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The interaction of styryl derivatives of pyridine N-oxides with proton donors in various solvents was studied. UV-Vis spectroscopy and thermogravimetric analysis were applied to determine the spectral and thermo-chemical characteristics of the resulting molecular complexes. The dependences of the thermodynamic parameters of the complexes on the N-oxide structure and on the solvating medium were established. The DSC method was used to determine the temperature and enthalpy characteristics of the desolvation and melting processes for both N-oxides and their complexes with proton donors.

Chitosan is a naturally occurring polysaccharide derived from chitin with a wide range of uses. Phthalocyanines are macroheterocyclic compounds that have a number of useful properties such as coloring and catalytic and antioxidant activity. Phthalocyanines are able to immobilize on chitosan, forming complexes with new useful properties. In this work, we evaluated the ability of phthalocyanines to increase the thermal stability of chitosan. Chitosan (CS) forms complexes with copper(II)-(CuPc) and cobalt(II)-(CoPc) tetrasulphophthalocyanines. The processes of destruction of chitosan (CS) and its complexes with sulphophthalocyanines CuPc and CoPc in oxidizing and inert atmospheres have been studied. It was established that, regardless of the atmosphere composition, the first chemical reactions taking place in the studied systems are elimination reactions. The latter ones in the case of chitosan and complex CS-CuPc lead to the formation of spatially crosslinked polymer structures, and it causes the release of CuPc from the polymer complex. It was found that in the case of CS-CoPc elimination reactions did not lead to the formation of crosslinked polymer structures but caused the destruction of the pyranose rings with a partial release of CoPc. Metallophthalocyanines showed antioxidant properties in the composition of complexes with chitosan, increasing the temperature of the beginning of glycosidic bond cleavage reaction by 30–35 °C in comparison with the similar characteristics for chitosan.

Poly(methyl methacrylate) films and poly(methyl methacrylate)/fullerene composite films were fabricated by casting from toluene solutions. The mass fraction of fullerene (C60) was varied from 0.05–...

The particle-size distribution in silica powder prepared by the sol–gel method has been determined by dynamic light scattering analysis. The average diameter of the particles was found to be 250 nm. Using a low-temperature nitrogen adsorption–desorption technique, it was found that the synthesised powder may be referred to as mesoporous materials. Polystyrene/silica composite films were fabricated by casting from o-xylene solutions. It was found, using thermogravimetry, that incorporation of silica leads to an increase in both the onset temperature of polymer degradation and in the temperature at which the maximum rate of weight loss occurs. Using differential scanning calorimetry, the phase transitions from the glassy state to the elastic one were studied for the polymeric materials. New data relating to the effect of silica on the glass-transition temperature, Tg, of composites with a low weight fraction of SiO2 were found. Specifically, we found a non-monotonic concentration dependence of the v...

Using thermogravimetry, the thermal stability of polymeric polystyrene/silica composites containing 0–5 wt % of filler is studied. It is found that, the higher the concentration of SiO2, the higher the characteristic temperatures of thermal destruction of the composite. Using the van Krevelen method, kinetic analysis of the obtained thermogravimetric curves was carried out. An increase in the activation energy of the process of thermal destruction is revealed with increasing silica concentration in the composite.

The current study aims at evaluating the causes of premature failure of roads in India by field investigation along with suggesting remedial measures to mitigate the earlier deterioration w...

The complexation processes of chitosan with cobalt(II)tetrasulfophthalocyanine (CoPc) and copper(II)tetrasulfophthalocyanine (CuPc) were studied calorimetrically in solution. It was established that CoPc forms two types of complexes with chitosan, while CuPc forms a single type of complex with chitosan, in which copper(II)tetrasulfophthalocyanine is in dimerized form. The complexes are thermodynamically stable, which was allowed to study them in a solid form by different methods. Joint application of DSC and TG/DTG methods allowed us to identify the temperature intervals for evaporation of physically and chemically bounded water and thermal decomposition of chitosan and its complexes. The glass transition temperature of chitosan (110.8 °C) is greater than the glass transition temperature of the complexes with CuPc (74.7 °C) and CoPc (71.2 °C). Using SEM images and X-ray data of heated, unheated chitosan and its complexes, it was shown that the complexes are predominantly amorphous. Heating of chitosan and its leads to increasing of amorphous phase. Modification of chitosan by phthalocyanines leads to decreasing of thermal stability of complexes insignificantly.

