1. Fusion behavior of pure magnesium during selective laser meltingSnehashis Pal, Matjaž Finšgar, Jernej Vajda, Uroš Maver, Tomaž Brajlih, Nenad Gubeljak, Hanuma Reddy Tiyyagura, Igor Drstvenšek, 2025, izvirni znanstveni članek Opis: This study examined the melting behavior and flowability of pure magnesium during selective laser melting. The potential to increase product density was also investigated. Various combinations of manufacturing parameters were considered. The laser power was gradually increased in different machine runs, with different scanning speeds for each run to vary the energy density (ED). The laser power ranged from 10 W to 75 W, and the scanning speed ranged from 100 mm/s to 800 mm/s. Lower laser powers resulted in poor melting, while higher laser powers produced better melting, with significant differences even when the ED was the same. High EDs between 3.50 J/mm² and 4.30 J/mm² led to a lack of melting at low laser power and to an unstable melt pool with significant spattering at high laser power. In contrast, moderate EDs in the range of 1.40 J/mm² to 2.90 J/mm² resulted in better density at high laser power. Higher scanning speeds helped to avoid the formation of a dense smog cloud and provided sufficient energy in a short time with the aid of higher laser power. Therefore, increasing both laser power and scanning speed improved melting performance and increased product density. The relative product density ranged from 80 % to 96.5 %. Reducing the layer thickness from 50 µm to 25 µm at a laser power of 40 W resulted in the formation of a well-formed melt pool in some areas and significant melt spattering in others, which led to a deterioration in density.
Ključne besede: magnesium, melt pool, laser power, scanning speed, layer thickness, support structure, laser powder bed fusion
Objavljeno v DKUM: 09.12.2025; Ogledov: 0; Prenosov: 2
 Celotno besedilo (3,08 MB)
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2. Fusion behavior of pure magnesium during selective laser meltingSnehashis Pal, Matjaž Finšgar, Jernej Vajda, Uroš Maver, Tomaž Brajlih, Nenad Gubeljak, Hanuma Reddy Tiyyagura, Igor Drstvenšek, 2025, izvirni znanstveni članek Opis: This study examined the melting behavior and flowability of pure magnesium during selective laser melting. The potential to increase product density was also investigated. Various combinations of manufacturing parameters were considered. The laser power was gradually increased in different machine runs, with different scanning speeds for each run to vary the energy density (ED). The laser power ranged from 10 W to 75 W, and the scanning speed ranged from 100 mm/s to 800 mm/s. Lower laser powers resulted in poor melting, while higher laser powers produced better melting, with significant differences even when the ED was the same. High EDs between 3.50 J/mm² and 4.30 J/mm² led to a lack of melting at low laser power and to an unstable melt pool with significant spattering at high laser power. In contrast, moderate EDs in the range of 1.40 J/mm² to 2.90 J/mm² resulted in better density at high laser power. Higher scanning speeds helped to avoid the formation of a dense smog cloud and provided sufficient energy in a short time with the aid of higher laser power. Therefore, increasing both laser power and scanning speed improved melting performance and increased product density. The relative product density ranged from 80 % to 96.5 %. Reducing the layer thickness from 50 µm to 25 µm at a laser power of 40 W resulted in the formation of a well-formed melt pool in some areas and significant melt spattering in others, which led to a deterioration in density.
Ključne besede: magnesium, melt pool, laser power, scanning speed, layer thickness, support structure, laser powder bed fusion
Objavljeno v DKUM: 09.12.2025; Ogledov: 0; Prenosov: 0 |
3. Oxygen-generating and antibacterial xanthan gum/PLA aerogels loaded with dexamethasone for potential wound healingNika Atelšek Hozjan, Gabrijela Horvat, Matjaž Finšgar, Ana Iglesias-Mejuto, Inés Ardao Palacios, Carlos A. García-González, Željko Knez, Zoran Novak, 2025, izvirni znanstveni članek Opis: Chronic wounds do not heal within a reasonable time frame due to hypoxia and bacterial inflammation, creating an urgent need for advanced biomaterials to address these challenges. In this study, oxygen-generating, antibacterial xanthan gum-polylactic acid (XA/PLA) aerogels loaded with dexamethasone were developed for the first time for potential wound healing applications. The aerogels contained sodium percarbonate and calcium peroxide as oxygen-releasing agents, providing sustained oxygen release for up to 48 h. The aerogels had a highly porous structure with a high specific surface area (up to 396 ± 8 m2/g) and revealed high liquid absorption capacity in simulated body fluid, absorbing up to 67 times their original weight and remaining stable for 72 h. The in vitro release tests showed controlled profiles of dexamethasone over 24 h. The antibacterial tests demonstrated strong antibacterial activity against Escherichia coli (an up to 15.92 mm inhibition zone diameter) and Staphylococcus aureus (up to a 31.07 mm inhibition zone diameter). The in vitro biocompatibility assays revealed good cytocompatibility with mouse fibroblast cells (NIH/3T3), with a cell viability of >90%. Hemocompatibility tests showed no hemolytic activity with human blood (lysis rate <2%). Overall, these results emphasise the versatility of the XA/PLA aerogels and their potential for the treatment of chronic wounds.
