St.Tilahun Belayneh - Academia.edu (original) (raw)
Papers by St.Tilahun Belayneh
The coffee cherry process generates huge amounts of byproducts which are disposed of on the land,... more The coffee cherry process generates huge amounts of byproducts which are disposed of on the land, causing a serious environmental problem. The coffee cherry husk is one of the main byproducts generated from dry coffee processing, which contains many high-value and exhibits antioxidative and antimicrobial properties biomolecules including phenols, tannins and flavonoids. The primary goal of this study was to investigate the effects of roasting temperatures (150–200 °C) and times (10–25 minutes) on the yield, total phenol, tannin, and flavonoid content, as well as the antioxidant and antimicrobial capacity of an ethanol extract obtained from the coffee cherry husk using an automatic solvent extractor. In this study, the extract yield, total phenol and flavonoid content, as well as the antioxidant and antimicrobial capacity of roasted coffee cherry husk extract were enhanced by roasting. The extract yield ranged between 6.22 ± 0.08–16.37 ± 0.61%. The total phenol and flavonoid content ...
Sustainability
This study aimed to investigate selected bioactive components in three underutilized wild edible ... more This study aimed to investigate selected bioactive components in three underutilized wild edible exotic fruits (Syzygium guineense Wild. DC, Ziziphus spina-christi L., and Citrus medica L.), using high-performance thin-layer chromatography and ultraviolet-visible spectrophotometry (HPTLC-UV-Vis), treated under three drying conditions. Ultrasound-assisted extraction was used to extract the target bioactive components under specified conditions, i.e., time of 15 min, temperature of 35 °C, methanol and water 75/25, v/v, and fruit powder-to-solvent ratio of 1:15, w/v. The mobile phase ratio for rutin, kaempferol, myricetin, and quercetin was toluene/ethylacetate/methanol/formic acid at 20:12:8:4, whereas, for phenolic acids, the ratio was 10:15:10:5, respectively. The HPTLC plates were scanned to identify and quantify selected compounds (phenolic acids, quercetin, rutin, myricetin, and kaempferol) at their maximum optimized absorption wavelengths. The contents of target bioactive compon...
The coffee cherry process generates huge amounts of byproducts which are disposed of on the land,... more The coffee cherry process generates huge amounts of byproducts which are disposed of on the land, causing a serious environmental problem. The coffee cherry husk is one of the main byproducts generated from dry coffee processing, which contains many high-value and exhibits antioxidative and antimicrobial properties biomolecules including phenols, tannins and flavonoids. The primary goal of this study was to investigate the effects of roasting temperatures (150–200 °C) and times (10–25 minutes) on the yield, total phenol, tannin, and flavonoid content, as well as the antioxidant and antimicrobial capacity of an ethanol extract obtained from the coffee cherry husk using an automatic solvent extractor. In this study, the extract yield, total phenol and flavonoid content, as well as the antioxidant and antimicrobial capacity of roasted coffee cherry husk extract were enhanced by roasting. The extract yield ranged between 6.22 ± 0.08–16.37 ± 0.61%. The total phenol and flavonoid content ...
Biochemical Systematics and Ecology, 2019
Two phenolic acids (1 and 2) and seven flavonoids (3-9) were isolated from the aerial parts of Al... more Two phenolic acids (1 and 2) and seven flavonoids (3-9) were isolated from the aerial parts of Alyssum alyssoides (Brassicaceae). All these compounds (1-9) were isolated from this particular species for the first time. Their structures were identified, on the basis of MS and NMR spectra as: p-hydroxy-benzoic acid (1), 3-methoxy-4hydroxybenzoic acid (vanillic acid) (2), kaempferol 3-O-β-D-glucopyranoside (astragalin) (3), kaempferol 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (nicotiflorin) (4), quercetin 3-O-β-D-glucopyranoside (isoquercetin) (5), quercetin 3-O-β-D-galactopyranoside (hyperoside) (6), isorhamnetin 3-O-β-D-glucopyranoside (7), isorhamnetin 3-O-β-D-galactopyranoside (8) and isorhamnetin 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (narcissin) (9). The chemotaxonomic significance of these compounds was summarized.
