1. High strain-rate deformation analysis of open-cell aluminium foamAnja Mauko, Mustafa Sarıkaya, Mustafa Güden, Isabel Duarte, Matej Borovinšek, Matej Vesenjak, Zoran Ren, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: Open-cell aluminium foam, Micro-computed tomography, High-strain rate, Direct impact hopkinson bar, Digital image correlation, Computer simulation
Objavljeno v DKUM: 06.12.2023; Ogledov: 68; Prenosov: 8
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2. Design of Tetra-Peptide Ligands of Antibody Fc Regions Using In Silico Combinatorial Library ScreeningMarko Jukič, Sebastjan Kralj, Anja Kolarič, Urban Bren, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: 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
Objavljeno v DKUM: 01.12.2023; Ogledov: 29; Prenosov: 4
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3. Effect of residual stresses on fatigue strength on the smooth and splined parts of spring torsion barsVinko Močilnik, Jožef Predan, Nenad Gubeljak, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: Dang Van fatigue criterion, torsion bars, pre-setting, high-cycle fatigue, residual stress
Objavljeno v DKUM: 30.11.2023; Ogledov: 71; Prenosov: 5
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4. Experimental and numerical analysis of fracture mechanics behavior of heterogeneous zones in S690QL1 grade high strength steel (HSS) welded jointDamir Tomerlin, Dražan Kozak, Luka Ferlič, Nenad Gubeljak, 2023, izvirni znanstveni članek Opis: 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.
Ključne besede: heterogeneous welded joint, high strength steel, mechanical testing, damage, fracture, mechanical properties, finite element analysis
Objavljeno v DKUM: 30.11.2023; Ogledov: 75; Prenosov: 4
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5. P-x,y equilibrium data of the binary systems of 2-propanol, 1-butanol and 2-butanol with carbon dioxide at 313.15 K and 333.15 KDragana Borjan, Maša Knez Marevci, Željko Knez, 2022, izvirni znanstveni članek Opis: The ability to predict the behaviour of high-pressure mixtures of carbon dioxide and alcohol is important for industrial purposes. The equilibrium composition of three binary carbon dioxide-alcohol systems was measured at temperatures of 313.15 K and 333.15 K and at pressures of up to 100 bar for carbon dioxide-2-propanol, up to 160 bar for carbon dioxide-1-butanol and up to 150 bar for carbon dioxide-2-butanol. Different equilibrium compositions of carbon dioxide in alcohols were observed despite their similar molecular weight (M2-propanol = 60.100 g mol−1, M1-butanol = 74.121 g mol−1 and M2-butanol = 74.122 g mol−1) and place in the functional hydroxyl group (first or second carbon molecule). It is assumed that the differences in the phase equilibria are due to different vapor pressures, polarities and solute-solute interactions.
Ključne besede: high-pressure phase equilibrium, carbon dioxide, 2-propanol, 1-butanol, 2-butanol
Objavljeno v DKUM: 17.08.2023; Ogledov: 128; Prenosov: 13
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6. Comparative Analyses of Medicinal Chemistry and Cheminformatics Filters with Accessible Implementation in Konstanz Information Miner (KNIME)Sebastjan Kralj, Marko Jukič, Urban Bren, 2022, izvirni znanstveni članek Opis: High-throughput virtual screening (HTVS) is, in conjunction with rapid advances in computer hardware, becoming a staple in drug design research campaigns and cheminformatics. In this context, virtual compound library design becomes crucial as it generally constitutes the first step where quality filtered databases are essential for the efficient downstream research. Therefore, multiple filters for compound library design were devised and reported in the scientific literature. We collected the most common filters in medicinal chemistry (PAINS, REOS, Aggregators, van de Waterbeemd, Oprea, Fichert, Ghose, Mozzicconacci, Muegge, Egan, Murcko, Veber, Ro3, Ro4, and Ro5) to facilitate their open access use and compared them. Then, we implemented these filters in the open platform Konstanz Information Miner (KNIME) as a freely accessible and simple workflow compatible with small or large compound databases for the benefit of the readers and for the help in the early drug design steps.
