Immobilized-OPG-Fc on a titanium surface inhibits RANKL-dependent osteoclast differentiation in vitro

The purpose of the present study was to examine the effect of osteoprotegerin (OPG)-Fc fusion protein immobilized on a titanium surface on the initial differentiation of osteoclast precursor RAW264.7 cells. These cells were cultured on titanium specimens over which OPG-Fc was immobilized. The enhancement of tartrate-resistant acid phosphatase (TRAP) and cathepsin K mRNA expression in RAW264.7 cells exposed to receptor activator of NF-κB ligand (RANKL) stimulation on OPG-Fc-coated titanium was significantly lower than that in RAW264.7 cells exposed to RANKL on titanium specimens without immobilized OPG-Fc (ANOVA, P < 0.01). Preincubation of OPG-Fc-coated titanium, in a medium supplemented with 10% fetal bovine serum at 37°C for two days before the cells were seeded, had no significant effect on the decrease in mRNA expression (ANOVA, P < 0.01). Taken together, these results indicate that OPG-Fc immobilized on a titanium surface blocks the differentiation of RAW264.7 cells induced by RANKL stimulation.     

Antibacterial and bioactive calcium titanate layers formed on Ti metal and its alloys

An antibacterial and bioactive titanium (Ti)-based material was developed for use as a bone substitute under load-bearing conditions. As previously reported, Ti metal was successively subjected to NaOH, CaCl₂, heat, and water treatments to form a calcium-deficient calcium titanate layer on its surface. When placed in a simulated body fluid (SBF), this bioactive Ti formed an apatite layer on its surface and tightly bonded to bones in the body. To address concerns regarding deep infection during orthopedic surgery, Ag⁺ ions were incorporated on the surface of this bioactive Ti metal to impart antibacterial properties. Ti metal was first soaked in a 5 M NaOH solution to form a 1 μm-thick sodium hydrogen titanate layer on the surface and then in a 100 mM CaCl₂ solution to form a calcium hydrogen titanate layer via replacement of the Na⁺ ions with Ca²⁺ ions. The Ti material was subsequently heated at 600 °C for 1 h to transform the calcium hydrogen titanate into calcium titanate. This heat-treated titanium metal was then soaked in 0.01–10 mM AgNO₃ solutions at 80 °C for 24 h. As a result, 0.1–0.82 at.% Ag⁺ ions and a small amount of H₃O⁺ ions were incorporated into the surface calcium titanate layers. The resultant products formed apatite on their surface in an SBF, released 0.35–3.24 ppm Ag⁺ ion into the fetal bovine serum within 24 h, and exhibited a strong antibacterial effect against Staphylococcus aureus. These results suggest that the present Ti metals should exhibit strong antibacterial properties in the living body in addition to tightly bonding to the surrounding bone through the apatite layer that forms on their surfaces in the body.     

Hierarchical flower-like titanium phosphate derived from H-titanate nanotubes for photocatalysis

Nanosheet-assembled hierarchical flower-like titanium phosphate (TiP) is synthesized via hydrothermal treatment of H-titanate nanotubes (Ti-NT) at the optimized conditions of 0.1 M of H₃PO₄ and hydrothermal temperature of 130 °C. A possible formation mechanism for the TiP flowers, involving the disintegration of Ti-NT and the growth and assembling of TiP nanosheets, is proposed. The main compositions of the uncalcined TiP flowers are titanium hydrogen phosphate hydrates (Ti(HPO₄)₂·xH₂O), which can be transformed to titanium phosphate (TiP₂O₇) after high temperature calcination. The photocatalytic activity of the prepared TiP flowers is increased with the increased calcination temperature, which may be attributed to the better photocatalytic activity of TiP₂O₇ than Ti(HPO₄)₂·xH₂O and the increased crystallization of TiP₂O₇.     

