ghanaopendata/ghanaian-research-english huggingface dataset:
Synthesis and characterisation of nanostructured copper oxide

Nanostructured copper oxides has attracted several research interests over the years due to their interesting optical properties and their potential use in several electronic applications such as solar cells and gas sensors. In this work, reverse micelle microemulsion (a bottom-up approach) and high energy milling (Top-down approach) have been employed for the production of defect-free and highly defective copper oxide nanocrystals. The produced defect-free nanocrystals show good crystallinity with the nanometric nature of the primary domains (20 nm - 4 nm) leading to quantum confinement phenomena. Mechanisms for the nanocrystal formation and growth validated by means of several techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and Fourier Transform Infra-Red spectroscopy (FTIR) have been proposed. The effect of high energy milling on the microstructure evolution of bulk copper oxide powders was investigated using synchrotron radiation XRD line profile analysis, High Resolution TEM and SEM. The reduction in the average size of crystallites and simultaneous narrowing of the size distribution occurs in the initial minutes of milling. A suitable nanocrystalline microstructure was achieved for a milling of ca. 20 min with asymptotic limit of about 10 nm. A high density of dislocations (≈4.2×10-16 m-2) was introduced in the system in the size reduction process.

Source: UG
Synthesis and characterisation of zeolite-A and Zn-exchanged zeolite-A based on natural aluminosilicates and their potential applications

Zeolites have been hydrothermally synthesized using alumina and silica based deposits (kaolin, bauxite, silica and feldspar) sampled from three regions in Ghana and the chemical compositions of the zeolites varied by batch formulations. The as-synthesized zeolites were characterized using X-ray Diffraction, Fourier Transform Infra-Red and Porosimetry techniques. The morphology and elemental compositions were examined using Scanning Electron Microscopy and energy dispersive X-ray spectroscopy (EDX). The results indicate that zeolite A was formed with a cubic structure and structural variations depending on the batch formulations. By increasing the silica content (Si/Al ratio) through batch formulations, the crystallite sizes of zeolites increased forming Zeolite A with LTA structure and Zeolite A (K-exchanged dehydrated). Samples with higher alumina content produced Zeolite A (Hydrated), Zeolite-Na and Zeolite A (Na, Dehydrated) with lower crystallite sizes. The zeolite synthesized was then used in the synthesis of zinc exchanged Zeolite A (Zn-zeolite A). EDX analysis confirmed a complete exchange of Na in the Zeolite framework with Zn and the feasibility as an adsorbent for methylene blue tested. The synthesized Zn-exchanged Zeolite A showed strong adsorption for methylene blue dye. The adsorption kinetics of the MB onto Zn-exchanged Zeolite A was observed to follow pseudo-second-order model. Freundlich model better described the interaction among adsorbate molecules onto the Zn-exchanged Zeolite A adsorbent, suggesting a multilayer distribution of adsorbate molecules with some level of interaction between adsorbed molecules. The regeneration capacity of the adsorbent was low and calculated to be about 48% at pH of 12. © 2018 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license.

Source: UG
Synthesis and Characterization of Chrysophyllum albidum (African Star Apple) Plant-Mediated Zinc Oxide Nanostructures and Evaluation of Their Antioxidant, Anti-Inflammatory, and Antimicrobial Activity

