Morphology of F-region vertical E×B drifts in the African sector using ionosonde measurements

F-region vertical velocities are derived from the ground-based ionosonde data for Ibadan (7.4°N, 3.9°E; dip 6°S: an equatorial station in the African zone), to study the general characteristics of electrodynamics of equatorial ionosphere, such as their variation with season, solar cycle, and magnetic activity at different local time sectors. The results show profound seasonal and geomagnetic effects. Except for equinoctial period, there is an excellent consistency in the magnitudes (nearly 20 m/s) and patterns of upward daytime F-region drifts at low and high solar activity periods. Evening F-region exhibits strong motion with absolute mean value for quiet-time (15 m/s) greater than on disturbed-time (10 m/s). The average downward quiet midnight-early morning hours sector value is well below than 10 m/s. The evening reversal time is earliest and latest during solstitial periods. Prereversal peak is season dependent and varies strongly with magnetic activity. We show that prereversal peak, daytime, and nighttime maximum drifts saturate at particular values of F10.7 cm solar radio flux index, effects not noticed with corresponding sunspot number. Our observations confirm several previous results from other equatorial sites utilizing different experimental techniques

Growth of Pseudomonas aeruginosa LP5 on 2, 5-dicchlorobenzoate: Detection of aromatic ring hydroxylating dioxygenase (ARHDO) gene

Pseudomonas aeruginosa LP5 grew on 2, 5-dichlorobenzoate with doubling time (D) 6.64 d and mean growth rate (k) 0.104 d-1. The organism showed a prolonged lag period lasting 9 days followed by a sudden rise within 3 days (D= 1.1 d; k= 0.628 d-1) and death in less than 72 hours on 2, 6-dichlorobenzoate. Polymerase chain reaction (PCR) amplification of DNA of LP5 showed aromatic dihydroxylating (ARHDO) gene band with molecular weight corresponding to the targeted fragment (0.73 kb). The capability of LP5 on dichlorobenzoates and detection of dioxygenase genes is a validation of its versatility and potential for bioremediation

Can Lifestyle Factors of Diabetes Mellitus Patients Affect Their Fertility?

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Metal biouptake by actively growing cells of metal-tolerant bacterial strains

Metal uptake potentials of Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia CA96Co, Rhodococcus sp. AL03Ni, and Corynebacterium kutscheri FL108Hg were studied to determine their competence in detoxification of toxic metals during growth. Metabolism-dependent metal biouptake of the bacteria revealed appreciable uptake of the metals (57–61, 10–30, 23–60, and 10–16 mg g dw−1 of Ni2+, Cr6+, Co2+, and Cd2+, respectively) from medium, after initial drop in pH, without lag phase. The bacteria exhibited 95–100 % removal efficiency for the metals from aqueous medium as 21 (±0.8)–84 (±2.0) concentration factors of the metals were transported into the bacterial systems. Passive adsorption onto the cell surfaces occurred within 2-h contact, and afterwards, there was continuous accumulation for 12 days. Biosorption data of the bacteria were only fitted into Langmuir isotherm model when strains AL96Co, CA207Ni, and AL03Ni interacted with Ni2+, achieving maximum uptake of 9.87, 2.72, and 2.69 mg g dw−1, respectively. This study established that the actively growing bacterial strains displayed, at least, 97.0 % (±1.5) continuous active removals of metals upon adsorption. The bacteria would be good candidates for designing bioreactor useful in the detoxification campaign of heavy metal-polluted systems

Effects of cadmium perturbation on the microbial community structure and heavy metal resistome of a tropical agricultural soil

