School of Physical Sciences (SPS)

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School of Physical Sciences (SPS)

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Start date: 2022Has files: Yes

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    Mathematical model of measles transmission dynamics using real data from Nigeria
    (Informa UK Limited, 2022-05-25) Olumuyiwa James Peter; Mayowa M. Ojo; Ratchada Viriyapong; Festus Abiodun Oguntolu
    Measles is a highly contagious and life-threatening disease caused by a virus called morbillivirus, despite the availability of a safe and cost-effective vaccine, it remains a leading cause of death, especially in children. Measles spreads easily from person to person via infected people's coughs and sneezes. It can also be transmitted through direct contact with the mouth or contaminated surfaces. To have a better knowledge of measles epidemiology in Nigeria, we develop a deterministic mathematical model to study the transmission dynamics of the disease in the population. The boundary of the model solution is performed, both equilibrium points are calculated, and the basic reproduction number ℛ0 is determined. We have proved that when ℛ0<1, the disease-free equilibrium point is both locally and globally stable. When ℛ0>1, the endemic equilibrium point exists and is stable if it satisfies Routh–Hurwitz criteria. We demonstrate the model's effectiveness by using a real-life application of the disease spread in Nigeria. We fit the proposed model using available data from Nigeria Center for Disease Control (NCDC) from January to December 2020 to obtain the best fit, this help us to determine the accuracy of the proposed model's representation to the real-world data. We investigate the impact of vaccination rate and hospitalization of infected individuals on the dynamics of measles in the population. The result shows that the combined control strategies reduce the peak of infection faster than the single control strategy.
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    Mathematical model for the dynamics of COVID-19 Pandemic Incorporating Isolation and Non-Linear Recovery Rate
    (ISEP Porto-Portugal, 2024-06-22) N. I. Akinwande; T. T. Ashezua; S. A. Somma; O. N. Abdurrahman; F. A. Oguntolu; O. M. Adetutu; R. I. Gweryina; R. O. Olayiwola; T. P. Adajime; F. A. Kuta; S. Abdulrahman; A. I. Enagi; G. A. Bolarin; M. D. Shehua; A. Usman.
    COVID-19 has in recent times created a major health concern in both developed and developing parts of the world. In this wise, there is every need to theoretically explore ways that will provide some insights into curtailing the spread of the disease in the population. In this paper, we present a population model for COVID-19 pandemic incorporating isolation and nonlinear recovery rate. The reproduction number was obtained using the next generation method. The disease-free equilibrium (DFE) of the model (1) was found to be locally and globally asymptotically stable whenever the associated reproduction number is less than unity. Results from the sensitivity analysis of the model, using the reproduction number, RC show that the top parameters that largely drive the dynamics of COVID-19 in the population are COVID-19 transmission rate and the proportion of individuals progressing to the class of reported symptomatic infectious individuals. Numerical simulations of the model shows that increasing the recovery rate of infected patients in the population will lead to an initial decrease in the number of hospitalized patients before subsequent increase. The reason for this could be attributed to the number of unreported symptomatic infectious individuals who are progressing to reported symptomatic infectious stage of infection for immediate isolation.
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    Modeling and optimal control of monkeypox with cost-effective strategies
    (Springer Science and Business Media LLC, 2022-11-22) Olumuyiwa James Peter; Chinwendu E. Madubueze; Mayowa M. Ojo; Festus Abiodun Oguntolu; Tawakalt Abosede Ayoola
    In this work, we develop and analyze a deterministic mathematical model to investigate the dynamics of monkeypox. We examine the local and global stability of the basic model without control variables. The outcome demonstrates that when the reproduction number , the model’s disease-free equilibrium would be locally and globally asymptotically stable. We further analyze the effective control of monkeypox in a given population by formulating and analyzing an optimal control problem. We extend the basic model to include four control variables, namely preventive strategies for transmission from rodents to humans, prevention of infection from human to human, isolation of infected individuals, and treatment of isolated individuals. We established the necessary conditions for the existence of optimal control using Pontryagin’s maximal principle. To illustrate the impact of different control combinations on the spread of monkeypox, we use the fourth-order Runge–Kutta forward–backward sweep approach to simulate the optimality system. A cost-effectiveness study is conducted to educate the public about the most cost-effective method among various control combinations. The results suggest that, of all the combinations considered in this study, implementing preventive strategies for transmission from rodents to humans is the most economical and effective among all competing strategies.
