Polymer X-ray refractive nano-lenses fabricated by additive technology.

The present work demonstrates the potential applicability of additive manufacturing to X-Ray refractive nano-lenses. A compound refractive lens with a radius of 5 µm was produced by the two-photon polymerization induced lithography. It was successfully tested at the X-ray microfocus laboratory source and a focal spot of 5 µm was measured. An amorphous nature of polymer material combined with the potential of additive technologies may result in a significantly enhanced focusing performance compared to the best examples of modern X-ray compound refractive lenses.

[Transperitoneal and transvaginal hysterectomy using devices of the dosed high-frequency electrical current].

The experience of application of apparatuses of the dosed high-frequency electric influence EK300M-1 "Patonmed" and energetic platform "Forcetriad", manufactured by Valleylab firm, during hysterectomy performance, using various surgical accesses, was presented. The variants of the applied regimens, depending on the vessels diameter and coexistant diseases, were proposed.

[Influence of terahertz (submillimeter) laser radiation on neurons in vitro].

The development of new sources of coherent non-ionizing radiation in terahertz wave range put forward the basic problems of revealing the mechanism of its action on biological objects, especially, on the nervous system. At this point it is necessary to reveal the radiation effects on complex molecular systems such as nerve cells. It was the main objective of this study. In the previous study we were the first to demonstrate highly specific effects of some examined wavelengths on the structural-functional properties of the nerve cells. The radiation of a free-electron laser produced damage to neuron morphology dependent on the power and wavelength. Transparent blank protrusions of the membrane, disorders of the growth of processes, and fall of the membrane potential were observed. The model developed and the data obtained approach the understanding of the molecular mechanisms of the effect of the waves under study on cells. These waves can be probably used as a tool for further investigation of functioning of neurons and neural system and correction of some pathology.

Mathematical modeling the kinetics of cell distribution in the process of ligand-receptor binding.

A statistical approach is presented to model the kinetics of cell distribution in the process of ligand-receptor binding on cell surfaces. The approach takes into account the variation of the amount of receptors on cells assuming the homogeneity of monovalent binding sites and ligand molecules. The analytical expressions for the kinetics of cell distribution have been derived in the reaction-limited approximation. In order to demonstrate the applicability of the mathematical model, the kinetics of binding the rabbit, anti-mouse IgG with Ig-receptors of the murine hybridoma cells has been measured. Anti-mouse IgG was labeled with fluorescein isothiocyanate (FITC). The kinetics of cell distribution on ligand-receptor complexes was observed during the reaction process by real-time measuring of the fluorescence and light-scattering traces of individual cells with the scanning flow cytometer. The experimental data were fitted by the mathematical model in order to obtain the binding rate constant and the initial cell distribution on the amount of receptors.

Individual Escherichia coli cells studied from light scattering with the scanning flow cytometer.

BACKGROUND: Flow cytometry is a powerful tool for the analysis of individual particles in a flow. Differential light scattering (an indicatrix) was used for many years to obtain morphologic information about microorganisms. The indicatrices play the same role for individual particle recognition as a spectrum for substance characterization. We combined two techniques to analyze the indicatrix of the cells for the purpose of developing a database of light-scattering functions of cells. METHODS: The scanning flow cytometer (SFC) allows the measurement of the entire indicatrix of individual particles at polar angles ranging from 5 degrees to 100 degrees. In this work, light-scattering properties of Escherichia coli have been studied both experimentally and theoretically with the SFC and the T-matrix method, respectively. The T-matrix method was used because of the nonspherical shape of E. coli cells, which were modeled by a prolate spheroid. RESULTS: The indicatrices of E. coli cells were stimulated with T-matrix method at polar angles ranging from 10 degrees to 60 degrees. The absolute cross-section of light scattering of E. coli has been determined comparing the cross section of polystyrene particles modeled by a homogeneous sphere. The E. coli indicatrices were compared for logarithmic and stationary phases of cell growth. CONCLUSIONS: The indicatrices of E. coli were reproducible and could be used for identification of these cells in biologic suspensions. The angular location of the indicatrix minimum can be used in separation of cells in logarithmic and stationary phases. To use effectively the indicatrices for that purpose, the light-scattering properties of other microorganisms have to be studied.

Calibration-free method to determine the size and hemoglobin concentration of individual red blood cells from light scattering.

At present, hemoglobin concentration and the volume of an erythrocyte can be determined from the intensities of light scattered by an individual cell at fixed angular intervals. This method is used in modern hemoglobin analyzers, but it requires calibration of optical and electronic units by certified particles of known size and refractive index. We describe a method that is based on the parametric solution of an inverse light-scattering problem and does not require a calibration procedure. The method is based on the use of parameters of the entire angular light-scattering pattern, called an indicatrix here. These parameters do not depend on the absolute intensity of light scattering. The indicatrix parameters form approximating equations that relate these parameters to the size and the phase-shift parameters of the particle. The applicability of the method is demonstrated by measurement of the indicatrices of individual sphered erythrocytes. The indicatrices of the individual erythrocytes were measured with a scanning flow cytometer at an angular range of from 15 to 55 deg. The volume and the hemoglobin concentration have been calculated by use of the developed method and by fitting of the experimental indicatrices to the indicatrices calculated from the Mie theory.

[Preparation of Drosophila mitotic chromosomes for electron-microscopic studies]. / Prigotovlenie preparatov mitoticheskikh khromosom drozofily dlia élektronno-mikroskopicheskogo issledovaniia.

A method of chromosome spreading on microscopic slides was modified for electron microscopy of metaphase chromosomes in Drosophila tissues. The slides covered with an electron transparent film were plasmochemically modified to make them hydrophilic. A piece of fixed tissue was macerated in 60% propionic acid before spreading chromosomes over the slide. The parts of preparation selected under light microscope for electron microscopic examination were cut and peeled of the slide to the top of a water drop. It was shown that the resolution of chromosomal structures was significantly higher than seen under optical microscope, but lower than in serial sections.

[Interaction of synthetic peptides with the individual components of the blood coagulation system]. / Vzaimodeistvie sinteticheskikh peptidov s otdel'nymi komponentami sistemy svertyvaniia krovi.

Spectrophotometry and viscosimetry were used to examine the interaction of taftcin and its decomposition products with individual components of the blood coagulation system. Peptides with free amino groups at the N-end were found to form complexes with heparin. The presence of free carboxylic groups at the C-end provided for their interaction with fibrinogen. In both the cases, the leading roles are played by electrostatic forces that determine the weakness of the effects seen. Taftcin has a negligible antipolymerization activity at the expense of the Pro-Arg sequence presence at the C-end.