Pb isotopic variability in melt inclusions from oceanic island basalts, polynesia     

AE Saal  SR Hart  N Shimizu  EH Hauri  GD Layne 《Science (New York, N.Y.)》1998,282(5393):1481-1484

Previous studies have suggested that melting processes are responsible for the trace element variability observed in olivine-hosted basaltic melt inclusions. Melt inclusions from three individual lava samples (two from Mangaia, Cook Islands, and one from Tahaa, Society Islands) have heterogeneous Pb isotopic compositions, even though the erupted lavas are isotopically homogeneous. The range of Pb isotopic compositions from individual melt inclusions spans 50 percent of the worldwide range observed for ocean island basalts. The melt inclusion data can be explained by two-component mixing for each island. Our data imply that magmas with different isotopic compositions existed in the volcanic plumbing system before or during melt aggregation.  相似文献   

A New Method for Isolation and Purification of Mammalian Striated Myofibrils     

Schick AF  Hass GM 《Science (New York, N.Y.)》1949,109(2837):486-487

  相似文献   

Photochemistry of vinclozolin in water and methanol–water solution     

Bernhard Schick  Pran N Moza  Klaus Hustert  Antonius Kettrup 《Pest management science》1999,55(11):1116-1122

The photolysis of the fungicide vinclozolin in aqueous and methanol–water (50 + 50 by volume) solution has been examined. Irradiation at λ = 254 nm for 10 minutes resulted in <90% and ≤95% substrate transformation respectively. The dissipation of vinclozolin both in water and methanol + water was linear and the calculated half-lives were 1.01 and 2.0 min respectively. Irradiation (8 h) with UV light (λ ≥ 290 nm) resulted in 10% degradation of the chemical, which is of the same magnitude as that of the control (not irradiated). Irradiation (8 h) under artificial sunlight (Suntest) in the presence of commercially available humic acid (K-salt) resulted in 55% degradation of the chemical. Photolysis leads to the opening of the 2,4-oxazolidine-dione ring, forming 3,5-dichlorophenyl isocyanate and 3,5-dichloroaniline. In addition, dechlorination and elimination of the  CHCH₂ moiety takes place, and one or both the chlorine atoms are replaced by a methoxy group. © 1999 Society of Chemical Industry  相似文献