EFFECT OF PROCESS-RELATED PARAMETERS ON BAND GAP OF ELECTROPHORETICALLY DEPOSITED TIO2NB2O5 COMPOSITE THIN FILMS

Nano-crystalline composite thin films of titanium dioxide and niobium (v) oxide (TiO2/Nb2O5 ) were successfully deposited on fluorine-doped tin oxide (FTO) coated glass substrate using electrophoretic deposition (EPD) technique. The colloidal suspension utilized in EPD cell consisted of mixture of TiO2 and Nb2O5 nanopowders and 2-propanol in a Pyrex glass. Values of potential difference (25 to 60V) were applied across the EPD electrodes placed in a parallel configuration 1.2cm apart and partially immersed in the suspension. The optimization of EPD parameters was achieved from transmittance measurements and band gap energy calculations. Both Nb2O5 and TiO2 nanoparticles were seen in XRD graphs to be present in the composite films in the ratio 1 to 1.78 which confirmed that both type of nanoparticles suspended in 2-propanol developed positive surface charges and were moved towards and deposited on the cathode upon application of an electric field. The band gap energy was evaluated for films deposited from varied EPD process-related parameters namely, concentration, deposition times and applied potential. The maximum values of band gap were obtained for films electrophoretically deposited from particle concentration of 0.01g/40mL (or 0.25g/L), applied voltage of 35V, and deposition time of 90s. These values of EPD process-related parameters formed the optimum values for deposition of crack free films of good porosity. The changes in band gap values are attributed to either energy shift of conduction band or valence band energy levels. The TiO2/Nb2O5 composite thin films, fabricated in this study from optimized parameters of EPD technique had smooth morphology as shown by SEM images. Further work is needed to evaluate the potential of TiO2/Nb2O5 composite films deposited by EPD for dye–sensitized solar cell application.Keywords: Electrophoretic deposition (EPD), TiO2/Nb2O5 composite thin films, PV applications, Solar energy, Optical band ga

Capital Structure, Firm Efficiency and Firm Value: The Case of Listed Non-Financial Firms in Kenya

This study examined the influence of a firm’s efficiency on the relationship between capital structure and firm value. The study analyzed thirty non – financial firms listed at the Nairobi Securities Exchange for a period of six years from   2008 to 2013.Capital structure was parameterized as the ratio of retained earnings to total capital, ratio of debt to total capital and ratio of equity to total capital of the firm. Efficiency is measured as the distance from the best practice frontier in the industry. The firm’s efficiency is measured by operational efficiency, cost efficiency and profit efficiency. Firm value is measured by its inputs and outputs. The inputs to the firms production are financing costs (FINC), distribution costs (DISTC), tax liability (TAX), and administrative expenses (ADEXP). The outputs are earnings per share(EPS)and the share price (SP).This study applied panel data analysis using fixed effects model. The results showed that cost efficiency negatively influences the relationship between capital structure and firm value as measured by the SP through increase in distribution costs, administrative costs in financing efficiency improvements in the firm’s core processes. Further Operating efficiency negatively and statistically significantly affects the relationship between firm value and capital structure through the increase in financing costs, distribution costs, administration costs and taxation costs. The results showed that profit efficiency negatively and insignificantly influences the relationship between capital structure and firm value as measured by the SP. Consequently it has a positive but statistically insignificant effect on financing costs, distribution costs, administrative costs and taxation costs. Moreover, capital structure has a positive and statistically significant effect on firm value but firm efficiency insignificantly influences the relationship between capital structure and firm value. This study does not investigate the reverse relationship like Margaritis and Psillaki (2007). Keywords: Capital Structure, Firm Efficiency, Firm Value, Listed Non-Financial Firms, Nairobi Securities Exchang

Using a value chain framework for food safety assessment of edible offals in Nairobi, Kenya

