A novel spectrofluorimetric method for the determination of L ascorbic acid is proposed. It is based on the inhibition of L ascorbic acid on the formation of 2,3 diaminophenazine, which is an oxidation product of ...A novel spectrofluorimetric method for the determination of L ascorbic acid is proposed. It is based on the inhibition of L ascorbic acid on the formation of 2,3 diaminophenazine, which is an oxidation product of o phenylenediamine catalyzed by laccase .The fluorescence (at λ ex /λ em =464 nm /530 nnm) was enhanced strongly in the presence of organic media . The mechanism of o phenylenediamine oxidation reaction catalyzed by laccase in the presence of L ascorbic acid is discussed .L ascorbic acid is determined in the ethanol, 1,4 dioxane and acetone over the linear range of 4.0×10 -7 ~1.2×10 -4 mol/L, 4.0×10 -7 ~ 8.0×10 -5 mol/L and 4.0×10 -7 ~1.0×10 -4 mol/L with a detection limit of 1.20×10 -8 mol/L,1.19×10 -8 mol/L and 1.24×10 -8 mol/L, respectively. The method has been successfully applied to the simple and rapid determination of L ascorbic acid in pharmaceuticals and milk powder.展开更多
Heavy-metal-free silver based I-III-VI semiconductor nanocrystals(NCs),including ternary silver indium sulfide(AgInS_(2))and derivative quaternary silver indium zinc sulfide(i.e.,AgInZn_(2)S_(4))NCs,possess advantages...Heavy-metal-free silver based I-III-VI semiconductor nanocrystals(NCs),including ternary silver indium sulfide(AgInS_(2))and derivative quaternary silver indium zinc sulfide(i.e.,AgInZn_(2)S_(4))NCs,possess advantages of low toxicity,and size-tunable band gaps approaching near-infrared spectral range,which make them candidates for use in optoelectronic and biological devices.Herein,we report syntheses of AgInS_(2) based NCs starting from In_(2)S_(3) template,which have been performed both in organic and aqueous phase through cation exchange.As a result,ternary silver indium sulfide and quaternary silver indium zinc sulfide NCs are obtained in both organic and aqueous media,and confirmed to be orthorhombic AgInS_(2) NCs and hexagonal AgInZn_(2)S_(4) NCs,respectively.Furthermore,the aqueous AgInZn_(2)S_(4) NCs with red emission and low cytotoxicity are explored for the cancer cell imaging.展开更多
This article reports pollutant removal performances of baffled subsurface flow, and integrated surface flow-floating treatment wetland units, when arranged in series for the treatment of municipal wastewater in Bangla...This article reports pollutant removal performances of baffled subsurface flow, and integrated surface flow-floating treatment wetland units, when arranged in series for the treatment of municipal wastewater in Bangladesh. The wetland units (of the hybrid system) included organic, inorganic media, and were planted with nineteen types of macrophytes. The wetland train was operated under hydraulic loading fluctuation and seasonal variation. The performance analyses (across the wetland units) illustrated simultaneous denitrification and organics removal rates in the first stage vertical flow wetland, due to organic carbon leaching from the employed organic media. Higher mean organics removal rates (656.0 g COD](m2.day)) did not completely inhibit nitrification in the first stage vertical flow system; such pattern could be linked to effective utilization of the trapped oxygen, as the flow was directed throughout the media by the baffle walls. Second stage horizontal flow wetland showed enhanced biodegradable organics removal, which depleted organic carbon availability for denitrification. The final stage integrated wetland system allowed further nitrogen removal from wastewater, via nutrient uptake by plant roots (along with nitrification), and generation of organic carbon (by the dead macrophytes) to support denitrification. The system achieved higher E. coli mortality through protozoa predation, E. coli oxidation, and destruction by UV radiation. In general, enhanced pollutant removal efflciencies as demonstrated by the structurally modified hybrid wetland system signify the necessity of such modification, when operated under adverse conditions such as: substantial input organics loading, hydraulic loading fluctuation, and seasonal variation.展开更多
文摘A novel spectrofluorimetric method for the determination of L ascorbic acid is proposed. It is based on the inhibition of L ascorbic acid on the formation of 2,3 diaminophenazine, which is an oxidation product of o phenylenediamine catalyzed by laccase .The fluorescence (at λ ex /λ em =464 nm /530 nnm) was enhanced strongly in the presence of organic media . The mechanism of o phenylenediamine oxidation reaction catalyzed by laccase in the presence of L ascorbic acid is discussed .L ascorbic acid is determined in the ethanol, 1,4 dioxane and acetone over the linear range of 4.0×10 -7 ~1.2×10 -4 mol/L, 4.0×10 -7 ~ 8.0×10 -5 mol/L and 4.0×10 -7 ~1.0×10 -4 mol/L with a detection limit of 1.20×10 -8 mol/L,1.19×10 -8 mol/L and 1.24×10 -8 mol/L, respectively. The method has been successfully applied to the simple and rapid determination of L ascorbic acid in pharmaceuticals and milk powder.