This study sought to evaluate the added advantage of mediating ZnO nanostructures with a medicinal plant. The synthesized ZnO nanocrystalline structures were confirmed by Fourier transform infrared spectrometer and characterized through scanning electron microscope, transmission electron microscope, ultraviolet–visible spectroscopy, and energydispersive X-ray spectrometer. The antioxidant, anti-inflammatory, and antimicrobial activities of the ZnO nanostructure mediated with methanol extracts of the leaf, fruit, and seed of Chrysophyllum albidum were then evaluated using DPPH assay, egg albumin denaturation assay, and agar well diffusion methods, respectively. All the characterization analyses revealed high-purity hexagonal-shaped ZnO nanoparticles which were agglomerated. The mean diameter of the particles determined were 11:3±1:7 nm, 20:4±3:2 nm, and 27:3±6:6 nm for C. albidum seed, fruit, and leaf extract-mediated ZnO NPs, respectively. The EC50 values recorded for the antioxidant activity of the extract-mediated ZnO NPs were 0:507 ± 0:015, 0:255 ± 0:006, 0:193 ± 0:003, and 0:004 ± 0:000 mg/mL for leaf, fruit, seed, and ascorbic acid, respectively. From the antimicrobial analysis, C. albidum seed extract-mediated ZnO NPs recorded the highest zone of inhibition (24:33 ± 0:47) against S. aureus whereas C. albidum leaf extract-mediated ZnO NPs gave the lowest zone of inhibition (13:00 ± 1:41) against E. coli at a concentration of 50 mg/mL. Moreover, C. albidum fruit extract-mediated ZnO NPs presented the highest zone of inhibition (18:00 ± 0:82) against the fungus (C. albicans) also at a concentration of 50 mg/mL. The IC50 values recorded for the anti-inflammatory activity of the extract-mediated ZnO NPs showed inhibition in the order fruit > seed > leaf. Meanwhile, extracts of the samples showed the presence of flavonoids, alkaloids, saponins, and glycosides as phytochemical constituents in the leaf, fruit, and seed samples. In conclusion, the synthesized ZnO NPs from the extracts of C. albidum displayed significant antioxidant, anti-inflammatory, and antimicrobial activities against some selected microbes and fungi.

Source: UG
Synthesis and Characterization of Cupric Oxide Nanoparticles for Photovoltaic Applications

A simple inexpensive chemical route has been identified and used to synthesize cupric oxide nanoparticles suitable for photovoltaic applications. X-ray diffraction analysis showed the synthesized nanoparticles to be a pure cupric oxide phase. The particle size and particle size distribution of the cupric oxide nanoparticles were obtained by transmission electron microscopy (TEM) whereas the crystallite size and crystallite size distribution were obtained by X-ray diffraction peak broadening analysis. The particle size was found to be between 20 nm and 60 nm, an indication that cupric oxide nanoparticles are dominant in the sample produced and analysed. The particle size distribution obtained from cumulative percentage frequency plots features a log-normal function. Absorbance measurements and analysis show that the material has an absorbance peak around 314 nm and an average energy bandgap of 1.48 eV, making it a good candidate for photovoltaic applications. A thin film of average thickness of 1.47 microns made, was used to determine the conductivity of the material, which is 8.541×10−2 Ω−1cm−1. Incident radiation of various wavelengths from the highest (600 nm) to the lowest (300 nm), caused decrease in resistance of the thin film sample, an indication that the material responds favourably to visible radiation making it suitable for photovoltaic and photo electronic applications. We emphasize that a low cost approach has been used successfully to synthesize cupric oxide nanoparticles with the suitable optical and electrical properties required for application in the photovoltaic and photo electronic industries.

Source: UG
Synthesis and Characterization of Goethite Nanostructured powder: Application in the Simultaneous Removal of Co(II) and Ni(II) Ions from Aqueous Solution

This study investigates the adsorption efficiency of goethite nanostructured powder for the simultaneous removal of cobalt and nickel ions. The nanostructured powder sample was synthesized via a chemical precipitation technique and characterized using SEM, FTIR-ATR and XRD techniques. From batch adsorption studies, maximum absorption for Co(II) and Ni(II) ions occurred at an equilibrium contact time of 80 min, with an adsorbent mass of 0.1 g, and at pH=7. Co(II) ions showed greater affinity to the nanoparticles as compared to Ni(II). The maximum quantities adsorbed were recorded as 148.5 mg/g for Co(II) and 110.6 mg/g for Ni(II) ions. The best isotherm model fit for both metal ions was the Freundlich model indicating heterogeneity of the surface binding sites. The pseudo-second order kinetic model was the best-fit model: an indication of a strong chemical adsorption between the adsorbent surface and metal ions. The findings show that the goethite nanostructured powder is a very effective adsorbent material and prominent candidate for the simultaneous removal of cobalt and nickel ions from water.

