Extraction of U(VI) from Perchlorate Solutions with Diantipyrylmethane Derivatives

Extraction of U(VI) from perchlorate solutions with diantipyrylmethane derivatives in chloroform and dichloroethane is studied. The composition of extractable complexes is [UO₂L₂](ClO₄)₂. The extraction constants are estimated. The maximal extractive power is shown by diantipyrylmethane in dichloroethane. Introduction of substituents at the methylene carbon of the extractant molecule makes the extraction worse.     

AICAR Protects Vascular Endothelial Cells from Oxidative Injury Induced by the Long-Term Palmitate Excess

Hyperlipidemia manifested by high blood levels of free fatty acids (FFA) and lipoprotein triglycerides is critical for the progression of type 2 diabetes (T2D) and its cardiovascular complications via vascular endothelial dysfunction. However, attempts to assess high FFA effects in endothelial culture often result in early cell apoptosis that poorly recapitulates a much slower pace of vascular deterioration in vivo and does not provide for the longer-term studies of endothelial lipotoxicity in vitro. Here, we report that palmitate (PA), a typical FFA, does not impair, by itself, endothelial barrier and insulin signaling in human umbilical vein endothelial cells (HUVEC), but increases NO release, reactive oxygen species (ROS) generation, and protein labeling by malondialdehyde (MDA) hallmarking oxidative stress and increased lipid peroxidation. This PA-induced stress eventually resulted in the loss of cell viability coincident with loss of insulin signaling. Supplementation with 5-aminoimidazole-4-carboxamide-riboside (AICAR) increased endothelial AMP-activated protein kinase (AMPK) activity, supported insulin signaling, and prevented the PA-induced increases in NO, ROS, and MDA, thus allowing to maintain HUVEC viability and barrier, and providing the means to study the long-term effects of high FFA levels in endothelial cultures. An upgraded cell-based model reproduces FFA-induced insulin resistance by demonstrating decreased NO production by vascular endothelium.     

Effectiveness of dietary non-starch polysaccharides in experimental toxic hepatitis

The efficiency of some polysaccharides was investigated in mice with an experimental toxic hepatitis. Hepatitis was induced by the oral administration of 10% solution CCl4 in olive oil at a dosage of 3 ml/kg body weight every day during 7 days. After that tested substances were administrated every day 30-40 min before a feeding at a dosage of 150 mg/kg body weight during 14-21 days. Results showed that a calcium alginate, two low-methoxyl pectins (one with the degree of esterification about 50% and other with the degree of esterification less 5%), fucoidan, and chitozan, but not lambda-carrageenan and kappa-carrageenan, have beneficial affects on liver total lipid, glycogen, malondialdehyde, and diene conjugates as well as on blood total lipid and alanine aminotransferase activity in animals with experimental toxic hepatitis.     

High-Sensitivity Photodetector Based on Atomically Thin MoS<Subscript>2</Subscript>

A design for a high-sensitivity photodetector with a single layer of MoS₂ transition-metal dichalcogenide used as the basic functional element is proposed and the process of its fabrication is presented step by step. Quality evaluation and the selection of functional MoS₂ flakes is based on the results of combined optical characterization. The main operating characteristics of the fabricated device are investigated and a photosensitivity of 1.4 mA/W is demonstrated. A difference of this device in comparison with existing analogues is its high photosensitivity at low operating voltages (in the range of ±3 V).     

Extraction of U(VI) with antipyrine in the presence of aminone pyrazolone dye

Extraction of U(VI) with a solution of antipyrine in chloroform in the presence of aminone [a pyrazolone dye, di(p-dimethylaminophenyl)(1-p-sulfophenyl-3-methylpyrazol-5-on-4-yl)carbinol ammonium salt] was studied. A procedure was suggested for extraction-chromatographic determination of 2–30 μg of U(VI). The extractable complex has the composition UO₂L₂A₂; ?₄₇₀ = 4.5 × 10⁴. Th, Sc, In, Fe(III), REE, Zr, Mo(VI), and some other elements in a 500-fold molar excess do not interfere with the determination.     

