International Journal of Environmental Research and Public Health, Aug 9, 2017
In different regions across the globe, elevated arsenic contents in the groundwater constitute a ... more In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch-Rs) and chitosan: pumice (Ch-Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm (R 2 > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.
The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-We... more The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-West Ethiopia were analyzed using GC-ECD. Results of the analysis indicated that all samples contained detectable quantities of p,p'-DDT and its metabolites, p,p-DDE and p,p-DDD, but none of the other OCPs analyzed. Mean levels of total DDT in the human and cow milk samples in the three areas were 12.68 and 0.389 μg g(-1) respectively. The distributions of p,p-DDT, p,p-DDE and p,p-DDD in the human milk samples from the three locations followed the same trend in which the proportion of p,p-DDT was the highest in all the three cases, comprising 55-71% of total DDT, followed by p,p-DDE, 26-39%, and the least, p,p-DDD of 2-5%. The mean ratio of DDT/DDE concentration for the three areas was calculated to be 2.01. This value was much higher than the values reported from other countries in earlier studies and indicates the existence of a higher quantity of DDT from a fresh input in the three study areas. The mean estimated daily intake of DDT by infants from mother's milk in the three locations was found to be 62.17 μg kg(-1) body weight, which is about three times higher than the acceptable daily intake set by WHO/FAO for total DDT, 20 μg kg(-1) of body weight. This alarmingly high daily intake value is a cause for concern, since children are highly susceptible to effects from such environmental contaminants. The study has revealed that people in the study areas are facing exposure to DDT from recent use. The observed contamination of mother's milk and the possible transfer of the contaminant from mother to child is an obvious risk associated with breast-feeding in the study areas and possibly in other parts of the country too.
The 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane(AAAPTS) functionalized silica gel ... more The 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane(AAAPTS) functionalized silica gel (AAAPTS/SiO 2) was synthesized and used as a potential adsorbent for the As(V) removal from aqueous solutions. AAAPTS/SiO 2 was characterized by IR, nitrogen adsorption and point of zero charge (pH pzc) measurements. The adsorption behaviors of As(III) and As(V), adsorption isotherms and dynamics of As(V) on AAAPTS/SiO 2 adsorbent were investigated. It was found that As(V) could be selectively adsorbed on AAAPTS/ SiO 2 adsorbent within pH of 2.7-9.2, while As(III) could not be absorbed in the studied pH range. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 13.9 mg•g − 1 for the AAAPTS/SiO 2 adsorbent. Kinetic studies indicated that sorption followed a pseudo-second-order model. The results showed that AAAPTS/SiO 2 adsorbent could be employed as an effective material for the removal of As(V) from aqueous solutions.
As breast milk is normally the only source of food in the early stages of life, the dietary level... more As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and 'enset' based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by using FAAS. Ave...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5% in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2
... formation of PVA/polyvinylpyridine (PVA-g-PVP) and polyethylene glycol and dex-tran sulfate-s... more ... formation of PVA/polyvinylpyridine (PVA-g-PVP) and polyethylene glycol and dex-tran sulfate-silica sol composite which was used for hydrogen peroxide or ... starting carbon and the silicate, Ormosils or other inorganic oxides such as titanium, zirconium and ruthenium ...
Batch adsorption studies were carried out to evaluate the Pb2+ adsorption capacities of three dif... more Batch adsorption studies were carried out to evaluate the Pb2+ adsorption capacities of three different fired clay soils with different particle size distributions. Adsorption efficiency was observed to increase with an increase in clay content. Adsorption efficiencies of the fired clay soils were also influenced by the firing temperature, the solution’s acidity, initial Pb2+ concentration, shaking time and adsorbent dose. Adsorption of Pb2+ by the clay soils was observed to increase linearly from pH 1 to 5 and then remained nearly constant at higher pH values. The adsorption of Pb2+ was observed to increase sharply with Pb2+ for the lower initial concentrations (5 to 10 mg/L), while a modest increase in Pb2+ adsorption was found from 10 to about 50 mg/L, a concentration at which maximum removal was attained. The Langmuir and Freundlich adsorption models were applied to the adsorption data and the Langmuir model represented the adsorption process better than the Freundlich model, wi...
