Rare earth elements particle reactivity

Although the oceanic distributions of rare earth elements somewhat resemble those of nutrients, their behaviors are clearly different in that they are not actively taken up by photoplankton but passively scavenged by particles. Elemental reactivity with suspended particles, which controls, together with sinking of particle aggregates, the mean oceanic residence times of not only REEs but also a number... 

The purpose of the present paper is to investigate the behavior of high temperature stable support in complete oxidation of methane, when sulfur species are present in the feed. Various characterization methods have been employed here in order to give a general picture of the deactivation of supported Pd catalysts in catalytic combustion of methane. This work will examine the reactivity of supported Pd catalysts, when the metal particles are dispersed over a thermally stable material, containing rare earth elements. Moreover, we will focus on the behavior of the catalysts when sulfur species are added to the feed, as sulfur can be present in significant amounts in natural gas. 

Berkelium is a metallic element located in group 11 (IB) of the transuranic subseries of the actinide series. Berkelium is located just below the rare-earth metal terbium in the lanthanide series of the periodic table. Therefore, it has many chemical and physical properties similar to terbium ( Tb). Its isotopes are very reactive and are not found in nature. Only small amounts have been artificially produced in particle accelerators and by alpha and beta decay. 

The high affinity of Ti and Zr for nitrogen and their tendency to form coarse nitride particles preclude the use of these elements in hot-rolled steels strengthened by finely dispersed nitride precipitates (Lichy et al. 1965, Bucher et al. 1969). Ti and Zr will combine with carbon in the solid state to form lath-shaped crystals of their carbides, which can cause embrittlement (Arrowsmith 1968). Ti and Zr are available at moderate cost, but their reactivity with 0, S, C, and N makes accurate control of the final properties of steels with these elements somewhat difficult. It is also interesting to note that steels treated with rare earths show consistently higher ductility than Zr-treated steels (Wilson and Klems 1974). 

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