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Item Analysis of Optimuzed Deposition Temperature of ZnO:Al Thin Film on SnSe ZnO:Al P-N Juction Solar Cell(2014) Munji, M. K.; Mbae, J. G.; Musembi, R. J.Solar energy has revolutionized the energy sector in the entire world by offering affordable, abundant and safe power source to the growing demands. The technology in solar cell production has advanced considerably in recent years Solar cell with very high conversion efficiency has been manufactured The efficiencies of solar cells depend on materials used. Deposition method and deposition conditions as they control the optoelectronic properties of the layers. Solar cell samples pre pared with a coat of ZnO)/AI exhibit 100 little degradation and very good solar cell properties (2hao et 01.,20(2). In this research Zinc Oxide will be doped in various percentages alluminurn ranging from 0% to 6% by mass to increase charge carriers. To obtain the optimum doping concentration, the optical and electrical properties of ZnO: AI thin film samples will be analyzed using a solid spec 3700 DUV optical spectrum analyzer and four point probe method respectively. The thin films of optimized Al doped 2nO will be deposited at different deposition temperature ranging from .4OOK-6OOK and tin selenide by reactive evaporation and evaporation technique respectively using Edward 306.Aulo evaporation system. The absorptance transrnittance and reflectance data of opitim ized ZnOA I in the range from 300nlll-2500nfll Will be obtained using UV-VIS NIR spectrophotometer solid state 3700 DUV. The resulting optical measurements will be analyzed using scout software to determine optical constant for thin solar cells The electrical properties of SnxSey and ZnO Al thin films w ill studied using four points probe method using Keithley 400 source meter using Lab View programme SnxSey-ZnO:AI solar cell will be fabricated using the optimized eloping concentration of AI and deposition temperature The performance of the p-n junction such as short circuit current (l sc). open circuit voltage (Voc ). fill factor (FF) and conversion efficiency (11) will be studied using a solar cell simulatorItem Animal feed suppliment from avocado residue and other locally available materials(Kenyatta University, 2009) Ndungu, E.; Gitome, J.; Wanjau, R.; Murungi, J.; Makibia, J.Kenya's population has been on the increase, and more than 15 million people are poor and live in rural Kenya. Of these, 70% are women, who are particularly vulnerable because they do not have equal access to social economic assets thus widening economic gap and rising poverty levels that erode self-esteem and growth in education, health, food security and employment. Most of the poor people are farmers who, apart from growing crops for subsistence, majority of them also keep livestock as a major source of farm income and manure. Proper feeding of the animals is a critical input in productivity as feeding alone accounts for about 40% of production cost or more depending on the sources of feeds and feed ingredients. The available feeds used by farmers including plant residual and napier grass do not meet all the needs of the cattle kept by most farmers which compromises the productivity of the animals leading to low income for the farmer. In order to improve and empower the small holder farmer, there is need to come up with technologies that. can improve their lives. This project aimed at reducing poverty in Evurore division in Mbeere District, by training the locals to prepare animal feed supplement, using locally available avocados. Avocado is one of the most commonly grown farm products in area and is available throughout the year. The fruit is mainly used as a salad fruit and a source of oil for cosmetic products as well as fuel. The seed and the peels of the avocado fruit have not been fully exploited and are normally thrown away with the garbage. This project was designed to come up with an economical way of producing commercial feed supplement using avocado peels and seed as well as other locally available materials in order to curb the problem of low animal feed resources for livestock. The avocado peels and seeds were analyzed for the levels of essential minerals using atomic absorption spectrometry (AAS) and were found to have substantial amounts of the minerals. The produced animal feed supplement will be used as a source of essential macro and micro nutrients which improve health and productivity of the livestock and consequently that of the farmers. The efficacy of the feed developed will be tested by feeding rats and comparing the results with those of commercially available feed concentrates .Item Application