Evolution of electrical and electrodynamic properties of YBa2Cu3O7-x bicrystal Josephson junctions with oxygen loading

The IV-curves and dynamic resistances R-d(V) of [001]-tilt YBa2Cu3O7-x bicrystal Josephson junctions have been experimentally studied at various levels of oxygen loading. Oxygen content was modified by annealing in ozone atmosphere, in vacuum or in air. Deviations of the IV-curves from those predicted by the RSJC model in the form of additional nonlinearities at the middle and high voltages were found to decrease after enhancement of oxygen content in junctions. Electrodynamic properties of Josephson junctions were analyzed using log-periodic YBa2Cu3O7-x antennas, integrated with the junctions. Fine structures on the IV-curves, related to antenna resonances, were modified with oxygen content due to better antenna-junction coupling and lower electromagnetic losses in YBa2Cu3O7-x film

Trimming of high-Tc bicrystal Josephson junctions by ozone and vacuum annealing

AbstractSpecific values of characteristic voltages IcRn and normal-state resistances Rn of high-Tc Josephson junctions (JJ) are often required for their THz applications in detection and spectroscopy. Recently, evolution of these electrical parameters of [001]-tilt YBa2Cu3O7-x bicrystal JJ after low-temperature ozone annealing has been studied. Here, we present the effect of ozone and vacuum annealing on the IV-curves of [100]-tilt YBa2Cu3O7-x bicrystal JJ. Annealing temperature Ta was varied from 100°C to 225°C. It was demonstrated, that annealing in ozone-oxygen mixture and in vacuum has an opposite effect on JJ parameters, and the changes were reversible at Ta up to 145°C. Ozone annealing at Ta=100°C resulted in up to 1.5 times decrease of Rn. After annealing in vacuum at higher Ta, a transition temperature Tc of JJ electrodes was reduced from 90K to 52K, and significant, multifold changes of IcRn and Rn were observed. Further annealing in ozone at Ta up to 225°C restored Tc and Rn almost to their initial values, but IcRnvalues couldn’t be increased above 20% of the initial value. The obtained results can be used for trimming of junction parameters after main fabrication procedure

Accumulation of storage proteins in plant seeds is mediated by amyloid formation

Copyright: © 2020 Antonets et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Amyloids are protein aggregates with a highly ordered spatial structure giving them unique physicochemical properties. Different amyloids not only participate in the development of numerous incurable diseases but control vital functions in archaea, bacteria and eukarya. Plants are a poorly studied systematic group in the field of amyloid biology. Amyloid properties have not yet been demonstrated for plant proteins under native conditions in vivo. Here we show that seeds of garden pea Pisum sativum L. contain amyloid-like aggregates of storage proteins, the most abundant one, 7S globulin Vicilin, forms bona fide amyloids in vivo and in vitro. Full-length Vicilin contains 2 evolutionary conserved β-barrel domains, Cupin-1.1 and Cupin-1.2, that self-assemble in vitro into amyloid fibrils with similar physicochemical properties. However, Cupin-1.2 fibrils unlike Cupin-1.1 can seed Vicilin fibrillation. In vivo, Vicilin forms amyloids in the cotyledon cells that bind amyloid-specific dyes and possess resistance to detergents and proteases. The Vicilin amyloid accumulation increases during seed maturation and wanes at germination. Amyloids of Vicilin resist digestion by gastrointestinal enzymes, persist in canned peas, and exhibit toxicity for yeast and mammalian cells. Our finding for the first time reveals involvement of amyloid formation in the accumulation of storage proteins in plant seeds

Search for Stop Production in RR-Parity-Violating Supersymmetry at HERA.

A search for stop production in R-parity-violating supersymmetry has been performed in $e^{+}p$ interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb$^{-1}$. At HERA, the R-parity-violating coupling $\lambda'$ allows resonant squark production, $e^+d\to\tilde{q}$. Since the lowest-mass squark state in most supersymmetry models is the light stop, $\tilde{t}$, this search concentrated on production of $\tilde{t}$, followed either by a direct R-parity-violating decay, or by the gauge decay to $b\tilde{\chi}^+_{1}$. No evidence for stop production was found and limits were set on $\lambda'_{131}$ as a function of the stop mass in the framework of the Minimal Supersymmetric Standard Model. The results have also been interpreted in terms of constraints on the parameters of the minimal Supergravity model.Comment: 24 pages, 11 figures, 1 table, Accepted by European Physical Journal