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There is a recent trend in tissue engineering and regenerative medicine to use nanotechnology and bionanomaterials to obtain materials that mimic the surface properties of a natural tissue. From this perspective, nanolevel tissue engineering can be viewed as a novel anatomy of the future. In this paper, a novel titanium-based alloy is studied following this strategy. The alloy nanostructuration is proposed as an improved alternative for restorative prosthodontics or an implantable biomaterial. Tests in (i) standard solution of simulated body fluid (SBF) and (ii) natural saliva were performed to investigate the alloy’s electrochemical stability. The results show that nanochannel growth on the alloy surface confers a higher stability than that of the untreated one in both natural and simulated environments. [ABSTRACT FROM AUTHOR]

Corrosion protective coatings were grown on pure magnesium in naturally carbonated mineral water containing Ca2+ using a simple, green conversion method. Dissolution of the native corrosion product, Mg(OH) 2 , mediates the surface nucleation of hydroxycarbonates. The pH increase due to CO 2 degassing to atmospheric pressure leads to calcium carbonate nucleation and lateral growth by the incorporation of nanoparticles in a continuous layer of calcite -Ca(Mg)CO 3 - microcrystals. The coated surfaces have a much improved corrosion resistance in physiological fluids, measured by EIS, weight loss, corrosion rates and hydrogen release. Cell viability/morphology assessment demonstrates that the coating is non-toxic and promotes the proliferation of osteoblastic cells. [Display omitted] • Carbonate protective coatings are obtained by chemical conversion coating on Mg. • The mechanism of carbonate coating formation is elucidated. • Carbonate coating inhibits corrosion of Mg in physiological fluids. • Corrosion rates of coated disks are two orders of magnitude lower than those of uncoated disks. • The carbonate coating is non-toxic and promotes cell proliferation of osteoblast cells. [ABSTRACT FROM AUTHOR]

Abstract: Several compositions in the vitreous SiO2–PbO–Na2O system, with 12.8–25mol% PbO and 21–34.6mol% Na2O were prepared by a conventional melt-quenched method. The structure of the obtained glasses was investigated by Infrared (IR), Raman and X-ray photoelectron spectroscopy (XPS) that have underlined the vitreous state of the samples and the differences in the structural units depending both on PbO and Na2O content. The structural units present in the glasses were evidenced by bands'' deconvolution in the IR and Raman spectra. The structural correlations in this ternary system are a real challenge, as the behavior of the compositions selected in the ternary system is totally different of that of the binary systems PbO–SiO2 and Na2O–SiO2. ICP-AES results on the aqueous solutions obtained from the studied glasses have shown different chemical stability in water related with extracted ions. The results could be correlated to the glasses structure, namely to the role played of PbO in the structure. [Copyright &y& Elsevier]

Abstract: The present study reports the evolution of reactive lanthanum cobaltite nanoparticles obtained by a polymeric precursor route, using citric acid as chelating agent. The crystallization from amorphous precursor, particle growth and the formation of nanoparticle agglomerates at different calcination temperatures was carried out by conventional and high-resolution electron microscopy, electron diffraction and energy-dispersive X-ray analysis and Raman spectroscopy. Microstructure measurements were compared with X-ray diffraction and chemical analysis results. Electron diffraction, combined with TEM, was used to determine the proportion of amorphous phase. The presence of amorphous carbon during the decomposition of the amorphous precursor was analyzed by Raman spectroscopy. The coherent crystalline domain size and the particle size have been monitored by XRD and electron microscopy in order to determine the evolution of both crystal size and the temperature onset for the formation of polycrystalline aggregates. The results demonstrate that at 550°C we obtain pure single-phase equiaxed nanopowders of LaCoO3 with crystal size of 20nm, free of amorphous carbon and without the presence of polycrystalline aggregates. [Copyright &y& Elsevier]

