Synthesis of oligomeric boron-containing phosphopolyols

Transesterification of phosphorus-containing esters of boric acid with glycols leads to formation of polyols, the promising antipyrenes. Structure and reactivity of the oligomeric boron-containing polyols are studied.     

Synthesis oftert-butyl substituted polymethine 1-benzothiopyrylium dyestuffs

A series of polymethine thiopyrylium dyestuffs of symmetrical and unsymmetrical structure, containing one to fourtert-butyl groups, has been synthesized from 6-tert-butyl-2-(p-tert-butylphenyl)-4-methyl-, 4,6-di(tert-butyl)-2-methyl-, and 6-tert-butyl-2,4-dimethyl-1-benzothiopyrylium perchlorates.     

Rearrangement of the bow shock shape using a “hot spike”

A method of possible diagnostics of supersonic flows around a blunt body and its aerodynamic characteristics by means of a thin channel of reduced density emerging in front of the bow shock wave is discussed. The channel was placed parallel to the body axis or inclined to it. Under the conditions of initially uniform pressure the temperature in the channel (the hot spike) is higher than that of the environment. A thin hot spike, which as its limit is infinitely thin, results in the formation of a precursory disturbance in front of the bow shock wave. The length of the precursor is comparable with the characteristic length, that is, the cross section of the blunt body. The hot spike when localized parallel to the body axis and not in line with it yields turning and deviating moments, a lift force was generated even for a symmetric blunt body. Possible applications of this effect are, for example, a change of the trajectory of a small asteroid by means of using the hot spike.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Vortex flows induced by interaction of a shock wave with thin regions of finite length and reduced density

A theoretical and experimental investigation has been made of the dynamics of the vortex flow induced by thin regions of reduced density in precursors that develop ahead of shock fronts during the propagation of shock waves through a channel and after its end up to the stage of restoration of the undisturbed flow. The satisfactory agreement between the experimental and calculated data indicates that the numerical analysis of the process in the framework of the Euler equations is valid.Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 149–153, May–June, 1993.     

Differences in reactivity of N-acetyl- and N,N-diacetylsialyl chlorides caused by their different supramolecular organization in solutions

O-Sialylation of a substituted indolin-3-one under phase-transfer catalysis conditions, which does not occur when N-acetylsialyl chloride is used, proceeds with N,N-diacetylsialyl chloride as the glycosyl donor. A study using dynamic light scattering of solutions of both sialyl chlorides under conditions close to the conditions used for glycosylation showed a difference in the correlation radii of light scattering particles in such solutions. This suggests that the introduction of an additional N-acetyl group into the sialyl chloride significantly alters the structure of the supramers of glycosyl donor, which apparently have an increased accessibility of individual molecules for the attack by a nucleophile, which increases its reactivity.

     

The magnetic isotope effect as a tool for apoptosis modulation in leukemic cells

Lymphocytes from healthy donors and leukemic cells of patients with acute B-lymphoblastic leukemia (BALL-1) and acute myeloid leukemia were exposed to nanoparticles bearing magnetic (Zn-67) and nonmagnetic (total isotope pool) nuclei of zinc. The values of the corresponding magnetic isotope effects determined as the ratio of LD₅₀ magnitudes of preparations with magnetic and nonmagnetic zinc isotopes were 0, 3.5, and 1.5. Morphological studies using confocal and fluorescence microscopy showed apoptotic death of cells with the preparations; as well, there was an increase in the cell aggregation and better aggregation of nanoparticles in the case of ⁶⁷Zn-NP, which resulted in a decrease of cytotoxicity. However the magnetic isotope effect was observed even in the case of aggregation.     

Binuclear heterometallic {M-Ln} pivalate complexes (M = Co, Ni, Cu; Ln = Sm, Gd): synthesis, structure, and thermolysis

Binuclear heterometallic complexes (??²-bpy)CoLn(Piv)₅(H₂O), (??²-bpy)NiLn(Piv)₅(H₂O), and (??²-bpy)CuLn(Piv)₅(HPiv) (Ln = Sm or Gd, Piv- is the pivalate anion) were synthesized. A comparative study of the structural characteristics and the thermolysis of the resulting compounds was performed.     

Structure, 1H and 13C NMR spectra, and biological activity of the antibiotic INA-1278 related to irumamycin and produced by the experimental Streptomyces sp. strain No. 1278

The screening for novel antibiotic producers by selection methods revealed the Streptomyces sp. strain No. 1278 producing the antibiotic INA-1278, which exhibits antimicrobial and antifungal activities. This compound was isolated from the liquid culture by extraction with organic solvents and purified by chromatographic methods. The structure of this antibiotic was studied by mass spectrometry and ¹H and ¹³C NMR spectroscopy. An analysis of the results of the investigation indicate that the compound INA-1278 is structurally related to the antibiotic irumamycin, which has been studied earlier. However, the novel antibiotic may differ from irumamycin in the configurations of some asymmetric centers, which were not established at the present stage of our research.