scholarly journals You are not always what we think you eat: selective assimilation across multiple whole-stream isotopic tracer studies

Ecology ◽  
2014 ◽  
Vol 95 (10) ◽  
pp. 2757-2767 ◽  
Author(s):  
W. K. Dodds ◽  
S. M. Collins ◽  
S. K. Hamilton ◽  
J. L. Tank ◽  
S. Johnson ◽  
...  
Keyword(s):  
Tracer Studies ◽  
Isotopic Tracer

Isotopic tracer studies of the further reactions of pentenes in the combusion of pentane

1978 ◽  
Vol 364 (1718) ◽  
pp. 309-329 ◽  
Keyword(s):  
Molecular Mass ◽  
Peroxy Radical ◽  
Combustion Products ◽  
Secondary Products ◽  
Tracer Studies ◽  
Isotopic Tracer ◽  
Cool Flames ◽  
Hydroperoxy Radical ◽  
Lower Molecular Mass ◽  
Before And After

Detailed studies have been made of the mechanisms by which products other than the conjugate alkenes are formed when pentane undergoes combustion in the presence of small quantities of isotopically labelled pent-1-ene and pent-2-ene. Seven pentenes, specifically labelled with 14 C in different skeletal positions, have been synthesized and the fate of the labelled carbon atoms during combustion has been determined. Special attention has been paid to the formation and destruction of the pentadienes, acrolein and ethylene, as products derived from pent-1-ene. In particular, measurements have been made of the instantaneous fraction of the original pentene converted into each of these compounds and of the percentages have been shown to be derived exclusively from the pentenes, whilst acrolein and ethylene, which are complementary products resulting simultaneously from the same pentene molecule, are formed principally from the alkenes. It has also been possible to determine the distribution of the points of abstractive attack in the pentenes and the reactivity rations of pent-1-ene to secondary products. There are sharply defined changes in the relative rates for the pentadienes and pent-1-ene before and after the passage of cool flames; the results suggest that penta-1, 2-diene is oxidized to acrolein and ethylene. A significant amount of 2, 4-dimethyloxetan is formed from both pent-1-ene and pent-2-ene; this compound appears to be produced by a somewhat unusual route, involving the isomerization of one hydroperoxy radical to another through a peroxy radical. The majority of these compounds result from reactions involving free radial addition to the alkene molecule. However, abstractive modes of attack, although leading almost exclusively to the pentadienes, acrolein and ethylene, are quantitatively very important in terms of the total amount of attack on the pentenes. The principal products formed from the pentenes are only minor constituents of the combustion products of pentane. This shows that the coujugate alkenes do not play nearly as important a part in the combustion of pentane as they do in the case of alkanes of lower molecular mass.

Isotopic tracer studies of chemical behavior of rare earth elements in environmental and biological sciences

2004 ◽  
Vol 92 (4-6) ◽  
Author(s):  
Z. Y. Zhang ◽  
Zhifang Chai
Keyword(s):  
Biological Sciences ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Human Body ◽  
Anthropogenic Activities ◽  
Animal Husbandry ◽  
Chemical Behavior ◽  
Tracer Studies ◽  
Isotopic Tracer

AbstractRare earth elements (REE), a group of elements with atomic numbers from 57 to 71, have been widely applied in recent years not only in industry but also in agriculture, forestry, animal husbandry and medicine. Numerous anthropogenic activities make REE to easily enter the environment and finally the human body

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