Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling...Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.展开更多
Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Mana...Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.展开更多
Pringle Creek, identified as the source of dioxin/furan (PCDD/F) contamination to a Lake Ontario harbour was remediated in 2008. Surface sediment collected in 2013 near the floodplain remediation was no longer contami...Pringle Creek, identified as the source of dioxin/furan (PCDD/F) contamination to a Lake Ontario harbour was remediated in 2008. Surface sediment collected in 2013 near the floodplain remediation was no longer contaminated (∑<sub>17</sub>PCDD\Fs < 60 pg/g dw), but residual contamination extended downstream to the creek mouth (surface sediment maximum: ∑<sub>17</sub>PCDD\Fs 2900 pg/g dw). Nevertheless, sediment ∑<sub>17</sub>PCDD/F concentrations were lower in 2013 than pre-remediation suggesting that cleaner sediment was being deposited in the creek. Core data confirmed the decrease in sediment contamination through time since the most contaminated sediment was buried. Prior to the development of a remediation strategy for the harbour, the transport of bed-load and suspended sediment contaminated with PCDD/F was assessed. The challenge was the shallow water depth (0.6 m) throughout the creek thereby requiring non-standard sediment traps designed for this study. Suspended sediment collected in traps in 2014 showed residual contamination at the remediated site (∑<sub>17</sub>PCDD\Fs: 380 pg/g dw;TEQ (TEF fish) < 0.6 pg/g), with concentrations increasing with distance downstream mirroring surface sediment: mean ∑17PCDD\Fs concentration for suspended sediment at the creek mouth was 2200 pg/g (SD 260 pg/g dw) indicating PCDD/F contributions to the harbour. However, congener patterns in bottom sediment and suspended sediment near the remediated site and extending about 100 m downstream were similar to background upstream patterns consistent with atmospheric deposition as the source rather than the historical source which indicated that floodplain remedial actions were successful.展开更多
Bio-based media, derived from cellulosic biomass depolymerisation or bioconversion processes, are composed of several chemicals and biochemicals. In this study, the main components of a hemicellulosic-based medium wer...Bio-based media, derived from cellulosic biomass depolymerisation or bioconversion processes, are composed of several chemicals and biochemicals. In this study, the main components of a hemicellulosic-based medium were analyzed using a dual detection HPLC method to separate and determine concentrations of the major monosaccharides (glucose, xylose, and arabinose), alcoholic and acidic components (ethanol, xylitol, and acetic acid) and furanic compounds (furfural and hydroxymethylfurfural (HMF)). The analyses, which employed a single stationary phase (Aminex HPX-87H) and two detection methods, were carried out under isocratic conditions and involved mobile phases consisting of 5 mM sulfuric acid and acetonitrile in different mix ratios from 0 to 0.061 mole fraction of acetonitrile. Based on the analysis run time and the chromatogram quality, the optimum condition was determined for the simultaneous quantification of the components.展开更多
Cytotoxic styryl lactone, ( + )-7-epi-Goniofufurone (1), has been prepared with a new route from 3-O-benzyl-1, 2-O-isopropylidene-5-C-phenyl-β-L-ido-pentofuranose (6), a derivative of (+)-glucose. Treatment of 14 wit...Cytotoxic styryl lactone, ( + )-7-epi-Goniofufurone (1), has been prepared with a new route from 3-O-benzyl-1, 2-O-isopropylidene-5-C-phenyl-β-L-ido-pentofuranose (6), a derivative of (+)-glucose. Treatment of 14 with HCl solution cleaved TBDMS and isopropylidene and simultaneously caused ring closure to afford 1 while treatment of 14 with Sc(OTf)3 only removed TBDMS to give 15.展开更多
The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-l2O3, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the ...The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-l2O3, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the chemical composition of the liquid products were discussed. Compared with the pyrolytic products of direct pyrolysis, the amount of residual char decreased, whereas the gas yield increased in the presence of the catalysts. The highest liquid yield over ZNO（49.5%） was obtained when the ratio of ZnO to glucose was 5%, whereas over γ-Al2O3 the liquid yield increased with increasing the amount of γ-Al2O3 added. The presence of both the catalysts enhanced the selectivity to furans in liquid and reduced that of anhydro sugars. A selectivity of 69.7% to furans was obtained over 1% ZnO with a selectivity of 14.6% to 5-hydroxymethylfurfural（HMF）. The maximum selectivity to furans（74.9%） and that to HMF（25.6%） were obtained in the presence of 10% γ-Al2O3.展开更多
Intermolecular addition-cyclization of 1, 3-dicarbonyl compounds with arylbromo- allenes in K2CO3 mediated condition afforded 2, 3, 4-trisubstituted furans in good yield.
A new method for preparing (2Z, 4Z, 6Z)-4,5-diethyloxepinedicarboxylate by one-step is described. The synthesis of several oxepines and azepines derivatives was carried out by the reaction of substituted furans or pyr...A new method for preparing (2Z, 4Z, 6Z)-4,5-diethyloxepinedicarboxylate by one-step is described. The synthesis of several oxepines and azepines derivatives was carried out by the reaction of substituted furans or pyrroles with diethyl acetylenedicarboxylate in boiling toluene. The effect factors for this reaction were discussed and reaction condition was optimized.展开更多
Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylate...Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylated furan derivatives based on Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes.This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups.Mechanistically,the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation.The reaction reported in this paper further demonstrates the generality of the carbene-based cross coupling.展开更多
基金supported by the National Natural Science Foundation of China(No.91543202)the Ministry of Environmental Protection of the People's Republic of China(Nos.201409022,201409080 and 201509063)South China Institute of Environmental Science(No.PM-zx021-201510-015)
文摘Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.
