@article{oai:nipr.repo.nii.ac.jp:00004553,
 author = {Sugiura,Naoji and Hashizume,Ko},
 journal = {Proceedings of the NIPR Symposium on Antarctic Meteorites},
 month = {Mar},
 note = {P(論文), A systematic search for presolar grains in ordinary chondrites was made by measuring isotopes of nitrogen. Only one chondrite (Yamato-74191) out of 20 ordinary chondrites showed the presence of very heavy nitrogen of probably presolar origin. The heavy nitrogen is not particularly concentrated in either magnetic nor non-magnetic fractions. The HF/HCl residue is enriched in nitrogen but the heavy nitrogen seems to have been lost by acid treatments. The carrier of the heavy nitrogen has not been identified. The release patterns of excess ^<15>N are similar to those of primordial Ar. Chondrites more primitive than the Y-74191 do not contain the heavy nitrogen, suggesting heterogeneous distribution of the carrier of the heavy nitrogen. Together with evidence for the heterogeneous distribution of presolar SiC in meteorites, it is concluded that exotic materials were not well mixed in the primitive solar nebula.},
 pages = {352--370},
 title = {Heavy nitrogen in the Yamato-74191 and the heterogeneity of the primitive solar nebula},
 volume = {4},
 year = {1991}
}