Natural & Applied Sciences

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    An assessment of common atmospheric particulate matter sampling and toxic metal analysis methods.
    (Academic Journals, 2010) Kgabi, Nnenesi A.
    In this study, the atmospheric particulate matter (PM) was sampled using the tapered element oscillating microbalance, and the inductively coupled plasma mass spectroscopy (ICP-MS) and scanning electron microscopy coupled with energy dispersive spectrometry (SEM/EDS) were used for determination of elemental composition of the PM. The efficiency and relevance of the sampling method, ICP-MS and SEM/EDS in toxic metal analysis were assessed. Low flow rate yielded high accumulated mass of particulate matter. The efficiency of the filter media used was found to be, in decreasing order: teflon-coated glass fiber, ringed-teflon and quartz filters. The main elements identified from the SEM/EDS on ringed-teflon filters were Si, Fe, Mg, K, Na, C, S, F and O, and for ICPMS, the following main elements were identified: Fe, Al, Ca, Mg, K, Na, Cr, Ni, Pb, Cu, Zn and Mn. The ICP-MS proved to be more relevant for the analysis of the toxic metals of interest. The standard deviations obtained from this method were less than 30% for most of the metals identified. The method detection limit was also low (0.2 to 1 µg/L) for most metals, and 50% and less standard deviation to mean ratios were obtained for Ni and Pb.
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    The current state of research development in Namibia.
    (NUST, 2011) Kgabi, Nnenesi A.
    Namibia has a number of unique features including history, the landscapes, a diversity of cultures, and the small population. All these attract researchers and thus create a need for a liberating yet ethical and stable research environment. The need for research support structures and mechanisms, and multi-disciplinary research teams working across institutions within the country cannot be debated.
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    Basic education and skills acquisition in Namibia.
    (NUST, 2012) Kgabi, Nnenesi A.
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    Situational analysis and promotion of the cultivation and utilisation of the Moringa oleifera tree in selected sub-Saharan Africa countries.
    (NUST, 2012) Kwaambwa, Habauka M.; Chimuka, L.; Kandawa-Schulz, M.; Munkombwe, N. M.; Thwala, J. M.
    Malnutrition, poverty and lack of safe drinking water and sanitation are serious problems in developing countries, especially sub-Saharan Africa. The Moringa oleifera (MO) tree could be the solution to these problems due to its medicinal, nutritional and water purification. The aim of the study was to assess and promote the cultivation and utilisation of the MO in 5 SADC countries namely Botswana, Namibia, South Africa, Swaziland and Zambia. The study was done between September 2010 and March 2011. It was found that the tree is generally used for nutritional and medicinal purposes except in Namibia where another species is found. The prices of the products vary from country-to-country. The information about the benefits of the MO was well received although a lot still needs to be done in order to benefit from this sustainable resource.
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    A review of current and future challenges in paints and coatings chemistry.
    (NUST, 2013) Kwaambwa, Habauka M.
    Paints and coatings are very important to everyday life. However, their formulation is becoming more and more complex due to legislative demands, driven by environmental and health concerns, to reduce or eliminate completely volatile organic compounds (VOCs) and any solvents considered hazardous air pollutants (HAPs). Liquid coatings formulation must simultaneously meet VOC limitations and HAP restrictions by shifting to high solids, low-solvent coatings as well as water-borne coatings. Non-aqueous formulations that meet existing and pending VOC and HAP regulations and offer the performance customers expect/require are still being produced. Switching to environmentally-friendly coatings involves more than simply replacing organic solvents with VOC-free ingredients such as water. Efficient formulation demands that basic rules governing the rheological behaviour are well-defined. This paper highlights the formulation and some of the current and future challenges in the paints and coatings industry with emphasis on the chemical aspects.
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    Surface Activity Interactions in Aqueous Solution of Anionic Surfactants with a Water Treatment Protein from Moringa oleifera Seeds
    (Scientific Research Publishing, 2015) Kwaambwa, Habauka M.; Maikokera, Raymond; Nermark, Fiona M.
    The interaction of anionic surfactants sodium dodecylbenzenesulphonate (SDBS) and sodium bis (2-ethyl-1-hexylsulfosuccinate) (AOT) with the water treatment protein extracted from Moringa oleifera seeds has been investigated by surface tension measurements. The results were compared with previously reported studies using surface tension and zeta potential measurements of the same protein with an anionic surfactant sodium dodecylsulphate. There is a strong electrostatic interaction between the protein and the surfactants characterized by a local maximum at intermediate surfactant concentration. This surfactant concentration depends on the protein concentration and corresponds to the surfactant concentration at the point of charge reversal (zeta potential = 0 mV). The number of surfactant molecules required to neutralize the positive charges on the protein was found to be 8 per protein molecule.