Ključne besede: high-throughput virtual screening, virtual screening, compound libraries, library design, compound filtering
Objavljeno v DKUM: 25.07.2023; Ogledov: 211; Prenosov: 10
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7. Inter-person differences in isometric coactivations of triceps surae and tibialis anterior decrease in young, but not in older adults after 14 days of bed restMatjaž Divjak, Gašper Sedej, Nina Murks, Mitja Gerževič, Uroš Marušič, Rado Pišot, Boštjan Šimunič, Aleš Holobar, 2022, izvirni znanstveni članek Opis: We examined activation patterns of the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), soleus (SO), and tibialis anterior (TA) muscles in eight older (58.4 ± 3.3 years) and seven young (23.1 ± 2.9 years) participants, before and after 14 days of horizontal bed rest. Visual feedback on the exerted muscle torque was provided to the participants. The discharge patterns of individual motor units (MUs) were studied in three repetitions of isometric plantar flexion at 30 and 60% of Maximum Voluntary Contraction (MVC), before, and 1 day after the 14-day bed rest, respectively. In the GL and GM muscles, the older participants demonstrated higher MU discharge rates than the young, regardless of the contraction level, both before and after the bed rest. In the TA and SO muscles, the differences between the older and young participants were less consistent. Detailed analysis revealed person-specific changes in the MU discharge rates after the bed rest. To quantify the coactivation patterns we calculated the correlation coefficients between the cumulative spike trains of identified MUs from each muscle, and measured the root mean square difference of the correlation coefficients between the trials of the same session (intra-session variability) and between different sessions (inter-session variability) in each participant (intra-person comparison) and across participants (inter-person comparison). In the intra-person comparison, the inter-session variability was higher than the intra-session variability, either before or after the bed rest. At 60% MVC torque, the young demonstrated higher inter-person variability of coactivation than the older participants, but this variability decreased significantly after the bed rest. In older participants, inter-person variability was consistently lower at 60% than at 30% MVC torque. In young participants, inter-person variability became lower at 60% than at 30% MVC torque only after the bed rest. Precaution is required when analyzing the MU discharge and coactivation patterns, as individual persons demonstrate individual adaptations to aging or bed rest.
Ključne besede: mišičnoskeletni sistem, mišice, bed rest, staranje, elektromiografija, high density electromyography, muscle disuse, motor units, discharge rate, aging
Objavljeno v DKUM: 07.07.2023; Ogledov: 265; Prenosov: 35
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8. Immunity of Heads of State and High-Ranking State Officials for International Crimes : magistrsko deloAdmir Muratović, 2021, magistrsko delo Opis: The present thesis is devoted to the immunity of Heads of State and high-ranking State officials, generally meaning the Heads of Government, and the Foreign Ministers, before the national and international courts, for international crimes as codified in the Rome Statute of the International Criminal Court (ICC), namely the crime of genocide, crimes against humanity, war crimes and the crime of aggression, with partial touch upon the crime of torture as well.
The introductory part lays out the prosecution of State officials throughout the history all the way to the World War II, the Nuremberg and Tokyo Trials, and the developments in the decades post-World War II, with the eventual establishment of the ICC. Afterwards, the definitions and list of international crimes are discussed.
Following the arguments for the rationale behind immunity and the correlation between immunity and jurisdiction, I elaborate on the various types of immunity, such as State immunity – and its subcategories personal and functional immunities – and diplomatic immunity. Thereby, I discuss at length the range of seemingly outstanding questions relating to, e.g., the scope of State officials entitled to immunity ratione personae, whether the commission of international crimes constitute officials acts, whether the immunity of State precludes a lawsuit towards State for breaches of jus cogens norms by acts that qualify as acta jure imperii, whether the diplomatic immunity pertains to high-ranking State officials other than ambassadors and diplomatic agents, etc. The explanations of other, less debatable questions, such as the distinction between personal and functional immunities for international crimes before national courts, is also provided.
