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Sample records for nanostructured neodymium titanium

  1. Titanium nanostructures for biomedical applications.

    PubMed

    Kulkarni, M; Mazare, A; Gongadze, E; Perutkova, Š; Kralj-Iglič, V; Milošev, I; Schmuki, P; A Iglič; Mozetič, M

    2015-02-13

    Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO2) nanotubes, using a simple electrochemical anodisation method of the metallic substrate and other processes such as the hydrothermal or sol-gel template. One key advantage of using TiO2 nanotubes in cell interactions is based on the fact that TiO2 nanotube morphology is correlated with cell adhesion, spreading, growth and differentiation of mesenchymal stem cells, which were shown to be maximally induced on smaller diameter nanotubes (15 nm), but hindered on larger diameter (100 nm) tubes, leading to cell death and apoptosis. Research has supported the significance of nanotopography (TiO2 nanotube diameter) in cell adhesion and cell growth, and suggests that the mechanics of focal adhesion formation are similar among different cell types. As such, the present review will focus on perhaps the most spectacular and surprising one-dimensional structures and their unique biomedical applications for increased osseointegration, protein interaction and antibacterial properties. PMID:25611515

  2. Titanium nanostructures for biomedical applications

    NASA Astrophysics Data System (ADS)

    Kulkarni, M.; Mazare, A.; Gongadze, E.; Perutkova, Š.; Kralj-Iglič, V.; Milošev, I.; Schmuki, P.; Iglič, A.; Mozetič, M.

    2015-02-01

    Titanium and titanium alloys exhibit a unique combination of strength and biocompatibility, which enables their use in medical applications and accounts for their extensive use as implant materials in the last 50 years. Currently, a large amount of research is being carried out in order to determine the optimal surface topography for use in bioapplications, and thus the emphasis is on nanotechnology for biomedical applications. It was recently shown that titanium implants with rough surface topography and free energy increase osteoblast adhesion, maturation and subsequent bone formation. Furthermore, the adhesion of different cell lines to the surface of titanium implants is influenced by the surface characteristics of titanium; namely topography, charge distribution and chemistry. The present review article focuses on the specific nanotopography of titanium, i.e. titanium dioxide (TiO2) nanotubes, using a simple electrochemical anodisation method of the metallic substrate and other processes such as the hydrothermal or sol-gel template. One key advantage of using TiO2 nanotubes in cell interactions is based on the fact that TiO2 nanotube morphology is correlated with cell adhesion, spreading, growth and differentiation of mesenchymal stem cells, which were shown to be maximally induced on smaller diameter nanotubes (15 nm), but hindered on larger diameter (100 nm) tubes, leading to cell death and apoptosis. Research has supported the significance of nanotopography (TiO2 nanotube diameter) in cell adhesion and cell growth, and suggests that the mechanics of focal adhesion formation are similar among different cell types. As such, the present review will focus on perhaps the most spectacular and surprising one-dimensional structures and their unique biomedical applications for increased osseointegration, protein interaction and antibacterial properties.

  3. Array of titanium dioxide nanostructures for solar energy utilization

    DOEpatents

    Qiu, Xiaofeng; Parans Paranthaman, Mariappan; Chi, Miaofang; Ivanov, Ilia N; Zhang, Zhenyu

    2014-12-30

    An array of titanium dioxide nanostructures for solar energy utilization includes a plurality of nanotubes, each nanotube including an outer layer coaxial with an inner layer, where the inner layer comprises p-type titanium dioxide and the outer layer comprises n-type titanium dioxide. An interface between the inner layer and the outer layer defines a p-n junction.

  4. Titanium nanostructural surface processing for improved biocompatibility

    SciTech Connect

    Cheng, H.-C.; Lee, S.-Y.; Chen, C.-C.; Shyng, Y.-C.; Ou, K.-L.

    2006-10-23

    X-ray photoelectron spectroscopy, grazing incident x-ray diffraction, transmission electron microscopy, and scanning electron microscopy were conducted to evaluate the effect of titanium hydride on the formation of nanoporous TiO{sub 2} on Ti during anodization. Nano-titanium-hydride was formed cathodically before anodizing and served as a sacrificial nanoprecipitate during anodization. Surface oxidation occurred and a multinanoporous structure formed after cathodic pretreatments followed by anodization treatment. The sacrificial nanoprecipitate is directly dissolved and the Ti transformed to nanoporous TiO{sub 2} by anodization. The formation of sacrificial nanoprecipitates by cathodic pretreatment and of the multinanostructure by anodization is believed to improve biocompatibility, thereby promoting osseointegration.

  5. Bi-phasic titanium dioxide nanoparticles doped with nitrogen and neodymium for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Gomez, Virginia; Bear, Joseph C.; McNaughter, Paul D.; McGettrick, James D.; Watson, Trystan; Charbonneau, Cecile; O'Brien, Paul; Barron, Andrew R.; Dunnill, Charles W.

    2015-10-01

    Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co-doped particles under white light.Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co

  6. Surface Engineering of Nanostructured Titanium Implants with Bioactive Ions.

    PubMed

    Kim, H-S; Kim, Y-J; Jang, J-H; Park, J-W

    2016-05-01

    Surface nanofeatures and bioactive ion chemical modification are centrally important in current titanium (Ti) oral implants for enhancing osseointegration. However, it is unclear whether the addition of bioactive ions definitively enhances the osteogenic capacity of a nanostructured Ti implant. We systematically investigated the osteogenesis process of human multipotent adipose stem cells triggered by bioactive ions in the nanostructured Ti implant surface. Here, we report that bioactive ion surface modification (calcium [Ca] or strontium [Sr]) and resultant ion release significantly increase osteogenic activity of the nanofeatured Ti surface. We for the first time demonstrate that ion modification actively induces focal adhesion development and expression of critical adhesion–related genes (vinculin, talin, and RHOA) of human multipotent adipose stem cells, resulting in enhanced osteogenic differentiation on the nanofeatured Ti surface. It is also suggested that fibronectin adsorption may have only a weak effect on early cellular events of mesenchymal stem cells (MSCs) at least in the case of the nanostructured Ti implant surface incorporating Sr. Moreover, results indicate that Sr overrides the effect of Ca and other important surface factors (i.e., surface area and wettability) in the osteogenesis function of various MSCs (derived from human adipose, bone marrow, and murine bone marrow). In addition, surface engineering of nanostructured Ti implants using Sr ions is expected to exert additional beneficial effects on implant bone healing through the proper balancing of the allocation of MSCs between adipogenesis and osteogenesis. This work provides insight into the future surface design of Ti dental implants using surface bioactive ion chemistry and nanotopography. PMID:26961491

  7. Improving Osteoblast Response In Vitro by a Nanostructured Thin Film with Titanium Carbide and Titanium Oxides Clustered around Graphitic Carbon

    PubMed Central

    Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d’Abusco, Anna; Superti, Fabiana; Misiano, Carlo; Zanoni, Robertino; Politi, Laura; Mazzola, Luca; Iosi, Francesca; Mura, Francesco; Scandurra, Roberto

    2016-01-01

    Introduction Recently, we introduced a new deposition method, based on Ion Plating Plasma Assisted technology, to coat titanium implants with a thin but hard nanostructured layer composed of titanium carbide and titanium oxides, clustered around graphitic carbon. The nanostructured layer has a double effect: protects the bulk titanium against the harsh conditions of biological tissues and in the same time has a stimulating action on osteoblasts. Results The aim of this work is to describe the biological effects of this layer on osteoblasts cultured in vitro. We demonstrate that the nanostructured layer causes an overexpression of many early genes correlated to proteins involved in bone turnover and an increase in the number of surface receptors for α3β1 integrin, talin, paxillin. Analyses at single-cell level, by scanning electron microscopy, atomic force microscopy, and single cell force spectroscopy, show how the proliferation, adhesion and spreading of cells cultured on coated titanium samples are higher than on uncoated titanium ones. Finally, the chemistry of the layer induces a better formation of blood clots and a higher number of adhered platelets, compared to the uncoated cases, and these are useful features to improve the speed of implant osseointegration. Conclusion In summary, the nanostructured TiC film, due to its physical and chemical properties, can be used to protect the implants and to improve their acceptance by the bone. PMID:27031101

  8. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  9. Yield stress and plasticity of nanostructured titanium of different purity at 300, 77, and 4.2 K

    SciTech Connect

    Tabachnikova, E. D. Bengus, V. Z.; Podol'skii, A. V.; Smirnov, S. N.; Valiev, R. Z.

    2009-11-15

    Specimens of nanostructured titanium with different dopant concentrations were prepared by intense plastic deformation via equal-channel-angular pressing. The low-temperature mechanical characteristics of the specimens subjected to active deformation under uniaxial tension and compression were studied. The yield stress and the limit uniform deformation of nanostructured and coarse-grained polycrystalline titanium were compared.

  10. A low-cost hierarchical nanostructured beta-titanium alloy with high strength

    NASA Astrophysics Data System (ADS)

    Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

    2016-04-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti-1Al-8V-5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications.

  11. Pyrolytic deposition of nanostructured titanium carbide coatings on the surface of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kremlev, K. V.; Ob"edkov, A. M.; Ketkov, S. Yu.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.; Tatarskii, D. A.; Yunin, P. A.

    2016-05-01

    Nanostructured titanium carbide coatings have been deposited on the surface of multiwalled carbon nanotubes (MWCNTs) by the MOCVD method with bis(cyclopentadienyl)titanium dichloride precursor. The obtained TiC/MWCNT hybrid materials were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. It is established that a TiC coating deposits onto the MWCNT surface with the formation of a core-shell (MWSNT-TiC) type structure.

  12. Patterning of titanium oxide nanostructures by electron-beam lithography combined with plasma etching

    NASA Astrophysics Data System (ADS)

    Hotovy, I.; Kostic, I.; Nemec, P.; Predanocy, M.; Rehacek, V.

    2015-07-01

    Patterning of metal oxide nanostructures with precisely controlled geometries and spacings can play an important role in the improvement of sensors for gas detection. Titanium oxide thin films were deposited on oxidized silicon substrates by reactive magnetron sputtering at room temperature. Patterning of TiO2 nanostructures was conducted by electron beam lithography combined with plasma etching. It was found that for 120 nm-thick TiO2 nanostructure formation, HSQ e-beam resists and Cr films prove to be suitable mask materials. Experimental results showed that the size of TiO2 nanostructures depends mainly on the e-beam lithography process and they can be controlled by the design geometry and the exposure dose. TiO2 nanostructures with a minimal diameter of 70 nm and spacing of 200 nm were successfully fabricated by ICP etching in CF4/Ar plasma through negative e-beam resist HSQ.

  13. NOVEL EMBEDDED CERAMIC ELECTRODE SYSTEM TO ACTIVATE NANOSTRUCTURED TITANIUM DIOXIDE FOR DEGRADATION OF MTBE

    EPA Science Inventory

    A novel reactor combining a flame-deposited nanostructured titanium dioxide film and a set of embedded ceramic electrodes was designed, developed and tested for degradation of methyl tert-butyl ether (MTBE) in water. On applying a voltage to the ceramic electrodes, a surface coro...

  14. Titanium Surfaces with Nanostructures Influence on Osteoblasts Proliferation: a Systematic Review

    PubMed Central

    Juodzbalys, Gintaras; Vilkinis, Valdas

    2014-01-01

    ABSTRACT Objectives Nanothechnology found to be increasingly implemented in implantology sphere over the recent years and it shows encouraging effect in this field. The aim of present review is to compare, based on the recent evidence, the influence of various nanostructure surface modifications of titanium for implants, on osteoblasts proliferation. Material and Methods A literature review of English articles was conducted by using MEDLINE database restricted to 2009 - 2014 and constructed according PRISMA guidelines. Search terms included “Titanium implant”, “Titanium surface with nanostructure”, “Osteoblast”. Additional studies were identified in bibliographies. Only in vitro and/or in vivo studies on nano structured implant surfaces plus control sample, with specific evaluation method for osteoblasts proliferation and at least one Ti sample with nanostructure, were included in the review. Results 32 studies with 122 groups of examined samples were selected for present review. Each study conducted in vitro experiment, two studies conducted additional in vivo experiments. All studies were dispensed by type of surface modification into two major groups; “Direct ablative titanium implant surface nano-modifications” with 19 studies and ”Nanocomposite additive implant surface modifications” with 13 studies. Overall 24 studies reporting on positive effect of nanostructured surface, 2 studies found no significant advantage and 6 studies reported on negative effect compared to other structure scales. Conclusions From examination of selected articles we can notice marked advantage in implementation of various nanostructures onto implant surface. Yet for discovering the ultimate implant surface nanostructure, further comparable investigations of Ti surface nanostructures need to be done. PMID:25386228

  15. Femtosecond laser induced periodic nanostructures on titanium dioxide film for improving biocompatibility

    NASA Astrophysics Data System (ADS)

    Shinonaga, T.; Horiguchi, N.; Tsukamoto, M.; Nagai, A.; Yamashita, K.; Hanawa, T.; Matsushita, N.; Guoqiang, X.; Abe, N.

    2013-03-01

    Periodic nanostructures formation on Titanium dioxide (TiO2) film by scanning of femtosecond laser beam spot at fundamental and second harmonic wave is reported. Titanium (Ti) is one of the most widely used for biomaterials, because of its excellent anti-corrosion and high mechanical properties. However, Ti implant is typically artificial materials and has no biofunction. Hence, it is necessary for improving the bioactivity of Ti. Recently, coating of TiO2 film on Ti plate surface is useful methods to improve biocompatibility of Ti plate. Then, if periodic nanostructures were formed on the film surface, cell spreading might be controlled at one direction. We propose periodic nanostructures formation on TiO2 film by femtosecond laser irradiation. Cell spread could be controlled along the grooves of periodic nanostructures. In the experiments, the film was formed on Ti plate with an aerosol beam. A commercial femtosecond Ti : sapphire laser system was employed in our experiments. Periodic nanostructures, lying perpendicular to the laser electric field polarization vector, were formed on the film at fundamental and second harmonic wave. Periodic nanostructures were also produced on Ti plate with femtosecond laser. The period of periodic nanostructures on the film was much shorter than that on Ti plate. By cell test, there was a region of cell spreading along the grooves of periodic nanostructures on the film formed with femtosecond laser at fundamental wave. On bare film surface, cell spreading was observed at all direction. These results suggest that direction of cell spread could be controlled by periodic nanostructures formation on the film.

  16. Greater osteoblast and endothelial cell adhesion on nanostructured polyethylene and titanium

    PubMed Central

    Raimondo, Theresa; Puckett, Sabrina; Webster, Thomas J

    2010-01-01

    Mostly due to desirable mechanical properties (such as high durability and low wear), certain synthetic polymers (such as polyethylene) and metals (such as titanium) have found numerous applications in the medical device arena from orthopedics to the vasculature, yet frequently, they do not proactively encourage desirable cell responses. In an effort to improve the efficacy of such traditional materials for various implant applications, this study used electron beam evaporation to create nanostructured surface features that mimic those of natural tissue on polyethylene and titanium. For other materials, it has been shown that the creation of nanorough surfaces increases surface energy leading to greater select protein (such as vitronectin and fibronectin) interactions to increase specific cell adhesion. Here, osteoblast (bone forming cells) and endothelial cell (cells that line the vasculature) adhesion was determined on nanostructured compared to conventional, nano-smooth polyethylene and titanium. Results demonstrated that nanorough surfaces created by electron beam evaporation increased the adhesion of both cells markedly better than conventional smooth surfaces. In summary, this study provided evidence that electron beam evaporation can modify implant surfaces (specifically, polyethylene and titanium) to have nanostructured surface features to improve osteoblast and endothelial cell adhesion. Since the adhesion of anchorage dependent cells (such as osteoblasts and endothelial cells) is a prerequisite for their long-term functions, this study suggests that electron beam evaporation should be further studied for improving materials for various biomedical applications. PMID:20856840

  17. Nanostructures and Lithium Electrochemical Reactivity of Lithium Titanites and Titanium Oxides: A Review

    SciTech Connect

    Yang, Zhenguo; Choi, Daiwon; Kerisit, Sebastien N.; Rosso, Kevin M.; Wang, Donghai; Zhang, Jiguang; Graff, Gordon L.; Liu, J.

    2009-07-15

    Being inherently safe and chemically compatible with the electrolyte, titanium oxidebased materials, including both Li-titanites and various TiO2-polymorphs, are considered alternatives to carbonaceous anodes in Li-ion batteries. Given the commercial success of the spinel lithium titanites, TiO2-polymorphs, in particular in nanostructured forms, have been fabricated and investigated for the applications. Nanostructuring leads to increased reaction areas, shortened Li+ diffusion and potentially enhanced solubility/capacity. Integration with an electron conductive second phase into the TiO2-based nanostructures eases the electron transport, resulting in further improved lithium electrochemical activity and the overall electrochemical performance. This paper reviews structural characteristics and Li-electrochemical reactivity, along with synthetic approaches, of nanostructures and nano-composites based on lithium titanites and TiO2-polymorphs that include rutile, anatase, bronze and brookite.

  18. Antibacterial and bioactive nanostructured titanium surfaces for bone integration

    NASA Astrophysics Data System (ADS)

    Ferraris, S.; Venturello, A.; Miola, M.; Cochis, A.; Rimondini, L.; Spriano, S.

    2014-08-01

    An effective and physiological bone integration and absence of bacterial infection are essential for a successful orthopaedic or dental implant. A titanium surface able to actively promote bone bonding and avoid microbial colonization represents an extremely interesting challenge for these purposes. An innovative and patented surface treatment focused on these issues is described in the present paper. It is based on acid etching and subsequent controlled oxidation in hydrogen peroxide, enriched with silver ions. It has been applied to commercially pure titanium (Ti-cp) and alloy Ti6Al4V. The chemistry and morphology of the surfaces are modified by the treatment on a nanoscale: they show a thin oxide layer with porosity on the nanoscale and silver particles (few nanometers in diameter), embedded in it. These features are effective in order to obtain antibacterial and bioactive titanium surfaces.

  19. Formation of periodic nanostructures using a femtosecond laser to control cell spreading on titanium

    NASA Astrophysics Data System (ADS)

    Shinonaga, T.; Tsukamoto, M.; Kawa, T.; Chen, P.; Nagai, A.; Hanawa, T.

    2015-06-01

    Although titanium (Ti) is a common biomaterial, controlling cell spreading by forming periodic structures using a femtosecond laser should improve its biocompatibility. Herein we investigate the influence of periodic nanostructures formed on the surface of a Ti plate on cell spreading. Nanostructures with a periodicity of 590 nm are formed using a femtosecond laser with a wavelength of 775 nm. Cell spreading on the plate without period structures lacks a definite direction, whereas cell spreading on the Ti plate with periodic structures occurs along the grooves, suggesting that forming periodic structures via a femtosecond laser can control cell spreading.

  20. Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

    PubMed Central

    2012-01-01

    Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors. PMID:22731888

  1. Selective growth of palladium and titanium dioxide nanostructures inside carbon nanotube membranes

    NASA Astrophysics Data System (ADS)

    Hevia, Samuel; Homm, Pía; Cortes, Andrea; Núñez, Verónica; Contreras, Claudia; Vera, Jenniffer; Segura, Rodrigo

    2012-06-01

    Hybrid nanostructured arrays based on carbon nanotubes (CNT) and palladium or titanium dioxide materials have been synthesized using self-supported and silicon-supported anodized aluminum oxide (AAO) as nanoporous template. It is well demonstrated that carbon nanotubes can be grown using these membranes and hydrocarbon precursors that decompose at temperatures closer to 600°C without the use of a metal catalyst. In this process, carbonic fragments condensate to form stacked graphitic sheets, which adopt the shape of the pores, yielding from these moulds' multi-walled carbon nanotubes. After this process, the ends of the tubes remain open and accessible to other substances, whereas the outer walls are protected by the alumina. Taking advantage of this fact, we have performed the synthesis of palladium and titanium dioxide nanostructures selectively inside carbon nanotubes using these CNT-AAO membranes as nanoreactors.

  2. A low-cost hierarchical nanostructured beta-titanium alloy with high strength.

    PubMed

    Devaraj, Arun; Joshi, Vineet V; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A; Lavender, Curt

    2016-01-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti-1Al-8V-5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications. PMID:27034109

  3. A low-cost hierarchical nanostructured beta-titanium alloy with high strength

    PubMed Central

    Devaraj, Arun; Joshi, Vineet V.; Srivastava, Ankit; Manandhar, Sandeep; Moxson, Vladimir; Duz, Volodymyr A.; Lavender, Curt

    2016-01-01

    Lightweighting of automobiles by use of novel low-cost, high strength-to-weight ratio structural materials can reduce the consumption of fossil fuels and in turn CO2 emission. Working towards this goal we achieved high strength in a low cost β-titanium alloy, Ti–1Al–8V–5Fe (Ti185), by hierarchical nanostructure consisting of homogenous distribution of micron-scale and nanoscale α-phase precipitates within the β-phase matrix. The sequence of phase transformation leading to this hierarchical nanostructure is explored using electron microscopy and atom probe tomography. Our results suggest that the high number density of nanoscale α-phase precipitates in the β-phase matrix is due to ω assisted nucleation of α resulting in high tensile strength, greater than any current commercial titanium alloy. Thus hierarchical nanostructured Ti185 serves as an excellent candidate for replacing costlier titanium alloys and other structural alloys for cost-effective lightweighting applications. PMID:27034109

  4. Enhanced osseointegration of titanium implants with nanostructured surfaces: an experimental study in rabbits.

    PubMed

    Salou, Laëtitia; Hoornaert, Alain; Louarn, Guy; Layrolle, Pierre

    2015-01-01

    Titanium and its alloys are commonly used for dental implants because of their good mechanical properties and biocompatibility. The surface properties of titanium implants are key factors for rapid and stable bone tissue integration. Micro-rough surfaces are commonly prepared by grit-blasting and acid-etching. However, proteins and cells interact with implant surfaces in the nanometer range. The aim of this study was to compare the osseointegration of machined (MA), standard alumina grit-blasted and acid-etched (MICRO) and nanostructured (NANO) implants in rabbit femurs. The MICRO surface exhibited typical random cavities with an average roughness of 1.5 μm, while the NANO surface consisted of a regular array of titanium oxide nanotubes 37±11 nm in diameter and 160 nm thick. The MA and NANO surfaces had a similar average roughness of 0.5 μm. The three groups of implants were inserted into the femoral condyles of New Zealand White rabbits. After 4 weeks, the pull-out test gave higher values for the NANO than for the other groups. Histology corroborated a direct apposition of bone tissue on to the NANO surface. Both the bone-to-implant contact and bone growth values were higher for the NANO than for the other implant surfaces. Overall, this study shows that the nanostructured surface improved the osseointegration of titanium implants and may be an alternative to conventional grit-blasted and acid-etched surface treatments. PMID:25449926

  5. Tribocorrosion behaviour of nanostructured titanium substrates processed by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Faghihi, S.; Li, D.; Szpunar, J. A.

    2010-12-01

    Aseptic loosening induced by wear particles from artificial bearing materials is one of the main causes of malfunctioning in total hip replacements. With the increase in young and active patients, complications in revision surgeries and immense health care costs, there is considerable interest in wear-resistant materials that can endure longer in the harsh and corrosive body environment. Here, the tribological behaviour of nanostructured titanium substrates processed by high-pressure torsion (HPT) is investigated and compared with the coarse-grained samples. The high resolution transmission electron microscopy reveals that a nanostructured sample has a grain size of 5-10 nm compared to that of ~ 10 µm and ~ 50 µm for untreated and annealed substrates, respectively. Dry and wet wear tests were performed using a linear reciprocating ball-on-flat tribometer. Nanostructured samples show the best dry wear resistance and the lowest wear rate in the electrolyte. There was significantly lower plastic deformation and no change in preferred orientation of nanostructured samples attributable to the wear process. Electrochemical impedance spectroscopy (EIS) shows lower corrosion resistance for nanostructured samples. However, under the action of both wear and corrosion the nanostructured samples show superior performance and that makes them an attractive candidate for applications in which wear and corrosion act simultaneously.

  6. Biological insertion of nanostructured germanium and titanium oxides into diatom biosilica

    NASA Astrophysics Data System (ADS)

    Jeffryes, Clayton S.

    There is significant interest in titanium oxide and germanium-silicon oxide nanocomposites for optoelectronic, photocatalytic, and solar cell applications. The ability of the marine diatom Pinnularia sp. to uptake soluble metal oxides from cell culture medium, and incorporate them into the micro- and nano-structure of their amorphous silica cell walls, called frustules, was evaluated using an engineered photobioreactor system. The effects of metal oxides on the structural and elemental properties of the frustule were also evaluated. Diatom cell cultures grown in 5 L photobioreactors were initially charged with 0.5 mM of soluble silicon, Si(OH)4, an obligate substrate required for frustule fomation. Upon exhaustion of Si(OH)4 cells were exposed to the mixed pulse-addition of soluble silicon and germanium or co-perfusion addition of soluble silicon and titanium, which were incorporated into the frustules. Metals composition of the cell culture medium, diatom biomass and purified frustules were measured, as was the local elemental composition within the frustule pores and the metal oxide crystallinity. Diatom frustules having a germanium composition of 1.6 wt % were devoid of the native intra-pore structures and possessed enhanced photoluminescence and electroluminescence when compared to frustules without Ge. Diatoms cultivated in the presence of soluble titanium incorporated amorphous titania into the frustule, which maintained native structure even when local TiO2 concentrations within the nanopores approached 60 wt. %. Titanium oxide could also be biomimetically deposited directly within the diatom nanopores by adsorbing poly-L-lysine to the diatom biosilica where it catalyzed the soluble titanium precursor Ti-BALDH into amorphous titania nanoparticles. Both biogenic and biomimetic titania could be converted to anatase titanium by thermal annealing. It was determined that nanostructured metal oxide composites can be fabricated biomimetically or in cell culture to

  7. Nanostructured titanate with different metal ions on the surface of metallic titanium: a facile approach for regulation of rBMSCs fate on titanium implants.

    PubMed

    Ren, Na; Li, Jianhua; Qiu, Jichuan; Sang, Yuanhua; Jiang, Huaidong; Boughton, Robert I; Huang, Ling; Huang, Wei; Liu, Hong

    2014-08-13

    Titanium (Ti) is widely used for load-bearing bio-implants, however, it is bio-inert and exhibits poor osteo-inductive properties. Calcium and magnesium ions are considered to be involved in bone metabolism and play a physiological role in the angiogenesis, growth, and mineralization of bone tissue. In this study, a facile synthesis approach to the in situ construction of a nanostructure enriched with Ca(2+) and Mg(2+) on the surface of titanium foil is proposed by inserting Ca(2+) and Mg(2+) into the interlayers of sodium titanate nanostructures through an ion-substitution process. The characteriz 0.67, and 0.73 nm ation results validate that cations can be inserted into the interlayer regions of the layered nanostructure without any obvious change of morphology. The cation content is positively correlated to the concentration of the solutions employed. The biological assessments indicate that the type and the amount of cations in the titanate nanostructure can alter the bioactivity of titanium implants. Compared with a Na(+) filled titanate nanostructure, the incorporation of divalent ions (Mg(2+) , Ca(2+) ) can effectively enhance protein adsorption, and thus also enhance the adhesion and differentiation ability of rat bone-marrow stem cells (rBMSCs). The Mg(2+) /Ca(2+) -titanate nanostructure is a promising implantable material that will be widely applicable in artificial bones, joints, and dental implants. PMID:24706634

  8. Electrically controlled drug release from nanostructured polypyrrole coated on titanium

    NASA Astrophysics Data System (ADS)

    Sirivisoot, Sirinrath; Pareta, Rajesh; Webster, Thomas J.

    2011-02-01

    Previous studies have demonstrated that multi-walled carbon nanotubes grown out of anodized nanotubular titanium (MWNT-Ti) can be used as a sensing electrode for various biomedical applications; such sensors detected the redox reactions of certain molecules, specifically proteins deposited by osteoblasts during extracellular matrix bone formation. Since it is known that polypyrrole (PPy) can release drugs upon electrical stimulation, in this study antibiotics (penicillin/streptomycin, P/S) or an anti-inflammatory drug (dexamethasone, Dex), termed PPy[P/S] or PPy[Dex], respectively, were electrodeposited in PPy on titanium. The objective of the present study was to determine if such drugs can be released from PPy on demand and (by applying a voltage) control cellular behavior important for orthopedic applications. Results showed that PPy films possessed nanometer-scale roughness as analyzed by atomic force microscopy. X-ray photoelectron spectroscopy confirmed the presence of P/S and Dex encapsulated within the PPy films. Results from cyclic voltammetry showed that 80% of the drugs were released on demand when sweep voltages were applied for five cycles at a scan rate of 0.1 V s - 1. Furthermore, osteoblast (bone-forming cells) and fibroblast (fibrous tissue-forming cells) adhesion were determined on the PPy films. Results showed that PPy[Dex] enhanced osteoblast adhesion after 4 h of culture compared to plain Ti. PPy-Ti (with or without anionic drug doping) inhibited fibroblast adhesion compared to plain Ti. These in vitro results confirmed that electrodeposited PPy[P/S] and PPy[Dex] can release drugs on demand to potentially fight bacterial infection, reduce inflammation, promote bone growth or reduce fibroblast functions, further implicating the use of such materials as implant sensors.

  9. Structure-related antibacterial activity of a titanium nanostructured surface fabricated by glancing angle sputter deposition

    NASA Astrophysics Data System (ADS)

    Sengstock, Christina; Lopian, Michael; Motemani, Yahya; Borgmann, Anna; Khare, Chinmay; Buenconsejo, Pio John S.; Schildhauer, Thomas A.; Ludwig, Alfred; Köller, Manfred

    2014-05-01

    The aim of this study was to reproduce the physico-mechanical antibacterial effect of the nanocolumnar cicada wing surface for metallic biomaterials by fabrication of titanium (Ti) nanocolumnar surfaces using glancing angle sputter deposition (GLAD). Nanocolumnar Ti thin films were fabricated by GLAD on silicon substrates. S. aureus as well as E. coli were incubated with nanostructured or reference dense Ti thin film test samples for one or three hours at 37 °C. Bacterial adherence, morphology, and viability were analyzed by fluorescence staining and scanning electron microscopy and compared to human mesenchymal stem cells (hMSCs). Bacterial adherence was not significantly different after short (1 h) incubation on the dense or the nanostructured Ti surface. In contrast to S. aureus the viability of E. coli was significantly decreased after 3 h on the nanostructured film compared to the dense film and was accompanied by an irregular morphology and a cell wall deformation. Cell adherence, spreading and viability of hMSCs were not altered on the nanostructured surface. The results show that the selective antibacterial effect of the cicada wing could be transferred to a nanostructured metallic biomaterial by mimicking the natural nanocolumnar topography.

  10. Organic photovoltaic with various plasmonic nanostructures using titanium nitride

    NASA Astrophysics Data System (ADS)

    Magdi, Sara; Gan, Qiaoqiang; Swillam, Mohamed A.

    2016-03-01

    We demonstrate absorption improvement in organic solar cells due to the incorporation of TiN nanopatterned back electrode. Organic solar cells (OSC) have already reached 10% power conversion efficiency (PCE), which made them comparable to commercial solar cells. Localizing light using plasmonic nanostructures has the potential to overcome OSC absorption limitations and thus further improve their PCE. Using a C-MOS compatible, cheap and abundant material for light trapping could facilitate the commercialization of OSC. This work theoretically shows that the replacement of Ag nanopatterned back electrode with TiN in plasmonic OSC gives enhanced performance. In addition, the incorporation of TiN nanoparticles inside the active layer has been studied and analyzed.

  11. Magnesium ion implantation on a micro/nanostructured titanium surface promotes its bioactivity and osteogenic differentiation function

    PubMed Central

    Wang, Guifang; Li, Jinhua; Zhang, Wenjie; Xu, Lianyi; Pan, Hongya; Wen, Jin; Wu, Qianju; She, Wenjun; Jiao, Ting; Liu, Xuanyong; Jiang, Xinquan

    2014-01-01

    As one of the important ions associated with bone osseointegration, magnesium was incorporated into a micro/nanostructured titanium surface using a magnesium plasma immersion ion-implantation method. Hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 30 minutes (Mg30) and hierarchical hybrid micro/nanostructured titanium surfaces followed by magnesium ion implantation for 60 minutes (Mg60) were used as test groups. The surface morphology, chemical properties, and amount of magnesium ions released were evaluated by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy, and inductively coupled plasma-optical emission spectrometry. Rat bone marrow mesenchymal stem cells (rBMMSCs) were used to evaluate cell responses, including proliferation, spreading, and osteogenic differentiation on the surface of the material or in their medium extraction. Greater increases in the spreading and proliferation ability of rBMMSCs were observed on the surfaces of magnesium-implanted micro/nanostructures compared with the control plates. Furthermore, the osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) genes were upregulated on both surfaces and in their medium extractions. The enhanced cell responses were correlated with increasing concentrations of magnesium ions, indicating that the osteoblastic differentiation of rBMMSCs was stimulated through the magnesium ion function. The magnesium ion-implanted micro/nanostructured titanium surfaces could enhance the proliferation, spreading, and osteogenic differentiation activity of rBMMSCs, suggesting they have potential application in improving bone-titanium integration. PMID:24940056

  12. Cell spreading on titanium periodic nanostructures with periods of 200, 300 and 600 nm produced by femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Tsukamoto, M.; Kawa, T.; Shinonaga, T.; Chen, P.; Nagai, A.; Hanawa, T.

    2016-02-01

    Titanium (Ti) is an important biomaterial. We have used femtosecond laser irradiation to form periodic nanostructures on Ti plate for control of the cell spreading. In this study, periodic nanostructures with periodicities of 200, 300 and 600 nm were formed on a Ti plates using a femtosecond laser with wavelengths of 258, 388 and 775 nm, respectively. Cell spreading on the Ti plate for periodic nanostructures with periodicity of 200 nm lacked a definite direction, whereas cell spreadings on the Ti plate for periodic nanostructures with periodicities of 300 and 600 nm occurred along the grooves.

  13. Nanostructured polymer-titanium composites and titanium oxide through polymer swelling in titania precursor.

    PubMed

    Kierys, A; Zaleski, R; Buda, W; Pikus, S; Dziadosz, M; Goworek, J

    2013-06-01

    Polymer (XAD7HP)/Ti(4+) nanocomposites were prepared through the swelling of polymer in titanium (IV) ethoxide as a titanium dioxide precursor. The nanocomposite beads exhibit relatively high porosity different than the porosity of the initial polymer. Thermal treatment of composite particles up to 200 °C in vacuum causes the change of their internal structure. At higher temperature, the components of composite become more tightly packed. Calcination at 600 °C and total removal of polymer produce spherically shaped TiO2 condensed phase as determined by XRD. Thermally treated composites show the substantial change of pore dimensions within micro- and mesopores. The presence of micropores and their transformation during thermal processing was studied successfully by positron annihilation lifetime spectroscopy (PALS). The results derived from PALS experiment were compared with those obtaining from low-temperature nitrogen adsorption data. PMID:23741082

  14. Titanium-Catalyzed Silicon Nanostructures Grown by APCVD

    NASA Astrophysics Data System (ADS)

    Usman, Mohammad A. U.; Smith, Brady J.; Jackson, Justin B.; De Long, Matthew C.; Miller, Mark S.

    2015-01-01

    We report on growth of Ti-catalyzed silicon nanostructures (SNCs) through atmospheric-pressure chemical vapor deposition. An extensive growth study relating the growth condition parameters, including the partial pressure of SiCl4 gas, reaction temperature, and reaction time, was carried out to obtain insight into the growth regimes for the observed SNCs. Based on phase diagram analysis of Ti-Si alloy and growth rate analysis of the silicon nanowires (SNWs) and silicon nanoplatelets, we believe the growth mechanism to be strongly dependent on the thermodynamics of the system, exhibiting a delicate balance that can easily tip between the growth and etching regimes of the system. Three types of SNCs were observed frequently throughout the study: nanowires, nanoplatelets, and balls. Regimes for highly etched growth were also noted through growth conditions plots. Ti-catalyzed SNWs grown using SiCl4 gas strongly suggest growth occurring through a type of vapor-solid-solid (VSS) mechanism that is limited by diffusion through the solid-catalyst interface. On the other hand, the two-dimensional SNP morphologies suggest growth occurring through the twin-plane mechanism at the edges, at 10 nm to 100 nm scales, also through a similar, VSS mechanism.

  15. Electrospun Nanostructured Fibers of Collagen-Biomimetic Apatite on Titanium Alloy

    PubMed Central

    Iafisco, Michele; Foltran, Ismaela; Sabbatini, Simona; Tosi, Giorgio; Roveri, Norberto

    2012-01-01

    Titanium and its alloys are currently the mainly used materials to manufacture orthopaedic implants due to their excellent mechanical properties and corrosion resistance. Although these materials are bioinert, the improvement of biological properties (e.g., bone implant contact) can be obtained by the application of a material that mimics the bone extracellular matrix. To this aim, this work describes a new method to produce nanostructured collagen-apatite composites on titanium alloy substrate, by combining electrospinning and biomimetic mineralization. The characterization results showed that the obtained mineralized scaffolds have morphological, structural, and chemical compositional features similar to natural bone extracellular matrix. Finally, the topographic distribution of the chemical composition in the mineralized matrix evaluated by Fourier Transform Infrared microspectroscopy demonstrated that the apatite nanocrystals cover the collagen fibers assembled by the electrospinning. PMID:22400013

  16. Characteristics of titanium dioxide nanostructures synthesized via electrochemical anodization at different applied voltages

    NASA Astrophysics Data System (ADS)

    Cheong, Y. L.; Yam, F. K.; Hassan, Z.

    2015-05-01

    This paper presents the study of the growth of nanostructure titanium dioxide (TiO2) via electrochemical anodization method. Both constant and alternating anodization voltage would be applied in this study. The effects of applied voltage on the morphological and structural properties were studied. Images of field emission scanning electron microscope (FE-SEM) revealed that morphology of nanostructure could be manipulated by changing the type and amount of applied voltage. Besides that, X-ray diffraction (XRD) results indicated that crystalline structures (anatase and rutile) could be obtained after being annealed at 700°C for 60 minutes. By analysing the data in XRD measurements, crystallite size of the TiO2 could be calculated by using the Scherrer method. Besides that, the relationship between mean crystallites sizes and anodization voltage would also be further studied in this paper.

  17. Characteristics of titanium dioxide nanostructures synthesized via electrochemical anodization at different applied voltages

    SciTech Connect

    Cheong, Y. L.; Yam, F. K.; Hassan, Z.

    2015-05-15

    This paper presents the study of the growth of nanostructure titanium dioxide (TiO{sub 2}) via electrochemical anodization method. Both constant and alternating anodization voltage would be applied in this study. The effects of applied voltage on the morphological and structural properties were studied. Images of field emission scanning electron microscope (FE-SEM) revealed that morphology of nanostructure could be manipulated by changing the type and amount of applied voltage. Besides that, X-ray diffraction (XRD) results indicated that crystalline structures (anatase and rutile) could be obtained after being annealed at 700°C for 60 minutes. By analysing the data in XRD measurements, crystallite size of the TiO{sub 2} could be calculated by using the Scherrer method. Besides that, the relationship between mean crystallites sizes and anodization voltage would also be further studied in this paper.

  18. Titanium nanostructures made by local oxidation with the atomic force microscope

    NASA Astrophysics Data System (ADS)

    Vullers, R. J. M.; Ahlskog, M.; Van Haesendonck, C.

    1999-04-01

    Surfaces can be oxidized under ambient conditions with the tip of a scanning probe microscope when applying a voltage between surface and tip. The oxidation process is voltage- and humidity-dependent, and can be explained in terms of anodic oxidation. Sufficiently thin metal films (e.g., Ti or Al) can be completely oxidized down to the substrate, enabling the direct writing of nanostructures. We report on the fabrication and electrical measurements of Ti lines and Ti/TiO x/Ti junctions defined in titanium thin films having a thickness smaller than 10 nm.

  19. Graphitic carbon in a nanostructured titanium oxycarbide thin film to improve implant osseointegration.

    PubMed

    Zanoni, R; Ioannidu, C A; Mazzola, L; Politi, L; Misiano, C; Longo, G; Falconieri, M; Scandurra, R

    2015-01-01

    A nanostructured coating layer on titanium implants, able to improve their integration into bones and to protect against the harsh conditions of body fluids, was obtained by Ion Plating Plasma Assisted, a method suitable for industrial applications. A titanium carbide target was attached under vacuum to a magnetron sputtering source powered with a direct current in the 500-1100 W range, and a 100 W radio frequency was applied to the sample holder. The samples produced at 900 W gave the best biological response in terms of overexpression of some genes of proteins involved in bone turnover. We report the characterization of a reference and of an implant sample, both obtained at 900 W. Different micro/nanoscopic techniques evidenced the morphology of the substrates, and X-ray Photoelectron Spectroscopy was used to disclose the surface composition. The layer is a 500 nm thick hard nanostructure, composed of 60% graphitic carbon clustered with 15% TiC and 25% Ti oxides. PMID:25492005

  20. Adherence of human oral keratinocytes and gingival fibroblasts to nano-structured titanium surfaces

    PubMed Central

    2014-01-01

    Background A key element for long-term success of dental implants is integration of the implant surface with the surrounding host tissues. Modification of titanium implant surfaces can enhance osteoblast activity but their effects on soft-tissue cells are unclear. Adherence of human keratinocytes and gingival fibroblasts to control commercially pure titanium (CpTi) and two surfaces prepared by anodic oxidation was therefore investigated. Since implant abutments are exposed to a bacteria-rich environment in vivo, the effect of oral bacteria on keratinocyte adhesion was also evaluated. Methods The surfaces were characterized using scanning electron microscopy (SEM). The number of adhered cells and binding strength, as well as vitality of fibroblasts and keratinocytes were evaluated using confocal scanning laser microscopy after staining with Live/Dead Baclight. To evaluate the effect of bacteria on adherence and vitality, keratinocytes were co-cultured with a four-species streptococcal consortium. Results SEM analysis showed the two anodically oxidized surfaces to be nano-structured with differing degrees of pore-density. Over 24 hours, both fibroblasts and keratinocytes adhered well to the nano-structured surfaces, although to a somewhat lesser degree than to CpTi (range 42-89% of the levels on CpTi). The strength of keratinocyte adhesion was greater than that of the fibroblasts but no differences in adhesion strength could be observed between the two nano-structured surfaces and the CpTi. The consortium of commensal streptococci markedly reduced keratinocyte adherence on all the surfaces as well as compromising membrane integrity of the adhered cells. Conclusion Both the vitality and level of adherence of soft-tissue cells to the nano-structured surfaces was similar to that on CpTi. Co-culture with streptococci reduced the number of keratinocytes on all the surfaces to approximately the same level and caused cell damage, suggesting that commensal bacteria could

  1. Osteogenic response and osteoprotective effects in vivo of a nanostructured titanium surface with antibacterial properties.

    PubMed

    Ravanetti, F; Chiesa, R; Ossiprandi, M C; Gazza, F; Farina, V; Martini, F M; Di Lecce, R; Gnudi, G; Della Valle, C; Gavini, J; Cacchioli, A

    2016-03-01

    In implantology, as an alternative approach to the use of antibiotics, direct surface modifications of the implant addressed to inhibit bacterial adhesion and to limit bacterial proliferation are a promising tactic. The present study evaluates in an in vivo normal model the osteogenic response and the osteointegration of an anodic spark deposition nanostructured titanium surface doped with gallium (ASD + Ga) in comparison with two other surface treatments of titanium: an anodic spark deposition treatment without gallium (ASD) and an acid etching treatment (CTR). Moreover the study assesses the osteoprotective potential and the antibacterial effect of the previously mentioned surface treatments in an experimentally-induced peri-implantitis model. The obtained data points out a more rapid primary fixation in ASD and ASD + Ga implants, compared with CTR surface. Regarding the antibacterial properties, the ASD + Ga surface shows osteoprotective action on bone peri-implant tissue in vivo as well as an antibacterial effect within the first considered time point. PMID:26787484

  2. Direct Blue Dye Degradation Using Titanium Nanostructures Under Energy-Efficient UV-LED Irradiation

    NASA Astrophysics Data System (ADS)

    Jo, Wan-Kuen; Tayade, Rajesh J.

