Catalytic Properties of Luminescent Tris-Homoleptic Cyclometalated Iridium(III) Complexes in the Oxidation of Morin in Visible Light

The photo-oxidation of Morin, 2′,3,4′,5,7-pentahydroxyflavone by six luminescent homoleptic tris-cyclometalated iridium(III) complexes was investigated with the aim of evaluating the catalytic properties of the complexes. The Iridium complexes were synthesized using 2-(1-naphthyl)-pyridine (npy) ligand and its derivatives such as npy-OMe, npy-CF3 and npy-Me to form Tris-homoleptic cyclometalated complexes; Ir(npy)3, Ir(npy-OMe)3, Ir(npy-CF3)3, Ir(npy-Me)3, Ir(Me-npy-Me)3, and Ir(Me-npy)3 with substitution at para position relative to nitrogen. The ligand substitution positions were found to influence the excited state lifetimes, where the complexes exhibited long lifetimes, τ, 1.4 – 3.6 μs, ensuring time for substrates to react before relaxation to ground state. All the six complexes displayed reversible or pseudo reversible redox processes with ground state oxidation potential range of 0.57 to 0.93V compared to Standard Calomel Electrode in CH2Cl2. The complexes degraded morin with rate constants kobs between 0.023-0.036 s -1 within a timescale of 12 minutes. The Ir(npy-Me)3 complex was found to have a high degradation with a rate constant of kobs = 0.036 s -1. Degradation reactions using all the six Iridium (III) complexes photoredox catalysts were found to follow first order kinetics and ca. 10-fold faster compared to similar oxidative reactions

INFLUENCE OF STRATEGY TYPOLOGY ON PERFORMANCE OF FREIGHT FORWARDING COMPANIES IN KENYA

Strategic management scholars have argued that firms in the same industryhave varying performance outcome attributed to several aspects such asthose registering exemplary performance embracing strategy typologies inthe face of intense market demands and rapidly changing competition tosurvive and maintain superior performance. The aim of this study was toestablish the influence of strategy typology on performance of freightforwarding companies in Kenya. The research was based on the industrialorganizational economic theory. Positivism research philosophy anddescriptive cross-sectional survey were used. Stratified random sampling wasapplied to derive a study sample of 120 freight forwarding firms. Primarydata was collected using semi-structured questionnaires. Data was analyzedusing regression analysis. The results of the study showed that there was asignificant influence of strategy typology on organizational performance. Thefinding supported the arguments that industrial organization economictheory assumed that an organization’s performance and ultimate survivaldepend on its ability to adapt to industry forces, even though theorganization has limited control. The study is set to enable management tomake informed decisions while planning for their medium and long-termstrategies. Strategies that are appropriately implemented enable theorganization to compete and record improved performance. The researcherrecommended replication of the study in different sectors and countries toenhance understanding of the relationship between strategy typology andorganizational performance

Artificial Neural Network for Prediction of Pollution Load of Lead, Copper, and Cadmium in a Water Resource: A case Study of River Sosiani, Eldoret Municipality, Kenya

This study aimed at predicting the pollution load of Lead, Copper, and Cadmium in river Sosiani using the Artificial Neural Network, based on parameters, Physico-chemical; turbidity, Electrical Conductivity, and Chemical Oxygen Demand, and Chemical; fluoride and phosphate. The Atomic Absorption Spectrophotometer, Ultra Violet-Visible Spectrophotometer, Ion Selective electrodes and Redox-titration methods were used for analysis in from six sample sites, S1 to S6. A total of 78 datasets from the experimental results were used and divided into three, training 60%, testing 20%, and holdout 20%. The model used the IBM SPSS statistics 20 software, and performances evaluated using Pearson’s correlation coefficient. The mean pollution loads from laboratory analysis were 0.615±0.293, 0.037±0.027, and 0.096±0.030 mg/L while those from ANN were 0.615±0.293, 0.032±0.023, and 0.073±0.033 mg/L for Pb, Cu, and Cd, respectively. The correlation coefficients between the ANN and the observed values for Pb, Cu, and Cd were 0.9999, 0.9910, and 0.9965, respectively. The ANN was able to predict the pollution load of Pb, Cu, and Cd in the river

The Synergy between the Comprehensive Nuclear Test-Ban Treaty Organization and the Kenya National Data Centre: Insights from Analysis of Chyulu Earthquake using Seismic and Infrasound Technologies

