Influence of Nano-defects on Current-voltage Characteristics of HTc Superconductors

Theoretical analysis is presented of the influence on the current-voltage characteristics of the nanosized defects, which may be created by heavy ions irradiation or can arise in technological process, for instance during the winding procedure of the superconducting coil. Results of calculations, performed basing on developed model of the interaction of pancake type vortices appearing in HTc superconductors with nano-sized defects are presented. The energy balance for flux creep process is deduced and current-voltage characteristics calculated in the function of static magnetic field, in accordance with experimental behavior. This static analysis has been extended further on the case of the time-varying magnetic field in which existence of dynamical anomalies is predicted, according to our previous experimental data. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3511

Influence of Radiation Induced Nano-defects on Critical Current of HTc Superconductors

Superconductors, including HTc materials are more and more frequently used in modern nuclear physics devices. During the work of nuclear accelerators arises however the radiation of heavy ions or fast neutrons, which can reach the superconducting windings, creating nano-sized defects. It influences properties of superconductors. In the paper is given theoretical analysis of the influence of nano-defects on the critical current of HTc superconductors. New theoretical model of the critical current is proposed based on an analysis of the interaction of nano-defects acting as pinning centers with pancake vortices appearing in HTc superconductors. Nano-defects from one side destroy the structure of superconducting materials, which effect has negative meaning, while from other side anchorage of individual vortices or vortex lattice on defects will improve critical current. These both opposite phenomena are considered for HTc materials and also for A15 type superconductors, in which superconductivity is strongly related to state of ordering of transition metals as Nb, V in linear chains. The potential barrier against pancake vortices movement has been considered and calculations of an influence of sizes of nano-defects on current-voltage characteristics performed. Expression for an energy barrier allowed also to determine the time stability of the magnetic vortex structure and flowing current, which effect has especial meaning in the superconducting shields. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3541

Zur Kenntniss des Isatins und seiner Derivate. VI. Mittheilung: Ueber Cumarophenazine

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A Three-Frequency Feed for Millimeter-Wave Radiometry

A three-frequency millimeter-wave feed horn was developed as part of an advanced component technology task that provides components necessary for higher-frequency radiometers to meet the needs of the Surface Water and Ocean Topography (SWOT) mission. The primary objectives of SWOT are to characterize ocean sub-mesoscale processes on 10-km and larger scales in the global oceans, and to measure the global water storage in inland surface water bodies, including rivers, lakes, reservoirs, and wetlands. In this innovation, the feed provides three separate output ports in the 87-to- 97-GHz, 125-to-135-GHz, and 161-to-183- GHz bands; WR10 for the 90-GHz channel, WR8 for the 130-GHz channel, and WR5 for the 170-GHz channel. These ports are in turn connected to individual radiometer channels that will also demonstrate component technology including new PIN-diode switches and noise diodes for internal calibration integrated into each radiometer front end. For this application, a prime focus feed is required with an edge taper of approximately 20 dB at an illumination angle of 40 deg. A single polarization is provided in each band. Preliminary requirements called for a return loss of better than 15 dB, which is achieved across all three bands. Good pattern symmetry is also obtained throughout all three-frequency bands. This three-frequency broadband millimeter-wave feed also minimizes mass and provides a common focal point for all three millimeter-wave bands

Inter-individual genetic variation in the temperature response of Leptosphaeria species pathogenic on oilseed rape

It is important to understand the likely response of plant pathogens to increased temperatures due to anthropogenic climate change. This includes evolutionary change due to selection on genetically based variation in growth rate with temperature. We attempted to quantify this in two ways. First, radial mycelial growth rates in agar culture were determined for a collection of 44 English isolates of Leptosphaeria maculans and 17 isolates of L. biglobosa, at 14 temperatures. For L. maculans the genetic variances in four parameters were measured: minimum temperature allowing growth, optimum temperature, growth rate at the optimum temperature and growth rate at the highest usable temperature, 31.8°C. The standard deviations were 0.068 °C , 1.28°C, 0.21 mm day-1 and 0.31 mm day 1 °C-1 respectively. For L. biglobosa, these figures were, respectively: immeasurably small, 1.31 °C, 0.053 mm day-1 and 0.53 mm day- °C-1. In addition, the incidence and severity of phoma stem canker in planta over a natural growing cycle at four temperatures (16°C, 20°C, 24°C and 28°C) around the average culture optimum were determined. There was no correlation between in vitro and in planta growth, and the decrease in pathogen measures either side of the optimum temperature was much less for in planta growth than for in vitro growth. We conclude that both pathogens have the capacity to evolve to adapt to changes in environmental conditions, but that predictions of the effect of this adaptation, or estimates of heritability in natural conditions, cannot be made from measurements in vitro

Effect of the inoculum dose of three grapevine trunk pathogens on the infection of artificially inoculated pruning wounds

This study assessed the infection rates of different spore inoculum doses of the grapevine trunk pathogens Diplodia seriata, Phaeomoniella chlamydospora and Eutypa lata following artificial inoculation of pruning wounds. Potted vines of cv. Tempranillo were inoculated with doses ranging from 10 to 4000 conidia per wound of D. seriata and P. chlamydospora and led to recovery percentages of 10–100% for D. seriata and 16–94% for P. chlamydospora. Eutypa lata, when inoculated onto wounds of vines in a mature vineyard (cv. Shiraz) and on detached canes (cv. Cabernet Sauvignon) with a dose range of 10 to 1000 ascospores per wound, led to recovery percentages of 17–95%. In the field assay, there was no difference in recovery from wounds that were exposed to single or double inoculations with the same total spore dose, or between canes that were harvested 7 or 11 months after inoculation. The results obtained in this study showed significant variability in pathogen recovery between trials, comparable with that reported previously, which suggests that factors such as pathogen virulence, environmental parameters and experimental conditions may influence the infection process. According to this study, in order to obtain optimal recovery percentages of 50–70% for robust evaluation of pruning wound treatments, dose ranges of 100-1000 conidia of D. seriata, 100–2000 conidia of P. chlamydospora, and 100–500 ascospores of E. lata per wound would be required.Georgina Elena, Mark R. Sosnowski, Matthew R. Ayres, Pascal Lecomte, Celine Benetreau, Francesc Garcia-Figueres, Jordi Luqu