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Showing 1 to 20 of 242 for “"14C"”.
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Extraction and measurement of cosmogenic in situ 14C from quartz
Unlike 14C that is produced in the upper atmosphere by the 14N(n,p)14C reaction, in situ 14C is produced within minerals at the earth’s surface by a number of spallation reactions including 17O(n,α)14C, 16O(n,2pn)14C and 14N(n,p)14C (Gosse & Phillips, 2001). A range of cosmic-ray produced …
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Uptake and utilization of alanine-1-14C by freshwater algae.
Experiments were conducted x^ith Chlorella pyrenoidosa, Cosmarium formosulum, and Gloeocapsa sp. to determine their relative heterotrophic capacity at various conditions. Cultures were incubated in nutrient media with 0.5 uc DL-alanine-l-^C added at various temperature (10C, 20C, 30C) and …
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AMS-14C-Analysen zur Rekonstruktion der Landschafts- und Kulturgeschichte in der Region Palpa (S-Peru)
… Arbeit wurde auf der Grundlage von über 100 14C-Datierungen an organischem Material aus Siedlungsresten und Grabfunden sowie Material im direkten Fundzusammenhang mit den Geoglyphen der Region Palpa eine erste numerische Chronologie der Paracas- und Nasca-Kultur erstellt. Das Hauptaugenmerk …
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In vitro starch digestibility and ex-vivo glucose response studies of Vietnamese starchy foods using Caco-2 cells and 14C radioisotope
… measured by using Caco-2 cell models and ᴅ-[U-14C]glucose as a tracer.
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Characterization of Microbial Survivall in the Presence of Radioactive 14C Spiked Salts in Order to Minimize W,aste from Graphite Moderated Nuclear Reactors
… products. This study investigated the removal of 14C in irradiated graphite. Two experiments were performed. In the first experiment, non-irradiated graphite was exposed to a Mixed Culture (MC) of bacteria for 120 hours. The objective was to determine if bacteria thrives in the presence of inert …
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A 14C and 15N study of the effects of ammonium or nitrate nutrition on carbon allocation in Triticum aestivum L. and Zea mays L
The poor response of some plant species, e.g. wheat, to ammonium nutrition has been attributed to a diversion of carbon allocation from structural material for root extension to functions associated with the assimilation and translocation of ammonium in the root. The aim of this research was to …
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The biosynthesis of virginiamycin S₁
… precursors of virginiamycin S₁. L-(U-14C)-Proline and L-(U-14C)-threonine were effectively incorporated into the respective amino acid components in the antibiotic. N-Methyl-L-phenylalanine was shown to arise from L-(U-14C)-phenylalanine and L-(methyl-14C)-methionine. …
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Einfluss der Aufnahmewege auf die Toxikokinetik von Terbutryn und Benzo[a]pyren bei drei benthischen Invertebraten
… Wasser und Nahrung auf die Toxikokinetik der 14C-markierten Testsubstanzen Terbutryn und Benzo[a]pyren bei den aquatischen Invertebraten Gammarus fossarum, Asellus aquaticus und Lumbriculus variegatus haben. Es wurden die toxikokinetischen Parameter zur Aufnahme und Elimination von …
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Solare Variabilität und Klimaschwankungen auf einer Zeitskala von einigen Dekaden bis Jahrhunderten im Holozän
… Einfluss des Sonnenwindes entstehende Isotop 14C verwendet. Die 14C-Produktion wurde aus der an absolut datierten Baumringchronologien gemessenen atmosphärischen 14C-Konzentration D14C mit Hilfe eines auf H. Oeschger und U. Siegenthaler basierenden Boxmodells für den Kohlenstoffkreislauf …
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Radioanglies sklaidos biosferoje tyrimas branduolinės elektrinės aplinkoje /
… to adapt to environmental changes. While the 14C isotope influence to the climate is not observed, the total cumulative atmospheric carbon after the beginning of the industrial revolution has significantly increased. In the begining of the 20 century the Suess effect was observed – atmospheric …
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Tracking nuclear generating station emissions and fossil fuel contributions using tree rings in southern Ontario, Canada
… of stable (12C, 13C) and radioactive (14C) isotopes of carbon are an important indicator of the Anthropocene. Carbon from anthropogenic sources can be released to the atmosphere as radiocarbon (14C) from nuclear power and above-ground nuclear weapons testing. Carbon-12 and carbon-13 …
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Evaluating the Hazard of Land Applying Composted Diazinon Waste Using Earthworm Biomonitoring
… study determined the bioavailability of delta-2-14C-diazinon and its degradation products to E. foetida in soil amended with composted delta-2-14C-diazinon. Results from the first study indicate that uncomposted diazinon sorbent and 30-day composted diazinon sorbent were toxic to E. foetida at …
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Investigations of temporal changes in climate and the geomagnetic field via high-resolution radiocarbon dating
… increase in the atmospheric radiocarbon (14C) concentration, which has been interpreted to be a result of decreased solar activity. Therefore, a solar-induced climate change has been suggested. In addition to changes in solar activity, geomagnetic field records also show prominent …
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The Fate of Naphthalene and n-Alkylnaphthalenes During Combustion, and an Evaluation of the Sources of these Compounds in Diesel Exhaust Emissions
… by the use of a procedure which employed a [14C]radiolabelled PAH technique and a diesel enriched fuel technique (DEFT). The combustion of diesel fuel spiked with [14C]naphthalene has shown unequivocally that 0.5% of the naphthalene contained in diesel fuel survives combustion under the …
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Impact of Sulfonylurea Herbicides on Seeded Bermudagrass Establishment and Cold Temperature Influence on Perennial Ryegrass Response to Foramsulfuron
… to determine absorption and translocation of 14C flazasulfuron when applied to perennial ryegrass roots or foliage. Roots treated with 14C flazasulfuron absorbed 41% of recovered 14C while 25% of 14C moved from treated roots to foliage. It appears root absorption is an important component of …
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Paleoceanographic variability on a millennial scale: a high resolution record of the latest deglaciation from the Blake Outer Ridge, western North Atlantic
… to century scale between 14,000 and 10,000 14C years BP. Furthermore, between 13,500 and 13,300 14C years BP and 10,900 and 10,600 14C years BP, the coincidence of benthic foraminifera abundance maxima and benthic δ13C minima from C. wuellerstorfi indicate an increased influence of AABW …
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Studies in the Folate Metabolism of Rats
The metabolism of 2-14C folic acid was studied in three-week-old weanling Wistar rats. Distribution of radioactivity after an oral dose of 2-14C folic acid was determined in urine, faeces, liver, and gut of the animals. Some of the urinary metabolites were characterized by column chromatography. …
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Aspects of Folate and Tetrahydrofolate Chemistry and Metabolism in the Rat
… of (±)-5-formyltetrahydrofolic acid -(2-14C), (±)-5,10-methenyltetrahydrofolic acid -(2-14C), (±)-10-formyltetrahydrofolic acid -(2-14C), and 10-formylfolic acid -(2-14C) from folic acid -(2-14C) is described. These compounds, and commercial 5-( CH, )- methyltetrahydrofolic acid, were …
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