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Titanium
Kinds of Titanium Terms modified by Titanium Selected AbstractsPreparation and Characterization of Codeposited Palladium-Nickel/Titanium Electrodes and Palladium-Nickel/Polymeric Pyrrole Film/Titanium ElectrodesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 10 2008X. Hu Abstract Palladium-nickel/titanium (Pd-Ni/Ti) and palladium-nickel/polymeric pyrrole film/titanium (Pd-Ni/PPy/Ti) electrodes were prepared by electrochemical deposition. The electrochemical characteristics of the Pd-Ni/Ti and Pd-Ni/PPy/Ti electrodes were studied by means of cyclic voltammetry (CV) based on orthogonal experiments. CV studies on the electrodes were conducted in 0.5,mol/L sulfuric acid solution. Experimental results indicate that the hydrogen adsorption peak value of the Pd-Ni/PPy/Ti electrode seen at ca. ,500,mV is larger than that of Pd-Ni/Ti electrode. Scanning electron microscope (SEM) images indicate that polymeric pyrrole film, which formed on electrode can modify the electrode surface configuration significantly and provide the surface of the Pd-Ni/PPy/Ti electrode with more layers and a larger surface area. [source] Positive magnetoresistance in TixW1-xSe2 (x = 0, 0.03) platelet crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006Sunil Kunjachan Abstract Layered transition metal dichalcogenide crystal, WSe2, has been grown by direct vapour transport technique. Titanium is used as a dopant in to the 2H type MX2 matrix. These crystals show positive magnetoresistance and a switching behaviour is observed at room temperature in the titanium-intercalated sample. The relative resistance change due to magnetic field for the doped sample is found to switch from 23.6% to 39.6% when the sample is rotated through 0° to 90°. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mono(aryloxido)Titanium(IV) Complexes and Their Application in the Selective Dimerization of EthyleneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2009Jean-Benoit Cazaux Abstract We report on the synthesis of mono(aryloxido)titanium(IV) complexes of general formula {Ti[O(o -R)Ar]X3}, with X = OiPr, ArO = 2- tert -butyl-4-methylphenoxy and R = CMe3 (2a), CMe2Ph (2b) and CH2NMe2 (2c). Attempts to reach pure mono(aryloxido) complexes when R = CH2NMe(CH2Ph) (2d) or CH2N(CH2Ph)2 (2e) were unsuccessful. When R = CH2OMe, the analogous mononuclear complex was not obtained, and instead, a dinuclear complex [(2- tert -butyl-4-methyl-6-methoxymethylphenoxy) TiCl(OiPr)(,2 -OiPr)2TiCl(OiPr)2] (3) was formed. Complexes 2b and 3 were characterized by single-crystal X-ray diffraction. The former contains a tetrahedrally coordinated TiIV centre, whereas in the latter the aryloxido ligand behaves as a chelating,bridging ligand between the two, chemically very different metal centres that form two face-sharing octahedra. Different synthetic approaches starting from [Ti(OiPr)4] or [TiCl(OiPr)3] were evaluated and are discussed. The hemilabile behaviour of the aryloxido ligand resulting from reversible coordination of its side arm was studied by variable-temperature 1H NMR spectroscopy for 2c (R = CH2NMe2). Complexes 2a,d were contacted with ethylene and AlEt3 as cocatalyst. When activated with AlEt3 (3 equiv.) at 20 bar and 60 °C, complex 2c exhibits interesting activity (2100 g/gTi/h) for the selective dimerization of ethylene to 1-butene (92,% C4=; 99+% C4=1). Noticeable differences in catalyst activity were observed when the R group was modified. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Dinuclear Titanium(IV) Complexes Bearing Phenoxide-Tethered N-Heterocyclic Carbene Ligands with cisoid Conformation through Control of HydrolysisEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2007Dao Zhang Abstract In situ generated N-heterocyclic carbene salt derivative Na2(L) of 1,3-bis(4,6-di- tert -butyl-2-hydroxybenzyl)imidazolium bromide, [H3(L)]Br, reacted with 1 equiv. of TiBr4 at ,78 °C to give a titanium complex of the composition [(L)TiBr2(thf)] (1), while the reaction in a 2:1 ratio under the same conditions afforded bisligand titanium complex [(L)2Ti] (2). Two oxygen-bridged titanium dimers, {[(L)TiBr]2(,-O)} (4) and {[(L)Ti(,-O)]2} (5), were obtained by control of hydrolysis of 1 and [(L)Ti(CH2Ph)2] (3) in tetrahydrofuran and diethyl ether. The molecular structures of 2, 4, and 5 have been confirmed by X-ray single-crystal analysis. The phenoxide-functionalized NHC ligand adopts transoid conformation in mononuclear complex 2 but rare cisoid conformation in dinuclear complexes 4 and 5. