21. Rigidity of terminal simplices in persistent homologyAleksandra Franc, Žiga Virk, 2023, izvirni znanstveni članek Povzetek: Given a filtration function on a finite simplicial complex, stability theorem of persistent homology states that the corresponding barcode is continuous with respect to changes in the filtration function. However, due to the discrete setting of simplicial complexes, the simplices terminating matched bars cannot change continuously for arbitrary perturbations of filtration functions. In this paper we provide a sufficient condition for rigidity of a terminal simplex, i.e., a condition on $\varepsilon > 0$ implying that the terminal simplex of a homology class or a bar in persistent homology remains constant through $\varepsilon$-perturbations of filtration function. The condition for a homology class or a bar in dimension $n$ depends only on the barcodes in dimensions $n$ and $n+1$.
Ključne besede: persistent homology, stability theorem, terminal simplex, rigidity
Objavljeno v DiRROS: 15.03.2024; Ogledov: 197; Prenosov: 90
 Celotno besedilo (476,36 KB)
Gradivo ima več datotek! Več... |
22. Development of the recycling procedure for rapid antigen testsRebeka Rudolf, Darja Feizpour, Žiga Jelen, Peter Majerič, Tilen Švarc, Matej Zadravec, Timi Gomboc, Aleksandra Kocijan, 2024, izvirni znanstveni članek Ključne besede: rapid antigen tests, recycling, characterization, nanogold, plastic
Objavljeno v DiRROS: 28.02.2024; Ogledov: 255; Prenosov: 91
Celotno besedilo (1,74 MB)
Gradivo ima več datotek! Več... |
23. Subchronic exposure of rats to sublethal dose of microcystin-YR induces DNA damage in multiple organsMetka Filipič, Bojana Žegura, Bojan Sedmak, Irena Horvat-Žnidaršič, Aleksandra Milutinović Živin, Dušan Šuput, 2007, izvirni znanstveni članek Povzetek: Background. Microcystins (MCs) are cyclic heptapeptides that are considered tobe liver specific toxins. They are potent tumour promoters and recent studies indicate that they are also genotoxic. In this study we measured DNA damage in lymphocytes, liver, kidney (cortex and medulla), lung, spleen and brain cells of male Fisher F344 rats that were exposed to sublethal dose (every second day 10 Ugžkg b.w.č i.p) of microeysrin-YR (MCYR) for one month. Methods. At the end of exposure the animals were sacrificed, the lymphocytes were isolated from blood taken from jugular vein, liver cells were obtained byperfusion with collagenase A and the cells from other organs were isolated by incubating small tissue pieces with eollagenase A. The DNA damage in isolated cells was measured with the single cells gel electrophoresis (SCGE) also called the comet assay. Results. A significant increase of the % tail DNAin MCYR-exposed animals compared to the nonexposed control ones was observed in brain (2.5 fold), liver (2.1 fold), kidney medulla (1.9 fold), kidney cortex (1.8 fold) and lung (1.7 fold) cells, while the DNA from lymphocytes and spleen cells was not affected. Conclusion. This study demonstrated that subehronic exposure to sublethal doses of MCs can induce systemicgenotoxicity in mammals, and it affects not only the liver but also other vital organs.
Ključne besede: DNA damage, comet assay, cyanobacteria, bacterial toxins, rats, inbred F344
Objavljeno v DiRROS: 20.02.2024; Ogledov: 228; Prenosov: 55
Celotno besedilo (142,90 KB) |
24. An outline of the history of radiotherapy at the Institute of oncology in Ljubljana from its beginning till 1980sAleksandra Oklješa Lukič, Karmen Hübscher, 2003, strokovni članek Povzetek: Background. The article presents the milestone events in the history of radiotherapy at the lnstitute of Oncology since its establishment till 1980s. It reviews the facts deduced from various jubilee publications, seminar reports and staff interviews of the Institute of Oncology. The aim of the article is to present the chronological history of radiotherapy at the Institute of Oncology, and to supplement the fragmented and incomplete recordswritten in the past. Conclusions. Available records are occasionally discrepant, but the most significant events in the history of the Institute ofOncology and its Radiotherapy Ward can nevertheless be ascertained.
Objavljeno v DiRROS: 06.02.2024; Ogledov: 173; Prenosov: 41
Celotno besedilo (212,78 KB) |
25. |
26. Tribological evaluation of vegetable ▫$oil/MoS_2$▫ nanotube-based lubrication of laser-textured stainless steelMarjetka Conradi, Bojan Podgornik, Maja Remškar, Damjan Klobčar, Aleksandra Kocijan, 2023, izvirni znanstveni članek Povzetek: In the present work, the functionalisation of austenitic stainless steel, AISI 316L surfaces via nanosecond Nd:YAG laser texturing in order to modify the surface morphology with crosshatch and dimple patterns is presented. A tribological analysis under lubrication with sunflower and jojoba oil with and without the addition of a solid lubricant, MoS2 nanotubes, was performed. In conjunction with friction/wear response laser-textured surface wettability, oil spreadability and oil retention capacity were also analysed. It was shown that the crosshatch pattern generally exhibited lower friction than the dimple pattern, with the addition of MoS2 nanotubes not having any significant effect on the coefficient of friction under the investigated contact conditions. This was found in addition to the better oil spreadability and oil retention capacity results of the crosshatch-textured surface. Furthermore, texturing reduced the wear of the stainless-steel surfaces but led to an approximately one order of magnitude larger wear rate of the steel counter-body, primarily due to the presence of hard bulges around the textured patterns. Overall, the crosshatch pattern showed better oil retention capacity and lower friction in combination with different vegetable oils, thus making it a promising choice for improving tribological performance in various environmentally friendly applications.
