21 research outputs found

    Determinants of stock market development in Nigeria using error correction model approach

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    Harnessing economic resources for national development is a major goal of governments; the stock market provides the medium through which funds could be mobilized and allocated for investments for development. This study sought to examine empirically whether stock market liquidity, savings rate, investment ratio, and foreign direct investment (FDI) were determinants of stock market development in Nigeria from 1970-2007. Using secondary data from the Central Bank of Nigeria Statistical Bulletin, 2007, and adopting co-integration and error correction mechanism (ECM), we found that stock market liquidity, savings rate, and one-period lagged stock market development were significant predictors of stock market development in Nigeria. It implies that improving liquidity of the market would impact the stock market; more domestic firms should be encouraged to enlist in the market and Nigerian businessmen abroad should enlist their  companies in their home stock market to increase liquidity in the market

    Investigating the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints

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    This study reports on the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints. Titanium white oil paint exists in a multitude of different recipes, and the effect of the formulation on photocatalytic binder degradation kinetics is unknown. These formulations contain, among others, one or both titanium dioxide polymorphs, zinc oxide, the extenders barium sulfate or calcium carbonate and various additives. Most research performed on the photocatalytic degradation process focusses on pure titanium white-binder mixtures and thus does not take into account the complete paint system. Since photocatalytic oil degradation is a process initiated by the absorption of UV light, any ingredient or combination of ingredients influencing the light scattering and absorption properties of the paint films may affect the degradation rate. In this study three sets of experiments are conducted, designed using the design of experiments (DoE) approach, to screen for the most important formulation factors influencing the degradation rate. The benefits of using DoE, compared to a more traditional ‘one factor at a time approach’ are robustness, sample efficiency, the ability of evaluate mixtures of multiple components as well as the ability to evaluate factor interactions. The three sets of experiments investigate (1) the influence of the TiO2 type, (2) the impact of different mixtures of two types of TiO2, ZnO and the additive aluminum stearate and (3) the influence of common extenders in combination with photocatalytic TiO2, on the photocatalytic degradation of the oil binder. The impact of the formulation on the degradation rate became apparent, indicating the shortcoming of oversimplified studies. The protective effect of photostable TiO2 pigments, even in a mixture with photocatalytic TiO2 pigments, as well as the negative effect of extenders was demonstrated. Furthermore, the ambiguous role of ZnO (photocatalytic or not) and aluminum stearate is highlighted. Neither can be ignored in a study of degradation behavior of modern oil paints and require further investigation

    Changes in Serum Markers of Atherogenesis and Hematological Profile after the consumption of Quail eggs

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    Previous studies suggest that diets with more eggs than is recommended may be used as part of a healthy diet in some countries. However, whether quail egg diets could form part of such diet has not been explored. The aim of the present study is to evaluate the effect of quail egg consumption on serum markers of atherogenesis and hematological parameters in healthy volunteers. Thirty adult subjects participated in this study after ascertaining their baseline health status. They were fed 3 eggs per day and 8hourlyfor 30 days. They were evaluated for serum levels of cholesterol sub-fractions, AIP and hematological parameters at days 0, 10 and 30 after the consumption of quail eggs. At day10, serum levels of cholesterol sub-fractions (TG, HDL-C and LDL-C) were not significantly (p>0.05) different from the corresponding values at baseline. Serum levels of VLDL-C and calculated AIP significantly (p<0.05) decreased compared to the levels at baseline. At day 30, serum levels of HDL-C, TG and VLDL-C significantly (p<0.05) increased, while LDL-C and AIP significantly decreased. Also, total RBC, HB, PCV, MCV, MCH and MCHC were not significantly different from the levels at baseline. At day 30, RBC, PCV and HB significantly (p<0.05) increased compared to the levels at baseline, while MCV, MCH and MCHC were not significantly (p>0.05) different from the baseline values. Indeed, long-term consumption of quail egg may be associated with improvement in serum markers of atherogenesis and hematological parameters due to its varied nutrient constituents and their activities

    Molecular and functional characterization of cDNAs putatively encoding carboxylesterases from the migratory locust, Locusta migratoria

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    Citation: Zhang J, Li D, Ge P, Guo Y, Zhu KY, et al. (2014) Molecular and Functional Characterization of cDNAs Putatively Encoding Carboxylesterases from the Migratory Locust, Locusta migratoria. PLoS ONE 9(4): e94809. doi:10.1371/journal.pone.0094809Carboxylesterases (CarEs) belong to a superfamily of metabolic enzymes encoded by a number of genes and are widely distributed in microbes, plants and animals including insects. These enzymes play important roles in detoxification of insecticides and other xenobiotics, degradation of pheromones, regulation of neurodevelopment, and control of animal development. In this study, we characterized a total of 39 full-length cDNAs putatively encoding different CarEs from the migratory locust, Locusta migratoria, one of the most severe insect pests in many regions of the world, and evaluated the role of four CarE genes in insecticide detoxification. Our phylogenetic analysis grouped the 39 CarEs into five different clades including 20 CarEs in clade A, 3 in D, 13 in E, 1 in F and 2 in I. Four CarE genes (LmCesA3, LmCesA20, LmCesD1, LmCesE1), representing three different clades (A, D and E), were selected for further analyses. The transcripts of the four genes were detectable in all the developmental stages and tissues examined. LmCesA3 and LmCesE1 were mainly expressed in the fat bodies and Malpighian tubules, whereas LmCesA20 and LmCesD1 were predominately expressed in the muscles and hemolymph, respectively. The injection of double-stranded RNA (dsRNA) synthesized from each of the four CarE genes followed by the bioassay with each of four insecticides (chlorpyrifos, malathion, carbaryl and deltamethrin) increased the nymphal mortalities by 37.2 and 28.4% in response to malathion after LmCesA20 and LmCesE1 were silenced, respectively. Thus, we proposed that both LmCesA20 and LmCesE1 played an important role in detoxification of malathion in the locust. These results are expected to help researchers reveal the characteristics of diverse CarEs and assess the risk of insecticide resistance conferred by CarEs in the locust and other insect species
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