In memoriam: Boris Dubrovin

Letters in Mathematical Physics -     

Effective bimetallic composite catalysts for the synthesis of arylated furans and thiophenes in aqueous media

Chemistry of Heterocyclic Compounds - N-(4,6-Dimethylpyrimidin-2-yl)-5-phenylisoxazole-3-carboxamide was used as a ligand for obtaining bimetallic boron-containing heterogeneous catalysts...     

Silacyclophanones 3*. Cyclic organosilicon esters of ortho-phthalic acids

Chemistry of Heterocyclic Compounds - Reactions of dichlorodimethylsilane with 2,3,4,5-tetrafluorophthalic acid bis(trimethylsilyl) ether (1:1, 20°C, 24 h) without a solvent and...     

Boron-Containing Lipids and Liposomes: New Conjugates of Cholesterol with Polyhedral Boron Hydrides

A series of boron-containing lipids were prepared by reactions of cyclic oxonium derivatives of polyhedron boranes and metallacarboranes (closo-dodecaborate anion, cobalt and iron bis(dicarbollides)) with amine and carboxylic acids which are derived from cholesterol. Stable liposomal formulations, on the basis of synthesized boron-containing lipids, hydrogenated soybean l -α-phosphatidylcholine and (HSPC) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG) as excipients, were prepared and then characterized by dynamic light scattering (DLS) that revealed the formation of particles to be smaller than 200 nm in diameter. The resulting liposomal formulations showed moderate to excellent loading and entrapment efficiency, thus justifying the design of the compounds to fit in the lipid bilayer and ensuring ease of in vivo use for future application. The liposomal formulations based on cobalt and iron bis(dicarbollide)-based lipids were found to be nontoxic against both human breast normal epithelial cells MCF-10A and human breast cancer cells MCF-7.     

Study of all stages of the Diels–Alder reaction of cyclopentadiene with 2,3-dicyano-1,4-benzoquinone and monoadducts: Kinetics,thermochemistry, and high pressure effect

The kinetic parameters and enthalpies of the Diels–Alder reactions between cyclopentadiene and 2,3-dicyano-1,4-benzoquinone leading to the formation of two different monoadducts and bisadduct were determined. The stability of adducts is compared. Monoadduct appears to be thermodynamically more stable than the bisadduct. Comparison with the other Diels–Alder reactions studied previously allows us to conclude that the heat effects upon formation of the considered Diels–Alder adducts are the lowest in comparison with all the studied dienophiles.     

Tomographic probability representation for quantum fermion fields

Tomographic probability representation is introduced for fermion fields. The states of the fermions are mapped onto the probability distribution of discrete random variables (spin projections). The operators acting on the fermion states are described by fermionic tomographic symbols. The product of the operators acting on the fermion states is mapped onto the star-product of the fermionic symbols. The kernel of the star-product is obtained. The antisymmetry of the fermion states is formulated as a specific symmetry property of the tomographic joint probability distribution associated with the states.     

Formation of helical beams by use of Pancharatnam-Berry phase optical elements

Spiral phase elements with topological charges based on space-variant Pancharatnam-Berry phase optical elements are presented. Such elements can be achieved by use of continuous computer-generated space-variant subwavelength dielectric gratings. We present a theoretical analysis and experimentally demonstrate spiral geometrical phases for infrared radiation at a wavelength of 10.6microm .