Interaction between blood plasma proteins and magnetite nanoparticles

Spin label EPR spectroscopy and dynamic and Rayleigh light scattering are employed to study the interaction between magnetite nanoparticles with a diameter of 17 nm and plasma proteins (fibrinogen and albumin). Protein molecules are shown to be adsorbed on nanoparticle surface with the formation of multilayer shells. When a buffer solution (pH 8.5) contains 0.01 vol % nanoparticles, 90–100 fibrinogen molecules are adsorbed per one particle and the thickness of an adsorbed layer is 30–40 nm. For albumin, the layer thickness is 10–15 nm. In a constant magnetic field, large linear microsized aggregates oriented parallel to field lines are formed in dispersions of nanoparticles covered with adsorbed protein molecules. The study of fibrin gel formation resulting from the action of thrombin enzyme on fibrinogen suggests that, in the presence of nanoparticles, the rate of gelation decreases by a factor of approximately two, while the ratio between the average mass and average length of fibrin polymer fibers rises.     

Synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes

A method for synthesis of a hybrid material from CdS nanoparticles and carbon nanotubes (CNT) by the precipitation of CdS nanoparticles on the CNT surface from an aqueous solution containing the Cd^II salt, thiourea, and ammonia was developed. The dependences of the size of particles formed on the CNT on the temperature of the solution and the duration of precipitation were observed. The degree of imperfection of the CNT surface exerts a substantial effect on the density of the precipitated CdS particles.     

Carbon/carbon nanocomposites fabricated by base catalyzed twin polymerization of a Si-spiro compound on graphite sheets

Defect-free microporous carbon layers on graphite can be produced by DABCO-catalyzed twin polymerization of 2,2'-spirobi[4H-1,3,2-benzodioxasiline] in a slurry polymerization and subsequent thermal transformation of the resulting phenolic resin into carbon.     

Wittig rearrangement of 1-[(1E)-3-(Benzyloxy)prop-1-en-1-yl]adamantane

Wittig rearrangement of an allyl benzyl ether containing an adamantane fragment has been studied. 1-[(1E)-3-(Benzyloxy)prop-1-en-1-yl]adamantane reacts with butyllithium to give [2,3]- and [1,2]-rearrangement products. The [2,3]-rearrangement product is a mixture of threo and erythro diastereoisomers, the latter prevailing.     

Vibrational spectra, structure, and proton conduction in hydrous tin dioxide

SnO₂ · nH₂O (hydrous tin dioxide, HTD, n = 1.5) and SnO₂ · nD₂O (deuterated hydrous tin dioxide, DHTD) samples were studied by IR and Raman spectroscopy. The using of these spectroscopic methods elucidated some structural features of the hydrogen-bond network in HTD, where two types of water molecules and two types of hydroxide groups are present. Type 1 water molecules and hydroxide groups are found to be linked to one another by weak hydrogen bonds, as in liquid water. Type 2 water molecules and hydroxide groups are linked to type 1 water molecules and hydroxide groups by rather strong hydrogen bonds. The existence of these strong hydrogen bonds is interpreted as arising from the effect of tin ions on some water molecules and hydroxide groups. Proton conductivity in HTD was found by the impedance method to be a nearly linear function of n. The break of the line at n = 1.3 corresponds to the percolation threshold. The roles of type 1 and type 2 water molecules and hydroxide groups in the generation of proton conduction in HTD are discussed.     

Synthesis and photoluminescence of Eu(III) and Tb(III) complex compounds containing anions of 4-CF3C6F4COOH and 4-(CF3)2CFC6F4COOH acids

Hydrates of Eu(III) and Tb(III) salts with anions (L) 4-CF₃C₆F₄COO^? and 4-(CF₃)₂CFC₆F₄COO^?, and also mixed-ligand complexes Ln(phen)(L)₃ were obtained. The compounds show red and green photoluminescence characteristic of Eu³⁺ and Tb³⁺ ions, respectively, in the visible region of spectrum. The intensity of the photoluminescence of the complexes containing 1,10-phenanthroline is much higher than that of compounds containing water. It is connected with sensitizing properties of phen in relation to Eu³⁺ and Tb³⁺ ions.     

Working electrodes for low-temperature CO2-sensors

The behavior of SnO₂ doped by Sb₂O₄, V₂O₅ and Ta₂O₅, Nb₂O₅ as working electrodes for CO₂ sensors was studied. The concentration dependence, relaxation of the voltage after pulses of CO₂ charged gases, temperature dependence were determined. The explanation of the effect of the nature of the working electrode on the CO₂-sensor behavior and the mechanism of the reactions at the working electrode are proposed. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11 – 18, 1994     

Synthesis and reactivity of acyclic and macrocyclic uracils bridged with five-membered heterocycles

Replacement of terminal atoms of Br in 1,3-bis(bromopentyl)-5(6)-substituted uracils with 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptoimidazole, and 2-mercaptobenzimidazoles resulted in a series of acyclic compounds and isomeric heterocyclophanes. Structures of macrocyclic regioisomers were unambiguously determined by NMR data. One of the regioisomers exhibits a hypochromic effect with respect to model compounds. The acyclic uracils obtained bridged with five-membered heterocycles are alkylated with methyliodide and methyl tosylate, and oxidated with m-CPBA, H₂O₂, and I₂.