Faculty of Applied Science and Technology

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APPLICATION OF STRUCTURAL BIOINFORMATICS IN AFRICAN SWINE FEVER VIRUS ANTIVIRAL DEVELOPMENT
(Technical University of Kenya, 2022-07) KINYANYI, DICKSON BENNET
African swine fever (ASF) is a fatal hemorrhagic disease of domesticated pigs that is caused by the African swine fever virus (ASFV). This disease poses a threat to food security thus leading to economic losses. Presently, there are no reports of approved available vaccines for ASF. Despite the ASFV sequences having well-conserved promoter motifs, no protein with features able to bind onto the promoter TATA-like elements has been identified, nor an antiviral capable of targeting viral TATA-like elements involved in ASFV transcription. This study aimed at finding a TATA Binding Protein (TBP) and potential minor groove binders (MGBs) that can target conserved promoter motifs in ASFV. The study implemented sequence-based search methods followed by three-dimensional structure modeling. The posterior probability of fold family classification was calculated using TM-fold, and biological function was determined using TM-site, RaptorXBinding Site, Gene Ontology, and TM-align. Subsequently, congocidine congeners, Hoechst 33258, and tris-benzimidazole were selected as potential minor groove binders targeting synthetic DNA constructs containing TATA-like motifs mimicking conserved ASFV promoters. The binding scores and calculated binding energies of docked DNA-ligands complexes were evaluated. The ligand behaviour within the minor grooves was assessed using molecular dynamics (MD) simulation. The results of this study established that the three-dimensional structure of a previously uncharacterized protein pB263R had features similar to a TBP with a TM-score of 0.52, with  95% posterior probability. Additionally, the selected minor groove binders were able to significantly dock on the AT-rich regions of the synthetic DNA constructs containing TATA-like motifs. Further, calculated binding energies revealed that less cytotoxic congocidine congeners and tris-benzimidazole were an improvement of cytotoxic congocidine. The MD simulation and molecular trajectory visualization revealed that the ligands remained embedded in the minor grooves of synthetic DNA constructs during the MD simulation time course. The findings of this study suggest that these ligands may be used as potential antivirals for ASF infection in abrogating ASFV transcription. Critical for control of several ASFV genotypes.
CHARACTERISATION OF CORNISH-SOUTH ULTRA-COMPACT HII-REGIONS SAMPLE USING THE MeerKAT
(2023-11-01) JUMA, CALVINCE
Ultra-compact HII (UC HII) regions are small and dense ionized regions surrounding massive protostars. They are formed when ultra-violet (UV) radiation from massive protostars ionizes the surrounding neutral hydrogen gas. UC HII regions represent the earliest stages of massive star formation; hence it is important to characterise them for a better understanding of the process of massive star formation. However, the mystery of the birth and early life of massive stars is yet to be solved due to some challenges such as their short lifetimes, rarity, and large distances, in constructing a complete evolutionary sequence. In addition, the massive protostars are born in a dusty environment which results in high extinction caused by dust grains making it challenging to observe the embedded protostars and their immediate environment in optical and infrared wavelengths. This limitation can be partially overcome by using radio observations that is less affected by dust extinction. Thus, the advantage of UC HII regions in studying massive star formation is that they emit strong radio continuum radiation due to the presence of free electrons within the ionized gas, enabling their detection even at large distances by radio telescopes. In this study, the radio data from the MeerKAT (1.3GHz) and CORNISH-South (5.5 GHz) surveys were used to conduct a comprehensive characterization of UC HII regions. The MeerKAT survey provided the opportunity to study these embedded objects at lower frequencies, where dust extinction has a minimal effect. With this data, I was able to estimate the radio spectral indices (𝛼) of 79 samples of ultra-compact HII regions. It was found that 91% of these sources had 𝛼 ranging from −0.1 to 2 between 1.3 GHz and 5.5 GHz thus indicating that they are thermal. The remaining 9% of the UC HII regions had 𝛼 less than −0.1 at radio frequency, which may be interpreted as the presence of non-thermal emission. However, this effect is caused by the fact that the MeerKAT observation is more sensitive to extended emission than the CORNISH-South observation. Further characterisation of these sources involved the determination of brightness temperature at 5.5 GHz (ranges from ~100.5K to ~104K), optical depth (range: 0.0 to 0.1), Lyman continuum fluxes ( peaks between 46.5 < (logNi) < 48.6 photons 𝑠 −1 ), emission measure (range from 106 to 108 pc cm-6 ), electron densities (peaks between 103 and 104 electrons cm−3 ), physical size (ranging from 0.01 pc to 0.05 pc) which were all consistent with UC HII regions. Finally, investigation for the presence of protostars in the UC HII regions sample was investigated by computing their radio luminosities and comparing them with those of protostars. It was found that the UC HII regions sample was not contaminated with any massive protostellar objects (MYSO jets and low-mass stars)
Decision quality: the impact of process redesign as an intangible, benefit on information technology investment decisions
(2001) Atieno, Anne Ndede
IT investment decisions often focus on tangible costs and benefits such as technical, strategic, and financial issues. Less tangible benefits such as process redesign integration, bave been largely ignored. Decisions makers who rely solely on these tangible costs and benefits for their assessment of IT investment value without integrating intangible benefit consideration may be making sub-optimal decisions and investments. This study looked at rhe important, yet often overlooked, intangible benefits consideration in the IT investment decision process with particular focus on process redesign as an intangible benefit. Survey questionnaires were sent out to a sample of 949 firms in three industries: healthcare, chemical, and insurance to solicit information from the chief information officer (CIo) on the level at which they integrate process redesign consideration in the IT inr-eshnent decision. Several important findings resulted from this research effort. First, the study irm"nr;fied seven component factors of process redesign and used these factors to measure the M of process redesign integration into the IT investment decision. Second, the study mfirmed, empirically, that there was an association between the consideration of tangible and intangible benefits. Those firms that expend large effort or resources towards tangible benef,rts consideration also spend more effort or resources toward intangible benefits consideration than otherwise. Third, it was empiricaliy determined that certain process redesign benefit factors received greater consideration than others. Fourth, it was determined #mr decision makers considered tangible benefits to be more important than intangible hmefits consideration and expended a greater portion of effort or resources towards the mideration of the former. Finally, this study found that the strategic relevance of IT in an orgAnization was associated with the level of effort or resoulce deployment towards inrangible benefits. Additional areas for further research were also identified.
