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Publication 16S Rrna Gene Amplicon-Based Metagenomic Analysis of Bacterial Communities in the Rhizospheres of Selected Mangrove Species from Mida Creek and Gazi Bay, Kenya(PLOS ONE, 2021-03-23) Muwawa Edith M.; Obieze Chinedu C.; Makonde Huxley M.; Jefwa Joyce M.; Kahindi James H. P.; Khasa Damase P.Prokaryotic communities play key roles in biogeochemical transformation and cycling of nutrients in the productive mangrove ecosystem. In this study, the vertical distribution of rhizosphere bacteria was evaluated by profiling the bacterial diversity and community structure in the rhizospheres of four mangrove species (Sonneratia alba, Rhizophora mucronata, Ceriops tagal and Avicennia marina) from Mida Creek and Gazi Bay, Kenya, using DNA-metabarcoding. Alpha diversity was not significantly different between sites, but, significantly higher in the rhizospheres of S. alba and R. mucronata in Gazi Bay than in Mida Creek. Chemical parameters of the mangrove sediments significantly correlated inversely with alpha diversity metrics. The bacterial community structure was significantly differentiated by geographical location, mangrove species and sampling depth, however, differences in mangrove species and sediment chemical parameters explained more the variation in bacterial community structure. Proteobacteria (mainly Deltaproteobacteria and Gammaproteobacteria) was the dominant phylum while the families Desulfobacteraceae, Pirellulaceae and Syntrophobacteraceae were dominant in both study sites and across all mangrove species. Constrained redundancy analysis indicated that calcium, potassium, magnesium, electrical conductivity, pH, nitrogen, sodium, carbon and salinity contributed significantly to the species–environment relationship. Predicted functional profiling using PICRUSt2 revealed that pathways for sulfur and carbon metabolism were significantly enriched in Gazi Bay than Mida Creek. Overall, the results indicate that bacterial community composition and their potential function are influenced by mangrove species and a fluctuating influx of nutrients in the mangrove ecosystems of Gazi Bay and Mida Creek.
Publication 2013 ISES Solar World Congress Promotion of PV Uptake and Sector Growth in Kenya through Value Added Training in PV Sizing, Installation and Maintenance(Science Direct, 2014) Justus Simiyu; Sebastian M. Waita; Alex Ogacho; Robinson MusembiSub-Saharan Africa, and more specifically the East African region, has the lowest rates of access to electricity in the world. On average, at most 15% of the rural population has access to electricity. Rural households and remote institutions use traditional energy sources such as charcoal, firewood, kerosene and diesel for generator sets, batteries and dry cell batteries. On the other hand, the region is one of the most promising in the world in economic development with growth levels being high and market saturation is a far away future problem. This growth has however been hampered by several factors with lack of energy being one of them. Kenya being one of the countries in the region faces a similar problem with the traditional sources of hydro facing weather related challenges. The situation is more wanting in the rural setting having only achieved electrification rates of between 5 and 10%. The rural being where the majority of low-income earning groups reside is further compounded with large geographical imbalance in electricity demand and supply. The main challenge to adopting pv utilization however, is lack of local capacity to handle the uptake all the way from solar home systems to grid connected and hybrid systems. According to Kenya Renewable Energy Association (KEREA), it is estimated that between 800 and 1000 pv technicians have been in practice since this sector started in Kenya in the late eighties, majority of them having the basic skills but no formal training to provide the service. They however have been offering necessary service to end-users and are hence an important aspect in the pv sector as a whole. Currently the pv (mainly SHS) comprise an over the counter trade system which provides loopholes when it comes to quality of products and installation. To safeguard the quality and safety of installations, formal training has to be incorporated in the system.Publication 454 Pyrosequencing-Based Assessment of Bacterial Diversity and Community Structure in Termite Guts, Mounds and Surrounding Soils(SpringerPlus, 2015) Makonde Huxley M.; Mwirichia Romano; Osiemo Zipporah; Boga Hamadi I.; Klenk Hans-PeterTermites constitute part of diverse and economically important termite fauna in Africa, but information on gut microbiota and their associated soil microbiome is still inadequate. In this study, we assessed and compared the bacterial diversity and community structure between termites’ gut, their mounds and surrounding soil using the 454 pyrosequencing-based analysis of 16S rRNA gene sequences. A wood-feeder termite (Microcerotermes sp.), three fungus-cultivating termites (Macrotermes michaelseni, Odontotermes sp. and Microtermes sp.), their associated mounds and corresponding savannah soil samples were analyzed. The pH of the gut homogenates and soil physico-chemical properties were determined. The results indicated significant difference in bacterial community composition and structure between the gut and corresponding soil samples. Soil samples (Chao1 index ranged from 1359 to 2619) had higher species richness than gut samples (Chao1 index ranged from 461 to 1527). The bacterial composition and community structure in the gut of Macrotermes michaelseni and Odontotermes sp. were almost identical but different from that of Microtermes and Microcerotermes species, which had unique community structures. The most predominant bacterial phyla in the gut were Bacteroidetes (40–58 %), Spirochaetes (10–70 %), Firmicutes (17–27 %) and Fibrobacteres (13 %) while in the soil samples were Acidobacteria (28–45 %), Actinobacteria (20–40 %) and Proteobacteria (18–24 %). Some termite gut-specific bacterial lineages belonging to the genera Dysgonomonas, Parabacteroides, Paludibacter, Tannerella, Alistipes, BCf9-17 termite group and Termite Treponema cluster were observed. The results not only demonstrated a high level of bacterial diversity in the gut and surrounding soil environments, but also presence of distinct bacterial communities that are yet to be cultivated. Therefore, combined efforts using both culture and culture-independent methods are suggested to comprehensively characterize the bacterial species and their specific roles in these environments.Publication A botanical inventory and diversity assessment of Mt. Marsabit forest, a sub-humid montane forest on the arid lands of northern Kenya(Wiley, 2007) Githae, E. W.; Chuah-Petiot, M.; Mworia, J. K.; Odee, D. W.A botanical inventory and diversity of trees, shrubs (≥5 cm diameter at breast height [dbh]), herbs,climbers and lianas was assessed in plots (154) of 20 × 5 m in Mt. Marsabit forest, northern Kenya. Werecorded 52 species of trees and shrubs, twelve species of herbs and six species of climbers and lianas.They belonged to 35 families and 64 genera. Rubiaceae was the richest family with nine species followedby Euphorbiaceae (six), Oleaceae (five), Rutaceae (four), Capparaceae, Labiatae and Leguminosae (threeeach). The rest of the families were represented by one or two species. Rinorea convallarioides (Bak.f.)Eyles ssp. marsabitensis Grey-Wilson (Violaceae), an endemic species, and Drypetes gerrardii Hutch.(Euphorbiaceae), were the two most important species, accounting for more than third of the combinedimportance value. Species diversity indices were 2.735 (Shannon–Wiener), 0.88 (Simpson's) and 0.296(Evenness). There was a strong evidence of disturbance arising from anthropogenic and wildlife foragingactivities. This inventory has affirmed Mt. Marsabit forest as a unique habitat for several endemic, rare,threatened or vulnerable plant species, which should be conserved.Publication A Comparative study of the household food access by farmers in Farmer Field and Life Schools in Gatanga Constituency, Murang’a County, Kenya(African scholarly science communications trust, 2019-06) Kimani, AM; Were, GM; Ndege, SKMany programs have been initiated to assist farmers diversify food production. The Farmer Field and Life Schools (FFLS), an agricultural extension methodology, is an example. Dietary assessment methods are used for nutrition assessments. This study compared household food consumption patterns, by using the Household Dietary Diversity Score (HDDS) of households who participated in the FFLS at baseline and after intervention and Non-FFLS households in the Gatanga Constituency in Murang’a County. The study was based on a United Nations Joint Program implemented from 2009 to 2013. A comparative cross-sectional design was used in this study to compare FFLS at baseline, after intervention and Non-FFLS households. 112 households (56 for cases and 56 for comparative group) participated in this study. The baseline survey with 390 households was in 2009. Data was analysed using the Statistical Package for Social Science (SPSS) version 21. Paired and independent T-Tests were used to determine the difference in the household dietary diversity score between FFLS at baseline and after intervention, and post intervention FFLS and Non-FFLS, respectively. Results show that 42.8% (n=56) of the FFLS households and 28.5% of non-FFLS household respondents were over 50 years of age. 49% of FLS and 11% non FFLS households have incomes ranging from 0-5,000 Ksh. per month, with 41% of FFLS and 32% non FFLS having incomes ranging from Ksh. 5,001- 10,0001 . Mean for Household Dietary Diversity Score (HDDS) at baseline was 8.16 and Non-FFLS was 8.45. Minimum food groups consumed across all groups were cereals, milk and milk products, oils and fats. Comparing FFLS at baseline and post intervention, the percentage of households consuming all food groups increased with exception of fruits and meat. There was a significant difference (p=0.007 against p<0.0005) in the HDDS when FFLS groups post intervention were compared with their baseline. There was no significant difference (p=0.176, against p<0.0005) in the HDDS between FFLS post intervention and non-FFLS households. Compared with the baseline information, FFLS participants