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis and Characterization of Novel Titanium, Germanium, and Tin Silazane Complexes Bearing a Cyclohexasilazanetriido LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2007Christian Lehnert Abstract Novel heterometallic silazane complexes were synthesized by the reaction of 1-lithio-2,2,4,4,6,6-hexamethylcyclotrisilazane Li(HMCTS)H2 with the tetrachloride salts of titanium and germanium as well as by the reaction of 1,1,3,3,5,5-hexamethylcyclotrisilazane H3(HMCTS) with tin tetrachloride and excess triethylamine. The products [H3(DMCHS)TiCl] (1), [H3(DMCHS)GeCl] (2), and [H3(DMCHS)SnCl] (3) {H3(DMCHS) = 2,2,4,4,6,6,8,8,10,10,12,12-dodecamethylcyclohexasilazane-1,5,9-triido} were characterized by 1H-, 13C-, 14N-, and 29Si NMR spectroscopy, elemental analyses and single-crystal X-ray structure analyses. The complexes have a surprising and interesting structure, that of a new dodecamethylcyclohexasilazane system with the Ti, Ge, or Sn atom in the center. These metal atoms are coordinated by one chlorine atom and three nitrogen atoms. The metal centers are part of three six-membered hetero-silazane rings. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The Transient Titanocene(II): Direct Synthesis from Solvated Titanium(II) Chloride and Cyclopentadienylsodium and Ensuing Interception with Diphenylacetylene as 1,1-Bis(cyclopentadienyl)-2,3,4,5-tetraphenyltitanacyclopentadiene,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2007John J. Eisch Abstract For the first time the unstable titanocene(II) has been directly synthesized by the Wilkinson metallocene approach, namely the interaction of a THF-soluble form of titanium(II) chloride with two equivalents of cyclopentadienylsodium in THF solution at 0°,25 °C. Because of the transient existence of the titanocene(II) thereby obtained, it could only be chemically trapped in high yield as 1,1-bis(cyclopentadienyl)-2,3,4,5-tetraphenyltitanacyclopentadiene by two equivalents of diphenylacetylene, if the acetylene was added at 25 °C, without removal of the by-product LiCl and NaCl. If the addition of the acetylene was delayed, in order to filter off the LiCl and NaCl from the reaction mixture, then no trace of the titanacyclopentadiene derivative was found upon hydrolytic workup. Instead, a significant portion of the acetylene was found to have undergone hydrotitanation. This finding is clear evidence that the titanocene(II) had undergone a precedented rearrangement to a known dimer having the structure of a titanocene(III) hydride with a fulvalene bridge between the titanium centers. We suggest that the LiCl and NaCl present in the unfiltered reaction mixture form a dichloro complex with titanocene(II) and thereby retard its dimerizing rearrangement to the titanocene(III) hydride. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Effect of Decrease of Hydride-Induced Embrittlement in Nanocrystalline Titanium,ADVANCED ENGINEERING MATERIALS, Issue 8 2010M.A. Murzinova Abstract The room-temperature impact toughness, strength and ductility of nanocrystalline (NC) and microcrystalline (MC) titanium with hydrogen content ranging from 0.1 to 16,at.-% (0.002 to 0.450,wt.-%) are studied. NC titanium has higher strength and lower sensitivity to hydride-induced brittle fracture than the MC material. In contrast to MC titanium, the elongation and impact toughness in the NC material does not decrease dramatically with increasing hydrogen content. Moreover, the fracture toughness in hydrogenated NC condition is found to be higher than that in MC titanium. This unusual result may be associated with the precipitation of equiaxial nanoscale hydrides in the interior of ,-grains in the NC material, while platelet hydrides are formed in MC titanium. One can expect that the risk of hydride-induced embrittlement is lower in NC than in MC titanium, making the NC material attractive for potential application under conditions that may cause hydrogen saturation above the permissible level for MC titanium. [source] Size Independent Shape Memory Behavior of Nickel,Titanium,ADVANCED ENGINEERING MATERIALS, Issue 8 