Edible offals comprise those parts of the animal considered fit for human consumption apart from the skeletal muscle, fat and attached skin. Edible offals form an important source of affordable animal protein and a delicacy for the larger Kenyan market. The offals are mainly traded in the informal markets which supplies at least 80% of the domestic market and where hygiene levels are low. The Meat Control Act Chapter 356, Laws of Kenya (Revised 2012) requires that offals be obtained from an officially declared food animal that has been slaughtered in a licensed slaughterhouse and declared fit for human consumption. According to the Meat Control Act, slaughterhouses in Kenya are classified as either export or local. The latter is subdivided into categories A, B, and C depending on their daily capacity, land size and the area they are authorized to supply meat and meat products. Each export slaughterhouse, category A and B slaughterhouses require a minimum of three meat inspectors to carry out inspection of carcasses and offals. The Directorate of Veterinary Services is the main regulator in Kenya on matters concerning safety of meat at the slaughterhouses. The Director of Veterinary Services appoints meat inspectors and veterinary officers who are responsible for ascertaining the safety of meat and meat products from the slaughterhouses. The meat inspectors also verify that slaughter facilities, staff, processes and equipment conform to food safety requirements. Offals, like carcass meat, should be handled under utmost hygiene conditions to minimize contamination or excessive growth of microorganisms. The current practices in slaughterhouses is that each set of edible offals is packaged separately in either polythene bags, plastic containers, meat transport containers or carriers and dispatched to the market. In some instances, stomachs and intestines are packaged for dispatch together with the lungs and hearts for transportation to distances over 50 km in either refrigerated or non-refrigerated containers or carriers. Some of these practices could compromise the safety of the offals. In this paper, we review the challenges faced in maintaining safety of edible offals especially at the slaughterhouses, distributors and retailers level from regulators' point of view

ANTIINFLAMMATORY PROPERTIES OF DICHLOROMETHANE: METHANOLIC LEAF EXTRACTS OF CAESALPINIA VOLKENSII AND MAYTENUS OBSCURA IN ANIMAL MODELS

Objective: Inflammation is the reaction to injury of the living tissues. Conventional medication of inflammation is expensive and arguably associated with various severe adverse effects hence the need to develop herbal agents that are effective as alternative. Caesalpinia volkensii and Maytenus obscura are plants that grow in Mbeere County of Eastern region of Kenya. This study was designed to evaluate the anti-inflammatory activity of C. volkensii and M. obscura plants. Methods: Experimental animals were divided in to four groups; normal group, diseased negative control group, diseased reference group and diseased experimental groups. Inflammation was inducted into the mice using carrageenan. The experimental groups were treated with leaf extracts of the plants at concentration of 50 mg/kg, 100 mg/kg and 150 mg/kg. Anti-inflammatory activities in rats were compared with diclofenac (15 mg/kg) as the standard conventional drug. Results: The leaf extracts of C. volkensii reduced the paw edema by between 6.50%-13.42% while the extracts of M. obscura reduced it by between 4.94%-22.36%. Diclofenac reduced the paw edema by between 4.11%-10.47%. Conclusion: The phytochemical screening results showed that the extracts of C. volkensii had flavonoids, steroids and phenolics while the leaf extracts M. obscura had phenolics, terpenoids and saponins. Flavonoids, saponins and phenolics have been associated with anti-inflammatory activities. Therefore, the study has established that the DCM: methanolic leaf extracts of Caesalpinia volkensii and Maytenus obscura are effective in management of inflammation

Access and barriers to measures targeted to prevent malaria in pregnancy in rural Kenya*

OBJECTIVES: To evaluate barriers preventing pregnant women from using insecticide-treated nets (ITN) and intermittent presumptive treatment (IPT) with sulphadoxine-pyrimethamine (SP) 5 years after the launch of the national malaria strategy promoting these measures in Kenya. METHODS: All women aged 15-49 years were interviewed during a community survey in four districts between December 2006 and January 2007. Women pregnant in the last 12 months were asked about their age, parity, education, use of nets, ITN, antenatal care (ANC) services and sulphadoxine-pyrimethamine (SP) (overall and for IPT) during pregnancy. Homestead assets were recorded and used to develop a wealth index. Travel time to ANC clinics was computed using a geographic information system algorithm. Predictors of net and IPT use were defined using multivariate logistic regression. RESULTS: Overall 68% of pregnant women used a net; 52% used an ITN; 84% attended an ANC clinic at least once and 74% at least twice. Fifty-three percent of women took at least one dose of IPT-SP, however only 22% took two or more doses. Women from the least poor homesteads (OR = 2.53, 1.36-4.68) and those who used IPT services (OR = 1.73, 1.24-2.42) were more likely to sleep under any net. Women who used IPT were more likely to use ITNs (OR = 1.35, 1.03-1.77), while those who lived more than an hour from an ANC clinic were less likely (OR = 0.61, 0.46-0.81) to use ITN. Women with formal education (1.47, 1.01-2.17) and those who used ITN (OR: 1.68, 1.20-2.36) were more likely to have received at least one dose of IPT-SP. CONCLUSION: Although the use of ITN had increased 10-fold and the use of IPT fourfold since last measured in 2001, coverage remains low. Provider practices in the delivery of protective measures against malaria must change, supported by community awareness campaigns on the importance of mothers' use of IPT