The effects of cadmium (Cd) contamination on the microbial community structure, soil physicochemistry and heavy metal resistome of a tropical agricultural soil were evaluated in field-moist soil microcosms. A Cd-contaminated agricultural soil (SL5) and an untreated control (SL4) were compared over a period of 5 weeks. Analysis of the physicochemical properties and heavy metals content of the two microcosms revealed a statistically significant decrease in value of the soil physicochemical parameters (P < 0.05) and concentration of heavy metals (Cd, Pb, Cr, Zn, Fe, Cu, Se) content of the agricultural soil in SL5 microcosm. Illumina shotgun sequencing of the DNA extracted from the two microcosms showed the predominance of the phyla, classes, genera and species of Proteobacteria (37.38%), Actinobacteria (35.02%), Prevotella (6.93%), and Conexibacter woesei (8.93%) in SL4, and Proteobacteria (50.50%), Alphaproteobacteria (22.28%), Methylobacterium (9.14%), and Methylobacterium radiotolerans (12,80%) in SL5, respectively. Statistically significant (P < 0.05) difference between the metagenomes was observed at genus and species delineations. Functional annotation of the two metagenomes revealed diverse heavy metal resistome for the uptake, transport, efflux and detoxification of various heavy metals. It also revealed the exclusive detection in SL5 metagenome of members of RND (resistance nodulation division) protein czcCBA efflux system (czcA, czrA, czrB), CDF (cation diffusion facilitator) transporters (czcD), and genes for enzymes that protect the microbial cells against cadmium stress (sodA, sodB, ahpC). The results obtained in this study showed that Cd contamination significantly affects the soil microbial community structure and function, modifies the heavy metal resistome, alters the soil physicochemistry and results in massive loss of some autochthonous members of the community not adapted to the Cd stress

Degradation of cyclohexane and cyclohexanone by Bacillus lentus strain LP32

A Gram-positive bacterium, Bacillus lentus LP32, originally isolated on the basis of its ability to utilise pyrene as sole source of carbon was found to be able to grow luxuriantly on alicyclic compounds as sole substrates. It showed poor growth on anthracene, naphthalene, 1-naphthol and phenanthrene. Growth rate on cyclohexane was 1.32 d-1, while doubling time was 0.76 d. The corresponding values for growth on cyclohexanone were 0.77 d-1 and 1.29 d, respectively. Within 10 days, the amount of cyclohexane in culture reduced from 317.62 to 102.55 mgl-1, then to 23.04 mgl-1 on day 18. On cyclohexanone, substrate concentration decreased from 287.56 mgl-1 to 101.66 mgl-1 in 10 days before declining to 24.21 mgl-1 on day 18. The rate of degradation when growing on cyclohexane was 23.50 mgl-1d-1 in the first 10 days and 9.93 mgl-1d-1 between day 10 and day 18, with 67.71% degradation in 10 days and overall percentage degradation of 92.43%. On cyclohexanone, the corresponding values were 18.59 and 9.68 mg l-1d-1 as well as 64.65 and 91.58%, respectively. This organism is a potential candidate for bioremediation purpose.Keywords: Degradation, cyclohexane, cyclohexanone, alicyclic compounds

Influence of pH, temperature and nutrient addition on the degradation of atrazine by Nocardioides spp. isolated from agricultural soil in Nigeria.

Aims: To effectively exploit the atrazine degrading capabilities of Nocardioides spp. isolated from agricultural soil samples in Nigeria and ascertain the effect of pH, temperature and nutrient addition on the degradation process. Methodology and results: Isolates were cultivated on atrazine mineral salts medium at a temperature range of 4 °C - 45 °C and a pH range of 3-10. An optimum atrazine degrading activity was observed in the isolates between temperatures of 25 °C and 37 °C and between pH 5 and 8. Different carbon sources (glycerine, glucose, chitin, cellulose and sodium citrate) and nitrogen sources (urea, biuret, cyanuric acid, potassium nitrate and ammonium chloride) were also added to the medium. The addition of carbon and nitrogen sources did not increase degradation rates although urea and glycerine repressed the degradation ability of the isolates. Statistical analyses of variance at P < 0.05 showed no significant differences in the growth and degradation rates by both bacterial isolates under these conditions. Conclusion, significance and impact study: Atrazine degradation by Nocardioides spp. is pH and temperature dependent, and requires no additional sources of carbon and nitrogen. Hence, its use in bioremediation of atrazine contaminated agricultural soil should be explored

