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Lead is contained as trace element in uranium ores and propagates throughout the production process to intermediate products like yellow cake or uranium oxide. The lead isotopes in such material originate from two sources: natural lead and radiogenic lead. The variability of the isotopic composition of lead in ores and yellow cakes was studied and the applicability of this parameter for nuclear forensic investigations was investigated. Furthermore, the chemical impurities contained in these materials were measured in order to identify characteristic differences between materials from different mines. For the samples investigated, it could be shown, that the lead isotopic composition varies largely from mine to mine and it may be used as one of the parameters to distinguish between materials of different origins. Some of the chemical impurities show a similar pattern and support the conclusions drawn from the lead isotope data.

Iron oxide nanorods are considered to be very promising platforms for biomedical applications, such as magnetic hyperthermia, magnetic resonance imaging, or immunoassays based on magnetooptical effects. However, their efficient colloidal stabilization is challenging, and colloidal aggregation could lead to the total loss of their performance. This work is focused on the synthesis and colloidal stabilization of iron oxide nanorods of an average length and diameter, L × d = 31 × 6 nm, synthesized by the hydrolysis of iron­(III) salt, followed by reduction of the obtained akaganeite to iron oxide in a microwave reactor. Synthesized nanorods exhibited a weak ferrimagnetic behavior with remnant magnetization M R ∼ 3 emu/g and saturation magnetization M S ∼ 13 emu/g. The nanorods were dispersed in water after adsorption on their surface of three different polymers: linear bisphosphonate–poly­(ethylene glycol) (PEG) molecules (denoted as OPT), polymethacrylate backbone/PEG side chains comb polymer (denoted as PCP; with PEG brushes both extended toward the solvent and having molecular weight M w ∼ 3000 g/mol), and polyacrylic sodium salt (PAA; M w ∼ 15000 g/mol). Experiments and theoretical evaluation of the interaction potential show that increasing the polymer grafting density on the nanorod surface as well as decreasing the concentration of a nonadsorbed polymer improve the nanorod colloidal stability. The best stability is obtained on an optimal range of weight ratio of the added polymer to the nanorods between 0.5 and 1.6 mg/mg. A higher grafting density reached with a OPT polymer with a bisphosphonate terminal group (2–4 nm–2) allows much better stability than using multiple adsorption with PCP (0.2–0.4 nm–2) or PAA. Even though the nanorods are still subject to some aggregation (effective hydrodynamic diameter ∼60 nm, compared to their TEM size of L × d = 31 × 6 nm), significant progress toward understanding their colloidal stability was achieved.

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The present study investigates thermally induced crystallization and phase evolution of amorphous calcium phosphate (ACP) partially substituted with Fe3+ ions (M/P = 1.5 : 1). It was demonstrated that the...

The monoclinic Sn2P2S6 and rombohedral layered SnP2S6 crystals have been investigated by 119Sn Mössbauer and X‐ray photoelectron spectroscopies. By comparing the isomer shift, quadrupole splitting and binding energies for Sn 3d and 4d core levels in these crystals with such parameters for the metal tin and for different tin compounds it was found that in the Sn2P2S6 crystals Sn existed in the Sn2+ oxidation state and in the SnP2S6 crystals – in the Sn4+ state. Temperature dependences of the isomer shift and Debye–Waller factor satisfied the Debye model in the temperature interval of 6 – 300 K for the SnP2S6 crystals but deviated from such behavior at T > 250 K for Sn2P2S6 crystals. This peculiarity together with specific character of the temperature dependence of the quadrupole splitting were related to the role of the stereoactive Sn 5s2 lone pair electrons in the determined by three‐well potential mechanism of the second order ferroelectric phase transition at 337 K in Sn2P2S6 crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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