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Although the degradation of polylactide has been relatively well understood, there is still a lack of reliable data on the behavior of its composites at specific temperatures. This paper studies the hydrolytic degradability of polylactide/not activated smectite clay nanocomposites in the 6 weeks accelerated degradation at 80 °C which has not been widely documented so far. The composites with 3 wt%, 5 wt% and 10 wt% of smectite filler content obtained by injection molding were investigated and compared to the neat polylactide matrix material. The results of degradation at 80 °C were referred to the hydrolytic degradation at 25 °C and 37 °C. Macroscopic changes in the nanocomposites, their molecular weight and pH of medium was monitored during the degradation time. The influence of clay addition on the crystallization, glass transition and the melting temperature was also studied by differential scanning calorimetry (DSC). The DSC results show that the presence of smectite clay results in a shift of the onset peak for the melting temperatures towards higher values while for the glass transition towards the lower ones. A significant difference in degradation rate between the polylactide matrix and the polylactide/clay nanocomposites was also noted. The shortened degradation time of the nanocomposites increases their potential for use in biomedical applications, but also in disposable thermoplastic products which are increasingly used. [ABSTRACT FROM AUTHOR]

Polymer-based nanocomposites containing biocompatible and bioactive nanocomponents seem to be excellent materials that could be used in many biomedical applications. The aim of this study was biological evaluation of resorbable polymer-based nanocomposites (PLA, PCL) and their modifications with ceramic nanoparticles (silica - SiO2, montmorylonit - MMT) or carbon nanotubes. The nanocomposites were seeded with the human osteoblast-like MG 63 cells. After 1, 3 and 7 days of incubation, Trypan blue exclusion test was used to determine the viability and number of cells. The cell population density depending on incubation time and cell population doubling time was calculated. The cell proliferation abilities on the all applied nanocomposites and on control material (polystyrene cell culture plate) were also compared. The number of cells growing on the nanocomposite surfaces increased with the incubation time. The cell viability was not decreased for all applied materials during the entire study (97-100%). The ceramic nanoparticles and carbon nanotubes modified the bone cell growth and proliferation rate. Results of this study confirm that all types of the nanocomposites are appropriate to the growing and proliferation of human osteoblast-like cells. [ABSTRACT FROM AUTHOR]

Powders and thin films of nanocrystalline yttrium disilicate (Y2Si2O7) doped with Ce3+ have been prepared by a sol–gel method. Structure and morphology of the synthesised samples have been determined and spectroscopic properties compared. The triclinic α-Y2Si2O7 form (space group P 1-) for the powders annealed between 1000°C and 1200°C has been found. A total conversion into a thortveitite-type monoclinic β-Y2Si2O7 polymorph after annealing of powder samples at 1400°C (space group C2/m) has been observed. In the case of films even at 1300°C the basically pure triclinic α-Y2Si2O7 phase was observed with luminescent spectroscopy. The influence of grain size, controlled by thermal treatment, on the structure and luminescence properties of the fabricated materials are presented and discussed. [ABSTRACT FROM AUTHOR]

Nanoparticulate powders of Eu-doped Lu2O3 were prepared using combustion process and glycine as a fuel. Such powders could be relatively easily sintered to translucent bodies at 1700 °C. Excitation and emission spectra were recorded for both types of the materials. The excitation spectra revealed the existence of much more efficient energy transfer from the host to the dopant in the sintered ceramics. Strong variations in the relative intensities of the excitation transitions are seen when comparing the powder and its sintered analog. This was explained assuming preferential occupation of the C3i site in the glycine-derived powder in comparison with the pellets. Most profound emission under X-ray excitation was found for the sintered ceramic doped with 5% of Eu. [Copyright &y& Elsevier]

Abstract: Bulk alkaline earth fluorides co-doped with optically active ions are prominent materials for luminescent applications. However, for phosphor materials the changeover to the nanoscale is a tightrope walk between achieving desirable features of small particles such as reduced light scattering and unwanted drawbacks such as a high surface defect concentration which is likely to result in quenching of luminescence. A new preparation route via ionic liquids allows obtaining pure and oxygen-free alkaline earth fluorides co-doped with Eu3+ and Gd3+ on the nanoscale with excellent quantum cutting abilities. [Copyright &y& Elsevier]