1. Mechanism elucidation of high-pressure generation in cellular metal at high-velocity impactMasatoshi Nishi, Shigeru Tanaka, Akihisa Mori, Matej Vesenjak, Zoran Ren, Kazuyuki Hokamoto, 2022, izvirni znanstveni članek Opis: Cellular metals exhibit diverse properties, depending on their geometries and base materials. This study investigated the mechanism of high-pressure generation during the high-velocity
impact of unidirectional cellular (UniPore) materials. Cubic UniPore copper samples were mounted
on a projectile and subjected to impact loading using a powder gun to induce direct impact of samples.
The specimens exhibited a unique phenomenon of high-pressure generation near the pores during
compression. We elucidate the mechanism of the high-pressure phenomenon and discuss the pore
geometries that contribute to the generation of high pressures.
Ključne besede: cellular metal, high-pressure, high-velocity impact, computational simulation, metal jet
Objavljeno v DKUM: 24.03.2025; Ogledov: 0; Prenosov: 2
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2. Total Knee replacement with an uncemented porous tantalum tibia component: A failure analysisSamo K. Fokter, Nenad Gubeljak, Esther Punzón Quijorna, Primož Pelicon, Mitja Kelemen, Primož Vavpetič, Jožef Predan, Luka Ferlič, Igor Novak, 2022, izvirni znanstveni članek Opis: Porous tantalum has been extensively used in orthopaedic surgery, including uncemented
total knee arthroplasty (TKA). Favourable results were reported with earlier monobloc tibial components and the design evolved to modular implants. We aimed to analyse possible causes for extensive
medial tibia bone loss, resulting in modular porous tantalum tibia baseplate fracture after primary
TKA. Retrieved tissue samples were scanned with 3 MeV focused proton beam for Proton-Induced
X-ray Emission (micro-PIXE) elemental analysis. Fractographic and microstructural analysis were
performed by stereomicroscopy. A full 3D finite-element model was made for numerical analysis
of stress–strain conditions of the tibial baseplate. Histological examination of tissue underneath
the broken part of the tibial baseplate revealed dark-stained metal debris, which was confirmed by
micro-PIXE to consist of tantalum and titanium. Fractographic analysis and tensile testing showed
that the failure of the tibial baseplate fulfilled the criteria of a typical fatigue fracture. Microstructural
analysis of the contact surface revealed signs of bone ingrowth in 22.5% of the surface only and
was even less pronounced in the medial half of the tibial baseplate. Further studies are needed to
confirm the responsibility of metal debris for an increased bone absorption leading to catastrophic
tibial tray failure.
Ključne besede: total knee arthroplasty, uncemented, cementless, trabecular metal, porous tantalum, tibial component, cementless baseplate fracture
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 2
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3. Effects of fixture configurations and weld strength mismatch on J-integral calculation procedure for SE(B) specimensPrimož Štefane, Stijn Hertelé, Sameera Naib, Wim de Waele, Nenad Gubeljak, 2022, izvirni znanstveni članek Opis: This work presents the development of a J-integral estimation procedure for deep and
shallow cracked bend specimens based upon plastic ηpl factors for a butt weld made in an S690 QL
high strength low alloyed steel. Experimental procedures include the characterization of average
material properties by tensile testing and evaluation of base and weld metal resistance to stable tearing
by fracture testing of square SE(B) specimens containing a weld centerline notch. J-integral has been
estimated from plastic work using a single specimen approach and the normalization data reduction
technique. A comprehensive parametric finite element study has been conducted to calibrate plastic
factor ηpl and geometry factor λ for various fixture and weld configurations, while a corresponding
plastic factor γpl was computed on the basis of the former two. The modified ηpl and γpl factors were
then incorporated in the J computation procedure given by the ASTM E1820 standard, for evaluation
of the plastic component of J and its corresponding correction due to crack growth, respectively. Two
kinds of J-R curves were computed on the basis of modified and standard ηpl and γpl factors, where
the latter are given by ASTM E1820. A comparison of produced J-R curves for the base material
revealed that variations in specimen fixtures can lead to ≈10% overestimation of computed fracture
toughness JIc. Furthermore, a comparison of J-R curves for overmatched single-material idealized
welds revealed that the application of standard ηpl and γpl factors can lead to the overestimation of
computed fracture toughness JIc by more than 10%. Similar observations are made for undermatched
single material idealized welds, where fracture toughness JIc is overestimated by ≈5%.
