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142 results on '"Kononov, E"'

1. Spectrum and energy levels of the high-lying singly excited configurations of Nd III

Author

Ding, M., Ryabtsev, A. N., Kononov, E. Y., Ryabchikova, T., and Pickering, J. C.

Subjects
Physics - Atomic Physics
Abstract

Fourier transform spectra of Nd Penning and hollow cathode discharge lamps were recorded within the region 32,500-54,000 cm$^{-1}$ (3077-1852 {\AA}) and grating spectra of Nd vacuum sliding sparks were recorded within the regions 820-1159 {\AA} and 1600-3250 {\AA}. New energy levels were found using the observed wavelengths measured accurate to a few parts in $10^8$ in Fourier transform spectra and to a few parts in $10^7$ in grating spectra. Atomic structure and transition probability calculations of Nd III were made using the Cowan codes by adjusting energy parameters to fit all known Nd III levels. Nd-rich stellar spectra were also used to evaluate the new calculations. In total, 355 transitions were classified from observed spectra involving 116 previously experimentally unknown energy levels of the 4f$^3$7s, 4f$^3$6d, and 4f$^3$5f configurations of Nd III, all reported here for the first time. One newly identified level of the 4f$^3$5d configuration is also reported. Typical level energy uncertainties are 0.01 cm$^{-1}$ for the 4f$^3$7s and 4f$^3$6d levels and 0.3 cm$^{-1}$ for the 4f$^3$5f levels. In addition, calculated energy levels up to 130,936 cm$^{-1}$ are presented, including eigenvector composition and calculated level lifetimes. Calculated transition probabilities and wavelengths between 1900-50,000 {\AA} are also presented. Using newly established levels of the 4f$^3$7s configuration and the recently established levels of the 4f$^3$6s configuration, the ionisation energy of Nd III was estimated at $178,090\pm330$ cm$^{-1}$, doubling the accuracy of the previously published value.

Published
2024

7. Spectrum and energy levels of the low-lying configurations of Nd III.

Author

Ding, M., Ryabtsev, A. N., Kononov, E. Y., Ryabchikova, T., Clear, C. P., Concepcion, F., and Pickering, J. C.

Subjects
GLOW discharges, ENERGY levels (Quantum mechanics), ATOMIC transition probabilities, STELLAR spectra, THEORY of wave motion, STARS
Abstract

Aims. Our goal is to accurately determine bound-to-bound transition wavelengths and energy levels of the low-lying open-shell configurations 4f4, 4f3 5d, 4f36s, and 4f3 6p of doubly ionised neodymium (Nd III) through high-resolution spectroscopy and semi-empirical calculations. Methods. The emission spectra of neodymium (Nd, Z = 60) were recorded using Penning and hollow cathode discharge lamps in the region 11 500-54000 cm−1 (8695–1852 Å) by Fourier transform spectroscopy at resolving powers up to 106. Wavenumber measurements were accurate to a few 10−3 cm−1. Grating spectroscopy of Nd vacuum sliding sparks and stellar spectra were used to aid line and energy level identification. For the analysis, new Nd III atomic structure and transition probability calculations were carried out using the Cowan code parameterised by newly established levels. Results. The classification of 432 transitions of Nd III from the Penning lamp spectra resulted in the determination of 144 energy levels of the 4f4, 4f3 5d, 4f3 6s, and 4f3 6p configurations of Nd III, 105 of which were experimentally established for the first time. Of the 40 previously published Nd III levels, one was revised and 39 were confirmed. Conclusions. The results will not only benchmark and improve future semi-empirical atomic structure calculations of Nd III, but also enable more reliable astrophysical applications of Nd III, such as abundance analyses of kilonovae and chemically peculiar stars, and studies of pulsational wave propagation in these stars. [ABSTRACT FROM AUTHOR]

Published
2024
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21. OT-82, a novel anticancer drug candidate that targets the strong dependence of hematological malignancies on NAD biosynthesis