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    HARVESTING RENEWABLE ENERGY FOR A SUSTAINABLE FUTURE USING QUANTUM DOT TECHNOLOGY
    (13th annual and international hybrid conference of the renewable and alternative energy of nigeria, 2025-03) Ikeri, H.I; Ndubueze, D. N; Eze, C. N.; Achuka, E. I; Nwagbara, O.; Onuabuchi, V. C
    This paper explores the role of quantum dots in revolutionizing renewable energy technologies, addressing challenges such as stability and environmental impact. Renewable energy is essential for a sustainable future and advancements in nanotechnology have opened new possibilities for efficient energy harvesting. The result obtained indicates that quantum dots (QDs), display tunable electronic properties, discrete electronic state and high photon absorption efficiency. The novel properties allow for new design architectures such as immediate band, multiple exciton generation and multiple junction solar cell technologies. These mechanics have shown to derive quantitative gains in the solar to electricity conversion efficiency to surpass the Shockley and Quisser limit imposed on conventional cells. By integrating QD-based systems with solar photovoltaics and next generation batteries would paves the way for more efficient and sustainable energy solutions.
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    Electrode Materials for Energy Storage and Conversion
    (Tailor and Francis, 2022) Eze, C. N.; Obodo, R. M; Ezema, F. I; Kebede, M. A
    Alkaline earth stannates are rare earths and are crucial material systems evident of their attractive physical properties. They are ternary metal oxide semiconductors.They have both perovskite structures (BaSnO3, SrSnO3) and spinel structures(ZnSnO4).They are compounds of tin (Sn). Broadly, these compoundsexhibit elevated melting-points, elevated thermal stability, great thermal expansion coefficient, excellent chemical resistance, small thermal conductivity and great ionic conductivity which guarantee their possible applicacability in thermal barrier coating, hosts for luminescence centers, hosts for nuclear wastes, oxygen monitoring sensors, high-temperature catalysts, solar cells applicability and solid electrolytes in large temperature fuel cells. When these materials are produced as nanoparticles, the decreased particle size as well as enlarged specific surface area could result in diverse phase transition temperatures, improved catalytic activity, and enhanced processability. Commonly, these rare earth complex oxide nanomaterialscould be fabricated via conventional solid-state reactions, coprecipitation, sol-gel, hydrothermal, self-propagation techniques, etc.In the background of energy crisis, climate change, long-term supply and security, solar energy is a striking source. For these stannates to be better utilized in solar energy harvesting applications, they are better doped.The stannates considered here are SrSnO3, BaSnO3 and ZnSnO4.The doped stannates are used in various ways as stated above and equally as transparent conductors, light absorbers, photoanodes, etc. This is in relation to optical properties.The Optical properties, structural order and surface properties of these materials are considered. On doping, thesestannates maintain excellent transparency which makes them excellent materials as transparent conductor particularlyZnSnO4. They are found highly useful in photocatalysis and other areas.In solar energy harvesting, solar energy harvesting devices could have a better output when nanostructures like doped stannates are incorporated in them. Such advance is hopeful. It improves the power conversion efficiencies (PCE) of such devices by utilizing new nanostructures to update device structural designs. This is an applauded process.
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    A STUDY OF CHEMICALLY DEPOSITED OXIDE- BASED TERNARY THIN FILM OF ZINC TITANATE (ZnTiO3) DOPED WITH NATURAL DYES AND THEIR POTENTIAL PHOTOVOLTAIC APPLICATIONS.
    (journal of nano and material science research, 2025) Eze, C. N.
