Titanium

Ordered (SBA-15) and disordered (KIL-2) mesoporous silica supports have been synthesized and used for incorporation of titania with different Ti/Si molar ratios (1/2, 1/1, 2/1) via sol–gel impregnation method. Titanium isopropoxide and aqueous titania sol prepared by low-temperature sol–gel processing were used as a source of titania. Characterization by powder X-ray diffraction (XRD), nitrogen sorption measurements, scanning electron microscopy (SEM) and UV–vis–NIR diffuse reflectance spectroscopy (DRS) has been carried out to investigate the chemical framework and morphology of powders. The photocatalytic degradation of isopropanol in the gaseous medium was selected as a probe reaction to test the photoactivity of powders and to verify the potential application of these materials for air remediation. It was found that the titania source, Ti/Si molar ratio and the type of silica support influenced the functional properties of the material, which were evaluated by adsorption capacity and photocatalytic activity in the gas–solid reactor. The adsorption capacity of isopropanol was the highest in the presence of the SBA-15-supported materials. The photoactivity results indicated that the powders which were prepared using SBA-15 as a silica support and a Ti/Si molar ratio of 1/1 were the most active towards isopropanol oxidation monitored in situ by FT-IR spectroscopy.

The purpose of this 2-part opinion article was to project the developments expected to occur in the next few years in orthodontic materials research and applications. Part 1 reviewed developments in bonding to enamel. Part 2 looks at other orthodontic materials applications and explores emerging research strategies for probing the biological properties of materials. In the field of metallic brackets, expansion of the use of titanium alloys with improved hardness and nickel-free steels with better corrosion resistance and increased hardness is expected. Manufacturing techniques might be modified to include laser-welding methods and metal injection molding. Esthetic bracket research will involve the synthesis of high-crystallinity biomedical polymers with increased hardness and stiffness, decreased water sorption, and improved resistance to degradation. New plastic brackets might incorportate ceramic wings. Fiber-reinforced composite archwires, currently experimental, could soon be commercially available, and long-term applications of shape-memory plastics might become viable. Advancements in elastomeric materials will result in polymers with reduced relaxation, broader use of fluoride-releasing elastomers with decreased relaxation, and large-scale film coating of elastomers to decrease reactivity, water sorption, and degradation. Finally, biocompatibility assessments will incorporate testing of potential endocrinological action. New polymer formulations might be tested in adhesive and plastic bracket manufacturing, based on benzoic ring-free monomers to avoid the adverse effects of the estrogenic molecule bisphenol-A. (Am J Orthod Dentofacial Orthop 2007;131:253-62) T he second part of this article includes a review of the current status of brackets, elastomerics, and archwires along with a projection of future developments in materials technology and clinical applications. It also gives a brief description of the novel assessment of the biological properties of polymers, which have already been implemented in associated biomedical disciplines.

We investigated the wetting behavior and reactions of different metals on Si3N4 using sessile drop measurements, analysis of reaction layers, and measuremeints of strengths of joined bars. Active metals, such as A1 and Ti, and alloys that contain them react with Si3N4 and cause ,wetting and spreading at the interface. AI-Si3N4 reaction at 900°C produced a thin layer of A1203 at the interface. Reaction between Si3N4 and Ag-Cu-Ti braze alloys at 900°C resulted in a complex microstructure in the reaction zone that contained TIN and titanium silicides. Breaking strengths of Si3N4 bars joined with the Ag-Cu-Ti braze alloys were higher than those for Si3N4 joined with Al, primarily because of the better wetting by the Ag-Cu-Ti alloys. Nonreactive metals and alloys such as Sn, In, Ag-Cu, and Ag-Cu-Sn neither wet, spread, nor adhere to Si3N4 substrates. [