Author

Korotchkina, L, Kazyulkin, D, Komarov, PG, Polinsky, A, Andrianova, EL, Joshi, S, Gupta, M, Vujcic, S, Kononov, E, Toshkov, I, Tian, Y, Krasnov, P, Chernov, MV, Veith, J, Antoch, MP, Middlemiss, S, Somers, K, Lock, RB, Norris, MD, Henderson, MJ, Haber, M, Chernova, OB, Gudkov, AV, Korotchkina, L, Kazyulkin, D, Komarov, PG, Polinsky, A, Andrianova, EL, Joshi, S, Gupta, M, Vujcic, S, Kononov, E, Toshkov, I, Tian, Y, Krasnov, P, Chernov, MV, Veith, J, Antoch, MP, Middlemiss, S, Somers, K, Lock, RB, Norris, MD, Henderson, MJ, Haber, M, Chernova, OB, and Gudkov, AV

Abstract

Effective treatment of some types of cancer can be achieved by modulating cell lineage-specific rather than tumor-specific targets. We conducted a systematic search for novel agents selectively toxic to cells of hematopoietic origin. Chemical library screenings followed by hit-to-lead optimization identified OT-82, a small molecule with strong efficacy against hematopoietic malignancies including acute myeloblastic and lymphoblastic adult and pediatric leukemias, erythroleukemia, multiple myeloma, and Burkitt’s lymphoma in vitro and in mouse xenograft models. OT-82 was also more toxic towards patients-derived leukemic cells versus healthy bone marrow-derived hematopoietic precursors. OT-82 was shown to induce cell death by inhibiting nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the salvage pathway of NAD synthesis. In mice, optimization of OT-82 dosing and dietary niacin further expanded the compound’s therapeutic index. In toxicological studies conducted in mice and nonhuman primates, OT-82 showed no cardiac, neurological or retinal toxicities observed with other NAMPT inhibitors and had no effect on mouse aging or longevity. Hematopoietic and lymphoid organs were identified as the primary targets for dose limiting toxicity of OT-82 in both species. These results reveal strong dependence of neoplastic cells of hematopoietic origin on NAMPT and introduce OT-82 as a promising candidate for the treatment of hematological malignancies.

Published
2020

29. Polychlorinated biphenyls in Arctic air. 1. Temporal and spatial trends: 1992-1924

Author

Stern, G. A., Halsall, C. J., Barrie, L. A., Muir, D. C. G., Fellin, P., Rosenberg, B., Rovinsky, F. YA., Kononov, E. YA., and Pastuhov, .

Subjects
Atmospheric research -- Arctic, Arctic research -- Environmental aspects, Polychlorinated biphenyls -- Research, Environmental issues, Science and technology
Abstract

A three-year study that commenced in 1992 examined the airborne concentration of persistent organic pollutants, particularly polychlorinated biphenyls (PCBs), in the Canadian and Russian Arctic. The two sites in Canada, Alert on Ellesmere Island and Tagish in the western Yukon, and the one in Russia at Dunai Island in eastern Sibera, yielded mean PCB concentration of 27.4, 17.0 and 34.0 pg/m3 in 1993, respectively. The sites' proximity to source areas of PCB and the influence of air mass movement from the source regions are the main factors for the spatial and temporal variations in PCB concentrations at the Arctic sites.

Published
1997

30. Spatial and temporal variation of polycyclic aromatic hydrocarbons in the Arctic atmosphere

Author

Halsall, C. J., Barrie, L. A., Fellin, P., Muir, D. C. G., Lockhart, L., Billeck, B. N., Rovinsky, F. Ya., Kononov, E. Ya., and Pastukhov, B.

Subjects
Arctic research -- Environmental aspects, Polycyclic aromatic hydrocarbons -- Research, Atmospheric research -- Arctic, Environmental issues, Science and technology
Abstract

The three-year air sampling program conducted at three locations in the Canadian and Russian Arctic that commenced in 1992 showed spatial and temporal variations on concentrations of polycyclic aromatic hydrocarbons (PAHs) in the Arctic atmosphere. The highest concentrations of PAHs were detected during colder months of October to April, indicating a clear seasonality. PAHs seemed to have traveled far from Eurasia into the high Arctic as evidenced by the air mass back trajectories computed for February 1994.

