This paper critically reviewed the current knowledge and challenges of rice husk biochar(RHB)production and its effects on soil properties,plant growth,immobilization of heavy metals,reduction of nutrient leaching and...This paper critically reviewed the current knowledge and challenges of rice husk biochar(RHB)production and its effects on soil properties,plant growth,immobilization of heavy metals,reduction of nutrient leaching and mitigation of greenhouse gas emissions.The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro-industrial wastes.RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio,which suggests the presence of higher aromatic carbon compounds.The increase of pyrolysis temperature also results in production of RHBs with higher ash content,lower yield and higher surface area.RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions.Although it depends on soil type,RHB application can improve soil organic carbon content,cation exchange capacity,available K concentration,bulk density and microbial activity.The effect of RHB on soil aggregation mainly depends on soil texture.The growth of different crops is also enhanced by application of RHB.RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability.RHB application shows a significant capacity in reduction of nitrate leaching,although its magnitude depends on the biochar application rate and soil biogeochemical characteristics.Use of RHB,especially in paddy fields,shows a promising mitigation effect on greenhouse gas(CH4,CO2 and N2O)emissions.Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time,its performance for specific applications(e.g.carbon sequestration,pH amendment)can be manipulated by adjusting the pyrolysis temperature.More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.展开更多
High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine...High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM, BET, FFIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange （MO） and 4-chlorophenol （4- CP） as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO2 nanoparticles were investigated. Results show that Gd and P doping enhances Ti02 surface textural properties by forming Ti O Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO2 with rate constant ofkapp - 1.28 ~ 10-2 min-1 for MO and kapp ~ 0.94 ~ 10-2 min-1 for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tri- doped Ti02 is due to the synergistic effect of enhanced surface chemistry and textural properties, increased number of surface adsorbed hydroxyl groups and organic species, improved visible light ab- sorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.展开更多
This paper aims to examine the effect of agglomeration on firm level productivity in Iran’s food manufacturing by employing a firm level dataset during 1986–2015 among firms for four districts.The empirical results ...This paper aims to examine the effect of agglomeration on firm level productivity in Iran’s food manufacturing by employing a firm level dataset during 1986–2015 among firms for four districts.The empirical results show that agglomeration in north districts are key factors in productivity growth.In this work,we apply a spatial Bayes model that uses hierarchical techniques during the three terms.The productivity clustering map is able to capture such patterns as the high productivity area that appears in the south,north districts of Iran.This paper evaluates the effect of agglomeration on firm productivity in Iran’s food industries at district level.We find that regional market potential is the strong predictor of productivity;moreover,industrial agglomeration has a productivity-augmenting impact.展开更多
Objective: The relationship between migraine and breast cancer risk has been reported inconsistently across different epidemiological studies. This meta-analysis was performed to explore the overall effect of migraine...Objective: The relationship between migraine and breast cancer risk has been reported inconsistently across different epidemiological studies. This meta-analysis was performed to explore the overall effect of migraine on breast cancer risk. Method: An electronic search of different major databases was conducted, including PubMed, Scopus, ScienceDirect, and the Cochrane library until February 1st, 2015. Of 652 retrieved studies, six population-based studies including two cohort studies with 130,812 and four case-control studies with 14,396 people were included in the analysis. Results: There was an inverse relationship between migraine and breast cancer risk (OR = 0.77;95% CI: 0.64, 0.92). Conclusion: The results of this meta-analysis showed that women with migraine history have a decreased risk of breast cancer. Further biological studies are needed to address the association.展开更多
Biochar is a product of pyrolysis of biomass in the absence of oxygen and has a high potential to sequester carbon into more stable soil organic carbon (OC).Despite the large number of studies on biochar and soil prop...Biochar is a product of pyrolysis of biomass in the absence of oxygen and has a high potential to sequester carbon into more stable soil organic carbon (OC).Despite the large number of studies on biochar and soil properties,few studies have investigated the effects of biochar in contrasting soils.The current research was conducted to evaluate the effects of different biochar levels (0 (as control),1% and 3%) on several soil physiochemical properties and nitrate leaching in two soil types (loamy sand and clay)under greenhouse conditions and wet-dry cycles.The experiment was performed using a randomized design with three levels of biochar produced from rice husks at 500 ℃ in three replications.Cation exchange capacity increased significantly,by 20% and 30% in 1% and 3% biochar-amended loamy sand soil,respectively,and increases were 9% and 19% in 1% and 3% biochar-amended clay soil,respectively.Loamy sand soil did not show improvement in aggregate indices,including mean weight diameter,geometric mean diameter,water stable aggregates and fractal dimension,which was contrary to the results for the clay soil.Rice husk biochar application at the both rates decreased nitrate leaching in the clay soil more than in the loamy sand.Our study highlights the importance of soil type in determining the value of biochar as a soil amendment to improve soil properties,particularly soil aggregation and reduced nitrate leaching.The benefits of the biochar in the clay soil were greater than in the loamy sand soil.展开更多
Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In ...Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In this study,a new model,namely genetic algorithm e support vector regression(GA-SVR)is proposed,which is applied to predict the amount of asphaltene precipitation.GA is used to select the best optimal values of SVR parameters and kernel parameter,simultaneously,to increase the generalization performance of the SVR.The GA-SVR model is trained and tested on the experimental data sets reported in literature.The performance of the GASVR model is compared with two scaling equation models,using statistical error measures and graphical analyses.The results show that the prediction performance of the proposed model,is highly reliable and satisfactory.展开更多
文摘This paper critically reviewed the current knowledge and challenges of rice husk biochar(RHB)production and its effects on soil properties,plant growth,immobilization of heavy metals,reduction of nutrient leaching and mitigation of greenhouse gas emissions.The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro-industrial wastes.RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio,which suggests the presence of higher aromatic carbon compounds.The increase of pyrolysis temperature also results in production of RHBs with higher ash content,lower yield and higher surface area.RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions.Although it depends on soil type,RHB application can improve soil organic carbon content,cation exchange capacity,available K concentration,bulk density and microbial activity.The effect of RHB on soil aggregation mainly depends on soil texture.The growth of different crops is also enhanced by application of RHB.RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability.RHB application shows a significant capacity in reduction of nitrate leaching,although its magnitude depends on the biochar application rate and soil biogeochemical characteristics.Use of RHB,especially in paddy fields,shows a promising mitigation effect on greenhouse gas(CH4,CO2 and N2O)emissions.Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time,its performance for specific applications(e.g.carbon sequestration,pH amendment)can be manipulated by adjusting the pyrolysis temperature.More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.
