Department of Physical Sciences

Permanent URI for this collectionhttp://localhost:4000/handle/20.500.12092/1963

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Start date: 2011End date: 2019

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Now showing 1 - 10 of 21
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    Hydromagnetic Turbulent Flow Between Two Parallel Infinite Plates
    (Science Journal of Applied Mathematics and Statistics, 2017) Karimi, Kennedy John Mwangi; Kinyua, Dickson Kande
    In this study we shall investigate hydromagnetic turbulent unsteady flow of an incompressible electrically conducting fluid between two parallel infinite plates. The flow variables such as velocity and thermodynamic properties at every point of fluid vary with respect to time. The effect of an applied transverse magnetic field normal to the main flow direction on the dynamic behavior of the fluid when the lower plate is stationary and the upper plate is impulsively started in opposite direction at constant velocity shall be investigated. Further, we shall investigate how the various parameters such as Peclet Number and Eckert Number affect the flow; in particular, velocity and temperature profiles. A finite difference method shall be used to solve the coupled non-liner and dimensionless partial differential equations governing this problem
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    Anti-Pyretic Properties of Methanolic Bark Extracts of Terminalia brownii in Wistar Rats ( Rattus novegicus )
    (J Pharmacogn Nat Prod, an open access journal, 2016) Mbinda, Wilton; Kasili, Sichangi; Mbiri, Jane W; Kisangau, Patrick D; Piero, Ngugi M
    The conventional drugs used to manage fever are usually not affordable, not easily available and have adverse side effects. Alternative therapeutic agents, like medicinal plant derivatives, should therefore be developed because they have been reported to be more affordable, more readily available and have lesser side effects. Terminalia brownii is traditionally used to manage fever but this ethno-medicinal claim lacks scientific validation. The present study therefore evaluated the anti-pyretic activity of T. brownii in Wistar rats. Fresh bark samples of T. brownii were collected from Kitui County, Kenya. This study used 30 adult male Wister rats that were 2-3 months old and weighing 140-180 g was used for the experiments. Steam-distilled turpentine was the pyrogen used to induce pyrexia and Aspirin was used as the reference drug. The extract reduced the elevated rectal temperatures by between 1.154.38% while aspirin reduced the elevated rectal temperatures by between 0.00-4.85%. The present study showed a significant dose-dependent anti-pyretic activity of methanolic bark extracts of T. brownii hence validating its folklore use as a fever remedy.
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    Anti-Pyretic Properties of Methanolic Bark Extracts of Terminalia brownii in Wistar Rats (Rattus novegicus)
    (Journal of oJ Pharmacognosy & Natural Products, 2016) Mbinda, Wilton; Kasili, Sichangi; Mbiri, Jane W; Kisangau, Patrick D; Piero, Ngugi M
    The conventional drugs used to manage fever are usually not affordable, not easily available and have adverse side effects. Alternative therapeutic agents, like medicinal plant derivatives, should therefore be developed because they have been reported to be more affordable, more readily available and have lesser side effects. Terminalia brownii is traditionally used to manage fever but this ethno-medicinal claim lacks scientific validation. The present study therefore evaluated the anti-pyretic activity of T. brownii in Wistar rats. Fresh bark samples of T. brownii were collected from Kitui County, Kenya. This study used 30 adult male Wister rats that were 2-3 months old and weighing 140-180 g was used for the experiments. Steam-distilled turpentine was the pyrogen used to induce pyrexia and Aspirin was used as the reference drug. The extract reduced the elevated rectal temperatures by between 1.15- 4.38% while aspirin reduced the elevated rectal temperatures by between 0.00-4.85%. The present study showed a significant dose-dependent anti-pyretic activity of methanolic bark extracts of T. brownii hence validating its folklore use as a fever remedy.
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    Water Resources and Management under Increasing Urban Demography: A Kenyan Perspective—A Review
    (Journal of Water Resource and Protection, 2018) Ondigo, Deziline Adhiambo; Kebwaro, Jeremiah; Kavoo, Agnes Mumo
    The United Nations classifies Kenya as a water-scarce country since it has less than 1000 m3 per capita of renewable freshwater supplies. Numerous factors including global warming, contamination of drinking water, and a lack of investment in water resources have aggravated the water crisis in Kenya. Estimates indicate that only about 56% of its population has access to safe water supply. Like many developing countries, Kenya recognizes the crucial role of water in realizing its development goals. Its economic performance and poverty reduction are critically dependent on clean water availability for agriculture, industrialization, energy production and tourism among others. Similar to most developing countries, Kenya suffers from lack of human, monetary and institutional capabilities to efficiently provide clean and sufficient water to its citizens. The water shortage in the major cities is acute and chronic and has continued to worsen with increasing urbanization, water pollution and encroachment of water catchment areas by humans and invasive plant species. Despite the water challenges facing the urban populations, Kenya possesses sufficient water resources to meet demand if the available resources are properly managed. Several initiatives are being put in place in Kenya to mitigate the water challenges and protect water resources in Kenya. These include enacting of water policies to protect water catchment areas, reduce pollution and enhance access to clean water.
