Thermodynamic properties of alloys binary In—Pr (Nd) and ternary In—Pr (Nd)—Ni systems

The thermochemical properties of In—Pr system melts in the range of compositions 0 < xIn < 0,4 and In—Nd in the whole concentration range at 1573 ± 1 K were investigated by isoperibolic calorimetry. The obtained data for the In—Pr system melts were extrapolated to the unexplored concentration interval, taking into account that at xPr = 1 the integral and partial mixing for Pr enthalpy are equal to zero. It was found that the first partial for Pr and the minimum enthalpy of mixing are equal to –139 ± 11 and –40,3 ± 0,2 kJ / mol, respectively. For the In—Nd system the first partial for In and Nd, the minimum enthalpy of mixing is equal to −131,7 ± 11, −140,6 ± 12 і –43,3  0,2 kJ / mol, respectively. Comparison of ΔHmin, melts of the five previously studied In—Ln systems from the ordinal number Ln (zLn) together with the data obtained in this work showed that they are described by a single trend line. For ΔHmin of melts of In—Eu (Yb) systems there are very insignificant deviations from the trend line. But for the size factor, these deviations from the trend line are more significant. The enthalpies of formation of some intermetallics of In—Ln systems are known, and most of them belong to the compound LnIn3. But there is no complete agreement between these data. The results of the most modern work show less dependence on the serial number of lanthanide and are more exothermic for heavy lanthanides, compared with other data. Keywords: thermochemical properties, compounds, melts, In, Pr, Nd.

Harnessing methylotrophs as a bacterial platform to reduce adverse effects of the use of the heavy lanthanide gadolinium in magnetic resonance imaging

Gadolinium is a key component of magnetic resonance imaging contrast agents that are critical tools for enhanced detection and diagnosis of tissue and vascular abnormalities. Untargeted post-injection deposition of gadolinium in vivo, and association with diseases like nephrogenic systemic fibrosis, has alerted regulatory agencies to re-evaluate their widespread use and generated calls for safer gadolinium-based contrast agents (GBCAs). Increasing anthropogenic gadolinium in surface water has also raised concerns of potential bioaccumulation in plants and animals. Methylotrophic bacteria can acquire, transport, store and use light lanthanides as part of a cofactor complex with pyrroloquinoline quinone (PQQ), an essential component of XoxF-type methanol dehydrogenases (MDHs), a critical enzyme for methylotrophic growth with methanol. We report robust gadolinium-dependent methanol growth of a genetic variant of Methylorubrum extorquens AM1, named evo-HLn, for evolved for heavy lanthanides. Genetic adaptation of evo-HLn resulted in increased xox1 promoter and XoxF MDH activities, transport and storage of Gd3+, and augmented biosynthesis of PQQ. Gadolinium-grown cells exhibited a shorter T1 relaxation time compared to cells with lanthanum or no lanthanide when analyzed by MRI. In addition, evo-HLn was able to grow on methanol using the GBCA Gd-DTPA as the sole gadolinium source, showing the potential of this strain for the development of novel GBCAs and gadolinium recovery from medical waste and/or wastewater.

Thermodynamic properties of alloys In—Tb system

The method of isoportic calorimetry investigated the thermochemical properties of the melt In—Tb system in the range of compositions 0 < xIn < 0,4 at 1625 ± 1 K. The obtained data were extrapolated on a non-investigated concentration interval, given that when xTb = 1 integral and partial to Tb enthalpia mixing is zero. It was established that the first partial for Terbium and the minimum enthalpy of mixing is –145 ± 7 and –40,1 ± 0,2 kJ/mol respectively. Comparison of ΔHmin, the melt of five previously investigated In—Ln systems from the serial number Ln (zLn), together with the data obtained in this papper, showed that they are described by one trend line. For ΔHmin In—Eu (Yb) melts (Yb) are very slight deviations from the trend line. But for dimensional factor, these deviations from the trend line are more significant. Enthalpia of the formation of some In—Ln intermetallides are known, with most of them relate to the LnIn3 compound. But there is no full reconciliation between these data. The results of the most modern work exhibit less dependence on the serial number of lanthanides and are more exothermic for heavy lanthanides, compared with other data. Comparing thermochemical properties of double Sn (Sb) —REM melt systems. It has been established that the energy of the interaction between the data p-elements and REM increases in such a sequence: In-REM → Sn—REM → Sb—REM. This is due to the fact that the stibium is the best acceptor of electrons. Keywords: thermochemical properties, melts, compounds, In, Tb.

