Faculty of Science

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EFFECTS OF SCIENCE PROCESS SKILLS MASTERY LEARNING APPROACH ON SECONDARY SCHOOL STUDENTS’ ACHIEVEMENT AND ACQUISITION OF SELECTED CHEMISTRY PRACTICAL SKILLS IN KOIBATEK DISTRICT SCHOOLS, KENYA
(Egerton University, 2011-03) CHEBII , ROSELYN J.A
Chemistry is one of the science subjects which are taught in Kenyan secondary schools. One of the objectives for teaching chemistry is to enable learners to use knowledge and skills acquired to solve problems in everyday life. Achievement of this objective depends on the methods and techniques employed by teachers during instruction. The method used can either enhance or hamper the learner’s interest in the subject and hence affect the overall performance of school learning. The Kenya National Examinations Council (KNEC) reports that secondary school students’ performance in chemistry practical papers is poor and this affects their overall achievement in Chemistry. Poor achievement in chemistry may be a result of the methods teachers use. This study was designed to investigate the effectiveness of Science Process Skills Mastery Learning Approach (SPROSMALEA) on students’ achievement and acquisition of selected science processes skills. The study was carried out in Koibatek District, Kenya, where a persistent low achievement in the subject has been registered. The study focused on the topic “salts” in Form Two chemistry syllabus. The Solomon Four Group, Non-equivalent Control Group Design was employed in the study. Four co-educational schools were purposively selected from the 35 secondary schools in the District and randomly assigned to serve as experimental group (E1), experimental group (E2) control group (C1) and control group (C2). Data were collected from a sample of 160 Form Two students. Three instruments namely, Chemistry Achievement Test (CAT), Science Process Skills Performance Test (SPSPT) and Classroom Observation Schedule (COS) were used for data collection. The instruments were pilot tested in two secondary schools in Koibatek District which were not part of the study but had similar characteristics as the sampled schools. This was to ascertain their suitability, establish its validity and reliability. Two groups, the experimental (E1) and control group (C1) were pre-tested, experimental group (E2) and second control group (C2) were not. All groups were taught the same course content for a period of four weeks, with the experimental groups receiving their instruction by use of (SPROSMALEA) approach and control groups using the conventional teaching method. During the teaching COS was used to observe and record the activities of the teachers and learners. A post-test on CAT and SPSPT was administered to all groups after the completion of instruction on the chemistry topic on salts. Both descriptive and inferential statistics were used to analyse the data using the Statistical Package for Social Sciences (SPSS) version 12.0 for Windows. ANOVA and ANCOVA were used to analyse differences in the four means of post-test scores. A t-test was used to get the differences between two means. Hypotheses of the study were tested at =0.05 level of significance. The results of the study indicate that students in the experimental groups outperformed the control groups in the achievement and the acquisition of selected chemistry practical skills. The findings further indicate that students’ and teachers’ activities during the instruction in the experimental groups had higher mean frequencies in COS than in the control groups. Science teachers, educators and policy makers are likely to benefit from the results and recommendations of the study in that it provides them with an alternative teaching approach which is capable of improving their achievement in the subject and acquisition of the desired practical skills.
Effects of jigsaw cooperative learning strategy on students’ achievement in secondary school mathematics in Laikipia East District, Kenya.
(Egerton University, 2013-04) MBACHO, WATETU NAOMI.
Secondary school students in Kenya have continued to perform poorly in mathematics in the Kenya Certificate of Secondary Education (K.C.S.E) national examinations. This raises concern for all stakeholders in education due to the importance they attach to mathematics. The factors that are attributed to the students‟ dismal performance in the subject include; inadequate facilities in the schools like the text books and qualified teachers, poor attitude towards the subject by the students and teachers, gender stereotypes, lack of role models, and the instructional methods used by teachers. This study sought to address the problem of ineffective instruction by teachers by finding out if the use of Jigsaw Cooperative learning Strategy during instruction of Surds and further logarithm in mathematics to form three students had effects on their performance. Surds and further logarithm are topics that are performed poorly in the KCSE. There is however inadequate documented information in research conducted in Kenya on effects of the use of Jigsaw Cooperative learning Strategy on students‟ achievement in mathematics. Solomon four non-equivalent control group design was used in the study. The two experimental groups received the Jigsaw cooperative learning Strategy as treatment and two control groups were taught using the conventional learning/teaching methods. A simple random sample of four district secondary schools was selected from Laikipia East District. The sample size was 160 students out of population of about 20,000 students in the district. A mathematics achievement test (MAT) was used for data collection. The instrument was piloted in a school which was not used in the study in the Laikipia East District. The instrument used had reliability coefficient of above the required threshold of 0.70. The instrument was validated by education experts from the Department of Curriculum and Instruction. Data was analyzed using t-test to test hypotheses at Coefficient alpha (ά) level of 0.05. Findings of this study show that learners taught using Jigsaw cooperative learning strategy performed better than those taught using Conventional learning methods. The results also show that there is no significant difference in achievement of girls and boys when taught using Jigsaw cooperative learning strategy. The findings are expected to be useful to students and teachers in secondary schools because they will be able to identify learning strategies which will enhance achievement in mathematics. Policy makers, curriculum developers and education officers are likely to benefit from this study in deciding on the appropriate learning strategy for learners to improve the quality of education in the country.