A Randomized Controlled Trial of Folate Supplementation When Treating Malaria in Pregnancy with Sulfadoxine-Pyrimethamine

OBJECTIVES: Sulfadoxine-pyrimethamine (SP) is an antimalarial drug that acts on the folate metabolism of the malaria parasite. We investigated whether folate (FA) supplementation in a high or a low dose affects the efficacy of SP for the treatment of uncomplicated malaria in pregnant women. DESIGN: This was a randomized, placebo-controlled, double-blind trial. SETTING: The trial was carried out at three hospitals in western Kenya. PARTICIPANTS: The participants were 488 pregnant women presenting at their first antenatal visit with uncomplicated malaria parasitaemia (density of ≥ 500 parasites/μl), a haemoglobin level higher than 7 g/dl, a gestational age between 17 and 34 weeks, and no history of antimalarial or FA use, or sulfa allergy. A total of 415 women completed the study. INTERVENTIONS: All participants received SP and iron supplementation. They were randomized to the following arms: FA 5 mg, FA 0.4 mg, or FA placebo. After 14 days, all participants continued with FA 5 mg daily as per national guidelines. Participants were followed at days 2, 3, 7, 14, 21, and 28 or until treatment failure. OUTCOME MEASURES: The outcomes were SP failure rate and change in haemoglobin at day 14. RESULTS: The proportion of treatment failure at day 14 was 13.9% (19/137) in the placebo group, 14.5% (20/138) in the FA 0.4 mg arm (adjusted hazard ratio [AHR], 1.07; 98.7% confidence interval [CI], 0.48 to 2.37; p = 0.8), and 27.1% (38/140) in the FA 5 mg arm (AHR, 2.19; 98.7% CI, 1.09 to 4.40; p = 0.005). The haemoglobin levels at day 14 were not different relative to placebo (mean difference for FA 5 mg, 0.17 g/dl; 98.7% CI, −0.19 to 0.52; and for FA 0.4 mg, 0.14 g/dl; 98.7% CI, −0.21 to 0.49). CONCLUSIONS: Concomitant use of 5 mg FA supplementation compromises the efficacy of SP for the treatment of uncomplicated malaria in pregnant women. Countries that use SP for treatment or prevention of malaria in pregnancy need to evaluate their antenatal policy on timing or dose of FA supplementation

Design of a study to determine the impact of insecticide resistance on malaria vector control: a multi-country investigation.

BACKGROUND: Progress in reducing the malaria disease burden through the substantial scale up of insecticide-based vector control in recent years could be reversed by the widespread emergence of insecticide resistance. The impact of insecticide resistance on the protective effectiveness of insecticide-treated nets (ITN) and indoor residual spraying (IRS) is not known. A multi-country study was undertaken in Sudan, Kenya, India, Cameroon and Benin to quantify the potential loss of epidemiological effectiveness of ITNs and IRS due to decreased susceptibility of malaria vectors to insecticides. The design of the study is described in this paper. METHODS: Malaria disease incidence rates by active case detection in cohorts of children, and indicators of insecticide resistance in local vectors were monitored in each of approximately 300 separate locations (clusters) with high coverage of malaria vector control over multiple malaria seasons. Phenotypic and genotypic resistance was assessed annually. In two countries, Sudan and India, clusters were randomly assigned to receive universal coverage of ITNs only, or universal coverage of ITNs combined with high coverage of IRS. Association between malaria incidence and insecticide resistance, and protective effectiveness of vector control methods and insecticide resistance were estimated, respectively. RESULTS: Cohorts have been set up in all five countries, and phenotypic resistance data have been collected in all clusters. In Sudan, Kenya, Cameroon and Benin data collection is due to be completed in 2015. In India data collection will be completed in 2016. DISCUSSION: The paper discusses challenges faced in the design and execution of the study, the analysis plan, the strengths and weaknesses, and the possible alternatives to the chosen study design

