Faculty of Science

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Now showing 1 - 20 of 257
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    Genetic Diversity and Relationship of African Sheep-A Y Chromosome Perspective
    (Egerton University, 2007-01) Ouna, Benard Aswani
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    Human Exposure to Lead in Selected Areas in Olkalou and Nairobi, Kenya
    (Egerton University, 2007-09) Kimani, G. Njoroge
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    Mathematical Models Applicable in Business Investments
    (Egerton university, 2004-10) Manyanga, David Ondiek
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    Milk Fat Changes in Accelerated Shelf Life Testing of Ready-To-Fry Chapati
    (Egerton university, 2004-04) Chitsaka, Grace Mwangome
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    Model-Based Assessment of Trends for some Communicable Diseases in Kenya
    (Egerton university, 1999-10) Kiprotich, James Rutto
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    Optimal Harvesting in Matrix Population Models
    (Egerton university, 1993-12) Oguna, Bernard Omolo
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    The Local Field and Orientational Order Parameter in Nematic and Smectic Liquid Crystals
    (Egerton University, 1995) Mukhebi, Lutta Abraham Michael.
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    The Ecology of Benthic Communities in a Tropical Mangrove Forests at Gazi Bay, Kenya
    (Egerton University, 2008-04) Kubasu,Kizito Masinde
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    Analysis of Selected Toxic Heavy Metals and Pesticide Residues in Catha Edulis from Selected Regions in Meru County, Kenya
    (Egerton University, 2024-09) Oyugi, Albert Morang’a
    Heavy metal and pesticide pollutions on environmental matrices and their potential human toxicity have attracted considerable attention worldwide in recent years. The desire to increase food production to satisfy the ever rising population has resulted in the use of potentially toxic pesticides and fertilisers. The application of these chemicals in modern farming technologies is a source for potentially toxic heavy metals and pesticide residue levels in human consumables such as foodstuffs, which may ultimately trigger adverse health effects. Accordingly, this study focused on the concentration profiles of cadmium (Cd), lead (Pb), chromium (Cr), iron (Fe), nickel (Ni), and copper (Cu) and pesticide residues in 11 khat (Catha edulis) samples randomly sourced from 11 farms within regions of Meru County, Kenya. These analyses are meant to evaluate any associated human health risks through comparison with the World Health Organisation/ Food and Agriculture Organisation (WHO/FAO) safe limits. Human health risk assessment was done using target hazard quotient (THQ) and health index (HI). Inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis gave results of heavy metal concentrations (mg/kg) in dry khat samples as follows; Cd (7.81 ± 1.56), Cr (15.98 ± 2.22) and Pb (32.35 ± 9.95), indicating all was above the acceptable WHO/FAO limits. The levels of Ni, Cu and Fe heavy metals were below permissible limits and may benefit important human biological functions. The Pb and Cd THQ values and the HI of all investigated heavy metals in the khat samples exceeded the threshold value of 1.0. This suggests that the excessive consumption of Meru khat-based products, poses a potential health risk to the consumers. Besides, the gas chromatograph-mass spectrometry (GC-MS) results showed the detection and identification of pyrethroid and organophosphate pesticides representing 54.5% pesticide contamination prevalence rate of the sample size. The Ultraviolet-Visible (UV-Vis) quantification results revealed that acephate and cypermethrin residue levels in khat samples were below maximum residue limits (MRLs) thus, there is no acephate and cypermethrin pesticide contamination reported from this study. Consequently, Meru khat farmers should regularly be educated on safe post-harvest practices to protect consumers. Therefore, the results of this work are important in sensitizing khat farmers that the use of agro-chemicals should significantly be minimized or avoided on farms and encourage on alternative farming practices that do not potentially increase potentially toxic heavy metals and residues in khat. Regular monitoring and evaluation of pesticide residues and heavy metals in khat products is necessary to ensure public and environmental health.
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    Secondary Metabolites from Juniperus Procera with Activity against Selected Maize and Bean Pathogens
    (Egerton University, 2024-09) Nduati, Teresia Wangui
    Maize (Zea mays) and beans (Phaseolus vulgaris L.) are important food crops in Kenya however, these crops have registered a decline in yields which is partly due to attack by fungal and bacterial pathogens. These pathogens are currently managed by use of synthetic pesticides, whose long term and widespread use has led to negative impacts which has endangered the environment in general. Extracts from Juniperus procera have been used as traditional medicine in treatment of various human pathogens. Scientific research has also proved efficacy of its various secondary metabolites towards human pathogens but minimal research has been done on their activity towards phytopathogens. This study, therefore, aimed at isolating secondary metabolites from the bark and leaves of J. procera with activity against three important plant pathogens; Xanthomonas axonopodis pv. phaseoli and Pseudomonas savastanoi pv. phaseolicola whose host is common bean and a maize pathogen Fusarium graminearum. The leaf and bark samples were collected from Mount Elgon National Park Forest, dried under shade and ground into a fine powder. Solvent extraction method was used to extract secondary metabolites from the powdered plant material whereby the powder was first soaked in methanol, filtered and solvent evaporated to obtain methanol extract. The methanol extract was suspended in water and partitioned between hexane and ethyl acetate to obtain ethyl acetate, hexane and aqueous extracts. The ethyl acetate extracts were purified using various chromatographic techniques. The pure compounds were analysed using 1D and 2D NMR and their masses determined using mass spectrometry. A flavonoid was isolated from the bark; epicatechin (12) while a biflavonoid and a diterpenoid were isolated from the leaf; podocarpusflavone A (13) and juniperolide (14) respectively. Disc agar diffusion assay was used to test the extracts and pure compounds against the three phytopathogens. Crude extracts were more active against the bacterial pathogens than the semi-pure fractions. For example, methanol and aqueous crude extracts from leaf had highest inhibition zones of 18.0 and 17.3 mm respectively against P. savastanoi pv. phaseolicola. Compound 12 had the highest inhibition zone of 21 mm against P. savastanoi pv. phaseolicola. Both compound 13 and 14 registered inhibition zones of 8 mm against P. savastanoi pv. phaseolicola. The extracts and the pure compounds did not show activity towards F. graminearum. It can therefore, be concluded that this medicinal plant can be a source of compounds to be used in control of important plant bacterial pathogens.
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    Investigation of 60Co Gamma Irradiation as a Technique for Leather Processing
    (Egerton University, 2024-09) Chebwogen, Mercy
    Leather industry is considered an eco-friendly industry because it converts meat by-products which would have otherwise been thrown into other landfills, into precious eco-benign products. Environmental implications related to this industry during processing present bleak prospects. However, green chemistry has been earmarked as a potential measure to curtail pollution though the quality of the resultant leather is inferior to that of synthetic processing. Therefore, measures to enhance the viability of green chemistry leather processing are necessary. Gamma radiation coupled with vegetable tanning agents is a viable processing method to improve leather properties and strength. Proper preservation and processing of hides and skins in the tannery determines the quality of the final product. In this study, seven samples (100 g) were cut, and one sample was preserved with bactericide, while the other six were irradiated with different doses of gamma radiation (0, 10, 20, 30, 40, and 50 kGy) using 60Co gamma irradiator Model GC 220E. Isolation of bacterial load was done for all samples and colony-forming units (CFU) were counted using plate count method. The remaining hide proceeded for processing up to pickling stage where the hide was cut into two halves along the backline. Both halves were cut into equally smaller samples for irradiation and then tanned using mimosa tannins and chromium salts. Dog-bone-shaped samples cut parallel and perpendicular to the backline from the irradiated pelt were tested for tensile properties using the Instron Testing Machine, Model 1101. The effect of sampling direction, tanning agents, and gamma radiation on the tensile properties was determined. Leather samples of dimension 30 mm 9.3 mm 0.93 mm were aged in a heat-adjustable cabinet at 80 for 24 hours and UV- cabinets (UV-C, 254 nm) for 144 hours and conditioned for 48 hours in a normal atmosphere before Dynamic Mechanical Analysis tests. The effect of gamma radiation on viscoelastic properties and photo and thermal stability of both chrome and mimosa-tanned leather was determined. The microbial load of hide treated with bactericide was reduced and when irradiated at 10 kGy of radiation, there was a significant reduction. The tensile strength was increased up to 30 kGy dose of radiation for both chrome and mimosa-tanned leather. On the other hand, the thermal and photostability of both leathers showed some variation with increasing doses of radiation. Gamma radiation as compared to bactericide reduced the microbial load of hides significantly contributing to a cleaner preservation approach of hides and skins in tanneries. Doses of up to 30 kGy induce additional crosslinks to the leather thus enhancing the strength and stability of the processed leather. Thus, this study recommends the incorporation of gamma radiation during leather processing.
