24 results on '"S. S. Savchenko"'
Search Results
2. Rapid quasi-periodic oscillations in the relativistic jet of BL Lacertae
- Author
-
S. G. Jorstad, A. P. Marscher, C. M. Raiteri, M. Villata, Z. R. Weaver, H. Zhang, L. Dong, J. L. Gómez, M. V. Perel, S. S. Savchenko, V. M. Larionov, D. Carosati, W. P. Chen, O. M. Kurtanidze, A. Marchini, K. Matsumoto, F. Mortari, P. Aceti, J. A. Acosta-Pulido, T. Andreeva, G. Apolonio, C. Arena, A. Arkharov, R. Bachev, M. Banfi, G. Bonnoli, G. A. Borman, V. Bozhilov, M. I. Carnerero, G. Damljanovic, S. A. Ehgamberdiev, D. Elsässer, A. Frasca, D. Gabellini, T. S. Grishina, A. C. Gupta, V. A. Hagen-Thorn, M. K. Hallum, M. Hart, K. Hasuda, F. Hemrich, H. Y. Hsiao, S. Ibryamov, T. R. Irsmambetova, D. V. Ivanov, M. D. Joner, G. N. Kimeridze, S. A. Klimanov, J. Knött, E. N. Kopatskaya, S. O. Kurtanidze, A. Kurtenkov, T. Kuutma, E. G. Larionova, S. Leonini, H. C. Lin, C. Lorey, K. Mannheim, G. Marino, M. Minev, D. O. Mirzaqulov, D. A. Morozova, A. A. Nikiforova, M. G. Nikolashvili, E. Ovcharov, R. Papini, T. Pursimo, I. Rahimov, D. Reinhart, T. Sakamoto, F. Salvaggio, E. Semkov, D. N. Shakhovskoy, L. A. Sigua, R. Steineke, M. Stojanovic, A. Strigachev, Y. V. Troitskaya, I. S. Troitskiy, A. Tsai, A. Valcheva, A. A. Vasilyev, O. Vince, L. Waller, E. Zaharieva, R. Chatterjee, Ministerio de Ciencia e Innovación (España), and European Commission
- Subjects
High-energy astrophysics ,Multidisciplinary ,Astrophysical magnetic fields, High-energy astrophysics, Time-domain astronomy ,Time-domain astronomy ,Astrophysical magnetic fields - Abstract
Full list of authors: Jorstad, S. G.; Marscher, A. P.; Raiteri, C. M.; Villata, M.; Weaver, Z. R.; Zhang, H.; Dong, L.; Gomez, J. L.; Perel, M., V; Savchenko, S. S.; Larionov, V. M.; Carosati, D.; Chen, W. P.; Kurtanidze, O. M.; Marchini, A.; Matsumoto, K.; Mortari, F.; Aceti, P.; Acosta-Pulido, J. A.; Andreeva, T.; Apolonio, G.; Arena, C.; Arkharov, A.; Bachev, R.; Bonnoli, G.; Borman, G. A.; Bozhilov, V; Carnerero, M., I; Damljanovic, G.; Ehgamberdiev, S. A.; Elsasser, D.; Frasca, A.; Gabellini, D.; Grishina, T. S.; Gupta, A. C.; Hagen-Thorn, V. A.; Hallum, M. K.; Hart, M.; Hasuda, K.; Hemrich, F.; Hsiao, H. Y.; Ibryamov, S.; Irsmambetova, T. R.; Ivanov, D., V; Joner, M. D.; Kimeridze, G. N.; Klimanov, S. A.; Knoett, J.; Kopatskaya, E. N.; Kurtanidze, S. O.; Kurtenkov, A.; Kuutma, T.; Larionova, E. G.; Leonini, S.; Lin, H. C.; Lorey, C.; Mannheim, K.; Marino, G.; Minev, M.; Mirzaqulov, D. O.; Morozova, D. A.; Nikiforova, A. A.; Nikolashvili, M. G.; Ovcharov, E.; Papini, R.; Pursimo, T.; Rahimov, I; Reinhart, D.; Sakamoto, T.; Salvaggio, F.; Semkov, E.; Shakhovskoy, D. N.; Sigua, L. A.; Steineke, R.; Stojanovic, M.; Strigachev, A.; Troitskaya, Y., V; Troitskiy, I. S.; Tsai, A.; Valcheva, A.; Vasilyev, A. A.; Vince, O.; Waller, L.; Zaharieva, E.; Chatterjee, R., Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales1,2,3. This variability seems mostly random, although some quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare4 in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet5, plasma instabilities6,7 or orbital motion in an accretion disc7,8. Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref. 9). BL Lac, the prototype of a subclass of blazars10, is powered by a 1.7 × 108 MSun (ref. 11) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref. 12)). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities6 near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image. © 2022 Springer Nature Limited., The research reported here is based on work supported in part by US National Science Foundation grants AST-2108622 and AST-2107806, and NASA Fermi GI grants 80NSSC20K1567, 80NSSC21K1917 and 80NSSC21K1951; by Shota Rustaveli National Science Foundation of Georgia under contract FR-19-6174; by the Bulgarian National Science Fund of the Ministry of Education and Science under grants DN 18-10/2017, DN 18-13/2017, KP-06-H28/3 (2018), KP-06-H38/4 (2019) and KP-06-KITAJ/2 (2020), and by National RI Roadmap Project D01-383/18.12.2020 of the Ministry of Education and Science of the Republic of Bulgaria; by JSPS KAKENHI grant #19K03930 of Japan; by the Ministry of Education, Science and