2010Blythe G. Clark While shape memory alloys such as NiTi have strong potential as active materials in many small-scale applications, much is still unknown about their shape memory and deformation behavior as size scale is reduced. This paper reports on two sets of experiments which shed light onto an inconsistent body of research regarding the behavior of NiTi at the nano- to microscale. In situ SEM pillar bending experiments directly show that the shape memory behavior of NiTi is still present for pillar diameters as small as 200,nm. Uniaxial pillar compression experiments demonstrate that plasticity of the phase transformation in NiTi is size independent and, in contrast to bulk single crystal observations, is not influenced by heat treatment (i.e., precipitate structure). [source] Influence of Treatment Conditions on the Chemical Oxidative Activity of H2SO4/H2O2 Mixtures for Modulating the Topography of Titanium,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Fabio Variola Abstract Host-tissue integration of medical implants is governed by their surface properties. The capacity to rationally design the surface physico-chemical cues of implantable materials is thus a fundamental prerequisite to confer enhanced biocompatibility. Our previous work demonstrated that different cellular processes are elicited by the nanotexture generated on titanium (cpTi) and Ti6Al4V alloy by chemical oxidation with a H2SO4/H2O2 mixture. Here, we illustrate that by varying the etching parameters such as temperature, concentration, and treatment time, we can create a variety of surface features on titanium which are expected to impact its biological response. The modified submicron and nanotextured surfaces were characterized by scanning electron (SEM) and atomic force (AFM) microscopies. Contact angle measurements revealed the higher hydrophilicity of the modified surfaces compared to untreated samples and Fourier transform infrared spectroscopy (FT-IR) established that the etching generated a TiO2 layer with a thickness in the 40,60,nm range. [source] Direct Laser Interference Structuring as a Tool to Gradually Tune the Wetting Response of Titanium and Polyimide SurfacesADVANCED ENGINEERING MATERIALS, Issue 10 2009Michael Hans Direct laser interference structuring has been used for topographical surface design on titanium and polyimide. The wetting response of processed materials showed a roughness-dependant increase in contact angle starting at initially hydrophilic conditions. [source] Evaluation of Transient Liquid Phase Bonding Between Titanium and SteelADVANCED ENGINEERING MATERIALS, Issue 7 2009Ahmed Elrefaey An investigation of microstructural development in transient liquid phase (TLP) bonds between commercially pure titanium and low carbon steel is presented in this study. Changes in the joint region and surrounding substrates were examined as a function of holding time at temperatures of 870 and 910 °C. Both interfacial microstructures and mechanical properties of brazed joints were investigated to evaluate joint quality. [source] Selective Electron Beam Melting of Cellular Titanium: Mechanical PropertiesADVANCED ENGINEERING MATERIALS, Issue 9 2008P. Heinl Cellular titanium seems to be a promising material for medical implant applications due to an elastic modulus comparable with human bone and an interconnected porosity which facilitates bone ingrowth. This paper reports the mechanical properties of non-stochastic cellular Ti-6Al-4V structures fabricated by Selective Electron Beam Melting depending on different unit cell sizes and varying energy input per unit length of the electron beam. [source] Biocompatibility of Lotus-type Stainless Steel and Titanium in Alveolar BoneADVANCED ENGINEERING MATERIALS, Issue 9 2006Y. Higuchi Abstract Lotus-type porous stainless steel (SUS304L) and porous titanium were fabricated by unidirectional solidification in a mixture gas of hydrogen and argon. The porous metals which were cut into 5,mm cubes (non-dehydrogenated) and 3.4,mm,,×,5,mm cylinders (dehydrogenated) were implanted into the canine mandible alveolar bone for two, four and eight weeks for animal experiments. The changes in the tissues were observed using SEM. For porous stainless steel (cylindrical; dehydrogenated) new formation of bones was observed around the sample in two weeks without any sign of bony