نتایج جستجو برای: fractionation
تعداد نتایج: 19571 فیلتر نتایج به سال:
The discovery by Farquhar et al. (1) of mass-independent isotope fractionation of S and S in rocks formed more than ;2 billion years ago (Ga), but not in younger rocks, has boosted the theory postulating a dramatic change from an anoxic to an oxygen-rich atmosphere about 2 Ga. That is because the only known natural process that may cause mass-independent fractionation of both S and S involves a...
[1] Analysis of experimental ozone absorption spectra reveals that ultraviolet photolysis within the structured Huggins band yields extraordinary wavelength-dependent isotopic fractionation, oscillating between complete enrichment and complete depletion for changes of less than 2 nm in the excitation wavelength. Visible photolysis yields wavelength-dependent fractionation that varies from 300% ...
We present a quantitative model for sulfur isotope fractionation accompanying bacterial and archaeal dissimilatory sulfate respiration. By incorporating independently available biochemical data, the model can reproduce a large number of recent experimental fractionation measurements with only three free parameters: (i) the sulfur isotope selectivity of sulfate uptake into the cytoplasm, (ii) th...
Human Serum albumin as well as other biological products prepared by blood fractionation for clinical purposes, was found to contain different amount of aluminum in different commercially available human albumin solutions. It has been reported that interaction of chemicals with the container material can occur during plasma collection, manufacture and storage, so aluminum is introduced into alb...
Inter-element fractionation in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis is one of the major challenges for using the technique for in situ trace element determination and isotopic ratio measurement of geological, environmental and biological solid samples. Attempts have been made to reduce inter-element fractionation in LA-ICP-MS analysis. However, this f...
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