The Experts below are selected from a list of 28980 Experts worldwide ranked by ideXlab platform
Ali Reza Khataee - One of the best experts on this subject based on the ideXlab platform.
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application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert butyl ether mtbe by uv h2o2 process
Journal of Hazardous Materials, 2005Co-Authors: D Salari, Nezamaddin Daneshvar, F Aghazadeh, Ali Reza KhataeeAbstract:Abstract During the last two decades, methyl tert -butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H 2 O 2 under UV light illumination (30 W). We studied the influence of the basic operational parameters such as initial concentration of H 2 O 2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H 2 O 2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals ( OH). The Semi-Log Plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order ( E Eo ). Our results showed that MTBE could be treated easily and effectively with the UV/H 2 O 2 process with E Eo value 80 kWh/m 3 /order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.
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photocatalytic degradation of azo dye acid red 14 in water on zno as an alternative catalyst to tio2
Journal of Photochemistry and Photobiology A-chemistry, 2004Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract The degradation of acid red 14 (AR14), commonly used as a textile dye, can be photocatalysed by ZnO. Using advanced oxidation processes (AOPs), zinc oxide appears to be a suitable alternative to TiO2 for water treatment. In this study, a detailed investigation of photocatalytic degradation of acid red 14 is presented. Photodegradation efficiency was small when the photolysis was carried out in the absence of ZnO and it was also negligible in the absence of UV light. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction (K=0.0548 min−1). The effects of some parameters such as pH, amount of photocatalyst, hydrogen peroxide and ethanol concentration were also examined. The addition of proper amount of hydrogen peroxide improved the decolorization, while the excess hydrogen peroxide could quenched the formation of hydroxyl radicals ( OH). As our results indicated that ethanol inhibited the photodegradation of dye, we concluded from the inhibitive effect of ethanol that hydroxyl radicals played a significant role in the photodegradation of dye. This should not undermine direct oxidation caused by positive holes.
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photocatalytic degradation of azo dye acid red 14 in water investigation of the effect of operational parameters
Journal of Photochemistry and Photobiology A-chemistry, 2003Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract Acid Red 14 (AR14), commonly used as a textile dye, could be photocatalytically degraded using TiO 2 suspensions irradiated by a UV-C lamp (30 W). The experiments showed that TiO 2 and UV light had a negligible effect when they were used on their own. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction ( K =1.41×10 −2 min −1 ). The effects of some parameters such as pH, the amount of TiO 2 and initial dye concentration were also examined. The photodegradation of AR14 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol it was deducted that hydroxyl radicals played a significant role in the photodegradation of dye, but a direct oxidation by positive holes was probably not negligible. Accordingly, it could be stated that the complete removal of color, after selecting optimal operational parameters could be achieved in a relatively short time, about 3.5 h.
Nezamaddin Daneshvar - One of the best experts on this subject based on the ideXlab platform.
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application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert butyl ether mtbe by uv h2o2 process
Journal of Hazardous Materials, 2005Co-Authors: D Salari, Nezamaddin Daneshvar, F Aghazadeh, Ali Reza KhataeeAbstract:Abstract During the last two decades, methyl tert -butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H 2 O 2 under UV light illumination (30 W). We studied the influence of the basic operational parameters such as initial concentration of H 2 O 2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H 2 O 2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals ( OH). The Semi-Log Plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order ( E Eo ). Our results showed that MTBE could be treated easily and effectively with the UV/H 2 O 2 process with E Eo value 80 kWh/m 3 /order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.
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photocatalytic degradation of azo dye acid red 14 in water on zno as an alternative catalyst to tio2
Journal of Photochemistry and Photobiology A-chemistry, 2004Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract The degradation of acid red 14 (AR14), commonly used as a textile dye, can be photocatalysed by ZnO. Using advanced oxidation processes (AOPs), zinc oxide appears to be a suitable alternative to TiO2 for water treatment. In this study, a detailed investigation of photocatalytic degradation of acid red 14 is presented. Photodegradation efficiency was small when the photolysis was carried out in the absence of ZnO and it was also negligible in the absence of UV light. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction (K=0.0548 min−1). The effects of some parameters such as pH, amount of photocatalyst, hydrogen peroxide and ethanol concentration were also examined. The addition of proper amount of hydrogen peroxide improved the decolorization, while the excess hydrogen peroxide could quenched the formation of hydroxyl radicals ( OH). As our results indicated that ethanol inhibited the photodegradation of dye, we concluded from the inhibitive effect of ethanol that hydroxyl radicals played a significant role in the photodegradation of dye. This should not undermine direct oxidation caused by positive holes.
