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1.
Morphological and immunocytochemical characterization of tumor spheroids in ascites from high-grade serous carcinoma
Simona Miceska, Erik Škof, Gorana Gašljević, Veronika Kloboves-Prevodnik, 2023, original scientific article

Abstract: Tumor spheroids in the ascites of high-grade serous carcinoma (HGSC) are poorly described. Our objective was to describe their morphological features, cellular composition, PD-1 and PD-L1 expression, and survival correlation of these parameters. The density and size of spheroids were assessed in Giemsa-stained smears; the cell composition of spheroids, including tumor cells, immune cells, capillaries, and myofibroblasts, as well as PD-1 and PD-L1 expression on tumor and immune cells was assessed in immunocytochemically stained cell block sections. Forty-seven patients with primary HGSC and malignant ascites were included. A cut-off value for a spheroid density of 10% was established, which significantly predicted overall survival. However, spheroid size did not correlate with survival outcomes. Spheroids were primarily composed of tumor cells, but the presence of lymphocytes and macrophages was also confirmed. Moreover, capillaries were present in the spheroids of three patients, but the presence of myofibroblasts was not confirmed. PD-1 was expressed on lymphocytes but not on tumor cells. PD-L1 expression was seen on both tumor and immune cells, assessed by 22C3 and SP263 antibody clones but not by the SP142 clone. Our results highlight the potential of routine cytopathological techniques to analyze spheroids in HGSC ascites as a valuable tool to investigate their potential as prognostic markers.
Keywords: ascites, cell blocks, high-grade serous carcinoma, ovarian carcinoma, spheroids, spheroid-associated immune cells, PD-1, PD-L1
Published in DKUM: 14.02.2024; Views: 50; Downloads: 3
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Poly(HIPEs) from terpenoid-derived acrylates
Stanko Kramer, Nastja Slavič, Peter Krajnc, 2023, original scientific article

Abstract: The need for utilization of non-fossil fuel derived sources for polymer production is growing. In this study the terpenoids tetrahydrogeraniol, citronellol and nopol were modified with an esterification procedure using acryloyl chloride, forming terpenoid acrylates. The synthesised acrylates were used for the production of hierarchically porous polymers via high internal phase emulsion (HIPE) templating with emulsions consisting of an organic (monomer) phase and an aqueous phase with a volume fraction of 85%. The acrylate terpenoids in the organic phase were crosslinked with trimethylolpropane triacrylate (TMPTA) to form the polyHIPEs. A crosslinking degree of 5 and 10 mol% was used to investigate the feasibility of polyHIPE production. While both crosslinking degrees enabled the synthesis of polymers, only the 10 mol% crosslinking yielded the typical interconnected porous cellular topology. The average primary pore diameter in the case of the tetrahydrogeraniol acrylate and citronellyl acrylate was 15.6 and 16.5 μm, respectively, while the average primary pore diameter in the case of nopol acrylate was 5.6 μm.
Keywords: terpenes, polyHIPE, terpenoids, bio-sourced monomers, porous polymers, high internal phase emulsions
Published in DKUM: 26.01.2024; Views: 53; Downloads: 3
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4.
Razvoj modela za spremljanje degradacije površine materiala med dinamičnim obremenjevanjem : doctoral disertation
Marijana Milković, 2023, doctoral dissertation

Abstract: The study focuses on the behavior of the AA7075-T6 material, widely used in the aerospace industry, under dynamic loadings. The material undergoes processing, including cold rolling and stretching, resulting in residual stress compressive stresses on its surface. The research centers on monitoring changes in the surface condition during dynamic loaidngs using Fiber Bragg Grating (FBG) sensors and numerical simulations. The dissertation includes experimental testing of AA 7075-T6 material samples, numerical simulations of optical fiber responses to tensile loads, and an investigation of surface condition changes using techniques such as focused ion beam engraving and scanning electron microscope observation. The study has shown that the surface condition of the material changes even under low dynamic loads, including variations in surface roughness, residual stresses, and FBG response. Despite low load levels, changes in FBG sensor spectra are observable. The dissertation concludes that the surface condition of the material changes during dynamic loadings, detectable through FBG sensors. It underscores the effectiveness of FBG sensors in monitoring stress levels throughout the material’s service life, particularly on the side lobes of the spectral response. In summary, the research on the dynamic behavior of the AA7075-T6 alloy offers valuable insight into surface condition changes that can impact the integrity and durability of materials in the aerospace industry.
Keywords: fatigue, high cycle load, Fiber Bragg grating
Published in DKUM: 05.01.2024; Views: 144; Downloads: 13
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5.
Fracture toughness of HSLA welds made on penstock material
Zdravko Praunseis, 2019, original scientific article