of LBIC measurements for characterisation of triple junction solar cells(Elsevier, 2014-04-15) Munji, M. K.; van Dyk, E.E.; Kwarikunda, N.; Vorstera, F.J.; Okullo, W.In this study the Light Beam Induced Current (LBIC) imaging technique was used to characterise InGaP/InGaAs/Ge triple junction solar cells. The study focused on the use of monochromatic and solar light as beam probes to obtain photocurrent response maps from which the presence of any current reducing features on the solar cell were identified. Point illuminated current voltage (I–V) curves were obtained simultaneously while LBIC scanning measurements were being made. Curve fitting using an interval division algorithm based on the single diode model was performed to extract basic point device and performance parameters to give a rough indication of the functioning of the triple junction device. Using red and blue lasers as beam probes, reverse voltage breakdown was observed on the I–V curves which could be attributed to the Ge bottom subcell not being fully activated. The extracted parameters obtained when using monochromatic and solar light beam probes showed a large variation, indicating the dependence of I–V parameters on the spectral content of the beam probe.Item Assessment of the impact of anthropogenic activities on the levels of nitrates and nitrites in Mathare-Gitathuru drainage basin(Kenyatta University, 2009) Nguyo, J.M.; Wanjau, R.N.; Murungi, J.I.; Moko, F.N.Item Banana Distribution and their Seed Systems in Central and Eastern Kenya.(African Crop Science Society, 2011) Mwangi, M.; Kasyoka, M.R.; Kori, N.; Mbaka, J.J.; Gitonga, N.; Tenywa, J.S.; Taulya, G.; Kawube, G.; Kawuki, R.; Namugwanya, M.; Santos, L.Bananas (Musa spp.) serve as food, income resource and animal feed in addition to other environmental benefits. In Kenya, the crop is mainly grown and managed by smallholder farmers. Over the last two decades, banana production has been on the decline. Pests, diseases and limited access to adequate clean planting materials constitute priority problems. This study aimed to determine distribution of bananas varieties, and the availability and sources of planting materials in Central and Eastern provinces of Kenya. Use of naturally regenerated suckers as planting materials exceeded 90% and continuously perpetuated the spread of banana diseases and pests that substantially reduce yields. Prospects for increasing seedlings supply through micropropagation has not been successful due to high cost of tissue cultured seedlings leading to low adoption (<60%). There is a gap between farmers with varying resource capabilities in accessing and using good quality planting materials. This can be resolved by interventions that supply farmers with healthy and affordable banana seedlings. Macropropagation, which is a simple, cost effective method that has been used successfully in other countries has great potential to address issues.Item Characterization of a low concentrator photovoltaics module(Elsevier, 2012-05) Munji, M. K.; Butler, B.A.; van Dyk, E.E.; Okullo, W.; Booysen, P.Low concentration photovoltaic (LCPV) systems have the potential to reduce the cost per kWh of electricity compared to conventional flat-plate photovoltaics (PV) by up to 50%. The cost-savings are realised by replacing expensive PV cells with relatively cheaper optical components to concentrate incident solar irradiance onto a receiver and by tracking the sun along either 1 axis or 2 axes. A LCPV module consists of three interrelated subsystems, viz., the optical, electrical and the thermal subsystems, which must be considered for optimal module design and performance. Successful integration of these subsystems requires the balancing of cost, performance and reliability. In this study LCPV experimental prototype modules were designed, built and evaluated with respect to optimisation of the three subsystems and overall performance. This paper reports on the optical and electrical evaluation of a prototype LCPV module.Item Characterization of SnxSeylSn02: Co PN Junction Deposited by Spray Pyrolysis for Photovoltaic Application(2014) Munji, M. K.; Gitonga, R.G.This research will involve characterization of Sn.Se.: S1102-Co P-N as a solar cell material. SnSe is Ci p- type semiconductor with a direct band gap and high absorption in the visible region spectrum Cobalt doped rin oxide is not only a direct band gap semiconductor but also has a wide band gap and high transmittance Solar cells making use either of the two materials have been fabricated and have achieved good efficiencies. A solar cell using the two materials for a P-N junction is yet to be fabricated In this.research Co-doped Sn02 and SnSe thin films