Structural refinement and photoluminescence properties of cube-like (Ca 1-xCu x)TiO 3 crystals synthesized by the microwave-hydrothermal method

In this work, (Ca 1-xCu x)TiO 3 crystals with (x = 0, 0.01 and 0.02), labeled as CTO, CCTO1 and CCTO2, were synthesized by the microwave-hydrothermal method at 140°C for 32 min. XRD patterns (Fig. 1), Rietveld refinement and FT-Raman spectroscopy indicated that these crystals present orthorhombic structure Pbnm. Micro-Raman and XANES spectra suggested that the substitution of Ca by Cu in A-site promoted a displacement of the [TiO6]-[TiO6] clusters adjacent from its symmetric center, which leads distortions on the [CaO 12] clusters neighboring and consequently cause the strains into the CaTiO3 lattice. FE-SEM images showed that these crystals have an irregular shape as cube like probably indicating an Ostwald-ripening and self-assemble as dominant mechanisms to crystals growth. The powders presented an intense PL blue-emission.

Osseointegration assessment of chairside argon-based nonthermal plasma-treated Ca-P coated dental implants

This study investigated the effect of an Argon-based nonthermal plasma (NTP) surface treatment-operated chairside at atmospheric pressure conditions applied immediately prior to dental implant placement in a canine model. Surfaces investigated comprised: Calcium-Phosphate (CaP) and CaP + NTP (CaP-Plasma). Surface energy was characterized by the Owens-Wendt-Rabel-Kaelble method and chemistry by X-ray photoelectron spectroscopy (XPS). Six adult beagles dogs received 2 plateau-root form implants (n = 1 each surface) in each radii, providing implants that remained 1 and 3 weeks in vivo. Histometric parameters assessed were bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed by Kruskall-Wallis (95% level of significance) and Dunn's post-hoc test. The XPS analysis showed peaks of Ca, C, O, and P for the CaP and CaP-Plasma surfaces. Both surfaces presented carbon primarily as hydro-carbon (CAC, CAH) with lower levels of oxidized carbon forms. The CaP surface presented atomic percent values of 38, 42, 11, and 7 for C, O, Ca, and P, respectively, and the CaPPlasma presented increases in O, Ca, and P atomic percent levels at 53, 12, and 13, respectively, in addition to a decrease in C content at 18 atomic percent. At 1 week no difference was found in histometric parameters between groups. At 3 weeks significantly higher BIC and BAFO were observed for CaPPlasma treated surfaces. Surface elemental chemistry was modified by the Ar-based NTP. Ar-based NTP improved bone formation around plateau-root form implants at 3 weeks compared with CaP treatment alone. © 2012 Wiley Periodicals, Inc.

Influence of the network modifier on the characteristics of MSnO 3 (M=Sr and Ca) thin films synthesized by chemical solution deposition

CaSnO3 and SrSnO3 alkaline earth stannate thin films were prepared by chemical solution deposition using the polymeric precursor method on various single crystal substrates (R- and C-sapphire and 100-SrTiO3) at different temperatures. The films were characterized by X-ray diffraction (θ-2θ, ω- and φ-scans), field emission scanning electron microscopy, atomic force microscopy, micro-Raman spectroscopy and photoluminescence. Epitaxial SrSnO3 and CaSnO 3 thin films were obtained on SrTiO3 with a high crystalline quality. The long-range symmetry promoted a short-range disorder which led to photoluminescence in the epitaxial films. In contrast, the films deposited on sapphire exhibited a random polycrystalline growth with no meaningful emission regardless of the substrate orientation. The network modifier (Ca or Sr) and the substrate (sapphire or SrTiO3) influenced the crystallization process and/or the microstructure. Higher is the tilts of the SnO6 octahedra, as in CaSnO3, higher is the crystallization temperature, which changed also the nucleation/grain growth process. © 2012 Elsevier Inc. All rights reserved.

