93 research outputs found
Determination of some total and bioavailable heavy metals in farmland soil around Rivers Niger and Benue in Lokoja, Nigeria
The work assessed the distribution of Cd, Cu, Mn, Ni, Pb and Zn in the farmland soils around Rivers Niger and Benue and beyond the confluence in Lokoja, Nigeria. The samples were collected in the dry and rainy seasons of 2013 and 2014, digested with aqua regia and analysed for heavy metals using atomic absorption spectrophotometry. The soil pH ranged from 6.4 to 7.2 for the farmland soils collected 50 m away from the bank of the rivers and each point 10 m apart (n=72). There was no significant difference in the mean values of the organic matter, organic carbon and moisture contents of the soils across the seasons. Cd concentration (mg/kg)in the soil samples collected in March 2013, June 2013, January 2014 and May 2014 at 0 â 15 cm depth ranged from 3.95 - 8.4; Cu 11.6 - 20.2 ; Mn 150.3 - 211.5; Ni 177.0 - 281.0 ; Pb 20.3 - 34.2 and Zn 40.5 - 77.8. The levels of the metals in the soil follow the ranking: Ni > Mn > Zn > Pb > Cu > Cd; with Cd and Ni being above European Union permissible limits. The order of the percentage of extracted metal by EDTA to the total metal content was Pb>Zn>Cu>Ni>Mn>Cd. I-geo pollution index showed that the farmland soils were moderately contaminated with Ni and Cd. Hence, there is the need to enforce environmental laws that borders on proper solid waste and effluent disposals.Key Words: Heavy Metalsâ Pollution index â River Niger and Benue â Soils â Seaso
Influence of Vehicle Traffic Emissions on Spatial Variation of Ozone and its Precursors in Air of Port Harcourt City, Nigeria
This study aimed at assessing the influence of vehicle traffic on spatial variation of ozone (O3) and its vehicular emission precursors in the air of Port Harcourt city. Sampling was carried out in ten (10) sites, eight (8) located within the high traffic density area (study sites) and two (2) located within the very low traffic density area (reference sites). The precursor pollutants measured were nitrogen dioxide (NO2), carbon monoxide (CO) and volatile organic compounds (VOCSs). Ozone and the precursor pollutants were measured in situ using AeroQUAL 500 series portable ambient air analyzer while traffic flow survey was achieved by direct counting. Measurements were carried out at morning, evening and off-peak traffic periods respectively. The mean concentrations of ozone and the precursor pollutants were significantly higher (p = 0.05) in the study sites than in the reference sites. Mean concentrations were higher at peak traffic periods than at off-peak traffic periods except for ozone that was higher at off-peak than at morning peak. There was significant correlation between traffic density and each of the pollutants including ozone. The spatial variability in concentration of pollutants was influenced by vehicular traffic. VOCs and NO2 levels were higher than the National Ambient Air Quality Standard (NAAQS) limit of 0.05 ppm and 0.04 â 0.06 ppm respectively, O3 concentration was below the standard limit (0.06 ppm) but was at the verge of exceeding. Traffic emission within the city was significant and could be mitigated through regular monitoring and control
Phenolic compounds isolated from Pilea microphylla prevent radiation-induced cellular DNA damage
AbstractSix phenolic compounds namely, quercetin-3-O-rutinoside (1), 3-O-caffeoylquinic acid (2), luteolin-7-O-glucoside (3), apigenin-7-O-rutinoside (4), apigenin-7-O-ÎČ-d-glucopyranoside (5) and quercetin (6) were isolated from the whole plant of Pilea microphylla using conventional open-silica gel column chromatography and preparative HPLC. Further, these compounds were characterized by 1D, 2D NMR techniques and high-resolution LCâMS. Compounds 1â3 and 6 exhibited significant antioxidant potential in scavenging free radicals such as DPPH, ABTS and SOD with IC50 of 3.3â20.4ÎŒmol/L. The same compounds also prevented lipid peroxidation with IC50 of 10.4â32.2ÎŒmol/L. The compounds also significantly prevented the Fenton reagent-induced calf thymus DNA damage. Pre-treatment with compounds 1â3 and 6 in V79 cells attenuated radiation-induced formation of reactive oxygen species, lipid peroxidation, cytotoxicity and DNA damage, correlating the antioxidant activity of polyphenols with their radioprotective effects. Compounds 1, 3 and 6 significantly inhibited lipid peroxidation, presumably due to 3âČ,4âČ-catechol ortho-dihydroxy moiety in the B-ring, which has a strong affinity for phospholipid membranes. Oxidation of flavonoids, with catechol structure on B-ring, yields a fairly stable ortho-semiquinone radical by facilitating electron delocalization, which is involved in antioxidant mechanism. Hence, the flavonoid structure, number and location of hydroxyl groups together determine the antioxidant and radioprotection mechanism
