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1.
Exploring antioxidative properties of xanthohumol and isoxanthohumol : an integrated experimental and computational approach with isoxanthohumol pKa determination
Jelena Tošović, Zala Kolenc, Gregor Hostnik, Urban Bren, 2025, izvirni znanstveni članek

Opis: This study explores the antioxidative activities of xanthohumol (XN) and isoxanthohumol (IXN), prenylated flavonoids from Humulus lupulus (family Cannabaceae), utilizing the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays along with computational Density Functional Theory methods. Experimentally, XN demonstrated significantly higher antioxidative capacities than IXN. Moreover, we determined IXN pKa values using the UV/Vis spectrophotometric method for the first time, facilitating its accurate computational modeling under physiological conditions. Through a thermodynamic approach, XN was found to efficiently scavenge HOO• and CH3O• radicals via Hydrogen Atom Transfer (HAT) and Radical Adduct Formation (RAF) mechanisms, while CH3OO• scavenging was feasible only through the HAT pathway. IXN exhibited its best antioxidative activity against CH3O• via both HAT and RAF mechanisms and could also scavenge HOO• through RAF. Both Single Electron Transfer (SET) and Sequential Proton Loss-Electron Transfer (SPLET) mechanisms were thermodynamically unfavorable for all radicals and both compounds.
Ključne besede: antioxidative activity, bio-active membranes, xanthohumol, isoxanthohumol, ORAC and FRAP assays, pKa determination, density functional theory, DFT
Objavljeno v DKUM: 31.01.2025; Ogledov: 0; Prenosov: 0
.pdf Celotno besedilo (2,80 MB)

2.
Combined effect of build orientation and energy density on density and mechanical properties of selectively laser melted Co-Cr-W-Si
Snehashis Pal, Igor Drstvenšek, 2022, izvirni znanstveni članek

Opis: The selective laser melting (SLM) process for manufacturing metals continues to be challenging in terms of achieving the maximum metallurgical properties that the process can provide. There are a variety of manufacturing parameters in the process that have individual characteristics, and when combined with other variables, the characteristics can be varied. However, in this study, the two most important manufacturing parameters, namely build direction and laser power, were considered to investigate their effects on density and tensile properties. Previously, the best scanning speed, hatch spacing, and layer thickness were determined, which directly affect the volumetric energy density in the SLM process. In this study, three different orientations and three different laser powers were selected, namely the X, Y, and Z directions and 55 W, 75 W, and 95 W laser power, respectively. Significant differences in product density were observed for the samples fabricated in the different orientations and with the different laser powers. The specimens fabricated in the Z direction always exhibit higher strength and ductility, which are significantly different from the specimens fabricated in the X and Y directions, while the laser power was 75 W and 95 W, respectively
Ključne besede: cobalt-chromium alloy, orientation, density, tensile strength, ductility, selective laser melting
Objavljeno v DKUM: 25.09.2024; Ogledov: 0; Prenosov: 8
.pdf Celotno besedilo (998,89 KB)
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3.
Motor unit discharge rate modulation during isometric contractions to failure is intensity- and modality-dependent
Tamara Valenčič, Paul Ansdell, Callum G. Brownstein, Padraig M. Spillane, Aleš Holobar, Jakob Škarabot, 2024, izvirni znanstveni članek