EFFECT OF DEFECTS AND TEMPERATURE ON THE MECHANICAL AND ELECTRONIC PROPERTIES OF NbC AND NbN: A FIRST-PRINCIPLES STUDY
(2023-11-01) MUCHIRI, PERPETUA
Transition metal carbides and nitrides (TMCNs) are materials that have attracted a lot of attention for both theoretical and experimental studies. This is largely attributed to their excellent physical and electronic properties that makes them ideal candidates for technological and industrial applications. This study focuses on the structural, mechanical and electronic properties of Niobium carbide (NbC) and Niobium Nitride (NbN). Also, owing to their fascinating properties, this study investigated the effects of defects and temperature on the mechanical properties of NbC and NbN from first principles. The study also investigated the effects of defects on the properties of the two materials with concentration ranging between (1.56% − 12.5%) and temperature ranging between 300 K – 1500 K. This is crucial since there exist no perfect materials in nature and the materials are used under extreme conditions such as high temperatures and high pressure. The calculations are performed on the rocksalt (RS), zinc blende (ZB) and wurzite (WZ) structures of the two compounds through the density functional theory formalism using generalized gradient functional approximation for the exchange correlation potential. The obtained results show that the pristine NbC and NbN have high values of elastic constants and mechanical properties in the range of 71 GPa – 815 GPa. The values of the mechanical properties among them bulk moduli, shear moduli, Vicker’s hardness as well as Young’s modulus decrease with increasing defect concentration (1.56 % - 12.5 %) and temperature (300 K - 1500 K). The results obtained show that defect concentration of up to 12.5 % does not compromise the structural properties of the materials and hence, they can still be used in various industrial applications. Further, the temperature range of 300 K – 1500 K considered show that the materials are still mechanically stable and can be suitable candidates in harsh environments of high temperature. Consequently, control of defects and temperature especially during synthesis of these materials is important in evaluating their mechanical response that can drive them to be ideal for super-hard and other related applications
EFFECTIVENESS OF BAOBAB-PEARL MILLET BLEND ON BONE MINERAL DENSITY OF WOMEN AGED 40-65 YEARS IN KITUI COUNTY, KENYA
(Technical University of Kenya, 2024-03-01) Immaculate, Kieti
Osteoporosis is a condition marked by low bone mass and bone tissue loss, which makes a person weak and frail. Osteoporosis, one of the most incapacitating diseases of older people, increases the risk of bone fractures, notably in the hip, spine, and wrist. Women over the age of 45 occupy a third of the hospital beds, on average. 24.3% of Kenyans are estimated to have osteoporosis. The main objective of the study will be to establish the nutrient content of baobab fortified pearl millet flour and assess its impact on bone health among women aged 40-65 years and with osteoporosis at Kitui East sub county, Kitui County. The study will adopt an experimental interventional trial study design. The sample size will be 93 female osteoporotic patients. Bone Mineral Density (BMD) data will be obtained by performing DEXA scan Absorptiometry tests on the women to get their Standard Deviation (SD) levels whereby a SD of 2.5 and above will be considered normal. Baobab dry fruit pulp, pearl millet and baobab fortified pearl millet flour will be analyzed for the nutrient content of selected nutrients of importance to bone health. Calcium, potassium, magnesium, iron, copper, vitamin C and zinc will be analyzed. The interventional trials on women with osteoporosis will make use of two formulations of pearl millet flour supplemented with baobab. Data on the study sample's nutritional status, physical activity level, and health-related characteristics will be gathered using a standardized questionnaire. With the exception of the nutritional status data, which will be entered and analyzed using the Nutri-survey computer package, data from the structured questionnaire will be entered and analyzed using SPSS version 19 software. Bone mineral density, the nutritional value of baobab-fortified pearl millet flour, and respondents' nutritional status will all be interpreted using World Health Organization (WHO) cutoff values. Chi-square (x 2 ) will be used to establish the associations between categorical data on BMD and Body mass Index (BMI). Persons Correlation (r) will be done to establish the association between continuous data. Data will be generated into means, frequencies and percentages and grouped into tables, charts and graphs. A p value of (p< 0.05) will be considered significant. Since many scientific researches has shown that majority of women don’t consume adequate bone health nutrients such as calcium in their diets, there is need of developing a nutrition intervention product which can provide the required bone health nutrients to prevent and manage osteoporosis
EVALUATION OF THE ACCURACY AND REPRODUCIBILITY OF THE PLANNING ISOCENTRE USING AUTOMATIC AND MANUAL COUCH MOVEMENTS
(2023-11-01) MOGIRE, NAOMI
The present study delves into the subject of analyzing the accuracy and reproducibility of the planned isocenter using automatic and manual couch movements, a pivotal issue within the broader context of radiotherapy. This research was driven by the compelling need to ascertain the deviation from the tumor isocenter during the delivery of radiation to cancerous cells and check whether they are within the acceptable clinical tolerance using the AAPM TG-142 protocol. The methodology adopted for this study was hinged on the analysis of the distances between the treatment isocenter from the planned isocenter. The research process involved a detailed collection of shifts using RANDO phantom from three regions of the body (head and neck, thoracic, and pelvic regions) using both automatic and manual couch movements. Sixty shifts; twenty for each region were recorded from where the distances were calculated. The distances offered a more objective evaluation of the accuracy of both couch movements as opposed to the shifts in coordinates. Moreover, the data was analyzed using MS Excel functions that ensured a comprehensive exploration of the topic and an in-depth understanding of the findings. It was found that automatic couch movements were more accurate in reproducing the planned isocenter as compared to manual couch movement techniques. In addition, the present study records a relatively high shift from the planned isocenter for the thoracic region. Only 20% and 17% of the shifts were within the acceptable limits for automatic and manual couch movement respectively compared to the pelvic, head and neck regions whose shifts tolerance was above 70% for both couch movements These results have far-reaching implications for radiation dose delivery as slight deviations from the planned isocenter could potentially lead to an important under dose to the target, which could lead to tumor recurrence and an excessive dosage to healthy tissue, which could have serious repercussions to normal tissues. In conclusion, the findings from this research not only fill a critical gap in the existing literature but also could potentially influence clinical practices and guidelines in the use of couch movements during treatment planning. Future research endeavors could build upon these findings, thereby paving the way for more comprehensive studies in this field.