We report the characterization of LaMnO3.15, LaCoO3 and LaFeO3 powders synthesized using a simple Pechini-type, polymerizable complex method based on polyesterification between citric acid and ethylene glycol. The microstructure was evaluated by scanning electron microscopy. Raman spectra measured at 300 K, excited by a He–Ne laser were studied. Pure perovskite powders of LaMnO3.15 and LaCoO3 with rhombohedral symmetry and LaFeO3 with orthorhombic symmetry were formed at thermal treatments as low as 550°C. The mean particle size was in the nanoscale range. [Copyright &y& Elsevier]

Nanopowders of lithium niobate LiNbO3 and rare earth (RE) substituted LiNbO3–RExLi1−xNbO3, x=0.05 (RE: La, Pr, Sm, Er) were synthesized using a simple technique as the polymerizable complex method, based on the Pechini-type reaction route. A mixed solution of citric acid and ethylene glycol with Li, Nb and RE ions was polymerized. The formation mechanism, the homogeneity and the structure of the obtained powders have been investigated by thermogravimetry, X-ray diffraction, Raman spectroscopy and scanning electron microscopy measurements. The X-ray diffraction analysis indicated the formation of perovskite-type oxides, which crystallize in rhombohedral system when the Li–Nb and Li–Nb–RE polymeric precursors were treated at temperatures as low as 500 °C for 2 h. No additional crystalline phases formed during calcinations, but shifting of the XRD peaks with the RE ion substitution for Li suggested that structural modification inside the LN is the same. The Raman spectroscopy data of LiNbO3 substituted by RE were compared to the results of the unsubstituted system. The substitution dependence of frequency and damping in the A1(TO2), A1(TO3) and E(TO2) modes were employed to deduce the incorporation site of RE ions in LiNbO3. [Copyright &y& Elsevier]

Two types of unsupported zeolites (silicalite-1 and silicalite-2) and porous alumina discs supports were prepared by the hydrothermal sol–gel synthesis method. The influence of the raw materials used as SiO2 source, the temperature of the thermal treatment and the presence of the ceramic support on the crystallization of zeolites were studied. The reaction products were characterized by X-ray diffraction (XRD), IR spectroscopy (IR) and scanning electron microscopy (SEM) studies. The SiO2 source had a significant effect on the final zeolite obtained: the use of colloidal silica sol (ZCS) as SiO2 source in the synthesis led to ZSM-11 (silicalite-2) crystals, while the sodium silicate solution (ZSS) produced the ZSM-5 (silicalite-1) type. The presence of the alumina support influences the crystallization process of ZSM-5, as it improves nucleation and the ordering of the crystals. [Copyright &y& Elsevier]

We report a simple technique for the preparation of lanthanum ferrite LaFeO3+d nanopowders by the polymerizable complex (PC) method based on the Pechini-type reaction route. A mixed solution of citric acid (CA) and ethylene glycol (EG) with La and Fe ions was polymerized. The formation mechanism, the homogeneity, and the structure of the obtained powders have been investigated by thermogravimetry, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM) measurements. X-ray diffraction results indicated the formation of perovskite-type, which crystallizes in orthorhombic system LaFeO3+d when the La–Fe polymeric precursor was treated at 550 °C for 6 h. [Copyright &y& Elsevier]

LaMeO3 (Me: Mn, Fe and Co) perovskites, obtained by polymerizable complex method at 900 °C for 6 h with grain size of ∼80 nm, were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. The Raman active phonons in perovskites crystallized in rhombohedral symmetry—LaMnO3.15 and LaCoO3—and orthorhombic symmetry—LaFeO3—were reported. Raman spectra were excited using Ar+ laser (wavelength 514.5 nm) with various laser beam powers between 10 and 450 μW on a sample at room temperature. Raman bands were compared to those reported for other similar systems with the orthorhombic and rhombohedral Pbnm structure. The Raman spectra of LaMnO3.15 and LaCoO3 were strongly dependent on the laser beam power. Raman spectra obtained for the studied systems are related to many factors as the laser irradiation and the structure of LaMnO3.15, LaFeO3 and LaCoO3 which greatly depends on the method of preparation, particle size, oxygen content, symmetry, temperature or the oxygen partial pressure. [Copyright &y& Elsevier]