    2016-01-01

    The present study describes the effect of titanium dioxide (TiO2) morphology on the photocatalytic activity under irradiation of ultraviolet light-emitting diode (UV-LED). Different TiO2 nanostructures were synthesized using hydrothermal (nanotubes and nanospheres) and solvothermal (nanoflowers) methods. The morphology, phase composition, bandgap, and chemical properties of the synthesized different TiO2 nanostructures were characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS), and Brunauer-Emmett-Teller (BET) analysis. The surface area of the nanotubes was larger than that of the nanospheres and nanoflowers by four- and three-fold, respectively. The photocatalytic activity of the photocatalysts was evaluated by degradation of direct blue-15 dye under UV-LED irradiation in a slurry-type reactor. The photocatalytic activity of the TiO2 nanoflowers was higher than that of TiO2 nanotubes or nanospheres, suggesting that nanoflowers can serve as efficient photocatalysts for dye degradation.

  3. Modulating macrophage polarization with divalent cations in nanostructured titanium implant surfaces

    NASA Astrophysics Data System (ADS)

    Lee, Chung-Ho; Kim, Youn-Jeong; Jang, Je-Hee; Park, Jin-Woo

    2016-02-01

    Nanoscale topographical modification and surface chemistry alteration using bioactive ions are centrally important processes in the current design of the surface of titanium (Ti) bone implants with enhanced bone healing capacity. Macrophages play a central role in the early tissue healing stage and their activity in response to the implant surface is known to affect the subsequent healing outcome. Thus, the positive modulation of macrophage phenotype polarization (i.e. towards the regenerative M2 rather than the inflammatory M1 phenotype) with a modified surface is essential for the osteogenesis funtion of Ti bone implants. However, relatively few advances have been made in terms of modulating the macrophage-centered early healing capacity in the surface design of Ti bone implants for the two important surface properties of nanotopography and and bioactive ion chemistry. We investigated whether surface bioactive ion modification exerts a definite beneficial effect on inducing regenerative M2 macrophage polarization when combined with the surface nanotopography of Ti. Our results indicate that nanoscale topographical modification and surface bioactive ion chemistry can positively modulate the macrophage phenotype in a Ti implant surface. To the best of our knowledge, this is the first demonstration that chemical surface modification using divalent cations (Ca and Sr) dramatically induces the regenerative M2 macrophage phenotype of J774.A1 cells in nanostructured Ti surfaces. In this study, divalent cation chemistry regulated the cell shape of adherent macrophages and markedly up-regulated M2 macrophage phenotype expression when combined with the nanostructured Ti surface. These results provide insight into the surface engineering of future Ti bone implants that are harmonized between the macrophage-governed early wound healing process and subsequent mesenchymal stem cell-centered osteogenesis function.

  4. Modulating macrophage polarization with divalent cations in nanostructured titanium implant surfaces.

    PubMed

    Lee, Chung-Ho; Kim, Youn-Jeong; Jang, Je-Hee; Park, Jin-Woo

    2016-02-26

    Nanoscale topographical modification and surface chemistry alteration using bioactive ions are centrally important processes in the current design of the surface of titanium (Ti) bone implants with enhanced bone healing capacity. Macrophages play a central role in the early tissue healing stage and their activity in response to the implant surface is known to affect the subsequent healing outcome. Thus, the positive modulation of macrophage phenotype polarization (i.e. towards the regenerative M2 rather than the inflammatory M1 phenotype) with a modified surface is essential for the osteogenesis funtion of Ti bone implants. However, relatively few advances have been made in terms of modulating the macrophage-centered early healing capacity in the surface design of Ti bone implants for the two important surface properties of nanotopography and and bioactive ion chemistry. We investigated whether surface bioactive ion modification exerts a definite beneficial effect on inducing regenerative M2 macrophage polarization when combined with the surface nanotopography of Ti. Our results indicate that nanoscale topographical modification and surface bioactive ion chemistry can positively modulate the macrophage phenotype in a Ti implant surface. To the best of our knowledge, this is the first demonstration that chemical surface modification using divalent cations (Ca and Sr) dramatically induces the regenerative M2 macrophage phenotype of J774.A1 cells in nanostructured Ti surfaces. In this study, divalent cation chemistry regulated the cell shape of adherent macrophages and markedly up-regulated M2 macrophage phenotype expression when combined with the nanostructured Ti surface. These results provide insight into the surface engineering of future Ti bone implants that are harmonized between the macrophage-governed early wound healing process and subsequent mesenchymal stem cell-centered osteogenesis function. PMID:26807875

  5. Titanium

    SciTech Connect

    Fox, G.J.

    1997-01-01

    The article contains a summary of factors pertinent to titanium use. Geology and exploitation, production processes, global production, titanium dioxide and alloy applications, and the titanium market are reviewed. Potential applications outlined are for oil and gas equipment and for the automotive industry. Titanium alloys were selected for drilling risers for North Sea oil and gas drilling platforms due to a high strength-to-weight ratio and corrosion resistance. These properties also make titanium alloys attractive for auto parts, although the cost is currently prohibitive.

  6. Evaluating the osseointegration of nanostructured titanium implants in animal models: Current experimental methods and perspectives (Review).

    PubMed

    Babuska, Vaclav; Moztarzadeh, Omid; Kubikova, Tereza; Moztarzadeh, Amin; Hrusak, Daniel; Tonar, Zbynek

    2016-01-01

    The aim of this paper is to review the experimental methods currently being used to evaluate the osseointegration of nanostructured titanium implants using animal models. The material modifications are linked to the biocompatibility of various types of oral implants, such as laser-treated, acid-etched, plasma-coated, and sand-blasted surface modifications. The types of implants are reviewed according to their implantation site (endoosseous, subperiosteal, and transosseous implants). The animal species and target bones used in experimental implantology are carefully compared in terms of the ratio of compact to spongy bone. The surgical technique in animal experiments is briefly described, and all phases of the histological evaluation of osseointegration are described in detail, including harvesting tissue samples, processing undemineralized ground sections, and qualitative and quantitative histological assessment of the bone-implant interface. The results of histological staining methods used in implantology are illustrated and compared. A standardized and reproducible technique for stereological quantification of bone-implant contact is proposed and demonstrated. In conclusion, histological evaluation of the experimental osseointegration of dental implants requires careful selection of the experimental animals, bones, and implantation sites. It is also advisable to use larger animal models and older animals with a slower growth rate rather than small or growing experimental animals. Bones with a similar ratio of compact to spongy bone, such as the human maxilla and mandible, are preferred. A number of practical recommendations for the experimental procedures, harvesting of samples, tissue processing, and quantitative histological evaluations are provided. PMID:27421518

  7. Low-temperature deformation and fracture of bulk nanostructural titanium obtained by intense plastic deformation using equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Bengus, V. Z.; Tabachnikova, E. D.; Natsik, V. D.; Mishkuf, Ä.¬.; Chakh, K.; Stolyarov, V. V.; Valiev, R. Z.

    2002-11-01

    The low-temperature plasticity and fracture of polycrystals of coarse-grained (CG) and nanostructural (NS) technical-grade titanium of two structural modifications with grain size 0.3 and 0.1 μm, which were prepared by equal channel angular pressing (ECAP) with additional thermomechanical treatment are studied. The measurements are performed at temperatures 300, 77, and 4.2 K with uniaxial compression at deformation rate 4×10-4 s-1. The "stress-plastic deformation" hardening curves are obtained, the macroscopic yield stress, and the ultimate plasticity are measured for samples with compression axis orientations parallel and transverse to the ECAP axis. It is found that the yield stress for NS titanium is 1.5-2 times higher than for CG titanium and the yield stress on cooling from 300 to 4.2 K. Plasticity anisotropy is also observed in NS titanium—the yield stress is 1.2-1.5 times greater when the compression axis is oriented perpendicular to the ESAP axis than for parallel orientation. The ultimate plasticity with such changes in the structure of samples and under the experimental conditions systematically decreases, but the deformation to fracture remains above 4%. Nanostructural titanium does not show cold-brittleness right down to liquid-helium temperatures, but at 4.2 K plastic flow becomes jumplike, just as in CG titanium. It is established that for low-temperature uniaxial compression NS titanium fractures as a result of unstable plastic shear accompanied by local adiabatic heating of the material. This phenomenon is not characteristic of CG titanium. A study of the morphology of the shear-fracture surfaces using a scanning electron microsope shows a characteristic "vein" pattern, attesting to local heating at temperatures ⩾800 °C. It is established that plastic deformation in NS titanium is thermally activated at low temperatures. It is shown that microstructural internal stresses due to thermal anisotropy and possible microtwinning affect the yield

  8. Titanium

    USGS Publications Warehouse

    Bedinger, G.M.

    2013-01-01

    Titanium is the ninth most abundant element in the earth’s crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  9. Enhanced osteoblast proliferation and corrosion resistance of commercially pure titanium through surface nanostructuring by ultrasonic shot peening and stress relieving.

    PubMed

    Jindal, Shitu; Bansal, Rajesh; Singh, Bijay P; Pandey, Rajiv; Narayanan, Shankar; Wani, Mohan R; Singh, Vakil

    2014-07-01

    This investigation was carried out to study the effect of a novel process of surface modification, surface nanostructuring by ultrasonic shot peening, on osteoblast proliferation and corrosion behavior of commercially pure titanium (c p-Ti) in simulated body fluid. A mechanically polished disc of c p-Ti was subjected to ultrasonic shot peening with stainless steel balls to create nanostructure at the surface. A nanostructure (<20 nm) with inhomogeneous distribution was revealed by atomic force and scanning electron microscopy. There was an increase of approximately 10% in cell proliferation, but there was drastic fall in corrosion resistance. Corrosion rate was increased by 327% in the shot peened condition. In order to examine the role of residual stresses associated with the shot peened surface on these aspects, a part of the shot peened specimen was annealed at 400°C for 1 hour. A marked influence of annealing treatment was observed on surface structure, cell proliferation, and corrosion resistance. Surface nanostructure was much more prominent, with increased number density and sharper grain boundaries; cell proliferation was enhanced to approximately 50% and corrosion rate was reduced by 86.2% and 41% as compared with that of the shot peened and the as received conditions, respectively. The highly significant improvement in cell proliferation, resulting from annealing of the shot peened specimen, was attributed to increased volume fraction of stabilized nanostructure, stress recovery, and crystallization of the oxide film. Increase in corrosion resistance from annealing of shot peened material was related to more effective passivation. Thus, the surface of c p-Ti, modified by this novel process, possessed a unique quality of enhancing cell proliferation as well as the corrosion resistance and could be highly effective in reducing treatment time of patients adopting dental and orthopedic implants of titanium and its alloys. PMID:25020216

  10. Electron-beam-induced deposition and post-treatment processes to locally generate clean titanium oxide nanostructures on Si(100).

    PubMed

    Schirmer, M; Walz, M-M; Vollnhals, F; Lukasczyk, T; Sandmann, A; Chen, C; Steinrück, H-P; Marbach, H

    2011-02-25

    We have investigated the lithographic generation of TiO(x) nanostructures on Si(100) via electron-beam-induced deposition (EBID) of titanium tetraisopropoxide (TTIP) in ultra-high vacuum (UHV) by scanning electron microscopy (SEM) and local Auger electron spectroscopy (AES). In addition, the fabricated nanostructures were also characterized ex situ via atomic force microscopy (AFM) under ambient conditions. In EBID, a highly focused electron beam is used to locally decompose precursor molecules and thereby to generate a deposit. A drawback of this nanofabrication technique is the unintended deposition of material in the vicinity of the impact position of the primary electron beam due to so-called proximity effects. Herein, we present a post-treatment procedure to deplete the unintended deposits by moderate sputtering after the deposition process. Moreover, we were able to observe the formation of pure titanium oxide nanocrystals (<100 nm) in situ upon heating the sample in a well-defined oxygen atmosphere. While the nanocrystal growth for the as-deposited structures also occurs in the surroundings of the irradiated area due to proximity effects, it is limited to the pre-defined regions, if the sample was sputtered before heating the sample under oxygen atmosphere. The described two-step post-treatment procedure after EBID presents a new pathway for the fabrication of clean localized nanostructures. PMID:21242619

  11. Electron-beam-induced deposition and post-treatment processes to locally generate clean titanium oxide nanostructures on Si(100)

    NASA Astrophysics Data System (ADS)

    Schirmer, M.; Walz, M.-M.; Vollnhals, F.; Lukasczyk, T.; Sandmann, A.; Chen, C.; Steinrück, H.-P.; Marbach, H.

    2011-02-01

    We have investigated the lithographic generation of TiOx nanostructures on Si(100) via electron-beam-induced deposition (EBID) of titanium tetraisopropoxide (TTIP) in ultra-high vacuum (UHV) by scanning electron microscopy (SEM) and local Auger electron spectroscopy (AES). In addition, the fabricated nanostructures were also characterized ex situ via atomic force microscopy (AFM) under ambient conditions. In EBID, a highly focused electron beam is used to locally decompose precursor molecules and thereby to generate a deposit. A drawback of this nanofabrication technique is the unintended deposition of material in the vicinity of the impact position of the primary electron beam due to so-called proximity effects. Herein, we present a post-treatment procedure to deplete the unintended deposits by moderate sputtering after the deposition process. Moreover, we were able to observe the formation of pure titanium oxide nanocrystals (<100 nm) in situ upon heating the sample in a well-defined oxygen atmosphere. While the nanocrystal growth for the as-deposited structures also occurs in the surroundings of the irradiated area due to proximity effects, it is limited to the pre-defined regions, if the sample was sputtered before heating the sample under oxygen atmosphere. The described two-step post-treatment procedure after EBID presents a new pathway for the fabrication of clean localized nanostructures.

  12. Investigation of nanostructured platinum-nickel supported on the titanium surface as electrocatalysts for alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Tamašauskaitė-Tamašiūnaitė, L.; Balčiūnaitė, A.; Vaiciukevičienė, A.; Selskis, A.; Pakštas, V.

    2012-06-01

    This study involves the formation of nanostructured platinum-nickel supported on the titanium surface catalysts using the galvanic displacement technique and investigation of their electrocatalytic activity toward the oxidation of borohydride, methanol and ethanol in an alkaline media by cyclic voltammetry and chronoamperometry. Scanning electron microscopy, Energy Dispersive X-ray Spectroscopy and X-ray diffraction were used to characterize the surface structure, composition and morphology. The nanoPt(Ni)/Ti and nanoPt/Ti catalysts exhibited a higher catalytic efficiency to the oxidation of borohydride, ethanol and methanol as compared with that of pure Pt.

  13. Microstructure and Mechanical Properties of Nanostructured and Ultrafine-Grained Titanium and the Zirconium Formed by the Method of Severe Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Sharkeev, Yu. P.; Eroshenko, A. Yu.; Danilov, V. I.; Tolmachev, A. I.; Uvarkin, P. V.; Abzaev, Yu. A.

    2014-02-01

    Results of investigation of the microstructure, mechanical properties, and thermostability of bioinert titanium VT1-0 and zirconium E110 in nanostructured and ultrafine-grained states formed by combined methods of severe plastic deformation, including abc pressing in a press-mould or without it and multipass rolling in grooved or smooth rolls, are presented. It is demonstrated that the combined severe plastic deformation method allows titanium and zirconium billets in nanostructured and ultrafine-grained states to be obtained that provides substantial improvement of the mechanical properties comparable to the properties of titanium alloys, for example, VT6 and VT16 ones. The yield strength and the microhardness of titanium and zirconium obey the Hall-Petch relationship.

  14. Tungsten Bronze Barium Neodymium Titanate (Ba(6-3n)Nd(8+2n)Ti(18)O(54)): An Intrinsic Nanostructured Material and Its Defect Distribution.

    PubMed

    Azough, Feridoon; Cernik, Robert Joseph; Schaffer, Bernhard; Kepaptsoglou, Demie; Ramasse, Quentin Mathieu; Bigatti, Marco; Ali, Amir; MacLaren, Ian; Barthel, Juri; Molinari, Marco; Baran, Jakub Dominik; Parker, Stephen Charles; Freer, Robert

    2016-04-01

    We investigated the structure of the tungsten bronze barium neodymium titanates Ba(6-3n)Nd(8+2n)Ti(18)O(54), which are exploited as microwave dielectric ceramics. They form a complex nanostructure, which resembles a nanofilm with stacking layers of ∼12 Å thickness. The synthesized samples of Ba(6-3n)Nd(8+2n)Ti(18)O(54) (n = 0, 0.3, 0.4, 0.5) are characterized by pentagonal and tetragonal columns, where the A cations are distributed in three symmetrically inequivalent sites. Synchrotron X-ray diffraction and electron energy loss spectroscopy allowed for quantitative analysis of the site occupancy, which determines the defect distribution. This is corroborated by density functional theory calculations. Pentagonal columns are dominated by Ba, and tetragonal columns are dominated by Nd, although specific Nd sites exhibit significant concentrations of Ba. The data indicated significant elongation of the Ba columns in the pentagonal positions and of the Nd columns in tetragonal positions involving a zigzag arrangement of atoms along the b lattice direction. We found that the preferred Ba substitution occurs at Nd[3]/[4] followed by Nd[2] and Nd[1]/[5] sites, which is significantly different to that proposed in earlier studies. Our results on the Ba(6-3n)Nd(8+2n)Ti(18)O(54) "perovskite" superstructure and its defect distribution are particularly valuable in those applications where the optimization of material properties of oxides is imperative; these include not only microwave ceramics but also thermoelectric materials, where the nanostructure and the distribution of the dopants will reduce the thermal conductivity. PMID:26998674

  15. Nanostructured Al{sub 2}O{sub 3}-TiO{sub 2} coatings for high-temperature protection of titanium alloy during ablation

    SciTech Connect

    Li Chonggui; Wang You; Tian Wei; Yang Yong

    2010-08-15

    Plasma-sprayed nanostructured Al{sub 2}O{sub 3}-13 wt.%TiO{sub 2} coatings were successfully fabricated on titanium alloys (Ti-6Al-4V) using as-prepared feedstock. Ablation experiments for the titanium alloy samples with or without a coating were carried out using a Metco 9MB plasma gun. The microstructure, phase constituents and mechanical properties of the titanium alloys before and after ablation were investigated by scanning electron microscope (SEM), X-ray diffractometer (XRD) and Vickers hardness tester. The surface morphologies, cross-sectional microstructure and hardness of titanium alloys with coatings are similar before and after ablation. In contrast, the microstructure and mechanical properties of the titanium alloy without coating are significantly changed after ablation. The surface coating is found to serve as a protective coating during ablation.

  16. Adhesive strength of medical polymer on anodic oxide nanostructures fabricated on biomedical β-type titanium alloy.

    PubMed

    Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken; Mohri, Tomoyoshi; Hanawa, Takao

    2014-03-01

    Anodic oxide nanostructures (nanopores and nanotubes) were fabricated on a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), by anodization in order to improve the adhesive strength of a medical polymer, segmented polyurethane (SPU), to TNTZ. TNTZ was anodized in 1.0M H3PO4 solution with 0.5 mass% NaF using a direct-current power supply at a voltage of 20V. A nanoporous structure is formed on TNTZ in the first stage of anodization, and the formation of a nanotube structure occurs subsequently beneath the nanoporous structure. The nanostructures formed on TNTZ by anodization for less than 3,600s exhibit higher adhesive strengths than those formed at longer anodization times. The adhesive strength of the SPU coating on the nanoporous structure formed on top of TNTZ by anodization for 1,200s improves by 144% compared to that of the SPU coating on as-polished TNTZ with a mirror surface. The adhesive strength of the SPU coating on the nanotube structure formed on TNTZ by anodization for 3,600s increases by 50%. These improvements in the adhesive strength of SPU are the result of an anchor effect introduced by the nanostructures formed by anodization. Fracture occurs at the interface of the nanoporous structure and the SPU coating layer. In contrast, in the case that SPU coating has been performed on the nanotube structure, fracture occurs inside the nanotubes. PMID:24433910

  17. Monolithic co-aerogels of carbon/titanium dioxide as three dimensional nanostructured electrodes for energy storage

    NASA Astrophysics Data System (ADS)

    Yang, Sungwoo; Cai, Yue; Cheng, Yingwen; Varanasi, C. V.; Liu, Jie

    2012-11-01

    Conductive fillers, such as amorphous carbon, carbon nanotube and graphene etc., are generally mixed with nanostructured metal oxide materials to improve the performance of electrode materials in energy storage devices. However, the conductive framework that provides path for electric conduction does not normally form a well-connected and robust 3-D network to ensure optimized ions transport. Here, we report a convenient, inexpensive and scalable method for synthesizing hybrid carbon and titanium dioxide co-gels and co-aerogels to improve the electrochemical capacity by combining both the lithium insertion and the surface storage mechanisms in Li ion batteries (LIBs) anodes. A monolithic piece of a hybrid C/TiO2 co-aerogel can be directly used as an active electrode without the addition of binders, such as polyvinylidene fluoride (PVDF). As a result, the performance of LIB anodes using the hybrid co-aerogel is significantly improved over current LIBs based on carbon/titanium oxide composites. The reversible discharge capacity was stabilized at ˜400 mAh g-1 at a 168 mA g-1 scan rate and an operating voltage between 3.0 and 0.05 V vs. Li+/Li with excellent cyclic capacity retention. This approach, however, is not limited to only C/TiO2 system but can be extended to other metal oxides to form co-gels with carbon to improve their potential use in numerous electrochemical, photocatalytic, and photoelectronic devices.

  18. Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

    2015-11-01

    Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

  19. Hierarchical titania nanostructures prepared with focused ion beam-assisted anodisation of titanium in an aqueous electrolyte

    NASA Astrophysics Data System (ADS)

    Yadav, Pradeep K.; Lemoine, Patrick; Dale, Graham; Hamilton, Jeremy W. J.; Dunlop, Patrick S. M.; Byrne, John A.; Mailley, Pascal; Boxall, Colin

    2015-04-01

    Titania nanostructures have been prepared by anodisation in aqueous solution assisted by focused ion beam (FIB) milling. The structures formed are bi-periodic, a disordered "native" nanotube array, with characteristics similar to those formed by the standard anodisation process and an ordered array of tubes with larger diameters, guided by the positioning of the FIB concave pits. Low kV EDX analysis shows implanted Ga in FIB-treated titanium which is efficiently removed by the anodisation process. Following thermal annealing, the FIB-treated regions also crystallise to the same anatase phase as the native regions. This result is in stark contrast to previous FIB-assisted anodisation studies which only produced nanostructured arrays of native dimensions. This singularity is discussed in terms of the stable FIB-induced crystalline defects which, in an aqueous electrolyte, can result in the growth of a weaker barrier layer and larger tubes. This novel process gave hexagonal and square arrays with tailored cross-sectional dimensions and therefore has potential for the synthesis of novel meta-materials.

  20. Tribological behaviour of mechanically synthesized titanium-boron carbide nanostructured coating.

    PubMed

    Aliofkhazraei, M; Rouhaghdam, A Sabour

    2012-08-01

    In this paper, titanium-boron carbide (Ti/B4C) nanocomposite coatings with different B4C nanoparticles contents were fabricated by surface mechanical attrition treatment (SMAT) method by using B4C nanoparticles with average nanoparticle size of 40 nm. The characteristics of the nanopowder and coatings were evaluated by microhardness test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Friction and wear performances of nanocomposite coatings and pure titanium substrate were comparatively investigated, with the effect of the boron carbide content on the friction and wear behaviours to be emphasized. The results show the microhardness, friction and wear behaviours of nanocomposite coatings are closely related with boron carbide nanoparticle content. Nanocomposite coating with low B4C content shows somewhat (slight) increased microhardness and wear resistance than pure titanium substrate, while nanocomposite coating with high B4C content has much better (sharp increase) wear resistance than pure titanium substrate. The effect of B4C nanoparticles on microhardness and wear resistance was discussed. PMID:22962832

  1. Nanostructured Titanium Oxide Film- And Membrane-Based Photocatalysis For Water Treatment

    EPA Science Inventory

    Titanium Oxide (TiO2) photocatalysis, one of the ultraviolet (UV)-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness ...

  2. Hydrothermal growth and characterization of titanium dioxide nanostructures for use in dye sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Sorge, Judith D.

    As the world's energy needs continue to grow, next generation photovoltaic cells are in high demand because they offer the possibility of an inexpensive alternative to current energy production techniques. Dye sensitized solar cells (DSSC's), utilize common materials and low cost commercialization techniques, which make them a compelling choice for research in this area. This research focuses on the titanium dioxide coating, which transfers electrons from the photoactive dye to the electrode. 3-4% efficient DSSC's using doctor bladed titanium dioxide coatings with a specific surface area of 55-60m2/g have been demonstrated in our laboratory. To enhance the efficiency of these cells, both the surface area and the electron conduction of the titania layer must be optimized. This has been done by utilizing high aspect ratio nanoparticles of titania instead of mesoporous layers formed with spherical particles. Anodization of titanium metal or anodic alumina membrane templating are common ways to produce nanorods, but involve complex processes leading toward expensive commercialization. This research instead focuses on the hydrothermal growth of nanofibrous titania on a titanium metal substrate, removing the need for dispersion and deposition procedures as well as using a low temperature processing method. Depending upon the formulation utilized, a variety of structures can be produced, from thick carpets of nanofiber strands to large platelets. The composition and morphology of the products have been characterized with respect to the growth conditions using electron microscopy, energy dispersive spectroscopy and x-ray diffraction. The compositional analysis is used to investigate the complicated reaction mechanisms in the system. Coatings of titania nanotubes were then tested in the DSSC's, as were those with the titanium metal substrate acting as the photo anode. Modeling the geometric parameters of the different pore structures of the coatings helps us to understand

  3. Synthesis and characterization of nanostructured titanium carbide for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Singh, Paviter; Singh, Harwinder; Singh, Bikramjeet; Kaur, Manpreet; Kaur, Gurpreet; Kumar, Manjeet; Bala, Rajni; Kumar, Akshay

    2016-04-01

    Titanium carbide (TiC) nanoparticles have been successfully synthesized by carbo-thermic reaction of titanium and acetone at 800 °C. This method is relatively low temperature synthesis route. It can be used for large scale production of TiC. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA) techniques. XRD analysis confirmed the formation of single phase TiC. XRD analysis confirmed that the particles are spherical in shape with an average particle size of 13 nm. DTA analysis shows that the phase is stable upto 900 °C and the material can be used for high temperature applications.

  4. Enhanced apatite-forming ability and cytocompatibility of porous and nanostructured TiO2/CaSiO3 coating on titanium.

    PubMed

    Hu, Hongjie; Qiao, Yuqin; Meng, Fanhao; Liu, Xuanyong; Ding, Chuanxian

    2013-01-01

    To improve the bioactivity and cytocompatibility of biomedical titanium dioxide coating, many efforts have been made to modify its surface composition and topography. Meanwhile, CaSiO(3) was commonly investigated as coating material on titanium implants for fast fixation and firm implant-bone attachment due to its demonstrated bioactivity and osteointegration. In this work, gradient TiO(2)/CaSiO(3) coating on titanium was prepared by a two-step procedure, in which porous and nanostructured TiO(2) coating on titanium was prepared by plasma electrolytic oxidation in advance, and then needle and flake-like CaSiO(3) nanocrystals were deposited on the TiO(2) coating surface by electron beam evaporation. In view of the potential clinical applications, apatite-forming ability of the TiO(2)/CaSiO(3) coating was evaluated by simulated body fluid (SBF) immersion tests, and MG63 cells were cultured on the surface of the coating to investigate its cytocompatibility. The results show that deposition of CaSiO(3) significantly enhanced the apatite-forming ability of nanostructured TiO(2) coating in SBF. Meanwhile, the MG63 cells on TiO(2)/CaSiO(3) coating show higher proliferation rate and vitality than that on TiO(2) coating. In conclusion, the porous and nanostructured TiO(2)/CaSiO(3) coating on titanium substrate with good apatite-forming ability and cytocompatibility is a potential candidate for bone tissue engineering and implant coating. PMID:22796775

  5. Picosecond ultrasonic study of surface acoustic waves on titanium nitride nanostructures

    SciTech Connect

    Bjornsson, M. M.; Connolly, A. B.; Mahat, S.; Rachmilowitz, B. E.; Daly, B. C.; Antonelli, G. A.; Myers, A.; Singh, K. J.; Yoo, H. J.; King, S. W.

    2015-03-07

    We have measured surface acoustic waves on nanostructured TiN wires overlaid on multiple thin films on a silicon substrate using the ultrafast pump-probe technique known as picosecond ultrasonics. We find a prominent oscillation in the range of 11–54 GHz for samples with varying pitch ranging from 420 nm down to 168 nm. We find that the observed oscillation increases monotonically in frequency with decrease in pitch, but that the increase is not linear. By comparing our data to two-dimensional mechanical simulations of the nanostructures, we find that the type of surface oscillation to which we are sensitive changes depending on the pitch of the sample. Surface waves on substrates that are loaded by thin films can take multiple forms, including Rayleigh-like waves, Sezawa waves, and radiative (leaky) surface waves. We describe evidence for detection of modes that display characteristics of these three surface wave types.

  6. Anti-infection activity of nanostructured titanium percutaneous implants with a postoperative infection model

    NASA Astrophysics Data System (ADS)

    Tan, Jing; Li, Yiting; Liu, Zhiyuan; Qu, Shuxin; Lu, Xiong; Wang, Jianxin; Duan, Ke; Weng, Jie; Feng, Bo

    2015-07-01

    The titanium percutaneous implants were widely used in clinic; however, they have an increased risk of infection since they breach the skin barrier. Lack of complete skin integration with the implants can cause infection and implant removal. In this work, three titania nanotubes (TNT) with different diameters, 50 nm (TNT-50), 100 nm (TNT-100) and 150 nm (TNT-150) arrays were prepared on titanium surfaces by anodization, pure titanium (pTi) was used as control. Samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle analysis. The antibacterial efficiency of TNT was evaluated in vitro against Staphylococcus aureus under the visible light. The results indicated that TNT-100 had the highest antibacterial efficiency under the visible light. Subsequently, TNT implants and pTi implants were placed subcutaneously to the dorsum of New Zealand White rabbits, 108 CFU S. aureus was inoculated into the implant sites 4 h after surgery. The TNF-alpha and IL-1alpha were determined using enzyme linked immunoassay (ELISA). TNT implants revealed less inflammatory factor release than pTi implants with or without injected S. aureus liquid. According to the histological results, the TNT implants displayed excellent tissue integration. Whereas, pTi implants were surrounded with fibrotic capsule, and the skin tissue was almost separated from the implant surface. Therefore, the TNT significantly inhibited the infection risk and enhanced tissue integration of the percutaneous implants compared to pTi. The immersion test in the culture medium suggested that one of causes be probably more proteins adsorbed on TNT than on pTi.

  7. Photoactivation of the processes of formation of nanostructures by local anodic oxidation of a titanium film

    SciTech Connect

    Ageev, O. A.; Alyab'eva, N. I.; Konoplev, B. G. Polyakov, V. V.; Smirnov, V. A.

    2010-12-15

    Experimental results on the conditions of activation of probe nanolithography of a thin titanium film by means of local anodic oxidation are reported. It is established that ultraviolet stimulation reduces the geometric dimensions of nanometric oxide structures. The stimulation is accompanied by an increase in the amplitude and duration of the threshold voltage pulse, correspondingly, from 6 to 7 V and from 50 to 100 ms at the relative humidity 50%. The experimental data on the effect of the cantilever coating material and substrate temperature on the geometric dimensions of nanometric oxide structures are reported.

  8. Demonstration of periodic nanostructure formation with less ablation by double-pulse laser irradiation on titanium

    NASA Astrophysics Data System (ADS)

    Furukawa, Yuki; Sakata, Ryoichi; Konishi, Kazuki; Ono, Koki; Matsuoka, Shusaku; Watanabe, Kota; Inoue, Shunsuke; Hashida, Masaki; Sakabe, Shuji

    2016-06-01

    By pairing femtosecond laser pulses (duration ˜40 fs and central wavelength ˜810 nm) at an appropriate time interval, a laser-induced periodic surface structure (LIPSS) is formed with much less ablation than one formed with a single pulse. On a titanium plate, a pair of laser pulses with fluences of 70 and 140 mJ/cm2 and a rather large time interval (>10 ps) creates a LIPSS with an interspace of 600 nm, the same as that formed by a single pulse of 210 mJ/cm2, while the double pulse ablates only 4 nm, a quarter of the ablation depth of a single pulse.

  9. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    NASA Astrophysics Data System (ADS)

    Klimenov, V. A.; Kurgan, K. A.; Chumaevskii, A. V.; Klopotov, A. A.; Gnyusov, S. F.

    2016-01-01

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  10. Tunable top-down fabrication and functional surface coating of single-crystal titanium dioxide nanostructures and nanoparticles.

    PubMed

    Ha, Seungkyu; Janissen, Richard; Ussembayev, Yera Ye; van Oene, Maarten M; Solano, Belen; Dekker, Nynke H

    2016-05-19

    Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and yet-to-be-developed applications. However, the implementation of single-crystal TiO2 has been hampered by challenges in its fabrication and subsequent surface functionalization. Here, we introduce a novel top-down approach that allows for batch fabrication of uniform high-aspect-ratio single-crystal TiO2 nanostructures with targeted sidewall profiles. We complement our fabrication approach with a functionalization strategy that achieves dense, uniform, and area-selective coating with a variety of biomolecules. This allows us to fabricate single-crystal rutile TiO2 nanocylinders tethered with individual DNA molecules for use as force- and torque-transducers in an optical torque wrench. These developments provide the means for increased exploitation of the superior material properties of single-crystal TiO2 at the nanoscale. PMID:27160731

  11. Nanostructured anatase-titanium dioxide based platform for application to microfluidics cholesterol biosensor

    NASA Astrophysics Data System (ADS)

    Azahar Ali, Md.; Srivastava, Saurabh; Solanki, Pratima R.; Varun Agrawal, Ved; John, Renu; Malhotra, Bansi D.

    2012-08-01

    We report results of studies relating to the fabrication of a microfluidics cholesterol sensor based on nanocrystalline anatase-titanium dioxide (ant-TiO2) film deposited onto indium tin oxide (ITO) glass. The results of response studies (optimized under the flow rate of 30 μl/min) conducted on cholesterol oxidase (ChOx) immobilized onto crystalline ant-TiO2 nanoparticles (˜27 nm)/ITO microfluidics electrode reveal linearity as 1.3 to 10.3 mM and improved sensitivity of 94.65 μA/mM/cm2. The observed low value of Km (0.14 mM) indicates high affinity of ChOx to cholesterol. No significant changes in current response of this microfluidics sensor are measured in the presence of different interferents.

  12. Hierarchical micro/nanostructured titanium with balanced actions to bacterial and mammalian cells for dental implants

    PubMed Central

    Zhu, Yu; Cao, Huiliang; Qiao, Shichong; Wang, Manle; Gu, Yingxin; Luo, Huiwen; Meng, Fanhao; Liu, Xuanyong; Lai, Hongchang

    2015-01-01

    A versatile strategy to endow dental implants with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat implant-related infection. Silver nanoparticles (Ag NPs) have been utilized as a highly effective and broad-spectrum antibacterial agent for surface modification of biomedical devices. However, the high mobility and subsequent hazardous effects of the particles on mammalian cells may limit its practical applications. Thus, Ag NPs were immobilized on the surface of sand-blasted, large grit, and acid-etched (SLA) titanium by manipulating the atomic-scale heating effect of silver plasma immersion ion implantation. The silver plasma immersion ion implantation-treated SLA surface gave rise to both good antibacterial activity and excellent compatibility with mammalian cells. The antibacterial activity rendered by the immobilized Ag NPs was assessed using Fusobacterium nucleatum and Staphylococcus aureus, commonly suspected pathogens for peri-implant disease. The immobilized Ag NPs offered a good defense against multiple cycles of bacteria attack in both F. nucleatum and S. aureus, and the mechanism was independent of silver release. F. nucleatum showed a higher susceptibility to Ag NPs than S. aureus, which might be explained by the presence of different wall structures. Moreover, the immobilized Ag NPs had no apparent toxic influence on the viability, proliferation, and differentiation of rat bone marrow mesenchymal stem cells. These results demonstrated that good bactericidal activity could be obtained with very small quantities of immobilized Ag NPs, which were not detrimental to the mammalian cells involved in the osseointegration process, and promising for titanium-based dental implants with commercial SLA surfaces. PMID:26604743

  13. Nanostructured titanium/diamond-like carbon multilayer films: deposition, characterization, and applications.

    PubMed

    Dwivedi, Neeraj; Kumar, Sushil; Malik, Hitendra K

    2011-11-01

    Titanium/diamond-like carbon multilayer (TDML) films were deposited using a hybrid system combining radio frequency (RF)-sputtering and RF-plasma enhanced chemical vapor deposition (PECVD) techniques under a varied number of Ti/diamond-like carbon (DLC) bilayers from 1 to 4, at high base pressure of 1 × 10(-3) Torr. The multilayer approach was used to create unique structures such as nanospheres and nanorods in TDML films, which is confirmed by scanning electron microscopy (SEM) analysis and explained by a hypothetical model. Surface composition was evaluated by X-ray photoelectron spectroscopy (XPS), whereas energy dispersive X-ray analysis (EDAX) and time-of-flight secondary ion mass spectrometer (ToF-SIMS) measurements were performed to investigate the bulk composition. X-ray diffraction (XRD) was used to evaluate the phase and crystallinity of the deposited TDML films. Residual stress in these films was found to be significantly low. These TDML films were found to have excellent nanomechanical properties with maximum hardness of 41.2 GPa. In addition, various nanomechanical parameters were calculated and correlated with each other. Owing to metallic interfacial layer of Ti in multilayer films, the optical properties, electrical properties, and photoluminescence were improved significantly. Due to versatile nanomechanical properties and biocompatibility of DLC and DLC based films, these TDML films may also find applications in biomedical science. PMID:21942626

  14. Fabrication and characterization of transparent conducting titanium-zinc oxide nanostructured thin films

    NASA Astrophysics Data System (ADS)

    Lu, Zhou; Long, Lu; Zhong, Zhi-you; Hou, Jin; Yang, Chun-yong; Gu, Jin-hua; Long, Hao

    2016-03-01

    Nano transparent conducting titanium-zinc oxide (Ti-ZnO) thin films were prepared on glass substrates by radio frequency (RF) magnetron sputtering technique. The deposited films are characterized by X-ray diffraction (XRD), four-probe meter and UV-visible spectrophotometer. The effects of Ti-doping content on the structural, optical and electrical properties of the films are investigated. The XRD results show that the obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The structural and optoelectronic characteristics of the deposited films are subjected to the Ti-doping content. The Ti-ZnO sample fabricated with the Ti-doping content of 3% (weight percentage) possesses the best crystallinity and optoelectronic performance, with the highest degree of preferred (002) orientation of 99.87%, the largest crystallite size of 83.2 nm, the minimum lattice strain of 6.263×10-4, the highest average visible transmittance of 88.8%, the lowest resistivity of 1.18×10-3 Ω·cm and the maximum figure of merit ( FOM) of 7.08×103 Ω-1·cm-1. Furthermore, the optical bandgaps of the films are evaluated by extrapolation method and observed to be an increasing tendency with the increase of the Ti-doping content.

  15. Nanostructured titanium nitride as a novel cathode for high performance lithium/dissolved polysulfide batteries

    NASA Astrophysics Data System (ADS)

    Mosavati, Negar; Chitturi, Venkateswara Rao; Salley, Steven O.; Ng, K. Y. Simon

    2016-07-01

    Lithium-sulfur (Lisbnd S) batteries could potentially revolutionize the rechargeable battery market due to their high energy density and low cost. However, low active material utilization, electrode volumetric expansion and a high rate of capacity fade due to the dissolution of lithium polysulfide intermediates in the liquid electrolyte are the main challenges facing further Lisbnd S battery development. Here, we enhanced Lisbnd S batteries active material utilization and decreased the volumetric expansion by using the lithium/dissolved polysulfide configuration. Moreover, a novel class of cathode materials, Titanium Nitride (TiN), was developed for polysulfide conversion reactions. The surface chemical environment of the TiN has been investigated by X-ray photoelectron spectroscopy (XPS) analysis. The existence of Ssbnd Tisbnd N bonding at the cathode electrode surface was observed, which indicates the strong interactions between TiN and polysulfides. Therefore, the TiN electrode retains the sulfur species on the cathode surface, minimizing the active material and surface area loss and consequently, improves the capacity retention. The resultant cells demonstrated a high initial capacity of 1524 mAh g-1 and a good capacity retention for 100 cycles at a C/10 current rate.

  16. Tunable top-down fabrication and functional surface coating of single-crystal titanium dioxide nanostructures and nanoparticles

    NASA Astrophysics Data System (ADS)

    Ha, Seungkyu; Janissen, Richard; Ussembayev, Yera Ye.; van Oene, Maarten M.; Solano, Belen; Dekker, Nynke H.

    2016-05-01

    Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and yet-to-be-developed applications. However, the implementation of single-crystal TiO2 has been hampered by challenges in its fabrication and subsequent surface functionalization. Here, we introduce a novel top-down approach that allows for batch fabrication of uniform high-aspect-ratio single-crystal TiO2 nanostructures with targeted sidewall profiles. We complement our fabrication approach with a functionalization strategy that achieves dense, uniform, and area-selective coating with a variety of biomolecules. This allows us to fabricate single-crystal rutile TiO2 nanocylinders tethered with individual DNA molecules for use as force- and torque-transducers in an optical torque wrench. These developments provide the means for increased exploitation of the superior material properties of single-crystal TiO2 at the nanoscale.Titanium dioxide (TiO2) is a key component of diverse optical and electronic applications that exploit its exceptional material properties. In particular, the use of TiO2 in its single-crystalline phase can offer substantial advantages over its amorphous and polycrystalline phases for existing and yet-to-be-developed applications. However, the implementation of single-crystal TiO2 has been hampered by challenges in its fabrication and subsequent surface functionalization. Here, we introduce a novel top-down approach that allows for batch fabrication of uniform high-aspect-ratio single-crystal TiO2 nanostructures with targeted sidewall profiles. We complement our fabrication approach with a functionalization strategy that achieves dense, uniform, and area-selective coating with a variety of biomolecules. This allows us to fabricate single-crystal rutile

  17. Decreased Staphylococcus aureus and increased osteoblast density on nanostructured electrophoretic-deposited hydroxyapatite on titanium without the use of pharmaceuticals

    PubMed Central

    Mathew, Dennis; Bhardwaj, Garima; Wang, Qi; Sun, Linlin; Ercan, Batur; Geetha, Manisavagam; Webster, Thomas J

    2014-01-01

    Background Plasma-spray deposition of hydroxyapatite on titanium (Ti) has proven to be a suboptimal solution to improve orthopedic-implant success rates, as demonstrated by the increasing number of orthopedic revision surgeries due to infection, implant loosening, and a myriad of other reasons. This could be in part due to the high heat involved during plasma-spray deposition, which significantly increases hydroxyapatite crystal growth into the nonbiologically inspired micron regime. There has been a push to create nanotopographies on implant surfaces to mimic the physiological nanostructure of native bone and, thus, improve osteoblast (bone-forming cell) functions and inhibit bacteria functions. Among the several techniques that have been adopted to develop nanocoatings, electrophoretic deposition (EPD) is an attractive, versatile, and effective material-processing technique. Objective The in vitro study reported here aimed to determine for the first time bacteria responses to hydroxyapatite coated on Ti via EPD. Results There were six and three times more osteoblasts on the electrophoretic-deposited hydroxyapatite on Ti compared with Ti (control) and plasma-spray-deposited hydroxyapatite on Ti after 5 days of culture, respectively. Impressively, there were 2.9 and 31.7 times less Staphylococcus aureus on electrophoretic-deposited hydroxyapatite on Ti compared with Ti (control) and plasma-spray-deposited hydroxyapatite on Ti after 18 hours of culture, respectively. Conclusion Compared with uncoated Ti and plasma-sprayed hydroxyapatite coated on Ti, the results provided significant promise for the use of EPD to improve bone-cell density and be used as an antibacterial coating without resorting to the use of antibiotics. PMID:24748789

  18. Superposition of nanostructures on microrough titanium-aluminum-vanadium alloy surfaces results in an altered integrin expression profile in osteoblasts.

