Norms of Multipliers and Best Approximations of Holomorphic Functions of Many Variables

We show that the Lebesgue–Landau constants of linear methods for summation of Taylor series of functions holomorphic in a polydisk and in the unit ball from over triangular domains do not depend on the number m. On the basis of this fact, we find a relation between the complete and partial best approximations of holomorphic functions in a polydisk and in the unit ball from .     

Advanced exact structure searching in large databases of chemical compounds

Efficient recognition of tautomeric compound forms in large corporate or commercially available compound databases is a difficult and labor intensive task. Our data indicate that up to 0.5% of commercially available compound collections for bioscreening contain tautomers. Though in the large registry databases, such as Beilstein and CAS, the tautomers are found in an automated fashion using high-performance computational technologies, their real-time recognition in the nonregistry corporate databases, as a rule, remains problematic. We have developed an effective algorithm for tautomer searching based on the proprietary chemoinformatics platform. This algorithm reduces the compound to a canonical structure. This feature enables rapid, automated computer searching of most of the known tautomeric transformations that occur in databases of organic compounds. Another useful extension of this methodology is related to the ability to effectively search for different forms of compounds that contain ionic and semipolar bonds. The computations are performed in the Windows environment on a standard personal computer, a very useful feature. The practical application of the proposed methodology is illustrated by several examples of successful recovery of tautomers and different forms of ionic compounds from real commercially available nonregistry databases.     

Chemical Ionization Methods in Selective Chromatography–Mass Spectrometry of Alkylphosphonic Acid Derivatives

Control over the destruction of chemical weapons requires analyses of various complex samples like water, soils, paint coats, mechanical rubber articles, vegetation, etc. aimed at the detection and determination of toxic substances related to chemical weapons. This paper considers the developed procedures of chromatographic–mass spectrometric analysis with positive- and negative-ion chemical ionization. These procedures eliminate false positive and negative results in determining complex samples containing trace organophosphorus compounds.     

Identification of Vodkas by Ion Chromatography and Gas Chromatography

Vodka samples from various distilleries were analyzed by ion chromatography in combination with gas chromatography for the identification of alcoholic products. It was shown that vodkas of the same name manufactured at the same distillery exhibited relatively stable anion–cation compositions; therefore, the ionic composition of vodka can serve as an identification feature. The use of methanol, 2-propanol, and 1-propanol concentrations, which were determined by gas chromatography, as identification features of vodka enhances the probability of detecting adulterated alcoholic products.     

Retention Time Locking in the Determination of Narcotic Drugs by Chromatography and Chromatography–Mass Spectrometry

The use of retention time locking (RTL) in the development of unified procedures for the detection and quantitative determination of drugs in biological fluids was considered. With consideration for the use of RTL, a chromatographic procedure with flame-ionization and mass-selective detection was developed for the detection and quantitative determination of opiates and their synthetic analogs; phenylalkylamine derivatives; cocaine; ketamine; and other narcotic drugs, their derivatives, and metabolites in urine. The analytical ranges for chromatography–mass spectrometry were 0.05–1000 and 0.005–1000 g/mL under the conditions of total ion current (TIC) scanning and selected ion monitoring (SIM), respectively. With flame-ionization detection (GC–FID), the analytical range was 0.5–1000 g/mL.     

Qualitative Chromatographic–Mass Spectrometric Analysis of Highly Toxic Alkyl Phosphonate and Alkyl Thiophosphonate Derivatives

The main goal of chemical analytical monitoring in the destruction of chemical weapons is to identify highly toxic compounds of similar structures in long homologues series. The difficulties with the identification are due to a wide range of possible structures of such compounds with similar mass-spectral patterns. This necessitates the development of special approaches to the interpretation of analytical data. The paper presents the data of experimental studies of specific features of chromatographic–mass spectrometric behavior of 150 substances of the specified classes. The account of these data can improve the reliability of the identification.     

Combination of the SNH/aza-Diels–Alder Reactions as Effective Synthetic Approach to 8-Hydroxy(methoxy)-Substituted 2-[6-(1-Methylindol-3-yl)pyridin-2-yl]quinoline Ligands/Fluorophores

Russian Journal of General Chemistry - 8-Hydroxy(methoxy)-substituted 2-[6-(1-methylindol-3-yl)pyridin-2-yl]quinoline ligands were synthesized by means of combination of SNH reaction between...     

Synthesis of 5-[(Thiophen-3-yl)amino]-1,2,4-triazines

Russian Journal of Organic Chemistry - Methyl 3-(3,6-diaryl-1,2,4-triazin-5-ylamino)thiophen-2-carboxylates were synthesized in 70–75% yield by solvent-free reaction of methyl...     

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.