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Abstract: Using structural analysis methods (metallographic, X-ray diffraction, differential scanning microscopy), a comprehensive study of the structure of Al82Cu7Fe11alloy, obtained in the form of ribbons by the melt spinning method, was carried out. It is shown that a multiphase amorphous-nanocrystalline structure of high dispersity is formed in the alloy, which includes a solid solution based on aluminum, intermetallic compounds Fe4Al13and CuAl2, and a small amount of a quasicrystalline phase of the composition Al–Fe–Cu with a tenth order symmetry axis (decagonal). The parameters of crystal lattices of phases and their volumetric content have been certified. It is shown that the main structural component of an alloy is iron aluminide, the content of which varies from 68 to 61 wt % across the ribbon cross section from the contact to the free surface. The temperatures of phase transformations in the alloy upon heating were determined. A comparative analysis of the structures on the basis of the phase composition and morphology of phases formed in rapidly quenched ribbons and an ingot of the same composition crystallized under equilibrium conditions was carried out. A difference in the alloy structure after different methods of crystallization has been established. The microhardness of the main structural components in the ingot was determined. Iron aluminide has a maximum hardness of 780 HV. It has been shown that the high hardness of 615 HVof the alloy after high-speed quenching is ensured by the formed multiphase amorphous-nanocrystalline state of the structure.

Progress in studying pathogenesis and increasing the reliability of hepatitis C diagnosis can be achieved by analysis of different forms of virus particles circulating in blood of both patients and infected persons. Detection of hepatitis C virus (HCV) proteins faces two basic difficulties: low concentration of HCV proteins, and their blocking by antibodies. The aim of this work was to develop a method for the detection of nucleocapsid (core) protein in the plasma of HCV‐infected persons using monoclonal antibodies (MABs). Twenty‐seven anti‐HCV‐positive donor plasmas were studied of which 21 contained HCV RNA and 6 were negative. The plasmas were centrifuged for 3 hr at 143,000 g and the antigenic activity of core‐protein was studied in the pellets by EIA using four MABs able to recognize four nonoverlapping determinants, two at N‐terminus and two at C‐terminus of recombinant core (1–150 aa). The determinants detected were present in the natural core protein of at least two genotypes (1b and 3a). Maximal efficiency of recombinant protein detection was achieved with 2 MABs, whereas a combination of 4 MABs was necessary for optimal detection of natural core protein. This is indicative of different conformational structures of natural protein and its gene‐engineered analog. The sensitivity of core detection by monoclonal sandwich assay was 1 ng/ml in the pellet or 5 pg/ml after normalization to the initial plasma volume. To dissociate immune complexes, the pellet was treated with 2.5 M KBr after first treating the pellet with the nonionic detergent Tween 80 to remove the virus lipid envelope. Using this treatment protocol, core protein was found in 19 of 21 RNA positive plasmas. J. Med. Virol. 55:1–6, 1998. © 1998 Wiley‐Liss, Inc.

The aim of this work was to obtain Si3N4/SiC composites, where silicon nitride served as the matrix, and the silicon carbide content varied from 3 to 50wt.%. To reduce the sintering temperature (hot pressing) of the ceramic, it is used a sintering additive of calcium aluminate eutectic. The charge was prepared as follows: the silicon nitride powder was mixed with 10 wt.% sintering calcium aluminates, then the charge was added over 100 % of silicon carbide in an amount of 3, 5, 7, 10, 15, 20 and 50 wt.% in a planetary mill. Ceramic materials were hot pressed at 1660degC, the pressure was 30 MPa for 60 minutes in N2 atmosphere. The 10 wt.% SiC composite has highest properties: 3.16 g/cm3 density, 650 MPa bending strength, 22 GPa microhardness.

The Si3N4-TiN composites were obtained by hot pressing at 1600-1800 degC in a nitrogen atmosphere from mixtures of powders of silicon nitride and metallic titanium. The influence of particle morphology, Ti content in the initial charge and synthesis conditions on the microstructure, phase composition, mechanical strength of the samples of ceramic composites Si3N4-TiN was studied. It was established that in the process of sintering, complete nitriding of titanium occurs with the formation of a non-stoichiometric nitride of composition TiN0.9. Samples of composites Si3N4-TiN, obtained from a mixture containing 5-30 % Ti, have a density of 3.02-3.41 g/cm3, water absorption 0.01-0.14 %, open porosity 0.03-0.44 % and flexural strength from 250 to 584 MPa. It is shown that ceramics Si3N4-TiN with a sintering additive of calcium aluminates is characterized by a dense intergrowth of silicon nitride crystals, which provides an increase in the strength of the samples.

The biomimetic precipitation of calcium phosphate (CaP) coating was performed by soaking of b-tricalcium phosphate (TCP) ceramic scaffolds in supersaturated solution. Surface functionalization was obtained by incorporation of bovine serum albumin (BSA) as a model protein. The structure and phase composition were studied by application of XRD, FTIR, SEM, BET absorption. BSA incorporation content as a result of co-precipitation was evaluated.

The paper considers preparation of a strong and dense ceramics based on silicon nitride by sintering in a SHS reactor. As a sintering agent, an additive was used in the Al2O3-CaO system. The content of the additive varied from 5 to 15 wt. %. It is established that an increase in the amount of silicon introduced into the initial charge increases the strength characteristics of the material due to the formation of secondary silicon nitride during sintering.