NuSpace

NuSpace is the official repository platform of the National University of Science and Technology that enables researchers in:

  • obtaining easy access to a wide range of academic materials,
  • promoting knowledge dissemination and facilitating interdisciplinary collaboration.

Explore our repository to discover a wealth of knowledge across various disciplines.

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Now showing 1 - 5 of 12

Recent Submissions

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Biological acidification of pig manure using banana peel waste to improve the dissolution of particulate phosphorus: A critical step for maximum phosphorus recovery as struvite
(Heliyon, 2022-07-22) Moyo, L.B.; Simate, G.S.; Mutsatsa, T.
Traditional disposal of agricultural bio-waste such as pig manure and banana peel waste poses an environmental nuisance. The uncontrolled disintegration of these waste materials decomposes to toxic effluent and methane a greenhouse gas twenty-one times more potent than carbon dioxide at trapping heat in the atmosphere, which is detrimental to the climate by elevating temperatures. Agricultural bio-waste is rich in nutrients that include nitrogen and phosphorus. Selectively separating these nutrients from the solid phase to produce high value products has been envisaged as an effective method of waste valorisation. This study aims to investigate the solubilisation of phosphorus (P) during anaerobic digestion (AD) of pig manure with banana peel waste as the co-substrate. The objective was to enhance the biological dissolution of the phosphorus from solid pig manure to the aqueous phase as this is envisaged to subsequently ease the recovery of P as a concentrated product via crystallization. Thereafter, phosphorus is used as a slow-release mineral fertilizer. Biological acidification was effective in reducing the pH to less than 6.50 from an initial pH of 7.28 at higher doses of BPW >100 g/L. Maximum dissolution of total phosphorus of 75% was observed at a pH of 5.40. Multiple regression analysis was used to correlate pH, banana peel waste concentration, and the anaerobic digestion time (ADT) to optimize the dissolution of P as this was deduced to be occurring at a low pH. A 2nd order polynomial was deduced to best fit the data with an R2 value of 0.90. The p values for the HRT and banana peel waste concentration were both <0.05 showing that both variables had a strong influence on the pH.
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Factors influencing library use by students with disabilities in Zimbabwe: The case of United College of Education (UCE)
(Library Philosophy and Practice, 2022) Ndiweni, M.; Machimbidza, T.; Mutula, S.
The study investigated the factors that influence library usage by students with disabilities at United College of Education in Zimbabwe. The study employed a qualitative approach. Interviews were held with sixteen students with disabilities, the chief librarian, two library assistants, and one library intern. Data were also collected through observations. Results reveal that great effort has been made to provide inclusive library services to students with disabilities; however, challenges remain. These include: physical inaccessibility of the library to students living with disabilities, lack of infrastructure to support available assistive technologies, information resources that do not accommodate students living with disabilities, and staff that is not adequately trained to handle users with disabilities. The study contributes to global debate about provision of library services to people living with disabilities from a Zimbabwean perspective. The study’s recommendations provide ideas that can be adopted by libraries to improve inclusivity.
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Investigation on the Potential Production of Diesel from Waste Tires
(Scientific Research Publishing, 2022-10-24) Mudono, S.; Jim, N.; Chigova, J.T.
An alternative fuel production was performed by catalytic-pyrolysis of waste tires under a nitrogen (N2) environment and with a zeolite catalyst. Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to removing tire residues from inadequate sites and it can be a sustainable process to produce alternative fuels. The project investigated the conversion of the waste tires into diesel as one way of waste management and also as a viable process which in turn helps to meet the fuel demand. Uses of the diesel and the by-products from the process were also outlined. Experiments were conducted on the pyrolysis process in order to find the optimum conditions for producing the diesel through pyrolysis; the temperature and residence time were optimized in order to get maximum output from the process. The optimum temperature of the reaction was found to be 520˚C and the optimum residence time was 92.5 minutes. Quality tests of the product were then conducted on the obtained product and most of the properties were found to meet the required standard specifications. The most critical properties which are density, final boiling point, flash point and kinematic viscosity, were found to be 0.8495 g/cm3 , 370˚C, 50.5˚C and 3.681 cSt, respectively, and they were within the required specifications. Quality analysis showed that a quality product that is suitable for automobiles could be obtained from the process. The process also produces useful by- products such as char, which can aid in the purification process of the diesel after conversion to activated carbon. The process is environmentally friendly if the appropriate pollution prevention methods like gas absorption are thoroughly implemented. Waste tires are an alternative source of diesel and hence the feasibility of implementing the project on a large scale.
