A Novel Bioactive Glass Containing Therapeutic Ions with Enhanced Biocompatibility

A novel bioactive glass containing therapeutic ions with enhanced biocompatibility was designed and produced by the classical melt-quenching route. Starting from a very promising composition (Bio_MS), which combined bioactivity and high crystallization temperature, the ratio between some oxides was tailored to obtain a new and more reactive (in terms of dissolution rate) bioactive glass, called BGMSN (composition in mol%: 6.1 Na2O, 31.3 CaO, 5 MgO, 10 SrO, 2.6 P2O5, 45 SiO2). The aim of this work was to produce a bioactive glass with a good biological performance, preserving, at the same time, the high crystallization temperature achieved for Bio_MS; this is strategic in order to avoid undesired crystalline phases during thermal treatments, which can undermine the bioactivity and even the stability of final products. A complete characterization of the novel bioactive glass was performed in terms of thermal, mechanical and biological properties and in vitro bioactivity. The thermal behavior of the bioactive glass was studied by heating microscopy, differential thermal analysis (DTA) and optical dilatometry; BGMSN showed a very high crystallization temperature and a high sinterability parameter, thus being suitable for applications where thermal treatments are required, such as sintered samples, coatings and scaffolds. Mechanical properties were investigated by the micro-indentation technique. The in vitro biological properties were evaluated by means of both direct and indirect cell tests, i.e., neutral red (NR) uptake and MTT assay, using murine long bone osteocyte Y4 (MLO-Y4) cells: the cellular viability of BGMSN was higher compared to cellular viability of 45S5, both in direct and indirect tests. Finally, the in vitro bioactivity test by soaking samples in simulated body fluid (SBF) showed high dissolution rate, with a good rate of formation of hydroxyapatite.

Effects of different sintering temperatures on thermal, physical, and morphological of SiO2-Na2O-CaO-P2O5 based glass-ceramic system from vitreous and ceramic wastes

This research involved comprehensive studies on thermal, physical, and morphological properties of SiO2-Na2O-CaO-P2O5 (SNCP) glass-ceramic at various sintering temperatures. The study in SNCP glass-ceramic using soda-lime-silica (SLS) wastes glass and clam shell (CS) wastes as the main raw of materials via conventional melt-quenching technique and solid state sintering are interesting and challenging by considering the research using waste materials to fabricate novel SNCP glass-ceramic. The main peaks, Na3PO4 and Ca3Na6Si6O18 were assigned to high crystallization temperature (Tc) at 650-950?C. The density of samples increases at 550-750?C and decreases at 850-950?C due to the increase of sample thickness and higher specific volume at high sintering temperature. FESEM micrograph showed that existed porous increased at sintering temperature 850-950?C contributes effect to low densification of the sample.

The Ferroelectricity and Crystallinity of Zirconia, Hafnia and Hafnium Zirconium Oxide (HZO) Ultrathin Films Prepared by Atomic Layer Deposition With and Without Post-Annealing

Large stable ferroelectricity in hafnium zirconium oxide (HZO) solid solution ultrathin films (including pure zirconia (ZrO2) and hafnia (HfO2)) and ZrO2/HfO2 bilayer ultrathin films of thickness ranging from 5–12 nm, prepared by thermal atomic layer deposition or remote plasma atomic layer deposition (RP-ALD) has been demonstrated. Ferroelectric crystallization of the ZrO2 ultrathin film with high-pressure orthorhombic (o) space group Pbc21 could be achieved without post-annealing due to the plasma-induced thermal stresses experienced by the film during the RP-ALD process. In contrast, for the ZrO2/HfO2 bilayer ultrathin film, due to the high crystallization temperature of HfO2, post-annealing was needed to achieve sufficient confinement of the sandwiched HfO2 layer by the ZrO2 top layer and Si bottom substrate to promote the high-pressure ferroelectric o-phase in HfO2. The ferroelectric properties of the HZO ultrathin films prepared by RP-ALD were highly dependent on the Hf-to-Zr ratio — an increasing amount of HfO2 has been found to be detrimental to the ferroelectricity, mainly due to the high crystallization temperature of HfO2. Without post-annealing, the ferroelectricity of the HZO ultrathin films was governed by the relative amounts of the amorphous phase and the ferroelectric o-phase induced by the plasma treatment. While with post-annealing, the ferroelectricity was governed by the relative amounts of the ferroelectric o-phase and the non-ferroelectric monoclinic (m) phase.

