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11.
Tribological evaluation of vegetable ▫$oil/MoS_2$▫ nanotube-based lubrication of laser-textured stainless steel
Marjetka 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: 101; Prenosov: 56
.pdf Celotno besedilo (4,56 MB)
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12.
Influence of oil viscosity on the tribological behavior of a laser-textured Ti6Al4V alloy
Marjetka 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: 131; Prenosov: 45
.pdf Celotno besedilo (4,00 MB)
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Ultra-high strenght TWIP steel with high chromium content
Pavel 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: 146; Prenosov: 53
.pdf Celotno besedilo (1,44 MB)
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15.
Improving the surface properties of additive-manufactured Inconel 625 by plasma nitriding
Danijela 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: 148; Prenosov: 57
.pdf Celotno besedilo (7,98 MB)
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16.
Monitoring of species’ genetic diversity in Europe varies greatly and overlooks potential climate change impacts
Peter Pearman, Olivier Broennimann, Tsipe Aavik, Tamer Albayrak, Paulo Célio Alves, Filipos Aravanopoulos, Laura Bertola, Aleksandra Biedrzycka, Elena Bužan, Vlatka Čubrić Čurik, Katja Kavčič Sonnenschein, Marjana Westergren, 2024, izvirni znanstveni članek

Povzetek: Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. However, genetic diversity has been largely neglected in biodiversity monitoring, and when addressed, it is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. We report an accounting of efforts to monitor population genetic diversity in Europe (genetic monitoring effort, GME), the evaluation of which can help guide future capacity building and collaboration towards areas most in need of expanded monitoring. Overlaying GME with areas where the ranges of selected species of conservation interest approach current and future climate niche limits helps identify whether GME coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area, financial resources and conservation policy influence GME, high values of which only partially match species’ joint patterns of limits to suitable climatic conditions. Populations at trailing climatic niche margins probably hold genetic diversity that is important for adaptation to changing climate. Our results illuminate the need in Europe for expanded investment in genetic monitoring across climate gradients occupied by focal species, a need arguably greatest in southeastern European countries. This need could be met in part by expanding the European Union’s Birds and Habitats Directives to fully address the conservation and monitoring of genetic diversity.
Ključne besede: genetics, monitoring, population genetic diversity, Europe
Objavljeno v DiRROS: 22.01.2024; Ogledov: 188; Prenosov: 73
.pdf Celotno besedilo (7,53 MB)
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17.
Phase II study of fluorouracil, leucovorin and interferon alpha-2a in patients with advanced colon cancer
Borut Štabuc, Aleksandra Markovič, Erik Brecelj, Samir Bešlija, Tomaž-Edvard Cizej, 1998, izvirni znanstveni članek

Povzetek: Based on in viro studies that have demonstrated synergy between fluorouracil (5-FU) and leucovorin (LV) as well as between 5-FU and recombinant alpha-2a interferon (IFN) against colon cancer cell lines a phase II study was carried out to evaluate the toxicity and clinical activity of 5-FU modulated with LV and IFN in patients with metastatic colon cancer. Twenty-two chemotherapy naive patients with measurable metastases of colon cancer have been treated with daily doses of 5-FU 600 mg/m2 in 6-hr intravenous infusion, and of LV 20 mg/m2 intravenously and IFN 6 MU subcutaneously, for 5 days every 4 weeks. Median age was 60 years, median PS (ECOG) was 1 (range 0-2). Liver, soft tissue and lung metastases were found in 12, 5 and 8 patients, respectively. Nineteen patients had a single metastatic site, two double, whereas one had more than two metastatic sites. Patients had 2-9 (mean 5) cycles of treatment.Objective response was observed in 7 patients (32%), and stable disease in 7 patients (32%). Overall median survival was 12.5 months, and for responders 14.4 months. Responses were generally short and median time for progression was 5.5 months. The most frequent adverse reactions were flu-like syndrome (50%), nausea/vomiting (36%), diarhoea (13Č), stomatitis (27%) and leucopenia (13%). This regimen of 5-FU with LV and IFN administration does notappear to be superior to previously published shedules of 5-FU with IFN or 5-FU with LV.
Objavljeno v DiRROS: 19.01.2024; Ogledov: 135; Prenosov: 40
.pdf Celotno besedilo (430,62 KB)