Chyulu hills is located on an off-rift volcano in the southwestern Kenya and has been seismically active. On 24th March 2019, Chyulu hills experienced one of the strongest earthquake in Kenya in recent times. The body wave seismic phases, surface wave seismic phase as well as the focal depth was used to analyse the seismic events. The propagation velocity of the seismic wave signal detection through infrasound station I32KE was also used. The seismic and infrasound data were processed using Geotool and DTK-GPMCC softwares provided to member states. The results showed that the seismic event was a natural earthquake by virtue of its focal depth of about 9.1 km and seismic wave velocity of 6.2 km/s. The infrasound station to source azimuth of 139.63o further complemented the epicentre of the seismic event as being in the southwestern Kenya near Chyulu hills

Electrocatalytic reduction and characterization of Tetrachlorvinphos in acetonitrile-water (1:1) media in presence of cyanocobalamin

This work investigates a possible electrocatalytic degradation of tetrachlorvinphos pesticide in acetonitrile-water media using cyanocobalamin as the catalyst. The catalyst and its derivatives are employed in some organic synthesis due to their ability to form and selectively cleave Co-C bonds. There is inadequate data from previous related works. This study explores possible electrocatalytic route for degradation of tetrachlorvinphos using the catalyst at temperature of 24 ± 1° by cyclic voltammetry method. Tetrachlorvinphos exhibited two consecutive reduction peaks at ~-0.710 ± 0.004 V and ~ -1.096 ± 0.029 V Versus Ag/AgCl. The second reduction peak registered a diffusion coefficient value of 3.68 x 10-5 cm2s-1 and current density of be 5.83 x 10-5 A/cm2. The reduction potential for tetrachlorvinphos in presence of cyanocobalamin was observed to be -0.923 ± 0.03 V versus Ag/AgCl. The diffusion coefficient and current density value was reported at 3.37 x 10-5 cm2s-1 and 2.56 X 10-5 A/cm2 respectively for an electro-reduction process. This implies that, catalytic reduction of the pesticide occurred at a significantly lower potential compared to direct reduction. The over potential saving of about 0.168 V is an indication of the catalyst efficiency on the pesticide degradation

Extending usability of old terrestrial fibre optic cables in Third-World Economic Zones

Communication Fibre Optic Cables (FOC) experience mechanical perturbations while in service thereby deforming their cylindrical shape and increasing birefringence. This leads to Polarization Mode Dispersion (PMD). This work investigated PMD fluctuations in cables that have been buried underground for more than 10 years in a semi-arid climatic region in Kenya. PMD was measured using EXFO-FTB5700 analyzer at hourly intervals in the target cables for 2,480 hours. PMD coefficient of 0.215 √⁄ was recorded. Outage margin () of 2.13 for the 10 Gbps system running an On-Off Keying Non-Return-to-Zero (OOK-NRZ) scheme (with 10ps receiver tolerance) was obtained. Similar analysis for the 100 Gbps system running a Dual Polarization Quadrature Phase-Shift Keying (DPQPSK) scheme (with 30 ps receiver tolerance), revealed an outage margin of 6.38. The availability of 99.29 % (corresponding to a downtime of 53.44 hours per year) revealed that, the cable under test could not sustain PMD limitations in a Dense Wavelength Division Multiplexing (DWDM) system that is deployed with a 10 Gbps transponder in a non-regenerated fibre span exceeding 450 km. 100 Gbps DWDM systems proved more resilient when using DP-QPSK than 10Gbps when using OOK-NRZ. The outage of 53.44 hours per year in a high capacity traffic system can translate to a substantial amount of losses in terms of credit notes to customers for not meeting the standard service level agreement of 99.999 % service availability. To overcome this limitation, it is recommended that 10 Gbps transponders that use OOK-NRZ channel modulation technique be replaced with 100 Gbps that uses DP QPSK technique to mitigate dispersion related outages in the links. This would also effectively provide a lot of idle capacity that can accelerate digitization of institutions and villages

Anti-inflammatory activity of selected plants used by the Ilkisonko Maasai, Kenya