ingrowth into the pores. The osteogenesis was found in shallow areas in the pores in four weeks and deep in the pores in eight weeks. Porous titanium, on the other hand, showed deep ingrowth of new bones in four weeks. Our observations allowed us to expect application of the porous metals as biomaterials. They maintain mechanical strength and are lighter in weight so that it is expected to be applied for dental implants and core materials of artificial bones. [source] Development of Cu and Zn Isotope MC-ICP-MS Measurements: Application to Suspended Particulate Matter and Sediments from the Scheldt EstuaryGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2008Jérôme C.J. Petit isotopes de Cu et Zn; interférences spectrales et non spectrales; fractionnement de masse instrumental; MC-ICP-MS; sédiments The present study evaluates several critical issues related to precision and accuracy of Cu and Zn isotopic measurements with application to estuarine particulate materials. Calibration of reference materials (such as the IRMM 3702 Zn) against the JMC Zn and NIST Cu reference materials were performed in wet and/or dry plasma modes (Aridus I and DSN-100) on a Nu Plasma MC-ICP-MS. Different mass bias correction methods were compared. More than 100 analyses of certified reference materials suggested that the sample-calibrator bracketing correction and the empirical external normalisation methods provide the most reliable corrections, with long term external precisions of 0.06 and 0.07, (2SD), respectively. Investigation of the effect of variable analyte to spike concentration ratios on Zn and Cu isotopic determinations indicated that the accuracy of Cu measurements in dry plasma is very sensitive to the relative Cu and Zn concentrations, with deviations of ,65Cu from ,0.4, (Cu/Zn = 4) to +0.4, (Cu/Zn = 0.2). A quantitative assessment (with instrumental mass bias corrections) of spectral and non-spectral interferences (Ti, Cr, Co, Fe, Ca, Mg, Na) was performed. Titanium and Cr were the most severe interfering constituents, contributing to inaccuracies of ,5.1, and +0.60, on ,68/64Zn, respectively (for 500 ,g l,1 Cu and Zn standard solutions spiked with 1000 ,g l,1 of Ti or Cr). Preliminary isotopic results were obtained on contrasting sediment matrices from the Scheldt estuary. Significant isotopic fractionation of zinc (from 0.21, to 1.13, for ,66Zn) and copper (from ,0.38, to 0.23, for ,65Cu), suggest a control by physical mixing of continental and marine water masses, characterized by distinct Cu and Zn isotopic signatures. These results provide a stepping-stone to further evaluate the use of Cu and Zn isotopes as biogeochemical tracers in estuarine environments. L'étude présentée ici porte sur l'évaluation critique d'un certain nombre de paramètres contrôlant la précision et la justesse des mesures des isotopes de Cu et Zn, dans le cadre d'une application à du matériel particulaire estuarien. Une calibration de matériaux de référence (tels que le Zn IRMM 3702) par rapport aux matériaux de référence JMC Zn et NIST Cu a été effectuée avec des plasmas humides et secs (avec Aridus I et DSN-100) sur un MC-ICP-MS Nu. Différentes méthodes de correction de biais de masse ont été comparées. Plus de 100 analyses de matériaux de référence certifiés ont montré que la correction par l'intercalation d'un calibrateur entre chaque échantillon et la calibration externe empirique fournissaient les corrections les plus fiables, avec des précisions externes sur le long terme de 0.06 et 0.07, (2SD) respectivement. Les effets de la variation des rapports de concentrations entre analyte et spike sur les mesures des rapports isotopiques de Cu et Zn ont montré que la justesse des mesures pour Cu en plasma sec est très tributaire des concentrations relatives de Cu et Zn, avec des déviations de ,65Cu allant de ,0.4, (Cu/Zn = 4) à+0.4, (Cu/Zn = 0.2). Une estimation quantitative des interférences spectrales et non spectrales (Ti, Cr, Co, Fe, Ca, Mg, Na) a été faite. Ti et Cr se sont révélés être les constituants interférents les plus importants pouvant entraîner des erreurs de ,5.1, et +0.60, sur ,68/64Zn respectivement (pour des solutions standards à 500 ,g l,1 de Cu et Zn dopées avec 1000 ,g l,1 de Ti ou Cr). Des données isotopiques préliminaires ont été obtenues sur des matrices sédimentaires très différentes provenant de l'estuaire de Scheldt. Les fractionnements significatifs du zinc (de 0.21,à 1.13, pour ,66Zn) et du cuivre (de ,0.38,à 0.23, pour ,65Cu) suggèrent un contrôle par un processus physique de mélange entre des masses d'eaux continentales et marines ayant des signatures isotopiques de Cu et Zn distinctes. Ces résultats constituent un tremplin vers une utilisation future des isotopes de Cu et Zn comme traceurs biogéochimiques des environnements estuariens. [source] Asymmetric meso -Epoxide Ring-Opening with Trimethylsilyl Cyanide Promoted by Chiral Binuclear Complexes of Titanium.