We investigate the thermodynamic and chemical structure of the intracluster medium (ICM) across a... more We investigate the thermodynamic and chemical structure of the intracluster medium (ICM) across a statistical sample of 20 galaxy clusters analysed with the Chandra X-ray satellite. In particular, we focus on the scaling properties of the gas density, metallicity and entropy and the comparison between clusters with and without cool cores (CCs). We find marked differences between the two categories except for the gas metallicity, which declines strongly with radius for all clusters (Z ∝ r −0.31), outside ∼0.02r 500. The scaling of gas entropy is non-self-similar and we find clear evidence of bimodality in the distribution of logarithmic slopes of the entropy profiles. With only one exception, the steeper sloped entropy profiles are found in CC clusters whereas the flatter slope population are all non-CC clusters. We explore the role of thermal conduction in stabilizing the ICM and conclude that this mechanism alone is sufficient to balance cooling in non-CC clusters. However, CC clusters appear to form a distinct population in which heating from feedback is required in addition to conduction. Under the assumption that non-CC clusters are thermally stabilized by conduction alone, we find the distribution of Spitzer conduction suppression factors, f c , to be log-normal, with a log (base 10) mean of −1.50 ± 0.03 (i.e. f c = 0.032) and log standard deviation 0.39 ± 0.02.
This study has been carried out to investigate the speciation of iron in the various, plant avail... more This study has been carried out to investigate the speciation of iron in the various, plant available and non-available, soil fractions and the efficiency of the Mango (Mangifera indica) plant leaf extract in mobilizing iron from the strongly-bound soil fractions of cultivated, forest and water logged soil samples which were collected
Journal of Occupational Medicine and Toxicology, 2012
Background In Ethiopia, although there are numerous small-scale and medium industries which use l... more Background In Ethiopia, although there are numerous small-scale and medium industries which use lead-based raw materials that may pose health risks to workers, there are no workplace regulations for lead exposure. Moreover, there are no studies carried out on the blood lead levels (BLLs) of workers or on the contribution of common workplace practices to lead poisoning. Method A cross-sectional study on the BLLs of 45 automotive garage workers and 40 non-garage workers was carried out in the town of Jimma, Ethiopia. In addition to BLL analysis, data on some risk factors such as smoking, and chewing ‘khat’ (the leaves of Catha adulis) were gathered through structured questionnaires and interviews and data analysis was performed using SPSS (version 16). The t-test was used to compare mean BLLs of study groups. The analysis of variance (ANOVA), Kruskal-Wallis, Pearson chi-square and odds ratio tests were used to investigate the associations between specific job type, smoking and/or ‘kha...
Background: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting inse... more Background: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. Methodology/Principal findings: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr) and insensitive acetylcholinesterase (ace-1R) mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dw...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5 % in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2) ranging 0.97 to 0.99. The adsorption capacities (qm) of S3, S2 and S1 calculated by using th...
BACKGROUND: As breast milk is normally the only source of food in the early stages of life, the d... more BACKGROUND: As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and ‘enset ’ based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. METHODS: Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by u...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5% in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2 ) ranging 0.97 to 0.99. The adsorption capacities (qm) of S3, S2 and S1 calculated by using th...
Background As breast milk is normally the only source of food in the early stages of life, the di... more Background As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and ‘enset’ based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. Methods Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by usin...
Http Dx Doi Org 10 1081 Tma 100002217, Aug 19, 2006
ABSTRACT A simple method for the detection and semi-quantitative determination of arsenic compoun... more ABSTRACT A simple method for the detection and semi-quantitative determination of arsenic compounds purgeable by a sweep gas from soil was designed. The results were used to tentatively evaluate the flow of volatile arsenic compounds from the lower reducing to the upper oxidizing zone in arsenic rich soils. About 10 kg of soil, with a total arsenic content of 2980 ± 25 mg kg−1 was purged with nitrogen at a flow rate of 10 ml min−1. The gaseous compounds were trapped in concentrated nitric acid solution, preconcentrated by gentle evaporation at 80°C and the arsenic content was determined by the Hydride Generation Atomic Absorption (HG-AAS) technique. Nitrite interference during detection was overcome by treating the final solution with sulfamic acid for 24 h at the prereduction step. Based on these results it may be reasonably assumed that at 20 ± 1°C from a one hectare area of soil having 15 cm depth in the lower reducing zone an estimated maximum of 1500 mg of arsenic could stream up to the oxidizing zone in one week time due to likely microbial reduction of arsenic. Part of these arsenic coumpounds would enter the atmosphere and the remaining part may get oxidized upon reaching the oxic layer and accumulate there in. The part undergoing oxidation in the oxic layer is suggested to be a factor contributing to the local maximum of arsenic in the 20 cm depth from the surface.
