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A Retrospective Analysis of Wastewater Confirms Dominant Circulation of SARS-CoV-2 Delta Variant in Nairobi, Kenya, between April 2021 and August 2021

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American Journal of Molecular Biology 2022年第3期12卷 109-121页

作者： Patson Sichamba Fred Wamunyokoli Peter Borus Rosemary Nzunza Opanda Silvanos Samwel Symekher Samoel Ashimosi Khamadi Janet Majanja meshack wadegu Esther Chitechi Benlick Mwangi Evans Komen Stephen Ombija Wallace Dimbuson Bulimo Pan African University Institute for Basic Sciences Technology and Innovation (PAUSTI) Nairobi Kenya Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Kenya Medical Research Institute Centre for Virus Research Nairobi Kenya

Wastewater surveillance has been applied in various parts of the world to monitor the introduction and transmissions of SARS-CoV-2 variants in a population. The knowledge of SARS-CoV-2 variants circulating in a population is critical to COVID-19 management and timing of the application of public health countermeasures. Contrary to the routine clinical surveillance of SARS-CoV-2 where cases from asymptomatic patients are often underreported, wastewater surveillance offers an unbiased tool for monitoring the extent of SARS-CoV-2 transmissions in a community. The present study aimed to characterize SARS-CoV-2 variants that circulated in Nairobi County, Kenya, between April 2021 and August 2021 utilizing wastewater samples. Viral RNA was extracted from wastewater samples, followed by SARS-CoV-2 screening by real-time RT-qPCR before targeted sequencing of the Spike gene. Forty samples were analyzed, of which 50% (n = 20) tested positive for SARS-CoV-2 by real-time RT-qPCR. Of these, 45% (n = 9) were successfully amplified by RT-PCR and sequenced. The majority (78%, 7/9) of the viruses belonged to the Delta (B.1.617.2) lineage of SARS-CoV-2, while a minority (22%) belonged to the Alpha (B.1.1.7) and Alpha-Delta lineages. Phylogenetic analysis of the SARS-COV-2 delta lineage strains revealed scattered clustering of the Kenyan viruses among the global strains included in the analysis, suggesting different introductory routes into the country. On the whole, our results confirm previous clinical findings that SARS-CoV-2 variants belonging to the Alpha (B.1.1.7) and Delta (B.1.617.2) lineages circulated in Nairobi County, Kenya during the study period, with the latter predominating. This is the first study to describe the diversity of SARS-CoV-2 variants circulating in Kenya, through wastewater analysis.

关键词： Wastewater Surveillance SARS-CoV-2 Delta Variants Spike Gene COVID-19 Kenya

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Distinct edaphic habitats are occupied by discrete legume assemblages with unique indicator species in the Cape Peninsula of South Africa

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Journal of Plant Ecology 2018年第4期11卷 632-644页

作者： meshack N.Dludlu Samson B.M.Chimphango Charles H.Stirton A.Muthama Muasya Department of Biological Sciences University of Cape TownPrivate Bag X3Rondebosch 7701Cape TownSouth Africa

Aims the Cape Peninsula is a small area(471 km2)situated on the south-westernmost tip of the Core Cape Subregion(CCR)of South *** the Cape Peninsula,Fabaceae are the third most species-rich plant family(162 species)and they have the second highest number of endemic species after the ***,legumes are not the dominant taxa in the *** tend to show patchy distributions within the landscape and different species assemblages usually occupy particular niches at any given *** present study undertook to establish if edaphic factors influence legume species distribution in the Cape Peninsula and to determine the key indicator species for the different *** Soils from 27 legume sites,spanning all major geological substrates of the Cape Peninsula,were analysed for 31 chemical and physi-cal *** species present at each site were recorded and a presence/absence matrix was *** analysis and discriminant function analysis(DFA)were run to group the sites based on overall similarity in edaphic characteristics and to identify the soil parameters contributing towards discriminating the *** correspondence analysis(CCA)was used to test for a cor-relation between legume species compositions and edaphic *** strength of the association between legume species and site groupings based on edaphic properties was assessed using indicator species *** findings Based on similarity in overall soil characteristics,the sites formed three clusters:one comprising sites of sandstone geology,one with dune sand sites and the third cluster comprising sites of both shale and granite geologies(hereafter referred to as soil types).the DFA confirmed the distinctness of these clusters and the CCA showed a significant correlation between legume species composition and edaphic *** key edaphic parameters were clay content,iron(Fe),potassium(K),sulphur(S)and zinc(Zn).these findings reveal

关键词： Fabaceae Core Cape Subregion Cape Peninsula edaphic factors biogeography

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Effect of Exhaust Gas Recirculation on Performance and Emission Characteristics of a Diesel-Piloted Biogas Engine

