Polybrominated Diphenyl Ethers Pollution in Urban and Rural Settings’ Ambient Air in Kenya: An Insight into Concentration Levels, Compositional Profile and Seasonal Variation

Air samples were collected from three urban and one rural sites in Kenya with the aim of establishing pollution levels of Polybrominated Diphenyl Ethers. Forty-eight air Samples were collected by passive air sampling, Soxhlet extracted and analysed for brominated diphenyl ethers using gas chromatography coupled with mass spectrometer. The mean concentration of polybrominated diphenyl ethers residue in air ranged from ≤0.9 to 152.72±3.19 pgm−3. The predominant congener was 2,2′,4,4′-tetra-bromodiphenyl ether with mean concentration range of 1.94±0.03 to 152.72±3.19 pgm−3 followed by 2,2′,4,4′,5-penta- bromodiphenyl ether with mean concentration range of 1.32±0.06 to 66.83±1.19 pgm−3. Seasonal variations of the pollutants showed a high level of Polybrominated Diphenyl Ethers in hot dry season in range of 1.94±0.03 to 152.72±3.19 pgm−3. Air samples from Dandora and Industrial area both from urban location recorded high concentrations of the analysed polybrominated diphenyl ethers compared with the air samples from the rural location

Use of Organic Binders to Enhance Defluoridation and Pathogen Removal Efficiency of Diatomaceous Earth-Based Ceramic Filters

The use of diatomaceous earth, DE, ceramic membranes in water purification has been in existence for centuries. However, the DE-based membranes are brittle, ineffective in the defluoridation, and disinfection of water. The aim of this work is to improve the mechanical strength, water defluoridation, and filtration efficiency of DE-based ceramic membrane using organic binders; Abelmoschus esculentus, Aloe vera, and Basella alba. The ceramic membranes were fabricated from DE-powder and plant-based organic binders with a ratio of 2:1 by mass. The dried samples were fired at 700.0 to 1150.0 °C. The fabricated membranes were then made to filter water contaminated with Escherichia coli, Rotavirus, and sodium fluoride. The results showed the DE-powder was characterized by 87.5%; 4.0% and 89.6; 2.9% silica and aluminum oxides for DE-A and DE-B respectively. Basella alba binder showed the highest content of organic matter and formed the strongest membranes with the highest efficiency. Basella alba was able to improve the modulus of rupture, defluoridation, and virus removal efficiency of the DE-B membranes by 84.8%, 30.9%, and 40.3% respectively. DE-B-powder plus Basella alba are potential materials in ceramic membranes as they were able to defluoridate by 89.2% and remove Rotavirus by 98.3% from water

Occurrence and Distribution of Polybrominated Diphenyl Ethers in Water from Nairobi River Basin, Kenya, East Africa

Polybrominated diphenyl ethers are linked to adverse health effects that includethyroid hormone disruption, neuro-developmental deficit, abnormal pregnancy,and potential carcinogens. This study was aimed at assessing the concentrationsof selected Polybrominated diphenyl ether compounds in water of Nairobi River.Water samples were collected by grab method from nine sites along the river andanalysed for brominated diphenyl ethers using gas chromatography coupled withmass spectrometer. The mean concentration of polybrominated diphenyl ethersresidue in water ranged from <0.0009 to 72.89 ± 6.15 ng/L. The dominantcongeners were 2,2′,4,4′-tetra- bromodiphenyl ether, 2,2′,4,4′,5,5′-hexabromodiphenylether, 2,2′,4,4′,6-penta-bromodiphenyl ether, 2,2′,4,4′,5,5′-hexabromodiphenylether and 2,2′,4,4′,5,6′-hexa-bromodiphenyl. The highest meanconcentration of 2,2′,4,4′-tetra- bromodiphenyl ether was 72.89 ± 6.15 ng/L,2,2′,3,4,4′-penta- bromodiphenyl ether was 14.08±0.68 ng/L, 2,2′,4,4′,6-pentabromodiphenylether was 43.67±1.47 ng/L, 2,2′,4,4′,5,5′-hexa-bromodiphenylether was 24.78±2.49 ng/L, and 2,2′,3,4,4′,5′,6-hepta-bromodiphenyl ether was11.75±0.97 ng/L. Consequently, as these compounds are known to bioaccumulatein fatty tissues, continued use of the river water poses a health risk toanimals and humans due to contamination across the food chain

Loss of Pyrethrins Content during Drying of Chrysanthemum cinerariifolium Flowers in Direct Sunlight