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photocatalytic degradation of azo dye acid red 14 in water investigation of the effect of operational parameters
Journal of Photochemistry and Photobiology A-chemistry, 2003Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract Acid Red 14 (AR14), commonly used as a textile dye, could be photocatalytically degraded using TiO 2 suspensions irradiated by a UV-C lamp (30 W). The experiments showed that TiO 2 and UV light had a negligible effect when they were used on their own. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction ( K =1.41×10 −2 min −1 ). The effects of some parameters such as pH, the amount of TiO 2 and initial dye concentration were also examined. The photodegradation of AR14 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol it was deducted that hydroxyl radicals played a significant role in the photodegradation of dye, but a direct oxidation by positive holes was probably not negligible. Accordingly, it could be stated that the complete removal of color, after selecting optimal operational parameters could be achieved in a relatively short time, about 3.5 h.
D Salari - One of the best experts on this subject based on the ideXlab platform.
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application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert butyl ether mtbe by uv h2o2 process
Journal of Hazardous Materials, 2005Co-Authors: D Salari, Nezamaddin Daneshvar, F Aghazadeh, Ali Reza KhataeeAbstract:Abstract During the last two decades, methyl tert -butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H 2 O 2 under UV light illumination (30 W). We studied the influence of the basic operational parameters such as initial concentration of H 2 O 2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H 2 O 2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals ( OH). The Semi-Log Plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order ( E Eo ). Our results showed that MTBE could be treated easily and effectively with the UV/H 2 O 2 process with E Eo value 80 kWh/m 3 /order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.
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photocatalytic degradation of azo dye acid red 14 in water on zno as an alternative catalyst to tio2
Journal of Photochemistry and Photobiology A-chemistry, 2004Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract The degradation of acid red 14 (AR14), commonly used as a textile dye, can be photocatalysed by ZnO. Using advanced oxidation processes (AOPs), zinc oxide appears to be a suitable alternative to TiO2 for water treatment. In this study, a detailed investigation of photocatalytic degradation of acid red 14 is presented. Photodegradation efficiency was small when the photolysis was carried out in the absence of ZnO and it was also negligible in the absence of UV light. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction (K=0.0548 min−1). The effects of some parameters such as pH, amount of photocatalyst, hydrogen peroxide and ethanol concentration were also examined. The addition of proper amount of hydrogen peroxide improved the decolorization, while the excess hydrogen peroxide could quenched the formation of hydroxyl radicals ( OH). As our results indicated that ethanol inhibited the photodegradation of dye, we concluded from the inhibitive effect of ethanol that hydroxyl radicals played a significant role in the photodegradation of dye. This should not undermine direct oxidation caused by positive holes.
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photocatalytic degradation of azo dye acid red 14 in water investigation of the effect of operational parameters
Journal of Photochemistry and Photobiology A-chemistry, 2003Co-Authors: Nezamaddin Daneshvar, D Salari, Ali Reza KhataeeAbstract:Abstract Acid Red 14 (AR14), commonly used as a textile dye, could be photocatalytically degraded using TiO 2 suspensions irradiated by a UV-C lamp (30 W). The experiments showed that TiO 2 and UV light had a negligible effect when they were used on their own. The Semi-Log Plot of dye concentration versus time was linear, suggesting first order reaction ( K =1.41×10 −2 min −1 ). The effects of some parameters such as pH, the amount of TiO 2 and initial dye concentration were also examined. The photodegradation of AR14 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol it was deducted that hydroxyl radicals played a significant role in the photodegradation of dye, but a direct oxidation by positive holes was probably not negligible. Accordingly, it could be stated that the complete removal of color, after selecting optimal operational parameters could be achieved in a relatively short time, about 3.5 h.
Gianfranco Amicosante - One of the best experts on this subject based on the ideXlab platform.