FEASIBILITY STUDY FOR YELLOW OLEANDER BIODIESEL PRODUCTION USING EGGSHELL-DERIVED NANOCATALYST SYNTHESIZED BY BOTTOM-UP TECHNIQUE
(Technical University of Kenya, 2023-10) MASIME, JEREMIAH ODHEK
The global energy demand is expected to rise by 53% by 2030, depleting crude oil reserves by 2052. This increase in energy demand growth has led to increased CO2 emissions, environmental degradation, and the need for alternative fuels. Researchers are exploring biofuel production using Yellow Oleander seeds, a non-edible plant with high oil content. Heterogeneous base catalysts are preferred for biodiesel production due to their non-toxic, high surface area, reusable, and superior stability, while nanocatalysis increases catalytic activity. The eggshell-derived nanocatalyst was prepared using the bottom-up technique and characterized using TG/DTG/DSC, BET/BJH, XRD, FTIR, XRF, TEM, SEM, and EDX. Response surface methodology was used to optimize biodiesel production from yellow oleander by analyzing physicochemical properties, performance, combustion, and emission characteristics in a 4-stroke engine and life cycle analysis. Yellow oleander oil yielded 64.53 ± 0.53 % under optimal conditions, including 80°C temperature, a petroleum ether solvent, 180 minutes, oilseed particle size, and 1:6 solid-to-solvent ratio, following second-order kinetics. The activation energy, enthalpy of extraction, and entropy were ΔEa = + 33.03 kJ/mol, ΔH = + 38.27 kJ kg-1, and ΔS = + 0.097 kJ/mol.K, respectively. The Gibbs free energy decreases at high temperatures, causing the extraction process to become spontaneous. Using XRD diffractograms, the particle size was determined to be 13.86 ± 0.987 nm. The spherical nature of the nanocatalyst particles was revealed by the SEM and TEM images. From BET analysis, the surface area, average pore diameter, and pore volume were; 5.54 ± 0.48 m2g-1, 18.57 ± 2.16 nm, and ≈ 0.016 ± 0.0 to 0.017 ± 0.0 cm g-1, respectively. The eggshell-derived nanocatalyst, a mesoporous material with a large specific surface area, was found to be beneficial for the transesterification reaction process. The response surface methodology yielded 93.70% of yellow oleander biodiesel under optimal conditions, including a reaction time of 40 minutes, a mild temperature of 60°C, and a 3.68 wt% catalyst loading. The FTIR spectrum of yellow oleander oil and biodiesel showed consistent carboxylate regions. The oil and biodiesel's physical and chemical properties align with ASTM D6751 standards. Engine performance, combustion, and emission behavior were evaluated. B20 was found to be the blend with properties close to that of petrodiesel. The study assessed the production costs and energy balance of a biodiesel plant, revealing an energy balance of 6.94 and an estimated production cost of KES 99.90/L (US$ 0.68)/L). The market price for a biodiesel blend of yellow oleander with 20% biodiesel (B20) was 186.75 KES/L (US$ 1.27 /L). This study synthesized a cost-effective, long-lasting nanocatalyst using waste egg shells to produce yellow oleander biodiesel, which meets ASTM D 6751 specifications and can be used in diesel engines.