    PubMed

    Gittens, Rolando A; Olivares-Navarrete, Rene; Hyzy, Sharon L; Sandhage, Kenneth H; Schwartz, Zvi; Boyan, Barbara D

    2014-08-01

    Recent studies of new surface modifications that superimpose well-defined nanostructures on microrough implants, thereby mimicking the hierarchical complexity of native bone, report synergistically enhanced osteoblast maturation and local factor production at the protein level compared to growth on surfaces that are smooth, nanorough, or microrough. Whether the complex micro/nanorough surfaces enhance the osteogenic response by triggering similar patterns of integrin receptors and their associated signaling pathways as with well-established microrough surfaces, is not well understood. Human osteoblasts (hOBs) were cultured until confluent for gene expression studies on tissue culture polystyrene (TCPS) or on titanium alloy (Ti6Al4V) disks with different surface topographies: smooth, nanorough, microrough, and micro/nanorough surfaces. mRNA expression of osteogenesis-related markers such as osteocalcin (BGLAP) and bone sialoprotein (BSP), bone morphogenetic protein 2 (BMP2), BMP4, noggin (NOG) and gremlin 1 (GREM1) were all higher on microrough and micro/nanorough surfaces, with few differences between them, compared to smooth and nanorough groups. Interestingly, expression of integrins α1 and α2, which interact primarily with collagens and laminin and have been commonly associated with osteoblast differentiation on microrough Ti and Ti6Al4V, were expressed at lower levels on micro/nanorough surfaces compared to microrough ones. Conversely, the αv subunit, which binds ligands such as vitronectin, osteopontin, and bone sialoprotein among others, had higher expression on micro/nanorough surfaces concomitantly with regulation of the β3 mRNA levels on nanomodified surfaces. These results suggest that the maturation of osteoblasts on micro/nanorough surfaces may be occurring through different integrin engagement than those established for microrough-only surfaces. PMID:25158204

  19. Influence of heat treatment on morphological changes of nano-structured titanium oxide formed by anodic oxidation of titanium in acidic fluoride solution.

    PubMed

    Neupane, Madhav Prasad; Park, Il Song; Lee, Min Ho; Bae, Tae Sung; Watari, Fumio

    2009-01-01

    TiO(2) nanotube array (TN) on titanium plate was fabricated by using an electrochemical method. The crystal structure and surface morphology of TN array was examined by X-ray diffraction (XRD) and Field Emission Scanning Electronic Microscopy (FE-SEM), respectively. The stability of the nanotube structure and crystal phase transition was studied at different temperatures in dry oxygen ambient. The as-deposited films were found to be amorphous. The tubes crystallized in the anatase phase at a temperature of 450 degrees C. Anatase crystallites formed inside the tubes walls was transformed completely to rutile at 500 degrees C in dry environment. With the heating temperature increased the intensity of rutile peak increased with decrease in reflection from titanium. Intense rutile peak was observed at 600 degrees C. The average pore diameter as calculated from FE-SEM images was 50-100 nm. At higher temperature tubular structure completely collapsed leaving dense rutile crystallites. A model was proposed to explain the formation mechanism of TN fabricated on titanium plate in HF/H(2)SO(4) electrolyte. PMID:19458449

  20. In Situ Generation of Electron Donor to Assist Signal Amplification on Porphyrin-Sensitized Titanium Dioxide Nanostructures for Ultrasensitive Photoelectrochemical Immunoassay.

    PubMed

    Shu, Jian; Qiu, Zhenli; Zhuang, Junyang; Xu, Mingdi; Tang, Dianping

    2015-10-28

    An ultrasensitive photoelectrochemical (PEC) immunoassay protocol for quantitative detection of low-abundant proteins at a low potential was designed by utilizing porphyrin-sensitized titanium dioxide (TiO2) nanostructures. Experimental results demonstrated that the water-soluble 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) could be bound onto titanium dioxide via the sulfonic group. TSPP-sensitized TiO2 nanostructures exhibited better photoelectrochemical responses and stability in comparison with TiO2 nanoparticles alone under continuous illumination. Using carcinoembryonic antigen (CEA) as a model analyte, a typical PEC immunosensor by using TSPP-TiO2 as the affinity support of anti-CEA capture antibody (Ab1) to facilitate the improvement of photocurrent response was developed. Bioconjugates of secondary antibody and glucose oxidase with gold nanoparticles (Ab2/GOx-AuNPs) was introduced by an antigen-antibody immunoreaction. AuNP acted as a powerful scaffold to bind with bioactive molecules, while GOx catalyzed glucose to in situ generate hydrogen peroxide (H2O2). The generated H2O2 as a sacrificial electron donor could be oxidized by the photogenerated holes to assist the signal amplification at a low potential under light excitation, thus eliminating interference from other species coexisting in the samples. Under optimal conditions, the PEC immunosensor showed a good linear relationship ranging from 0.02 to 40 ng mL(-1) with a low detection limit of 6 pg mL(-1) CEA. The precision, reproducibility, and specificity were acceptable. In addition, the method accuracy was also evaluated for quantitatively monitoring human serum samples, giving results matching with the referenced CEA ELISA kit. PMID:26451956

  1. Nanostructured model implants for in vivo studies: influence of well-defined nanotopography on de novo bone formation on titanium implants

    PubMed Central

    Ballo, Ahmed; Agheli, Hossein; Lausmaa, Jukka; Thomsen, Peter; Petronis, Sarunas

    2011-01-01

    An implantable model system was developed to investigate the effects of nanoscale surface properties on the osseointegration of titanium implants in rat tibia. Topographical nanostructures with a well-defined shape (semispherical protrusions) and variable size (60 nm, 120 nm and 220 nm) were produced by colloidal lithography on the machined implants. Furthermore, the implants were sputter-coated with titanium to ensure a uniform surface chemical composition. The histological evaluation of bone around the implants at 7 days and 28 days after implantation was performed on the ground sections using optical and scanning electron microscopy. Differences between groups were found mainly in the new bone formation process in the endosteal and marrow bone compartments after 28 days of implantation. Implant surfaces with 60 nm features demonstrated significantly higher bone-implant contact (BIC, 76%) compared with the 120 nm (45%) and control (57%) surfaces. This effect was correlated to the higher density and curvature of the 60 nm protrusions. Within the developed model system, nanoscale protrusions could be applied and systematically varied in size in the presence of microscale background roughness on complex screw-shaped implants. Moreover, the model can be adapted for the systematic variation of surface nanofeature density and chemistry, which opens up new possibilities for in vivo studies of various nanoscale surface-bone interactions. PMID:22267926

  2. Semi-transparent ordered TiO2 nanostructures prepared by anodization of titanium thin films deposited onto the FTO substrate

    NASA Astrophysics Data System (ADS)

    Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Skowroński, Łukasz; Karczewski, Jakub; Siuzdak, Katarzyna

    2016-09-01

    In a significant amount of cases, the highly ordered TiO2 nanotube arrays grow through anodic oxidation of a titanium metal plate immersed in electrolyte containing fluoride ions. However, for some practical applications, e.g. solar cells or electrochromic windows, the semi-transparent TiO2 formed directly on the transparent, conductive substrate is very much desired. This work shows that high-quality Ti coating could be formed at room temperature using an industrial magnetron sputtering system within 50 min. Under optimized conditions, the anodization process was performed on 2 μm titanium films deposited onto the FTO (fluorine-tin-oxide) support. Depending on the electrolyte type, highly ordered tubular or porous titania layers were obtained. The fabricated samples, after their thermal annealing, were investigated using scanning electron microscopy, Raman spectroscopy and UV-vis spectroscopy in order to investigate their morphology, crystallinity and absorbance ability. The photocurrent response curves indicate that materials are resistant to the photocorrosion process and their activity is strongly connected to optical properties. The most transparent TiO2 films were fabricated when Ti was anodized in water electrolyte, whereas the highest photocurrent densities (12 μA cm-2) were registered for titania received after Ti anodization in ethylene glycol solution. The obtained results are of significant importance in the production of thin, semi-transparent titania nanostructures on a commercial scale.

  3. Hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite positive electrode materials for rechargeable lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Zegeye, Tilahun Awoke; Kuo, Chung-Feng Jeffrey; Wotango, Aselefech Sorsa; Pan, Chun-Jern; Chen, Hung-Ming; Haregewoin, Atetegeb Meazah; Cheng, Ju-Hsiang; Su, Wei-Nien; Hwang, Bing-Joe

    2016-08-01

    Herein, we design hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite (MC-Meso C-doped TiO2/S) as a positive electrode material for lithium-sulfur batteries. The hybrid MC-Meso C-doped TiO2 host material is produced by a low-cost, hydrothermal and annealing process. The resulting conductive material shows dual microporous and mesoporous behavior which enhances the effective trapping of sulfur and polysulfides. The hybrid MC-Meso C-doped TiO2/S composite material possesses rutile TiO2 nanotube structure with successful carbon doping while sulfur is uniformly distributed in the hybrid MC-Meso C-doped TiO2 composite materials after the melt-infusion process. The electrochemical measurement of the hybrid material also shows improved cycle stability and rate performance with high sulfur loading (61.04%). The material delivers an initial discharge capacity of 802 mAh g-1 and maintains it at 578 mAh g-1 with a columbic efficiency greater than 97.1% after 140 cycles at 0.1 C. This improvement is thought to be attributed to the unique hybrid nanostructure of the MC-Meso C-doped TiO2 host and the good dispersion of sulfur in the narrow pores of the MC spheres and the mesoporous C-doped TiO2 support.

  4. Hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite positive electrode materials for rechargeable lithium-sulfur batteries

    NASA Astrophysics Data System (ADS)

    Zegeye, Tilahun Awoke; Kuo, Chung-Feng Jeffrey; Wotango, Aselefech Sorsa; Pan, Chun-Jern; Chen, Hung-Ming; Haregewoin, Atetegeb Meazah; Cheng, Ju-Hsiang; Su, Wei-Nien; Hwang, Bing-Joe

    2016-08-01

    Herein, we design hybrid nanostructured microporous carbon-mesoporous carbon doped titanium dioxide/sulfur composite (MC-Meso C-doped TiO2/S) as a positive electrode material for lithium-sulfur batteries. The hybrid MC-Meso C-doped TiO2 host material is produced by a low-cost, hydrothermal and annealing process. The resulting conductive material shows dual microporous and mesoporous behavior which enhances the effective trapping of sulfur and polysulfides. The hybrid MC-Meso C-doped TiO2/S composite material possesses rutile TiO2 nanotube structure with successful carbon doping while sulfur is uniformly distributed in the hybrid MC-Meso C-doped TiO2 composite materials after the melt-infusion process. The electrochemical measurement of the hybrid material also shows improved cycle stability and rate performance with high sulfur loading (61.04%). The material delivers an initial discharge capacity of 802 mAh g-1 and maintains it at 578 mAh g-1 with a columbic efficiency greater than 97.1% after 140 cycles at 0.1 C. This improvement is thought to be attributed to the unique hybrid nanostructure of the MC-Meso C-doped TiO2 host and the good dispersion of sulfur in the narrow pores of the MC spheres and the mesoporous C-doped TiO2 support.

  5. Neodymium-doped glasses for waveguide lasers

    NASA Astrophysics Data System (ADS)

    Church, Kenneth H.; Zanoni, Raymond; Sapak, David L.; Hayden, Joseph S.

    1994-10-01

    We report recent results from our work on the fabrication of neodymium waveguide lasers. Several neodymium doped glasses. APG-1, LG-680, BK 7 and S 3 made by Schott Glass Technologies, Inc. were studied as candidates for use as waveguide lasers. It was found that S 3, a standard ophthalmic glass, had the best ion-exchange properties of any of the glasses studied. A waveguide laser was successfully made using the neodymium doped S 3 glass.

  6. Nanostructured Graphene-Titanium Dioxide Composites Synthesized by a Single-Step Aerosol Process for Photoreduction of Carbon Dioxide

    PubMed Central

    Wang, Wei-Ning; Jiang, Yi; Fortner, John D.; Biswas, Pratim

    2014-01-01

    Abstract Photocatalytic reduction of carbon dioxide (CO2) to hydrocarbons by using nanostructured materials activated by solar energy is a promising approach to recycling CO2 as a fuel feedstock. CO2 photoreduction, however, suffers from low efficiency mainly due to the inherent drawback of fast electron-hole recombination in photocatalysts. This work reports the synthesis of nanostructured composites of titania (TiO2) nanoparticles (NPs) encapsulated by reduced graphene oxide (rGO) nanosheets via an aerosol approach. The role of synthesis temperature and TiO2/GO ratio in CO2 photoreduction was investigated. As-prepared nanocomposites demonstrated enhanced CO2 conversion performance as compared with that of pristine TiO2 NPs due to the strong electron trapping capability of the rGO nanosheets. PMID:25053879

  7. Q-Switching in a Neodymium Laser

    ERIC Educational Resources Information Center

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

    2012-01-01

    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  8. Equilibrium state of anatase to rutile transformation for nano-structured Titanium Dioxide powder using polymer template method.

    NASA Astrophysics Data System (ADS)

    Dam, Tapabrata; Jena, Sidhartha S.; Pradhan, Dillip K.

    2016-02-01

    In this work we report the novel synthesis procedure of phase-pure nano-structured titania in anatase phase using polyacrylamide gel based polymer template method. The evolution of rutile phased titania with increasing temperature has also been investigated. The synthesized nano-materials are characterized using X-ray diffraction, Brunauer - Emmett - Teller surface analysis technique and Scanning electron microscopy. We have used dual phase Rietveld refinement method to analyse the X-Ray diffraction data to get clear picture of crystallographic information of the prepared samples.

  9. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    NASA Astrophysics Data System (ADS)

    Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

    2016-02-01

    The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  10. Nanostructures having crystalline and amorphous phases

    SciTech Connect

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  11. Biomechanical, histological, and ultrastructural analyses of laser micro- and nano-structured titanium alloy implants: a study in rabbit.

    PubMed

    Palmquist, Anders; Lindberg, Fredrik; Emanuelsson, Lena; Brånemark, Rickard; Engqvist, Håkan; Thomsen, Peter

    2010-03-15

    The aim of this study was to evaluate the biomechanical properties and ultrastructure of the bone response of partly laser-modified Ti6Al4V implants compared with turned, machined implants after 8 weeks in rabbit. The surface analyses performed with interference microscopy and electron microscopy showed increased surface topography with micro- and nano-sized surface features as well as increased oxide thickness of the modified surface. The biomechanical testing demonstrated a 270% increase in torque value for the surface modified implants compared with the control implants. Histological evaluation of ground sections of specimens subjected to biomechanical testing revealed ongoing bone formation and remodeling. A histological feature exclusively observed at the laser-modified surface was the presence of fracture in the mineralized bone rather than at the interface between the bone and implant. Transmission electron microscopy (TEM) was performed on Focused Ion Beam (FIB) prepared samples of the intact bone-implant interface, demonstrating a direct contact between nanocrystalline hydroxyapatite and the oxide of the laser-modified implant surface. In conclusion, laser-modified titanium alloy implants have significantly stronger bone anchorage compared with machined implants and show no adverse tissue reactions. PMID:19425049

  12. Femtosecond laser nanostructuring of titanium metal towards fabrication of low-reflective surfaces over broad wavelength range

    NASA Astrophysics Data System (ADS)

    Dar, Mudasir H.; Kuladeep, R.; Saikiran, V.; Narayana Rao, D.

    2016-05-01

    We investigated experimentally the formation of laser induced periodic surface structures (LIPSS) on titanium (Ti) metal upon irradiation with linearly polarized Ti:Sapphire femtosecond (fs) laser pulses of ∼110 fs pulse width and 800 nm wavelength in air and water environments. It is observed that initially formed random and sparsely distributed nano-roughness (nanoholes, nanoparticles and nanoprotrusions) gets periodically structured with increase in number of laser pulses. In air at lower fluence, we observed the formation of high spatial frequency-LIPSS (HSFL) oriented parallel to the laser polarization direction, whereas at higher fluence formation of low spatial frequency-LIPSS (LSFL) were observed that are oriented perpendicular to the incident laser polarization. In water two types of subwavelength structures were observed, one with spatial periodicity of ∼λ/15 and oriented parallel to laser polarization, while the other oriented perpendicular to laser polarization with feature size of λ/4. The optimal conditions for fabricating periodic sub-wavelength structures are determined by controlling the fluence and pulse number. The fs laser induced surface modifications were found to suppress the specular reflection of the Ti surface over a wide wavelength range of 250-2000 nm to a great extent.

  13. ZnO nanoparticle incorporated nanostructured metallic titanium for increased mesenchymal stem cell response and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Elizabeth, Elmy; Baranwal, Gaurav; Krishnan, Amit G.; Menon, Deepthy; Nair, Manitha

    2014-03-01

    Recent trends in titanium implants are towards the development of nanoscale topographies that mimic the nanoscale properties of bone tissue. Although the nanosurface promotes the integration of osteoblast cells, infection related problems can also occur, leading to implant failure. Therefore it is imperative to reduce bacterial adhesion on an implant surface, either with or without the use of drugs/antibacterial agents. Herein, we have investigated two different aspects of Ti surfaces in inhibiting bacterial adhesion and concurrently promoting mammalian cell adhesion. These include (i) the type of nanoscale topography (Titania nanotube (TNT) and Titania nanoleaf (TNL)) and (ii) the presence of an antibacterial agent like zinc oxide nanoparticles (ZnOnp) on Ti nanosurfaces. To address this, periodically arranged TNT (80-120 nm) and non-periodically arranged TNL surfaces were generated by the anodization and hydrothermal techniques respectively, and incorporated with ZnOnp of different concentrations (375 μM, 750 μM, 1.125 mM and 1.5 mM). Interestingly, TNL surfaces decreased the adherence of staphylococcus aureus while increasing the adhesion and viability of human osteosarcoma MG63 cell line and human mesenchymal stem cells, even in the absence of ZnOnp. In contrast, TNT surfaces exhibited an increased bacterial and mammalian cell adhesion. The influence of ZnOnp on these surfaces in altering the bacterial and cell adhesion was found to be concentration dependent, with an optimal range of 375-750 μM. Above 750 μM, although bacterial adhesion was reduced, cellular viability was considerably affected. Thus our study helps us to infer that nanoscale topography by itself or its combination with an optimal concentration of antibacterial ZnOnp would provide a differential cell behavior and thereby a desirable biological response, facilitating the long term success of an implant.

  14. Electrolysis of neodymium oxide. Final report for the period August 19, 1991 through February 28, 1997

    SciTech Connect

    Keller, R.; Larimer, K.T.

    1997-05-01

    The objective of this research was to develop an electrolytic process for the continuous and economic production of neodymium alloys from neodymium oxide. The electrolysis of neodymium oxide continued to show promise for implementation as a low-cost process to produce high- quality neodymium or neodymium-iron alloy.

  15. Radio-Purification of Neodymium Chloride

    SciTech Connect

    Hans, S.; Yeh, M.; Cumming, J. B.; Hahn, R. L.

    2011-04-27

    Organometallic liquid scintillator becomes one of the man detection mediums for neutrino experiment. Liquid-liquid extraction is the method of choice for loading metallic ions of interest into the organic solvents at BNL. High purity of all starting materials is essential for the optimization of synthesis. A newly developed 'self-scavenging' technique was applied to purify undesired radioisotopes from the starting metal compound and found to effectively remove thorium and such containments from the neodymium chloride for SNO+.

  16. Quenching of neodymium fluorescence by molecular hydrogen

    SciTech Connect

    Prohaska, J.D.; Machewirth, D.P.; Snitzer, E.

    1995-04-01

    We show that the hydrogen-loading technique used to enhance a fiber`s ultraviolet photosensitivity for writing Bragg gratings can lead to quenching of the lasing ion`s fluorescence. The neodymium fluorescence and radiative lifetimes are measured for the untreated fiber, the hydrogen-loaded fiber, and the postannealed fiber. We show that postannealing can be used to remove the unreacted hydrogen molecules from the fiber laser and restore the radiative lifetime to near that of its original value.

  17. Synthesis and characterization of hybrid nanostructures produced in the presence of the titanium dioxide and bioactive organic substances by hydrothermal method

    SciTech Connect

    Zima, Tatyana; Baklanova, Natalya; Bataev, Ivan

    2013-02-15

    Hybrid nanostructures produced by hydrothermal treatment of TiO{sub 2} in the presence of bioactive organic substances such as chitosan, aminoterephthalic acid and their mixture have been investigated. Sodium polytitanates as one-dimensional elongated structures with lengths of several hundred of nanometers were obtained in the presence of chitosan and aminoterephthalic acid. With chitosan the elongated nanostructures are formed by successive superposition of structural fragments-nanostrips with well-ordered multilayered morphology and increased distance between successive layers to 1.2 nm. Quite different amorphous products as agglomerates with roundest and rhomboid morphology are formed when the mixture of chitosan and aminoterephthalic acid is added to the reaction system. One can propose that main reason of such behavior is a low rate of diffusion of dissolved Ti(IV) ions in the high viscous mixed chitosan-aminoterephthalic system. An effect of organic substances on the formation, morphology and transformation of various titanates is discussed. - Graphical abstract: The typical images of hybrid nanostructures produced by hydrothermal treatment of TiO{sub 2} in the presence chitosan and mixed chitosan with aminoterephthalic acid. Highlights: Black-Right-Pointing-Pointer Various shapes of TiO{sub 2} based structures can be produced in the presence of organic. Black-Right-Pointing-Pointer An addition of chitosan results in the formation of the elongated nanostructures. Black-Right-Pointing-Pointer These structures have multilayered morphology and increased distance between layers. Black-Right-Pointing-Pointer Different agglomerates are formed when chitosan and aminoterephthalic acid are mixed.

  18. Holmium laser pumped with a neodymium laser

    SciTech Connect

    Bowman, S.R.; Rabinovich, W.S.

    1991-07-30

    This patent describes a solid-state laser device. It comprises a holmium laser having a first host material doped with an amount of holmium ions sufficient to produce an output laser emission at about 3 {mu}m when the holmium ions in the holmium laser are pumped by a pump beam at a wavelength of about 1.1 {mu}m; and neodymium laser pump source means for supplying a pump beam to pump the holmium ions in the holmium laser at a wavelength of about 1.1 {mu}m.

  19. Neodymium-142 evidence for Hadean mafic crust.

    PubMed

    O'Neil, Jonathan; Carlson, Richard W; Francis, Don; Stevenson, Ross K

    2008-09-26

    Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower 142Nd/144Nd ratios than the terrestrial standard (epsilon142Nd = -0.07 to -0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of 4280(-81)(+53) million years. These rocks thus sample incompatible-element-enriched material formed shortly after Earth formation and may represent the oldest preserved crustal section on Earth. PMID:18818357

  20. Embedded of neodymium oxide nanoclusters in silica

    NASA Astrophysics Data System (ADS)

    Duhan, S.; Aghamkar, P.; Singh, M.; Kishore, N.

    2007-06-01

    The solgel process successfully prepared Nd IIO 3 / SiO II nanocomposites. After drying in air at 85°C for three days, samples were heat treated, in air, at 750, 950, 1150 and 1250°C. Characterizations were made by, Infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Mechanisms of neodymium oxide nano clusters formation in the densified silica matrix with respect to thermal treatment are discussed. XRD profiles confirm the crystallinity of the nanoclusters. The size of the nanoclusters was found in the range 15-30nm.

  1. Interfacial Reactions and Cubic Neodymium Oxide Formation in Low Dispersed Nd2O3-SiO2 System by Wet Chemical Method

    NASA Astrophysics Data System (ADS)

    Duhan, S.; Aghamkar, P.

    2009-01-01

    Neodymium (binary oxide) powders are synthesized by a solgel technique. Prepared powders are heat treated under different temperature for different time duration and obtained nanostructure of Nd. Metal particle have diameters in the range 7.8-21.6 nm. It is found that the heat treatment plays an important role to produce different structure of Nd-doped silica matrix. The peak position shifts to lower angle as the size of the nano metal oxide particles size increases.

  2. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    DOEpatents

    Wong, Stanislaus S.; Mao, Yuanbing

    2016-06-14

    The invention relates to nanomaterial's and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  3. Titanate and titania nanostructures and nanostructure assemblies, and methods of making same

    DOEpatents

    Wong, Stanislaus S; Mao, Yuanbing

    2013-05-14

    The invention relates to nanomaterials and assemblies including, a micrometer-scale spherical aggregate comprising: a plurality of one-dimensional nanostructures comprising titanium and oxygen, wherein the one-dimensional nanostructures radiate from a hollow central core thereby forming a spherical aggregate.

  4. Luminescence from chromium-neodymium-doped lithium niobate

    NASA Astrophysics Data System (ADS)

    Mahpoud, S.; Chamiel, N.; Weiss, A. M.; Rosenbluh, M.; Herman, A.; Shoham, A.; Lipavsky, B.; Rotman, S. R.

    1999-10-01

    Luminescence from chromium-neodymium-doped lithium niobate (LiNbO 3) was experimentally measured to determine the degree of non-radiative energy transfer between chromium and neodymium ions. Evidence is presented for two different time constants for emission from chromium ions in the material, indicating that non-radiative transfer does occur. Differences between quasi-continuous pumping and pulsed excitation are discussed.

  5. Synthesis of Nanostructured Carbides of Titanium and Vanadium from Metal Oxides and Ferroalloys Through High-energy Mechanical Milling and Heat Treatment

    SciTech Connect

    Basu, P.; Jian, P. F.; Seong, K. Y.; Seng, G. S.; Hussain, Z.; Aziz, A.; Masrom, A. K.

    2010-03-11

    Carbides of Ti and V have been synthesized directly from their oxides and ferroalloys through mechanical milling and heat treatment. The powder mixtures are milled in a planetary ball mill from 15-80 hours and subsequently heat treated at 1000-1300 deg. C for TiO{sub 2}-C mixtures, at 500-550 deg. C for V{sub 2}O{sub 5}-C mixtures and at 600-1000 deg. C for (Fe-V)-C mixtures. The milled and heat treated powders are characterized by SEM, EDAX, XRD, and BET techniques. Nanostructured TiC has been successfully synthesized under suitable processing conditions. However, carbides of vanadium is unidentified even though possibilities of V{sub 2}O{sub 5}-C reaction are indicated with an extent of induced amorphism in the powder mixture. Density, specific surface area and particle size of the milled and heat treated mixtures are correlated with heat treatment temperatures. Similar attempts are also made to synthesize vanadium carbides from industrial grade Fe-V.

  6. Titanium 2013

    USGS Publications Warehouse

    2014-01-01

    Titanium is the ninth most abundant element in the earth's crust and can be found in nearly all rocks and sediments. It is a lithophile element with a strong affinity for oxygen and is not found as a pure metal in nature. Titanium was first isolated as a pure metal in 1910, but it was not until 1948 that the metal was produced commercially using the Kroll process (named after its developer, William Kroll) to reduce titanium tetrachloride with magnesium to produce titanium metal.

  7. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, R.; Glatzmaier, G.C.

    1995-05-23

    A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  8. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, Rasit; Glatzmaier, Gregory C.

    1995-01-01

    A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  9. Boundary processes traced by neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Jeandel, C.; Lacan, F.

    2003-04-01

    Continental margins have been identified as preferential sites for removing of reactive elements from the ocean, on the base of U-series measurements (more specifically 231Pa/230Th). This process is called boundary scavenging (Bacon, 1988). Five years of neodymium isotopes data in water masses along the ocean margins (Indonesia, Papua New Guinea, Greenland-Scotland ridge and Labrador Sea) suggests that Nd is transferred from the sediments to the ocean but the reverse also occurs via the so-called boundary scavenging. These processes are only detectable by isotopic ratio measurements because they affect the isotopic signature of the water mass coming in contact with the margin, without changing its concentration. They can involve much higher fluxes than net input processes: for example, the modification of the AAIW signature along the Papua New Guinea slope involves exchange processes only (Lacan and Jeandel, 2001). Since we suspect that such processes not only affect the Nd oceanic chemistry but also the chemical fate of other reactive elements in the ocean, we suggest that the concept of boundary scavenging should be extended to "boundary exchange".

  10. Electrolytic production of neodymium metal from a molten chloride electrolyte

    SciTech Connect

    Chambers, M.F.; Murphy, J.E.

    1991-01-01

    This paper reports that the U.S. Bureau of Mines conducted experiments on electrowinning of neodymium metal by using a molten-metal cathode at 650{degrees} C and an electrolyte of 50 mol pet NdCl, (neodymium chloride) and 50 mol pet KCl (potassium chloride). The molten-metal cathodes were alloys of magnesium and zinc or magnesium and cadmium. Current efficiencies were 90 pct with a Mg-Zn cathode and 80 pct with a Mg-Cd cathode. The Mg-Cd cathode was easily separated from the electrolyte. In contrast, the Mg-Zn cathode tended to mix with the electrolyte, making separation difficult. The cathode metals were separated from the neodymium by distillation at 1,100{degrees} C under a vacuum of 10{sup {minus}4} torr. Neodymium metal of 99.9 + purity was recovered from the Mg-Cd alloy cathode after 30 min distillation time. The neodymium recovered from the Mg-Zn system contained almost 2 pct Zn after vacuum distillation. Continuous operation using the Mg-Cd alloy cathode was demonstrated.

  11. New high-strength neodymium phosphate laser glass

    SciTech Connect

    Galagan, B I; Glushchenko, I N; Denker, B I; Kalachev, Yu L; Mikhailov, Viktor A; Sverchkov, S E; Shcherbakov, Ivan A; Kuleshov, N V

    2009-12-31

    A high-strength neodymium laser glass (SNLG) based on an alumoborophosphate composition is developed and synthesised; its physicochemical, spectral, luminescent, and lasing characteristics are studied. It is found that the chemical stability and thermal resistance of the new glass are considerably higher than the corresponding characteristics of known neodymium-doped phosphate laser glasses. Investigations of lasing upon longitudinal diode pumping showed that, due to the higher thermal resistance, the new glass allows one to obtain output powers twice as high as those of industrial GLS22 glass. (active media)

  12. Nanowatt threshold, alumina sensitized neodymium laser integrated on silicon

    PubMed Central

    Maker, Ashley J.; Armani, Andrea M.

    2013-01-01

    Low threshold lasers based on rare-earth elements have enabled numerous scientific discoveries and innovations in industry. However, pushing the threshold into the sub-microwatt regime has been stymied by a fundamental material phenomenon. Specifically, rare earth dopants form clusters which quench emission and reduce efficiency. Here, we fabricate resonant cavity lasers from neodymium-doped silica films containing alumina. The alumina prevents the clustering of the Neodymium, enabling the lasers to achieve thresholds of 530nanoWatts at room temperature. PMID:24216946

  13. Efficient wide-aperture neodymium glass rod amplifiers

    SciTech Connect

    Potemkin, A K; Zhurin, K A; Kirsanov, A V; Kopelovich, E A; Kuznetsov, M V; Kuz'min, A A; Flat, F A; Khazanov, Efim A; Shaikin, A A

    2011-06-30

    Amplifiers based on neodymium phosphate glass rods 60 - 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps. (lasers)

  14. Purification of cerium, neodymium and gadolinium for low background experiments

    NASA Astrophysics Data System (ADS)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  15. Materials flow analysis of neodymium, status of rare earth metal in the Republic of Korea.

    PubMed

    Swain, Basudev; Kang, Leeseung; Mishra, Chinmayee; Ahn, JoongWoo; Hong, Hyun Seon

    2015-11-01

    Materials flow analysis of neodymium, status of rare earth elements (REEs) in the Republic of Korea has been investigated. Information from various resources like the Korean Ministry of Environment, Korea international trade association, United Nations Commodity Trade Statistics Database and from individual industry were collected and analyzed for materials flow analysis of neodymium. Demand of neodymium in the Republic of Korea for the year 2010 was 409.5 tons out of which the majority of neodymium, i.e., 68.41% was consumed by domestic electronics industry followed by medical appliances manufacturing (13.36%). The Republic Korea is one of the biggest consumer and leading exporter of these industrial products, absolutely depends on import of neodymium, as the country is lacking natural resources. The Republic of Korea has imported 325.9 tons of neodymium permanent magnet and 79.5 tons of neodymium containing equipment parts mainly for electronics, medical appliances, and heavy/light vehicles manufacturing industry. Out of which 95.4 tons of neodymium permanent magnet get exported as an intermediate product and 140.6 tons of neodymium in the form of consumable products get exported. Worldwide the neodymium is at the high end of supply chain critical metal because of increasing demand, scarcity and irreplaceable for technological application. To bring back the neodymium to supply stream the recycling of end of life neodymium-bearing waste can be a feasible option. Out of total domestic consumption, only 21.9 tons of neodymium have been collected and subsequently recycled. From material flow analysis, the requirement for an efficient recycling system and element-wise material flow management for these REEs in the Republic of Korea were realized and recommended. PMID:26210233

  16. Superhydrophilic nanostructure

    DOEpatents

    Mao, Samuel S; Zormpa, Vasileia; Chen, Xiaobo

    2015-05-12

    An embodiment of a superhydrophilic nanostructure includes nanoparticles. The nanoparticles are formed into porous clusters. The porous clusters are formed into aggregate clusters. An embodiment of an article of manufacture includes the superhydrophilic nanostructure on a substrate. An embodiment of a method of fabricating a superhydrophilic nanostructure includes applying a solution that includes nanoparticles to a substrate. The substrate is heated to form aggregate clusters of porous clusters of the nanoparticles.

  17. Neodymium-YAG laser vitreolysis in sickle cell retinopathy

    SciTech Connect

    Hrisomalos, N.F.; Jampol, L.M.; Moriarty, B.J.; Serjeant, G.; Acheson, R.; Goldberg, M.F.

    1987-08-01

    Six patients with proliferative sickle cell retinopathy and vitreous bands were treated with the neodymium-YAG (Nd-YAG) laser to accomplish lysis of avascular traction bands or to clear the media in front of the macula. Transection of bands was possible in five of the six cases but in two of these the effect was only partial. Three cases were satisfactorily treated with the Nd-YAG laser application alone, two eventually required conventional vitreoretinal surgery, and one patient's condition stabilized despite failure of the treatment. Complications from the treatment occurred in three cases and included subretinal (choroidal) hemorrhage, preretinal hemorrhage, microperforation of a retinal vein, and focal areas of damage to the retinal pigment epithelium. Neodymium-YAG vitreolysis may be a useful modality in carefully selected patients with proliferative sickle cell retinopathy, but potentially sight-threatening complications may occur.

  18. Treatment of benign urethral strictures using a sapphire tipped neodymium:YAG laser.

    PubMed

    Smith, J A

    1989-11-01

    Sapphire tips increase the energy density and cutting effect of a neodymium:YAG laser. Sapphire tipped neodymium:YAG laser fibers were used to perform urethrotomy in 24 men with benign urethral strictures. The cutting effect was inadequate in 10 patients. Of the 24 patients 16 (67%) had a recurrent stricture within 1 year. Sapphire tipped neodymium:YAG laser fibers offer no apparent advantage over cold knife urethrotomy for treatment of benign urethral strictures. PMID:2810498

  19. Additive-pulse modelocking of non-cw neodymium lasers

    NASA Astrophysics Data System (ADS)

    Heinz, P.; Reuther, A.; Laubereau, A.

    1993-03-01

    Passive modelocking of several flash-lamp pumped neodymium lasers with electro-optic amplitude stabilization is demonstrated using a nonlinear Michelson interferometer. Improved performance is reported for the GSGG- YLF- and glass-laser as compared to the nonlinear absorber, with shorter pulse durations and smaller amplitude fluctuations, e.g. 5 μJ pulses for 460 ± 20 fs for Nd:glass. Evidence is obtained for multi-selfstability of the pulse energy.

  20. [Neodymium magnet injury causing nasal fracture: a case report].

    PubMed

    Aykan, Andaç; Güzey, Serbülent; Avşar, Sedat; Öztürk, Serdar

    2015-05-01

    In parallel with technological developments, small size but strong magnets are commonly used in modern devices. In terms of foreign body injuries, magnet injuries are quite rare. However, due to their unique characteristics, there are some difficulties in their management. The magnetic field generated by the magnet affects the surgical instruments and make treatment difficult. In this case report, a nasal injury due to neodymium magnet and our alternative approach for its management was reported. PMID:26033660

  1. An improved biofunction of titanium for keratoprosthesis by hydroxyapatite-coating.

    PubMed

    Dong, Ying; Yang, Jingxin; Wang, Liqiang; Ma, Xiao; Huang, Yifei; Qiu, Zhiye; Cui, Fuzhai

    2014-03-01

    Titanium framework keratoprosthesis has been commonly used in the severe corneal blindness, but the tissue melting occurred frequently around titanium. Since hydroxyapatite has been approved to possess a good tissue integration characteristic, nanostructured hydroxyapatite was coated on the surface of titanium through the aerosol deposition method. In this study, nanostructured hydroxyapatite coating was characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and auger electronic spectrometer. Biological evaluations were performed with rabbit cornea fibroblast in vitro and an animal model in vivo. The outcomes showed the coating had a grain-like surface topography and a good atomic mixed area with substrate. The rabbit cornea fibroblasts appeared a good adhesion on the surface of nanostructured hydroxyapatite in vitro. In the animal model, nanostructured hydroxyapatite-titanium implants were stably retained in the rabbit cornea, and by contrast, the corneal stroma became thinner anterior to the implants in the control. Therefore, our findings proved that nanostructured hydroxyapatite-titanium could not only provide an improved bond for substrate but also enhance the tissue integration with implants in host. As a promising material, nanostructured hydroxyapatite-titanium-based keratoprosthesis prepared by the aerosol deposition method could be utilized for the corneal blindness treatment. PMID:23749719

  2. Complexation of di-amides of dipicolinic acid with neodymium

    SciTech Connect

    Lapka, J.L.; Paulenova, A.

    2013-07-01

    Di-amides have undergone significant studies as possible ligands for use in the partitioning of trivalent minor actinides and lanthanides. The binding affinities of three isomeric ligands with neodymium in acetonitrile solution have been investigated. The stability constants of the metal-ligand complexes formed between different isomers of N,N'-diethyl-N,N'- ditolyl-di-picolinamide (EtTDPA) and trivalent neodymium in acetonitrile have been determined by spectrophotometric and calorimetric methods. Each isomer of EtTDPA has been found to be capable of forming three complexes with trivalent neodymium, Nd(EtTDPA), Nd(EtTDPA){sub 2}, and Nd(EtTDPA){sub 3}. Values from spectrophotometric and calorimetric titrations are within reasonable agreement with each other. The order of stability constants for each metal:ligand complex decreases in the order Et(m)TDPA > Et(p)TDPA > Et(o)TDPA. The obtained values are comparable to other di-amidic ligands obtained under similar system conditions and mirror previously obtained solvent extraction data for EtTDPA at low ionic strengths. (authors.

  3. Preparation of titanium diboride powder

    DOEpatents

    Brynestad, Jorulf; Bamberger, Carlos E.

    1985-01-01

    Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

  4. Development and Characterization of a Hybrid TITANIUM:SAPPHIRE/NEODYMIUM:GLASS Multiterawatt Laser System

    NASA Astrophysics Data System (ADS)

    Chien, Chingyuan

    The broad bandwidth of Ti:sapphire, and the high energy storage/extraction capability of Nd:glass have made it possible to develop a hybrid Ti:sapphire/Nd:glass chirped -pulse-amplification (CPA) laser system. This 400-fs laser system generates pulses with a contrast ratio of 10 ^6:1, and is capable of producing a focused intensity in excess of 10^{19} W/cm^2. The plasma produced by the interaction of an intense 400-fs laser pulse with an Al solid target is studied using a time-integrated x-ray spectrometer. The temporal behavior of the keV x-ray pulse emitted from the laser-produced plasma is studied with an x-ray streak camera (with 2 ps time resolution). The characteristic of the x-ray emission strongly depends on the contrast of the laser pulse. Second harmonic generation of a 1 mu m, 400-fs laser pulses is investigated for Type I and Type II conversion schemes with a KDP crystal. High conversion efficiencies (up to 80%) are obtained in the intensity range from 100-400 GW/cm^2, with no obvious damage to the crystal. In the Type II predelay scheme, a pulse shortening effect is observed and the shortest measured pulse duration is 180 fs. The experimental results generally agree with the simulations of the code MIXER.

  5. Do foraminifera accurately record seawater neodymium isotope composition?

    NASA Astrophysics Data System (ADS)

    Scrivner, Adam; Skinner, Luke; Vance, Derek

    2010-05-01

    Palaeoclimate studies involving the reconstruction of past Atlantic meridional overturning circulation increasingly employ isotopes of neodymium (Nd), measured on a variety of sample media (Frank, 2002). In the open ocean, Nd isotopes are a conservative tracer of water mass mixing and are unaffected by biological and low-temperature fractionation processes (Piepgras and Wasserburg, 1987; Lacan and Jeandel, 2005). For decades, benthic foraminifera have been widely utilised in stable isotope and geochemical studies, but have only recently begun to be exploited as a widely distributed, high-resolution Nd isotope archive (Klevenz et al., 2008), potentially circumventing the difficulties associated with other methods used to recover past deep-water Nd isotopes (Klevenz et al., 2008; Rutberg et al., 2000; Tachikawa et al., 2004). Thus far, a single pilot study (Klevenz et al., 2008) has indicated that core-top sedimentary benthic foraminifera record a Nd isotope composition in agreement with the nearest available bottom seawater data, and has suggested that this archive is potentially useful on both millennial and million-year timescales. Here we present seawater and proximal core-top foraminifer Nd isotope data for samples recovered during the 2008 "RETRO" cruise of the Marion Dufresne. The foraminifer samples comprise a depth-transect spanning 3000m of the water column in the Angola Basin and permit a direct comparison between high-resolution water column and core-top foraminiferal Nd isotope data. We use these data to assess the reliability of both planktonic and benthic foraminifera as recorders of water column neodymium isotope composition. Frank, M., 2002. Radiogenic isotopes: Tracers of past ocean circulation and erosional input, Rev. Geophys., 40 (1), 1001, doi:10.1029/2000RG000094. Klevenz, V., Vance, D., Schmidt, D.N., and Mezger, K., 2008. Neodymium isotopes in benthic foraminifera: Core-top systematics and a down-core record from the Neogene south Atlantic

  6. Effect of transscleral neodymium: YAG cyclophotocoagulation on intraocular lenses

    SciTech Connect

    Blomquist, P.H.; Gross, R.L.; Koch, D.D. )

    1990-03-01

    A neodymium: YAG laser operating in the thermal mode was used to irradiate isolated intraocular lenses (IOLs) and to perform transscleral cyclophotocoagulation on pseudophakic autopsy eyes to investigate the potential damage to IOL haptics such irradiation may cause. In the isolated IOLs, 70 mJ of energy deformed and partially melted both polymethylmethacrylate (PMMA) and polypropylene haptics. One of the capsular-fixated PC-IOL haptics in an autopsy eye partially melted when irradiated with the maximum energy level (8.8 J), with the aiming beam focused 1 mm posterior to the limbus and maximal posterior focus offset.

  7. Local immunity in treating skin melanoma by neodymium pulsed laser

    NASA Astrophysics Data System (ADS)

    Moskalik, Konstantin G.

    1997-06-01

    The number and correlation of skin stroma cells was studied on mice C57B1 with the subcutaneously transplanted melanoma B16 which was exposed to neodymium pulsed laser radiation. Within 1-5 days after the exposure the total number of the free skin stroma cells was found to increase in the periphery from the radiation epicenter and the number of lymphocytes, macrophages and leucocytes tended to grow. Lymphoid infiltration was also revealed in the preparations of the epithelized wound and cicatrix on the skin melanoma sites in the patients who had undergone pulsed laser radiation therapy.

  8. Urethral strictures treatment with neodymium:YAG laser.

    PubMed

    Silber, N

    1992-04-01

    A total of 14 patients with stricture of the urethra underwent treatment with Nd:YAG (neodymium:YAG) laser irradiation. A new 800-micron hemispherical optical quartz fiber was used in contact technique to produce linear incisions in the scarred tissue. Within 11.2 months, median of follow up, there was improvement in the obstructive voiding symptoms in all the patients. One patient who still had mild stricture in the first follow-up cystoscopy was managed successfully with second treatment. Endoscopic application of laser energy in the contact mode facilitates the immediate vaporization and disintegration of the fibrous area and secondary reepithelization of the urethra without scarring. PMID:10171965

  9. Colorful titanium oxides: a new class of photonic materials.

    PubMed

    Li, Zhenzhen; Xin, Yanmei; Zhang, Zhonghai

    2015-12-21

    In this communication, a new class of photonic materials, namely, two-dimensional titanium oxide-based photonic crystals, are proposed and were fabricated with an electrochemical anodization method. The high structural periodicity of the nanostructures, and the feasible variability of the chemical compositions help to realize tunable photonic bandgaps for selective light absorption in broad wavelength regions. PMID:26450687

  10. Opportunities in the electrowinning of molten titanium from titanium dioxide

    NASA Astrophysics Data System (ADS)

    van Vuuren, D. S.; Engelbrecht, A. D.; Hadley, T. D.

