美国乳品收入损失补偿计划(MILC)及其启示

美国奶业高度发展,以联邦销售订单和乳品价格支持计划为核心的奶业补贴政策体系日趋完善,尤其是2002年乳品收入损失补偿计划(MILC),在扶持奶业发展、抵御产销风险方面发挥着重要作用。本文简要介绍了MILC计划的法律背景、申请条件、申请程序及政策效果,以及该计划对中国奶业政策的启示。     

Use of molecularly imprinted solid-phase extraction sorbent for the determination of four 5-nitroimidazoles and three of their metabolites from egg-based samples before tandem LC-ESIMS/MS analysis

A nitroimidazole, molecularly imprinted polymer (MIP) was tested to extract four 5-nitroimidazoles (i.e., dimetridazole (DMZ), ipronidazole (IPZ), metronidazole (MNZ), and ronidazole (RNZ)) and three of their metabolites (i.e., DMZOH, IPZOH, and MNZOH) from egg powder samples. Various MIP templates were produced, and their selectivity was assessed on nitroimidazole standard solutions using liquid chromatography coupled with ultraviolet detection. The optimal cleanup was then used for the extraction of nitroimidazole in egg powder samples, and their quantification was achieved by isotope dilution LC-ESIMS/MS. The sample preparation entails a solubilization of the samples with water and acetonitrile followed by a MISPE cleanup step before LC-ESIMS/MS analysis. Data acquisition was achieved using selected reaction monitoring, and quantification was done with five deuterated analogues (i.e., DMZ- d(3), RNZ- d(3), IPZ- d(3), DMZOH- d(3), and IPZOH- d(3)). DMZOH- d(3) was used to quantify MNZ and MNZOH since they do not have their corresponding internal standards. The method was validated according to the European Union criteria by spiking experiments at concentration levels of 1, 2, and 3 microg/kg. At these three levels and for compounds having their own internal standards, acceptable performance data were obtained, with internal standard corrected recoveries ranging from 91 to 111%, and decision limits (CCalpha) and detection capabilities (CCbeta) were below 0.34 and 0.39 microg/kg, respectively.     

An electronic micropenetrometer (EMP) for field measurements of biological soil crust stability

Despite the importance of biological soil crusts (BSC) for ecosystem functions in arid and semiarid areas, little information on their mechanical stability is available. Goal of this study was to develop a micropenetrometer (EMP) that allows to determine BSC stability at high spatial resolutions. First results show that differences in BSC stability at 39 μm resolution can be detected and that cyanobacterial BSC has an average penetration resistance of 0.75 MPa.     

Application of an electronic micropenetrometer to assess mechanical stability of biological soil crusts

An in situ determination of biological soil‐crust stability was carried out in two study sites along a sharp rainfall gradient. Penetration resistance (PR) of the crusts was measured using a newly developed light‐weight needle‐type electronic micropenetrometer. The depth‐related PR data revealed two sections possessing different structures and stability. The topcrust (0–2 mm) had significantly higher amounts of N, organic C, carbonates, and salts as compared to the underlain subcrust. The mean PR of the topcrust was 0.68 MPa for the southern study site, Nizzana‐South (≈ 100 mm annual rainfall), and it increased significantly for the northern study site, Nizzana‐69 (≈ 170 mm annual rainfall), with a mean of 1.11 MPa. A subcrust (2–30 mm) was identified that was characterized by a high amount of carbonates and a PR > 2 MPa. The electronic micropenetrometer system is a promising device for identifying areas of changing crust stability in relation to biological soil‐crust properties. The overall stability of biological soil crusts depends on the topcrust and subcrust structure. This structure is linked to abiotic and biotic factors and likely in relation to the amount of annual precipitation.