Viscosity of Al-Ni-Co-Nd(Sm) glass-forming melts at high temperatures.

Obtaining amorphous alloys with good mechanical and anticorrosion properties is an important problem of modern condensed matter physics. Since the preparation of amorphous alloys involves casting them from liquid state, information on the properties of the melts is needed. Viscosity is one of the most informative structure-sensitive property of melts. In this paper viscosity of some glass-forming Al-Ni-Co-Nd(Sm) melts with different ratio of transition metals was studied using damped oscillation method in a wide temperature range up to 1550 K. Activation energies of the viscous flow were calculated from the experimental data. The hysteresis of viscosity temperature dependences during heating and subsequent cooling was found. It can be associated with a melt transition to a more homogeneous state. The repeated heating and cooling of the melts without crystallization lead to Arrhenius type of viscosity temperature dependences.

The Wills-Harrison approach to the thermodynamics of binary liquid transition-metal alloys.

In the present study, the Wills-Harrison approach in conjunction with the Bretonnet-Silbert local model pseudopotential is applied to the thermodynamics of binary transition-metal liquid alloys. The calculation is performed in the framework of the variational method of thermodynamic perturbation theory with a hard-sphere reference system. The Vashishta-Singwi exchange-correlation function and the Nozières-Pines exchange-correlation energy are used. The free energy of mixing for liquid Fe-Co alloy is calculated at different compositions near the melting temperature. The agreement with the experimental data is quite satisfactory.

[Glycosphingolipids and antitumor immunity]. / Glikosfingolipidy i protivoopukholevyi immunitet.

Glycosphingolipids are immunogenic components of cell surface whose composition and structure change during the cell transformation. The contemporary state of the question about the influence of glycosphingolipids on specific and non-specific antitumour immunity is considered. The available information about shedding of glycosphingolipids from the tumour cell surface, about the change of the ganglioside content in blood serum of the tumour host and about the effect of glycolipids on immunocompetent cells is analyzed. The results obtained by the authors in studies of the influence of glycosphingolipids on effector cells of the body natural resistance system to tumour are discussed.

[New types of polymerizable phosphatidylcholines, synthesis and properties]. / Novye tipy polimerizuemykh fosfatidilkholinov, sintez i svoistva.

Phosphatidylcholines bearing 11-methacryloylaminoundecanoyl or 12-keto-10-octadecanoyl residues were synthesized. Both phosphatidylcholines are easily polymerized under UV irradiation. The second phospholipid produces liposomes which, after polymerization, acquire an increased stability to deteriorating factors (organic solvents, detergents and human plasma).

[DNA-phospholipid interactions. A study using lipid-specific fluorescent and photoreactive probes]. / DNK-fosfolipidnoe vzaimodeistvie. Issledovanie s pomoshch'iu lipidspetsificheskikh fluorestsentnykh i fotoreaktivnykh zondov.

The interaction of phospholipids with phage T7 DNA was investigated using anthryl-vinyl-labeled and photoactivable phosphatidylcholine and sphingomyelin. Fluorescence polarization studies demonstrated that, in the presence of DNA, the fluorophore mobility is diminished as its distance from the polar head-group is increased. Immobilization of lipid chains is enhanced by Ca2+ ions, the effect being more pronounced for sphingomyelin than for phosphatidylcholine derivatives. On the other hand, phospholipids with a photoactivable group could not be crosslinked to DNA in the DNA-phospholipid complexes, evidencing against the presence of contacts between lipids and DNA.

[Synthesis of fluorescent-labeled cerebrosides]. / Sintez fluorestsentnomechenykh tserebrozidov.

Synthesis of fluorescently labeled cerebrosides--N-[12-(9-anthryl)-11-trans-dodecenoyl]-1 beta-O-galactosylsphingosine and its 9-(3-perylenoyl)nonanoyl analog is described. Both probes are easily inserted in phosphatidylcholine vesicles.

[DNA-phospholipid interaction. 31P-NMR study]. / DNK-fosfolipidnoe vzaimodeistvie. Issledovanie metodom 31P-IaMR.

The phage T7 DNA complexes with various phospholipids (PL) were studied by 31P NMR at PL/nucleotide molar ratio of 2 : 1. Using a phosphatidylcholine thion analogue, the contributions of PL and DNA into the 31P NMR spectrum of the complex were estimated. It was found that PL-DNA interaction results in partial immobilizing ability of PL depends on their structure, increasing in the following row: phosphatidylcholine-phosphatidylethanolamine less than sphingomyelin less than or equal to ternary mixture of these PL. The data obtained are indicative of nonequivalent binding of DNA with various PL species.

[Synthesis of a fluorescently-labeled platelet activating factor]. / Sintez fluorestsentnomechenogo faktora aktivatsii trombotsitov.