    2005-10-01

    The value chain of titanium products shows that the difference between the cost of titanium ingot and titanium dioxide is about 9/kg titanium. In contrast, the price of aluminum, which is produced in a similar way, is only about 1.7/kg. Electrowinning of molten titanium from titanium dioxide is therefore believed to have significant potential to reduce the cost of titanium products. The process is hampered by the high operating temperatures and sophisticated materials of construction required; the high affinity of titanium for carbon, oxygen, and nitrogen; and physical and chemical properties of the different titanium oxide species when reducing titanium from Ti4+ to metallic titanium.

  11. Incorporation of Cerium and Neodymium in Uranyl Phases

    SciTech Connect

    Kim, C W.; Wronkiewicz, David J.; Finch, R J.; Buck, Edgar C.

    2006-07-15

    The potential for incorporating rare earth elements (REE) into/onto crystalline compounds has been evaluated by precipitating uranyl phases from aqueous solutions containing either cerium or neodymium. These REEs serve both as monitors for evaluating the potential repository behavior of REE radionuclides, and as surrogate elements for actinides (e.g., Ce4 and Nd3 for Pu4 and Am3, respectively). The present experiments examined the behavior of REE in the presence of ianthinite Formula Not Shown, becquerelite (Ca(UO2)6O4(OH)6(H2O)8), and other uranyl hydroxide compounds commonly noted as alteration products during the corrosion of UO2, spent nuclear fuel, and naturally occurring uraninite. The results of these experiments demonstrate that significant quantities of both cerium (Kd=1020) and neodymium (Kd=840) are incorporated within the uranium alteration phases and suggest that ionic substitution and/or adsorption to the uranyl phases can play a key role in the limiting the mobility of REE (and by analogy, actinide elements) in a nuclear waste repository.

  12. Recycling potential of neodymium: the case of computer hard disk drives.

    PubMed

    Sprecher, Benjamin; Kleijn, Rene; Kramer, Gert Jan

    2014-08-19

    Neodymium, one of the more critically scarce rare earth metals, is often used in sustainable technologies. In this study, we investigate the potential contribution of neodymium recycling to reducing scarcity in supply, with a case study on computer hard disk drives (HDDs). We first review the literature on neodymium production and recycling potential. From this review, we find that recycling of computer HDDs is currently the most feasible pathway toward large-scale recycling of neodymium, even though HDDs do not represent the largest application of neodymium. We then use a combination of dynamic modeling and empirical experiments to conclude that within the application of NdFeB magnets for HDDs, the potential for loop-closing is significant: up to 57% in 2017. However, compared to the total NdFeB production capacity, the recovery potential from HDDs is relatively small (in the 1-3% range). The distributed nature of neodymium poses a significant challenge for recycling of neodymium. PMID:25029356

  13. On the increasing of adhesive strength of nanotube layers on beta titanium alloys for medical applications

    NASA Astrophysics Data System (ADS)

    Fojt, Jaroslav; Filip, Vladimir; Joska, Ludek

    2015-11-01

    The nanostructuring of titanium and its alloys surfaces is used inter alia for increasing the medical implants osseointegration. Many papers about this topic were published. However, in most cases there were no informations about nanostructures adhesion to the surface, which is crucial from the application point of view. The aim of this study was to prepare nanostructures on titanium beta alloy and optimized its adhesion to the alloy surface. Nanotubes were formed by anodic polarization in electrolyte containing fluoride ions. The composition of the nanotubes was described by X-ray photoelectron spectroscopy. Nanostructures adhesion was tested by pull-of method. The nanotubes on the Ti-36Nb-6Ta beta alloy surface were prepared by anodization. The nanostructures properties were modified by electrochemical process parameters. The adhesion of the nanotubes prepared in this work was satisfactory for implantological applications.

  14. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, Rudolf; Larimer, Kirk T.

    1998-01-01

    A method of producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage.

  15. Origin of the Sudbury Complex by meteoritic impact: Neodymium isotopic evidence

    USGS Publications Warehouse

    Faggart, B.E., Jr.; Basu, A.R.; Tatsumoto, M.

    1985-01-01

    Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 ?? 21 ?? 106 years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.

  16. Titanium hermetic seals

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1995-07-04

    Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

  17. Titanium hermetic seals

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1995-01-01

    Titanium is prenitrided by being heated in a nitrogen environment under conditions which give rise to the formation of a titanium-nitride surface layer on the titanium. Titanium thus prenitrided may be used in electrical components which are hermetically sealed using silicate glasses and standard glass sealing techniques. According to the method of the invention, alkali volatilization and formation of deleterious interfacial silicide are inhibited.

  18. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, R.K.; Watkins, R.D.

    1988-01-21

    Glass compositions containing CaO, Al/sub 2/O/sub 3/, B/sub 2/O/sub 3/, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  19. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, Richard K.; Watkins, Randall D.

    1992-01-01

    Glass compositions containing CaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, SrO and BaO of various combinations of mole % are provided. These compositions are capable of forming stable glass-to-metal seals with titanium and titanium alloys, for use in components such as seals for battery headers.

  20. A new contact neodymium: YAG laser for cyclophotocoagulation

    SciTech Connect

    Iwach, A.G.; Drake, M.V.; Hoskins, H.D. Jr.; Schuster, B.L.; Vassiliadis, A.; Crawford, J.B.; Hennings, D.R. )

    1991-06-01

    A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

  1. Segmental irradiation of the bladder with neodymium YAG laser irradiation

    SciTech Connect

    McPhee, M.S.; Mador, D.R.; Tulip, J.; Ritchie, B.; Moore, R.; Lakey, W.H.

    1982-11-01

    The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma.

  2. Neodymium isotope evidence for a chondritic composition of the Moon.

    PubMed

    Rankenburg, K; Brandon, A D; Neal, C R

    2006-06-01

    Samarium-neodymium isotope data for six lunar basalts show that the bulk Moon has a 142Nd/144Nd ratio that is indistinguishable from that of chondritic meteorites but is 20 parts per million less than most samples from Earth. The Sm/Nd formation interval of the lunar mantle from these data is 215(-21)(+23) million years after the onset of solar system condensation. Because both Earth and the Moon likely formed in the same region of the solar nebula, Earth should also have a chondritic bulk composition. In order to mass balance the Nd budget, these constraints require that a complementary reservoir with a lower 142Nd/144Nd value resides in Earth's mantle. PMID:16741118

  3. α-uranium phase in compressed neodymium metal

    NASA Astrophysics Data System (ADS)

    Chesnut, Gary N.; Vohra, Yogesh K.

    2000-02-01

    The light rare-earth metal, neodymium, has been studied up to 155 GPa in a diamond-anvil cell using energy dispersive x-ray diffraction with a synchrotron source. The pressures were calibrated using copper as an internal x-ray pressure standard. A phase transformation from a monoclinic phase (C2/m, 4 atoms/cell) to an orthorhombic α-U phase (Cmcm, 4 atoms/cell) was observed at 113+/-6 GPa without any observable volume collapse. The observation of α-U phase in Nd and, previously, in cerium and praseodymium clearly establishes this phase in light rare-earth metals. Our equation of state measurements suggest that delocalization of the f shell in Nd occurs without any volume collapse unlike Ce and Pr.

  4. Isotope enrichment by frequency-tripled temperature tuned neodymium laser photolysis of formaldehyde

    DOEpatents

    Marling, John B.

    1977-01-01

    Enrichment of carbon, hydrogen and/or oxygen isotopes by means of isotopically selective photo-predissociation of formaldehyde is achieved by irradiation provided by a frequency-tripled, temperature tuned neodymium laser.

  5. Microscale Demonstration of the Paramagnetism of Liquid Oxygen with a Neodymium Magnet

    ERIC Educational Resources Information Center

    Mattson, Bruce

    2007-01-01

    A microscale classroom demonstration of the paramagnetic behavior of various samples of liquid oxygen with neodymium magnet is being presented. The experiment should be done with extreme caution, as liquid oxygen reacts violently with organic matters.

  6. Description of the traction characteristics of the neodymium compensators of the automatic vibration isolations

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.; Panchenko, Y. V.; Gurov, M. G.

    2016-04-01

    In this paper the method of calculation of neodymium magnets was presented. The calculation of the neodymium magnets characteristics and stiffness correctors of the vibration isolator according to the requirements for vibration isolation devices with stiffness compensators was performed. This research has been performed with the support of the President scholarship for young scientists, order No. 184 of Ministry of education and science of the Russian Federation of the 10th of March 2015.

  7. Nanostructured photovoltaics

    NASA Astrophysics Data System (ADS)

    Fu, Lan; Tan, H. Hoe; Jagadish, Chennupati

    2013-01-01

    Energy and the environment are two of the most important global issues that we currently face. The development of clean and sustainable energy resources is essential to reduce greenhouse gas emission and meet our ever-increasing demand for energy. Over the last decade photovoltaics, as one of the leading technologies to meet these challenges, has seen a continuous increase in research, development and investment. Meanwhile, nanotechnology, which is considered to be the technology of the future, is gradually revolutionizing our everyday life through adaptation and incorporation into many traditional technologies, particularly energy-related technologies, such as photovoltaics. While the record for the highest efficiency is firmly held by multijunction III-V solar cells, there has never been a shortage of new research effort put into improving the efficiencies of all types of solar cells and making them more cost effective. In particular, there have been extensive and exciting developments in employing nanostructures; features with different low dimensionalities, such as quantum wells, nanowires, nanotubes, nanoparticles and quantum dots, have been incorporated into existing photovoltaic technologies to enhance their performance and/or reduce their cost. Investigations into light trapping using plasmonic nanostructures to effectively increase light absorption in various solar cells are also being rigorously pursued. In addition, nanotechnology provides researchers with great opportunities to explore the new ideas and physics offered by nanostructures to implement advanced solar cell concepts such as hot carrier, multi-exciton and intermediate band solar cells. This special issue of Journal of Physics D: Applied Physics contains selected papers on nanostructured photovoltaics written by researchers in their respective fields of expertise. These papers capture the current excitement, as well as addressing some open questions in the field, covering topics including the

  8. Laser Gas Nitriding of Titanium and Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Dai, J. J.; Hou, S. Q.

    Titanium and titanium alloys are widely used in many fields due to some of their characteristics such as light density, high strength, and excellent corrosion resistance. However, poor mechanical performances limit their practical applications. Laser gas nitriding is a promising method used to improve the surface properties of components. Recent developments on laser gas nitriding of titanium and titanium alloys are reviewed. The processing parameters have important effects on the resulting characteristics of titanium and titanium alloys. The resulting microstructure and properties of laser gas nitrided specimens are presented. The problems to be solved and the prospects in the field of laser gas nitriding of titanium and titanium alloys are discussed.

  9. Dichloromethane photodegradation using titanium catalysts

    SciTech Connect

    Tanguay, J.F.; Suib, S.L.; Coughlin, R.W. )

    1989-06-01

    The use of titanium dioxide and titanium aluminosilicates in the photocatalytic destruction of chlorinated hydrocarbons is investigated. Titanium-exchanged clays, titanium-pillared clays, and titanium dioxide in the amorphous, anatase, and rutile forms are used to photocatalytically degrade dichloromethane to hydrochloric acid and carbon dioxide. Bentonite clays pillared by titanium dioxide are observed to be more catalytically active than titanium-exchanged clays. Clays pillared by titanium aluminum polymeric cations display about the same catalytic activity as that of titanium-exchanged clays. The rutile form of titanium dioxide is the most active catalyst studied for the dichloromethane degradation reaction. The anatase form of titanium dioxide supported on carbon felt was also used as a catalyst. This material is about five times more active than titanium dioxide-pillared clays. Degradation of dichloromethane using any of these catalysts can be enhanced by oxygen enrichment of the reaction solution or by preirradiating the catalyst with light.

  10. Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

    SciTech Connect

    Thankachan, Smitha; Binu, P. J.; Xavier, Sheena; Mohammed, E. M.

    2011-10-20

    The effect of Nd{sup 3+} substitution on the structural properties of Magnesium ferrite was studied in the series MgNd{sub x}Fe{sub 2-x}O{sub 4}, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol-gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples are in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz--120MHz was also studied

  11. Power neodymium-glass amplifier of a repetitively pulsed laser

    SciTech Connect

    Vinogradov, Aleksandr V; Gaganov, V E; Garanin, Sergey G; Zhidkov, N V; Krotov, V A; Martynenko, S P; Pozdnyakov, E V; Solomatin, I I

    2011-11-30

    A neodymium-glass diode-pumped amplifier with a zigzag laser beam propagation through the active medium was elaborated; the amplifier is intended for operation in a repetitively pulsed laser. An amplifier unit with an aperture of 20 Multiplication-Sign 25 mm and a {approx}40-cm long active medium was put to a test. The energy of pump radiation amounts to 140 J at a wavelength of 806 nm for a pump duration of 550 {mu}s. The energy parameters of the amplifier were experimentally determined: the small-signal gain per pass {approx}3.2, the linear gain {approx}0.031 cm{sup -1} with a nonuniformity of its distribution over the aperture within 15%, the stored energy of 0.16 - 0.21 J cm{sup -3}. The wavefront distortions in the zigzag laser-beam propagation through the active element of the amplifier did not exceed 0.4{lambda} ({lambda} = 0.63 {mu}m is the probing radiation wavelength).

  12. Laser self-doubling in neodymium yttrium aluminum borate

    NASA Astrophysics Data System (ADS)

    Lu, Bao-Sheng; Wang, Jun; Pan, Heng-Fu; Jiang, Min-Hua; Liu, En-Quan

    1989-12-01

    The nonlinear effects of neodymium yttrium aluminum borate Nd(x)Y(1-x)Al3(BO3)4 (NYAB) crystal powder samples with different Nd(3+) mole percentages are reported. The optimum X values for the growth of NYAB crystals with high optical homogeneity has been determined. The performance of laser self-frequency doubling from 1.06-0.53 micron has been realized, for the first time, in a 5 x 3 x 3 cu mm NYAB crystal. The Nd(3+) ions in crystal show weak absorption at 0.53 micron. The threshold energy is measured to be less than 2 mJ; the output energy of green light at 0.53 micron is more than 5 mJ and the conversion efficiency is over 10 percent. The experiments show that the performance is improved if the optical path length is increased and the cavity design is improved. The refractive indices n(0) and n(e) of the crystal have been measured by the prism method at different wavelengths. The phase-matching angles of Types I and II have been obtained by solving equations for the phase-matching angles. The results are in good agreement with the experimental values. The nonlinear coefficient d(11) of the NYAB crystal has been measured to be 4 x 10 to the-9th esu.

  13. LASERS: Efficient neodymium-doped gadolinium gallium garnet crystal laser

    NASA Astrophysics Data System (ADS)

    Doroshenko, Maxim E.; Osiko, Vyacheslav V.; Sigachev, V. B.; Timoshechkin, M. I.

    1991-07-01

    An investigation was made of the stimulated emission parameters of a laser utilizing a gadolinium gallium garnet crystal doped with neodymium ions (YAG:Nd) at the 1.062 μm wavelength. The free-running efficiency was the highest so far achieved for flashlamp-pumped lasers utilizing unsensitized garnets. For an active element 8 mm in diameter and 120 mm long the absolute efficiency was 5.4% and the differential efficiency was 5.9%. The average free-running power was 170 W. A comparison was made of the optical powers of thermal lenses in cylindrical GGG:Nd and YAG:Nd active elements and this was found to be 2.4 times higher for a GGG:Nd crystal at the same pump powers. It was shown that by using traditional methods of compensating for the thermal lens in cylindrical active elements, it is possible to develop pulsed GGG:Nd crystal lasers having an average output power higher than 100 W, an efficiency of ~ 4%, and an angular divergence of less than 10 mrad.

  14. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  15. Laboratory and clinical experience with neodymium:YAG laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kabalin, John N.

    1996-05-01

    Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

  16. Surface analysis and osteoblasts response of a titanium oxi-carbide film deposited on titanium by ion plating plasma assisted (IPPA).

    PubMed

    Mazzola, L; Bemporad, E; Misiano, C; Pepe, F; Santini, P; Scandurra, R

    2011-10-01

    Titanium is the most widely used material in orthopaedic and dental implantoprosthesis due to its superior physical properties and enhanced biocompatibility due to the spontaneous formation of a passivating layer of titanium oxides which, however, does not form good chemical bonds with bone and tends to brake exposing bulk titanium to harsh body fluids releasing titanium particles which may prime an inflammation response and a fibrotic tissue production. In order to avoid these possible problems and to enhance the biocompatibility of titanium implants, modifications of titanium surfaces by many different materials as hydroxyapatite, titanium nitride, titanium oxide and titanium carbide have been proposed. The latter is shown to be an efficient protection for the titanium implant in the harsh conditions of biological tissues and, compared to untreated titanium, acting like an osteoblast stimulation factor increasing in vitro production of proteins involved in osteogenesis. These results were confirmed by in vivo experiments in rabbits: implants covered by the titanium carbide (TiC) layer were faster and better osseointegrated than untreated titanium implants. The TiC layer was deposited by a Pulsed Laser Deposition (PLD) device which allowed only one deposition per cycle, shown to be unsuitable for industrial applications. Therefore the main objective of the present work was to replace PLD process with an Ion Plating Plasma Assisted (IPPA) deposition process, which is suitable for industrial upgrading. By this technique, nanostructured TiOx-TiCy-C has been deposited on titanium after sandblasting with 120 micron zirconia spheres. XPS analyses revealed the presence of about 33% carbon (50% of which is present as free carbon), 39% oxygen and 28% titanium (37% of which is bound to carbon to form TiC and 63% is bound to oxygen to form non stoichiometric oxides). Surface mechanical response of as-deposited coatings has been performed by nanoindentation techniques

  17. Electrolytic production of neodymium metal from a molten chloride electrolyte. Rept. of Investigations/1991

    SciTech Connect

    Chambers, M.F.; Murphy, J.E.

    1991-01-01

    Electrowinning of neodymium metal was accomplished by using a molten-metal cathode at 650 C and an electrolyte of 50 mol pct neodymium chloride-50 mol pct potassium chloride. The molten-metal cathodes were alloys of magnesium and zinc or magnesium and cadmium. Current efficiencies were 90 pct with a Mg/Zn cathode and 80 pct with a Mg-Cd cathode. The Mg-Cd cathode was easily separated from the electrolyte. In contrast, the Mg-Zn cathode tended to mix with the electrolyte, making separation difficult. The cathode metals were separated from the neodymium by distillation at 1,100 C under a vacuum of 10 to the -3rd power torr. Neodymium metal of 99.9+ purity was recovered from the Mg-Cd alloy cathode after 30 min distillation time. The neodymium recovered from the Mg-Zn system contained almost 2 pct Zn after vacuum distillation. Continuous operation using the Mg-Cd alloy cathode was demonstrated.

  18. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, R.K.; McCollister, H.L.; Phifer, C.C.; Day, D.E.

    1997-07-15

    Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B{sub 2}O{sub 3}), barium oxide (BaO), lanthanum oxide (La{sub 2}O{sub 3}), and at least one other oxide selected from the group consisting of aluminum oxide (Al{sub 2}O{sub 3}), calcium oxide (CaO), lithium oxide (Li{sub 2}O), sodium oxide (Na{sub 2}O), silicon dioxide (SiO{sub 2}), or titanium dioxide (TiO{sub 2}). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900 C, and generally about 700--800 C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps). 1 fig.

  19. Sealing glasses for titanium and titanium alloys

    DOEpatents

    Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

    1997-01-01

    Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

  20. Sprayable titanium composition

    DOEpatents

    Tracy, Chester E.; Kern, Werner; Vibronek, Robert D.

    1980-01-01

    The addition of 2-ethyl-1-hexanol to an organometallic titanium compound dissolved in a diluent and optionally containing a lower aliphatic alcohol spreading modifier, produces a solution that can be sprayed onto a substrate and cured to form an antireflection titanium oxide coating having a refractive index of from about 2.0 to 2.2.

  1. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, R.; Larimer, K.T.

    1998-09-22

    A method is described for producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage. 4 figs.

  2. Electrowinning of neodymium from a molten oxide-fluoride electrolyte. Report of investigations/1994

    SciTech Connect

    Dysinger, D.K.; Murphy, J.E.

    1994-01-01

    Neodymium metal of 99.8 percent purity was prepared by electrolysis of Nd2O3 salts dissolved in a molten fluoride electrolyte. The metal was electrowon in a molten state at current efficiencies of 50 to 60 percent. Oxygen and carbon were the major impurities detected in the product. During operation of the small scale laboratory cell, a number of technical problems including anode effect, low oxide solubility in the electrolyte, high neodymium metal solubility, reactivity of the metal with the cell materials, and back reaction of the metal with the anode gases were encountered. Approaches to improve cell operation and prospects for commercial adoption of the electrolytic production of neodymium metal are discussed.

  3. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

  4. Hafnium and Neodymium Isotopes in Atlantic Ocean Waters

    NASA Astrophysics Data System (ADS)

    Rickli, J.; Frank, M.; Halliday, A.

    2007-12-01

    Neodymium isotopic compositions (ICs) have been established as a tracer of water masses in the present and past oceans since the late 1970s. Hafnium isotopes share the capability of tracing water masses and in combination with Nd isotopes provide information on continental weathering regimes. Whereas Nd released during weathering reflects the bulk Nd IC of the weathered lithology, the released Hf is more radiogenic than the weathered lithology. This effect is due to highly variable Lu/Hf--ratios in rock--forming minerals ("zircon effect") and as a consequence physical weathering apparently leads to more congruent weathering of Hf than chemical weathering does. Our understanding of the Hf IC of seawater to date has been derived (with the exception of some as yet unpublished data from the Arctic and Pacific oceans (Zimmermann et al., in prep.)) from ferromanganese crusts and nodules, since Hf concentrations in seawater are low and have until recently hampered direct measurements of Hf IC of seawater. We present IC for the dissolved Hf and Nd in Atlantic seawater. Samples were taken mainly on a transect from the Bay of Biscay to Cape Town (RV Polarstern cruise ANT XXIII/1 in 2005). A few additional samples are from the Labrador Sea and the Drake Passage. Hafnium and Nd were pre--concentrated by iron co--precipitation from 60 to 140 liters of filtered (0.45 μm) seawater. Separation of Hf and Nd followed previously established ion chromatographic procedures. Hafnium and Nd ICs were measured by MC--ICPMS (Nu Plasma) with a 2σ external reproducibility of 0.65 and 0.3 ǎrepsilon--units, respectively. Sample sizes varied but were in most cases larger than 3ng of Hf. Surface seawater as well as deep water samples extending to ~5,000 m, plot on the "seawater array" defined previously from measurements of ferromanganese crusts and nodules. Surface seawater ICs are quite uniform for Hf ranging from ǎrepsilonHf = 0 to +2 at most sampling sites on the Atlantic transect. In the

  5. Recent Progress in the Development of Neodymium Doped Ceramic Yttria

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Edwards, Chris; Trivedi, Sudhir B.; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra; Kear, Bernard

    2007-01-01

    Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching.

  6. Treatment of urethral diseases with neodymium:YAG laser.

    PubMed

    Bloiso, G; Warner, R; Cohen, M

    1988-08-01

    Over a thirty-month period, a wide variety of common urethral problems were treated on an ambulatory basis, with the neodymium:yttrium-aluminum garnet (Nd:YAG) laser. When used discriminately, laser treatment appears to be an effective modality for the management of selected urethral strictures. Thus far, excellent results have been obtained in 30 of 31 cases of short strictures where laser urethrotomy was performed as the first stricture procedure (average follow-up 10 months). Furthermore, in a series of 36 cases of secondary bladder neck contractures, all of the evaluated patients responded well (average follow-up 7 months). Good results were obtained in only 11 of 48 complicated strictures (average follow-up 14 months). However, while most of these extensive strictures were not eradicated, laser therapy generally produced a documented clinical improvement, comparable to urethrotomy or dilatation, in 15 of these cases. A series of 24 condylomata involving the urethra were treated satisfactorily, with no recurrences (average follow-up 13 months). Laser treatment also has been used successfully for the management of several urethral caruncles, urethral polyps, two meatal hemangiomas, one urethral carcinoma, and a distal duplicated urethra. Recently, the Nd:YAG laser has been applied to the prostatic urethra with vaporization of obstructing median bar hyperplasia. Favorable results have been achieved in 5 of 6 cases treated with a newly developed technique that utilizes direct laser contact. Retrograde ejaculation has not been encountered in these patients (average follow-up 6 months). All of these procedures have been accomplished in the office, largely without urethral catheterization. Lidocaine jelly occasionally supplemented with intravenous sedation provided satisfactory anesthesia. PMID:3400132

  7. Effect of fulvic acid on neodymium uptake by goethite.

    PubMed

    Armstrong, Christopher R; Wood, Scott A

    2012-12-01

    Experimental studies of the interaction of aqueous neodymium (Nd), Suwannee River fulvic acid (FA), and solid phase goethite were conducted. Results from blank systems (individual Nd and FA), binary systems (Nd-goethite, FA-goethite, and Nd-FA), and ternary systems (Nd-FA-goethite) at 0.1 mol/kg and 25°C are reported. In the binary Nd-goethite system a classic sorption edge is observed, whereby virtually all Nd is removed from solution above the goethite point of zero charge (PZC). Similarly, the binary FA-goethite system exhibits strong FA sorption; However in this system near complete removal of FA from solution is observed below the goethite PZC. In the binary Nd-FA system, both aqueous Nd and FA feature a sharp decrease in concentration at ca. pH 9. Various experiments in the ternary system were conducted. For all concentrations, FA enhanced Nd sorption below the goethite PZC, attributed to the formation of a Type B ternary surface complex (mineral-ligand-metal ion). Notably, the 100 ppm FA ternary system showed anomalously high dissolved Nd in solution above the PZC (i.e., Nd sorption suppression) and a concomitant increase in goethite dissolution (∼9 ppm total Fe(3+) observed above circa pH 9.5). Our results suggest that Nd-FA complexation plays a key role in Nd uptake by goethite, and that this process is largely governed by pH: Whereas at pHs below the goethite PZC, Nd-FA complexation facilitates Nd sorption, above the PZC, and particularly at elevated FA concentrations, the formation of aqueous Nd-FA complexes suppresses Nd removal. Moreover, under these conditions, goethite dissolution may also play a role in mitigating Nd uptake by goethite. PMID:22958855

  8. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions

    USGS Publications Warehouse

    Basu, A.R.; Tatsumoto, M.

    1979-01-01

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 ?? 106 to 1300 ?? 106 years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. Copyright ?? 1979 AAAS.

  9. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions.

    PubMed

    Basu, A R; Tatsumoto, M

    1979-07-27

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 x 10(6) to 1300 x 10(6) years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. PMID:17790851

  10. Equilibrium distribution of lanthanum, neodymium, and thorium between lithium chloride melt and liquid bismuth

    NASA Astrophysics Data System (ADS)

    Zagnit'ko, A. V.; Ignat'ev, V. V.

    2013-04-01

    The distribution of lanthanum, neodymium, and thorium between a lithium chloride melt and liquid bismuth with additions of lithium as a reducing agent are investigated at 650°C. Equilibrium values of their distribution constants are measured. It is shown that in contrast to neodymium and lanthanum, thorium cannot be extracted from bismuth into lithium chloride. This allows us to propose an efficient scheme for separating lanthanides and thorium in a system for the extraction of fuel salts in molten-salt nuclear reactors.

  11. Epitaxial neodymium-doped sapphire films, a new active medium for waveguide lasers.

    PubMed

    Kumaran, Raveen; Webster, Scott E; Penson, Shawn; Li, Wei; Tiedje, Thomas; Wei, Peng; Schiettekatte, Francois

    2009-11-01

    Epitaxial films of neodymium-doped sapphire have been grown by molecular beam epitaxy on R-, A-, and M-plane sapphire substrates. The emission spectrum features sharp lines consistent with single-site doping of the Nd(3+) ion into the host crystal. This material is believed to be a nonequilibrium phase, inaccessible by conventional high-temperature growth methods. Neodymium-doped sapphire has a promising lasing line at 1096 nm with an emission cross section of 11.9x10(-19) cm(2), similar to the 1064 nm line of Nd:YVO(4). PMID:19881593

  12. Nanostructured metal foams: synthesis and applications

    SciTech Connect

    Luther, Erik P; Tappan, Bryce; Mueller, Alex; Mihaila, Bogdan; Volz, Heather; Cardenas, Andreas; Papin, Pallas; Veauthier, Jackie; Stan, Marius

    2009-01-01

    Fabrication of monolithic metallic nanoporous materials is difficult using conventional methodology. Here they report a relatively simple method of synthesizing monolithic, ultralow density, nanostructured metal foams utilizing self-propagating combustion synthesis of novel metal complexes containing high nitrogen energetic ligands. Nanostructured metal foams are formed in a post flame-front dynamic assembly with densities as low as 0.011 g/cc and surface areas as high as 270 m{sup 2}/g. They have produced metal foams via this method of titanium, iron, cobalt, nickel, zirconium, copper, palladium, silver, hafnium, platinum and gold. Microstructural features vary as a function of composition and process parameters. Applications for the metal foams are discussed including hydrogen absorption in palladium foams. A model for the sorption kinetics of hydrogen in the foams is presented.

  13. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium.

    PubMed

    Zhu, Wei; Teel, George; O'Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium's osseointegration involves inducing bio-mimetic nanotopography to enhance cell-implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications. PMID:26677327

  14. Enhanced charge storage of ultrathin polythiophene films within porous nanostructures.

    PubMed

    Nejati, Siamak; Minford, Thomas E; Smolin, Yuriy Y; Lau, Kenneth K S

    2014-06-24

    In a single step polymerization and coating, oxidative chemical vapor deposition (oCVD) has been used to synthesize unsubstituted polythiophene. Coatings have been conformally coated within porous nanostructures of anodized aluminum oxide, titanium dioxide, and activated carbon. Significant enhancement in charge capacity has been found with ultrathin polythiophene coatings that preserve the surface area and pore space of the nanostructures. Pseudocapacitors consisting of ultrathin polythiophene coated within activated carbon yielded increases of 50 and 250% in specific and volumetric capacitance compared with bare activated carbon. Devices were stable up to the 5000 cycles tested with only a 10% decrease in capacitance. PMID:24840296

  15. Magnetoresistance and magnetic ordering in praseodymium and neodymium hexaborides

    SciTech Connect

    Anisimov, M. A.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Samarin, N. A.; Filipov, V. B.; Shitsevalova, N. Yu.; Kuznetsov, A. V.; Sluchanko, N. E.

    2009-11-15

    The magnetoresistance {Delta}{rho}/{rho} of single-crystal samples of praseodymium and neodymium hexaborides (PrB{sub 6} and NdB{sub 6}) has been measured at temperatures ranging from 2 to 20 K in a magnetic field of up to 80 kOe. The results obtained have revealed a crossover of the regime from a small negative magnetoresistance in the paramagnetic state to a large positive magnetoresistive effect in magnetically ordered phases of the PrB{sub 6} and NdB{sub 6} compounds. An analysis of the dependences {Delta}{rho}(H)/{rho} has made it possible to separate three contributions to the magnetoresistance for the compounds under investigation. In addition to the main negative contribution, which is quadratic in the magnetic field (-{Delta}{rho}/{rho} {proportional_to} H{sup 2}), a linear positive contribution ({Delta}{rho}/{rho} {proportional_to} H) and a nonlinear ferromagnetic contribution have been found. Upon transition to a magnetically ordered state, the linear positive component in the magnetoresistance of the PrB{sub 6} and NdB{sub 6} compounds becomes dominant, whereas the quadratic contribution to the negative magnetoresistance is completely suppressed in the commensurate magnetic phase of these compounds. The presence of several components in the magnetoresistance has been explained by assuming that, in the antiferromagnetic phases of PrB{sub 6} and NdB{sub 6}, ferromagnetic nanoregions (ferrons) are formed in the 5d band in the vicinity of the rareearth ions. The origin of the quadratic contribution to the negative magnetoresistance is interpreted in terms of the Yosida model, which takes into account scattering of conduction electrons by localized magnetic moments of rare-earth ions. Within the approach used, the local magnetic susceptibility {chi}{sub loc} has been estimated. It has been demonstrated that, in the temperature range T{sub N} < T < 20 K, the behavior of the local magnetic susceptibility {chi}{sub loc} for the compounds under investigation can

  16. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  17. Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

    ERIC Educational Resources Information Center

    Malerich, Charles; Ruff, Patricia K.; Bird, Aubrey

    2004-01-01

    An easy-to-see method for demonstrating and measuring the magnetic force between paramagnetic substance and a rare earth magnet is presented. The readily available trapezoid-shaped neodymium magnet and a low cost, easy-to-set-up, portable apparatus are used in the experiments.

  18. Neodymium YAG lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Various aspects of neodymium yag lasers are discussed in approximately 267 citations. Laser materials and outputs, laser mode locking; crystal, fiber, and nonlinear optics, optical pumping communications, energy conversion efficiency, and laser applications are covered. Pulsed, continuous wave, solid state, Q switched, infrared, and dye lasers are included.

  19. Measurement of the gain in a disk amplification stage with neodymium phosphate glass active elements

    SciTech Connect

    Voronich, Ivan N; Galakhov, I V; Garanin, Sergey G; Eroshenko, V A; Zaretskii, Aleksei I; Zimalin, B G; Ignat'ev, Ivan V; Kirdyashkin, M Yu; Kirillov, G A; Osin, Vladimir A; Rukavishnikov, N N; Sukharev, Stanislav A; Sharov, Oleg A; Charukhchev, Aleksandr V

    2003-06-30

    The measuring technique is described and time-resolved measurements of the small-signal gain as a function of the pump energy in a disk amplification stage with neodymium phosphate glass active elements in the 'Luch' facility are presented. The distribution of the gain over the amplifier aperture in the horizontal plane is measured. (lasers)

  20. Attainment of a high gain in a disk amplifying stage with neodymium phosphate glass elements

    SciTech Connect

    Voronich, Ivan N; Garanin, Sergey G; Zaretskii, Aleksei I; Ignat'ev, Ivan V; Kirillov, G A; Murugov, Vasilii M; Osin, Vladimir A; Sukharev, Stanislav A; Charukhchev, Aleksandr V

    2004-06-30

    An efficient reflecting coating made of a MIRO foil with an oxide layer is fabricated, which enhances the reflection of radiation of pump lamps in the head of a high-power neodymium laser and allows a gain g{sub 0}=5x10{sup -2} cm{sup -1} to be achieved. (lasers)

  1. Praseodymium Nitrate and Neodymium Complexation with Organophosphorus Reagents in Supercritical Carbon Dioxide Solvent

    SciTech Connect

    Robert V. Fox; R. Duane Ball; Peter de B. Harrington; Harry W. Rollins; John G. Jolley; Chien M. Wai

    2004-11-01

    Complex formation reactions of praseodymium nitrate hexahydrate, and neodymium nitrate hexahydrate salts with tri-n-butyl phosphate (TBP) and several other neutral organophosphorus reagents were investigated in supercritical carbon dioxide. The concentration of the metal complexes in the supercritical fluid (SCF) phase was determined using UV-Vis and luminescence spectroscopies. The stoichiometry of the complexes was determined using the mole-ratio method. Extraction equilibrium constants were calculated from the spectral data using least-squares regression and hard-equilibria models. UV-Vis absorbance data indicate that praseodymium nitrate and neodymium nitrate both form 1:4 lanthanide–tributyl phosphate complexes in supercritical carbon dioxide at 308 K. The conditional extraction coefficients for those two systems were calculated to be log Kex=7.45±0.06 for the praseodymium system and log Kex=7.52±0.03 for the neodymium system. For comparison, neodymium nitrate complexation reactions with tri-n-butyl phosphate and tributyl phosphite (TBPO3) were studied in hexane under ambient conditions. UV-Vis data indicate that a 1:4 neodymium–tributyl phosphate complex is formed in hexane with a conditional extraction coefficient of log Kex=3.4±0.2. Tributyl phosphite forms a 1:8 complex with neodymium in hexane with a conditional extraction coefficient of log Kex=11.0±0.1. Neodymium nitrate was titrated with other organophosphorus reagents, tributyl phosphite and tributyl phosphine oxide (TBPO), in supercritical carbon dioxide to investigate differences between neutral oxygen donor ligands and neutral phosphorus donor ligands. UV-Vis and luminescence data indicate that neodymium nitrate forms a 1:8 complex with tributyl phosphite and a 1:5 complex with tributyl phosphine oxide, compared to a 1:4 complex with tri-n-butyl phosphate. The conditional extraction coefficient for the 1:8 neodymium–tributyl phosphite system was calculated as log Kex=21.4±0.2 from UV

  2. Titanium Allergy: A Literature Review

    PubMed Central

    Goutam, Manish; Giriyapura, Chandu; Mishra, Sunil Kumar; Gupta, Siddharth

    2014-01-01

    Titanium has gained immense popularity and has successfully established itself as the material of choice for dental implants. In both medical and dental fields, titanium and its alloys have demonstrated success as biomedical devices. Owing to its high resistance to corrosion in a physiological environment and the excellent biocompatibility that gives it a passive, stable oxide film, titanium is considered the material of choice for intraosseous use. There are certain studies which show titanium as an allergen but the resources to diagnose titanium sensivity are very limited. Attention is needed towards the development of new and precise method for early diagnosis of titanium allergy and also to find out the alternative biomaterial which can be used in place of titanium. A review of available articles from the Medline and PubMed database was done to find literature available regarding titanium allergy, its diagnosis and new alternative material for titanium. PMID:25484409

  3. Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

    PubMed

    Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

    2011-02-01

    In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells. PMID:21207950

  4. Mechanisms of magma generation beneath hawaii and mid-ocean ridges: uranium/thorium and samarium/neodymium isotopic evidence.

    PubMed

    Sims, K W; Depaolo, D J; Murrell, M T; Baldridge, W S; Goldstein, S J; Clague, D A

    1995-01-27

    Measurements of uranium/thorium and samarium/neodymium isotopes and concentrations in a suite of Hawaiian basalts show that uranium/thorium fractionation varies systematically with samarium/neodymium fractionation and major-element composition; these correlations can be understood in terms of simple batch melting models with a garnet-bearing peridotite magma source and melt fractions of 0.25 to 6.5 percent. Midocean ridge basalts shows a systematic but much different relation between uranium/thorium fractionation and samarium/neodymium fractionation, which, although broadly consistent with melting of a garnet-bearing peridotite source, requires a more complex melting model. PMID:17788786

  5. Titanium by design: TRIP titanium alloy

    NASA Astrophysics Data System (ADS)

    Tran, Jamie

    Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

  6. Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

    PubMed Central

    Zhu, Wei; Teel, George; O’Brien, Christopher M; Zhuang, Taisen; Keidar, Michael; Zhang, Lijie Grace

    2015-01-01

    Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing bio-mimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC) attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications. PMID:26677327

  7. High-temperature oxidation of titanium silicide coatings on titanium

    SciTech Connect

    Abba, A.; Caillet, M.; Galerie, A.

    1982-02-01

    Coatings of Ti/sub 5/Si/sub 3/ on titanium have been prepared by means of decomposition of silane SiH/sub 4/ on heated titanium ribbons. Oxidation of the coated titanium specimens was much slower than that of the noncoated ones. Gravimetric and morphological experiments allowed to propose a mechanism describing the oxidation process.

  8. Titanium Cold Spray Coatings

    NASA Astrophysics Data System (ADS)

    Ajaja, Jihane; Goldbaum, Dina; Chromik, Richard; Yue, Stephen; Rezaeian, Ahmad; Wong, Wilson; Irissou, Eric; Legoux, Jean-Gabriel

    Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical properties similar to a traditional bulk material. Vickers hardness testing and nanoindentation were used as micro-and nano-scale measurement techniques to characterize the mechanical properties of titanium coatings, deposited at different deposition conditions, and bulk Ti. The mechanical properties of bulk titanium and titanium coatings were measured over a range of length scales, with the indentation size effect examined with Meyer's law. Hardness measurements are shown to be affected by material porosity, microstructure and coating particle bonding mechanism. Hard-ness measurements showed that Ti coatings deposited at higher gas pressures and temperatures demonstrate an indentation load response similar to bulk Ti. Key words: titanium, cold spray, Vickers hardness, nanoindentation, indentation size effect, microstructure, mechanical properties

  9. Nanostructured composite reinforced material

    DOEpatents

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  10. Titanium metal: extraction to application

    SciTech Connect

    Gambogi, Joseph; Gerdemann, Stephen J.

    2002-09-01

    In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

  11. Mineral of the month: titanium

    USGS Publications Warehouse

    Gambogi, Joseph

    2004-01-01

    From paint to airplanes, titanium is important in a number of applications. Commercial production comes from titanium-bearing ilmenite, rutile and leucoxene (altered ilmenite). These minerals are used to produce titanium dioxide pigment, as well as an assortment of metal and chemical products.

  12. Weld-bonded titanium structures

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Creedon, J. F. (Inventor)

    1976-01-01

    Structurally stronger titanium articles are produced by a weld-bonding technique comprising fastening at least two plates of titanium together using spotwelding and curing an adhesive interspersed between the spot-weld nuggets. This weld-bonding may be employed to form lap joints or to stiffen titanium metal plates.

  13. Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1975-01-01

    Tensile and creep properties of experimental beta-titanium alloys were determined. Titanium-vanadium alloys had substantially greater tensile and creep strength than the titanium-niobium and titanium-molybdenum alloys tested. Specific tensile strengths of several titanium-vanadium-aluminum-silicon alloys were equivalent or superior to those of commercial titanium alloys to temperatures of 650 C. The Ti-50V-3Al-1Si alloy had the best balance of tensile strength, creep strength, and metallurgical stability. Its 500 C creep strength was far superior to that of a widely used commercial titanium alloy, Ti-6Al-4V, and almost equivalent to that of newly developed commercial titanium alloys.

  14. Titanium alkoxide compound

    DOEpatents

    Boyle, Timothy J.

    2007-08-14

    A titanium alkoxide composition is provided, as represented by the chemical formula (OC.sub.6H.sub.5N).sub.2Ti(OC.sub.6H.sub.5NH.sub.2).sub.2. As prepared, the compound is a crystalline substance with a hexavalent titanium atom bonded to two OC.sub.6H.sub.5NH.sub.2 groups and two OC.sub.6H.sub.5N groups with a theoretical molecular weight of 480.38, comprising 60.01% C, 5.04% H and 11.66% N.

  15. Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

    SciTech Connect

    Rosal, Blanca del; Pérez-Delgado, Alberto; Rocha, Ueslen; Martín Rodríguez, Emma; Jaque, Daniel; Misiak, Małgorzata; Bednarkiewicz, Artur; Vanetsev, Alexander S.; Orlovskii, Yurii; Jovanović, Dragana J.; Dramićanin, Miroslav D.; Upendra Kumar, K.; Jacinto, Carlos; Navarro, Elizabeth; and others

    2015-10-14

    The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF{sub 3}:Nd{sup 3+}, SrF{sub 2}:Nd{sup 3+}, NaGdF{sub 4}: Nd{sup 3+}, NaYF{sub 4}: Nd{sup 3+}, KYF{sub 4}: Nd{sup 3+}, GdVO{sub 4}: Nd{sup 3+}, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a “universal” optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymium-doped nanoparticle to be preferentially used in each case.

  16. Neodymium-doped barium borate glasses as fluorescent concentrators for the infrared spectral range

    NASA Astrophysics Data System (ADS)

    Dyrba, Marcel; Wiegand, Marie-Christin; Ahrens, Bernd; Schweizer, Stefan

    2012-06-01

    Neodymium-doped barium borate glasses are investigated for their potential as fluorescent concentrators for the near infrared spectral range. Additional doping of the glasses with silver oxide and subsequent heat treatment leads to a reduction of the doped silver ions and to the formation of metallic silver nanoparticles. The formation of the silver nanoparticles is indicated by a broad surface plasmon-related extinction band at approximately 410 nm. The influence of the silver nanoparticles on the fluorescence properties is investigated.