基金This work was supported by the National Key R&D Program of China(No.2017YFB1002900)the Natural Science Foundation of Youth Fund Project of China(No.51602024)+2 种基金the National Natural Science Foundation of China(No.2157015)the Talent Introduction Plan of Overseas Top Ranking Professors by the State Administration of Foreign Expert Affairs(No.MSBJLG040)the Germany/Hong Kong Joint Research Scheme sponsored by the Research Grants Council of Hong Kong and the German Academic Exchange Service(No.G-CityU106/18).
文摘Heavy-metal-free silver based I-III-VI semiconductor nanocrystals(NCs),including ternary silver indium sulfide(AgInS_(2))and derivative quaternary silver indium zinc sulfide(i.e.,AgInZn_(2)S_(4))NCs,possess advantages of low toxicity,and size-tunable band gaps approaching near-infrared spectral range,which make them candidates for use in optoelectronic and biological devices.Herein,we report syntheses of AgInS_(2) based NCs starting from In_(2)S_(3) template,which have been performed both in organic and aqueous phase through cation exchange.As a result,ternary silver indium sulfide and quaternary silver indium zinc sulfide NCs are obtained in both organic and aqueous media,and confirmed to be orthorhombic AgInS_(2) NCs and hexagonal AgInZn_(2)S_(4) NCs,respectively.Furthermore,the aqueous AgInZn_(2)S_(4) NCs with red emission and low cytotoxicity are explored for the cancer cell imaging.
文摘This article reports pollutant removal performances of baffled subsurface flow, and integrated surface flow-floating treatment wetland units, when arranged in series for the treatment of municipal wastewater in Bangladesh. The wetland units (of the hybrid system) included organic, inorganic media, and were planted with nineteen types of macrophytes. The wetland train was operated under hydraulic loading fluctuation and seasonal variation. The performance analyses (across the wetland units) illustrated simultaneous denitrification and organics removal rates in the first stage vertical flow wetland, due to organic carbon leaching from the employed organic media. Higher mean organics removal rates (656.0 g COD](m2.day)) did not completely inhibit nitrification in the first stage vertical flow system; such pattern could be linked to effective utilization of the trapped oxygen, as the flow was directed throughout the media by the baffle walls. Second stage horizontal flow wetland showed enhanced biodegradable organics removal, which depleted organic carbon availability for denitrification. The final stage integrated wetland system allowed further nitrogen removal from wastewater, via nutrient uptake by plant roots (along with nitrification), and generation of organic carbon (by the dead macrophytes) to support denitrification. The system achieved higher E. coli mortality through protozoa predation, E. coli oxidation, and destruction by UV radiation. In general, enhanced pollutant removal efflciencies as demonstrated by the structurally modified hybrid wetland system signify the necessity of such modification, when operated under adverse conditions such as: substantial input organics loading, hydraulic loading fluctuation, and seasonal variation.