will be deposited on glass substrates using spray pyrolysis technique. The precursor solution will be prepared by dissolving 0.025 M of stannic chloride (SnCl2.5H2O) and different amounts of cobalt nitrate 6-hydrate (Co (NO;)2:6H20) and 1 - 1 dimethyl selenourea (IC3H8N2Se. Different thin films such as Sn02: CO-SIl02: SnSe and Co-SnO]: Snse \will be prepared Optical properties of thin films will be characterized i.e. absorbance spectra, transmittance and reflectance with UV-VIS-NIR spectrophotometer and the band gap of the films will be analysed by use 01scout software. Electrical characterization especially sheet resistivity wiII be measured using the Four point probe method. Thin films with optimum properties will be used at fabricated a P-N junction through double deposition. I-V characteristics of the junction will be done using. Keithley 2400 source meter and a computet. Fill factor (FF), open circuit voltage (Voc), and efficiency of tile junction wil] be obtainedItem Characterization of TiO2 based dye-sensitized Solar Cell prepared by screen printing method(2014) Munji, M. K.; Muendo, Musila Nicholas; Simiyu, J.The dye-sensitized solar cells can provide an economically credible alternative in mitigating the challenges presented by the current convectional photovoltaic devices. Whereas the semiconductor assume both the task of light absorption and charge carrier transport, the two functions are separated. Light is absorbed by a sensitizer which is anchored 10 the surface of a wide band semiconductor. Charge separation takes place at the interface via photo-induced electron injection from the dye into the conduction band of the semiconductor. Carriers are transported in the conduction band of the semiconductor to the charge collector. The use of sensitizers in conjunction with oxide filrns of nano crystalline morphology provides a broad absorption band and permits to harvest a large fraction of sunlight. Nearly quantitative conversion of incident photon into electric current is achieved over a large spectral range extending from the UV to the near IR region. Overall solar energy to electrical energy conversion efficiencies of over 10% has been reported ln addition, there are good prospects to produce these cells at lower cost than conventional solar cells This research aims at contributing to the foregoing research on characterization of low cost Ti02 based dye sensitized solar cells. To achieve that, black berry dye was used as the electron donating species. Blackberry dye was extracted from blackberry fruit and adsorbed onto a nano-porous titania substrate. The nano-porous Ti02 was prepared by sol-gel process and its layer \NaS mounted on a glass substrate by employing screen printing technique. Using DUV3700 spectrophotometer, the Ti02 layer was characterized \0 obtain its optical properties which are transmittance and reflectance. Graphite coated glass 1\3S used as the counter electrode. An UIo• electrolyte solution was used as the redox couple. This solution was made of potassium iodide saturated with iodine. The solar cell parameters were determined 85 3 way of characterizing the solar cell. They included open circuit voltage (Voc), short circuit current (l sc ). fill factor (FF), power at maximum power point (Prnax) of the solar cell and efficiency (11).Item Comparative determination of heavy metals bioaccumulation in bamboo as a phytoremediative process to polluted riverine wetlands(Kenyatta University, 2009) Orina, B.G.; Anyango, S.O.; Wanjau, R.; Murungi, J.Nairobi's unplanned settlements have resulted into open drained domestic and industrial waste into tributaries that join the larger Nairobi River at different stages of its development. Polluted water, to is either directly taken up by planted riverine crops or used through irrigation by the residents. Crop production acts as an important commercial venture for the communities living around the basin. Bioaccumulation of heavy metals such as Zn, Cu, Cd and Pb is evident in these crops causing a health risk to urban consumers. Rehabilitating these wetlands with alternative plant species that reinstate purification, not consumed as food with significant commercial value is therefore urgently needed. Bamboo, due to its growth characteristics and heavy metal accumulation tendencies could serve to uptake heavy metals from polluted aquatic ecosystems and also provide an income generating alternative. four species of bamboo; water bamboo, giant bamboo (Dendrocalamus gingateus), yellow and green bamboo (Bambusa spp) and other plants were grown on potted polluted soils from Motoine riverine, and the accumulated levels of Zn, Cu, Pb and Cd were determined at regular intervals. The results