Phytochemical screening and antibacterial activity of Centaurea senegalensis growing in Nigeria

The increasing prevalence of drug resistant pathogens in developing countries has necessitated research for effective therapeutic agents from plants. This study was designed to evaluate the antibacterial properties of Centaurea senegalensis and investigate the phytochemical constituents. The plant sample was extracted using methanol and subjected to successive partition with n-hexane, dichloromethane and ethyl acetate. The methanol extract (ME), hexane (HF), dichloromethane (DF) and ethylacetate (EF) fractions were subjected to antibacterial screening on selected gram-positive and gram-negative bacteria using agar well and micro broth dilution methods. The antibacterial efficacies of extracts showed varying zones of growth inhibitions (15-31 mm). The DF fraction was effective on Methicillin resistant Staphylococcus aureus (MRSA), and Vancomycin resistant enterococci (VRE) with interesting activity (28 mm, MIC 12.5 mgmL-1). However, the EF was most effective fraction against gram-negative bacteria such as Escherichia coli (31 mm, MIC, 12.5 mgmL-1). Chemical composition of bioactive fraction was determined using gas chromatography-mass spectrometry (GC-MS). The compounds detected were largely natural acetylenes such as 1, 5-heptadien-3-yne (23.2%), 2-hexyne-1-ol (12.3%), 2-methyl-1,5-hexadien-3-yne (6.6%) and 5-methyl-1-hexyn-3-ol (2.1%) as most abundant phytoconstituents identified. C. senegalensis fractions have demonstrated effective activity on both gram-positive and gram-negative bacteria, which might be attributed to acetylene derived natural compounds. Our findings have shown the importance of C. senegalensis as source of chemical compounds with effective antibacterial properties.Keywords: Centaurea senegalensis, phytochemical screening, antibacterial activity, GC-M

Total petroleum hydrocarbon content in surface water and sediment of Qua-Iboe River, Ibeno, Akwa-Ibom State, Nigeria

The total petroleum hydrocarbon content in surface water and sediment of Qua Iboe River, Akwa Ibom State, Nigeria was assessed by randomly collecting samples from five sampling points of the study area and from a control site. The samples were extracted with dichloromethane (DCM) by liquid-liquid partition for water and Soxhlet extraction for sediments followed by subsequent clean up on column chromatography and analyzed by gas chromatography-flame ionization detection (GC-FID) for the determination of total petroleum hydrocarbons (TPH). The results showed variation of total petroleum hydrocarbon (TPH) content from 90 to 250 μg/L in the water and 270 to 830 mg/kg in the sediments, with mean value of 168.33±59.29 μg/L and 606.83±229.48 mg/kg respectively. The average amount of TPH in the water samples collected from all the sampling points was generally lower than the EU standard limit of 300 μg/L. However, the levels in the sediments exceeded the EGASPIN target value (50 mg/kg) for mineral oil but were below the intervention value (5,000 mg/kg), this indicates a serious impact of oil industrial activities on the area. Hence, our findings have indicated evidence that Qua Iboe River is under pollution threat and underscore the need for early remediation if adverse health defects are to be prevented.Keywords: Total petroleum hydrocarbon, GC-FID, surface water, sediment

A reliable strategy for slug flow attenuation in pipeline-riser systems

Oil and gas activities across the globe now take place deep offshore. To operate in this harsh environment, there are numerous challenges. These can be in the form of high cost of production, space constraints, operational and technological demands. The co-transportation of oil and gas in same pipeline is one of the operational and technological approaches adopted in the industry to meet the transportation of produced crude. This approach comes with its attendant flow assurance difficulties. Slugging is one of such problems which can constitute operational hitches resulting in production reduction and sometimes eventual plant shutdown. Existing attenuation techniques are limited in various ways. Therefore, seeking a reliable solution to this problem is highly desired.In this study, an experimental study of multiple techniques for slug attenuation was attempted. A passive device-the intermittent slug absorber, topside choking and topside separator were investigated. The results show that a combination of the methods proves to be more effective compared to individual techniques. A significant reduction in riser- base pressure of up to 39% was achieved. This is advantageous and translates to an increase in oil recovery. Thus, the proposed strategy helps to achieve system stability and improved production at a lower cost

Antifungal Activity of Hyptis spicigera Methanol Leaf Extract and Flavonoid Fraction

