Influence of titanium and lutetium on the persistent luminescence of ZrO2

Non-doped as well as titanium and lutetium doped zirconia (ZrO2) materials were synthesized via the sol-gel method and structurally characterized with X-ray powder diffraction. The addition of Ti in the zirconia lattice does not change the crystalline structure whilst the Lu doping introduces a small fraction of the tetragonal phase. The UV excitation results in a bright white-blue luminescence at ca. 500 nm for all the materials which emission could be assigned to the Ti3+ e(g) -> t(2g) transition. The persistent luminescence originates from the same Ti3+ center. The thermoluminescence data shows a well-defined though rather similar defect structures for all the zirconia materials. The kinetics of persistent luminescence was probed with the isothermal decay curve analyses which indicated significant retrapping. The short duration of persistent luminescence was attributed to the quasi-continuum distribution of the traps and to the possibility of shallow traps even below the room temperature. (C) 2012 Optical Society of America

Effect of whitening toothpaste on titanium and titanium alloy surfaces

Dental implants have increased the use of titanium and titanium alloys in prosthetic applications. Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium is prone to fluoride ion attack. Thus, the aim of the present study was to compare Ti-5Ta alloy to cp Ti after toothbrushing with whitening and conventional toothpastes. Ti-5Ta (%wt) alloy was melted in an arc melting furnace and compared with cp Ti. Disks and toothbrush heads were embedded in PVC rings to be mounted onto a toothbrushing test apparatus. A total of 260,000 cycles were carried out at 250 cycles/minute under a load of 5 N on samples immersed in toothpaste slurries. Surface roughness and Vickers microhardness were evaluated before and after toothbrushing. One sample of each material/toothpaste was analyzed by Scanning Electron Microscopy (SEM) and compared with a sample that had not been submitted to toothbrushing. Surface roughness increased significantly after toothbrushing, but no differences were noted after toothbrushing with different toothpastes. Toothbrushing did not significantly affect sample microhardness. The results suggest that toothpastes that contain and those that do not contain peroxides in their composition have different effects on cp Ti and Ti-5Ta surfaces. Although no significant difference was noted in the microhardness and roughness of the surfaces brushed with different toothpastes, both toothpastes increased roughness after toothbrushing.

Effects of type I collagen coating on titanium osseointegration: histomorphometric, cellular and molecular analyses

The investigation of titanium (Ti) surface modifications aiming to increase implant osseointegration is one of the most active research areas in dental implantology. This study was carried out to evaluate the benefits of coating Ti with type I collagen on the osseointegration of dental implants. Acid etched Ti implants (AETi), either untreated or coated with type I collagen (ColTi), were placed in dog mandibles for three and eight weeks for histomorphometric, cellular and molecular evaluations of bone tissue response. While the histological aspects were essentially the same with both implants being surrounded by lamellar bone trabeculae, histomorphometric analysis showed more abundant bone formation in ColTi, mainly at three weeks. Cellular evaluation showed that cells harvested from bone fragments in close contact with ColTi display lower proliferative capacity and higher alkaline phosphatase activity, phenotypic features associated with more differentiated osteoblasts. Confirming these findings, molecular analyses showed that ColTi implants up-regulates the expression of a panel of genes well known as osteoblast markers. Our results present a set of evidences that coating AETi with collagen fastens the osseointegration by stimulating bone formation at the cellular and molecular levels, making this combination of morphological and biochemical modification a promising approach to treat Ti surfaces.

In situ effect of sodium fluoride or titanium tetrafluoride varnish and solution on carious demineralization of enamel

