Computational Study of Ring-Cusp Magnet Configurations that Provide Maximum Electron Confinement

Enhancing the confinement of primary electrons within the plasma in a discharge chamber of an ion thruster improves plasma ionization and consequently the thruster\u27s performance. This work computationally calculates the location, position, and orientation of the permanent magnets that provide a ring-cusp magnetic field that maximizes electron confinement in an axi-symmetric cylindrical aluminum-wall discharge chamber. Small samarium cobalt magnets are circumferentially arranged in a ring around the front, side, or back wall of the chamber. The generated ring-cusp magnetic field for any specified magnet configuration is calculated using MAXWELL2D, a two dimensional electromagnetic field simulation computer code. For various magnet configurations, PRIMA, a particle-in-cell computer code modified by Mahalingam and Menart, is used to model the trajectory of the primary electrons in the magnetic field. The confinement length, the length of time an electron is retained within the chamber, is output by PRIMA, and it is the parameter used to determine the performance of the magnet configurations surveyed. The performance of various magnet ring pairs are studied and guidelines on the location, position, and orientation of the magnet rings are obtained. These guidelines are then combined to give complex ring-cusp magnet ring arrangements on a fixed size discharge chamber. For three complex arrangements having three magnet rings, a decrease in the chambers confinement ability is seen when the applied guidelines are slightly violated. This observed decrease validates the guidelines deduced in this work

Genotypic Characterization of Aminoglycoside Resistance Genes from Bacteria Isolates in Selected Municipal Drinking Water Distribution Sources in Southwestern Nigeria

BACKGROUND: Multi-drug Resistant (MDR) bacteria could lead to treatment failure of infectious diseases and could be transferred by non-potable water. Few studies have investigated occurrence of Antibiotic Resistance Genes (ARGs) among bacteria including Aminoglycoside Modifying Genes (AMGs) from Drinking Water Distribution Systems (DWDS) in Nigeria. Here, we aimed at characterization of AMGs from DWDS from selected states insouthwestern Nigeria.METHODS: One hundred and eighty one (181) MDR bacteria that had been previously characterized using 16S rDNA and showed resistance to at least one aminoglycoside antibiotic were selected from treated and untreated six water distribution systems in southwestern Nigeria. MDR bacteria were PCR genotyped for three AMGs:aph (3´´)c, ant (3´´)b and aph(6)-1dd.RESULTS: Out of 181 MDR bacteria genotyped, 69(38.12%) tested positive for at least one of the genotyped AMGs. Highest (50, 27.62%) detected gene was ant (3”)c followed by aph (3")c(33,18.23%). Combination of aph(3")c and ant (3")b in a single bacteria was observed as the highest (14, 7.73%) among the detected gene combination. Alcaligenes sp showed the highest (10/20) occurrence of ant (3")b while aph(3")c was the highest detected among Proteussp (11/22). Other bacteria that showed the presence of AMGs include: Acinetobacter, Aeromonas, Bordetella, Brevundimonas, Chromobacterium, Klebsiella, Leucobacter, Morganella, Pantoae, Proteus, Providencia, Psychrobacter and Serratia.CONCLUSIONS: High occurrence of ant (3”)c and aph (3”)c among these bacteria call for urgent attention among public health workers, because these genes can be easily disseminated to consumers of these water samples if present on mobile genetic elements like plasmids, integrons and transposons

Evaluation of microbial inoculants as biofertilizers for the improvement of growth and yield of soybean and maize crops in savanna soils

Open Access JournalCertain rhizobacteria exert considerable influence on plant growth and development, particularly under limiting conditions. The effects of some indigenous soil microbial isolates and commercially produced microbial inoculants, referred to as bio-inoculants, on the growth and dry matter yield (DMY) of maize (Zea mays) and soybean (Glycine max) crops were assessed under greenhouse conditions. In two sets of experiments, one set comprised of free-living nitrogen-fixing microorganisms (Azospirillum spp.), three soils from Ibadan, Mokwa and Shanono located in different agro-ecological zones, and maize as the test crop. The other set consisted of microbial inoculants that can act as biocontrol agents applied to sterilized and non-sterilized soils; soybean was the test crop. The bio-inoculants were applied separately and also in combination. The treatments included a reference termed ‘mineral N’ where macro- and micro-nutrients were supplied at optimal rates, a control where bio-inoculants were not applied, and four replicates. All treatments, excluding the reference, received only macro-nutrients at suboptimal rates. The crops were grown for eight weeks and growth parameters were measured. The shoot DMY of maize was relatively large (42 to 63 g plant-1) and differed significantly among the soils but the bio-inoculants did not improve the shoot DMY significantly (P > 0.05) in any of the soils when compared with the control. However, sole inoculation of Mazospiriflo-2 enhanced nitrogen uptake significantly in maize grown in Shanono soil. For soybean, the shoot DMY was also not improved by the inoculation or the addition of the microbial products compared with the control