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Deformable polyurethane joints and fibre grids for resilient seismic performance of reinforced concrete frames with orthoblock brick infills
Theodoros Rousakis, Alper Ilki, Arkadiusz Kwiecień, Alberto Viskovic, Matija Gams, Petra Triller, Bahman Ghiassi, Andrea Benedetti, Zoran Rakicevic, Camilla Colla, Omer Faruk Halici, BogusŁaw Zając, Łukasz Hojdys, Piotr Krajewski, Fabio Rizzo, Vachan Vanian, Anastasios Sapalidis, Efthimia Papadouli, Aleksandra Bogdanovic, 2020, izvirni znanstveni članek

Povzetek: The behaviour of reinforced concrete frames with masonry wall infills is influenced a lot by the stiffness and strength difference between the frame and the infill, causing early detrimental damage to the infill or to the critical concrete columns. The paper reports the results from shake table seismic tests on a full-scale reinforced concrete (RC) frame building with modified hollow clay block (orthoblock brick) infill walls, within INMASPOL SERA Horizon 2020 project. The building received innovative resilient protection using Polyurethane Flexible Joints (PUFJs) made of polyurethane resin (PU), applied at the frame-infill interface in different schemes. Further, PUs were used for bonding of glass fibre grids to the weak masonry substrate to form Fibre Reinforced Polyurethanes (FRPUs) as an emergency repair intervention. The test results showed enhancement in the in-plane and out-of-plane infill performance under seismic excitations. The results confirmed remarkable delay of significant infill damages at very high RC frame inter-story drifts as a consequence of the use of PUFJs. Further, the PUFJ protection enabled the resilient repair of the infill even after very high inter-story drift of the structure up to 3.7%. The applied glass FRPU system efficiently protected the damaged infills against collapse under out-of-plane excitation while they restored large part of their in-plane stiffness.
Ključne besede: polyurethane, flexible joint, RC column, brick infill, shake table, resilience
Objavljeno v DiRROS: 05.09.2023; Ogledov: 273; Prenosov: 112
.pdf Celotno besedilo (5,77 MB)
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20.
Izzivi medgeneracijskega vodenja v zdravstveni negi
Aleksandra Grbič, 2023, objavljeni znanstveni prispevek na konferenci

Povzetek: Današnja večgeneracijska delovna sila v zdravstveni negi predstavlja edinstvene izzive vodenja. Namen raziskave je prikazati medgeneracijske razlike različnih generacij v zdravstveni negi in vodstvenih "iztočnic", ki bodo vodje usmerjale pri optimalnih strategijah vodenja različnih generacij. Uporabili smo analizo in sintezo pregleda dokazov iz zbirke podatkov CINAHL, PubMed in WEB OF SCIENCE . Ključne iskalne besedne zveze so bile: "nurse", "generation", "multigenerational", "relationship", "teamwork", "leadership". Omejitveni kriteriji iskanja so bili: obdobje 2018 do 2023, celotno besedilo člankov v angleščini. Začetna merila je izpolnjevalo 130 zadetkov, v končno analizo jih je bilo vključenih 9. Rezultati so pokazali, da lahko vodilne medicinske sestre s poznavanjem in razumevanjem ključnih razlik posameznih generacij oblikujejo močnejše time v zdravstveni negi. Razumevanje različnih generacijskih skupin lahko vodjem v zdravstveni negi omogoči razmislek o tem, kaj poganja, motivira ali ovira medicinske sestre različnih generacij. Zaposlovanje in ohranjanje delovne sile, ki jo vse bolj sestavljajo medicinske sestre iz več generacijskih skupin, je izziv, ki ga je mogoče rešiti z globljim razumevanjem vsake od splošno opredeljenih generacijskih skupin
Ključne besede: medicinske sestre, timsko delo, vodenje
Objavljeno v DiRROS: 25.07.2023; Ogledov: 420; Prenosov: 95
.pdf Celotno besedilo (327,75 KB)

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