The current work emphasizes improving the procedure for analysis and design of flexible pavement by considering a variety of materials to be used in different layers of pavement. Field investigation and laboratory analysis were carried out to classify the subgrade soil based on their strength parameter. It is observed that most of the flexible pavement near Satara is getting deteriorated earlier than its design life. In the present study, the effect of waste materials individually and in combination on the physical properties, rutting, and fatigue behavior of pavement by laboratory and analytical investigation is evaluated. The various important input parameters like traffic characteristics, moduli of paving materials, etc. are used in structural models. The output of structural models in the form of strains, stresses, and deflection are used in distress models while the output of these distress models is examined against fatigue and rutting criteria recommended by the Guidelines for the Design of Flexible Pavements (IRC:37-2012). The computed strains at the critical locations are compared with allowable limits to decide the thicknesses of hypothetical conditions formed under different combinations of varying materials and thicknesses. The design charts proposed by consideration of multiple factors of varying nature are more realistic and optimum design charts, which can be considered to replace existing pavement sections with an eco-friendly and economic approach.

Polymethylmethacrylate-based film composites containing small additives of fullerenes (up to 3 wt %) are obtained. The thermal behavior of the obtained materials is studied by DSC in the temperature range from 25 to 130°C. It is found that the character of the DSC curve depends on the composite composition. For films containing up to 0.1 wt % C60, one glass transition temperature (Tgsoft) is observed, while in the case of films with a higher concentration of the filler, two glass transition temperatures (Tgsoft and Tgsolid) are observed. It is found that the dependence of Tgsoft value on the content of fullerenes is nonmonotonic with a minimum at 0.5 wt % of C60.

Thermal stability of polyvinyl alcohol/cellulose nanocrystals composites has been studied. It has been shown that nanocrystalline cellulose in its acid form considerably enhances the thermal stability of the composites, while the neutral form of the nanocrystalline cellulose has little effect on the thermal stability of the composites.

The results of studies and comparative analysis of thermal properties and photostability of zinc(II) complexes with tetramethyl- and tetraphenyl-substituted dipyrrins and tetraphenyl-meso-azadipyrrin are reported. The thermal decomposition of complexes starts in the temperature range between 293 and 481°C depending on the molecular structure. Tetraphenyl-substituted zinc(II) dipyrrinate shows the highest photoand thermal stability. The substitution of phenyl moieties in the ligand structure with methyl groups and replacement of the methine spacer with a nitrogen atom reduces thermal stability and photostability of the complexes.

The investigation of electrochemical properties of active layers containing 5,15-bis(pyrid-3-yl)-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphine, [5,15-bis(pyrid-3-yl)-3,7,13,17-tetramethyl-2,8,12, 18-tetraethylporphinato]cobalt(II), bispyridine[5,15-bis(pyrid-3-yl)-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphinato]cobalt(III), [5,15-bis(pyrid-4-yl)-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphinato]cobalt(II) and bispyridine[5,15-bis(pyrid-4-yl)-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphinato]cobalt(III) in 0.1 M KOH aqueous solution has been carried out by cyclic voltammetry. The potential ranges of redox processes related to the transformation of the porphyrin macrocycle, pyridyl substituents and central metal have been established. The electrochemical parameters of oxygen electroreduction reaction (the half-wave potential — E[Formula: see text](O[Formula: see text]), the maximum potential — E[Formula: see text](O[Formula: see text]), the current density — j, the activation energy — Eact) have been determined. It was shown that all porphyrins exhibit the catalytic activity. The electroreduction process of oxygen on electrode with the porphyrin-ligand occurs via 2-electron mechanism to give hydrogen peroxide ion HO2-, and on ones with the cobalt porphyrins — via parallel-sequential pathway including 2-electron and 4-electron processes to give HO2-, OH-. The presence of pyridine axial ligands in Co-complexes leads to a significant increase of the electrocatalytic activity in molecular oxygen reduction reaction.

The data on thermal stability under argon atmosphere of a series of porphyrin ligands containing meso- and β-positioned electron-donor (Me, Et, or Ph) groups as well as electron-acceptor pyridinyl substituents differing in the heteroatom location are presented. Thermogravimetric analysis and electron absorption spectroscopy studies have shown that pyridinylporphyrins are thermally stable at heating to 360–500°С depending on the functional substitution in the molecule.

Aurora‐A regulates the recruitment of TACC3 to the mitotic spindle through a phospho‐dependent interaction with clathrin heavy chain (CHC). Here, we describe the structural basis of these interactions, mediated by three motifs in a disordered region of TACC3. A hydrophobic docking motif binds to a previously uncharacterized pocket on Aurora‐A that is blocked in most kinases. Abrogation of the docking motif causes a delay in late mitosis, consistent with the cellular distribution of Aurora‐A complexes. Phosphorylation of Ser558 engages a conformational switch in a second motif from a disordered state, needed to bind the kinase active site, into a helical conformation. The helix extends into a third, adjacent motif that is recognized by a helical‐repeat region of CHC, not a recognized phospho‐reader domain. This potentially widespread mechanism of phospho‐recognition provides greater flexibility to tune the molecular details of the interaction than canonical recognition motifs that are dominated by phosphate binding.