HEAD TO HEAD AND TAIL TO TAIL 180◦ DOMAIN WALLS IN PbTiO3/PbTiO3 FERROELECTRIC THIN FILMS: AN AB INITIO STUDY
(2024-02-23) SIFUNA, JAMES SIMIYU
Charged domain walls (DWs) in ferroelectric materials have gained a lot of interest for a decade now. Large conductivity has been reported at the DWs of insulating ferroelectric materials, and it has lots of applications in actuators, sensors and capacitors. In the prior studies, the origination of this conductivity at DWs and the stabilization procedures of the charged domains remain controversial. Plenty of studies have called for the employment of dopants, oxygen vacancies or other external potentials to screen the polarization discontinuity at the DWs. Unfortunately, these kind of computations in literature cannot be used to answer questions about; the intrinsic critical thickness for stabilizing the two-dimensional conducting layers for the screening of the polarization charges, the spatial extension of the hole and electron gases, or the size of the polarization that would result from the induction of such DWs in an ideal slab. This thesis seeks to elucidate the stabilization of 180◦ head to head (HH) and tail to tail (TT) DWs in an ideal slab. Once this stabilization is achieved, queries on the origin of the conductivity seen in at the DWs and the stabilization of such domains will be a thing of the past. The electronic and structural characteristics of charged domain walls (DWs) in PbTiO3 thin films were determined using first-principles simulations as prescribed by the SIESTA method. At first, it was important to implement a strategy that would take into account the Hubbard (U) and spin-orbit coupling in the SIESTA method. This was important so as to accurately describe the physics of the DWs in this study. To benchmark the strategy implemented herein, calculations were performed on tetragonal IrO2. The lattice constants of IrO2 were found to be in a perfect agreement to experimental results. A difference of the order of 1.5% on the lattice constants was seen in comparison to other well known methodologies like VASP and QUANTUM ESPRESSO. The band structures of IrO2 generated by the implementation in here, VASP and QUANTUM ESPRESSO were identical. This gave the author confidence to use the implementation on the complex HH and TT domains. The polarization ( e PZ j ) in the DWs under this study was computed using the effective Born charges. The polarization was then used to obtain the spatial extension of the hole and electron gases at the DWs. To understand better on how much charge was transferred from the free-surfaces to the DWs in order to screen the depolarizing fields, the author plotted the planar average of the free charge (ρfree(z)). This thesis demonstrates how the formation of two-dimensional electron and hole gases at the free surface and at the DWs may stabilize the highly energetic 180◦ head to head (HH) and tail to tail (TT) DWs in free-standing slabs. The walls’ breadth, ≈ 7 unit cells for TT DW and ≈ 6 for HH DW, was found to be significantly more than what is seen when the domains are configured in their neutral state. With a perfect balance between the bound charges (divergence of polarization) and the screening charges, the distribution of the free charge was electrostatically associated with structural distortions. Examining the DWs in an intrinsic manner, the global charge neutrality expected, was observed. Also to note, was that at the interior of the domains, the polarization profile was astonishingly flat and was found to be 57.26 μC/cm2 for HH and 45.72 μC/cm2 for TT structures respectively. From a practical standpoint, this study provides an alternate explanation for the intriguing discovery of extremely high conductivities at the DWs between two insulating polar materials.
THE IMPACT OF SCHISTOSOMA MANSONI ON DISEASE SEVERITY OF SECONDARY INFECTION WITH TRYPANOSOMA BRUCEI RHODESIENSE IN A MOUSE MODEL
(2023-11-01) MITALO, NANCY
Human African Trypanosomiasis (HAT) and Schistosomiasis are neglected parasitic diseases found in the African continent. There’s paucity of data on the outcome during co-infection of S. mansoni and Trypanosoma brucei rhodesiense. This study was conducted to determine how primary infection with Schistosoma mansoni affects HAT diseases progression with a secondary infection with Trypanosoma brucei rhodesiense (T.b.r) in a mouse model. Female BALB-c mice (6-8 weeks old) were randomly divided into four groups of 12 mice each. The different groups were infected with Schistosoma mansoni (100 cercariae) and Trypanosoma brucei rhodesiense (5.0x104 ) separately or together. Twenty-one days’ post infection with T.b.r, mice were sacrificed and samples collected for analysis. The primary infection with S. mansoni significantly enhanced successive infection by T.b.r; consequently, promoting HAT disease severity and curtailing host survival time. T.b.r-induced neurological integrity impairment and breach of the blood brain barrier were markedly pronounced on co-infection with S. mansoni. Co-infection with S. mansoni and T.b.r resulted in microcytic hypochromic anemia characterized by suppression of RBCs, hematocrit, hemoglobin and red cell indices. Moreover, co-infection of the mice with the two parasites resulted in leukocytosis which was accompanied with elevation of basophils, neutrophils, lymphocytes, monocytes, and eosinophils. More importantly, co-infection resulted in significant elevation of alanine amino transferase (ALT), alkaline phosphatase (ALP), aspartate amino transferase (AST), total bilirubin, creatinine, urea and uric acid, markers of liver and kidney damage. Meanwhile, S. mansoni-driven dyslipidemia was significantly enhanced by co-infection of mice with T.b.r. Moreover, co-infection with S. mansoni and T.b.r led to a strong immune response characterized by significant increase in serum IFN-γ and TNF-α. T.b.r infection enhanced S. mansoni-induced depletion of cellular reduced glutathione (GSH) in the brain and liver tissues, indicative of lethal oxidative damage. Similarly, co-infection resulted in significant rise in nitric oxide (NO) and malondialdehyde (MDA) levels. In conclusion, primary infection with S. mansoni exacerbates disease severity of secondary infection with T.b.r in a mouse model that is linked with harmful inflammatory response, oxidative stress and organ injury
