Inhibition effect of butan-1-ol on the corrosion behavior of austenitic stainless steel (Type 304) in dilute sulfuric acid

The electrochemical behavior of austenitic stainless steel (Type 304) in 3 M sulfuric acid with 3.5% recrystallized sodium chloride at specific concentrations of butan-1-ol was investigated with the aid of potentiodynamic polarization, open circuit measurement and weight loss technique. Butan-1-ol effectively inhibited the steel corrosion with a maximum inhibition efficiency of 78.7% from weight-loss analysis and 80.9% from potentiodynamic polarization test at highest concentration studied. Adsorption of the compound obeyed the Freundlich isotherm. Thermodynamic calculations reveal physiochemical interactions and spontaneous adsorption mechanism. Surface characterizations showed the absence of corrosion products and topographic modifications of the steel. Statistical analysis depicts the overwhelming influence and statistical significance of inhibitor concentration on the inhibition performance.     

Geological influence on the activity concentration of terrestrial radionuclides 226Ra, 232Th and 40K in the Jos Plateau,Nigeria

The Jos Plateau has been reported to have elevated levels of natural background radiation. A few earlier studies have measured the levels of natural radioactivity for specific locations in the area. Our interest is to investigate how geology of the study area influences the activity concentrations of natural radionuclides. Thus, the activity concentrations of terrestrial radionuclides in soil samples collected across the geological formations of the Jos Plateau were determined by gamma spectrometry technique. The mean activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were found to exceed their corresponding world reference values of 35, 40 and 400?Bq?kg^?1, respectively. Data were compared using statistical methods, analysis of variance (ANOVA) and post hoc tests. The results revealed in some instances significant influences of geological types on the activity concentrations in the area. The spatial distribution maps of activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were geostatistically interpolated by ordinary Kriging method using ArcGIS software.     

Domestic petroleum-related expertise utilization and Nigeria's oil industry survival: A multicriteria decision analysis

Despite Nigeria's current economic crisis and the need to remove control structures which were originally designed to protect national interest so as to attract foreign investment in upstream activities of its oil sector, the notion of an indigenously controlled oil sector is still alive in the country. The current paper utilizes a multiperiod goal programming model to examine the effect the enforcement of Nigeria's Petroleum Decree on the utilization of domestic petroleum-related expertise would have on the survival of the multinational oil companies and, therefore, of the oil industry. The results indicate that there are some benefits to the nation in enforcing the Decree, but that to do so now will trigger a chain of events that will culminate in the demise of the oil industry. The results also highlight the danger in using legislation to regulate strategic industries and the role operational researchers can play in public policy design and decisions in the future.     

Effect of non‐normality on the power in analysis of variance: A simulation study

The use of simulation methods for calculating the power values in the case of non‐normal errors is discussed. One and two‐way layouts are considered for the fixed effect model. The Erlangian and contaminated normal distribution are taken as examples of a non‐normal error distribution. The results obtained by these methods are given in tables 1 and 2 which indicate that for inference concerning means the power calculated under normal theory is only slightly affected by the non‐normality of the errors.     

Natural radionuclides and hazards of rock samples collected from Southeastern Nigeria

Gamma radiation from natural radionuclides in thirty eight rock samples collected from Southeastern Nigeria was measured using gamma-ray spectrometry method. The activity concentrations varied from 13.1 ± 1.6 Bq kg⁻¹ (ferrogeneisis shale) to 129 ± 38 Bq kg⁻¹ (granite) for ²²⁶Ra, 42.4 ± 4.5 Bq kg⁻¹ (siltstone) to 150 ± 23 Bq kg⁻¹ (pegmatite) for ²³²Th and 64.5 ± 6.3 Bq kg⁻¹ (ferrogeneisis shale) to 882 ± 298 Bq kg⁻¹ (granite) for ⁴⁰K. Hazard indices were used to determine the suitability of the rock samples for building in the context of radiological hazard. The results obtained for the radium equivalent activity and the external hazard index show that two of the samples, granite and pegmatite exceeded the recommended limits of 370 Bq kg⁻¹ and 1, respectively. However the results of the gamma index were below the recommended limit. The dose rates and the annual effective dose calculated ranged from 0.012 to 0.042 μGy h⁻¹ and 0.06–0.21 mSv, respectively.     

LC-MS analysis of oils of Monodora myristica and Monodora tenuifolia and isolation of a novel cyclopropane fatty acid

Abstract

Seeds of Monodora myristica and M. tenuifolia were extracted with hexane and the extracts were subjected to column chromatography, LC-MS and NMR analysis. In addition to masses of previously isolated compounds, other masses corresponding to unidentified compounds from the plants were detected. Using 2?D NMR techniques, one of the fractions from M. tenuifolia was characterised as a novel 13-(2-butylcyclopropyl)-6,9-dodecadienoic acid. However, none of the compounds detected in LC-MS corresponded to the ones previously identified by GC-MS.     