who were of low economic status improved their HDDS. Targeting of vulnerable households to participate in such programs has the potential of improving their HDDS compared with the regular HDDS population. Integration of nutrition in agricultural programs with strong extension systems like the - has great potential to improve access and consumption of diversified foods for vulnerable households.Publication A Comparative Study of the Physiochemical and Bacteriological Parameters of Potable Water from Different Sources in Kitui County, Kenya(Journal of Environment and Earth Science, 2022-11-30) T, Wambua; W, Hunja Carol; Josphert, Kimatu; M, Muluvi Geoffrey; U, Kitheka Johnson; Festus, Mutiso; L, Githenya; K, Ndufa James; Kennedy, MutatiDeveloping nations are experiencing an ever-increasing demand for safe water due to climate change and the ever-increasing human population. Various strategies including construction of shallow wells, boreholes and sand dams along the river are done to make water available to various households. However, availability of water sources near are faced with challenges of pollution from a variety of sources. The aim of this study was to determine the levels of selected bacteriological and physico-chemical parameters in three potable water sources namely Kiembeni borehole, Mwitasyano River and Kalundu Dam in Kitui County. The quality of this water was compared to the standards for potable water prescribed by Kenya Bureau of Standards (KEBS). Representative sampling was conducted during the wet season (October 2019) and the dry season (August 2020) in the three sampling sites. The samples were analyzed for physico-chemical parameters: pH, color, turbidity, alkalinity, conductivity, iron, calcium, magnesium, hardness, chloride, fluoride, sulphates, ammonia, total dissolved solids and bacteriological parameters: total and fecal coliform. The analysis was performed at the Kenya Water Institute (KEWI) laboratory using standard procedures. The values obtained for the different water sources in the wet season and dry season were pooled and mean values calculated to determine the overall quality of drinking water. The results indicated that all the water sources had fecal coliform levels unsuitable for drinking water. Most of the values obtained for pH, color, alkalinity, conductivity, calcium, fluoride and sulphates in all sources of water were within the recommended potable water standards by KEBS. However, turbidity, iron and total coliform obtained values for borehole water samples were not within the recommended KEBS standards. The river and dam water samples were within the recommended standards for magnesium, hardness, chloride, ammonia and total dissolved solids. Although results indicate that some of the physico-chemical parameters were in conformance with the recommended standards, the overall bacteriological parameters render the water unsuitable for drinking. Thus, public health intervention programmes should be focused on addressing various sources of water pollution including regular disinfection of water.Publication A demand analysis for Sahiwal breeding animals from the national sahiwal stud (NSS) between 1971 and 2007(2012) Mailu, Stephen; Ndambiri, Hillary; Ritho, C.; Nganga, S. I.; Miyancha, S. O.; Omboto, P.; Gudeta, Sileshi; Kibowon, PhilipThe main objective of this working paper is to trace the development of demand for Sahiwal breeding stock over the period 1971-2007. Such an analysis will enhance our understanding of what has happened on the demand side within the study period. There is only a handful of Sahiwal breeding farms existing in the country, which implies that a particular market structure exists. This paper thus traces the likely evolution of demand and provides some insights on what has happened over the period since 1971. The year 1971 was upon decided as a starting point for the simple pragmatic reason that data for earlier years may not be available. Demand indicators assembled from the records at KARI-Naivasha are used to establish the trends of demand in order to predict the likely trajectory of demand in the near future. Time series analysis of data shows the probability of demand for bulls to have been on a downward trend while for heifers, it has been increasing over time. Also critical in this result is that the probability for heifer crosses is soon catching up with demand for heifers and bulls and given these trends, this may be the animal in greatest demand. Results for average request sizes are mixed with an increase in the size of requests for bulls and heifer crosses until 1990s and a drop in the size of requests since. Some parts of the country also appear to have dropped off, notably Coast Province while others (North Eastern) are rare demand centres. A second part of the analysis, which involves the estimation of models that explain these trends, provides a framework within which the role of important demand shifting parameters such as prices, production systems and distances is determined in greater detailPublication A Hybrid of Fuzzy Logic and Sliding Mode Techniques for Photovoltaic Maximum Power Point Tracking Systems Under Partial Shading(University of