Magnetic and thermal properties of single-crystal NdFe<Subscript>3</Subscript>(BO<Subscript>3</Subscript>)<Subscript>4</Subscript>

The neodymium ferroborate NdFe₃(BO₃)₄ undergoes an antiferromagnetic transition at T _N = 30 K, which manifests itself as a λ-type anomaly in the temperature dependence of the specific heat C and as inflection points in the temperature dependences of the magnetic susceptibility χ measured at various directions of an applied magnetic field with respect to the crystallographic axes of the sample. Magnetic ordering occurs only in the subsystem of Fe³⁺ ions, whereas the subsystem of Nd³⁺ ions remains polarized by the magnetic field of the iron subsystem. A change in the population of the levels of the ground Kramers doublet of neodymium ions manifests itself as Schottky-type anomalies in the C(T) and χ(T) dependences at low temperatures. At low temperatures, the magnetic properties of single-crystal NdFe₃(BO₃)₄ are substantially anisotropic, which is determined by the anisotropic contribution of the rare-earth subsystem to the magnetization. The experimental data obtained are used to propose a model for the magnetic structure of NdFe₃(BO₃)₄.     

Kinetics of oxygen absorption by aqueous electrolyte solutions in the presence of microencapsulated quartz particles activating the mass transfer in the liquid phase

Effect of the ion composition of aqueous solutions on the oxygen absorption kinetics in a system constituted by a gas (air) and a liquid (aqueous solution) in the presence of microencapsulated quartz particles activating the mass transfer in the liquid phase was studied. It was found that ions with positive hydration cause a substantial decrease in the O₂ mass-transfer enhancement factor, whereas ions with negative hydration lead to its increase under the same conditions. It is shown that the effect of ions on the rate of oxygen absorption by aqueous electrolyte solutions can be prognosticated on the basis of data on the influence of these ions on the structure and viscosity of water. The results of the study can serve as a basis for varying the rate of heterogeneous reactions in gas-liquid systems, whose rate is limited by the mass transfer of oxygen into aqueous media, by purposeful control over their ion composition.     

Properties of solutions of methyl cellulose blends with poly(N-methyl-N-vinylacetamide) in water and dimethylacetamide and of the related composite films

The rheological properties of dilute and moderately concentrated solutions of methyl cellulose blends with poly(N-methyl-N-vinylacetamide) in water and dimethylacetamide are studied, and the stressstrain characteristics of the composite films based on these blends are estimated. DSC, X-ray diffraction, and thermomechanical analysis are used to investigate the structural organization of composite films, to estimate the temperatures of relaxation transitions, and to determine the composition ranges in which the polymers are compatible and form mixed structures.     

Chitosan-dextran branched copolymers: Synthesis and properties

Chitosan-dextran branched copolymers have been synthesized, and the rheological properties of their aqueous acetic acid solutions have been studied. On the basis of the data of FTIR spectroscopy, the formation of chemical bonds between chitosan and dextran at the nitrogen atom has been confirmed. With the use of dynamic mechanical analysis and differential scanning calorimetry, the temperatures of relaxation transitions in the resulting branched copolymers have been determined. It is shown that, along with the formation of a branched copolymer, the chemical crosslinking of chitosan macrochains can occur. Mechanical properties of films formed from solutions of the obtained polymers have been studied.     

Synthesis of Acyl Derivatives of Prolyl-leucinamides

Russian Journal of Organic Chemistry - Synthetic routes to prolyl-leucinamide, N-benzyl(prolyl)leucinamide, and N-(prolyl-leucyl)morpholine were proposed. Treatment of these compounds with benzoyl...     

Micro- and Nanosecond Pulses Used in Doxorubicin Electrochemotherapy in Human Breast and Colon Cancer Cells with Drug Resistance

(1) Background: Pulsed electric field (PEF) techniques are commonly used to support the delivery of various molecules. A PEF seems a promising method for low permeability drugs or when cells demonstrate therapy resistance and the cell membrane becomes an impermeable barrier. (2) Methods: In this study, we have used doxorubicin-resistant and sensitive models of human breast cancer (MCF-7/DX, MCF-7/WT) and colon cancer cells (LoVo, LoVoDX). The study aimed to investigate the susceptibility of the cells to doxorubicin (DOX) and electric fields in the 20–900 ns pulse duration range. The viability assay was utilized to evaluate the PEF protocols’ efficacy. Cell confluency and reduced glutathione were measured after PEF protocols. (3) Results: The obtained results showed that PEFs significantly supported doxorubicin delivery and cytotoxicity after 48 and 72 h. The 60 kV/cm ultrashort pulses × 20 ns × 400 had the most significant cytotoxic anticancer effect. The increase in DOX concentration provokes a decrease in cell viability, affected cell confluency, and reduced GSSH when combined with the ESOPE (European Standard Operating Procedures of Electrochemotherapy) protocol. Additionally, reactive oxygen species after PEF and PEF-DOX were detected. (4) Conclusions: Ultrashort electric pulses with low DOX content or ESOPE with higher DOX content seem the most promising in colon and breast cancer treatment.     

In Vitro Antineoplastic and Antiviral Activity and In Vivo Toxicity of Geum urbanum L. Extracts

This study evaluated the in vitro antineoplastic and antiviral potential and in vivo toxicity of twelve extracts with different polarity obtained from the herbaceous perennial plant Geum urbanum L. (Rosaceae). In vitro cytotoxicity was determined by ISO 10993-5/2009 on bladder cancer, (T-24 and BC-3C), liver carcinoma (HEP-G2) and normal embryonic kidney (HEK-293) cell lines. The antineoplastic activity was elucidated through assays of cell clonogenicity, apoptosis induction, nuclear factor kappa B p65 (NFκB p65) activation and total glutathione levels. Neutral red uptake study was applied for antiviral activity. The most promising G. urbanum extract was analyzed by UHPLC–HRMS. The acute in vivo toxicity analysis was carried out following OEDC 423. The ethyl acetate extract of aerial parts (EtOAc-AP) exhibited the strongest antineoplastic activity on bladder cancer cell lines (IC₅₀ = 21.33–25.28 µg/mL) by inducing apoptosis and inhibiting NFκB p65 and cell clonogenicity. EtOAc and n-butanol extracts showed moderate antiviral activity against human adenovirus type 5 and human simplex virus type I. Seventy four secondary metabolites (gallic and ellagic acid derivatives, phenolic acids, flavonoids, etc.) were identified in EtOAc-AP by UHPLC–HRMS. This extract induced no signs of acute toxicity in liver and kidney specimens of H-albino mice in doses up to 210 mg/kg. In conclusion, our study contributes substantially to the detailed pharmacological characterization of G. urbanum, thus helping the development of health-promoting phytopreparations.     

Phase Composition and Thin Structure of Steel Surface after Plasma Electrolytic Carbonitriding

Russian Physics Journal - Using the transmission electron microscopy of thin foils the paper studies the phase composition and fine structure of 0.18С–1Cr–3Ni–1Mo–Fe...     

Problems of solubility of hydrolysis lignin

Interaction of hydrolysis lignin with polyacrylonitrile in water-dimethyl sulfoxide solution in the presence of an activator was studied, and the properties of the products were examined.