Possibility of chiral recognition by adsorption on enantiomorphous crystals: the impact of crystal surface polarity.

Chiral crystals remain one of the probable sources of first minute chiral symmetry breaking, a trigger that potentially causes an as-yet unknown type of asymmetric autocatalysis during the formation of chiral biopolymers under the conditions of the Archean Earth. Therefore, studying adsorption processes on the surface of such crystals may help improve the understanding of the nature of the initial chiral shift. The adsorptive activity of non-porous crystals with respect to the majority of organic molecules essentially depends on the ability of a crystal surface to engage in specific intermolecular interactions.

Mechanism of chiral recognition by enantiomorphous cytosine crystals during enantiomer adsorption.

The quest to understand why life exhibits chirality has been far from successful. In the terrestrial theory of chirality emergence in living matter, one of the main possible mechanisms is the chiral recognition of organic molecules by enantiomorphic crystals. In this work, we studied the ability of enantiomorphic cytosine crystals, obtained by Viedma ripening, for chiral recognition by enantiomers adsorption.

[Mitochondrial cytochrome b gene variation in brown bear (Ursus arctos Linnaeus, 1758) from southern part of Russian Far East].

The genetic variability of brown bear Ursus arctos from the southern part of the Russian Far East was first ex- amined based on the variations in the mitochondrial DNA cytochrome b sequence. The presence of two phylogenetic groups of haplotypes described previously for other parts of the species range was demonstrated. Part of the samples belonged to the haplotype group distributed across the whole range, while another part belonged to the rare group previously only reported for Japan and Alaska.

Thermodynamics of organic molecule adsorption on sorbents modified with 5-hydroxy-6-methyluracil by inverse gas chromatography.

The thermodynamic features of organic molecule adsorption from the gaseous phase of sorbents modified with 5-hydroxy-6-methyluracil (HMU) were studied. Molar internal energy and entropy of adsorption variation analyses showed that with every type surface, except for silica gel, layers of supramolecular structure have cavities equal in size with the ones revealed in HMU crystals by X-ray diffraction. Adsorption thermodynamics on HMU-modified sorbents depended on the amount of impregnated HMU and on the polarity, but not the porosity, of the initial sorbent.