نتایج جستجو برای: carbon and sulfur stable isotopes
تعداد نتایج: 16921217 فیلتر نتایج به سال:
We used variation in algal d13C between river habitats to study the spatial scale of energy flow through river food webs. We found a strong negative relationship between herbivore d13C (which reflects algal d13C) and water velocity in three productive Northern California rivers but not in unproductive streams. The contrast among habitats suggests that water velocity affects algal d13C most stro...
Swart, P.K., 1983. Carbon and oxygen isotope fractionation in scleractinian corals: a review. Earth-Sci. Rev., 19: 51-80. The present theories on the fractionation of stable isotopes in scleractinian corals are critically discussed in the light of data available on primary productivity, respiration and stable isotope chemistry. These data support a model of fractionation in which the carbon and...
Various geochemical proxies have been developed to determine if ancient sedimentary strata were deposited in marine or nonmarine environments. A critical parameter for proxy reliability is the residence time of aqueous species seawater, which rarely considered relying on stable isotopes and elemental abundance ratios. Differences may affect our ability track geologically short-lived alternation...
Stable isotopes have been extensively used to trace element cycles and their incorporation into food webs. This chapter provides a brief introduction to the principles of using stable isotopes as natural or deliberate tracers in estuarine systems, with a focus on (1) assessing the origin and cycling of organic and inorganic elements (mainly carbon and nitrogen), (2) defining estuarine food webs...
The catalyst activity of fluorite-type oxide, such as ceria and zirconia, for the reduction of sulfur dioxide by carbon monoxide to elemental sulfur can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst with a feed gas of stoichiometri...
Hollow carbon spheres (HCS) with a nanoporous shell are promising for the use in lithium-sulfur batteries because of the large internal void offering space for sulfur and polysulfide storage and confinement. However, there is an ongoing discussion whether the cavity is accessible for sulfur. Yet no valid proof of cavity filling has been presented, mostly due to application of unsuitable high-va...
krytyn triplet alkyl esters ayzvsyanydha reactions and lead to the production of acetylene is stable.
The natural abundance of carbon-13 in blood proteins increases during the cachectic state and may be a biomarker for disease status. We hypothesized a corresponding drop in the relative abundance of 13C in breath CO2. Using the lipopolysacchride (LPS)-induced endotoxemia model of the acute cachectic state, we demonstrated that the acute phase response causes shifts in the stable isotopes of car...
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