Surface modification of a Ti–7.5Mo alloy using NaOH treatment and Bioglass® coating

The objective of this study was to propose a surface modification for a low-modulus Ti–7.5Mo alloy to initiate the formation of hydroxyapatite (HA) during in vitro bioactivity tests in simulated body fluid (SBF). Specimens of commercially pure titanium (c.p. Ti) and Ti–7.5Mo were initially immersed in a 15 M NaOH solution at 60°C for 24 h, resulting in the formation of a porous network structure composed of sodium titanate (Na₂Ti₅O₁₁). Afterwards, bioactive Bioglass^® particles were deposited on the surface of NaOH-treated c.p. Ti and Ti–7.5Mo. The specimens were then immersed in SBF at 37°C for 1, 7 and 28 days, respectively. The apatite-forming ability of the NaOH-treated and Bioglass^®-coated Ti–7.5Mo was higher than that of the c.p. Ti under the same condition. The X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) results indicated that the deposited amounts of calcium phosphate were much greater for the surface-treated Ti–7.5Mo than for the c.p. Ti, a finding attributable to or correlated with the higher pH value of the SBF containing surface-treated Ti–7.5Mo. Moreover, in the surface-treated Ti–7.5Mo, the pH value of the SBF approached a peak of 7.66 on the first day. A combination of NaOH treatment and subsequent Bioglass^® coating was successfully used to initiate in vitro HA formation in the surface of the Ti–7.5Mo alloy.     

Hydriding and dehydriding rates and hydrogen-storage capacity of Mg–14Ni–3Fe2O3–3Ti prepared by reactive mechanical grinding

The magnesium prepared by mechanical grinding under H₂ (reactive mechanical grinding) with transition elements or oxides showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni (expected to increase hydriding and dehydriding rates) was chosen as transition element to be added. Fe₂O₃ (expected to increase hydriding rate) was selected as an oxide to be added. Ti was also selected since, it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. A sample, Mg–14Ni–3Fe₂O₃–3Ti, was prepared by reactive mechanical grinding and its hydrogen storage properties were investigated. This sample absorbed 4·02 wt% H for 5 min, 4·15 wt% H for 10 min and 4·42 wt% H for 60 min at n?=?2. It desorbed 2·46 wt% H for 10 min, 3·98 wt% H for 30 min and 4·20 wt% H for 60 min at n?=?2.     

Catalytic decomposition of organic anions in alkaline radioactive waste: III. Oxidation of oxalate and glycolate

Decomposition of oxalate and glycolate ions in alkaline solutions under the action of O₃, H₂O₂, and Na₂S₂O₈ was studied spectrophotometrically and titrimetrically. At 20°C, ozone slowly decomposes oxalate in 0.05 M NaOH. In 1 M NaOH, heating at 90°C is required to oxidize oxalate with ozone. Glycolate is readily oxidized with ozone at 20°C in 0.05–1 M NaOH, predominantly into oxalate. Hydrogen peroxide is ineffective reagent for oxalate and glycolate decomposition. Persulfate oxidizes oxalate ion in 0.5–5 M NaOH at 90°C. The reaction of persulfate with glycolate proceeds at 50°C and higher temperatures and is characterized by an induction period, which shortens with increase in concentration of S₂O ₈ ^2? , OH^?, and temperature, or in the presence of AgNO₃ and K₄Fe(CN)₆. Oxidation involves thermal dissociation of persulfate ions into radical ions followed by a chain reaction.     

A thermodynamic study of the systems Ti  O  X II. Investigation of the system TiO2  Ti  Cl2

The equilibrium composition of the gas phase and the yield of titanium oxides in the system TiO₂  Ti  Cl₂ have been calculated at preset temperatures and total pressure of the gas phase in the system, TiO₂:Ti ratios used in the preparation of TiO, Ti₂O₃, Ti₃O₅ and Ti_nO_2n?1 (4 ? n ? 10) and varying chlorine concentrations. The results obtained are discussed with a view to prepare titanium oxides single crystals by the chemical transport method.     

