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Search Results: 1 - 10 of 3643 matches for " Tatiana Kukhtarev "
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Temperature Dependent Surface Resistivity Measures of Commercial, Multiwall Carbon Nanotubes (MWCNT), and Silver Nano-Particle Doped Polyvinyl Alcohol (PVA) Films  [PDF]
Matthew Edwards, Stephen Egarievwe, Afef Janen, Tatiana Kukhtarev, Jemilia Polius, John Corda
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.513093
Abstract: Pure and doped Polyvinylidene difluoride (PVDF) films, for the detection of infrared radiation, have been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We found that the surface resistivity measurements on PVA films were readily implemented.
Heavy electrons: Electron droplets generated by photogalvanic and pyroelectric effects
V. Krasnoholovets,N. Kukhtarev,T. Kukhtareva
Physics , 2009, DOI: 10.1142/S0217979206034662
Abstract: Electron clusters, X-rays and nanosecond radio-frequency pulses are produced by 100 mW continuous-wave laser illuminating ferroelectric crystal of LiNbO_3. A long-living stable electron droplet with the size of about 100 mcm has freely moved with the velocity 0.5 cm/s in the air near the surface of the crystal experiencing the Earth gravitational field. The microscopic model of cluster stability, which is based on submicroscopic mechanics developed in the real physical space, is suggested. The role of a restraining force plays the inerton field, a substructure of the particles' matter waves, which a solitary one can elastically withstand the Coulomb repulsion of electrons. It is shown that electrons in the droplet are heavy electrons whose mass at least 1 million of times exceeds the rest mass of free electron. Application for X-ray imaging and lithography is discussed.
Crystal Optical Properties of Inhomogeneous Plates and the Problems of Polarization Tomography of Photoelastic Materials
Kushnir O.,Nek P.,Vlokh R.,Kukhtarev N
Ukrainian Journal of Physical Optics , 2005,
Abstract: Using the Jones matrix formalism, crystal optical properties of inhomogeneous material consisting of a pile of weakly birefringent plates are analysed in relation to the cell model adopted in polarization tomography of 3D dielectric tensor field in photoelastic media. It is shown that the material manifests in general an “apparent” optical gyration caused by different orientations of the plates. Relations between the polarimetric parameters and the dielectric tensor components are ascertained for the case of weak optical anisotropy.
Crystal Optical Properties of Inhomogeneous Plates and the Problems of Polarization Tomography of Photoelastic Materials
O. Kushnir,P. Nek,R. Vlokh,N. Kukhtarev
Physics , 2007, DOI: 10.3116/16091833/6/3/87/2005
Abstract: Using the Jones matrix formalism, crystal optical properties of inhomogeneous material consisting of a pile of weakly birefringent plates are analysed in relation to the cell model adopted in polarization tomography of 3D dielectric tensor field in photoelastic media. It is shown that the material manifests in general an "apparent" optical gyration caused by different orientations of the plates. Relations between the polarimetric parameters and the dielectric tensor components are ascertained for the case of weak optical anisotropy.
Protein phase instability developed in plasma of sick patients: clinical observations and model experiments  [PDF]
Tatiana Yakhno
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.23034
Abstract: This article discusses the causes of formation of micron-size protein structures in liquid plasma or serum of the patients with different diseases, which are accompanied by inflammatory reac-tions. Self-organizing processes in sessile dry-ing drops of natural and model biological liq-uids are used for study of possible mechanisms of development the protein phase instability in serum. There was shown that violation of opti-mal ratio between albumin and osmotic active components could lead to loss of albumin ag-gregative stability and albumin coagulation structures formation. Possible role of these structures in pathogenesis of inflammation is discussed.
Eating disorders, body image, and dichotomous thinking among Japanese and Russian college women  [PDF]
Atsushi Oshio, Tatiana Meshkova
Health (Health) , 2012, DOI: 10.4236/health.2012.47062
Abstract: This study explored cross-cultural differences between Japan and Russia in terms of women’s body images, proneness to eating disorders, and the effects of dichotomous thinking. Participants included 419 Japanese and 187 Russian college women who completed the Dichotomous Thinking Inventory (DTI), the 26-item version of the Eating Attitudes Test, and responses regarding nine figures representing female body shapes. The mean age of the participants was 19.8 years, with no significant age differences between the countries. The results showed that Japanese women have leaner ideal body images than Russian women, whereas there were no cross-cultural differences in the participants’ real body images. DTI scores among Russian participants were higher than DTI scores among Japanese participants, which indicated that Russian women think more dichotomously than Japanese. Structural equation modeling indicated a significantly negative effect of dichotomous thinking only on real body image in Russia; the ideal body image had greater effects on eating disorder in Russia than in Japan.
Functional Acrylic Polymer as Corrosion Inhibitor of Carbon Steel in Autoclaved Air-Foamed Sodium Silicate-Activated Calcium Aluminate/Class F Fly Ash Cement  [PDF]
Toshifumi Sugama, Tatiana Pyatina
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511109
Abstract:

The study focused on investigating the effectiveness of functional acrylic polymer (AP) in improving the ability of airfoamed sodium silicate-activated calcium aluminate/Class F fly ash cement (slurry density of 1.3 g/cm3) to mitigate the corrosion of carbon steel (CS) after exposure to hydrothermal environment at 200?C or 300?C. Hydrothermally-initiated interactions between the AP and cement generated the formation of Ca-, Al-, or Na-complexed carboxylate derivatives that improved the AP’s hydrothermal stability. A porous microstructure comprising numerous defect-free, evenly distributed, discrete voids formed in the presence of this hydrothermally stable AP, resulting in the increase in compresive strength of cement. The foamed cement with advanced properties conferred by AP greatly protected the CS against brine-caused corrosion. Four major factors governed this protection by AP-incorporated foamed cements: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surface; 2) Inhibiting the cathodic reactions at the corrosion site of CS; 3) Extending the coverage of CS by the cement; and 4) Improving the adherence of the cement to CS surface.