Background Dodonaea angustifolia is a known medicinal plant across East Arica. The flower of D. a... more Background Dodonaea angustifolia is a known medicinal plant across East Arica. The flower of D. angustifolia is not well investigated in terms of phytochemistry and biological activities. This study aims to investigate the presence of flavonoids and phenolic acid in the flower of D. angustifolia and its antioxidant activity. Methods Preliminary phytochemical screening was carried out using standard protocols. Antioxidant activity evaluation using DPPH assay and total phenol content (TPC) and total flavonoid content (TFC) determinations in the flower extract was compared with the values of the leaf extract. UHPLC–DAD analysis was managed to develop the profile of the flower extract. Prediction of biological activity spectra for substances (PASS) was done using an online server for antioxidant and related activities. Results Preliminary phytochemical screening, TPC, and TFC values confirmed the presence of flavonoids and phenolic acids. From HPLC analysis of flavonoids: quercetin, myr...
CRC Press eBooks, May 9, 2022
The Analyst, 2019
Paper based electrochemical sensors (PESs) are simple, low-cost, portable and disposable analytic... more Paper based electrochemical sensors (PESs) are simple, low-cost, portable and disposable analytical sensing platforms that can be applied in clinical diagnostics, food quality control and environmental monitoring.
Advances in Chemistry, 2017
This research paper deals with the determination of total chromium (total Cr), Cr(III), and Cr(VI... more This research paper deals with the determination of total chromium (total Cr), Cr(III), and Cr(VI) in Kombolcha leather industrial wastewater and the surrounding (soil and lettuce plant) samples where the wastewater flows. The levels of total Cr, Cr(VI), and Cr(III) in wastewater, soil, and lettuce plant samples were determined by FAAS, UV/Vis spectrophotometer, and difference (Cr(VI) from total Cr), respectively. Among all samples taken, the maximum amounts of total Cr, Cr(III), and Cr(VI) were obtained at the discharging point and the minimum amounts of total Cr and Cr(III) were found downstream (400 m from the junction) of Kombolcha leather industrial wastewater. On the other hand, the minimum concentration of Cr(VI) was obtained in lettuce plant sample. The amounts of total Cr in all samples except soil sample were above the permissible limit as set by WHO/FAO. The concentrations of Cr(III) in all wastewater samples were above the permissible level, whereas the concentration of ...
Advanced Materials Research, 2012
A new model is developed for a cascade of four hydropower reservoirs operation. The aim is to imp... more A new model is developed for a cascade of four hydropower reservoirs operation. The aim is to improve the total power generation from the system. Daily data of reservoir level, release and power generated which varies from 4-20 years are used for analysis. Long-term data of reservoir level and inflow are used to determine the critical period. The critical period is classified into four seasons; these are filling, depleting, upper and lower level operating season. Mathematical models are used to rank the refill and the deplete order of the reservoirs. A new rule models are presented using the results of refill and depletion ranks. Power generation using the developed model is compared to the long-term historical generated; and it is found that the new rule model boost the daily power production by 5.3% and the plant factor by 2%.
2011 National Postgraduate Conference, 2011
Operating rule model of a cascade of four hydroelectric power reservoirs was revised using a newl... more Operating rule model of a cascade of four hydroelectric power reservoirs was revised using a newly developed stage-area and stage-storage relationships. Stage-area relation is the basis for the development stage-storage relation. The basic concept that used to develop stage-area was the change in area with change in stage is proportional to stage. Simpson one-third numerical integration method is used to compute the net storage volume between stages. The result was verified and used to model the operation of the cascading system. The aim of developing a new operating rule model was to improve the total annual power generation from the system. Critical period studied using long-term daily reservoir level and inflow data, it showed that the length of critical period is equal to calendar year. Four important seasons were involving in the period; these are refill, deplete upper and lower operating level. Mathematical models were used to rank the refill and the deplete order of the reservoirs. Seasonally operating rule model was developed using the results of refill and depletion rankings. The power generated based on the developed model was compared to the long-term historically generated; and it found that the new rule model boosted the daily power production by 5.3% (12 MW per day), and the plant factor by 2%.
Advanced Materials Research, 2012
The cascading reservoirs in Perak, Malaysia, were used to test the sensitivity analysis of hydroe... more The cascading reservoirs in Perak, Malaysia, were used to test the sensitivity analysis of hydroelectric power generation during refill and deplete period of the reservoirs. The cascading scheme comprises four reservoirs namely Temenggor, Bersia, Kenering and Chenderoh. The test was conducted after the analysis of water balance and stage-storage relationship of each reservoir in the cascading scheme. The result showed that power generation from the smaller reservoir, Bersia, is more sensitive to the change of headrace level, while the larger storage capacity and rated head reservoir is the most sensitive to the change of release. Therefore, to maximize the power generation from the cascading reservoir, the refill operations should be ranked according to the increasing order of the reservoir storage capacity and a reverse order should be followed during deplete period.