Published
1997

46. 3D Numerical Simulation Of Gas Flow Around Reentry Vehicles.

Author

Polyakov, S. V., Kudryashova, T. A., Kononov, E. M., and Sverdlin, A. A.

Abstract

Mathematical model of 3D gas flow around reentry vehicle is considered. This model is based on QGD (Quasy-GasDynamics) equations. Numerical methods for solving of these equations on tetrahedral meshes are presented. Parallel realization of these methods is based on MPI and OpenMP technologies. Parallelization is performed using domain decomposition principle. [ABSTRACT FROM AUTHOR]

Published
2011
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47. PCBs in the arctic atmosphere : I : spatial and temporal trends : 1992-1994.

Author

Stern, G. A., Halsall, Crispin J., Barrie, L. A., Muir, D. C. G., Fellin, P., Rosenberg, B., Rovinski, F. Y., Kononov, E. Y., Pastukhov, B. V., Stern, G. A., Halsall, Crispin J., Barrie, L. A., Muir, D. C. G., Fellin, P., Rosenberg, B., Rovinski, F. Y., Kononov, E. Y., and Pastukhov, B. V.

Abstract

In 1992, a long term program was established to measure the airborne concentrations of persistent organic pollutants (POPs) in the Arctic. To maximize spatial variation over a wide geographical area, three Arctic locations were selected; two sites in Canada, Alert on Ellesmere Island and Tagish in the western Yukon, and one in Russia at Dunai Island in eastern Siberia. PCB data is presented here for the years 1992−1994. Mean ∑PCB concentrations for 1993, the year when all three sites were running simultaneously, were 27.4, 17.0, and 34.0 pg/m3 at the Alert, Tagish, and Dunai sites, respectively. With the exception of the Tagish site in 1993, where ∑PCB concentrations were found to be weakly correlated with mean monthly tem peratures, no correlation with temperature was observed. However, changes in the homolog group profile with temperature were apparent. On an annual basis, the trichlorinated congeners made the largest single contribution to the atmospheric concentrations of ∑PCB, however, this contribution declined with the onset of warmer months. This temperature-dependent homolog pattern was most clearly evident at Dunai, where the contribution of the pentachlorinated congeners matched or exceeded that of the trichlorinated congeners during May, June, and July of 1993. It was also evident at Alert and Tagish, but not to the same degree. Spatial and year-to-year differences at these Arctic sites were attributed to both the site's proximity to source areas (where different PCB mixtures and quantities have been used) and to the influence of air mass movement from these source regions.

Published
1997

49. 4 f5 s5 p-4 f5 s5 p6 s transitions in the W VIII spectrum and spectra of isoelectronic hafnium, tantalum, and rhenium ions.

Author

Ryabtsev, A., Kononov, E., Kildiyarova, R., Tchang-Brillet, W., and Wyart, J.

Subjects
SPECTRUM analysis, ISOELECTRONIC sequences, HAFNIUM, TANTALUM, RHENIUM, WAVELENGTHS, SPECTROGRAPHS, DIFFRACTION gratings
Abstract

Spectra of hafnium, tantalum, tungsten, and rhenium in the range of 145-350Å, excited in a low-inductive vacuum spark, have been recorded on a grazing-incidence vacuum spectrograph using a grating with 3600 lines/mm and a radius of 3 m. The wavelengths and intensities of more than 3800 lines in the tungsten spectrum have been measured. Comparison with the Hartree-Fock calculations showed that most spectral lines should be due to transitions in the W VIII spectrum. Short-wavelength lines due to the 4 f5 s5 p-4 f5 s5 p6 s transitions have been identified in the W VIII spectrum and the Re IX, Ta VII, and Hf VI isoelectronic spectra. [ABSTRACT FROM AUTHOR]

Published
2012
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