EFFECTS OF GOWIN’S VEE HEURISTIC TEACHING STRATEGY ON SECONDARY SCHOOL STUDENTS’ CONCEPTUAL UNDERSTANDING AND METACOGNITION IN THE TOPIC OF MOMENTS IN PHYSICS, IN UASIN GISHU COUNTY, KENYA
(Egerton Unversity, 2015-09)
Physics is a science subject that has contributed immensely to the technological advancement of the world. In the Kenyan 8-4-4 curriculum, it is optional at form three. However, various studies show that physics in Kenya has been faced with poor performance. Consequently, many students drop out of the subject. Educational researchers have partially attributed the cause to be poor instructional methods. This study attempts to change this trend in the topic of moments in physics. Data were collected on the effects of Gowin’s Vee heuristic strategy on secondary school students’ conceptual understanding and metacognition in the topic of moments in physics in Uasin Gishu County Kenya. Solomon four non equivalent control group design was used. Two experimental groups were taught using Gowin’s Vee and two control groups were taught using conventional methods. The target population was 3735 form two students in 83 mixed secondary schools. Purposive sampling was used to select 134 students. The instruments used were Physics Metacognitive Activity Inventory Questionnaire (PMCAIQ) and Physics Conceptual Understanding Achievement Test (PCUAT). Their validities were determined by supervisors and science education experts of Egerton University and physics teachers. Estimations of reliabilities using Chronbach coefficient of alpha gave 0.75 and 0.78 for PCUAT and PMCAIQ respectively. Analysis using means and standard deviations was done. Also sample t-test, one way ANOVA and post hoc analysis were done at coefficient of alpha (α) equal to 0.05 level of test of significance using Statistical Packages for Social Sciences. Gowin’s Vee had statistically significant improvement on students’ conceptual understanding and metacognition in the topic of moments in physics hence it improved students’ conceptual understanding and metacognition. Therefore teachers should use it in teaching this topic and other topics in physics. This study is important in enhancing performance and quality of teaching in the topic of moments in physics and sciences in general.
EFFECTS OF FIREPLACE ADVANCE ORGANIZER TEACHING STRATEGY ON SECONDARY SCHOOL STUDENTS’ MOTIVATION AND ACHIEVEMENT IN CHEMISTRY IN BARINGO COUNTY, KENYA
(Egerton University, 2013-09) KIBET, KIPLAGAT DAVID.
Chemistry is a fundamental science and is responsible for many of the materials used in modern society as well as developments and tests carried out in the field of medicine. However, Kenya’s secondary school students’ performance in chemistry has been poor. This poor performance has been attributed partially to teaching methods used in the classroom.Thus, there is need to seek teaching strategies that can improve students’ performance in chemistry and motivate them. The use of Advance Organizer Teaching Strategy may stimulate active thinking and facilitate the integration of new information into established schemas. However, it is not clear how a Fireplace Advance Organizer Teaching Strategy would affect students motivation and achievement in Baringo County. This study sought to address this issue. The study used Solomon Four Non- Equivalent Control Group Design. Simple random sampling was used to obtain 8 sample schools from the 19 County single sex secondary schools in Baringo County. The 8 sample schools were assigned to the experimental and control groups. Each sample school provided a Form Three class with 45 students; hence 360 subjects were involved. Experimental groups were taught using a Fireplace Advance Organizer Teaching Strategy (FAOTS) while control groups were taught using the conventional methods. Prior to the study, teachers and students from experimental group were trained on the use of FAOTS. Experimental group (E1) and control group (C1) were pretested using Students’ Motivation Questionnaire (SMQ) and Chemistry Achievement Test (CAT) and all groups post-tested at the end of three weeks. The two instruments were pilot tested determine their reliability while their validity was ascertained by experts from the Deparment of Curriculum Instruction and Educational Management of Egerton University. The reliability coefficient for SMQ was 0.73 while that of the CAT was 0.98. Statistical Package for Social science (SPSS) was used for data analysis. Data was analyzed using descriptive statistics and inferential statistics, at α=0.05. The results of the study showed that students’ achievement and motivation are higher when FAOTS is used than when reqular methods are used. When FAOTS is used, boys’ in boys schools achieve higher motivation and achievement than girls’ in girls schools. Based on the findings, the study recommended chemistry teachers’ to revisit their teaching strategies and the teacher education programs to incorporate FAOTS in order to improve the learners’ performance.