Nairobi Research Archive, 2020-11-20) Gathoni, Robinson N.Solar energy harvesting using photovoltaic (PV) modules have been one of the most commonsources of renewable energy for several decades. These modules have been used as a sourceof electricity for households, industries, in stand-alone, and grid-connected solar plants. Themodules consist of semi-conductor solar cells combined in series and parallel. In order to makea solar system, the modules are usually linked in series. The performance of a solar system isaffected by environmental factors like varying radiance and temperatures, shadowing caused byhigh-rise buildings, birds, fog, trees and dust. Such varying environmental conditions affect asolar cell's efficiency. Nevertheless, given all the effort made to mitigate the impact of all theseenvironmental threats, some of the natural occurrences such as varying radiance, clouds, dust,wind-speed and change in temperature, can not be done away with. To improve the e ciencyof the entire solar system, power extraction must be optimized under all weather conditions.Fuzzy logic and sliding mode techniques are e cient, fast and reliable methods of trackingthe maximum power point that have been used in this study. The application of these twoapproaches substantially increases system e ciency for all environmental conditions includingpartial shading instances. The sliding mode technique is a very fast, stable and robust algorithmthat work e ectively under very stable weather condition while the fuzzy logic has beenexploited under partial shading conditions. Both methods rely heavily on a good understandingof the characteristics of PV modules, which are studied using I-V, P-V or P-I curves. In thiswork, three new algorithms have been used to simulate and model the characteristics of a PVmodule.The algorithms are based on a single diode equivalent circuit, which has been chosen dueto the simplicity of simulation and modeling and provides a fast convergence time. The algorithmsare classi ed according to the method of obtaining the best values of the unknownve parameters of the diode model. Ideality factor (A), saturation current (Io), photocurrentiv(Iph), series (Rs) and parallel (Rp) resistances are the ve unknown parameters to be determinedfor characterization of a PV module using a diode model. These parameters have beenextracted using the I-V curve's three critical points at short circuit point (SCP), open circuitpoint (OCP) and maximum power point (MPP). The rst algorithm has been based on thechoice of ideality factor below the optimal ideality factor (Ao), such that 0 A Ao, whereasthe other parameters depends heavily on the choice of A. The second algorithm has been basedon the choice of ideality factor in the neighborhood of Ao and the third algorithm has beenbased on A Ao. The three methods have been utilized to characterize the solar module usingI-V and P-V curves and have output power errors of less than 0.5%.For proof of concept of the three algorithms, PV module with IEC61215 speci cations havecarefully selected from Kyocera- KC130CGT. Additional experimental work has been carriedout at Solinc Kenya Ltd using Solinc 60Wp and 250Wp PV modules, similar to those mountedon the rooftop of the building in Chiromo at School of Physical Sciences.Publication A Regional Assessment of Seasonal-to-decadal Changes in estuarine Socio-ecological Systems in the Western Indian Ocean. Published in Western Indian Ocean Journal of Marine Science(WIO Journal of Marine Science, 2021) Jorge Santos; Johan C. Groeneveld; Fiona MacKay; Cosmas N. MungaAbstract Estuarine socio-ecological systems (SES) in the Western Indian Ocean (WIO) region face mounting pressures from overexploitation, habitat degradation, impacts of climate change and governance inadequacies. A regional assessment of seasonal-to-decadal change in SES of three estuaries (Bons Sinais in Mozambique, Ruvu in Tanzania and Tana in Kenya) was undertaken along 2000 km of tropical coastline (3°-18°S), using a systems-oriented approach and information collected during the Estuarize-WIO project (2016-2019). All three estuaries were open and tidal, but differed along gradients of geomorphology, annual precipitation, exposure to tropical storms, drought, sea level rise, and rural to urban development. Despite physical differences, similar marine species, mangrove assemblages, seasonality in fish-based farming systems and cultivated crops, and fishing methods were apparent across the region. Key differences were related to the scale of anthropogenic disturbance, discerned from land use / land cover (LULC) change analysis, which showed decadal increases in developed-, cultivated- and grasslands, at the expense of wetlands and forests, and seasonal transformation of wetlands to agriculture and grasslands. The three estuaries represented a gradient along urban-production-conservation dimensions, brought about by rural to urban transformation, and by freshwater and sediment diversion for economic development in upstream catchment areas. Household surveys indicated strongly seasonal livelihood strategies, with highest diversity in peri-urban settings, and reliance on different combinations of ecosystem