The synthesis of fluorescently labelled PAF-acether, 1-alkyl-2-acetyl-sn-glycero-3-phospho-[N-(9-anthrylmethyl)-N, N-dimethylethanolamine] with the label in the choline moiety is described, plasmalogen lysophosphatidylcholine of bovine heart being used as starting material.

[Ganglioside GM3 derivatives and their immunomodulating effect]. / Proizvodnye gangliozida GM3 i ikh immunomoduliruiushchii éffekt.

The derivatives of ganglioside GM3-NeuLacCer. NeuLacSph and NeuAcLacSphAc-were obtained and their immunomodulating properties studied. These substances are shown to inhibit lymphocyte blast-transformation independently of their ceramide structure. On the contrary, the stimulation by the above GM3-derivatives of Con A-induced T-suppressor activity depends significantly on the structure of their ceramide moiety.

[Ferricyanide ion binding sites on the surface of lecithin liposomes]. / Mesta sviazyvaniia ferritsianid-ionov na poverkhnosti letsitinovykh liposome.

Interaction of ferricyanide ions with sonicated lecithin liposomes has been studied by (1)H-NMR. Ferricyanide induced shifts have been shown to change along the choline chain of the lecithin head group. The magnitude of the shift decreases as the distance from the positive end of zwitterionic moiety increases. It is concluded that ferricyanide ions bind to the positive charged ammonium groups of the phospholipid.

[Influence of the structure of lecithins on their interaction with cholesterol]. / Vliianie struktury letsitinov na ikh vzaimodeistvie s kholesterinom

Interaction between cholesterine and phosphatidilcholines (PC) of three types: 1,2-disaturated (SS), 1,2-diunsaturated (UU) and 1-saturated-2-unsaturated (SU) was studied in bilayer vesicular membranes (BVM) by means of NMR-1H spectroscopy. BVM were obtained by sonification of aqueous (D2O) dispersions of individual (PC) and their mixtures. It is found that molecular special specificity of the interaction between PC AND cholesterine is preserved not only during phase division but also in the case when all the phospholipid components of the bilayer are in a liquid crystal state. At low content of cholesterine it favourably interacts with UU-PC, further on with the increase of concentration cholesterine starts to interact with SU- and SS-types of PC. It has been shown that such behaviour of cholesterine can not be explained by means of static models, i.e. by the differences in stability of its stechiometric complexes with CP molecules of different types. An attempt has been undertaken to interpret the selective character of PS-cholesterine interaction proceeding from the suggestion about the anisotropic character of lateral diffusion in the membranes, consisting of various structural types of PC.

[The effect of gangliosides on experimental influenza infection]. / Vliianie gangliozidov na éksperimental'nuiu grippoznuiu infektsiiu.

Experiments in two strains of mice; CBA, susceptible to influenza, and CBAXC57Bl/cXFl, resistant to it, demonstrated stimulation of influenza infection caused by gangliosides. The stimulating effect of gangliosides (GMl, GDla, GTlb) seems to be explained by their insertion into plasma membranes of epithelial cells of the respiratory tract and by an increase, due to it, of the number of superficial virus-specific receptors.

[Ganglioside (GD3) in serum of cancer patients]. / Gangliozid (GD3) v syvorotke krovi rakovykh bol'nykh.

Gangliosides were studied in blood serum of healthy volunteers and of patients with cancer of mammary gland and stomach. Blood serum of the majority of patients with cancer and only 15% of healthy persons were shown to contain ganglioside GD3 which was detected in blood of patients with some other tumors.

[Inhibition of the cytotoxic activity of natural killer cells by glycosphingolipids. Effect of the structure of carbohydrate chains]. / Ingibirovanie tsitotoksicheskoi aktivnosti estestvennykh killerov glikosfingolipidami. Vliianie struktury oligosakharidnykh tsepei.

The ability of various glycosphingolipids to inhibit the cytotoxic activity of natural killer (NK) cells was studied. The inhibitory effect was found to depend on the structure and concentration of the glycosphingolipids. Gangliosides SiaLacCer inhibited the NK activity most effectively and their inhibitory effect depended on the structure of sialic acids: the N-acetyl form was more active than the N-glycoloyl form. Elongation of the carbohydrate chain decreased the inhibitory effect and monosialogangliosides NeuGcGgOse3Cer and NeuAcGgOse4Cer were practically inactive. The inhibitory ability of disialogangliosides depended on the structure of the carbohydrate chain as well as on the structure and attachment site of the sialic acids. Previously it was found that ganglioside (NeuAc)2LacCer, which is absent or very low in normal blood, is produced by a number of tumors and alongside with NeuAcLacCer is present in elevated amounts in the blood of tumor-bearing subjects. Elevated concentration of these gangliosides in the blood of tumor hosts may inhibit apparently the NK activity and thus contribute to the escape of tumor cells from host immune surveillance.