Herbs, Shrubs, and Trees of Potential Medicinal Benefits
The coffee cherry process generates huge amounts of byproducts which are disposed of on the land,... more The coffee cherry process generates huge amounts of byproducts which are disposed of on the land, causing a serious environmental problem. The coffee cherry husk is one of the main byproducts generated from dry coffee processing, which contains many high-value and exhibits antioxidative and antimicrobial properties biomolecules including phenols, tannins and flavonoids. The primary goal of this study was to investigate the effects of roasting temperatures (150–200 °C) and times (10–25 minutes) on the yield, total phenol, tannin, and flavonoid content, as well as the antioxidant and antimicrobial capacity of an ethanol extract obtained from the coffee cherry husk using an automatic solvent extractor. In this study, the extract yield, total phenol and flavonoid content, as well as the antioxidant and antimicrobial capacity of roasted coffee cherry husk extract were enhanced by roasting. The extract yield ranged between 6.22 ± 0.08–16.37 ± 0.61%. The total phenol and flavonoid content ...
Sustainability
This study aimed to investigate selected bioactive components in three underutilized wild edible ... more This study aimed to investigate selected bioactive components in three underutilized wild edible exotic fruits (Syzygium guineense Wild. DC, Ziziphus spina-christi L., and Citrus medica L.), using high-performance thin-layer chromatography and ultraviolet-visible spectrophotometry (HPTLC-UV-Vis), treated under three drying conditions. Ultrasound-assisted extraction was used to extract the target bioactive components under specified conditions, i.e., time of 15 min, temperature of 35 °C, methanol and water 75/25, v/v, and fruit powder-to-solvent ratio of 1:15, w/v. The mobile phase ratio for rutin, kaempferol, myricetin, and quercetin was toluene/ethylacetate/methanol/formic acid at 20:12:8:4, whereas, for phenolic acids, the ratio was 10:15:10:5, respectively. The HPTLC plates were scanned to identify and quantify selected compounds (phenolic acids, quercetin, rutin, myricetin, and kaempferol) at their maximum optimized absorption wavelengths. The contents of target bioactive compon...
The coffee cherry process generates huge amounts of byproducts which are disposed of on the land,... more The coffee cherry process generates huge amounts of byproducts which are disposed of on the land, causing a serious environmental problem. The coffee cherry husk is one of the main byproducts generated from dry coffee processing, which contains many high-value and exhibits antioxidative and antimicrobial properties biomolecules including phenols, tannins and flavonoids. The primary goal of this study was to investigate the effects of roasting temperatures (150–200 °C) and times (10–25 minutes) on the yield, total phenol, tannin, and flavonoid content, as well as the antioxidant and antimicrobial capacity of an ethanol extract obtained from the coffee cherry husk using an automatic solvent extractor. In this study, the extract yield, total phenol and flavonoid content, as well as the antioxidant and antimicrobial capacity of roasted coffee cherry husk extract were enhanced by roasting. The extract yield ranged between 6.22 ± 0.08–16.37 ± 0.61%. The total phenol and flavonoid content ...
Biochemical Systematics and Ecology, 2019
Two phenolic acids (1 and 2) and seven flavonoids (3-9) were isolated from the aerial parts of Al... more Two phenolic acids (1 and 2) and seven flavonoids (3-9) were isolated from the aerial parts of Alyssum alyssoides (Brassicaceae). All these compounds (1-9) were isolated from this particular species for the first time. Their structures were identified, on the basis of MS and NMR spectra as: p-hydroxy-benzoic acid (1), 3-methoxy-4hydroxybenzoic acid (vanillic acid) (2), kaempferol 3-O-β-D-glucopyranoside (astragalin) (3), kaempferol 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (nicotiflorin) (4), quercetin 3-O-β-D-glucopyranoside (isoquercetin) (5), quercetin 3-O-β-D-galactopyranoside (hyperoside) (6), isorhamnetin 3-O-β-D-glucopyranoside (7), isorhamnetin 3-O-β-D-galactopyranoside (8) and isorhamnetin 3-O-(6″-α-L-rhamnopyranosyl)-β-D-glucopyranoside (narcissin) (9). The chemotaxonomic significance of these compounds was summarized.