We report a simple technique for preparation of lanthanum cobaltite LaCoO3 powders by the polymerizable complex (PC) method based on the Pechini-type reaction route. A mixed solution of citric acid (CA) and ethylene glycol (EG) with La and Co ions was polymerized. The final materials obtained by the polyesterification between CA and EG were compared with those obtained by the nonpolymerizable route using only CA as complexant, without EG. The formation mechanism, homogeneity and the structure of the obtained powders have been investigated by thermogravimetry, X-ray diffraction and scanning electron microscopy (SEM) measurements. X-ray diffraction results indicated the formation of LaCoO3 (rhombohedral) when the La–Co polymeric precursor was treated at 600 °C for 6 h. A better mixing of La and Co cations was achieved in the PC-derived precursor than in the precursor derived from the nonpolymerizable, amorphous citrate route. [Copyright &y& Elsevier]

We studied glass formation in the SiO2-rich region of the ternary oxide system Al2O3–ZrO2–SiO2. Gels with the composition 5–5–90 mol% have been synthesized by the sol–gel method in acid media and then treated up to 1650 °C and kept for 2 and 10 h. A glass with the same composition has been obtained by quenching in water from the melt. The structural evolution of gels annealed at different temperatures up to 1650 °C was followed by thermal analysis, X-ray diffraction, specific surface area, density measurements and IR spectroscopy. The materials consisted mainly of amorphous phase up to 1200 °C, at which partial crystallization of cristobalite was observed. The presence of Zr and Al in the silica network at high temperatures was investigated by IR spectroscopy. The crystallization of gels at high temperatures and the crystalline phases formed are related to the preparation conditions and the thermal treatment. For samples from quenched melts zircon was the only crystalline phase detected, while in the case of the samples slowly cooled down from 1650 °C, zircon, silica, zirconia and alumina or mullite were observed depending on the treatment time. [Copyright &y& Elsevier]

Abstract: An 8-year-old girl presented with a history of pain in the right hypocondrium, multiple petechiae in the skin, and ecchimoses at sites of minor trauma. Laboratory investigations showed severe thrombocytopenia. Doppler ultrasonography and magnetic resonance imaging showed portal and splenic vein cavernomatous transformation and splenomegaly. The patient underwent laparoscopic subtotal splenectomy with lower pole preservation and esophagogastric devascularization. The postoperative course was uneventful. No gastrointestinal bleeding occurred within the first 34 months after surgery. Conclusions: Thrombocytopenia associated with splenomegaly is a rare form of presentation in portal cavernoma. Preserving the spleen immune function must be a goal in surgical management, especially in children. Laparoscopic subtotal splenectomy combined with esophagogastric devascularization is a difficult procedure, but it can be useful in patients with portal cavernoma and severe thrombocytopenia without gastrointestinal bleeding. [Copyright &y& Elsevier]

Here we report the synthesis, microstructure and superplastic creep behavior of alumina-based composites reinforced with 5–20 wt% ZrO2, prepared from high-purity alumina powders and zirconium alcoxide precursor mixtures. The composites reached 100% true strain at 1350 °C, deformed by stationary creep in the range of strain rates ~10−7 to 10−4 s−1. The microstructure remained stable during creep; no evidence of grain growth, grain boundary opening or cracking were observed in deformed samples. We conclude from the analysis of creep parameters that creep takes place mainly by interface-reaction-accommodated grain boundary sliding, and that the mobility of alumina grain boundaries controls the creep rate. The observed behavior is explained by the role of alumina–zirconia interphases, stronger and with a faster relaxation kinetics than alumina interfaces, to achieve an effective grain boundary pinning. Zirconia particles (~0.2–0.4 μm) are homogeneously placed at alumina grain boundaries (~1–2 μm). [ABSTRACT FROM AUTHOR]

Highlights: [•] The novel Ti–20Nb–10Zr–5Ta alloy shows exceptional electrochemical characteristics. [•] The composition of the complex oxide passive layer depends on the potential. [•] The oxidation of tantalum is inhibited under the experimental conditions used. [•] Alloying elements are enriched in the oxide layer relative to the bulk alloy. [•] The combination of properties makes this alloy suitable for biomedical applications. [ABSTRACT FROM AUTHOR]