Electrical properties of composites based on polystyrene with hybrid silicon dioxide particles

Composites based on polysterene and hybrid core-shell nanoparticles are studied; the nanoparticle core consists of silicon dioxide, and ethylphenylic groups (organic shell) are grafted to the core surface. It is shown that the permittivity, the volume resistivity, the thermostimulated depolarization current spectra, and the glass transition temperature of these materials depend on the nanofiller content and, what is more important, the nanofiller distribution over the polymer volume in the form of particles or their aggregates.     

Reaction of tetracyanoquinodimethane with azoles

The reaction of tetracyanoquinodimethane (TCQD) with azoles was studied. It was found that products of 1,6 addition to the quinoid system of TCQD are formed with pyrrole, indole, and their methyl derivatives. The addition products split out HCN under the influence of UV light to give deeply colored products of replacement of one nitrile group in TCQD by a heterocyclic grouping. Data on the UV and NMR spectra of the compounds obtained are presented.Communication IV from the series Chemistry of Quinomethanes. See [3] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 1633–1639, December, 1976.     

Rheological properties of sulfur-containing hyperbranched polycarbosilanes and related magnetic compositions

Russian Chemical Bulletin - The rheological properties of hyperbranched polycarbosilanes with butyl and decyl terminal groups and their sulfur-containing analogs were compared. The use of various...     

Synthesis and study of a sorbent based on silica gel modified with hyperbranched poly(dichloromethylsilylpropyl)carbosilane with molecular imprints of 2,4-dichlorophenoxyacetic acid

A new sorbent for selective sorption of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solutions—silica gel modified with hyperbranched poly(dichloromethylsilylpropyl)carbosilane with molecular imprints of 2,4-D (SG-MI)—has been synthesized, and its specific surface area has been estimated. Sorption of 2,4-D has been studied under static conditions. Analysis of sorption isotherms shows that SG-MI is capable molecular recognition of 2,4-D. The selectivity of the sorbent synthesized was estimated for structurally related compounds.     

Fracture of polystyrene- and molecular silica sol-based nanocomposites during fast compression

Polystyrene-based composites containing hybrid molecular silica sol nanoparticles with a core-shell structure are studied during fast compression. Polystyrene and the related composites are found to fail instantaneously at a certain critical pressure, which is accompanied by the emission of electromagnetic and acoustic waves. The composite composition changes the critical pressure during explosion and the frequency characteristics of the generated electromagnetic and acoustic waves. The charge density transfer mechanism in a composite with a filler concentration higher than 10 wt % is shown to differ from that in composites with a lower filler content.     

Behavior of polystyrene-based nano- and microcomposites under fast compression

Composites based on polystyrene (PS) and core-shell hybrid nanoparticles of molecular silica sol are studied during fast compression. At a certain critical pressure, PS and the related composites are found to fail instantaneously. This process is accompanied by the emission of electromagnetic and acoustic waves. The sample composition and the filler particle size change both the critical pressure during explosion and the frequency characteristics of the appearing electromagnetic and acoustic waves. The fracture of PS and the related composites is accompanied by the formation of a fibrillar structure.     

Antagonists to human and mouse vascular endothelial growth factor receptor 2 generated by directed protein evolution in vitro

Using directed in vitro protein evolution, we generated proteins that bound and antagonized the function of vascular endothelial growth factor receptor 2 (VEGFR2). Binders to human VEGFR2 (KDR) with 10-200 nM affinities were selected by using mRNA display from a library (10(13) variants) based on the tenth human fibronectin type III domain (10Fn3) scaffold. Subsequently, a single KDR binding clone (K(d) = 11 nM) was subjected to affinity maturation. This yielded improved KDR binding molecules with affinities ranging from 0.06 to 2 nM. Molecules with dual binding specificities (human/mouse) were also isolated by using both KDR and Flk-1 (mouse VEGFR2) as targets in selection. Proteins encoded by the selected clones bound VEGFR2-expressing cells and inhibited their VEGF-dependent proliferation. Our results demonstrate the potential of these inhibitors in the development of anti-angiogenesis therapeutics.