Control of plant fungal diseases using synthetic fungicides continue to cause major problems to human health and the entire ecosystem. The aim of this research was to investigate the phytochemical and antifungal properties of Hyptis spicigera methanol leaf extract and flavonoid fraction on Aspergillus and Fusarium species, with a view to uncovering effective bio-fungicides for development as substitutes to chemical fungicides. Phytochemical screening revealed the presence of sterols and triterpenes, cardiac glycosides, flavonoids, tannins and alkaloids. The quantitative analysis showed that saponin (690 mg/g GAE), phenolics (220 mg/g GAE) and flavonoids (140 mg/g GAE) were found to be in high concentration. The antifungal effects of H. spicigera methanol extract on F. graminearum (21 mm) was significantly (p<0.05) higher than the control fungicide (Mancozeb). Similarly, the flavonoid fraction was more effective on A. parasitic (18 mm) than the control fungicide used. The extract and fraction exhibited MIC with range 3.13-12.5 mg/mL and MFC 6.25-12.5 mg/mL, indicating promising antifungal efficacies against A. flavus and F. graminearum. Our findings have revealed that H. spicigera flavonoid rich fraction has potential for development as effective bio-fungicide to control plant fungal diseases of the Aspergillus and Fusarium species

Seroprevalence of Hepatitis B surface antigenaemia among pregnant women attending antenatal clinic at General Hospital Aliero, Kebbi State, Northern-Nigeria

No Abstract

Characteristics of horizontal gas-liquid two-phase flow measurement in a medium-sized pipe using gamma densitometry

Two-phase flows are common occurrences in many industrial applications. The understanding of their characteristics in industrial piping systems is vital for the efficient design, optimization, and operation of industrial processes. Most of the previous experimental studies involving the use of gamma densitometers for holdup measurements in air-water mixtures are limited to smaller diameter pipes (generally regarded as those with < 50 mm in nominal diameter). Further, very few literature report experimental data obtained using gamma desitometers. This paper presents an application of a gamma densitometer in the measurement of two-phase flow characteristics in an intermediate diameter pipe (nominal diameter between 50 mm and 100 mm). Scaled air-water experiments were performed in a 17-m long, 0.0764-m internal diameter horizontal pipe. Liquid superficial velocity ranged between 0.1–0.4 m/s while gas superficial velocity ranged from 0.3 to 10.0 m/s. The measured parameters include liquid holdup, pressure gradient, flow pattern, and slug flow features. The flow patterns observed were stratified, stratified-wavy, plug, slug, and annular flows. Plug and slug flow patterns showed good agreement with established flow pattern maps. Furthermore, the slug translational velocity was observed to increase with increasing mixture velocity, as reported by previous authors, hence establishing the reliability of the instrumentation employed. The slug body length was also measured using the gamma densitometer and was found to be within the range 24–36D with a mean length of 30.6D

Effect of Height Variation for the Determination of Accurate Focal Zone for a Thin Foil L-Shaped Parabolic Reflector

The use of concentrators in forms of solar energy collector in order to concentrate sun rays for better usage is on the increase worldwide. This paper presents the effect of height variations for the determination of accurate focal zone for three different parabolic reflectors. The system was constructed using locally available materials with design parameters. The thermal performance experiments were conducted (water boiling test) to evaluate the performance evaluation of the reflector at different height. The experimental test results showed that the systems when set at 65 cm height from cooking vessel performed better than at 45 cm and 55 cm heights respectively. Similarly the temperature profile of the systems showed highest result of 94.1 oC at a height of 65 cm

An Improved Model for the Prediction of Liquid Loading in gas Wells using Firefly and Particle Swarm Optimization Algorithms

Liquid loading is an undesired phenomenon in gas wells that occurs when producing wells attain a flow rate below which liquid will not be able to flow to the surface. The inability of the energy from the gas to transport the liquid to the surface causes back flow and eventual accumulation of liquid at the wellbore. This is characterised by intermittent flow, which, if left unchecked, can eventually kill the well. An effective and reliable predictive method must therefore, be employed. In this study, improved models based on data set from condensate/water in a gas well were developed by applying firefly (FA) and particle swarm optimisation (PSO) algorithms. The results showed that the model developed out perform many of the existing models. The models predicted liquid loading in gas well at 86% level of accuracy compared to the 81% highest possible from published models. Although, the FA and PSO models predicted liquid loading at higher accuracy compared with Turner and Coleman models for higher wellhead pressure systems, the Coleman model appeared to perform better in the prediction of critical gas rate for low-pressure systems. However, the developed model can significantly improve the prediction of liquid loading in gas wells at a higher reliability and accuracy levels. Thus, the proposed models can be a veritable tool for accurately predicting liquid loading in gas wells