目的了解重庆地区辣椒、花椒和八角中真菌毒素污染状况。方法采用随机抽样方法,在重庆地区盘溪、菜园坝和江津3个市场,抽取180批次香辛料样品,采用高效液相色谱-串联质谱法(highperformance liquid chromatography tandem mass spectrom...目的了解重庆地区辣椒、花椒和八角中真菌毒素污染状况。方法采用随机抽样方法,在重庆地区盘溪、菜园坝和江津3个市场,抽取180批次香辛料样品,采用高效液相色谱-串联质谱法(highperformance liquid chromatography tandem mass spectrometry,HPLC-MS/MS)检测黄曲霉毒素(aflatoxin,AF)AFB1、AFB2、AFG1和AFG2、赭曲霉毒素A(ochratoxinA,OTA)和伏马毒素(flumonisin B,FB1和FB2)。结果重庆地区辣椒、花椒和八角中的真菌毒素总检出率分别为60.0%、100%、96.7%。AFs和OTA是3种香辛料最主要的污染毒素,其中黄曲霉毒素以AFG2为主。盘溪市场的AFs污染总体情况稍好,菜园坝市场AFs污染最严重;江津市场的OTA污染最为严重。结论重庆地区香辛料中存在真菌毒素污染问题,有必要建立香辛料中真菌毒素的限量标准。展开更多
With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energ...With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energy levels are calculated exactly and the impurity binding energies are calculated with the variational approach. It is found that the behaviors of electronic and shallow impurity states in heterostructures under an applied electric field are analogous to that of quantum wells. Our results show that with the increasing strength of electric field, the electron confinement energies increase, and the impurity binding energy increases also when the impurity is on the surface, while the impurity binding energy increases at first, to a peak value, then decreases to a value which is related to the impurity position when the impurity is away from the surface. In the absence of electric field, the result tends to the Levine's ground state energy (-1/4 effective Rydberg) when the impurity is on the surface, and the ground impurity binding energy tends to that in the bulk when the impurity is far away from the surface. The dependence of the impurity binding energy on the impurity position for different electric field is also discussed.展开更多
文摘目的了解重庆地区辣椒、花椒和八角中真菌毒素污染状况。方法采用随机抽样方法,在重庆地区盘溪、菜园坝和江津3个市场,抽取180批次香辛料样品,采用高效液相色谱-串联质谱法(highperformance liquid chromatography tandem mass spectrometry,HPLC-MS/MS)检测黄曲霉毒素(aflatoxin,AF)AFB1、AFB2、AFG1和AFG2、赭曲霉毒素A(ochratoxinA,OTA)和伏马毒素(flumonisin B,FB1和FB2)。结果重庆地区辣椒、花椒和八角中的真菌毒素总检出率分别为60.0%、100%、96.7%。AFs和OTA是3种香辛料最主要的污染毒素,其中黄曲霉毒素以AFG2为主。盘溪市场的AFs污染总体情况稍好,菜园坝市场AFs污染最严重;江津市场的OTA污染最为严重。结论重庆地区香辛料中存在真菌毒素污染问题,有必要建立香辛料中真菌毒素的限量标准。
基金Natural Science Foundation of Shanghai Municipal Commission of Education
文摘With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energy levels are calculated exactly and the impurity binding energies are calculated with the variational approach. It is found that the behaviors of electronic and shallow impurity states in heterostructures under an applied electric field are analogous to that of quantum wells. Our results show that with the increasing strength of electric field, the electron confinement energies increase, and the impurity binding energy increases also when the impurity is on the surface, while the impurity binding energy increases at first, to a peak value, then decreases to a value which is related to the impurity position when the impurity is away from the surface. In the absence of electric field, the result tends to the Levine's ground state energy (-1/4 effective Rydberg) when the impurity is on the surface, and the ground impurity binding energy tends to that in the bulk when the impurity is far away from the surface. The dependence of the impurity binding energy on the impurity position for different electric field is also discussed.
