Preparation and Properties of Frost-Resistant Materials Based on Compounds of Oligoether Urethane Epoxides and Diglycidyl Urethane

A procedure was suggested for preparing epoxy ether urethane oligomers via intermediate oligodiisocyanates with increased content of the starting 2,4-toluene diisocyanate. The procedure allows preparation of epoxy-containing oligomers with appreciable fraction of low-molecular-mass diglycidyl urethane. The presence of diglycidyl urethane in the binder enhances not only the adhesion but also the strength of the cured material without significantly affecting the glass transition point of the binder. Elastic materials prepared by curing the compounds studied with cylcoaliphatic amines exhibit enhanced levels of strength and low-temperature elasticity.

     

Local solvability of the capillary problem

This paper studies conditions for local (in time) solvability of a qualitatively new singularllimit problem, the free (unknown) boundary problem appearing recently. In fact, there are not so many different free boundary problems, which corresponds to not so large a variety of principally different phase transitions of the first and second kinds. Therefore, the appearance of principally new problems elicits interest. This paper studies structural features of a certain problem on the basis of a certain method developed previously, precisely, the localization method [1, 3, 9].     

Terpenoid Hydrazones as Biomembrane Penetration Enhancers: FT-IR Spectroscopy and Fluorescence Probe Studies

Hydrazones based on mono- and bicyclic terpenoids (verbenone, menthone and carvone) have been investigated in vitro as potential biomembrane penetration enhancers. In this regard, liposomes composed of lecithin or cardiolipin as phospholipid phase components with incorporated fluorescence probes have been prepared using the thin-film ultrasonic dispersion method. The mean particle size of the obtained liposomes, established using laser diffraction, was found to be 583 ± 0.95 nm, allowing us to categorize them as multilamellar vesicles (MLVs) according to their morphology. Pursuant to fluorescence analysis, we may assume a reduction in microviscosity and, consequently, a decrease in the packing density of lecithin and cardiolipin lipids to be the major mechanism of action for terpenoid hydrazones 1–15. In order to determine the molecular organization of the lipid matrix, lipids were isolated from rat strata cornea (SCs) and their interaction with tested compounds was studied by means of Fourier transform infrared spectroscopy. FT-IR examination suggested that these hydrazones fluidized the SC lipids via the disruption of the hydrogen-bonded network formed by polar groups of SC constituents. The relationship between the structure of terpenoid hydrazones and their ability to enhance biomembrane penetration is discussed.     

Understanding the solubilization of Ca acetylide with a new computational model for ionic pairs

The unique reactivity of the acetylenic unit in DMSO gives rise to ubiquitous synthetic methods. We theoretically consider CaC₂ solubility and protolysis in DMSO and formulate a strategy for CaC₂ activation in solution-phase chemical transformations. For this, we use a new strategy for the modeling of ionic compounds in strongly coordinating solvents combining Born–Oppenheimer molecular dynamics with the DFTB3-D3(BJ) Hamiltonian and static DFT computations at the PBE0-D3(BJ)/pob-TZVP-gCP level. We modeled the thermodynamics of CaC₂ protolysis under ambient conditions, taking into account its known heterogeneity and considering three polymorphs of CaC₂. We give a theoretical basis for the existence of the elusive intermediate HC C–Ca–OH and show that CaC₂ insolubility in DMSO is of thermodynamic nature. We confirm the unique role of water and specific properties of DMSO in CaC₂ activation and explain how the activation is realized. The proposed strategy for the utilization of CaC₂ in sustainable organic synthesis is outlined.

Constructing the carbon framework from a carbon-neutral source: a new computational model for ionic pairs in solution based on DFTB MD and DFT helps to propose a strategy for sustainable organic transformations with solid CaC₂.     

Separate determination of microquantities of iprite and lewisite in bituminous masses by gas chromatography

A procedure is developed for the separate determination of microquantities of iprite (2,2′-dichlorodiethylsulfide) and α-lewisite (2-chlorovinyldichloroarsine) in bituminous masses formed in the bitumenation of iprite-lewisite crude mixtures in objects of the destruction of chemical weapons. The concentration range is (2–20) × 10⁻⁴%.     

Synthesis of 2,3′,4′-tricyanobiphenyl derivatives and tetraphenylphthalocyanines based thereon

The nitration of 2,3′,4′-tricyanobiphenyl with subsequent transformations of the obtained product provided 4-X-2,3′,4′-tricyanobiphenyls (X = NO₂, NH₂, NHCOCH₃, Br, I). The condensation of the initial biphenyl or its 4-X-derivatives (X = NO₂, NHCOCH₃, Br, I) in the presence of zinc acetate afforded the corresponding zinc complexes of tetra(4-X-2-cyanophenyl)phthalocyanines.     

Tangent cone to a regular quasimetric Carnot-Carathéodory space

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