This study evaluated the effect of titanium tetrafluoride (TiF4) formulations on enamel carious demineralization in situ. Thirteen subjects took part in this cross-over, split-mouth, double-blind study performed in three phases of 14 d each. In each subject, two sound and two predemineralized specimens of bovine enamel were worn intra-orally and plaque accumulation was allowed. One sound and one predemineralized specimen in each subject was treated once with sodium fluoride (NaF) varnish or solution (Treatment A); TiF4 varnish or solution (Treatment B); or placebo varnish or no treatment (Treatment C). The initially sound enamel specimens were exposed to severe cariogenic challenge (20% sucrose, eight times daily for 5 min each time), whereas the predemineralized specimens were not. Eleven subjects were able to finish all experimental phases. The enamel alterations were quantified by surface hardness and transversal microradiography. Demineralization of previously sound enamel was reduced by all test formulations except for the NaF solution, while both TiF4 formulations were as effective as NaF varnish. For the predemineralized specimens, enamel surface hardness was increased only by TiF4 formulations, while subsurface mineral remineralization could not be seen in any group. Within the experimental protocol, TiF4 was able to decrease enamel demineralization to a similar degree as NaF varnish under severe cariogenic challenges, while only TiF4 formulations remineralized the enamel surface.

Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy

This study aimed to evaluate the chemical interaction of collagen with some substances usually applied in dental treatments to increase the durability of adhesive restorations to dentin. Initially, the similarity between human dentin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR-FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.

Tool wear evaluations in friction stir processing of commercial titanium Ti–6Al–4V

This research addresses the application of friction stir welding (FWS) of titanium alloy Ti–6Al–4V. Friction stir welding is a recent process, developed in the 1990s for aluminum joining; this joining process is being increasingly applied in many industries from basic materials, such as steel alloys, to high performance alloys, such as titanium. It is a process in great development and has its economic advantages when compared to conventional welding. For high performance alloys such as titanium, a major problem to overcome is the construction of tools that can withstand the extreme process environment. In the literature, the possibilities approached are only few tungsten alloys. Early experiments with tools made of cemented carbide (WC) showed optimistic results consistent with the literature. It was initially thought that WC tools may be an option to the FSW process since it is possible to improve the wear resistance of the tool. The metallographic analysis of the welds did not show primary defects of voids (tunneling) or similar internal defects due to processing, only defects related to tool wear which can cause loss of weld quality. The severe tool wear caused loss of surface quality and inclusions of fragments inside the joining, which should be corrected or mitigated by means of coating techniques on tool, or the replacement of cemented carbide with tungsten alloys, as found in the literature.

Radiative association of Ti and O atoms

Rate coefficients for the radiative association of titanium and oxygen atoms to form the titanium monoxide (TiO) molecule are estimated. The radiative association of Ti(F-3) and O(P-3) atoms is dominated by an approach along the C-3 Delta potential energy curve, accompanied by spontaneous emission into the X-3 Delta ground state of TiO. For temperatures ranging from 300-14 000 K, the total rate coefficients are found to vary from 4.76 x 10(-17) to 9.96 x 10(-17) cm(3) s(-1), respectively.

Preparation and characterization of Zircaloy 4-Tantalum alloys for application in corrosive media

Two Zircaloy 4-Ta alloys (14 and 55 wt.% Ta) were produced by arc-melting. The alloys were hot-rolled at 900 degrees C and heat-treated under argon atmosphere for 100 h at 700 degrees C. The alloys were analyzed by scanning electron microscopy and X-ray diffractometry. The microstructure of both rolled and heat-treated alloys is constituted of (beta Zr,Ta)-II Ta-rich precipitates dispersed in a (alpha Zr) matrix. Corrosion tests performed in boiling concentrated H2SO4 solutions showed that the Zircaloy 4-Ta alloys are more corrosion resistant than Zircaloy 4 and that the corrosion resistance increases with increasing Ta content. (c) 2012 Elsevier Ltd. All rights reserved.

Development of Nanoinjector Devices for Electrospray Ionization - Tandem Mass Spectrometry (ESI-MSn)

In mass spectrometric (MS) systems with electrospray ionization (ESI), the sample can be analyzed coupled to separation systems (such as liquid chromatography or capillary electrophoresis) or simply by direct infusion. The greatest benefit of the type of injection is the possibility of continuous use of small amounts of samples over a long period of time. This extended analysis time allows a complete study of fragmentation by mass spectrometry, which is critical for structure elucidation of new compounds, or when using an ion trap mass analyzer. The injector filled with the sample is placed at the ESI source inlet creating an electric field suitable for the continuous formation of a spray (solvent and sample) and consequently, the gradual and even release of the sample. For the formation of the spray, is necessary that the injector end is metalized. The formation of a bilayer of titanium and gold provided an excellent attachment of the film, resulting in a nanoinjector for ionization/spray formation in the system for MS. The nanoinjectors showed high repeatability and stability over 100 min by continuous sampling with 10 mu L of sample.

