Diffusion Boundary Layers in Transport of Aliphatic Acids in Electromembrane Systems

The regularities of the formation of diffusion boundary layers during the transport of aliphatic acids in electromembrane systems are studied and their characteristics obtained experimentally are analyzed. It is shown that their concentration profiles in solutions of the electrodialyzer sections are asymmetric near membranes of different polarity. Experimental values of diffusion layer thicknesses are compared with those following from the known theoretical relations. The equation, which is proposed for the surface concentration, permits the prediction of the operation mode of apparatus during electrodialysis of solutions of aliphatic acids and other weak electrolytes. Specific features characterizing the emergence of a limiting state and the character of the distribution of limiting current densities over the height of the membrane channel are revealed.     

Identification of raw materials for the production of vodkas based on the results of gas-liquid chromatographic analysis with the use of fuzzy logic

The concepts of fuzzy logic were applied to the analysis of gas-chromatographic data for 12 samples of Russian vodka products. It was found that, with the use of the truth degrees of fuzzy logic propositions on the composition of analytical samples based on a simulation of expert’s reasoning, the grade of raw materials used for the production of the analytical samples can be supposed and the conformity with standards can be established.     

Stability of Polymeric-Salt Gels Used To Synthesize Complex-Oxide Materials

The conditions for stability of polymeric-salt systems based on polyvinyl alcohol, used to synthesize complex-oxide materials containing rare-earth, alkaline-earth, and d metals, were studied.     

Micellar Thin-Layer Chromatography and Preconcentration of L-Carnitine with Magnetite Nanoparticles

Journal of Analytical Chemistry - Thin-layer chromatography (TLC) is used to study the chromatographic behavior of L-carnitine in aqueous–organic mobile phases (MPs) and aqueous MPs in the...     

A comprehensive investigation of phase transformations in the Pb0.9975[Zr0.495Sn0.4Ti0.1Nb0.005]O3 ceramics

The effect of temperature and electric field on the character of dipole ordering in ceramics of the composition Pb_0.9975[Zr_0.495Sn_0.4Ti_0.1Nb_0.005]O₃ has been investigated. The phase transitions have been revealed from anomalies in the temperature dependences of the pyroelectric current measured in the dynamic mode, as well as from the dilatometric and dielectric parameters. The E-T phase diagram has been constructed using the results obtained from the field experiments.     

Dynamic Analysis of a Two-Mass System with Essentially Nonlinear Vibration Damping

A nonlinear system with two degrees of freedom is considered. The system consists of an oscillator with relatively large mass, which approximates some continuous elastic system, and an oscillator with relatively small mass, which damps the vibrations of the elastic system. A modal analysis reveals a local stable mode that exists within a rather wide range of system parameters and favors vibration damping. In this mode, the vibration amplitudes of the elastic system and the damper are small and high, respectively__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 1, pp. 102–111, January 2005.     

Synthesis,extraction, and transport properties of dibenzo-18-crown-6 modified with the fragments of 2-amino-1,3,4-thiadiazol and kojic acid

New heterocyclic derivatives of dibenzo-18-crown-6 (DB18C6), the products of coupling of kojic acid (5-hydroxy-2-hydroxymethyl-γ-pyrone) with 4′-DB18C6-yldiazonium chloride, 4′,4″-and 4′,5″-DB18C6-diyldiazonium dichlorides and products of heterocyclization of DB18C6 mono-and dicarboxylic acids with thiosemicarbazide are prepared. Their structures are studied by the methods of ¹H NMR and IR spectroscopy. Polyphosphoric acid is found to be the best agent for the heterocyclization of thiosemicarbazide with DB18C6 carboxylic derivatives. It is proven that the parent substrates, the DB18C6 mono or dicarboxylic acids, serve as phase transfer catalysts for the heterocyclization reaction. Extraction and transport properties of the obtained compounds in respect of potassium, sodium and ammonium picrates are explored.