  17. Long-Pulsed Neodymium-Doped Yttrium Aluminum Garnet Laser for Glomuvenous Malformations in Adolescents.

    PubMed

    Trost, Jaren; Buckley, Colin; Smidt, Aimee C

    2015-01-01

    Currently there exist few reported cases where lasers are used successfully to treat glomuvenous malformations in adolescents. In the two cases described here, we provide evidence that the long-pulsed neodymium-doped yttrium aluminum garnet laser is an effective and safe alternative treatment for these lesions. Our case series is unique because it focuses on adolescents, the population that most often seeks treatment for this dermatologic condition. PMID:26138991

  18. Neodymium(III) Complexation by Amino-Carbohydrates via a Ligand-Controlled Hydrolysis Mechanism

    SciTech Connect

    Levitskaia, Tatiana G.; Chen, Yongsheng; Fulton, John L.; Sinkov, Sergey I.

    2011-07-28

    Chelation of neodymium-III Nd(III) by D-glucosamine (DGA) and chitosan was investigated in solution at near-physiological pH and ionic strength. This research demonstrates the first example of the lanthanide ion heteroleptic hydroxo-carbohydrate complex in solution. It was demonstrated that DGA and chitosan suppressed formation of polynuclear Nd(III) species at elevated pH.

  19. Crystallization of neodymium-rich phases in silicate glasses developed for nuclear waste immobilization

    NASA Astrophysics Data System (ADS)

    Caurant, D.; Majerus, O.; Loiseau, P.; Bardez, I.; Baffier, N.; Dussossoy, J. L.

    2006-08-01

    Glass-ceramics containing neodymium-rich crystalline phases can be obtained by crystallization of silicate glasses (nucleation + crystal growth heat treatments) or by controlled cooling of melts. Such materials could be envisaged as durable matrices for conditioning minor actinides- and Pu-rich nuclear wastes if the partitioning ratio of the wastes between crystalline phase and residual glass is high (principle of double containment barrier). In radioactive waste forms, Nd would be partially substituted by actinides and neutron absorbers (Gd). In this work, two silicate glass compositions leading to efficient nucleation and crystallization of either zirconolite (Ca 1- xNd xZrTi 2- xAl xO 7, x < 1) or apatite (Ca 2Nd 8Si 6O 26) in their bulk were studied as potential waste forms. The effect of the method used to prepare glass-ceramics (controlled cooling from the melt or nucleation + crystal growth from the glass) on both the microstructure and the structure of the neodymium-rich crystalline phase was studied. The highest number of zirconolite or apatite crystals in the bulk was obtained using the nucleation + crystal growth method. However, the percentage of neodymium incorporated in zirconolite crystals remained too small to make realistic the use of such materials for the conditioning of actinides in comparison with more durable bulk ceramics.

  20. Structural and optical properties of calcium neodymium hexaaluminates single crystals, potential laser materials

    NASA Astrophysics Data System (ADS)

    Alablanche, S.; Kahn-Harari, A.; Thery, J.; Viana, B.; Vivien, D.; Dexpert-Ghys, J.; Faucher, M.

    1992-05-01

    The structural and optical properties of calcium-neodymium hexaaluminates crystals Ca 1- xNd xMg x Al 12- xO 19 (labeled Ca 1- xNd x) with a magnetoplumbite (MP) structure are investigated. The floating zone method is used to grow single crystals in the composition range 0.1 ≤ x ≤ 0.7, although for high calcium content, the melting of the compounds is no longer congruent. The X-ray structural determination, optical absorption at 4 K, and ESR investigation agree in the localization of Nd 3+ at the regular large cations site of the MP structure with axial ( D3 h) symmetry. A set of crystal field and free ion parameters which fits the absorption spectrum of Nd 3+ in this site is calculated. When x increases, Nd 3+ ions tend to occupy also a second site with lower symmetry. Moreover some anomalous behavior observed in the absorption and ESR spectra at high neodymium concentration may be related to Nd 3+-Nd 3+ ion pairing. Fluorescence intensity and lifetime measurements as a function of the x value are reported. There is evidence of strong cross-relaxation between neighboring neodymium ions for high x values. The results obtained for the Ca 1- xNd x compounds can be extended to other series in which Nd 3+ is replaced by another lanthanide ion. Preliminary investigations have been performed with Pr 3+ and are also reported.

  1. Single crystal growth and characterization of lanthanum-neodymium oxalate octahydrate

    NASA Astrophysics Data System (ADS)

    Want, Basharat

    2011-11-01

    Single crystals of mixed lanthanum-neodymium oxalates are grown by gel diffusion method using agar gel as a medium of growth. The crystals grow in the agar gel with hexagonal morphology having (001), (110) and (010) as habit faces. Single crystal X-ray diffraction results show that the crystals belong to monoclinic system with cell parameters; a=10.344(2) Å, b=9.643(6) Å, c=11.721(2) Å, β=118.7 (2)° , bearing the space group P2/c. Fourier transform infrared spectrum of the crystals indicates the presence of water and other functional groups associated with the oxalate ions. Thermogravimetric and differential thermal analysis support the presence of 8H 2O molecules attached to the lanthanum-neodymium crystal lattice. The thermal decomposition in the nitrogen atmosphere leads to the formation of mixed lanthanum-neodymium oxide as the final product. Energy dispersive analysis of X-rays along with elemental analysis suggests the stoichiometry of the gel grown crystals to be La 1.5Nd 0.5(C 2O 4) 3·8H 2O.

  2. Sorting Titanium Welding Rods

    NASA Technical Reports Server (NTRS)

    Ross, W. D., Jr.; Brown, R. L.

    1985-01-01

    Three types of titanium welding wires identified by their resistance to current flow. Welding-wire tester quickly identifies unknown titaniumalloy wire by touching wire with test probe, and comparing meter response with standard response. Before touching wire, tip of test probe dipped into an electrolyte.

  3. Sintering titanium powders

    SciTech Connect

    Gerdemann, Stephen J.; Alman, David E.

    2005-09-01

    Recently, there has been renewed interest in low-cost titanium. Near-net-shape powder metallurgy offers the potential of manufacturing titanium articles without costly and difficult forming and machining operations; hence, processing methods such as conventional press-and-sinter, powder forging and powder injection molding are of interest. The sintering behavior of a variety of commercial and experimental titanium powders was studied. Commercial powders were acquired that were produced different routes: (i) sponge fines from the primary titanium processing; (ii) via the hydride-dehydride process; and (iii) gas atomization. The influence of vacuum sintering time (0.5 to 32 hrs) and temperature (1200, 1275 or 1350°C) on the microstructure (porosity present) of cold pressed powders was studied. The results are discussed in terms of the difference in powder characteristics, with the aim of identify the characteristics required for full density via press-and-sinter processing. Near-net-shape tensile bars were consolidated via cold pressed and sintered. After sintering, a sub-set of the tensile bars was hot-isostatic pressed (HIPed). The microstructure and properties of the bars were compared in the sintered and HIPed conditions.

  4. Evidence of antibacterial activity on titanium surfaces through nanotextures

    NASA Astrophysics Data System (ADS)

    Seddiki, O.; Harnagea, C.; Levesque, L.; Mantovani, D.; Rosei, F.

    2014-07-01

    Nosocomial infections (Nis) are a major concern for public health. As more and more of the pathogens responsible for these infections are antibiotic resistant, finding new ways to overcome them is a major challenge for biomedical research. We present a method to reduce Nis spreading by hindering bacterial adhesion in its very early stage. This is achieved by reducing the contact interface area between the bacterium and the surface by nanoengineering the surface topography. In particular, we studied the Escheria Coli adhesion on titanium surfaces exhibiting different morphologies, that were obtained by a combination of mechanical polishing and chemical etching. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) characterization revealed that the titanium surface is modified at both micro- and nano-scale. X-ray Photoelectron Spectroscopy (XPS) revealed that the surfaces have the same composition before and after piranha treatment, consisting mainly of TiO2. Adhesion tests showed a significant reduction in bacterial accumulation on nanostructured surfaces that had the lowest roughness over large areas. SEM images acquired after bacterial culture on different titanium substrates confirmed that the polished titanium surface treated one hour in a piranha solution at a temperature of 25 °C has the lowest bacterial accumulation among all the surfaces tested. This suggests that the difference observed in bacterial adhesion between the different surfaces is due primarily to surface topography.

  5. Osteogenic activity of titanium surfaces with nanonetwork structures

    PubMed Central

    Xing, Helin; Komasa, Satoshi; Taguchi, Yoichiro; Sekino, Tohru; Okazaki, Joji

    2014-01-01

    Background Titanium surfaces play an important role in affecting osseointegration of dental implants. Previous studies have shown that the titania nanotube promotes osseointegration by enhancing osteogenic differentiation. Only relatively recently have the effects of titanium surfaces with other nanostructures on osteogenic differentiation been investigated. Methods In this study, we used NaOH solutions with concentrations of 2.5, 5.0, 7.5, 10.0, and 12.5 M to develop a simple and useful titanium surface modification that introduces the nanonetwork structures with titania nanosheet (TNS) nanofeatures to the surface of titanium disks. The effects of such a modified nanonetwork structure, with different alkaline concentrations on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMMSCs), were evaluated. Results The nanonetwork structures with TNS nanofeatures induced by alkali etching markedly enhanced BMMSC functions of cell adhesion and osteogenesis-related gene expression, and other cell behaviors such as proliferation, alkaline phosphatase activity, extracellular matrix deposition, and mineralization were also significantly increased. These effects were most pronounced when the concentration of NaOH was 10.0 M. Conclusion The results suggest that nanonetwork structures with TNS nanofeatures improved BMMSC proliferation and induced BMMSC osteogenic differentiation. In addition, the surfaces formed with 10.0 M NaOH suggest the potential to improve the clinical performance of dental implants. PMID:24741311

  6. Diameter of titanium nanotubes influences anti-bacterial efficacy

    NASA Astrophysics Data System (ADS)

    Ercan, Batur; Taylor, Erik; Alpaslan, Ece; Webster, Thomas J.

    2011-07-01

    Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.

  7. Titanium dioxide nanoswords with highly reactive, photocatalytic facets

    NASA Astrophysics Data System (ADS)

    Sosnowchik, Brian D.; Chiamori, Heather C.; Ding, Yong; Ha, Jong-Yoon; Wang, Zhong Lin; Lin, Liwei

    2010-12-01

    Titanium dioxide (TiO2) is one of the most widely studied and important materials for catalysis, photovoltaics, and surface science applications, but the ability to consistently control the relative exposure of higher surface energy facets during synthesis remains challenging. Here, we present the repeatable synthesis of highly reactive, rutile {001} or {101} facets on broad, sword-shaped TiO2 nanostructures rapidly synthesized in minutes. Growth occurs along planes of lower surface energy, repeatedly yielding nanostructures with large, high energy facets. The quantitative photocatalytic reactivity of the nanoswords, demonstrated by the photoreduction of silver, is over an order of magnitude higher than reference low energy TiO2{110} substrates. Therefore, the higher surface energy dominated TiO2 nanoswords are ideal structures for characterizing the physicochemical properties of rutile TiO2, and may be used to enhance a variety of catalytic, optical, and clean-technology applications.

  8. Nanostructured hematite for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Ling, Yichuan

    Solar water splitting is an environmentally friendly reaction of producing hydrogen gas. Since Honda and Fujishima first demonstrated solar water splitting in 1972 by using semiconductor titanium dioxide (TiO2) as photoanode in a photoelectrochemical (PEC) cell, extensive efforts have been invested into improving the solar-to-hydrogen (STH) conversion efficiency and lower the production cost of photoelectrochemical devices. In the last few years, hematite (alpha-Fe2O3) nanostructures have been extensively studied as photoanodes for PEC water splitting. Although nanostructured hematite can improve its photoelectrochemical water splitting performance to some extent, by increasing active sites for water oxidation and shortening photogenerated hole path length to semiconductor/electrolyte interface, the photoactivity of pristine hematite nanostructures is still limited by a number of factors, such as poor electrical conductivities and slow oxygen evolution reaction kinetics. Previous studies have shown that tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their optical and electrical properties. In this thesis, I will first demonstrate an unintentional Sn-doping method via high temperature annealing of hematite nanowires grown on fluorine-doped tin oxide (FTO) substrate to enhance the donor density. In addition to introducing extrinsic dopants into semiconductors, the carrier densities of hematite can also be enhanced by creating intrinsic defects. Oxygen vacancies function as shallow donors for a number of hematite. In this regard, I have investigated the influence of oxygen content on thermal decomposition of FeOOH to induce oxygen vacancies in hematite. In the end, I have studied low temperature activation of hematite nanostructures.

  9. Controlled implant/soft tissue interaction by nanoscale surface modifications of 3D porous titanium implants

    NASA Astrophysics Data System (ADS)

    Rieger, Elisabeth; Dupret-Bories, Agnès; Salou, Laetitia; Metz-Boutigue, Marie-Helene; Layrolle, Pierre; Debry, Christian; Lavalle, Philippe; Engin Vrana, Nihal

    2015-05-01

    Porous titanium implants are widely employed in the orthopaedics field to ensure good bone fixation. Recently, the use of porous titanium implants has also been investigated in artificial larynx development in a clinical setting. Such uses necessitate a better understanding of the interaction of soft tissues with porous titanium structures. Moreover, surface treatments of titanium have been generally evaluated in planar structures, while the porous titanium implants have complex 3 dimensional (3D) architectures. In this study, the determining factors for soft tissue integration of 3D porous titanium implants were investigated as a function of surface treatments via quantification of the interaction of serum proteins and cells with single titanium microbeads (300-500 μm in diameter). Samples were either acid etched or nanostructured by anodization. When the samples are used in 3D configuration (porous titanium discs of 2 mm thickness) in vivo (in subcutis of rats for 2 weeks), a better integration was observed for both anodized and acid etched samples compared to the non-treated implants. If the implants were also pre-treated with rat serum before implantation, the integration was further facilitated. In order to understand the underlying reasons for this effect, human fibroblast cell culture tests under several conditions (directly on beads, beads in suspension, beads encapsulated in gelatin hydrogels) were conducted to mimic the different interactions of cells with Ti implants in vivo. Physical characterization showed that surface treatments increased hydrophilicity, protein adsorption and roughness. Surface treatments also resulted in improved adsorption of serum albumin which in turn facilitated the adsorption of other proteins such as apolipoprotein as quantified by protein sequencing. The cellular response to the beads showed considerable difference with respect to the cell culture configuration. When the titanium microbeads were entrapped in cell

  10. Understanding the biological responses of nanostructured metals and surfaces

    NASA Astrophysics Data System (ADS)

    Lowe, Terry C.; Reiss, Rebecca A.

    2014-08-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science.

  11. Synthesis of 0.1% & 0.2% neodymium doped barium zirconium titanate (BaZr0.2Ti0.8O3) and study of their dielectric behaviour

    NASA Astrophysics Data System (ADS)

    Kumar, Anil; Kumar, Vipin; Gupta, Merry; Ghumman, S. S.

    2015-08-01

    Efforts have been made to ease process of producing widely used multilayered ceramics of Barium Zirconium Titanium Oxides and study their dielectric behaviour and structural properties. For this purpose, adequate proportions of Barium Carbonate, Zirconium Oxide and Titanium Oxide were taken and hand milled for 2 hours. Neodymium composition of the order of 0.1% and 0.2% was used for doping to weight percentage of BaZr0.2Ti0.8O3. The samples were authenticated using raw data obtained from Bruker AXS D8 advance Copper KL alpha source XRD equipment. Further, the samples were studied for their phase transition, composition, single phase perovskite structure using XRD technique. The technique has also been applied to know formation of stable homogeneous solid solution from XRD parameters. The other physical parameters like the morphology, micro structural information, crystal arrangements and topography have also been observed through SEM. The SEM has revealed information related to grain size development and composition of sample with fine agglomerates. For complete study of the compounds the atomic and weight composition has also been examined by Electron Dispersive Spectroscopy patterns. The comparison has been made with other works on ceramics at various frequencies and has yielded very interesting results.

  12. Synthesis of 0.1% & 0.2% neodymium doped barium zirconium titanate (BaZr{sub 0.2}Ti{sub 0.8}O{sub 3}) and study of their dielectric behaviour

    SciTech Connect

    Kumar, Anil Kumar, Vipin; Gupta, Merry; Ghumman, S. S.

    2015-08-28

    Efforts have been made to ease process of producing widely used multilayered ceramics of Barium Zirconium Titanium Oxides and study their dielectric behaviour and structural properties. For this purpose, adequate proportions of Barium Carbonate, Zirconium Oxide and Titanium Oxide were taken and hand milled for 2 hours. Neodymium composition of the order of 0.1% and 0.2% was used for doping to weight percentage of BaZr0.2Ti0.8O3. The samples were authenticated using raw data obtained from Bruker AXS D8 advance Copper KL alpha source XRD equipment. Further, the samples were studied for their phase transition, composition, single phase perovskite structure using XRD technique. The technique has also been applied to know formation of stable homogeneous solid solution from XRD parameters. The other physical parameters like the morphology, micro structural information, crystal arrangements and topography have also been observed through SEM. The SEM has revealed information related to grain size development and composition of sample with fine agglomerates. For complete study of the compounds the atomic and weight composition has also been examined by Electron Dispersive Spectroscopy patterns. The comparison has been made with other works on ceramics at various frequencies and has yielded very interesting results.

  13. Corrosion of stainless steel, nickel-titanium, coated nickel-titanium, and titanium orthodontic wires.

    PubMed

    Kim, H; Johnson, J W

    1999-02-01

    Orthodontic wires containing nickel have been implicated in allergic reactions. The potential for orthodontic wires to cause allergic reactions is related to the pattern and mode of corrosion with subsequent release of metal ions, such as nickel, into the oral cavity. The purpose of this study was to determine if there is a significant difference in the corrosive potential of stainless steel, nickel titanium, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium orthodontic wires. At least two specimens of each wire were subjected to potentiostatic anodic dissolution in 0.9% NaCl solution with neutral pH at room temperature. Using a Wenking MP 95 potentiostat and an electrochemical corrosion cell, the breakdown potential of each wire was determined. Photographs were taken of the wire speci mens using a scanning electron microscope, and surface changes were qualitatively evaluated. The breakdown potentials of stainless steel, two nickel titanium wires, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium were 400 mV, 300 mV, 750 mV, 300 mV, 1800 mV, and >2000 mV, respectively. SEM photographs revealed that some nickel titanium and stainless steel wires were susceptible to pitting and localized corrosion. The results indicate that corrosion occurred readily in stainless steel. Variability in breakdown potential of nickel titanium alloy wires differed across vendors' wires. The nitride coating did not affect the corrosion of the alloy, but epoxy coating decreased corrosion. Titanium wires and epoxy-coated nickel titanium wires exhibited the least corrosive potential. For patients allergic to nickel, the use of titanium or epoxy-coated wires during orthodontic treatment is recommended. PMID:10022183

  14. Hydride precipitation in titanium

    SciTech Connect

    Numakura, H.; Kowia, M.

    1984-10-01

    The crystal structure and morphology of hydride (deuteride) precipitates are investigated on ..cap alpha..-titanium specimens containing 1-3 at.% H or D by transmission electron microscopy. The hydride is found to have a face-centered tetragonal structure (c/a = 1.09) with an ordered arrangement of hydrogen, being isomorphous to ..gamma..-zirconium hydride. Two types of precipitation mode are observed with the habit planes (0110) and near (0225).

  15. Titanium Honeycomb Panel Testing

    NASA Technical Reports Server (NTRS)

    Richards, W. Lance; Thompson, Randolph C.

    1996-01-01

    Thermal-mechanical tests were performed on a titanium honeycomb sandwich panel to experimentally validate the hypersonic wing panel concept and compare test data with analysis. Details of the test article, test fixture development, instrumentation, and test results are presented. After extensive testing to 900 deg. F, non-destructive evaluation of the panel has not detected any significant structural degradation caused by the applied thermal-mechanical loads.

  16. Surface-hardened nanostructured Ti- and Zr-matrix composites for medical and engineering applications

    NASA Astrophysics Data System (ADS)

    Sharkeev, Yu. P.; Kukareko, V. A.; Legostaeva, E. V.; Byeli, A. V.

    2011-03-01

    Combined studies have been conducted on the structural-phase state and physical-mechanical and tribological properties of nanostructured titanium and zirconium subjected to ion-beam implantation or microplasma oxidation. Low-temperature ion-beam nitriding of the materials examined is shown to provide a 25-35-fold increase in the wear resistance of their surface layers and a 40% decrease in the friction coefficient for tribological interaction with contact surfaces. Microplasma oxidation of titanium in aqueous solution of phosphoric acid, hydroxylapatite and calcium carbonate powders enables calcium-phosphate coatings with high physical-mechanical properties to be produced. Tribological tests in a dry friction regime and in isotonic solution of sodium chloride have revealed that a nanostructured titanium substrate-calcium phosphate coating biocomposite exhibits a fairly high friction coefficient (0.4-1.0) in tribological interactions with ultrahigh molecular-weight polyethylene or bone tissue. A substantial improvement in the tribotechnical properties of nanostructured titanium and zirconium with modified surface layers makes them very promising materials for medical and engineering applications.

  17. Titanium fasteners. [for aircraft industry

    NASA Technical Reports Server (NTRS)

    Phillips, J. L.

    1972-01-01

    Titanium fasteners are used in large quantities throughout the aircraft industry. Most of this usage is in aluminum structure; where titanium structure exists, titanium fasteners are logically used as well. Titanium fasteners offer potential weight savings to the designer at a cost of approximately $30 per pound of weight saved. Proper and least cost usage must take into consideration type of fastener per application, galvanic couples and installation characteristics of protective coatings, cosmetic appearance, paint adhesion, installation forces and methods available and fatigue performance required.

  18. Titanium: light, strong, and white

    USGS Publications Warehouse

    Woodruff, Laurel; Bedinger, George

    2013-01-01

    Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

  19. INDUSTRIAL PROCESS PROFILES FOR ENVIRONMENTAL USE: CHAPTER 26. TITANIUM INDUSTRY

    EPA Science Inventory

    The titanium industry produces two principal products, titanium metal and titanium dioxide. For purposes of analyses, therefore, the industry is considered in two segments: titanium metal production and titanium dioxide production. Two industrial process flow diagrams and eleven ...

  20. Nanostructured Oxides and Sulfides for Thermoelectrics

    NASA Astrophysics Data System (ADS)

    Koumoto, Kunihito

    2011-03-01

    Thermoelectric power generation can be applied to various heat sources, both waste heat and renewable energy, to harvest electricity. Even though each heat source is of a small scale, it would lead to a great deal of energy saving if they are combined and collected, and it would greatly contribute to reducing carbon dioxide emission. We have been engaged in developing novel thermoelectric materials to be used for energy saving and environmental protection and are currently developing nanostructured ceramics for thermoelectric conversion. We have demonstrated a quantum confinement effect giving rise to two dimensional electron gas (2DEG) in a 2D superlattice, STO/STO:Nb (STO: strontium titanate), which could generate giant thermopower while keeping high electrical conductivity. One unit-cell thick Nb-doped well layer was estimated to show ZT=2.4 at 300K. Then, a ``synergistic nanostructuring'' concept incorporating 2DEG grain boundaries as well as nanosizing of grains has been applied to our STO material and 3D superlattice ceramics was designed and proposed. It was verified by numerical simulation that this 3D superlattice ceramics should be capable of showing ZT=1.0 at 300K which is comparable to or even higher than that of conventional bismuth telluride-based thermoelectrics. We have recently proposed titanium disulfide-based misfit-layered compounds as novel TE materials. Insertion of misfit-layers into the van der Waals gaps in layer-structured titanium disulfide thus forming a natural superlattice gives rise to internal nanointerfaces and dramatically reduces its lattice thermal conductivity. ZT value reaches 0.37 at 673 K even without optimization of electronic properties. Our challenge to further increase ZT by controlling their electronic system and superlattice structures will be presented.

  1. Bioinspired chemistry: Rewiring nanostructures

    NASA Astrophysics Data System (ADS)

    Ulijn, Rein V.; Caponi, Pier-Francesco

    2010-07-01

    The cell's dynamic skeleton, a tightly regulated network of protein fibres, continues to provide inspiration for the design of synthetic nanostructures. Genetic engineering has now been used to encode non-biological functionality within these structures.

  2. Measuring Strong Nanostructures

    ScienceCinema

    Andy Minor

    2010-01-08

    Andy Minor of Berkeley Lab's National Center for Electron Microscopy explains measuring stress and strain on nanostructures with the In Situ Microscope. More information: http://newscenter.lbl.gov/press-relea...

  3. Measuring Strong Nanostructures

    SciTech Connect

    Andy Minor

    2008-10-16

    Andy Minor of Berkeley Lab's National Center for Electron Microscopy explains measuring stress and strain on nanostructures with the In Situ Microscope. More information: http://newscenter.lbl.gov/press-relea...

  4. Improving of the operation efficiency of the vehicle due to using of the neodymium magnets inside the vibration isolation devices

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.

    2015-09-01

    In this paper the isolation suspension with stiffness compensator based on neodymium magnets is suggested. It was found that the passive vibration isolators not completely sufficient of modern requirement of the vibration isolation. It was determined that the neodymium magnets with the same initial parameters are most effective in comparison with DC current electromagnets. The mathematical model of the vibration isolation suspension has been developed. In this research the traction characteristics for given magnets are presented. Also the design of the vibration isolation suspension with compensator of the stiffness based on neodymium magnets has been developed. This research has been performed under support of the President scholarship for young scientists under the order of Russian Federation Ministry of the education and science No 184 from 10th of March 2015.

  5. Understanding bactericidal performance on ambient light activated TiO2-InVO4 nanostructured films.

    PubMed

    He, Ziming; Xu, Qingchi; Tan, Timothy Thatt Yang

    2011-12-01

    TiO(2)-InVO(4) nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO(2)-InVO(4) nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO(4) and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO(2) film, the current TiO(2)-InVO(4) films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell "photo-fixation" was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film. PMID:22012408

  6. Titanium Optics for Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Soulas, George C.; Haag, Thomas W.; Patterson, Michael J.; Rawlin, Vincent K.

    1999-01-01

    Ion thruster total impulse capability is limited, in part, by accelerator grid sputter erosion. A development effort was initiated to identify a material with a lower accelerator grid volumetric sputter erosion rate than molybdenum, but that could utilize the present NSTAR thruster grid design and fabrication techniques to keep development costs low, and perform as well as molybdenum optics. After comparing the sputter erosion rates of several atomic materials to that of molybdenum at accelerator voltages, titanium was found to offer a 45% reduction in volumetric erosion rates. To ensure that screen grid sputter erosion rates are not higher at discharge chamber potentials, titanium and molybdenum sputter erosion rates were measured at these potentials. Preliminary results showed only a slightly higher volumetric erosion rate for titanium, so that screen grid erosion is insignificant. A number of material, thermal, and mechanical properties were also examined to identify any fabrication, launch environment, and thruster operation issues. Several titanium grid sets were successfully fabricated. A titanium grid set was mounted onto an NSTAR 30 cm engineering model ion thruster and tested to determine optics performance. The titanium optics operated successfully over the entire NSTAR power range of 0.5 to 2.3 kW. Differences in impingement-limited perveances and electron backstreaming limits were found to be due to a larger cold gap for the titanium optics. Discharge losses for titanium grids were lower than those for molybdenum, likely due to a slightly larger titanium screen grid open area fraction. Radial distributions of beam current density with titanium optics were very similar to those with molybdenum optics at all power levels. Temporal electron backstreaming limit measurements showed that titanium optics achieved thermal equilibrium faster than molybdenum optics.

  7. Architectures for Nanostructured Batteries

    NASA Astrophysics Data System (ADS)

    Rubloff, Gary

    2013-03-01

    Heterogeneous nanostructures offer profound opportunities for advancement in electrochemical energy storage, particularly with regard to power. However, their design and integration must balance ion transport, electron transport, and stability under charge/discharge cycling, involving fundamental physical, chemical and electrochemical mechanisms at nano length scales and across disparate time scales. In our group and in our DOE Energy Frontier Research Center (www.efrc.umd.edu) we have investigated single nanostructures and regular nanostructure arrays as batteries, electrochemical capacitors, and electrostatic capacitors to understand limiting mechanisms, using a variety of synthesis and characterization strategies. Primary lithiation pathways in heterogeneous nanostructures have been observed to include surface, interface, and both isotropic and anisotropic diffusion, depending on materials. Integrating current collection layers at the nano scale with active ion storage layers enhances power and can improve stability during cycling. For densely packed nanostructures as required for storage applications, we investigate both ``regular'' and ``random'' architectures consistent with transport requirements for spatial connectivity. Such configurations raise further important questions at the meso scale, such as dynamic ion and electron transport in narrow and tortuous channels, and the role of defect structures and their evolution during charge cycling. Supported as part of the Nanostructures for Electrical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160

  8. Reactive sputtering of titanium diboride and titanium disilicide

    SciTech Connect

    Maya, L.; Vallet, C.E.; Fiedor, J.N.

    1997-07-01

    Nanocomposite films of titanium nitride in either boron nitride or silicon nitride matrices were prepared by reactive sputtering of titanium diboride or titanium disilicide targets in a nitrogen plasma. These films were expected to have high dielectric constants and in the case of the silicon nitride matrix high hardness. The films were characterized by a variety of physicochemical techniques including photoelectron spectroscopy, Rutherford backscattering spectroscopy, RBS, and transmission electron microscopy. The films derived from titanium diboride incorporated oxygen as an inadvertent impurity in the form of titanium monoxide and dioxide. A silicon oxynitride underlayer is suggested by the RBS analysis of the silicon nitride based film, apparently arising from exposure of the native oxide on silicon to the nitrogen plasma. Capacitance measurements of the films showed moderately high dielectric constants of about 30{endash}60 and a hardness of 11 GPa for the silicon nitride nanocomposite. {copyright} {ital 1997 American Vacuum Society.}

  9. CONTROL OF LASER RADIATION PARAMETERS: New nanosecond polymer passive switch for neodymium lasers

    NASA Astrophysics Data System (ADS)

    Bezrodnyi, V. I.; Vovk, L. V.; Derevyanko, Nadezhda A.; Ishchenko, Aleksandr A.; Karabanova, L. V.; Mushkalo, I. L.

    1995-03-01

    A new nanosecond passive switch for neodymium lasers was developed on the basis of a highly elastic polyurethane matrix with an optical strength of 1200 MW cm-2, containing a photostable organic dye NOK. The switch was investigated under various Q-switching conditions in YAG, GSGG : Cr : Nd, and yttrium aluminate crystal lasers. Nanosecond single giant pulses and bursts of pulses were generated. The service life was 2×106 pulses at a single point of the switch. The energy of giant single pulses was 0.9 J. Repetition of single pulses at 50 Hz was possible.

  10. Laser amplifier based on a neodymium glass rod 150 mm in diameter

    SciTech Connect

    Shaykin, A A; Fokin, A P; Soloviev, A A; Kuzmin, A A; Shaikin, I A; Burdonov, K F; Khazanov, E A; Charukhchev, A V

    2014-05-30

    A unique large-aperture neodymium glass rod amplifier is experimentally studied. The small-signal gain distribution is measured at different pump energies. The aperture-averaged gain is found to be 2.3. The stored energy (500 J), the maximum possible pump pulse repetition rate, and the depolarisation in a single pulse and in a series of pulses with a repetition rate of one pulse per five minutes are calculated based on the investigations performed. It is shown that the use of this amplifier at the exit of the existing laser can increase the output pulse energy from 300 to 600 J. (lasers)

  11. Neodymium and lead isotope evidence for enriched early Archean crust in North America

    NASA Technical Reports Server (NTRS)

    Bowring, Samuel A.; Housh, Todd B.; Isachsen, Clark E.; Podosek, Frank A.; King, Janet E.

    1989-01-01

    Neodymium and lead isotope measurements and uranium-lead zircon geochronology from Archaean gneisses of the Slave Province in the Northwest Territories of Canada are reported. The gneisses contain zircons with cores older than 3.842 Gyr and an epsilon(Nd) (3.7 Gyr) of - 4.8. This is the oldest reported chondritic model age for a terrestrial sample and provides evidence for strongly enriched pre-3.8-Gyr crust, a reservoir complementary to the depleted mantle already in existence by 3.8 Gyr before the present.

  12. Neodymium neutron transmission and capture measurements and development of a new transmission detector

    NASA Astrophysics Data System (ADS)

    Barry, Devin P.

    Neodymium is a 235U fission product and is important in reactor neutronic calculations. The aim of this thesis is to improve upon the existing neutron cross section data of neodymium. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m flight station with a 16-segment Nal multiplicity detector, and the transmission measurements were performed at 15-m and 25-m flight stations, respectively, with 6Li glass scintillation detectors. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes were deduced within the energy range of 1.0 eV to 500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 1 barns that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters. This thesis also explains the resolution function in detail and discusses its importance when fitting experimental data to extract resonance parameters. More accurate resolution function parameters were determined for epithermal transmission and capture measurements by fitting well known resonances in Uranium-238. Improved transmission bare-bounce target in-beam photomultiplier tube (PMT) resolution function parameters were found and compared to those used previously at the RPI LINAC and a marked improvement in the quality of the fits is shown. In addition

  13. Retinal detachment as a complication of neodymium: yttrium aluminum garnet laser cyclophotocoagulation.

    PubMed

    Geyer, O; Neudorfer, M; Lazar, M

    1993-05-01

    We report a traction retinal detachment that developed within one month of transscleral neodymium: yttrium aluminum garnet (Nd:YAG) laser cyclophotocoagulation, a previously unreported complication of the new cyclodestructive procedure. A 17-year-old boy was referred to our department with uncontrolled aphakic glaucoma OD after having undergone cyclocryotherapy twice. Three treatments with transscleral Nd:YAG cyclophotocoagulation were done over nine months to lower his intraocular pressure. Hypotony and traction retinal detachment occurred after the third laser treatment and was managed successfully by vitrectomy with a fluid-gas exchange. Thus, the possibility of this additional complication should be remembered when doing transscleral Nd:YAG cyclophotocoagulation. PMID:8517586

  14. Decreased cervical cancer cell adhesion on nanotubular titanium for the treatment of cervical cancer

    PubMed Central

    Crear, Jara; Kummer, Kim M; Webster, Thomas J

    2013-01-01

    Cervical cancer can be treated by surgical resection, chemotherapy, and/or radiation. Titanium biomaterials have been suggested as a tool to help in the local delivery of chemotherapeutic agents and/or radiation to cervical cancer sites. However, current titanium medical devices used for treating cervical cancer do not by themselves possess any anticancer properties; such devices act as carriers for pharmaceutical agents or radiation sources and may even allow for the growth of cancer cells. Based on studies, which have demonstrated decreased lung, breast, and bone cancer cell functions on nanostructured compared to nanosmooth polymers, the objective of the present in vitro study was to modify titanium to possess nanotubular surface features and determine cervical cancer cell adhesion after 4 hours. Here, titanium was anodized to possess nanotubular surface features. Results demonstrated the ability to decrease cervical cancer cell adhesion by about a half on nanotubular compared to currently used nanosmooth titanium (without the use of chemotherapeutics or radiation), opening up numerous possibilities for the use of nanotubular titanium in local drug delivery or radiation treatment of cervical cancer. PMID:23493522

  15. Structure and photocatalysis activity of silver doped titanium oxide nanotubes array for degradation of pollutants

    NASA Astrophysics Data System (ADS)

    Al-Arfaj, E. A.

    2013-10-01

    Semiconductor titanium oxide showed a wonderful performance as a photocatalysis for environmental remediation. Owing to high stability and promising physicochemical properties, titanium oxide nanostructures are used in various applications such as wastewater treatment, antimicrobial and air purification. In the present study, titanium oxide nanotubes and silver doped titanium oxide nanotubes were synthesized via anodic oxidation method. The morphology and composition structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results depicted that nanotubes possess anatase phase with average tube diameter of 65 nm and 230 ± 12 nm in length. The band gap of the un-doped and silver doped titanium dioxide nanotubes was determined using UV-Vis. spectrophotometer. The results showed that the band gap of titanium dioxide nanotubes is decreased when doped with silver ions. The photocatalysis activity of un-doped and silver doped TiO2 nanotubes were evaluated in terms of degradation of phenol in the presence of ultra violet irradiation. It was found that silver doped TiO2 nanotubes exhibited much higher photocatalysis activity than un-doped TiO2 nanotubes.

  16. Anodic behavior of alloys in the systems aluminum-scandium(yttrium, praseodymium, neodymium) in a neutral medium

    SciTech Connect

    Ganiev, I.N.; Yunusov, I.; Krasnoyarskii, V.V.

    1988-03-10

    The authors investigated the influence of scandium, yttrium, praseodymium, and neodymium on the anodic behavior of aluminum in a 3% sodium chloride solution by a potentiodynamic method which provided information over a time interval during which the state of the electrode surface and the composition of the solution remained essentially unchanged. Data were derived for electrochemical and pitting corrosion for different alloy contents and compositions. Results were analyzed for aluminum-scandium, aluminum-yttrium, aluminum-praseodymium, and aluminum-neodymium binary systems.

  17. Understanding bactericidal performance on ambient light activated TiO2-InVO4 nanostructured films

    NASA Astrophysics Data System (ADS)

    He, Ziming; Xu, Qingchi; Yang Tan, Timothy Thatt

    2011-12-01

    TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film.TiO2-InVO4 nanostructured films were coated onto glass substrates and systematically investigated for their bactericidal activities using Escherichia coli (E. coli) as the model bacterium under ambient light illumination. The uniform TiO2-InVO4 nanostructured films were prepared using titanium isopropoxide (TTIP) as the precursor via a simple sol-gel approach. Polyethylenimine (PEI) was used as a surfactant to ensure uniform dispersion of InVO4 and a sacrificial pore-inducing agent, generating nanostructured films. Compared to unmodified TiO2 film, the current TiO2-InVO4 films exhibited enhanced bactericidal activities under ambient light illumination. Bacterial cell ``photo-fixation'' was demonstrated to be crucial in enhancing the bactericidal activity. A bacterial-nanostructured surface interaction mechanism was proposed for the current ambient-light activated nanostructured film. Electronic supplementary information (ESI) available: Photocatalytic activity test procedure and results, AFM images, EDX results, LSCM images, and wettability results. See DOI: 10.1039/c1nr11126d

  18. Final Technical Report: Nanostructured Shape Memory ALloys

    SciTech Connect

    Wendy Crone; Walter Drugan; Arthur Ellis; John Perepezko

    2005-07-28

    With this grant we explored the properties that result from combining the effects of nanostructuring and shape memory using both experimental and theoretical approaches. We developed new methods to make nanostructured NiTi by melt-spinning and cold rolling fabrication strategies, which elicited significantly different behavior. A template synthesis method was also used to created nanoparticles. In order to characterize the particles we created, we developed a new magnetically-assisted particle manipulation technique to manipulate and position nanoscale samples for testing. Beyond characterization, this technique has broader implications for assembly of nanoscale devices and we demonstrated promising applications for optical switching through magnetically-controlled scattering and polarization capabilities. Nanoparticles of nickel-titanium (NiTi) shape memory alloy were also produced using thin film deposition technology and nanosphere lithography. Our work revealed the first direct evidence that the thermally-induced martensitic transformation of these films allows for partial indent recovery on the nanoscale. In addition to thoroughly characterizing and modeling the nanoindentation behavior in NiTi thin films, we demonstrated the feasibility of using nanoindentation on an SMA film for write-read-erase schemes for data storage.

  19. Titanium minerals for new materials

    NASA Astrophysics Data System (ADS)

    Kotova, O.; Ozhogina, E.; Ponaryadov, A.; Golubeva, I.

    2016-04-01

    The mineral composition of titanium minerals of modern coastal-marine placer in Stradbroke Island (Australia) and Pizhma paleoplacer in Middle Timan (Russia) has been presented. The physical features of titanium minerals and their modification methods were shown. Photocatalysts on the basis of the Pizhma leucoxene were developed for water purification.

  20. The application of an assisting gas plasma generator for low- temperature magnetron sputtering of Ti-C-Mo-S antifriction coatings on titanium alloys

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Savostikov, V. M.; Tabachenko, A. N.; Dudarev, E. F.; Melnikova, E. A.; Shulepov, I. A.

    2015-11-01

    The positive effect of assisting influence of high-density gas plasma formed by an independent plasma generator PINK on mechanical and tribological characteristics of Ti-C- Mo-S magnetron coating on titanium alloys at lowered to 350°C temperature of coating regardless of alloy structural condition was revealed by methods of calotest, nanorecognition, scratch testing and frictional material tests. The coating formed by means of a combined magnetron plasma method reduces titanium alloys friction coefficient in multiple times and increases wear resistance by two orders of magnitude. At the same time the mechanical properties of ultra-fine-grained titanium alloys obtained by nanostructuring do not deteriorate.

  1. Nanostructures having high performance thermoelectric properties

    DOEpatents

    Yang, Peidong; Majumdar, Arunava; Hochbaum, Allon I.; Chen, Renkun; Delgado, Raul Diaz

    2015-12-22

    The invention provides for a nanostructure, or an array of such nanostructures, each comprising a rough surface, and a doped or undoped semiconductor. The nanostructure is an one-dimensional (1-D) nanostructure, such a nanowire, or a two-dimensional (2-D) nanostructure. The nanostructure can be placed between two electrodes and used for thermoelectric power generation or thermoelectric cooling.

  2. Nanostructures having high performance thermoelectric properties

    DOEpatents

    Yang, Peidong; Majumdar, Arunava; Hochbaum, Allon I; Chen, Renkun; Delgado, Raul Diaz

    2014-05-20

    The invention provides for a nanostructure, or an array of such nanostructures, each comprising a rough surface, and a doped or undoped semiconductor. The nanostructure is an one-dimensional (1-D) nanostructure, such a nanowire, or a two-dimensional (2-D) nanostructure. The nanostructure can be placed between two electrodes and used for thermoelectric power generation or thermoelectric cooling.

  3. Milestones in Functional Titanium Dioxide Thermal Spray Coatings: A Review

    NASA Astrophysics Data System (ADS)

    Gardon, M.; Guilemany, J. M.

    2014-04-01

    Titanium dioxide has been the most investigated metal oxide due to its outstanding performance in a wide range of applications, chemical stability and low cost. Coating processes that can produce surfaces based on this material have been deeply studied. Nevertheless, the necessity of coating large areas by means of rapid manufacturing processes renders laboratory-scale techniques unsuitable, leading to a noteworthy interest from the thermal spray (TS) community in the development of significant intellectual property and a large number of scientific publications. This review unravels the relationship between titanium dioxide and TS technologies with the aim of providing detailed information related to the most significant achievements, lack of knowhow, and performance of TS TiO2 functional coatings in photocatalytic, biomedical, and other applications. The influence of thermally activated techniques such as atmospheric plasma spray and high-velocity oxygen fuel spray on TiO2 feedstock based on powders and suspensions is revised; the influence of spraying parameters on the microstructural and compositional changes and the final active behavior of the coating have been analyzed. Recent findings on titanium dioxide coatings deposited by cold gas spray and the capacity of this technology to prevent loss of the nanostructured anatase metastable phase are also reviewed.

  4. Synthesis and characterization of TiO2 nanostructure thin films grown by thermal CVD

    NASA Astrophysics Data System (ADS)

    Rizal, Umesh; Das, Soham; Kumar, Dhruva; Swain, Bhabani S.; Swain, Bibhu P.

    2016-04-01

    Thermal Chemical Vapor Deposition (CVD) deposited Titanium dioxide nanostructures (TiO2-NSs) were grown by using Ti powder and O2 precursors on Si/SiO2 (100) substrate. The microstructure and vibration properties of TiO2-NSs were characterized by Fourier transform infrared (FTIR), SEM, and photoluminescence (PL) spectroscopy. The role of O2 flow rate on TiO2-NSs revealed decreased deposition rate, however, surface roughness has been increased resulted into formation of nanostructure thin films.