Bioaugmentation Approach using Pseudomonas and Bacillus for Malodour Reduction in Poultry Feacal Waste Management

Introduction. A workable strategy is bioaugmentation, which involves introducing certain bacteria in sufficient quantities to promote biodegradation. This study focuses on isolating and utilizing malodor-reducing bacteria from fecal wastes obtained from a poultry farm in Ashi, Ibadan. Methods. Standard methods were employed to isolate and identify species of Pseudomonas and Bacillus. Quantitative detection of hydrogen sulfide gas and other relevant parameters was performed using MSA Orion and Multi Gas Detector. Hydrogen sulfide (H2S) release was quantitatively monitored during fermentation, considering varying loads of inocula. Results. The bacterial isolates comprised Pseudomonas aeruginosa, P. fluorescens, P. putida, Bacillus fastidiosus, B. licheniformis, B. megaterium, B. subtilis, B. sphaericus, and B. thuringiensis. Odor levels varied based on inocula load and fermentation duration. In batches with Pseudomonas, hydrogen sulfide was undetectable after two days, while Bacillus-inoculated batches required ten days. The formation of microbial mats and subsequent decrease in H2S content contributed to malodor reduction. Notably, fluorescent pseudomonas exhibited successful mineralization during the treatment of fecal waste. Conclusion. Pseudomonas isolates demonstrated superior effectiveness in odor reduction compared to Bacillus isolates

Foreign aid, human capital and economic growth nexus: Evidence from Nigeria

This study investigates the link between aid and human capital in promoting economic growth of Nigeria. The study used two models; the first model was used to test the validity of the medicine model in Nigeria; while the extended model was used to investigate the effect of aid and human capital shocks on growth using Engle-Granger and Vector Error Correction Model (VECM) estimation techniques respectively. The findings from the first model suggest that persistent increase in foreign aid flows beyond a particular point (the optimal point) may adversely affect growth thus confirming the proposition of the Medicine Model. Evidence from the study’s extended model indicates that growth in Nigeria is sensitive to human capital shock via education while the response from aid shock is trivial in the long run. The mechanism through which aid impacts economies is influenced by many heterogeneous factors, notably; the role played by the recipient governments is often not considered. Our implication from the obtained results is that government expenditures on education with additional inflows of aid can promote economic growth in Nigeria. However, there is also an indication that attainment of economic growth might be challenging for this aid-dependent country

Evaluation of Resistance Pattern and Plasmid Profile of Staphylococcus Species Isolated from Clinical and Community Samples in Ibadan South-West, Nigeria

Aims: Staphylococcus species have been a major human pathogen of public health importance globally. This study was designed to evaluate the resistance pattern and plasmid profile of Staphylococcus species isolated from clinical and community settings. Methodology: Staphylococcus species from clinical (55) and community (53) which were previously isolated in University of Ibadan and her teaching hospital and identified as S. epidermidis (92.6%), S. aureus (6.5%) and S. xylosus (0.9%) were used. The antibiogram and plasmid profiles were determined by standard procedures. Results: In clinical isolates of S. epidermidis, 30.9, 34.5, 40.0, 41.8, 60.0, 76.4, and 89.1% were resistant to chloramphenicol (CHL), streptomycin (STR), erythromycin (ERY), gentamycin (GEN), tetracycline (TET), cotrimoxazole (COT), and cloxacillin (CXC) respectively. Correspondingly, in community isolates of S. epidermidis, 28.3, 32.1, 50.9, 26.4, 58.5, 90.6 and 92.5% were resistant to these antibiotics. The only clinical S. xylosus isolated was resistant to all the antibiotics except CHL and STR. In the clinical isolates of S. aureus, 5.5, 5.5, 7.3, 7.3, 7.3, 9.1 and 9.1% were resistant to ERY, CHL, STR, GEN, TET, COT and CXC respectively. In community isolates, only one S. aureus was resistant to COT, CHL, ERY, GEN and STR while two were resistant to CXC. Plasmid profiling showed that 33/35 (94.3%) of clinical and 17/19 (89.5%) of community isolates had plasmid of size 23.13 kb. Conclusion: The increasing resistance and similarity of plasmid profile of the community isolates to clinical isolates call for urgent establishment of antibiotic surveillance system to minimize the emergence of drug resistance pathogens in the community

