The primary objective of this article is to investigate how survival modelling can be used in traffic accident analysis to explain driver accident risk factors. Accident records of 398 drivers from 2007 to 2009 were obtained from Motor Traffic and Transport Department (MTTD), Ghana Police Service, Northern region. Cox proportional regression model was employed for the analysis using the SAS package. The conclusion was that Survival modelling promises to be a useful tool for road safety analysis and the most significant variables to the risks of accident were driver characteristics (age, gender, experience), their behaviour in traffic (speed, use of alcohol, use of safety belt), the nature of exposure (annual kilometreage, road surface condition) and vehicle characteristics (vehicle age, weight, tyres condition). Implementation of the findings of this study will enable policy makers put up better measures to reduce accident occurrence in the region in particular and the country as a whole. Key words: Cox proportional model, accident risks, annual vehicle kilometreage, survival modelling, SAS package.
{"title":"Survival modeling of accident risks of vehicle drivers in Northern Region of Ghana","authors":"A. Faisal, M. Diedhiou, Katara Salifu","doi":"10.5897/SRE2017.6549","DOIUrl":"https://doi.org/10.5897/SRE2017.6549","url":null,"abstract":"The primary objective of this article is to investigate how survival modelling can be used in traffic accident analysis to explain driver accident risk factors. Accident records of 398 drivers from 2007 to 2009 were obtained from Motor Traffic and Transport Department (MTTD), Ghana Police Service, Northern region. Cox proportional regression model was employed for the analysis using the SAS package. The conclusion was that Survival modelling promises to be a useful tool for road safety analysis and the most significant variables to the risks of accident were driver characteristics (age, gender, experience), their behaviour in traffic (speed, use of alcohol, use of safety belt), the nature of exposure (annual kilometreage, road surface condition) and vehicle characteristics (vehicle age, weight, tyres condition). Implementation of the findings of this study will enable policy makers put up better measures to reduce accident occurrence in the region in particular and the country as a whole. \u0000 \u0000 \u0000 \u0000 Key words: Cox proportional model, accident risks, annual vehicle kilometreage, survival modelling, SAS package.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"13 1","pages":"27-43"},"PeriodicalIF":0.0,"publicationDate":"2018-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6549","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46938196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The precipitation concentration index (PCI) of Indian region using monthly data for 1951 to 2015 was estimated on an annual and seasonal scale to show the changes in temporal and spatial distribution of rainfall over the 34 meteorological sub-divisions. As a result, annual values of PCI showed more erratic nature than the uniform to moderate behaviour of seasonal (Jun-Sept) PCI values. Computation of PCI will be useful in hydrological, water resources as well as flood and drought management programs. As floods are more common in north and northeast India, PCI may serve as a warning tool in disaster control management in relation to floods and soil erosion since PCI can help in the analysis of soil erosion and in the calculation of erodibility of land and loss of soil due to it. Key words: Temporal and spatial distribution of rainfall, precipitation concentration index, meteorological sub-divisions of India, floods and erosion.
{"title":"Precipitation concentration changes over India during 1951 to 2015","authors":"S. Nandargi S., Aman K.","doi":"10.5897/SRE2017.6540","DOIUrl":"https://doi.org/10.5897/SRE2017.6540","url":null,"abstract":"The precipitation concentration index (PCI) of Indian region using monthly data for 1951 to 2015 was estimated on an annual and seasonal scale to show the changes in temporal and spatial distribution of rainfall over the 34 meteorological sub-divisions. As a result, annual values of PCI showed more erratic nature than the uniform to moderate behaviour of seasonal (Jun-Sept) PCI values. Computation of PCI will be useful in hydrological, water resources as well as flood and drought management programs. As floods are more common in north and northeast India, PCI may serve as a warning tool in disaster control management in relation to floods and soil erosion since PCI can help in the analysis of soil erosion and in the calculation of erodibility of land and loss of soil due to it. \u0000 \u0000 Key words: Temporal and spatial distribution of rainfall, precipitation concentration index, meteorological sub-divisions of India, floods and erosion.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"13 1","pages":"14-26"},"PeriodicalIF":0.0,"publicationDate":"2018-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6540","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42511394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Teklay, G. Gebeyehu, T. Getachew, T. Yaynshet, S. Inbasekaran, T. Sastry
Leather sector in Ethiopia is blessed with huge livestock resource which serves as source of raw material (hides and skin), cheap and highly disciplined workforce, cheap cost of doing business, significant international comparative advantages, investment incentives, and custom duty exemption. This industry remains a supplier of low value added, semi- processed hides and skin to the international market. leather sheet of wonderful strength (9.84±0.16 MPa) and very reasonable elongation at break (31.40%) having amenable use was prepared and the production of this value added products from waste material is a reasonable task of the time that scholars should do as it can serve as means of income besides its advantage to reduce environmental pollution specially in countries like Ethiopia which, have untapped solid waste leather resource. Key words: Solid waste, leather fiber, latex, Ethiopia.
