335 research outputs found

    Results of the investigation of the otolith function in manned space flights

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    The effects of conditions of long term and short term space flights on the otolith function of cosmonauts were investigated via pre and post examinations. The results show that after long term flight, the intensity of the otolith reflex increased and asymmetry occurred in the indicators of the otolith function. Large changes in terms of expression and duration in the indicators of the otolith function after long term flight as compared with short term flight were also noted

    PHOTOTUNABLE SELECTIVE REFLECTION OF CHOLESTERIC LIQUID CRYSTALS

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    The dependence of the helical pitch of a cholesteric liquid crystal based on a composite photosensitive chiral dopant (cChD) on the intensity of light irradiation was studied. The transmission spectra and the selective reflection spectra of cholesteric liquid crystal cells were measured. The concentration of the cChD additive is calculated, so that the peak of selective reflection and its rearrangement occurs in the visible range of the electromagnetic radiation spectrum (380-780 nm). The possibility of photo-control by shifting the peak of the selective reflection of the cChD additive was studied, when exposed to LEDs with wavelengths of 365 nm and 450 nm, while reducing or increasing the intensity, a change in the spiral pitch was observed. Depending on the light intensity, part of the molecules of the chiral additive containing the azo group underwent isomerization, i.e. molecules in the trans-form passed to the cis-form, which led to a spectral shift of the selective reflection peak. If a small intensity of the 365 nm LED was applied, then some of the molecules were forced to transition from the trans- to the cis-form, and then, when illuminated with a 450 nm LED, from the cisto the trans-form. After reversible rearrangement, the properties of cholesteric liquid crystal changes due to interaction with light, because under the influence of light, the equilibrium ratio of the trans- and cis-isomers of the molecules of the substance changed, which macroscopically changed the torsion force of the chiral additive. Using two LEDs of 365 nm and 450 nm with different emission spectra, a reversible control of the cChD selective reflection peak in the visible range was obtained. The maximum displacement occurred at approximately 145 nm.The dependence of the helical pitch of a cholesteric liquid crystal based on a composite photosensitive chiral dopant (cChD) on the intensity of light irradiation was studied. The transmission spectra and the selective reflection spectra of cholesteric liquid crystal cells were measured. The concentration of the cChD additive is calculated, so that the peak of selective reflection and its rearrangement occurs in the visible range of the electromagnetic radiation spectrum (380-780 nm). The possibility of photo-control by shifting the peak of the selective reflection of the cChD additive was studied, when exposed to LEDs with wavelengths of 365 nm and 450 nm, while reducing or increasing the intensity, a change in the spiral pitch was observed. Depending on the light intensity, part of the molecules of the chiral additive containing the azo group underwent isomerization, i.e. molecules in the trans-form passed to the cis-form, which led to a spectral shift of the selective reflection peak. If a small intensity of the 365 nm LED was applied, then some of the molecules were forced to transition from the trans- to the cis-form, and then, when illuminated with a 450 nm LED, from the cisto the trans-form. After reversible rearrangement, the properties of cholesteric liquid crystal changes due to interaction with light, because under the influence of light, the equilibrium ratio of the trans- and cis-isomers of the molecules of the substance changed, which macroscopically changed the torsion force of the chiral additive. Using two LEDs of 365 nm and 450 nm with different emission spectra, a reversible control of the cChD selective reflection peak in the visible range was obtained. The maximum displacement occurred at approximately 145 nm

    Dicyclopentadiene Polymerization in Solutions under the Action of Various Catalytic Systems

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    The kinetics of dicyclopentadiene polymerization in toluene solution under the action of different catalytic systems through adiabatic thermometry was investigated. Unlike cationic metathesis polymerization has a sufficiently large induction period associated with low speed by implantation monomer on carbine bond of catalyst. It has been shown that the rate of metathesis polymerization of dicyclopentadiene in comparable circumstances is about three times lower than the rate of cationic polymerization of the same monomer

    Dicyclopentadiene Polymerization in Solutions under the Action of Various Catalytic Systems

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    The kinetics of dicyclopentadiene polymerization in toluene solution under the action of different catalytic systems through adiabatic thermometry was investigated. Unlike cationic metathesis polymerization has a sufficiently large induction period associated with low speed by implantation monomer on carbine bond of catalyst. It has been shown that the rate of metathesis polymerization of dicyclopentadiene in comparable circumstances is about three times lower than the rate of cationic polymerization of the same monomer

    Oxidation and Structuring of Polydicyclopentadiene Thin Layers

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    It has been shown that polymeric film coatings derived from polydicyclopentadiene are subject to oxidation and structuring in air. Oxidation in air of double bonds in films gradually happens during several weeks and it comes amid an increase of adsorption band of carbonyl and hydroxyl groups in polymers infrared spectrums. Moreover, because of selective oxidation of cis-configured chains, structuring occurs around the double bonds in the polymer chain in polydicyclopentadiene films acquired by metathesis polymerization

    Diffuse Neuroendocrine System: Structural and Functional Effects of Radiation Injury to Amine Precursor Uptake and Decarboxylation (APUD) Cells

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    The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract and the subsequent adaptive response of DNES. Analysis of our results, together with a review of the literature, indicates that APUD cells actively participate both in pathogenesis of radiation injury and development of organ and tissue radiosensitivity

    Enzymatic Activity of Aphroproteins

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    Chitinase and proteinase activities were found in aphroproteins excreted by larvae of the cicada Aphrophora costalis Mats; this accounts for their fungicidal effect. Aphroproteins did not show DNase or RNase activities and did not exhibit properties of proteinase inhibitors. The data suggest that larval foam protects the larva and host plant from entomogenous and phytopathogenic fungi

    The variability of representation and latency of the F-wave in patients at different periods of spinal cord injury

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    Introduction. Neurophysiological examination in patients with spinal cord injury is advisable to determine the end of the period of spinal shock. F-wave is a late electromyographic phenomenon realized by activating a pool of motor neurons of the anterior horns of the spinal cord. In the state of spinal shock, the duration of which is variable, F-waves are not recorded. The presence of F-waves from the tibial nerves indicates the completion of spinal shock and restoration of electrical excitability of motor neurons of the anterior horn of the spinal cord. The appearance of F-waves is a marker for diagnostic transcranial magnetic stimulation to assess the viability of the cortical-spinal tract in the early stages of spinal shock.Study aim. To analyze the representation of F-waves in patients in different periods of spinal shock, depending on the level, volume and duration of the lesion.Materials and methods. There were a total of 15 patients with spinal trauma in age from 19 to 29 years enrolled. All patients affected were localized in segments C4–C7. The examination included stimulation electroneuromyography: registration of motor responses, sensory responses and F-waves from the median, ulnar, fibular and tibial nerves on both sides.Results. In 5 patients: 3 in acute, 1 in early and 1 in late periods of spinal cord injury, spinal shock was clinically diagnosed: electromyographic revealed the absence of F-waves for all tested nerves. In 4 patients in the early period of spinal cord injury F-waves were registered only with n. tibialis, the first spontaneous movements in the limbs were clinically observed; in 6 patients in the intermediate and late periods of spinal cord injury f-waves were recorded from all the nerves under study with constant latency. The end of spinal shock was clinically verified, with the presence of a minimum volume of movements and restoration of sensitivity in individual segments.Conclusion. Registration of F-wave should be a mandatory component of stimulation electromyographic in the verification of spinal shock, the duration of which is not correlated with the periods of spinal cord injury. The presence of f-waves is a diagnostic marker for transcranial magnetic stimulation to assess the viability of the cortical-spinal tract
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