Resonant light scattering by a gradient quantum well

Resonant scattering of monochromatic light by a quantum well with the frequency of its excitonic resonance varying along a certain direction in the plane of the well is studied experimentally and theoretically. It is shown that the simplest model of a thin inhomogeneous layer that yields an exact solution of the direct and inverse scattering problems allows one to successfully describe the experimental observation of resonant scattering by a GaAs/AlGaAs quantum well with the frequency of the exciton resonance linearly varying in the plane of the well.     

Influence of water and aqueous carboxylic acids on properties of epoxide polymer materials

The possibility of biodegradation in model media is investigated. The relative changes in weight Δm/m ₀, electric permeability Δɛ/ɛ₀, tangent of dielectric losses angle Δtanδ/tanδ₀, and numeric values of physicomechanical H _R, σ_tensile, and ɛ_p, adhesive τ_shear and structural n _L parameters for epoxide polymers solidified by amine, anhydride, or catalytic agents upon exposure for a long period (up to 60 days) in water and aqueous carboxylic acids were determined. The changes in the specified parameters were found to depend on the nature of the solidifying agent. The validation of the model was performed by comparing data obtained under model conditions with those obtained during in-field tests using air and methane tanks.     

Comparative analysis of methods for investigating polymer biocorrosion processes

A comparative analysis of indirect methods for investigating polymer biocorrosion (in aerotanks, methane tanks, and different aggressive media) is performed. The instrumental evaluation (on a spectrophotometer) of surface biodeteriorations and relative changes in the values of epoxy polymer properties (weight Δm/m ₀ and dielectric conductivity Δ?/?₀) during their exposure in the aerotanks and methane tanks was performed.     

Specific Features of Phase Synchronization for the Second Optical Harmonic Generated on a χ(2) Grating

Russian Physics Journal -     

Additional beams in optically uniaxial crystals

Reasons for occurrence of additional beams are established for rays reflected from a tilted prism face and transmitted through the interface between two crystal media. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 50–53, July, 2007.     

An investigation of the effect of adamantanecarboxylic acids on the structure of epoxy polymers by means of X-ray structural and thermomechanical analyses

The effects of structural modification of epoxy polymers (EPs) with mono- and dicarboxylic adamantane acids are studied. Within a cluster model of the structure of amorphous polymers, the components of the X-ray amorphous halo of the objects under study are identified based on the assumption of the existence of an open-packed matrix and regions of local order. It is established that the introduction of bulk adamantane fragments increases the nonuniformity of the EP structure, which causes a change in molecular and topological characteristics.     

The role of human in the loop: lessons from D3R challenge 4

The rapid development of new machine learning techniques led to significant progress in the area of computer-aided drug design. However, despite the enormous predictive power of new methods, they lack explainability and are often used as black boxes. The most important decisions in drug discovery are still made by human experts who rely on intuitions and simplified representation of the field. We used D3R Grand Challenge 4 to model contributions of human experts during the prediction of the structure of protein–ligand complexes, and prediction of binding affinities for series of ligands in the context of absence or abundance of experimental data. We demonstrated that human decisions have a series of biases: a tendency to focus on easily identifiable protein–ligand interactions such as hydrogen bonds, and neglect for a more distributed and complex electrostatic interactions and solvation effects. While these biases still allow human experts to compete with blind algorithms in some areas, the underutilization of the information leads to significantly worse performance in data-rich tasks such as binding affinity prediction.     

The Linear Kerr Effect

Russian Physics Journal -     

Electrooptical modulation of broadband light with Gaussian amplitude distribution over the spectrum

Physical principles of the operation of an optical modulator that employs, as a light source, a laser or light-emitting diode with a spectral width up to several tens of nanometers are considered. The half-wave voltage and modulation depth of the light are found with allowance for the spectral distribution of the amplitude and refractive index dispersion.     

Mathematical models of behavior of polymer material with shape memory

The algorithm of the behavior of the deformation models of network epoxypolymer heat-shrink sleeves with shape memory in vitreous and highly elastic states upon the formation of spigot adhesive joints was considered.