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Smart Grid and Renewable Energy 2015年第4期6卷 49-58页

作者： meshack Hawi Robert Kiplimo Hiram Ndiritu Department of Mechanical Engineering JKUAT Nairobi Kenya Department of Marine Engineering JKUAT Nairobi Kenya

In this research, a Direct Injection Compression Ignition (DICI) engine was modified into a dual-fuel engine that used biogas as the primary fuel and diesel as pilot fuel, with the focus on reduction of harmful exhaust emissions while maintaining high thermal efficiency. The effect of exhaust gas recirculation (EGR) on engine performance and emission characteristics was studied. The EGR system was developed and tested with different EGR percentages, i.e. 0%, 10%, 20% and 30%. The effect of EGR on exhaust gas temperature and performance parameters like brake specific fuel consumption, brake power and brake thermal efficiency was studied. The performance and emission characteristics of the modified engine were compared with those of the conventional diesel engine. The results showed that EGR led to a decrease in specific fuel consumption and an increase in brake thermal efficiency. With increase in percent (%) of EGR, the percentage increase in brake thermal efficiency was up to 10.3% at quarter load and up to 14.5% at full load for single fuel operation while for dual-fuel operation an increase up to 9.5% at quarter load and up to 11.2% at full load was observed. The results also showed that EGR caused a decrease in exhaust gas temperature;hence it’s potential to reduce NOX emission. However, emissions of HC and CO increased slightly with EGR.

关键词： DICI Engine Dual-Fuel Engine EGR NOX

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Persicaria lanigera (Polygonaceae) leaf extract exhibits antiulcerogenic and antiproliferative activities against acetic acid-induced ulcerative colitis and cotton pellet-induced granuloma tissue in rats

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Asian Pacific Journal of Tropical Biomedicine 2024年第7期14卷 269-278页

作者： meshack Antwi-Adjei Ernest Obese Emmanuel Awintiig Adakudugu Benjamin Aboagye Daniel Anokwah Akua Afriyie Karikari Roberta Antwi-Adjei Elvis Ofori Ameyaw Department of Pharmacology School of Medical SciencesUniversity of Cape CoastCape CoastGhana Department of Pharmacotherapeutics and Pharmacy Practice School of Pharmacy and Pharmaceutical SciencesUniversity of Cape CoastCape CoastGhana Department of Forensic Sciences School of Biological SciencesUniversity of Cape CoastCape CoastGhana Department of Pharmacognosy and Herbal Medicine School of Pharmacy and Pharmaceutical SciencesUniversity of Cape CoastCape CoastGhana Department of Biomedical Sciences School of Allied Health SciencesCollege of Agriculture and Natural SciencesUniversity of Cape CoastCape CoastGhana

Objective:To assess the effect of leaf extract of Persicaria lanigera on cotton pellet-induced granuloma tissue formation and acetic acid-induced ulcerative ***:Rats were randomly divided into six groups:normal control,negative control,positive control(dexamethasone or sulfasalazine)as well as Persicaria lanigera(100-600 mg/kg)-treated *** effects of the extracts on body weight,antioxidant,and hematological parameters,as well as mast cell proliferation,were *** addition,a histological evaluation was ***:Persicaria lanigera extract significantly decreased the mean exudate amount and suppressed granuloma tissue formation in a concentration-dependent manner in rats(P<0.05).Additionally,the extract significantly increased body weight,improved hematological profile,reduced the disease activity index score and malondialdehyde level,as well as enhanced catalase and superoxide dismutase activities(P<0.05).Histological evaluation showed Persicaria lanigera extract alleviated acetic acid-induced colonic damages,as evidenced by decreased cell necrosis,edema,and inflammatory cell ***:Persicaria lanigera extract possesses antiproliferative,antioxidative,and anti-colitis ***,its underlying mechanisms of action need further investigation.

关键词： Colitis Persicaria lanigera Antioxidant Cotton pellets Mast cells Granuloma tissue formation

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Experimental investigation and optimization of the gasification parameters of macadamia nutshells in a batch-fed bubbling fluidized bed gasifier with air preheating

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Energy Storage and Saving 2023年第4期2卷 559-570页

作者： Fredrick Irungu Njuguna Hiram M.Ndiritu Benson B.Gathitu meshack Hawi Jotham Muthoka Munyalo School of Mechanical Manufacturing and Materials EngineeringJomo Kenyatta University of Agriculture and TechnologyNairobi62000-00200Kenya School of Biosystems and Environmental Engineering Jomo Kenyatta University of Agriculture and TechnologyNairobi62000-00200Kenya