基金Project supported by the Research office of the Sharif University of Technology(90212681)
文摘High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM, BET, FFIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange （MO） and 4-chlorophenol （4- CP） as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO2 nanoparticles were investigated. Results show that Gd and P doping enhances Ti02 surface textural properties by forming Ti O Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO2 with rate constant ofkapp - 1.28 ~ 10-2 min-1 for MO and kapp ~ 0.94 ~ 10-2 min-1 for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tri- doped Ti02 is due to the synergistic effect of enhanced surface chemistry and textural properties, increased number of surface adsorbed hydroxyl groups and organic species, improved visible light ab- sorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.
基金Under the auspices of Project of Research Center of Ferdowsi university of Mashhad(No.40779).
文摘This paper aims to examine the effect of agglomeration on firm level productivity in Iran’s food manufacturing by employing a firm level dataset during 1986–2015 among firms for four districts.The empirical results show that agglomeration in north districts are key factors in productivity growth.In this work,we apply a spatial Bayes model that uses hierarchical techniques during the three terms.The productivity clustering map is able to capture such patterns as the high productivity area that appears in the south,north districts of Iran.This paper evaluates the effect of agglomeration on firm productivity in Iran’s food industries at district level.We find that regional market potential is the strong predictor of productivity;moreover,industrial agglomeration has a productivity-augmenting impact.
文摘Objective: The relationship between migraine and breast cancer risk has been reported inconsistently across different epidemiological studies. This meta-analysis was performed to explore the overall effect of migraine on breast cancer risk. Method: An electronic search of different major databases was conducted, including PubMed, Scopus, ScienceDirect, and the Cochrane library until February 1st, 2015. Of 652 retrieved studies, six population-based studies including two cohort studies with 130,812 and four case-control studies with 14,396 people were included in the analysis. Results: There was an inverse relationship between migraine and breast cancer risk (OR = 0.77;95% CI: 0.64, 0.92). Conclusion: The results of this meta-analysis showed that women with migraine history have a decreased risk of breast cancer. Further biological studies are needed to address the association.
文摘Biochar is a product of pyrolysis of biomass in the absence of oxygen and has a high potential to sequester carbon into more stable soil organic carbon (OC).Despite the large number of studies on biochar and soil properties,few studies have investigated the effects of biochar in contrasting soils.The current research was conducted to evaluate the effects of different biochar levels (0 (as control),1% and 3%) on several soil physiochemical properties and nitrate leaching in two soil types (loamy sand and clay)under greenhouse conditions and wet-dry cycles.The experiment was performed using a randomized design with three levels of biochar produced from rice husks at 500 ℃ in three replications.Cation exchange capacity increased significantly,by 20% and 30% in 1% and 3% biochar-amended loamy sand soil,respectively,and increases were 9% and 19% in 1% and 3% biochar-amended clay soil,respectively.Loamy sand soil did not show improvement in aggregate indices,including mean weight diameter,geometric mean diameter,water stable aggregates and fractal dimension,which was contrary to the results for the clay soil.Rice husk biochar application at the both rates decreased nitrate leaching in the clay soil more than in the loamy sand.Our study highlights the importance of soil type in determining the value of biochar as a soil amendment to improve soil properties,particularly soil aggregation and reduced nitrate leaching.The benefits of the biochar in the clay soil were greater than in the loamy sand soil.
文摘Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In this study,a new model,namely genetic algorithm e support vector regression(GA-SVR)is proposed,which is applied to predict the amount of asphaltene precipitation.GA is used to select the best optimal values of SVR parameters and kernel parameter,simultaneously,to increase the generalization performance of the SVR.The GA-SVR model is trained and tested on the experimental data sets reported in literature.The performance of the GASVR model is compared with two scaling equation models,using statistical error measures and graphical analyses.The results show that the prediction performance of the proposed model,is highly reliable and satisfactory.