Processing,spark plasma sintering,and mechanical behavior of alumina/titanium composites

This paper focuses on the study of the processing and mechanical properties, (flaw tolerance and R-curve behavior) of alumina–titanium ceramic–metal composites produced by spark plasma sintering. In order to obtain homogenously dispersed composites, a rheological study was carried out by measuring the flow behavior in different conditions of solid content, amount of dispersant and shear stress. It has been found that, with the suitable conditions (80 wt% solids and 3 wt% deflocculant), a ceramic–metal homogeneously dispersed (Al₂O₃–Ti) composite can be obtained. After sintering, the composites were mechanically tested and the cermet showed an important improvement in the flaw tolerance and R-curve behavior when compared with the monolithic material. It has been demonstrated by scanning electronic microscopy that this improvement is a consequence of the reinforcement mechanisms provided by the metallic particles that interact with the crack producing a notable increase in toughness up to ~8 MPa m^1/2.     

Effect of Ba deoxidation on oxygen content in NiTi alloys and non-metallic inclusions

The effect of Ba deoxidation on the oxygen content and non-metallic inclusions in NiTi alloys was investigated. The NiTi alloy melt was held in a CaO crucible at 1673 K under Ar gas flow for 0–600 s. Metallic Ba (0.5–1.5 mass% with respect to NiTi alloy melt) was added to the melt. After melting, oxygen content of 710 and 330 mass ppm decreased to 210 and 130 mass ppm, respectively, after a holding time of 300 s after the addition of Ba. The oxygen in the melts was reduced to as low as 64 mass ppm after a second Ba deoxidation. The non-metallic inclusions observed in the NiTi alloys were the Ti₄Ni₂O _X and Ti(C,N,O) _X types. Decreased oxygen content through Ba deoxidation caused a change in the main phase of the non-metallic inclusions from the Ti₄Ni₂O _X type to the Ti(C,N,O) _X type, and a decrease in the area percents of the non-metallic inclusions.     

Fabrication and characterization of nanostructured (Sn–Ti)O<Subscript>2</Subscript> pellets and films for liquefied petroleum gas sensing

Present paper reports the synthesis of nanostructured (Sn–Ti)O₂ via physicochemical method, its characterization and performance as liquefied petroleum gas (LPG) sensor. The synthesized material was characterized using XRD that confirmed the formation of (Sn–Ti)O₂ nanocomposite. Minimum crystallite size was found as 7 nm. The material was also investigated through SEM, DSC, FTIR, PL and UV–Vis spectrophotometer. Further, the pellet, thick and thin films were fabricated for the sensing analysis. Pellets (9 mm diameter, 4 mm thickness) of (Sn–Ti)O₂ nanocomposite were made by hydraulic pressing machine by applying uniaxial pressure of 616 MPa, thick films (thickness ~2 µm) were made by screen printing technique and thin films were prepared using a Photo resist spinner unit. Further at room temperature, the pellet and films were exposed to LPG in a gas chamber under controlled conditions at room temperature and variations in resistance with the concentrations of LPG were observed. The maximum value of sensitivity of solid state pellet, thick and thin films based sensors were found 7, 9 and 39 for 5 vol% of LPG, respectively. Sensing characteristics were found to be reproducible, after 6 months of their fabrication, indicating the stability of the sensors.     

The effect of Mg:Ti ratio on the phase composition and microwave dielectric properties of MgTiO3 ceramics prepared by one synthetic process

In this paper, MgO–CaO–TiO₂ based ceramics was prepared by solid-state reaction technique and the effect of Mg:Ti ratio (0.873–1.057) on the phase, microstructure and microwave dielectric properties were investigated. Only two phases MgTiO₃ and CaTiO₃ appeared in the sample with Mg:Ti = 0.955, and MgTi₂O₅ and Mg₂TiO₄ appeared in the sample with Mg:Ti ratio lower and higher than 0.955 respectively. The microstructure showed the dark MgTiO₃ grains and the bright grains with three elements Mg, Ca and Ti in the triangle grain boundary. As increasing the ratio of Mg:Ti, the dielectric constant (ε_r) displayed down trend from 21.2 to 20.6, and the Q × f value first increased from 76,300 to 80,000 GHz, thereafter, it declined to 75,000 GHz. Meanwhile, the temperature coefficient of resonant frequency (τ_f) value first varied from ?3.8 to 1.2 ppm/°C and then maintained unchanged. At last, our MgO–CaO–TiO₂ based ceramics with Mg:Ti = 0.955 sintered at 1,310 °C for 4 h showed good microwave dielectric properties: ε_r = 21.1, Q × f = 79,915 GHz and τ_f = 1.2 ppm/°C.     