Ključne besede: metal weld, strength mismatch, fracture, plastic correction factors, fixture rollers, J-R resistance curve
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 2
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5. The thermomechanical, functional and biocompatibility properties of a Au–Pt–Ge alloy for PFM dental restorationsPeter Majerič, Minja Miličić Lazić, Dijana Mitić, Marko Lazić, Ema Krdžović Lazić, Gyöngyi Vastag, Ivan Anžel, Vojkan Lazić, Rebeka Rudolf, 2024, izvirni znanstveni članek Opis: A high-noble Au–Pt–Ge porcelain-fused-to-metal (PFM) dental alloy without the known adverse metallic elements and with the addition of germanium (Ge) was produced as a more cost-effective alternative to other precious alloying metals, with investigations for determining the functionality and clinical use of this alloy. The thermomechanical, biocompatibility, durability, workability and economic characteristics of the produced dental alloy were investigated. These properties were investigated with in vitro biocompatibility testing on human gingival fibroblasts (HGFs); static immersion testing for metal ion release; DSC analysis; hardness, tensile testing, density and coefficient of thermal expansion (CTE) measurements; metallographic and SEM/EDX microstructure investigations; and finally with the production of a test PFM dental bridge. The results of the thermomechanical testing showed alloy properties suitable for dental restorations and clinical use, with somewhat lower mechanical properties, making the alloy not suitable for extensive multiunit fixed restorations. The microstructure investigations showed segregations of Ge in the homogeneous alloy matrix, which reduce the alloy’s mechanical properties. The produced PFM dental bridge showed excellent workability of the alloy in a dental laboratory setting, as well as a high standard of the final dental restoration. The ion release was negligible, well below any harmful quantities, while the cell viability examination showed significantly higher viability ratings on polished alloy samples as compared to as-cast samples. The results showed that a dental substructure in direct contact with oral tissue and fluids should be highly polished. The performed investigations showed that the produced PFM dental alloy is suitable for clinical use in producing high-quality dental restorations with high biocompatibility for patients prone to metal allergies
Ključne besede: noble metal dental alloys, metal–ceramic alloys, materials testing, biocompatibility testing
Objavljeno v DKUM: 25.11.2024; Ogledov: 0; Prenosov: 7
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6. Potentiometric surfactant sensor with a pt-doped acid-activated multi-walled carbon nanotube-based ionophore nanocompositeNada Glumac, Milan Momčilović, Iztok Kramberger, Darko Štraus, Nikola Sakač, Elvira Kovač-Andrić, Bojan Đurin, Marija Kraševac Sakač, Kristina Đambić, Marija Jozanović, 2024, izvirni znanstveni članek Opis: Two new surfactant sensors were developed by synthesizing Pt-doped acid-activated multiwalled carbon nanotubes (Pt@MWCNTs). Two different ionophores using Pt@MWCNTs, a new plasticizer, and (a) cationic surfactant 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-DHBI (Pt@MWCNT-DHBI ionophore) and (b) anionic surfactant dodecylbenzenesulfonate-DBS (Pt@MWCNT-DBS ionophore) composites were successfully synthesized and characterized. Both surfactant sensors showed a response to anionic surfactants (dodecylsulfate (SDS) and DBS) and cationic surfactants (cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium bromide (CTAB)). The Pt@MWCNT-DBS sensor showed lower sensitivity than expected with the sub-Nernstian response of ≈23 mV/decade of activity for CPC and CTAB and ≈33 mV/decade of activity for SDS and DBS. The Pt@MWCNTDHBI surfactant sensor had superior response properties, including a Nernstian response to SDS (59.1 mV/decade) and a near-Nernstian response to DBS (57.5 mV/decade), with linear response regions for both anionic surfactants down to ≈2 × 10−6 M. The Pt@MWCNT-DHBI was also useful in critical micellar concentration (CMC) detection. Common anions showed very low interferences with the sensor. The sensor was successfully employed for the potentiometric titration of a technical grade cationic surfactant with good recoveries. The content of cationic surfactants was measured in six samples of complex commercial detergents. The Pt@MWCNT-DHBI surfactant sensor showed good agreement with the ISE surfactant sensor and classical two-phase titration and could be used as an analytical tool in quality control