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    Analysis of the Impact of Cross-sectional Data Discrepancies on the Effectiveness of Radiation Shielding Design Using Monte Carlo Codes
    (International Journal of Physics, 2019) Kebwaro, Jeremiah Monari
    The effect of cross-sectional data discrepancies on the effectiveness of radiation shielding design has been investigated in this paper. The MCNP code with cross-sections from ENDF/B-V and ENDF/B-VII has been used to determine the gamma ray dose equivalent, H*(10), behind a lead glass shield enclosing a slow neutron source. It is observed that the radiative capture gamma ray dose behind the shield is higher when ENDF/B-V cross-sections are used compared to that produced by ENDF/B-VII cross-sections. The discrepancy is due to absence of energetic primary gamma rays when ENDF/B-VII is used. The results show that shielding design using ENDF/B-VII cross-sections could underestimate the shield by a fair margin and compromise safety. It is therefore necessary to consider more than one release of ENDF/B when using lead glass for shielding slow neutron capture gamma rays. The discrepancies need to be addressed in the next releases.
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    Evaluation of In vivo Toxicity of Methanolic Leaf Extract of Vernonia lasiopus (O. Hoffman)
    (Journal of Pharmacognosy & Natural Products, 2017) Mbinda, Wilton M; Ngugi, Mathew P; Koech, Samson C; Muthoni, Beatrice G; Musila, Michael N
    The main objective of this study was to evaluate the in vivo toxicity of methanolic leaf extract of Vernonia lasiopus. To provide information on the safety of V. lasiopus, we evaluated its acute and sub-chronic toxicity in Wistar rats. For evaluation of acute toxicity of the plant extract, five Wistar rats were orally dosed with 2000 mg/kg body weight sequentially. Sub-chronic toxicity was tested in twenty Wistar rats using three extract doses 100, 300 and 1000 mg/kg body weight. They were orally administered for 28 days. Mortality and toxicity signs were monitored during the study period. At the end of the experiment, the animals were sacrificed, their internal organs weighed and blood samples collected for haematology and biochemical analysis. In acute toxicity, no single death was reported; leading to conclusion that the median lethal dose (LD50) of methanolic leaf extract of V. lasiopus is beyond 2000 mg/kg body weight. In sub-chronic toxicity studies, V. lasiopus lowered total proteins in all the study groups significantly. Albumin was also lowered at extract dose of 1000 mg/kg body weight. In addition, it resulted to significant neutropenia, lymphocytosis and thrombocytosis in the group administered with dose extract of 1000 mg/kg body weight (P˂0.05). It was therefore concluded that methanolic leaf extract of V. lasiopus is safe for use when administered at therapeutic doses. The plant extract may also be useful in the management of haematological disorders especially thrombocytopenia.
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    Critical temperature and condensate fraction of a bose – einstein condensate trapped in a finite volume
    (Centre for Info Bio Technology, 2014) Mukoya, AK; Sakwa, TW; Khanna, KM; Ayodo, YK; Sarai, A; Rapondo, BW; Namwitako, J
    Bose - Einstein Condensation, BEC, of an ideal gas is investigated for a finite number of particles trapped in a harmonic potential. The values of the critical temperature for Rb-87, its condensate fraction and the energy per particle are determined. The maxima appear to increase with the number of particles due to the fact that a smaller system has a larger available effective volume which concurs with the behavior of the critical temperatures.
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    Anti-inflammatory properties of methanolic bark extracts of terminalia Brownii in wistar albino rats
    (Innovare academic sciences pvt ltd., 2016-06) Wilton, Mbinda; Wanja, Mbiri J.; Sichangi, Kasili; Kisangau, Patrick; Ngugi, M. Piero
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    Reproducibility of (n,γ) gamma ray spectrum in Pb under different ENDF/B releases
    (Elsevier, 2016-02) Kebwaro, Jeremiah Monari
    Radiative capture reactions are of interest in shielding design and other fundamental research. In this study the reproducibility of (n,γ) reactions in Pb when cross-section data from different ENDF/B releases are used in the Monte-Carlo code, MCNP, was investigated. Pb was selected for this study because it is widely used in shielding applications where capture reactions are likely to occur. Four different neutron spectra were declared as source in the MCNP model which consisted of a simple spherical geometry. The gamma ray spectra due to the capture reactions were recorded at 10 cm from the center of the sphere. The results reveal that the gamma ray spectrum produced by ENDF/B-V is in reasonable agreement with that produced when ENDF/B-VI.6 is used. However the spectrum produced by ENDF/B-VII does not reveal any primary gamma rays in the higher energy region (E > 3 MeV). It is further observed that the intensities of the capture gamma rays produced when various releases are used differ by a some margin showing that the results are not reproducible. The generated spectra also vary with the spectrum of the source neutrons. The discrepancies observed among various ENDF/B releases could raise concerns to end users and need to be addressed properly during benchmarking calculations before the next release. The evaluation from ENDF to ACE format that is supplied with MCNP should also be examined because errors might have arisen during the evaluation.
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