Technological Development of the Republic of Serbia (contract 451-03-9/2021-14/200002) and observing grant support from the Institute of Astronomy and Rozhen NAO BAS through the bilateral joint research project ‘Gaia Celestial Reference Frame (CRF) and fast variable astronomical objects’; by the Agenzia Spaziale Italiana (ASI) through contracts I/037/08/0, I/058/10/0, 2014-025-R.0, 2014-025-R.1.2015 and 2018-24-HH.0 to the Italian Istituto Nazionale di Astrofisica (INAF). H.Z. is supported by the NASA Postdoctoral Program at Goddard Space Flight Center, administered by ORAU. M.V.P. is partially supported by the Russian Foundation for Basic Research grant 20-02-00490. G.B. acknowledges support from the State Agency for Research of the Spanish MCIU through the ‘Center of Excellence Severo Ochoa’ award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709) and from the Spanish ‘Ministerio de Ciencia e Innovacíon’ (MICINN) through grant PID2019-107847RB-C44. M.D.J. thanks the Brigham Young University Department of Physics and Astronomy for continued support of the extragalactic monitoring programme under way at the West Mountain Observatory. R.C. thanks ISRO for support under the AstroSat archival data utilization programme and BRNS for support through a project grant (sanction no. 57/14/10/2019-BRNS). The measurements at the Hans Haffner Observatory, Hettstadt, Germany, were supported by Baader Planetarium, Mammendorf, Germany. This study was based (in part) on observations conducted using the 1.8-m Perkins Telescope Observatory (PTO) in Arizona, USA, which is owned and operated by Boston University. These results made use of the Lowell Discovery Telescope (LDT) at Lowell Observatory. Lowell Observatory is a private, non-profit institution dedicated to astrophysical research and public appreciation of astronomy, and operates the LDT in partnership with Boston University, the University of Maryland and the University of Toledo. This paper is partly based on observations made with the IAC-80 operated on the island of Tenerife by the Instituto de Astrofisica de Canarias in the Spanish Observatorio del Teide and on observations made with the LCOGT telescopes, one of whose nodes is located at the Observatorios de Canarias del IAC on the island of Tenerife in the Observatorio del Teide. This paper is partly based on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The VLBA is an instrument of the NRAO, USA. The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
- Published
- 2022
3. The optical behaviour of BL Lacertae at its maximum brightness levels: a blend of geometry and energetics
- Author
-
C M Raiteri, M Villata, S G Jorstad, A P Marscher, J A Acosta Pulido, D Carosati, W P Chen, M D Joner, S O Kurtanidze, C Lorey, A Marchini, K Matsumoto, D O Mirzaqulov, S S Savchenko, A Strigachev, O Vince, P Aceti, G Apolonio, C Arena, A Arkharov, R Bachev, N Bader, M Banfi, G Bonnoli, G A Borman, V Bozhilov, L F Brown, W Carbonell, M I Carnerero, G Damljanovic, V Dhiman, S A Ehgamberdiev, D Elsaesser, M Feige, D Gabellini, D Galán, G Galli, H Gaur, K Gazeas, T S Grishina, A C Gupta, V A Hagen-Thorn, M K Hallum, M Hart, K Hasuda, K Heidemann, B Horst, W-J Hou, S Ibryamov, R Z Ivanidze, M D Jovanovic, G N Kimeridze, S Kishore, S Klimanov, E N Kopatskaya, O M Kurtanidze, P Kushwaha, D J Lane, E G Larionova, S Leonini, H C Lin, K Mannheim, G Marino, M Minev, A Modaressi, D A Morozova, F Mortari, S V Nazarov, M G Nikolashvili, J Otero Santos, E Ovcharov, R Papini, V Pinter, C A Privitera, T Pursimo, D Reinhart, J Roberts, F D Romanov, K Rosenlehner, T Sakamoto, F Salvaggio, K Schoch, E Semkov, J Seufert, D Shakhovskoy, L A Sigua, C Singh, R Steineke, M Stojanovic, T Tripathi, Y V Troitskaya, I S Troitskiy, A Tsai, A Valcheva, A A Vasilyev, K Vrontaki, Z R Weaver, J H F Wooley, E Zaharieva, and A V Zhovtan
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