X-ray fluorescence microscopy (XFM) facilitates high-sensitivity quantitative imaging of trace metals at high spatial resolution over large sample areas and can be applied to a diverse range of biological samples. Accurate determination of elemental content from recorded spectra requires proper calibration of the XFM instrument under the relevant operating conditions. Here, we describe the manufacture, characterization, and utilization of multielement thin-film reference foils for use in calibration of XFM measurements of biological and other specimens. We have used these internal standards to assess the two-dimensional distribution of trace metals in a thin tissue section of a rat hippocampus. The data used in this study was acquired at the XFM beamline of the Australian Synchrotron using a new 384-element array detector (Maia) and at beamline 2-ID-E at the Advanced Photon Source. Post-processing of samples by different fixation techniques was investigated, with the conclusion that differences in solvent type and sample handling can significantly alter elemental content. The present study highlights the quantitative capability, high statistical power, and versatility of the XFM technique for mapping trace metals in biological Published in the special issue Imaging Techniques with Synchrotron Radiation samples, e.g., brain tissue samples in order to help understand neurological processes, especially when implemented in conjunction with a high-performance detector such as Maia.

An organically templated titanium phosphate, (C 6 H 13 NH 3 )[Ti(HPO 4 )(PO 4 )]‚H 2 O, has been prepared by hydrothermal synthesis from titanium(IV) chloride, phosphoric acid, and n-hexylamine. The structure of this material has been characterized by powder X-ray diffraction (XRD), 1 H [including 1 H{FS-Lee-Goldburg (LG)}-1 H homonuclear correlation (HOMCOR), 1 H double quantum (DQ), and 1 H{FS-LG}-31 P cross-polarization (CP) heteronuclear correlation (HETCOR)], 13 C, and 31 P magic-angle spinning (MAS) NMR, Fourier transform infrared (FTIR) spectroscopy, and thermal analyses [thermogravimetry (TG) and differential scanning calorimetry (DSC)]. Based on the empirical evidence, particularly solidstate NMR, modeling studies, and powder XRD, a crystal structure has been proposed, having unit cell parameters a ) 5.089(2) Å, b ) 6.335(2) Å, c ) 22.792(5) Å, ) 102.48(2)°, space group P2 1 , and Z ) 2. This compound is built up of anionic titanium phosphate layers, similar to those present in the γ-type titanium phosphate, with n-hexylammonium cations intercalated in the interlayer space.

Thin films of the lanthanum titanium oxynitride perovskite (LaTiO x N y ) synthesized by reactive radio-frequency sputtering on conductive Nb-doped strontium titanate (Nb:SrTiO 3 ) substrates are evaluated as photoelectrodes for water splitting reaction under visible light. The films are characterized by X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron and atomic force microscopy, and ultraviolet-visible spectroscopy. Thin films with polycrystalline, oriented, or epitaxial structures are obtained depending on the substrate temperature and plasma composition. The band-gap energies of the films thus prepared are in the range 2.05-2.35 eV. Photoelectrochemical measurements reveal that the photoactivity of these films increases with the quality of film crystallization. The flat-band position of LaTiO x N y is found to change with pH of the reactant solution. Surface modification with colloidal IrO 2 is also demonstrated to result in a marked increase in photoactivity, with the modified epitaxial LaTiO x N y film exhibiting a photocurrent density of ca. 70 µA cm -2 at +1.0 V vs. Ag/AgCl at pH 4.5 in aqueous Na 2 SO 4 solution under irradiation at visible wavelengths (λ > 420 nm).

Determinations of IgG subclasses were made by electroimmunoassay and crossed immunoelectrophoresis, and Gm markers were typed in sera from seventeen patients with well-defined immunodeficiency diseases. Certain IgG subclass and Gm patterns were recognized in various diseases: IgG2 deficiency and homozygosity of Gm(4,5) in the cartilage-hair-hypoplasia syndrome, in the ataxia telangiectasia syndrome and in selective IgG subclass deficiency; and IgG3 deficiency and homozygosity of Gm(1,-5) in the Wiskott-Aldrich syndrome. The findings suggest a common structural or regulator gene defect in some immunodeficiency diseases. In IgA deficiencies, the levels of IgG1 were raised. In patients with IgG subclass deficiencies there was sometimes a compensatory increase of the remaining IgG subclasses, with a preponderance of IgG1 and IgG3. The increased IgGI showed restricted heterogeneity with only an increase ofthe electrophoretically cathodal part. This part contained both kappa and lambda chains. IgG subclass deficiency indicates treatment with gammaglobulin even if the serum levels of IgG are normal or increased.