Quantum Mechanics Insight into the Microwave Nucleation of SrTiO3 Nanospheres

An extensive investigation of strontium titanate, SrTiO3 (STO), nanospheres synthesized via a microwave-assisted hydrothermal (MAH) method has been conducted to gain a better insight into thermodynamic, kinetic, and reaction phenomena involved in STO nucleation and crystal growth processes. To this end, quantum chemical modeling based on the density functional theory and periodic super cell models were done. Several experimental techniques were employed to get a deep characterization of structural and optical features of STO nanospheres. A possible formation mechanism was proposed, based on dehydration of titanium and strontium clusters followed by mesoscale transformation and a self-assembly process along an oriented attachment mechanism resulting in spherical like shape. Raman and XANES analysis renders a noncentrosymmetric environment for the octahedral titanium, while infrared and first order Raman modes reveal OH groups which are unsystematically incorporated into uncoordinated superficial sites. These results seem to indicate that the key component is the presence of distorted TiO6 clusters to engender a luminescence property. Analysis of band structure, density Of states, and charge map shows that there is a close relationship among local broken symmetry, polarization, and energy split of the 3d orbitals of titanium. The interplay among these electronic and structural features provides necessary conditions to evaluate its luminescent properties under two energy excitation.

Titanium dioxide induced inflammation in the small intestine

AIM: To investigate the effects of titanium dioxide (TiO2) nanoparticles (NPTiO2) and microparticles (MPTiO2) on the inflammatory response in the small intestine of mice. METHODS: BI 57/6 male mice received distilled water suspensions containing TiO2 (100 mg/kg body weight) as NPTiO2 (66 nm), or MPTiO2 (260 nm) by gavage for 10 d, once a day; the control group received only distilled water. At the end of the treatment the duodenum, jejunum and ileum were extracted for assessment of cytokines, inflammatory cells and titanium content. The cytokines interleukin (IL)-1b, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, IL-17, IL-23, tumor necrosis factor-alpha (TNF-alpha), intracellular interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) were evaluated by enzyme-linked immunosorbent assay in segments of jejunum and ileum (mucosa and underlying muscular tissue). CD4(+) and CD8(+) T cells, natural killer cells, and dendritic cells were evaluated in duodenum, jejunum and ileum samples fixed in 10% formalin by immunohistochemistry. The titanium content was determined by inductively coupled plasma atomic emission spectrometry. RESULTS: We found increased levels of T CD4(+) cells (cells/mm(2)) in duodenum: NP 1240 +/- 139.4, MP 1070 +/- 154.7 vs 458 +/- 50.39 (P < 0.01); jejunum: NP 908.4 +/- 130.3, MP 813.8 +/- 103.8 vs 526.6 +/- 61.43 (P < 0.05); and ileum: NP 818.60 +/- 123.0, MP 640.1 +/- 32.75 vs 466.9 +/- 22.4 (P < 0.05). In comparison to the control group, the groups receiving TiO2 showed a statistically significant increase in the levels of the inflammatory cytokines IL-12, IL-4, IL-23, TNF-alpha, IFN-gamma and TGF-beta. The cytokine production was more pronounced in the ileum (mean SE): IL-12: NP 33.98 +/- 11.76, MP 74.11 +/- 25.65 vs 19.06 +/- 3.92 (P < 0.05); IL-4: NP 17.36 +/- 9.96, MP 22.94 +/- 7.47 vs 2.19 +/- 0.65 (P < 0.05); IL-23: NP 157.20 +/- 75.80, MP 134.50 +/- 38.31 vs 22.34 +/- 5.81 (P < 0.05); TNF alpha: NP 3.71 +/- 1.33, MP 5.44 +/- 1.67 vs 0.99 +/- 019 (P < 0.05); IFN gamma: NP 15.85 +/- 9.99, MP 34.08 +/- 11.44 vs 2.81 +/- 0.69 (P < 0.05); and TGF-alpha: NP 780.70 +/- 318.50, MP 1409.00 +/- 502.20 vs 205.50 +/- 63.93 (P < 0.05). CONCLUSION: Our findings indicate that TiO2 particles induce a Th1-mediated inflammatory response in the small bowel in mice. (C) 2012 Baishideng. All rights reserved.