Background: The Ilkisonko Maasai are a Kenyan pastoralist community that uses indigenous plants for the management of pain and inflammatory conditions such as arthritis. Objectives: The purpose of this study was to validate the use of plants for medicinal purposes by the Ilkisonko Maasai through testing for anti-inflammatory activity using the carrageenan-induced rat paw oedema assay. Methodology: The methanol extracts (400 mg/kg body weight) of Rhus natalensis (bark), Acacia drepanolobium (bark), Acacia nilotica (bark), Acacia reficiens (bark), Acacia robusta (bark), Grewia villosa (bark), Ximenia americana (bark and leaves) and Rhus vulgaris (leaves) were evaluated for in vivo anti-inflammatory efficacy using the carrageenan-induced rat paw oedema assay. Diclofenac (20 mg/kg body weight) was used as the positive control and paw volume was measured by a plethysmometer. Results: The maximum percentage inhibition (PI) of the extracts was observed as Grewia villosa (58.6% at 24 h), Rhus vulgaris (57.8% at 24 h), Acacia nilotica (55.5% at 1 h), Ximenia americana (54.5% at 1 h), Acacia drepanolobium (50.9% at 24 h), Acacia reficiens (47.6% at 1 h), Rhus natalensis (43.8% at 24 h) and Acacia robusta (37.4% at 24 h) (p < 0.05 for all PI). Diclofenac (20 mg/kg) showed a steady increase in PI from 1 h to 4 h with a maximum PI of 66.2% (p < 0.05) at 4 h and the lowest PI of 14.3% at 24 h. Conclusion: All extracts of the plants assessed exhibited anti-inflammatory activity at early phase of inflammation. Additionally, extracts of five plants, namely Rhus natalensis, Acacia drepanolobium, Acacia robusta, Grewia villosa and Rhus vulgaris showed anti-inflammatory activity at both early and late phases of inflammation. There is need for further studies to identify phytochemicals with active anti-inflammatory activity. Key words- Ilkisonko Maasai, carrageenan, inflammation, Rhus, Acacia, Grewia and Ximeni

