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Open Journal of Microphysics 2024年第2期14卷 13-23页

作者： Calford odhiambo Otieno Department of Physics Kisii University Kisii Kenya

Efficient third-order nonlinearities of the Zinc Oxide and Al-doped Zinc Oxide were studied by Third Harmonic Generation (Third Harmonic Generation) Maker fringes to establish the effect Aluminum of Aluminum doping (Al-doping) on the cubic nonlinearities. Adding the Al-dopant to the Zinc Oxide crystal structure results in changes that affect the optical and nonlinear characteristics. Presented results indicate that the magnitude of X(3) was enhanced at single experimental wavelengths;however, across the broadband experimental spectrum, the effect of Al-doping remained relatively constant. The observed enhancement of third-order nonlinearity was purely from the bound electronic response. The observation is attributed to increased charge carriers and spontaneous polarization in the Zinc Oxide and Al-doped Zinc Oxide crystal structure.

关键词： Nonlinear Optics Harmonic Generation Maker Fringes Zinc Oxide

Influence of Constituent Materials Properties on the Compressive Strength of in Situ Concrete in Kenya

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Open Journal of Civil Engineering 2017年第1期7卷 63-81页

作者： Victoria Akoth Okumu Stanley Muse Shitote walter odhiambo oyawa Pan African University Institute for Basic Sciences Technology and Innovations (PAUISTI) Hosted at Jomo Kenyatta University of Agriculture and Technology (JKUAT) Juja Kenya Multimedia University of Kenya Nairobi Kenya Rongo University Rongo Kenya Commission of University Education Nairobi Kenya

The poor quality of Kenyan in situ concrete has necessitated research to establish the properties of the ingredient materials and their influence on the troubling rate of failure of reinforced concrete structures in the country during construction and usage. The compressive strength of concrete relies on the properties of the constituent materials, proportions of the mixture, workmanship, compaction method and curing conditions. This paper outlines findings of an experimental investigation on the properties of Kenyan concrete ingredient materials and their influence on the compressive strength of concrete in Kenya. Three types of cements (42.5N, 32.5R, 32.5N) from six different cement manufacturers and fine aggregates from three different regions in the country were used during the study. Cements and aggregates chemical analysis was done using the Atomic Absorption Spectrometer machine while the physical and the mechanical properties were checked based on the British Standards. The British DOE concrete mix design method was used to generate the concrete mix proportion and concrete was tested for early and ultimate compressive strengths at 7, 14 and 28 days. It was observed that the different cement brands have varying properties with CEM A having the highest ultimate compressive and flexural strengths. It was further noted that aggregates from the coastal region produced concrete of higher compressive strengths. When the commonly used mix design method was adopted, blended Portland cements produced concrete with ultimate compressive strengths lower than the designed target strengths. The study therefore recommends the development of a concrete mix design procedure for blended cement concrete production in Kenya.

关键词： Blended Portland Cement Ordinary Portland Cement Concrete Compressive Strength Concrete Constituent Materials Blended Portland Cement Concrete

Compressive and Flexural Strength of Recycled Reactive Powder Concrete Containing Finely Dispersed Local Wastes

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Open Journal of Civil Engineering 2018年第1期8卷 12-26页

作者： Demiss Belachew Asteray walter odhiambo oyawa Stanley Muse Shitote Civil Engineering Department Pan African University Institute for Basic Science Technology and Innovation Hosted at Jomo Kenyatta University of Agriculture and Technology Nairobi Kenya Addis Ababa Science and Technology University Addis Ababa Ethiopia Commission for University Education Nairobi Kenya Civil and Structural Engineering Department Moi University Eldoret Kenya

The main objective of this experimental study is to investigate the behavior of Recycled Reactive Powder Concrete (RRPC) developed from finely dispersed local waste raw materials. In this study, RRPC was developed by utilizing local wastes (finely dispersed waste glass powder, waste fly ash and waste ceramic powder) together with Portland cement, fine sand, admixture, steel fibers and water through full replacement of silica fume as well as quartz powder for sustainable construction practice. In this study, all raw materials for making RRPC were analyzed for X-Ray Fluorescence analysis. For sustainability of local construction works, this study employed standard curing method at ambient temperatures instead of steam curing at higher temperatures. Moreover, hand mixing was used throughout the study. To evaluate the structural performances of the developed RRPC mixes, compressive and flexural strengths of RRPC were investigated experimentally and compared with the control mix. The experimental results indicated that replacing the silica fume fully by finely dispersed local waste glass powder (GP) and fly ash (FA) is a promising approach for local structural construction applications. Accordingly, a mean compressive strength of 62.9 MPa and flexural strength of 8.8 MPa were developed using 50% GP-50% FA at 28thdays standard curing. In this study, 17.56% larger compressive strength and 30.6% flexural strength improvements were observed as compared to the control mix.

