Theoretical characteristics of codeless GPS-signal acquisition in the L1 band are described and analyzed. The results obtained allow for a reliable choice of a coherent integration interval, calculation of signal detection thresholds, and estimation of signal detection probability. The operability and feasibility of the technique for codeless signal acquisition by frequency has been experimentally confirmed with the use of a software receiver.

The redox transformations in a conducting polymer film on a platinum electrode were studied by Raman spectroelectrochemistry at fixed potentials depending on the incidence angle of the laser beam. Raman scattering was excited with a laser at a wavelength of 532 nm. Polyaniline (PANI) and its complex with poly-2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPSA) were used as a conducting polymer. The polymer films were deposited by potentiostatic electropolymerization. By varying the incidence angle of the beam it is possible to obtain a Raman spectrum without the bands of the substrate overlapping with the characteristic bands of the polymer to minimize the substrate effect on the interpretation of the results. A comparative study of the electrochemical oxidation/reduction of the PANI films taking into account the detected angular dependence showed that, unlike the PANI films obtained in the presence of hydrochloric acid, the films of the PANI-PAMPSA complex retained the radical cation state of PANI in the range of the cathodic potentials. The reason for this is the presence of a nonconductive polymer acid phase in the PANI-PAMPSA film, as a result of which the percolation threshold of the conducting domains of PANI appears at less cathodic potentials, hindering further extraction of the positive charge during the film reduction. In addition, the use of this approach can significantly improve the accuracy of determination of the threshold potential of the leucoemeraldine-emeraldine transition.

Для сорбции вирусов гриппа из водной среды применен электропроводящий полимер полипиррол с сопряженной структурой цепей. Исследована эффективность связывания вируса полимером для чего, использованы различные факторы, разрушающие сорбционные взаимодействия: воздействие растворителя, повышенная температура, ультразвук. Изучена возможность десорбции вируса под действием перечисленных факторов. Определена инфекционная активность вирусов в обработанных сорбентом водных средах, в комплексах с полимером, у десорбированных вирусов

The paper considers joint software processing of signals from global (GLONASS, GPS, BeiDou, Galileo) and regional (IRNSS) navigation satellite systems. A general block diagram of the prototype multiconstellation software-defined radio (SDR) is presented; its capabilities to process signals from navigation systems are discussed. The developed SDR allows for separate and combined navigation solutions using signals received in Russia’s North-West from 30 satellites of 5 different navigation systems. The accuracy of these solutions and the DOP values are analyzed.

The molecular mobility of nanocellulose hydrogels isolated from microcrystalline cellulose is evaluated using the spin probe method, from the correlation time τ (s) and rotational frequency ν = 1/τ(s–1) of stable nitroxyl radicals introduced into the medium under study. In an aqueous gel medium, the EPR spectrum of the probe features an anisotropic triplet of frozen particles over a temperature range of 77 to 265 K. In an aqueous–ethanolic gel solution, the temperature of onset of rotation of the radical is 85 K lower. The rotational correlation time is determined from the parameters of the EPR spectrum recorded in the temperature range of 180–290 K. The resulting Arrhenius temperature dependence logν = f(1/T) is used to evaluate the activation energy of rotation E of the radical and the preexponential factor ν0(s–1), the frequency of rotational vibrations of the particle around the equilibrium position. For the aqueous medium, E = 11.2 kcal/mol; in the presence of ethanol, E = 5.2 kcal/mol; the preexponential factors for the aqueous and aqueous–ethanolic media are ν0 = 7 × 1018 and 6 × 1014 s–1, respectively. The parameters E and ν0 measured in the pure solvents and in the samples containing nanocellulose differ little, which is indicative of a high hydrophobicity of the probe molecule (and hydrogel particles) and of their weak interaction with the environment. The high value (~1018 s–1) of the preexponential factor is explained in terms of the compensation effect of water.

Conditions that allow obtaining stable aqueous dispersions based on conducting polymer, polyaniline, as a result of aniline polymerization in the solution of polymeric acid at its twofold excess were determined. The electrical and optical properties of polianiline obtained under these conditions remain invariable during at least 2 years due to the absence of aggregation of conducting polymer particles that are separated by macromolecules of polymeric acid. Data obtained by EPR spectroscopy, SEM, UV–visible spectroscopy, and IR spectroscopy prove these results.