Source: UG
Synthesis and Characterization of Hydroxyapatite- (HAP-) Clay Composites and Adsorption Studies on Methylene Blue for Water Treatment

Dyes used by the textile, tannery, and food industries tend to pollute water bodies and must be removed to get clean water. Hydroxyapatite (HAP) was synthesized from eggshells using the wet precipitation process. 'e as-synthesized HAP was characterized using Fourier Transform Infrared (FTIR) and X-ray powder diffraction (XRD). 'e synthesized HAP was mixed with three different clays: halloysite (HNT), kaolinite (KAO), and bentonite (BENT). 'e removal efficiency values of methylene blue (MB) from the data showed that HAP-BENT adsorbents had higher values, followed by HAP-HNT and then HAP-KAO adsorbents. 'e combined masses of 24 mg, 34.5 mg, and 33 mg (representing 20%, 15%, and 10% of HAP-BENT mass) had average adsorption capacity values of 20.7 mg/g, 17.2 mg/g, and 17.9 mg/g, respectively. For each mass percentage, the adsorption capacity values were found to decrease with adsorbent dosage. 'e HAP-BENT composites had removal efficiency values of 98.4, 91.9%, and 91.9%, respectively. Adsorption data for the HAP-BENT adsorbents were found to be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. 'e effect of temperature on adsorption capacity was evaluated and thermodynamical modeling was undertaken. 'e thermodynamical modeling predicts that based on the value of the change in enthalpy and Gibbs free energy the process was exothermic and spontaneous. 'is work confirms the potential of HAP-clay composites in removing MB from water.

Source: UG
Synthesis and Characterization of Modified Kaolin-Bentonite Composites for Enhanced Fluoride Removal from Drinking Water

Fluoride-contaminated drinking waters are known to cause severe health hazards such as fluorosis and arthritis. This paper presents the encapsulation of iron oxide nanoparticles in kaolin-bentonite composites adsorbents (KBNPs) for the removal of fluoride from drinking water by adsorption compared with kaolin-bentonite composite (KB). Adsorbents with an average weight of ∼200 mg and ∼7 mm diameter (granules) were prepared in the ratio of 10 :10 : 0.1 for kaolinite, bentonite, and magnetite nanoparticles, respectively. The granules were air-dried and calcined at 750°C and contacted with 2 mg/L sodium fluoride solution at varying time periods. .e adsorbents were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) formulation, and Brunauer–Emmett–Teller (BET), whereas the adsorption mechanism and the kinetics were explained using the Langmuir isotherm, Freundlich models, and pseudo-first-order and pseudo-second-order models. The results showed that the BET surface areas for the granules were 10 m2 /g and 3 m2 /g for KBNPs and KB, respectively. The SEM images for the adsorbents before and after adsorption confirm the plate-like morphology of kaolin and bentonite. The FTIR analyses of bentonite (3550 cm−1 –4000 cm−1 ) and kaolin (400–1200 cm−1 ) correspond to the structural hydroxyl groups and water molecules in the interlayer space of bentonites and the vibrational modes of SiO4 tetrahedron of kaolin, respectively. The KBNPs composites also recorded a fluoride removal efficiency of ∼91% after 120 minutes compared with 64% for KB composites without Fe3O4 nanoparticles. .e adsorptions of fluoride by the KBNPs and KB granules were found to agree with the Freundlich isotherm and a pseudo-second-order kinetic model, respectively. .e results clearly show that the impregnation of clays with magnetite nanoparticles has significant effect in the removal of fluoride, and the implication of the results has been discussed to show the impact of clay-magnetite nanoparticles composites in the removal of fluoride from contaminated water.

Source: UG
Synthesis and characterization of zinc and copper oxide nanoparticles and their antibacteria activity

Inorganic nano-metal oxides can be effective alternatives to drug resistant organic antibiotics due to their broad spectrum antimicrobial activity against pathogenic and mutagenic gram-negative and positive bacteria. In this study, zinc and copper oxides (ZnO and CuO) were synthesised using a wet chemical reduction method. The oxide nanoparticles were characterized using X-ray diffraction (XRD), UV–Vis spectrometer, Fourier Transformed Infrared spectrometer and Transmission electron microscopy (TEM). The antibacterial activities of the nanoparticles were investigated against e. coli and s. aureus using disk diffusion and microdilution tests. The TEM micrographs showed that copper oxide nanoparticles assumed a nanorod shape of average length of 100 nm whiles zinc oxide nanoparticles were spherical of average diameter of 15 nm. The FTIR results showed that the nanoparticles were free of impurities and organic surfactants, which was confirmed by XRD. For the antibacteria tests, the minimum inhibition concentration (MIC) of CuO against e. coli and s. aureus were 1 mg/ml and 0.25 mg/ml respectively whiles it was 0.1 mg/ml for ZnO against s. aureus with ZnO producing no inhibition against e. coli. With the microdilution test, both nanoparticles exhibited activity against both bacterias at all varying concentrations. The results concluded that CuO had higher antibacteria activity compared to ZnO.