Biological debris between modular components using Morse tapers in hip arthroplasty can lead to weakening of the implant construct. We conducted a study to determine the effect of blood and fat within the taper interface. Tapers were divided into groups 1 (clean), 2 (surface covered with blood and fat), and 3 (blood and fat wiped off). Each taper was impacted and disassembled 5 times. There was a difference in mean disassembly force between pulls within group 2. Thus, blood and fat contamination can have a significant effect on the potential for disassembly.

Lithium titanate spinel (Li 4 Ti 5 O 12 , or LTS) is receiving consideration as a nanopowder anode material for use in lithium-ion batteries. LTS has more positive working potential than traditional graphite anodes, and it does not react with electrolyte components. However, the main drawback of LTS powder is its poor interparticle electronic conductance that reduces the high-rate ability of the electrode. To improve this we have coated the surface of the LTS powder with a titanium nitride layer by atomic layer deposition (ALD). In situ infrared spectroscopy studies were conducted to confirm the attachment of the titanium precursor. The nitrogen content of films was measured by total nitrogen content testing. Transmission electron microscopy (TEM) micrographs confirmed the formation of a thin titanium nitride film around LTS particles by ALD. Finally, lithium cells with electrodes made of original and modified LTS nanopowders were assembled and tested.

This paper reports on the preparation of titanium (IV) oxide films via the improved atmospheric pressure barrier torch discharge (BTD) deposition. This approach is a modification of the atmospheric pressure glow discharges (APGDs) ranking among plasma enhanced chemical vapor deposition (PECVD) techniques. These methods are based on plasma-chemical reactions of the precursors' vapors occurring in the active plasma environment. The layers are produced in terms of heterogeneous recombination reactions of the high active species on the supporting surface. The major treated topic comprises the influence of the used support on the physical properties of the layers. A set of three different supports was used including quartz slides (nonconducting, dielectric), silicon discs (semi-conducting) and polished Ni sheets (conducting). Crystallographic structure, surface roughness, surface wettability and the film thickness were assessed and used as a set of physical properties to be discussed and compared for each of the films and mutually. In parallel the qualitative analysis of the emission spectra of the barrier torch discharge during the deposition process was also presented. Different conductive connection of plasma stream with the substrate crucially influences the temperature of this substrate. It has a direct effect mainly on the crystallinity and morphology of the films and also on the plasma parameters. This knowledge might be used as a tool for the optimization of deposition conditions. Photocatalytic functionality of the layers was quantified in a simple test based on the photocatalytic oxidation of Rhodamine B (C 28 H 31 ClN 2 O 3 ) under UV radiation.

In the past several years, there has been a trend in the sunscreen/ cosmetics industry to replace micron-sized titanium dioxide (TiO 2) particles with nanoscale materials. The increased use of nanoscale TiO 2 has resulted in questions about these and other nanoproducts. This study examines the effects of using nanoscale TiO 2 on ultraviolet (UV) attenuation in simple to complex sunscreen formulations. UV light attenuation, product stability, and potential damage to the skin barrier were examined with both nanoscale and microscale TiO 2 particles. Results indicate that none of the formulations decreased the barrier function of the skin and the best UV attenuation occurs when the TiO 2 particles are stabilized with a coating and evenly distributed such as with non-agglomerated coated nanoscale materials. This indicates that nanoscale TiO 2 may have better efficacy while lacking toxicity. Ré sumé Au cours des dernières années, nous avons constaté une tendance dans l'industrie solaire/cosmétique pour le remplacement des particules micron-taille de dioxyde de titane (TiO 2) avec des matériaux de nano-échelle. L'utilisation accrue des particules de TiO 2 l'échelle du nanométre a engendré des questions sur tous les produits contenant des matériaux nano-échelle. Cette étude examine les effets de l'utilisation de particule de TiO 2 a l'échelle du nanomètre sur l'atténuation des rayons UV dans les formulations de crème solaire simple et complexe. Nous avons étudié l'atténuation de la luminosité ultraviolet (UV), la stabilité du produit et les effets sur la fonction barrière de la peau, avec les particules de TiO 2 nano-échelle et micro-échelle. Les résultats indiquent que les particules a l'échelle du nanométre, enduits et non-aggloméré, fournissent une excellente atténuation UV, sans diminuer la fonction barrière de la peau. Ceci suggére que les particules de TiO 2 a l'échelle du nanométre ont une meilleure efficacité, sans poser des inquiétudes en ce qui concerne leur securité.

