| 11. |
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| 12. |
- Vannikov, Anatoly, et al.
(author)
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Photorefractive polymer composites for the IR region based on carbon nanotubes
- 2005
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In: Optics and Spectroscopy (English translation of Optika i Spektroskopiya). - : Pleiades Publishing Ltd. - 1562-6911 .- 0030-400X. ; 99:4, s. pp.643-648
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Journal article (peer-reviewed)abstract
- The photorefractive properties of polymer composites based on aromatic polyimide and single-wall carbon nanotubes are studied using radiation at a wavelength of 1064 nm. It is found that the nanotubes possess photoelectric sensitivity in this spectral region and that the kinetic photorefractive characteristics of the polymer composites are entirely determined by the photogeneration and charge transport characteristics of the layers. The two-beam gain coefficient of the signal beam measured for a composite consisting of aromatic polyimide and 0.25 wt % of single-wall carbon nanotubes in a constant electric field E 0 = 79 V/μm is equal to 84 cm -1 and exceeds the optical absorption coefficient by 59 cm -1 . The refractive index modulation is equal to Δn = 0.004 at E 0 = 54 V/μm. © 2005 Pleiades Publishing, Inc.
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| 13. |
- Grishina, A. D., et al.
(author)
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Fast photorefractive polymer composites based on nanocrystalline J-aggregates of the
- 2004
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In: Synthetic Metals. - : Elsevier BV. - 0379-6779. ; 144:2, s. 113-120
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Journal article (peer-reviewed)abstract
- The hole and electron drift mobility, photoelectric properties as well as influence of temperature, dark current and also relative position of oxidation potentials of the interacting components on photorefractive characteristics of the composites from aromatic polyimide doped with nanocrystalline J-aggregates of a cyanine dye are presented. The nanocrystalline J-aggregates were used as the photosensitizers and also as nonlinear optical chromophores. The experimental electric field dependence of the charge carrier photogeneration efficiency is well fitted by Onsager equation when the quantum yield of the bound thermalized electron-hole pairs φ0=1 and the initial separation of the charges in the pair r0=14.1Å. The charge photogeneration time constant determines the response time of the photorefractive grating formation. The polymer composites exhibit gain coefficient Γ=218cm-1 and response time shorter than 20ms at applied electric field 50V/μm and a intensity of each writing beam 30mW/cm2. The net gain coefficient Γ-α=143cm -1.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Vannikov, A, et al.
(author)
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Effect of cyanine dyes on photoelectric, nonlinear optical and photorefractive properties of composites based on carbon nanotubes
- 2012
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In: Macroheterocycles. - : Ivanovo State University of Chemistry and Technology. - 1998-9539. ; 5:4-5, s. 377-383
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Journal article (peer-reviewed)abstract
- Analysis of photoelectrical, nonlinear optical, and photorefractive properties of composites PVK containing singlewalled carbon nanotubes shows that addition of visible range cyanine dye with high electron affinity into the composites provides considerable increase of quantum efficiency of the mobile charge carries generation at 1064 nm, but reduces the third order susceptibility. As a result, photorefractive gain coefficient Γ of object laser beam increases twofold and achieves after pre-illumination the value 120 cm-1.
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| 18. |
- Vannikov, A, et al.
(author)
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Photoelectric, nonlinear optical, and photorefractive properties of polymer composites including carbon nanotubes and cyanine dyes
- 2013
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In: Physics of the Solid State. - 1063-7834 .- 1090-6460. ; 55:3, s. 572-580
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Journal article (peer-reviewed)abstract
- The effect of cyanine dye additives on the photoelectric, nonlinear optical, and photorefractive properties of polyvinyl carbazole composites based on closed single-walled carbon nanotubes has been investigated. It has been found that these characteristics are affected by the dye in which the lowest unoccupied molecular orbital (LUMO) lies below the level of the photoexcited nanotube. The addition of this dye to the composite leads to a 14-fold increase in the quantum efficiency of the generation of mobile charge carriers under irradiation by a laser (1064 nm) in the absorption region of the nanotubes. Moreover, the addition of the dye to the composite decreases the third-order susceptibility χ (3) , presumably, due to the opposite orientations of dipoles of the dye and the nanotube upon adsorption of the dye on the nanotube. The addition of the dye to the composite also provides a twofold increase in the two-beam photorefractive amplification factor of the laser beam with a wavelength of 1064 nm. The obtained values of the two-beam photorefractive amplification factor reach 120 cm -1 . © 2013 Pleiades Publishing, Ltd.