In 2021 BL Lacertae underwent an extraordinary activity phase, which was intensively followed by the Whole Earth Blazar Telescope (WEBT) Collaboration. We present the WEBT optical data in the BVRI bands acquired at 36 observatories around the world. In mid 2021 the source showed its historical maximum, with R = 11.14. The light curves display many episodes of intraday variability, whose amplitude increases with source brightness, in agreement with a geometrical interpretation of the long-term flux behaviour. This is also supported by the long-term spectral variability, with an almost achromatic trend with brightness. In contrast, short-term variations are found to be strongly chromatic and are ascribed to energetic processes in the jet. We also analyse the optical polarimetric behaviour, finding evidence of a strong correlation between the intrinsic fast variations in flux density and those in polarisation degree, with a time delay of about 13 h. This suggests a common physical origin. The overall behaviour of the source can be interpreted as the result of two mechanisms: variability on time scales greater than several days is likely produced by orientation effects, while either shock waves propagating in the jet, or magnetic reconnection, possibly induced by kink instabilities in the jet, can explain variability on shorter time scales. The latter scenario could also account for the appearance of quasi-periodic oscillations, with periods from a few days to a few hours, during outbursts, when the jet is more closely aligned with our line of sight and the time scales are shortened by relativistic effects., Comment: 15 pages, 16 figures, submitted to MNRAS
- Published
- 2023
- Full Text
- View/download PDF
4. Variability of the Blazar 1156+295 in 2005–2020
- Author
-
V. A. Hagen-Thorn, D. A. Morozova, S. S. Savchenko, E. I. Hagen-Thorn, Yu. V. Milanova, L. V. Shalyapina, and A. A. Vasil’ev
- Subjects
Space and Planetary Science ,Astronomy and Astrophysics - Published
- 2021
5. Energy Gap Evaluation in Microcrystalline m-HfO2 Powder
- Author
-
Artem O. Shilov, Alexander Vokhmintsev, Andrey V. Chukin, Ilya Weinstein, Maksim I. Vlasov, Maksim S. Karabanalov, and S. S. Savchenko
- Subjects
Materials science ,Microcrystalline ,Band gap ,General Mathematics ,General Physics and Astronomy ,Composite material - Abstract
In this paper optical properties of microcrystalline HfO2 powder are investigated. X-ray diffraction and Raman spectroscopy were used to determine that the studied samples are in monoclinic phase. Based on the analysis of the diffuse reflectance spectra and applying Kubelka-Munk formalism we evaluated the indirect bandgap value Eg = 5.34 ± 0.05 eV. The calculated value is in agreement with independent data for HfO2 thin films synthesized by various methods. The paper is based on the materials of the report presented at the first Russian scientific confererence with the participation of the international community "YENISEI PHOTONICS – 2020"
- Published
- 2021
6. Exciton–Phonon Interactions and Temperature Behavior of Optical Spectra in Core/Shell InP/ZnS Quantum Dots
- Author
-
Alexander Vokhmintsev, Ilya Weinstein, and S. S. Savchenko
- Subjects
Core (optical fiber) ,Condensed Matter::Materials Science ,Materials science ,Phonon ,Quantum dot ,Exciton ,Excited state ,Shell (structure) ,Spectral bands ,Atmospheric temperature range ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Molecular physics - Abstract
The chapter summarizes research results on temperature evolution of optical absorption spectra in a wide temperature range of 6.5–296 K for colloidal core/shell InP/ZnS quantum dot ensembles with a different size distribution. Exciton–optical transition energies in the InP core and ZnS shell were determined by the second-order derivative spectrophotometry. Numerical analysis within the frame of linear exciton–phonon coupling showed that the shifts of the observed spectral maxima with temperature were due to the interaction of excited states with longitudinal acoustic vibrations. It was established that the half-width of the spectral bands remained unchanged, which indicated the inhomogeneous broadening effect and a high degree of static disorder in the ensembles under study. The semi-phenomenological model was proposed that took into account the effects of the exciton–phonon interaction and allowed one to analyze the influence of the static and dynamic types of atomic disorder on behavior of optical absorption spectra in InP/ZnS quantum dots under temperature variation.