Background Dodonaea angustifolia is a known medicinal plant across East Arica. The flower of D. a... more Background Dodonaea angustifolia is a known medicinal plant across East Arica. The flower of D. angustifolia is not well investigated in terms of phytochemistry and biological activities. This study aims to investigate the presence of flavonoids and phenolic acid in the flower of D. angustifolia and its antioxidant activity. Methods Preliminary phytochemical screening was carried out using standard protocols. Antioxidant activity evaluation using DPPH assay and total phenol content (TPC) and total flavonoid content (TFC) determinations in the flower extract was compared with the values of the leaf extract. UHPLC–DAD analysis was managed to develop the profile of the flower extract. Prediction of biological activity spectra for substances (PASS) was done using an online server for antioxidant and related activities. Results Preliminary phytochemical screening, TPC, and TFC values confirmed the presence of flavonoids and phenolic acids. From HPLC analysis of flavonoids: quercetin, myr...
CRC Press eBooks, May 9, 2022
The Analyst, 2019
Paper based electrochemical sensors (PESs) are simple, low-cost, portable and disposable analytic... more Paper based electrochemical sensors (PESs) are simple, low-cost, portable and disposable analytical sensing platforms that can be applied in clinical diagnostics, food quality control and environmental monitoring.
Advances in Chemistry, 2017
This research paper deals with the determination of total chromium (total Cr), Cr(III), and Cr(VI... more This research paper deals with the determination of total chromium (total Cr), Cr(III), and Cr(VI) in Kombolcha leather industrial wastewater and the surrounding (soil and lettuce plant) samples where the wastewater flows. The levels of total Cr, Cr(VI), and Cr(III) in wastewater, soil, and lettuce plant samples were determined by FAAS, UV/Vis spectrophotometer, and difference (Cr(VI) from total Cr), respectively. Among all samples taken, the maximum amounts of total Cr, Cr(III), and Cr(VI) were obtained at the discharging point and the minimum amounts of total Cr and Cr(III) were found downstream (400 m from the junction) of Kombolcha leather industrial wastewater. On the other hand, the minimum concentration of Cr(VI) was obtained in lettuce plant sample. The amounts of total Cr in all samples except soil sample were above the permissible limit as set by WHO/FAO. The concentrations of Cr(III) in all wastewater samples were above the permissible level, whereas the concentration of ...
Advanced Materials Research, 2012
A new model is developed for a cascade of four hydropower reservoirs operation. The aim is to imp... more A new model is developed for a cascade of four hydropower reservoirs operation. The aim is to improve the total power generation from the system. Daily data of reservoir level, release and power generated which varies from 4-20 years are used for analysis. Long-term data of reservoir level and inflow are used to determine the critical period. The critical period is classified into four seasons; these are filling, depleting, upper and lower level operating season. Mathematical models are used to rank the refill and the deplete order of the reservoirs. A new rule models are presented using the results of refill and depletion ranks. Power generation using the developed model is compared to the long-term historical generated; and it is found that the new rule model boost the daily power production by 5.3% and the plant factor by 2%.
2011 National Postgraduate Conference, 2011
Operating rule model of a cascade of four hydroelectric power reservoirs was revised using a newl... more Operating rule model of a cascade of four hydroelectric power reservoirs was revised using a newly developed stage-area and stage-storage relationships. Stage-area relation is the basis for the development stage-storage relation. The basic concept that used to develop stage-area was the change in area with change in stage is proportional to stage. Simpson one-third numerical integration method is used to compute the net storage volume between stages. The result was verified and used to model the operation of the cascading system. The aim of developing a new operating rule model was to improve the total annual power generation from the system. Critical period studied using long-term daily reservoir level and inflow data, it showed that the length of critical period is equal to calendar year. Four important seasons were involving in the period; these are refill, deplete upper and lower operating level. Mathematical models were used to rank the refill and the deplete order of the reservoirs. Seasonally operating rule model was developed using the results of refill and depletion rankings. The power generated based on the developed model was compared to the long-term historically generated; and it found that the new rule model boosted the daily power production by 5.3% (12 MW per day), and the plant factor by 2%.
Advanced Materials Research, 2012
The cascading reservoirs in Perak, Malaysia, were used to test the sensitivity analysis of hydroe... more The cascading reservoirs in Perak, Malaysia, were used to test the sensitivity analysis of hydroelectric power generation during refill and deplete period of the reservoirs. The cascading scheme comprises four reservoirs namely Temenggor, Bersia, Kenering and Chenderoh. The test was conducted after the analysis of water balance and stage-storage relationship of each reservoir in the cascading scheme. The result showed that power generation from the smaller reservoir, Bersia, is more sensitive to the change of headrace level, while the larger storage capacity and rated head reservoir is the most sensitive to the change of release. Therefore, to maximize the power generation from the cascading reservoir, the refill operations should be ranked according to the increasing order of the reservoir storage capacity and a reverse order should be followed during deplete period.
Herbs, Shrubs, and Trees of Potential Medicinal Benefits