The cyanobacteria-bloom in raw waters frequently causes an unpredictable chemical dosing of preoxidation and coagulation for an effective removal of algal cells in water treatment plants. This study investigated the e...The cyanobacteria-bloom in raw waters frequently causes an unpredictable chemical dosing of preoxidation and coagulation for an effective removal of algal cells in water treatment plants. This study investigated the effects of preoxidation with NaOCl and ClO_2 on the coagulation-flotation effectiveness in the removal of two commonly blooming cyanobacteria species, Microcystis aeruginosa（MA） and Cylindrospermopsis raciborskii（CR）, and their corresponding trihalomethane（THM） formation potential. The results showed that dual dosing with NaOCl plus ClO_2 was more effective in enhancing the deformation of cyanobacterial cells compared to single dosing with Na OCl, especially for CR-rich water.Both preoxidation approaches for CR-rich water effectively reduced the CR cell count with less remained dissolved organic carbon（DOC）, which benefited subsequent coagulation–flotation. However, preoxidation led to an adverse release of algogenic organic matter（AOM） in the case of MA-rich water. The release of AOM resulted in a poor removal in MA cells and a large amount of THM formation after oxidation-assisted coagulation-flotation process. The reduction in THM formation potential of CR-rich waters is responsible for effective algae and DOC removal by alum coagulation. It is concluded that the species-specific characteristic of cyanobacteria and their AOM released during chlorination significantly influences the performance of coagulation–flotation for AOM removal and corresponding THM formation.展开更多
Iodinated trihalomethanes(I-THMs)in drinking water pipelines have attracted wide attention due to their high toxicity.The coexistence of widely present lead dioxide(PbO_(2))with commonly used disinfectant sodium hypoc...Iodinated trihalomethanes(I-THMs)in drinking water pipelines have attracted wide attention due to their high toxicity.The coexistence of widely present lead dioxide(PbO_(2))with commonly used disinfectant sodium hypochlorite(NaClO)in drinking water might change the formation characteristics of I-THMs due to the strongly oxidizing properties of PbO_(2).This study investigated the formation of I-THMs during the co-oxidation of natural organic matter including humic acid(HA),extracellular organic matter(EOM),and intracellular organic matter(IOM)of algogenic organic matter by PbO_(2) and NaClO.Triiodomethane(CHI_(3))is the dominant product in the single oxidation system of PbO_(2),whereas trichloromethane(CHCl_(3)),chlorodiiodomethane(CHClI_(2)),and dichloroiodomethane(CHCl2I)are the major products in the single NaClO system.In the co-oxidation system,the dominant I-THMs are similar to those in the single NaClO system.However,the CHCl_(3) content decreased to 56.4%whereas I-THMs concentrations remained unchanged with the increase of PbO_(2) concentration.The main reason is attributed to the reduced residual chlorine content due to the reaction of PbO_(2) with NaClO.IOM is more prone to forming I-THMs than HA and EOM due to the specified structures.This study suggested that PbO_(2) in the drinking water supply pipelines might change the risk of THMs.展开更多
Melittin is a basic 26-amino-acid polypeptide that constitutes 40-60% of dry honeybee（Apis mellifera）venom.Although much is known about its strong surface activity on lipid membranes,less is known about its painprod...Melittin is a basic 26-amino-acid polypeptide that constitutes 40-60% of dry honeybee（Apis mellifera）venom.Although much is known about its strong surface activity on lipid membranes,less is known about its painproducing effects in the nervous system.In this review,we provide lines of accumulating evidence to support the hypothesis that melittin is the major pain-producing substance of bee venom.At the psychophysical and behavioral levels,subcutaneous injection of melittin causes tonic pain sensation and pain-related behaviors in both humans and animals.At the cellular level,melittin activates primary nociceptor cells through direct and indirect effects.On one hand,melittin can selectively open thermal nociceptor transient receptor potential vanilloid receptor channels via phospholipase A2-lipoxygenase/cyclooxygenase metabolites,leading to depolarization of primary nociceptor cells.On the other hand,algogens and inflammatory/proinflammatory mediators released from the tissue matrix by melittin＇s pore-forming effects can activate primary nociceptor cells through both ligand-gated receptor channels and the G-protein-coupled receptor-mediated opening of transient receptor potential canonical channels.Moreover,subcutaneous melittin up-regulates Nav1.8 and Nav1.9subunits,resulting in the enhancement of tetrodotoxinresistant Na~＋currents and the generation of long-term action potential firing.These nociceptive responses in the periphery finally activate and sensitize the spinal dorsal horn pain-signaling neurons,resulting in spontaneous nociceptive paw flinches and pain hypersensitivity to thermal and mechanical stimuli.Taken together,it is concluded that melittin is the major pain-producing substance of bee venom,by which peripheral persistent pain and hyperalgesia（or allodynia）,primary nociceptive neuronal sensitization,and CNS synaptic plasticity（or metaplasticity） can be readily induced and the molecular and cellular mechanisms underlying naturally-occurring venomous biotoxins can be experimentally 展开更多
基金the National Science Council of Taiwan (No. NSC102-2119-M-002-008) for the financial support
文摘The cyanobacteria-bloom in raw waters frequently causes an unpredictable chemical dosing of preoxidation and coagulation for an effective removal of algal cells in water treatment plants. This study investigated the effects of preoxidation with NaOCl and ClO_2 on the coagulation-flotation effectiveness in the removal of two commonly blooming cyanobacteria species, Microcystis aeruginosa（MA） and Cylindrospermopsis raciborskii（CR）, and their corresponding trihalomethane（THM） formation potential. The results showed that dual dosing with NaOCl plus ClO_2 was more effective in enhancing the deformation of cyanobacterial cells compared to single dosing with Na OCl, especially for CR-rich water.Both preoxidation approaches for CR-rich water effectively reduced the CR cell count with less remained dissolved organic carbon（DOC）, which benefited subsequent coagulation–flotation. However, preoxidation led to an adverse release of algogenic organic matter（AOM） in the case of MA-rich water. The release of AOM resulted in a poor removal in MA cells and a large amount of THM formation after oxidation-assisted coagulation-flotation process. The reduction in THM formation potential of CR-rich waters is responsible for effective algae and DOC removal by alum coagulation. It is concluded that the species-specific characteristic of cyanobacteria and their AOM released during chlorination significantly influences the performance of coagulation–flotation for AOM removal and corresponding THM formation.