Opis: The physiological mechanisms determining the progressive decline in the maximal muscle torque production capacity during isometric contractions to task failure are known to depend on task demands. Task-specificity of the associated adjustments in motor unit discharge rate (MUDR), however, remains unclear. This study examined MUDR adjustments during different submaximal isometric knee extension tasks to failure. Participants performed a sustained and an intermittent task at 20% and 50% of maximal voluntary torque (MVT), respectively (Experiment 1). High-density surface EMG signals were recorded from vastus lateralis (VL) and medialis (VM) and decomposed into individual MU discharge timings, with the identified MUs tracked from recruitment to task failure. MUDR was quantified and normalised to intervals of 10% of contraction time (CT). MUDR of both muscles exhibited distinct modulation patterns in each task. During the 20% MVT sustained task, MUDR decreased until ∼50% CT, after which it gradually returned to baseline. Conversely, during the 50% MVT intermittent task, MUDR remained stable until ∼40–50% CT, after which it started to continually increase until task failure. To explore the effect of contraction intensity on the observed patterns, VL and VM MUDR was quantified during sustained contractions at 30% and 50% MVT (Experiment 2). During the 30% MVT sustained task, MUDR remained stable until ∼80–90% CT in both muscles, after which it continually increased until task failure. During the 50% MVT sustained task the increase in MUDR occurred earlier, after ∼70–80% CT. Our results suggest that adjustments in MUDR during submaximal isometric contractions to failure are contraction modality- and intensity-dependent.
Ključne besede: muscle contractions, high-density EMG signals, electromyiograms
Objavljeno v DKUM: 23.08.2024; Ogledov: 117; Prenosov: 10
.pdf Celotno besedilo (3,77 MB)
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4.
Traffic density-related black carbon distribution : impact of wind in a basin town
Borut Jereb, Brigita Gajšek, Gregor Šipek, Špela Kovše, Matevž Obrecht, 2021, izvirni znanstveni članek

Opis: Black carbon is one of the riskiest particle matter pollutants that is harmful to human health. Although it has been increasingly investigated, factors that depend on black carbon distribution and concentration are still insufficiently researched. Variables, such as traffic density, wind speeds, and ground levels can lead to substantial variations of black carbon concentrations and potential exposure, which is even riskier for people living in less-airy sites. Therefore, this paper "fills the gaps" by studying black carbon distribution variations, concentrations, and oscillations, with special emphasis on traffic density and road segments, at multiple locations, in a small city located in a basin, with frequent temperature inversions and infrequent low wind speeds. As wind speed has a significant impact on black carbon concentration trends, it is critical to present how low wind speeds influence black carbon dispersion in a basin city, and how black carbon is dependent on traffic density. Our results revealed that when the wind reached speeds of 1 ms-1 , black carbon concentrations actually increased. In lengthy wind periods, when wind speeds reached 2 or 3 ms-1 , black carbon concentrations decreased during rush hour and in the time of severe winter biomass burning. By observing the results, it could be concluded that black carbon persists longer in higher altitudes than near ground level. Black carbon concentration oscillations were also seen as more pronounced on main roads with higher traffic density. The more the traffic decreases and becomes steady, the more black carbon concentrations oscillate.
Ključne besede: black carbon, black carbon concentration, traffic pollution, air pollution, wind, traffic density, logistics, basin city
Objavljeno v DKUM: 20.08.2024; Ogledov: 44; Prenosov: 8
.pdf Celotno besedilo (2,71 MB)
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5.
Investigation of the best manufacturing orientation of Co-Cr-W-Si dental prosthetic elements in the selective laser melting process
Snehashis Pal, Janez Gotlih, Igor Drstvenšek, 2022, izvirni znanstveni članek

Opis: It is well known that Selective Laser Melting (SLM) does not provide the same mechanical properties in all directions of the part. This is due to the microstructural grain orientation and pore shape in SLM products. Therefore, depending on the direction of the pressure applied to the SLM product, a different manufacturing orientation is required to achieve the best mechanical properties. Changing the microstructural grain orientation is difficult through SLM, but a process to reduce the size and number of the pores can be discovered through different combinations of manufacturing parameters. In prosthodontics, pressure is usually applied in the vertical direction, which leads to compression and bending of crowns with bridges. The compressive load can be easily absorbed in the crowns, but the bending force has a significant effect here. Therefore, a product with high tensile strength and high ductility is needed to survive longer. Considering these requirements, this study determined the best parameters for laser processing by SLM method to reduce porosity and improve mechanical strength and ductility of Co-CrW-Si alloy products. The result is a relative product density of 100% for cubic specimens and a yield strength, ultimate tensile strength, and elongation at break of the tensile specimens of 900 MPa, 1200 MPa, and 15%, respectively, obtained in specimen build-up in the Z direction with a laser power of 60 W and a scanning speed of 450 mm/s. Eventually, the best orientation for the production of dental prosthetic elements using the SLM process was determined.
Ključne besede: cobalt-chromium alloy, dental implant, density, tensile strength, ductility, selective laser melting
Objavljeno v DKUM: 03.07.2024; Ogledov: 78; Prenosov: 12
.pdf Celotno besedilo (640,47 KB)
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Materials for HybridNeuro webinar titled "Validation of results: statistical models and MU identification accuracy"
Aleš Holobar, Nina Murks, 2024, zaključena znanstvena zbirka raziskovalnih podatkov