Synthesis strategies and application of ternary quantum dots—in cancer therapy

Semiconductor nanoparticles also known as quantum dots (QDs) have continued to receive more attention from researchers due to their unique optical, magnetic and photo physical properties which made them useful as biomedical materials, solar cells, catalyst etc. However, ternary I–III–VI QDs have shown to be a safer alternative to the binary II–VI or IV–VI QDs due to the absent of heavy toxic elements such as Cd and Pb. Cancer management and therapy in Africa has been bedevilled by a lot of challenges such as inaccurate diagnosis and ineffective therapeutic methods. Therefore, the need to develop an appropriate approach for cancer detection and treatment is of paramount importance. Tunable optical properties and absorption in the near infra-red region of the ternary QDs makes them useful as fluorescent probes in cancer detection and treatment. They have the ability to detect specific cancer cells including those that are not easily detected by modern imaging technique. Also, properties such as non-bleaching, stability, water solubility etc. made them a desirable fluorophore when compared to conventional dyes. Most cancer drugs suffer from inherent shortcomings such as limited absorption, insolubility and aggregation. However, these shortcomings can be overcome when these drugs are applied in form of conjugated systems. The use of QDs as conjugates has revolutionise the treatment of cancer in the 21st century. This review provides information about the synthesis strategies, optical properties, hydrophilization and bioconjugation of ternary I–III–VI QDs. Furthermore, we described the various biomedical applications in biosensors, bioimaging, drug delivery and phototherapeutic techniques. Finally, we looked at the challenges and future perspective of these QDs in cancer management

Biodegradation potentials of polyaromatic hydrocarbon (pyrene and phenanthrene) by Proteus mirabilis isolated from an animal charcoal polluted site

Indiscriminate disposal of animal charcoal from skin and hides cottage industries often impact the environments with toxic hydrocarbon components and thus require eco-friendly remedial strategies. A bacterial strain isolated from a site polluted with animal charcoal was characterized, identified as Proteus mirabilis 10c, and studied for ability to degrade pyrene and phenanthrene. The bacterium resisted 30 µg chloramphenicol, 10 µg ampicillin, 30 µg amoxicillin and 10 µg perfloxacin; while it utilized a number of polycyclic aromatic hydrocarbons and cinnamic acid. Specific growth rate on pyrene and phenanthrene were 0.281 d−1 and 0.276 d−1, respectively. Kinetics of degradation of pyrene was 87.92 mg l−1 in 30 days at the rate of 2.93 mg l−1 d−1, biodegradation constant at 0.073 d−1 and half-life of 9.50 d. The corresponding values for phenanthrene degradation kinetics by the bacterium were 90.12 mg l−1, 3.02 mg l−1 d−1, 0.079 d−1 and 8.77 d, respectively. Efficient degradation of crude oil (92.3%) in chemically defined medium was evident with near-disappearance of most aromatic spectra in 30 days. Considering its unique physiologies and broad specificities for aromatic and aliphatic hydrocarbons, the bacterium has potentials for decommissioning environments contaminated with toxic components of animal charcoal

Clinical versus Sonographic Estimation of Foetal Weight in Southwest Nigeria

A prospective study was conducted at Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, Nigeria, between 3 January and 31May 2004, to compare the accuracy of clinical and ultrasonographic estimation of foetal weight at term. One hundred pregnant women who fulfilled the inclusion criteria had their foetal weight estimated independently using clinical and ultrasonographic methods. Accuracy was determined by percentage error, absolute percentage error, and proportion of estimates within 10% of actual birthweight (birthweight of +10%). Statistical analysis was done using the paired t-test, the Wilcoxon signed-rank test, and the chi-square test. The study sample had an actual average birthweight of 3,255+622 (range 2,150–4,950) g. Overall, the clinical method overestimated birthweight, while ultrasound underestimated it. The mean absolute percentage error of the clinical method was smaller than that of the sonographic method, and the number of estimates within 10% of actual birthweight for the clinical method (70%) was greater than for the sonographic method (68%); the difference was not statistically significant. In the low birthweight (<2,500 g) group, the mean errors of sonographic estimates were significantly smaller, and significantly more sonographic estimates (66.7%) were within 10% of actual birthweight than those of the clinical method (41.7%). No statistically significant difference was observed in all the measures of accuracy for the normal birthweight range of 2,500-<4,000 g and in the macrosonic group (≥4,000 g), except that, while the ultrasonographic method underestimated birthweight, the clinical method overestimated it. Clinical estimation of birthweight is as accurate as routine ultrasonographic estimation, except in low-birthweight babies. Therefore, when the clinical method suggests weight smaller than 2,500 g, subsequent sonographic estimation is recommended to yield a better prediction and to further evaluate foetal well-being