goods and services in coastal and upstream rural settings. Estuarine fisheries ranged from unselective, low trophic-level fisheries using fine-mesh nets at the urbanized and most-disturbed Bons Sinais Estuary, to a more complex organized fishery at the least-disturbed Tana. At Ruvu, fisheries and agriculture production exit the system to distant markets. The systems-oriented approach demonstrated that human-induced processes affected WIO estuaries and dependent livelihoods more deeply than inherent physical differences. A key conclusion is that research, management and governance will benefit from regional cooperation, given the similarities of the systems and the different levels of disturbance.Publication A review of the changes in phytoplankton community structure and ecology in lake naivasha, kenya(Academic Journals, 1970-01-01) Argwings Owino Omondi, Steve Opiyo Balaka, George Ogendi Mokua, James Onchieku Mokua, Steve Oduor OmondiPhytoplankton community structure plays a vital role in freshwater ecosystems. Besides the provision of dissolved oxygen through photosynthesis, they also form an important diet for several fish and zooplankton species. Plankton are also used as biological indicators of water quality. The objective of this paper is to provide a comprehensive review on the changes in phytoplankton community structure and their ecological functional roles. Phytoplankton are the primary producers in Lake Ecosystem. The diversity, distribution, and abundance of phytoplankton are influenced by both abiotic and biotic factors. Lake Naivasha has undergone drastic ecological changes due to the growth in human population, horticultural and floricultural developments and changes in its fisheries. Lake Naivasha is surrounded by horticultural farms that are greatly influencing its ecosystem health and the major fish species in the lake are of introduced species. These anthropogenic activities together with hydrological changes are expected to play a role in the changes in phytoplankton community structure. Previous investigations indicate that there are more than 143 species of phytoplankton and seasonal shift in phytoplankton dominance overtime between Chlorophyta, Bacillariophyta, and Cyanophyta. Due to various limnological, hydrological, and ecological changes being witnessed in the Lake, there is need for the monitoring of phytoplankton community structure. Such information would be useful in the Lake’s management and conservation.Publication A Review of the Current Trends in the Production and Consumption of Bioenergy(Sami Publishing Company, 2021-02-01) Korir, Benjamin K.; Kibet, Joshua; Mosonik, Bornes C.With the current traditional fossil fuels depleting at an alarming rate coupled with environmental degradation because of toxic emissions, there is a mounting desire in search of renewable and sustainable energy resources. In this regard, bioenergy is considered one of the greatest potential to address the global energy demands in order to foster confidence in energy security, economic sustainability, and environmental protection. Global use of biomass to generate electricity and enhanced green energy transport is expected to increase in the near future. Accordingly, the demand for renewable energy is aimed at minimizing energy poverty and mitigation against climate change. Bioenergy despite bioconversion challenges is one of the key solutions to the world’s current energy demands. Model bioenergy plant sources – Croton megalocarpus, palm oil, Jatropha, and soybeans are briefly discussed in this review as major sources of bioenergy. The increased focus on bioenergy has been necessitated by high oil and gas prices, and the desire for sustainable energy resources. Nonetheless, corrupt practices and lack of political goodwill has hampered efforts towards achieving the full utilization of bioenergy. Corruption has been widely cited as a major setback to bioenergy development in a range of global jurisdictions. In order to minimize environmental damage, carbon trade has been projected as a necessary action by developing countries to reduce carbon emissions. Generally, the analysis of the use of fossil fuels across the world shows a strong interrelationship involving energy utilization, degradation of air quality, and environmental health concerns.Publication A Review of the Current Trends in the Production and Consumption of Bioenergy(Sami Publishing Company(SPC), 2021) Korir, Benjamin K.; Kibet, Joshua; Mosonik, Bornes C.With the current traditional fossil fuels depleting at an alarming rate coupled with environmental degradation because of toxic emissions, there is a mounting desire in search of renewable and sustainable energy resources. In this regard, bioenergy is considered one of the greatest potential to address the global energy demands in order to foster confidence in energy security, economic sustainability, and environmental protection. Global use of biomass to generate electricity and enhanced green energy transport is expected to increase in the near future. Accordingly, the demand for renewable energy is aimed at minimizing energy poverty and mitigation against climate change. Bioenergy despite bioconversion