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The goal of this research is to examine the influence that incorporation of synthesized hydroxyapatite (HA) and fluorapatite (FA) nanoparticles has on the synthesis and mechanical characteristics of glass-ionomer cements (GICs). In this research, HA and FA nanoparticles were synthesized through wet-chemical precipitation method. The obtained inorganic nanoparticles were evaluated with XRD, SEM, TEM, and STA analyses. The glass powder of the GIC (G1 and G2) were synthesized with two different formulations, and in addition, the polymer of GIC, acrylic-itaconic copolymer, was prepared in this research. The synthesized GIC components were appraised employing XRD and STA (for glass component) and FTIR and H-NMR (for polymer component). HA and FA nanoparticles were then added into the powder component (G1 and G2) at 5% and 8 wt%, and unblended powder was utilized as a control. Compressive strength (CS) and diametral tensile strength (DTS) before and after 1, 7, and 28 days of storage in distilled water were investigated utilizing a universal testing machine. Surface microhardness after 1 and 7 days of storage in distilled water was measured utilizing Vickers microhardness tester. Also, setting and working time was determined as specified in the ASTM standard. The obtained results showed that the calcined HA and FA nanoparticles have an ellipsoid-like morphology, and their mean crystallite sizes were measured as 24 and 30 nm, respectively. The mechanical results of the modified GICs, following the addition of HA and FA (5 and 8 wt%) into the glass ionomer cement and 28 days storage in distilled water, exhibited statistically higher CS (64–70 and 66–72 MPa, respectively). Also, higher DTS was observed, at about 7.5–10.5 and 8.5–12 MPa, respectively. The microhardness of the GICs containing HA and FA nanoparticles (5 wt%) increased by 6.5 and 14%, respectively. In addition, the working time and setting time by adding the 5 wt% nanoparticles reduced about 12 and 19% for HA and 13.5 and 18% for FA, respectively. Finally, it can be concluded that the synthesized GICs containing HA and FA nanoparticles provide enhanced mechanical properties to restorative dental materials. [ABSTRACT FROM AUTHOR]

In this study we employed the sol-gel method to synthesize new CaO-P2O5-SiO2-ZnO-B2O3 bioactive glasses. Three samples with various B2O3 content (5, 10 and 15 mol %) was prepared and their bioactivity were evaluated by immersion in simulated body fluid (SBF) and the glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The experimental results revealed that with increasing the amount of boron content, a more crystalline domain can be observed in their XRD patterns and consequently the formation of hydroxyapatite (HA) increased. FTIR spectra showed that the sample containing 10 mol% of boron had the sharpest peaks attributed to the formation of hydroxyapatite. Biocompatibility of the samples was examined by MTT assay and alkaline phosphatase activity. The result ascertained that the synthesized bioactive glass had good biocompatibility and can serve as a bone substitute in bone defects. [ABSTRACT FROM AUTHOR]

In this study, bioactive glass of the type SiO-CaO-SrO-PO was obtained by the sol-gel processing method and the effects of SrO/CaO substitution on the in vitro biological properties of the synthesized glasses were evaluated. The obtained bioactive glasses were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), differentioal scanning caloremetry (DSC) and Brunauer, Emmett and Teller (BET) analyses. The effects of various glass compositions on proliferation and differentiation of osteoblastic cells were also evaluated. The results showed that incorporation of Sr in the obtained glass network did not result in any structural alteration due to the similar role of SrO compared with that of CaO. In vitro experiments with human osteosarcoma cell lines (MG-63) indicated that bioactive glass incorporating 5 mol % in the composition revealed optimal cell proliferation and alkaline phosphatase (ALP) activity. Our results ascertained this material to be non-toxic and compatible for the proposed work in segmental defects in the rabbit model in vivo. [ABSTRACT FROM AUTHOR]

Ce-doped FeVO nanocomposites were successfully synthesized using reverse micro-emulsion route. Thermal and microstructural characteristics were comprehensively investigated by simultaneous thermal analysis, X-ray diffraction (XRD), scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and laser particle size analyzer. Moreover, as the anode material of lithium-ion batteries, the electrochemical properties were studied by galvanostatic charge and discharge tests and electrochemical impedance spectroscopy. The thermal analysis illustrated that the triclinic crystal structure of FeVO nanoparticles is formed at about 520 °C, which is confirmed by XRD and FT-IR results. Furthermore, the microstructural analyses revealed more regular particles and high specific surface area for wet-chemical derived FeVO:Ce, which decreases the diffusion pathway of the lithium ions during the insertion/extraction process. The electrochemical measurements indicated that the electrode cycling performance and rate retention ability of Ce-doped FeVO are better than those of pure FeVO due to the expansion of the crystal lattice, which provided more lattice space for lithium intercalation and de-intercalation. Consequently, the as-prepared Ce-doped FeVO with relatively high specific and reversible capacity, thermal stability and satisfactory cycling performance is a promising candidate for use as a lithium batteries anode material. [ABSTRACT FROM AUTHOR]

