نتایج جستجو برای: lead isotopes
تعداد نتایج: 362795 فیلتر نتایج به سال:
The Markov chain statistical multifragmentation model predicts inhomogeneous distributions of fragments and their isospin in the freeze-out volume caused by an angular momentum and external long-range Coulomb field. These effects can take place in peripheral nucleus-nucleus collisions at intermediate energies and lead to neutron-rich isotopes produced in the midrapidity kinematic region of the ...
Background: Numerous models show that if morphology and diet are correlated, frequencydependent competition will lead to fitness differences among phenotypically dissimilar individuals within a species. Hypothesis: Selection acts primarily on diet, and only indirectly on morphology via its correlation with diet. Field sites and organism: British Columbia, Canada; 340 individual threespine stick...
We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica re...
Coral-based history of lead and lead isotopes of the surface Indian Ocean since the mid-20th century
a Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA b Center for Environmental Sensing and Modeling, Singapore–MIT Alliance for Research and Technology, Singapore c Center for Oceanography and Marine Technology, Surya University, Indonesia d Institute of Geology and Paleontology, RWTH Aachen University, Aachen, Germany e Earth Ob...
Lead isotope ratios ((206)Pb/(207)Pb and (208)Pb/(207)Pb) and concentrations in the livers and bones of marbled teal and white-headed duck found dead or moribund were determined in order to establish the main lead source in these waterfowl species. Lead concentrations in bone (dry weight) and liver (wet weight) were found to be very high in many of the white-headed ducks (bone: geometric mean=8...
Dated sediment cores from four remote Canadian Shield headwater lakes, where atmospheric deposition has been the only input of anthropogenic Pb, situated along a transect extending 300 km from a nonferrous metal smelter, were analyzed for both lead concentrations and isotopic composition; porewater samples collected at the same sites were analyzed for Pb and other geochemical variables. The dep...
A method for the determination of Pb isotope ratios (IR) in cigarette tobacco by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) has been developed and applied to tobacco samples from genuine and counterfeit cigarettes obtained in the USA. The IR ²⁰⁷Pb/²⁰⁶Pb, (208)Pb/²⁰⁶Pb, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb were measured using a Q-ICP-MS instrument. Two certified refer...
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