International Journal of Environmental Research and Public Health, Aug 9, 2017
In different regions across the globe, elevated arsenic contents in the groundwater constitute a ... more In different regions across the globe, elevated arsenic contents in the groundwater constitute a major health problem. In this work, a biopolymer chitosan has been blended with volcanic rocks (red scoria and pumice) for arsenic (V) removal. The effect of three blending ratios of chitosan and volcanic rocks (1:2, 1:5 and 1:10) on arsenic removal has been studied. The optimal blending ratio was 1:5 (chitosan: volcanic rocks) with maximum adsorption capacity of 0.72 mg/g and 0.71 mg/g for chitosan: red scoria (Ch-Rs) and chitosan: pumice (Ch-Pu), respectively. The experimental adsorption data fitted well a Langmuir isotherm (R 2 > 0.99) and followed pseudo-second-order kinetics. The high stability of the materials and their high arsenic (V) removal efficiency (~93%) in a wide pH range (4 to 10) are useful for real field applications. Moreover, the blends could be regenerated using 0.05 M NaOH and used for several cycles without losing their original arsenic removal efficiency. The results of the study demonstrate that chitosan-volcanic rock blends should be further explored as a potential sustainable solution for removal of arsenic (V) from water.
The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-We... more The level of some OCPs in human and cow milk collected from Asendabo, Serbo and Jimma in South-West Ethiopia were analyzed using GC-ECD. Results of the analysis indicated that all samples contained detectable quantities of p,p'-DDT and its metabolites, p,p-DDE and p,p-DDD, but none of the other OCPs analyzed. Mean levels of total DDT in the human and cow milk samples in the three areas were 12.68 and 0.389 μg g(-1) respectively. The distributions of p,p-DDT, p,p-DDE and p,p-DDD in the human milk samples from the three locations followed the same trend in which the proportion of p,p-DDT was the highest in all the three cases, comprising 55-71% of total DDT, followed by p,p-DDE, 26-39%, and the least, p,p-DDD of 2-5%. The mean ratio of DDT/DDE concentration for the three areas was calculated to be 2.01. This value was much higher than the values reported from other countries in earlier studies and indicates the existence of a higher quantity of DDT from a fresh input in the three study areas. The mean estimated daily intake of DDT by infants from mother's milk in the three locations was found to be 62.17 μg kg(-1) body weight, which is about three times higher than the acceptable daily intake set by WHO/FAO for total DDT, 20 μg kg(-1) of body weight. This alarmingly high daily intake value is a cause for concern, since children are highly susceptible to effects from such environmental contaminants. The study has revealed that people in the study areas are facing exposure to DDT from recent use. The observed contamination of mother's milk and the possible transfer of the contaminant from mother to child is an obvious risk associated with breast-feeding in the study areas and possibly in other parts of the country too.
The 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane(AAAPTS) functionalized silica gel ... more The 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane(AAAPTS) functionalized silica gel (AAAPTS/SiO 2) was synthesized and used as a potential adsorbent for the As(V) removal from aqueous solutions. AAAPTS/SiO 2 was characterized by IR, nitrogen adsorption and point of zero charge (pH pzc) measurements. The adsorption behaviors of As(III) and As(V), adsorption isotherms and dynamics of As(V) on AAAPTS/SiO 2 adsorbent were investigated. It was found that As(V) could be selectively adsorbed on AAAPTS/ SiO 2 adsorbent within pH of 2.7-9.2, while As(III) could not be absorbed in the studied pH range. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 13.9 mg•g − 1 for the AAAPTS/SiO 2 adsorbent. Kinetic studies indicated that sorption followed a pseudo-second-order model. The results showed that AAAPTS/SiO 2 adsorbent could be employed as an effective material for the removal of As(V) from aqueous solutions.