Evaluation of radiological hazards in the sediments of Ogun river, South-Western Nigeria

The concentrations of natural radionuclides in the sediments of Ogun river in South Western Nigeria have been measured and determined using gamma-ray spectrometry. The mean activity concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th at different locations along the course of the river were found to vary from 370.99±19.26 Bq/kg (at Olopade) to 608.02±24.66 Bq/kg (at Owere), 5.57±2.34 (at Ekerin) to 20.40±4.52 Bq/kg (at Sokori) and 5.04±2.24 Bq/kg (at mile 12-Maidan) to 23.10±4.81 Bq/kg (at Sokori) respectively. The overall calculated mean of the total indoor absorbed dose rates was 64.46±9.16 nGy/h with corresponding annual indoor effective dose of 0.32±0.05 mSv/y. Radium equivalent activity (Ra_eq), external hazard index (H_ex), internal hazard index (H_in) and representative gamma index (I_γr) were calculated in order to assess the radiation hazards associated with the use of these sediments in the construction of dwellings. The overall estimated values for the radium equivalent activity, external hazard index, internal hazard index and the representative gamma index were 67.96±10.74 Bq/kg, 0.18±0.03, 0.22±0.05 and 0.54±0.08, respectively. These values obtained for the river sediments were less than the recommended safe and criterion limits by UNSCEAR and also, they compared well with the values from other countries of normal radiation areas. It suffices to say therefore that sediments from Ogun river are safe and can be used for construction of buildings without undue radiological health concerns. Results of the study could serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.     

Modulatory role of Acacia honey from north-west Nigeria on sodium arsenite-induced clastogenicity and oxidative stress in male Wistar rats

Effect of Acacia honey from north-west Nigeria on sodium arsenite-induced oxidative damage and clastogenicity in male Wistar rats was investigated. Animals were divided into four groups and were treated daily via oral gavage for one week before they were sacrificed. Brain, liver and blood serum were collected for antioxidant and protein assays. Clastogenicity, in vitro antioxidant activity, vitamins and minerals were also evaluated. From the results, co-administration of Acacia honey with sodium arsenite on the animals increased (P < 0.05) glutathione peroxidase, superoxide dismutase and catalase activities with concomitant decrease in malondialdehyde levels and anti-clastogenic effects relative to the group treated with sodium arsenite only. The honey possesses reducing power, high hydrogen peroxide scavenging activity, good amount of vitamins (A, C and E), flavonoids (5.08 ± 0.92 mg QE/100 g) and phenolics (5.40 ± 0.69 mg GAE/100 g). The minerals present include zinc, iron, sodium, magnesium, potassium and calcium. In conclusion, Acacia honey from Nigeria may mitigate oxidative stress and clastogenicity.     

A study of dissolution kinetics of a Nigerian galena ore in hydrochloric acid

The results of experimental investigation on the study of dissolution kinetics of a Nigerian galena ore in hydrochloric acid solution were discussed. The influence of acid concentration, temperature, particle size, stirring speed and solid/liquid ratio on the extent of dissolution was examined. The elemental analysis by XRF showed that the galena ore is composed mainly of PbS with metals such as Sn, Fe and Zn occurring as minor elements and Mn, Rb, Sr and Nb as traces. The XRD analysis indicated galena as the dominant mineral phase, with the presence of associated minerals, such as α-quartz (SiO₂), sphalerite (ZnS), cassiterite (SnO₂), pyrite (FeS₂) and manganese oxide (MnO₂).Results of leaching studies showed that galena dissolution in HCl solution increases with increasing acid concentration and temperature; while it decreases with particle diameter and solid/liquid ratio at a fixed stirring rate of 450 rpm. The study showed that 94.8% of galena was dissolved by 8.06 M HCl at 80 °C within 120 min with initial solid/liquid ratio of 10 g/L. The corresponding activation energy, E_a was calculated to be 38.74 kJ/mol. Other parameters such as reaction order, Arrhenius constants, reaction and dissociation constants were calculated to be 0.28, 73.69 s^?1, 1.73 ± 0.13 × 10³ and 1.37 ± 0.024 × 10⁴ mol L^?1 s^?1, respectively. The mechanism of dissolution of galena was established to follow the shrinking core model for the diffusion controlled mechanism with surface chemical reaction as the rate controlling step for the dissolution process. Finally, the XRD analysis of the post-leaching residue showed the presence of elemental sulphur, lead chloride and α-quartz.