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    Evaluation of Meat Quality of Spent Hens Fed On Black Soldier Fly (Hermetia Illucens) Larvae Based Diet and Of Bread From Wheat Flour Enriched With Spent Hen Meat Powder
    (Egerton University, 2024-09) Marcasy Phanice Makokha
    The utilization of insect protein in poultry feed is globally gaining momentum. However, the meat quality of hens fed on diet with black soldier fly larvae meal (BSFLM) as fishmeal (FM) substitute has received limited research attention. Off layers are usually sold at a very cheap price and hence the need to diversify their use. Wheat bread is among stable foods that are low in essential amino acids, thus enrichment is crucial. The birds were subjected to four diets –FM substituted with varying rations of black soldier fly larvae meal (T1-0% BSFLM- control, T2-25% BSFLM, T3-50% BSFLM, T4-75% BSFLM and T5-100% BSFLM). Fifteen birds per feeding group were slaughtered after 80 weeks and processed into meat powder. Refined wheat flour was then blended with 0%, 20%, 25%, 30% levels of the meat powder from hens fed on diet with 50% Black Soldier Fly Larvae Meal to produce high-valued bread products. The meat powders and bread from each treatment were subjected to proximate composition, mineral, amino acids, fatty acids and vitamin profiles analysis. The processed loaves of bread were further analysed for microbial quality and consumer acceptability. Results showed that the feed substitution did not affect the proximate compositions of the meat products. Omega 3 fatty acids were uninfluenced (P < 0.05) whilst the total monounsaturated fatty acids progressively increased with increasing dietary inclusion of Black Soldier Fly Larvae Meal. Lysine, methionine, and isoleucine were significantly higher (P < 0.05) in insect-fed hen meat products. The levels of zinc and B vitamins except B1 were proportionally enhanced in the chicken fed Black Soldier Fly Larvae Meal incorporated diet. Crude protein, ash, Omega 3 fatty acids and vitamins (retinol, nicotinic acid, and pantothenic acid) were significantly increased in supplemented bread products. Limiting amino acids like lysine and threonine in enriched bread products increased by 3.0–4.5 and 1.8–3.1-folds, respectively. Iron, zinc, and calcium increased by 1.1, 1.2 and 3.0-folds in bread with 30% meat powder. Overall acceptability of breads prepared with 25 and 30% meat powder were highly ranked. These results provide valuable information on the applicability and suitability of meat powder from hen fed insect based meal (IBM) as novel ingredient in the development of new functional food products to address rampant global malnutrition.
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    Trends and Determinants of Neonatal Mortality in Kenya Analysis of the Kenya Demographic Health Survey 1998-2014 and a Validation Study within Nakuru Municipality
    (Egerton University, 2024-09) Imbo E. Akinyi
    Globally, there has been a marked decline in neonatal mortality and overall child mortality indicators from 1990 to date. In Kenya, however, neonatal deaths contribute to 40% of under-five mortality rates (U5MR) making it an important health priority. This study analysed trends and determinants of neonatal mortality in Kenya from 1998 to 2014 utilizing data from the Kenya Demographic and Health Surveys (KDHS) and primary data from a study at the Nakuru Level 6 Hospital. Study results from logistic regression analysis showed that mother’s wealth status was a significant predictor of neonatal morality as mothers from the poorest households had higher odds of neonatal deaths (OR=1.9, p=0.015, CI=95%) in 2003 and (OR=1.09, p=0.0046) in 2014. The study found that level of education was a significant predictor of neonatal deaths. In the analysis conducted in 2003, mothers with primary education had twice the likelihood of losing their infants in the neonatal period (OR=2.06, p=0.037, CI=95%). This trend continued in 2008 (OR=2.15, p=0.01, CI=95%) and 2014 (OR=3.127, p=0.014, CI=95%). Additionally, infants born with low birth weight (LBW) had a higher risk of death within the first 28 days. The results from 2003 showed an odds ratio of (OR=23.08 p=0.006, CI=95%), while in 2008 it was (OR=18.216, p=0.042, CI=95%), and in 2014 it was (OR=9.59, p=0.04, CI=95%), compared to neonates weighing more than 3.5 kilograms at birth. Mothers who delivered in hospitals had a lower likelihood of neonatal deaths (OR=0.78, p=0.012, CI=95%) in 1998 and (OR=0.062, p=0.043, CI=95%) in 2008 compared to mothers who delivered at home. Mothers who did not attend ANC during pregnancy were 5 times more likely to experience neonatal deaths (OR=5.571, p=0.005, CI=95%) in 1998, (OR= 2.163, p=0.033, CI=95%) in 2008 and (OR=9.636, 0.027, CI=95%) in 2014 compared to mothers who attained the recommended >4 ANC visits. Based on analysis of the primary data collected in Nakuru, low birth weight emerged as a significant predictor of neonatal deaths. The study therefore recommends prioritization of enhancement of maternal health and nutrition education during pregnancy to reduce incidences of low birth weight through increased antenatal visits. Additionally, implementing universal health care and promoting sustained community referrals can encourage hospital deliveries and decrease the occurrence of new-born deaths due to complications that may arise after birth. Emphasizing girls' education is also crucial in ameliorating the adverse effects of low mother literacy on neonatal survival
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