Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading ...Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge.To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading,a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests,whereas the simulation results were not satisfactory.The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than that measured by the field tests,which is attributed to the relatively low permeability layer formed during the preloading process of the prefabricated vertical drain.To better reflect the consolidation process of the conditioned sludge,a simplified analysis method considering the low permeability layer around the prefabricated vertical drain was proposed.The initial permeability coefficient of the low permeability layer is determined via numerical simulations using finite difference method.The predicted settlement curve was in good agreement with the measured results,which indicated that the numerical simulation based on the equal strain condition considering the relatively low permeability layer can better analyze the consolidation process of ferric chloride-conditioning sludge with vacuum preloading.展开更多
Glycyrrhiza uralensis is considered to be one of the most important herbs in traditional Chinese medicine due to its numerous pharmacological effects particularly its ability to relieve cough and act as a mucolytic.Ba...Glycyrrhiza uralensis is considered to be one of the most important herbs in traditional Chinese medicine due to its numerous pharmacological effects particularly its ability to relieve cough and act as a mucolytic.Based on previous research,these effects are mediated by a number of active ingredients,especially glycyrrhizic acid(GA).In the present study,a gene encodingβ-amyrin synthase(β-AS)involved in GA biosynthesis in G.uralensis has been cloned and expressed in Saccharomyces cerevisiae.The cloned enzyme showed similar activity to native enzymes isolated from other Glycyrrhiza species to catalyze the conversion of 2,3-oxidosqualene intoβ-amyrin.In fact theβ-AS gene is particularly important in the GA biosynthetic pathway in G.uralensis.The complete sequence of the enzyme was determined and a phylogenetic tree based on theβ-AS gene of G.uralensis and 20 other species was created.This showed that Glycyrrhiza glabra had the closest kinship with G.uralensis.The results of this work will be useful in determining how to improve the efficacy of G.uralensis by improving its GA content and in exploring the biosynthesis of GA in vitro.展开更多
基金acknowledge the financial support from The National Natural Science Foundation No.Gk321002Foundation of Nanjing Hydraulic Research Institute No.Y320012.
文摘Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge.To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading,a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests,whereas the simulation results were not satisfactory.The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than that measured by the field tests,which is attributed to the relatively low permeability layer formed during the preloading process of the prefabricated vertical drain.To better reflect the consolidation process of the conditioned sludge,a simplified analysis method considering the low permeability layer around the prefabricated vertical drain was proposed.The initial permeability coefficient of the low permeability layer is determined via numerical simulations using finite difference method.The predicted settlement curve was in good agreement with the measured results,which indicated that the numerical simulation based on the equal strain condition considering the relatively low permeability layer can better analyze the consolidation process of ferric chloride-conditioning sludge with vacuum preloading.
文摘Glycyrrhiza uralensis is considered to be one of the most important herbs in traditional Chinese medicine due to its numerous pharmacological effects particularly its ability to relieve cough and act as a mucolytic.Based on previous research,these effects are mediated by a number of active ingredients,especially glycyrrhizic acid(GA).In the present study,a gene encodingβ-amyrin synthase(β-AS)involved in GA biosynthesis in G.uralensis has been cloned and expressed in Saccharomyces cerevisiae.The cloned enzyme showed similar activity to native enzymes isolated from other Glycyrrhiza species to catalyze the conversion of 2,3-oxidosqualene intoβ-amyrin.In fact theβ-AS gene is particularly important in the GA biosynthetic pathway in G.uralensis.The complete sequence of the enzyme was determined and a phylogenetic tree based on theβ-AS gene of G.uralensis and 20 other species was created.This showed that Glycyrrhiza glabra had the closest kinship with G.uralensis.The results of this work will be useful in determining how to improve the efficacy of G.uralensis by improving its GA content and in exploring the biosynthesis of GA in vitro.
