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The effect of illumination in the visible spectral range on the magnitude of transverse acoustoelectric effect (TAE) in ZnS/Si structures was studied using a noncontact surface acoustic wave device based on the acoustoelectronic structure with an air gap. ZnS films were obtained using pyrolysis of the chelate organometallic complex, zinc diethyldithiocarbamate, on Si substrates within the temperature range 220 to 260 °C. It has been established that the charge of the adsorption origin on the external surface of the ZnS film strongly influences the photo-processes in the structure under consideration. For the samples with a small surface charge, the value of TAE decreases rapidly with the increase in illumination power due to an increase in the concentration of non-equilibrium carriers. For the samples with a large surface charge, the barrier-trap mechanism of photogeneration is observed, in which the appearance of non-equilibrium carriers is accompanied by their capture and subsequent thermalization. This compensating mechanism explains well both stabilization of the magnitude of TAE by a distributed system of traps with rather large capacitance, and the specific shape of dependence of the TAE magnitude on illumination power. The technique developed by us on the basis of the transverse acoustoelectric effect in the layered piezodielectric / air-gap / semiconductor structure is a powerful tool for noncontact determination of the charge state of film structures, depending on their deposition parameters and various external conditions. [ABSTRACT FROM AUTHOR]

We report the results of the comprehensive study of the structural, magnetic and optical properties of SrTiO3 perovskite doped with Eu3+ ions. Polycrystalline powders were obtained by sol-gel process including high-temperature annealing at 1300°C. The structural analysis showed that material is composed of several phases with dominant SrTiO3 and considerable quantity of titanium dioxide (rutile, 10×20%). Both the amount of Eu and ratio of Eu:Sr in the final product are considerably smaller as compared to the original solutions for synthesis. The elemental analysis reveals europium only in the phase of EuSrTi2O7 compound for equimolar ratio of Eu and Sr during the synthesis. The EPR analysis reports deficiency of Eu2+ in the samples under investigations. SrTiO3:Eu3+ powders demonstrate weak photoluminescence, which intensity grows up with increasing the concentration of Eu and reaches its maximum at c.a. 8 mol.% of Eu in the original solutions. Addition of Al increases the intensity of photoluminescence (c.a. 2.2 for 10 mol.%). Emission spectra are typical for Eu3+ occupied sites with high symmetric environment (dominant 5D0→7F1 transition) with relatively low distortion (both 5D0→7F2 and 5D0→7F4 as well present, but with a lower intensity) of coordination polyhedron. Low solid-solubility limit of Eu3+ in perovskite matrix (less than 1 mol.%), peculiarities of optical spectra, effect of Al, production/annealing temperature dependence etc. have suggested that structural effects are dominating in functional, in particular, optical properties of SrTiO3:Eu3+ phosphors. [ABSTRACT FROM AUTHOR]

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We consider the crisp and fuzzy partitioning techniques of cluster analysis bearing in mind their application for classification of data obtained with chemical sensor arrays. The advantage of the cluster analysis techniques is existence of a parameter S(I). This parameter gives quantitative efficiency of classification and can be used as optimization criterion for sensor system as a whole as well as the measurement procedure. The crisp and fuzzy techniques give practically the same result when analyzing the data that cluster uniquely. It is shown that big value of the parameter S(I) is not sufficient for adequate data partitioning into cluster in more complicated cases, and the results of clusterization for the above techniques may diverge. In this case, one should apply both techniques concurrently, checking the correctness of partitioning into clusters against the principal component analysis. [ABSTRACT FROM AUTHOR]

We report the effect of easy axis producing on isotropic polymer surface in cells with dye-doped liquid crystal (LC) irradiated with visible polarized light. We showed strong dependencies of the light-induced anchoring on the time passed from the cell's filling with LC. The cells made from the reference rubbed aligning surface and the tested isotropic surface and filled with doped LC were irradiated with light with polarization set at 45° to the rubbing direction. Twist structures resulted due to light-induced easy axis on the tested surface were studied. The twist angle decreased exponentially with cell's age. We believe that this behaviour is due to the anisotropic dark adsorption of dye on the substrate and formation of "dark" easy axis, which influences on the light-induced anchoring. This model is supported by experiments on time changes of cell's conductivity, surface plasmon resonance angle and the anchoring memory effect in a not-irradiated cell. [ABSTRACT FROM AUTHOR]

We show that an important factor in the mechanism of formation for thin films of organic semiconductors is the change in the temperature gradient in the film as its thickness increases. In this case, an important role information of oriented films is played by both diffusional processes within clusters and by re-evaporation of small crystallites. [ABSTRACT FROM AUTHOR]