In the following part, I analyse the immunity of the incumbent high-ranking State officials before international courts, with a particular focus set on the ICC and Article 27 of the Rome Statute. Emphasizing provisions concerning international cooperation and judicial assistance to the ICC, I bring up Article 98 of the Rome Statute as a counterweight to the rejection of immunity before the ICC, and consider the interplay between both, Articles 27 and 98. Another point of divergence here is the question of which States fall under the scope of the term ‘third State’ in Article 98 of the Rome Statute. Furthermore, the analysis of the Al-Bashir case is provided through the application of the United Nations (UN) Security Council Resolution 1593 (2005), as well as Articles 25 and 103 of the UN Charter. Additionally, I intend to provide a method of resolving some of the ambiguities stemming out of the seemingly contradicting Rome Statute provisions by applying the rules of treaty interpretation, in particular its subsidiary means, discerning the object and purpose of the Rome Statute through the lenses of its Preamble.
In the final part, I have sought out various other concepts that could supersede the immunity of high-ranking State officials for international crimes, including the jus cogens international crime exception to immunity, the obligation aut dedere aut judicare, and the universal jurisdiction.
Ključne besede: State immunity, immunity ratione personae, immunity ratione materiae, Heads of State, high-ranking State officials, international crimes, international courts, International Criminal Court (ICC), Rome Statute, Al-Bashir case, UN Security Council
Objavljeno v DKUM: 23.07.2021; Ogledov: 1012; Prenosov: 108
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10. FORMULATION, PREPARATION AND CHARACTERIZATION OF NANOEMULSIONS FOR PARENTERAL NUTRITION : doctoral disertationDušica Mirković, 2019, doktorska disertacija Opis: The aim of this doctoral research was to develop and optimize parenteral nanoemulsions as well as the total parenteral nutrition (TPN) admixture containing a nanoemulsion obtained in the course of the optimization process (hereinafter referred to as optimal nanoemulsion), and to examine their physicochemical and biological quality as well. In addition, the quality of the prepared nanoemulsions was compared with the quality of the industrial nanoemulsion (Lipofundin® MCT/LCT 20%), and, in the end, the TPN admixture initially prepared was also compared with the admixture into which the industrial emulsion was incorporated.
Parenteral nanoemulsions that were considered in this dissertation were prepared by the high-pressure homogenization method. This method is the most widely applied method for the production of nanoemulsions due to the shortest length of homogenization time, the best-obtained homogeneity of the product and the smallest droplet diameter.
For the nanoemulsion formulation, preparation and optimization purposes, by using, firstly, the concept of the computer-generated fractional design, and, after that, the full experimental design, the assessment of both direct effects of different formulation and process parameters (the oil phase type, the emulsifier type and concentration, a number of homogenization cycles and the pressure under which homogenization was carried out) as well as the effects of their interactions on the characteristics of prepared nanoemulsions was performed.
Monitoring the nanoemulsion physical and chemical stability parameters was carried out immediately after their preparation, and then after 10, 30 and 60 days. It included the visual inspection, the measurement of the droplet diameter (the mean and volume droplet diameter), the polydispersity index, the ζ-potential, the pH value, the electrical conductivity, and the peroxide number. After the preparation and after 60 days, the biological evaluation (the sterility test and the endotoxic test) of the prepared nanoemulsions was carried out. As far as the characterization of the TPN admixture is concerned, it included practically the same parameters. The dynamics of monitoring the characteristics of the TPN admixture was determined on the basis of practical needs of hospitalized patients (0h, 24h and 72h).
The scope and comprehensiveness of this issue indicated the need to divide the doctoral dissertation into three basic stages. The first stage was preliminary. Using the 24-1 fractional factorial design, nanoemulsions for the parenteral nutrition were prepared. They contained either a combination of soybean and fish oil, or a combination of medium chain triglycerides and fish oil. In addition, the type and the amount of an emulsifier used, a number of high-pressure homogenization cycles, and the homogenization pressure, were also varied. The measurement of the above-mentioned parameters for the industrial nanoemulsion was parallely carried out (Lipofundin® MCT/LCT 20%). The objective of this part of the research was to identify critical numerical factors having the most significant effect on the characteristics that define the prepared parenteral nanoemulsions. Parameters that were singled out as the result of this stage of the research (the emulsifier concentration and a number of homogenization cycles) were used as independent variables in the second stage of the research.
Ključne besede: nanoemulsions, total parenteral nutrition admixtures, high pressure homogenization, design of experiments, optimization, analysis of variance, artificial neural networks
Objavljeno v DKUM: 07.06.2019; Ogledov: 11679; Prenosov: 17
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