As breast milk is normally the only source of food in the early stages of life, the dietary level... more As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and 'enset' based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by using FAAS. Ave...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5% in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2
... formation of PVA/polyvinylpyridine (PVA-g-PVP) and polyethylene glycol and dex-tran sulfate-s... more ... formation of PVA/polyvinylpyridine (PVA-g-PVP) and polyethylene glycol and dex-tran sulfate-silica sol composite which was used for hydrogen peroxide or ... starting carbon and the silicate, Ormosils or other inorganic oxides such as titanium, zirconium and ruthenium ...
Batch adsorption studies were carried out to evaluate the Pb2+ adsorption capacities of three dif... more Batch adsorption studies were carried out to evaluate the Pb2+ adsorption capacities of three different fired clay soils with different particle size distributions. Adsorption efficiency was observed to increase with an increase in clay content. Adsorption efficiencies of the fired clay soils were also influenced by the firing temperature, the solution’s acidity, initial Pb2+ concentration, shaking time and adsorbent dose. Adsorption of Pb2+ by the clay soils was observed to increase linearly from pH 1 to 5 and then remained nearly constant at higher pH values. The adsorption of Pb2+ was observed to increase sharply with Pb2+ for the lower initial concentrations (5 to 10 mg/L), while a modest increase in Pb2+ adsorption was found from 10 to about 50 mg/L, a concentration at which maximum removal was attained. The Langmuir and Freundlich adsorption models were applied to the adsorption data and the Langmuir model represented the adsorption process better than the Freundlich model, wi...
We investigate the thermodynamic and chemical structure of the intracluster medium (ICM) across a... more We investigate the thermodynamic and chemical structure of the intracluster medium (ICM) across a statistical sample of 20 galaxy clusters analysed with the Chandra X-ray satellite. In particular, we focus on the scaling properties of the gas density, metallicity and entropy and the comparison between clusters with and without cool cores (CCs). We find marked differences between the two categories except for the gas metallicity, which declines strongly with radius for all clusters (Z ∝ r −0.31), outside ∼0.02r 500. The scaling of gas entropy is non-self-similar and we find clear evidence of bimodality in the distribution of logarithmic slopes of the entropy profiles. With only one exception, the steeper sloped entropy profiles are found in CC clusters whereas the flatter slope population are all non-CC clusters. We explore the role of thermal conduction in stabilizing the ICM and conclude that this mechanism alone is sufficient to balance cooling in non-CC clusters. However, CC clusters appear to form a distinct population in which heating from feedback is required in addition to conduction. Under the assumption that non-CC clusters are thermally stabilized by conduction alone, we find the distribution of Spitzer conduction suppression factors, f c , to be log-normal, with a log (base 10) mean of −1.50 ± 0.03 (i.e. f c = 0.032) and log standard deviation 0.39 ± 0.02.
This study has been carried out to investigate the speciation of iron in the various, plant avail... more This study has been carried out to investigate the speciation of iron in the various, plant available and non-available, soil fractions and the efficiency of the Mango (Mangifera indica) plant leaf extract in mobilizing iron from the strongly-bound soil fractions of cultivated, forest and water logged soil samples which were collected
Journal of Occupational Medicine and Toxicology, 2012
Background In Ethiopia, although there are numerous small-scale and medium industries which use l... more Background In Ethiopia, although there are numerous small-scale and medium industries which use lead-based raw materials that may pose health risks to workers, there are no workplace regulations for lead exposure. Moreover, there are no studies carried out on the blood lead levels (BLLs) of workers or on the contribution of common workplace practices to lead poisoning. Method A cross-sectional study on the BLLs of 45 automotive garage workers and 40 non-garage workers was carried out in the town of Jimma, Ethiopia. In addition to BLL analysis, data on some risk factors such as smoking, and chewing ‘khat’ (the leaves of Catha adulis) were gathered through structured questionnaires and interviews and data analysis was performed using SPSS (version 16). The t-test was used to compare mean BLLs of study groups. The analysis of variance (ANOVA), Kruskal-Wallis, Pearson chi-square and odds ratio tests were used to investigate the associations between specific job type, smoking and/or ‘kha...