Synthesis and characterization of silver sulphide-reduced graphene oxide nanocomposite for application in the photoactive and hole transport layers of organic solar cells
(Egerton University, 2025) Oyugi Ngure Robert
The demand for clean energy, occasioned by technological innovations, necessitates sustainable and cost-effective sources such as organic solar cells (OSCs), speciﬁcally bulk heterojunction polymer solar cells (BHPSCs). Inadequate light absorption and charge transport are the common challenges with these sources, which reduce their power conversion efficiency. Incorporating silver sulphide (Ag2S) and reduced graphene oxide (rGO) can improve light absorption and charge carrier mobility, respectively. The study reports successful synthesis, characterisation, and application of Ag;S-rGO nanocomposite (synthesised by chemical reduction method) to enhance the OSCs’ performance. Scanning electron microscopy (SEM) demonstrated the intercalation of rGO sheets within the Ag; S nanoparticles during the chemical reduction process, and that Ag2S had a nanowire shape. Further, SEM energy dispersive X-ray (SEM EDX) showed purity of Ag2S — rGO by indicating C, Ag, O, and S as the only elements in the nanocomposite. X-ray diffraction (XRD) analysis showed sharp and intense diffraction peaks, conﬁnning the high crystallinity of the Ag2S nanoparticles. Thennal gravimetric analysis (TGA) showed rGO slowed nanocomposite decomposition between 520°C and 850°C. AgzS-rGO nanocomposite exhibited strong absorption of light in the ultraviolet and visible regions, making the nanocomposite suitable for use in OSCs. The Fourier Transform Infrared (FTIR) analysis of the nanocomposite showed strong AgzS-rGO interaction with new C-O-C and OH bands, indicating S1lCC€SSfLll integration of rGO into AggS, hence nanocomposite formation. The nanocomposite increased the light trapping of the P3HT: PCBM photoactive layer material within the visible region, improving the efﬁciency of OSCs in light harvesting. For the hole transport layers, however, the higher rGO content slightly reduced the light transmittance due to strong absorbance and plasmonic effects due to Ag2S nanoparticles. All the OSCs with modiﬁed active and hole transport layers (HTL) exhibited improved photovoltaic performance. The nanocomposite in the absorbing layer improved charge generation, leading to increased JSC (from 6.9 mAcm'2 to 17 mAcm'2) and a subsequent enhancement in PCE from 1.5% to 3.4% (a 127% increase). The nanocomposite improved charge collection at the interface, leading to an enhanced PCE by 53% (from 1.5% to 2.3%). The application of Ag2S-rGO nanocomposite considerably improved the performance of the OSCs after application in the HTL and the photoactive layers. Therefore, the study supports the development of sustainable energy solutions.
Analysis of selected toxic metals and polycyclic aromatic hydrocarbons in the Molo river water basin, Kenya
(Egerton University, 2025) Kipkoech, Nathan Kipsang
Water quality is affected by the concentration of heavy metals, cations, anions, microbes, and organic compounds, which when present outside concentrations recommended by guideline values provided by regulatory bodies like world health organization (WHO) and European commission (EC), the water is deemed polluted. These pollutants in water bodies are associated with several health impacts on humans and aquatic organisms, such as effects on reproductive health, respiratory system, cardiovascular system and cancers. Using simple random sampling technique based on altitude and excluding the biological parameters and pays attention to the physical and chemical parameters by determining the concentration of some selected anions, cations, heavy metals, and polycyclic aromatic hydrocarbons (PAHs) in the Molo River water basin in Nakuru County. The water basin serves the people of Nakuru and Baringo Counties residing along Molo river water basin. The Nakuru — Eldoret highway passes through the basin with several vehicle accidents reported around Salgaa and the Sachangwan areas along the highway which has led to monumental oil spills, considered precursors for oleﬁns and polycyclic aromatic hydrocarbons (PAHs) in the water basin. Agricultural activities including thriving ﬂower farms, weathering and timber treatment in the basin are exposing the basin to pollution impacts resulting from organic contaminants and heavy metals. PAHs were extracted and analysed using Gas chromatograph (GC-MS), heavy metals analysed using atomic absorption (AAS), whereas sediment morphology was determined using a scanning electron microscope (SEM). The data generated for physical and heavy metals were used to calculate WQI and WPI which gave a single dimensionless numbers for overall water quality and pollution status. The average WQI obtained was 57.47 indicating that the water is slightly polluted. Also the average WPI obtained was 0.77 indicating that the water from the water basin is not of good quality. Sediment morphology and composition showed the presence of heavy metal pollutants of concern which include lead, manganese and copper. With respect to PAHs, cumulative unsubstituted PAHs Z13 = 2l6.5li0.5l ppm, Substituted PAHs Z21 = l38.34i0.88 ppm, Hetero- atomic Z14 = 23.86i0.35 ppm, and a total PAH load of 378.7li 1.08 ppm. The detected PAHs had calculated total BaP-TEQ of 5. l4 ppm. These PAHs reported included six (6) PAHs listed in the 16 priority pollutants which include acenaphthene, ﬂuorine, ﬂuoranthene, pyrene, chrysene and bezo[a]pyrene. This indicates the need for formulating policies to mitigate contamination in the basin frequent monitoring to provide timely status of contamination.