{"title":"Preparation of value added composite sheet from solid waste leather - A prototype design","authors":"A. Teklay, G. Gebeyehu, T. Getachew, T. Yaynshet, S. Inbasekaran, T. Sastry","doi":"10.5897/SRE2017.6551","DOIUrl":"https://doi.org/10.5897/SRE2017.6551","url":null,"abstract":"Leather sector in Ethiopia is blessed with huge livestock resource which serves as source of raw material (hides and skin), cheap and highly disciplined workforce, cheap cost of doing business, significant international comparative advantages, investment incentives, and custom duty exemption. This industry remains a supplier of low value added, semi- processed hides and skin to the international market. leather sheet of wonderful strength (9.84±0.16 MPa) and very reasonable elongation at break (31.40%) having amenable use was prepared and the production of this value added products from waste material is a reasonable task of the time that scholars should do as it can serve as means of income besides its advantage to reduce environmental pollution specially in countries like Ethiopia which, have untapped solid waste leather resource. \u0000 \u0000 Key words: Solid waste, leather fiber, latex, Ethiopia.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"13 1","pages":"11-13"},"PeriodicalIF":0.0,"publicationDate":"2018-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6551","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46669667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Benzina Farida, Hamid Sonia, Mohand-Kaci Hakima, Bissaad Fatma, H. Fatma
The Culicidae are biting insects that are most harmful to people. They are almost all blood-suckers, and are responsible for the spread of many important diseases such as malaria, yellow fever and elephantiasis. Entomopathogenic microorganisms occupy an important place among the alternative methods of fighting against pests insect. The fungus, Beauveria bassiana is an entomopathogenic agent naturally present in the ecosystems and offers a very interesting potential for controlling populations of mosquitoes. Our study aims at showing the 4th stage larvae histological changes of the domestic mosquito Culex pipiens, treated with the entomopathogenic fungus B. bassiana in suspension which corresponds to a dose of 107 spore/mL. In fact, after developing the individuals in the fungal solution, histological study was carried out on the following parts; cuticle, intestine, adipose tissue and hemolymph. The histological studies showed many alterations and malformation in the treated 4th instar larvae body and tissues. The infection affected the different parts of the body, especially the cuticle, the adipose cells, and midgut, in addition to the development and the colonization of B. bassiana inside tissues. The application of B. bassiana on the cuticle of the larvae was dependent on an apparent disturbance in the structure of the cuticle or the degeneration of its different parts. The fungus infection does not stop at the level of the body walls, so it even goes to adipose tissue, epidermal cells and intestine. Based on these results, B. bassiana could be suggested as suitable biocontrol agent against C. pipiens. Key words: Beauveria bassiana, Culex pipiens, cuticle, histological study, midgut, adipose tissue.