- Published
- 2020
7. Optical parameters and energy gap estimation in hafnia thin film
- Author
-
S. S. Savchenko, V. A. Gritsenko, A. S. Vokhmintsev, A. O. Shilov, and I. A. Weinstein
- Subjects
3D optical data storage ,Materials science ,biology ,business.industry ,Band gap ,Physics::Optics ,Molar absorptivity ,Hafnia ,biology.organism_classification ,Condensed Matter::Materials Science ,Absorption edge ,Dispersion (optics) ,Optoelectronics ,Thin film ,business ,Refractive index - Abstract
Optical absorption spectra of HfO2 thin film synthesized by ion beam sputtering deposition technique were studied. Interference effects were used to determine film thickness, which was d=288 nm, and to calculate dispersion curves for refractive index, extinction coefficient and both real and imaginary parts of dielectric permittivity. Optical data near intrinsic absorption edge were analyzed to estimate the energy gap of Eg = 5.40±0.05 eV in the hafnia film under research.
- Published
- 2020
8. Temperature dependence of the optical absorption spectra of InP/ZnS quantum dots
- Author
-
Ilya Weinstein, S. S. Savchenko, and Alexander Vokhmintsev
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,medicine.diagnostic_test ,Exciton ,Shell (structure) ,02 engineering and technology ,Atmospheric temperature range ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Spectral line ,0104 chemical sciences ,Core (optical fiber) ,Condensed Matter::Materials Science ,Quantum dot ,Spectrophotometry ,medicine ,Atomic physics ,0210 nano-technology ,Absorption (electromagnetic radiation) - Abstract
The optical-absorption spectra of InP/ZnS (core/shell) quantum dots have been studied in a broad temperature range of T = 6.5–296 K. Using the second-order derivative spectrophotometry technique, the energies of optical transitions at room temperature were found to be E 1 = 2.60 ± 0.02 eV (for the first peak of excitonic absorption in the InP core) and E 2 = 4.70 ± 0.02 eV (for processes in the ZnS shell). The experimental curve of E 1(T) has been approximated for the first time in the framework of a linear model and in terms of the Fan’s formula. It is established that the temperature dependence of E 1 is determined by the interaction of excitons and longitudinal acoustic phonons with hω = 15 meV.
- Published
- 2017
9. IDENTIFICATION OF CAUSATIVE AGENTS OF GLANDERS AND MELIOIDOSIS BASED ON PRINCIPLES OF POLYPHASE TAXONOMIC APPROACH
- Author
-
Ya A Lopasteiskaya, S. S. Savchenko, Antonov Va, E E Kim, G. A. Tkachenko, E V Prokhvatilova, T V Zamarina, Merinova Lk, Khrapova Np, Senina Tv, I I Korsakova, E V Pimenova, E V Molchanova, and N P Ageeva
- Subjects
0301 basic medicine ,Melioidosis ,biology ,030106 microbiology ,Glanders ,Medicine (miscellaneous) ,glanders and melioidosis causative agents ,General Medicine ,Computational biology ,biology.organism_classification ,medicine.disease ,Microbiology ,QR1-502 ,intra-species typing ,03 medical and health sciences ,Genetic typing ,Burkholderia ,medicine ,Identification (biology) ,monoclonal antibodies ,Typing ,pathogenic burkholderia genomes - Abstract
Aim. Determine an optimal set of the most effective methods of identification and intraspecies typing of causative agents of glanders and melioidosis. Materials and methods. Bacteriologic, immunochemical, molecular-genetic methods were used. Results. A possibility to identify collection strains of pathogenic and closely related Burkholderia in semiautomatic systems is studied. Means of detection of informative variable genome segments of the specified microorganisms were developed, methods of their genetic typing were selected. Effectiveness of application of precipitating mAbs for differentiation of Burkholderia was established. Data on diagnostic possibilities of immunoglobulins fluorescing based on monoclonal antibodies of various etiotropic directionality for detection and identification of B. mallei and B. pseudomallei are generalized. Experimental series of amplification test-systems for identification of glanders and melioidosis causative agents in real-time PCR format are created. Conclusion. A number of methods for identification and typing of glanders and melioidosis causative agents is proposed.