  5. Fabrication of TiN nanostructure as a hydrogen peroxide sensor by oblique angle deposition

    PubMed Central

    2014-01-01

    Nanostructured titanium nitride (TiN) films with varying porosity were prepared by the oblique angle deposition technique (OAD). The porosity of films increases as the deposition angle becomes larger. The film obtained at an incident angle of 85° exhibits the best catalytic activity and sensitivity to hydrogen peroxide (H2O2). This could be attributed to its largest contact area with the electrolyte. An effective approach is thus proposed to fabricate TiN nanostructure as H2O2 sensor by OAD. PMID:24589278

  6. Optical properties of a binuclear neodymium complex in phosphorus oxychloride for liquid laser

    NASA Astrophysics Data System (ADS)

    Zhang, Guofang; She, Jiangbo; Han, Kai; Nie, Rongzhi; Li, Dongdong; Peng, Bo

    2015-11-01

    A novel binuclear neodymium complex Nd(CF3COO)3·(Ph3PO)2 (Ph3PO: triphenylphosphine oxide) with high stimulated emission cross-section was presented. The molecular structure of the complex was characterized by single-crystal X-ray diffraction. The optical properties of the complex in liquid medium were studied. From the absorption and luminescence spectra, the Judd-Ofelt parameters of Nd(CF3COO)3·(Ph3PO)2 in phosphorus oxychloride were obtained. Based on the crystal structure, the effects of crystal field and bonding valence properties on three intensity parameters Ωt(t = 2, 4, 6) and emission cross-section were analyzed in detail. The emission cross-section of 4F3/2 → 4I11/2 fluorescence transition (2.78 × 10-20 cm2) of the new neodymium compound was higher than those of other Nd(III) complexes and even comparable with some laser glasses.

  7. Neodymium doped hydroxyapatite theranostic nanoplatforms for colon specific drug delivery applications.

    PubMed

    Victor, Sunita Prem; Paul, Willi; Vineeth, V M; Komeri, Remya; Jayabalan, Muthu; Sharma, Chandra P

    2016-09-01

    Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410nm they exhibit near infrared emission at 670nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MTT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route. PMID:27281239

  8. Preparation of carbon nanotube-neodymium oxide composite and research on its catalytic performance

    SciTech Connect

    Zhao Lei; Wang Zhihua; Han Dongmei; Tao Dongliang; Guo Guangsheng

    2009-05-06

    Carbon Nanotube-Neodymium Oxide (CNT-Nd{sub 2}O{sub 3}) composite was prepared by using acid treated carbon nanotubes (CNTs) and neodymium nitrate in the presence of sodium dodecyl sulfate and ammonia liquid. Techniques of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) are used to characterize the morphology, structure, composition and catalytic property of the CNT-Nd{sub 2}O{sub 3} composite. The experimental results show that the Nd{sub 2}O{sub 3} nanoparticles, which have an average diameter of about 30-40 nm, are loaded on the surface of carbon nanotube. Compared with pure Nd{sub 2}O{sub 3} nanorods, the CNT-Nd{sub 2}O{sub 3} composite can catalyze the thermal decomposition of ammonium perchlorate more effectively. The sampling methods of the experimental samples made a difference on the catalytic experiment results, and the best catalytic result was obtained when de-ionized water served as the solvent of ammonium perchlorate.

  9. First clinical experience with a Q-switched neodymium:YAG laser for urinary calculi.

    PubMed

    Hofmann, R; Hartung, R; Schmidt-Kloiber, H; Reichel, E

    1989-02-01

    Animal studies using a high intensity nanosecond pulsed neodymium:YAG laser did not reveal any serious tissue damage. Following these investigations patient treatment was begun in June 1987. Laser energy of a neodymium:YAG laser with an 8 nsec. pulse duration and a repetition rate of up to 50 Hz. was coupled into a flexible 600 resp. 400 micron. quartz fiber. Laser-induced breakdown was created with 35 to 50 mJ. at the fiber tip, resulting in a shock wave that disintegrated the calculus into tiny fragments. A total of 56 patients with 58 calculi (54 ureteral and 4 kidney stones) was treated from June 1987 to March 1988. Of the calculi 48 could be fragmented completely, while 6 others were reduced to a size small enough to be removed with forceps. Four stones composed of calcium oxalate monohydrate could not be disintegrated. The combination of laser stone disintegration with flexible ureterorenoscopy implies the possibility of an atraumatic, 1-step procedure for fragmentation of ureteral and kidney calculi. PMID:2563297

  10. Investigation of Carboxylic Acid-Neodymium Conversion Films on Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Cui, Xiufang; Liu, Zhe; Lin, Lili; Jin, Guo; Wang, Haidou; Xu, Binshi

    2015-01-01

    The new carboxylic acid-neodymium anhydrous conversion films were successfully prepared and applied on the AZ91D magnesium alloy surface by taking absolute ethyl alcohol as solvent and four kinds of soluble carboxylic acid as activators. The corrosion resistance of the coating was measured by potentiodynamic polarization test in 3.5 wt.% NaCl solution in pH 7.0. The morphology, structure, and constituents of the coating were observed by scanning electron microscope, energy dispersivespectrum, x-ray photoelectron spectrum, and Fourier infrared spectrometer. Results show that corrosion resistance properties of samples coated with four different anhydrous conversion films were improved obviously. The corrosion potential increased, corrosion current density decreased, and polarization resistance increased. Among these four kinds of conversion films the one added with phytic exhibits the best corrosion resistant property. The mechanism of anhydrous-neodymium conversion film formation is also analyzed in this paper. It reveals that the gadolinium conversion coating is mainly composed of stable Nd2O3, MgO, Mg(OH)2, and carboxylate of Nd. And that the sample surface is rich in organic functional groups.

  11. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 μm, <75 μm, and < 45 μm; two different sizes of a hydride-dehydride [HDH] <75 μm and < 45 μm; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  12. Electrorotation of titanium microspheres.

    PubMed

    Arcenegui, Juan J; Ramos, Antonio; García-Sánchez, Pablo; Morgan, Hywel

    2013-04-01

    Electrorotation (ROT) data for solid titanium micrometer-sized spheres in an electrolyte are presented for three different ionic conductivities, over the frequency range of 10 Hz to 100 kHz. The direction of rotation was found to be opposite to the direction of rotation of the electric field vector (counterfield electrorotation), with a single rotation peak. The maximum rotation rate occurs at a frequency of the order of the reciprocal RC time constant for charging the particle double layer capacitance through the resistor of the electrolyte bulk. A model for the electrical torque acting on a metallic sphere is presented, using a constant phase element impedance to describe the metal/electrolyte interface. The titanium spheres are much denser than the electrolyte and rest on the bottom substrate. Therefore, the electrical and viscous torques near a wall are considered in the analysis. Good agreement is found between the predicted and measured rotational speed as a function of frequency. Theory shows that there is no effect of induced charge electroosmotic flow on the ROT, as observed experimentally. PMID:23348799

  13. Biocompatibility of Titanium

    NASA Astrophysics Data System (ADS)

    Namavar, Fereydoon; Sabirianov, Renat; Marton, Denes; Rubinstein, Alexander; Garvin, Kevin

    2012-02-01

    Titanium is the material of choice for orthopaedic applications because of its known biocompatibility. In order to enhance osteogenic properties of the Ti implants, it is necessary to understand the origin of its biocompatibility. We addresses the origin of Ti biocompatibility through (1) theoretical modeling, (2) the precise determination of Ti surface chemistry by X-ray photoelectron spectroscopy (XPS), (3) and the study of fibronectin adsorption as a function of Ti (near) surface chemistry by Enzyme-linked immunosorbent assay (ELISA). We compare the protein adsorption on Ti with the native oxide layer and the one coated by TiO2 in anatase phase using ion beam assisted deposition (IBAD). We show that the thin native sub-stoichiometric titanium oxide layer is crucial for biocompatibility of Ti surface. This is due to the enhancement of the non-specific adsorption of proteins which mediate cell adhesion. Improving the surface oxide quality, i.e. fabricating stoichiometric TiO2 (using IBAD) as well as nanoengineering the surface topology that matches its dimensions to that of adhesive proteins, is crucial for increased protein adsorption and, as a result, further increases biocompatibility of Ti implant materials.

  14. Titanium in 1980

    NASA Astrophysics Data System (ADS)

    Minkler, Ward W.

    1981-04-01

    Much attention is being focused on the availability and use of non-fuel minerals in the United States. Because of the rapid increase in demand since 1978, titanium has been one of the much-publicized metals in this group. Sponge producers are now expanding sponge manufacturing plants to meet this greater demand, and it now appears that there could be a surplus of sponge in 1981. A delay in airplane purchases caused by severe operating losses of the airlines could have a significant effect on mill product shipments in 1981. However, there is no reason to believe that titanium has reached maturity as a structural aerospace or industrial metal. While it is unreasonable to anticipate that demand will continue to grow at the same rate experienced between 1978 and 1980, new greenfield capacity will nevertheless be required in the early 1980s. Two basic issues must be resolved before such ventures become reality: 1) choice of process; and 2) method for financing, either public or private. Both will be the subject of study and debate in 1981.

  15. Nanostructures for enzyme stabilization

    SciTech Connect

    Kim, Jungbae; Grate, Jay W.; Wang, Ping

    2006-02-02

    The last decade has witnessed notable breakthroughs in nanotechnology with development of various nanostructured materials such as mesoporous materials and nanoparticles. These nanostructures have been used as a host for enzyme immobilization via various approaches, such as enzyme adsorption, covalent attachment, enzyme encapsulation, and sophisticated combinations of methods. This review discusses the stabilization mechanisms behind these diverse approaches; such as confinement, pore size and volume, charge interaction, hydrophobic interaction, and multipoint attachment. In addition, we will introduce recent rigorous approaches to improve the enzyme stability in these nanostructures or develop new nanostructures for the enzyme stabilization. Especially, we will introduce our recent invention of a nanostructure, called single enzyme nanoparticles (SENs). In the form of SENs, each enzyme molecule is surrounded with a nanometer scale network, resulting in stabilization of enzyme activity without any serious limitation for the substrate transfer from solution to the active site. SENs can be further immobilized into mesoporous silica with a large surface area, providing a hierarchical approach for stable, immobilized enzyme systems for various applications, such as bioconversion, bioremediation, and biosensors.

  16. Titanium-dioxide nanotube p-n homojunction diode

    SciTech Connect

    Alivov, Yahya E-mail: pnagpal@colorado.edu; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant E-mail: pnagpal@colorado.edu

    2014-12-29

    Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO{sub 2}) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO{sub 2} nanotubes p-n homojunction. This TiO{sub 2}:N/TiO{sub 2}:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of −5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

  17. Titanium-dioxide nanotube p-n homojunction diode

    NASA Astrophysics Data System (ADS)

    Alivov, Yahya; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant

    2014-12-01

    Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO2) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO2 nanotubes p-n homojunction. This TiO2:N/TiO2:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of -5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

  18. Nanostructured materials for hydrogen storage

    DOEpatents

    Williamson, Andrew J.; Reboredo, Fernando A.

    2007-12-04

    A system for hydrogen storage comprising a porous nano-structured material with hydrogen absorbed on the surfaces of the porous nano-structured material. The system of hydrogen storage comprises absorbing hydrogen on the surfaces of a porous nano-structured semiconductor material.

  19. Synthesis of porphyrin nanostructures

    DOEpatents

    Fan, Hongyou; Bai, Feng

    2014-10-28

    The present disclosure generally relates to self-assembly methods for generating porphyrin nanostructures. For example, in one embodiment a method is provided that includes preparing a porphyrin solution and a surfactant solution. The porphyrin solution is then mixed with the surfactant solution at a concentration sufficient for confinement of the porphyrin molecules by the surfactant molecules. In some embodiments, the concentration of the surfactant is at or above its critical micelle concentration (CMC), which allows the surfactant to template the growth of the nanostructure over time. The size and morphology of the nanostructures may be affected by the type of porphyrin molecules used, the type of surfactant used, the concentration of the porphyrin and surfactant the pH of the mixture of the solutions, and the order of adding the reagents to the mixture, to name a few variables.

  20. Nanostructured Biomaterials for Regeneration**

    PubMed Central

    Wei, Guobao; Ma, Peter X.

    2009-01-01

    Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/dysfunctional tissues or organs. Biomaterials (scaffolds) serve as temporary 3D substrates to guide neo tissue formation and organization. It is often beneficial for a scaffolding material to mimic the characteristics of extracellular matrix (ECM) at the nanometer scale and to induce certain natural developmental or/and wound healing processes for tissue regeneration applications. This article reviews the fabrication and modification technologies for nanofibrous, nanocomposite, and nanostructured drug-delivering scaffolds. ECM-mimicking nanostructured biomaterials have been shown to actively regulate cellular responses including attachment, proliferation, differentiation and matrix deposition. Nano-scaled drug delivery systems can be successfully incorporated into a porous 3D scaffold to enhance the tissue regeneration capacity. In conclusion, nano-structured biomateials are a very exciting and rapidly expanding research area, and are providing new enabling technologies for regenerative medicine. PMID:19946357

  1. Beta titanium alloys and their role in the titanium industry

    NASA Astrophysics Data System (ADS)

    Bania, Paul J.

    1994-07-01

    The class of titanium alloys generically referred to as the beta alloys is arguably the most versatile in the titanium family. Since these alloys offer the highest strength-to-weight ratios and deepest hardenability of all titanium alloys, one might expect them to compete favorably for a variety of aerospace applications. To the contrary, however, except for one very successful application (Ti-13V-11Cr-3Al on the SR-71), the beta alloys have remained a very small segment of the industry. As a perspective on this situation, this article reviews some past and present applications of titanium alloys. It also descibes some unique new alloys and applications that promise to reverse historical trends.

  2. Descaling and cleaning titanium and titanium alloy surfaces

    SciTech Connect

    Not Available

    1981-01-01

    The recommended practice covers a cleaning and descaling procedure useful to producers, users, and fabricators of titanium and titanium alloys for the removal of ordinary shop soils, oxides, and scales resulting from heat treatment operations and foreign substances present as surface contaminants. The procedures are not mandatory for removal of the indicated soils but rather serve as a guide when titanium and titanium alloys are being processed in the wrought, cast, or fabricated form. The soils should be removed prior to chemical milling, joining, plating, fabrication, and in any situation where foreign substances interfere with the corrosion resistance, stability, and quality of the finished product. The recommended practice discusses processing soil removal, blast cleaning, pickling, descaling, and inspection. (JMT)

  3. Simulation of Semiconductor Nanostructures

    SciTech Connect

    Williamson, A J; Grossman, J C; Puzder, A; Benedict, L X; Galli, G

    2001-07-19

    The field of research into the optical properties of silicon nanostructures has seen enormous growth over the last decade. The discovery that silicon nanoparticles exhibit visible photoluminescence (PL) has led to new insights into the mechanisms responsible for such phenomena. The importance of understanding and controlling the PL properties of any silicon based material is of paramount interest to the optoelectronics industry where silicon nanoclusters could be embedded into existing silicon based circuitry. In this talk, we present a combination of quantum Monte Carlo and density functional approaches to the calculation of the electronic, structural, and optical properties of silicon nanostructures.

  4. Plasmonic nanostructures: artificial molecules.

    PubMed

    Wang, Hui; Brandl, Daniel W; Nordlander, Peter; Halas, Naomi J

    2007-01-01

    This Account describes a new paradigm for the relationship between the geometry of metallic nanostructures and their optical properties. While the interaction of light with metallic nanoparticles is determined by their collective electronic or plasmon response, a compelling analogy exists between plasmon resonances of metallic nanoparticles and wave functions of simple atoms and molecules. Based on this insight, an entire family of plasmonic nanostructures, artificial molecules, has been developed whose optical properties can be understood within this picture: nanoparticles (nanoshells, nanoeggs, nanomatryushkas, nanorice), multi-nanoparticle assemblies (dimers, trimers, quadrumers), and a nanoparticle-over-metallic film, an electromagnetic analog of the spinless Anderson model. PMID:17226945

  5. Advanced titanium processing

    SciTech Connect

    Hartman, Alan D.; Gerdemann, Stephen J.; Schrems, Karol K.; Holcomb, Gordon R.; Argetsinger, Edward R.; Hansen, Jeffrey S.; Paige, Jack I.; Turner, Paul C.

    2001-01-01

    The Albany Research Center of the U.S. Department of Energy has been investigating a means to form useful wrought products by direct and continuous casting of titanium bars using cold-wall induction melting rather than current batch practices such as vacuum arc remelting. Continuous ingots produced by cold-wall induction melting, utilizing a bottomless water-cooled copper crucible, without slag (CaF2) additions had minor defects in the surface such as ''hot tears''. Slag additions as low as 0.5 weight percent were used to improve the surface finish. Therefore, a slag melted experimental Ti-6Al-4V alloy ingot was compared to a commercial Ti-6Al-4V alloy ingot in the areas of physical, chemical, mechanical, and corrosion attributes to address the question, ''Are any detrimental effects caused by slag addition''?

  6. Hydrogen in titanium alloys

    SciTech Connect

    Wille, G W; Davis, J W

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

  7. Photoacoustic spectroscopy study of neodymium complexes with alanine, valine, phenylalanine and tryptophan.

    PubMed

    Yang, Yuetao; Zhang, Shuyi

    2003-04-01

    Neodymium complexes with amino acids: Nd(Ala)(3)Cl(3).3H(2)O, Nd(Val)(3)Cl(3).3H(2)O, Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O (Ala: L-alanine, Val: L-valine, Phe: L-phenylalanine, Trp: L-tryptophan) are synthesized and their photoacoustic (PA) spectra are reported. The nephelauxetic ratio beta, bonding parameter b(1/2) and Sinha parameter delta are calculated based on their PA spectra. The variation of these parameters and correlation of them with the nature of metal-ligand bonding are discussed. The PA intensity analysis of the f-f transitions of neodymium ion is carried out by calculating the intensity branching vector. The environmental effect on the f-f transitions of neodymium ion is also studied. The branching vectors of the f-f transitions of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O are similar, which indicates the perturbation of the two ligand fields is similar. The branching vectors of energy levels 4G(5/2)+(2)G(7/2) of Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O increase remarkably compared with those of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O. As the degree of covalency increases, the oscillator strength of the hypersensitive transition exhibits a corresponding increase. The relaxation process of Nd(Ala)(3)Cl(3).3H(2)O is established through its PA and electron absorption spectroscopy (EAS). A method used to resolve the PA amplitude spectrum is suggested. With the phase spectrum, PA absorption bands of Nd(Trp)(3)Cl(3).3H(2)O are resolved well in the region of ligand absorption. PMID:12659889

  8. Brazing titanium to stainless steel

    NASA Technical Reports Server (NTRS)

    Batista, R. I.

    1980-01-01

    Titanium and stainless-steel members are usually joined mechanically for lack of any other effective method. New approach using different brazing alloy and plating steel member with nickel resolves problem. Process must be carried out in inert atmosphere.

  9. Ti implants with nanostructured and HA-coated surfaces for improved osseointegration.

    PubMed

    Sirin, Hasret Tolga; Vargel, Ibrahim; Kutsal, Tulin; Korkusuz, Petek; Piskin, Erhan

    2016-05-01

    This study was aimed at comparing the osseointegration of titanium (Ti)-based Küntscher nails (K-nails) and plates with modified nanostructured and hydroxyapatite-coated surfaces in a rat femur model. Material surfaces were first modified via a simple anodization protocol in which the materials were treated in hydrogen fluoride (1% w/w) at 20 V. This modification resulted in tubular titanium oxide nanostructures of 40-65 nm in diameter. Then, hydroxyapatite-deposited layers, formed of particles (1-5) μm, were produced via incubation in a simulated body fluid, followed by annealing at 500°C. Both surface modifications significantly improved cell proliferation and alkaline phosphatase (ALP) activity as compared to the control (non-modified Ti implants). The controls and modified nails and plates were implanted in the femur of 21 male Sprague-Dawley rats. The implants, with surrounding tissues, were removed after 10 weeks, and then mechanical tests (torque and pull-out) were performed, which showed that the modified K-nails exhibited significantly better osseointegration than the controls. Histologic examinations of the explants containing plates showed similar results, and the modified plates exhibited significantly better osseointegration than the controls. Surface nanostructuring of commercially available titanium-based implants by a very simple method - anodization - seems to be a viable method for increasing osseointegration without the use of bioactive surface coatings such as hydroxyapatite. PMID:26496822

  10. Photocatalytic Activity of Nanostructured Anatase Coatings Obtained by Cold Gas Spray

    NASA Astrophysics Data System (ADS)

    Gardon, M.; Fernández-Rodríguez, C.; Garzón Sousa, D.; Doña-Rodríguez, J. M.; Dosta, S.; Cano, I. G.; Guilemany, J. M.

    2014-10-01

    This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS) supported on titanium sub-oxide (TiO2- x ) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO2 particles fragmented when impacting onto the hard surface of the APS TiO2- x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO2 coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25® photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide.

  11. Titanium/gold process characterization

    SciTech Connect

    Fajardo, L.S.

    1991-11-01

    Characterization of the titanium/gold (Ti/Au) deposition process used at the Allied-Signal Inc., Albuquerque Microelectronics Operation (AMO) was performed. Tests were conducted to set up evaporation parameters, correlate titanium and gold thicknesses to sheet resistance, improve thickness uniformity, and reduce frontside contamination of deposit material on product wafers. The Ti/Au process is the final step in the production of integrated circuits (ICs) at the AMO wafer fabrication facility. 3 figs.

  12. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2015-09-29

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  13. Atomically Traceable Nanostructure Fabrication.

    PubMed

    Ballard, Josh B; Dick, Don D; McDonnell, Stephen J; Bischof, Maia; Fu, Joseph; Owen, James H G; Owen, William R; Alexander, Justin D; Jaeger, David L; Namboodiri, Pradeep; Fuchs, Ehud; Chabal, Yves J; Wallace, Robert M; Reidy, Richard; Silver, Richard M; Randall, John N; Von Ehr, James

    2015-01-01

    Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure. PMID:26274555

  14. Nanostructured catalyst supports

    DOEpatents

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2012-10-02

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  15. Emerging double helical nanostructures

    NASA Astrophysics Data System (ADS)

    Zhao, Meng-Qiang; Zhang, Qiang; Tian, Gui-Li; Wei, Fei

    2014-07-01

    As one of the most important and land-mark structures found in nature, a double helix consists of two congruent single helices with the same axis or a translation along the axis. This double helical structure renders the deoxyribonucleic acid (DNA) the crucial biomolecule in evolution and metabolism. DNA-like double helical nanostructures are probably the most fantastic yet ubiquitous geometry at the nanoscale level, which are expected to exhibit exceptional and even rather different properties due to the unique organization of the two single helices and their synergistic effect. The organization of nanomaterials into double helical structures is an emerging hot topic for nanomaterials science due to their promising exceptional unique properties and applications. This review focuses on the state-of-the-art research progress for the fabrication of double-helical nanostructures based on `bottom-up' and `top-down' strategies. The relevant nanoscale, mesoscale, and macroscopic scale fabrication methods, as well as the properties of the double helical nanostructures are included. Critical perspectives are devoted to the synthesis principles and potential applications in this emerging research area. A multidisciplinary approach from the scope of nanoscience, physics, chemistry, materials, engineering, and other application areas is still required to the well-controlled and large-scale synthesis, mechanism, property, and application exploration of double helical nanostructures.

  16. Continuous production of titanium powder

    SciTech Connect

    Gerdemann, Stephen J.; Oden, Laurence L.; White, Jack C.

    1997-01-01

    Although incremental improvements have been made to the Kroll process since its inception in 1948, the process in use today remains essentially the same batch process developed by Dr. Kroll and perfected by the U.S. Bureau of Mines. In this process, titanium tetrachloride (TiCl4) is reduced by magnesium to produce titanium metal. There are two major limitations to the Kroll process: (1) it is a batch process; and (2) the reduction of TiCl4 proceeds so rapidly that the sponge formed is an interlocking dendritic mass with inclusions of magnesium, magnesium salts and titanium subchloride that must undergo several purification steps before the metal is suitable for use. The Albany Research Center (ARC), formerly the U.S. Bureau of Mines, has investigated a new, continuous titanium metal production process in which a titanium powder is produced in a bath of molten salt. In this process, the rate of the reduction reaction was slowed and controlled by diluting the reactants with molten chloride salts. The diluted reactant streams were combined in a continuous stirred tank reactor, operated much like a crystallizer. New titanium metal forms on the already present small Ti particles. When the Ti particles become too large to remain suspended in solution, they fall to the bottom of the reactor and are removed. Initial experiments show promise but problems remain in obtaining the required purity and uniform particle size.

  17. Low cost titanium--myth or reality

    SciTech Connect

    Turner, Paul C.; Hartman, Alan D.; Hansen, Jeffrey S.; Gerdemann, Stephen J.

    2001-01-01

    In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium, and titanium cost has prevented its use in non-aerospace applications including the automotive and heavy vehicle industries.

  18. Extraction chromatography of neodymium by an organophosphorous extractant supported on various polymeric resins

    SciTech Connect

    Takigawa, D.Y.

    1993-04-01

    Fifteen resins coated with dihexyl-N,N-diethylcarbamoylmethyl phosphonate (CMP) were studied for their extraction of neodymium (Nd) in 4.0 and 7.0 M nitric acid. Resin properties, such as chemical composition and physical morphology, which can influence Nd extraction as well as subsequent resin regeneration (Nd stripping), were identified. Hydrophilic or polar resins coated with CMP efficiently extracted the Nd. Resins initially washed free of residual monomer and solvent before CMP coating outperformed their untreated counterparts. The macroporous styrene-divinylbenzene hydrophobic resins that were high in surface area were less effective supports compared with hydrophilic microporous Aurorez, polybenzimidazole (PBI) and macroporous Amberlite polyacrylic resins. Only one resin, Duolite C-467, showed no measurable improvement in Nd extraction with CMP coating. CMP-coated Aurorez PBI, a microporous and hydrophilic polymeric resin with an average surface area, showed the best overall efficiency for Nd removal and resin regeneration.

  19. Detection of Neodymium in APOGEE H-band Spectra and its Application to Chemical Tagging

    NASA Astrophysics Data System (ADS)

    Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.; Holtzman, Jon A.; Lawler, James E.; Ivans, Inese I.; Majewski, Steven R.; Schiavon, Ricardo P.; Zasowski, Gail; Nidever, David L.; Hearty, Fred; Allende-Prieto, Carlos; Beers, Timothy C.; García Pérez, Ana; Sobeck, Jennifer; Apogee Team

    2015-01-01

    We report the successful detection of the rare earth element Neodymium (Nd) in the high-resolution, H-band spectra from the SDSS III Apache Point Observatory Galactic Evolution Experiment (APOGEE). Using the Nd II transition at 16058.014 angstroms, we have detected significant Nd enhancements in all stars observed by APOGEE belonging to the Sagittarius (Sgr) Dwarf Spheroidal (dSph) galaxy. Because Sgr is known to be enhanced in heavy s-process elements such as Nd, we can use this feature to identify and chemically tag Sgr stream members that have been observed in the Galactic halo by APOGEE. We also use this feature to characterize rare earth element abundance variations in clusters observed by APOGEE.

  20. Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

    PubMed Central

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region. PMID:25302320

  1. Current status and future outlook for bonded neodymium permanent magnets (invited)

    NASA Astrophysics Data System (ADS)

    Croat, J. J.

    1997-04-01

    Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed.

  2. Spectroscopic Properties of Neodymium-Doped Yttrium Orthovanadate Single Crystals with High-Resolution Measurement

    NASA Astrophysics Data System (ADS)

    Sato, Yoichi; Taira, Takunori

    2002-10-01

    The absorption and fluorescence spectra of the neodymium-doped yttrium orthovanadate (Nd:YVO4) single crystal were investigated carefully. For the 808.8-nm absorption cross section, the published values varied between 18.4 and 25.6 × 10-20 cm2 for π-polarization. The authors evaluated this spectroscopic parameter with high resolution at 0.5 nm, and discovered 48.4 cm-1 at 808.8 nm even for the absorption of 1 at.% Nd3+-ion-doped YVO4 single crystal. This value is 1.3 times larger than the well-known value, and confirms that Nd:YVO4 is very suitable for microchip lasers, and that certain laser characteristics of Nd:YVO4 of previous works should be re-evaluated.

  3. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-01

    Gallium oxide and more particularly β-Ga2O3 matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  4. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    SciTech Connect

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-15

    Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  5. Omega phase formation in titanium and titanium alloys

    SciTech Connect

    Gray, G.T. III; Morris, C.E.; Lawson, A.C.

    1992-05-01

    Although the response of titanium alloys to dynamic loading is receiving increased attention in the literature (particularly in the area of shear-band formation), a more limited experimental database exists concerning the detailed structure/property relationships of titanium alloys subjected to shock loading. In this study, preliminary results concerning the influence of alloy chemistry on the property of omega-phase formation and its structure in three titanium alloys are presented. The influence of shock-wave deformation on the phase stability and substructure evolution of high-purity (low-interstitial) titanium, A-70 (3700 ppm oxygen) titanium, and Ti-6Al-4V were probed utilizing real-time velocity interferometry (VISAR) and ``soft`` shock-recovery techniques. VISAR wave profiles of shock-loaded high-purity titanium revealed the omega-phase pressure-induced transition to occur at approximately 10.4 GPa. Wave profile measurements on A-70 Ti shocked to pressures up to 35 GPa and Ti-6Al-4V shocked to pressures up to 25 GPa exhibited no evidence of a three-wave structure indicative of a pressure-induced phase transition. Neutron and X-ray diffractometry and TEM analysis confirmed the presence of retained {omega}-phase in the electrolytic-Ti and the absence of {omega}-phase in the shock-recovered A-70 Ti and Ti-6Al-4V. Suppression of the {alpha}-{omega} phase transition in A-70 Ti, containing a high interstitial oxygen content, is seen to simultaneously correlate with suppression of deformation twinning. Neutron diffraction was used to measure the in-situ bulk lattice constants and volume fraction of the {alpha} and {omega} phases in the recovered high-purity titanium samples that were shock loaded. The influence of alloy content on the kinetics of formation/retention of {omega}-phase and substructure evolution is discussed and contrasted in light of previous literature studies.

  6. Self assembled DC sputtered nanostructured rutile TiO₂ platform for bisphenol A detection.

    PubMed

    Singh, Nawab; Reza, K Kamil; Ali, Md Azahar; Agrawal, Ved Varun; Biradar, A M

    2015-06-15

    A novel biosensor platform comprising of the functionalized sputtered rutile nanostructured titanium dioxide (nTiO2) for rapid detection of estrogenic substance (bisphenol A) has been proposed. The direct current (DC) sputtering of titanium (Ti) on glass substrate has been converted to ordered nanostructured TiO2 film via oxidation. The nanostructured TiO2 surface was functionalized with self-assembled monolayer (SAM) of 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde. The enzyme molecule, tyrosinase (Tyrs) has been covalently immobilized on the surface of APTES modified nanostructured TiO2 film. To investigate the crystalline structure and surface morphology of functionalized nTiO2/Ti electrode, the X-ray diffraction, scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy have been carried out. This impedimetric biosensor exhibits a comparable sensitivity (361.9 kΩ/µM) in a wide range of detection (0.01-1.0 µM) and a response time of 250 s for bisphenol A (BPA) monitoring. This novel manufacturing process for nTiO2 film is cheap, practical and safer for functionalization with SAM and glutaraldehyde to improve the biosensor efficacy. The strong protein absorption capability of the nTiO2 surface demonstrates an excellent electrochemical biosensor and could be useful for the detection of other phenolic compounds. PMID:25656780

  7. Cell response of anodized nanotubes on titanium and titanium alloys.

    PubMed

    Minagar, Sepideh; Wang, James; Berndt, Christopher C; Ivanova, Elena P; Wen, Cuie

    2013-09-01

    Titanium and titanium alloy implants that have been demonstrated to be more biocompatible than other metallic implant materials, such as Co-Cr alloys and stainless steels, must also be accepted by bone cells, bonding with and growing on them to prevent loosening. Highly ordered nanoporous arrays of titanium dioxide that form on titanium surface by anodic oxidation are receiving increasing research interest due to their effectiveness in promoting osseointegration. The response of bone cells to implant materials depends on the topography, physicochemistry, mechanics, and electronics of the implant surface and this influences cell behavior, such as adhesion, proliferation, shape, migration, survival, and differentiation; for example the existing anions on the surface of a titanium implant make it negative and this affects the interaction with negative fibronectin (FN). Although optimal nanosize of reproducible titania nanotubes has not been reported due to different protocols used in studies, cell response was more sensitive to titania nanotubes with nanometer diameter and interspace. By annealing, amorphous TiO2 nanotubes change to a crystalline form and become more hydrophilic, resulting in an encouraging effect on cell behavior. The crystalline size and thickness of the bone-like apatite that forms on the titania nanotubes after implantation are also affected by the diameter and shape. This review describes how changes in nanotube morphologies, such as the tube diameter, the thickness of the nanotube layer, and the crystalline structure, influence the response of cells. PMID:23436766

  8. Antibacterial Au nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It

  9. Manganese Nanostructures and Magnetism

    NASA Astrophysics Data System (ADS)

    Simov, Kirie Rangelov

    The primary goal of this study is to incorporate adatoms with large magnetic moment, such as Mn, into two technologically significant group IV semiconductor (SC) matrices, e.g. Si and Ge. For the first time in the world, we experimentally demonstrate Mn doping by embedding nanostructured thin layers, i.e. delta-doping. The growth is observed by in-situ scanning tunneling microscopy (STM), which combines topographic and electronic information in a single image. We investigate the initial stages of Mn monolayer growth on a Si(100)(2x1) surface reconstruction, develop methods for classification of nanostructure types for a range of surface defect concentrations (1.0 to 18.2%), and subsequently encapsulate the thin Mn layer in a SC matrix. These experiments are instrumental in generating a surface processing diagram for self-assembly of monoatomic Mn-wires. The role of surface vacancies has also been studied by kinetic Monte Carlo modeling and the experimental observations are compared with the simulation results, leading to the conclusion that Si(100)(2x1) vacancies serve as nucleation centers in the Mn-Si system. Oxide formation, which happens readily in air, is detrimental to ferromagnetism and lessens the magnetic properties of the nanostructures. Therefore, the protective SC cap, composed of either Si or Ge, serves a dual purpose: it is both the embedding matrix for the Mn nanostructured thin film and a protective agent for oxidation. STM observations of partially deposited caps ensure that the nanostructures remain intact during growth. Lastly, the relationship between magnetism and nanostructure types is established by an in-depth study using x-ray magnetic circular dichroism (XMCD). This sensitive method detects signals even at coverages less than one atomic layer of Mn. XMCD is capable of discerning which chemical compounds contribute to the magnetic moment of the system, and provides a ratio between the orbital and spin contributions. Depending on the amount

  10. Titanium-based silicide quantum dot superlattices for thermoelectrics applications.

    PubMed

    Savelli, Guillaume; Stein, Sergio Silveira; Bernard-Granger, Guillaume; Faucherand, Pascal; Montès, Laurent; Dilhaire, Stefan; Pernot, Gilles

    2015-07-10

    Ti-based silicide quantum dot superlattices (QDSLs) are grown by reduced-pressure chemical vapor deposition. They are made of titanium-based silicide nanodots scattered in an n-doped SiGe matrix. This is the first time that such nanostructured materials have been grown in both monocrystalline and polycrystalline QDSLs. We studied their crystallographic structures and chemical properties, as well as the size and the density of the quantum dots. The thermoelectric properties of the QDSLs are measured and compared to equivalent SiGe thin films to evaluate the influence of the nanodots. Our studies revealed an increase in their thermoelectric properties-specifically, up to a trifold increase in the power factor, with a decrease in the thermal conductivity-making them very good candidates for further thermoelectric applications in cooling or energy-harvesting fields. PMID:26086207

  11. Plasma quench production of titanium from titanium tetrachloride

    SciTech Connect

    Sears, J.W.

    1994-10-01

    This project, Plasma Quench Production of Titanium from Titanium Tetrachloride, centers on developing a technique for rapidly quenching the high temperature metal species and preventing back reactions with the halide. The quenching technique chosen uses the temperature drop produced in a converging/diverging supersonic nozzle. The rapid quench provided by this nozzle prevents the back reaction of the halide and metal. The nature of the process produces nanosized particles (10 to 100 nm). The powders are collected by cyclone separators, the hydrogen flared, and the acid scrubbed. Aluminum and titanium powders have been produced in the laboratory-scale device at 1 gram per hour. Efforts to date to scale up this process have not been successful.

  12. Planar plasmonic chiral nanostructures.

    PubMed

    Zu, Shuai; Bao, Yanjun; Fang, Zheyu

    2016-02-21

    A strong chiral optical response induced at a plasmonic Fano resonance in a planar Au heptamer nanostructure was experimentally and theoretically demonstrated. The scattering spectra show the characteristic narrow-band feature of Fano resonances for both left and right circular polarized lights, with a chiral response reaching 30% at the Fano resonance. Specifically, we systematically investigate the chiral response of planar heptamers with gradually changing the inter-particle rotation angles and separation distance. The chiral spectral characteristics clearly depend on the strength of Fano resonances and the associated near-field optical distributions. Finite element method simulations together with a multipole expansion method demonstrate that the enhanced chirality is caused by the excitation of magnetic quadrupolar and electric toroidal dipolar modes. Our work provides an effective method for the design of 2D nanostructures with a strong chiral response. PMID:26818746

  13. Nanostructured sulfur cathodes.

    PubMed

    Yang, Yuan; Zheng, Guangyuan; Cui, Yi

    2013-04-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. PMID:23325336

  14. Nanostructured Superhydrophobic Coatings

    SciTech Connect

    2009-03-01

    This factsheet describes a research project that deals with the nanostructured superhydrophobic (SH) powders developed at ORNL. This project seeks to (1) improve powder quality; (2) identify binders for plastics, fiberglass, metal (steel being the first priority), wood, and other products such as rubber and shingles; (3) test the coated product for coating quality and durability under operating conditions; and (4) application testing and production of powders in quantity.

  15. Pickled luminescent silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Boukherroub, R.; Morin, S.; Wayner, D. D. M.; Lockwood, D. J.

    2001-05-01

    In freshly prepared porous Si, the newly exposed silicon-nanostructure surface is protected with a monolayer of hydrogen, which is very reactive and oxidizes in air leading to a loss of luminescence intensity and a degradation of the electronic properties. We report a surface passivation approach based on organic modification that stabilizes the luminescence. This novel 'pickling' process not only augments the desired optoelectronic properties, but also is adaptable to further chemical modification for integration into chemical and biophysical sensors.

  16. TiO{sub 2} nanotube, nanowire, and rhomboid-shaped particle thin films fixed on a titanium metal plate

    SciTech Connect

    Inoue, Yuko; Noda, Iwao; Torikai, Toshio; Watari, Takanori; Hotokebuchi, Takao; Yada, Mitsunori

    2010-01-15

    Titanium dioxide thin films having various nanostructures could be formed by various treatments on sodium titanate nanotube thin films approximately 5 {mu}m thick fixed on titanium metal plates. Using an aqueous solution with a lower hydrochloric acid concentration (0.01 mol/L) and a higher reaction temperature (90 deg. C) than those previously employed, we obtained a hydrogen titanate nanotube thin film fixed onto a titanium metal plate by H{sup +} ion-exchange treatment of the sodium titanate nanotube thin film. Calcination of hydrogen titanate nanotube thin films yielded porous thin films consisting of anatase nanotubes, anatase nanowires, and anatase nanoparticles grown directly from the titanium metal plate. H{sup +} ion-exchange treatment of sodium titanate nanotube thin films at 140 deg. C resulted in porous thin films consisting of rhomboid-shaped anatase nanoparticles. - Graphical abstract: Titanium dioxide nanotube, nanowire, and rhombic particle thin films could be formed by various treatments on a sodium titanate nanotube thin film fixed on a titanium metal plate.

  17. Titanium pigmentation. An electron probe microanalysis study

    SciTech Connect

    Dupre, A.; Touron, P.; Daste, J.; Lassere, J.; Bonafe, J.L.; Viraben, R.

    1985-05-01

    A patient had an unusual pigmentary disease induced by titanium dioxide. The use of a topical cream containing titanium dioxide caused a xanthomalike appearance on the patient's penis. Electron probe microanalysis was valuable in establishing the cause of this balanitis.

  18. Method for Surface Texturing Titanium Products

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor)

    1998-01-01

    The present invention teaches a method of producing a textured surface upon an arbitrarily configured titanium or titanium alloy object for the purpose of improving bonding between the object and other materials such as polymer matrix composites and/or human bone for the direct in-growth of orthopaedic implants. The titanium or titanium alloy object is placed in an electrolytic cell having an ultrasonically agitated solution of sodium chloride therein whereby a pattern of uniform "pock mark" like pores or cavities are produced upon the object's surface. The process is very cost effective compared to other methods of producing rough surfaces on titanium and titanium alloy components. The surface textures produced by the present invention are etched directly into the parent metal at discrete sites separated by areas unaffected by the etching process. Bonding materials to such surface textures on titanium or titanium alloy can thus support a shear load even if adhesion of the bonding material is poor.

  19. Antibacterial Au nanostructured surfaces.

    PubMed

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-02-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies. PMID:26648134

  20. Compact, efficient, scalable neodymium laser co-doped with activator ions and pumped by visible laser diodes

    NASA Astrophysics Data System (ADS)

    Scheps, Richard

    1994-02-01

    Efficient, low threshold laser emission from a laser crystal doped with chromium and neodymium ions is obtained when pumped by visible laser diodes in the range of 610 nm to 680 nm. A typical laser Cr,Nd:GSGG crystal having an extraordinarily broad absorption bandwidth allows high pump efficiencies when using visible laser diodes, particularly in comparison to the Nd:YAG laser. The broad absorption bandwidth tolerance of the Cr,Nd:GSGG crystal to the pumping wavelengths allows visible diode pumping of the neodymium transition without regard to the wavelength of the visible diodes. Longitudinal or end-pumping to take advantage of the emission properties of the visible laser diodes, a nearly hemispherical laser resonator configuration and other co-doped Cr,Nd laser host materials are disclosed.

  1. Coherent control near metallic nanostructures

    SciTech Connect

    Efimov, Ilya; Efimov, Anatoly

    2008-01-01

    We study coherent control in the vicinity of metallic nanostructures. Unlike in the case of control in gas or liquid phase, the collective response of electrons in a metallic nanostructure can significantly enhance different frequency components of the control field. This enhancement strongly depends on the geometry of the nanostructure and can substantially modify the temporal profile of the local control field. The changes in the amplitude and phase of the control field near the nanostructure are studied using linear response theory. The inverse problem of finding the external electromagnetic field to generate the desired local control field is considered and solved.

  2. Low Temperature Growth of Nanostructured Diamond Films on Metals

    NASA Technical Reports Server (NTRS)

    Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

    2001-01-01

    The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments

  3. Lightweight Protective Coatings For Titanium Alloys

    NASA Technical Reports Server (NTRS)

    Wiedemann, Karl E.; Taylor, Patrick J.; Clark, Ronald K.

    1992-01-01

    Lightweight coating developed to protect titanium and titanium aluminide alloys and titanium-matrix composite materials from attack by environment when used at high temperatures. Applied by sol-gel methods, and thickness less than 5 micrometers. Reaction-barrier and self-healing diffusion-barrier layers combine to protect titanium alloy against chemical attack by oxygen and nitrogen at high temperatures with very promising results. Can be extended to protection of other environmentally sensitive materials.

  4. Process for reproducibly preparing titanium subhydride

    SciTech Connect

    Carlson, R.S.

    1982-01-05

    Titanium subhydride is produced in a reactor by heating a selected amount of finely divided titanium compound at a selected temperature for a selected period of time under dynamic vacuum conditions. Hydrogen is removed substantially uniformly from each powder grain and there is produced a subhydride of substantially uniform titanium-hydrogen composition. Selection of the amount, temperature and time produces a subhydride of selected titanium hydrogen composition.

  5. Process for reproducibly preparing titanium subhydride

    DOEpatents

    Carlson, Richard S.

    1982-01-01

    Titanium subhydride is produced in a reactor by heating a selected amount of finely divided titanium compound at a selected temperature for a selected period of time under dynamic vacuum conditions. Hydrogen is removed substantially uniformly from each powder grain and there is produced a subhydride of substantially uniform titanium-hydrogen composition. Selection of the amount, temperature and time produces a subhydride of selected titanium-hydrogen composition.