Fabrication and evaluation of germanium doped cesium tin triiodide perovskite solar cells
(Egerton University, 2025) Kerubo, Mogusu Marion
In the ever-evolving landscape of renewable energy technologies, perovskite solar cells (PSCs) have emerged as an alternative for efﬁcient and affordable photovoltaics (PVs). The quest for sustainable energy sources, coupled with the need to eliminate toxic lead content has called for research in inorganic, cost effective and stable lead-free PSCs. In this work, tin (IV) oxide (S1102) electron transport layer (ETL) and gennanium doped cesium tin triiodide (CsSnI3-Ge) perovskite layer, incorporated with a 5mole% Ge concentration were deposited via thermal evaporation and spin coating methods respectively. In the deposition of SnO; ﬁlms, the thickness was varied, and CsSnI3-Ge ﬁlms were deposited under different spin coating speeds. Optical measurements were done using the ultraviolet visible (UV-Vis) spectrophotometer while structural and morphological measurements for the perovskite layers were performed using an X-ray diffraction (XRD) and scanning electron microscope (SEM) machines respectively. Our ﬁndings show that optical properties for the 30 nm thickness ETL displayed a higher transmittance of approximately 80%, and the band gap values ranged from 3.02 eV to 3.34 eV. The CsSnI3-Ge layer deposited at a spin coating speed of 4000 rpm displayed the highest absorbance of approximately 0.77 a.u attaining a band gap value in the range of 2.85 eV to 3.35 eV which was higher than the ideal value of ~l.5 eV. Structural analysis on CsSnI3-Ge ﬁlms displayed a consistent orthorhombic structure across all samples. The crystallite sizes were nearly identical, as was seen in SEM images. Generally, the perovskite ﬁlm synthesized by spin coating speed of 4000 revolutions per minute (rpm) displayed higher absorbance, higher crystallinity and a relatively uniform ﬁlm morphology making it the optimal layer for fabrication. Three perovskite structures of ﬂuorine doped tin (IV) oxide (FTO)/SnOz/CsSnI3-Ge/copper (I) oxide (Cu2O)/graphite were fabricated and their current density-voltage (J -V) characteristics investigated using a solar cell simulator. From the results, the best performing cell attained a power conversion efﬁciency (PCE) of 2.458% with an open circuit voltage (Voc) of 0.7056 V, a short circuit current density (J Sc) of 8.868 mA.cm‘ 2 and a ﬁll factor (FF) of 39.27%. This output was less than expected but agrees with that of several Sn based PSCs. An optimal annealing temperature has been recommended for the SD02 ETL for band gap control as well as an all-vacuum environment for the synthesis of Sn based perovskites. Altemative synthesis routes for Ge doping should also be explored and interface/surface passivation strategies should be considered for an improved V09. Additionally, hall effect measurement is recommended to determine the charge carrier concentration. This study will help contribute to advancements in renewable energy technologies, research and promotion of sustainable energy solutions
Optimized optoelectronic properties of electron transport materials for dye-sensitized solar cell
(Egerton University, 2025) Kipchirchir Benjamin Korir
The past decade has witnessed signiﬁcant progress in dye-sensitized solar cells (DSSCs) due to attractive power conversion efﬁciencies (PCEs), low toxicity, roll-to-roll compatibility, and versatility. As a result, signiﬁcant strides have been made in developing high-perfonnance DSSCs for the Internet of Things (IoT), highly integrated microelectronics, light-emitting diodes, and portable power supplies, among other emerging applications. Concurrently, fundamental studies have been conducted to elucidate the underlying electronic, chemical, and physical properties of isolated components of DSSCs from both theoretical and experimental perspectives. In this roadmap, this study optimized electron transport materials using density functional theory (DFT) formalism and numerical simulation methods to investigate the optoelectronic and photovoltaic characteristics of simulated solar cell models. One-dimensional solar cell capacitance simulator (SCAPS-1D) and Gaussian 09w SCAPS-1D