Phosphate-based glasses have been examined in many studies as a potential biomaterial for bone repair because of its degradation properties, which can be controlled and allow the release of various elements to promote osteogenic tissue growth. However most of these experiments studied either tertiary or quaternary glass systems. This study investigated a qinternary system that included titanium dioxide for degradation rate control and zinc that is considered to have a role in bone formation. Zinc and titanium phosphate glass discs of different compositions were melt synthesized and samples of each composition was tested for different physical, chemical and biological characteristics via density measurement, X-ray diffraction, differential thermal analysis, mass loss, ion release, scanning electron microscopy, biocompatibility studies via live/dead assays at three time points (day 1, 4, and 7). The results showed that the glass was amorphous and that the all thermal variables decreas...

Abstract: Many dental clinical implant studies have fo- cused on the success of endosseous implants with a variety of surface characteristics. Most of the surface alterations have been aimed at achieving greater bone-to-implant con- tact as determined histometrically at the light microscopic ...

The possibility of producing titanium alloy Ti ? 6Al ? 4V with minimal residual porosity from mixtures of elemental powders by the method of pressing and sintering without hot deformation during or after sintering was investigated. Various powder mixtures based on titanium and titanium hydride with alloying additions of either elemental powders having different particle sizes, or master alloys, were studied. It was shown that the synthesis of Ti ? 6Al ? 4V from mixtures of titanium hydride and master alloys is optimal with respect to the attainment of high relative density. In this case the sintered material has density up to 99%, homogeneous microstructure with relatively small (100-120 µm) ß-phase grains, and a low concentration of impurities, in particular oxygen, which provide a high level of mechanical properties s(ten = 970 MPa, d = 6%).

To propose a new surgical technique for fixing the nasal septum to the midline, for long term prevention of nasal obstruction, in secondary and select cases of primary septoplasty. Patterns of septal deformity, materials used for titanium plates, surgical results, symptom improvement, and surgical complications were investigated.

Alkaline phosphatase (ALP) is an enzyme thought to be important in the process of biomineralization. ALP promotes hydrolysis of phosphate containing substrates, produces orthophosphate and increases the uptake of calcium. ALP has been demonstrated recently to induce mineralization of collagen sheets in the animal body. Many factors are being investigated to try to increase the quantity of bone around dental implants. The aim of this study was an evaluation of the bone formation around dental implants used in conjunction with ALP extracted from calf intestine. Titanium plasma-sprayed implants were put for 30 min in glasses containing 5OOpg of ALP, and then inserted into the femoral articular surface of the knee joint. The implants were retrieved after 2,3, 4 and 8 weeks, and treated to obtain thin ground sections. The histological examination showed a higher quantity of bone trabeculae, and at 2 and 3 weeks, the presence of plump, elongated, highly stained, very active ALP-positive osteoblasts around the treated specimens. ALP seems, in the experimental conditions of this pilot study, to have a positive effect on bone formation around titanium plasma-sprayed implants. 0 1998 Elsevier Science Limited An increase in the bone quantity around dental implants would have, probably, a significant importance because ii: would be possible to shorten the healing time and the time necessary for the prosthetic reconstruction.