Urban Unsustainability and Development

Welcome to the thirteenth edition issue one of the Africa Habitat Review Journal of the School of the Built Environment, University of Nairobi, Kenya. This edition of Africa Habitat Review has presented ten papers on issues relating to Urban Unsustainability and Development.The paper entitled The North-South Divide in Urban Patterns and the Contradictions of Using Homogeneous Instruments of Planning: Lessons from Kenya deals with three development pathways that characterize all urban societies in the world and, these, result in different spatial patterns. The first pathway is laissez-faire, which produces informal or organic urban patterns while the second pathway is the preplanned development trajectory which results in the ideal urban patterns. The third pattern is urban decay, which occurs when preplanned patterns reach optimum thresholds. Countries in the ‘North’ have since minimized or eliminated informal development processes in favour of the preplanned pathway. However, countries in the ‘South’, Kenya included, are trapped in a dual development pathway, where informal patterns dominate the urban fabric, and therefore preplanned theories would be ineffective in regulating such patterns. The paper notes that planning theories and instruments were developed in the North to respond to challenges in their urban development scenarios. These foreign instruments were exported to Kenya during colonial rule. However, the study found that the instruments have never been modified to respond to the specific challenges in Kenya, especially those related to organic urban patterns and this is the main factor in ineffective urban planning.The Unsustainability of Urban Habitat Transformation: A Case Study of Kileleshwa in Nairobi, Kenya paper interrogates the issue of sustainability of the market-driven urban residential transformation of Nairobi through a case study of Kileleshwa, a residential neighbourhood located in the western suburbs of the city. The paper examines the impact of the ongoing transformation from low-density housing to higher density high-rise apartment housing on the sustainability of the urban habitat. This is predicated on an understanding of sustainability in which its components are hierarchically organized to privilege the environmental component over the social and economic ones. The findings indicate that the current production of housing in Kileleshwa is unsustainable. This is demonstrated by the inadequacy of the neighbourhood’s infrastructure in supporting the current trajectory of the habitat’s densification. The paper observes the need to reframe the approach to urban development through a paradigm shift in prioritizing the environmental component of sustainability and deliberate planning for densification in place of the current ad hoc approach to urban development. The paper further observes that sustainable urban development requires both a foregrounding of environmental concerns and the adoption of a holistic approach in the satisfaction of urban needs such as housing with their commensurate physical and social infrastructure. The paper recommends the upgrading of the existing physical infrastructure to support densification, and the redirection of the ongoing urban development towards the more sustainable compact city structure.Cadastre Systems and Their Effectiveness in Implementation of a GIS-Based Physical Addressing System: A Case Study of Kiambu, Thika and Machakos Towns in Kenya study assesses the effectiveness of the cadastre system as a basis for implementation of a GIS-based physical addressing system. This study reveals that the existing cadastre in Thika, Kiambu and Machakos towns was prepared using different scales, have different datum, are incomplete and inadequate, and not current to support a digital physical addressing system. Only the main streets are named and have no unique numbering and naming of properties. The paper observes that the cadastre systems at their current states in the three towns are not effective as a basis of implementing a GIS-based physical addressing system. The paper recommends an inclusive automation of all cadastre records in the three towns. In addition, there is need to develop a National Spatial Data Infrastructure (NSDI) to support physical addressing.A New Frontier in Collaborative Approaches in Sustainable Open Spaces Delivery in Nairobi City was a study aimed to examine the historical loss of public open spaces in Nairobi City. The paper also examined the residents’ awareness of the importance of the resource and sought to determine the collaborative planningand governance approaches used for delivery of sustainable open spaces. Study results indicate serious lossof public open spaces, highlights residents’ awareness of open space benefits and the absence of collaborativeplanning and governance practices. This study recommends new governance structures, higher status for urbanplanning and sustainable open spaces delivery based on pertinent frameworks achieved through collaborativegovernance approaches.The paper on Evaluation of Property Rates Collection and Enforcement in Devolved Systems of Governance inKenya: A Case Study of Nairobi City County focuses on property rates collection and enforcement in devolvedsystems of governance in Kenya, specifically in Nairobi City County. The study sought to establish the propertyrates Collection Ratio (CR) in Nairobi City County (NCC); identify and measure the effectiveness of propertyrates’ collection and enforcement tools in NCC; and determine challenges faced by NCC in rates collection andenforcement. The study established that collection ratio has been reducing over the years; from 16.93 percent in2011/2012 to 6.65 percent in 2014/2015. The property rates collection and enforcement tools utilized in NairobiCity County include provision of discounts and waivers on property rates interest; sanctions and penalties;and social pressure. The enforcement tools that were found to be effective in ensuring compliance in ratespayment include provision of improved public services; operational debt recovery; sanctions and penalties;provision of discounts and waivers on interests & penalties. Some of the challenges hindering compliance inproperty rates payment in Nairobi City County include negative attitude of the public towards property ratesand rates officials; unfair administration; discontentment with property rates administration; and complexitiesin understanding tax system and payment procedures. To improve on compliance, the paper recommendsprovision of improved public services to boost the morale of rates’ payers; use of an integrated computer assistedproperty rates administration system; and capacity building of the administrators.Riparian Zones and Their Role in Enhancing Resilience to Flooding in Urban Areas: A Case Study of NairobiRiver Basin is a paper that elaborates the need to investigate the role of functional riparian zones in enhancingresilience to flooding in urban areas. Specifically, this study examined whether there are developments that areat a permanent risk of floods as a result of ignoring potential role of the riparian zone, and to assess whetherthe criteria used during delimitation of riparian zones is adequate to shield development from effects of floods.This study established that the width of the river varies along the river profile and depends on the adjoiningtopography. The location of the high-water mark therefore is not constant from the river and widens or narrowsdepending on the adjoining topography. The study revealed that there are structures that are at permanent riskof flooding. This study further established that the criteria used during delineation of the riparian zone is notadequate to protect development from flood hazards. Areas where structures are constructed within definedactive flood areas are constricted and they have blocked the flood paths. As a result, floods get elevated dueto lower rate of evacuation causing localized flooding in areas not ordinarily affected by floods. The paperconcludes that functional riparian zones have potential roles of ensuring flood resilience. The study recommendsregeneration of the active flood areas through relocation of structures and planting of trees. The study furtherrecommends pegging of inundated flood areas based on the criteria established in the study.The Production of Space and Place in Informal Settlements: A Case Study of Mukuru Kwa Njenga paper seeksto understand how the space and place are conceived and used in Nairobi´s informal settlements. Using thecase of Mukuru Kwa Njenga, the study explores three questions around the production of space and place; first,whether in informal settlements there exists abstract or conceived space, second, whether the space respondsto a structure of power in the area, and third, how do people use day by day the different categories of space(public, semi-public and private). The study finds that, informal settlements indeed have internal structuresthat resemble the formal city, although in a less systematic way. Ownership of resources and the internalstructures of power play a major role in the conception of space into an informal functional space. This studyconcludes that understanding the spatial dynamics in the informal settlements and creation of flexible spatialsolutions that allow low income people to have a space and place in the city may be the way towards an inclusivetransformation.The paper entitled Universal Design Awareness among Urban Planners and Its Impact on Public Transport Systems in Nairobi, Kenya investigates the level of universal design awareness among professionals (engineers,QS, designers and architects) and the general public in relation to public transport systems in Nairobi-Kenya.Research results revealed that universal design is not a common concept known to most public transport users.The major element of perceptions revolved around cost of universal design application. This study establisheda lack of a clear framework and policies on universal design application in public transportation services thuscreating inconvenience and difficult transfers at transportation system connections. The study recommendsthat universal design application in Nairobi city's public transport needs to consider social inclusiveness andstrengthen the urban planning agenda.Adaptation of Swahili Architecture and Identity: A Case Study of Lamu Island is the ninth paper in thisthirteenth edition. The author questions cultural identity and the resulting material culture of the Swahili peoplein Lamu. This exploration reveals that the cultural identity of Lamu has a history firmly rooted in hybridisationand transculturation. A comparative analysis of four housing typologies demonstrates that the stone housesare characterised by variations and adjustments of an otherwise expected model; adapted to meet the dynamicfunctions as the town grew with irresolute precepts. The paper recommends that in the phase of a modernisingLamu, it is thus not necessary to limit cultural identity to physical forms, aesthetics, materials and textures.Appraisal of Human-Centred Design as a Public Health Tool: Curbing the Incidence of Lifestyle Diseases inKenya paper argues that cost-effective and feasible preventive actions for lifestyle diseases in Kenya, throughthe use of HCD in designing health programmes, will possibly help avert potentially catastrophic costs forcommunities through primordial prevention. The paper observes that designing a successful health interventioncan increase access and uptake of health care and services prompting behaviour change and equally improvingexpected health outcomes