ISOLATION AND CHARACTERIZATION OF LACTOBACILLUS AND WEISSELLA STRAINS FROM KIMERE TOWARDS DEVELOPMENT OF A NOVEL PROBIOTIC YOGHURT FOR AFLATOXIN B1 CONTROL
(Technical University of Kenya, 2022-01) NDUTI, NICHOLAS NDARU
In Kenya, maize is an important staple food. Unfortunately, household maize is generally spoilt by fungi whose mycotoxin metabolites have been found to cause adverse effect to animal and human health. The study had four objectives: i) to determine aflatoxin levels in maize and maize flours in three different selected regions in Kenya. ii) To isolate and characterize Lactobacillus and Weissella strains in Kimere and determine their individual strain capacity to sequester aflatoxins. iii) To assess growth of the isolated Lactobacillus and Weissella strains in milk so as to develop a novel yoghurt using the highest Lactobacillus and Weissella aflatoxins binding strains. iv) To determine the capacity to lower aflatoxin B1 (AFB1) metabolite (aflatoxin M1) in urine of children from Eastern Kenya by Lactobacillus and Weissella isolated strains. To achieve the objectives, 75 maize grains and 27 flour samples were collected from three parts of Kenya and analysed for aflatoxins by Enzyme linked immunosorbent assay (ELISA) plus spectrophotometric technique. Basic and advanced molecular microbiology techniques were employed to obtain Lactobacillus and Weissella isolates from Kimere. These included growing the Lactobacillus and Weissella in a selective media followed by Gram staining. To identify the species of the isolated Lactobacillus and Weissella, Polymerase Chain Reaction (PCR) was used to amplify the DNA extracts. DNA blocks were sequenced and identified using the Blast software process. A novel yoghurt was developed using an isolate of Lactobacillus rhamnosus and Weissella, along with starter culture Streptococcus thermophilus. The capacity of the isolates to sequester or bind AFB1, in vitro and in vivo was determined using ELISA. Where applicable High Performance Liquid Chromatography (HPLC) as well as Spectrophotometric techniques were used. Sequestration of AFB1 in vivo was examined indirectly by measuring aflatoxin M1 (AFM1) in urine of school children in Eastern Kenya whose diet was mainly maize or maize-based. Samples of urine from children were analyzed by ELISA, and Liquid chromatography-mass spectrophotometry combination (LC-MS). The results for objective one showed a significant difference between the AFB1 levels in Maize grains (P<0.05) from different regions. Maize samples from Eastern Kenya region had the highest contamination. Maize samples from Nairobi had the lowest concentration at 6.02±0.31145 ppb. There was no significant difference in the total aflatoxins in Maize flour samples from all regions (P>0.05). Moreover there was significant difference in AFB1 concentrations between stores for example from Western and Eastern regions (P<0.05). Total aflatoxin levels in maize flours were slightly above international standard of 5ppb but lower than the Kenyan standard which is 10 ppb. The results for objective two indicated that out of 300 isolates from Kimere that were analysed for capacity to lower the risk of aflatoxin exposure in vivo or in vitro, Weissella cibaria NN20 had highest but statistically insignificant survival in low acidic condition than probiotic Lactobacillus rhamnosus GR-1 and Escherichia coli GR12 (P>0.05). Weissella cibaria NN20 bound 43.7±2.3 % of total available AFB1 in modulated media. Objective three and four had results showing that lactobacillus isolated from Kimere had capacity to ferment milk same as yoghurt and be able to reduce aflatoxin M1 in urine in vivo from 6.3ppb to 2.6ppb. The results confirmed the hypothesis that consumers were at a risk of aflatoxin exposure and that they were indeed consuming the AFB1 contaminated maize and maize products. In conclusion, the findings confirmed relatively high concentrations of Aflatoxins in maize and maize flours despite government efforts to prevent this. These results call for further intervention at table level. The Lactobacillus and Weissella isolates reduced AFB1 both in vitro and in vivo, suggesting that probiotic yoghurt has the potential to prevent aflatoxicosis among consumers of maize and maize based diets.
LIMITATIONS IN THE CONVECTIONAL ISBN - 10 CODE
(2012) Kamaku, Waweru; Mwathi, Cecilia; Kivunge, Bernard
The I nternational S tandard B ook N umber system (ISBN - 10) which was in operation until 2007 uniquely identified every book published internationally but was later replaced with the ISBN - 13 . The code was had the ability to detect and correct single errors, to detect and correct some transposition errors and also d etect multiple errors. This paper discusses some major limitations in the code and shows how error detection and correction capabilities affected the total dictionary on the code. The paper then shows the great need that lead to the development of the ISBN
Magnetohydrodynamic (MHD) Free Convective Flow past an Infinite Vertical Porous Plate with Joule Heating
(2013) Sigey, K. Johana; Okelo, A. Jeconia; Gatheri, K. Francis; Ngesa, O. Joel
This work addresses the problem of Magnetohydrodynamic laminar unsteady flow of an incompressible electrically conducting fluid past an infinite vertical porous plate. It investigates how joule heating affects the velocity and temperature profiles of the fluid flow subjected to transverse magnetic field. The research examines specific equations of MHD flow which are solved numerically by finite difference approximations, using computer programme. The numerical results of this study reveal that an increase in joules heating parameter causes an increase in the velocity and temperature profiles uniformly near the plate but remain constantly distributed away from the plate, implying that the flow field of the MHD free convective flow is influenced substantially by the strength of Joules heating near the wall of the plate and at the mainstream
A MULTI-WAVELENGTH STUDY OF MASSIVE STAR FORMING REGION G188.95+0.89 IN PROBING THE DYNAMICS OF MASSIVE STAR FORMATION
(Technical University of Kenya, 2023-11) MARTIN MULE MUTIE, MARTIN MULE