Gasification of biomass waste has a significant potential to reduce environmental impact and promote sustainability by producing syngas,which is considered as renewable *** work investigated the gasification of macadamia nutshells in air-preheated,batch-fed fluidized bed *** study conducted a parametric analysis to assess the effect of equivalence ratio(ER)and air temperature on the gasifier temperature profile and its performance based on gas composition,higher heating value(HHV),and gas *** research was conducted within the range of 0.15-0.35 for the ER and 25-825℃ for the air ***-objective numerical optimization was conducted using response surface methodology(RSM).From the parametric study,a distinct temperature profile was observed along the gasifier height,with the peak temperature near the top of the fluidized bed section and the lowest temperature at the top of the *** preheating mostly favored gasification temperature at the lower part of the gasifier and showed rare significance at the *** improvement in gasifier performance was observed beyond an air temperature of 620℃,which was identified as the ideal air-preheating *** of variance(ANOVA)revealed that the ER was the most influential parameter in the production of combustible gasses,syngas HHV and gas *** preheating did not have a significant effect on methane production and gas *** most optimal values for ER and air temperature were obtained as 0.195℃ and 620℃,respectively,producing optimal values of 9.54,14.65%,2.03,4.02 MJ⋅Nm^(-3),and 1.82 Nm^(3)⋅kg^(-1) for hydrogen,carbon monoxide,methane,HHV,and gas yield,respectively.

关键词： Biomass gasification Air preheating Optimization Response surface methodology

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Performance of Water in Glass Evacuated Tube Solar Water Heater under Kenya Climatic Condition

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Computational Water, Energy, and Environmental Engineering 2021年第2期10卷 37-48页

作者： Ernest Kyekyere Hiram Ndiritu meshack Hawi Polline Mwambe Department of Mechanical Engineering Pan African University Institute for Basic Sciences Technology and Innovation Nairobi Kenya Department of Mechanical Engineering Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar water heaters as a result of their greater surface area exposed for sunlight absorption. Water-in-glass evacuated tube solar water heaters are widely used as compared to heat-pipe solar water heaters due to their short payback periods. In this study, the performance of water-in-glass evacuated tube solar water heater is investigated through experiments under the climatic conditions in Kenya. The results revealed a daily efficiency range of 0.58 - 0.65 and a daily final outlet temperature greater than 55°C given an initial temperature of 25°C.

关键词： Solar Water Heater Water-in-Glass Evacuated Tube Solar Collector Solar Irradiation

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Optimization of Flow Parameters for Waste Lubricating Oil Combustion

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World Journal of Engineering and Technology 2022年第4期10卷 875-894页

作者： Dorcas Makworo Robert Kiplimo meshack Hawi Bernard Owiti Pan African University Institute for Basic Sciences Technology and Innovation Nairobi Kenya Department of Marine Engineering and Maritime Operation Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Department of Mechanical Engineering Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya

The global energy demand has continued to skyrocket, exacerbating the already severe energy problem and environmental pollution, prompting researchers to look for alternative energy sources. Exploration of waste lubricating oil (WLO) as an alternative source of fuel has gained prominence among researchers due to its availability at low cost and the potential to generate energy while providing a safer means of disposal. The main challenge with WLO combustion is proper regulation of fuel and oxidizer during combustion to realize a near stoichiometric result. Additionally, WLO has high viscosity, hence preheating of the oil is necessary to lower the viscosity and enhance atomization, for a more efficient combustion process. This paper presents the optimization of flow parameters for combustion of WLO in a burner system by use of response surface methodology (RSM). The effects of air flow rate, injection pressure and fuel flow rate on combustion performance of a WLO burner were investigated. The highest flame temperature recorded was 1200°C at an air flow rate of 1 m3/min, fuel flow rate of 0.08 m3/hr and injection pressure of 20 bar. Tests on physical and chemical properties of WLO were conducted and characterized according to ASTM standard to ascertain its potential as an alternative fuel. The calorific values of WLO from petrol and diesel engines were found to be 41.23 MJ/kg and 42.65 MJ/kg respectively. Therefore, recycling of WLO by utilizing it as a fuel for burners has double benefits of mitigating environmental pollution and harnessing energy for process heating and power generation.