First-principles calculations of elastic moduli of Ti–Mo–Nb alloys using a cluster-plus-glue-atom model for stable solid solutions

Using the first-principles calculations, a cluster-plus-glue-atom model was employed to investigate the elastic and electronic properties of Ti–Mo–Nb alloys with cluster formula of [MoTi₁₄] (glue atom) _x (glue atom = Ti, Mo, Nb, x = 1 or 3) for a theoretical guidance in composition design of β titanium alloys. The bulk modulus, shear modulus, Young’s modulus, and Poisson ratio were evaluated from the calculated elastic constants using Voigt–Reuss–Hill average scheme on the periodic supercell model of cluster packing. The electronic properties of the Ti–Mo–Nb alloys were discussed by analyzing the electron density of state and Mulliken population. Meanwhile, we designed two series of Ti–Mo–Nb alloys, i.e., [MoTi₁₄]X₁ (X = Ti, Mo, Nb) and [YTi₁₄]Nb₃ (Y = Ti, Mo), and experimentally measured their mechanical properties. Our theoretical results (including mass density, Young’s modulus, ductility) based on our cluster packing model agreed well with the experimental data, especially for [TiMo₁₄]X₁ (X = Ti, Mo, Nb) alloy series. On the contrary, the random solid solution structures were mechanically unstable and the calculated values significantly deviated from the experiments. Based on the cluster-plus-glue-atom model, an Ashby map of E/ρ versus B/G was constructed and indicated the inverse correlation between stiffness and ductility, for which the random solid solution model was unable to reflect. The Mo/Ti = 1/14 rule derived from the cluster model may serve as an important guideline for composition design of Ti–Mo based systems to achieve low elastic modulus alloys with stable β phase.     

Ti doped hematite thin film photoanode with enhanced photoelectrochemical properties

Ti-doped Fe₂O₃ thin films were prepared on fluorine-doped SnO₂ substrate as visible light active photoelectrochemical anodes. The fabricated films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD data showed all films exhibited rhombohedral hematite phase, and the cell parameters showed that Titanium atoms substituted Fe atoms in the hematite lattice. AFM demonstrated that Ti doping could decrease the particle size on the surface compared with pure hematite. XPS results presented that Ti atom concentration was about 2.23 % in the doped film surface. The incident photon to electron conversion efficiency of Ti doped α-Fe₂O₃ film reached 23 % at 400 nm under 0.30 V bias versus AgCl in 1 M NaOH, which was nearly four times than that of undoped film. Titanium atoms in α-Fe₂O₃ lattice could increase the conductivity of hematite film. And excited electrons and holes in the bulk film could be separated more efficiently, rather than recombining with each other rapidly as that in pure hematite, which ultimately prolonged the life of electrons and holes and obtained the high efficiency Fe₂O₃ photo anode.     

Active Soldering of ZnS–SiO2 Sputtering Targets to Copper Backing Plates Using an Sn56Bi4Ti(Ce,Ga) Filler

ZnS–SiO₂ targets have been directly soldered to copper backing plates at 180°C in air using an Sn56Bi4Ti(Ce, Ga) filler. The affinity of cerium to oxygen protects titanium from oxidation, allowing titanium to react with ZnS–SiO₂ sputtering target. The shear strengths are 1.7, 8.7, and 1.3 MPa for ZnS–SiO₂/ZnS–SiO₂, copper/copper and ZnS–SiO₂/copper joints, respectively. EPMA elemental mapping shows that aging test at 120° for 100 hours enhanced the segregation of titanium at the ZnS–SiO₂/solder interfaces. The shear strength of ZnS–SiO₂/copper joint after aging test is 1.3 MPa that shows no trace of degradation compared to the initial quality of the samples.     

