Synthesis and biological evaluation of novel D-ring fused steroidal (2)-substituted-1,2,3-triazoles.

In this study, a series of 13 new D-ring fused steroidal (2)-substituted-1,2,3-triazoles were synthesized, characterized and evaluated for their biological activities. The relative binding affinities of the synthesized compounds for the ligand-binding domains of estrogen receptors α and β, androgen receptor and glucocorticoid receptor demonstrated that androstane derivatives 3a and 3h and estratriene derivative 4e showed highly specific and strong binding affinity for estrogen receptor β, while 3b, 3e, 4a and 4b displayed high binding affinity for the glucocorticoid receptor. The synthesized compounds were tested for their ability to inhibit aldo-keto reductases 1C3 and 1C4 by monitoring NADPH consumption using fluorescence spectroscopy.

Evaluation of different LSC methods for Rn determination in waters.

Monitoring of Rn in drinking or surface waters, as well as in groundwater has been performed regularly in connection with geological, hydrogeological and hydrological surveys and health hazard studies. Liquid scintillation counting (LSC) is often preferred analytical method for Rn measurements in waters as it allows multiple-sample automatic analysis. LSC method implies mixing of water samples with organic scintillation cocktail, which triggers radon diffusion from the aqueous into an organic phase for which it has a much greater affinity, eliminating the possibility of radon emanation in that manner.

Possibilities and limitations of color quench correction methods for gross alpha/beta measurements.

Gross alpha/beta activity determination is utilized as a very popular Liquid Scintillation Counting (LSC) technique widely used in routine monitoring of drinking, surface and waste waters. Since quenching phenomena are most problematic effect during LSC measurements, the objectives of this paper are to present, consider and evaluate two methods for color quench correction as a proposal for supplement to the ASTM D 7283-06 method for gross α/β determination. The first method is PSA adjustment: application of previously established dependence of optimal PSA discriminator between alpha and beta events on quench level of sample.

Sr determination in water samples using Čerenkov radiation.

A procedure for the determination of Sr in environmental water samples using Čerenkov radiation and low-level liquid scintillation counter Quantulus 1220 was applied and optimized. Low diffusion polyethylene vials, high performance glass counting vials and low potassium borosilicate glass vilas of 20 ml volume (all from PerkinElmer) were used in order to examine their potential effect on counting process. The derived efficiencies were 45.

PSA discriminator influence on (222)Rn efficiency detection in waters by liquid scintillation counting.

A procedure for the (222)Rn determination in aqueous samples using liquid scintillation counting (LSC) was evaluated and optimized. Measurements were performed by ultra-low background spectrometer Quantulus 1220™ equipped with PSA (Pulse Shape Analysis) circuit which discriminates alpha/beta spectra. Since calibration procedure is carried out with (226)Ra standard, which has both alpha and beta progenies, it is clear that PSA discriminator has vital importance in order to provide precise spectra separation.

Radionuclide, scintillation cocktail and chemical/color quench influence on discriminator setting in gross alpha/beta measurements by LSC.

Gross alpha/beta measurements in drinking waters enable radiochemical composition analysis in environmental studies providing efficient screening method that can indicate whether water contains elevated levels of any radionuclide. Routine gross alpha/beta activity monitoring in drinking waters has been carried out for a few years in laboratory for low-level radioactivity measurements in Novi Sad according to ASTM method, performing measurements on liquid scintillation counter Quantulus 1220 which can simultaneously generate alpha/beta spectra of samples by Pulse Shape Analysis (PSA circuit). In this paper, PSA discriminator impact was investigated to ensure obtaining of accurate and reliable alpha/beta activities.

Improvement of measuring methods and instrumentation concerning (222)Rn determination in drinking waters - RAD7 and LSC technique comparison.

A procedure for the determination of (222)Rn in environmental water samples using liquid scintillation counting (LSC) was applied and optimized. A minimum detectable activity of 0.029Bql(-1) in a 20ml glass vial (10ml water sample mixed with 10ml of liquid scintillation cocktail) has been achieved during 300min of measurement time.