{"title":"Histological changes in the larvae of the domestic mosquito Culex pipiens treated with the entomopathogenic fungus Beauveria bassiana","authors":"Benzina Farida, Hamid Sonia, Mohand-Kaci Hakima, Bissaad Fatma, H. Fatma","doi":"10.5897/SRE2017.6544","DOIUrl":"https://doi.org/10.5897/SRE2017.6544","url":null,"abstract":"The Culicidae are biting insects that are most harmful to people. They are almost all blood-suckers, and are responsible for the spread of many important diseases such as malaria, yellow fever and elephantiasis. Entomopathogenic microorganisms occupy an important place among the alternative methods of fighting against pests insect. The fungus, Beauveria bassiana is an entomopathogenic agent naturally present in the ecosystems and offers a very interesting potential for controlling populations of mosquitoes. Our study aims at showing the 4th stage larvae histological changes of the domestic mosquito Culex pipiens, treated with the entomopathogenic fungus B. bassiana in suspension which corresponds to a dose of 107 spore/mL. In fact, after developing the individuals in the fungal solution, histological study was carried out on the following parts; cuticle, intestine, adipose tissue and hemolymph. The histological studies showed many alterations and malformation in the treated 4th instar larvae body and tissues. The infection affected the different parts of the body, especially the cuticle, the adipose cells, and midgut, in addition to the development and the colonization of B. bassiana inside tissues. The application of B. bassiana on the cuticle of the larvae was dependent on an apparent disturbance in the structure of the cuticle or the degeneration of its different parts. The fungus infection does not stop at the level of the body walls, so it even goes to adipose tissue, epidermal cells and intestine. Based on these results, B. bassiana could be suggested as suitable biocontrol agent against C. pipiens. \u0000 \u0000 \u0000 \u0000 Key words: Beauveria bassiana, Culex pipiens, cuticle, histological study, midgut, adipose tissue.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"13 1","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2018-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6544","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43503473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yutaka Andoh, Kengo Omura, T. Kentaro, Kawamoto Koushi, T. Fujinami
The purpose of this study was twofold. First, extent of the influence of flyer layouts on user impressions was investigated. Data were collected from 425 non-designers. The participants, consisting of eight groups of men and women between the ages of 20 and 50, were shown 60 flyers (12 layouts × five other design features) of a piano concert on a computer screen. The percentage of layout contribution to user impression, estimated by the ranges of category scores, was under 20%. This result indicates that layouts have a relatively small influence on impressions. Second, using dual scaling, layouts which had an influence on the variety of impressions was confirmed. The analysis produced X/Y dimensions where the first dimension (X-axis) indicated “formal-casual” and the second dimension (Y-axis) indicated “powerful-delicate.” It was suggested that the degree of alignment enhanced a formal impression, while the degree of symmetry enhanced a powerful impression. Key words: Layout, flyer, user impression, document design.
{"title":"Influence of layouts on visual impression: Comparing 12 flyer layout patterns","authors":"Yutaka Andoh, Kengo Omura, T. Kentaro, Kawamoto Koushi, T. Fujinami","doi":"10.5897/SRE2017.6511","DOIUrl":"https://doi.org/10.5897/SRE2017.6511","url":null,"abstract":"The purpose of this study was twofold. First, extent of the influence of flyer layouts on user impressions was investigated. Data were collected from 425 non-designers. The participants, consisting of eight groups of men and women between the ages of 20 and 50, were shown 60 flyers (12 layouts × five other design features) of a piano concert on a computer screen. The percentage of layout contribution to user impression, estimated by the ranges of category scores, was under 20%. This result indicates that layouts have a relatively small influence on impressions. Second, using dual scaling, layouts which had an influence on the variety of impressions was confirmed. The analysis produced X/Y dimensions where the first dimension (X-axis) indicated “formal-casual” and the second dimension (Y-axis) indicated “powerful-delicate.” It was suggested that the degree of alignment enhanced a formal impression, while the degree of symmetry enhanced a powerful impression. \u0000 \u0000 \u0000 \u0000 Key words: Layout, flyer, user impression, document design.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"200-207"},"PeriodicalIF":0.0,"publicationDate":"2017-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44019929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Unreliability in the assumption of soil properties, selection of elapse time, choice of time step size and atmospheric variables causes most inconsistencies in the simulation results. Therefore, time step size studied was based on root water up-take on a single Lime tree on a Boulder Clay. The effects of ¼, ½ and 1 day time step sizes on generated capillary potential at 0.0 m, 1.4 m and 3.0 m from the lime tree for elapse time of 30, 90, 190 and 270 days elapsed time were studied. A straightforward sink term for root water uptake was used and combined with two-dimensional axi-symmetric governing equation for unsaturated soil. The simulated capillary potential was directly proportional to the elapsed time. The time step sizes studied were found to give the same generated capillary potentials at same spacial distances. The idea was to investigate the generated capillary potentials at ¼, ½ and 1 days time steps sizes at a same spatial distance from the Lime tree on a Boulder Clay should be the same. Consequently, the difference in the results generated with the three initial time step sizes were far less than ±5%, which is satisfactory. Key words: Unsaturated soil, boundary condition, capillary potential, spatial discretization, time discretization.