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Dichotomy of CC versus CN Bond Formation Abstract In the presence of chiral catalysts derived from the same chiral hexadentate ligand and aluminium, zinc or titanium ions, the reaction between cyclohexene oxide and trimethylsilyl cyanide can be controlled to give predominantly either the nitrile (up to 99% ee) or the isonitrile product (up to 94% ee). The metal ion, ligand stereochemistry and base concentration all play a role in determining the product ratio. [source] Titanium(IV)/Tridentate BINOL Derivative as Catalyst for meso -Aziridine Ring-Opening Reactions: High Enantioselectivity, Strong Positive Non-Linear Effect and Structural CharacterizationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009Rongmin Yu Abstract A titanium-based chiral Lewis acid was found to be effective for the ring-opening reactions of meso -aziridines with aniline nucleophiles. The products were generally isolated in high yields and with high to excellent enantioselectivity. The catalytic system was studied by X-ray single crystal analysis. In experiments on non-linear effects a strong non-linear effect of the catalyst system was observed. [source] Nanocrystalline Titanium(IV) Oxide as an Efficient Heterogeneous Catalyst for Tandem Michael and Nucleophilic 1,2-Addition to EnonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2006Lakshmi Kantam Abstract Nanocrystalline titanium(IV) oxide was found to be an efficient heterogeneous catalyst for the conjugate 1,4-addition of indoles with ,,, - unsaturated ketones to afford ,-indolyl ketones in excellent yields. The subsequent catalytic 1,2-addition of Me3SiCN to carbonyl compounds can be performed in one pot with moderate to good yields. Low sensitivity towards traces of moisture and high tolerance of different functional groups make nanocrystalline titanium(IV) oxide suitable for carrying out multistep synthetic sequences. [source] Epoxidation of allyl chloride and hydrogen peroxide over titanium silicalite-1 film on SiO2 pellet supportJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2007Li Wang Abstract Titanium silicalite-1 (TS-1) films were prepared on SiO2 pellet supports via an in situ hydrothermal synthesis method and were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and 29Si magic angle spinning nuclear magnetic resonance (Si MAS NMR). The growth time of TS-1 film had a strong effect on its morphology and the thickness and size of the crystals. The uniformity and thickness of TS-1 films increased with increase of growth times. The epoxidation of allyl chloride (ACH) with dilute hydrogen peroxide to form epichlorohydrin (ECH) over the TS-1 films was carried out in a fixed bed reactor. The conversion of ACH and the selectivity to ECH over the TS-1 films of the second growth were higher than that of the first growth, the third and the fourth growth. And the conversion and selectivity as a function of time-on-stream gave a good stable performance in an extended test up to at least 19 h. The final steady-state conversion and selectivity were approximately 86% and 55%, respectively. Copyright © 2007 Society of Chemical Industry [source] The ZiReal Post: A New Ceramic Implant AbutmentJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 1 2003URS BRODBECK DMD ABSTRACT Restorations in the anterior esthetic zone present significant challenges in both the surgical and prosthetic phases of implant dentistry. Titanium has been established as the material of choice for endosseous implants, resulting in a high degree of predictability. Many types of implants require transmucosal abutments to retain implant restorations. Ceramics may be the ideal material to replace natural teeth, but most transmucosal abutments are made of titanium. However, ceramics