challenges is one of the key solutions to the world’s current energy demands. Model bioenergy plant sources – Croton megalocarpus, palm oil, Jatropha, and soybeans are briefly discussed in this review as major sources of bioenergy. The increased focus on bioenergy has been necessitated by high oil and gas prices, and the desire for sustainable energy resources. Nonetheless, corrupt practices and lack of political goodwill has hampered efforts towards achieving the full utilization of bioenergy. Corruption has been widely cited as a major setback to bioenergy development in a range of global jurisdictions. In order to minimize environmental damage, carbon trade has been projected as a necessary action by developing countries to reduce carbon emissions. Generally, the analysis of the use of fossil fuels across the world shows a strong interrelationship involving energy utilization, degradation of air quality, and environmental health concerns.Publication A review of the impacts of invasive aquatic weeds on the bio- diversity of some tropical water bodies with special reference to Lake Victoria (Kenya)(Biodiversity, 0020-12-30) Aloo, Peninah; Ojwang, William; Omondi, Reuben; Njiru, James Murithi; Oyugi, DalmasAquatic weeds may be defined as troublesome or unsightly plants growing in abundance inaquatic situations where they are not wanted. These plants are either adapted to continuoussupplies of water or are at least tolerant to waterlogged soil conditions for substantial periodsof time. The wide range of adaptation to varying amounts of water, and the impossibility ofsharply distinguishing between aquatic and terrestrial environments, makes it difficult toprecisely define an aquatic plant. The menace of water weeds is reaching alarming proportions in many parts of the world, especially in tropical water bodies where they have led toserious ecological and economic losses. Lake Victoria, Kenya, which is the largest freshwaterbody in the tropics, has undergone serious ecological changes including over-exploitationof its fishery resources, degradation of the catchment area, introduction of exotic fish speciesand invasion by the water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae),among others. The presence of the weed in the lake has led to many problems includingblockage of water pumps, reduced fishing activities and increase in water borne diseasessuch as schistosomiasis. Positively, aquatic weeds constitute a free crop of great potentialvalue; they are a highly productive crop that requires no tillage, fertilizer, seed, or cultivation.Moreover, these plants have the potential for exploitation as animal feed, human food, sourceof food to some aquatic organisms, soil additives, fuel production, wastewater treatment,source of raw materials and habitat to many organisms. This paper reviews the effects ofaquatic weeds in aquatic systems with examples from some selected waterbodies and specialreference to Lake Victoria.Publication A review of the impacts of invasive aquatic weeds on the bio- diversity of some tropical water bodies with special reference to Lake Victoria (Kenya)(Biodiversity Journal, 2013-12-30) Aloo, Peninah; Ojwang, William; Omondi, Reuben; Njiru, James Murithi; Oyugi, DalmasAquatic weeds may be defined as troublesome or unsightly plants growing in abundance inaquatic situations where they are not wanted. These plants are either adapted to continuoussupplies of water or are at least tolerant to waterlogged soil conditions for substantial periodsof time. The wide range of adaptation to varying amounts of water, and the impossibility ofsharply distinguishing between aquatic and terrestrial environments, makes it difficult toprecisely define an aquatic plant. The menace of water weeds is reaching alarming proportions in many parts of the world, especially in tropical water bodies where they have led toserious ecological and economic losses. Lake Victoria, Kenya, which is the largest freshwaterbody in the tropics, has undergone serious ecological changes including over-exploitationof its fishery resources, degradation of the catchment area, introduction of exotic fish speciesand invasion by the water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae),among others. The presence of the weed in the lake has led to many problems includingblockage of water pumps, reduced fishing activities and increase in water borne diseasessuch as schistosomiasis. Positively, aquatic weeds constitute a free crop of great potentialvalue; they are a highly productive crop that requires no tillage, fertilizer, seed, or cultivation.Moreover, these plants have the potential for exploitation as animal feed, human food, sourceof food to some aquatic organisms, soil additives, fuel production, wastewater treatment,source of raw materials and habitat to many organisms. This paper reviews the effects ofaquatic weeds in aquatic systems with examples from some selected waterbodies and specialreference to Lake VictoriaPublication A review of thermal energy storage designs, heat storage materials and cooking performance of solar cookers with heat storage(Elsevier, 2017-08-01) Nkhonjera, Lameck; Bello-Ochende, Tunde; John, Geoffrey; King’ondu, Cecil