Source: UG
Synthesis and crystal structure studies of three n-phenylphthalimide derivatives

The three N-phenylphthalimide derivatives, 2-(3,4-dichlorophenyl) isoindoline-1,3-dione (I), 2-(2,4-dichlorophenyl)isoindoline-1,3-dione (II) and 2-(2,4,5-trichlorophenyl)isoindoline-1,3-dione (III), were synthesized by the condensation of equimolar amounts of phthalic anhydride and 3,4-dichloroaniline, 2,4-dichloroaniline, 2,4,5-trichloroaniline, respectively, under acetic acid reflux and their structures determined by a combination of elemental analysis, FT-IR, 1H &amp; 13C-NMR spectroscopy and single crystal X-ray diffraction studies. Compounds I and II crystallize in a monoclinic crystal system (space group P21/c) with cell parameters of a = 5.7414(2), b = 8.0917(6), c = 26.077(1) Å and β = 99.4709(12) o for compound I, and a = 12.7133(9), b = 13.4328(9), c = 7.2603(5) Å and β = 93.210 (2)o for compound II. On the other hand, compound III crystallizes in a tetragonal crystal system (space group I4 1/a) with a = 13.4607(9) and c = 30.100(2) Å. The phthalimide moieties of these compounds are essentially planar, while the chloro-substituted phenyl ring of each compound shows consistent twist from the phthalimide plane with dihedral angles of 61.02(3), 69.09(3) and 85.78(5)o, respectively, for I, II and III. In the crystal structures of these compounds, a few weak C-H···O interactions form double-tape structures of centrosymmetric dimers of graph-set notation R 2 2 (10) for I and III, and an inversion dimer of graph-set motif R 2 2 (14) for II. In addition, some short contacts of C···C, C···O and Cl·· ·Cl are observed for I, II and III, respectively. © 2013 Springer Science+Business Media New York.

Source: UG
Synthesis and Initial Testing of Novel Antimalarial and Antitubercular Isonicotinohydrazides

The Bacteriology Department aims to improve the quality of life first for Ghanaians and the world at large by conducting research into bacterial diseases of public health importance to Ghana and globally. In addition to working on enteric pathogens and sexually transmitted diseases, the department’s current main focus is on the two most important mycobacterial diseases of public health importance to Ghana, namely Buruli ulcer (BU) and tuberculosis (TB).

Source: UG
Synthesis and Kinetic Adsorption Characteristics of Zeolite / CeO2 Nanocomposite

Adsorption is an effective method for treating polluted water bodies. In this study, Zeolite/Cerium oxide nanocomposite (Z/CeO2-NC) was hydrothermally synthesize and its adsorption capacity on methylene blue organic dye (MB) studied. The as-synthesized nanocomposite (Z/CeO2–NC) were characterized using X-Ray Diffraction (XRD), Fourier Transform Infra-Red (FT-IR), Energy Dispersive X-Ray Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). Kinetic models and sorption isotherms were used to predict the adsorption rate constants and process mechanisms. The synthesized Z/CeO2-NC showed an excellent adsorption kinetics of methylene blue and the characteristics of adsorption best fitted a pseudo-second-order model. The rate parameters of other models were evaluated and compared to establish the adsorption mechanisms. The Langmuir isotherm model best fitted the adsorption process indicating a homogeneous monolayer of the dye on the surface of the adsorbent. The thermodynamic Gibbs free energy (ΔG) parameter was determined to be negative, indicating a spontaneous adsorption process. The synthesized Z/CeO2-NCs showed strong adsorption for methylene blue dye with increasing amount of CeO2. The maximum adsorption efficiency was calculated as 93.9% and the maximum regeneration efficiency of the adsorbent was found to be 78.8% higher after it had been washed by alkaline solution of pH 13. The results reflect the feasibility of the nanocomposite as an adsorbent with a potential application in wastewater treatment technologies.

