Mössbauer and X-ray diffraction study of structural phase transitions in LaMnO<Subscript>3 + δ</Subscript>

The influence of the conditions of thermal treatment on the formation and mutual transitions of structural modifications of the LaMnO_{3 + δ} compound doped with ⁵⁷Fe (4%) have been investigated by Mössbauer spectroscopy and X-ray diffraction analysis. It is found that heat treatment in vacuum and in air ensures reversible structural transformations of two orthorhombic and one rhombohedral phases (space groups Pnma and \(R\bar 3c\), respectively). Changes in the configuration of the oxygen environment of cations at reversible phase transitions are considered.     

Energy dependence of directed flow over a wide range of pseudorapidity in Au + Au collisions at the BNL Relativistic Heavy Ion Collider

We report on measurements of directed flow as a function of pseudorapidity in Au + Au collisions at energies of square root of SNN = 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the BNL Relativistic Heavy Ion Collider. These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.     

Determination of heavy metals and their speciation in waters and bottom sediments of water reservoirs using inductively coupled plasma atomic emission spectrometry and electrothermal atomic absorption spectrometry

The use of inductively coupled plasma atomic emission spectrometry in combination with electrothermal atomic absorption spectrometry and autoclave sample preparation essentially improved performance characteristics of the determination of heavy metals and simplified analytical procedures for determining their speciation. Inductively coupled plasma atomic emission spectrometry can give information about the concentrations of a wide range of elements in water and bottom deposits at a level of MPC and, thus, is useful for revealing sources of pollution of water reservoirs. More sensitive electrothermal atomic absorption spectrometry was used for determining background concentrations of Pb, Cd, Co, Ni, Cu, Cr, Mo, and As and assessing the speciation of Pb, Cd, Co, Cu, and Zn in waters and bottom sediments. Based on the results of analyses of surface, bottom, and void waters; bottom sediments and their step-by-step extracts; and KMC and DEAE cellulose adsorbents containing charge-separated heavy metals, the ecological status of Kuibyshev, Ivan’kovo, and Rybinsk water reservoirs was assessed.     

Iodine-Chemisorption,Interpenetration and Polycatenation: Cationic MOFs and CPs from Group 13 Metal Halides and Di-Pyridyl-Linkers

Eight cationic, two-dimensional metal-organic frameworks (MOFs) were synthesized in reactions of the group 13 metal halides AlBr₃, AlI₃, GaBr₃, InBr₃ and InI₃ with the dipyridyl ligands 1,2-di(4-pyridyl)ethylene (bpe), 1,2-di(4-pyridyl)ethane (bpa) and 4,4’-bipyridine (bipy). Seven of them follow the general formula ²_∞[MX₂(L)₂]A, M=Al, In, X=Br, I, A⁻=[MX₄]⁻, I⁻, I₃⁻, L=bipy, bpa, bpe. Thereby, the porosity of the cationic frameworks can be utilized to take up the heavy molecule iodine in gas-phase chemisorption vital for the capture of iodine radioisotopes. This is achieved by switching between I⁻ and the polyiodide I₃⁻ in the cavities at room temperature, including single-crystal-to-single-crystal transformation. The MOFs are 2D networks that exhibit (4,4)-topology in general or (6,3)-topology for ²_∞[(GaBr₂)₂(bpa)₅][GaBr₄]₂⋅bpa. The two-dimensional networks can either be arranged to an inclined interpenetration of the cationic two-dimensional networks, or to stacked networks without interpenetration. Interpenetration is accompanied by polycatenation. Due to the cationic character, the MOFs require the counter ions [MX₄]⁻, I⁻ or I₃⁻ counter ions in their pores. Whereas the [MX₄]⁻, ions are immobile, iodide allows for chemisorption. Furthermore, eight additional coordination polymers and complexes were identified and isolated that elaborate the reaction space of the herein reported syntheses.