal nanoparticles. In this study, iron (Fe) nanoparticles with uniform sizes and shapes, and silver (Ag) nanoparticles with unique morphology and phases were synthesized from aqueous plantain peel extracts. The effect of temperature and concentration of the starting metal salts on the size and shape of the synthesized nanoparticles were investigated. The catalytic effectiveness of the metal nanoparticles was also assessed based on their ability to mediate the degradation of methylene blue dye in the presence of sodium borohydride (NaBH4) as the reducing agent. Phytochemical analysis of the plantain peel extract revealed the presence of polyhydroxy compounds: tannins, flavonoids, glycosides, saponins, and terpenoids. The presence of these compounds in the extract was confirmed by Fourier transform infra-red analysis. Microstructural analysis showed that the Fe nanoparticles had uniform cylindrical shapes with 70.0 ± 0.4 nm diameters, whereas the Ag nanoparticles exhibited multi-shaped, single and polycrystalline phases with a varying size range. UV–Vis spectroscopic analysis indicated that Ag nanoparticles exhibited maximum plasmon absorbance at 440 nm typical of nanoscale silver while X-ray diffraction studies showed that the Fe and Ag nanoparticles were highly crystalline. The study indicated that Ag can be synthesized at all temperatures, whereas the Fe nanoparticles formed only above room temperature with plantain peel extract. Both Fe and Ag nanoparticles exhibited dose-dependent degradation of methylene blue dye, suggesting their potential use as bio-catalysts, although the Fe nanoparticles showed a better catalytic efficiency. This study demonstrates an eco-friendly approach to synthesizing uniformly shaped and sized Fe and Ag bio-catalysts for potential use in effluent waste treatment in cosmetics, food, pharmaceuticals, plastics, paper industries, and in general environmental remediation.