- Published
- 2016
10. [IDENTIFICATION OF CAUSATIVE AGENTS OF GLANDERS AND MELIOIDOSIS BASED ON PRINCIPLES OF POLYPHASE TAXONOMIC APPROACH]
- Author
-
I I, Korsakova, V A, Antonov, N P, Khrapova, T V, Zamarina, E V, Pimenova, E E, Kim, L K, Merinova, T V, Senina, G A, Tkachenko, S S, Savchenko, N P, Ageeva, E V, Molchanova, Ya A, Lopasteiskaya, and E V, Prokhvatilova
- Subjects
Burkholderia pseudomallei ,Melioidosis ,Glanders ,Animals ,Humans ,Real-Time Polymerase Chain Reaction ,Burkholderia mallei - Abstract
Determine an optimal set of the most effective methods of identification and intraspecies typing ofcausative agents ofglanders and melioidosis. Materials andmethods. Bacteriologic, immunochemical, molecular-genetic methods were used.A possibility to identify collection strains of pathogenic and closely related Burkholderia in semiautomatic systems is studied. Means of detection of informative variable genome segments ofthe specified microorganisms were developed, methods of their genetic typing were selected. Effectiveness of application of precipitating mAbs for differentiation of Burkholderia was established. Data on diagnostic possibilities of immunoglobulins fluorescing based on monoclonal antibodies of various etiotropic directionality for detection and identification of B. mallei and B. pseudomallei are generalized. Experimental series of amplification test-systems for identification of glanders and melioidosis causative agents in real-time PCR format are created.A number of methods for identification and typing of glanders and melioidosis causative agents is proposed.
- Published
- 2019
11. Burkholderia mallei genotyping based on different region analysis
- Author
-
L. V. Lemasova, S. S. Savchenko, G. A. Tkachenko, M. L. Ledeneva, O. S. Bondareva, and Antonov Va
- Subjects
0301 basic medicine ,biology ,Strain (biology) ,030106 microbiology ,Glanders ,Computational biology ,Pathogenicity ,biology.organism_classification ,medicine.disease ,Microbiology ,Virology ,03 medical and health sciences ,Burkholderia mallei ,Infectious Diseases ,Genetics ,Epidemiological surveillance ,medicine ,Molecular Biology ,Genotyping ,Region analysis - Abstract
The development of methods for glanders agent genotyping is urgent due to the high pathogenicity of this microbe, lack of effective preventive measures, and threat of the use of Burkholderia mallei as a biological weapon. In this study, we propose a scheme for genotyping of B. mallei strains based on different region analysis (DFR). The choice of variable loci specific for different strains of the glanders agent was performed by analyzing the annotated whole-genome sequences of the B. mallei strains. Primers and fluorescence probes were designed for nine selected loci. The amplification conditions for different regions were optimized in two variants: with electrophoretic detection and hybridization-fluorescence detection in the strip format. DFR analysis was assessed in 14 B. mallei strains. The strain genetic profiles revealed that developed DFR-typing was characterized by a high discrimination power (Hunter–Gaston index was 0.92), reproducibility, rapidity, easy interpretation, and applicability for epidemiological surveillance of glanders.
- Published
- 2016
12. Spectral Features and Luminescence Thermal Quenching of InP/ZnS Quantum Dots within 7.5 – 295 K Range
- Author
-
Ilya Weinstein, S. S. Savchenko, and Alexander Vokhmintsev
- Subjects
Range (particle radiation) ,Materials science ,business.industry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,010309 optics ,Quantum dot ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,Luminescence ,business ,Thermal quenching - Published
- 2018
13. Modern approaches to genotyping of causative agents of particularly dangerous infections
- Author
-
V. A. Antonov, S. S. Savchenko, Yu. O. Muratova, A. I. Abueva, G. A. Tkachenko, and O. S. Bondareva
- Subjects
medicine.medical_specialty ,medicine ,Biology ,Intensive care medicine ,Genotyping - Abstract
Currently genotyping of microorganisms is widely used in the investigation of outbreaks of infectious diseases, the implementation of epidemiological surveillance of infections and phylogenetic analysis of bacterial pathogens. Development of methods for genotyping is particularly topical for pathogens of such highly dangerous infections as plague, cholera, anthrax, brucellosis, tularemia, glanders and melioidosis, due to their high pathogenicity and contagiousness. In this overview there is presented the characteristics of different genotyping methods together with an indication of their advantages and drawbacks. There has been analyzed the frequency of the use of genotyping methods on an annual basis and in terms of the type of the causative agents of especially dangerous infections.