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Bifurcation Analysis of a 5D Nutrient, Plankton, Limnothrissa miodon Model with Hydrocynus vittatus Predation
(Journal of Applied Mathematics, 2022-07-20) Mutasa, F.K.; Jones, B.; Tendaupenyu, I.H.; Nhiwatiwa, T.; Ndebele-Murisa, M.R.
In this paper, we construct and analyze a theoretical, deterministic 5D mathematical model of Limnothrissa miodon with nutrients, phytoplankton, zooplankton, and Hydrocynus vittatus predation. Local stability analysis results agree with the numerical simulations in that the coexistence equilibrium is locally stable provided that certain conditions are satisfied. The coexistence equilibrium is globally stable if certain conditions are met. Existence, stability, and direction of Hopf bifurcations are derived for some parameters. Bifurcation analysis shows that the model undergoes Hopf bifurcation at the coexistence point for the zooplankton growth rate with periodic doubling leading to chaos.
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Malunguza, N. J. 2016. MATHEMATICAL MODELLING AND ANALYSIS OF EXISTING AND EMERGING PROBLEMS INFLUENCING THE TRANSMISSION DYNAMICS OF HIV/AIDS IN AFRICAN HETEROSEXUAL SETTINGS. PhD Thesis.
(2016) Malunguza, N. J.
The human immunodeficiency virus (HIV) is spread through exchange of body fluids and affects specific cells of the immune system, called CD4 + T cells. Progressive depletion of these cells over time leads to a condition called the acquired immuno deficiency syndrome (AIDS). In Africa, transmission in the general population is predominantly heterosexual. Confluence of various complex social, cultural and behavioural tendencies influence the incidence and distribution of the virus in the region and there are sub-populations that are particularly at heightened risk of acquiring or passing on the virus. In this thesis, HIV transmission models are formulated to obtain qualitative and quantitative insights into the transmission dynamics of the disease. The models are designed to capture the effect of differential infectivity and susceptibility through stratification of the population into sub-groups according to some risk factors peculiar to the group. Alcohol consumption in sexual settings reflective of gender inequities and same sex interaction between men and men in heterosexual settings are studied as inherently problematic pre-existing risks. Super-infection by different HIV subtypes, contraceptive use and heterosexual anal intercourse are also considered as emerging challenges in disease control. The models are rigorously analysed using analytical and computational techniques to determine solutions and their dynamical properties and transmission characteristics. Results show that superinfection by two non-competing HIV strains increases disease burden and must be factored in the HIV policing framework. Partnership formation rates between low and high risk groups are shown to be pivotal in the spread of HIV across heterogeneous populations so that constraining formation of partnerships between the general population and high risk groups such as alcohol consumers and men who have sex with men will be beneficial in the fight against HIV. Whereas literature on the acquisition and transmission risk posed by hormonal contraceptive use remains inconclusive, model results indicate the potential for accelerated spread and the bridging effect of men who may be the link between the high risk hormonal contraceptive users and the low risk general population. The model fit to data for Zimbabwe supports heterosexual anal intercourse (AI) only by a small percentage (< 1%) of the population in order for parameters to remain plausible with results showing that even at that low prevalence, heterosexual AI would compound HIV transmission. Study results show that MSM increase HIV spread in heterosexual settings through their bisexual activities and that curtailing bisexuality would overally have a negative impact on HIV spread. To bridge the gap between theory and real world observations, some models were fitted to sentinel data for Zimbabwe. Although data at the onset of the epidemic is sparse, an estimate of the basic reproductive number R0 quantifying the magnitude of the control effort necessary for epidemic control, was drawn. Projections of incidence and prevalence are made to allow for forward planning. Results from the assessment of each individual model collectively contribute to the general understanding of the problem surrounding the population level transmission dynamics of HIV for effective disease prevention and control.