关键词： Waste Lubricating Oil Combustion Burner Optimization Flame Temperature Response Surface Methodology

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Stomatal Conductance, Growth and Yield of Pelargonium sidoides DC. in Response to Watering Frequency and Terminal Water Stress

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Journal of Agricultural Science and Technology(A) 2017年第8期7卷 513-521页

作者： Motiki meshack Mofokeng Hintsa Tesfamichael Araya Phatu William Mashela Christian Phillipus du Plooy Agricultural Research Council Roodeplaat Vegetable and Ornamental Plant Institute (ARC-Roodeplaat VOP) Private Bag X293Pretoria 0001 South Africa Green Technologies Research Centre University of Limpopo Private Bag X1106 Sovenga 0727 South Africa

Water is an important factor affecting growth, yield and distribution of different species. Plant response to water deficit can be in the form of physiological disorders, such as reduction in transpiration or assimilating partitioning to root growth. Sustainable use of water has become a priority in agriculture and thus innovative irrigation management practices are critical. The study aimed at investigating how watering frequency and terminal water stress influence growth of Pelargonium sidoides, an important medicinal plant in Southern Africa. The trial was a randomized complete block design with three replicates, and treatment factors were watering frequency （everyday, twice and once a week） and terminal water stress （no watering four weeks before harvesting, no watering two weeks before harvesting and no terminal stress）. There was an interacting effect of watering frequency and terminal water stress on biomass and fresh root yield. More frequent watering resulted in significantly higher biomass and fresh root yield, compared to other treatments. Watering everyday with terminal or no terminal water stress resulted in higher fresh root yield, compared to other watering treatments with terminal water stress. Plant height and leaf area were significantly affected by watering frequency and terminal water stress, respectively. A significant drop in stomatal conductance of plants watered everyday was observed 240 d after treatment implementation, such that there was no significant difference across all the three watering frequency treatments. In conclusion, farmers can save on irrigation costs by reducing watering frequency, as there was no significant difference on dry root yield.

关键词： African geranium irrigation water stress stomatal aperture root yield drought tolerance.

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Trends of Temperature Extreme Indices over Arusha and Kilimanjaro Regions in Tanzania

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Atmospheric and Climate Sciences 2021年第3期11卷 520-534页

作者： Ladislaus Benedict Chang’a Lovina Peter Japheth Agnes Lawrence Kijazi Elisia Hamisi Zobanya Leila Francis Muhoma meshack Anton Mliwa Jafari Swalehe Chobo Research and Applied Meteorology Tanzania Meteorological Authority Dar es Salaam Tanzania Agrometeorological Section Tanzania Meteorological Authority Dar es Salaam Tanzania Tanzania Meteorological Authority Dar es Salaam Tanzania Climatology and Climate Change Section Tanzania Meteorological Authority Dar es Salaam Tanzania Volunteers Tanzania Meteorological Authority Dar es Salaam Tanzania

The study aimed at analyzing the trends and variability of temperature extremes over the northeastern highlands in Tanzania, specifically over Arusha and Kilimanjaro regions. Quality controlled mean monthly, daily maximum and minimum temperature data for the period 1961 to 2020, obtained from Tanzania Meteorological Authority, were used in the study. Rclimdex and the National Climate Monitoring Products (NMCP) software, developed by the World Meteorological Organization (WMO), were used for

关键词： Climate Extreme Warm Night Cold Night Extreme Temperature Indices NCMP

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Total Carbon Stock and Potential Carbon Sequestration Economic Value of Mukogodo Forest-Landscape Ecosystem in Drylands of Northern Kenya

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Open Journal of Forestry 2022年第1期12卷 19-40页

作者： Nereoh C. Leley David K. Langat Abdalla K. Kisiwa Geoffry M. Maina meshack O. Muga Kenya Forestry Research Institute Nairobi Kenya Department of Natural Resources Egerton University Njoro Kenya Food and Agriculture Organization of the United Nations Nairobi Kenya

Carbon sequestration is one of the important ecosystem services provided by forested landscapes. Dry forests have high potential for carbon storage. However, their potential to store and sequester carbon is poorly understood in Kenya. Moreover, past attempts to estimate carbon stock have ignored drylands ecosystem heterogeneity. This study assessed the potential of Mukogodo dryland forest-landscape in offsetting carbon dioxide through carbon sequestration and storage. Four carbon pools (above and below ground biomass, soil, dead wood and litter) were analyzed. A total of 51 (400 m2) sample plots were established using stratified-random sampling technique to estimate biomass across six vegetation classes in three landscape types (forest reserve, ranches and conservancies) using nested-plot design. Above ground biomass was determined using generalized multispecies model with diameter at breast height, height and wood density as variables. Below ground, soil, litter and dead wood biomass;carbon stocks and carbon dioxide equivalents (CO2eq) were estimated using secondary information. The CO2eq was multiplied by current prices of carbon trade to compute carbon sequestration value. Mean ± SE of biomass and carbon was determined across vegetation and landscape types and mean differences tested by one-way Analysis of Variance. Mean biomass and carbon was about 79.15 ± 40.22 TB ha

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