The sol-gel preparative method was employed to synthesize SrZnSiO:Eu nanostructure phosphors for white-light emitting diodes. The effects of calcination temperature and atmosphere as two important process parameters on the structural, morphological and optical properties were investigated using comprehensive characterization methods such as X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM) and photoluminescence spectra. The obtained phosphors are efficiently excited from 340 to 400 nm, which matches the near UV emitting InGaN chip and emits strong band peaking at 481 nm due to 4f 5d( D) → 4f( S) transition of Eu ions. In this europium-doped host lattice, a partial reduction of Eu to Eu at high temperature during the synthesis in air according to the charge compensation model is perceived. Furthermore, for this sample forbidden f-f transitions of Eu are observed. Finally, using Scherrer's equation the crystallite size of the optimum products with color coordination of x = 0.176, y = 0.193 is estimated at ~30 nm, which was consistent with TEM observations. [ABSTRACT FROM AUTHOR]

In this research, a new blue-emitting phosphor Eu-doped SrZnSiO was developed for white light-emitting diodes via the sol-gel process. Thermogravimetric-differential thermal analysis, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), and photoluminescence (PL) spectra were used to characterize the resulting phosphors. The obtained phosphor is efficiently excited in the wavelength range of 340-400 nm which matches to a near-UV-emitting InGaN chip and emits strong band blue light peaking at 481 nm because of 4 f5 d( D) → 4 f( S) transition of Eu ions. The effects of the activator concentration and excess Si (y > 1) on the luminescence properties were evaluated. It was found that, when the Eu content ( x) and the Si concentration (2 y) were 0.04 and 2.4, respectively, the optimum phosphor can be achieved. Also, the mechanism of concentration quenching was determined to be the dipole-dipole interaction using Dexter's theory. Finally, the mean crystallite size of the products was estimated to be approximately 30 nm using Scherrer's equation, which was confirmed by the TEM observations. [ABSTRACT FROM AUTHOR]

In this research, we demonstrate rapid mechanochemical synthesis of nanocrystalline α-alumina (α-Al2O3) from a starting mixture of hematite (Fe2O3) and aluminum (Al). The formation of α-Al2O3 nanocrystallites occurs during the solid-state reaction and through the reduction treatment. Also in this paper, effects of milling time on the particle size and lattice strain of nanocrystalline α-Al2O3 are investigated. The results indicate that complete reduction is reached only after 2 h of milling in a planetary mill and the crystallite size of obtained α-Al2O3 is in general about 12 nm. Also, it is found that increasing the milling time can effectively decrease the nanocrystalline size and increase the lattice strain of α-Al2O3. Finally, the experimental results show appropriate homogeneity and dispersion of related nanocrystallites. [ABSTRACT FROM AUTHOR]

Titanium alloy (Ti6Al4V) substrates, having the ability of biomimetic calcium phosphate-based materials, especially hydroxyapatite deposition in a simulated body fluid (SBF) means of chemical treatment (alkaline treatment) and subsequent heat treatment, was studied. The effects of alkaline treatment time, concentration and heat treatment temperature on the formation of calcium phosphate (carbonate-hydroxyapatite) on Ti6Al4V surface were examined. For this purpose, the metallic substrates were treated in 0, 5 and 10 M NaOH solutions at a temperature of 60 or 80°C for 1 and 3 days. Subsequently the substrate was heat-treated at 500, 600 and 700°C for 1 h for consolidation of the sodium titanate hydrogel layer. Finally, they were soaked in SBF for 1 and 3 days. The substrate surfaces were characterized by the techniques commonly used for bulk material such as scanning electron microscopy (SEM) and thin film X-ray diffraction (TF-XRD). With regard to the SEM and TF-XRD results, the optimum process consists of 3 days soaking in 5 M NaOH in 80°C and subsequent heat treatment at 600°C for 1h. It is worth mentioning that the results showed that the apatite formed within 3 days on the specimen surfaces, however, there was no sign of apatite formation in the control samples (without alkaline and heat treatment) which was treated for up to 3 days immersion in SBF. [ABSTRACT FROM AUTHOR]