In respect to the cost of constituents, Cu-Al-Ni alloys can be regarded as low-cost shape memory alloys. However, the processing is quite costly due to the brittleness of the ingots. Therefore it would be advantageous to produce semi-finished products directly from the melt via highly productive technique. A laboratory device for vertical continuous casting directly from the vacuum induction melting furnace was experimentally employed for continuous casting of the Cu-13 wt.% Al-4 wt.% Ni shape memory alloy. A water-cooled copper crystalliser with a graphite insert was used to cast Ø 16 mm strands. Diverse sets of casting parameters were tested, the average casting speeds being within the range from 250 mm min-1 to 625 mm min-1. The castability of the alloy using this technique was good. Strands were examined in the as-cast condition, and no cracks or other defects were discovered. Medium casting speeds resulted in good surface quality, and a fully martensitic microstructure was obtained even at the lowest average casting speed. The paper presents and discusses the surface quality, microstructures and mechanical properties.
COBISS.SI-ID: 17450518
Gold nanoparticles (GNPs) are claimed as outstanding biomedical tools for cancer diagnostics and photo-thermal therapy, but without enough evidence on their potentially adverse immunological effects. Using a model of human dendritic cells (DCs), we showed that 10 nm- and 50 nm-sized GNPs (GNP10 and GNP50, respectively) were internalized predominantly via dynamin-dependent mechanisms, and they both impaired LPS-induced maturation and allostimulatory capacity of DCs, although the effect of GNP10 was more prominent. However, GNP10 inhibited LPS-induced production of IL-12p70 by DCs, and potentiated their Th2 polarization capacity, while GNP50 promoted Th17 polarization. Such effects of GNP10 correlated with a stronger inhibition of LPS-induced changes in Ca2+ oscillations, their higher number per DC, and more frequent extraendosomal localization, as judged by live-cell imaging, proton, and electron microscopy, respectively. Even when released from heat-killed necrotic HEp-2 cells, GNP10 inhibited the necrotic tumor cell-induced maturation and functions of DCs, potentiated their Th2/Th17 polarization capacity, and thus, impaired the DCs% capacity to induce T cell-mediated anti-tumor cytotoxicity in vitro. Therefore, GNP10 could potentially induce more adverse DC-mediated immunological effects, compared to GNP50.
COBISS.SI-ID: 27671847
In this research, the structure changes along the depth of gradient layers of titanium substrate, after etching with NaOH and subsequent thermal treatment at various temperatures between 300 and 800 °C, were investigated by XRD, FTIR and AES. Particularly, the changes of Ti substrate after etching with NaOH, subsequent ionic exchange of Na+ with Ca2+ ions and thermal treatment at 700 °C were analysed. Due to this approach, it was possible to get insight into the chemical changes and changes of Ti oxidation states and consequent phase analysis, along the depth of the titanium oxide coatings. In addition, Secondary Electron Imaging (SEI) showed very interesting nanotopology of all samples. Particularly interesting topology, consisting of very thin nano-designed walls between mutually interconnected pores, was observed for the sample in which Na+ were replaced with Ca2+ ions. This structure might be suitable for deposition of hydroxyapatite by biomimetic or plasma methods and as an appropriate scaffold for cell adhesion and proliferation.
COBISS.SI-ID: 17537814
This article reports the synthesis of Ag/TiO2 and Au/TiO2 nanoparticles by single-step ultrasonic spray pyrolysis (USP) conducted by an investigation of the process parameters and the morphological characteristics of the obtained nanostructures. The influence of the ratio in the precursor solution, physical characteristics of used components, and temperature had a large influence on the formation of different nanoparticle morphologies. The experimental investigations were performed using classic USP equipment, with variations of the process parameters. Scanning electron microscopy, transmission electron microscopy, and focused ion beam analyses were used to characterize the complex nanostructures. Based on the obtained results, the optimal process window for the formation of the different morphologies for the Ag/TiO2 and Au/TiO2 nanoparticles is determined and the possibility of synthesis of the core-shell structures in one step by USP is confirmed.
COBISS.SI-ID: 18716182
The observations of microstructure before and after explosive compaction revealed that explosive loading resulted in intensive fragmentation of grains that are enriched with sub-grain layered structure. The analysis of the results has shown that grain size refinement made the main contribution to the strengthening of explosive treated copper.
COBISS.SI-ID: 18561558