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1624. High-temperature oxidation of boiler steels at 650 °CJaka Burja, Barbara Šetina, Borut Žužek, Tilen Balaško, 2023, original scientific article Abstract: This study presents a comprehensive investigation of the formation, composition and
behaviour of oxide layers during the high-temperature oxidation of four different steel alloys (16Mo3,
13Cr, T24 and P91) at a uniform temperature of 650 °C. The study is aimed at assessing the oxidation
damage due to short-term overheating. The research combines CALPHAD (CALculation of PHAse
Diagrams) calculations, thermogravimetric analysis (TGA) and advanced microscopy techniques, in-
cluding scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD), to elucidate
the complex mechanisms controlling oxidation kinetics and oxide layer development. CALPHAD
calculations were used to determine the thermodynamically stable phases for each steel type at 650
◦C and different oxygen activities. The results showed different phase compositions, highlighting
the importance of the chromium content in steel for the formation of oxide layers. The different
oxidation kinetics and oxide layer compositions are presented and associated with the increased risk
of material degradation due to overheating. These results have significant implications for industrial
applications, mainly the susceptibility to oxidation of low-alloyed steels like 16Mo3 and 13 Cr and
contribute to a deeper understanding of oxidation processes in steels. Keywords: high-temperature oxidation, thermogravimetric analysis, kinetics, CALPHAD, boiler steels, SEM, EBSD Published in DiRROS: 26.01.2024; Views: 403; Downloads: 170 Full text (12,99 MB) This document has many files! More... |
1625. Morphological characteristics of young and old murine hematopoietic stem cell niches, as modeled in vitroMojca Justin, Ema Rogac Randl, Veno Kononenko, Matej Hočevar, Damjana Drobne, Primož Rožman, 2023, original scientific article Abstract: The hematopoietic stem cell (HSC) niche undergoes detrimental changes with age. The molecular differences between young and
old niches are well studied and understood; however, young and old niches have not yet been extensively characterized in terms of
morphology. In the present work, a 2D stromal model of young and old HSC niches isolated from bone marrow was investigated
using light and scanning electron microscopy (SEM) to characterize cell density after one, two, or three weeks of culturing, cell
shape, and cell surface morphological features. Our work is aimed at identifying morphological differences between young and
old niche cells that could be used to discriminate between their respective murine HSC niches. The results show several age-
specific morphological characteristics. The old niches differ from the young ones in terms of lower cell proliferating capacity,
increased cell size with a flattened appearance, increased number of adipocytes, and the presence of tunneling nanotubes. In
addition, proliferating cell clusters are present in the young niches but not in the old niches. Together, these characteristics
could be used as a relatively simple and reliable tool to discriminate between young and old murine HSC niches and as a
complementary approach to imaging with specific cellular markers. Keywords: bone marrow, hematoopetic stem cell niche, aging, adipocytes, scanning electron microscopy Published in DiRROS: 26.01.2024; Views: 368; Downloads: 158 Full text (2,47 MB) This document has many files! More... |
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1627. Vehicle–bridge interaction modelling using precise 3D road surface analysisMaja Kreslin, Peter Češarek, Aleš Žnidarič, Darko Kokot, Jan Kalin, Rok Vezočnik, 2024, original scientific article Abstract: Uneven road surfaces are the primary source of excitation in the dynamic interaction between a bridge and a vehicle and can lead to errors in bridge weigh-in-motion (B-WIM) systems. In order to correctly reproduce this interaction in a numerical model of a bridge, it is essential to know the magnitude and location of the various roadway irregularities. This paper presents a methodology for measuring the 3D road surface using static terrestrial laser scanning and a numerical model for simulating vehicle passage over a bridge with a measured road surface. This model allows the evaluation of strain responses in the time domain at any bridge location considering different parameters such as vehicle type, lateral position and speed, road surface unevenness, bridge type, etc. Since the time domain strains are crucial for B-WIM algorithms, the proposed approach facilitates the analysis of the different factors affecting the B-WIM results. The first validation of the proposed methodology was carried out on a real bridge, where extensive measurements were performed using different sensors, including measurements of the road surface, the response of the bridge when crossed by a test vehicle and the dynamic properties of the bridge and vehicle. The comparison between the simulated and measured bridge response marks a promising step towards investigating the influence of unevenness on the results of B-WIM. Keywords: interakcija vozilo in most, terestično lasersko skeniranje, neravnost vozišča, numerično modeliranje Published in DiRROS: 26.01.2024; Views: 445; Downloads: 160 Full text (12,08 MB) This document has many files! More... |
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1629. Kartiranje in vrednotenje ekosistemskih storitev na Jelovici : projekt JeloviZaAnže Japelj, Andreja Ferreira, Andrej Kobler, Anže Martin Pintar, Katja Kavčič Sonnenschein, 2023, final research report Keywords: ekosistemske storitve, vrednotenje, kartiranje, Jelovica, kaskadni model Published in DiRROS: 26.01.2024; Views: 438; Downloads: 0 |
1630. Kartiranje in vrednotenje ekosistemskih storitev na Jelovici : projekt JeloviZaAnže Japelj, Andreja Ferreira, Andrej Kobler, Anže Martin Pintar, Katja Kavčič Sonnenschein, 2023, treatise, preliminary study, study Keywords: ekosistemske storitve, vrednotenje, kartiranje, Jelovica, kaskadni model Published in DiRROS: 26.01.2024; Views: 410; Downloads: 0 |