Search the digital library catalog

Abstract: This review provides a comprehensive Life Cycle Assessment (LCA) of a cosmetic cream to assess the environmental impacts throughout its entire life cycle, from raw material extraction to disposal, using the methodology according to international standards. The LCA was performed using the OpenLCA 2.0.1 software, with data from the Ecoinvent 3.8 database and relevant literature. The assessment focused on multiple impact categories, including climate change, acidification, eutrophication (freshwater, marine and terrestrial), ecotoxicity (freshwater), human toxicity (cancer and non-cancer), ionizing radiation, land use, ozone depletion, photochemical ozone formation, resource use (fossils, minerals and metals), and water use. The LCA of a cosmetic cream containing gold nanoparticles revealed significant environmental impacts across critical categories. The total climate change potential was 2596.95 kg CO2 eq., driven primarily by nanoparticle synthesis (60.7%) and electricity use (31.9%). Eutrophication of freshwater had the highest normalized result (3.000), with nanoparticle synthesis contributing heavily, indicating the need for improved wastewater treatment. The resource use (minerals and metals) scored 1.856, while the freshwater ecotoxicity reached 80,317.23 CTUe, both driven by the nanoparticle production. The human toxicity potentials were 1.39 × 10−6 CTUh (cancer) and 7.45 × 10−5 CTUh (non-cancer), linked to emissions from synthesis and energy use. The LCA of the cosmetic cream revealed several critical areas of environmental impact. The most significant impacts are associated with gold nanoparticle synthesis and electricity use. Addressing these impacts through optimized synthesis processes, improved energy efficiency, and alternative materials can enhance the product’s sustainability profile significantly.
Keywords: life cycle assessment, cosmetic cream, environmental impacts, gold nanoparticles
Published in DKUM: 17.12.2024; Views: 0; Downloads: 9
Full text (1,71 MB)
This document has many files! More...

Abstract: The coupled processes of coprecipitation and ultrasonic spray pyrolysis (USP) were used to synthesize Fe3O4-Au hybrid nanostructures. The first coprecipitation method enabled the synthesis of Fe3O4 nanoparticles by mixing iron salts’ ions (Fe2+ and Fe3+) and ammonia as the base, and USP was used as the coating process of the Fe3O4 nanoparticles with Au. The formatted hybrid nanostructures consist of Fe3O4 nanoparticles that have Au on their surface in the form of gold nanoparticles (AuNPs). AuNPs have a crystalline structure and range in size from 10 to 200 nm. Additional characterization techniques, including ICP-OES, TEM, SEM, EDS, DLS, zeta potential, and room temperature magnetic hysteresis loops, were used to determine the chemical, physical, and magnetic properties of the Fe3O4 nanoparticles and hybrid nanostructures. It was found that USP produces separate AuNPs too (not just on the Fe3O4 surface), suggesting a bimodal formation of AuNPs. The zeta potential of the Fe3O4 nanoparticles showed poor stability (−15 mV), indicating a high tendency to aggregate, and the zeta potential of the hybrid nanostructures was also very low (≅0), which, comparatively means even worse stability. The saturation magnetization of the Fe3O4 nanoparticles was 35 emu/g, which is relatively lower than that of bulk Fe3O4, while the saturation magnetization of the hybrid nanostructures was significantly lower (0.1 emu/g) compared to the Fe3O4 nanoparticles.
Keywords: magnetic NPs, gold NPs, transmission electron microscopy, magnetic properties
Published in DKUM: 29.11.2024; Views: 0; Downloads: 10
Full text (7,32 MB)
This document has many files! More...

Abstract: 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
Keywords: noble metal dental alloys, metal–ceramic alloys, materials testing, biocompatibility testing
Published in DKUM: 25.11.2024; Views: 0; Downloads: 3
Full text (11,75 MB)
This document has many files! More...

Abstract: This study demonstrates the successful synthesis of Ni/Y2O3 nanocomposite particles through the application of ultrasound-assisted precipitation using the ultrasonic spray pyrolysis technique. They were collected in a water suspension with polyvinylpyrrolidone (PVP) as the stabiliser. The presence of the Y2O3 core and Ni shell was confirmed with transmission electron microscopy (TEM) and with electron diffraction. The TEM observations revealed the formation of round particles with an average diameter of 466 nm, while the lattice parameter on the Ni particle’s surface was measured to be 0.343 nm. The Ni/Y2O3 nanocomposite particle suspensions were lyophilized, to obtain a dried material that was suitable for embedding into a polylactic acid (PLA) matrix. The resulting PLA/Ni/Y2O3 composite material was extruded, and the injection was moulded successfully. Flexural testing of PLA/Ni/Y2O3 showed a slight average decrease (8.55%) in flexural strength and a small decrease from 3.7 to 3.3% strain at the break, when compared to the base PLA. These findings demonstrate the potential for utilising Ni/Y2O3 nanocomposite particles in injection moulding applications and warrant further exploration of their properties and new applications in various fields.
Keywords: ultrasound spray pyrolysis, Ni/Y2O3, lyophilization, PLA, extrusion, injection moulding
Published in DKUM: 05.04.2024; Views: 199; Downloads: 20
Full text (3,29 MB)
This document has many files! More...

Keywords: gold nanoparticles, fullerene C60, lens, coatings, characterisation
Published in DKUM: 28.03.2024; Views: 183; Downloads: 21
Full text (25,25 MB)
This document has many files! More...