Toughness Improvement of Geothermal Well Cement at up to 300°C: Using Carbon Microfiber  [PDF]
Toshifumi Sugama, Tatiana Pyatina
Open Journal of Composite Materials (OJCM) , 2014, DOI: 10.4236/ojcm.2014.44020
Abstract: This study aimed at assessing the usefulness of carbon microfiber (CMF) in improving the compressive-toughness of sodium metasilicate-activated calcium aluminate/Class F fly ash foamed cement at hydrothermal temperatures of up to 300°C. When the CMFs came in contact with a pore solution of cement, their surfaces underwent alkali-caused oxidation, leading to the formation of metal (Na, Ca, Al)-complexed carboxylate groups. The extent of this oxidation was enhanced by the temperature increase, corresponding to the incorporation of more oxidation derivatives at higher temperatures. Although micro-probe examinations did not show any defects in the fibers, the enhanced oxidation engendered shrinkage of the interlayer spacing between the C-basal planes in CMFs, and a decline in their thermal stability. On the other hand, the complexed carboxylate groups present on the surfaces of oxidized fibers played a pivotal role in improving the adherence of fibers to the cement matrix. Such fiber/cement interfacial bonds contributed significantly to the excellent bridging effect of fibers, resistance to the cracks development and propagation, and to improvement of the post-crack material ductility. Consequently, the compressive toughness of the 85°-, 200°-, and 300°C-autoclaved foamed cements reinforced with 10 wt% CMF was 2.4-, 2.9-, and 3.1-fold higher than for cement without the reinforcement.
Polyphosphatase PPX1 of Saccharomyces cerevisiae as a Tool for Polyphosphate Assay  [PDF]
Lidiya Lichko, Tatiana Kulakovskaya
Advances in Enzyme Research (AER) , 2015, DOI: 10.4236/aer.2015.34010
Abstract: The recombinant exopolyphosphatase PPX1 with a specific activity of ~300 U/mg protein was purified from the strain of Saccharomyces cerevisiae with the inactivated PPN1 gene transformed by the expression vector carrying the yeast PPX1 gene. The recombinant PPX1 was similar to the PPX1 of wild strains in its substrate specificity and requirement for cations. PPX1 had the high substrate specificity to polyphosphates. The preparation was suitable for polyphosphate assay in the presence of orthophosphate and nucleoside phosphates not hydrolyzed by PPX1. The yield of the enzyme preparation was 250 assays per 1 g of the biomass. The recombinant PPX1 was successfully used in polyphosphate assay in different yeast species and some foodstuffs.
Bond Durability of Carbon-Microfiber-Reinforced Alkali-Activated High-Temperature Cement Adhering to Carbon Steel  [PDF]
Toshifumi Sugama, Tatiana Pyatina
Engineering (ENG) , 2017, DOI: 10.4236/eng.2017.92007
Abstract: The study aims at evaluating the bond durability of a carbon microfiber (CMF)-reinforced alkali-activating calcium aluminate cement (CAC)/fly ash F (FAF) blend cementitious material adhering to carbon steel (CS) under stresses induced by a 350 heat-25 water cooling cycle. This cementitious material/CS joint sample was originally prepared in an autoclave at 300 under a pressure of 8.3 MPa. For comparison, two reference geothermal well cements, Class G modified with silica (G) and calciumaluminum phosphate (CaP), were employed as well reinforced with CMF. In the CAC/FAF blending cement systems, the CAC-derived cementitious reaction products preferentially adhered to CS surfaces, rather than that of FAF-related reaction products. CMF played a pivotal role in creating tough interfacial bond structure of cement layer adhering to CS. The bond toughness also was supported by the crystalline cementitious reaction products including sodalite, brownmillerite, and hedenbergite as major phases, and aragonite, boehmite, and garronite as minor ones. The brownmillerite as an interfacial reaction product between cement and CS promoted the chemical bonding of the cement to CS, while the other phases served in providing the attractive bonding of the cement to CS. The post-stress-test joint samples revealed the formation of additional brown-millerite, aragonite, and garronite, in particular brownmillerite as the major one. The combination of chemical bonding and self-advancing adherence behavior of the cement was essential for creating a better interfacial bond structure. A similar interfacial bond structure was observed with CaP. The crystalline phase composition of the autoclaved cement revealed apatite, zeolite, and ferrowyllieite as major reaction products, and aragonite and al-katoite as the minor ones. Ferrowyllieite was identified as cement/CS interfacial reaction product contributing to the chemical bond of cement, while the other phases aided in providing the attractive bond of cement. After a stress test, two phases, ferrowyllieite and aragonite, promoted the self-advancing adherence of cement to CS. However, the effectiveness of these phases in improving adherence performance of cement was less than that of CAC/FAF blend cement, reflecting the fact that the bond durability of CAC/FAF blend cement was far better than that of the CaP. In contrast, the autoclaved silica-modified G cement consisting
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