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

Survival of Phoma koolunga, a causal agent of ascochyta blight, on field pea stubble or as pseudosclerotia in soil

Phoma koolunga is a recently recognized pathogen in the ascochyta blight complex of field pea (Pisum sativum). Unlike the other three ascochyta blight pathogens, survival of P. koolunga is poorly understood. Survival of this fungus was examined on field pea stubble and as pseudosclerotia on the surface of, and buried in, field soil. Pseudosclerotia were formed in plates containing potato dextrose agar (PDA) mixed with sand or amended with fluorocytocin. After 1 month, P. koolunga was recovered on amended PDA from 93% of stubble sections retrieved from the soil surface, 36% of buried stubble sections and 100% of pseudosclerotia buried in field soil, pasteurized or not. The frequency of recovery of P. koolunga decreased over time and the fungus was not recovered from stubble on the soil surface at 15 months, nor was it recovered from stubble buried in soil at 11 months or later, or from pseudosclerotia buried for 18 months. In a pot bioassay, most ascochyta blight lesions developed on plants inoculated with stubble retrieved from the soil surface after 1 month. Infectivity of the inoculum decreased over time. Disease on plants inoculated with stubble that had been buried or left on the soil surface for up to 6 and 5 months, respectively, and pseudosclerotia retrieved at 14 months and later from field soil did not differ from the non-inoculated control. These results suggest that field pea stubble may play a role in survival of P. koolunga, especially if it remains on the soil surface. In addition, pseudosclerotia were able to persist in soil and infect field pea plants into the next season.M. Khani, J. A. Davidson, M. R. Sosnowski and E. S. Scot

Survival, transmission and control of Phoma koolunga in field pea seed and reaction of field pea genotypes to the pathogen

Little is known about the epidemiology of Phoma koolunga, a component of the ascochyta blight complex of field pea in southern Australia. The aims of this research were to investigate seed infection, efficacy of fungicides as seed dressings and the reaction of current field pea genotypes to this fungus. The frequency of isolation of P. koolunga from individual seed samples from South Australia, Victoria and Western Australia ranged from 0 to 6 %. Disease was transmitted to 98% of seedlings that emerged from artificially inoculated seeds (AIS) in growth room conditions. The necrotic index on seedlings that emerged from AIS at 8°C was greater than that for seedlings at 12, 16 and 20°C. P-Pickel T® and Jockey Stayer® were the most effective fungicides for reducing disease incidence and severity on seedlings emerged from AIS sown in soil and on germination paper, respectively. The response of 12 field pea genotypes to one isolate of P. koolunga was assessed by spraying plants with pycnidiospore suspension in controlled conditions and examining symptoms from 3 to 21 days post-inoculation (dpi). Genotypes Sturt, Morgan and Parafield showed more severe disease on the lowest three leaves than the other genotypes at 21 dpi. In another experiment, four genotypes of short, semi-leafless type field peas were inoculated with three isolates of P. koolunga which differed in virulence and assessed as described above. Kaspa showed significantly less disease than Morgan or WAPEA2211 at 21 dpi when inoculated with two of the three isolates tested. Isolates of P. koolunga differed in aggressiveness based on % leaf area diseased until 14 dpi, but differences were not significant at 21 dpi.M. Khani, J. A. Davidson, M. R. Sosnowski, E. S. Scot

Morpho-physiological effects of Stymjod foliar application on Dactylis glomerata L.

The aim of the experiment was to study the effects of foliar application of a growth regulator containing iodine nanoparticles, with the trade name of Stymjod, on morphometrics, photosynthetic activity and chlorophyll content of Dactylis glomerate L. The following parameters were determined: the weight of fresh and dry matter of plants, leaves and roots, the number of shoots and leaves, potential (FV/Fm) and effective (F/Fm’) quantum efficiency of photosystem, photochemical (qP) and non-photochemical (qN) quenching, as well as chlorophyll a and chlorophyll b content in leaf blades. The pot experiment was carried out in a breeding room. Stymjod was applied at 1.5%, 3% and 4.5% concentrations in the spray solution. It is a nanotechnology-based growth regulator, with easily assimilable forms of mineral and organic ingredients, favorably affecting plant ontogenesis. Plants were treated twice with a single dose of 50 mL of spray per pot. They were sprayed till they were completely covered with the liquid. Distilled water was used to spray control plants. The results were statistically processed using analysis of variance, while the significance of the differences between means was determined with Tukey's test with P = 0.05. In the experiment it was found that different concentrations of Stymjod in the spray resulted in different response of plants. The best morphological effects were obtained using the concentration of the product exceeding 3%. In the test conditions Stymjod applied to D. glomerata increased the efficiency of the photosynthetic apparatus and the content of chlorophyll pigments

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

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