Frost-Resistant Polyurethane-Urea Materials Based on Oligoethers

Physicomechanical behavior of cross-linked segmented polyester urethane ureas with poly(tetramethylene oxide) segments of varied molecular mass, plasticized with di-(2-ethylhexyl) cebacate, was considered. Data on how the structure of flexible and rigid segments affects the physicomechanical properties of the plasticized material, including those at low temperatures, are presented. Ways were determined for obtaining the optimal hybrid structure of the polymers under study for developing materials with enhanced frost resistance.     

Approximation of Bounded Holomorphic and Harmonic Functions by Fejér Means

Ukrainian Mathematical Journal - We compute the exact values of the least upper bounds on the classes of bounded holomorphic and harmonic functions in a unit disk for the remainders in a...     

Relationship between superconducting transition temperature and crystal-structure parameters of ceramics Tl2Ba2CuO6±x prepared by high-pressure cold pressing

The relationship between the superconducting transition temperature T _c and the crystal-structure parameters of high-temperature superconducting ceramic samples of the Tl2201 phase, which were prepared using high-pressure cold pressing, has been determined. The cold pressing under high pressure has been shown to lead to elongation of the Ba-Ba distances and a decrease in the hole concentration in thallium-containing high-temperature superconducting samples. The planar Cu-O1_plan distances and the structural distortion of the CuO₂ layers were found to have the greatest effect on the T _c value.     

Summation of <Emphasis Type="Italic">p</Emphasis>-Faber series by the Abel–poisson method in the integral metric

We establish conditions on the boundary G \Gamma of a bounded simply connected domain W ì \mathbbC \Omega \subset \mathbb{C} under which the p-Faber series of an arbitrary function from the Smirnov space E_p( W),1 \leqslant p < ￥ {E_p}\left( \Omega \right),1 \leqslant p < \infty , can be summed by the Abel–Poisson method on the boundary of the domain up to the limit values of the function itself in the metric of the space L_p( G) {L_p}\left( \Gamma \right) .     

Determination of growth hormones (β-agonists) in muscle tissue by HPLC with mass spectrometric detection

A procedure is developed for determining 11 β-agonists, that is, hormonal growth promoters for farm animals, using HPLC with mass spectrometric detection. The procedure includes the enzymatic hydrolysis of homogenates of organs and tissues of animals (longissimus muscle, liver, and kidney), precipitation of proteins with perchloric acid, extraction of β-agonists with a mixture of isopropyl alcohol–ethyl acetate (6: 4), purification of the extract by solid phase extraction using a Bond Elut cartridge, HPLC separation in the gradient elution mode, electrospray ionization, and mass spectrometric detection in the multiple reaction monitoring mode. The procedure is certified. The analytical range is 1.0–100.0 μg/kg.     

Procedure for setting control for the turnover of new,potentially hazardous psychoactive substances. Detection of metabolites of a new APINAC psychoactive compound in rat urine by gas and liquid chromatography with mass spectrometry detection

The appearance of a new APINAC compound (AKB-57, ACBL(N)-018, adamantan-1-yl-1-pentyl-1H-indazol-3-carboxylate) in the Russian market of psychoactive drugs led to the need in setting measures of state control over its turnover and in solving the problem of categorizing this compound as a potentially hazardous psychoactive substance. To establish these control measures, it was necessary to determine the appropriate chromatographic–mass spectrometric characteristics and to search for its metabolites for their subsequent automated detection. The structure of an APINAC molecule has significant similarity with the molecules of other synthetic cannabinoids. In this paper, primary information on the metabolism of APINAC in the body of rats is presented. A number of putative metabolites, which are the products of hydrolysis of the initial structure and additional monohydroxylation of these products, carbonylation and carboxylation of the lateral N-pentyl chain of indazole-containing metabolites, were detected in rat urine by liquid chromatography–mass spectrometry in the mode of measurement of exact masses and gas chromatography–mass spectrometry. It was found that the formation of glucuronides is characteristic for 1-adamantol and its monohydroxylated metabolite and for the indazole-containing product of hydrolysis of APINAC. The presented mass spectra and retention characteristics of the detected metabolites can help in the detection of these (or similar) compounds in human urine.     

Efficient Synthesis of Methyl 6-(6-Aryl-1,2,4-triazin3-yl)pyridine-2-carboxylates

Russian Journal of Organic Chemistry - Methyl 6-(6-aryl-1,2,4-triazin-3-yl)pyridine-2-carboxylates were synthesized in up to 70% yield by one-step condensation of substituted...     

Chromatographic study of expert and biological samples containing desomorphine

Expert and biological samples containing desomorphine and concomitant compounds were studied by gas chromatography, chromatography-mass spectrometry, and high-performance liquid chromatography. Some synthetic analogues of desomorphine were identified, and their chromatographic parameters and mass spectra were described. Techniques for the extraction and study of desomorphine and didehydrodesomorphine on a Milichrom A-02 liquid chromatograph were outlined. This information is important for experts in analytical toxicology and criminalistics.     

Phase equilibria in the NaF-LiF-LaF3 system

The NaF-LiF-LaF₃ system was studied by differential thermal and X-ray powder diffraction analyses. In the system, there are two ternary invariant points, a eutectic (580 ± 2°C, 44.0 mol % NaF, 42.0 mol % LiF, 14.0 mol % LaF₃), and a peritectic (595 ± 2°C, 45.0 mol % NaF, 39.0 mol % LiF, 16.0 mol % LaF₃). The ternary peritectic point results from the intersection of the crystallization fields of LiF, LaF₃, and NaLaF₄.