Papers by Keyword: Radiotracer

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Authors: Mohd Amirul Syafiq Mohd Yunos, Siti Aslina Hussain, Jaafar Abdullah, Engku Mohd Fahmi Engku Chik, Noraishah Othman, Shahidan Radiman
Abstract: This paper describes the development of colloidal Au-SiO2 with core-shell structure nanoparticle radioactive tracers by neutron activation in nuclear reactor that produce Au-198 (T1/2=2.7 d) emitting gamma ray of 412 keV. Using conventional citrate-reduction method, gold nanoparticles were prepared from its corresponding metal salts in aqueous solution then coated with uniform shells of amorphous silica via a sol-gel reaction. The citrate-reduction-based method provides gold nanoparticles with higher concentration and narrow size distribution. By using transmission electron microscopy (TEM), the resultant of particle size and silica coatings could be varied from tens to several hundred of nanometers by controlling the catalyzer and precipitation time. Au-SiO2 core-shell nanostructure is good to prevent the particles from getting agglomerated resulting in a big mass. In addition, silica surface offer very good chances that make the hydrophobic and hydrophilic behavior on the gold nanoparticles. EDXRF spectrum has proven that Au-SiO2 core-shell nanoparticles sample consists purely of a gold and silica particles. This target material of radiotracer application used to investigate multiphase system in process industries without disturbing the system operation.
Authors: L.G. Kornelyuk, A.Yu. Lozovoi, Igor M. Razumovskii
Authors: O.V. Markovich, Igor M. Razumovskii
Authors: Joanna Dudała, Jolanta Gilewicz-Wolter, Zdzisław Stęgowski
Abstract: The paper presents the application of multitracer method of diffusion measurement in Cr-Mn steels. Two austenitic steels were investigated: Cr13Mn18SiCa and Cr17Mn17 as well as austenitic-ferritic one: Cr15Mn19. The serial sectioning technique was used for simultaneous evaluation of diffusion coefficients of radioisotopes of chromium 51Cr, manganese 54Mn and iron 59Fe at 1073K and 1173 K. Diffusion coefficients of radiotracers at 1173 K were calculated on the basis of both: activity of removed layer (differential method) and residual activity of the sample (integral method). The evaluated diffusion coefficients of metals in austenitic steels are higher than those in austenitic-ferritic one; their values are about 10-12 ÷ 10-11 cm2s-1. Moreover it was found that at 1173 K the diffusion rate of manganese is higher than that for iron and chromium while at 1073 K diffusion rates of chromium and manganese are comparable and higher than that for iron. Furthermore the experimental results point out that at 1173 K the volume diffusion is the dominant mechanism of metals’ transport while at 1073 K the high diffusivity paths diffusion prevails.
Authors: S. Peteline, Eugene M. Tanguep Njiokep, Sergiy V. Divinski, Helmut Mehrer
Authors: G. Pasold, F. Albrecht, C. Hülsen, R. Sielemann, W. Witthuhn
Abstract: Silicon carbide (SiC) was investigated for deep band gap states of europium by means of deep level transient spectroscopy (DLTS). The knowledge of the properties of optoelectrically active impurities or defects is essential for a detailed understanding of the energy-transfer process resulting in the observable excitations [1]. SiC-samples of the polytypes 4H as well as 6H are ion-implanted by different europium- isotopes in order to obtain a chemical identification of the characterized energy levels. Here the concentration sensitivity of the DLTS is applied to observe the elemental transmutation of the incorporated radioactive tracer atoms 146Eu (t1/2=4.51 d) and 147Eu (t1/2=24.6 d). DLTS on samples implanted with stable Eu-ions (153Eu) was carried out for comparison and manifestation of the results. From these studies 5 Eu-related deep band gap levels are established: in 4H-SiC two levels at EV+0.86(2) eV and EC−0.47(2) eV, and in 6H-SiC three levels at EV+0.88(2) eV, EC−0.29(2) eV and EC−0.67(2) eV.
Authors: E. Demir, A.B. Tugrul, N. Baydogan, A.F. Baytaş, N. Altinsoy, S. Haciyakupoğlu, B. Büyük
Abstract: In this study, diffusion of rubidium and potassium in soil was observed representing two alkaline elements. Generally, these elements are found as salt compounds in the earth. Soil columns were prepared in the laboratory conditions. Rubidium chlorite and potassium nitrate compounds were irradiated at ITU TRIGA Mark II nuclear research reactor at the Energy Institute of ITU to produce the radiotracer 86Rb and 42K. The irradiated compounds were sprinkled to the surface of different soil columns and were watered with realistic amounts. Radioactivity measurements were carried out by using a scintillation detector at the outside of the column for different soil depths in different diffusion times. As the results of the study, the behavior of two alkaline elements was observed appropriately similar in the soil.
Authors: Jean Bernardini, Christophe Girardeaux, Andree Rolland
Abstract: Grain-boundary heterodiffusion of iron in pure copper and self diffusion of iron in copper–0.091at% iron were measured by the serial sectioning technique in the Harrison B-regime. The penetration profiles corresponding to iron heterodiffusion in pure copper show a strong positive curvature far beyond the (Dvt)1/2 depth . This peculiar shape, which does not exist for self diffusion in the solid solution, proves the presence of a strong non linear grain-boundary segregation of iron in copper in spite of the respective surface energies of these metals. This segregation is linked to the size effect which is, as predicted by numerical simulation, the main driving force for grainboundary segregation.
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