showed that bamboo averagely absorbs 243 mg/kg of Zn, 1.3 mg of Cd, 222 mg/kg of Cu and 36 mg/kg of Pb annually in its initial years. Significant correlations were observed between heavy metal concentrations in the soils after the harvests and the bioaccumulations in the bamboo species (P>0.05, DF12, t-test). Very high correlations between reducing soil heavy metal contents and increasing bamboo heavy metal accumulation (r = -0.788).therefore due to the first growth rate and large biomass index, bamboo forms a good plant for bio filtration of these heavy metals. Bamboo production per year is estimated to be between 30-75 tons/ha per year. The total absorption therefore translates to 6.66-16.65 kg of Zn, 7.29- 18.23 kg of Cu, 1.08-2.7kg of Pb, 39-97.5g of Cd per ha/ year. The study recommends building up of bamboo systems along Motoine River in Kibera as a purifying model and substituting them for commercial edible vegetation in slums around wetlands a viable option.Item Conducting polyamic acid membranes for sensing and site-directed immobilization of proteins(2013) Noah, Naumih M; Omowunmi, A. SadikPoly (amic) acid (PAA) is a functionalized conducting polymer substrate that provides electrochemical detection control of biospecific binding. In this work, we report a biosensor platform based on the PAA for oriented immobilization of biomolecules. The PAA was used to covalently attach biomolecules, resulting in a significant improvement in the detection sensitivity. The biosensor sensing elements comprise a layer of PAA antibody (or antigen) composite self assembled onto gold (Au) electrode via N-hydroxysuccinimide (NHS) and 1 ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) linking. The modified PAA was characterized by Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), and electrochemical techniques. Cyclic voltammetry and impedance spectroscopy experiments conducted on electrodeposited PAA on Au electrode using ferricyanide produced a measurable decrease in the diffusion coefficient compared with the bare electrode, indicating some retardation of electron transfer within the bulk material of the PAA. Thereafter, the modified PAA surface was used to immobilize antibodies and then to detect inducible nitric oxide synthase (a pain biomarker) and mouse immunoglobulin G (IgG) using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and amperometric techniques. ELISA results indicated a significant amplified signal by the modified PAA, whereas the SPR and amperometric biosensors produced significant responses as the concentration of the antigen was increasedItem Current State of Handling, Processing and Quality of Omena (Rastrionebola argentea) in Mfangano and Rusinga Islands, Kenya(2010-12) Jumbe, J; Kibas, P.; Kakongoro, D.; Tumwebaze, R.The livelihood of many Small Scale Fishers in Lake Victoria is based on the Omena Rastrionebola argentea fishery. The processing and trading in Omena in Kenya is dominated by women (80%) who derive their livelihood from the sale of the fish species. Their operations and practice in handling, processing and packaging of the fish is characterized by poor methods and low quality of the fish product due to current wide, traditional practice of drying the fish on the ground or on old fishing nets. This drying method results in fish products which are contaminated by microorganisms and debris. As a result Omena products on the market are of low quality, value and demand. The objective of this research was to determine the current status and practice in the handling, processing and quality of Omena in Suba District and appropriate technological interventions needed to improve the quality and add value to Omena products for a better sale price and to reduce post harvest losses especially during the rainy season. The second objective was to determine gender disparities among the small scale processors and the effects on fish quality and practice. Results indicate that there is no difference in the fish handling and processing practice among the genders. The quality of the Small Scale Fish processors’ fish products was low as fish samples tested were contaminated with debris and had a high bacterial load which included faecal coliforms. The experimental solar tent and rack dried fish samples were of high quality such as low bacterial count and free from faecal coliforms. Solar tent and rack drying technology if adopted by the Small Scale Fish processors can improve the Omena quality, raise the market value and increase income for poverty alleviation.Item Determination of insecticidal activity of Kenyan Bt isolates against the spotted stem borer, chilo partellus(2010) Nyambaka, H. N.; Kimani, G.; Gichuki, S.; Amata, R.; Okomo, M.; Kasina, M.The