Small-angle light scattering from polymer-dispersed liquid-crystal films

A method is developed for modeling and computing the angular distribution of light scattered forward from a single-layer polymer-dispersed liquid-crystal (PDLC) film. The method is based on effective-medium approximation, anomalous diffraction approximation, and far-field single-scattering approximation. The angular distribution of forward-scattered light is analyzed for PDLC films with droplet size larger than the optical wavelength. The method can be used to study field-and temperature-induced phase transitions in LC droplets with cylindrical symmetry by measuring polarized scattered light intensity.     

Transformation of cholesteric orientational structures and optical textures induced by the electric field–driven ionic modification of surface anchoring

The reorientation of a cholesteric liquid crystal with a large helical pitch induced by the electric field–driven modification of surface anchoring is investigated. In the initial state, the liquid crystal cell has a homeotropic alignment of the director. An applied dc electric field produced a twisted homeoplanar structure of the cholesteric.     

Some nonlinear problems of groundwater flow through a porous medium

Self-similar solutions of the equation of groundwater gravity flow through a porous medium are given. The water flows from a basin into an underground permeable reservoir bounded from below by an impervious bed. A periodic problem of flow through a porous medium in which the water level in the basin periodically oscillates is considered. It is shown that in this case the water table elevation effect, i.e., water pumping into the aquifer, develops at a sufficient distance from the littoral zone. The invariant-group solutions of the problem of flow through a porous medium are investigated with allowance for evaporation from the groundwater surface.     

Nucleophilic substitution of hydrogen–the Boger reaction sequence as an approach towards 8-(pyridin-2-yl)coumarins

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Effective Synthetic Approach to 4-Arylpyridine-2,6-dicarboxylic Acids

Russian Journal of Organic Chemistry - A convenient synthetic route to 4-arylpyridine-2,6-dicarboxylic acid has been proposed on the basis of substituted benzaldehydes according to the Kröhnke...     

Detection of small signals in mass spectra

The results of the chromatographic–mass spectrometric analysis of a mixture containing a compound with low protonation efficiency have been given. A software package for preliminary processing of mass spectra is used for determining the peak parameters of the compound ions. The reliability of the processing results has been confirmed by comparison with the tabular data for the isotope masses and the isotopic composition of the component. The mass spectrum has been interpreted by calculating the peak areas and centroids together by evaluating the standard deviation of the center of the peak. The results of processing the mass spectrum using the mMass program have been given.

     

An Efficient One‐Pot,Multicomponent, and Green Solvent Protocol for the Synthesis of Dihydropyridine Derivatives

Highly prominent dihydropyridine analogs have been developed and screened for their yields by using different catalysts under eco‐friendly ethanol solvent condition. Triethylamine catalyst was identified as ro bust catalyst for this synthetic path. The key benefits of this procedure are environmentally benign procedure, mild reaction conditions, simplicity of operation, high yields, mild reaction period, and decent substrate generality.     

Microwave assisted synthesis and Anti-microbial activity of new Diethyl ((dialkoxyphosphoryl) (2-hydroxyphenyl) methyl) phosphoramidates

The synthesis of new α-aminophosphonates 4a-j (diethyl((dialkoxyphosphoryl)(phenyl)methyl)phosphoramidates) were achieved through a one pot simple and efficient method from the three-component condensation reaction (Kabachnik-Fields reaction) of diethyl phosphoramidate, aryl salicylaldehydes, and dialkyl phosphite by using microwave irradiation under solvent-free and catalyst-free conditions in good to excellent yields and short reaction times. The structures of the novel products were established by IR, ¹H, ¹³C & ³¹P-NMR and Mass spectroscopy. All the synthesized compounds were screened their antimicrobial activity.     

An expedient solvent-free C-benzylation of 4-hydroxycoumarin with styrenes

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Liquid crystal materials with ionic-surfactant operation

A conceptually new approach for developing methods of control of liquid crystals is discussed. The approach is based on modifying surface anchoring. A brief review of the authors’ research on developing ionic-surfactant control of liquid crystalline materials is described. This approach is based on the effect of electrically induced modification of the boundary conditions by ions of surface-active compounds.