ABSTRACT Massive stars are born in regions that are opaque to optical observations. This is a challenge in understanding the processes that involve their formation. In order to investigate their formations, a multi-wavelength approach in the infrared (IR) to radio wavelengths was employed to probe the environment around the core, where they are formed. To understand the dynamics of massive star formation, we probed the molecular cloud to check the chemical composition, bipolar outflows and detailed measurements of molecular velocity fields. G188.95+089 is the Massive Star Forming Region (MSFR) that was used in our study. The choice of the star-forming region was due to the fact that it is nearby, emits periodic masers and harbours multiple star-forming cores. While there are many tracers that can be utilized to infer the presence of massive star formation, we relied on Class II methanol masers at 6.7 GHz. In executing the multi-wavelength investigation, radio data from the 26 m Hartebeesthoek Radio Astronomy Observatory (HartRAO) dish was used to analyse the observed spectra of 6.7 GHz methanol masers. Interferometric data from the Atacama Large Millimeter/sub-Millimeter Array (ALMA) were used to check molecular line and continuum emissions of the source. Complementary infrared data from WISE, 2MASS, Hi-GAL, GLIMPSE, IRAS and MSX was used to probe the presence of extended sources surrounding the massive star forming region. Results from radio observations showed that the source had five velocity maser features that exhibited average periodicity of 397.6 days and at least two showed evidence of velocity drifts ranging from −2.38 × 10−5kms−1d−1 to +1.88 × 10−5kms−1d−1. One maser feature at 11.45 Km s−1 exhibited a varying spectra with exponential decay as from year 2003 to present. The spectra of the other maser velocity features have varied significantly since detection in 1991. Using ALMA band 6 at ∼ 1.3 mm and band 7 at ∼ 0.93 mm data, we were able to identify eight continuum cores (MM1-MM8) in the source, with masses ranging from 0.40 to 8.20 solar masses. In the ALMA band 7 observations, G188.95+0.89 MM2 was resolved into two continuum cores separated by 0.1 arcsec. The thermal emission of CH3OH (4(2, 2) - 3 (1, 2)) linked with MM2 has a double peak. In MM2, SiO emission has a bow-shock morphology, but high 12CO evidence for an east-west bipolar outflow is provided by emission to the east and west of MM2. SiO emission shows bipolar outflow centered around MM2 core. Using near- and mid-IR color-color diagrams, young sources were detected in this star-forming region. A total of 36 candidate YSOs, were detected within a 60′′ radius of the G188.95+0.89 source. There is an IR cluster made up of nine of these YSOs just outside the UC HII zone. Only the H and Ks bands of the 2MASS data can reveal nine highly red shifted objects. These sources have redder colors than H − K > 2, indicating that the IR cluster is extremely young. It is unlikely that interstellar absorption alone is responsible for the reddening of the vectors; instead, the presence of a circumstellar disc and envelope must account for at least some of the IR excess. Although further investigation is needed, it appears that the velocity drifts were caused by gas falling into the inner radius of the accretion disk surrounding the protostar G188.95+0.89. The variability of 6.7 GHz methanol masers is a confirmation of on going accretion in the source. Although the presence of accretion disks in the source cannot be confirmed with the existing measurements, the identification of outflows is consistent with their existence. The out-flowing material creates shocks when it encounters the quiescent gas of the envelop. The detection of SiO molecular lines is an effective tool for checking for the existence of shocks. The shock waves pushes the gas into ever denser physical states that allow it to cool and fragment more efficiently. We argue that MM2 has a massive multiple (at least binary) of young star objects, but more VLBI observations are needed to confirm that this is indeed the case.
The nonnegative P 0 -matrix completion problem.
(2003) Choi, Ji Young; Dealba, Luz Maria; Hogben, Leslie; Kivunge, Benard M; Nordstrom, Sandra K; Shedenhelm, Mike
In this paperthe nonnegative P 0 -matrix completion problem is considered. It is shown that a pattern for 4 × 4 matrices that includes all diagonal positions has nonnegative P 0 - completion if and only if its digraph is complete when it has a 4-cycle. It is also shown that any positionally symmetric pattern that includes all diagonal positions and whose graph is an n -cycle has nonnegative P 0 -completion if and only if n =4.
Numerical Simulation of Turbulent Natural Convection in an Enclosure
(1994) Gatheri, Francis Kimani
On the cycle indices of frobenious groups
(2010) Munywoki, Michael; Kamuti, Ireri; Kivunge, Benard
There are several very useful formulas, which give the cycle indices of the binary operation of the sum, product, composition and po wer group of M and H in terms of cycle indices of M and H . One very useful binary operation on groups, which has not been exploited, is the semidirect product. Suppose G = M ⋊ H , a semi direct product; the question is: how can we express the cycle index of G in terms of the cycle indices of M and H ? This work partially answers this question by considering the cycle indices of so me particularly semidirect product groups; namely – Frobenious groups
OUTCOME OF CHRONIC SCHISTOSOMIASIS IN REGULATION OF MALARIA DISEASE SEVERITY AND PATHOLOGICAL EVENTS IN A MOUSE MODEL
(Technical University of Kenya, 2022-05-01) MUGANDA, ANDREW
First, I wish to thank the Almighty God for the strength, good health, and focus for making this journey possible. Special thanks to my supervisors Dr. Edward Okonjo, Dr. James Nyabuga and Prof. Dorcas Yole, for the excellent supervision, commitment and guidance throughout the development of this thesis. I extend my gratitude to my supervisors for helping in conceptualization of the idea and putting it together. Furthermore, for walking with me throughout the research journey. In addition, my supervisors were very committed in ensuring that I overcome my challenges during experimental stages and helping me understand that drawbacks are avenues for learning. I am grateful to the staff at the Department of Applied and Technical Biology and Department of Biochemistry and Biotechnology at TU-K for the assistance during my laboratory sessions and I appreciate them for providing me with the necessary academic support that enabled me to finish my studies. Special thanks to the Muganda’s family, may God bless you abundantly for walking with me and encouraging me to focus on the finish line.
