Natural & Applied Sciences

Research Papers/Topics Natural & Applied Sciences

The status and challenges of a modern irrigation system in Kenya: A systematic review

Abstract The modernization efforts of the irrigation subsector in Kenya have been hampered by several challenges. This review describes the status and challenges facing irrigated agriculture in Kenya. The results indicated that as of 2018, the developed irrigation schemes covered an area of 222,240 ha, which is 16% of the irrigation potential of 1.34 million ha. Most large-scale irrigation schemes use the furrow system. Private and commercial farms and smallholder irrigation schemes use mo...

Sensitivity and Optimal Control Analysis of an Extended SEIR COVID-19 Mathematical Model

Abstract In this paper, a mathematical model based on a system of ordinary differential equations is developed with vaccination as an intervention for the transmission dynamics of coronavirus 2019 (COVID-19). The model solutions are shown to be well posed. The vaccine reproduction number is computed by using the next-generation matrix approach. The sensitivity analysis carried out on this model showed that the vaccination rate and vaccine efficacy are among the most sensitive parameters of t...

Effects of Sand-Harvesting on River Water Quality and Riparian Soil Physico-Chemical Properties

Abstract The widespread distribution of river sand-harvesting activities continues to degrade river water quality and the surrounding riverine environments. This study determined practical effects of sand-harvesting on two rivers in Kakamega County Kenya. Water samples were tested for turbidity and total suspended solids (TSS). For riparian soils, nitrogen (N), phosphorus (P), pH, organic carbon (OC), moisture content and textural class were determined on composite samples obtained from the ...

Comparative effects of nitrogen, phosphorus and potassium on Radopholus similis infection in East African Highland Banana plants as influenced by rhizosphere biota

Abstract Root parasitism by Radopholus similis may vary under different nutritional conditions and soil substrates. Such variations in nematode infection may affect deductions from evaluations of pest control measures. Three parallel factorial experiments (nutrients × soil sterility × nematode) were conducted to investigate the effects of N-P-K and soil biota on R. similis infection and banana plant growth. Chlorophyll content was lower in plants receiving N-deficient solution or w...

Factors associated with uncorrected refractive errors in school-going adolescents in Kakamega County, Kenya

Abstract Background: Uncorrected refractive errors (URE) present an enormous burden on children in Kenya. The study investigated factors associated with URE in school-going adolescents in Kakamega County, Kenya. Material and methods: An observational, cross-sectional study with multistage sampling was conducted with randomly selected secondary school students in forms one to four. Comprehensive clinical examinations conducted by optometrists were used to determine participants’ URE types a...

Occurrence and Distribution of Per- and Polyfluoroalkyl Substances from Multi-Industry Sources to Water, Sediments and Plants along Nairobi River Basin, Kenya

Abstract Per- and polyfluoroalkyl substances (PFAS) are ever-present pollutants in the environment. They are persistent and bio-accumulative with deleterious health effects on biota. This study assesses the levels of PFAS in environmental matrices along the Nairobi River, Kenya. An aggregate of 30 PFAS were determined in water, while 28 PFAS were detected in sediments and plants using solid phase extraction then liquid chromatography–mass spectrometric techniques. In water, higher levels o...

Effects of oil exploration on surface water quality- a review

Abstract The oil industry is a source of revenue and foreign exchange for an economy. Nevertheless, oil exploration is an inherent risk to the environment due to the pollution of water resources, especially surface water resources. The main waste is produced water which is increasing around the world .As a consequence,water pollution resulting from normal oil drilling, refining, distribution, and accidents is the principal concern of oil exploration in the environment. Oil pollution is assoc...

Ethernal Conversion to Butanol over Small Coinage Metal Clusters: An Experimental and Computational Study

Abstract We illustrate the mechanism for the C–O, C–H and O–H bond activation in the coupling of ethanol to butanol over small coinage clusters (copper, silver and gold). It is found that charge transfer interactions between the clusters and the alcohol initiate their reactions allowing a chemisorption step. The binding energy is calculated, whereby ethanol adsorbs very strongly on Au in comparison to Ag and Cu. The nature of bonding is investigated using natural bond orbital (NBO) ana...

