An express method of synthesis of surface-modified membrane composites is suggested that allows obtaining heterogeneous materials featuring effects of the blocking of the transport of solvent ions and molecules. Studies using the methods of atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and IR spectroscopy show that polyaniline is in the form of emeraldine and water at the interface of polyaniline aromatic chains and initial membrane sulfogroups is in a structured state due to formation of interpolymer complexes. This determines higher thermal stability of composites and specific morphology of the polyaniline layer. Measurement of electroosmotic and diffusion permeability and also membrane conductivity in HCl solutions (with the concentration of 0.01 to 2 M) shows the blocking effect of the polyaniline layer causing a significant decrease in transport characteristics in a wide range of concentrations of equilibrium solutions. A model of structural heterogeneity of composites is offered that takes into account the presence of an additional structural element, polyaniline, in the basic polymer matrix. Mechanisms of the observed barrier effects are discussed. Comparison of the transport-structural parameters of the MF-4SK membrane and MF-4SK/PAn composites allows elucidating the role of polyaniline in formation of transport routes for ion and solvent fluxes.

BACKGROUND: Dental erosion is a common problem in modern societies, owing to the increased consumption of acid drinks such as soft drinks, sports drinks, fruit juice. Examining the enamel surface with the Atomic Force Microscopy (AFM) enables more precise registering and defining the changes of enamel surface structure and microhardness. This method can be used to compare the efficiency of application of different preventive and therapy materials and medicaments in dentistry. The chronic regular consumption of low pH cola drinks encouraged the erosion of the teeth. The loss of anatomy and sensitivity are direct results of acid cola dissolving coronal tooth material. Under the influence of coca cola, a change of crystal structure and nanomorphology on enamel surface occurs.AIM: This paper reflects dental damage from abusive cola drinking, and the clinical presentation can be explained from data presented in this thesis.MATERIAL AND METHODS: The trial was conducted on a total of 40 extracted teeth which were divided into two groups treated with the solution of coca cola during 5 minutes, and then prepared and tested with a standard AFM procedure, type SPM-5200. Quantitative analysis was performed by comparing the roughness parameters (Ra) of the treated and non-treated sample.RESULTS: Based on the test of a hypothesis of the existence of differences between the treated and untreated sample, with an application of a t-test, it is shown that there are statistically highly significant differences between Ra of the treated sample with a 5-minute treatment of coca cola and Ra of the same sample without the treatment.CONCLUSION: Use of AFM enables successful monitoring of changes on enamel surface as well as the interpretation of the ultrastructural configuration of the crystal stage and the damage created under the influence of different external factors.

Effect of the nature of carbon-graphite materials on the kinetics of intercalation of lithium ions into the matrix of electrodes of lithium power cells, on the physicochemical characteristics of lithium intercalation-deintercalation, and discharge characteristics of compacted graphite-containing electrodes was subjected to a comparative study.

The possibility of preparing graphite from hydrolysis lignin using pyrolysis and graphitization processes was considered. The influence of lignin milling on the granulometric composition of the graphite obtained was studied. The structure of graphite prepared from lignin was confirmed by X-ray diffraction analysis. Prospects for using graphite materials prepared from lignin in electrochemical and other technologies are demonstrated.

The possibility of the adsorption of priority pollutant gases (nitrogen dioxide, methane, ammonia, sulfur oxide (II), hydrogen sulfide, ozone, carbon monoxide, carbon monoxide (II), chlorine) on the surface of chromium-containing pyrolyzed polyacrylonitrile (pPAN) is evaluated. A model of a cluster of chromium-containing pPAN (Cr-PAN) is constructed. The thermodynamic parameters of the following systems are determined by the method of molecular modeling and compared: Cr-pPAN cluster–gas molecule, Cr-pPAN cluster–oxygen molecule, Cr-pPAN cluster–water molecule, Cr-PAN cluster–oxygen molecule–gas molecule, and Cr–pPAN cluster–water molecule–gas molecule. The effect of a water molecule on the process of adsorption of pollutant gases on the surface of a Cr–PAN cluster and the absence of an effect of an oxygen molecule located in the immediate vicinity of the clusters are revealed. It is established that Cr-pPAN has the property of selective adsorption of the following gases: nitrogen dioxide, chlorine, and ammonia. Within the density functional theory (DFT), the force parameters of the Cr–pPAN structure are estimated and the increase in the contact surface zone upon the introduction of a Cr₂O₃ molecule is confirmed.