Corrosion resistance of galvanized roofing sheets in acidic and rainwater environments

The galvanization of steel sheets for building roofs and construction of additional structures has been a valued solution to the challenges faced by the deterioration of roofing steel sheets in an unfavourable surroundings. This research was conducted on galvanized roofing sheets obtained from the open market in Nigeria. The samples were cut to a small size (5 cm by 4 cm) and immersed in sulfuric acid (H2SO4) and hydrochloric acid (HCl). As the control medium for the experiment, rainwater was used. The experiment was performed over 1200 hours; each sample was removed every 240 hours, thoroughly washed, dried, and weighed again. Based on the reacting media, variations in the weights of the samples were obtained. According to ASTM G1-03 standard practice, Corrosion rates were calculated for preparing, cleaning, and evaluating corrosion test specimens. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) was also carried out. Although some samples resisted corrosion, other samples corroded. It is predicted that the green-coated samples are more resistant to corrosion in rainwater and H2SO4 and thus more stable

Electrochemical studies of the corrosion inhibition property of Rosmarinus officinalis on mild steel in dilute sulphuric acid

The electrochemical behaviour and corrosion inhibition of mild steel in 0.5M and 1M dilute sulpuric acid by rosemary oil (Rosmarinus officinalis) at ambient temperature was investigated through potentiodynamic polarization test, weight loss techniques analysis and optical microscopy. Results obtained showed the organic compound to be highly effective with a maximum inhibition efficiency of 80.8 % and 87.9% from weight loss and 84.1% and 80.8% from polarization test in the acid test solutions. The adsorption characteristics of the compound obeyed the Langmuir adsorption isotherm while the inhibition mechanism was observed from thermodynamic calculations to be physiochemical. Optical microscopy micrographs confirms the overwhelming influence of the compound on the topography and surface morphology of the steel after exposure

Effects of alloying on aluminium-silicon alloys – a review

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A comparative study on the corrosion behaviour of welded and un-welded API 5L X70 steel in simulated fuel grade ethanol

In a bid to mitigate global warming, fuel grade ethanol (FGE) is being increasingly used in the fuel industry. However, there are material compatibility issues. In this study, the effect of Simulated Fuel Grade Ethanol (SFGE) on welded and un-welded API 5 L X-70 pipeline was investigated via gravimetric technique. Mass loss tests showed that the lowest corrosion rate was recorded in E10, whereas the highest corrosion rate was recorded in E40 environment. Statistical analysis reveals that on the basis of two-factor analysis of variance (ANOVA) test results, exposure time, and ethanol concentration significantly affected the corrosion rates of welded and unwelded X70 steel. Morphological examination revealed increased corrosion with an increase in ethanol concentration for welded X70 steel, which compares well with the results from mass loss tests

Integrated Harvesting Techniques for African Egg Plant (Solanum macrocarpon L., cv. Igbagba)

This study elucidated the influence of harvesting height and frequency on concurrent seed and shoots production of the African Eggplant, Solanum macrocarpon L., cv. Igbagba/Igbo. The overall aim was to use the outcome to make recommendations that would enable African resource poor farmers secure the much needed increase in income for improved livelihoods. The study was carried out between April to November 2004 on the National Horticultural Research Institute (NIHORT) Ibadan, Nigeria commercial vegetable production fields. Result shows that harvesting at 0.08 m above ground level was optimal and significantly highest for leaf, stem, shoot, seed and total yields except at 0.12 m above ground level for seed production. The result of financial profitability analysis shows that harvesting 0.08 m above ground level and fortnightly was most profitable for leaf, shoot and total yields compared to all the treatment combinations. Harvesting 0.12 m above ground level and monthly, however, was most profitable for seed production when compared to all treatments combinations. The study concluded noting that integrated harvesting techniques for shoot (leaf + stem) and seed production proved economically viable and optimize resource use efficiency better than growing S. macrocarpon sole either for shoot or seed

Expression of a recombinant IRP-like Plasmodium falciparum protein that specifically binds putative plasmodial IREs

Plasmodium falciparum iron regulatory-like protein (PfIRPa, accession AJ012289) has homology to a family of iron-responsive element (IRE)-binding proteins (IRPs) found in different species. We have previously demonstrated that erythrocyte P. falciparum PfIRPa binds a mammalian consensus IRE and that the binding activity is regulated by iron status. In the work we now report, we have cloned a C-terminus histidine-tagged PfIRPa and overexpressed it in a bacterial expression system in soluble form capable of binding IREs. To overexpress PfIRPa, we used the T7 promoter-driven vector, pET28a(+), in conjunction with the Rosetta(DE3)pLysS strain of E. coli, which carries extra copies of tRNA genes usually found in organisms such as P. falciparum whose genome is (A+T)-rich. The histidine-tagged recombinant protein (rPfIRPa) in soluble form was partially purified using His-bind resin. We searched the plasmodial database, plasmoDB, to identify sequences capable of forming IRE loops using a specially developed algorithm, and found three plasmodial sequences matching the search criteria. In gel retardation assays, rPfIRPa bound three 32P-labeled putative plasmodial IREs with affinity exceeding the affinity for the mammalian consensus IRE. The binding was concentration-dependent and was not inhibited by heparin, an inhibitor of non-specific binding. Immunodepletion of rPfIRPa resulted in substantial inhibition of the signal intensity in the gel retardation assays and in Western blot-determinations of rPfIRPa protein levels. Endogenous PfIRPa retained all three putative 32P-IREs at the same position on the gel as the recombinant PfIRPa. © 2002 Elsevier Science B.V. All rights reserved

The major genetic determinants of HIV-1 control affect HLA class I peptide presentation.

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection