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1

A robust model of material degradation within a corrosive environment

Majkowska A., Sławiński D., Badur J.

Transactions of the Institute of Fluid-Flow Machinery

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2015

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nr 128

85--96

EN

This paper is a proposition of implementation an amendment to the existing classic definition of degradation described the by Kachanov-Robotnov model. The proposed model allows to determine the rate of degradation the material structure in an independent verified corrosive environment and determining the redistribution of three-dimensional stress fields taking into account the progressive degradation. According to that purpose, the computational solid dynamics (CSD) numerical simulation of corrosion degradation performed with the mathematical model which was calibrated on the basis of an experiment has been performed by Mrowiec and Werber.

2

Znaczenie głębokości obszaru strefy wpływu ciepła na rodzaj przeprowadzanej rewitalizacji przy uszkodzeniach wirników

Badur J., Bzymek G., Majkowska A., Sławiński D., Ziółkowski P., Ziółkowski P. J.

Instal

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2015

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nr 12

36--40

PL

Strefa wpływu ciepła (HAZ) ma szczególne znaczenie zarówno w procesach spawalniczych, jak i podczas różnego typu zdarzeń wynikających z zatarcia się uszczelnień, panwi łożysk, czopów itp. prowadzących do stopienia i zmiany struktury materiału. Zjawisku temu towarzyszy znaczny przyrost temperatury, który może być spowodowany wewnętrznym źródłem ciepła: bądź to termicznym, jak i również mechanicznym wywołanym wzajemnym tarciem stykających się powierzchni. W celu wyznaczenia głębokości obszaru strefy wpływu ciepła i tym samym znalezienia miejsc ewentualnych zmian fazowych w strukturze metalu, a także miejsc uplastycznienia konstrukcji, wykonano szereg symulacji numerycznych thermal-FSI. Jako warunki brzegowe zadano źródła ciepła na czopie łożyska zmienne w czasie trwania zjawiska. W symulacjach thermal-FSI, wykorzystano autorski model źródła ciepła zaimplementowany do kodu komercyjnego, którego zadaniem było oszacowanie rozkładu temperatur, jaki wygenerowany został w trakcie analizowanego zdarzenia. W dalszej kolejności, dla wyznaczenia głębokości pól płynięcia plastycznego metalu panwi i korpusu łożyska oraz czopa wirnika zaadaptowano model plastyczności Burzyńskiego. Stałe do modelu opisującego wielkość generowanego ciepła zweryfikowano eksperymentalnie. Wyniki uzyskane w zaproponowanym modelu pokryły się z późniejszymi badaniami krystalograficznymi oraz ultradźwiękowymi, przeprowadzonymi w laboratorium producenta turbiny. Stwierdzono dużą zgodność uzyskiwanych przez model wyników z pomiarami rzeczywistymi na obiekcie. Ostatecznie sformułowano wnioski dotyczące HAZ i koniecznych modernizacji.

EN

Heat affected zone (HAZ) plays a crucial role both in welding process as well as in different types of cases, that are the consequences from destroy the clearances, bearing liners, journals, etc., that lead to melting and changing in the structure of the material. This phenomenon is accompanied by a significant increase in temperature, which can be caused by an external, either thermal as well as mechanical, source of heat resulting from mutual friction of the surfaces. In order to determine the depth of heat affected zone area and thus find both places of possible phase changes in metal structure, as well as places of plasticity, we performed a series of thermal-FSI numerical simulations. The heat rate sources of the journal surface changing in duration of the phenomenon were taken into account as boundary conditions. In thermal-FSI simulations, there was used the original model implemented in the commercial code, whose task was to estimate temperature field that has been generated during the analyzed case. Further, to determine the depth of the field of plasticity of the metal, there was adapted Burzyński model plasticity. The necessary constants for the model describing the size of the heat generated were experimentally verified. The obtained results in the proposed model agreed with subsequent crystallographic and ultrasound studies, which were conducted in the laboratory turbine manufacturer. It was found good agreement of model results with actual measurements on an object. Suggestions to a proper modernization have been stated, too.

3

68Ge/68Ga radioisotope generator as a source of radiotracers for water flow investigations

Palige J., Majkowska A., Herdzik I., Ptaszek S.

Nukleonika

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2011

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Vol. 56, No. 1

77-80

EN

Radiotracer experiments on the model of rectangular settler with a volume of 3 m3, with a consecutive application as a tracer of the aqueous phase fluoresceine (representative tracer of water), eluate from a 68Ge/68Ga radioisotope generator (0.1 N HCl solution) and chelates after Ga ions complexation with 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) and 1,4,7,10-tetrazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were carried out. The obtained residence time distribution (RTD) functions indicate that only the complex compounds of gallium are stable in the water phase and are not adsorb on the vessel walls, so they can be recommended as tracers of the water phase.

4

Makrocykliczne kompleksy radionuklidów w medycynie nuklearnej

Majkowska A., Bilewicz A.

Wiadomości Chemiczne

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2008

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[Z] 62, 7-8

609-633

EN

The use of radiometal-labeled small complexes and biomolecules as diagnostic and therapeutic agents is a relatively new area of medical research. Radiopharmaceuticals are radiolabeled molecules designed to deliver ionizing radiation doses to specific disease sites. Between the targeting biomolecule and a radionuclide a bifunctional ligand is inserted, one end of which is covalently attached to the targeting molecule either directly or through a linker whereas the other strongly coordinates a metallic radionuclide. Selection of a bifunctional ligand is largely determined by the nature and oxidation state of a metal ion. The metal chelate can significantly affect the tumor uptake and biodistribution of radiopharmaceuticals based on small biomolecules. This is because in many cases the metal chelate contributes greatly to the overall size and lipophilicity of the radiopharmaceutical. Therefore, the design and selection of the ligand is very important for the development of a clinically useful therapeutic agent. The requirement for high thermodynamic and kinetic stability of the metal complex is often achieved through the use of macrocyclic ligands with a functionalized arm for covalent bonding to the biomolecule. In this review synthesis of bifunctional macrocyclic ligands and properties of radionuclide macrocyclic complexes used in nuclear medicine are presented. We describe results in two areas: substituted macrocyclic aza ligands for chelation of hard metal cations, and macrocycles containing sulphur for complexation of soft metal cations. Special attention was paid to stability of the complexes as well as to their lipophilicity, which affect biological properties of the formed radiopharmaceuticals. We also include a forecast of the near-term opportunities that are likely to determine practice in the next few years.