Conducting electrically active films obtained by the electrochemical oxidation of aniline in molten electrolytes and concentrated hydrochloric acid

The feasibility of obtaining electrically conducting and active films by the electropolymerization of aniline in butylpyridinium tetrachloroaluminate or hexachlorodialuminate as the medium has been demonstrated. Identical voltamperometric characteristics with a potential peak of 0.5 V were found in these films and the compound formed upon the electrochemical polymerization of aniline in 20% hydrochloric acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 212–214, January, 1991.     

Generalized criterion of solvent polarity as a tool for control of chromatographic process

The generalized (reductive) criterion of solvent polarity was obtained by the method of multiparametric optimization of the Snyder index P", Hildebrand parameter _T , permittivity _r , and solvatochromism parameter E _T (30). Possibilities of employing this criterion for estimation of the elution power of normal and reversed mobile phases used in high-performance liquid chromatography were considered.     

Carbonized fibers based on polyvinyl alcohol

On the basis on polyvinyl alcohol (PVA), carbonized fibers were produced in the form of a complex technical thread with tensile strength above 200 MPa and specific electrical conductivity of at least 0.5 S/cm. Using thermogravimetric and differential thermal analysis, Raman scattering, and wide-angle X-ray diffraction, structures of these fibers were characterized. The structural parameters of carbonized PVA fibers are close to the parameters of carbonized coal tar pitch obtained by heat treatment at 1000°C. The structure and properties of carbonized fibers modified with potassium bisulfate were also studied.     

Dielectric spectroscopy of aminoalcohols and polyethylenepolyamines

Dependences of dielectric permittivity ?(f) and dielectric loss tangents tansδ(f) of aminoalcohols (AAs), polyethylenepolyamines (PEPAs), water, and aqueous solutions of AAs and PEPAs with water concentrations of 1 wt % are investigated in the frequency range of 0.025–1000 kHz. The dielectric relaxation of the liquids under study is investigated. An interrelation between the dielectric parameters and physicochemical properties of AAs and PEPAs is established. Empirical equations that describe this interrelation with a high degree of accuracy of approximation validity are derived. The effect of water on the dielectric characteristics of AAs and PEPAs is shown. It is suggested that we evaluate the energy of affinity of AAs and PEPAs for water using the coefficient of dielectric losses ?″.     

Change in the structure of oriented poly(vinyl alcohol) fibers impregnated with potassium bisulfate during heat treatment in air

The structural transformations of oriented PVA fibers impregnated with potassium bisulfate during their heat treatment in air to a temperature of 600°C were studied. The preliminary thermal stabilization of the impregnated fibers was conducted in air at 215°C for 1 h with maintenance of a high degree of orientation of the fibers. The melting peak of the preliminarily thermally stabilized impregnated PVA fibers is completely suppressed during their subsequent heat treatment in air, and the yields of coke residue are 48 and 43% of the thermally stabilized fiber mass at 500 and 600°C, respectively.     

Spectroscopic study of zeolite Na-ETS-10 and ethylene photopolymerization reaction on its surface

Zeolite Na-ETS-10 is studied by the Raman and IR spectroscopy methods. The ethylene polymerization reaction on this zeolite under UV irradiation is studied by IR spectroscopy. It is found that this reaction proceeds at room temperature yielding polyethylene. The experimental data are analyzed using 2D correlation spectroscopy.     

Water transbilayer diffusion in macroscopically oriented lipid bilayers as studied by pulsed field gradient NMR

Water self-diffusion in lipid bilayers macroscopically oriented on glass plates was studied by pulsed field gradient¹H nuclear magnetic resonance technique. Diffusion decays were multicomponent with a distribution of diffusion coefficients ranging from about 10⁻¹⁰ to about 10⁻¹³ m²/s. A number of measurements with variations of the sample orientation, diffusion time and the distance between the glass plates showed that the “fast” component of diffusion corresponds to water in the bilayer “cracks”. The “slow” component of diffusion corresponds to transbilayer water diffusion in the long-diffusion-time regime. For a more reliable separation of parts corresponding to fast and slow diffusion of water, a “component-resolved spectroscopy” method for the global analysis of correlated spectral data (P. Stilbs, K. Paulsen, P.C. Griffiths: J. Phys. Chem. 100, 8180, 1996) was applied.     

Lateral Diffusion of Lipids and Diffusion of Water through Lipid Bilayers in the Presence of (1,1-Dimethyl-3-Oxobutyl)Phosphonates

The influence of some amphiphilic (diethyl, dipropyl, and dibutyl) esters of (1,1-dimethyl-3-oxobutyl)phosphonic acid with the regularly changing number of CH₂ groups in the hydrocarbon (hydrophobic) moiety on the lateral diffusion of dioleoyl phosphatidylcholine lipid and transmembrane diffusion of water in the oriented multibilayer system was studied by ¹H pulsed field gradient NMR at phosphonate concentrations up to 30 mol %. The shape of the ³¹P NMR spectra and the dependence of the shape of the ¹H NMR spectra on the bilayer orientation suggest that the presence of phosphonates does not affect the phase state of the system. The lamellar liquid crystalline phase remains unchanged, and phosphonate molecules become incorporated into the bilayer and have the same orientation as phospholipid molecules. The presence of phosphonates in the lipid bilayer increases the coefficients of lipid lateral diffusion and water diffusion through bilayers. This effect depends monotonically on the number of CH₂ groups in the phosphonate molecule. The most probable place for the incorporation of amphiphilic phosphonate molecules is the hydrophilic/hydrophobic interphase region of the bilayer. The molecules incorporated into the interphase disorder the bilayer and increase lateral diffusion of lipids and bilayer permeability compared with the ester-free bilayer. When the number of CH₂ groups in the ester molecule increases from diethyl to dibutyl phosphonate, the arrangement of lipid hydrocarbon tails becomes more ordered. This decreases the lipid lateral diffusion coefficient and bilayer permeability to water molecules.     

Interaction of polyacrylic acid with lipid bilayers: effect of polymer mass

Polyanion‐coated lipid vesicles are proposed to have an appreciable potential for drug delivery because of their ability to control the permeability of lipid bilayers by environmental parameters such as pH and temperature. However, details of the interaction of this class of polymers with lipids and their mechanisms of induced permeability are still being debated. In this work, we applied ¹H NOESY to study details of the interaction of polyacrylic acid (PAA) fractions of molecular weights 5 and 240 kDa with dimyristoylphosphatidylcholine vesicles. We showed that PAA of two different molecular masses modifies lipid bilayers increasing disorder and probability of close contact between polar and hydrophobic groups. PAA molecules adsorb near the interface of lipid bilayers but do not penetrate into the hydrophobic core of the bilayer and, thus, cannot participate in formation of transbilayer channels, proposed in earlier works. Increasing the molecular mass of PAA from 5 kDa to 240 kDa does not change the effect of PAA on the bilayer, although PAA240 forms a more compact structure (either intra‐molecular or inter‐molecular) and interacts more strongly with interface lipid protons. Copyright © 2013 John Wiley & Sons, Ltd.