ABSTRACT
Two main non-destructive techniques can be used to measure standard 222Rn gas ampoules: well-type ionization chambers and gamma-ray spectrometry, the former being used in the Système International de Référence (SIR) for international comparison purposes. The reliability of these techniques requires that the variability of the flame-sealed gas glass ampoules used have a negligible influence on the detector response. This variability is studied in this work by considering three parameters: the volume of the ampoule, the position of the sealing point and the thickness of the glass. Results showed that variability of the gas ampoules induced measurement bias larger than the uncertainty of the standard sources.
ABSTRACT
The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10-6 to 10-5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.
ABSTRACT
Many pharmacokinetic studies have been undertaken following both intravenous and oral administration in diseased patients after acute or chronic administration. Studies were carried out on COLD patients (IV and PO routes), patients with renal insufficiency (PO route) and patients with hepatic insufficiency (PO route). Plasma almitrine bismesylate assays are performed by a simple, sensitive and specific technique using a thermoionic nitrogen detector. Pharmacokinetic results obtained are compared to those obtained on healthy volunteers and discussed in terms of absorption, distribution and elimination. Results show that for the same administered dose, pharmacokinetic profile in COLD patients is close to the pharmacokinetic profile obtained on healthy volunteers. After six months' treatment the levels are not dependent on the subject's age or weight. In patients with renal insufficiency total plasma clearance is unchanged, mean steady state levels will be the same as normal patients and almitrine bismesylate can be administered in renal subjects without a change in dosage. In patients with liver insufficiency results are more variable. Some subjects have the same profile as healthy volunteers but absorption is diminished in others. Regarding the variability in kinetics and potential for impaired elimination, almitrine bismesylate should be titrated carefully in hepatic insufficiency.