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| 19. |
- Grishina, AD, et al.
(author)
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Photoelectric and photorefractive properties of polyvinylcarbazole composites with graphene in the visible spectral range
- 2013
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In: High Energy Chemistry. - 0018-1439 .- 1608-3148. ; 47:4, s. 187-191
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Journal article (peer-reviewed)abstract
- The photoelectric and photorefractive characteristics of polyvinylcarbazole (PVK) composites with 0.15 wt % graphene at a wavelength of 532 nm have been measured. The dependence of the quantum efficiency of generation of mobile charge carriers as determined from the photocurrent is well approximated by the Onsager equation calculated accurate to E (0) (3) for the quantum yield of thermalized electron-hole pairs of phi(0) = 1 and their initial separation radius of r (0) = 10.9 . The long-wavelength edge of optical absorption for PVK lies at 365 nm. Thus, the photogeneration of mobile carriers during illumination of the composite at 532 nm is due to photoexcitation of graphene. The measurement of the photorefractive properties has revealed that the two-beam coupling gain coefficient is I" = 50 cm(-1) at E (0) = 150 V/mu m and equal intensities of incident beams. It has been found that at E (0) = 83.3 V/mu m, the two-beam coupling gain coefficient increases from 8 to 14 cm(-1) as the ratio of incident beam intensities I (1)(0)/I (2)(0) increases from 1 to 2.4.
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| 20. |
- Nilsson, Kristofer F., 1981-, et al.
(author)
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Estimation of endogenous adenosine activity at adenosine receptors in guinea-pig ileum using a new pharmacological method
- 2010
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In: Acta Physiologica. - : Blackwell Publishing. - 1748-1708 .- 1748-1716. ; 199:2, s. 231-241
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Journal article (peer-reviewed)abstract
- AIM: Adenosine modulates neurotransmission and in the intestine adenosine is continuously released both from nerves and from smooth muscle. The main effect is modulation of contractile activity by inhibition of neurotransmitter release and by direct smooth muscle relaxation. Estimation of adenosine concentration at the receptors is difficult due to metabolic inactivation. We hypothesized that endogenous adenosine concentrations can be calculated by using adenosine receptor antagonist and agonist and dose ratio (DR) equations.METHODS: Plexus-containing guinea-pig ileum longitudinal smooth muscle preparations were made to contract intermittently by electrical field stimulation in organ baths. Schild plot regressions were constructed with 2-chloroadenosine (agonist) and 8-(p-sulfophenyl)theophylline (8-PST; antagonist). In separate experiments the reversing or enhancing effect of 8-PST and the inhibiting effect of 2-chloroadenosine (CADO) were analysed in the absence or presence of an adenosine uptake inhibitor (dilazep), and nucleoside overflow was measured by HPLC.RESULTS: Using the obtained DR, baseline adenosine concentration was calculated to 28 nm expressed as CADO activity, which increased dose dependently after addition of 10(-6) m dilazep to 150 nm (P < 0.05). HPLC measurements yielded a lower fractional increment (80%) in adenosine during dilazep, than found in the pharmacological determination (440%).CONCLUSION: Endogenous adenosine is an important modulator of intestinal neuro-effector activity, operating in the linear part of the dose-response curve. Other adenosine-like agonists might contribute to neuromodulation and the derived formulas can be used to calculate endogenous agonist activity, which is markedly affected by nucleoside uptake inhibition. The method described should be suitable for other endogenous signalling molecules in many biological systems.
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