Investigation of Bemethyl Biotransformation Pathways by Combination of LC–MS/HRMS and In Silico Methods

Bemethyl is an actoprotector, an antihypoxant, and a moderate psychostimulant. Even though the therapeutic effectiveness of bemethyl is well documented, there is a gap in knowledge regarding its metabolic products and their quantitative and qualitative characteristics. Since 2018, bemethyl is included to the Monitoring Program of the World Anti-Doping Agency, which highlights the challenge of identifying its urinary metabolites. The objective of the study was to investigate the biotransformation pathways of bemethyl using a combination of liquid chromatography-high-resolution mass spectrometry and in silico studies. Metabolites were analyzed in a 24 h rat urine collected after oral administration of bemethyl at a single dose of 330 mg/kg. The urine samples were prepared for analysis by a procedure developed in the present work and analyzed by high performance liquid chromatography–tandem mass spectrometry. For the first time, nine metabolites of bemethyl with six molecular formulas were identified in rat urine. The most abundant metabolite was a benzimidazole–acetylcysteine conjugate; this biotransformation pathway is associated with the detoxification of xenobiotics. The BioTransformer and GLORY computational tools were used to predict bemethyl metabolites in silico. The molecular docking of bemethyl and its derivatives to the binding site of glutathione S-transferase has revealed the mechanism of bemethyl conjugation with glutathione. The findings will help to understand the pharmacokinetics and pharmacodynamics of actoprotectors and to improve antihypoxant and adaptogenic therapy.     

Synthesis and biological activity of silyl- and germylsubstituted trifluroacetylfurans

A series of silyl, germyl and alkyl substituted trifluoroacetylfurans has been synthesized under Friedel-Crafts electrophilic acylation conditions. Biological investigations have demonstrated that germyl derivatives of trifluoroacetylfuran are more toxic than the silicon analogues. 5-Triethylgermyl-2- trifluoroacetylfuran was the most toxic compound (CD(nabla), 11.2 mg kg(-1), i.p. for white mice), 200 times more toxic than the silicon analogue. 5-t-Butyl- and 5-trimethylsilyl-2-trifluroacetylfuran prolong the duration of ethanol anaesthesia by 220 and 140%. 5-Triethylgermyl-2-trifluroacetylfuran exibited high anesthetic activity in hexobarbital test (prolonged the duration by 137%). Some of compounds influenced muscle tone and locomotor coordination parameters. 5-Triethylgermyl-2-trifluomacetylfuran exibited analgesic activity (D(nabla), 0.9 mg k}(-infinity)).     

On canonical transformations of gravitational variables in extended phase space

In the recent years, a certain attention was attracted to the statement that Hamiltonian formulations of general relativity (GR), in which different parametrizations of gravitational variables were used, may not be related by a canonical transformation. An example was given by Dirac’s Hamiltonian formulation and that of Arnowitt-Deser-Misner. It might be indicative of a non-equivalence of these formulations and the original (Lagrangian) formulation of GR. The problem is believed to be of importance since many authors make use of various representations of the gravitational field as a starting point in searching for a way to reconcile the theory of gravity with quantum principles. It can be shown that the above-mentioned conclusion on non-equivalence of different Hamiltonian formulations is based on a consideration of canonical transformations in the phase space of physical degrees of freedom only, while the transformations also involve the gauge degrees of freedom. We shall give a clear proof that the Hamiltonian formulations corresponding to different parametrizations of the gravitational variables are related by canonical transformations in extended phase space embracing the gauge degrees of freedom on equal footing with the physical ones. It will be demonstrated for the full gravitational theory in a wide enough class of parametrizations and gauge conditions.     

Edge effects in second-harmonic generation in nanoscale layers of transition-metal dichalcogenides

Semiconductors - The results of studying the optical properties of nanoscale single crystals of MoS2:Cl2 and WS2:Br2 semiconductor compounds are presented. In microscopic images obtained at the...