Rare-earth elements in the ore of the Bukukinskoye tungsten deposit (the Eastern Transbaikalia)

Research subject. This study investigated the mineral association of quartz-wolframite veins of the Bukukinskoye tungsten deposit, with a particular focus on the content of rare-earth elements and their carrier minerals, their chemical composition and the distribution of light and heavy lanthanides. Materials and methods. The chemical composition of two groups of samples containing different ore minerals, as well as the mineral composition of ores was investigated on 143 samples in thin and polished sections using an AXIO ScopeAI optical polarizing microscope and a LEO 1430 VP scanning electron microscope. Chemical examination of ores was carried out using the ISP MS method. Results. The study of the chemical composition of group samples determined that the content and distribution of REE, the ratio of light and heavy lanthanides in ores depends on the ratio of wolframite and other ore minerals, associated with fluorite and apatite. The main REE concentrator mineral in the wolframite-sulfide-quartz ores of the Bukukinskoye deposit is monazite-(Ce) containing (wt %) Ce (27.09–31.59) La (13.13–17.67), Nd (5.59–10.26), Pr (up to 2.86), Sm (up to 1.14), Th (up to 6.59). Conclusion. The obtained results confirmed our earlier findings for the wolframite of the Sherlova Gora that an increase in the concentration coefficient of heavy lanthanides depends on a decrease in their ionic radius. The contents, mineral forms and ratios of REE of the cerium and yttrium groups in the ore of the Bukukinskоyе deposit can be typochemical signs of greisen tungsten deposits, thus being useful for typification of ore formation in geological forecasting and prospecting.

Ion-adsorption rare earth ores of China

Geology and geochemistry of China’s ion-adsorption rare earth ores are discussed. The structure and material constitution of Lognan, Huashan, Guposhan and Heling deposits are compared. The weathered layer structure, as well as the distribution, differentiation and occurrence forms of rare earth elements (REE) in the weathered layer are described. The prospecting indicators and criteria of readily dissociated adsorbed REE ore are identified to find this type ores in the territory of Russia. The weathered layer enclosing ion-adsorption rare earth ore features specific differentiation of REE. General composition of such ores is governed by the composition of the primary rare earth mineralization in mother granites. If granites contain much yttrium and heavy lanthanides, then ion-adsorption rare earth ore contain also much yttrium and heavy lanthanides. Regarding differentiation of REE, yttrium and heavy lanthanides mainly concentrate in the middle, most clayey part of the weathered layer, while cerium accumulates in subsurface lateritic soil. The prime feature of ion-adsorption rare earth ore is the prevalence of readily dissociated REE, which can reach a quantity of 80% and more but not less than a half. The rest REE concentrate in relict rock-forming minerals and accessories. The quantitative estimation of adsorption form of REE is necessary for the geological and economic appraisal of a deposit. It is assumed that the quantity of readily soluble REE should be not less than 0.05–50% of the total content. Russia has many regions with such geotectonic environment. It is required to explore ion-adsorption rare earth ore occurrences in these regions.

Magnetic and Electronic Properties of Heavy Lanthanides (Gd, Tb, Dy, Er, Ho, Tm)

Rare earth metals (REM) occupy a special and important place in our lives. This became especially noticeable during the rapid development of industry in the industrial era of the twentieth century. The tendency of development of the rare-earth metals market certainly remains in the XXI century. According to experts estimates the industry demand for chemical compounds based on them will tend to grow during the nearest years until it reaches the market balance. At the same time, the practical use of high-purity rare-earth metals requires the most accurate understanding of the physical properties of metals, especially magnetic ones. Despite a certain decline in interest in the study of high-purity REM single crystals during the last decade, a number of scientific groups (Ames Lab, Lomonosov Moscow State University (MSU), Baikov Institute of Metallurgy and Materials Science Russian Academy of Science (RAS)) are still conducting high-purity studies on high-purity metal samples. The present article is a combination of a review work covering the analysis of the main works devoted to the study of heavy REMs from gadolinium to thulium, as well as original results obtained at MSU. The paper considers the electronic properties of metals in terms of calculating the density of states, analyzes the regularities of the magnetic phase diagrams of metals, gives the original dependences of the Neel temperature and tricritical temperatures for Gd, Tb, Dy, Er, Ho, Tm, and also introduces a phenomenological parameter that would serve as an indicator of the phase transformation in heavy REMs.

INFLUENCE OF LIGHT AND HEAVY LANTHANIDES ON THE PHYSIOLOGICAL PROCESSES OF Taraxacum hybernum

The current study was carried out to study the influence of light and heavy lanthanides on the physiological process of Crimean-Sagyz/ Krim-saghyz (dandelion - Taraxacum hybernum). Lanthanide belongs to the group of light or heavy; infiltration of dandelion (Crimean saghyz) seeds with light and heavy lanthanides solutions increased the germination energy by 26%. The differences in the influence of light (cerium) and heavy (lutetium) were manifested in the quantum efficiency change of the photosystem 2 (PS II). Treatment of leaves with high concentrations (100 µM) led to a decrease of Y (II), moreover, under the influence of light lanthanide, the decrease was greater by 21%. It is assumed that the effect of the used lanthanides on the dandelion photosynthetic apparatus is multidirectional. Cerium influenced the PS II antenna complex, and lutetium influenced the reaction centers. A 10-fold decrease in the concentration did not change the nature of cerium action, except that Y (II) was restored already on the second day after treatment. The effect of lutetium became noticeable only by the 8th day after treatment when Y (II) became higher than that of untreated plants. Thus, the results of the study suggested that in dandelion leaves, lanthanides with a concentration of 10 µM increased the quantum efficiency of PS II in contrast to cerium.