Ključne besede: wound healing, aerogels, xanthan gum
Objavljeno v DKUM: 08.12.2025; Ogledov: 0; Prenosov: 1
Celotno besedilo (10,31 MB) |
4. A review of analytical techniques for the analysis of oral smokeless products and heated tobacco productsMatjaž Rantaša, David Majer, Matjaž Finšgar, 2025, pregledni znanstveni članek Opis: The increasing popularity in recent years of oral smokeless products (OSPs) and heated tobacco products (HTPs) has raised significant public health and regulatory concerns. Although these products are often marketed as less harmful alternatives to traditional cigarettes, they differ considerably in both design and, more importantly, in their chemical composition. Notably, they contain potentially dangerous compounds such as tobacco-specific nitrosamines, flavorings, heavy metals, and nicotine, which can be addictive and harmful to human health at certain concentrations. This work provides an overview of the analytical techniques and methods used to analyze OSPs and HTPs, including the determination of moisture content and pH, the extraction of various compounds, the generation of HTP aerosol, and non-targeted analysis, as well as the quantification of extracted compounds using gas chromatography, liquid chromatography, and spectroscopy. Identifying and quantifying the chemical composition of OSPs and HTPs is essential for assessing their health impact and developing proper regulatory standards regarding these products.
Ključne besede: gas chromatography, heated tobacco products, liquid chromatography, nicotine, oral smokeless products
Objavljeno v DKUM: 13.11.2025; Ogledov: 0; Prenosov: 2
Celotno besedilo (1,70 MB) |
5. Surface analysis of sodium metamizolate as an active pharmaceutical ingredient in solid formMatjaž Finšgar, Katja Andrina Varda, 2026, izvirni znanstveni članek Opis: This study focuses on the surface and subsurface characterization of a pharmaceutical tablet containing sodium metamizolate (NaMET), with an emphasis on mass spectrometry using time-of-flight secondary ion mass spectrometry (ToF-SIMS). ToF-SIMS enabled the identification of NaMET-specific fragment ions, which served as signals for the determination of the spatial distribution of this active pharmaceutical ingredient (API) within the tablet matrix. A ToF-SIMS fragmentation mechanism for NaMET was proposed based on the ToF-SIMS spectra analysis measured on a NaMET reference standard. 3D ToF-SIMS imaging showed heterogeneous localization of the API across a 5 μm depth. Complementary techniques, including 3D profilometry and atomic force microscopy (AFM), provided surface roughness and morphological data, while X-ray photoelectron spectroscopy (XPS) confirmed the elemental composition and chemical states. Depth profiling by XPS further supported the non-uniform distribution of NaMET.
