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- Author or Editor: S. Ivanova x
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Abstract
The possibilities of liquid membrane preconcentration of neptunium from environmental samples of different nature have been studied. The use the solid-supported liquid membrane containing a trioctylmethylammonium nitrate carrier allows to achieve preconcentration factors of 102–5×102. The teflon solid support does not interact with the luminescent matrix (CaF2, PbMoO4) during calcination at 900 °C, so it makes practical to measure the neptunium content by luminescence without reextraction to aqueous solution. As a result, the detection limit of neptunium is lowed down to 10–13 g ml–1 and 5×10–13 g g–1 for pure solutions and soils, respectively.
Abstract
Conditions for neptunium recovery from nitrate solution containing large amounts of uranium by extraction with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP), and a mixture of PMBP with di-2-ethyl-hexylphosphoric acid (HDEHP) were studied. A two-stage technique, based on removal of uranium macroamounts at the first stage by means of extraction of uranium with PMBP and HDEHP mixture, and neptunium extraction by PMBP at the second stage, was suggested.
Abstract
Determination of microamounts of plutonium isotopes by luminescent radiation in the infra-red region of PbMoO4 crystallophosphors activated by plutonium is proposed. The determination is possible against the background of subtantial amounts of uranium, iron, rare earths and other elements. The detection limit of plutonium is 10–9 g in the samples tested. The accuracy is 0.1 for a confidence level of 0.95.
Aronia melanocarpa fruit juice (AMFJ) used in this experiment was very rich in phenolic substances, anthocyanins being the main flavonoid group. The antioxidant action of AMFJ was determined in vitro through measuring its Trolox equivalent antioxidant capacity (TEAC), superoxide dismutase (SOD)-like activity and catalase (CAT)-like activity. The TEAC of AMFJ was 63±0.8 mM. The SOD-like activity of 1 ml AMFJ was equivalent to that of 230.3±8.4 U SOD and was equal to that of 12.3 mg L-ascorbic acid and 11.4 mg Trolox, respectively. The CAT-like activity of 1 ml AMFJ was equivalent to the activity of 3223.5±91.3 U CAT and was equal to that of 6.4 mg L-ascorbic acid, while Trolox did not show such an activity. The pronounced antioxidant action of AMFJ is probably due to its high content of phenolic compounds.
The research presents the effect of novel edible coatings based on low molecular weight chitosan on some properties of fresh-cut melon fruits – weight loss, total soluble solids, total acidity, mechanical strength and bacteria growth. Three different compositions were used as coatings – pure chitosan, chitosan and Ca lactate and alginate/chitosan multilayers. It was shown that the additional alginate layer substantially improves the protective properties of pure chitosan coating, resulting in preservation of cell structure. Negligible negative effect on the antibacterial activity of pure chitosan is demonstrated.