Advanced manufacturing approaches, including additive manufacturing (i.e., " 3D printing ") of metallic structures requires a change to qualification strategies. One approach, informed qualification, integrates modeling strategies to make predictions of material characteristics, including the prediction of tensile properties for given chemistries and microstructures. In this work, constitutive equations are developed and presented that can predict the yield strength of additively manufactured Ti-6Al-4V subjected to one of three different heat-treatments: a stress relief anneal in the aþb phase field; a hot isostatic press treatment in the aþb phase field; and a b-anneal. The equations are nominally identical, though different strengthening mechanisms are active according to subtle microstructural differences. To achieve an equation that can predict the yield strength of the material, it is also necessary to include an assessment of dramatic reduction in the tensile strength due to texture (i.e., a " knock-down " effect). This has been experimentally measured, and included in this paper. The resulting predictions of yield strength are generally within 5% of their experimentally measured values.

Titanium-zirconium based alloys containing a small amount of niobium were investigated in order to evaluate their possible use as biomedical materials. Zirconium, which belongs to the IVa group, is known to have good corrosion resistance and biocompatibility similar to titanium. As the titanium-zirconium system shows a complete solid solution, a wide variation of alloy design is available and large quantities of solid-solution hardening must be possible. Niobium, having a beta-phase stabilizing effect, was chosen as a ternary element in order to control desirably the microstructure. There have been no reports which suggest its harm to a living body. The alloys containing 2% or 3% niobium showed the highest hardness value after aging heat treatment at 773 K. In contrast to this, no alteration of hardness was seen in specimens aged at 1073 K. Through conventional X-ray diffractometry and in situ X-ray analysis using a hot stage, beta-phase precipitation in the A matrix was identified....

Bacteriorhodopsin (bR) is a membrane protein found in the archae Halobacterium salinarum. Here, we studied wild type bR and especially the triple mutant bR, 3Glu [E9Q/E194Q/E204Q], in combination with wide gap semiconductor TiO 2 for their suitability as efficient light harvester in solar cell. Our differential scanning calorimetry data show thermal robustness of bR wild type and 3Glu mutant, which make them good candidates as photosensitizer in solar cells. Molecular modeling indicates that binding of bR to the exposed oxygen atoms of anatase TiO 2 is favorable for electron transfer and directed by local, small distance interactions. A solar cell, based on bR wild type and bR triple mutant immobilized on nanocrystalline TiO 2 film was successfully constructed. The photocurrent density-photo voltage (J-V ) characteristics of bio-sensitized solar cell (BSSC), based on the wild type bR and 3Glu mutant adsorbed on nanocrystalline TiO 2 film electrode were measured. The results show that the 3Glu mutant displays better photoelectric performance compared to the wild type bR, giving a short-circuit photocurrent density (J SC ) of 0.09 mA/cm 2 and the open-circuit photovoltage (V OC ) 0.35 V, under an illumination intensity of 40 mW/cm 2 .

Plaque-induced lesions can produce peri-implant bone loss with ultimate implant loss. Although the peri-implant tissues seem to be more resistant than the periodontal ones to plaque and calculus, they can produce a more extensive spread of the infection to the deeper tissues around implants. The case of a 45year-old female patient is presented in which, over a three year period, there was a progressive loss of peri-implant bone and the formation of a periapical radiolucency with an external fistula. The implant was removed and examined with the cutting-grinding system. Microscopy examination showed that most of the hydroxyapatite (HA) was still adherent to the metal. There was a detachment in the area of the HA-titanium interface. The implant surface was almost completely covered by bacteria. Bacteria were also present in the bone medullary spaces surrounding the implant. The infection of the periodontal tissues had progressed into the alveolar bone, thus producing a localized bone infection. The cause of the implant failure is probably related to a defective connection of the abutment or to overloading of the implant due to the presence of interlocks in the prosthetic restoration.