Ključne besede: tribology, stainless steel, vegetable oil lubrication, MoS2 nanotubes
Objavljeno v DiRROS: 02.02.2024; Ogledov: 204; Prenosov: 99
Celotno besedilo (4,56 MB)
Gradivo ima več datotek! Več... |
27. Influence of oil viscosity on the tribological behavior of a laser-textured Ti6Al4V alloyMarjetka Conradi, Aleksandra Kocijan, Bojan Podgornik, 2023, izvirni znanstveni članek Povzetek: Laser texturing with a dimple pattern was applied to modify a Ti6Al4V alloy at the micro level, aiming to improve its friction and wear resistance in combination with oil lubrication to optimize the performance in demanding industrial environments. The tribological analysis was performed on four different dimple-textured surfaces with varying dimple size and dimple-to-dimple distance and under lubrication with three different oils, i.e., T9, VG46, and VG100, to reflect the oil viscosity’s influence on the friction/wear of the laser-textured Ti6Al4V alloy. The results show that the surfaces with the highest texture density showed the most significant COF reduction of around 10% in a low-viscosity oil (T9). However, in high-viscosity oils (VG46 and VG100), the influence of the laser texturing on the COF was less pronounced. A wear analysis revealed that the laser texturing intensified the abrasive wear, especially on surfaces with a higher texture density. For low-texturing-density surfaces, less wear was observed for low- and medium-viscosity oils (T9 and VG46). For medium-to-high-texturing densities, the high-viscosity oil (VG100) provided the best contact conditions and wear results. Overall, reduced wear, even below the non-texturing case, was observed for sample 50–200 in VG100 lubrication, indicating the combined effect of oil reservoirs and increased oil-film thickness within the dimples due to the high viscosity.
Ključne besede: oil lubrication, surface modification, Ti-based alloy, tribology
Objavljeno v DiRROS: 01.02.2024; Ogledov: 267; Prenosov: 105
Celotno besedilo (4,00 MB)
Gradivo ima več datotek! Več... |
28. |
29. Ultra-high strenght TWIP steel with high chromium contentPavel Podaný, Tomáš Studecký, Tomas Gregor, Radek Prochazka, Aleksandra Kocijan, 2023, izvirni znanstveni članek Povzetek: A new ultra-high strength steel with a fully austenitic microstructure and twinning-induced plasticity (TWIP) effect has been developed. TWIP effect gives this steel a good combination of high strength of over 1000 MPa and ductility of over 35%. This new steel has a high chromium content, which increases its corrosion resistance. By combining cold rolling and annealing, the steel has achieved a very fine austenitic microstructure with an average grain diameter of 2.85 µm. This steel could be used for structural applications or components that need to withstand high levels of stress, deformation and corrosion environment.
Ključne besede: TWIP steels, corrosion resistance, microstructure, tensile strength, plasticity
Objavljeno v DiRROS: 31.01.2024; Ogledov: 283; Prenosov: 169
Celotno besedilo (1,44 MB)
Gradivo ima več datotek! Več... |
30. Improving the surface properties of additive-manufactured Inconel 625 by plasma nitridingDanijela Anica Skobir Balantič, Črtomir Donik, Bojan Podgornik, Aleksandra Kocijan, Matjaž Godec, 2023, izvirni znanstveni članek Povzetek: As a surface-hardening technique, plasma nitriding is a common procedure for improving the properties of
conventional Ni-based alloys. The diffusion of nitrogen hardens a layer on the surface of the alloy, leading to
better wear resistance and a higher coefficient of friction, as well as a higher surface hardness. This study reports
the effect of plasma nitriding on additive-manufactured (AM) Inconel 625 (IN625) compared to its conventional
manufactured and nitrided counterparts. The samples produced with the laser powder-bed fusion (LPBF) process
were subsequently plasma nitrided in the as-built condition, stress-relief annealed at 870 °C and solution treated
at 1050 °C. The plasma nitridings were carried out at 430 °C and 500 °C for 15 h. The growth kinetics of the
nitride layer of the AM samples depends on the prior heat treatments and is faster in the as-built state due to the
specific cellular structure. The lower nitriding temperature leads to the formation of expanded austenite in the
nitride layer, while at the higher nitriding temperature, the expanded austenite decomposes and CrN precipitation
occurs. The XRD and SEM analyses confirmed the presence of two layers: the surface layer and the
diffusion layer beneath. The lower nitriding temperature caused the formation of expanded austenite or a
combination of expanded austenite and CrN. The higher nitriding temperature led to the decomposition of the
expanded austenite and to the formation/precipitation of CrN. The higher nitriding temperature also decreased
the corrosion resistance slightly due to the increased number of precipitated Cr-nitrides. On the other hand, the
wear resistance was significantly improved after plasma nitriding and was much less influenced by the nitriding
temperature.
Ključne besede: additive manufacturing, powder-bed fusion, plasma nitriding, expanded austenite, wear and corrosion resistance, Ni-based alloy
Objavljeno v DiRROS: 31.01.2024; Ogledov: 275; Prenosov: 109
Celotno besedilo (7,98 MB)
Gradivo ima več datotek! Več... |