- Published
- 2014
14. [GENOTYPING OF THE BURKHOLDERIA MALLEI STRAINS BASED ON DIFFERENT REGION ANALYSIS]
- Author
-
O S, Bondareva, S S, Savchenko, G A, Tkachenko, M L, Ledeneva, L V, Lemasova, and V A, Antonov
- Subjects
DNA, Bacterial ,Genotyping Techniques ,Glanders ,Animals ,Humans ,Burkholderia mallei ,Polymerase Chain Reaction ,Russia - Abstract
Development of the genotyping methods of glanders agent is urgent due to its high pathogenicity, lack of effective preventive measures and threat of the use of Burkholderia mallei as a biological weapon. In this work we proposed a scheme for the typing of the B. mallei strains based on different region analysis (DFR). The choice of variable loci differentially presented in various strains of glanders agents was performed by analyzing annotated whole-genome sequences of the B. mallei strains. Primers and fluorescence probes were designed for 9 selected loci. The amplification conditions for different regions were optimized in two variants: with electrophoretic detection and hybridization-fluorescence detection in the strip format. The possibility of applying the DFR analysis to genetic characterization of strains was assessed in 14 B. mallei strains. The genetic profiles of the studied B. mallei strains revealed that the developed DFR-typing scheme was characterized by high discrimination power (Hunter-Gaston index value was 0.92), reproducibility, rapidity, easy interpretation, and applicability for epidemiological surveillance of glanders.
- Published
- 2016
15. Luminescence parameters of InP/ZnS@AAO nanostructures
- Author
-
Alexander Vokhmintsev, Ilya Weinstein, and S. S. Savchenko
- Subjects
Membrane ,Photoluminescence ,Materials science ,Nanocrystal ,business.industry ,Quantum dot ,Optoelectronics ,Nanotechnology ,Phosphor ,Color temperature ,Chromaticity ,Luminescence ,business - Abstract
Nanostructured membranes of anodic aluminum oxide (AAO) with InP/ZnS semiconductor nanocrystals deposited in pores were synthesized by electrochemical technique, physical deposition and post processing in an ultrasonic bath. Photoluminescence spectra of the samples were studied. Fluorescent properties of the quantum dots are found to be retained after the deposition. The color range is illustrated that can be covered using membranes annealed at temperatures < 900°C and by varying the concentration of the deposited InP/ZnS nanocrystals. Chromaticity coordinates and correlated color temperature for the fabricated white InP/ZnS@AAO phosphor are (0.21, 0.26) and 4115 K, respectively.
- Published
- 2016
16. Automatized channel for resistivity measurements in layered materials by four-point probe technique
- Author
-
Alexander Vokhmintsev, Ilya Weinstein, S. S. Savchenko, and A. O. Gryaznov
- Subjects
Microprobe ,Materials science ,Cascade ,Electrical resistivity and conductivity ,business.industry ,Analytical chemistry ,Optoelectronics ,Sputter deposition ,business ,Electrical conductor ,Quartz ,Multimeter ,Line (electrical engineering) - Abstract
An automatized channel for measuring the resistivity in materials by the four-point probe technique was developed. The installation was based on Cascade Microtech MPS150 microprobe station, National Instruments PXIe-4143 power supply unit and PXI-4072 digital multimeter. Registration modes of surface and bulk specific resistance for samples with positioning the probes in a line or at square vertices were implemented. Measurements under corresponding modes were carried out for metallic, semiconducting bulk samples and thin coatings. Conductive and optical properties of 10, 20 and 30 nm Au layers formed on quartz glass by magnetron sputtering were investigated.
- Published
- 2016
17. On estimation of the pitch angle for spiral arms of galaxies
- Author
-
S. S. Savchenko
- Subjects
Physics ,Spiral galaxy ,Logarithm ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Radius ,Astrophysics ,Grand design spiral galaxy ,Galaxy ,symbols.namesake ,Computer Science::Sound ,Fourier analysis ,symbols ,Pitch angle ,Interacting galaxy ,Instrumentation ,Astrophysics::Galaxy Astrophysics - Abstract
The shape of the arms of spiral galaxies is usually described by logarithmic spiralswith constant pitch angles, however, some galaxies display variations of the pitch angle along their spiral arms. We propose a method of determining the pitch angle of the arms in spiral galaxies based on the window Fourier analysis of their images. This method allows us not only to infer the average pitch angle, but also to obtain its value as a function of galactocentric radius. The method is implemented in the form of freely available programs.