delta – endotoxin crystals containing insecticidal Cryproteins were isolated from 20 unidentified local Bacillus thuringiensis Berliner (Bt)isolates and a reference isolate Bt aizawai(Bta) using froth floatation and low speed centrifugation at KARI Biotechnology laboratories, NARL. The total protein was quantified using the Bradford assay method and protein yield from the nutrientbroths was estimated at 3.11 mg/ml ±0.938 mg/ml of nutrient broth culture with a purity level of 54.8% ±15.3% of the protein pellet. Leaf – dip bioassay was used to determine the efficacy of the isolates against Chilo Partellus (Swinhoe), a well-established and invasive stem borer in Kenya. Among the isolates, Bt44 and Bt48 had the most potent endotoxin crystals to 1stinstar C. partelluslarvae. In addition, the efficacy of these two isolates was not statistically different (P>0.05) from that of Btabased on LT50 values. The findings show that these two locally available unidentified Bt isolates could be used in management of C. partellusand their characterisation (Cryprotein) could aid in their utilization.Item Ecological management of cereal stem borers in Ethiopia. Integrated Approaches to Higher Maize Productivity in the New Millennium.(2002) Kairu, E. W.; Degaga, E. G.; Overholt, W. A.Three lepidopterous stem borers were reported on maize in Ethiopia. Although complete crop loss is evident in some areas, the average yield loss of maize caused by cereal stem borers in Ethiopia can be estimated between 20 and 50%. A resource-poorfarmers produce over 87% of aize, inexpensive, ecologically sound and effective cereal stem borer control methods are indispensable. To this end, surveys and field experiments were conducted in 1999 and 2000. Surveys were conducted in major maize growingareas of eastern, western, southern and northern thiopia. In the surveys, four stel1 borers, 20 species of parasitoids, 14 species of predators and seven entomopathogens were investigated. These natural enemies gave about 18% re<1:uction of cereal stem borers. Of these natural enemies Cotesia flavipes Cameron (Hymenoptera raconidae) alone gave 13% reduction. Intercropping of maize with beans significantly (PItem Effect of 2, 4-d levels on callus induction of leaf and stem explants of 5 local farmer-preferred sweet potato varieties in Kenya(2010) Machuka, Jesse; Bett, B.; Gichuki, S. T.; Ateka, E.Five local and popular sweet potato (Ipomoea batatas(Lam.) varieties were selected from the major sweet potato growing areas, based on farmer-preferences and desirable characteristics. Both leaf and stem explants were incubated for callus induction with various concentrations of an auxin 2,4 Dichlorophenoxyacetic acid (2,4-D) at 0, 0.5, 1.0, 2.0, and 5.0 mg/L. The highest percentage of callus induction was realized at 2.0 mg/L and 5.0 mg/L 2,4-D in all varieties for both leaf and stem explants. Callus was induced at 3 weeks after incubation of leaf and stem explants in all tested varieties. Stem explants demonstrated a better response to callus induction at all 2,4-D concentrations and in all varieties as compared to leaf explants. All varieties responded differently to callus induction.Item Effect of bacillus thuringiensis (bt)–cotton protein endotoxins (cryiac and cry2ab2) on below ground fauna diversity with reference to entomopathogenic nematodes(2010) Mbugi, J.P.; Njinju, S.M.; Waturu, C.N.This study was conducted with the aim of determining the impact of genetically modified (GM) cotton on the diversity of below ground fauna. The entomopathogenic nematode, Steinernema karii infectivity to the larvae of the wax moth was also used to determine the effect of Bacillus thuringensis-cotton protein endotoxin on below ground biodiversity. Soils from theconfined field trial area had a diverse fauna that included Hemiptera, Hymenoptera, Coleoptera, spiders, wireworms and chaffer grabs. Cotton containing Bt series, non Bt cotton and kenaf were grown in pots under confined conditions and uprooted at flowering stage. Soils from the rhizosphere (soils that adhered to the roots) were tested for the presence of Bt endotoxin using the Quick Stix Comb strip method and were found to be positive for the endotoxin even within non Bt treatments. Those soils werethen inoculated with S.karii and fifth instar larvae of the wax moth, Galleria mellonella in the laboratory. Cadavers of Galleria larvae were recovered from the soils over a period of 10 days and dissected to confirm the cause of mortality. Data was transformed using SQRX + 1, subjected to Analysis Of Variance (ANOVA) and means separated using LSD. Results from the study showed that there were no significant differences between