38 research outputs found

    Investigation of the composition of the Luna 16 lunar sample

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    The concentrations of aluminum, manganese, sodium, chromium, iron, cobalt, and 12 rare earth elements were determined by neutron activation analysis using slow neutrons. Oxygen and silicon were determined using a fast neutron generator. Mossbauer spectroscopy was used to investigate iron compounds in Luna 16 regolith samples from the upper part of the core

    Elemental Composition of Infusions of Herbs (Tisanes) of North Ossetia (the Caucasus)

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    Herbal infusions are consumed worldwide owing to their beneficial properties. Cultivated or obtained from the wild, herbal raw plant materials may contain trace elements at various levels. This study relates to the release of beneficial and potentially toxic trace elements from herbal preparations during infusion. The elemental contents of seven commercially available herbal tea products were determined prior to and following two modes of infusion. Teabags (of equal herb content) were infused in 200 mL of boiling bottled water “Holy Spirit” for 15 and 45 min, in glass beakers. The total content of 57 elements including heavy metals, rare earth elements, as well as Th and U, were determined by ICP-MS and ICP-AES. The metals present in the highest concentrations were K, Ca, P, and S. Potassium, Mg, Co, Ni, As, Rb, and Cs had the highest extractability, whereas Ga, Ge, Se, Zr, Nb, Te, Er, Yb, W, Tl, and U had the lowest extractability

    Mechanism of Exciplex Decay: The Quantum Yields and the Rate Constants of Radical Ion Formation from Exciplexes with Partial Charge Transfer

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    The dynamics of exciplex and radical ion formation was studied in donor–acceptor systems with G * et > –0.1 eV. It was shown that the quenching of excited singlet states of aromatic molecules by electron donors in polar solvents led to the formation of radical ions via exciplex dissociation resulting to complete charge separation. Intersystem crossing and internal conversion into the ground state (back electron transfer) compete with this process. The quantum yields and the rate constants of the radical ion formation were measured
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