Source: UG
Synthesis and microstructural characterization of kaolin-polyethylene composites

In this article, the preparation and characterization of kaolin/polyethylene composites are presented. Microstructural characteristics of six different kaolin-polyethylene composites with varying percentage compositions of kaolin and polymer were produced using a modified melt compounding approach, was explored. The characterization methods employed are scanning electron microscopy (SEM), attenuated total reflectance mid Infrared (ATR-MIR), X-ray powder diffraction (XRD), thermogravimetric and differential thermal analysis (TGA-DTA), compressive, flexural strengths and impact resistance analysis. The implications of the results are discussed for the design of kaolin/polymer composites for constructional purposes. POLYM. COMPOS., 35:1507-1515, 2014. © 2013 Society of Plastics Engineers.

Source: UG
Synthesis and profiling of benzylmorpholine 1,2,4,5-tetraoxane analogue N205: Towards tetraoxane scaffolds with potential for single dose cure of malaria

A series of aryl carboxamide and benzylamino dispiro 1,2,4,5-tetraoxane analogues have been designed and synthesized in a short synthetic sequence from readily available starting materials. From this series of endoperoxides, molecules with in vitro IC50s versus Plasmodium falciparum (3D7) as low as 0.84 nM were identified. Based on an assessment of blood stability and in vitro microsomal stability, N205 (10a) was selected for rodent pharmacokinetic and in vivo antimalarial efficacy studies in the mouse Plasmodium berghei and Plasmodium falciparum Pf3D70087/N9 severe combined immunodeficiency (SCID) mouse models. The results indicate that the 4-benzylamino derivatives have excellent profiles with a representative of this series, N205, an excellent starting point for further lead optimization studies. © 2018

Source: UG
A Synthesis of Remote Sensing and Local Knowledge Approaches in Assessing Land Degradation in the Bawku East District – Ghana

A greater percentage of Northern Ghana is under threat of land degradation and is negatively impacting on the well-being of the people owing to deforestation, increasing incidence of drought, indiscriminate bush burning and desertiﬁcation. The problem is becoming severe with serious implications on the livelihoods of the people as the land is the major resource from which they eke their living. Reversing Land degradation requires sustainable land use planning which should be based on detailed up-to-date information on landscape attributes. This information can be generated through remote sensing analytical studies. Therefore, an attempt has been made in this study to collect data for planning by employing remote sensing techniques and ground truthing. The analysis included satellite image classiﬁcation and change detection between Landsat images captured in 1989, 1999 and 2006. The images were classiﬁed into the following classes: water bodies, close savannah woodland, open savannah woodland, grassland/unharvested farmland, exposed soil, burnt scars, and settlement. Change detection performed between the 1989 and 1999 and 1989 and 2006 showed that the environment is deteriorating. Land covers such as close savannah woodland, open savannah woodland and exposed soil diminished over the period whereas settlement and water bodies increased. The grassland/unharvested farmland showed high increases because the images were captured at the time that some farms were still having crops or crop residue. Urbanization, land clearing for farming, over grazing, ﬁrewood fetching and bush burning were identiﬁed as some of the underlying forces of vegetal cover degradation. The socio-cultural beliefs and practices of the people also inﬂuenced land cover changes as sacred groves as well as medicinal plants are preserved. Local knowledge is recognized and used in the area but it is not properly integrated with scientific knowledge for effective planning for sustainable land management. This is due to lack of expertise in remote sensing and geographic information systems (GIS) in the area.

Source: UG
Synthesis of Three-Dimensional Reduced-Graphene Oxide from Graphene Oxide

Carbon materials and their allotropes have been involved significantly in our daily lives. Zero-dimensional (0D) fullerenes, onedimensional (1D) carbon materials, and two-dimensional (2D) graphene materials have distinctive properties and thus received immense attention from the early 2000s. To meet the growing demand for these materials in applications like energy storage, electrochemical catalysis, and environmental remediation, the special category, i.e., three-dimensional (3D) structures assembled from graphene sheets, has been developed. Graphene oxide is a chemically altered graphene, the desired building block for 3D graphene matter (i.e., 3D graphene macrostructures). A simple synthesis route and pore morphologies make 3D reduced-graphene oxide (rGO) a major candidate for the 3D graphene group. To obtain target-specific 3D rGO, its synthesis mechanism plays an important role. Hence, in this article, we will discuss the general mechanism for 3D rGO synthesis, vital procedures for fabricating advanced 3D rGO, and important aspects controlling the growth of 3D rGO.

Source: UG