Russian Journal of Physical Chemistry B最新文献

A model is proposed to study the effect of regiodefects (opposite orientation of adjacent monomer units along a chain) on the behavior of ferroelectric polymers in an electric field at low temperatures. Within the framework of the model, it is shown that there is a smooth reorientation of the dipole moments of monomers near the regiodefects, which is in agreement with the data obtained in the molecular dynamics (MD) calculations. An analytical expression is obtained for the dependence of the average polarization on the temperature, electric field, and concentration of regiodefects is obtained. Comparison with the MD calculations allows us to estimate the bond stiffness of neighboring monomers and the induced electric field. The quantum version of the proposed model is studied. It is shown that the ground state is singlet, and excitations can be either gaped or gapless, depending on the parity of the number of monomers between defects. There is a plateau on the zero-temperature magnetization curve.

In this paper, using fluorescence and confocal microscopy, we study the content of the flavin adenine nucleotide (FAD) cofactor and enzymatic NAD(P)H-oxidase complexes (with fluorophores Annexin V‑ FITC, 7-AAD (7-aminoactinomycin D), EtBr) under conditions of apoptosis caused by sodium anphen with hydrogen peroxide in healthy mouse splenocytes and Lewis carcinoma tumor cells. The use of fluorescence microscopy allows observing and quantifying the apoptotic effect of sodium anphen and hydrogen peroxide, and it also allows visualizing the metabolic changes in the cell, including the increased fluorescence of FAD in tumor cells and NAD(P)H-oxidase complexes in splenocytes. The data obtained indicate the possibility of using sodium anphen in combination with hydrogen peroxide as an antitumor drug acting on certain types of cells.

The change in the surface conductivity of lithium fluoride (LiF) during the adsorption of hydrogen fluoride (HF) is experimentally investigated. It is shown that the specific surface conductivity of LiF increases approximately by a factor of 10⁴ during the HF pressure change in the range of 0–200 Torr. A model is proposed to describe the experimental results obtained.

Theoretical studies of the implementation of possible types of stationary states for a countercurrent liquid–liquid plug reactor are carried out. States such as a stable node and focus, and an unstable focus with a stable limit cycle (oscillations) are found. Using these data, the evolution of stationary states with continuous changes in the external control parameters is studied. When the relationship between the flow rates of the phases changes, a structure of stationary states, which can be realized both at the entrance and exit of the dispersion medium, is found.

Hybrid nanosystems based on iron oxide nanoparticles (IONPs) and human serum albumin (HSA) were synthesized. The size and composition of HSA@IONP nanosystems were characterized using UV/visible spectrophotometry (particularly, using the Bradford protein assay), dynamic light scattering (DLS), and electron magnetic resonance. The dark and photoinduced cytotoxicity of these systems were studied using methylene blue (MB) as a model photosensitizer (PS). The analysis of the survival of cultured tumor cells of the human breast adenocarcinoma line MCF-7 showed an increase in photoinduced cytotoxicity upon excitation of the PS accumulated by cells due to delivery via the nanosystems, compared to the free PS in equivalent concentrations. HSA@IONPs are discussed as a promising platform for the targeted delivery of a PS to tumor cells.

The phase behavior of mixtures of linear flexible polymers and V-shaped liquid crystals (LCs) is inspected using a combination of the Flory–Huggins (FH) theory of polymer solutions and the Landau–de Gennes theory of nematic ordering. The influence of the architecture of V-shaped molecules on the system’s phase diagrams is examined.

A highly sensitive method for the quantitative rapid determination of cardiac troponin I (cTnI) in human serum is developed. The method is based on an enzyme-linked immunosorbent assay (ELISA) on magnetic particles in the volume of a blood serum sample, which can significantly reduce the diffusion limitations typical for the traditional ELISA. Alkaline phosphatase which is a high-performance enzyme was used as an enzyme label. The enzyme demonstrated a catalytic efficiency of (k_cat/K_m) = 26 500 L/(s mM) in combination with the substrate 1-naphtyl phosphate monosodium salt. The planar electrochemical sensors manufactured by industrial screen-printing technology are used for signal detection. The detection is carried out in differential pulse voltammetry mode. The calculated limit of detection by the enzymatic reaction product is 0.075 μM which significantly exceeds the sensitivity of colorimetric methods. The combination of the proposed methods and approaches makes it possible to obtain a quantitative analysis for cTnI in human serum within 20 min with an estimated detection limit of 7 pg/mL and the upper reference limit of the normal analyte concentration (99th percentile) of 22 pg/mL.

This paper presents the results of a study of spectrum-induced myopia using a model of quail maturation. Using acoustic microscopy methods in the native state, the geometric dimensions of the structural elements of the eye involved in focusing the optical system are determined, and the patterns of their changes as the body grows and during emmetropization are identified. Particular emphasis is placed on the composition, structure, and mechanical properties of the sclera as the main supporting tissue of the eye, responsible for its shape and size.