CESR in superconductors: Relevance of highT c copper oxide systems

CESR is a highly effective tool to study the interaction among conduction electrons in normal metals. In superconductors belowT _c it can reveal vital information concerning the pairing interactions. A comparative study of highT _c and conventional superconductors is presented and it is shown that the disappearance of CESR in the superconducting state is a feature common to both conventional and highT _c superconductors and establishes the importance of exchange interactions in pairing. This is supported by experimental observations.     

均值-标准差质量控制图用于短碘量法测定进口铜精矿中铜含量的应用

根据GB/T3884.1-2012中短碘量法测定进口铜精矿中铜含量,实验中收集了 20组数据,用EXCEL函数功能计算其平均值,标准偏差,上下控制限,上下警戒限;以实验日期为横坐标,铜含量测定值为纵坐标,用EXCEL图表功能绘制质量控制图,持续监控日常铜精矿中铜含量的检测系统.结果表明:质量控制图可以直观和有效的控制铜...     

Effects of iodine intercalation into Bi-based copper oxide superconductors

We have investigated the stage-1 iodine-intercalation compounds, whose host materials are Bi₂Sr₂Ca_1–x Y _x Cu₂O₈ (Bi-2212 phase) and Bi_1.6Pb_0.5Sr_1.9–x La _x Cu_1.05O₆ (Bi-2201 phase) with variousx values. In the Bi-2212 phase, it has been found that the change inT _c through the stage-1 iodine intercalation is due to two effects; a change of the two-dimensionality and an increase in the carrier number. The former effect decreasesT _c by about 10 K independent of the carrier number of the host sample. The latter effect shifts thex dependence ofT _c to largerx values by about 0.08, taking account of oxygen release from the host samples during the intercalation process. This result is clear evidence for the occurrence of both the change of two-dimensionality and the increase in carrier number about 0.04 per CuO₂ unit due to the charge transfer through the stage-1 iodine intercalation. In the Bi-2201 phase,T _c decreases by about 10 K through the stage-1 iodine intercalation.     

An accurate method to measure alpha-emitting natural radionuclides in atmospheric filters: Application in two NORM industries

In this work, an accurate method for the measurement of natural alpha-emitting radionuclides from aerosols collected in air filters is presented and discussed in detail. The knowledge of the levels of several natural alpha-emitting radionuclides (²³⁸U, ²³⁴U, ²³²Th, ²³⁰Th, ²²⁸Th, ²²⁶Ra and ²¹⁰Po) in atmospheric aerosols is essential not only for a better understanding of the several atmospheric processes and changes, but also for a proper evaluation of the potential doses, which can inadvertently be received by the population via inhalation.The proposed method takes into account the presence of intrinsic amounts of these radionuclides in the matrices of the quartz filters used, as well as the possible variation in the humidity of the filters throughout the collection process. In both cases, the corrections necessary in order to redress these levels have been evaluated and parameterized. Furthermore, a detailed study has been performed into the optimisation of the volume of air to be sampled in order to increase the accuracy in the determination of the radionuclides.The method as a whole has been applied for the determination of the activity concentrations of U- and Th-isotopes in aerosols collected at two NORM (Naturally Occurring Radioactive Material) industries located in the southwest of Spain. Based on the levels found, a conservative estimation has been performed to yield the additional committed effective doses to which the workers are potentially susceptible due to inhalation of anthropogenic material present in the environment of these two NORM industries.     

An optically-based inverse method to measure in-plane permeability fields of fibrous reinforcements

Structural composite manufacturing relying on Liquid Composite Molding technologies is strongly affected by local variability of the fibrous reinforcement. Optical techniques using light transmission are used and allow field measurements of areal weight (and fibre volume fraction) of glass fibre reinforcement. The coupling of obtained areal weight mappings along with injection flow fronts is used to extract in-plane permeability fields. The current work presents results with a focus on glass random mats, but the method can be adapted to any glass fibrous medium. A study of convergence and error due to discretization is performed. Also the influence of the stacking of fibrous layers on the preform variability is analyzed. The major advantage of the proposed technique is a relatively fast acquisition of statistical data on reinforcement variability, which can be later utilized in stochastic based process simulations.