may also be used as abutments in implant restorations. This combination of ceramics for abutment and crown provides better translucency for the implant restoration than is available with metal abutments and porcelain-fused-to-metal crowns. Ceramic abutments and implant restorations also minimize the gray color associated with metal components that is transmitted through the peri-implant tissues. Customized emergence profiles also may be obtained with ceramic abutments; this generally improves the predictability and consistency of the esthetics obtainable in implant restorations. Zirconia as a ceramic material offers not only outstanding material properties but also a well-documented biocompatibility. CLINICAL SIGNIFICANCE This article discusses the clinical and laboratory features of a new ceramic abutment, ZiRealÔ Post (Implant Innovations, Inc., Palm Beach Gardens, Florida). [source] Titanium and zirconium complexes containing modified TREN ligands for the polymerization of 1-alkenes,A comparative studyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2007Padmanabhan Sudhakar Abstract The titanium and zirconium complexes in C3 and Cs symmetric forms synthesized from corresponding aminotriols in combination with MAO polymerized 1-hexene in a controlled manner. When the polymerization temperature was lowered, they gave high molecular weight monodisperse polyhexene with narrow polydispersities indicating quazi-living systems. The isotactic polyhexene obtained from C3 titanium catalyst has the molecular weight of around 46,500 with PDI of 1.3 and the hemi-isotactic polymer from Cs titanium catalyst has the molecular weight of around 617,000 with PDI of 1.3. The analogues zirconium complexes upon activation with MAO polymerize hexene to give polyhexene having molecular weight of 53,000 (C3) and 626,000 (pseudo-Cs) with PDI ranging from 1.2 to 1.4. The MIX-titanium catalyst prepared from the 50:50 mixture of aminotriols was also able to polymerize 1-hexene and the GPC traces of the polyhexene suggests that even though the catalyst was formed from the mixture of aminotriols, the C3 and Cs symmetry of the catalysts retain its originality avoiding the formation of aggregates or polymeric forms. When one of the arms of aminotriol was methylated yield C2 and meso aminodiol ligands and their corresponding titanium and zirconium complexes gave higher molecular weight polyhexenes with lower PDI (C2 -Zr- Mn: 260,000; PDI: 1.05,1.10; mesoZr- Mn: 220,000; PDI: 1.05,1.10) possibly suggesting that these systems are close to living systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5470,5479, 2007 [source] Fatigue and Fluoride Corrosion on Streptococcus mutans Adherence to Titanium-Based Implant/Component SurfacesJOURNAL OF PROSTHODONTICS, Issue 5 2009Cassia Bellotto Correa DDS Abstract Purpose: The influence of fatigue and the fluoride ion corrosion process on Streptococcus mutans adherence to commercially pure Titanium (Cp Ti) implant/component set surfaces were studied. Materials and Methods: Thirty Nobel implants and 30 Neodent implants were used. Each commercial brand was divided into three groups. Group A: control, Group B: sets submitted to fatigue (105 cycles, 15 Hz, 150 N), and Group C: sets submitted to fluoride (1500 ppm, pH 5.5) and fatigue, simulating a mean use of 5 years in the oral medium. Afterward, the sets were contaminated with standard strains of S. mutans (NTCC 1023) and analyzed by scanning electronic microscopy (SEM) and colony-forming unit counts (CFU/mL). Results: By SEM, bacterial adherence was verified only in group C in both brands. By CFU/mL counts, S. mutans was statistically higher in both brands in group C than in groups A and B (p < 0.05, ANOVA). Conclusion: The process of corrosion by fluoride ions on Cp Ti implant/component sets allowed greater S. mutans adherence than in the absence of corrosion and with the fatigue process in isolation. [source] Differing Expansion Contributions of Three Investment Materials Used for Casting TitaniumJOURNAL OF PROSTHODONTICS, Issue 5 2009Danny Low BDS, MScDent, MScMed Abstract Purpose: This laboratory study aimed at investigating the effect of setting expansion (SE), which could enlarge a wax pattern by concurrent exothermic reaction. Materials and Methods: Two phosphate-bonded investment materials (Rematitan Plus, T-invest C & B) and alumina-magnesia-based investment material (Titavest CB) were subjected to setting temperature and SE measurements (n = 10). Full-crown wax patterns were prepared from metal dies having the same design. Crown castings (n = 6) were made using a one-chamber high-pressure casting machine. Commercially pure titanium ingot (Japanese Industrial Standard Class II) was used for each casting. Dimensional accuracy of the cast crowns was expressed by marginal discrepancy for a pair of wax pattern and casting prepared from the same die. All results were then subjected to regression analysis. Results: Rematitan Plus gave the highest setting temperature (about 70°C) and the highest SE (1.16 ± 0.01%) almost concurrently. The result was that Rematitan Plus produced oversized crowns from the lowest thermal expansion (TE) value (0.53 ± 0.05%) reducing the linear correlation to 0.80 (p < 0.05). No significant linear relationship was found between SE of investment material and crown-casting accuracy. Conclusions: The almost concurrent occurrence of high SE and high setting temperature generation in Rematitan Plus enlarged the wax pattern and effectively supplemented its low TE to produce oversized crowns. Despite this adverse effect, the correlation between TE and crown accuracy was still high. It is generally expected that the TE values given by manufacturers predict crown accuracy, when uniform TE, small SE, and minimum heat generation during setting are assured. [source] Titanium in Today's Dental Practice.JOURNAL OF PROSTHODONTICS, Issue 3 2000What Cuts It? [source] Fabrication of High-Purity Ti3SiC2 Powders by an In Situ Reaction of Polycarbosilane and Metal TitaniumJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Jinshan Yang High-purity titanium silicon carbide powders were fabricated by an in situ reaction of polycarbosilane and metal titanium. The effects of the starting reagents and the pyrolysis temperature on the fabrication of high-purity Ti3SiC2 were studied. The results showed that high-purity Ti3SiC2 could be obtained when the atomic ratio of Ti:Si was 3:1.5 and the effect of the temperature of pyrolysis on the purity of the powders was insignificant. The atomic ratio of Ti:Si was calculated on the basis of the empirical formula of SiC2.5H7. [source] Screening of Different Titanium (IV) Catalysts in the Synthesis of Poly(ethylene terephthalate)MACROMOLECULAR REACTION ENGINEERING, Issue 6 2008Fatemeh Ahmadnian Abstract The polycondensation of bis(hydroxyethylene) terephthalate and its oligomers to PET catalyzed by different chelated and non-chelated titanium catalysts in a lab-scale stirred-tank reactor and differential scanning calorimeter were investigated. Different titanium compounds showed different activity and selectivity. The nature of catalyst ligands plays an important role in catalyst efficiency. Non-chelated titanium derivatives were more active and less selective. Reaction progress is characterized by an initial inhibition period depending on the type of catalyst. The original titanium compounds used are precursors and are probably activated by a ligand exchange reaction. [source] Effect of potential on the corrosion behavior of a new titanium alloy for dental implant applications in fluoride mediaMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2004A. M. Al-Mayouf Abstract The effect of fluoride ion concentration and pH on the corrosion behavior of TCA (60 Ti 10 Ag 30 Cu), which is a new Ti alloy with low melting point, pure Titanium (Ti), and TAV (TiAl6V4) was examined using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) at different potentials. Results show that the corrosion resistance of TCA and Ti decrease at anodic potentials compared with results obtained at OCP. At one potential the corrosion resistance decrease depends on NaF concentration and pH. TAV shows less resistance against corrosion in fluoride containing saliva. TCA has potentials more positive than Ti and TAV due to surface enrichment of Cu and Ag as Ti dissolves which accelerates the cathodic reaction. Fluoride ion may not hinder the growth of oxide layers on the surfaces of the electrodes. It will have influence on the properties of the oxide layer causing them to be not protective against corrosion in acid media containing fluoride ions. [source] Sol,gel derived metal oxides doped with silver