Crystal structure and photocatalytic properties of titanate nanotubes prepared by chemical processing and subsequent annealing

Anatase TiO₂ nanoparticles were synthesized from sol–gel processing, and they were used as a precursor for titanate nanotubes (TNT) formation. TNT were synthesized under reflux heating of anatase TiO₂ in concentrated NaOH solution followed by repeated washing with distilled water and 0.1 M HCl. The nanotubular structure was preserved till 450 °C, above which nanorod formation started. The as-synthesized nanotubes were found to have mixed crystal structure of anatase and Na _x H_2?x Ti₃O₇·nH₂O (where 0 < x <  2), contrary to what has been reported before. The XRD peaks of titanate were slightly shifted to higher angles upon calcination along with prominent anatase peaks. Complete transformation to nanorods occurred at 600 °C and crystal structure was transformed to Na₂Ti₆O₁₃ and anatase. Sodium presence in TNT was confirmed by EDX, and Na–O and H–O–H along with Ti–OH vibrations were found by FTIR. Ti–OH/H–O–H vibrations were less prominent for samples calcined at 500 °C and above, which confirms structural water loss is associated with morphological change. The as-synthesized TNTs had a specific surface area of 157 m² g^?1, and it decreased by increasing calcination temperature. TNTs were applied to methylene blue aqueous solution to observe their decolorization capability under UV irradiation. The as-synthesized TNTs showed enhanced photocatalytic decolorization as compared to anatase titania nanoparticles due to presence of Ti–OH groups and higher specific surface area. The photocatalytic activity reduced when TNTs were annealed at high temperatures. The changes in the photocatalytic activity are related to the existence of hydroxyl groups in the structure, decrease in specific surface area of annealed nanotubes, change in morphology from nanotubes to nanorods, and bandgap shift to visible light when TNTs were calcined at higher temperatures.     

Sol–gel preparation and characterization of black titanium oxides Ti2O3 and Ti3O5

Sub-micron black titanium oxides powders Ti₂O₃ and Ti₃O₅ were synthesized via a facile and economical sol–gel method in this paper. Relatively pure Ti₃O₅ and Ti₂O₃ can be obtained by annealing the as-prepared PEG600-based gel with a heating rate of 10 °C min^?1 and maintaining the temperature at 1,000 and 1,200 °C, respectively, under high pure (99.999 %) argon atmosphere for 4 h. The FESEM images reveal that the morphologies of the as-prepared Ti₃O₅ and Ti₂O₃ are sphere-like and plate-like mixed type structures. The particle size of Ti₃O₅ sample is in the range of 50–200 nm. However, the appearance of Ti₂O₃ is 200–500 nm irregular flake structures covered with 20–50 nm spherical particles. This PEG600-based sol–gel approach has a low reaction temperature of 1,000 °C herein for the preparation of Ti₃O₅, which is ascribed to that, the molecular PEG-600 was distributed well in the homogeneous gel through secondary cross-linking of the organic molecules, and with the increasing of heating temperature, molecular PEG-600 was carbonized. These nanoscaled and homogeneous mixtures of carbon and TiO₂ made the carbon thermal reduction reaction occur subsequently at 1,000 °C. The Raman vibrational wavenumbers of as-prepared Ti₃O₅ and Ti₂O₃ are perfectly coincident with those of calculated results of pure Ti₃O₅ and Ti₂O₃. Besides, the Fourier transform infrared spectra of Ti₃O₅ and Ti₂O₃ were also investigated in this article. Finally, the powder electrical resistivity of Ti₃O₅ and Ti₂O₃ is 4.7 × 10^?3 and 2.5 × 10^?3 Ω m, respectively.     

Phase evolution and reaction mechanism during reduction–nitridation process of titanium dioxide with ammonia

Titanium nitride powders were synthesized from titanium dioxide at 1173–1373 K in ammonia atmosphere. The reduction–nitridation products with various fractions obtained at various temperatures were analyzed by X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, and selected area electron diffraction. The reaction sequence from TiO₂ to TiN in ammonia atmosphere was changed by increasing the reaction temperature. The reaction sequence at 1173 K was found as TiO₂ → TiN_1?xO_x → TiN. When the reaction temperature was above 1273 K, the reaction sequence changed to as follows: TiO₂ → Ti₉O₁₇ → TiN_1?xO_x → TiN. Ti₃O₅ was not found as an intermediate phase on account of its instability in NH₃ atmosphere. The morphology of the synthesized TiN is closely related to that of the raw materials.     