Ključne besede: potentiometric surfactant sensor, metal-doped MWCNT, surfactants, carbon nanocomposite, sensors
Objavljeno v DKUM: 23.08.2024; Ogledov: 110; Prenosov: 9
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8. Comprehensive analysis of different coating materials on the POM substrateTonica Bončina, Srečko Glodež, Brigita Polanec, Lara Hočuršćak, Franc Zupanič, 2023, izvirni znanstveni članek Opis: This study presents a comprehensive analysis of different coating materials on the POM substrate. Specifically, it investigated physical vapour deposition (PVD) coatings of aluminium (Al), chromium (Cr), and chromium nitride (CrN) of three various thicknesses. The deposition of Al was accomplished through a three-step process, particularly plasma activation, metallisation of Al by magnetron sputtering, and plasma polymerisation. The deposition of Cr was attained using the magnetron sputtering technique in a single step. For the deposition of CrN, a two-step process was employed. The first step involved the metallisation of Cr using magnetron sputtering, while the second step involved the vapour deposition of CrN, obtained through the reactive metallisation of Cr and nitrogen using magnetron sputtering. The focus of the research was to conduct comprehensive indentation tests to obtain the surface hardness of the analysed multilayer coatings, SEM analyses to examine surface morphology, and thorough adhesion analyses between the POM substrate and the appropriate PVD coating.
Ključne besede: POM, PVD coating, metal coating, adhesion analyses, indentation tests
Objavljeno v DKUM: 15.02.2024; Ogledov: 304; Prenosov: 38
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9. Nanomaterials and their recent applications in impedimetric biosensingZala Štukovnik, Regina Fuchs-Godec, Urban Bren, 2023, pregledni znanstveni članek Opis: Impedimetric biosensors measure changes in the electrical impedance due to a biochemical process, typically the binding of a biomolecule to a bioreceptor on the sensor surface. Nanomaterials can be employed to modify the biosensor's surface to increase the surface area available for biorecognition events, thereby improving the sensitivity and detection limits of the biosensor. Various nanomaterials, such as carbon nanotubes, carbon nanofibers, quantum dots, metal nanoparticles, and graphene oxide nanoparticles, have been investigated for impedimetric biosensors. These nanomaterials have yielded promising results in improving sensitivity, selectivity, and overall biosensor performance. Hence, they offer a wide range of possibilities for developing advanced biosensing platforms that can be employed in various fields, including healthcare, environmental monitoring, and food safety. This review focuses on the recent developments in nanoparticle-functionalized electrochemical-impedimetric biosensors.
Ključne besede: impedimetric biosensor, electrochemical impedance spectroscopy, nanomaterials, metal nanoparticles, carbon nanofibers, carbon nanotubes, graphene oxide, quantum dots
Objavljeno v DKUM: 12.02.2024; Ogledov: 6175; Prenosov: 32
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10. Simulation of Dual-Beam Laser Metal Deposition : magistrsko deloMatej Kočevar, 2021, magistrsko delo Opis: Laser metal deposition process plays an important role in the coating and additive manufacturing of the components. Implementation of dual-beam process represents a further development and offers the advantage of laser ablation process, which provides exert force on the melt pool and increases absorption properties of the workpiece for laser light in comparison to conventional laser metal deposition processes.
The main goal of the present work is to predict temperature distribution on the surface and in the cross-section during a dual-beam laser metal deposition. A better understanding of temperature distribution of the dual-beam laser metal deposition is crucial for analyzing the impact of different process parameters on the process. The prediction of temperature distribution was done using the version 6.14-6 of finite element software ABAQUS/Standard from Dassault Systèmes. The results of the simulations show that the temperature distribution in the case of dual-beam laser metal deposition can be determined with minimum deviation by utilizing the finite element analysis.
Ključne besede: Laser Metal Deposition (LMD), dual-beam process, wire-based Laser Metal Deposition (LMD-w), Finite Element Method (FEM)
Objavljeno v DKUM: 23.09.2021; Ogledov: 1214; Prenosov: 73
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