Manufacture of Bi-cuprate thin films on MgO single crystal substrates by chemical solution deposition

Bi2Sr2CaCu2O8 thin films have been deposited on MgO single crystal substrates by spin-coating a solution based on 2-ethylhexanoate precursors dissolved in xylene. Pyrolysis takes place between 200 degrees C and 450 degrees C and is accompanied by the release of 2-ethylhexanoic acid, CO2 and H2O vapour. Highly c-axis oriented Bi2Sr2CaCu2O8 as well as Er-or Ho-doped Bi2Sr2(Ca, Ln)Cu2O8 (Ln = Er, Ho) films were obtained after heat treatment at 840 degrees C in air

VÝZKUM VLIVU DEFORMACE NA CHOVÁNÍ CHROMOVÝCH KARBIDŮ V NÁSTROJOVÉ OCELI POMOCÍ TECHNOLOGIE TVÁŘENÍ S PŘECHODEM PŘES SEMI-SOLID STAV

Klasické zpracování nástrojových ocelí je již v průmyslové praxi běžně využíváno, přesto se však stále hledají cesty, jak odstranit ze struktury problematické ostrohranné primární karbidy chromu, které zhoršují houževnatost nástrojových ocelí. Díky dalšímu výzkumu jiných metod tváření byla objevena nové dosud nevyužívané metody pro modifikaci výsledných struktur. Díky tomuto zpracování lze dosáhnout lepších mechanických vlastností. Hlavním problémem u vysocepecných ocelí ledeburitického typu je tvorba ostrohranných karbidů. Tyto karbidy jsou obtížně rozpustitelné a v mikrostruktuře díky jejich velikosti a tvaru nežádoucí. Zvyšují sice odolnost materiálu vůči opotřebení, ale současně snižují houževnatost a mohou být koncentrátory napětí. Tento příspěvek je věnován využití jedné z těchto technologií. V tomto případě se jedná o využití technologii semi-solid zpracování. V přechozích letech bylo při zpracování nástrojové oceli pomocí tixoformingu dosaženo nekonvenční struktury a mechanických vlastností. Toto zjištění se následně stalo podnětem k dalším experimentům. Struktura získaná kombinací semi-solid zpracování a následným tvářením měla oproti standardně dosahovaným strukturám po semi-solid zpracování odlišný charakter. Karbidické síťoví bylo redistribuováno v celém objemu materiálu, tím vytvářelo zpevňující prvek a nezpůsobovalo křehkost oceli, kterou trpí materiály s výrazným karbidickým síťovím. Tímto způsobem byla navržena a sestavena nová technologie, umožňující zásadní modifikaci struktury a tím i zlepšení mechanických vlastností. Tento postup zpracování byl dále aplikován na polotovary větších rozměrů a byl zjišťován i vliv jednotlivých stupňů deformace i směr tváření na vývoj struktury.Induction hardening technology is mainly used for processing parts where high hardness, although conventional treatment of tool steels is ordinarily used in industrial practice, engineers continue to seek new procedures to rid tool steels of objectionable primary sharp-edged chromium carbides, which impair toughness. Fortunately, research into metal forming yielded new methods of modifying the microstructure of hypereutectoid steels. Using these methods, mechanical properties can be improved by virtue of eliminating objectionable sharp-edged carbides. These carbides resist dissolution and their size and shape make them undesirable microstructural constituents. Although they do improve wear resistance of the matrix, they also impair toughness and may act as stress concentrators. The microstructures produced by a sequence involving semi-solid processing and subsequent forming operations were different from conventional semi-solid-processed microstructures. In the former microstructures, the prior carbide network was broken up, dispersed, and became a strengthening constituent. Brittleness which plagues materials with prominent carbide networks was thus removed. The experimental material used in this study was X210Cr12 tool steel. Two semi-solid processing temperatures were used: 1240°C and 1260°C. There were two holding times: 30 minutes and 60 minutes. Another variable was the number of reductions. The resulting microstructures were examined with respect to individual sequences and reductions applied. Detailed microstructure analysis was carried out using a scanning electron microscope (SEM). Chemical compositions of carbides were determined by means of EDS (Energy Dispersive X-ray Spectroscopy). Microhardness was measured in order to gather comprehensive materials data. The purpose of the study was to identify trends, if any, in microstructural property evolution in response to the above-described processing sequence

Mortality Rates in Poultry Species and Categories during Transport for Slaughter

Transport-related mortality rates were compared for various poultry species and categories where published data are limited. The numbers of broilers, hens and cockerels, turkeys, ducks, and geese transported for slaughter, and the numbers that died during such transport, were recorded from 1997 to 2006 in cooperation with the State Veterinary Administration of the Czech Republic. The mortality rate for individual poultry species and categories was calculated overall, and was also recorded for the following transport distances: up to 50 km, from 51 km to 100 km, from 101 km to 200 km, from 201 km to 300 km, and over 300 km. Transport of poultry for slaughter was accompanied by varying mortality rates depending on poultry species and categories. The highest mortality rates occurred in hens and cockerels (1.013%), followed by turkeys (0.272%), broilers (0.253%), ducks (0.103%), and geese (0.056%). Differences among the mortality rates estimated were highly significant (p < 0.001). Mortality rates highly correlated with transport distance. The lowest mortality rates were for the shortest transport distances: In broilers (0.154%), turkeys (0.164%), and hens and cockerels (0.595%) for a transport distance up to 50 km; and in ducks (0.069-0.111%) and geese (0.021 - 0.053%) for transport distances up to 300 km. Highest mortality rates in hens and cockerels (1.892%), turkeys (0.341%), and broilers (0.536%) were observed for transport distances over 200 km, while in ducks (0.147%) and geese (0.253%), highest mortality rates were with transport distances exceeding 300 km. The highest mortality rates for all transport distances were in hens and cockerels, followed by turkeys and broilers. The mortality rate in turkeys for a transport distance up to 50 km was significantly higher than that in broilers. No significant differences were found between mortality rates in turkeys and broilers for transport distances of 51-100 km and 101-200 km whereas, for a distance of 201-300 km and in distances exceeding 300 km, the mortality rates in broilers were significantly higher compared to turkeys. The lowest mortality rates were observed in ducks and geese, with a significant difference between them only for transport distances of 51 to 100 km, where the mortality rate in ducks was higher, and over 300 km, where the mortality rate in geese was higher. When planning the transport of poultry for slaughter, susceptibility to stress induced by transport and transport distance (i.e. the duration of transport) of poultry species and categories should be considered

Research data supporting "Effect of Y-211 particle size on the growth of single grain Y–Ba–Cu–O bulk superconductors"

The files provided contain the raw 211 particle distribution data, DTA, XRD and trapped field data used to produce the figures presented in the paper. Further documentation is provided in the origin files.This work was supported by the EPSRC, Czech Ministry of Industry and Trade EP/K02910X/

Preparation and Characterization of Mg1-xB2 Bulk Samples and Cu/Nb Sheathed Wires with Low Grade Amorphous Boron Powder

MgB2 bulk and wire samples were prepared using cheap, low grade amorphous boron powders. Based on chemical analysis performed on the starting reagents, three nominal stoichiometries were studied. It was found that the structural and superconducting properties of the bulk samples were not affected by the composition, but that residual Mg was left in the wires for the nominal MgB2 composition. In contrast, slightly Mg-deficient compositions were free from residual Mg and exhibited higher critical current densities. The MgB2 phase formation kinetics was not influenced by the variations in the nominal powder compositio