Trigger System of the HyperNIS Experiment

Physics of Particles and Nuclei Letters - The trigger system of the HyperNIS spectrometer, which was proposed for distinguishing events with the formation and subsequent decay of relativistic...     

Thermal stationarity criteria for a proper study on growth (dissolution) kinetics in systems with small volumes of solutions in melts

It is shown that an application of theories developed on the assumption of the stationary thermal conditions for discussing the results on kinetic experiments with small volumes of solutions in melts is incorrect if the strong measures on eliminating temperature oscillations in these experiments are not taken. The results on an analysis of the influence of various temperature changes on the velocity of migration of liquid interlayers through a crystalline wafer are presented and discussed. Criteria for thermally stationary conditions in kinetic experiments are deduced.     

Preparation of highly concentrated carboxyl-containing butyl acrylate based polymer dispersions by emulsion polymerization

A study of the influence exerted by the structure of oxyethylated and sulfooxyethylated alkylphenols on the features of emulsion polymerization of butyl acrylate with methacrylic acid showed that the use of mixtures of an ionic emulsifier with nonionic emulsifiers allows preparation of stable low-viscosity dispersions of butyl acrylate-methacrylic acid copolymers with no less than 65 wt % content of the main substance.     

Simulation of mass transfer in a kinetic experiment based on migration of flat layers of a solution in a melt in a temperature gradient field

Mass transfer upon migration of flat liquid layers of a solution in a melt under conditions of slow change in the average temperature at a constant rate has been analyzed for the dislocation and nucleation mechanisms of interface processes. It is shown that the experimental data on the dependence of the migration rate of flat layers on their thickness can be adequately described within the theory developed for strictly steady thermal conditions. A technique is proposed for determining the overall limitations on the mass transfer at interfaces and the migration rate in the diffusion mode from the experimental results obtained in a mixed migration mode.

     

Microsequential injection analysis: Determination of rutin and quercetin in food supplements and pharmaceutical products

Conditions for the oxidative coupling of rutin and quercetin with 3-methylbenztiazolinon-2-hydrazone have been determined under the conditions of microsequential flow analysis (‘lab-on-a-valve’). To provide the high sensitivity of the determination, methods aimed at improving the overlapping of the zones in the flow have been utilized; these are stopped flow and injection of a ‘spacer’ zone. Good results have been obtained using a new approach, the injection of a ‘spacer’ zone with a rate gradient. A program of operations for the automatic spectrophotometric determination of rutin and quercetin has been composed. The analytical range is (6–50) × 10⁻⁵ M for the determination of rutin and (5–50) × 10⁻⁵ M for the determination of quercetin, the productivity of analysis being 59 samples per hour. The procedure has been applied to the analysis of plant extracts and pharmaceutical product Askorutin.     

Stress-strain state of ice cover during aircraft takeoff and landing

We consider the linear unsteady motion of an IL-76TD aircraft on ice. Water is treated as an ideal incompressible liquid, and the liquid motion is considered potential. Ice cover is modeled by an initially unstressed uniform isotropic elastic plate, and the load exerted by the aircraft on the ice cover with consideration of the wing lift is modeled by regions of distributed pressure of variable intensity, arranged under the aircraft landing gear. The effect of the thickness and elastic modulus of the ice plate, takeoff and landing regimes on stress-strain state of the ice cover used as a runway.     

Synthesis and Properties of New 2,6-Poly(phenylquinoline)s and Their Composites with 2,1,3-Benzothiadiazole

We synthesized 2,6-poly(phenylquinoline)s, the elementary polymer unit of which contained alkyl carbazole or alkyl indolo[3,2-b]carbazole moieties with C₁₂ and C₁₈ alkyl side chains at nitrogen atoms and the oxygen or phenylamine bridge group between the quinoline cycles. The synthesized polymers form heat-resistant coatings, for which the temperature for 5% weight loss is higher than 450°С. It is demonstrated that introduction of 10 wt % of 2,1,3-benzothiadiazole to the poly(phenylquinoline)s leads to an increase in the photosensitivity of the composite as compared with the original polymers. Structural-morphological studies of the synthesized poly(phenylquinoline)s and their composites were carried out.     

Spectroscopic study of polyphenylquinolines—materials with efficient intramolecular charge transfer

The energy structure and nature of intramolecular charge transfer have been determined for a series of synthesized 2,6-polyphenylquinolines (PPQs) containing resorcinol, oxygen, and phenylamine bridging groups between phenylquinoline cycles and possessing an arylene radical in the form of alkylated derivatives of carbazole or indolo[3,2-b]carbazole, as well as arylated derivatives of carbazole with nitro- and fluorine substituents. The analysis was based on data on their absorption spectra, photosensitivity, carrier photogeneration quantum efficiency, and luminescence. It is shown that the PPQ monomeric unit is a composite intramolecular charge-transfer complex (ICTC) between the donor arylene fragment and the acceptor quinoline cycle; the latter, in turn, is an ICTC between the donor bridging group and quinoline ring (when acceptor fluorine or nitro substituents are introduced into the carbazole structure, the complex becomes ternary), and the narrowest band gap (2.3 eV) corresponds to the PPQ having a phenylamine bridging group and a fragment of indolo[3,2-b]carbazole.