Browsing by Author "Apalangya, V.A."
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Item Boron Nitride Nanotubes for Curcumin Delivery as an Anticancer Drug: A DFT Investigation(MDPI, 2022) Nafiu, S.; Apalangya, V.A.; Yaya, A.; Sabi, E.B.The electrical properties and characteristics of the armchair boron nitride nanotube (BNNT) that interacts with the curcumin molecule as an anticancer drug were studied using ab initio calculations based on density functional theory (DFT). In this study, a (5,5) armchair BNNT was employed, and two different interactions were investigated, including the interaction of the curcumin molecule with the outer and inner surfaces of the BNNT. The adsorption of curcumin molecules on the investigated BNNT inside the surface is a more favorable process than adsorption on the outside surface, and the more persistent and stronger connection correlates with curcumin molecule adsorption in this case. Furthermore, analysis of the HOMO–LUMO gap after the adsorption process showed that the HOMO value increased marginally while the LUMO value decreased dramatically in the curcumin-BNNT complexes. As a result, the energy gaps between HOMO and LUMO (Eg) are narrowed, emphasizing the stronger intermolecular bonds. As a result, BNNTs can be employed as a drug carrier in biological systems to transport curcumin, an anticancer medication, and thereby improve its bioavailabilityItem A comparative study of the interaction of nickel, titanium, palladium, and gold metals with single-walled carbon nanotubes: A DFT approach(Results in Physics, 2019-03) Kayang, K.W.; Nyankson, E.; Efavi, J.K.; Apalangya, V.A.; Adetunji, B.I.; Gebreyesus, G.; Tia, R.; Abavare, E.K.K.; Onwona-Agyeman, B.; Yaya, A.Interactions between transition metal atoms, nickel, titanium, palladium and gold and (3,3), (4,2), (6,0) and (5,1) carbon nanotubes were studied using first principles calculations. The Fermi energy levels of the carbon nanotubes studied were found to increase during interactions with the transition metal atoms. Amongst the four metals, gold atom was found to have an enhanced interaction with the nanotubes transforming from semiconducting to a conducting tube. Titanium was also found to show similar characteristics to gold only when the atom was placed in the middle of the carbon nanotubes. Nickel and palladium atoms interactions did not affect much the electronic properties of the carbon nanotubes, with some slight changes in the electronic properties at some specific sites of the nanotubes. It is proposed from this study that, the carbon nanotube-metal interactions could be used as a guide to shed light on the electronic properties of such materials which could become promising engineering materials and revolutionize the electronic industry.Item Industrial Applications of Clay Materials from Ghana - A Review(Oriental Journal of Chemistry, 2018-08) Asamoah, R.B.; Nyankson, E.; Annan, E.; Agyei-Tuffour, B.; Efavi, J.K.; Kan-Dapaah, K.; Apalangya, V.A.; Damoah, L.N.W.; Dodoo-Arhin, D.; Tiburu, E.K.; Kwofie, S.K.; Onwona-Agyeman, B.; Yaya, A.Clay minerals are phyllosilicate groups naturally found in soils in all parts of the world. They have proven to be among the most essential industrial minerals because of their unique physicochemical properties and versatile applications within a wide range of fields including ceramics, construction, and environmental remediation, biomedical as well as cosmetics. Clay minerals are also primary to the production of other materials such as composite for secondary applications. In Ghana, clay mineral deposits are commonly found in several areas including soil horizons as well as geothermal fields and volcanic deposits, and are formed under certain geological conditions. This review seeks to explore the geographical occurrence and discusses the current uses of various local clay materials in Ghana in order to highlight opportunities for the utilization of these materials for other applications.Item Investigation and Characterization of Al paste as back surface field (BSF) for High Efficiency Si Solar cell(IEEE PES/IAS PowerAfrica, 2021) Awaah, M.A.; Awaah, I.; Apalangya, V.A.; Das, K.K.Photovoltaic solar cells offer many advantages, including needing little maintenance, environmentally