    The ternary metal oxide thin film of ZnTiO3 doped with three different natural dyes were synthesized on glass substrate via solution growth (SG) at room temperature. Chemical baths were used which contained Zinc Sulphate (ZnSO4.7H2O), Sodium Hydroxide (NaOH), Titanium Chloride (TiCl3), distilled water and calibrated drops per bath of organic dyes: Lawsonia inermis, Beta vulgaries and Jatropha curcas respectively. Each deposit which was set at a temperature of 80 0C lasted for 1 h and each deposit was annealed at 400 0C for 1 h. These deposited nano thin films were characterized for their structural, morphological, optical properties, elemental composition and electronic (chemical) structure and presence of functional groups by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), UV-VIS spectrophotometer, Energy Dispersive X-ray Fluoroscopy (EDXRF) and photoluminescence Fourier Transform Infrared Radiation Spectroscopy (FTIR). Polycrystalline thin films were evidenced which marked porosity offered them maximum surface area for dye loading which is critical for photosensitization in dye sensitized solar cells (DSSCs). Such doping presented band gaps of doped ZnTiO3 from 1.84 eV to 3.45 eV depending on dopants applied as against undoped film band gap that was 3.55 eV. The FTIR results showed good photophysical, carboxylate and modification properties of the dyes which helps in sunlight harvesting, anchoring and surface structure modification of the films. The dye influenced the optical properties of the samples and in particular, the reduction of the energy band gap, Eg from an increase in absorption coefficient α, giving high absorbance A, low extinction coefficient k, low reflectance R, which inferred its potential applications in solar energy devices when used in construction, poultry houses, solar cells and DSSCs.
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    Optical Properties of PbSe, PbS, and PbTe Semiconductor Quantum Dots and their Applications
    (2025-08) Ikeri, H.I; Harry, S.T; Achuka, E.I; Eze, C. N.; Asielue, O.K; Ndubueze, N.D
    Abstract - Optical properties of PbSe, PbS, and PbTe semiconductors in confinement regimes have been studied using the Brus equation. The results indicate that QDs exhibit size-dependent optical behavior and, hence, tunable bandgaps and emission wavelengths as a consequence of quantum confinement. As the QD size decreases, the absorption edge and emission peak are blue-shifted for all three materials. It is found that PbSe QDs display significant quantum confinement even at larger sizes. Due to its relatively large exciton Bohr radius (~46 nm), as the size decreases from 10 nm to 2 nm, the bandgap increases from 0.27 eV to over 1 eV, shifting absorption and emission into the near-infrared (NIR), leading to applications into NIR photodetectors, solar cells, and biomedical imaging. Also, PbS QDs exhibit significant quantum confinement effects at smaller sizes due to their smaller exciton Bohr radius (~20 nm) compared to PbSe. The bandgap increases from 0.41 eV to around 1.5 eV as the size decreases from 10 nm to 2 nm, shifting absorption and emission from the NIR into the visible range. This is utilized in solar cells, visible to NIR photodetectors and LEDs. Furthermore, PbTe QDs also exhibit pronounced quantum confinement effects because of their relatively large exciton Bohr radius (~46 nm). The bandgap increases from 0.32 eV to around 1 eV as the size decreases from 10 nm to 2 nm, shifting absorption and emission into the NIR and Mid-Infrared (MIR) regions, making them excellent materials for infrared detectors, thermoelectric and MIR applications. Among the semiconductor materials studied, PbS QD typically exhibits the largest increase in bandgap with decreasing size, making them suitable for applications requiring larger bandgap tunability, followed by PbSe and PbTe. These different optical characteristics are due to their unique electronic properties and exciton Bohr radii.
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    Mathematical Analysis of the Transmission Dynamics of Hepatitis B Virus
    (Springer Science and Business Media LLC, 2025-05-15) F.A. Oguntolu; O.J. Peter; D. Aldila; G. B. Balogun; O. P. Ogunmola; B. I. Omede
    Hepatitis B is a life-threatening hepatic illness induced by the Hepatitis B virus (HBV). This is a major worldwide health issue, especially in low- and middle-income nations in Africa and the Western Pacific, where prevalence rates are the greatest. Nevertheless, the existence of an efficacious vaccination, Hepatitis B persists in inflicting significant morbidity and death owing to a deficiency of awareness regarding the illness. Thus, we developed a deterministic mathematical model to elucidate the transmission dynamics of Hepatitis B, integrating elements such as vertical transmission, re-infection, and environmental viral concentration. The study starts with the calculation of the basic reproduction number and the assessment of the local stability of the disease-free equilibrium employing the Routh-Hurwitz criteria. A comprehensive examination of the model indicates that the model may experience backward bifurcation phenomena under some specific conditions. This trait presents considerable challenges in the proper management of Hepatitis B infection among the population. Assuming no re-infection of Hepatitis B post-recovery, the disease-free equilibrium point is globally asymptotically stable when the basic reproduction number is less than or equal to one. The sensitivity analysis of the basic reproduction number was conducted to assess the influence of each fundamental parameter in the model that contributes to disease transmission. Utilizing the optimal control theory to effectively curb the spread of Hepatitis B, we incorporated two time-varying control strategies, namely the prevention of susceptible individuals from acquiring HBV (through safe sex practice, regular washing of hands, and using protective hand gloves when handling blood, body fluid and semen) and the sensitization on individuals on personal hygiene, sterilization and proper disposal of medical and dental equipment like syringes in order to reduce the shedding of HBV in the environment. The numerical simulations indicated that Hepatitis B infection may be effectively managed and mitigated within the community if both control measures are correctly implemented.
