Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode...Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.展开更多
Changes in the employment structure in rural China were studied with a focus on off-farm self-employment.Data from the Chinese Household Income Project surveys were used,covering the same 14 provinces from 1988 to 201...Changes in the employment structure in rural China were studied with a focus on off-farm self-employment.Data from the Chinese Household Income Project surveys were used,covering the same 14 provinces from 1988 to 2018.We found that the proportion of adults in rural China with self-employment as their primary form of off-farm employment increased from only 2 percent in 1988 to 11 percent in 2013,with no further increases through 2018.In 1988 and 1995,the rate of self-employment was highest in the eastern region but this regional pattern subsequently disappeared.The probability of being self-employed in rural China was higher among married males than among unmarried persons.Having a migration experience increased the likelihood of being self-employed.Since 1995,self-employed households have had a higher average income than other categories of household.Based on estimates of income functions,we conclude that the income premium from being self-employed increased rapidly from 1988 to 1995 to become remarkably large when only a few adults were self-employed.However,as a larger fraction of the rural population entered self-employment,the payoff from being self-employed has rapidly diminished,although it was still substantial in 2018.展开更多
基金supported by the Central Public Interest Scientific Institution Basal Research Fund for the Chinese Academy of Agricultural Sciences(Grant No.:Y2021PT05)National Institute of Environmental Health Science Superfund Research Program(Grant No.:P42 ES004699)+1 种基金National Academy of Sciences(Subaward No.:2000009144)Ningbo Innovation Project for Agro-Products Quality and Safety(Grant No.:2019CXGC007).
文摘Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal enables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concentration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.
文摘Changes in the employment structure in rural China were studied with a focus on off-farm self-employment.Data from the Chinese Household Income Project surveys were used,covering the same 14 provinces from 1988 to 2018.We found that the proportion of adults in rural China with self-employment as their primary form of off-farm employment increased from only 2 percent in 1988 to 11 percent in 2013,with no further increases through 2018.In 1988 and 1995,the rate of self-employment was highest in the eastern region but this regional pattern subsequently disappeared.The probability of being self-employed in rural China was higher among married males than among unmarried persons.Having a migration experience increased the likelihood of being self-employed.Since 1995,self-employed households have had a higher average income than other categories of household.Based on estimates of income functions,we conclude that the income premium from being self-employed increased rapidly from 1988 to 1995 to become remarkably large when only a few adults were self-employed.However,as a larger fraction of the rural population entered self-employment,the payoff from being self-employed has rapidly diminished,although it was still substantial in 2018.
