Rearrangement of the vortex lattice due to instabilities of vortex flow

With increasing applied current we show that the moving vortex lattice changes its structure from a triangular one to a set of parallel vortex rows in a pinning free superconductor. This effect originates from the change of the shape of the vortex core due to non-equilibrium effects (similar to the mechanism of vortex motion instability in the Larkin-Ovchinnikov theory). The moving vortex creates a deficit of quasiparticles in front of its motion and an excess of quasiparticles behind the core of the moving vortex. This results in the appearance of a wake (region with suppressed order parameter) behind the vortex which attracts other vortices resulting in an effective direction-dependent interaction between vortices. When the vortex velocity $v$ reaches the critical value $v_c$ quasi-phase slip lines (lines with fast vortex motion) appear which may coexist with slowly moving vortices between such lines. Our results are found within the framework of the time-dependent Ginzburg-Landau equations and are strictly valid when the coherence length $\xi(T)$ is larger or comparable with the decay length $L_{in}$ of the non-equilibrium quasiparticle distribution function. We qualitatively explain experiments on the instability of vortex flow at low magnetic fields when the distance between vortices $a \gg L_{in} \gg \xi (T)$. We speculate that a similar instability of the vortex lattice should exist for $v>v_c$ even when $a<L_{in}$.Comment: 10 pages, 11 figure

AC Josephson properties of phase slip lines in wide tin films

Current steps in the current-voltage characteristics of wide superconducting Sn films exposed to a microwave irradiation were observed in the resistive state with phase slip lines. The behaviour of the magnitude of the steps on the applied irradiation power was found to be similar to that for the current steps in narrow superconducting channels with phase slip centers and, to some extent, for the Shapiro steps in Josephson junctions. This provides evidence for the Josephson properties of the phase slip lines in wide superconducting films and supports the assumption about similarity between the processes of phase slip in wide and narrow films.Comment: 7 pages, 2 figures, to be published in Supercond. Sci. Techno

Assay of nitrofuran drugs using an amperometric monoamine oxidase biosensor

A method for assaying nitrofuran drugs (furazolidone, furadonine, and furagin) using an amperometric biosensor based on a printed platinum electrode and immobilized monoamine oxidase was developed for analysis of medicinal formulations and urine. Nitrofuran derivatives were found to have inhibitory actions, albeit weaker than those of classical tricyclic antidepressants, on the catalytic activity of monoamine oxidase. This side-effect inhibitory action allowed assay of furazolidone, furadonine, and furagin with lower detection limits, which were 8.3 × 10-9, 8.5 × 10-8, and 9.4 × 10-10 M respectively. The results obtained here show that this side effect of furazolidone, furadonine, and furagin must be taken into consideration when these agents are prescribed to patients. © 2011 Springer Science+Business Media, Inc

CRITICAL CURRENT HYSTERESIS DUE TO ELECTRON OVERHEAT IN NARROW SUPERCONDUCTING FILMS

On a étudié l'hystérésis des caractéristiques courant-tension des couches minces supraconductrices d'étain et d'indium dans un large intervalle de température. On a montré, que si ce transfert de chaleur est parfait, la valeur de l'hystérésis et sa variation avec latemperature s'accordent avec les résultats de la théorie de Shklovski, expliquant l'apparition de l'hystérésis par la surchauffe des électrons par rapport au réseau. Sur ces mêmes couches, on a découvert l'influence de la surchauffe des électrons sur la valeur de la résistance thermique de l'interface métal-isolant.The hysteresis of IVC has been studied on thin superconducting films of tin and indium in a wide temperature range. It has been shown that under perfect heat transfer, the value of hysteresis and its temperature dependence are in agreement with the results of Shklovsky's theory according to which the hysteresis is due to electron overheat with respect to the lattice. The effect of electron overheat on thermal resistivity of a metal-insulator interface has been found

Mixed variational inequalities and economic equilibrium problems

We consider rather broad classes of general economic equilibrium problems and oligopolistic equilibrium problems which can be formulated as mixed variational inequality problems. Such problems involve a continuous mapping and a convex, but not necessarily differentiable function. We present existence and uniqueness results of solutions under weakened P-type assumptions on the cost mapping. They enable us to establish new results for the economic equilibrium problems under consideration

Assay of nitrofuran drugs using an amperometric monoamine oxidase biosensor

A method for assaying nitrofuran drugs (furazolidone, furadonine, and furagin) using an amperometric biosensor based on a printed platinum electrode and immobilized monoamine oxidase was developed for analysis of medicinal formulations and urine. Nitrofuran derivatives were found to have inhibitory actions, albeit weaker than those of classical tricyclic antidepressants, on the catalytic activity of monoamine oxidase. This side-effect inhibitory action allowed assay of furazolidone, furadonine, and furagin with lower detection limits, which were 8.3 × 10-9, 8.5 × 10-8, and 9.4 × 10-10 M respectively. The results obtained here show that this side effect of furazolidone, furadonine, and furagin must be taken into consideration when these agents are prescribed to patients. © 2011 Springer Science+Business Media, Inc

Assay of nitrofuran drugs using an amperometric monoamine oxidase biosensor

A method for assaying nitrofuran drugs (furazolidone, furadonine, and furagin) using an amperometric biosensor based on a printed platinum electrode and immobilized monoamine oxidase was developed for analysis of medicinal formulations and urine. Nitrofuran derivatives were found to have inhibitory actions, albeit weaker than those of classical tricyclic antidepressants, on the catalytic activity of monoamine oxidase. This side-effect inhibitory action allowed assay of furazolidone, furadonine, and furagin with lower detection limits, which were 8.3 × 10-9, 8.5 × 10-8, and 9.4 × 10-10 M respectively. The results obtained here show that this side effect of furazolidone, furadonine, and furagin must be taken into consideration when these agents are prescribed to patients. © 2011 Springer Science+Business Media, Inc

Phase diagram of a current-carrying superconducting film in the absence of a magnetic field

We present the phase diagram for the current states of superconducting films, based on the experimental investigation of the resistive transition induced by transport current. We found that a rather narrow film never enters the vortex state, but experiences direct transition from the purely superconducting state to the resistive state with phase-slip centers as soon as the current exceeds the Ginzburg-Landau critical current Ic. The Meissner current state of the films of intermediate width transforms at I > 0.8Ic to the vortex resistive state which exists within the current interval 0.8Ic < I < Im, where the value Im of the upper critical current is in a good agreement with the theory. The vortex state of wide films is realized within the current region I^{AL} < I < Im, where I^{AL} is the transition point to the vortex state by Aslamazov and Lempitskiy. At I>Im, the wide films enter a vortex-free resistive state with phase-slip lines.Comment: 4 pages, 5 figure