Pyrethrins are organic compounds derived from the flowers of Chrysanthemum cinerariifolium for their insecticidal activities. Pyrethrins I and Pyrethrins II are the two main classes in which Pyrethrins are grouped. The two groups are composed of six organic compounds namely pyrethrin I, jasmolin I, cinerin I, pyrethrin II, jasmolin II and cinerin II. The compounds are degradable on exposure to direct sunlight, moisture and temperatures. Pyrethrins are used as a broad spectrum natural insecticide in agriculture and public health. The aim of this research was to establish the differential total extractable pyrethrins content on drying flowers in direct sunlight and in darkness. Mature pyrethrum flowers from experimental farm, College of Agriculture and Veterinary Sciences, Kabete campus, University of Nairobi, were harvested in brown paper bags, divided into four sets and taken to the laboratory. The first set of flowers were dried in direct sunlight for two weeks and the second set to a constant weight at a temperature of between 16-29OC. The third set were dried in darkness for two weeks and the fourth set to a constant weight at room temperature. Drying was done between 3rd- 17th of August 2019. The dried flowers were then ground into fine powder and extracted using Soxhlet extraction method with hexane. The extracts were refined and analyzed by titrimetric method. Pyrethrum flowers were found to achieve maximum moisture loss at varying times depending with the dying method used. The yield of pyrethrins obtained on drying the flowers to constant weight in direct sunlight was 1.02% while in darkness was 1.38%. The percentage of pyrethrins obtained from flowers dried in direct sunlight for two weeks was 0.86 and 1.01 in darkness. Moisture level for the flowers dried to a constant weight was 9%. The pyrethrins I:II ratio was found to vary for the two drying methods used. The best condition to dry the pyrethrum flowers was found to be in darkness to a moisture content of 9%

Concurrent Machine learning Assisted Raman Spectroscopy of Whole Blood and Saliva for Breast Cancer Diagnostics

Highly sensitive and unique biomarkers are needed for early cancer detection. In particular, biomarkers in biofluids can be useful in detecting the existence of a tumor early in the body. The utility of biofluid markers for cancer detection can be enhanced when multiple biofluids are simultaneously biochemically analyzed in order to acquire complementary information for diagnostic purposes. This work aimed at investigating the universal human whole blood and saliva biomarkers for breast cancer screening using machine learning-assisted Raman spectroscopy. Raman spectroscopy was performed in the 393 – 2063 cm-1 region using 785 nm laser excitation. Machine learning-assisted Raman spectroscopy was implemented by performing principal component analysis, independent component analysis, and support vector machine modeling on the Raman spectra in order to extract the underlying multivariate relationships between the observed biochemical alterations. Ten spectral regions were determined: 612 ± 1.44 cm-1, 785 cm-1, 968 ± 2.02 cm-1, 1000 ± 0.86 cm-1, 1248 cm-1, 1340 cm-1, 1371 ± 0.57 cm-1, 1448 ± 1.73 cm-1, 1500 ± 2.88 cm-1, and 1661 ± 1.44 cm-1, which can be regarded as universal biomarkers of breast cancer using both whole blood and saliva samples. The diagnostic models based on principal component analysis followed by support vector machine achieved mean sensitivity of 95.83 ± 2.48%, specificity of 99.16 ± 0.65%, and accuracy of 98.50 ± 0.65% when differentiating healthy blood samples from diseased blood samples. Further, this model yielded mean sensitivity of 73.0 ± 6.20%, specificity of 97.50 ± 0.67%, and accuracy of 93.66 ± 0.80% when differentiating the healthy saliva samples from diseased saliva samples. The determined biomarkers could be used to establish a spectral system for detection of breast cancer. Further work, including large sample sizes, has to be done to figure out how proteins and nucleic acids behave in their conformational states in human blood and saliva before translating the findings to actual clinical application

Comparative Study on Insecticidal Activity of Permethrin with Dust Formulated Essential Oils of Monodora myristica, Syzgum caryophyllatum (L) Alston and Pinus slvestris

A study was conducted to determine the insecticidal activity of essential oils of Monodora myristica African Nutmeg, Pinus sylvestris pine essential oil and Syzgum caryophyllatum (l) alston clove essential oil on Acanthoscelides obtectus bean weevil, Camponotus pennsylvanicus Carpenter ant and Sitophilus oryzae rice weevil at different exposure time. The essential oils were obtained from the plant materials by steam distillation using Clavenger type apparatus. The major components of the essential oils were determined using Gas Chromatography-Mass Spectrometry. The essential oils were formulated with clay and chalk which serve as the carrier 5%w/w using acetone as the co-solvent. A control formulation was also prepared by mixing 1.5ml of the acetone with chalk and clay respectively. It was observed that the essential oil of Syzgum caryophyllatum (l) alston has the highest insecticidal activities followed by Monodora myristica and lastly Pinus sylvestris. Permethrin also has high insecticidal activities but depreciate fast on exposure. The major components of essential oil of Pinus sylvestry are α-pinene 27.17%, 3-Cyclo 21.82%, borneol 6.75%, Syzgum caryophyllatum (l) alston constituents are eugenol 75.90%, Eugenol acetate 17.53%, benzene, 1-ethyl-3-nitro 9.12%, benzoic acid, 3-(1-methylethyl) 7.95% and β–caryophyllene 5.91% and Monodora myristica with Linalool 91%, Sabinol-cis 17.87%, tr-13-octadecenoie 25.18% and palmitic acid 7.66%. The essential oils of Pinus sylvestry, Monodora myristica and Syzgum caryophyllatum (l) alston have insecticidal activity