关键词： Local Wastes Recycled Reactive Powder Concrete Compressive Strength Flexural Strength Standard Curing

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay,Southeast China

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Journal of Environmental Sciences 2010年第2期22卷 314-320页

作者： Mangala Yatawara odhiambo Joshua Owago Julia E Burnet Key Laboratory of Biogeology and Environmental Geology of Ministry of Education

In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays, Fujian Province, China, concentrations of organochlorine pesticides （hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs） and heavy metals （Cu, Pb, Zn, As, Cr, Cd, Ni and Hg） in 13 species collected from different sites in the hays were analyzed by GC-ECD and ICP-MS. The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples. Most of the organisms showed higher levels of DDTs than the first level criterion （10 ng/g） for marine biological quality in China （GB 18421-2001） but conformed to the first level criterion （20 ng/g） for HCHs. The estimated mean daily uptake of pesticides was below the level for minimal risk to the consumers. The levels of Cd, As and Pb in most organisms from both bays were markedly elevated and above the recommended legal limits for human consumption. Our results showed the need for routine monitoring of marine species contamination to ensure public and environmental health.

关键词： organochlorine pesticides residue levels technical HCH heavy metals Fujian Province

Density Functional Study of Mechanical, Electronic and Pressure Induced Phase Transition Properties of CaFé₂As₂

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Open Journal of Microphysics 2023年第3期13卷 36-51页

作者： Mochama Victor Samuel Calford odhiambo Otieno Phillip Nyawere Department of Physics Kisii University Kisii Kenya Department of Physical and Biological Sciences Kabarak University Nakuru Kenya

We report results on the ab initio study of the mechanical and electronic properties of the iron Pnictide compound CaFe2As2 and its phase transition under pressure using Quantum Espresso code. We do analysis of the strength of bonds in individual points of this material and proper Cauchy pressure calculation which will give more insight on the elastic responses. Ground state energy was done in the framework of density functional theory (DFT) based on plane wave self-consistent field (PWscf) and ultrasoft pseudo potential (USPP) method as treated in the Perdew-Burke Ernzerhof (PBE) generalized gradient approximation and local density approximations. Elastic constants were computed using thermo_pw and the values were used to calculate mechanical properties and pressure phase changes. From the non-zero positive elastic constants, the Iron Pnictide compound is found to be mechanically stable and its Poisson’s ratio indicates that it is brittle and isotropic. Pressure induced phase transition is here found to happen at an applied external pressure of 0.2 GPa causing the tetragonal phase to change to an orthorhombic phase which agrees well with previous reports.

关键词： Phase Transition Elastic Constants Modulus

Size,efficiency,market power,and economies of scale in the African banking sector

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Financial Innovation 2019年第1期5卷 54-75页

作者： Simplice A.Asongu Nicholas M.odhiambo Department of Economics University of South AfricaP.O.Box 392Pretoria 0003South Africa Department of Economics&Development Studies Covenant UniversityOtaNigeria

There is a growing body of evidence that interest rate spreads in Africa are higher for big banks compared to small banks.One concern is that big banks might be using their market power to charge higher lending rates as they become larger,more efficient,and unchallenged.In contrast,several studies found that when bank size increases beyond certain thresholds,diseconomies of scale are introduced that lead to inefficiency.In that case,we also would expect to see widened interest margins.This study examines the connection between bank size and efficiency to understand whether that relationship is influenced by exploitation of market power or economies of scale.Using a panel of 162 African banks for 2001–2011,we analyzed the empirical data using instrumental variables and fixed effects regressions,with overlapping and non-overlapping thresholds for bank size.We found two key results.First,bank size increases bank interest rate margins with an inverted U-shaped nexus.Second,market power and economies of scale do not increase or decrease the interest rate margins significantly.The main policy implication is that interest rate margins cannot be elucidated by either market power or economies of scale.Other implications are discussed.

关键词： Sub-Saharan Africa Banks Lending rates Efficiency Quiet life hypothesis Competition

Demography, reproductive biology and diet of the bushveld gerbil Tatera leucogaster (Rodentia: Gerbillinae) in the Lake Rukwa valley, south-western Tanzania

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Integrative Zoology 2008年第1期3卷 31-37页

作者： Richard O.odhiambo Rhodes H.MAKUNDI Herwig LEIRS Ron VERHAGEN Pest Management Centre Sokoine University of AgricultureMorogoroTanzania Evolutionary Biology Department of BiologyUniversity of AntwerpAntwerpBelgium Danish Pest Infestation Laboratory Danish Institute of Agricultural SciencesKongens LyngbyDenmark

Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.