K.This paper discusses the thermal energy storage units, heat storage materials and cooking performance of solar cookers with heat storage surveyed in literature. It is revealed that rectangular and cylindrical containers are widely used in the heat storage devices of the solar cookers. The geometry of the storage units, however, depended on the mode of heat transport into the storage medium and out to the cooking vessel from which, three categories of solar cookers (2-stage, 3-stage, and 4-stage solar cookers) are identified. Furthermore, oils and organic phase change materials dominated in the sensible and latent heat storage units respectively. Additionally, the inclusion of high thermal conductive material into the storage medium was the principal technique used in enhancing effective thermal conductivity. Besides, it is shown that there is no significant difference between the cooking power of cookers equipped with sensible and latent heat storage units. However, the design parameters of the cookers as well as thermal diffusivity of the storage medium greatly influenced the cooking power. The 3-stage cookers outperformed their 2-stage counterparts whereas cookers with cooking vessels integrated to the thermal storage unit outperformed the ones with non-integrated cooking vessels. On the other hand, lower thermal diffusivity of the storage medium increased cooking power in cookers with sensible heat storage but decreased the cooking power in cookers with latent heat storage. Finally, it is shown that the quest for the development of high temperature thermal storage units, and the optimization of the geometry as well as heat transfer characteristics of thermal energy storage units remain the potential areas of research in heat storage for cooking.Publication A Review of Toxic Metals and Hazardous Organics in Wood Treatment Sites and Their Etiological Implications(Journal of Chemical Reviews, 2022-02-07) Miranji, Edwin K.; Kipkemboi, Pius K.; Kibet, Joshua K.Increased natural and human activities over the last century have led to excess levels of inorganic and organic pollutants into the environment and natural ecosystems. This review critically examines heavy metal and organic pollutants' role in wood treatment sites and their etiological consequences. These pollutants are not only recalcitrant but also tenacious to degradation under ordinary conditions. Although some heavy metals are essential to human health, they are toxic at elevated concentrations. Heavy metals feature carcinogenic properties and cause serious health risks to live systems and the environment because of their bio-accumulative, non-degenerative, and refractory characteristics. On the other hand, organic pollutants are readily introduced into the ecosystem from irresponsible use of detergents, volatile organic compounds, paints, pesticides, and wood preservatives. During the wood treatment process, various chemicals are used to enhance durability. Nevertheless, the use of wood preservatives such as chromated copper arsenate (CCA) and pentachlorophenol (PCP) potentially induces pollutants considered detrimental to human health and the ecological environment. Remediation of wood treatment sites using phytomanagement strategies and nanotechnologies has been presented in this review. Therefore, some challenges and recommendations for further research and applications are herein presented.Publication A Simple Low Cost Solar Panel/cell Characterization Experiment for Senior Undergraduate Students(ISES, 2015-11-11) Sebastian Waita*, Justus Simiyu, Alexander N. Kiragu, Vivian Imali and Bernard AdudaA simple low cost solar cell characterization experiment has been developed for senior undergraduate students in the Department of Physics, University of Nairobi. Experiments were conducted with solar panels (also called solar modules/photovoltaic modules) rated 20 W and 40 W peak power on different sunny days on the roof top of Physics Department, University of Nairobi. It was observed that the current- voltage (I-V) curves obtained for all the measurements for each panel were comparable. The fill factor (FF), short circuit current (Isc), open circuit voltage (Voc), current at maximum power point (Im) and voltage at maximum power point (Vm) were within acceptable margins when compared with the manufacturer’s rated values, an indication of the reliability and accuracy of the method. The method eliminates the need for expensive characterization equipment like solar simulators, unaffordable by many developing country institutions. The experiment is recommended for senior undergraduate students with an interest in renewable energy as one way of introducing them to renewable energy. The experiment may also help in arousing the learner’s interest in solar energy.Publication A Soil Tool Kit to Evaluate Soil Properties and Monitor Soil Health Changes in Smallholder Farming Contexts(Elsevier Publishing Company, 2020-10-15) Nyamasoka-Magonziwa Blessing; Vanek Steven J.; Ojiem John O.; Fonte Steven J.Smallholder farmers often face challenges in managing soil fertility due to limited inputs and high spatial variability on their farms. While improved knowledge of soil constraints could