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SOS response in bacteria: Inhibitory activity of lichen secondary metabolites against Escherichia coli RecA protein
'Elsevier BV', 2017Co-Authors: Pierangelo Bellio, Cendron Laura, Letizia Di Pietro, Alisia Mancini, Marisa Piovano, Marcello Nicoletti, Fabrizia Brindelli, Donatella Tondi, Nicola Franceschini, Gianfranco AmicosanteAbstract:RecA is a bacterial multifunctional protein essential to genetic recombination, error-prone replicative bypass of DNA damages and regulation of SOS response. The activation of bacterial SOS response is directly related to the development of intrinsic and/or acquired resistance to antimicrobials. Although recent studies directed towards RecA inactivation via ATP binding inhibition described a variety of micromolar affinity ligands, inhibitors of the DNA binding site are still unknown. Purpose Twenty-seven secondary metabolites classified as anthraquinones, depsides, depsidones, dibenzofurans, diphenyl-butenolides, paraconic acids, pseudo-depsidones, triterpenes and xanthones, were investigated for their ability to inhibit RecA from Escherichia coli. They were isolated in various Chilean regions from 14 families and 19 genera of lichens. Methods The ATP hydrolytic activity of RecA was quantified detecting the generation of free phosphate in solution. The percentage of inhibition was calculated fixing at 100 \ub5M the concentration of the compounds. Deeper investigations were reserved to those compounds showing an inhibition higher than 80%. To clarify the mechanism of inhibition, the Semi-Log Plot of the percentage of inhibition vs. ATP and vs. ssDNA, was evaluated. Results Only nine compounds showed a percentage of RecA inhibition higher than 80% (divaricatic, perlatolic, alpha-collatolic, lobaric, lichesterinic, protolichesterinic, epiphorellic acids, sphaerophorin and tumidulin). The half-inhibitory concentrations (IC50) calculated for these compounds were ranging from 14.2 \ub5M for protolichesterinic acid to 42.6 \ub5M for sphaerophorin. Investigations on the mechanism of inhibition showed that all compounds behaved as uncompetitive inhibitors for ATP binding site, with the exception of epiphorellic acid which clearly acted as non-competitive inhibitor of the ATP site. Further investigations demonstrated that epiphorellic acid competitively binds the ssDNA binding site. Kinetic data were confirmed by molecular modelling binding predictions which shows that epiphorellic acid is expected to bind the ssDNA site into the L2 loop of RecA protein. Conclusion In this paper the first RecA ssDNA binding site ligand is described. Our study sets epiphorellic acid as a promising hit for the development of more effective RecA inhibitors. In our drug discovery approach, natural products in general and lichen in particular, represent a successful source of active ligands and structural diversity
Amicosante Gianfranco - One of the best experts on this subject based on the ideXlab platform.
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SOS response in bacteria: inhibitory activity of lichen secondary metabolites against Escherichia coli RecA protein
'Elsevier BV', 2017Co-Authors: Bellio Pierangelo, Tondi Donatella, Cendron Laura, Di Pietro Letizia, Mancini Alisia, Piovano Marisa, Nicoletti Marcello, Brisdelli Fabrizia, Franceschini Nicola, Amicosante GianfrancoAbstract:Abstract Background RecA is a bacterial multifunctional protein essential to genetic recombination, error-prone replicative bypass of DNA damages and regulation of SOS response. The activation of bacterial SOS response is directly related to the development of intrinsic and/or acquired resistance to antimicrobials. Although, recent studies directed towards RecA inactivation via ATP binding inhibition described a variety of micromolar affinity ligands, inhibitors of the DNA binding site are still unknown. Purpose Twenty-seven secondary metabolites classified as anthraquinones, depsides, depsidones, dibenzofurans, diphenyl-butenolides, paraconic acids, pseudo-depsidones, triterpenes and xanthones, were investigated for their ability to inhibit RecA from Escherichia coli. They were isolated in various Chilean regions from 14 families and 19 genera of lichens. Methods The ATP hydrolytic activity of RecA was quantified detecting the generation of free phosphate in solution. The percentage of inhibition was calculated fixing at 100 \ub5M the concentration of the compounds. Deeper investigations were reserved to those compounds showing an inhibition higher than 80%. To clarify the mechanism of inhibition, the Semi-Log Plot of the percentage of inhibition versus ATP and versus ssDNA, was evaluated. Results Only nine compounds showed a percentage of RecA inhibition higher than 80% (divaricatic, perlatolic, alpha-collatolic, lobaric, lichesterinic, protolichesterinic, epiphorellic acids, sphaerophorin and tumidulin). The half-inhibitory concentrations (IC50) calculated for these compounds were ranging from 14.2 \ub5M for protolichesterinic acid to 42.6 \ub5M for sphaerophorin. Investigations on the mechanism of inhibition showed that all compounds behaved as uncompetitive inhibitors for ATP binding site, with the exception of epiphorellic acid which clearly acted as non-competitive inhibitor of the ATP site. Further investigations demonstrated that epiphorellic acid competitively binds the ssDNA binding site. Kinetic data were confirmed by molecular modelling binding predictions which shows that epiphorellic acid is expected to bind the ssDNA site into the L2 loop of RecA protein. Conclusion In this paper is describe the first RecA ssDNA binding site ligand. Our study set epiphorellic acid as a promising hit for the development of more effective RecA inhibitors. In our drug discovery approach natural products in general and lichen specifically, represent a successful source of active ligands and structural diversity