文摘Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.
文摘Pringle Creek, identified as the source of dioxin/furan (PCDD/F) contamination to a Lake Ontario harbour was remediated in 2008. Surface sediment collected in 2013 near the floodplain remediation was no longer contaminated (∑<sub>17</sub>PCDD\Fs < 60 pg/g dw), but residual contamination extended downstream to the creek mouth (surface sediment maximum: ∑<sub>17</sub>PCDD\Fs 2900 pg/g dw). Nevertheless, sediment ∑<sub>17</sub>PCDD/F concentrations were lower in 2013 than pre-remediation suggesting that cleaner sediment was being deposited in the creek. Core data confirmed the decrease in sediment contamination through time since the most contaminated sediment was buried. Prior to the development of a remediation strategy for the harbour, the transport of bed-load and suspended sediment contaminated with PCDD/F was assessed. The challenge was the shallow water depth (0.6 m) throughout the creek thereby requiring non-standard sediment traps designed for this study. Suspended sediment collected in traps in 2014 showed residual contamination at the remediated site (∑<sub>17</sub>PCDD\Fs: 380 pg/g dw;TEQ (TEF fish) < 0.6 pg/g), with concentrations increasing with distance downstream mirroring surface sediment: mean ∑17PCDD\Fs concentration for suspended sediment at the creek mouth was 2200 pg/g (SD 260 pg/g dw) indicating PCDD/F contributions to the harbour. However, congener patterns in bottom sediment and suspended sediment near the remediated site and extending about 100 m downstream were similar to background upstream patterns consistent with atmospheric deposition as the source rather than the historical source which indicated that floodplain remedial actions were successful.
文摘Bio-based media, derived from cellulosic biomass depolymerisation or bioconversion processes, are composed of several chemicals and biochemicals. In this study, the main components of a hemicellulosic-based medium were analyzed using a dual detection HPLC method to separate and determine concentrations of the major monosaccharides (glucose, xylose, and arabinose), alcoholic and acidic components (ethanol, xylitol, and acetic acid) and furanic compounds (furfural and hydroxymethylfurfural (HMF)). The analyses, which employed a single stationary phase (Aminex HPX-87H) and two detection methods, were carried out under isocratic conditions and involved mobile phases consisting of 5 mM sulfuric acid and acetonitrile in different mix ratios from 0 to 0.061 mole fraction of acetonitrile. Based on the analysis run time and the chromatogram quality, the optimum condition was determined for the simultaneous quantification of the components.
文摘Cytotoxic styryl lactone, ( + )-7-epi-Goniofufurone (1), has been prepared with a new route from 3-O-benzyl-1, 2-O-isopropylidene-5-C-phenyl-β-L-ido-pentofuranose (6), a derivative of (+)-glucose. Treatment of 14 with HCl solution cleaved TBDMS and isopropylidene and simultaneously caused ring closure to afford 1 while treatment of 14 with Sc(OTf)3 only removed TBDMS to give 15.
基金Supported by the National Basic Research Program of China(No. 2007CB210203)the Special Research Fund for the Doc-toral Program of Higher Education of China(No.20050610013)+1 种基金the Science Foundation of Sichuan Province, China (No.105JY029-025-2)the Funds for Innovative Research of Sichuan University, China.
文摘The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-l2O3, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the chemical composition of the liquid products were discussed. Compared with the pyrolytic products of direct pyrolysis, the amount of residual char decreased, whereas the gas yield increased in the presence of the catalysts. The highest liquid yield over ZNO（49.5%） was obtained when the ratio of ZnO to glucose was 5%, whereas over γ-Al2O3 the liquid yield increased with increasing the amount of γ-Al2O3 added. The presence of both the catalysts enhanced the selectivity to furans in liquid and reduced that of anhydro sugars. A selectivity of 69.7% to furans was obtained over 1% ZnO with a selectivity of 14.6% to 5-hydroxymethylfurfural（HMF）. The maximum selectivity to furans（74.9%） and that to HMF（25.6%） were obtained in the presence of 10% γ-Al2O3.
基金We are grateful to the National Natural Science Foundation of China(No.20472072,20332060).
文摘Intermolecular addition-cyclization of 1, 3-dicarbonyl compounds with arylbromo- allenes in K2CO3 mediated condition afforded 2, 3, 4-trisubstituted furans in good yield.
基金The National Natural Science Foundation of China(No.20372086) supported this work
文摘A new method for preparing (2Z, 4Z, 6Z)-4,5-diethyloxepinedicarboxylate by one-step is described. The synthesis of several oxepines and azepines derivatives was carried out by the reaction of substituted furans or pyrroles with diethyl acetylenedicarboxylate in boiling toluene. The effect factors for this reaction were discussed and reaction condition was optimized.
基金supported by NSFC(22371008),BNLMSLaboratory for Synthetic Chemistry and Chemical Biology of Health@InnoHK of ITC,HKSAR.
文摘Furans bearing alkynyl substituents are highly useful in organic synthesis.However,the methodologies to access these important furan derivatives are rather limited.We herein report an efficient synthesis of alkynylated furan derivatives based on Pd-catalyzed oxidative cross-coupling reaction between allenyl ketones and terminal alkynes.This novel synthesis of alkynylated furans with wide substrate scope is operationally simple and tolerates various functional groups.Mechanistically,the formation of the palladium carbene through cycloisomerization and the subsequent alkynyl migratory insertion are proposed as the key steps in the transformation.The reaction reported in this paper further demonstrates the generality of the carbene-based cross coupling.
