Results 191 to 200 of about 742 (235)
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Recalcitrant Dissolved Organic Carbon Fractions
Annual Review of Marine Science, 2013Marine dissolved organic carbon (DOC) exhibits a spectrum of reactivity, from very fast turnover of the most bioavailable forms in the surface ocean to long-lived materials circulating within the ocean abyss. These disparate reactivities group DOC by fractions with distinctive functions in the cycling of carbon, ranging from support of the microbial ...
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Carbonization of coker feedstocks and their fractions
Carbon, 1986Abstract Carbonization studies of petroleum vacuum distillation residua have been carried out on a laboratory scale with the objective of developing a better understanding of the causes and mechanisms of the incidence of shot coke formation in delayed coking.
S. Eser +3 more
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Carbon isotope fractionation during the precipitation of calcium carbonate
Earth and Planetary Science Letters, 1970The fractionation of the carbon isotopes12C and13C in the equilibrium system CO2 (gas)-HCO3−(dissolved- CaCO3 (solid) has been measured at temperatures between 20°C and 60°C. The fractionation between solid carbonate and gaseous carbon dioxide,ecg,is+(10.17 ± 0.18)ooo at 20°C and the temperature dependence,dccg/dT,is−(0.063 ± 0.008)ooo/°C at 20°C.
K. Emrich, D.H. Ehhalt, J.C. Vogel
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Fractionation of Sulfur and Carbon Isotopes in a Meromictic Lake
Science, 1963In the permanently stagnant depths of Green Lake (near Syracuse, N.Y.), sulfide made by bacteria is depleted in heavy sulfur (S 34 ), and sulfate is enriched. The fractionation factor, 1.0575, is the greatest yet observed.
E S, Deevey, N, Nakai, M, Stuiver
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Carbonization of Carbonates and Fractionation of Stable Carbon Isotopes in a Dynamic Slip Zone
Geochemistry International, 2020Data obtained on carbonates and metaterrigenous rocks of the Devonian complex of the Sultan-Uizdag Range, northwestern Uzbekistan, which are carbonized in local deformation zones, are used in a generalized interpretation of the genesis of carbonaceous matter by means of decomposition of carbonates under the effect of seismogenic movements.
Yu. A. Morozov +3 more
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Evaluation of an expired fraction carbon dioxide monitor
Anaesthesia, 2002Summary Respiratory monitoring is an important aspect of critical care, especially in neurosurgery and neuro‐intensive care. Fixed capnographs are too cumbersome to allow monitoring during patient transport. Recently several portable expired fraction carbon dioxide devices have been developed, but no evaluation ...
U, Ratnasabapathy, S, Allam, M J, Souter
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Carbon Isotope Fractionation in Bacterial Production of Methane
Science, 1959Anaerobic bacteria from a Pacific Ocean mud cause unusually large carbon isotope fractionations during fermentation of methanol. The methane produced is about 8 percent enriched in C 12 , relative to the original methanol.
W D, ROSENFELD, S R, SILVERMAN
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Carbon isotope fractionation in plants
Phytochemistry, 1981Abstract Plants with the C 3 , C 4 , and crassulacean acid metabolism (CAM) photosynthetic pathways show characteristically different discriminations against 13 C during photosynthesis. For each photosynthetic type, no more than slight variations are observed within or among species.
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Photoluminescent Carbon Dots: A Mixture of Heterogeneous Fractions
ChemPhysChem, 2018AbstractPhotoluminescent carbon dots (CDs) fractions have been isolated from a gel‐like material (GM), which was synthesized using a convenient one‐step solvothermal route. In terms of purification, size exclusion chromatography (SEC) and dialysis were compared with acetone wash, which revealed the advantage of acetone wash.
Yiqun Zhou +9 more
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Mechanism of Carbon Isotope Fractionation Associated with Lipid Synthesis
Science, 1977The low carbon-13/carbon-12 ratio of lipids is shown to result from isotopic fractionation during the oxidation of pyruvate to acetyl coenzyme A. In vitro analysis of the kinetic isotope effects of this reaction indicates that there will be a large, temperature-dependent difference in the carbon-13/carbon-12 ratio between the methyl and carbonyl carbon
DeNiro, Michael J., Epstein, Samuel
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