{"title":"Time step-size on simulation of tree-induced capillary potential in unsaturated soils","authors":"M. Abdullahi","doi":"10.5897/SRE2017.6543","DOIUrl":"https://doi.org/10.5897/SRE2017.6543","url":null,"abstract":"Unreliability in the assumption of soil properties, selection of elapse time, choice of time step size and atmospheric variables causes most inconsistencies in the simulation results. Therefore, time step size studied was based on root water up-take on a single Lime tree on a Boulder Clay. The effects of ¼, ½ and 1 day time step sizes on generated capillary potential at 0.0 m, 1.4 m and 3.0 m from the lime tree for elapse time of 30, 90, 190 and 270 days elapsed time were studied. A straightforward sink term for root water uptake was used and combined with two-dimensional axi-symmetric governing equation for unsaturated soil. The simulated capillary potential was directly proportional to the elapsed time. The time step sizes studied were found to give the same generated capillary potentials at same spacial distances. The idea was to investigate the generated capillary potentials at ¼, ½ and 1 days time steps sizes at a same spatial distance from the Lime tree on a Boulder Clay should be the same. Consequently, the difference in the results generated with the three initial time step sizes were far less than ±5%, which is satisfactory. \u0000 \u0000 \u0000 \u0000 Key words: Unsaturated soil, boundary condition, capillary potential, spatial discretization, time discretization.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"188-199"},"PeriodicalIF":0.0,"publicationDate":"2017-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41848253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maria de Sousa Alves Cristiely, Olinto Galvão Alcione, Geraldo Kramer Dany, Ribeiro Barbosa Isabelle, Mendes de Sousa Anesio
Improper disposal of municipal solid waste is a problem in Brazil, especially in the North, as noted in Araguatins, TO and can lead to environmental contamination caused by heavy metals. This study aims to analyze the occurrence of heavy metals in soil and leachate in the landfill of Araguatins, TO, Brazil. Soil samples and manure were collected at different points and stored in plastic containers for later laboratory analysis of heavy metals (Cd, Cu, Ni, Pb and Zn (slurry - atomic absorption spectroscopy)) and soil (ICP-MS). Soil samples have heavy metals concentrations based on the recommended range. The slurry samples had lead, copper and zinc above the permissive range. Key words: Heavy metals, dump, slurry, soil.
{"title":"Determination of heavy metals in landfill area in Tocantins, Brazil","authors":"Maria de Sousa Alves Cristiely, Olinto Galvão Alcione, Geraldo Kramer Dany, Ribeiro Barbosa Isabelle, Mendes de Sousa Anesio","doi":"10.5897/SRE2017.6530","DOIUrl":"https://doi.org/10.5897/SRE2017.6530","url":null,"abstract":"Improper disposal of municipal solid waste is a problem in Brazil, especially in the North, as noted in Araguatins, TO and can lead to environmental contamination caused by heavy metals. This study aims to analyze the occurrence of heavy metals in soil and leachate in the landfill of Araguatins, TO, Brazil. Soil samples and manure were collected at different points and stored in plastic containers for later laboratory analysis of heavy metals (Cd, Cu, Ni, Pb and Zn (slurry - atomic absorption spectroscopy)) and soil (ICP-MS). Soil samples have heavy metals concentrations based on the recommended range. The slurry samples had lead, copper and zinc above the permissive range. \u0000 \u0000 Key words: Heavy metals, dump, slurry, soil.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"163-166"},"PeriodicalIF":0.0,"publicationDate":"2017-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6530","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45340210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Review of literature related to the impact of climate change on maize (Zea mays L.) yield using Global Climate Models (GCMs), statistical downscaling, and crop simulation (APSIM-maize-and-CERES-maize models) models are discussed. GCMs can simulate the current and future climatic scenarios. Crop yield projections using crop models require climate inputs at higher spatial resolution than that provided by GCMs. The computationally inexpensive statistical downscaling technique is widely used for this translation. Studies on regional climate modeling have mostly focused on Southern Africa and West Africa, with very few studies in Zambia. Additionally, the integrated use of climate and crop models have received relatively less attention in Africa compared to other parts of the world. Conversely, the AgMIP protocols have been implemented in Sub-Saharan Africa (SSA) (Ethiopia, Kenya, Tanzania, Uganda and South Africa) and South Asia (SA) (Sri Lanka). In Zambia, however, the protocols have not been applied at either regional or local scale. Applying crop and statistical downscaling models requires calibration and validation, and these are crucial for correct climate and crop simulation. The review shows that although uncertainties exist in the design of models, and parameters, soil, climate and management options, the climate would adversely affect maize yield production in SSA. The potential effect of climate change on maize production can be studied using crop models such as agricultural production simulator (APSIM) and decision support system for agrotechnology (DSSAT) models. There is need to use integrated assessment modeling to study future climate impact on maize yield. The assessment is essential for long-term planning in food security and in developing adaptation and mitigation strategies in the face of climate variability and change. Key words: Review, AgMIP, climate scenario, climate change, variability, crop simulation model, bias correction, dynamical downscaling, Global Climate Model (GCM), statistical downscaling.