A study was made of the influence of an amphiphilic macrocyclic nickel(II) complex on the electrical and electro-optic properties of liquid-crystalline systems based on ZhK-440I. It was shown that addition of this complex leads to a decrease in the electrohydrodynamic instability threshold and formation of unusual tetragonal ordered structures in the systems studied. [ABSTRACT FROM AUTHOR]

Review: 222 refs. [ABSTRACT FROM AUTHOR]

Aim: To study upstream and downstream events in CD150-mediated Akt signaling pathway in normal human B cells, EBV-transformed lymphoblastoid (LCL) and malignant Hodgkin's lymphoma (HL) B cell lines., Methods: To access protein-protein interaction we applied immunoprecipitation, Western blot analysis and surface plasmon resonance (SPR) technique. A novel modification of SPR technique using reduced glutathione bound to golden surface was proposed. Immunostaining and isolation of cytoplasmic fractions and nuclear extracts were performed to detect proteins' localization in cells. Western blot analysis was performed to follow up the phosphorylation of proteins on specific sites and proteins' expression level., Results: It was shown that CD150 ligation induced Akt activation in normal tonsillar B cells (TBC), SH2D1A positive LCL and HL B cell lines. The p85α subunit of PI3K co-precipitated with CD150 cytoplasmic tail. This direct association depends on tyrosine phosphorylation and is mediated by N terminal SH2 domain of p85α. CD150 initiated phosphorylation of FoxO1 transcription factor in normal B cells as well as in LCL MP-1 and HL cell line L1236. At the same time, CD150 ligation triggered GSK-3β kinase phosphorylation only in immortalized LCL MP-1 and HL cell line L1236., Conclusions: We have demonstrated that CD150 receptor could trigger PI3K-mediated Akt signaling pathway in normal, EBV-transformed and malignant B cells. CD150-mediated phosphorylation of Akt downstream targets GSK-3β and FoxO1 in EBV-transformed and HL cells could be one of the mechanisms to avoid apoptosis and support survival program in these immortalized B cells.

The irreversible adsorption of proteins on artificial surfaces plays an important role in a wide variety of practical problems. The simple analytical models based on definite concepts regarding the mechanisms of interfacial evolution can be used efficiently for characterization of protein-surface interactions by analyzing the intrinsic kinetics of the process. In this article, analytical expressions are derived for the adsorption kinetics that take into account the presence of more than one adsorbed state for proteins in biofilms. It is shown that the experimentally observed dependence of the adsorbed mass on the concentration of protein in solution can be reproduced with this model, and the approach provides a rapid method for obtaining quantitative parameters for the adsorption process. It is shown by analytical approximation of the kinetic curves for fibrinogen adsorption onto an unmodified gold surface studied by a surface plasmon resonance biosensor that this model is in good quantitative agreement with experiments. It is found that the rate of adsorption, controlled mainly by the mass flow from the solution, determines the contribution both to self-assembling and spreading, resulting in variations of adsorbed fibrinogen interfacial structures.

Highly specific and proximal method of laboratory diagnostics of the viral disease, has been developed using the structural protein of the potato virus X, as a model, and monospecific antibodies to it. The immunospecific determination of the potato virus X was carried out by the surface plasmon resonance method using specific IgG-antigen complexes, immobilized on the sensor surface modified by rodanide and protein A of Staphylococcus aureus.

A possibility to detect adenoviral protein--hexon, using specific antibodies by surface plasmon resonance (SPR) was demonstrated. The hexon of the human adenovirus 2 (Ad2) binds to antibodies immobilized on the sensor surface treated by KNCS and protein A Staphylococcus aureus. The specificity of antihexon antibodies was demonstrated by indirect method of fluorescent antibodies (MFA) and cellular variant of the immunoassay (cELISA).

The use of instrumental systems based on the surface plasmon resonance (SPR) for rapid diagnosis of intact plant viruses (in particular, tobacco mosaic virus (TMV)) is considered. A new approach using detection of viral antigen and antibody (IgG) complexes formed during the preincubation step (instead of their consecutive application in classical approach) is discussed. A comparison between signal level registered from the mixture of virus and specific serum and that from the sample without virus (samples deposited onto the sensor surface treated with thiocyanate and protein A Staphylococcus aureus) allows unambiguous detection of viral particles in the material studied. The performance capabilities of the method are discussed and illustrated by quantitative detection of virus in the actual samples (cells homogenate) at high concentration.

Immobilization of immunoglobulins on the unmodified gold surface and the gold surface, modified by thiocyanate and protein A Staphylococcus aureus and their subsequent interaction with complementary antibodies were studied using the surface plasmon resonance method. Viral antigens were detected by surface plasmon resonance method in the cell homogenate of green alga Bracteococcus minor, which was artificially infected by tobacco mosaic virus. It was shown, that the process of interaction between virus and antiviral serum obey the Langmure model.