关键词： feeding ecology reproduction seasonal abundance Tanzania Tatera leucogaster

Chimeric ALT Perforator-Free Flap with Vastus Lateralis Muscle for the Obliteration of the Intrathoracic Dead Space Post-Pneumonectomy: A Case Report

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Modern Plastic Surgery 2023年第3期13卷 63-73页

作者： Nelson Oduor Ouma Daniel odhiambo Otieno Lee Njagi Munge Ferdinand Wanjala Nang’ole Department of Surgery Plastic Reconstructive and Aesthetic Surgery Thematic Unit College of Health Sciences The University of Nairobi Nairobi Kenya

Chest wall reconstruction is a surgical procedure aimed at restoring the integrity and function of the chest wall, which may be damaged due to trauma, cancer, infection, or congenital defects. The chest wall plays a vital role in protecting the thoracic organs, supporting the respiratory system, and maintaining the shape of the chest. Therefore, any defect or deformity of the chest wall can have significant functional and aesthetic consequences for the patient. The authors present a case report at Kenyatta National Hospital (KNH) of a dyspneic 47-year-old male patient with a right anterolateral chest wall defect post-pneumonectomy previously complicated by bronchopleural fistula. Past attempts at the chest wall reconstruction had utilized the ipsilateral latissimus dorsi muscle, pectoralis major muscle, and the omental pedicled flaps with limited success. A chimeric anterolateral thigh (ALT) perforator-free flap with vastus lateralis (VL) muscle was used to obliterate the post-pneumonectomy intrathoracic dead space and to provide a cutaneous paddle. This case report aims to show the versatility of the ALT flap for chest wall reconstruction to prevent the post-pneumonectomy syndrome associated with tracheal deviation, inspiratory stridor, and exertional dyspnea. In conclusion, chest wall reconstruction with obliteration of intrathoracic dead space post-pneumonectomy is challenging and needs careful planning and execution.

关键词： Chest Wall Reconstruction Bronchopleural Fistula Pneumonectomy Chimeric ALT Flap Intrathoracic Dead Spacepost-Pneumonectomy

Seasonal Variation in Physicochemical Properties of Groundwater, a Case Study of Kamiti-Marengeta Subcatchment Kiambu, Kenya

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Journal of Water Resource and Protection 2022年第2期14卷 72-85页

作者： Miriam Judith Adongo Mary Kalibala Makokha Joy Apiyo Obando Jacob odhiambo Ochieng Department of Geography Kenyatta University Nairobi Kenya Department of Environmental Science Kenyatta University Nairobi Kenya

The seasonal variation and quality status of groundwater systems of Kamiti-Marengeta sub-catchment were evaluated through analysis of boreholes and 17 shallow wells water samples in May 2016 and September 2017. Consequently, the results were compared against the Kenya Bureau of Standards (KEBS) and World Health Organization (WHO) guidelines for drinking water purposes, and its suitability for drinking was established. The results showed that turbidity, calcium, potassium, iron, and fluoride levels in some of the boreholes and pH, calcium, sodium, and iron levels in some shallow wells exceeded the KEBS and WHO standards for drinking water quality. Turbidity, dissolved oxygen, and total hardness significantly varied across the regions of the study, and one-way ANOVA (P < 0.05) indicated a significant difference in the mean concentration of electrical conductivity, turbidity, total hardness, calcium, and iron in boreholes and in all parameters in shallow wells except for magnesium during the two seasons. The findings of this study provide baseline information on the quality of the groundwater systems of the area. It also contributes to knowledge on seasonal variation of groundwater quality of volcanic aquifers like the Nairobi Aquifer System (NAS) which is important for water quality monitoring.

关键词： Groundwater Water Quality Seasonal Variation

Organochlorine Pesticides(OCPs) in Soils Along the Eastern Slope of the Tibetan Plateau

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Pedosphere 2010年第5期20卷 607-615页

作者： XING Xin-Li QI Shi-Hua ZHANG Yuan YANG Dan J. O. odhiambo Key Laboratory of Biogeology and Environmental Geolagy of Ministry o.f Education China University of Geosciences Wuhan 430074 (China) School of Environmental Studies China University of Gcosciences Wuhan 430074 (China)

Soil samples collected from several sites along an altitudinal transect on the eastern slope of the Tibetan Plateau were analyzed for hexachlorobenzenes(HCHs) and dichlorodiphenyltrichloroethanes(DDTs).The results showed that HCHs and DDTs were found in the soil samples from the remote high altitude areas away from source regions,which confirmed the long-range atmospheric transport phenomenon of these organochlorine pesticides(OCPs) insecticides.The OCP concentrations in the soils had a significant negative correlation with altitude;they showed a trend to increase with decreasing altitude,but the increase was not continuous,being interrupted at some moderate-altitude sites on the transect.The distances from the source region,landforms,soil properties,and physical-chemical properties of OCPs were more important than total organic carbon content to the distribution of OCPs in soils disturbed by human activities.An analysis of the compositions of HCH isomers and DDTs revealed predominantly low ratios of α-HCH to γ-HCH,ranging from 0.06 to 4.79,which suggested current lindane inputs.On the other hand,low p,p-DDT/p,p-DDE and o,p-DDT/p,p-DDT ratios were observed,indicating mainly aged historical DDT residues in the study area.

关键词：有机氯农药土壤样品青藏高原六氯环己烷高海拔地区远距离传输东坡人类活动干扰