benign of any electricity generating source with zero greenhouse gas emission. In the photovoltaic industry both the reduction of the silicon material thickness and the increase of the solar cells efficiency are critical topics for cost reduction. One key factor to reducing the cost and energy consumption of solar cell production process is reducing the thickness of the Si wafer to the order of 200 μm, the current industry wafer thickness ranges of 275 - 350 μm. The back-surface field (BSF), ~50 μm thick is formed during the firing of a screen printed A1 on the rear side. The main issue using thinner wafers with Al BSF is the bow of the wafers after firing. In this study, baseline Si Solar cells with 19.7% light conversion efficiencies was achieved on monocrystalline ptype CZ-Si with two types of Al BSF pastes. High performance SiN:H was grown by PECVD tool. The Al/Ag firing process for the Sun Chemical product (CTX 0435) needs to be optimized as the current process disintegrates to powder substance after Ag firing. The process window for firing the DuPont Ag front-side paste is large and yields low series resistance values without forming gas anneal (FGA anneal).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.Item Roll-to-roll fabrication of cellulose nanocrystal-poly(vinyl alcohol) composite coatings with controlled anisotropy(Cellulose, 2018-11) Chowdhury, R.A.; Clarkson, C.; Apalangya, V.A.; Islam, S.M.N.; Youngblood, J.P.Cellulose nanocrystal (CNC) composite coatings may impart many benefits in packaging, electronic, optical, etc. applications, however, large-scale cellulose coating production is a major engineering challenge. A versatile roll-to-roll reverse gravure process for the manufacture of cellulose nanocrystal-poly(vinyl alcohol) (CNC–PVA) coatings on a flexible polymer substrate was investigated in the present work. CNC content was varied from 0 to 100% to determine the effect of CNC concentration on coating anisotropy. Coatings were characterized by polarized light microscopy, UV–Vis spectrophotometry, cross-hatch adhesion testing and optical profilometry. This method produced uniform, highly transparent coatings with surface roughness less than 100 nm for all CNC–PVA weight ratios examined. The isotropic-anisotropic coating transformation was observed above 50% CNC, with a maximum anisotropy at 70% CNC along the shear direction. Anisotropic CNC–PVA coatings exhibited increased water vapor barrier performance due to the increased CNC packing and density.Item Sorption and degradation of neonicotinoid insecticides in tropical soils(Northeast Forestry University, 2018-04) Dankyi, E.; Gordon, C.; Carboo, D.; Apalangya, V.A.; Fomsgaard, I.S.The purpose of this study was to evaluate the effects of Broussonetia papyrifera (paper mulberry) invasion and land use on the floristic composition of a dry semi-deciduous forest in Ghana. Forty-five plots (25 m × 25 m each), distributed among three land uses—selectively logged (SL); abandoned farmlands (AF); and an undisturbed reference (RF)—were surveyed. Results showed lower tree species richness (S), diversity (H′), evenness (S) and basal area (BA) in the SL (46, 0.78, 0.32 and 269.12 m2 ha−1, respectively) and AF (40, 0.53, 0.45, and 131.16 m2 ha−1) sites compared to the RF site (79, 2.66, 0.87, 963.72 m2 ha−1). Similar patterns were found at the shrub layer, but no differences were observed at the herb layer. Non-metric multidimensional scaling ordination revealed distinct species composition among the land uses. The two disturbed habitats, SL and AF, were associated with increased B. papyrifera invasion particularly in the overstory, with importance value index and mean relative density of 45 and 65.03%, and 42 and 53.29%, correspondingly. However, the species was only sparsely represented in the RF site. Tree density of B. papyrifera correlated negatively with H′, S, E, BA, and native tree density and richness. These findings highlight the strong link between human land use (i.e., logging and slash-and-burn farming), invasion, and vegetation characteristics, and suggest the need to limit these disturbances to conserve biodiversity within tropical forest ecosystems. © 2018 Northeast Forestry University and Springer-Verlag GmbH Germany, part of Springer Nature