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Povzetek: Incorporating cyclodextrins (CDs) into ionically crosslinked polysaccharide matrices offers a promising strategy for developing well-defined, safe-by-design and biocompatible carrier systems with tunable rheological properties. In this study, β-cyclodextrin (β-CD) was functionalized with citric acid (CDC) and maleic anhydride (CDM) using solvent-free synthesis to improve compatibility with alginate hydrogels. The modified CDs were characterized by FTIR, 1H NMR, DLS, zeta potential, and MS, confirming successful esterification (4.0 and 3.4 –OH substitution for CDC and CDM, respectively) and stable aqueous dispersion. Rheological measurements showed that native CD accelerated gelation (within approximately 30 s), while CDC and CDM delayed crosslinking (by 2 to 13 min) and reduced gel strength, narrowing the linear viscoelastic range to 0.015–0.089% strain due to competition between polycarboxylated CDs and alginate chains for Ca2+ ions. Vibrational prilling produced alginate microbeads with diameters of 800–1000 µm and a simultaneous increase in size and CD concentration. Hydrogels demonstrated high CD retention (>80% after 28 h) and slightly greater release of CDC and CDM than native CD. Overall, solvent-free modification of CDs with citric and maleic acids provides a sustainable approach to tailoring the gelation kinetics, viscoelasticity, and release behavior of alginate-based hydrogels, offering a versatile, food- and health-compliant platform for controlled delivery of bioactive compounds.
Ključne besede: cyclodextrin, alginate, dry modification, solvent-free, hydrogels, viscoelasticity, rheometry, microcarrier design
Objavljeno v DiRROS: 25.11.2025; Ogledov: 1126; Prenosov: 359
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Ključne besede: ADC12 aluminum alloy, Y-modification, T6 heat treatment, deep etching, mechanical properties, orthogonal analysis
Objavljeno v DiRROS: 20.08.2025; Ogledov: 1113; Prenosov: 509
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Povzetek: Magnesium and its alloys have emerged as promising materials for biomedical applications due to their light weight, mechanical compatibility with bone, biodegradability, and excellent biocompatibility. However, their rapid degradation in physiological environments remains a critical challenge. To address this, a range of surface-modification techniques have been explored to tailor the surface properties while preserving the bulk characteristics of magnesium. This paper provides an overview of surface-engineering methods aimed at enhancing the corrosion resistance, mechanical performance and bioactivity of magnesium. Three key surface-modification approaches are presented: plasma treatment, laser texturing and sandblasting. Plasma treatment resulted in the formation of a stable, protective oxide layer with significantly improved corrosion resistance and hydrophilicity. Laser texturing generated hierarchical microstructures yielding superhydrophobic surfaces with an enhanced hardness, though slightly reduced corrosion resistance. Sandblasting led to an increased surface roughness and mechanical stiffness, but also introduced microstructural defects that are detrimental to the corrosion stability. Overall, the study demonstrates how tailored surface modifications can effectively balance the mechanical integrity and degradation behavior of magnesium, paving the way for its optimized use in biomedical applications.
Ključne besede: magnesium, surface modification, biomaterial
Objavljeno v DiRROS: 18.06.2025; Ogledov: 1180; Prenosov: 544
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Ključne besede: CrVN coating, laser modification, hot forming, self-lubrication, wear, friction
Objavljeno v DiRROS: 14.05.2025; Ogledov: 1351; Prenosov: 400
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Povzetek: Aluminum alloy 7075 is utilized widely across marine, aerospace, and automotive sectors. However, its surface wear resistance has hindered its application in certain tribological environments. Addressing this challenge, the current study examines a hybrid laser method to increase surface wear resistance by combining two techniques: ultrafast laser texturing and laser-based surface hardening. Ultrafast laser processing is conducted using 3 W laser power, 100 kHz pulse repetition rate, 4 mm s-1 scanning speed, and three different scan patterns. After the texturing operation, laser-based surface hardening is then performed on these textures using a continuous wave laser. The laser heat treatment is conducted using laser powers of 400 and 500 W with three different scan speeds of 1, 2, and 3 mm s-1 . Microhardness evaluations show a notable increase in hardness, with the hardest sample exhibiting a 17.8% increase compared to the pristine sample. The lasertextured and laser heat-treated samples exhibit a significant reduction in the average coefficient of friction and wear volumes compared to samples that were laser-textured but not laser heat-treated. The investigated laser processing strategy offers a promising approach for surface modification, enhancing both mechanical properties and wear resistance of aluminum alloy 7075 surfaces.
Ključne besede: hardness, laser hardening, parametric modeling, surface modification, ultrafast laser texturing, wear resistance
Objavljeno v DiRROS: 05.11.2024; Ogledov: 1585; Prenosov: 1467
Celotno besedilo (4,46 MB)
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