nanoparticles as tunable plasmonic materialsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010Leonid Dolgov Abstract New composite materials made of transition metal oxides doped with silver nanoparticles are proposed. Titanium and zirconium dioxide matrices were prepared by sol,gel method adjusted for addition of silver nanodopants. Commercially available silver nanoparticles in the form of powder (30,50,nm) or colloidal solution (5,15,nm) were used for doping of oxide hosts. To recover plasmonic properties of silver after annealing in air, reduction of samples in the H2:Ar atmosphere was performed. As a result, the silver-containing TiO2 and ZrO2 films of good optical quality with plasmonic absorption near 400,nm were obtained. The potential of embedding of luminescent markers (like rare earth ions) into considered films is discussed. [source] Bulk nanostructured titanium fabricated by hydrostatic extrusionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2010Krzysztof Topolski Abstract The paper is concerned with the use of Hydrostatic Extrusion (HE), which is one of the methods of Severe Plastic Deformation (SPD), for grain refinement of titanium grade 2. Titanium in the form of rods was subjected to multi-stage extrusion. The aim was to optimize the HE process so as to obtain nanostructured titanium rods. The results show that it is possible to produce nanostructured Ti rods of a diameter suitable for industrial applications. The refinement to nano-sized grains is accompanied by a significant improvement of mechanical properties. The tensile strength of more than 1000MPa was achieved and the hardness increase exceeded 50%. This study was also concerned with the problem of up-scaling the dimensions of nano-refined components produced by HE. The basic condition for HE to yield nanostructured Ti is that an appropriately high accumulated strain should be applied (, > 3). The results demonstrate that, by using HE, we can produce nano-Ti rods with diameters amounting to ,8mm. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Titanium versus Nontitanium Prostheses in Ossiculoplasty,THE LARYNGOSCOPE, Issue 9 2008Charles S. Coffey MD Abstract Objectives/Hypothesis: To compare the hearing outcomes and complications observed using either titanium or nontitanium prostheses in a 7-year consecutive series of ossiculoplasties performed by a single surgeon. Study Design: Retrospective. Methods: A database of ossicular reconstruction surgeries was reviewed for preoperative and postoperative audiometric data including air and bone conduction thresholds at four frequencies and speech reception thresholds. Outcomes were evaluated at time points less than and greater than 6 months postoperatively. Baseline demographic and surgical characteristics and postoperative complications were also noted. Results: A total of 105 cases had sufficient audiometric data available for analysis, including 80 performed with titanium and 25 with nontitanium implants. Follow-up ranged from 1.2 to 74.2 months, with a mean of 14.9 months. Mean air-bone gap at initial follow-up was 21.7 dB in the nontitanium group and 15.4 dB in the titanium group; this difference was significant (P = .01). Postoperative air-bone gap of less than 20 dB at initial follow-up was achieved in 50.0% of nontitanium cases and 77.1% of titanium cases (P = .012). This difference in "success" rates persisted at longer follow-up but did not achieve statistical significance. Mean speech reception thresholds at <6 months was 29.7 dB in the nontitanium group and 22.6 dB in the titanium group (P = .049). Extrusion was observed with two nontitanium prostheses (8.0%) and three titanium prostheses (3.8%) (P > .05). Conclusions: Titanium ossicular prostheses provide hearing outcomes superior to those of nontitanium prostheses when evaluated within 6 months after ossiculoplasty. [source] Highly Enantioselective Epoxidation of Styrenes Catalyzed by Proline-Derived C1 -Symmetric Titanium(Salan) Complexes,ANGEWANDTE CHEMIE, Issue 40 2009Kazuhiro Matsumoto Dr. Titanhart! Mit neuartigen, von Prolin abgeleiteten C1 -symmetrischen Titan(salan)-Komplexen gelingt die Epoxidierung von Styrolderivaten mit wässrigem Wasserstoffperoxid als Oxidationsmittel mit Enantiomerenüberschüssen zwischen 96 und 98,% (siehe Schema). [source] | ||||||||||||||||||||||||||||||||||||||||||||||