Petrography and Geochemistry of the Rocks in Lodwar, Kenya and their Influences on Groundwater Quality

Rock geochemistry influences groundwater quality and the aquifer processes of an area. The geology of the study area comprises quartzo-feldspathic gneiss and biotite gneiss of the Precambrian basement, sedimentary Turkana Grits and Holocene sediments, Tertiary volcanics comprising nepheline phonolites and augite basalts, alluvial deposits along the banks of major streams and laggas (ephemeral streams), and Quaternary sands that blanket much of the area. This paper evaluates the influence of rock chemistry on groundwater quality in Lodwar area. Conventional petrography and geochemistry techniques involving measurement of major elements using X-ray fluorescence (XRF) and trace elements using and X-ray diffraction (XRD) in 69 rock samples to evaluate their mineralogical compositions. The major rock-forming in rocks of the study area include pyroxenes, olivine, kaolinite, siderite, fluorite calcite and dolomite. These minerals release major ions to groundwater through weathering, leaching, oxidation, dissolution and precipitation, and ion exchange reactions during rock-water interactions. The rocks in study area have generally low amounts of Na and K with modal values < 2.00 wt%, suggesting other sources of Na+ and K+ ions in groundwater. In contrast, Ca, Mg, Al, Fe and Mn are released to groundwater from rocks, as shown by high modal compositions of individual elements and associated oxides. The higher concentrations of Na+, K+, Ca2+ and Mg2+ in the groundwater of the Turkana Grit aquifer relative to the grit rock samples suggest a long history of dissolution and recycling of the groundwater. The ratio SiO2:Al2O3 was found to be greater than 8.0 implying a high degree of maturity of the grits. The results presented by this study show that geological factors and processes have location-specific influence on groundwater quality and should be considered in aquifer water quality studies and supply development across Africa’s vast ASAL regions

Optimal Control Problem for Cholera Epidemiology

In this paper, the major objective was to theoretically investigate, proof the existence and local optimality state of singular control by applying L1 type objective function. The objective function L1 has been applied in a Compartmental model since it is linear in the control variables. Generalized Legendre-Clebsch Condition applied showed the existence of singular control for both vaccination and sanitation that are optimal. The condition for local stability of the model was also established and the basic reproductive number assimilated. The disease-free equilibrium of the model is locally asymptotically stable if < 1, and unstable if >1. This means that all interventions applied need to reduce the basic reproductive number to reduce the force of infection

Understanding and explaining observed variability in microwave amplification by stimulated emission of radiation (maser) sources in NGC 6334 I

An active star forming region NGC 6334I has continued to undergo variations in the velocity and flux intensity of the 1665 MHz OH maser transition. We report the findings of the periodic variation observed in the velocity of the 1665 MHz OH maser for observations that started in October 2011 to December 2016 using the 26 m Hartebeeshoek Observatory radio telescope. Two velocity channels -10.6 kms-1 and -10.2 kms-1 in the Left Circular Polarization showed evidence of periodic variation. The period of variation was found to be equal to 366.01 ± 3.33 and 365.89 ± 1.28 days, respectively. The cause of the periodic variation was the uncorrected velocity local standard of rest for maser sources which are far away from NGC 6334I

A climate-smart agriculture approach using double digging, Zai pits and Aquacrop model in rain-fed sorghum cultivation at Wiyumiririe location of Laikipia County, Kenya

The smallholder farmers of Wiyumiririe in Laikipia County are food insecure and highly vulnerable to climate related hazards owing to dearth of resources and over reliance on rain-fed agriculture. A preliminary reconnaissance pre-field visit of the area showed that there were no tangible CSA measures in place that could significantly improve the farmers’ adaptive capacity in a way that would make them food secure. This study therefore sought to investigate how double digging, Zai pits and Aquacrop model would be applied to help the community overcome food insecurity and adapt to climate change. The researcher identified experimental plots that were set out based on the split plot design. The field trials were done from January 2016 to February 2019. Daily weather data, soil water content, above ground biomass and percent canopy cover measured at regular intervals formed input data to calibrate Aquacrop model. The validated model was then used to determine the impacts of climate change on Sorghum crop yields at Wiyumiririe and to prepare scenarios for policy makers. The findings show that the interventions had significant impact because farmers who adopt either double digging or Zai pits and farmyard manure at 5 tons/ha, can obtain yields of approximately 9tons per hectare under current weather conditions and in future under climate change. This is because the attainable yields of 9 tons/ha are more than double the average production in Kenya of 4 tons/ha. Furthermore, the model output showed sorghum crop yields will generally increase in future mainly due associated increased carbon dioxide fertilization. However, the increase in yields needs to be taken with caution. This is because the compounding effects of water stress which is likely to cause a 61% reduction in canopy expansion, 31% closure in stomata and temperature stress of 31% is not yet fully understood. Moreover, the impacts of altered weather patterns to crop physiology, soil chemical properties and; prevalence of crop pests and diseases are still obscure