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Your search keyword '"Tsvetkov, V B"' showing total 17 results
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4. Optical properties of the Bi+ center in KAlCl4

Author

Veber, A. A., Romanov, A. N., Usovich, O. V., Fattakhova, Z. T., Haula, E. V., Korchak, V. N., Trusov, L. A., Kazin, P. E., Sulimov, V. B., and Tsvetkov, V. B.

Subjects
Physics - Optics, Condensed Matter - Materials Science
Abstract

Temperature behavior of the Bi+ center emission, excitation bands and luminescence decay law in KAlCl4 crystal are investigated. Abrupt changes of the monocation optical properties are observed at phase transitions of the host. The observed optical transitions are assigned to the specific energy states of Bi+ ion. It is shown that two thermalized levels are responsible for the luminescence. The experimental temperature behavior of the emission and excitation bands are in agreement with theory of electron-phonon interaction of impurity centers in solids; the effective-phonon frequencies and Huang-Rhys parameters are estimated. The configuration coordinate diagram is determined for the Bi+ center in KAlCl4 crystal.

Published
2013
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5. Luminescent properties of Bi-doped polycrystalline KAlCl4

Author

Veber, A. A., Romanov, A. N., Usovich, O. V., Fattakhova, Z. T., Haula, E. V., Korchak, V. N., Trusov, L. A., Kazin, P. E., Sulimov, V. B., and Tsvetkov, V. B.

Subjects
Physics - Optics, Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter
Abstract

We observed an intensive near-infrared luminescence in Bi-doped KAlCl4 polycrystalline material. Luminescence dependence on the excitation wavelength and temperature of the sample was studied. Our experimental results allow asserting that the luminescence peaked near 1 um belongs solely to Bi+ ion which isomorphically substitutes potassium in the crystal. It was also demonstrated that Bi+ luminescence features strongly depend on the local ion surroundings.

Published
2012
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7. Broadband supercontinuum generation in dispersion decreasing fibers in the spectral range 900–2400 nm

Author

Zhluktova, I. V. (Irina V.), Kamynin, V. A. (Vladimir A.), Korobko, D. A. (Dmitry A.), Abramov, A. S. (Aleksei S.), Fotiadi, A. A. (Andrei A.), Sysoliatin, A. A. (Alexej A.), Tsvetkov, V. B. (Vladimir B.), Zhluktova, I. V. (Irina V.), Kamynin, V. A. (Vladimir A.), Korobko, D. A. (Dmitry A.), Abramov, A. S. (Aleksei S.), Fotiadi, A. A. (Andrei A.), Sysoliatin, A. A. (Alexej A.), and Tsvetkov, V. B. (Vladimir B.)

Abstract

The spectrally flat supercontinuum generation in the wavelength range of 900–2400 nm is demonstrated in silica-based fibers of variable core diameter and dispersion. It is shown that, in comparison with standard optical fibers of the same length, supercontinuum spectra 200 nm wider can be realized in the samples under study. The significant difference between the spectral and temporal transformations of radiation depending on the direction of propagation is demonstrated in the researched fiber samples.

Published
2022

10. Spectroscopy of the yttrium scandate doped by thulium ions

Author

null Tsvetkov V. B., null Vlasov V. I., null Kutovoi S. A., null Guryev D. A., null Voronov V. V., null Kashin V. V., null Rusanov S. Ya., null Alimov O. K., and null Dobretsova E. A.

Abstract

The thulium-doped yttrium scandate crystal fiber has been obtained by the laser-heated pedestal growth method. The crystal belongs to the bixbyite type, has a cubic structure and crystallizes in the Ia3 space group. The lattice parameters (a=10.224(1) Angstrem) have been determined using the powder X-ray diffraction. Spectral-kinetic measurements have allowed to detect two symmetrically independent optical centers of Tm3+ ions in the crystal fiber. Keywords: bixbyite, optical center, rare-earth ion, laser-heated pedestal growth.

Published
2022
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12. Destruction of Renal Concretions with Electrolytic Glow Discharge Plasma.

Author

Ali, S. Kh., Ali, Kh. M., Bezrukov, E. A., Belov, S. V., Danyleiko, Yu. K., Egorov, A. B., Sidorov, V. A., and Tsvetkov, V. B.

Subjects
COST effectiveness, KIDNEY stones, LITHOTRIPSY, MEDICAL technology, RADIO frequency therapy, TREATMENT duration
Abstract

We present results from experimental studies supporting the use of electrolytic glow discharge plasma to destroy renal concretions. The rate of fragmentation of urinary stones was assessed in relation to the power of the plasma discharge and the duration of treatment. The process of plasmakinetic lithotripsy was found to be effective for fragmentation of different types of urinary stone. The results lead to the conclusion that plasmakinetic destruction of renal concretions is a fundamentally novel, effective, and economical method which combines well with technologies using radio-frequency surgery in saline for the treatment of pathological processes in urology. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Near infrared photoluminescence of the univalent bismuth impurity center in leucite and pollucite crystal hosts

Author

Romanov, A. N., Veber, A. A., Vtyurina, D. N., Fattakhova, Z. T., Haula, E. V., Shashkin, D. P., Sulimov, V. B., Tsvetkov, V. B., and Korchak, V. N.

Subjects
Technische Fakultät, ddc:600
Abstract

The bismuth doped aluminosilicate phases leucite (KAlSi2O6), gallium leucite (KGaSi2O6) and pollucite (CsAlSi2O6) display broadband NIR photoluminescence. The active center, responsible for this luminescence, is the Bi+ monocation, which substitutes for the large alkali metal cations. The Al,Si-disorder in the aluminosilicate framework of studied crystal phases results in the heterogeneity of Bi+ luminescent center population, which manifests itself in the characteristic dependency of the luminescence spectrum shape on the excitation wavelength. The relation of NIR emission in Bi+-doped leucite and pollucite phases to the luminescent properties of bismuth-doped glasses is also discussed.

Published
2015

17. EVOLUTIONARY DYNAMICS OF STRUCTURAL AND FUNCTIONAL DOMAINS OF INFLUENZA A VIRUS NS1 PROTEIN.

Author

Vasin AV, Petrova-Brodskaya AV, Plotnikova MA, Tsvetkov VB, and Klotchenko SA

Abstract

Influenza A virus (IAV) NS1 protein is one of the key viral factors responsible for virus-host interactions. NS1 counteracts host antiviral defense, participates in the processing and export of cellular mRNAs, regulates the activity of viral RNA polymerase and the expression of viral genes, and influences the cellular signaling systems. Multiple NS1 functions are carried out due to the interactions with cellular factors, the number of which exceeds one hundred. It is noteworthy that only two segments of IAV genome - NS and NP - did not undergo reassortment and evolved in the course of genetic drift, beginning with the pandemic of 1918 to the present. This fact may indicate the importance of NS1 and its numerous interactions with cellular factors in the interspecific adaptation of the virus. The review presents data on the evolution of the human IAV NS1 protein and analysis of the amino acid substitutions in the main structural and functional domains of NS1 protein during evolution.

Published
2017
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