help them manage limited resources more effectively, formal soil analyses are typically out of reach due to high costs of testing and transport associated with regional analytical laboratories. To address these challenges, we assembled a tool kit that uses minimal reagents and low-cost equipment to provide in-field quantitative data that are comparable to formal laboratory methods. We validated our tool kit measurements against standard analyses conducted at national laboratories on soils collected from 36 smallholder farms in Kenya and 115 farms in Peru. Additionally, in Kenya, we evaluated two legume treatments, involving the incorporation of residues from: 1) Lablab purpureus (lablab), versus 2) Phaseolus vulgaris (common bean). The tool kit measurements that were considered include important indicators of soil health (such as permanganate oxidizable carbon (POXC), available P, pH, particulate organic matter (POM), and aggregate stability) that can influence crop yields and multiple soil functions. POXC and pH measured with the tool kit from Kenyan soils were highly correlated to those measured by a standard laboratory (R2 = 0.77; R2 = 0.56; respectively). The tool kit and standard laboratory available P were less well correlated, but also showed a highly significant positive relationship (R2 = 0.30). Similar patterns were noted for POXC, pH and available P measured in Peruvian soils (R2 = 0.75; R2 = 0.75; R2 = 0.35; respectively). Importantly, the tool kit and standard lab analyses also displayed similar abilities to predict maize grain yield in Kenya. When used to detect soil impacts of incorporating P. vulgaris versus L. purpureus, only POM differed significantly between the two legume treatments, although L. purpureus was slightly higher for most of the beneficial soil health properties. Our findings suggest that the tool kit methods proposed here have broad applicability to smallholder farms for explaining variability in crop yields, assessing soil contexts, and quantifying management-induced changes in soil health.Publication A Test of the Applicability of the Lake Habitat Survey for Hydromorphological Monitoring of a Tropical Alkaline Lake (Simbi) with a Fisheries Potential(International Journal of Fisheries and Aquatic Studies, 2019-09) Opiyo, Stephen; Getabu, Albert Mochache; Sitoki, Lewis Morara; Shitandi, AnakaloThe Lake Habitat Survey (LHS) is an ecological integrity monitoring tool developed for temperate lakes by an independent team of researchers to support the implementation of the EU Water Framework Directive (WFD). It has been widely applied but more testing is needed in different settings, therefore this study investigated the applicability of the LHS protocol in assessing the habitat quality of a tropical alkaline lake in the face of increasing impacts of anthropogenic pressure and climate change. The LHS metrics of Lake Habitat Quality Assessment (LHQA) and Lake Habitat Modification Score (LHMS) estimated for Lake Simbi collectively suggested that the physical habitat quality of the lake is moderate since its hydromorphology is moderately modified. In conclusion, LHS is effective for monitoring ecological condition of water bodies to inform decision making for conservation and management hence it is suitable for adoption in Kenya and the tropics as one of the standard tools for lake environmental assessments.Publication A virus-induced gene silencing (VIGS) system for functional genomics in the parasitic plant Striga hermonthica(springer, 2014-06-03) Kirigia, Dinah; Runo, Steven; Alakonya, AmosStriga hermonthica is a hemiparasitic weed that infects cereals in Sub Sahara Africa (SSA) resulting in up to 100% grain yield loss. This significant loss in grain yields is a major contributor to food insecurity and poverty in the region. Current strategies to control the parasite are costly, unavailable and remain unpracticed by small-scale farmers, underscoring the need for more economical and sustainable control strategies. Development of resistant germplasm is the most sustainable strategy in the control of S. hermonthica, but is constrained by paucity of resistance genes for introduction into crop germplasm. RNA interference (RNAi) has potential for developing host-derived resistance against S. hermonthica by transformation of host crops with RNAi sequences targeted at critical Striga genes. The application of RNAi in management of S. hermonthica is however constrained by lack of efficient high throughput screening protocols for the candidate genes for silencing, as well as sub optimal delivery of siRNAs into the parasite. In comparison to stable transformation, viral induced gene silencing (VIGS) is a rapid and powerful tool for plant functional genomics and provides an easy and effective strategy in screening for putative candidate genes to target through RNAi. In addition, VIGS allows for a secondary amplification of the RNAi signal increasing the siRNA threshold and facilitates siRNA transport through viral movement proteins. We tested the efficiency of the Tobacco rattle virus (TRV1 and TRV2) VIGS vectors in silencing S. hermonthica phytoene desaturase (PDS) gene through agrodrench and agro-infiltration.