Organochlorine pesticides in rain, rivers and groundwater in the Lake Naivasha basin and implications for their management

Organochlorines (OCs) have a high persistence in the environment and toxicity to humans and wildlife. Despite their ban in several countries, they are still found in agricultural areas. Their presence in drinking water resources (rivers, rain and groundwater) in Lake Naivasha area, which has had a booming horticultural industry in the last three decades was investigated. Twenty-two water samples from the rift floor around Lake Naivasha were collected in June 2017 and analysed for organochlorines. Findings show that all the water samples are contaminated with various organochlorine pesticides and metabolites. The abundance of OCs in water resources can be ranked as follows, rain> river >groundwater in which 18 compounds were identified; alpha, beta, gamma and delta HCH, endrin, aldrin, heptachlor, chlordane, b-endosulfan, methoxychlor, p,p′-DDE, p,p′-DDD, endrin aldehyde, endosulphan sulphate, p,p′-DD and endrin ketone. Their concentrations range from 0.1 to1 μg/L. The OCs with high concentrations are aldrin, endrin aldehyde and endosulphan sulphate. Twelve banned compounds were found present, several decades after their ban (1986 - 2014) shows either occasional usage in the region or the residues drift from use elsewhere. Despite the low concentrations, many of these pollutants can exceed acceptable daily intake (ADI) for humans. Thus, the National Environment Management Authority, Kenya needs to set OCs guidelines on drinking water quality and concerted efforts with agriculture, water and health ministries is needed to ensure public health safety

Advancing understanding and modeling of climate processes for provision of deterministic climate information for sustainable development in Kenya and Eastern Africa

The implications of climate variability and emerging climate change make East Africa particularly vulnerable region due to dependence of most socio-economic activities on highly variable climatic variables like rainfall which has relatively low predictability. Dynamical climate modelling for both operational climate information services like seasonal outlooks, and long-term projections has made notable improvements since 1990s. Models are the only tools for projecting the long-term future climate alongside provision of short-term information for planning and management of climate sensitive socio-economic activities like rain-fed agriculture and water resources. Using rainfall and moist circulation evaluation results, this study illustrates the “UM HadGEM-GC2” model give good indications of processes which quantify climate extremes namely floods and droughts over East Africa. Among the most important processes revealed in this study, vertically integrated moisture flux, which embraces both horizontal moisture transport into or out of East Africa with sufficient moist-air depth or dry atmospheric column are crucial mechanisms for occurrence of floods and droughts in Kenya and East Africa. Knowledge products like these can translate into mitigation and adaptation decisions in water resources, agriculture and food security. To model developers, processed based model evaluation outcomes like these reveals what physics and dynamics attributes to focus on in the formulation of next generation models and development of evaluation metrics