program were used to study the solar cell conﬁguration FTO/ZnOS/N 719 dye/CuSCN/Au, while Gaussian 09w was used to analyze ground state properties, optimized geometries, and bandgap energies. FTO/ZnOS/N719 dye/CuSCN/Au achieves an outstanding performance of power conversion efﬁciency (PCE) of 10.87%, short circuit current (J56) of 20.32897 mA/cmz, ﬁll factor (FF) of 68.56% and open circuit voltage (V05) of 0.7800 V. For the HTL-free conﬁguration, the architecture FTO/ZnOS/N719 dye/Au yielded an optimal power conversion efﬁciency (PCE) of 11.54%, 18.50 mAcm'2 as the short circuit current (J50), 62.71% as the ﬁll factor (FF), and an open-circuit voltage (Vac) of 0.99 V, while FTO/TiO2/N719 dye/Au gave an optimal photovoltaic perfonnance of 10.22% as the PCE, a J50 of 16.50 mAcm‘2, and 63.58% as the FF. The computational studies of reduced density gradient (RDG) and molecular electrostatic potential (MEP) agree with earlier studies in statistical physics, which suggest that the N719 dye chemically bonds with photoelectrodes via the two carboxylic groups in a bidentate bridging conﬁguration. This theoretical investigation demonstrates that SnO2 and ZnOS are altemative photoelectrodes to conventional T102 in harnessing visible light. Nonetheless, ZnOS stands out as a top ETL contender owing to its high J50 and PCE, which enhance its light-harvesting capabilities.
Studies of selected heavy metals removal from nakuru industrial wastewater using sugarcane bagasse and valorised bagasse
(Egerton University, 2025) Lang’at, Ezekiel Kipkorir
Adsorption of heavy metals is a novel technology for treatment of wastewaters containing different types of heavy metals. This study aimed at using sugarcane bagasse (NSCB) and valorised bagasse (VSCB) adsorbents made out of sugarcane bagasse, a viable and low cost agricultural waste material from Nzoia sugar factory in Westem Kenya, to investigate kinetic and thennodynamic properties for the removal of selected heavy metals (cadmium(II), copper(II), chromium(III), nickel(II) and lead(II)) from industrial wastewater at controlled pH, using Atomic Absorption Spectrophotometer (AAS). Sugarcane bagasse (NSCB) was divided into smaller particle sizes and air-dried at room temperature, dried in a drying oven at 70 °C for 24 h; while Valorised sugarcane bagasse (VSCB) was prepared by slowly heating bagasse at 300 °C for 3 hours. NSCB and VSCB were sieved through standardized sieves of 150-595um. Batch experiments were done to get the optimum conditions of pH, adsorbent dosage, particle size, contact time, concentration and temperature. Eleven (l 1) industrial Wastewater samples were collected randomly from three major locations (A, B, and C), lying between 0° l0’ 0” S and 36°10’ 00” E within Nakuru City in Nakuru County, Kenya. The levels of heavy metals in the untreated wastewater ranged respectively from: 0.02 — 2.02 ppm for lead, 0.02-0.8lppm for copper, 0.02-0.10 ppm for cadmium, 0.024-0.670 ppm for nickel and 0.004-9.94 ppm for chromium. The levels of lead, copper, cadmium and chromium in some of the Wastewater samples were above the limits set by the Kenya Bureau of Standardisation (KEBs). The study showed that the adsorption efﬁciency of NSCB and VSCB powder was higher in aqueous solution than in Wastewater. The removal kinetics of the metal ions ﬁtted well with the pseudo-second-order model. For NSCB, the adsorption isotherm models of Pb2+ and Ni“ showed better fitting for Freundlich isotherm while Cd”, Cu2+ and Cr“ showed better ﬁt on the Langmuir isothenn model. While Pb”, Ni2+, Cd“, and Cu2+ had a better ﬁt for the Freundlich isotherm as Cr“ has a better ﬁt with the Langmuir isotherm model on VSCB. The negative free energy change (AG) values revealed spontaneous adsorption process of the metal ions onto NSCB and VSCB, respectively. The enthalpy change (AH) and entropy change (AS) ranged from 28.34 - 74.84 k]mol'1 and lll.70-344.23 Jmol'lK’1 for NSCB and VSCB further reﬂecting higher afﬁnity ofthe metal ions onto NSCB and VSCB. This study addresses sustainable developmental goal 6 (SDG 6) which seeks to improve water quality by reducing pollution and proportions of heavy metals in untreated Wastewater using NSCB and VSCB adsorbents.
