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188 results on '"A. P. Timosheva"'

27. Self-organization and properties of dispersed systems based on dilute aqueous solutions of ( S )- and ( R )-lysine

Author

Svetlana Yu. Sergeeva, M. D. Shevelev, Olga A. Salakhutdinova, Yuliya V. Kiseleva, Irina S. Ryzhkina, A. P. Timosheva, and Alexander I. Konovalov

Subjects
Range (particle radiation), Aqueous solution, 010405 organic chemistry, Chemistry, Lysine, Uv absorption, General Chemistry, 010402 general chemistry, 01 natural sciences, Spectral line, 0104 chemical sciences, Chemical engineering, Phase (matter), Nanometre
Abstract

In a concentration range of 1.0–1.0 × 10–17 mol dm–3, aqueous systems based on (S)-and (R)-lysine vary in the ability to form a dispersed phase (domains and nanoassociates) hundreds nanometers in size with different UV absorption spectra of these systems.

Published
2018

41. Specifics of self-organization and properties of highly dilute aqueous solutions of polyoxidonium

Author

L. I. Murtazina, S. Yu. Sergeeva, Irina S. Ryzhkina, Alla V. Chernova, A. B. Margulis, S. A. Ryzhkin, R. A. Safiullin, M. K. Kadirov, A. P. Timosheva, and A. I. Konovalov

Subjects
Aqueous solution, Conductometry, 010405 organic chemistry, Chemistry, Analytical chemistry, Nanoparticle tracking analysis, General Chemistry, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Ultraviolet visible spectroscopy, Transmission electron microscopy, Phase (matter), Nanometre, Electrophoretic light scattering
Abstract

Using a combination of physicochemical methods (dynamic and electrophoretic light scattering (DLS and ELS, respectively), nanoparticle tracking analysis, atomic force and transmission electron microscopy (AFM and TEM, respectively), UV spectroscopy, conductometry, pH-metry, dielcometry), it was found that dilute solutions of a multicomponent drug immunomodulator polyoxidonium (PO) are nanoheterogeneous disperse systems, with their disperse phase undergoing considerable restructurings when diluting the solution in the range of calculated concentrations from 1∙10–1 to 1∙10–16 mg mL–1, which is reflected in the non-monotonous concentration dependencies of specific electroconductivity, dielectric permittivity, and pH of the solutions. Using ELS, AFM, TEM, and UV spectroscopy methods, it was found that the disperse phase with a size of hundreds of nanometers which forms at concentrations of ≤1∙10–5 mg mL–1, contains organized water structures substantiating the negative values of ζ-potential, which vary non-monotonously from–5 to–16 mV. Radioprotective properties of dilute solutions of PO (1∙10–1 and 1∙10–9 mg mL–1) were demonstrated for the first time when exposing the test mutant bacterial strain Salmonella typhimurium TA 100 (Ames test) to X-ray radiation in a dose of 7.50 mGy used for medical diagnostics.

Published
2016

43. Highly diluted aqueous solutions of cetyltrimethylammonium bromide: Correlations between self-organization, physicochemical properties, and biological activity

Author

Irina S. Ryzhkina, O. A. Mishina, A. D. Voloshina, A. P. Timosheva, A. I. Konovalov, Yu. V. Kiseleva, and N. V. Kulik

Subjects
chemistry.chemical_compound, Aqueous solution, Chemistry, Bromide, Critical micelle concentration, Inorganic chemistry, Organic chemistry, Biological activity, Physical and Theoretical Chemistry
Published
2014

45. Diffusivity data and reaction kinetics as probes for self-assembling: Cationic surfactant–chloroform system

Author

Svetlana S. Lukashenko, Shamil K. Latypov, Ruslan R. Kashapov, Elena P. Zhiltsova, A. P. Timosheva, Lucia Ya. Zakharova, Alexander I. Konovalov, and Victor V. Syakaev

Subjects
Chloroform, General Chemical Engineering, Inorganic chemistry, Cationic polymerization, General Physics and Astronomy, Micelle, chemistry.chemical_compound, chemistry, Pulmonary surfactant, Bromide, Reagent, Organic chemistry, Reactivity (chemistry), Physical and Theoretical Chemistry, Octane
Abstract