Abstract: The presence of different microstructures along the pre-crack fatigue front has a significant effect on the critical crack tip opening displacement (CTOD). This value is the relevant parameter for the safe servicing of welded structures (penstocks). In the case of specimens with the through-thickness notch partly in the weld metal, partly in the heat-affected zone, and partly in the base material, i.e., using the composite notched specimen, the fracture behaviour significantly depends on the portion of the ductile base material, the size, and the distribution of mismatching factor along the vicinity of the crack front.
Keywords: High Strength low Alloyed Steel, CTOD Fracture Toughness Testing, CTOD-R resistance Curve, Welded joints
Published in DKUM: 22.12.2023; Views: 305; Downloads: 4
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6.
Enhancing the performance of high-growth small- and medium-sized enterprises through effective project- management processes and stakeholder engagement : a systems perspective
Igor Vrečko, Polona Tominc, Karin Širec, 2023, original scientific article

Abstract: This study examines the impact of project management practices on high-growth Small and Medium-sized Enterprises (HG SMEs) from a systems perspective, utilizing Structural Equation Modelling (SEM) and data from a diverse SME sample. It investigates the intricate relationships among project management system support, project management processes, stakeholder involvement, project management success, project success, and HG SME growth. Our findings highlight the substantial positive influence of project management processes and stakeholder engagement on project management success. These factors subsequently contribute significantly to both project success and the overall growth of HG SMEs. Notably, project management system support does not exhibit a substantial influence on these success factors. Furthermore, our research uncovers important indirect effects. Project management processes indirectly impact both project success and HG SME growth, underscoring their central role. Similarly, stakeholder involvement indirectly influences HG SME growth through its impact on project success, emphasizing its significance. This study contributes to the existing body of knowledge by emphasizing the critical roles of project management processes, stakeholder engagement, and project success as drivers of SME growth. These insights have valuable implications for SME managers, project leaders, and policymakers, highlighting the essential nature of effective project management in shaping the growth trajectory of SMEs.
Keywords: project management, project success, SME growth, stakeholder engagement, projectmanagement processes, high-growth SMEs, systems perspective, SEM
Published in DKUM: 13.12.2023; Views: 178; Downloads: 11
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7.
High strain-rate deformation analysis of open-cell aluminium foam
Anja Mauko, Mustafa Sarıkaya, Mustafa Güden, Isabel Duarte, Matej Borovinšek, Matej Vesenjak, Zoran Ren, 2023, original scientific article

Abstract: This study investigated the high-strain rate mechanical properties of open-cell aluminium foam M-pore®. While previous research has examined the response of this type of foam under quasi-static and transitional dynamic loading conditions, there is a lack of knowledge about its behaviour under higher strain rates (transitional and shock loading regimes). To address this gap in understanding, cylindrical open-cell foam specimens were tested using a modified Direct Impact Hopkinson Bar (DIHB) apparatus over a wide range of strain rates, up to 93 m/s. The results showed a strong dependency of the foam's behaviour on the loading rate, with increased plateau stress and changes in deformation front formation and propagation at higher strain rates. The internal structure of the specimens was examined using X-ray micro-computed tomography (mCT). The mCT images were used to build simplified 3D numerical models of analysed aluminium foam specimens that were used in computational simulations of their behaviour under all experimentally tested loading regimes using LS-DYNA software. The overall agreement between the experimental and computational results was good enough to validate the built numerical models capable of correctly simulating the mechanical response of analysed aluminium foam at different loading rates.
Keywords: Open-cell aluminium foam, Micro-computed tomography, High-strain rate, Direct impact hopkinson bar, Digital image correlation, Computer simulation
Published in DKUM: 06.12.2023; Views: 226; Downloads: 17
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8.
Design of Tetra-Peptide Ligands of Antibody Fc Regions Using In Silico Combinatorial Library Screening
Marko Jukič, Sebastjan Kralj, Anja Kolarič, Urban Bren, 2023, original scientific article