Ključne besede: matamizole, sodium metamizolate, ToF-SIMS, XPS, surface analysis, API
Objavljeno v DKUM: 10.11.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (9,03 MB) |
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7. Uporaba sistema dissowash&dose v farmacevtski analitiki : magistrsko deloLana Embreuš, 2025, magistrsko delo Opis: Magistrsko delo prikazuje uporabo sistema dissoWASH&DOSE za izvajanje ciklov čiščenja med izvajanjem testov raztapljanja in določanje prenosa analita (angl. carry over, CO). Teste raztapljanja smo izvedli s tremi aktivnimi farmacevtskimi učinkovinami (API) – kofeinom (KOF), paracetamolom (PA) in natrijevim naproksenatom (NN). Najprej smo izvedli delno validacijo spektrofotometričnih metod za vsak analit. Linearno koncentracijsko območje smo za KOF določili od 1,00 mg/L do 30,00 mg/L, za PA in NN pa od 1,00 mg/L do 19,00 mg/L. Linearnost smo ovrednotili z izračunom kvadrata korelacijskega koeficienta, ki je bil za vse API ≥0,9990 in izračunom koeficienta kvalitete, katerega vrednosti so bile ≤5,00 %. Točnost smo ovrednotili z izračunom povprečnih izkoristkov, ki so bili na treh testiranih koncentracijskih nivojih znotraj zastavljenega kriterija 95,00–105,00 %. Natančnost smo ovrednotili z relativnim standardnim odmikom, ki je bil za vse API <10,00 %. Meja zaznavnosti je bila za vse API <0,01 mg/L. Z določanjem volumnov (V) odmerjanja medija za raztapljanje in medija za čiščenje pri ciklu čiščenja reakcijskih posod in pri ciklu čiščenja pokrova, temperaturnih senzorjev, vzorčevalnih kanul in mešal, smo preverili točnost in natančnost odmerjanja sistema dissoWASH&DOSE. Zastavljena hipoteza je bila, da bo sistem dissoWASH&DOSE uspešno izvedel cikel čiščenja s CO nižjim od 0,50 %. Izvedli smo preizkuse nižanja V čistilnega medija za čiščenje reakcijskih posod ter čiščenje pokrova, temperaturnih senzorjev, vzorčevalnih kanul in mešal, da bi preverili, kako skupni V čistilnega medija obeh ciklov čiščenja vpliva na CO. CO je bil <0,50 % za vse API pri vseh testiranih V čistilnega medija obeh ciklov čiščenja, tj. pri skupnih V obeh ciklov čiščenja 430 mL, 330 mL, 230 mL, 130 mL in 40 mL. Posledično lahko s sistemom dissoWASH&DOSE zadovoljivo očistimo reakcijske posode, pokrove, temperaturne senzorje, vzorčevalne kanule in mešala tudi pri nižjih V čistilnega medija ter je zato primeren za zaporedno izvajanje testov raztapljanja za KOF, NN in PA v farmacevtski analitiki.
Ključne besede: testi raztapljanja, UV-VIS spektrofotometrija, prenos analita, KOF, paracetamol, natrijev naproksenat
Objavljeno v DKUM: 02.07.2025; Ogledov: 0; Prenosov: 52
Celotno besedilo (3,86 MB) |
8. 3D-printed cellulose aerogels minimally cross-linked with polyurea : a robust strategy for tissue engineeringAna Iglesias-Mejuto, Grigorios Raptopoulos, Nanthilde Malandain, Mariana Neves Amaral, Inés Ardao Palacios, Matjaž Finšgar, Anna Laromaine, Anna Roig, Catarina Pinto Reis, Carlos A. García-González, Patrina Paraskevopoulou, 2025, izvirni znanstveni članek Opis: Cellulose and its derivatives are increasingly explored in biomedical applications due to their biocompatibility,biodegradability, and mechanical performance. In regenerative medicine, aerogel scaffolds with tunable morphology and compositionare highly valued for their ability to support tissue regeneration. Three-dimensional (3D) printing offers an effective method tofabricate aerogels with hierarchical pore structures, comprising interconnected macropores and mesopores, that are crucial for tissueengineering. For clinical use, 3D printing should ensure the structural integrity of printed structures and achieve a printing resolutionthat allows for customization. In this work, the X-aerogel technology, implemented via polyurea cross-linking, was applied to 3D-printed cellulose structures, thereby expanding the potential applications of both technologies. Specifically, 3D-printedmethylcellulose (MC) and MC doped with bacterial cellulose nanofiber (MCBCf) gels were cross-linked with an aliphaticpolyurea, yielding, after supercritical drying, the corresponding (X-MC and X-MCBCf) aerogels. Elaborate characterization withATR-FTIR, XPS, ToF-SIMS, N2 porosimetry, He pycnometry, and SEM confirmed the formation of polyurea on the biopolymerframework, reinforcing the structure and improving the mechanical properties without altering the morphology or texturalcharacteristics of the materials. A significant outcome of cross-linking with polyurea is the long-term stability of X-MC and X-MCBCf aerogels in water, in contrast to their native counterparts, and their capacity to absorb water up to 1800% w/w within only 2h. Preliminary biological evaluation of the materials, including in vitro (cell compatibility, hemolytic activity), in ovo (HET-CAM),and in vivo (A. salina model) tests, showed good cell viability, blood compatibility, and safety for living organisms. From afundamental materials perspective, the most important finding of this work is the disproportionally high stability of X-MC and X-MCBCf in physiological environments, achieved with only a minimal (almost undetectable) amount of cross-linking polyurea. Froman application standpoint, the findings of this study, collectively, position these aerogels as sustainable and promising candidates fortissue engineering scaffolds.