treatments. Galleria larva mortality due to S. karii infections were 64%, 63%, 61% and 50% for HART89M, sterilized soil, Bt cotton and Isoline treatments respectively. A number of false positives were recorded during the experiment for the Bt toxin implying that further refinement of the Quick Stix comb strip technique is required.Item Effect of larval food plants and seasons on the quality of the African wild silkmoth, gonometa postica walker (lepidoptera: lasiocampidae) cocoons(Kenyatta University, 2009) Fening, K. O.; Kioko, E. N.; Raina, S. K.; Mueke, J. M.Wild silkmoth farming offers an economic incentive for forest-adjacent communities to fully participate in forest conservation initiatives. Gonometa postica Walker is known to produce high-quality silk. It is being utilised for commercial wild silk production by the forest-adjacent communities in Mwingi District in Kenya. The developmental time of G. postica larvae and cocoons quality were studied in the Imba and Mumoni woodlands of Mwingi during the long and short rainy seasons of 2006 and 2007. Acacia elatior Brenan, Acacia tortilis (Forssk.) and Acacia nilotica (L.) Del were used as larval host plants. Larvae were reared in semi-captivity by using net sleeves attached to the branches of the host plants. Also, cocoons from the wild population were sampled from the host plants to evaluate their quality. The weight and size of cocoons were used as the determinant of their quality. Larval developmental period and cocoons quality differed according to host plants, seasons and sites, for those reared in semi-captivity. However, cocoons quality from the wild habitat varied with seasons and sites but not with host plants. Larvae reared on A. elatior had the shortest developmental period and highest cocoons quality than those raised on A. tortilis and A. nilotica. Thus, A. elatior is recommended as the most suitable host plant for the semi-captive rearing of G. postica larvae. This will help augment the natural population of the silkmoth and to ensure the sustainable harvesting of the cocoons.Item Effect of Sn Doping on the Electrical Properties of as Prepared and annealed ZnO thin films Prepared by Reactive Evaporation(2014) Munji, M. K.; Nyaga, P. K.; Musembi, R. J.Layers of transparent and conductive Sn-doped Zinc oxide (lnO) have been prepared by reacti. e evaporation on glass substrates. The deposition has been done at various doping levels ranging from J % to 8%. Annealing of samples was done using Rapid Thermal Processing (RTP). In this work, Nabertherrn Programmable Furnace system was used and annealing done at 300°C for one hour. Electrical characterization has been done for both prepared and annealed samples using four point probe configuration at room temperature (25°C) to obtain the sheet resistance. The sheet resistance for tin doped zinc oxide reduced with increase in tin doping to a minimum of J J .920cm at 4% tin doping for as prepared samples and I I .890cl11 for annealed samples.Item Effectieveness of plant oils and essential oil of Ocimum plant species for protection of stored grains against damage by stored product beetles(2015) Obeng-Ofou.D, D.; Jembere, B.; Hassanali, Ahmed; Reichmuth, Ch.Item Efficacy of transgenic kernels harbouring the cry3a gene from bacillus thuringiensis in the control of the larger grain borer and maize weevil(2012) Taracha, Catherine Ongecha; Ombakho, G.; Nan’gayo, F.; Machuka, JesseInsect bioassays were conducted to evaluate the efficacy of maize seed kernels expressing protein of aδ-endotoxin gene of Bacillus thuringiensis tenebrionis Cry3A against economically important coleopteran pests in stored maize. Results from infestation of transgenic seed kernel assays conducted in the laboratory indicate that the kernels had no influence on the survival of the adult larger grain borer Prostephanus truncatus (Horn.) and maize weevil Sitophilus zeamais respectively. There was no adult mortality recorded. There was high population reduction in the T0 transgenic kernels (61%-88%) for both the beetles when compared to the non-transgenic control , in the T1 generation the population reduction was 37%-76% for P. truncatus and 61%-80% for S. zeamais except for inbred A04 which had no effect on population reduction. The lowest kernel damage and weight loss was observed in maize inbredCML 395 for P. truncatus in both T0 and T1 maize generations and in inbred I04 for S.zeamais.Item Evaluation of bacille calmeti'e guerin, montanide incomplete seppic and aluminium hydroxide as adjuvants for leishmania vaccine in balb/ c mice(Kenyatta University, 2009) Muli, J.M.; Macharia, J.C.; Kariuki, T.M.; Gicheru, M. M.
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