The local geometry of Carnot manifolds at singular points

In this paper we study the local geometry of Carnot manifolds in a neighborhood of a singular point in the case when horizontal vector fields are 2M-smooth. Here M is the depth of a Carnot manifold.     

Gas chromatography determination of trace of biomarkers of mustard agent and some organophosphoric toxic agents in urine

A procedure has been developed for the determination of thioglycol, 1,1′-sulfonyl-bis[2-(methylsulfonyl)-ethane], 1-methylsulfonyl-2-[2-(methylthio)ethylsulfonyl]ethane (biomarkers of mustard agent) and methylphosphonic acid, O-ethylmethylphosphonic acid, O-isopropylmethylphosphonic acid, and O-pinacolyl methylphosphonic acid (biomarkers of organophosphoric toxic agents) in urine. The procedure includes the recovery of components by liquid extraction, derivatization, separation by gas-liquid chromatography, and detection by flame-photometric and mass spectral detectors. The procedure has been applied to the analysis of samples of artificial urine by the standard addition method.     

Effect of a lanthanide ion on the micellation and self-organization of lyotropic liquid crystal systems

Lanthanide-containing lyotropic liquidcrystalline systems were synthesized and their phase behavior, as well as the micellar behavior of aqueous solutions of decaethylene glycol monodecyl ether in the absence and presence of a lanthanide ion, were studied. Tensimetry and conductometry were used to determine the critical micellation concentration, and the values obtained by these methods were found to be in close agreement with each other. Polarization microscopy observations showed that, in concentrated aqueous solutions, ordered lyotropic mesophases arise. The parameters of the phase transitions in the systems under study were determined. The mesophase obtained was demonstrated to have a 2D hexagonal supramolecular structure.     

Quasi-stationary stefan problem with values on the front depending on its geometry

The problem presented below is a singular-limit problem of the extension of the Cahn-Hilliard model obtained via introducing the asymmetry of the surface tension tensor under one of the truncations (approximations) of the inner energy [2, 5–8, 10, 12, 13].     

Crystal engineering as a scientific basis for modification of physicochemical properties of bioflavonoids

Flavonoids are of interest for pharmacy and medicinal chemistry due to a wide range of biological activities. The major goal for the design of new drugs based on flavonoids is to increase bioavailability of pharmaceutical substances. Crystal engineering is a useful tool for this purpose. This review presents a systematic analysis of the publications on crystal engineering of flavonoids published between 2000 and 2019. The data on objects, methods of supramolecular synthesis, analysis, and preclinical studies of its products are summarized. The trends in crystal engineering of flavonoids are considered and promising areas for further research are identified. The review may be of interest for researchers engaged in the design of drugs with low bioavailability, including bioflavonoids.

     

Topological classification of integrable geodesic flows on orientable two-dimensional Riemannian manifolds with additional integral depending on momenta linearly or quadratically

Moscow State University. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 27, No. 3, pp. 42–56, July–September, 1993.     

Organogels versus Hydrogels: Advantages,Challenges, and Applications

Organogels are an important class of gels, and are comparable to hydrogels owing to their properties as liquid-infused soft materials. Despite the extensive choice of liquid media and compatible networks that can provide a broader range of properties, relatively few studies are reported in this area. This review presents the applicability of organogels concerning their choice of components, unique properties, and applications. Their distinctive features compared to other gels are discussed, including multi-stimuli responses, affinity to a broad range of substances, thermal and environmental stability, electronic and ionic conductivity, and actuation. The active role of solvents is highlighted in the versatility of organogel properties. To differentiate between organogels and other gels, these are classified as gels filled with different organic liquids, including highly polar organic solvents and binary solvent systems. Most promising applications of organogels as sophisticated multifunctional materials are discussed in light of their unique features.     

Epoxidation of cycloolefins with hydrogen peroxide in the presence of heteropoly acids combined with phase transfer catalyst

Oxidation of cycloolefins (cyclohexene, cyclooctene, and cyclododecene) with a 30% solution of hydrogen peroxide at 65 °C in the presence of heteropoly acids (HPA) H₃PW_12–x Mo _x O₄₀ (x = 0—12), which are precursors of active peroxo complexes, and phase transfer catalysts Q⁺Cl^–, where Q⁺ is the quaternary ammonium cation containing C₄—C₁₈ alkyl groups or [C₅H₅NC₁₆H₃₃]⁺, was studied. The catalytic activity decreases in the HPA series: H₃PW₁₂O₄₀ > H₃PW₉Mo₃O₄₀ > H₃PW₆Mo₆O₄₀ > H₃PW₃Mo₉O₄₀ > H₃PMo₁₂O₄₀. The state of the H₃PW₁₂O₄₀—I₂I₂ system was studied using UV, IR, and ³¹P NMR spectroscopies with variation of the [H₂O₂] : [HPA] ratio from 2 to 200 during cyclohexene epoxidation. Despite different catalytic precursors, the reaction proceeds through the same peroxo complex.     

Calix[4]arene N-chalconeamides: synthesis and influence on Mg2+,ATP-dependent Ca2+ accumulation in the smooth muscle subcellular structures

The cone-shaped calixarene N-chalconeamides were synthesized by the reaction of calix[4]arene carboxylic acids or acid chlorides with aminochalcones. It was found, that calixarene chalconeamides influence the Mg²⁺, ATP-dependent Ca²⁺ accumulation in mitochondria and sarcoplasmatic reticulum of the smooth muscle cells.     

Chemical Variability and Pharmacological Potential of Propolis as a Source for the Development of New Pharmaceutical Products

This review aims to analyze propolis as a potential raw material for the development and manufacture of new health-promoting products. Many scientific publications were retrieved from the Scopus, PubMed, and Google Scholar databases via searching the word "propolis". The different extraction procedures, key biologically active compounds, biological properties, and therapeutic potential of propolis were analyzed. It was concluded that propolis possesses a variety of biological properties because of a very complex chemical composition that mainly depends on the plant species visited by bees and species of bees. Numerous studies found versatile pharmacological activities of propolis: antimicrobial, antifungal, antiviral, antioxidant, anticancer, anti-inflammatory, immunomodulatory, etc. In this review, the composition and biological activities of propolis are presented from a point of view of the origin and standardization of propolis for the purpose of the development of new pharmaceutical products on its base. It was revealed that some types of propolis, especially European propolis, contain flavonoids and phenolic acids, which could be markers for the standardization and quality evaluation of propolis and its preparations. One more focus of this paper was the overview of microorganisms’ sensitivity to propolis for further development of antimicrobial and antioxidant products for the treatment of various infectious diseases with an emphasis on the illnesses of the oral cavity. It was established that the antimicrobial activity of different types of propolis is quite significant, especially to Gram-negative bacteria and lipophilic viruses. The present study could be also of interest to the pharmaceutical industry as a review for the appropriate design of standardized propolis preparations such as mouthwashes, toothpastes, oral drops, sprays, creams, ointments, suppositories, tablets, and capsules, etc. Moreover, propolis could be regarded as a source for the isolation of biologically active substances. Furthermore, this review can facilitate partially overcoming the problem of the standardization of propolis preparations, which is a principal obstacle to the broader use of propolis in the pharmaceutical industry. Finally, this study could be of interest in the area of the food industry for the development of nutritionally well-balanced products. The results of this review indicate that propolis deserves to be better studied for its promising therapeutic effects from the point of view of the connection of its chemical composition with the locality of its collection, vegetation, appropriate extraction methods, and standardization.