Ključne besede: 3D printing, aerogels, cellulose, methylcellulose, polyurea, tissue engineering, X-aerogels
Objavljeno v DKUM: 30.05.2025; Ogledov: 0; Prenosov: 6
Celotno besedilo (7,71 MB) |
9. Surface and subsurface mass spectrometric analysis of dexamethasone in solid pharmaceutical dosage formsMatjaž Finšgar, 2025, izvirni znanstveni članek Opis: This study presents an in-depth mass spectrometric investigation of dexamethasone (DEX) distribution within pharmaceutical tablets using time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with gas cluster ion beam (GCIB) sputtering. Fragmentation mechanism of DEX was identified, which enabled the determination of three-dimensional chemical imaging of the active ingredient in both surface and subsurface regions. The data reveal that a 4-mg DEX formulation exhibits a continuous and extended distribution of the drug into the tablet matrix, while a 0.5-mg formulation shows DEX localized in distinct, isolated domains. Topographical features and the overall composition of the surface were confirmed by complementary analyses employing atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). These results demonstrate how molecule distribution patterns can be linked to formulation heterogeneity using advanced mass spectrometric techniques, opening new possibilities for pharmaceutical manufacturing quality control and optimization.
Ključne besede: mass spectrometry, dexamethasone, pharmaceutical tablets, DEX, ToF-SIMS
Objavljeno v DKUM: 30.05.2025; Ogledov: 0; Prenosov: 5
Celotno besedilo (5,53 MB) |
10. Macroscale superlubricity with a high load-carrying capacity enabled by nitrogen-doped graphene quantum dots in lubricated silicon-doped amorphous carbon filmsIrfan Nadeem, Matjaž Finšgar, Goran Dražić, Bojan Ambrožič, Matjaž Malok, Albano Cavaleiro, Mitjan Kalin, 2025, izvirni znanstveni članek Opis: Achieving macroscale superlubricity with engineering materials is highly desirable for energy conservation, environmental benefits, and longevity of mechanical components. However, attaining superlubricity in aqueous-lubricated systems with enhanced load-bearing capacity remains challenging in metallic materials. Herein, nitrogen-doped graphene quantum dots (NGQDs) as a nano-additive in aqueous glycerol facilitate macroscale superlubricity between friction pairs of steel and silicon-doped hydrogenated amorphous carbon (a-C:H:Si). Superlubricity is observed in boundary-lubrication regime with a friction coefficient of 0.0055–0.0097 under various sliding conditions. Notably, the wear of the steel counterface (k = 8.51 × 10−9 mm3/Nm) decreased by 47.8%, resulting in a final contact pressure of 206.7 MPa, which exceeds values reported for aqueous-lubricated systems during superlubricity. The lubrication mechanism reveals that NGQDs' adsorption on the steel-worn surface, coupled with the tribocatalytic generation of FeNxCy moieties on a-C:H:Si surface, is crucial for reducing friction. These FeNxCy moieties, with a multitude of active sites, facilitate the subsequent anionic adsorption of pyrrolic-rich NGQDs. Simultaneously, the formation of amorphous graphitic film, driven by continuous shearing and exfoliation of graphene sheets within the adsorbed NGQDs, contributes to the stability of superlubricity. These findings provide insights into the functional characteristics of NGQDs for achieving superlubricity in aqueous-lubricated systems, paving the way for future energy-saving applications.
Ključne besede: macroscale superlubricity, metallic materials, streel
Objavljeno v DKUM: 29.05.2025; Ogledov: 0; Prenosov: 100
Celotno besedilo (8,45 MB) |