Plasmodium falciparum transmission and aridity: a Kenyan experience from the dry lands of Baringo and its implications for Anopheles arabiensis control

<p>Abstract</p> <p>Background</p> <p>The ecology of malaria vectors particularly in semi-arid areas of Africa is poorly understood. Accurate knowledge on this subject will boost current efforts to reduce the burden of malaria in sub-Saharan Africa. The objective of this study was to describe the dynamics of malaria transmission in two model semi-arid sites (Kamarimar and Tirion) in Baringo in Kenya.</p> <p>Methods</p> <p>Adult mosquitoes were collected indoors by pyrethrum spray collections (PSC) and outdoors by Centers for Disease Control (CDC) light traps and identified to species by morphological characteristics. Sibling species of <it>Anopheles gambiae </it>complex were further characterized by rDNA. PCR and enzyme-linked immuno-sorbent assays (ELISA) were used to test for <it>Plasmodium falciparum </it>circumsporozoite proteins and host blood meal sources respectively.</p> <p>Results</p> <p><it>Anopheles arabiensis </it>was not only the most dominant mosquito species in both study sites but also the only sibling species of <it>An. gambiae s.l. </it>present in the area. Other species identified in the study area were <it>Anopheles funestus</it>, <it>Anopheles pharoensis </it>and <it>Anopheles coustani</it>. For Kamarimar but not Tirion, the human blood index (HBI) for light trap samples was significantly higher than for PSC samples (Kamarimar, 0.63 and 0.11, Tirion, 0.48 and 0.43). The HBI for light trap samples was significantly higher in Kamarimar than in Tirion while that of PSC samples was significantly higher in Tirion than in Kamarimar. Entomological inoculation rates (EIR) were only detected for one month in Kamarimar and 3 months in Tirion. The number of houses in a homestead, number of people sleeping in the house, quality of the house, presence or absence of domestic animals, and distance to the animal shelter and the nearest larval habitat were significant predictors of <it>An. arabiensis </it>occurrence.</p> <p>Conclusion</p> <p>Malaria transmission in the study area is seasonal with <it>An. arabiensis </it>as the dominant vector. The fact this species feeds readily on humans and domestic animals suggest that zooprophylaxis may be a plausible malaria control strategy in semi-arid areas of Africa. The results also suggest that certain household characteristics may increase the risk of malaria transmission.</p

A Randomized Placebo-Controlled Trial of Intermittent Preventive Treatment in Pregnant Women in the Context of Insecticide Treated Nets Delivered through the Antenatal Clinic

Background:Current recommendations to prevent malaria in African pregnant women rely on insecticide treated nets(ITNs) and intermittent preventive treatment (IPTp). However, there is no information on the safety and efficacy of theircombined use.Methods:1030 pregnant Mozambican women of all gravidities received a long-lasting ITN during antenatal clinic (ANC)visits and, irrespective of HIV status, were enrolled in a randomised, double blind, placebo-controlled trial, to assess thesafety and efficacy of 2-dose sulphadoxine-pyrimethamine (SP). The main outcome was the reduction in low birth weight.Findings:Two-dose SP was safe and well tolerated, but was not associated with reductions in anaemia prevalence atdelivery (RR, 0.92 [95% CI, 0.79-1.08]), low birth weight (RR, 0.99 [95% CI, 0.70-1.39]), or overall placental infection(p = 0.964). However, the SP group showed a 40% reduction (95% CI, 7.40-61.20]; p = 0.020) in the incidence of clinicalmalaria during pregnancy, and reductions in the prevalence of peripheral parasitaemia (7.10% vs 15.15%) (p,0.001), and ofactively infected placentas (7.04% vs 13.60%) (p = 0.002). There was a reduction in severe anaemia at delivery of borderlinestatistical significance (p = 0.055). These effects were not modified by gravidity or HIV status. Reported ITN's use was morethan 90% in both groups.Conclusions:Two-dose SP was associated with a reduction in some indicators, but these were not translated to significantimprovement in other maternal or birth outcomes. The use of ITNs during pregnancy may reduce the need to administerIPTp. ITNs should be part of the ANC package in sub-Saharan Afric