Background: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting inse... more Background: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. Methodology/Principal findings: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr) and insensitive acetylcholinesterase (ace-1R) mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dw...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5 % in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2) ranging 0.97 to 0.99. The adsorption capacities (qm) of S3, S2 and S1 calculated by using th...
BACKGROUND: As breast milk is normally the only source of food in the early stages of life, the d... more BACKGROUND: As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and ‘enset ’ based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. METHODS: Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by u...
The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural co... more The abilities of three thermally treated clay soils, S1, S2 and S3, which differed in textural compositions, to remove Cr (VI) from aqueous solutions were evaluated. Removal efficiencies of the clays were found to be influenced by textural composition, pH, initial Cr(VI) concentration, shaking time and adsorbent dose. An increase in the clay content of a clay-based soil by 1 % was found to result in an increase of about 0.5% in Cr(VI) removal. The adsorption of Cr(VI) by the clay-based soils was highest at pH 1 and 2 and, decreased above pH 2. For the lower initial concentrations (5 – 50 mg/L) of Cr(VI), adsorption was observed to increase sharply. A slower increase was observed up to about 75 mg/L and adsorption density remain nearly constant above 75 mg/L. The Cr(VI) adsorption process was better represented by the Langmuir model than by the Freundlich, with correlation coefficients (r 2 ) ranging 0.97 to 0.99. The adsorption capacities (qm) of S3, S2 and S1 calculated by using th...
Background As breast milk is normally the only source of food in the early stages of life, the di... more Background As breast milk is normally the only source of food in the early stages of life, the dietary levels of the essential elements in the milk of lactating mothers are significantly important. Ethiopia is a country of many nations and nationalities with distinct dietary habits. This variation in food habit may result in the variation of the nutritional quality of milk of lactating mothers who live in different part of the country, which in turn may affect the intake of nutrients by breast-fed infants. Therefore, a cross-sectional study of the levels of Ca, Mg, Fe, Zn and Cu in milk of mothers from societies with cereal and ‘enset’ based dietary habits was carried out to assess the influence of maternal diet on the levels of the elements in human milk. Methods Milk samples were collected from 27 voluntary mothers in Jimma and in 18 rural areas of Welkite. Breast milk samples were collected within four days postpartum and the concentrations of the elements were determined by usin...
Http Dx Doi Org 10 1081 Tma 100002217, Aug 19, 2006
ABSTRACT A simple method for the detection and semi-quantitative determination of arsenic compoun... more ABSTRACT A simple method for the detection and semi-quantitative determination of arsenic compounds purgeable by a sweep gas from soil was designed. The results were used to tentatively evaluate the flow of volatile arsenic compounds from the lower reducing to the upper oxidizing zone in arsenic rich soils. About 10 kg of soil, with a total arsenic content of 2980 ± 25 mg kg−1 was purged with nitrogen at a flow rate of 10 ml min−1. The gaseous compounds were trapped in concentrated nitric acid solution, preconcentrated by gentle evaporation at 80°C and the arsenic content was determined by the Hydride Generation Atomic Absorption (HG-AAS) technique. Nitrite interference during detection was overcome by treating the final solution with sulfamic acid for 24 h at the prereduction step. Based on these results it may be reasonably assumed that at 20 ± 1°C from a one hectare area of soil having 15 cm depth in the lower reducing zone an estimated maximum of 1500 mg of arsenic could stream up to the oxidizing zone in one week time due to likely microbial reduction of arsenic. Part of these arsenic coumpounds would enter the atmosphere and the remaining part may get oxidized upon reaching the oxic layer and accumulate there in. The part undergoing oxidation in the oxic layer is suggested to be a factor contributing to the local maximum of arsenic in the 20 cm depth from the surface.
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