Environmentally unfriendly Oil exploration activities have been ongoing in the Soku area of the Niger Delta of Nigeria since 1956. This study evaluated the concentration of hydrocarbons and heavy metals in Shellfish a...Environmentally unfriendly Oil exploration activities have been ongoing in the Soku area of the Niger Delta of Nigeria since 1956. This study evaluated the concentration of hydrocarbons and heavy metals in Shellfish and drinking water sources in the study area. It revealed the absence (<0.001 mg/l) of most heavy metals (Ni, Ch, Cd, Pb mg/l) in the water column;a high concentration of the major ion composition of seawater (sulphates 5 - 1018;calcium 0.502 - 53.502;sodium 1.247 - 63.337;potassium 0.508 - 102.745;magnesium 0.354 - 42.574 mg/l);and high PAHs (<0.001 - 0.032 mg/l) levels occurring above WHO limits (0.007 mg/l) with some risk of exposure to cancer. Results from the analysis of shellfish showed that concentrations of chromium and zinc were below permissible limits while cadmium concentrations were slightly above permissible limits of the European Community. Nickel and lead were above permissible limits in the fish samples in all standards while PAHs occurred at the cancer risk levels of 10?6. A review of the public health situation in the Soku area with a view to understanding current trends, sources of perturbations and preferable solutions to the potential public health challenges raised in this study is hereby recommended. Also, this study recommends that relevant agencies and developmental partners should launch a national drive to create awareness among people/environmental/public health professionals’/health workers/administrators on this regional concern.展开更多
The effect of proportional blend of periwinkle and African star apple seed shell as bio-fillers in flexible polyether foam was studied.Flexible polyether foam samples incorporated with these bio-fillers at varying per...The effect of proportional blend of periwinkle and African star apple seed shell as bio-fillers in flexible polyether foam was studied.Flexible polyether foam samples incorporated with these bio-fillers at varying percentages;10%(S1),20%(S2),30%(S3),40%(S4)and 50%(S5)were produced respectively,while 0%(S0)which had no filler was used as control during the experiment.The mechanical properties of the produced foam samples were determined via density,compression set,indentation hardness,tensile strength and elongation at break tests.The cream time,rise time and height of the foam as parameters for characterising the produced foam samples were determined too.Flammability test was also carried out.The microstructure of the foam samples was analysed as well by using the scanning electron microscope.The results of the experiment showed that the density of the foam samples progressively increased from 19.20(S0)-26.45(S5)as the quantity of the filler increased.The indentation hardness result also showed an increase on addition of the filler.The foam’s loading ability also increased on incorporation of the filler but S3 showed remarkable recovery after compression.The tensile strength and elongation at break of the foam decreased on addition of the filler.The morphological analysis ascertained the effect of the progressive introduction of the filler on the surface morphology of the foam.The flammability of the foam was found to decrease as the filler load increased.Since these fillers are of organic origin,readily available,cheap and eco-friendly,they provide a means of making biodegradable foam,and reducing the flammability of foam.Thus,reducing environmental pollution whilst enhancing the mechanical property of foam.展开更多
Several recent studies of vertebrate adaptation to environmental stress have suggested roles for microRNAs （miRNAs） in regulating glo- bal suppression of protein synthesis and/or restructuring protein expression pat...Several recent studies of vertebrate adaptation to environmental stress have suggested roles for microRNAs （miRNAs） in regulating glo- bal suppression of protein synthesis and/or restructuring protein expression patterns. The present study is the first to characterize stress- responsive alterations in the expression of miRNAs during natural freezing or anoxia exposures in an invertebrate species, the intertidal gastropod Littorina littorea. These snails are exposed to anoxia and freezing conditions as their environment constantly fluctuates on both a tidal and seasonal basis. The expression of selected miRNAs that are known to influence the cell cycle, cellular signaling pathways, carbohydrate metabolism and apoptosis was evaluated using RT-PCR. Compared to controls, significant changes in expression were observed for miR-la-1, miR-34a and miR-29b in hepatopancreas and for miR-la-1, miR-34a, miR-133a, miR-125b, miR-29b and miR-2a in foot muscle after freezing exposure at -6 ~C for 24 h （P 〈 0.05）. In addition, in response to anoxia stress for 24 h, significant changes in expression were also observed for miR-la-1, miR-210 and miR-29b in hepatopancreas and for miR-1 a-1, miR-34a, miR-133a, miR-29b and miR-2a in foot muscle （P 〈 0.05）. Moreover, protein expression of Dicer, an enzyme responsible for mature microRNA processing, was increased in foot muscle during freezing and anoxia and in hepatopancreas during freezing. Alterations in expression of these miRNAs in L. littorea tissues may contribute to organismal survival under freezing and anoxia.展开更多
