Nonlinear surface waves in arrays of curved waveguides

We study both theoretically and experimentally the nonlinear surface waves at the edge of curved waveguide arrays with a surface defect. We show that the nonlinear coupling between different linear modes supported by the array can lead to beam switching to different output waveguides with increasing of the nonlinearity strength. Our experimental observations are in good agreement with the numerical modelling.     

Novel structural type of bridged urea derivatives bearing azatricyclo[4.3.1.03,8]decane moiety

Structural Chemistry - In an attempt to synthesize 4-thia-6-azatricyclo[5.3.1.13,9]dodecan-5-imine as putative antihypotensive agent with prolonged effect, a reaction of...     

Organic crystallography: three decades after Kitaigorodskii

Structural Chemistry - Main postulates of Aleksandr Kitaigorodskii’s theory of organic crystal structures are revisited. The additive model of van der Waals atom-atom potentials giving rise...     

Progress in intermolecular and intramolecular reactions of thioamides with diazo compounds and azides

Reactions of thioamides with nitrogen-rich 1,3-dipoles, diazo compounds and azides, have been known for long time already. However in recent years introduction of catalysts of different types (rhodium-, ruthenium- and copper-containing and Lewis acids) as well as highly electrophilic sulfonyl azides, allowed the development of new methods for the synthesis of heterocycles, enamines and N-sulfonyl amidines. Moreover, a new methodology in organic synthesis, based on generation and subsequent transformations of α-diazocarbonyl compounds was created. Reactions of sulfonyl azides with thioamides undergo readily in mild conditions to produce different sorts of N-sulfonyl amidines and represent a new type of click-type processes. Most of the cited works were published in the current decade. Earlier seminal papers are also reviewed when they constitute the background for new synthetic methods which were developed further.     

β-(Cycloalkylamino)ethanesulfonyl azides as novel water-soluble reagents for the synthesis of diazo compounds and heterocycles

Chemistry of Heterocyclic Compounds - Novel water-soluble sulfonyl azides were synthesized, which are basic by nature. The obtained compounds were used as donors of the diazo group in the diazo...     

The first example of the stereoselective synthesis and crystal structure of a spirobicycloquinazolinone based on (–)‐fenchone and anthranilamide

The possibility of a single‐stage solvent‐free stereoselective synthesis of a spirocyclic compound from the natural bicyclic monoterpenoid (?)‐fenchone and anthranilamide has been shown for the first time. The molecular and crystal structure of (1R,2S,4S)‐1,3,3‐trimethyl‐1′H‐spiro[bicyclo[2.2.1]heptane‐2,2′‐quinazolin]‐4′(3′H)‐one, C₁₇H₂₂N₂O, was established by X‐ray diffraction though the chirality was assumed via the known reactant connectivity and ¹H and ¹³C NMR spectroscopy. It has shown that in the molecule, for steric reasons, there is an elongation of the Me₂C—C(N)N bond to 1.603 (5) Å. The formation of dimers via N—H…O=C hydrogen bonds with an interaction energy of 93.30 kJ mol^?1 and through cavities (33.7% of the unit‐cell volume) was established in the packing of the molecules. There are no π‐stacking interactions in the structure.     

A Curie–Weiss theory of the continuum Widom–Rowlinson model

A version of the continuum Widom–Rowlinson model is introduced and studied. It is a two-component gas of point particles placed in ${\mathbf{R}}^d$ in which like particles do not interact and unlike particles contained in a given vessel of volume V repel each other with intensity $a/V$. This model is thermodynamically equivalent to a one-component gas with multi-particle interaction. For both models, a rigorous theory of a phase transition is presented and the ways of its construction in the framework of the grand canonical formalism are outlined.     

Application of the ultrasonic velocity profile method to the mapping of liquid metal flows under the influence of a non-uniform magnetic field

An ultrasonic velocity profile (UVP) method has been successfully applied to the investigation of a liquid metal channel flow under the influence of an inhomogeneous magnetic field. Using velocity profiles obtained by the ultrasonic velocimeter and their numerical post processing, two-dimensional time-averaged flow maps were efficiently produced. A single transducer immersed directly into the working fluid was used in order to simplify alignment of measurement lines and avoid the undesirable refraction of the acoustic beam on the walls. An M-shaped flow and wake behind a magnetic obstacle were reconstructed as the patterns of shear and large-scale vortical flows.     

Light scattering by a finite obstacle and fano resonances

The conditions for observing Fano resonances at elastic light scattering by a single finite-size obstacle are discussed. General arguments are illustrated by consideration of the scattering by a small (relative to the incident light wavelength) spherical obstacle based upon the exact Mie solution of the diffraction problem. The most attention is paid to recently discovered anomalous scattering. An exactly solvable one-dimentional discrete model with nonlocal coupling for simulating diffraction in wave scattering in systems with reduced spatial dimensionality is also introduced and analyzed. Deep connections between the resonances in the continuous and discrete systems are revealed.