PESTICIDES: OCCUPATIONAL EXPOSURE AND POTENTIAL IMPACTS ON ECOSYSTEM AND HUMAN HEALTH IN MERU COUNTY, KENYA
(Technical University of Kenya, 2021-03) MARETE, GABRIEL MUTHEE
ABSTRACT This study assessed the usage of pesticides and its impacts on ecosystems and human health through occupational exposure in selected farming communities in Imenti North, Imenti South and Buuri Sub-counties in Meru, Kenya, where horticultural crops including French beans, kales and tomatoes are grown intensively for export and local consumption. The study was done through use of questionnaire distributed to farmers, agricultural extension and health care workers in selected farms in the three Sub-counties. In addition, analysis of pesticide residues by GC-MS in samples of farm soil, French beans, kales and tomatoes, from randomly selected sites in the three Sub-counties was done. The survey established that various pesticides in the classes of organochlorines, organophosphates, carbamates, pyrethroids and fungicides, were used in the three Sub-counties, with the most frequently used ones (>60 respondents out of 173) being parathion, diazinon, permethrin, pirimiphos methyl, carbaryl, deltamethrin, dieldrin, methoxychlor, cypermethrin, propoxur and carbofuran. Some of these including dieldrin, parathion and carbofuran were used illegally because they have been banned. Although most farmers had general information on pesticide usage through various social groups and contact with agricultural extension workers, only 32–43 % of the farmers had received training on pesticide handling and use. Most farmers (65%) had knowledge of safe pesticide handling procedures including reading labels on packages and wearing protective clothing; but many farmers (44% in Buuri, 57% in Imenti South and 60% in Imenti North) did not wear the requisite protective clothing when applying pesticides. Agricultural extension workers (52%) and health care workers (59%) were trained in their work and had at least a certificate level qualification from a tertiary institution. Most agricultural extension workers (95%) and health care workers (71%) had experience of dealing with pesticides and knew how to administer 1st AID against pesticide poisoning, respectively. Farmers (26%) reported experiencing health effects after using pesticides, with most effects being felt after using dimethoate, malathion, carbofuran, carbaryl and heptachlor. There was a statistically significant (p < 0.05) association between various factors (availability of protective clothing, hiring of labourers, farm land size, expenditure on pesticides and expenditure on treatment, respectively) on intoxication from pesticide exposure. Analysis of organochlorine pesticide residues in soil, French beans, Kales and tomatoes sampled randomly from the selected sites found widespread contamination of soils with organochlorine pesticide residues, with total (Σall OCs analysed, in μg/Kg dry weight) ranging from 15.78 – 307.70 in Imenti North, 1.25 – 159.88 μg/Kg in Imenti South, and 14.96 – 106.13 μg/Kg in Buuri. However, organochlorine pesticide residues were not detected in any of the vegetables. Other pesticides, including chlorpyrifos, carbendazine, imidacloprid, acetaprimid, metalaxyl, diazinon, azoxystribin, triadimefon, acephate, thiamethoxim and diuron were found in farm soils, French beans, kales and tomatoes, with concentrations (in μg/Kg dry weight) in soil samples ranging from BDL (metalaxyl and azoxystrobin) – 13,030 (carbendazin). In French beans, kales and tomatoes, the concentrations (in μg/Kg wet weight) ranged from BDL – 290, with the highest being imidacloprid in tomatoes. The pesticide residue levels generally were very low and met the Maximum Residue Limits set by European Union and other countries, and posed no concern to human health. Risk assessment of the residues in terms of estimated daily intakes (mg/Kg BW/day) also confirmed no health risk in the population. However, it is recommended that preharvest intervals for the pesticides should be observed in the three Sub-counties to avoid long term exposure to consumers.
PHYLOGENETIC DIVERSITY AND TOXIGENIC POTENTIAL OF FUSARIUM SPECIES IN WHEAT AND LEVELS OF DEOXYNIVALENOL AND FUMONISINS IN MARKET WHEAT PRODUCTS, KENYA
(Technical University of Kenya, 2023-11) OTIENO, PHANICE KHESELI
ABSTRACT In Kenya, wheat is the second most consumed cereal grain after maize and provides nutrition for about 50% of the world's population. However, production of the grain often faces setbacks occasioned by fungal infections and the related chemical contaminants. Unrelenting fungal disease control system, sufficient wheat seed system and observation of food safety measures to curb deficiency and alleviate ill health associated with consumption of mycotoxin contaminated wheat products is essential. This study assessed farmers’ knowledge on fungal wheat diseases and, their practices in choices of wheat cultivars cropped in three ecological regions of Kenya. Prevalence and diversity of Fusarium species in the produce of farmer saved and certified seeds of wheat cultivars was also analyzed. In addition, the genetic ability of the isolated Fusarium spp. to produce mycotoxins was evaluated. Lastly, a survey to investigate occurances and levels of fumonisins and deoxynivalenol (DON) in selected market wheat products sampled in Narok town, Nakuru city and Nairobi, the capital city of Kenya was done. Two hundred and sixty wheat grain samples were collected from 123 farms in Narok, Uasin Gishu and Nakuru Counties between 2016 and 2017. Peptone Pentachloro-nitrobenze Agar was used for isolation of Fusarium spp. from the grains samples, while PDA, CLA and SNA media were used for cultural and morphological characterization. Fusarium species identity and diversity was determined using sequence analysis of the gene encoding translation elongation factor 1-alpha (tef1-alpha). The genetic ability of the Fusarium spp. to produce mycotoxins was determined using Tri13F/Tri13RDON and FUM1F/FUM1R primer pairs. ELISA Kit protocols were used for assessment of mycotoxin levels. ANOVA, the Tukey HSD test and microscopy were used for data analysis. Notably, barely 10% of wheat cultivars released into the Kenyan market were under cultivation in the targeted areas within the study period. In all the three regions, Njoro BWII wheat cultivar was the most preferred and the most frequently (48.8%) sampled wheat cultivar. Top on the list of agroeconomic factors that influenced the selection of wheat cultivars to plant were the weight of wheat grains at harvest and the resilience of wheat cultivars to wheat rust. Other than wheat rust, most farmers had limited knowledge about other fungal diseases while only 1.63% of them cited Fusarium head blight (FHB) as a problematic fungal disease in wheat production. Eight Fusarium spp. (Fusarium poae, F. verticillioides, F. equiseti, F. heterosporum, F. tricinctum, Fusarium sp. F. oxysporum, and F. culmorum) were identified. However, the species diversity in the study regions did not differ significantly. While certified commercial wheat seeds produced 33.75 percent of the recovered Fusarium spp., wheat grains from farmer-saved seeds produced 66.25%. Tri13DON gene was not detected in the isolated putative DON producers while FUM1 gene was detected in 60% of the isolated Fusarium species. Over 76% of the analyzed wheat grain samples had detectable levels of fumonisins. However, the highest level (9.6ppm) did not exceed the permissible levels of between 2000μg/kg and 4000μg/kg in whole grains according to EU guidelines. Over 75% of the sampled market wheat products contained levels of DON and fumonisins that were below the permissible maximum limits of 750μg/kg according to EU guidelines. Wheat flour contained the highest concentration of DON (5.6 μg/kg). The significant research finding is that a minimal percentage of wheat cultivars released into the market had been cultivated in the studied regions. Among other factors, farmers did not prioritize selection of cultivars based on their ecological growth requirements and they notably had minimal knowledge about other serious wheat fungal diseases such as FHB to the extend of referring to all diseases observed on the crop as wheat rust. Fusarium spp. with the ability to produce mycotoxins were prevalent in the wheat cultivars sampled in the three study areas. This calls for intensified integrated control measures of the pathogens across the three regions. Finally, the quantities of DON and fumonisin found in the wheat products from the market samples were within acceptable limits. Hence, this result highlights the safety of the products for human consumption. However, frequent surveys are recommended to ascertain consistency in the levels of the toxins within the recommended measures. More extension services are also needed to educate wheat farmers on all-important qualities of wheat cultivars released in the market. Lastly, enhancement of awareness on the prevalence of other dangerous fungal diseases such as FHB, it’s related health affecting mycotoxins and how farmers can participate in the control of such diseases.
PUTATIVE EFFECTS OF CYANOCOBALAMIN IN THE REGULATION OF INFLAMMATORY RESPONSES, OXIDATIVE STRESS AND PATHOPHYSIOLOGICAL EVENTS DURING SEVERE STAGE OF HUMAN AFRICAN TRYPANOSOMIASIS
(2023-11-01) Oula, James
Human African Trypanosomiasis (HAT) is a neglected tropical disease caused by T. b. rhodesiense and T. b. gambiense, with tsetse fly (Glossina spp) being the known vector. T. b. rhodesiense causes acute form of HAT in Africa. The severe late stage of the disease is characterized by infiltration of the brain through the blood brain barrier (BBB) as well as overwhelming inflammation and oxidative stress. Treatment of HAT is reliant on the stage of the disease and melarsoprol remains the drug of choice for treatment of late-stage HAT despite the fact that it causes post-treatment reactive encephalopathy (PTRE). It therefore implies that, new treatment strategies that control the breach of the BBB as well as inflammatory reactions and oxidative stress may benefit those on treatment. This study utilized cyanocobalamin (vitamin B12), a well characterized anti-inflammatory and anti-oxidant molecule to determine its effects on T. b. rhodesiense-driven deleterious events. Therefore, the objective was to determine the effects of cyanocobalamin in the regulation of immune response during T. b. rhodesiense infection. Mice were randomly assigned into four groups each containing 8 mice; with group one being the control. Group two was infected with 5.0 x 104 KETRI 2537 T.b.rhodesiense; group three was supplemented with 8mg/kg of vitamin B12 for two weeks before infection. For group four, administration of vitamin B12 was started 4 days post infection (dpi). The general health of the mice was assessed using rapid murine coma and behavior scale (RMCBS), while parasiteamia was determined microscopically. At 42 dpi, the mice were sacrificed to obtain blood, tissues and organs for various analyses. The statistical analysis was done by GraphPad Prism software package. One-way ANOVA was used to compare the treatment groups with controls, Tukey’s post-hoc test for internal comparisons and Log-rank (Mantel-Cox) test for survival analysis. The results were given as a mean ±SEM with the level of significance set at P <0.05.The results showed that vitamin B12 enhanced the survival rate of T.b.rhodesiense infected mice independent of parasitemia of antilog 8.7 organism/ml and prevented T.b.rhodesiense-induced disruption of the BBB. Notably, T.b.rhodesiense-induced hematological alteration leading to microcytic hypochromic anemia and leukocytosis was nullified in mice administered with vitamin B12. T.b.rhodesiens-induced dyslipidemia was reversed by vitamin B12. T.b.rhodesiense-induced elevation of the liver alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, urea, uric acid and creatinine for kidney damage markers were attenuated by vitamin B12. Vitamin B12 blocked T.b.rhodesiense-driven rise in pro-inflammatory cytokines (TNF-α and IFN-γ), nitric oxide (NO) and malonaldehyde (MDA). T.b.rhodesiense-induced depletion of glutathione (GSH) levels were attenuated in the presence of vitamin B12 in the brain, spleen and liver tissues; a clear indication of the anti oxidant activity of vitamin B12. The histological analysis of the brain and liver confirmed T.b.rhodesiense-driven damage of these vital organs; which was ameliorated by vitamin B12. In conclusion, treatment with vitamin B12 potentially protects against various pathological events associated with severe late-stage HAT and presents a great opportunity for further scrutiny to develop an adjunct therapy for severe late-stage HAT.

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