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Semi-conducting polyethylene (PE) nanocomposites with outstanding magnetic properties at room temperature were synthesized. These exceptional properties, for a diamagnetic and insulating matrix as PE, were obtained by polymerizing ethylene in the presence of a catalytic system formed by a metallocene catalyst supported on a mixture of reduced graphene oxide (rGO) and carbon nanotubes with encapsulated iron (CNT-Fe). It was used a constant and very low amount of CNT-Fe, obtained by vapor chemical deposition using ferrocene. The percolation threshold, to achieve conductivity, was obtained using a variable amount of rGO. The nanocomposites were semiconductors with the addition of 2.8 wt % and 6.0 wt % of the filler, with electrical conductivities of 4.99 3 10 26 S cm 21 and 7.29 3 10 24 S cm 21 , respectively. Very high coercivity values of 890-980 Oe at room temperature were achieved by the presence of only 0.04-0.06 wt % of iron in the nanocomposites. The novelty of this work is the production of a thermoplastic with both, magnetic and electric properties at room temperature, by the use of two fillers, that is rGO and CNT-Fe. The use of a small amount of CNT-Fe to produce the magnetic properties and variable amount of rGO to introduce the electrical conductivity in PE matrix let to balance both properties. The encapsulation strategy used to obtain Fe in CNT, protect Fe from easy oxidation and aggregation.

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Two fast, simple and reliable methods for the determination of Cu and Mn in infant formula were developed by HR-CS GF AAS.