Effect of hemoglobin on the NO-donor ability of μ<Superscript>2</Superscript>-<Emphasis Type="Italic">S</Emphasis>-bis(pyrimidine-2-thiolato)tetranitrosyldiiron

The hydrolysis of the iron nitrosyl complex [Fe₂(μ₂-SC₄H₃N₂)₂(NO)₄](C₄H₃N₂S^? is pyrimidine-2-thiolate) in the presence of hemoglobin (Hb) is accompanied by the NO release into a solution. In the absence of Hb, the starting complex is oxidized by nitric oxide that is released into a solution, which leads to further transformations of NO, nitric oxide being present in the solution only partially. The effective rate constant for the decomposition of the complex is high and depends on its concentration. On the one hand, in the presence of Hb, NO molecules rapidly and irreversibly bind to Hb to form HbNO, which is the intermediate in the nitric oxide metabolism. On the other hand, the reversible binding of the iron nitrosyl complex to the surface functional groups of Hb leads to a decrease in its concentration in a solution and deceleration of the formation of NO. Therefore, Hb can ensure the complete and more prolonged assimilation of NO.     

Structure and properties of μ<Subscript>2</Subscript>-<Emphasis Type="Italic">S</Emphasis>-[bis(benzenethiolato)tetranitrosyldiiron] in solution

Dinuclear iron tetranitrosyl complex with the composition [Fe₂(SPh)₂(NO)₄] (1) was synthesized and its single crystals and polycrystals were studied by X-ray diffraction, IR spectroscopy, and elemental analysis. The decomposition products of complex 1 were investigated by electrochemical method and mass spectrometry. The mass spectrum of a solution of complex 1 shows two groups of ions: the primary decomposition products of 1 in solution (the complex ions [Fe(SPh)(NO)₂(NO₂)]⁻, [Fe(SPh)₂(NO)]⁻, and [Fe(SPh)₂(NO)₂]⁻) and a series of the ions [FeO₂ + n(NO)]⁻ and [FeO₃ + n(NO)]⁻ (n = 0–4), which are formed in secondary reactions. The structures of the complexes, which were formed through the Fe-NO bond dissociation and the replacement of the NO ligand by aqua and oxygen ligands in complex 1, and the structure of the complex [FeO₃]⁻ were studied by quantum chemical modeling.     

Anisotropy of the local field in anisotropic films of conjugated polymers

Using the data on dispersion of refractive indices in the visible region, the experimental values of the components L _j of the Lorentz tensor have been obtained for uniaxial (crystalline, oriented on a substrate, and stretched) films of conjugated polymers from nanometer to micrometer thicknesses. The dependence of the components L _j on the axial and planar orientations of macromolecules with respect to the optical axis of the film, technology of fabricating the films, and chemical structure of macromolecules has been elucidated. The correlation between the components L _j and the measured parameter η has been determined and the analytical dependence L _j (η) for films with both types of macromolecular orientation has been established. In the visible region (0 ≤ η ≤ 0.5), the presence of one point (η = 1/3) of isotropization of the tensor L and three points (η = 0, 1/3, and 0.5) of isotropization of the local field tensor f has been revealed. The point η = 1/3 of isotropization of the tensors L and f has been determined. A comparison has been made between the values of L _j (η) with predictions of known models of the local field for conjugated polymers.     

Fiber-optic chemical sensor of amine-type compounds

A scheme of a fiber chemical sensor of amine-type compounds has been implemented. The sensor includes a film nanostructure deposited on the end face of an optical fiber 600 μm in diameter. The film consists of luminescent silica nanoparticles modified by functional pyrylocyanine dye, silver nanoparticles, and a photonic crystal opal film. An additional coating of the sensor film from above by a porous selective mirror, such as a photonic crystal, and introduction of silver nanoparticles 5–7 nm in diameter into it make it possible to increase the sensor sensitivity by an order of magnitude.     

Self-sustained oscillations in systems with delay under irregularly varying excitation conditions

A mathematical model of a system consisting of two coupled chaotic delay subsystems is presented. Instead of constant initial conditions in the form of a single impetus to excite the subsystems, continuous irregular oscillations are used that simulate intrinsic noise and continue acting on self-sustained oscillations after their excitation. An equation of an autonomous subsystem with regard to feedback variation is derived. It is shown that, when an autonomous subsystem is excited by irregular oscillations, chaotic motions become stochastic. In this case, the intensity of oscillations simulating intrinsic noise increases, suppressing self-sustained oscillations and providing the regenerative amplification of irregular oscillations. Interaction of coupled oscillations for identical and nonidentical subsystems is considered for the case of different noiselike initial conditions. It is found that interacting oscillations are not completely identical even if the parameters of the subsystems are the same.     

Flow and heat transfer of non-Newtonian fluids in enameling dies

The present work analyses computationally the flow inside wire enameling dies within the framework of the lubrication theory approximation. Non-Newtonian flow behavior and heat transfer are accounted for as well. It is shown that the developed approach most accurately predicts the momentum and heat fluxes along the wire. As such it is proven as a reliable and computationally efficient tool for the design of flow optimized die shapes. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Finely dispersed refractory compounds for high-temperature ceramic matrix composite applications

Application of finely dispersed refractory compounds in the creation of high-temperature ceramic matrix composites (HTCMC) is briefly reviewed. Examples of successful combination of nanomaterials and HTCMC technologies are given.