Role of cytokines in varying Trypanosoma brucei rhodesiense infection outcomes in vervet monkeys
(Egerton University, 2025) Jebet, Clarah
The clinical manifestations of Rhodesian human African trypanosomiasis (rHAT), which is caused by T. b. rhodesiense, range from acute illness to chronic illness. The basis of this is poorly understood but is suggested to involve host and pathogen factors, and their interaction. Among other factors, host immune factors, including cytokines, play a role which has begun to unravel, and has been shown to vary depending on the host, pathogen species and strain, and mode of infection. These factors have also been suggested to be potential diagnostic biomarkers. With clinical diagnosis important in HAT, understanding the underlying basis of varying infection outcomes is important. In this study, the vervet monkey (Chlorocebus aethiops), a non-human primate (NHP) model of HAT, was employed to investigate the involvement of cytokines in the manifestation of different clinical outcomes of rHAT. The work utilised pathological data along with cryopreserved, archived S€l'l1IIl and cerebrospinal ﬂuid (CSF) samples obtained from previously infected animals. Two groups of vervet monkeys were infected with strains KETRI 3801 and KETRI 3928 to represent acute and chronic disease forms, respectively, alongside an uninfected control group. Three animals per group (n=3) for plasma analysis and two animals per group(n=2) for CSF analysis were selected due to limited resources available. Quantities of immune modulators, namely INF-y, TGF-[3, TNF-(X, IL-113, IL-6, IL-10, IL-12, IL-13 and a brain damage biomarker protein, S100B were determined, and pathological data, including survival time, parasitaemia, packed cell volume (PCV), temperature, weight and food intake, were analysed. The levels of individual cytokines showed variations in the course of infection. Levels of IL-12, IL-6 and IL-l[5 cytokines were signiﬁcantly increased (p<0.05) from the early stage through to the onset of late-stage disease. Additionally, cerebrospinal ﬂuid (CSF) parasite counts and White blood cell (WBC) levels were higher in KETRI 3801 infections compared to KETRI 3928. IL-12, IL-6 and IL-1B cytokines were particularly higher in acute infection, possibly contributing to the severity of the disease in KETRI 3801 infections, while the interaction between IL-113, IL-6 and IL-10 played a typical pro- and counter-inﬂammatory response during infection progression. Fluctuations in parasitaemia were observed in infected animals, with the KETRI 3801 cohort exhibiting a higher parasitaemia (peak antilog 8.7) than KETRI 3928 (peak antilog 7.8). In addition, infected animals had higher febrile temperature, lower body weight and PCV, which these much pronounced in acute as compared to chronic infections. Monkeys infected with KETRI 3801 and KETRI 3928 had a mean survival time of 28 and 95 days, respectively. The ﬁndings suggest strain-directed and host-dependent immunomodulation as the basis of the different infection outcomes. Also, cytokines are key regulators of disease progression and severity in the NHP model of HAT, and they are essential for understanding the differences in infection outcomes
Synthesis and characterization of FASnI2Br and ZnO:S for fabrication of enhanced-efficiency perovskite solar cells
(Egerton University, 2025) Odhiambo, Cephas Rohn
Clean and renewable energy sources have experienced signiﬁcant demand in recent years due to their necessity for sustainable industrial development. This requirement is also emphasized by the United Nations‘ Sustainable Development Goal 7, "Affordable and Clean Energy." The advent of perovskite solar cells has generated considerable interest in the energy sector, offering hope for advancements in solar technology. Perovskite solar cells are known for their high efﬁciency and ability to convert a wide range of light wavelengths into electricity. Additionally, these solar cells exhibit excellent charge carrier mobility, light absorption and have a high tolerance for structural defects. However, perovskite solar cells face challenges related to toxicity and instability. This research addressed these issues by investigating lead free FASnl2Br. Furthermore, incorporating bromine into FASnl3 and sulphur into ZnO was aimed at enhancing the stability solar cells fabricated with these materials. This approach improved thermal stability, resulting in a well-ordered, compact crystal lattice and reducing the propensity for phase transitions or degradation at higher temperatures. It also enhanced moisture stability through defect passivation. In this study, FASnIgBr and ZnO:S suitable for perovskite device applications was synthesized by spin coating using solution-based