Multi-nuclear magnetic resonance study of Na3AlF6-AlPO4 molten and solidified mixtures.

Phosphorus is one of the predominant impurities in the Hall-Heroult process for industrial aluminium production. The nature of the dissolved phosphorus species in the Na(3)AlF(6)-AlPO(4) system has been investigated by in situ high-temperature (HT) (19)F, (23)Na, (27)Al, (17)O, and (31)P NMR. The combination of these experiments enables to define the presence of PO(4)(3-), AlF(5)(2-) and (AlF(4)-O-PO(3))(4-) anions in the melt, and then the formation of Al-O-P bonding. Melts solidified at different cooling rates were characterised using various solid-state NMR techniques including multiple quantum magic angle spinning (MQMAS), rotational echo double resonance (REDOR) and heteronuclear single quantum correlation (HSQC). The glass obtained by the rapid quenching of the hypereutectic melt has been carefully described in order to better understand the structure of the melt.

[Advantages of digitalization and analysis of roentgenograms of bones by microcomputer.]. / Výhody digitalizácie a analýzy röntgenogramov kostí mikropocítacom.

The creation of an experimental group for digitalization of two-dimensional X-ray pictures of bones was the starting point for the application of selected procedures for their computer-assisted analysis. During processing of the picture first the primary digitalized picture was corrected (e. g. subtraction of the background, correction of the non-homogenity of the scanning element and light source) and subsequently the picture was prepared by spot or local transformations (e. g. semithresholding, equalization, Sobel's operator and subtraction of two differently prepared pictures) while preserving the geometry of the original objects on the picture. On treated pictures of bony structures then graphic procedures of identification of important spots, lines, angles and derived indices and of mutual relations of bones were verified. For creation of prerequisites of the long-term development of osseous changes, in particular in patients with non-cemented implants of the hip joints, possibilities of and quantitative requirements of filing of digitalized two-dimensional X-ray pictures of the bones in information media were tested as well as the possibility to transmit them in the local computer network. Finally the authors draw attention to the advantages of digitalization and analysis of two-dimensional X-ray pictures of bones by a microcomputer from the aspect of impact on information, economic aspects and in particular preserving of information in digital form. Key words: digitalization of X-ray pictures, digital processing of X-ray pictures, filing of X-ray pictures.