Cell attachment and spreading to titanium-based alloy surfaces is a major parameter in implant technology. In this paper, substratum surface hydrophobicity, surface free energy, interfacial free energy and surface roughness were investigated to ascertain which of these parameters is predominant in human fibroblast spreading. Two methods for contact angle measurement were compared: the sessile drop method and the captive bubble two-probe method. The relationship between surface roughness and the sessile drop contact angles of various engineered titanium surfaces such as commercial pure titanium (cp-Ti), titanium -aluminium -vanadium alloy (Ti -6Al -4V), and titaniumnickel (NiTi), was shown. Surface free energy (SFE) calculations were performed from contact angles obtained on smooth samples based on the same alloys in order to eliminate the roughness effect. SFE of the surfaces have been calculated using the Owens -Wendt (OW) and Van Oss (VO) approaches with the sessile drop method. The OW calculations are used to obtain the dispersive (c d ) and polar (c p ) component of SFE, and the VO approach allows to reach the apolar (c LW ) and the polar acid -base component (c ab ) of the surface. From captive bubble contact angle experiments (air or octane bubble under water), the interfacial free energy of the different surfaces in water was obtained. A relationship between cell spreading and the polar component of SFE was found. Interfacial free energy values were low for all the investigated surfaces indicating good biocompatibility for such alloys. D

Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO 2 -based photocatalyst, Evonik-Degussa P-25. Low-temperature electron spin resonance (ESR) measurements performed on this material provided the first experimental evidence for the formation of oxygen vacancies (V o ), which were also found responsible for the visible-light absorption. The V o surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO 2 particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO 2 surface often requires harsh technological conditions and complicated procedures, such as annealing at high temperatures, radio-frequencyinduced plasma or ion sputtering.

In recent years, Ti-Zr-Nb alloys have become increasingly attractive as biomedical implant materials. In the present communication, we report the formation of self-organized nanotube oxide layers on a Ti-28Zr-8Nb biomedical alloy surface in 1 M (NH 4 ) 2 SO 4 containing 0.25 M NH 4 F. The morphology of the nanotube layers (the diameter and the length) is affected by the electrochemical conditions used (applied potential and time). Under specific conditions oxide layers consisting of highly ordered nanotubes with a wide range of diameters and lengths can be formed, varying, respectively, from approx. 50 to 300 nm and from approx. 500 nm to 22 lm. The present results are highly promising for this biomedical alloy, as the large surface area and the tunable nanoscale geometry of the surface oxide provide novel pathways for the interaction of the materials with biorelevant species, such as cells and proteins.

Bone remodeling due to stress-shielding has been studied using a model system consisting of metal-polymer laminated fixation plates securely fixed to canine femurs. The plate stiffness was controlled by varying the ratio of metal facing to polymer core thickness in the laminate design while secure fixation to bone was achieved by providing a porous bone interfacing surface for the ingrowth of bone from the periosteal sur-face. Observations of laterally and medially placed plates indicated resorption in the area of the periosteal and endosteal bone surfaces respectively, for the higher stiffness composite plates used. The results indicate that plate stiffness greater than approximately 70 GPa (axial) and 6 N m2 (flexural) will result in extensive bone remodeling in the canine femur after a six month implantation period.

We generated, on titanium surfaces, self-assembled layers of vertically oriented TiO 2 nanotubes with defined diameters between 15 and 100 nm and show that adhesion, spreading, growth, and differentiation of mesenchymal stem cells are critically dependent on the tube diameter. A spacing less than 30 nm with a maximum at 15 nm provided an effective length scale for accelerated integrin clustering/focal contact formation and strongly enhances cellular activities compared to smooth TiO 2 surfaces. Cell adhesion and spreading were severely impaired on nanotube layers with a tube diameter larger than 50 nm, resulting in dramatically reduced cellular activity and a high extent of programmed cell death. Thus, on a TiO 2 nanotube surface, a lateral spacing geometry with openings of 30−50 nm represents a critical borderline for cell fate.

