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二噁英、多氯联苯和氯丙醇的痕量与超痕量检测技术研究 总被引:3,自引:0,他引:3
吴永宁 《中国食品卫生杂志》2005,17(6):481-486
为建立食品中二噁英、多氯联苯和氯丙醇的检测技术并达到国际水平,将稳定性同位素稀释质谱技术应用到中国食品安全和环境分析领域,针对不同目标化合物分别建立了高分辩磁质谱、四极杆低分辩质谱和离子阱串联质谱的标准化检测技术,特别是采用双同位素稀释同时测定4种氯丙醇的技术。通过对EPA1613A/1668A、FDA4084和EPSI/RM/31、AOAC2000.01等国际先进方法用食品(鱼、鱼油、鹿肉、奶粉和猪油)和环境样品(飞灰、土壤和底泥)开展对比筛选和一系列实验室闻协同性验证,确立了二噁英和多氯联苯的稳定性同位素稀释质谱检测方法,建立了用双稳定性同位素进行酱油中单氯取代和双氯取代氯丙醇同时测定的方法,提出了符合国际规范的技术方案,作为国家标准方法待颁布。利用该检测技术在中国首次开展鱼贝类和土壤中污染的二噁英和多氯联苯同系物类型特征指纹库研究和酱油中氯丙醇的大规模调查,获得了中国人群膳食二噁英毒性当量和氯丙醇摄入状况的暴露数据,不仅证明所建立的方法实用、可行,也为我国履行承诺摸清了家底,提供了依据。 相似文献
13.
通过对PROTOS1-8高速卷烟机在线激光打孔参数的组合试验和数据回归分析,得出了烟支稀释率与脉冲、脉冲与能量的乘积、能量、打孔数量等参数的线性相关方程。试验结果表明,利用各线性方程可计算出能保证LASER 300S激光打孔系统正常运行的参数组合,与实际在线打孔的烟支稀释率值具有较好的符合性和稳定性,能够提高在线加工质量。 相似文献
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G. Batey M. Buehler M. Cuthbert T. Foster A.J. Matthews G. Teleberg A. Twin 《低温学》2009,49(12):727-734
There has been much recent research interest into “cryogen-free” dilution refrigerators. Cryogen-free systems have some advantages from a safety and convenience point of view as liquid cryogens are unnecessary. However, this also makes integrating the low-temperature system with a high magnetic field environment much more challenging. Here we shall describe recent successes of integrating superconducting magnets and dilution refrigerators into one system requiring a single pulse tube cooler. The resulting environment provides experimental temperatures between 7 mK and 30 K and magnetic fields up to 12 T. We shall describe the effects of AC loss heating in such systems on the pulse tube refrigerator when the field is ramped and also the effects of eddy current heating on the mixing chamber in sweeping fields. 相似文献
16.
Plates of Al-6061-T6 with a thickness of 12.7 mm were welded with a non-heat treatable ER4043 electrode in four welding passes using the typical single V groove butt joint (at room temperature) and in one pass using the novel modified indirect electric arc (MIEA) joint (at 50, 100 and 150 °C). Microstructural characterization of the weld metal revealed that the MIEA joint design yielded microstructures in which columnar growth was restricted and a grain refining effect occurred without the addition of inoculants, even with preheating of the joints. The self-refining effect in the MIEA joint was discussed in terms of the cooling behavior and the large dilution of base material. Vickers microhardness profiles revealed that the high dilution rates obtained with the MIEA joint caused alloying of the weld pool with magnesium producing a weld metal composition sensible to heat treating due to the precipitation of Mg2Si precipitates. The grain self-refining effect of the MIEA joint along with alloying of the weld metal were found to have a profound impact on the mechanical properties of the welded joints. 相似文献
17.
大姚崩落采矿法借计算机模拟优选采场参数 总被引:1,自引:0,他引:1
目前大姚铜矿氧化矿采用的是底盘漏斗崩落采矿法。可是矿石损失值很高,虽然矿山做了大量工作,但是仍然不能将其降至设计的指标。鉴于目前的状况,为了掌握在矿山具体条件下崩落矿岩的流动规律;矿体产状、采场结构参数以及回采工艺与回贫指标之间的关系;以便为改进采矿方法、结构参数和回采工艺提供具有说服力的依据。展开了计算机模拟的最优化研究。论文说明了计算机模拟的试验方法并且分析了所获得的结果,提出了对实际生产具有指导意义的选择与建议。 相似文献
18.
We report the design, main features and on-ground qualification of the dilution cooler qualification model for the Planck mission. We mainly emphasize the innovative cryogenics and structural aspects developed in order to meet the severe requirements of the mission. We also report the results of the dilution cooler itself in the 100 mK range after successful tests of the qualification model on a dedicated test bench. 相似文献
19.
卫星导航多系统组合定位技术可以充分发挥各个卫星导航系统的优势,能够大大提高系统的可用性、连续性、可靠性和精度。本文主要对组合定位方式下的几何精度因子进行详细分析,这对多系统组合定位技术的研究具有一定的实际意义和参考价值。 相似文献
20.
E. M. Stanciu A. Pascu M. H. Ţierean I. Voiculescu I. C. Roată C. Croitoru 《Materials and Manufacturing Processes》2016,31(12):1556-1564
This paper presents an alternative approach to obtaining crack- and pore-free NiCrBSiFeCuMoC hard coatings on a low alloy steel substrate through coaxial laser cladding, by using Inconel 718 as a buffer layer between the hard coating and the base material. The presence of the buffer layer reduces the overall cracking susceptibility of the hardfacing material by reducing the compressive stresses developed during the cladding process and ensuring a more uniform heat distribution gradient at the surface of the material than the base metal alone, which provides an additional hardness and wear coefficient increase of 7% and improves the corrosion resistance of the obtained materials by 20%, in comparison with the reference sample obtained without an intermediate layer, by using the same operational parameters and minimizes elemental dilution with the substrate. Our method could prove useful in increasing the quality and life cycle of expensive high-performance hard-coated materials, especially those working under demanding operational and environmental conditions. 相似文献