Covariant description of inelastic electron--deuteron scattering:predictions of the relativistic impulse approximation
Using the covariant spectator theory and the transversity formalism, the
unpolarized, coincidence cross section for deuteron electrodisintegration,
, is studied. The relativistic kinematics are reviewed, and simple
theoretical formulae for the relativistic impulse approximation (RIA) are
derived and discussed. Numerical predictions for the scattering in the high
region obtained from the RIA and five other approximations are presented
and compared. We conclude that measurements of the unpolarized coincidence
cross section and the asymmetry , to an accuracy that will distinguish
between different theoretical models, is feasible over most of the wide
kinematic range accessible at Jefferson Lab.Comment: 54 pages and 24 figure
Continuously improving the practice of cardiology
Guidelines for the management of patients with
cardiovascular disease are designed to assist
cardiologists and other physicans in their practice.
Surveys are conducted to assess whether guidelines
are followed in practice. The results of surveys on
acute coronary syndromes, coronary revascularisation,
secondary prevention, valvular heart disease
and heart failure are presented. Comparing surveys
conducted between 1995 and 2002, a gradual improvement
in use ofsecondary preventive therapy
is observed. Nevertheless, important deviations
from established guidelines are noted, with a
significant variation among different hospitals in
the Netherlands and in other European countries.
Measures for fiuther improvement of clinical
practice indude more rapid treatment of patients
with evolving myocardial infarction, more frequent
use of clopidogrel and glycoprotein IIb/IIIa
receptor blockers in patients with acute coronary
syndromes, more frequent use of 5-blockers in
patients with heart failure and more intense
measures to encourage patients to stop smoking.
Targets for the proportion ofpatients who might
receive specific therapies are presented
Fine-Scale Mapping of the 4q24 Locus Identifies Two Independent Loci Associated with Breast Cancer Risk
Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored.
Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium.
Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 Ă 10â4; OR, 1.04; 95% confidence interval (CI), 1.02â1.07] and rs77928427 (P = 1.86 Ă 10â4; OR, 1.04; 95% CI, 1.02â1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 â„ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factorâbinding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue.
Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2.
Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk
Exploring South Africa's southern frontier : a 20-year vision for polar research through the South African National Antarctic Programme
Antarctica, the sub-Antarctic islands and surrounding Southern Ocean are regarded as one of the planetâs
last remaining wildernesses, âinsulated from threat by [their] remoteness and protection under the Antarctic
Treaty Systemâ. Antarctica encompasses some of the coldest, windiest and driest habitats on earth. Within
the Southern Ocean, sub-Antarctic islands are found between the Sub-Antarctic Front to the north and the
Polar Front to the south. Lying in a transition zone between warmer subtropical and cooler Antarctic waters,
these islands are important sentinels from which to study climate change. A growing body of evidence
now suggests that climatically driven changes in the latitudinal boundaries of these two fronts define the
islandsâ short- and long-term atmospheric and oceanic circulation patterns. Consequently, sub-Antarctic
islands and their associated terrestrial and marine ecosystems offer ideal natural laboratories for studying
ecosystem response to change. For example, a recent study indicates that the shift in the geographical
position of the oceanic fronts has disrupted inshore marine ecosystems, with a possible impact on top
predators. Importantly, biotic responses are variable as indicated by different population trends of these top
predators. When studied collectively, these variations in speciesâ demographic patterns point to complex
spatial and temporal changes within the broader sub-Antarctic ecosystem, and invite further examination of
the interplay between extrinsic and intrinsic drivers.http://www.sajs.co.zaam2017GeneticsMammal Research InstituteZoology and Entomolog
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