Abstract: Abstract Peptides, or short chains of amino-acid residues, are becoming increasingly important as active ingredients of drugs and as crucial probes and/or tools in medical, biotechnological, and pharmaceutical research. Situated at the interface between small molecules and larger macromolecular systems, they pose a difficult challenge for computational methods. We report an in silico peptide library generation and prioritization workflow using CmDock for identifying tetrapeptide ligands that bind to Fc regions of antibodies that is analogous to known in vitro recombinant peptide libraries’ display and expression systems. The results of our in silico study are in accordance with existing scientific literature on in vitro peptides that bind to antibody Fc regions. In addition, we postulate an evolving in silico library design workflow that will help circumvent the combinatorial problem of in vitro comprehensive peptide libraries by focusing on peptide subunits that exhibit favorable interaction profiles in initial in silico peptide generation and testing.
Keywords: peptide design, in silico combinatorial library, peptide combinatorial library, peptide library design, high-throughput virtual screening, peptide molecular docking, antibody purification, peptide drug design, recombinant peptide libraries
Published in DKUM: 01.12.2023; Views: 150; Downloads: 11
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9.
Effect of residual stresses on fatigue strength on the smooth and splined parts of spring torsion bars
Vinko Močilnik, Jožef Predan, Nenad Gubeljak, 2023, original scientific article

Abstract: The article discusses the effect of residual stresses on the fatigue strength of torsion bars by using the Dang Van fatigue criterion, at the stress concentration at the root of the tooth and at the smooth part of the torsion bar. Residual compressive stresses were induced on the surface during the technological processes by cold surface rolling and torsional pre-strain (pre-setting) to the plastic range, to increase the elastic linear range and to reduce the stress state during torsional loading. Normally, the stress reduction in the torsion bar at the mounting point is provided by the increased diameter of the splined part, compared to the smooth part of the torsion bar. In the case of a small difference between the diameter of the splined and the smooth parts of the torsion bar, a fatigue crack can be initiated in the notch, which causes the torsion bar to break during operation after a few hundred loading cycles. FEM stress analysis of a torsion bar was performed in the article. The actual residual stresses were measured by the non-destructive X-ray method at the place of stress concentration on the smooth and splined parts with a notch of the torsion bar, and Dang Van’s failure criterion was used to determine the fatigue behavior during torsional loading. Therefore, in the paper, the three methods were combined to determine the optimum lifetime of a torsion bar exposed to the required cyclic torque. The results of the analysis showed that the residual compressive stresses are useful up to a certain limit where the retarded fatigue crack initiation occurred, but a further increase of compressive stress caused an increase of the maximum shear stresses, which, in turn, caused the initiation of fatigue and failure at the splined part of the torsion bar before achieving the required number of cycles.
Keywords: Dang Van fatigue criterion, torsion bars, pre-setting, high-cycle fatigue, residual stress
Published in DKUM: 30.11.2023; Views: 194; Downloads: 9
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10.
Experimental and numerical analysis of fracture mechanics behavior of heterogeneous zones in S690QL1 grade high strength steel (HSS) welded joint
Damir Tomerlin, Dražan Kozak, Luka Ferlič, Nenad Gubeljak, 2023, original scientific article

Abstract: The heterogeneity of welded joints’ microstructure affects their mechanical properties, which can vary significantly in relation to specific weld zones. Given the dimensional limitations of the available test volumes of such material zones, the determination of mechanical properties presents a certain challenge. The paper investigates X welded joint of S690QL1 grade high strength steel (HSS), welded with slightly overmatching filler metal. The experimental work is focused on tensile testing to obtain stress-strain properties, as well as fracture mechanics testing. Considering the aforementioned limitations of the material test volume, tensile testing is carried out with mini tensile specimens (MTS), determining stress-strain curves for each characteristic weld zone. Fracture mechanical testing is carried out to determine the fracture toughness using the characteristic parameters. The experimental investigation is carried out using the single edge notch bend (SENB) specimens located in several characteristic welded joint zones: base metal (BM), heat affected zone (HAZ), and weld metal (WM). Fractographic analysis provides deeper insight into crack behavior in relation to specific weld zones. The numerical simulations are carried out in order to describe the fracture behavior of SENB specimens. Damage initiation and evolution is simulated using the ductile damage material behavior. This paper demonstrates the possibility of experimental and numerical determination of fracture mechanics behavior of characteristic heterogeneous welded joint zones and their influence on crack path growth.
Keywords: heterogeneous welded joint, high strength steel, mechanical testing, damage, fracture, mechanical properties, finite element analysis
Published in DKUM: 30.11.2023; Views: 215; Downloads: 10
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