- Published
- 2012
18. Modern Approaches for Detection of Glanders and Melioidosis. Identification and Typing of Burkholderia mallei and Burkholderia pseudomallei
- Author
-
Alekseev Vv, A. A. Budchenko, V. V. Alekseeva, Yu. I. Sorokina, E V Prokhvatilova, D. V. Viktorov, O. V. Zinchenko, S. S. Savchenko, Senina Tv, V. I. Ilyukhin, I. B. Zakharova, G. A. Tkachenko, Khrapova Np, and V. A. Antonov
- Subjects
Microbiology (medical) ,Infectious Diseases ,Melioidosis ,Genetic typing ,Epidemiology ,Immunology ,Glanders ,medicine ,Typing ,Biology ,medicine.disease ,Microbiology - Abstract
Analysed are the methodological approaches used for identification and typing of B. mallei and B. pseudomallei . Suggested are recommendations for improvements of algorithms of laboratory diagnosis of glanders and melioidosis including wide range of biochemical, immunodiagnostic and molecular genetic methods.
- Published
- 2012
19. Identification of coccidioidomycosis causative agent by means of polymerase chain reaction
- Author
-
Antonov Va, Zamaraev Vs, Grishina Ma, G. A. Tkachenko, A. V. Lipnitskii, S. S. Savchenko, and V. S. Lesovoi
- Subjects
Coccidioides species ,Biology ,biology.organism_classification ,Microbiology ,DNA extraction ,Virology ,law.invention ,Highly sensitive ,Infectious Diseases ,law ,Genetics ,Identification (biology) ,Coccidioides ,Molecular Biology ,Gene ,Polymerase chain reaction ,Specific identification - Abstract
For the purpose of diagnosing coccidioidomycosis by means of PCR, two pairs of primers were constructed. The first one was developed on the basis of MBP-I gene to be used for identification of two Coccidioides species, C. immitis and C. posadasii. The other pair of primers was constructed on the basis of the gene encoding immunodominant glycoprotein of the spherule outer wall (SOW gp82) to be used for identification of C. posadasii. With these primers, both highly sensitive and highly specific identification of coccidioidomycosis causative agents proved to be possible. An efficient procedure was developed for isolation of fungal DNA from soil contaminated with Coccidioides spp. arthrospores. This procedure includes guanidine thiocyanate-phenol-chloroform deproteinization followed by DNA purification by means of nucleosorption.
- Published
- 2007
20. The use of multilocus sequence typing (MLST) and randomly amplified polymorphic DNA (RAPD) to differentiate among strains of the glanders pathogen Burkholderia mallei
- Author
-
Zamaraev Vs, V. I. Ilyukhin, S. S. Savchenko, Alekseev Vv, Antonov Va, and V. V. Altukhova
- Subjects
Genetics ,Highly pathogenic ,Glanders ,Biology ,bacterial infections and mycoses ,medicine.disease ,biology.organism_classification ,Microbiology ,RAPD ,chemistry.chemical_compound ,Burkholderia mallei ,Infectious Diseases ,chemistry ,Virology ,medicine ,Multilocus sequence typing ,Molecular Biology ,Pathogen ,Genotyping ,DNA - Abstract
The glanders pathogen (Burkholderia mallei) is a highly pathogenic microorganism for humans and animals. In this article we studied the possibility of using genotyping methods for the differentiation of B. mallei strains. We characterized 14 strains of the glanders pathogen using amplification with random primers (randomly amplified polymorphic DNA, RAPD) and multilocus sequence typing (MLST). It was shown that RAPD was the best of the methods used for differentiating B. mallei strains, and it may therefore be more useful for molecular-epidemiological investigations.
