Browsing Radiocarbon, Volume 30 (1988) by Title
Now showing items 1-20 of 38
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13th International Radiocarbon ConferenceAmerican Journal of Science, 1988-01-01
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13th International Radiocarbon ConferenceAmerican Journal of Science, 1988-01-01
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Determination of Radon by Liquid Scintillation alpha/Beta Particle Spectrometry: Towards the Resolution of a 14C Dating ProblemTraces of uranium and radium within the 14C sample generate radon (Rn) which gets occluded during the benzene synthesis, thus generating false (extra) counts within the 14C counting window. This, if undetected, gives rise to erroneous 14C age determinations. The application of simultaneous alpha and Beta liquid scintillation spectrometry will enable a mathematical evaluation of the 14C signal unaffected by alpha and Beta particle emissions from radon decay daughters.
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Growth Rates of Natural Amazonian Forest Trees Based on Radiocarbon MeasurementsEvergreen trees in the tropical rain forest of the Amazonas Basin can produce growth rings which are not necessarily related to annual events. Therefore, estimation of growth rate cannot be done by dendrochronology. This report presents a technique for determining the growth rate of these trees based on radiocarbon measurements of two segments of equal radial distance from the outer part of the tree trunk. The measured 14C activity is compared to local 14C fallout and growth rates are derived from models taking into account bomb 14C effects. Eleven trees from various parts of the Amazon Basin were analyzed. The average growth rates range from ca 5 to > 40 yr per centimeter corresponding to extrapolated ages from ca 60 to > 400 yr.
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Improved Collagen Extraction by Modified Longin MethodA re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein ("collagen") remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product.
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LaboratoriesAmerican Journal of Science, 1988-01-01
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Microwave Oven Pretreatment of Carbonates for 14C Dating by Accelerator Mass SpectrometryA microwave oven is used to pretreat carbonate samples prior to graphitisation and radiocarbon dating by accelerator mass spectrometry. The method reduces the risk of contamination of small carbonate samples and provides a fast and convenient method for the acid evolution of CO2.