Microwave dielectric properties and low temperature sintering of Li2Zn(Ti1−xSnx)3O8 (x ≤ 0.20) ceramics with B2O3–CuO addition

In the present work, the influence of Sn substitution for Ti on the phase composition and microwave dielectric properties of the Li₂Zn(Ti_1?xSnx)₃O₈ (x ≤ 0.20) ceramics was studied. It was found that the Sn did not occupy the Ti site in the Li₂Zn(Ti_1?xSn_x)₃O₈ system but existed in the form of SnO₂ as a secondary phase. With the increase of Sn amount, the best microwave dielectric properties with ε_r = 23.3, Q × f = 71,000 GHz and TCF = ?21.7 ppm/°C were obtained in the Li₂Zn(Ti_0.9Sn_0.1)₃O₈ ceramic sintered at 1,120 °C. The sintering temperature of Li₂Zn(Ti_0.9Sn_0.1)₃O₈ ceramic can be can effectively lowered to below 960 °C by the addition of 0.4B₂O₃–0.6CuO and this materials is chemically compatible with silver. This makes the Li₂Zn(Ti_1?xSn_x)₃O₈ ceramics good candidates for low temperature co-fired ceramics technology.     

Synthesis and conductive performance of antimony-doped tin oxide-coated TiO2 by the co-precipitation method

The synthesis of Sb–SnO₂/TiO₂ (SST) composites by assembling antimony-doped tin oxide (Sb–SnO₂) nanoparticles on the surface of titanium dioxide (TiO₂) is systematically investigated. X-ray diffraction data show that the SST composite materials with good crystallinity can be indexed as anatase TiO₂ phase and cassiterite SnO₂ phase. The scanning electron microscopy and transmission electron microscopy indicate that Sb–SnO₂ particles with average diameter of 25 nm have been successfully coated on the surface of TiO₂. In addition, the Ti–O–Sn band can be detected on the surface of TiO₂ through Fourier translation infrared spectroscopy. The influences of pH, Sn/Ti mole ratio, hydrolysis temperature and calcination temperature on the electrical resistivity of the SST powders are studied. Under the optimum experimental conditions, the electrical resistivity of the composite conductive powders is 2.546 × 10³ Ω cm. Therefore, the SST composite conductive powders are useful as conductive fillers for the application in antistatic materials.     

Reduced titanium oxide Ti3O5 powder as a promising conductive additive for LiFePO4-based lithium-ion batteries

Reduced titanium oxide Ti₃O₅ powder which was fabricated by a sol–gel process was added to lithium iron phosphate (LiFePO₄) cathode electrodes for use in lithium-ion batteries and its performance was investigated. First discharging of the cathode electrode with Ti₃O₅ powder as the conductive additive keeps the capacity of 170.9 mAh g^?1 at 0.1 C, 150.8 mAh g^?1 at 0.5 C, 134.6 mAh g^?1 at 1 C, and 107 mAh g^?1 at 2 C, respectively, which is higher than that of the cathode electrode with acetylene black as the conductive additive, who keeps the capacity of 162 mAh g^?1 at 0.1 C, 142.8 mAh g^?1 at 0.5 C, 126.9 mAh g^?1 at 1 C, and 105.8 mAh g^?1 at 2 C, respectively. Over 100 cycles at 0.5 C, the LiFePO₄ cathode electrode with Ti₃O₅ powder can maintain 77.5 % of its initial capacity, and the electrode with acetylene black shows 73.6 % capacity retention. The reason why the electrode with Ti₃O₅ additive shows better rate capability is that the Ti₃O₅ powder exhibits a relatively good electrical conductivity and shows a more homogeneous dispersion than acetylene black among the LiFePO₄ particles during the cycles, in the investigation, a layer of suspected titanium oxide yarn-like thin film is discovered coating on the LiFePO₄ particles of the cathode electrode with Ti₃O₅ powder after 100 cycles at 0.5 C.