Study of the topology of metal-containing granular films by light scattering and atomic force microscopy

The correlation properties of films consisting of granular structures with granules smaller than 6 nm prepared by the laser electrodispersion method are investigated. The correlation functions of the nanoparticle distribution on a transparent substrate are calculated from the angular structure of scattered radiation using the single-scattering approximation, as well as from the data of atomic force microscopy for copper, nickel, and palladium structures with different packing density. The size of coarse particles in nanostructures is estimated.     

By how many tautomerisation routes the Watson–Crick-like A·C* DNA base mispair is linked with the wobble mismatches? A QM/QTAIM vision from a biological point of view

Here for the first time we present four novel routes of the tautomerisation via the sequential DPT that links biologically important A·C*(WC) DNA base mispair with Watson–Crick (WC) geometry and wobble (w) A*·C*(w), A·C*_O2(w), A*·C*(w ₁) and A·C(w _⊥) mismatches, pursuing the goal of estimation of their contribution into the transition mutations during DNA biosynthesis. These processes occur without opening of the pairs and are accompanied by the substantial changes in their geometry. A detailed analysis of these pathways leads to an identification of the A·C*(WC)?A*·C*(w) tautomerisation route as the most suitable among these processes from the point of view of the spontaneous point mutagenesis, since it proceeds via the time that is significantly less than the time used by the replicative DNA-polymerase for the incorporation of one incoming nucleotide into the synthesised DNA double helix. This non-dissociative transition occurs through the planar, highly stable, zwitterionic \( {\text{TS}}_{{{\text{A}} \cdot {\text{C*(WC)}} \leftrightarrow {\text{A}}^{ + } \cdot {\text{C}}^{\text{ - }} (w )}}^{{{\text{A}}^{ + } \cdot {\text{C}}^{\text{ - }} }} \) transition state and dynamically unstable intermediate A⁺·C^?(w) ion pair and is accompanied by the consistent rearrangement of the 10 unique patterns of the specific intermolecular interactions, among which there are from 2 to 4 AH···B H-bonds and 2 loosened A–H–B covalent bridges. Basic physico-chemical properties of this mutual tautomeric transformation, which is internally inherent to the A·C*(WC) and A*·C*(w) base mispairs, are documented, and its possible biological assignment is discussed here.     

Reflection spectra and optical constants of quasicrystalline Al-Pd-Re films in the IR region

Optical properties of quasicrystalline Al-Pd-Re films have been investigated in the mid and far IR regions. Films were deposited on sapphire substrates using layer-by-layer ion-plasma sputtering with subsequent vacuum annealing. Reflection spectra have been measured in a wide IR spectral range from 50 to 7500 cm^?1. The complex dielectric function of the films was determined from the experimental data by dispersion analysis of the reflection spectra. The frequency dependence of the real part of the optical conductivity was calculated.     

In situ immobilization on the silica gel surface and adsorption capacity of poly[4-methacroyloxy-(4′-carboxy-2′-nitro)-azobenzene] on toxic metals ions

Abstract

A new organo-mineral composite material has been synthesized by in situ immobilization of poly[(4-methacroyloxy-(4′-carboxy-2′-nitro)azobenzene on the silicagel surface. As a result of thermogravimetric analysis and DSC-MS analysis it has been found that the composition of synthesized composite includes 10,1?wt. % of polymer. It has been found that the synthesized composite exhibits the sorption ability in terms of microquantities of Cu (II), Cd (II), Pb (II) and Fe (III) ions in a neutral aqueous medium. The maximum degree of sorption of ions Cu (II), Pb (II) and Fe (III) is achieved during the first minutes of contact, and for Cd (II) ions the equilibrium is established within a day. The sorption capacity of silica gel as a result of modification by this polymer increases with respect to Cu (II) ions more than 14 times, with respect to Pb (II) ions - 5 times.     

Effect of gamma radiation on the molecular-topological structure and properties of poly(vinylidene fluoride) and the matrix in a PVDF-based glass-reinforced plastic

The amorphous-topological structure of poly(vinylidene fluoride) (PVDF), the pseudo-network structure of which is formed by polyassociative entities of the cluster type and persists upon γ-irradiation up to 250 kGy, has been investigated. As a result of the processes involved in the fabrication of the glass-reinforced plastic (GRP), five crystalline modifications arise in the polymer matrix instead of cluster branching points in the initial PVDF, and the temperature of the molecular flow of the polymer matrix in the GRP rises from 410 to 593 K in comparison with the initial PVDF. The strength of GRP made of untreated glass cloth (110 MPa) is higher than that of the initial PVDF (86 MPa). However, when using glass cloth treated with a process sizing agent, the strength of the GRP increases up to 286 MPa. After γ-irradiation of the latter, upon which a sharp drop in the strength is observed immediately with the onset of GRP irradiation, the exposure of PVDF and GRP made of untreated glass cloth results in a drop in the strength only after 50 kGy. The irradiation eliminates the properties acquired by the polymer matrix during the fabrication of GRP, and the properties of the GRP polymer matrix approach those of the initial PVDF with an increase in the radiation dose.     

Superconducting synchrotron project for hadron therapy

The project of a superconducting medical synchrotron for carbon therapy in the ion energy range from 140 to 400 MeV/n is discussed in this paper. This project is aimed at developing and building a medical synchrotron on the basis of superconducting technologies at JINR under the construction of the Nuclotron accelerator complex. A linear accelerator with alternating phase focusing is proposed for injecting carbon ion into the synchrotron, while it is planned to use a superconducting gantry weighing about 150 t for delivering radiation treatment to patients from all directions.     

Spectral and concentration dependences of the optical properties of thin layers of oxidized amorphous copper and nickel nanoparticles in the infrared spectral region

Optics and Spectroscopy - The optical properties of thin layers of nanostructures based on oxidized amorphous copper and nickel granules are studied in the IR spectral region. The absorption...