Topographically and chemically modified titanium implants are recognized to have improved osteogenic properties; however, the molecular regulation of this process remains unknown. This study aimed to determine the microRNA profile and the potential regulation of osteogenic differentiation following early exposure of osteoprogenitor cells to sand-blasted, large-grit acid-etched (SLA) and hydrophilic SLA (mod-SLA) surfaces. Firstly, the osteogenic characteristics of the primary osteoprogenitor cells were confirmed using ALP activity and Alizarin Red S staining. The effect of smooth (SMO), SLA and modSLA surfaces on the TGF-b/BMP (BMP2, BMP6, ACVR1) and non-canonical WNT/Ca 2+ (WNT5A, FZD6) pathways, as well as the integrins ITGB1 and ITGA2, was determined. It was revealed that the modified titanium surfaces could induce the activation of TGF-b/BMP and non-canonical WNT/Ca 2+ signaling genes. The expression pattern of microRNAs (miRNAs) related to cell differentiation was evaluated. Statistical analysis of the differentially regulated miRNAs indicated that 35 and 32 miRNAs were down-regulated on the modSLA and SLA surfaces respectively, when compared with the smooth surface (SMO). Thirty-one miRNAs that were down-regulated were common to both modSLA and SLA. There were 10 miRNAs up-regulated on modSLA and nine on SLA surfaces, amongst which eight were the same as observed on modSLA. TargetScan predictions for the down-regulated miRNAs revealed genes of the TGF-b/BMP and non-canonical Ca 2+ pathways as targets. This study demonstrated that modified titanium implant surfaces induce differential regulation of miRNAs, which potentially regulate the TGF-b/BMP and WNT/Ca 2+ pathways during osteogenic differentiation on modified titanium implant surfaces.

h i g h l i g h t s We have studied the hydrated hydroxyl silicate mineral inesite. Of formula Ca 2 (Mn,Fe) 7 Si 10 O 28 (OH)Á5H 2 O. Using a combination of scanning electron microscopy with EDX and Raman and infrared spectroscopy. OH stretching vibrations are readily studied. The application of vibrational spectroscopy has enabled an assessment of the molecular structure of inesite.

This study investigated the concept of using plates to attach endoprostheses to bone after segmental resection for bone tumours in an animal model. Titanium alloy plates integrated with the prosthesis and coated with hydroxyapatite were attached to bone by screws. This type of uncemented fixation relied on the induction of periosteal bone formation into and around the plates to secure the implant to bone. Tow, three, and six-slotted plate designs were investigated. On retrieval, each plate was securely fixed by new bone. Bone apposition on the external surface of the plates occurred through a combination of periosteal bone production, invasion of bone through slots in the plate, and bone growth over the ends of the plates. Most plates became incorporated into a remodelled cortex. Higher bone turnover rates (μm day−1) were seen in bone in the slots of the plate compared with normal cortical bone turnover (p < 0.05). Significantly higher rates of turnover were measured beneath slotted parts of the plates compared with regions below the unslotted parts (p < 0.05). The cross-sectional area of bone surrounding the six-plate implant design was significantly higher than that of the three-plate (p < 0.05) and two-plate (p < 0.05) designs. In addition, significantly more bone formed adjacent to the six-plated implant design compared with that in the contralateral limb (p = 0.002). However, no significant difference was found when the total cortical area around the three-plated design was compared with that of the contralateral limb (p = 0.63). In contrast, significantly less bone was measured adjacent to the two-plate design than in the untreated limb (p = 0.001). Image analysis also demonstrated increased cortical porosity adjacent to the six-plate design compared with the three-plate (p = 0.004) and two-plate (p < 0.05) designs. Finite element analysis demonstrated that the six and three-plate designs increased the second moment of area compared with that in the left tibia (p = 0.003 and 0.066, respectively). However, the attachment of the more flexible two-plate design did not significantly increase the second moment of area compared with that in the contralateral limb (p = 0.235). It was concluded that due to both mechanical and biological effects, the hydroxyapatite-coated plate designs generated new bone that enhanced fixation and encouraged plate integration into the load-bearing structure of the cortex. This method of fixation may be an alternative to the use of intramedullary cemented stems in patients requiring bone tumour implants and may be the only way to preserve the joint in difficult cases where only short segments of bone remain.