文摘Environmentally unfriendly Oil exploration activities have been ongoing in the Soku area of the Niger Delta of Nigeria since 1956. This study evaluated the concentration of hydrocarbons and heavy metals in Shellfish and drinking water sources in the study area. It revealed the absence (<0.001 mg/l) of most heavy metals (Ni, Ch, Cd, Pb mg/l) in the water column;a high concentration of the major ion composition of seawater (sulphates 5 - 1018;calcium 0.502 - 53.502;sodium 1.247 - 63.337;potassium 0.508 - 102.745;magnesium 0.354 - 42.574 mg/l);and high PAHs (<0.001 - 0.032 mg/l) levels occurring above WHO limits (0.007 mg/l) with some risk of exposure to cancer. Results from the analysis of shellfish showed that concentrations of chromium and zinc were below permissible limits while cadmium concentrations were slightly above permissible limits of the European Community. Nickel and lead were above permissible limits in the fish samples in all standards while PAHs occurred at the cancer risk levels of 10?6. A review of the public health situation in the Soku area with a view to understanding current trends, sources of perturbations and preferable solutions to the potential public health challenges raised in this study is hereby recommended. Also, this study recommends that relevant agencies and developmental partners should launch a national drive to create awareness among people/environmental/public health professionals’/health workers/administrators on this regional concern.
文摘The effect of proportional blend of periwinkle and African star apple seed shell as bio-fillers in flexible polyether foam was studied.Flexible polyether foam samples incorporated with these bio-fillers at varying percentages;10%(S1),20%(S2),30%(S3),40%(S4)and 50%(S5)were produced respectively,while 0%(S0)which had no filler was used as control during the experiment.The mechanical properties of the produced foam samples were determined via density,compression set,indentation hardness,tensile strength and elongation at break tests.The cream time,rise time and height of the foam as parameters for characterising the produced foam samples were determined too.Flammability test was also carried out.The microstructure of the foam samples was analysed as well by using the scanning electron microscope.The results of the experiment showed that the density of the foam samples progressively increased from 19.20(S0)-26.45(S5)as the quantity of the filler increased.The indentation hardness result also showed an increase on addition of the filler.The foam’s loading ability also increased on incorporation of the filler but S3 showed remarkable recovery after compression.The tensile strength and elongation at break of the foam decreased on addition of the filler.The morphological analysis ascertained the effect of the progressive introduction of the filler on the surface morphology of the foam.The flammability of the foam was found to decrease as the filler load increased.Since these fillers are of organic origin,readily available,cheap and eco-friendly,they provide a means of making biodegradable foam,and reducing the flammability of foam.Thus,reducing environmental pollution whilst enhancing the mechanical property of foam.
基金supported by a Discovery Grant from the Natural Sciences and Engineering Research Council (NSERC Grant No. 6793) of CanadaK.K. Biggar held an NSERC postgraduate fellowship, and S.F. Kornfeld and Y. Maistrovski were supported by NSERC undergraduate summer research awards
文摘Several recent studies of vertebrate adaptation to environmental stress have suggested roles for microRNAs （miRNAs） in regulating glo- bal suppression of protein synthesis and/or restructuring protein expression patterns. The present study is the first to characterize stress- responsive alterations in the expression of miRNAs during natural freezing or anoxia exposures in an invertebrate species, the intertidal gastropod Littorina littorea. These snails are exposed to anoxia and freezing conditions as their environment constantly fluctuates on both a tidal and seasonal basis. The expression of selected miRNAs that are known to influence the cell cycle, cellular signaling pathways, carbohydrate metabolism and apoptosis was evaluated using RT-PCR. Compared to controls, significant changes in expression were observed for miR-la-1, miR-34a and miR-29b in hepatopancreas and for miR-la-1, miR-34a, miR-133a, miR-125b, miR-29b and miR-2a in foot muscle after freezing exposure at -6 ~C for 24 h （P 〈 0.05）. In addition, in response to anoxia stress for 24 h, significant changes in expression were also observed for miR-la-1, miR-210 and miR-29b in hepatopancreas and for miR-1 a-1, miR-34a, miR-133a, miR-29b and miR-2a in foot muscle （P 〈 0.05）. Moreover, protein expression of Dicer, an enzyme responsible for mature microRNA processing, was increased in foot muscle during freezing and anoxia and in hepatopancreas during freezing. Alterations in expression of these miRNAs in L. littorea tissues may contribute to organismal survival under freezing and anoxia.