  6. Variations in the neodymium and strontium isotopic composition and REE content of molluscan shells from the Cretaceous Western Interior seaway

    SciTech Connect

    Whittaker, S.G.; Kyser, T.K. )

    1993-08-01

    Rare earth element concentrations, [epsilon][sub ND](T) values, and strontium isotopic compositions of mollusc shells were used to trace variations in the neodymium and strontium isotopic composition of the epicontinental Late Cretaceous Western Interior seaway of North America. Rare earth element patterns are different in aragonite and calcite produced by the molluscs endemic to the seaway, indicating that either mineralogical control or possibly scavenging by organic films associated with the different phases of biogenic carbonate resulted in differential partitioning of the REEs from seawater during shell formation. The biogenic carbonate also may contain REEs associated with Fe-flocs trapped in the shells during growth, but these flocs cannot result in different REE patterns of aragonite and calcite produced by the molluscs. The neodymium isotopic composition of the Western Interior seaway is inferred to have varied 13 [epsilon]-units over 20 My as a result of incursions of seawater from the Arctic Ocean and Gulf of Mexico, river influx from tectonically active terranes, benthic diagenetic fluxes, and volcanic ash falls. Ash from a variety of volcanic centers in western North America was significant in producing rapid and marked changes in [sup 143]Nd/[sup 144]Nd ratios of the seaway, and abrupt regional variations in neodymium isotopic composition of the seaway make the construction of an accurate neodymium isotope evolution curve difficult for this basin. Strontium isotopic compositions of the mollusc shells indicate the [sup 87]Sr/[sup 86]Sr ratio of the Western Interior seaway was generally similar to contemporaneous oceans, although, periodically, the basin had strontium isotopic compositions distinct from contemporaneous seawater. 58 refs., 7 figs., 3 tabs.

  7. Neodymium glass laser with a pulse energy of 220 J and a pulse repetition rate of 0.02 Hz

    SciTech Connect

    Kuzmin, A A; Kulagin, O V; Khazanov, Efim A; Shaykin, A A

    2013-07-31

    A compact neodymium glass laser with a pulse energy of 220 J and a record-high pulse repetition rate of 0.02 Hz (pulse duration 30 ns) is developed. Thermally induced phase distortions are compensated using wave phase conjugation. The integral depolarisation of radiation is decreased to 0.4% by using linear compensation schemes. The second harmonic of laser radiation can be used for pumping Ti : sapphire multipetawatt complexes. (letters)

  8. Mechanical properties of titanium connectors.

    PubMed

    Neo, T K; Chai, J; Gilbert, J L; Wozniak, W T; Engelman, M J

    1996-01-01

    The tensile mechanical properties of welded titanium joints were studied, and intact titanium was used as controls. Welded joints were fabricated with either a stereographic laser-welding technique or a gas tungsten arc welding technique. The effect of heat treatment following a simulated porcelain application was also investigated. Heat-treated laser welds had significantly lower ultimate tensile strengths. Heat treatment had no effect on the modulus of elasticity or elongation, but generally significantly decreased the yield strength of the titanium specimens. The gas tungsten are welding specimens had significantly higher yield strengths and elastic moduli than the other two groups. The elongation of the control specimens was significantly greater than the elongation of the gas tungsten arc welding specimens, which was in turn significantly higher than that of the laser-welded specimens. PMID:8957877

  9. Photonuclear reactions on titanium isotopes

    SciTech Connect

    Belyshev, S. S.; Dzhilavyan, L. Z.; Ishkhanov, B. S.; Kapitonov, I. M.; Kuznetsov, A. A. Orlin, V. N.; Stopani, K. A.

    2015-03-15

    The photodisintegration of titanium isotopes in the giant-dipole-resonance energy region is studied by the photon-activation method. Bremsstrahlung photons whose spectrum has the endpoint energy of 55 MeV is used. The yields and integrated cross sections are determined for photoproton reactions on the titanium isotopes {sup 47,48,49,50}Ti. The respective experimental results are compared with their counterparts calculated on the basis of the TALYS code and a combined photonucleon-reaction model. The TALYS code disregards the isospin structure of the giant dipole resonance and is therefore unable to describe the yield of photoproton reactions on the heavy titanium isotopes {sup 49,50}Ti.

  10. Adaptive mesh refinement in titanium

    SciTech Connect

    Colella, Phillip; Wen, Tong

    2005-01-21

    In this paper, we evaluate Titanium's usability as a high-level parallel programming language through a case study, where we implement a subset of Chombo's functionality in Titanium. Chombo is a software package applying the Adaptive Mesh Refinement methodology to numerical Partial Differential Equations at the production level. In Chombo, the library approach is used to parallel programming (C++ and Fortran, with MPI), whereas Titanium is a Java dialect designed for high-performance scientific computing. The performance of our implementation is studied and compared with that of Chombo in solving Poisson's equation based on two grid configurations from a real application. Also provided are the counts of lines of code from both sides.

  11. 21 CFR 73.2575 - Titanium dioxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the...

  12. 21 CFR 73.3126 - Titanium dioxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891,...

  13. 40 CFR 180.1195 - Titanium dioxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide (CAS Reg. No. 13463-67-7) is exempted from the requirement of...

  14. 21 CFR 73.3126 - Titanium dioxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891,...

  15. 21 CFR 73.3126 - Titanium dioxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891,...

  16. 21 CFR 73.2575 - Titanium dioxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the...

  17. 21 CFR 73.3126 - Titanium dioxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891,...

  18. 21 CFR 73.2575 - Titanium dioxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the...

  19. 21 CFR 73.1575 - Titanium dioxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the...

  20. 21 CFR 73.1575 - Titanium dioxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the...

  1. 21 CFR 73.1575 - Titanium dioxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the...

  2. 21 CFR 73.1575 - Titanium dioxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the...

  3. 40 CFR 180.1195 - Titanium dioxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide (CAS Reg. No. 13463-67-7) is exempted from the requirement of...

  4. 40 CFR 180.1195 - Titanium dioxide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or...

  5. 21 CFR 73.2575 - Titanium dioxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the...

  6. 40 CFR 180.1195 - Titanium dioxide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or...

  7. 40 CFR 180.1195 - Titanium dioxide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or...

  8. 21 CFR 73.3126 - Titanium dioxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.3126 Section 73.3126 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3126 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide (CAS Reg. No. 13463-67-7), Color Index No. 77891,...

  9. 21 CFR 73.1575 - Titanium dioxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Titanium dioxide. 73.1575 Section 73.1575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1575 Titanium dioxide. (a) Identity and specifications. (1) The color additive titanium dioxide shall conform in identity and specifications to the...

  10. 21 CFR 73.2575 - Titanium dioxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the...

  11. Evaluating United States and world consumption of neodymium, dysprosium, terbium, and praseodymium in final products

    NASA Astrophysics Data System (ADS)

    Hart, Matthew

    This paper develops scenarios of future rare-earth-magnet metal (neodymium, dysprosium, terbium, and praseodymium) consumption in the permanent magnets used in wind turbines and hybrid electric vehicles. The scenarios start with naive base-case scenarios for growth in wind-turbine and hybrid-electric-vehicle sales over the period 2011 to 2020, using historical data for each good. These naive scenarios assume that future growth follows time trends in historical data and does not depend on any exogenous variable. Specifically, growth of each technological market follows historical time trends, and the amount of rare earths used per unit of technology remains fixed. The chosen reference year is 2010. Implied consumptions of the rare earth magnet metals are calculated from these scenarios. Assumptions are made for the material composition of permanent magnets, the market share of permanent-magnet wind turbines and vehicles, and magnet weight per unit of technology. Different scenarios estimate how changes in factors like the material composition of magnets, growth of the economy, and the price of a substitute could affect future consumption. Each scenario presents a different method for reducing rare earth consumption and could be interpreted as potential policy choices. In 2010, the consumption (metric tons, rare-earth-oxide equivalent) of each rare-earth-magnet metal was as follows. Total neodymium consumption in the world for both technologies was 995 tons; dysprosium consumption was 133 tons; terbium consumption was 50 tons; praseodymium consumption was zero tons. The base scenario for wind turbines shows there could be strong, exponential growth in the global wind turbine market. New U.S. sales of hybrid vehicles would decline (in line with the current economic recession) while non-U.S. sales increase through 2020. There would be an overall increase in the total amount of magnetic rare earths consumed in the world. Total consumption of each rare earth in the short

  12. Thermal Stir Welds in Titanium

    NASA Astrophysics Data System (ADS)

    Fonda, Richard W.; Knipling, Keith E.; Pilchak, Adam L.

    2016-01-01

    Although conventional friction stir welding (FSW) has proven unsuccessful in joining thick sections of alpha and near-alpha titanium alloys, thermal stir welding, a variant of the FSW process in which an external heat source is used to preheat the workpiece, is demonstrated to be able to reliably join 12.3-mm-thick plates of CP titanium. This paper describes the microstructures and textures that develop in these thermal stir welds. The observed microstructure was used to reconstruct the high-temperature microstructure and texture present during the welding process and therefore reveal the genesis of the welding structures.

  13. Ion implantation induced nanotopography on titanium and bone cell adhesion

    NASA Astrophysics Data System (ADS)

    Braceras, Iñigo; Vera, Carolina; Ayerdi-Izquierdo, Ana; Muñoz, Roberto; Lorenzo, Jaione; Alvarez, Noelia; de Maeztu, Miguel Ángel

    2014-08-01

    Permanent endo-osseous implants require a fast, reliable and consistent osseointegration, i.e. intimate bonding between bone and implant, so biomechanical loads can be safely transferred. Among the parameters that affect this process, it is widely admitted that implant surface topography, surface energy and composition play an important role. Most surface treatments to improve osseointegration focus on micro-scale features, as few can effectively control the effects of the treatment at nanoscale. On the other hand, ion implantation allows controlling such nanofeatures. This study has investigated the nanotopography of titanium, as induced by different ion implantation surface treatments, its similarity with human bone tissue structure and its effect on human bone cell adhesion, as a first step in the process of osseointegration. The effect of ion implantation treatment parameters such as energy (40-80 keV), fluence (1-2 e17 ion/cm2) and ion species (Kr, Ar, Ne and Xe) on the nanotopography of medical grade titanium has been measured and assessed by AFM and contact angle. Then, in vitro tests have been performed to assess the effect of these nanotopographies on osteoblast adhesion. The results have shown that the nanostructure of bone and the studied ion implanted surfaces, without surface chemistry modification, are in the same range and that such modifications, in certain conditions, do have a statistically significant effect on bone tissue forming cell adhesion.

  14. Neodymium and strontium isotopic constraints on soil sources in Barbados, West Indies

    NASA Astrophysics Data System (ADS)

    Borg, Lars E.; Banner, Jay L.

    1996-11-01

    Neodymium and strontium isotopic compositions and Sm/Nd ratios are used to constrain the sources of silicate-rich soils developed on uplifted Pleistocene coral-reef limestones on Barbados, West Indies. The geographic and geologic setting of Barbados facilitates the application of these tracers to the evaluation of the following soil sources: (1) Pleistocene reef limestone regolith, (2) Tertiary carbonate rocks, sandstones, and mudstones that are exposed in northeastern Barbados, (3) volcanic ash erupted from the Lesser Antilles arc, (4) Saharan dust transported by trade winds, and (5) fertilizer. The soils have ɛNd values that range from -6.6 to -1.9, 87Sr /86Sr values of 0.70890 to 0.71067, and Sm/Nd ratios of 0.223-0.260. The Pleistocene limestone component is the most significant source of Sr in the soils and a negligible source of Nd. Comparison of Sm and Nd concentrations and neodymium isotopic compositions of soil samples that are weathered to varying extents indicates that Sm and Nd are relatively unfractionated and retained in the soils during weathering. ɛNd and Sm/Nd variations in the soils, therefore, primarily reflect the compositions and proportions of the silicate sources. Mass balance calculations based on SmNd systematics require that the silicate soil components contain between 30-85% volcanic ash, with the remaining silicate fraction comprised of old, continentally-derived sediment. In contrast to Sm and Nd, Sr is mobilized and removed from the soils during weathering. Strontium from volcanic and carbonate sources is preferentially removed relative to continental silicate sources. The strontium isotopic compositions of the soils, therefore, reflect the combined effects of the degree of weathering and the compositions and proportions of the soil sources. Mass balance calculations indicate that at least 35-60% of the initial Sr in the soils has been removed by weathering. These results illustrate (1) the utility of radiogenic isotopes in

  15. The interplay between particulate and dissolved neodymium in the Western North Atlantic: First insights and interpretations

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Kretschmer, S.; Lambelet, M.; van de Flierdt, T.; Rutgers van der Loeff, M.; Rijkenberg, M. J. A.; Gerringa, L. J.; De Baar, H. J. W.

    2014-12-01

    Dissolved neodymium (Nd) isotopes (expressed as ɛNd) have been widely used as a water mass tracer to reconstruct paleo ocean circulation. However, the marine geochemical cycle of Nd is not well understood. Unclear input mechanisms, scarcity of available data, and observed decoupling between dissolved ɛNd and Nd concentration patterns ([Nd]) are only a few of the unresolved issues. The latter is often referred to as the Nd paradox(e.g. Goldstein and Hemming 2003). Here we revisit this paradox with an unprecedented data set on particulate Nd isotope and concentration data from five stations along the Dutch GEOTRACES transect GA02 in the western North and equatorial Atlantic Ocean (cruises 64PE319 and 64PE321 from April to July 2010). Particulates were collected with in-situ pumps on 0.8 µm Supor filters and subjected to a total digestion procedure in the home laboratory. The particulates collected farthest north (Irminger Sea and Labrador Sea) show a strong affinity to the nearby land masses in their Nd isotope composition: Very negative values (ɛNd ≈-20) are observed in the Labrador Sea, which is surrounded by old continental rocks. More positive values of up to ɛNd ≈-4 are found east of Greenland probably derived from the Nansen Fjord Formation's basaltic rocks. In these two areas the particulate ɛNd is offset from dissolved Nd isotopes by up to 7.7 ɛ-units, but reveals a similar vertical distribution. Further downstream of the flow path of the North Atlantic Deep Water, dissolved and particulate Nd isotopic compositions in the water column seem to merge and become indistinguishable from one another south of Bermuda (BATS station). This seems to indicate that particulate and dissolved fractions exchange with increasing distance from source regions and age of water masses. Neodymium concentrations in particulates [pNd] are low (KD<5%) and invariant. However, most stations show a significant increase in [pNd] close to the seafloor, where [pNd] nearly

  16. Neodymium isotopes in Archean seawater and implications for the marine Nd cycle in Earth's early oceans

    NASA Astrophysics Data System (ADS)

    Alexander, Brian W.; Bau, Michael; Andersson, Per

    2009-06-01

    Published neodymium (Nd) isotopic data for Archean iron-formations (IF) suggest that, overall, seawater throughout the Archean typically displayed 143Nd/ 144Nd close to bulk Earth values, with ЄNd( t) between - 1.5 and + 2.5. Neodymium isotopic ratios in seawater during deposition of the ~ 3.8 Isua (Greenland) IF likely displayed positive ЄNd(3.8 Ga) of + 2.5, as suggested by IF-G, an Isua reference IF that is considered the best archive for Early Archean seawater. Seawater 143Nd/ 144Nd ratios dominated by radiogenic Nd (positive ЄNd( t)) seem to have persisted for much of the Archean, as IF from the Pietersburg greenstone belt, South Africa, suggest seawater ЄNd(2.95 Ga) ≥ + 1. However, similarly aged (~ 2.9 Ga) IFs from South Africa indicate that significant variations in seawater 143Nd/ 144Nd occurred, and clearly show influences from isotopically distinct crustal sources. These variations are apparently related to depositional environment, with cratonic margin, shallow-water IFs possessing a continental ЄNd( t) of - 3, while IFs associated with sub-aqueous mafic volcanics display more radiogenic, positive ЄNd( t) values. Such variation in seawater 143Nd/ 144Nd is not possible in an isotopically well-mixed ocean, and similar to today, it appears that marine Nd cycling in the Archean produced water masses with distinct Nd isotopic ratios. Since the presence of banded iron-formations requires a reducing Archean ocean capable of transporting Fe, metal-oxide precipitation and scavenging processes near deep sea hydrothermal vent systems would not have scavenged mantle Nd, i.e., Nd sourced from alteration of oceanic crust. We propose that bulk anoxic seawater prior to 2.7 Ga possessed relatively constant positive ЄNd( t) of + 1 to + 2, whereas local shallow-water masses associated with exposed evolved crust could possess distinctly different, lower ЄNd( t).

  17. Preparation and characterization of TiO2/silicate hierarchical coating on titanium surface for biomedical applications.

    PubMed

    Huang, Qianli; Liu, Xujie; Elkhooly, Tarek A; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

    2016-03-01

    In the current work, TiO2/silicate hierarchical coatings with various nanostructure morphologies were successfully prepared on titanium substrates through micro-arc oxidation (MAO) and subsequent hydrothermal treatment (HT). Moreover, the nucleation mechanism and growth behavior of the nanostructures, hydrophilicity, protein adsorption and apatite-inducing ability of various coatings were also explored. The novel TiO2/silicate hierarchical coatings comprised calcium silicate hydrate (CSH) as an outer-layer and TiO2 matrix as an inner-layer. According to the morphological features, the nanostructures were classified as nanorod, nanoplate and nanoleaf. The morphology, degree of crystallinity and crystalline phases of CSH nanostructures could be controlled by optimizing the HT conditions. The nucleation of CSH nanostructures is caused by release and re-precipitation mechanism. The TiO2/CSH hierarchical coatings exhibited some enhanced physical and biological performances compared to MAO-fabricated coating. The improvement of the hydrophilicity, fibronectin adsorption and apatite-inducing ability was found to be morphological dependent according to the following trend: nanoleaf coating>nanoplate coating>nanorod coating>MAO coating. The results indicate that the tuning of physical and morphological properties of nanostructures coated on biomaterial surface could significantly influence the hydrophilicity, protein adsorption and in vitro bioactivity of biomaterial. PMID:26706535

  18. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, II, George T.; Hansen, Jeffrey S.; Oden, Laurance L.; Turner, Paul C.; Ochs, Thomas L.

    1998-01-01

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  19. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, G.T. II; Hansen, J.S.; Oden, L.L.; Turner, P.C.; Ochs, T.L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body followed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet. 3 figs.

  20. Method of making multilayered titanium ceramic composites

    DOEpatents

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  1. Design of nanostructured-based glucose biosensors

    NASA Astrophysics Data System (ADS)

    Komirisetty, Archana; Williams, Frances; Pradhan, Aswini; Konda, Rajini B.; Dondapati, Hareesh; Samantaray, Diptirani

    2012-04-01

    This paper presents the design of glucose sensors that will be integrated with advanced nano-materials, bio-coatings and electronics to create novel devices that are highly sensitive, inexpensive, accurate, and reliable. In the work presented, a glucose biosensor and its fabrication process flow have been designed. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. Currently, the biosensors are being fabricated using the process flow developed. Once completed, the sensors will be bio-functionalized and tested to characterize their performance, including their sensitivity and stability.

  2. Bone integration capability of nanopolymorphic crystalline hydroxyapatite coated on titanium implants

    PubMed Central

    Yamada, Masahiro; Ueno, Takeshi; Tsukimura, Naoki; Ikeda, Takayuki; Nakagawa, Kaori; Hori, Norio; Suzuki, Takeo; Ogawa, Takahiro

    2012-01-01

    The mechanism by which hydroxyapatite (HA)-coated titanium promotes bone–implant integration is largely unknown. Furthermore, refining the fabrication of nano-structured HA to the level applicable to the mass production process for titanium implants is challenging. This study reports successful creation of nanopolymorphic crystalline HA on microroughened titanium surfaces using a combination of flame spray and low-temperature calcination and tests its biological capability to enhance bone–implant integration. Sandblasted microroughened titanium implants and sandblasted + HA-coated titanium implants were subjected to biomechanical and histomorphometric analyses in a rat model. The HA was 55% crystallized and consisted of nanoscale needle-like architectures developed in various diameters, lengths, and orientations, which resulted in a 70% increase in surface area compared to noncoated microroughened surfaces. The HA was free from impurity contaminants, with a calcium/phosphorus ratio of 1.66 being equivalent to that of stoichiometric HA. As compared to microroughened implants, HA-coated implants increased the strength of bone–implant integration consistently at both early and late stages of healing. HA-coated implants showed an increased percentage of bone–implant contact and bone volume within 50 μm proximity of the implant surface, as well as a remarkably reduced percentage of soft tissue intervention between bone and the implant surface. In contrast, bone volume outside the 50 μm border was lower around HA-coated implants. Thus, this study demonstrated that the addition of pure nanopolymorphic crystalline HA to microroughened titanium not only accelerates but also enhances the level of bone–implant integration and identified the specific tissue morphogenesis parameters modulated by HA coating. In particular, the nanocrystalline HA was proven to be drastic in increasing osteoconductivity and inhibiting soft tissue infiltration, but the effect was

  3. Synthesis and properties of nanoscale titanium boride

    NASA Astrophysics Data System (ADS)

    Efimova, K. A.; Galevskiy, G. V.; Rudneva, V. V.

    2015-09-01

    This work reports the scientific and technological grounds for plasma synthesis of titanium diboride, including thermodynamic and kinetic conditions of boride formation when titanium and titanium dioxide are interacting with products resulting from boron gasification in the nitrogen - hydrogen plasma flow, and two variations of its behavior using the powder mixtures: titanium - boron and titanium dioxide - boron. To study these technology variations, the mathematical models were derived, describing the relation between element contents in the synthesized products of titanium and free boron and basic parameters. The probable mechanism proposed for forming titanium diboride according to a "vapour - melt - crystal" pattern was examined, covering condensation of titanium vapour in the form of aerosol, boriding of nanoscale melt droplets by boron hydrides and crystallization of titanium - boron melt. The comprehensive physical - chemical certification of titanium diboride was carried out, including the study of its crystal structure, phase and chemical composition, dispersion, morphology and particle oxidation. Technological application prospects for use of titanium diboride nanoscale powder as constituent element in the wettable coating for carbon cathodes having excellent physical and mechanical performance and protective properties.

  4. Nanoindentation of Carbon Nanostructures.

    PubMed

    Kumar, Dinesh; Singh, Karamjit; Verma, Veena; Bhatti, H S

    2016-06-01

    In the present research paper carbon nanostructures viz. single walled carbon nanotubes, multi-walled carbon nanotubes, single walled carbon nanohorns and graphene nanoplatelets have been synthesized by CVD technique, hydrothermal method, DC arc discharge method in liquid nitrogen and microwave technique respectively. After synthesis 5 mm thick pallets of given nanomaterial are prepared by making a paste in isopropyl alcohol and using polyvinylidene difluoride as a binder and then these pallets were used for nanoindentation measurements. Hardness, reduced modulus, stiffness, contact height and contact area have been measured using nanoindenter. PMID:27427726

  5. Biomimetics of photonic nanostructures

    NASA Astrophysics Data System (ADS)

    Parker, Andrew R.; Townley, Helen E.

    2007-06-01

    Biomimetics is the extraction of good design from nature. One approach to optical biomimetics focuses on the use of conventional engineering methods to make direct analogues of the reflectors and anti-reflectors found in nature. However, recent collaborations between biologists, physicists, engineers, chemists and materials scientists have ventured beyond experiments that merely mimic what happens in nature, leading to a thriving new area of research involving biomimetics through cell culture. In this new approach, the nanoengineering efficiency of living cells is harnessed and natural organisms such as diatoms and viruses are used to make nanostructures that could have commercial applications.

  6. Nanostructures for peroxidases

    PubMed Central

    Carmona-Ribeiro, Ana M.; Prieto, Tatiana; Nantes, Iseli L.

    2015-01-01

    Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability. PMID:26389124

  7. Nanostructures for peroxidases.

    PubMed

    Carmona-Ribeiro, Ana M; Prieto, Tatiana; Nantes, Iseli L

    2015-01-01

    Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability. PMID:26389124

  8. Fatigue behavior of titanium alloys

    SciTech Connect

    Boyer, R.R.; Eylon, D.; Luetjering, G.

    1999-07-01

    This symposium was international in nature, with leaders in the fields of fatigue technology and the metallurgy of titanium from the US, Europe and Asia. It covered basic research, development, applications and modeling--life predictions and design of both fatigue crack initiation and propagation of titanium alloys. There were presentations on the full range of titanium alloy systems, from commercially pure and {alpha}-alloys, {alpha}/{beta}- and {beta}-alloys to the gamma titanium aluminides. The effects of processing/heat treatment/microstructure on the fatigue properties were discussed, and models proposed to correlate the microstructures to the observed fatigue performance. Test environments reported on included hard vacuum (and the effect of vacuum level), vacuums with partial pressures of miscellaneous gases, lab air and aqueous media. A session was devoted to the effects of environment and fatigue enhancement via surface treatments using techniques such as shot peening and roller burnishing. The effects of dwell on both S-N and crack growth rate behavior were covered. It was a very comprehensive symposium with presentations from academia, government laboratories and industry, with industrial participants ranging from the petroleum industry to medical and aerospace interests. This book has been separated into four sections, representing the technology areas covered in various sessions, namely Mechanisms of Fatigue crack Initiation and Propagation of Conventional Alloys, Fatigue in Intermetallics, Environmental and Surface Aspects of Fatigue, and Application, Life Prediction and Design. Separate abstracts were prepared for most papers in this volume.

  9. Lactobacillusassisted synthesis of titanium nanoparticles

    PubMed Central

    2007-01-01

    An eco-friendlylactobacillussp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.

  10. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-07-28

    A plutonium-uranium alloy suitable for use as the fuel element in a fast breeder reactor is described. The alloy contains from 15 to 60 at.% titanium with the remainder uranium and plutonium in a specific ratio, thereby limiting the undesirable zeta phase and rendering the alloy relatively resistant to corrosion and giving it the essential characteristic of good mechanical workability.

  11. Defective titanium dioxide single crystals exposed by high-energy {001} facets for efficient oxygen reduction

    NASA Astrophysics Data System (ADS)

    Pei, Dan-Ni; Gong, Li; Zhang, Ai-Yong; Zhang, Xing; Chen, Jie-Jie; Mu, Yang; Yu, Han-Qing

    2015-10-01

    The cathodic material plays an essential role in oxygen reduction reaction for energy conversion and storage systems. Titanium dioxide, as a semiconductor material, is usually not recognized as an efficient oxygen reduction electrocatalyst owning to its low conductivity and poor reactivity. Here we demonstrate that nano-structured titanium dioxide, self-doped by oxygen vacancies and selectively exposed with the high-energy {001} facets, exhibits a surprisingly competitive oxygen reduction activity, excellent durability and superior tolerance to methanol. Combining the electrochemical tests with density-functional calculations, we elucidate the defect-centred oxygen reduction reaction mechanism for the superiority of the reductive {001}-TiO2-x nanocrystals. Our findings may provide an opportunity to develop a simple, efficient, cost-effective and promising catalyst for oxygen reduction reaction in energy conversion and storage technologies.

  12. Defective titanium dioxide single crystals exposed by high-energy {001} facets for efficient oxygen reduction

    PubMed Central

    Pei, Dan-Ni; Gong, Li; Zhang, Ai-Yong; Zhang, Xing; Chen, Jie-Jie; Mu, Yang; Yu, Han-Qing

    2015-01-01

    The cathodic material plays an essential role in oxygen reduction reaction for energy conversion and storage systems. Titanium dioxide, as a semiconductor material, is usually not recognized as an efficient oxygen reduction electrocatalyst owning to its low conductivity and poor reactivity. Here we demonstrate that nano-structured titanium dioxide, self-doped by oxygen vacancies and selectively exposed with the high-energy {001} facets, exhibits a surprisingly competitive oxygen reduction activity, excellent durability and superior tolerance to methanol. Combining the electrochemical tests with density-functional calculations, we elucidate the defect-centred oxygen reduction reaction mechanism for the superiority of the reductive {001}-TiO2−x nanocrystals. Our findings may provide an opportunity to develop a simple, efficient, cost-effective and promising catalyst for oxygen reduction reaction in energy conversion and storage technologies. PMID:26493365

  13. Nanorough titanium surfaces reduce adhesion of Escherichia coli and Staphylococcus aureus via nano adhesion points.

    PubMed

    Lüdecke, Claudia; Roth, Martin; Yu, Wenqi; Horn, Uwe; Bossert, Jörg; Jandt, Klaus D

    2016-09-01

    Microbial adhesion to natural and synthetic materials surfaces is a key issue e.g. in food industry, sewage treatment and most importantly in the biomedical field. The current development and progress in nanoscale structuring of materials surfaces to control microbial adhesion requires an advanced understanding of the microbe-material-interaction. This study aimed to investigate the nanostructure of the microbe-material-interface and link it to microbial adhesion kinetics as function of titanium surface nanoroughness to gain new insight into controlling microbial adhesion via materials' surface nanoroughness. Adhesion of Escherichia coli and Staphylococcus aureus was statistically significantly reduced (p≤0.05) by 55.6 % and 40.5 %, respectively, on physical vapor deposited titanium thin films with a nanoroughness of 6nm and the lowest surface peak density compared to 2nm with the highest surface peak density. Cross-sectioning of the microbial cells with a focused ion beam (FIB) and SEM imaging provided for the first time direct insight into the titanium-microbe-interface. High resolution SEM micrographs gave evidence that the surface peaks are the loci of initial contact between the microbial cells and the material's surface. In a qualitative model we propose that the initial microbial adhesion on nanorough surfaces is controlled by the titanium surface peak density via nano adhesion points. This new understanding will help towards the design of materials surfaces for controlling microbial adhesion. PMID:27288816

  14. A new solid-state, frequency-doubled neodymium-YAG photocoagulation system.

    PubMed

    Jalkh, A E; Pflibsen, K; Pomerantzeff, O; Trempe, C L; Schepens, C L

    1988-06-01

    We have developed a solid-state laser system that produces a continuous green monochromatic laser beam of 532 nm by doubling the frequency of a neodymium-YAG laser wavelength of 1064 nm with a potassium-titamyl-phosphate crystal. Photocoagulation burns of equal size and intensity were placed in two rabbit eyes with the solid-state laser system and the regular green argon laser system, respectively, using the same slit-lamp mode of delivery. Histologic findings of lesion sections revealed no important differences between the two systems. In theory, the longer wavelength of the solid-state laser offers the advantages of less scattering in ocular media, higher absorption by oxyhemoglobin, and less absorption by macular xanthophyll than the 514-nm wavelength of the regular green argon laser. The solid-state laser has impressive technical advantages: it contains no argon-ion gas tube that wears out and is expensive to replace; it is much more power efficient, and thus considerably smaller and compact; it is sturdier and easily movable; it does not require external cooling; it uses a 220-V monophasic alternating current; and it requires little maintenance. PMID:3370017

  15. Denmark Strait water circulation traced by heterogeneity in neodymium isotopic compositions

    NASA Astrophysics Data System (ADS)

    Lacan, Francois; Jeandel, Catherine

    2004-01-01

    Seawater neodymium isotopic composition ( ɛNd) and rare earth element (REE) concentrations were measured along four hydrologic sections within the East Greenland Current (EGC), between the Fram and the Denmark Straits, during summer 1999. EGC intermediate waters, between 77°N and 70°N, displaying similar hydrological characteristics as Denmark Strait Overflow Water (DSOW), had very constant REE characteristics and ɛNd value of -10.9. This constancy reveals the absence of lithogenic input, from the East Greenland margin, into intermediate waters in this area, corroborating previous dissolved aluminum data. The DSOW was characterized by ɛNd=-8.4±1.4. This value can be explained by the imprint of lithogenic formations, mainly basaltic, bordering the Denmark Strait on the intermediate waters described above. However, granitic Precambrian formations seem to contribute, although more slightly, to defining the DSOW Nd signature. This double influence could explain the heterogeneity of the Denmark Strait waters. These results provide a better understanding of the DSOW Nd signature, allowing a better use of this tracer in the study of present and past North Atlantic Deep Water dynamics. Atlantic Water was present at a station located at the mouth of Nansen Fjord, on the western side of Denmark Strait. We suggest that this water reaches the fjord intermittently as isolated water lenses or eddies detached from the northward flowing branch of the Irminger current.

  16. Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary

    PubMed Central

    Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

    2015-01-01

    Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (−8.9) to values typical of river suspended matter (−10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

  17. Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

    PubMed

    Rousseau, Tristan C C; Sonke, Jeroen E; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

    2015-01-01

    Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (-8.9) to values typical of river suspended matter (-10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

  18. Reduced North Atlantic Deep Water flux to the glacial Southern Ocean inferred from neodymium isotope ratios

    PubMed

    Rutberg; Hemming; Goldstein

    2000-06-22

    The global circulation of the oceans and the atmosphere transports heat around the Earth. Broecker and Denton suggested that changes in the global ocean circulation might have triggered or enhanced the glacial-interglacial cycles. But proxy data for past circulation taken from sediment cores in the South Atlantic Ocean have yielded conflicting interpretations of ocean circulation in glacial times--delta13C variations in benthic foraminifera support the idea of a glacial weakening or shutdown of North Atlantic Deep Water production, whereas other proxies, such as Cd/Ca, Ba/Ca and 231Pa/230Th ratios, show little change from the Last Glacial Maximum to the Holocene epoch. Here we report neodymium isotope ratios from the dispersed Fe-Mn oxide component of two southeast Atlantic sediment cores. Both cores show variations that tend towards North Atlantic signatures during the warm marine isotope stages 1 and 3, whereas for the full glacial stages 2 and 4 they are closer to Pacific Ocean signatures. We conclude that the export of North Atlantic Deep Water to the Southern Ocean has resembled present-day conditions during the warm climate intervals, but was reduced during the cold stages. An increase in biological productivity may explain the various proxy data during the times of reduced North Atlantic Deep Water export. PMID:10879531

  19. Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems.

    PubMed

    Lumetta, Gregg J; Sinkov, Sergey I; Krause, Jeanette A; Sweet, Lucas E

    2016-02-15

    The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO(-) anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions. PMID:26815878

  20. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications.

    PubMed

    Zacchia, Nicholas A; Valentine, Megan T

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy. PMID:26026529

  1. Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources

    USGS Publications Warehouse

    Horan, M.F.; Walker, R.J.; Fedorenko, V.A.; Czamanske, G.K.

    1995-01-01

    Picrites from the Gudchikhinsky suite, the oldest rocks examined, have ??Os of +5.3 to +6.1 and ??Nd of +3.7 to +4.0. The osmium and neodymium isotopic compositions of these rocks are similar to some modern ocean-island basalts (OIB), consistent with their derivation from an mantle plume. Picrites from the stratigraphically higher Tuklonsky suite have similar ??Os of +3.4 to +6.5, but ??Nd of -0.9 to -2.6. The similar ??Os, but lower ??Nd , suggest that some magmas from the same OIB-type, mantle source were contaminated by lithospheric components. A differentiated ankaramite flow, associated with the top of the stratigraphically higher Morongovsky suite, has ??Os of +9.8 to +10.2 and ??Nd of +1.3 to +1.4. The higher ??Os may indicate that the plume source was heterogeneous with respect to osmium isotopic composition, consistent with osmium isotopic measurements in rocks from other plume sources. Mg-rich, alkaline rocks (meymechites) from the Guli area that erupted much nearer the end of the flood-basalt event have ??Os of -1.2 to -2.6 and ??Nd of +3.7 to +4.9. These rocks were probably produced by low degrees of partial melting of mantle after the main stages of flood-basalt production. -from Authors

  2. Rhenium-osmium and samarium-neodymium isotopic systematics of the stillwater complex

    USGS Publications Warehouse

    Lambert, D.D.; Morgan, J.W.; Walker, R.J.; Shirey, S.B.; Carlson, R.W.; Zientek, M.L.; Koski, M.S.

    1989-01-01

    Isotopic data for the Stillwater Complex, Montana , which formed about 2700 Ma (million years ago), were obtained to evaluate the role of magma mixing in the formation of strategic platinum-group element (PGE) ore deposits. Neodymium and osmium isotopic data indicate that the intrusion formed from at least two geochemically distinct magmas. Ultramafic affinity (U-type) magmas had initial ??Nd of -0.8 to -3.2 and a chondritic initial 187Os/186Os ratio of ???0.88, whereas anorthositic affinity (A-type) magmas had ??Nd of -0.7 to +1.7 and an initial 187Os/186Os ratio of ???1.13. These data suggest that U-type magmas were derived from a lithospheric mantle source containing recycled crustal materials whereas A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The Nd and Os isotopic data also suggest that Os, and probably the other PGEs in ore horizons such as the J-M Reef, was derived from A-type magmas. The Nd and Os isotopic heterogeneity observed in rocks below the J-M Reef also suggests that A-type magmas were injected into the Stillwater U-type magma chamber at several stages during the development of the Ultramafic series.

  3. Neodymium:yttrium-aluminium-garnet laser for excision of pulmonary nodules: an institutional review.

    PubMed

    Moghissi, Keyvan; Dixon, Kate

    2009-03-01

    Eighty patients amongst 850 undergoing pulmonary surgery with the use of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser had a solitary pulmonary nodule (< or = 50 mm) on chest radiography, which was confirmed or suspected pre-operatively to be primary lung cancer. All patients had a mini-thoracotomy to expose the lesion. They then had Nd:YAG laser to excise the nodule locally. There was no hospital mortality. Six patients had non-fatal post-operative complications. Pathologically, 46 patients had primary lung cancer and ten had secondary lung cancer. Twenty-four others had benign lesions. Mean hospital stay was 5.5 days. Post-operative reduction of forced vital capacity (FVC) and forced expiratory volume in one second (FEV(1)) was 14% and 13% (mean), respectively. Thirty-seven patients with primary lung cancer were followed up for between 12 months and 60 months. Mean survival time of these patients was 39 months (s.d. 13 months). It was concluded that Nd:YAG laser for pulmonary nodular lesions should be considered for a selected group of patients unsuitable for standard resection. PMID:18214573

  4. Clinical comparison of semiconductor diode versus neodymium: YAG non-contact cyclo photocoagulation.

    PubMed Central

    Ulbig, M W; McHugh, D A; McNaught, A I; Hamilton, A M

    1995-01-01

    AIMS--The advent of diode lasers has allowed their use in transscleral cyclo photocoagulation for refractory glaucoma. A trial was performed to compare the ocular hypotensive and inflammatory effects of cyclo photocoagulation using a continuous wave diode (810 nm) and a free running neodymium:yttrium aluminium garnet (Nd:YAG) laser (1064 nm). METHODS--Forty patients with refractory glaucoma were randomised to receive either diode or Nd:YAG therapy. The intraocular pressure (IOP) and inflammatory response to treatment were monitored over 3 months. RESULTS--There was no significant laser related difference in the effect on IOP after one treatment. There was, however, a difference in effect in retreatments with the IOP lowering effect significantly less, but equally sustained in diode retreatment patients. Severe postoperative complications such as hyphaema or fibrinous anterior uveitis only occurred in the Nd:YAG group. CONCLUSION--The degree and duration of the ocular hypotensive response to cyclo photocoagulation appears to be related to the available power output of the system used, and the extent of tissue damage. Images PMID:7626573

  5. Neodymium:YAG laser treatment of lower leg telangiectasia: a new minimally invasive approach.

    PubMed

    Iannitti, Tommaso; Lonardi, Roberto; Rottigni, Valentina; Palmieri, Beniamino

    2012-09-01

    The aim of this study was to validate the safety and effectiveness of a new therapeutic procedure for the treatment of lower leg telangiectasia without clinical vein insufficiency. A group of 20 healthy women aged between 24 and 47 years (mean±sem 37.05 ± 1.47) with lower leg telangiectasia without clinical vein insufficiency, previously investigated by echo colour Doppler sonography, were recruited and were treated with neodymium:YAG laser (mean±sem 2.5 ± 0.11 sessions). Good or excellent results were obtained in 16 patients and the improvements were statistically significant (p < 0.01). Out of the 20 patients, 16 were satisfied with the procedure. We strongly support laser treatment of lower leg telangiectasia since it allows injection of chemicals to be avoided, and changes the stromal microarchitecture rearranging the fibroblast network into a more resistant pattern reducing the likelihood of relapse. PMID:22205469

  6. Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

    NASA Technical Reports Server (NTRS)

    Kurweg, U. H.

    1984-01-01

    A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

  7. High-mobility thin film transistors with neodymium-substituted indium oxide active layer

    SciTech Connect

    Lin, Zhenguo; Lan, Linfeng Xiao, Peng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2015-09-14

    Thin-film transistors (TFTs) with neodymium-substituted indium oxide (InNdO) channel layer were demonstrated. The structural properties of the InNdO films as a function of annealing temperature have been analyzed using X-ray diffraction and transmission electron microscopy. The InNdO thin films showed polycrystalline nature when annealed at 450 °C with a lattice parameter (cubic cell) of 10.255 Å, which is larger than the cubic In{sub 2}O{sub 3} film (10.117 Å). The high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy showed that no Nd{sub 2}O{sub 3} clusters were found in the InNdO film, implying that Nd was incorporated into the In{sub 2}O{sub 3} lattice. The InNdO TFTs annealed at 450 °C exhibited more excellent electrical properties with a high mobility of 20.4 cm{sup 2} V{sup −1} s{sup −1} and better electric bias stability compared to those annealed at 300 °C, which was attributed to the reduction of the scattering centers and/or charge traps due to the decrease of the |Nd3d{sub 5/2}{sup 5}4f{sup 4}O2p{sup −1}〉 electron configuration.

  8. Near-infrared electroluminescence at room temperature from neodymium-doped gallium nitride thin films

    SciTech Connect

    Kim, Joo Han; Holloway, Paul H.

    2004-09-06

    Strong near-infrared (NIR) electroluminescence (EL) at room temperature from neodymium (Nd)-doped gallium nitride (GaN) thin films is reported. The Nd-doped GaN films were grown by radio-frequency planar magnetron cosputtering of separate GaN and metallic Nd targets in a pure nitrogen ambient. X-ray diffraction data did not identify the presence of any secondary phases and revealed that the Nd-doped GaN films had a highly textured wurtzite crystal structure with the c-axis normal to the surface of the film. The EL devices were fabricated with a thin-film multilayered structure of Al/Nd-doped GaN/Al{sub 2}O{sub 3}-TiO{sub 2}/indium-tin oxide and tested at room temperate. Three distinct NIR EL emission peaks were observed from the devices at 905, 1082, and 1364 nm, arising from the radiative relaxation of the {sup 4}F{sub 3sol2} excited-state energy level to the {sup 4}I{sub 9sol2}, {sup 4}I{sub 11sol2}, and {sup 4}I{sub 13sol2} levels of the Nd{sup 3+} ion, respectively. The threshold voltage for all the three emission peaks was {approx}150 V. The external power efficiency of the fabricated EL devices was {approx}1x10{sup -5} measured at 40 V above the threshold voltage.

  9. Endoscopic management of post-traumatic prostatic and supraprostatic strictures using Neodymium-YAG laser.

    PubMed

    Nabi, Ghulam; Dogra, Prem Nath

    2002-12-01

    We assessed the feasibility, efficacy and long-term results of endoscopic management using Neodymium-YAG (Nd-YAG) laser as a day care procedure in patients with post-traumatic supraprostatic and prostatic strictures. Three patients with post-traumatic prostatic and supraprostatic obliterative strictures underwent Nd-YAG laser core through urethrotomy as a day care procedure. Patient age ranged between 12 and 14 years. Mean duration of injury was 16 months. The length of stricture was assessed by bi-directional endoscopy prior to the procedure in all cases. Core through procedure was carried out using Nd-YAG laser under the guidance of a cystoscope placed antegradely. Patients were discharged on the same day with urethral catheter. Foley catheters were removed at 6 weeks. Nd-YAG laser core through procedure was carried out successfully in all cases with negligible blood loss in a mean time of 48 min. There were no intraoperative or postoperative complications. Patients were discharged on the same day. Follow-up cystogram was conducted at 6 weeks and urethroscopy at months. At a mean follow-up of 23 months, patients were asymptomatic and voiding well. Nd-YAG laser core through urethrotomy is a safe and effective procedure. It is a less invasive alternative to more complex urethroplasty procedures for patients with post-traumatic prostatic and supraprostatic strictures. It can be carried out as a day care procedure in carefully selected patients and has no complications. PMID:12492959

  10. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  11. Optical properties of Lead bismuth borate glasses doped with neodymium oxide.