Introduction: Accurate tumour bed (TB) localisation is a key requirement for the UK IMPORT (Intensity Modulated Partial Organ Radiotherapy) trial. We audited the value of titanium clips for TB localisation following breast conserving surgery (BCS) in breast radiotherapy (RT) planning. Patients and methods: At surgery, paired clips were positioned around the TB as follows: 1. Medial, lateral, superior and inferior: half-way between skin and fascia; 2. Posterior: at the pectoral fascia; 3. Anterior: close to the suture line. Thirty consecutive patients with clips inserted were audited at the time of RT planning. Audit standards were set as follows: (i) 5/6 pairs of clips identified on RT planning computed tomography (CT) scan e 100%; (ii) possible clip migration: <10%; (iii) TB localisation improved with clips: >50%. Inter-and intraobserver variability in clinician outlining of the TB was studied in a subset of 12 randomly selected patients to see if this impacted on positioning of radiotherapy field borders. Results: Five or six pairs of clips were identified in all 30 cases. The TB could be successfully identified using CT seroma alone in only 8/30 (27%) patients. Clips were essential for the TB localisation of the other 22/30 (73%) patients. There was no evidence of clip migration. TB localisation led to modified RT field borders in 18/30 (60%) patients. Five of these patients had highly visible seromas, so the addition of clips modified field borders in 13/30 (43%) patients. Both inter-and intra-observer variability was reasonable and did not impact on positioning of radiotherapy field borders. Conclusion: Titanium clips provide an accurate and reliable method of TB localisation following BCS. We anticipate that the audit results will lead to clips being adopted as best practice by the Association of Breast Surgeons (ABS) at BASO (British Association of Surgical Oncology).

Objective. Biodegradable materials are particularly useful for the fixation of zygomatic fractures. Different systems are commercially available. The aim of this study was to compare the clinical outcome of zygomatic fracture fixation using 3 biodegradable systems and a titanium osteosynthesis system. Study design. Patients with displaced fractures of the zygomatic bone presenting at our department from October 2001 to May 2003 were randomly allocated to 1 of 3 treatment groups for fracture fixation (study group A: LactoSorb: n = 18; study group B: BioSorb: n = 18; study group C: Delta: n = 18). Treatment outcome and complication rates were compared with a historic patient group with zygomatic fractures fixed with titanium osteosynthesis (control group D: n = 15).

Titanium is known as the metal of the future because of its excellent combination of properties such as high specific strength, low thermal conductivity, and high corrosion resistance. There is a critical need for developing and establishing cost-effective methods for the machining of titanium, especially in terms of tool-wear optimization. This paper addresses the application of ultrasonic machining, an impact machining process for the cost-effective machining of commercially pure titanium (ASTM Grade-I) and evaluation of tool-wear rate under the effect of different process parameters. Tool material, abrasive material, slurry concentration, abrasive grit size, and power rating of the ultrasonic machine were included as the input factors in this investigation. The optimal settings of these parameters were determined through experiments planned, conducted, and analyzed using the Taguchi method. The significant parameters contributing most to the variation in tool-wear rate were identified and the results obtained were validated by conducting the confirmation experiments. Thereafter, the outcome of the Taguchi model has been used for developing a micro-model for tool-wear rate (TWR); using Buckingham's pie theorem. A comparison of the experi-mental results obtained assists in the validation of the model.

+)-Isoretronecanol (1) has been prepared in four steps and 36% overall yield via the diastereoselective addition of the titanium(IV) enolate derived from N-4-chlorobutyryl-1,3-thiazolidine-2-thione (3) to N-Boc-2-methoxypyrrolidine (5), which afforded 2-substituted pyrrolidine 7 in 84% yield (8:1 diastereoisomeric ratio), followed by reductive recovery of the chiral auxiliary and cyclization.

In this work, we describe a kinetically controlled crystallization process assisted by an oriented attachment (OA) mechanism based on a nonaqueous sol-gel synthetic method (specifically, the reaction of titanium(IV) chloride (TiCl 4 ) with n-octanol) to prepare re-crystallized anatase TiO 2 mesocrystals (single crystal). The kinetics study revealed a multi-step and hierarchical process controlled by OA, and a high resolution transmission electron microscopy (HRTEM) analysis clearly shows that the synthesized mesocrystal presents a truncated bipyramidal Wulff shape, indicating that its surface is dominated by {101} facets. This shape is developed during the recrystallization step. The material developed here displayed superior photocatalytic activity under visible light irradiation compared to TiO 2 -P25 as a benchmarking.