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- Galin, Mikhail A., et al.
(författare)
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Synchronization of Large Josephson-Junction Arrays by Traveling Electromagnetic Waves
- 2018
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Ingår i: Physical Review Applied. - 2331-7019. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Mutual synchronization of many Josephson junctions is required for superradiant enhancement of the emission power. However, the larger the junction array is, the more difficult is the synchronization, especially when the array size becomes much larger than the emitted wavelength. Here, we study experimentally Josephson emission from such larger-than-the-wavelength Nb/NbSi/Nb junction arrays. For one of the arrays we observe a clear superradiant enhancement of emission above a threshold number of active junctions. The arrays exhibit strong geometrical resonances, seen as steps in current-voltage characteristics. However, radiation patterns of the arrays have forward-backward asymmetry, which is inconsistent with the solely geometrical resonance (standing-wave) mechanism of synchronization. We argue that the asymmetry provides evidence for an alternative mechanism of synchronization mediated by unidirectional traveling-wave propagation along the array (such as a surface plasmon). In this case, emission occurs predominantly in the direction of propagation of the traveling wave. Our conclusions are supported by numerical modeling of Josephson traveling-wave antenna. We argue that such a nonresonant mechanism of synchronization opens a possibility for phase locking of very large arrays of oscillators.
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- Khotin, M.G., et al.
(författare)
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Analysis of nuclear protein complexes comprising a-actinin-4 by 2D-electrophoresis and mass-spectrometry
- 2009
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Ingår i: Tsitologiya. - : SP MAIK Nauka/Interperiodica. - 0041-3771. ; 51:8, s. 684-690
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Tidskriftsartikel (refereegranskat)abstract
- Actin-binding protein a-actinin-4 is a member of spectrin super family. It is located in the cytoplasm and in the nucleus. However, nuclear functions of a-actinin-4 are still not clear. In this study, we analyzed composition of nuclear protein complexes associated with a-actinin-4 in A431 cells. Using 2D electrophoresis, we have determined that about 50 different proteins may be associated with nuclear a-actinin-4. Using mass-spectrometry, we analyzed major proteins of these complexes. ß-Actin, a- and ß-tubulins, ribonucleoprotein A2/B1, which regulates splicing and is associated with ß-actin, peroxiredoxin-1, which is involved in oxidative stress, and glycolytic enzyme D-3-phosphoglycerate dehydrogenase were identified by MALDI-TOF. Detection of these proteins in nuclear complexes with a-actinin-4 may suggest that a-actinin-4 is involved in transcription and splicing. Presence of a-actin in the investigated complexes was confirmed by tandem mass-spectrometry (MALDITOF-TOF). Immunoprecipitation of nuclear proteins with antibodies against a-tubulin confirmed association of a-actinin-4 with a-tubulin in the protein complex. Nuclear a-actinin-4 constitutes of 105 KDa fullsize isoform and two truncated isoforms of 65 and 75 kDa, whereas only the truncated isoform have been found in nuclear complexes with a-tubulin. These data suggest that a-actinin-4 is associated with a number of different nuclear protein complexes which may carry out different functions in the cell nucleus.
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