A Mechanically-Alloyed Amorphous 2Si-B-3C-N Ceramic with a Crystallization Temperature up to 1800°C

A mixture of cubic silicon powder, hexagonal boron nitride powder and graphite powder was mechanically alloyed for 30 hrs in argon. The as-milled 2Si-B-3C-N composite powder was heated up to 1900 °C in nitrogen, with a heating rate of 25 °C/min and under a pressure of 80 MPa. XRD and HRTEM results show that the as-milled 2Si-B-3C-N composite powder has a well amorphous structure. Under the current hot-pressing circumstances, the amorphous ceramic starts to crystallize at a temperature between 1800 °C and 1900 °C. Once the temperature is higher than crystallization temperature, crystallites appear in the amorphous matrix with a great nucleation rate, but a small growth rate. Hot pressed at 1900 °C for 0 mins or 10 mins, the prepared 2Si-B-3C-N bulk ceramic has an average grain size of 8.7 nanometers and 22.3 nanometers, respectively. After an intensive literature search, we believe the present work is the first one to make clear that it is possible to use the mechanical alloying route to prepare amorphous Si-B-C-N ceramic with such a high crystallization temperature.

Bioglass and bioceramic composites processed by Spark Plasma Sintering (SPS): biological evaluation Versus SBF test

The biocompatibility of hydroxyapatite (HA), a lab-made bioglass (BGCaMIX) with high crystallization temperature and different HA/BGCaMIX composites, produced by Spark Plasma Sintering (SPS), was tested with respect to murine osteocytes both by direct and indirect tests, in order to also investigate possible cytotoxic effects of the samples’ extracts. Previous investigations demonstrated that the samples’ bioactivity, evaluated in a simulated body fluid solution (SBF), increased with the increasing amount of BGCaMIX in the sample itself. Although none of the samples were cytotoxic, the findings of the biological evaluation did not confirm those arising from the SBF assay. In particular, the results of direct tests did not show an enhanced “biological performance” of materials with higher glass content. This finding may be due to the high release of ions and particulate from the glass phase. On the contrary, the performance of the BGCaMIX alone is better for the indirect tests, based on filtered samples’ extracts. This work further demonstrates that, when considering bioglasses and HA/bioglass composites, the results of the SBF assays should be interpreted with great care, making sure that the results arising from direct contact tests are integrated with those arising fromthe indirect ones.

Bioglass and bioceramic composites processed by Spark Plasma Sintering (SPS): biological evaluation Versus SBF test

The biocompatibility of hydroxyapatite (HA), a lab-made bioglass (BGCaMIX) with high crystallization temperature and different HA/BGCaMIX composites, produced by Spark Plasma Sintering (SPS), was tested with respect to murine osteocytes both by direct and indirect tests, in order to also investigate possible cytotoxic effects of the samples’ extracts. Previous investigations demonstrated that the samples’ bioactivity, evaluated in a simulated body fluid solution (SBF), increased with the increasing amount of BGCaMIX in the sample itself. Although none of the samples were cytotoxic, the findings of the biological evaluation did not confirm those arising from the SBF assay. In particular, the results of direct tests did not show an enhanced “biological performance” of materials with higher glass content. This finding may be due to the high release of ions and particulate from the glass phase. On the contrary, the performance of the BGCaMIX alone is better for the indirect tests, based on filtered samples’ extracts. This work further demonstrates that, when considering bioglasses and HA/bioglass composites, the results of the SBF assays should be interpreted with great care, making sure that the results arising from direct contact tests are integrated with those arising fromthe indirect ones.

Carbon-Doped Sb-Rich Ge-Sb-Te Phase Change Material for High Speed and High Thermal Stability Phase Change Memory Applications

Carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) is proved to be a promising candidate for phase change memory because of it high crystallization temperature (higher than 200°C) and 10-year data retention temperature (higher than 120°C). The carbon-doped Sb-rich Ge-Sb-Te (Sb-CGST) films were deposited on SiO2/Si (100) substrate by RF magnetron co-sputtering using CGST alloy target (a GST target containing 16 at. % C) and Sb targets at room temperature. The content of Sb in the films was controlled by adjusting the sputtering power ratio of CGST and Sb. The results showed that both of these two properties increase firstly and then decreases with increasing the content of Sb, which are superior to that of Ge2Sb2Te5. Furthermore, Sb-CGST based PCM cells were fabricated to investigate the property of material. 6ns pulse could realize SET operation, and 3.2 x 10-11J energy can realize RESET operation.