基金supported by the National Natural Science Foundation of China(No.22076141)the Fundamental Research Funds for the Central Universities,China(No.2022-4-YB-13).
文摘Iodinated trihalomethanes(I-THMs)in drinking water pipelines have attracted wide attention due to their high toxicity.The coexistence of widely present lead dioxide(PbO_(2))with commonly used disinfectant sodium hypochlorite(NaClO)in drinking water might change the formation characteristics of I-THMs due to the strongly oxidizing properties of PbO_(2).This study investigated the formation of I-THMs during the co-oxidation of natural organic matter including humic acid(HA),extracellular organic matter(EOM),and intracellular organic matter(IOM)of algogenic organic matter by PbO_(2) and NaClO.Triiodomethane(CHI_(3))is the dominant product in the single oxidation system of PbO_(2),whereas trichloromethane(CHCl_(3)),chlorodiiodomethane(CHClI_(2)),and dichloroiodomethane(CHCl2I)are the major products in the single NaClO system.In the co-oxidation system,the dominant I-THMs are similar to those in the single NaClO system.However,the CHCl_(3) content decreased to 56.4%whereas I-THMs concentrations remained unchanged with the increase of PbO_(2) concentration.The main reason is attributed to the reduced residual chlorine content due to the reaction of PbO_(2) with NaClO.IOM is more prone to forming I-THMs than HA and EOM due to the specified structures.This study suggested that PbO_(2) in the drinking water supply pipelines might change the risk of THMs.
基金supported by grants from the National Basic Research Development Program of China (2013CB 835100)the National Natural Science Foundation of China (81171049,31300919,and 31400948)+1 种基金the National Key Technology R&D Program,China (2013BAI04B04)the Twelfth Five-Year Project of China (AWS12J004)
文摘Melittin is a basic 26-amino-acid polypeptide that constitutes 40-60% of dry honeybee（Apis mellifera）venom.Although much is known about its strong surface activity on lipid membranes,less is known about its painproducing effects in the nervous system.In this review,we provide lines of accumulating evidence to support the hypothesis that melittin is the major pain-producing substance of bee venom.At the psychophysical and behavioral levels,subcutaneous injection of melittin causes tonic pain sensation and pain-related behaviors in both humans and animals.At the cellular level,melittin activates primary nociceptor cells through direct and indirect effects.On one hand,melittin can selectively open thermal nociceptor transient receptor potential vanilloid receptor channels via phospholipase A2-lipoxygenase/cyclooxygenase metabolites,leading to depolarization of primary nociceptor cells.On the other hand,algogens and inflammatory/proinflammatory mediators released from the tissue matrix by melittin＇s pore-forming effects can activate primary nociceptor cells through both ligand-gated receptor channels and the G-protein-coupled receptor-mediated opening of transient receptor potential canonical channels.Moreover,subcutaneous melittin up-regulates Nav1.8 and Nav1.9subunits,resulting in the enhancement of tetrodotoxinresistant Na~＋currents and the generation of long-term action potential firing.These nociceptive responses in the periphery finally activate and sensitize the spinal dorsal horn pain-signaling neurons,resulting in spontaneous nociceptive paw flinches and pain hypersensitivity to thermal and mechanical stimuli.Taken together,it is concluded that melittin is the major pain-producing substance of bee venom,by which peripheral persistent pain and hyperalgesia（or allodynia）,primary nociceptive neuronal sensitization,and CNS synaptic plasticity（or metaplasticity） can be readily induced and the molecular and cellular mechanisms underlying naturally-occurring venomous biotoxins can be experimentally