Herein two sensitive techniques, i.e., NMR self-diffusion measurements and dielcometry are involved to test the association of cationic surfactant 4-aza-1-tetradecyl-1-azoniabicyclo[2.2.2]octane bromide (BC-14) and polyethyleneimine hydrophobized with tetradecyl moieties (PEI-14) in their chloroform solutions. The data obtained make it possible to nominate these methods as highly powerful instruments for the identification of a very uncooperative aggregation. Mixed BC-14/PEI-14 association is probably observed only at a relatively high polymer concentration, which is indicated by a decrease in the diffusivity of surfactant molecules. Aggregation is strongly promoted by the addition of water, with a high [water]/[BC-14] molar ratio of 60 attained. Even a very slight association has a serious impact on the reactivity, the pre-concentration effect and the shift of acid–base equilibrium of solutes. A 4-fold acceleration of the reactivity of an organophosphorus pollutant occurs in the BC-14 reverse micelles due to the concentration of reagents and changes in their microenvironment, which strongly supports the very idea of association. The high binding constants derived from the analysis of kinetic data provide evidence on high degree of concentration of compounds, while changes in the microenvironment affect their ionization. These impacts may be of key importance in analytical procedures and the chemical reactivity of compounds in nonpolar media.

Published
2013

46. Self-organization and chirality in the high dilution solutions of glycoluril enantiomers with (R)- and (S)-methionine moieties

Author

L. I. Murtazina, Angelina N. Kravchenko, Vladimir V. Baranov, Alexander I. Konovalov, Svetlana Yu. Sergeeva, Yuliya V. Kiseleva, A. P. Timosheva, O. A. Mishina, and Irina S. Ryzhkina

Subjects
Supramolecular chirality, chemistry.chemical_compound, Methionine, chemistry, Stereochemistry, Mole, Glycoluril, Moiety, General Chemistry, Enantiomer, Chirality (chemistry), Dilution
Abstract

The high dilution (1×10 -15 –1×10 -5 mol dm -3 ) solutions of glycolurils containing an ( S )-methionine moiety are capable of space-time self-organization to give nanoassociates, unlike the solutions of glycolurils with an ( R )-methionine moiety. The formation of supra- molecular domains in the solutions at concentrations of 1×10 -3 –1×10 -2 mol dm -3 is responsible for a transition from molecular to supramolecular chirality.

Published
2015

47. Theoretical study of the structure of N-arylmaleimides and bis-maleimides

Author

Denis V. Chachkov, Ya. A. Vereshchagina, and A. P. Timosheva

Subjects
Quantum chemical, Steric effects, Dipole, Computational chemistry, Chemistry, Organic Chemistry, Steric factor, Moment (physics), Chlorine atom, Ring (chemistry), Inductive effect
Abstract

Conformational analysis of N-arylmaleimides and bis-maleimides was performed by the dipole moment method and quantum chemical calculations. The aromatic ring and heterocycle in N-arylmaleimides are turned with respect to each other through an angle of 42–44°, which excludes conjugation between these fragments. No conjugation exists between the dioxopyrrole rings in bridged bis-maleimides. The structure of the examined compounds is controlled by steric factors. Pronounced inductive effect of chlorine atoms in chloro-substituted bis-maleimides is responsible for their reduced dipole moments.

Published
2013

48. Low-concentration aqueous solutions of an amphiphilic calix[4]resorcinarene derivative: Self-organization, physicochemical properties, and biological activity under common and hypoelectromagnetic conditions

Author

Yu. N. Valitova, M. K. Kadirov, Irina S. Ryzhkina, Roman A. Safiullin, Yu. V. Kiseleva, A. P. Timosheva, and A. I. Konovalov

Subjects
chemistry.chemical_compound, Aqueous solution, chemistry, Amphiphile, Organic chemistry, Biological activity, Physical and Theoretical Chemistry, Resorcinarene, Derivative (chemistry), Volume concentration
Published
2012

49. Relationship between self-organization, physicochemical properties, and biological activity of aqueous solutions of hemin derivatives

Author

G. A. Zheltukhina, Yu. V. Kiseleva, L. I. Murtazina, A. P. Timosheva, A. I. Konovalov, V. E. Nebolsin, S. A. Okorochenkov, and Irina S. Ryzhkina

Subjects
chemistry.chemical_compound, Aqueous solution, Dynamic light scattering, chemistry, Computational chemistry, Inorganic chemistry, Biological activity, Physical and Theoretical Chemistry, Hemin
Published
2011

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