Quaternary Heusler alloy Ni 50 Mn 8 Fe 17 Ga 25 ribbons have been prepared by the melt-spun method. The ribbons exhibit large negative magnetoresistance ͑MR͕͒=͓R͑H͒ − R͑0͔͒ / R͑0͖͒ over a wide temperature region, particularly in the region during the martensitic phase transformation. The MR decreases significantly after annealing. The large MR is isotropic and is mainly attributed to the local magnetic disorders, magnetic clusters, and heterogeneity. The maximum MR at martensitic transformation may be due to the redistribution of electrons and the increase of phase boundary scattering. This feature adds a useful functionality to the already interesting Heusler alloys.
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SummaryThe effect of lead on soil nematode communities at the 0 -20 cm depth was investigated along an increasing distance from a highway in Northeast China. The results showed that the abundance of total nematodes significantly increased from 40 m and then decreased eventually and the similar trend was also found in most indices studied. Thirty seven genera of nematodes belonging to 8 orders and 24 families were observed in our study, and Helicotylenchus was eudominant genus at all the sampling sites. The numbers of total nematodes significantly correlated with total and available Pb (P < 0.05), while ΣMI had a significantly negative correlation with TOC, Total N (P < 0.01) and C/N ratio (P < 0.05). Total and available Pb in soil had positive correlation with the numbers of total nematodes and bacterivores. The concentration of Pb also had an effect on abundance of Helicotylenchus, which increased in moderate concentration of Pb. NCR could be effectively used as indicators, as it was sensitive to concentration of Pb.
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