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    Mathematical model of COVID-19 transmission dynamics incorporating booster vaccine program and environmental contamination
    (Elsevier BV, 2022-11) N.I. Akinwande; T.T. Ashezua; R.I. Gweryina; S.A. Somma; F.A. Oguntolu; A. Usman; O.N. Abdurrahman; F.S. Kaduna; T.P. Adajime; F.A. Kuta; S. Abdulrahman; R.O. Olayiwola; A.I. Enagi; G.A. Bolarin; M.D. Shehu
    COVID-19 is one of the greatest human global health challenges that causes economic meltdown of many nations. In this study, we develop an SIR-type model which captures both human-to-human and environment-to-human-to-environment transmissions that allows the recruitment of corona viruses in the environment in the midst of booster vaccine program. Theoretically, we prove some basic properties of the full model as well as investigate the existence of SARS-CoV-2-free and endemic equilibria. The SARS-CoV-2-free equilibrium for the special case, where the constant inflow of corona virus into the environment by any other means, Ω is suspended (Ω=0) is globally asymptotically stable when the effective reproduction number 𝑅0⁢𝑐<1 and unstable if otherwise. Whereas in the presence of free-living Corona viruses in the environment (Ω>0), the endemic equilibrium using the centre manifold theory is shown to be stable globally whenever 𝑅0⁢𝑐>1. The model is extended into optimal control system and analyzed analytically using Pontryagin's Maximum Principle. Results from the optimal control simulations show that strategy E for implementing the public health advocacy, booster vaccine program, treatment of isolated people and disinfecting or fumigating of surfaces and dead bodies before burial is the most effective control intervention for mitigating the spread of Corona virus. Importantly, based on the available data used, the study also revealed that if at least 70% of the constituents followed the aforementioned public health policies, then herd immunity could be achieved for COVID-19 pandemic in the community.
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    Estimating the Heat Flow, Geothermal Gradient and Radiogenic Heat within the Young Granites of Jos Plateau North Central Nigeria
    (University of Tehran Press, 2024-02) Adetona, A. A; Rafiu, A. A; Aliyu, B. Sh; John, M. K; Kwaghhua, I. F
    Both aeromagnetic and radiometric data were used to evaluate the Curie point depth and radiogenic heat production (RHP) of the young granitic regions of the Jos Plateau. An area of 55 by 110 square kilometers is bounded by latitude 9°30' to 10°00' N and longitude 8°30' to 9°30' E in central Nigeria. The magnetic data was subjected to spectral analysis to obtain the Curie depth, which was subsequently used to evaluate the geothermal gradient and heat flow for the area. Also, the concentration of radioelements (potassium, thorium and uranium) and the average density of the in-situ rock were used to estimate the radiogenic heat production at each point where the Curie point was evaluated. The heat flow in the study area ranges from 10 to 165.5 mW/m2 with an average value of 111.00 mW/m2. The regions with anomalous heat flow of 165.5 mW/m2 are located around Bowon Dodo, Dan Tsofo, Kadunu, Gimi, Kaura and Zankan in plateau state. The geothermal gradient values range from 5 to 68 °C/Km with an average of 26.16 °C/Km. The radiometric data analysis resulted in radiogenic heat values ranging from 0.4 µWm3 to 6 µW/m3 with an average radiogenic heat value of 3.36 µW/m3. Both analyses revealed that regions such as Ataka, Gimi, Jimjim and Pari could be investigated for geothermal energy potential. The high concentration of uranium, thorium and potassium associated with the study area is likely due to the weathering of the in-situ granitic basement rocks.