{"title":"Climate change impact on maize (Zea mays L.) yield using crop simulation and statistical downscaling models: A review","authors":"Charles Bwalya Chisanga, E. Phiri, V. Chinene","doi":"10.5897/SRE2017.6521","DOIUrl":"https://doi.org/10.5897/SRE2017.6521","url":null,"abstract":"Review of literature related to the impact of climate change on maize (Zea mays L.) yield using Global Climate Models (GCMs), statistical downscaling, and crop simulation (APSIM-maize-and-CERES-maize models) models are discussed. GCMs can simulate the current and future climatic scenarios. Crop yield projections using crop models require climate inputs at higher spatial resolution than that provided by GCMs. The computationally inexpensive statistical downscaling technique is widely used for this translation. Studies on regional climate modeling have mostly focused on Southern Africa and West Africa, with very few studies in Zambia. Additionally, the integrated use of climate and crop models have received relatively less attention in Africa compared to other parts of the world. Conversely, the AgMIP protocols have been implemented in Sub-Saharan Africa (SSA) (Ethiopia, Kenya, Tanzania, Uganda and South Africa) and South Asia (SA) (Sri Lanka). In Zambia, however, the protocols have not been applied at either regional or local scale. Applying crop and statistical downscaling models requires calibration and validation, and these are crucial for correct climate and crop simulation. The review shows that although uncertainties exist in the design of models, and parameters, soil, climate and management options, the climate would adversely affect maize yield production in SSA. The potential effect of climate change on maize production can be studied using crop models such as agricultural production simulator (APSIM) and decision support system for agrotechnology (DSSAT) models. There is need to use integrated assessment modeling to study future climate impact on maize yield. The assessment is essential for long-term planning in food security and in developing adaptation and mitigation strategies in the face of climate variability and change. \u0000 \u0000 \u0000 \u0000 Key words: Review, AgMIP, climate scenario, climate change, variability, crop simulation model, bias correction, dynamical downscaling, Global Climate Model (GCM), statistical downscaling.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"167-187"},"PeriodicalIF":0.0,"publicationDate":"2017-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6521","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45631058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to investigate the effect of sonication on the fatty acids of alga oil, oil of Chlorella vulgaris was extracted by sonication at 20, 40, 60 and 80 kHz. Oil extracted by refluxing alga cells in n-hexane was used as control. Probable changes in the structures of the fatty acids were investigated using gas chromatography and Fourier transform infrared spectroscopy (FT-IR). The retention profiles of the chromatograms were similar with differences observed only in peak heights. The FT-IR spectrum of the hexane extract was similar to the spectra of oil extracted at 20 and 40 kHz. The FT-IR spectra of oil extracted at 60 and 80 kHz were identical but different from the other spectra. Peaks at about 1560 cm-1 which were prominent in the 60 and 80 kHz spectra but absent from the other spectra were assigned to non-oil lipids such as steroids. It was concluded that extraction of oil from C. vulgaris by sonication at 20, 40, 60 and 80 kHz had no degradative effect on the structure of the fatty acids of C. vulgaris. Key words: Alga, triglycerides, extraction, sonication, chromatography, spectroscopy.