Role of Ca, Fe, Cu and Zn in breast cancer: Study by X-ray fluorescence techniques and immunohistochemical analysis

In recent years, several studies have shown that concentrations of trace elements are altered in neoplastic breast tissues. However, the microenvironment and metabolic changes caused by tumors are complex and still not completely understood. Under this aspect, the combination of different techniques to investigate the role of trace elements in promoting and/or maintaining a tumor is interesting once the combination of information obtained by analytical techniques and immunohistochemical assays, associated with clinicopathological data, may allow a better metabolic understanding of trace elements in breast cancer. In this work, the role of the trace elements Ca, Fe, Cu and Zn in neoplastic breast tissues was investigated by X-ray fluorescence (XRF) techniques and immunohistochemical assays. We determined concentrations of Ca, Fe, Cu and Zn in normal and neoplastic breast tissues using energy dispersive XRF, and these values were used to set the positive or negative expression of elements in normal and neoplastic tissues. These expressions were correlated with the spatial distributions of trace elements (evaluated by micro-XRF) and with immunoexpression of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs and vascular endothelial growth factor. The results revealed that the expression of the trace elements Fe, Cu and vascular endothelial growth factor are related, indicating that higher levels of these elements can be associated with the angiogenic process in breast cancer. Also, associations between Ca, Zn and MMPs expression have been observed, possibly because of the fact that both metals are present in these proteins. © 2013 John Wiley & Sons, Ltd.

Dielectric and structural characterization of Pb1-xAxZr0.40Ti0.60O3 (A = Sr, Ca) ferroelectric ceramics

This paper reports the influence of Sr- and Ca-substitution on the structural and ferroelectric properties of Pb1-xSrxZr0.40Ti0.60O3 (PSZT) and Pb1-xCaxZr0.40Ti0.60O3 (PCZT) ceramic systems. The dielectric measurements show that these substitutions cause a diffuse behavior in the dielectric permittivity curves for all samples. According to the X-ray absorption near-edge structure (XANES) spectra collected at Ti K- and LIII-edge, when Pb was replaced by Sr or Ca, a decrease in the local distortion around Ti atoms in the TiO6 octahedron could be observed. The O K-edge XANES spectra also revealed that the hybridization between O 2p and Pb 6sp states decreased as the amount of Sr or Ca atoms increased. Based on these results, it was possible to ascertain that the ferroelectric behavior in PSZT and PCZT samples bears a close correlation to the hybridization weakening between O 2p and Pb 6 sp states. © 2013 by American Scientific Publishers.

Influência dos defeitos cristalinos nas propriedades dielétricas e não-ôhmicas do 'CA' 'CU IND.3' 'TI IND.4' 'O IND.12'(CCTO)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of the network modifier on the characteristics of MSnO3 (M=Sr and,Ca) thin films synthesized by chemical solution deposition

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of calcium on the structural properties of Ba(1-x)Ca (x) TiO3 particles synthesized by complex polymerization method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cross linked Poly (4-Vinylpyridine-Ethylene Glycol Dimethacrylate) Used for Preconcentration of Cd(II) and its Determination by Flow Injection Flame Atomic Absorption Spectrometry

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of a co-substituted A-site on structural characteristics and ferroelectricity of (Pb, Ba, Ca)TiO3 complex perovskites: analysis of local-, medium- and long-range order

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental evidence of enhanced ferroelectricity in Ca doped BiFeO3

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization and properties of elephant grass ashes as supplementary cementing material in pozzolan/Ca(OH)(2) pastes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Production and characterization of natural rubber-Ca/P blends for biomedical purposes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Longitudinal evaluation of fluoride levels in nails of 18-30-month-old children that were using toothpastes with 500 and 1100 mu g F/g

ObjectivesThis study aimed to evaluate the fluoride concentration in the fingernails and toenails of children aged 18-30months during use of fluoride-containing toothpastes supplemented with calcium glycerophosphate (CaGP) or sodium trimetaphosphate (TMP).MethodsAccording to the toothpaste used, children (n=56) were randomly assigned into three groups: 500gF/g with 1% TMP, 500gF/g with 0.25% CaGP, and 1100gF/g. Fingernails and toenails were collected monthly over a period of 330days, from the beginning of toothpaste use. Fluoride concentration in the water consumed by the volunteers and fluoride intake from diet and toothpaste were also determined. Fluoride analyses were performed with the electrode after hexamethyldisiloxane-facilitated diffusion or by the direct method, according to the samples. Data passed normality and homoscedasticity tests and were analyzed by 2-way analysis of variance (anova) and 1-way anova followed by Student-Newman-Keuls test (P<0.05).ResultsFluoride levels in the fingernails and toenails as well as fluoride intake from toothpaste were similar for the groups treated with 500gF/g with 1% TMP and 500gF/g with 0.25% CaGP toothpastes, but significantly lower than the 1100 gF/g group (P<0.05). No significant differences were noted among the groups regarding fluoride intake from diet and that by water consumed by the volunteers (P>0.05).ConclusionThe results of the longitudinal study suggest that the level of fluoride present in nails was lower with the use of toothpastes with a low fluoride concentration.

Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)