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.

It is generally accepted that there is a vast, well-populated biosphere in the subsurface, but the depth limit of the terrestrial biosphere has yet to be determined, largely because of the lack of access to the subsurface. Here as part of the Chinese Continental Scientific Drilling (CCSD) project in eastern China, we acquired continuous rock cores and endeavored to probe the depth limit of the biosphere and the depth-dependent distribution of microorganisms at a geologically unique site, that is, a convergent plate boundary. Microbiological analyses of ultra-high-pressure metamorphic rock cores taken from the ground surface to 5,158-meter reveal that microbial distribution was continuous up to a depth of ~4,850 m, where temperature was estimated to be ~137°C. The metabolic state of these organisms at such great depth remains to be determined. Microbial abundance, ranging from 10 3 to 10 8 cells/g, was also related to porosity, but not to the depth and rock composition. In addition, microbial diversity systematically decreased with depth. Our results support the notion that temperature is a key factor in determining the lower limit of the biosphere in the continental subsurface. | 279 DAI et Al.