Red cell distribution width as a surrogate marker of haemoglobinopathies in western Kenya

Abstract distribution width (RDW) measures anisopoikiloytosis and is readily reported by haematology analysers as a complete blood count parameter. The utility of RDW as a diagnostic marker of haemoglobinopathies in Kenya remains undetermined and undocumented. Objective: This study aimed to determine the diagnostic efficacy of RDW in discriminating haemoglobinopathy and haemoglobinopathy-free cases in Kenya. Methods: The case-control study used randomly selected haematology analyser outputs ...

Soil Microbes Determine Outcomes of Pathogenic Interactions Between Radopholus similis and Fusarium oxysporum V5w2 in Tissue Culture Banana Rhizospheres Starved of Nitrogen, Phosphorus, and P

Abstract The contributions of soil biota toward outcomes of pathogenic interactions between Radopholus similis and Fusarium oxysporum V5w2 in tissue culture banana plants starved of nitrogen (N), phosphorus (P), and potassium (K) were investigated. The study was based on three screenhouse factorial experiments (2 × 2 × 2) comprising of potted banana plants with or without R. similis, with or without F. oxysporum V5w2, and either grown in sterile or non-sterile soil. All plants in each of t...

The Role of Innovative Teaching and Learning Methods Towards the Classification of Living Things: A Review

Abstract Biology continues to present difficulties in teaching and learning. Among other biology domains classification of living things is considered to be one of the challenging subjects as different studies indicated students’ misconceptions in the test to classify both plants and animals. Inadequate teaching methods were the core source of these challenges which were also found to lead to poor performance in schools. This review paper shows the role of active teaching methods to improv...

Risk Factors Associated with Helminthic Intestinal Infection in Lurambi Subcounty, Kakamega, Kenya

Abstract Background. Soil-transmitted helminths (STHs) and schistosome infections have been known to be major causes of morbidity and mortality in sub-Saharan countries. School aged and preschool children are known to be at high risk of infection. Therefore, the aim of this study was to determine the prevalence and risk factors associated with soil-transmitted helminths among school-going children in Lurambi Subcounty, Kakamega, Kenya. Method. A cross-sectional study was conducted from Jan 2...

Semiochemical signatures associated with differential attraction of Anopheles gambiae to human feet

Abstract Background Several human-produced volatiles have been reported to mediate the host-seeking process under laboratory conditions, yet no effective lure or repellent has been developed for field application. Previously, we found a gradation of the attractiveness of foot odors of different malaria free individuals to Anopheles gambiae sensu stricto Giles. In this study, foot odor of the individual with the most attractive ‘smelly’ feet to the An. gambiae was collected, analyzed and ...

Direct detection of bacteremia by exploiting host-pathogen interactions of lipoteichoic acid and lipopolysaccharide

Abstract Bacteremia is a leading cause of death in sub-Saharan Africa where childhood mortality rates are the highest in the world. The early diagnosis of bacteremia and initiation of treatment saves lives, especially in high-disease burden areas. However, diagnosing bacteremia is challenging for clinicians, especially in children presenting with co-infections such as malaria and HIV. There is an urgent need for a rapid method for detecting bacteremia in pediatric patients with co-morbiditie...

Genome Sequence of a Staphylococcus xylosus Clinical Isolate, Strain SMA0341-04 (UGA5), from Siaya County Referral Hospital in Siaya, Kenya

Abstract We report here the genome sequence of a Staphylococcus xylosus clinical isolate, strain SMA0341-04 (UGA5), which contains one chromosome and at least one plasmid. Notably, strain SMA0341-04 (UGA5) contains the tetracycline efflux major facilitator superfamily (MFS) transporter (tetK) gene.


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