The thermodynamic properties and electronic structure of hydrated Ra 2+ have been investigated using ab initio quantum chemical calculations that apply the relativistic model core potential method and compared with those of the other hydrated divalent alkaline earth metal ions (Mg 2+ , Ca 2+ , Sr 2+ , and Ba 2+ ). The solvation free energies calculated for [Ra (H 2 O) n ] 2+ (n = 1-9) in a continuum dielectric media (semi-continuum model) showed that the hydration number of Ra 2+ is in the range of 7-9. Natural population analysis (NPA), natural bond orbital (NBO) analysis and localized molecular orbital energy decomposition analysis (LMO-EDA) showed that the dominant interaction between hydrated Ra 2+ ions and solvent water molecules is electrostatic interaction to form coordination bonds which have a strong ionic bond character. On the other hand, not only electrostatic interaction but also covalent interaction accompanying chargetransfer from solvent water molecules to the central ion are important in the interaction between hydrated Mg 2+ or Ca 2+ (lighter divalent alkaline earth metal ions) and solvent water molecules. Keywords Radium divalent ion, Hydration, Chemical bond character, Relativistic model core potential, MCP the most basic steps. Although Glendening, Feller [2] and Han[3] have studied the structure of aqua clusters of divalent alkaline earth metal ions including Ra 2+ , their studies were those
Using fragment molecular orbital-molecular dynamics (FMO-MD) simulation at the FMO3-HF/6-31G(d,p) level, the hydration of a Ra 2? ion was theoretically investigated. The first peaks of the radial distribution function (RDF) for Ra-O and Ra-H lengths were predicted to be 2.85 and 3.45 Å with broad envelopes in the ranges of 2.5-3.5 and 2.8-4.3 Å , respectively. The broad peaks shows that the first hydration shell of Ra 2? is much more flexible than those in the other hydrated divalent alkaline earth metal ions, i.e., Ra 2? is a structure-breaking ion. The hydration number of Ra 2? was predicted to be 8.1. From the angular distribution function (ADF), it was clarified that the octa hydrated Ra 2? ion has a flexible square antiprism structure at room temperature.
Pd nano-octahedron absorbs hydrogen gas faster than Pd nano-cube. This means that H-absorption rate of Pd nanoparticles can be controlled by their structural design. For further design of nano materials for H-absorption, it is important to understand tuning mechanism of H-absorption achieved in shape-controlled Pd nano particles. In this study, kinetics of H-absorption into Pd nano-octahedron and Pd nano-cube were investigated by electronic structure calculation and molecular dynamics simulation. Both simulations well support experimental observation. It was clarified that the shape dependency in H-absorption of the Pd nanoparticles originates from difference in H-invasion process from surface to the inside.
Cytochrome c 6 from the red alga Porphyra yezoensis has been puri®ed and crystallized by the sitting-drop vapour-diffusion method. Two different crystal forms, tetragonal and orthorhombic, were obtained. The tetragonal crystals belong to space group P4 1 2 1 2 or P4 3 2 1 2, with unit-cell dimensions a = 49.33 (2), c = 83.70 (10) A Ê . The orthorhombic crystals belong to space group P2 1 2 1 2 1 , with unit-cell dimensions a = 46.74 (2), b = 49.42 (1), c = 37.11 (1) A Ê . Absorption spectra of the crystals showed that the tetragonal form was oxidized and the orthorhombic form was reduced.
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