technique. Structural and optoelectronic characterization was performed using X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The ZnO:S was observed to show Wurtzite hexagonal structure that agrees with theoretical information. Finally, perovskite solar cells were fabricated on indium-doped tin oxide glass substrates using a spin coater. Doping enhanced the transmission through ZnO:S making it best suited as an electron transport layer (ETL) material. For FASnI;Br, the XRD structure exhibited peaks of a perovskite material. The doping increased optical absorption of FASnl3 making it best suited for perovskite material. A power conversion efficiency (PCE) of 16.5%, Jsc of21.3 mAcm'2 and Voc of 1.15 V were obtained using ZnO:S ETL tested with FAPbI3. The solar cell fabricated with FASnIgBr exhibited moderate performance and favourable electrical properties; PCE of 3.57%, Voc of 0.569 V and J sc of 0.568 mAcm'Z. It was also concluded that ZnO: 4%S performed better than ZnO: 8%S doping concentrations. This research significantly contributes to the field by developing non-toxic, stable materials for perovskite solar cells. The enhanced performance can still be achieved by studying interfacial layer materials as well as passivation materials. This will in future, revolutionize photovoltaic technology, paving the way for more efﬁcient and durable solar energy solutions.
Purification, Bioactivity and Structure Elucidation of Mosquito Larvicidal Compunds from Mycelium of BAsidiomycete JO5444
(Egerton University, 2009-03) Njogu, E.M.
As malaria burden persists in most parts of the developing world, the concept of implementation of new strategies to control the disease continue to gain support. ln Kenya, mosquito population has increased to unprecedented levels as the insects are now a common sight in places they were previously not known to habit. Mosquitoes species belonging to genera Anopheles, Culex, and Aedes are the principal vectors of etiologic agents of various diseases like malaria. filariasis, Japan encephalitis (JE), dengue fever, dengue hemorrhagic fever (DHF) and yellow fever to mention just but a few. It is known that elimination of the vector is one of the most effective ways of controlling disease transmission. This takes the approach of using adulticides and larvicides. Whereas the former is well established, it has limitations like the challenges of targeting mobile adult mosquitoes and resistance of mosquitoes to insecticides. Larval control has long been an option for disease control but it has been greatly under developed and underutilized approach especially in tropical Africa where it may be of much utility than is generally appreciated. Killing mosquito larvae before they emerge as adults can reduce or eliminate the need for ground or aerial application of pCnli\.i\.i¢> l.u kill mosquitoes. During the search for new. effective and environmentally bcnignnatural larvicidal compounds. larvicidal activity of nine enriched fractions and one pure compound from mycelium of basidiomycetes serialized JO5444 were investigated. Bioactivity-guided fractionation and puriﬁcation afforded one pure novel compound identiﬁed as (oxiran-2-yl)methylpentanoate by its spectral data. The LC50 and LCQQ at 24 hours of the pure compound against larvae of Ae aegypti in their late third and early fourth instars were studied and found to be l.50ppm and l.90ppm respectively. The complete structure of the purified compound was obtained from both lD and 2D NMR experiments, and analysis of the spectra obtained allowed complete 1H and BC NMR assignments. The ‘H NMR and BC NMR data for the puriﬁed compound have been provided. Fungal secondary metabolites are therefore hereby reported and proposed as a complimentary tool for control of mosquitoes and hence reduce transmission of diseases that they vector. \ vi
Purification and Characterization of Trypanolysin from the Midgut of Desert Locust (Schistocerca gregaria), A Non-Vector of Trypanosomes
(Egerton University, 2008-09) Gitau, John Mwaura
Prospecting for Antibacterial Compounds from A Basidiomycete JO5191
(Egerton University, 2007-07) Mutambi, Emily Mbayisi