Composites of polymers with conjugated chain structures, polyaniline and polypyrrole, are used as sorbents for human and bird flu viruses. Sorption properties of the composites are compared to characteristics of the initial polymers. It is shown that polymer composites containing metallic silver nanoparticles possess sorption activity, similarly to their composites with polyethylene and the initial polyaniline and polypyrrole. The introduction of silver into polypyrrole resulted in an enhancement of the sorption activity as compared to that of the initial polymer. Nontoxic metal—polymer composites reduce considerably the concentrations of human flu viruses A(H1N1), A(H3N2), and B and bird flu virus A(H5N2) with different structures of surface virion proteins in aqueous media at a sorbent concentration of 10–20 mg/mL in the temperature range from +4 to 37°C.

New composite lignocellulose materials were prepared using modified lignin and nanocellulose. The materials were studied by elemental and thermal gravimetric analysis, and their tensile tests were performed. The results obtained show that addition of nanocellulose to modified lignin makes possible its use as filler in paper production.

Chemical polymerization of 3,4-ethylenedioxythiophene is carried out in the presence of polymeric sulfonic acids of different structures, such as flexible-chain polyacids with a uniform distribution of sulfonic acid groups along the macromolecular chain, namely, polystyrene sulfonic (PSSA) and poly-2-acrylamido-2-methyl-1-propanesulfonic (PAMPSA) acids, and rigid-chain polysulfonic acid with a nonuniform distribution of sulfonic acid groups along the macromolecular chain—namely, poly- p , p ′-(2,2′-disulfonic acid)-diphenylene terephthalamide. The polymerization process and the properties of solutions and films of the synthesized complexes of poly-3,4-ethylenedioxythiophene (PEDOT) with the above polyacids are studied by the UV, visible, and near-IR spectroscopy. The electric properties of the films are investigated. The effects of the concentration ratio between the oxidizer and monomer and of the structure of polymeric acid on the kinetics of the PEDOT synthesis, as well as on the spectral and electric properties of the obtained polymer, are revealed. A correlation between the absorption of the PEDOT/PSSA complexes in the near-IR range and their specific conductivity is established.

Electrodeposition of polyaniline (PANI) complexes with a polymeric sulfonic acid of variable molecular weight has been studied with the purpose to explain specific features of aniline electropolymerization in the presence of polyelectrolytes. Poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) was taken as a model polyelectrolyte due to the ease of varying its molecular weight during polymerization of the monomer. Depending on the polyacid molecular weight, crucial changes in the shape of charge– and potential–time dependences and cyclic voltammograms have been observed during potentiostatic, galvanostatic, and cyclic voltammetry syntheses of PANI, respectively. The results are considered in terms of the influence of molecular weight on proton condensation ability of the polyacid and, therefore, on the degree of aniline protonation and its local concentration in the vicinity of polyacid macromolecule. The PANI films obtained are characterized by cyclic voltammetry and UV–vis and Raman spectroelectrochemistry, and the influence of the polyacid molecular weight on these properties is discussed.

Химическую полимеризацию 3,4-этилендиокситиофена проводили в присутствии полимерных сульфокислот различного строения: гибкоцепных поликислот с равномерным распределением сульфокислотных групп вдоль цепи макромолекулы – полистиролсульфоновой (ПССК) и поли-(2-акриламидо-2-метил-1-пропансульфоновой) (ПАМПСК) кислот, а также жесткоцепной полисульфокислоты с неравномерным распределением сульфокислотных групп вдоль цепи макромолекулы – поли-4,4-(2,2-дисульфокислота)дифенилентерефталамида. Ход полимеризации, свойства растворов и пленок синтезированных комплексов поли-3,4-этилендиокситиофена (ПЭДОТ) с вышеуказанными поликислотами были исследованы методом спектроскопии в УФ-, видимой и ближней ИК областях. Изучены электрические свойства этих пленок. Обнаружено влияние соотношений концентраций окислителя и мономера и структуры полимерной кислоты на кинетику синтеза ПЭДОТ, спектральные и электрические свойства получаемого полимера. Показана корреляция между поглощением комплексов ПЭДОТ/ПССК в ближней ИК области и их удельной проводимостью.

The nucleation of the solid phase of interpolymer complexes of polyaniline (PAn) during electropolymerization of aniline on highly orientated pyrolytic graphite in aqueous solutions of hydrochloric acid and polymer sulfoacids, which differ in the rigidity of the polymer framework, was studied in situ by atomic force microscopy. The rigidity of the polyacid chain, which determines possible changes in its conformation in solution and its ability to adapt its conformation to that of the rigid conjugated PAn macromolecule, directly affects the shape and growth rate of the nuclei of solid phase of PAn and the film morphology at the early stages of electropolymerization. The rigid-chain and semirigid-chain polymer acids, which have the conformation of an elongated or slightly bent rod in solution, determine the conformation of the interpolymer complex nuclei. In contrast, in the presence of flexible-chain polyacids, the process is mainly controlled by the conformation of PAn macromolecules.