{"title":"Effect of sonication at different ultrasonic frequencies on the quality and quantity of fatty acids of the oil of Chlorella vulgaris.","authors":"F. A. Olubunmi","doi":"10.5897/SRE2014.6084","DOIUrl":"https://doi.org/10.5897/SRE2014.6084","url":null,"abstract":"In order to investigate the effect of sonication on the fatty acids of alga oil, oil of Chlorella vulgaris was extracted by sonication at 20, 40, 60 and 80 kHz. Oil extracted by refluxing alga cells in n-hexane was used as control. Probable changes in the structures of the fatty acids were investigated using gas chromatography and Fourier transform infrared spectroscopy (FT-IR). The retention profiles of the chromatograms were similar with differences observed only in peak heights. The FT-IR spectrum of the hexane extract was similar to the spectra of oil extracted at 20 and 40 kHz. The FT-IR spectra of oil extracted at 60 and 80 kHz were identical but different from the other spectra. Peaks at about 1560 cm-1 which were prominent in the 60 and 80 kHz spectra but absent from the other spectra were assigned to non-oil lipids such as steroids. It was concluded that extraction of oil from C. vulgaris by sonication at 20, 40, 60 and 80 kHz had no degradative effect on the structure of the fatty acids of C. vulgaris. \u0000 \u0000 \u0000 \u0000 Key words: Alga, triglycerides, extraction, sonication, chromatography, spectroscopy.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"155-162"},"PeriodicalIF":0.0,"publicationDate":"2017-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2014.6084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44929144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. B. Kouassi, A. Diawara, K. Kouadio, Fidèle Yoroba, E. Toualy
This study focused on the occurrences and relationships of the Atlantic Cold Tongue (ACT) and the West African Monsoon (WAM) onsets in the Sudano-Sahelian region during 1983-2000. Two simulations (WAFSSTERA and WAFSSTREY) were used to investigate the sensitivity of the Regional Atmospheric Model (MAR) for two different datasets of sea surface temperature (ERA-40 and Reynolds SST datasets). The MAR reproduced the rainfall high values in the Guinean zone. A band of weak precipitation (<1 mm/day) was observed in the two simulations. WAFSSTERA gave more annual daily average rainfall (~1.6 mm/day) than WAFSSTREY. The simulated onset date index (ODI) of WAM showed more northward penetration of monsoon flow, particularly during flood years in the Gulf of Guinea. These results also indicated that the monsoon onset did not depend on the SST dataset used to force the model. Finally, the negative difference between ODIs and ACT onset date could be due to warm SST. The yearly evolution of the southern heat transport was also in agreement with this difference. It showed yearly succession of negative and positive anomalies around 7.5°N (mean rainy equilibrium position over West Africa). Such study could be useful for the forecast of WAM onset and ACT scenario relationships. Key words: Atlantic cold tongue, onset date index, regional climate model, sea surface temperature, West African Monsoon.
{"title":"West African Monsoon (WAM) and Atlantic Cold Tongue (ACT) onsets using Regional Climate Model","authors":"K. B. Kouassi, A. Diawara, K. Kouadio, Fidèle Yoroba, E. Toualy","doi":"10.5897/SRE2017.6525","DOIUrl":"https://doi.org/10.5897/SRE2017.6525","url":null,"abstract":"This study focused on the occurrences and relationships of the Atlantic Cold Tongue (ACT) and the West African Monsoon (WAM) onsets in the Sudano-Sahelian region during 1983-2000. Two simulations (WAFSSTERA and WAFSSTREY) were used to investigate the sensitivity of the Regional Atmospheric Model (MAR) for two different datasets of sea surface temperature (ERA-40 and Reynolds SST datasets). The MAR reproduced the rainfall high values in the Guinean zone. A band of weak precipitation (<1 mm/day) was observed in the two simulations. WAFSSTERA gave more annual daily average rainfall (~1.6 mm/day) than WAFSSTREY. The simulated onset date index (ODI) of WAM showed more northward penetration of monsoon flow, particularly during flood years in the Gulf of Guinea. These results also indicated that the monsoon onset did not depend on the SST dataset used to force the model. Finally, the negative difference between ODIs and ACT onset date could be due to warm SST. The yearly evolution of the southern heat transport was also in agreement with this difference. It showed yearly succession of negative and positive anomalies around 7.5°N (mean rainy equilibrium position over West Africa). Such study could be useful for the forecast of WAM onset and ACT scenario relationships. \u0000 \u0000 Key words: Atlantic cold tongue, onset date index, regional climate model, sea surface temperature, West African Monsoon.","PeriodicalId":21603,"journal":{"name":"Scientific Research and Essays","volume":"12 1","pages":"142-154"},"PeriodicalIF":0.0,"publicationDate":"2017-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5897/SRE2017.6525","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48727505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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