The need for new antibacterial compounds with different modes of action to manage drug-resistant bacterial strains is urgent. The molecular basis of most antimicrobial agents is now fairly well known and thus it is now possible to develop new compounds with improved antimicrobial properties. lliougli there are several drug targets that have been idcntiticd and upon which most antil>actc|'ial agents act. there is still great need and potential to prospect from novel sources for new drug candidates. liasidioinycctes have proved to be cwellcnt producers of secondary metabolites \\‘llll vast activities. Picliniinaiy scicemiig of nude extracts from a basidiomyccte .IO5l9l, revealed strong antibacterial activity against two Urani-negative bacteria: /;'.\'1'/11'1"/1'/rm ¢‘n// and .S'rlln/um’/lu !4i'/r/Iinzu/"Imn. lhls resealcli piojettt involved the puriﬁcation of the compounds using column chromatography and semi preparative lll’LC followed by structure elucidation of the compounds responsible for the observed antibacterial activity. The fungus was cultivated in 25 replicates of I litre~scale in nutrient liquid media for 22 days and crude extracts prepared from both the myccliuin and the culture ﬁltrate immediately allcr stopping growth. The crude extracts were screened for anti- bacterial activity and the compounds puriﬁed by bioassay-guided fractionation on silica gel and reverse phase high-pressure liquid chromatography. The chemical structures of the puriﬁed compound(s) were detennined using spectroscopic techniques: infrared (IR), nuclear magnetic resonance (NMR) in conjunction Willi MS and CD and found to be flavanones. The antibacterial activities were detennined by the calculation of minimum inhibitory concentrations (MIC), which were found to be in the range 3ig/ml - l2tg/ml. agreeing considerably well with those from the literature. -
Polymorphism of Attachin D Gene in Glossina pallidipes Tsetse Fly Populations of Nguruman and Busia-Teso, Kenya
(Egerton University, 2011-03) Mayoke, Abraham
Tsetse ﬂies (Glassina spp) that spread African trypanosomes express Attacin, an immune system protein, during trypanosome infection. The actual mechanism of protection by Attacin proteins in trypanosome-infected Glossina pallidipes is unknown. The objectives for this study was to assess polymorphism of Attacin gene in natural G. pallidzpes populations isolated from Nguruman and Busia-Teso regions of Kenya (regions with different disease transmission levels and genetic diversity of tsetse ﬂies) and correlate polymorphism of the gene to trypanosome infection in G. pallidzpes from the study regions. Biconical traps and suitable attractants were used to lure and capture the G. pallidipes ﬂies. Midguts were dissected from the captured ﬂies and preserved in Trizol reagent. Trypanosome parasitemia in the salivary glands of the ﬂies were determined through standard microscopy. PCR of Attacin D (AttD) gene was conducted on Genomic DNA (extracted from carcasses), and the product sequenced using automated sequencer. Trypanosome infections in the rnidgut tissues were detected by microscopy and their presence conﬁrmed via nested RT-PCR using trypanosome species speciﬁc primers. A total of 586 non-teneral and l5l teneral G. pallidipes were sampled ﬁom Nguruman. In Busia ~ Teso, 17 and 16 non-teneral and teneral G. palidipes were sampled. A homologue of G. m. morsitans Attacin D in G. pallidzpes was successfully identiﬁed ﬁom a region of 484 base pairs. Most polymorphism were mutations, deletions and substitutions but with predominance of mutation in coding sites. Two types of AttD were revealed, a conserved region and several introns in all individual ﬂies’ sequences in position 170 to 180. Attacin D polymorphism in G. pallidzpes from Nguruman and Busia-Teso were predominant downstream from position 199 to position 298. Microcopy examination revealed putative presence of trypanosome in midgut and proboscis of two ﬂies, one each from Nguruman and Busia~Teso, while PCR results revealed putative infections in two and four ﬂies from respective towns. Putative G. pallidipes Attacin D homologous were identiﬁed only in G. m. morsitans and in Aedes aegypti among insect vectors of pathogens in Glossina, Aedes and Rhodnius genera. Interproscan analyses did not reveal any differences in domain architecture among the putative G. pallidipes attacin D sequences. The observed differences in polymorphism of Atttacin D populations in Ngururnan and Busia-Teso may be responsible for the differences in Trypanosomiasis incidences in the two towns. vi
Effects of Varied Magnetic Intensities and Exposure Time on Germination and Growth of Rosecoco Beans (Phaselous vulgaris L.)
(2008-07) Odhiambo, Peter Jared Oloo
Evaluation of the Molluscicidal Effect of the Plants Phytolacca octandra, Phytolacca dodecandra and Balanites aegyptiaca as a Possible Control of
(Egerton university, 2004-04) Mwongela, Boniface Mailu
Genetic Diversity and Relationship of African Sheep-A Y Chromosome Perspective
(Egerton University, 2007-01) Ouna, Benard Aswani
Human Exposure to Lead in Selected Areas in Olkalou and Nairobi, Kenya
(Egerton University, 2007-09) Kimani, G. Njoroge
Isolation and Biochemical Characterization of Transferring From Tsetse Fly, Glossina morsitan centralis
(Egerton university, 2000-04) Orina, Alfred Issac

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