- Published
- 2007
21. [The comparative evalution of informativeness of immunologic and molecular genetic methods and means during stages of specific indication of melioidosis agent]
- Author
-
E V, Prokhvatilova, V A, Antonov, D V, Viktorov, N P, Khrapova, G A, Tkachenko, V I, Iliukhin, I B, Zakharova, M A, Grishina, N G, Plekhanova, I V, Novickaia, M Ia, Kulakov, T V, Bulatova, I I, Korsakova, S S, Savchenko, O S, Bondareva, N N, Teteriatnikova, T V, Senina, Ia A, Lopasteĭskaia, A A, Baturin, and A S, Kulikova
- Subjects
Melioidosis ,Burkholderia ,Glanders ,Animals ,Humans ,Horses ,Polymerase Chain Reaction ,Bacterial Typing Techniques - Abstract
The reference-center of monitoring of agents of glanders and melioidosis carried out testing of reagents kits for diagnostic of agent of melioidosis and other close-related species of Burkholderiae in vitro. At the stage of specific identification of pathogenic Burkholderiae the diagnostic possibilities of commercial and experimental kits of reagents for express- and rapid analysis were evaluated. The criteria of evaluation of diagnostic value of kits of reagents were sensitivity, specificity and time of implementation of studies. The analysis with application of mono- and multi-locus amplification systems, including real-time polymerase chain reaction permitted during 5-6 hours to implement identification and differentiation of Burkholderia pseufomallei, B. thailandensis and B. cepacia.
- Published
- 2015
22. [Molecular genetic analysis of Pseudomonas aeruginosa strains isolated from environment and patients in health care facilities]
- Author
-
V A, Antonov, V V, Altukhova, S S, Savchenko, G A, Tkachenko, V S, Zamaraev, S I, Zhukova, O G, Kramar', N L, Matveeva, O V, Ostrovskiĭ, and G P, Dudchenko
- Subjects
Urban Population ,Virulence Factors ,Pseudomonas aeruginosa ,Humans ,Pseudomonas Infections ,Polymerase Chain Reaction ,Sensitivity and Specificity ,DNA Primers ,Plasmids ,Random Amplified Polymorphic DNA Technique ,Russia - Abstract
Analysis of genetic heterogeneity of Pseudomonas aeruginosa strains isolated in and out of hospitals.To study the genetic diversity of 36 strains of P. aeruginosa plasmid analysis, random amplified polymorphic DNA (RAPD) technique as well as polymerase chain reaction for detection of virulence genes algD, lasB, toxA, plcH, plcN, exoS, nan1, and nan2.Epidemically important strains were found in different ecological niches. It was shown that these virulence factors could play important roles in pathogenesis of infection.RAPD technique was effective for analysis of P. aeruginosa isolates. Number of studied typing bands differed between related isolates for each random primer.
- Published
- 2010
23. [Identification of the agents of coccidioidomycosis using polymerase chain reaction]
- Author
-
G A, Tkachenko, M A, Grishina, V A, Antonov, S S, Savchenko, V S, Zamaraev, V S, Lesovoĭ, and A V, Lipnitskiĭ
- Subjects
Antigens, Fungal ,Coccidioidomycosis ,Membrane Glycoproteins ,Coccidioides ,Genes, Fungal ,Humans ,DNA, Fungal ,Polymerase Chain Reaction ,DNA Primers - Abstract
Two pairs of primers for diagnosis of coccidioidomycosis using the method of PCR were constructed. One pair was used for identification of the two species of Coccidioides (C. immitis and C. posadasil) on the basis of MBP-1 gene. The other pair was chosen on the basis of SOWgp82 gene, which encodes an immunodominant, spherule outer wall glycoprotein for detecting only C. posadasii. The used primers allowed the agents of coccidioidomycosis to be detected using PCR with high sensitivity and specificity. The effective method of isolation of fungus DNA from soil contaminated with arthroconidia of Coccidioides spp. was developed. It includes guanidinthiocyanate-phenol-chloroform deproteinization followed by DNA purification using nuclear sorption.
- Published
- 2007
24. [The use of multilocus sequence typing (MLST) and randomly amplified polymorphic DNA (RAPD) for the differentiation between strains of Burkholderia mallei]
- Author
-
V A, Antonov, V V, Altukhova, S S, Savchenko, V S, Zamaraev, V I, Iliukhin, and V V, Alekseev
- Subjects
Molecular Epidemiology ,Polymorphism, Genetic ,Species Specificity ,Quantitative Trait Loci ,Sequence Analysis, DNA ,Burkholderia mallei ,Random Amplified Polymorphic DNA Technique - Abstract
Burkholderia mallei is highly pathogenic microorganism for both humans and animals. In this work, the possibility of the use of the genotyping method for differentiation between strains of B. mallei was studied. A collection of 14 isolates of B. mallei was characterized using randomly amplified polymorphic DNA (RAPD) and multilocus sequence typing (MLST). RAPD was the best method used for detecting strain differences of B. mallei. It was suggested that this method would be an increasingly useful molecular epidemiological tool.
- Published
- 2007
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.