1) Dilution of samples with incubation medium arrested calcium uptake but did not remove extracellularly bound calcium.2) Dilution with medium containing 0.4 mmol 1 −1 La Cl 3 not only arrested calcium uptake but also prevented calcium efflux and, if enough time was allowed, displaced extracellular calcium.
3) Dilution with medium containing 3 mmol 1 −1 EGTA gave uptake values similar to those obtained with La 3 , but only if extensive extraction of calcium was prevented by rapid handling of samples.
Results obtained after quenching with La 3 or EGTA showed that calcium uptake by synaptosomes may be a multiphasic process, which emphasizes the need for techniques that allow for satisfactory time resolution.
We describe here in general terms the experimental method we use to detect and "count" very rare atoms or particles, such as the cosmogenic nuclides we discussed above.
Accelerator Mass Spectrometry (AMS), a sophisticated detection technique,identifies and counts rare atoms, such as radiocarbon and other cosmogenic nuclides, at an unprecedented level of sensitivity.
To provide access without cookies would require the site to create a new session for every page you visit, which slows the system down to an unacceptable level.Is there some information on time or age, embedded in Nature and its nuclei, be it on cosmological, galactic, geologic, prehistorical or historical time scales ? Our research, extending to several disciplines, is devoted to these questions.Literature and Links : stable nuclides which constitute matter as we know it, ourselves, our computer chips, the planets around us, have been synthesized in the stars of our Galaxy.This brings about related questions : when were all other elements created or "synthesized"?Are some of the nuclei we are made of "primordial" in any sense ? Are there other "radiogenic" nuclides, or otherwise produced ?Let us take two examples taken from two different disciplines.