Opis: This dataset contains a collection of teaching materials that were used in the HybridNeuro project webinar titled "Validation of results: statistical models and MU identification accuracy". The webinar was presented by Aleš Holobar and covered the complexities of motor unit (MU) identification accuracy, regression analysis and Bayesian models. The primary aim of the webinar was to spark a robust discussion within the scientific community, particularly focusing on the application and implications of linear mixed models and Bayesian regression in the realm of MU identification. The teaching materials include Matlab and R source code for statistical analysis of the included data, as well as three examples of MU identification results in CSV format (from both synthetic and experimental HDEMG signals). The presentation slides in PDF format are also included. The dataset is approximately 9 MB in size.
Ključne besede: HybridNeuro, webinar, teaching materials, statistical models, regression analysis, motor unit identification, matlab, rstudio, statistics, surface high density electromyogram (HDEMG), tibialis anterior, dataset
Objavljeno v DKUM: 30.05.2024; Ogledov: 221; Prenosov: 23
.pdf Celotno besedilo (108,35 KB)
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9.
Simulated and experimental HDEMG signals of biceps brachii muscle for analysis of motor unit merging
Aleš Holobar, Jakob Škarabot, Dario Farina, 2024, zaključena znanstvena zbirka raziskovalnih podatkov

Opis: This dataset contains a collection of simulated and experimental surface HDEMG recordings of the biceps brachii muscle during the isometric elbow flexion. Simulated data contains 50 recordings: 5 subjects and 5 excitation levels, each with and without added noise. Experimental data contains 16 recordings: 2 subjects with 4 excitation levels and 2 repetitions of each level. Synthetic data was simulated using the cylindrical volume conductor model [1] and the motor unit recruitment and firing modulation model proposed in [2]. Each recording is 20 seconds in length with 90 HDEMG channels sampled at 2048 Hz and is stored as a 2D matrix of raw EMG values in Matlab’s MAT format. Experimental surface EMG data was recorded on two volunteers during isometric contractions at constant force level. Each recording is 25 seconds in length with 64 HDEMG channels sampled at 2048 Hz and is also stored as a 2D matrix of raw EMG values in Matlab’s MAT format. The dataset is approximately 1.5 GB in size.
Ključne besede: surface high density electromyogram (HDEMG), motor unit, spike train, motor unit merging, simulated data, experimental data, biceps brachii, dataset
Objavljeno v DKUM: 30.05.2024; Ogledov: 172; Prenosov: 14
.pdf Celotno besedilo (125,29 KB)
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10.
Simulated HDEMG data of biceps brachii muscle during isometric elbow flexion
Aleš Holobar, Dario Farina, 2024, zaključena znanstvena zbirka raziskovalnih podatkov

Opis: This dataset contains a collection of 150 simulated surface HDEMG recordings of the biceps brachii muscle during the isometric elbow flexion. Data was simulated using the cylindrical volume conductor model [1] and the motor unit recruitment and firing modulation model proposed in [2]. Each recording is 30 seconds in length with 90 HDEMG channels and sampled at 2048 Hz and is stored as a 2D matrix of raw EMG values in Matlab’s .MAT format. The dataset is 6 GB in size.
Ključne besede: surface high density electromyogram (HDEMG), motor unit, simulation, biceps brachii, elbox flexion, dataset
Objavljeno v DKUM: 30.05.2024; Ogledov: 260; Prenosov: 34
.pdf Celotno besedilo (109,56 KB)
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