On the contact interaction between a strip-shaped punch and a linearly-deformable base through a covering of variable thickness

The contact problem of the frictionless penetration of a punch with strip-shaped section into the surface of a linearly-deformable base protected by a thin elastic layer (covering) of variable thickness, the stiffness of which is comparable to or smaller than that of the supporting elastic body, is investigated. A Fredholm integral equation of the second kind is obtained for the unknown contact pressure with a coefficient in front of the leading term that is a fairly arbitrary function of the longitudinal coordinate. To solve it the Bubnov-Galerkin projection method is used in which the coordinate elements are chosen to be a system of orthogonal polynomials and delta-shaped functions [1, 2] (variational-difference method), together with an algorithm for the required asymptotic expansions [3] when the above-mentioned coefficient is small. In the special case of an elastic half-space protected by a covering of constant thickness, the results obtained are compared with the corresponding characteristics given in [4].     

[Co(solv)<Subscript>6</Subscript>][B<Subscript>10</Subscript>H<Subscript>10</Subscript>] (solv = DMF and DMSO) for low-temperature synthesis of borides

The synthesis and structure of complexes [Co(solv)₆][B₁₀H₁₀] (solv = DMF and DMSO) have been reported. Both complexes have been prepared in a high yield by the reaction between cobalt(II) salts and closo-decaborates Cat₂[B₁₀H₁₀] in the corresponding solvent. The complexes have been characterized by elemental analysis, IR and UV spectroscopy, X-ray powder diffraction, and X-ray crystallography. The thermal properties of the compounds have been studied in the temperature range 20–600°C under argon. The conditions to form cobalt borides have been determined based on the results of thermal analysis, subsequent annealing of the complexes in various conditions, and analysis of IR spectra of the resulting thermolysis products.     

Preparation of nanostructured titania thin films by sol–gel technology

This study is concerned with the preparation of hydrolytically active heteroligand complex [Ti(OC₄H₉)_3.61(O₂C₅H₇)_0.39] from titanium butoxide and acetylacetone and with the gel formation kinetics in a solution of this complex upon hydrolysis and polycondensation. Single-layer and double-layer thin films of a solution of this precursor were coated on polished silicon substrates using the dip-coating method. The crystallization of nanostructured titania films during the heat treatment of these xerogel coatings was studied using various protocols; the anatase–rutile phase transition temperature was found to depend on the film thickness. The effects of the precursor solution viscosity on the film thickness and crystallite size were determined.     

Modification of solids with polymer nanolayers as a process for manufacture of novel biomaterials

The results of study on the chemical deposition of polymeric coatings of a nanoscale thickness on porous and flat inorganic matrices and encapsulation of nano-and microparticles in polymer shells are discussed. Procedures for the deposition of homogeneous defect-free coatings are detailed by using polytetrafluoroethylene, polyaniline, and their derivatives as examples. The matrices modified with nanosized polytetrafluoroethylene and polyaniline layers are promising biomaterials for one-step isolation of nucleic acids from complex biological mixtures (cell and tissue lysates, whole blood, plant feedstock), as well as for high-performance chromatography of proteins and other biopolymers. Approaches to the fabrication of polymer shells on luminescent nanocrystals of (CdSe)ZnS via the inclusion of the nanocrystals in micrometer-sized particles based on acrolein-styrene copolymers and the formation of polymer shells directly on nanoparticles are discussed. It was shown that polymer-functionalized luminescent nanocrystals hold promise as bioanalytical reagents.     

Mechanochemical synthesis of complex hydrides

This survey concerns the effects of mechanical treatment on the properties of simple and complex hydrides and solid-phase reactions that occur during mechanical activation of hydride systems. Special attention is paid to the mechanochemical synthesis of hydroborates and hydroaluminates.     

The optical properties of solid carbohydrates irradiated with γ radiation

The ultraviolet absorption spectra, the optical activity and the reference index of solutions of glucose, sucrose, and maltose prepared from irradiated powders were investigated.     

Multifunctional polymer dispersions for biomedical assays obtained by heterophase radical polymerization

Methods for the preparation of multifunctional dispersions of polymer particles (DPP) in the course of free radical heterophase polymerization, which provides careful control of both macromolecular and colloidal properties, are considered. Approaches that, according to the polymerization technique, make it possible to control the particle diameter and shape, particle size distribution, colloidal stability, morphology, surface chemistry and functionality, as well as the formation of organo-inorganic hybrid particles, are demonstrated. The possibilities of DPP application in homogeneous and heterogeneous assays and cell labelling are reviewed. The use of DPP leads to decrease the reaction scales and costs and to increase the speed, sensitivity, selectivity, and reproducibility of assays.     

Upconversion nanoparticles for tumor imaging with near-infrared radiation

Prospects for using upconversion nanoparticles as markers for tumor optical imaging are discussed. Using a model of epidermoid Lewis lung carcinoma engrafted in mice, luminescent signals from nanoparticles delivered into the tumor tissue are registered in vivo.     

Effect of magnetic field on lyotropic nematic in the vanadium pentoxide (V2O5)-water system

The optical textures of anisotropic phases of dispersed aqueous vanadium pentoxide solutions have been studied. It was established that the application of a magnetic field to these phases results in the formation of transient magnetohydrodynamic domains. The evaluation of the Freedericksz threshold field for the S-effect provided the determination of the elastic constant, K ₁ ≈ 3.6 × 10^?7 dyn. It is concluded that the studied anisotropic phases can be related to nematics.     

Optical sensing quantum dot-labeled polyacrolein particles prepared by layer-by-layer deposition technique

Optical sensing polymer particles with tailored semiconductor nanocrystal (QD) loading are prepared by layer-by-layer deposition technique (LbL). Polyacrolein particles of 1.2 μm diameter are used as solid support for deposition of hydrophilic CdSe/ZnS nanocrystal/polyelectrolyte multilayers formed by electrostatic interactions. The pH-dependent fluorescence of QDs and pH-dependent conformations of polyelectrolytes, which likely passivate the surface state of nanocrystals, allow a creation of both mono- and multiplex coded polymer particles with pH-dependent fluorescence intensity. Bovine serum albumin (BSA) as outermost layer makes it possible to design the optical sensing polymer particles with reversibly responded fluorescence at pH variations. The fluorescence of such polymer particles with BSA outer layer is sensitive to copper(II) ion while the fluorescence of these particles is practically insensitive to the other divalent cations (Zn(2+), Ca(2+), Ba(2+), Co(2+), Mg(2+)). The detection limit of Cu(2+) is about 15 nM. Adaptation of LbL method to prepare QD-labeled polymer particles with enhanced complexity (e.g. several types of QDs, multiple biofunctionality) is expected to open new opportunities in biotechnological applications.