ANTIMICROBIAL RESISTANCE IN ENTEROBACTERIACEAE FROM INTENSIVELY-REARED APPARENTLY HEALTHY AND DISEASED POULTRY IN ABEOKUTA, NIGERIA

The emergence and wide-spread dissemination of antimicrobial resistant bacteria strains is a global phenomenon of great public health and economic implications. Antimicrobial resistance was investigated in enterobacteriaceae isolated from apparently healthy and diseased poultry birds using the broth micro-dilution method to determine antimicrobial minimum inhibitory concentration (MIC). In all, 504 bacterial isolates including Escherichia coli (471), Klebsiella spp (28) and Salmonella enterica isolates (5) were studied. The isolates were resistant to ampicillin (88.5%), chloramphenicol (62.3%), ciprofloxacin (74.8%), enrofloxacin (81.0%), neomycin (83.9%), norfloxacin (78.8%), streptomycin (91.3%) and tetracycline (83.3%). The geometric mean MIC (µg/µL) of tested antimicrobials for enterobacteriaceae is as follows: ampicillin (102.5), chloramphenicol (48.4), ciprofloxacin (19.1), enrofloxacin (34.5), neomycin (47.7), norfloxacin (24.5), streptomycin (142.2) and tetracycline (62.5). Although rates of resistance to ampillin, streptomycin and tetracycline were similar among isolates from apparently healthy and diseases birds, resistance to chloramphenicol, ciprofloxacin, enrofloxacin, neomycin and norfloxacin were significantly higher (p<0.05) in isolates from diseased chickens than in those from apparently healthy chickens. The high rates of antimicrobial resistance in bacteria may contribute to the persistence of pathogens in poultry flock and ineffectiveness of antimicrobial chemotherapy during disease outbreaks.Â

The Impact of Ethical Tax Behaviour on Tax Compliance of Tax Authority and Corporate Taxpayers of listed Manufacturing Companies in Nigeria

The development of tax payment decision-making models (Sociological, Economical and Psychological) has focused on economic and behavioural factors affecting tax compliance. The issue of tax evasion, which remains an ethical problem for companies, has been a general concern in developed and developing countries alike. The main problem of this study is low tax collection on the part of relevant tax authority, couple with non-tax compliance behaviour of the corporate taxpayers in Nigeria. This study examined the effect of tax fairness of tax authority on tax compliance behaviour of taxpayers in the Nigerian manufacturing sector. This study adopted a survey research method, and 400 copies of the questionnaire were administered to the selected listed manufacturing companies in Nigeria and relevant tax authority staff (FIRS). Theory of Planned Behaviour underpinned this study and Correlation analysis, Analysis of Variance (ANOVA) and Multiple Regression analysis were also employed. The study found that there is a significant level of tax compliance among the listed manufacturing company in Nigeria. The study also shows that the tax authority’s perception of fairness of -2.769 (0.006) has a significant impact on corporate taxpayer’s compliance behaviour. Based on the above findings, the study recommends that taxpayers need to file accurate tax returns, transparency in total income declaration and minimize the risk of breaching of tax laws within the entity, while tax authority should apply tax laws consistently without bias (fairness), also adhere strictly to moral and ethical code of conduct. Keywords: Taxes, Ethics, Tax Authority, Manufacturing, Nigeri

Investigation of the Inhibitive Properties of Alchornea laxiflora leaves on the Corrosion of Mild Steel in HCl: Thermodynamics and Kinetic Study

Staff PublicationThe use of naturally occurring compounds as corrosion inhibitors is of potential interest because of their cost effectiveness, abundant availability and environmental acceptability. Therefore, the study investigates the inhibition efficacy of acid extract of Alchornea laxiflora leaves on mild steel in acidic medium using gravimetric method. Experiments were performed by varying the immersion time, concentration of extract and the temperature. The results showed that acid extract of Alchornea laxiflora leaves is a potential inhibitor for the corrosion of mild steel in acidic medium. The corrosion rate of mild steel in 1M HCl decreases with increase in the concentration of the extract. The inhibition efficiency increases progressively as the concentration of the extract increases but decreases with rise in temperature and the exposure time. The highest inhibition efficiency observed in the presence of the extract was 96 %. Activation energy was found to be 21.81 kJ mol-1 for the blank and increases to 82.57 kJ mol-1 in the presence of the extract. Thermodynamic parameters such as enthalpy change, entropy change and Gibb’s free energy were evaluated. Kinetics of the reaction in the presence of the extracts revealed that it follows a first order reaction and the half-lives increase as the concentration of the extract increases. Adsorption studies revealed that Langmuir adsorption isotherm is the best adsorption model applicable to the adsorption of the extract on mild steel surface. Preliminary investigation of the phytochemical con