Magnetic Properties of Liquid-Phase Sintered CoFe2O4 for Application in Magnetoelastic and Magnetoelectric Transducers

Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe2O4 was obtained using a conventional ceramic method and Bi2O3 was used as additive in order to obtain liquid-phase sintered samples. Bi2O3 was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 degrees C and 950 degrees C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives.

Bone tissue, cellular, and molecular responses to titanium implants treated by anodic spark deposition

A myriad of titanium (Ti) surface modifications has been proposed to hasten the osseointegration. In this context, the aim of this study was to perform histomorphometric, cellular, and molecular analyses of the bone tissue grown in close contact with Ti implants treated by anodic spark deposition (ASD-AK). Acid-etched (AE) Ti implants either untreated or submitted to ASD-AK were placed into dog mandibles and retrieved at 3 and 8 weeks. It was noticed that both implants, AE and ASD-AK, were osseointegrated at 3 and 8 weeks. Histomorphometric analysis showed differences between treatments only for bone-to-implant contact, being higher on AE implants. Although not backed by histomorphometric results, gene expression of key bone markers was higher for bone grown in close contact with ASD-AK and for cells harvested from these fragments and cultured until subconfluence. Cell proliferation at days 7 and 10 and alkaline phosphatase activity at day 10 was higher on AE surfaces. No statistical significant difference was noticed for extracellular matrix mineralization at 17 days. Our results have shown that the Ti fixtures treated by ASD-AK allowed in vivo osseointegration and induced higher expression of key markers of osteoblast phenotype, suggesting that this surface treatment could be considered to produce implants for clinical applications. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A:30923098, 2012.

Influence of the Sol-Gel pH Process and Compact Film on the Efficiency of TiO2-Based Dye-Sensitized Solar Cells

The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2 nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2 films. Nanoparticles prepared under acid pH exhibit smaller particle size and higher surface area, which result in higher dye loadings and better short-circuit current densities than DSCs based on alkaline TiO2-processed films. On the other hand, the product of charge collection and separation quantum yields in films with TiO2 obtained by alkaline hydrolysis is c. a. 27% higher than for the acid TiO2 films. The combination of acid and alkaline TiO2 nanoparticles as mesoporous layer in DSCs results in a synergic effect with overall efficiencies up to 6.3%, which is better than the results found for devices employing one of the nanoparticles separately. These distinct nanoparticles can be also combined by using the layer-by-layer technique (LbL) to prepare compact TiO2 films applied before the mesoporous layer. DSCs employing photoanodes with 30 TiO2 bilayers have shown efficiencies up to 12% higher than the nontreated photoanode ones. These results can be conveniently used to develop optimized synthetic procedures of TiO2 nanoparticles for several dye-sensitized solar cell applications.

Development of nanoinjector devices for electrospray ionization - tandem mass spectrometry (ESI-MSn)

In mass spectrometric (MS) systems with electrospray ionization (ESI), the sample can be analyzed coupled to separation systems (such as liquid chromatography or capillary electrophoresis) or simply by direct infusion. The greatest benefit of the type of injection is the possibility of continuous use of small amounts of samples over a long period of time. This extended analysis time allows a complete study of fragmentation by mass spectrometry, which is critical for structure elucidation of new compounds, or when using an ion trap mass analyzer. The injector filled with the sample is placed at the ESI source inlet creating an electric field suitable for the continuous formation of a spray (solvent and sample) and consequently, the gradual and even release of the sample. For the formation of the spray, is necessary that the injector end is metalized. The formation of a bilayer of titanium and gold provided an excellent attachment of the film, resulting in a nanoinjector for ionization/spray formation in the system for MS. The nanoinjectors showed high repeatability and stability over 100 min by continuous sampling with 10 µL of sample.