    PubMed

    Farouk, M; Abd El-Maboud, A; Ibrahim, M; Ratep, A; Kashif, I

    2015-10-01

    Neodymium doped Lead bismuth borate glasses with the composition of 25PbO-25Bi2O3-50B2O3:xNd2O3, where x=0.5, 1, 1.5 and 2 mol%, have been prepared by melt quenching technique. The behavior of the density and molar volume allows concluding that, addition of Nd2O3 leads to the formation of non-bridging oxygen. Rare earth ion parameters have been calculated and studied. The optical band gap (Eg), and band tails (Ee) were determined. Judd-Ofelt theory for the intensity analysis of induced electric dipole transitions has been applied to the measured oscillator strengths of the absorption bands to determine the three phenomenological intensity parameters Ω2, Ω4 and Ω6 for glass. It was observed that the deviation parameters, rms, was found to be 0.56:0.58(×10(-6)). The estimated Judd-Ofelt parameters were found to be Nd2O3concentration dependent. The hypersensitive transition, (4)I9/2→(4)G5/2+(2)G7/2, is closely related to Ω2 parameter. PMID:25965518

  12. Crystal and Electronic Study of Neodymium-Substituted CuFeO2 Oxide

    NASA Astrophysics Data System (ADS)

    Ozkendir, Osman Murat

    2016-06-01

    Neodymium-substituted CuFeO2 samples were investigated according to their crystal and electronic properties via the general formula Nd x Cu1- x FeO2. The crystal structure analysis results revealed polycrystalline formations in the sample and a change in crystalline sizes with the substituted heavy fermion "Nd." Increasing the Nd amount in the sample was determined to cause a disturbance on the Cu-Fe planes that supports the formation of crystal structures with low crystal symmetries such as monoclinic or triclinic geometries. To obtain the background mechanisms of the crystal properties, the X-ray absorption fine structure spectroscopy technique was used to study the electronic properties of the samples. Prominent changes in the crystal structures due to 4 f electrons' contributions from the substituted Nd atoms as the main "role player" in the phase transitions were determined. The Nd atoms were observed as the key element guiding the entire phenomenon as a result of their large size and narrow 4 f levels. Also, magnetic properties of the samples were tested at room temperature and without an applied magnetic field by X-ray magnetic circular dichroism study due to previous studies that reported the parent oxide CuFeO2 to have magnetic ordering at T N = 11 K (-262 °C). Except the sample for x = 1.0 (NdFeO3), no magnetic ordering was observed at room temperature; i.e., all of the samples showed paramagnetic behaviors.

  13. Optical radiation hazards of laser welding processes. Part 1: Neodymium-YAG laser.

    PubMed

    Rockwell, R J; Moss, C E

    1983-08-01

    High power laser devices are being used for numerous metalworking processes such as welding, cutting and heat treating. Such laser devices are totally enclosed either by the manufacturer or the end-user. When this is done, the total laser system is usually certified by the manufacturer following the federal requirements of the Code of Federal Regulations (CFR) 1040.10 and 10.40.11 as a Class I laser system. Similarly, the end-user may also reclassify an enclosed high-power laser into the Class I category following the requirements of the American National Standards Institute (ANSI) Z-136.1 (1980) standard. There are, however, numerous industrial laser applications where Class IV systems are required to be used in an unenclosed manner. In such applications, there is concern for both ocular and skin hazards caused by direct and scattered laser radiation, as well as potential hazards caused by the optical radiation created by the laser beam's interaction with the metal (i.e. the plume radiation). Radiant energy measurements are reported for both the scattered laser radiation and the resultant plume radiations which were produced during typical unenclosed Class IV Neodymium-YAG laser welding processes. Evaluation of the plume radiation was done with both radiometric and spectroradiometric measurement equipment. The data obtained were compared to applicable safety standards. PMID:6688700

  14. Constraints on ocean circulation at the Paleocene-Eocene Thermal Maximum from neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Abbott, April N.; Haley, Brian A.; Tripati, Aradhna K.; Frank, Martin

    2016-04-01

    Global warming during the Paleocene-Eocene Thermal Maximum (PETM) ˜ 55 million years ago (Ma) coincided with a massive release of carbon to the ocean-atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role of changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites to reconstruct past deep-ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth Nd isotopes and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for initiation and recovery of the ocean-atmosphere system associated with the PETM.

  15. Planar waveguides in neodymium-doped calcium niobium gallium garnet crystals produced by proton implantation

    NASA Astrophysics Data System (ADS)

    Chun-Xiao, Liu; Meng, Chen; Li-Li, Fu; Rui-Lin, Zheng; Hai-Tao, Guo; Zhi-Guang, Zhou; Wei-Nan, Li; She-Bao, Lin; Wei, Wei

    2016-04-01

    In this work, the fabrication and optical properties of a planar waveguide in a neodymium-doped calcium niobium gallium garnet (Nd:CNGG) crystal are reported. The waveguide is produced by proton (H+) implantation at 480 keV and a fluence of 1.0×1017 ions/cm2. The prism-coupling measurement is performed to obtain the dark mode of the waveguide at a wavelength of 632.8 nm. The reflectivity calculation method (RCM) is used to reconstruct the refractive index profile. The finite-difference beam propagation method (FD-BPM) is employed to calculate the guided mode profile of the waveguide. The stopping and range of ions in matter 2010 (SRIM 2010) code is used to simulate the damage profile induced by the ion implantation. The experimental and theoretical results indicate that the waveguide can confine the light propagation. Project supported by the National Natural Science Foundation of China (Grant Nos. 11405041, 61405240, 61077070, 61177086, 51002181, and 61177084), the Scientific Research Starting Foundation for New Teachers of Nanjing University of Posts and Telecommunications (NUPTSF) (Grant No. NY214159), and the Research Center of Optical Communications Engineering & Technology, Jiangsu Province, China (Grant No. ZSF0401).

  16. Laser treatment of a neodymium magnet and analysis of surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

    2016-08-01

    Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

  17. Constraints on ocean circulation at the Paleocene-Eocene Thermal Maximum from neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Abbott, A. N.; Haley, B. A.; Tripati, A. K.; Frank, M.

    2015-06-01

    Global warming during the Paleocene Eocene Thermal Maximum (PETM) ~55 million years ago (Ma) coincided with a massive release of carbon to the ocean-atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role for changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites and comparing data with published data from fossil fish debris to reconstruct past deep ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for global recovery of the ocean-atmosphere system after the PETM.

  18. Mineralogy of the mid-ocean-ridge basalt source from neodymium isotopic composition of abyssal peridotites.

    PubMed

    Salters, Vincent J M; Dick, Henry J B

    2002-07-01

    Inferring the melting process at mid-ocean ridges, and the physical conditions under which melting takes place, usually relies on the assumption of compositional similarity between all mid-ocean-ridge basalt sources. Models of mantle melting therefore tend to be restricted to those that consider the presence of only one lithology in the mantle, peridotite. Evidence from xenoliths and peridotite massifs show that after peridotite, pyroxenite and eclogite are the most abundant rock types in the mantle. But at mid-ocean ridges, where most of the melting takes place, and in ophiolites, pyroxenite is rarely found. Here we present neodymium isotopic compositions of abyssal peridotites to investigate whether peridotite can indeed be the sole source for mid-ocean-ridge basalts. By comparing the isotopic compositions of basalts and peridotites at two segments of the southwest Indian ridge, we show that a component other than peridotite is required to explain the low end of the (143)Nd/(144)Nd variations of the basalts. This component is likely to have a lower melting temperature than peridotite, such as pyroxenite or eclogite, which could explain why it is not observed at mid-ocean ridges. PMID:12097907

  19. Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Sipes, D. L.

    1985-01-01

    In recent experiments, 80-mW CW power in a single mode has been achieved from a neodymium:yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8 percent, the highest reported CW efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/sq cm), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76 percent for Nd:YAG at 1.06 microns pumped at 0.810 micron). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10 percent are expected.

  20. Power scaling of diode-pumped neodymium yttrium aluminum borate laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1991-01-01

    Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

  1. Nanofractal surface structure under laser sintering of titanium and nitinol for bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Shishkovsky, I.; Morozov, Yu.; Smurov, I.

    2007-12-01

    Comparative microanalysis and histological studies of porous titanium and nitinol (NiTi) implants fabricated by selective laser sintering are carried out. Sintered Ti and NiTi nanoporous structures are developed with grain sizes ranging from dozens to several hundreds nanometer and their formation is discussed. Dependence of the surface morphology of the implant on laser processing parameters (laser power, scanning velocity and beam diameter) is observed by analyzing the fractal-type nanostructure and its self-organization from the nano- to the macro-passing through the microlevel. It is shown that functional characteristics of the synthesized medical implants depend on the pores size distribution and their relative location as well as on the nanostructural morphology of the sintered surface.

  2. Small Titanium Oxo Clusters: Primary Structures of Titanium(IV) in Water.

    PubMed

    Zhang, Guanyun; Hou, Jie; Tung, Chen-Ho; Wang, Yifeng

    2016-04-01

    For sol-gel synthesis of titanium oxide, the titanium(IV) precursors are dissolved in water to form clear solutions. However, the solution status of titanium(IV) remains unclear. Herein three new and rare types of titanium oxo clusters are isolated from aqueous solutions of TiOSO4 and TiCl4 without using organic ligands. Our results indicate that titanium(IV) is readily hydrolyzed into oxo oligomers even in highly acidic solutions. The present clusters provide precise structural information for future characterization of the solution species and structural evolution of titanium(IV) in water and, meanwhile, are new molecular materials for photocatalysis. PMID:26990885

  3. Irradiation-Induced Nanostructures

    SciTech Connect

    Birtcher, R.C.; Ewing, R.C.; Matzke, Hj.; Meldrum, A.; Newcomer, P.P.; Wang, L.M.; Wang, S.X.; Weber, W.J.

    1999-08-09

    This paper summarizes the results of the studies of the irradiation-induced formation of nanostructures, where the injected interstitials from the source of irradiation are not major components of the nanophase. This phenomena has been observed by in situ transmission electron microscopy (TEM) in a number of intermetallic compounds and ceramics during high-energy electron or ion irradiations when the ions completely penetrate through the specimen. Beginning with single crystals, electron or ion irradiation in a certain temperature range may result in nanostructures composed of amorphous domains and nanocrystals with either the original composition and crystal structure or new nanophases formed by decomposition of the target material. The phenomenon has also been observed in natural materials which have suffered irradiation from the decay of constituent radioactive elements and in nuclear reactor fuels which have been irradiated by fission neutrons and other fission products. The mechanisms involved in the process of this nanophase formation are discussed in terms of the evolution of displacement cascades, radiation-induced defect accumulation, radiation-induced segregation and phase decomposition, as well as the competition between irradiation-induced amorphization and recrystallization.

  4. Tensile properties of titanium electrolytically charged with hydrogen

    NASA Technical Reports Server (NTRS)

    Smith, R. J.; Otterson, D. A.

    1971-01-01

    Yield strength, ultimate tensile strength, and elongation were studied for annealed titanium electrolytically charged with hydrogen. The hydrogen was present as a surface hydride layer. These tensile properties were generally lower for uncharged titanium than for titanium with a continuous surface hydride; they were greater for uncharged titanium than for titanium with an assumed discontinuous surface hydride. We suggest that the interface between titanium and titanium hydride is weak. And the hydride does not necessarily impair strength and ductility of annealed titanium. The possibility that oxygen and/or nitrogen can embrittle titanium hydride is discussed.

  5. Facile synthesis of silicon carbide-titanium dioxide semiconducting nanocomposite using pulsed laser ablation technique and its performance in photovoltaic dye sensitized solar cell and photocatalytic water purification

    NASA Astrophysics Data System (ADS)

    Gondal, M. A.; Ilyas, A. M.; Baig, Umair

    2016-08-01

    Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO2) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet-visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

  6. EDITORIAL: Nanostructured solar cells Nanostructured solar cells

    NASA Astrophysics Data System (ADS)

    Greenham, Neil C.; Grätzel, Michael

    2008-10-01

    Conversion into electrical power of even a small fraction of the solar radiation incident on the Earth's surface has the potential to satisfy the world's energy demands without generating CO2 emissions. Current photovoltaic technology is not yet fulfilling this promise, largely due to the high cost of the electricity produced. Although the challenges of storage and distribution should not be underestimated, a major bottleneck lies in the photovoltaic devices themselves. Improving efficiency is part of the solution, but diminishing returns in that area mean that reducing the manufacturing cost is absolutely vital, whilst still retaining good efficiencies and device lifetimes. Solution-processible materials, e.g. organic molecules, conjugated polymers and semiconductor nanoparticles, offer new routes to the low-cost production of solar cells. The challenge here is that absorbing light in an organic material produces a coulombically bound exciton that requires dissociation at a donor-acceptor heterojunction. A thickness of at least 100 nm is required to absorb the incident light, but excitons only diffuse a few nanometres before decaying. The problem is therefore intrinsically at the nano-scale: we need composite devices with a large area of internal donor-acceptor interface, but where each carrier has a pathway to the respective electrode. Dye-sensitized and bulk heterojunction cells have nanostructures which approach this challenge in different ways, and leading research in this area is described in many of the articles in this special issue. This issue is not restricted to organic or dye-sensitized photovoltaics, since nanotechnology can also play an important role in devices based on more conventional inorganic materials. In these materials, the electronic properties can be controlled, tuned and in some cases completely changed by nanoscale confinement. Also, the techniques of nanoscience are the natural ones for investigating the localized states, particularly at

  7. Titanium-Oxygen Reactivity Study

    NASA Technical Reports Server (NTRS)

    Chafey, J. E.; Scheck, W. G.; Witzell, W. E.

    1962-01-01

    A program has been conducted at Astronautics to investigate the likelihood of occurrence of the catastrophic oxidation of titanium alloy sheet under conditions which simulate certain cases of accidental failure of the metal while it is in contact with liquid or gaseous oxygen. Three methods of fracturing the metal were used; they consisted of mechanical puncture, tensile fracture of welded joints, and perforation by very high velocity particles. The results of the tests which have been conducted provide further evidence of the reactivity of titanium with liquid and gaseous oxygen. The evidence indicates that the rapid fracturing of titanium sheet while it is in contact with oxygen initiates the catastrophic oxidation reaction. Initiation occurred when the speed of the fracture was some few feet per second, as in both the drop-weight puncture tests and the static tensile fracture tests of welded joints, as well as when the speed was several thousand feet per second, as in the simulated micrometeoroid penetration tests. The slow propagation of a crack, however, did not initiate the reaction. It may logically be concluded that the localized frictional heat of rapid fracture and/or spontaneous oxidation (exothermic) of minute particles emanating from the fracture cause initiation of the reaction. Under conditions of slow fracture, however, the small heat generated may be adequately dissipated and the reaction is not initiated. A portion of the study conducted consisted of investigating various means by which the reaction might be retarded or prevented. Providing a "barrier" at the titanium-oxygen interface consisting of either aluminum metal or a coating of a petroleum base corrosion inhibitor appeared to be only partially effective in retarding the reaction. The accidental puncturing or similar rupturing of thin-walled pressurized oxygen tanks on missiles and space vehicle will usually constitute loss of function, and may sometimes cause their catastrophic destruction

  8. Efficient and Robust Thermoelectric Power Generation Device Using Hot-Pressed Metal Contacts on Nanostructured Half-Heusler Alloys

    NASA Astrophysics Data System (ADS)

    Joshi, Giri; Poudel, Bed

    2016-06-01

    We report an efficient thermoelectric device with power density of 8.9 W/cm2 and efficiency of 8.9% at 678°C temperature difference using hot-pressed titanium metal contact layers on nanostructured half-Heusler materials. The high power density and efficiency are due to the efficient nanostructured materials and very low contact resistance of ~1 μΩ cm2 between the titanium layer and half-Heusler material. Moreover, the bonding strength between the titanium and half-Heusler is more than 50 MPa, significantly higher compared with conventional contact metallization methods. The low contact resistance and high bonding strength are due to thin-layer diffusion of titanium (<100 μm) into the half-Heusler at high temperature (>600°C). The low contact resistance and high bonding strength result in a stable and efficient power generation device with great potential for use in recovery of waste heat, e.g., in automotive and industrial applications.

  9. Repairable, nanostructured biomimetic hydrogels

    NASA Astrophysics Data System (ADS)

    Firestone, M.; Brombosz, S.; Grubjesic, S.

    2013-03-01

    Proteins facilitate many key cellular processes, including signal recognition and energy transduction. The ability to harness this evolutionarily-optimized functionality could lead to the development of protein-based systems useful for advancing alternative energy storage and conversion. The future of protein-based, however, requires the development of materials that will stabilize, order and control the activity of the proteins. Recently we have developed a synthetic approach for the preparation of a durable biomimetic chemical hydrogel that can be reversibly swollen in water. The matrix has proven ideal for the stable encapsulation of both water- and membrane-soluble proteins. The material is composed of an aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid and a zwitterionic co-surfactant that self-assembles into a nanostructured physical gel at room temperature as determined by X-ray scattering. The addition of a water soluble PEGDA co-monomer and photoinitator does not alter the self-assembled structure and UV irradiation serves to crosslink the acrylate end groups on the macromer with the PEGDA forming a network within the aqueous domains as determined by FT-IR. More recently we have begun to incorporate reversible crosslinks employing Diels-Alder chemistry, allowing for the extraction and replacement of inactive proteins. The ability to replenish the materials with active, non-denatured forms of protein is an important step in advancing these materials for use in nanostructured devices This work was supported by the Office of Basic Energy Sciences, Division of Materials Sciences, USDoE under Contract No. DE-AC02-06CH11357.

  10. Holocene fluctuations of neodymium isotope ratios in eastern Fram Strait sediments - An indication for deepwater variability?

    NASA Astrophysics Data System (ADS)

    Werner, K.; Frank, M.; Teschner, C.; Zieringer, M.; Spielhagen, R. F.

    2012-04-01

    The Fram Strait as the only deep water connection of the world's oceans to the Arctic plays a substantial role for the heat influx to the Arctic Ocean and controls freshening of the Nordic Seas through Arctic sea ice export. Large amounts of warm and saline Atlantic Water derived from the North Atlantic Drift transport most of the heat through eastern Fram Strait to the Arctic basin, resulting in year-round ice-free conditions. Arctic sea ice and cold and fresh waters exit the western part of the strait southward along the Greenland shelf. However, little is still known about the water mass transport at intermediate and bottom water depths in the Fram Strait. High-resolution Holocene sediment sequences from the Western Svalbard margin have been investigated for its neodymium isotope ratios stored in ferromanganese oxyhydroxide coatings of the sediment to derive information on the source of bottom seawater passing the site. The radiogenic isotope data are compared to a multitude of proxy indicators for the climatic and oceanographic variability in the eastern Fram Strait during the past 8,500 years. In order to obtain a calibration of the Nd isotope compositions extracted from sediments to modern bottom water mass signatures in the area, a set of core top and water samples from different water depths in the Fram Strait was additionally investigated for its present-day Nd isotope signatures. A significantly higher inflow of deepwater produced in the Nordic Seas to the core site is inferred for the earlier periods of the Holocene. Cooler surface water conditions and increased sea ice abundances during the late Holocene coincide with more radiogenic Nd isotope ratios likely resembling the neoglacial trend of the northern North Atlantic.

  11. How Well Do Neodymium Isotopes Trace AMOC Mixing? A Test in the Southwest Atlantic

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Goldstein, S. L.; Pena, L.; Hartman, A. E.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2014-12-01

    Neodymium (Nd) isotope ratios are used to trace past AMOC circulation, based on observations that seawater Nd isotope ratios effectively "fingerprint" water masses, and that over long water mass transport distances in deep seawater they reflect values expected from water mass mixing. Over the past several years, studies have increasingly focused on the potential of external addition of Nd along water mass transport paths (for example through "boundary exchange" with particulates or addition from groundwaters), thus challenging the idea that Nd isotopes behave "quasi-conservatively" in the oceans. The SW Atlantic, with the major water masses involved in the AMOC (southward flowing NADW, northward flowing AAIW and AABW), is arguably the best place on Earth to evaluate how well Nd isotopes trace water mass mixing, in order to clarify its value for following the AMOC through time. We will report Nd isotope ratios of seawater collected on the SW Atlantic meridional transect of the NIOZ West Atlantic GEOTRACES Cruise Leg 3 (RRS James Cook 057), which sampled seawater profiles and the sediment surface at 18 stations between 0-50°S. Most stations are sampled in the open ocean, providing a test of whether Nd isotopes show quasi-conservative mixing systematics away from continental margins. The cruise section also provides several opportunities to test the potential effects of external Nd input. For example, it transects the continental shelf in the far south, the Rio Grande Rise, volcanic seamounts, and the major geological age boundaries of South America. It also crosses the major Southern Hemisphere wind zones, allowing us to test the impacts of aeolian input, and inputs from major rivers (Parana-Paraguay, Sao Francisco, Amazon). All of these features have the potential to modify the seawater Nd isotope ratios, allowing us to determine if they add significant external Nd.

  12. Development of an empirical kinetic model for sonocatalytic process using neodymium doped zinc oxide nanoparticles.

    PubMed

    Khataee, Alireza; Vahid, Behrouz; Saadi, Shabnam; Joo, Sang Woo

    2016-03-01

    The degradation of Acid Blue 92 (AB92) solution was investigated using a sonocatalytic process with pure and neodymium (Nd)-doped ZnO nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The 1% Nd-doped ZnO nanoparticles demonstrated the highest sonocatalytic activity for the treatment of AB92 (10 mg/L) with a degradation efficiency (DE%) of 86.20% compared to pure ZnO (62.92%) and sonication (45.73%) after 150 min. The results reveal that the sonocatalytic degradation followed pseudo-first order kinetics. An empirical kinetic model was developed using nonlinear regression analysis to estimate the pseudo-first-order rate constant (kapp) as a function of the operational parameters, including the initial dye concentration (5-25 mg/L), doped-catalyst dosage (0.25-1 g/L), ultrasonic power (150-400 W), and dopant content (1-6% mol). The results from the kinetic model were consistent with the experimental results (R(2)=0.990). Moreover, DE% increases with addition of potassium periodate, peroxydisulfate, and hydrogen peroxide as radical enhancers by generating more free radicals. However, the addition of chloride, carbonate, sulfate, and t-butanol as radical scavengers declines DE%. Suitable reusability of the doped sonocatalyst was proven for several consecutive runs. Some of the produced intermediates were also detected by GC-MS analysis. The phytotoxicity test using Lemna minor (L. minor) plant confirmed the considerable toxicity removal of the AB92 solution after treatment process. PMID:26584992

  13. Effect of neodymium substitution on structural and ferroelectric properties of BNT ceramics

    SciTech Connect

    Pal, Vijayeta; Dwivedi, R.K.; Thakur, O.P.

    2014-03-01

    Graphical abstract: - Highlights: • First time, we synthesized (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} system by semi wet technique. • Grain size reduced with doping and Nd acts as an inhibitor in the grain growth. • Specimen with x = 0.02 exhibits excellent ferroelectric properties at RT. • P–E loops show the co-existence of polar and non polar regions around ‘T{sub d}’. - Abstract: Polycrystalline specimens of (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} (BNNT) ceramic system with compositions x ≤ 0.04 were synthesized by semi-wet technique using ethylene glycol precursor. Structural and electrical properties were investigated in detail to observe the effect of neodymium (Nd) substitution in BNT system. XRD patterns for all the specimens showed single phase formation with rhombohedral structure. Field emission scanning electron micrographs (FE-SEM) revealed that the grain growth was inhibited significantly with Nd content. The temperature dependence behaviour of dielectric constant revealed that the depolarisation temperature ‘T{sub d}’ decreases whereas temperature of maximum dielectric constant ‘T{sub m}’ increases with Nd concentration. The piezoelectric charge coefficient (d{sub 33}) showed maxima at x = 0.02 and well defined ferroelectric behaviour was observed for all the samples.

  14. Microscale neodymium distribution in sedimentary planktonic foraminiferal tests and associated mineral phases

    NASA Astrophysics Data System (ADS)

    Tachikawa, Kazuyo; Toyofuku, Takashi; Basile-Doelsch, Isabelle; Delhaye, Thomas

    2013-01-01

    Neodymium isotopic ratios recorded in calcareous foraminiferal tests (shells) and associated authigenic minerals were used to trace past water masses, although the origin of preserved Nd signals is still a matter of debate. We determined, for the first time, the microscale Nd distribution in two planktonic foraminifera species (Globigerinoides ruber and Neogloboquadrina dutertrei) and coexisting authigenic minerals from two selected time slices (15.6 and 129 kyr) of a marine sediment core in the Panama Basin. Elemental mapping of Nd, Ca, Fe, Mn, and Si was performed using NanoSIMS ion probe and electron probe microanalysis (EPMA) on uncleaned tests together with scanning electron microscopy (SEM) imagery. EPMA and SEM images revealed the presence of Fe-rich framboidal minerals inside test pores and inner chambers, particularly in the old samples. The young sample presented Fe- and Mn-rich patches on the inner test wall. The Nd intensity in Fe-Mn-rich patches and in some framboids was much higher than in foraminiferal calcite, where the Nd distribution was randomly heterogeneous with no systematic features such as an ontogenic Nd-rich layer or species-specific differences. The relationship between Nd, Fe, and Mn confirmed a significant role of Fe-Mn oxides as a Nd carrier. The high Nd enrichment in some framboids could be explained by Nd adsorption onto oxidized surface of Fe sulfides particles rather than direct incorporation. Since the authigenic precipitates are major Nd carrier phases, the Nd isotopic signals in sedimentary foraminiferal tests likely reflect bottom/pore water values rather than surface water ones.

  15. Past Hydrological Variability in the Congo Basin inferred from Neodymium Isotopes

    NASA Astrophysics Data System (ADS)

    Bayon, G.

    2015-12-01

    Major events of vegetation changes and soil erosion occurred in Central Africa during the last few millennia, at a time when the first farmers settled in the rainforest. The palaeoclimatic context in which these environmental changes took place still remains poorly constrained. Improving our knowledge on the drivers of past hydrological variability in Central Africa is important to further evaluate the relative role of climate versus humans in shaping late Holocene African landscapes. In this study, we have used neodymium (Nd) isotopes in a marine sediment core to reconstruct the composition of the sediment load exported from the Congo Basin during the Holocene. Core KZR23 was recovered at 2200 m water depth from within the Congo submarine canyon and is characterized by high sedimentation rates (about 2m/kyr), thereby allowing reconstruction of past river sediment discharge at an unprecedented high temporal resolution. A suite of river particulate samples collected from the main tributaries within the Congo watershed was analyzed in order to tag each major sub-basin with the characteristic geochemical and Nd isotopic signatures of its source region. In parallel, an annual series of suspended particles sampled on a monthly basis at the Congo River ORE-HYBAM station (Brazzaville) was also analyzed to characterize the seasonality of sediment provenance in relation with present hydrological cycle. Using Nd isotopes as tracers for sediment provenance together and other proxy data for past erosion, vegetation and rainfall patterns (i.e. bulk sediment radiocarbon data, pollens, biomarkers, compound-specific isotope analyses), we will provide a more comprehensive picture of past hydrological variability in the Congo Basin for the Holocene period.

  16. High resolution neodymium characterization along the Mediterranean Sea margins: implications for ɛNd modeling.

    NASA Astrophysics Data System (ADS)

    Ayache, Mohamed; Dutay, Jean-claude; Arsouze, Thomas; Jeandel, Catherine; Revillon, Sidonie

    2016-04-01

    An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (ɛNd) was realized in order to establish a new database and a map (using a high resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done, in order to improve this dataset in key areas (e.g Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions, (ɛNd values -11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high resolution regional oceanic model (1/12° of horizontal resolution), ɛNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides the opportunity to study in more details the processes governing the Nd isotope distribution in the marine environment. This work highlights that a significant interannual variability of ɛNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in Nd IC at intermediate depths that could be noticeable in the Western part of the basin. This highlights that the temporal and geographical variations of ɛNd could represent an interesting insight of Nd as a quasi-conservative tracer of water masses in the Mediterranean Sea, in particular in the context of paleo-oceanographic applications, i.e. to explore if EMT-type signatures occurred in the past (Roether et al., 2014, Gacic et al., 2011).

  17. A composite nanostructured electron-transport layer for stable hole-conductor free perovskite solar cells: design and characterization

    NASA Astrophysics Data System (ADS)

    Yu, Zhenhua; Qi, Fei; Liu, Pei; You, Sujian; Kondamareddy, Kiran Kumar; Wang, Changlei; Cheng, Nian; Bai, Sihang; Liu, Wei; Guo, Shishang; Zhao, Xing-Zhong

    2016-03-01

    A novel composite nanostructured titanium dioxide (TiO2) based electron-transport layer (ETL) is designed by combining size blended nanoparticles (SBNP) and nanoarrays (NA) for efficient perovskite solar cell (PSC) applications. The composite nanostructured (SBNP + NA) ETL is successfully employed in hole-conductor free PSCs, there by achieving a stable device with a maximum efficiency of 13.5%. The improvement in the performance is attributed to the better charge transport and lower recombination in the SBNP + NA ETL. Despite the stable high efficiency, SBNP + NA ETL based PSCs are advantageous owing to their low cost, ease of all-solution fabrication process in an open environment and good reproducibility.A novel composite nanostructured titanium dioxide (TiO2) based electron-transport layer (ETL) is designed by combining size blended nanoparticles (SBNP) and nanoarrays (NA) for efficient perovskite solar cell (PSC) applications. The composite nanostructured (SBNP + NA) ETL is successfully employed in hole-conductor free PSCs, there by achieving a stable device with a maximum efficiency of 13.5%. The improvement in the performance is attributed to the better charge transport and lower recombination in the SBNP + NA ETL. Despite the stable high efficiency, SBNP + NA ETL based PSCs are advantageous owing to their low cost, ease of all-solution fabrication process in an open environment and good reproducibility. Electronic supplementary information (ESI) available: Details of the experimental section and ESI figures. See DOI: 10.1039/c5nr09045h

  18. TOPICAL REVIEW: Magnetic surface nanostructures

    NASA Astrophysics Data System (ADS)

    Enders, A.; Skomski, R.; Honolka, J.

    2010-11-01

    Recent trends in the emerging field of surface-supported magnetic nanostructures are reviewed. Current strategies for nanostructure synthesis are summarized, followed by a predominantly theoretical description of magnetic phenomena in surface magnetic structures and a review of experimental research in this field. Emphasis is on Fe- or Co-based nanostructures in various low-dimensional geometries, which are studied as model systems to explore the effects of dimensionality, atomic coordination, chemical bonds, alloying and, most importantly, interactions with the supporting substrate on the magnetism. This review also includes a discussion of closely related systems, such as 3d element impurities integrated into organic networks, surface-supported Fe-based molecular magnets, Kondo systems or 4d element nanostructures that exhibit emergent magnetism, thereby bridging the traditional areas of surface science, molecular physics and nanomagnetism.

  19. Nanostructured Materials for Renewable Energy

    SciTech Connect

    2009-11-01

    This factsheet describes a research project whose overall objective is to advance the fundamental understanding of novel photoelectronic organic device structures integrated with inorganic nanostructures, while also expanding the general field of nanomaterials for renewable energy devices and systems.

  20. Peptide nanostructures in biomedical technology.

    PubMed

    Feyzizarnagh, Hamid; Yoon, Do-Young; Goltz, Mark; Kim, Dong-Shik

    2016-09-01

    Nanostructures of peptides have been investigated for biomedical applications due to their unique mechanical and electrical properties in addition to their excellent biocompatibility. Peptides may form fibrils, spheres and tubes in nanoscale depending on the formation conditions. These peptide nanostructures can be used in electrical, medical, dental, and environmental applications. Applications of these nanostructures include, but are not limited to, electronic devices, biosensing, medical imaging and diagnosis, drug delivery, tissue engineering and stem cell research. This review offers a discussion of basic synthesis methods, properties and application of these nanomaterials. The review concludes with recommendations and future directions for peptide nanostructures. WIREs Nanomed Nanobiotechnol 2016, 8:730-743. doi: 10.1002/wnan.1393 For further resources related to this article, please visit the WIREs website. PMID:26846352

  1. Homogeneous liquid-liquid extraction of neodymium(III) by choline hexafluoroacetylacetonate in the ionic liquid choline bis(trifluoromethylsulfonyl)imide.

    PubMed

    Onghena, Bieke; Jacobs, Jeroen; Van Meervelt, Luc; Binnemans, Koen

    2014-08-14

    The ionic liquid choline bis(trifluoromethylsulfonyl)imide, [Chol][Tf2N], was used for the extraction of neodymium(III), in combination with choline hexafluoroacetylacetonate, [Chol][hfac], as the extractant. The binary mixture of [Chol][Tf2N] and water shows temperature-dependent phase behavior, with an upper critical solution temperature of 72 °C. A novel extraction technique, homogeneous liquid-liquid extraction (HLLE), was applied to this solvent system. HLLE is based on the use of thermomorphic solvent mixtures and has the advantage of forming a homogeneous phase during mixing. Extraction is not kinetically hindered by an interface and the extraction equilibrium is reached faster than in the case of heterogeneous mixing in conventional solvent extraction. Several extraction parameters were studied for the extraction of neodymium(III) with [Chol][hfac]: temperature, pH, extractant concentration and loading of the ionic liquid phase. A speciation study was performed to determine the stoichiometry of the extracted neodymium(III) complex and a plausible extraction mechanism is proposed. Neodymium is extracted as a tetrakis hexafluoroacetylacetonate complex with one choline cation as counter ion. The crystal structure of the extracted complex showed the presence of a coordination bond between the choline counter ion and the neodymium(III) center, resulting in a coordination number of nine. The stripping of the loaded neodymium and the influence of acid and extractant concentrations on the phase behavior of the [Chol][Tf2N]-H2O system were investigated. PMID:24938933

  2. Metallographic preparation of titanium diboride coatings

    SciTech Connect

    McAllaster, M.E.

    1980-03-01

    A method is described for preparing metallographic cross sections of thin, hard, chemically vapor deposited titanium diboride coatings on various softer substrates. Standard metallographic preparation techniques were found to result in fracturing and edge rounding of the coatings. It is shown that these problems can be avoided by unidirectional grinding on worn 600 grit silicon carbide abrasive paper. Typical photomicrographs of chemically vapor deposited titanium diboride coatings are shown along with photomicrographs of intermediate phases that form at the titanium diboride - substrate interfaces.

  3. Production of titanium from ilmenite: a review

    SciTech Connect

    Kohli, R.

    1981-12-01

    The general principles for beneficiation of titanium ores are reviewed and the specific processes used in individual units in various countries are discussed. This is followed by a critical evaluation of various current and potential reduction methods for the production of titanium metal from the processed concentrates. Finally, the report outlines a research program for the development of a commercially viable alternative method for the production of titanium metal.

  4. Ultrafine-grained titanium for medical implants

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Stolyarov, Vladimir V.; Latysh, Vladimir V.; Raab, Georgy J.

    2002-01-01

    We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

  5. Large-mode-area single-mode-output Neodymium-doped silicate glass all-solid photonic crystal fiber

    PubMed Central

    Li, Wentao; Chen, Danping; Qinling, Zhou; Hu, Lili

    2015-01-01

    We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M2 1.18. PMID:26205850

  6. Diode pumped neodymium doped ASL (Sr1-xLax-yNdyMgxAl12-xO19) laser

    NASA Astrophysics Data System (ADS)

    Zheng, Lihe; Loiseau, Pascal; Aka, Gérard

    2013-07-01

    Blue laser based on Neodymium doped strontium lanthanum magnesium aluminoxide (Sr1-xLax-yNdyMgxAl12-xO19) single crystal were constructed by second harmonic generation. Output power of 1.72 W at 900nm was obtained under 792nm laser diode pump. Intra cavity second harmonic generation were performed with non linear crystal LBO leading to output power of 76.6 mW at 450nm with absorbed power of 13.7 W and average absorption efficiency of 61% in Nd:ASL crystal.

  7. Morphologic and histologic changes in canine temporomandibular joint tissues following arthroscopic guided neodymium:YAG laser exposure

    SciTech Connect

    Bradrick, J.P.; Eckhauser, M.L.; Indresano, A.T. )

    1989-11-01

    A neodymium:yttrium aluminum garnet (Nd:YAG) laser beam was introduced by a quartz fiber passed arthroscopically into the superior joint space of the temporomandibular joints (TMJ) of five mongrel dogs, with one joint serving as a control without laser wounds. Immediate postoperative death and examination of the disc grossly and histologically revealed different patterns for contact and noncontact burn wounds. The wounds exhibited signs of thermal coagulation necrosis similar to those reported in other tissues. The potential implications of the adaptation of the Nd:YAG laser to TMJ arthroscopic surgery are discussed.

  8. Surfactant free most probable TiO2 nanostructures via hydrothermal and its dye sensitized solar cell properties

    PubMed Central

    Mali, Sawanta S.; Kim, Hyungjin; Shim, Chang Su; Patil, Pramod S.; Kim, Jin Hyeok; Hong, Chang Kook

    2013-01-01

    Tailoring the nano-morphology and nano-architecture of titanium dioxide (TiO2) is the most important task in the third generation solar cells (Dye sensitized solar cells/Quantum dot sensitized solar cells) (DSSCs/QDSSCs). In this article we present complete study of surfactant free synthesis of TiO2 nanostructures by a simple and promising hydrothermal route. The plethora of nanostructures like nanoparticles clusters, 1D tetragonal nanorods, 3D dendrites containing nanorods having <30 nm diameter and 3D hollow urchin like have been synthesized. These nanostructures possess effective large surface area and thus useful in DSSCs. In the present work, 7.16% power conversion efficiency has been demonstrated for 3D dendritic hollow urchin like morphology. Our synthetic strategy provides an effective solution for surfactant free synthesis of efficient TiO2 nanoarchitectures. PMID:24141599

  9. The Design, Construction and Testing of a Multipole Wiggler Magnet Titanium Vacuum Chamber for the SRS.

    NASA Astrophysics Data System (ADS)

    Bliss, Neil; Dawson, Cheryl

    1997-05-01

    An upgrade to the SRS is planned, which will provide high quality X-rays to upto four new experimental stations, on two new beamlines. These X-rays will originate in two new 2T multipole wiggler (MPW) insertion devices. The insertion devices are a hybrid design consisting of Neodymium-Iron-Boron permanent magnets and Vanadium Permendur pole pieces. In order to achieve the high on-axis field strength of the MPW and reduce the volume of permanent magnet material, a minimum amount of vacuum chamber material is required between the electron beam stay clear aperture and the poles of the MPW. Careful consideration has been given to the design, material selection and construction technique for the vacuum chamber to achieve a 1 mm wall thickness and 0.3 mm flatness tolerance over the nine pole face areas. Titanium alloy Ti-6Al-4V has been chosen in preference to more conventional ultra high vacuum chamber materials and a prototype has been constructed and tested.

  10. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, S.J.; White, J.C.

    1998-08-04

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag. 1 fig.

  11. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, Stephen J.; White, Jack C.

    1999-01-01

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  12. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    DOEpatents

    Gerdemann, Stephen J.; White, Jack C.

    1998-01-01

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  13. Recovery of titanium values from titanium grinding swarf by electric furnace smelting

    SciTech Connect

    Gerdemann, S.J.; White, J.C.

    1999-10-19

    A method for the recovery of valuable materials from titanium grinding swarf is provided comprising the steps of sieving the accumulated titanium grinding swarf to remove unwanted coarse trash and grinding wheel fragments, pelletizing, and smelting in an electric arc furnace to produce ferrotitanium and/or high titanium slag.

  14. The effects of hydrogen embrittlement of titanium

    NASA Technical Reports Server (NTRS)

    Taylor, Delbert J.

    1989-01-01

    Titanium alloys, by virtue of their attractive strength to density ratio, fatigue, fracture toughness and corrosion resistance are now commonly used in various aerospace and marine applications. The cost, once very expensive, has been reduced, making titanium even more of a competitive material today. Titanium and titanium alloys have a great affinity to several elements. Hydrogen, even in small amounts, can cause embrittlement, which in turn causes a reduction in strength and ductility. The reduction of strength and ductility is the subject of this investigation.

  15. Method for producing titanium aluminide weld rod

    DOEpatents

    Hansen, Jeffrey S.; Turner, Paul C.; Argetsinger, Edward R.

    1995-01-01

    A process for producing titanium aluminide weld rod comprising: attaching one end of a metal tube to a vacuum line; placing a means between said vacuum line and a junction of the metal tube to prevent powder from entering the vacuum line; inducing a vacuum within the tube; placing a mixture of titanium and aluminum powder in the tube and employing means to impact the powder in the tube to a filled tube; heating the tube in the vacuum at a temperature sufficient to initiate a high-temperature synthesis (SHS) reaction between the titanium and aluminum; and lowering the temperature to ambient temperature to obtain a intermetallic titanium aluminide alloy weld rod.

  16. Vacuum arc deposition of nanostructured multilayer coatings for biomedical applications.

    PubMed

    Vladescu, A; Kiss, A; Braic, M; Cotrut, C M; Drob, P; Balaceanu, M; Vasilescu, C; Braic, V

    2008-02-01

    In recent years, the smart materials have attracted much attention due to their unusual properties such as shape memory effect and pseudoelasticity, being widely used for biomedical implants. These materials contain certain amounts of nickel, titanium and others which are not adequate for surgical implants and prosthesis. In the work reported here, two types of nonostructured multilayer coatings (TiN/ZrN, ZrN/Zr) used to prevent the ions release from shape memory alloys were investigated. For comparison, the TiN and ZrN monolayers were also examined. The films were deposited onto nickel-titanium based alloy (Ti-Ni-Nb) and Ni substrates by vacuum arc deposition technique under various deposition conditions. The concentrations of dissolved ions in Ringer solution for uncoated and coated Ni samples were determined to examine the benefic barrier effect of these coatings for ions release from shape memory alloys. In order to have a more complete characterization of the investigated coatings, other properties such as elemental and phase composition, morphology, texture, microhardness, and adhesion were studied. For all coatings, the concentrations of dissolved ions were lower that those measured in the case of the uncoated specimens. The nanostructured multilayer films exhibited the best mechanical and anticorrosive properties. PMID:18464399

  17. Application of anodized titanium for enhanced recruitment of endothelial progenitor cells

    PubMed Central

    2012-01-01

    Objectives To study the efficacy of an effective anodized titanium surface with enhanced attachment of endothelial progenitor cell (EPC). Background In-stent restenosis is a major obstacle for vascular patency after catheter-based intravascular interventions. Recently, stents that capture EPCs have been paid attention in order to make a functional endothelialized layer at the site of stent-induced endothelial denudation. Anodized titanium has been shown to enhance stem cell attachment. Anodization is a quick and inexpensive method, which can provide suitable stent surface. Methods Surface topography was examined by high-resolution scanning electron microscopy (SEM). Substrates were co-cultured with EPCs at second passage in 24-well culture plates. Evaluation of cell growth, proliferation, viability, surface cytotoxicity and cell adhesion was performed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and 4,6-diamidino-2-phenylindole dihydrochloride staining. For platelet attachment, platelets added to substrates were evaluated under SEM. Results The average MTT values for tissue culture polystyrene plate, unanodized and anodized titanium with nanostructure were equal to 0.49, 0.16 and 0.72, respectively (P < 0.05). The surface had no cytotoxic effects on cells. The average cell attachment results showed that 9,955 ± 461.18, 3,300 ± 197.98 and 11,359 ± 458.10 EPCs were attached per well of tissue culture polystyrene plate, unanodized and anodized titanium surfaces, respectively (P < 0.05). Conclusions Anodized titanium surfaces can be potentially applied for devices that need enhanced recruitment of EPCs. This unique property makes these anodized surfaces good and cheap candidates for designing cardiovascular medical devices as endovascular stents. PMID:22676440

  18. Nanostructured component fabrication by electron beam-physical vapor deposition

    NASA Astrophysics Data System (ADS)

    Singh, Jogender; Wolfe, Douglas E.

    2005-08-01

    Fabrication of cost-effective, nano-grained net-shaped components has brought considerable interest to Department of Defense, National Aeronautics and Space Administration, and Department of Energy. The objective of this paper is to demonstrate the versatility of electron beam-physical vapor deposition (EB-PVD) technology in engineering new nanostructured materials with controlled microstructure and microchemistry in the form of coatings and net-shaped components for many applications including the space, turbine, optical, biomedical, and auto industries. Coatings are often applied on components to extent their performance and life under severe environmental conditions including thermal, corrosion, wear, and oxidation. Performance and properties of the coatings depend upon their composition, microstructure, and deposition condition. Simultaneous co-evaporation of multiple ingots of different compositions in the high energy EB-PVD chamber has brought considerable interest in the architecture of functional graded coatings, nano-laminated coatings, and design of new structural materials that could not be produced economically by conventional methods. In addition, high evaporation and condensate rates allowed fabricating precision net-shaped components with nanograined microstructure for various applications. Using EB-PVD, nano-grained rhenium (Re) coatings and net-shaped components with tailored microstructure and properties were fabricated in the form of tubes, plates, and Re-coated spherical graphite cores. This paper will also present the results of various metallic and ceramic coatings including chromium, titanium carbide (TiC), titanium diboride (TiB2), hafnium nitride (HfN), titanium-boron-carbonitride (TiBCN), and partially yttria stabilized zirconia (YSZ) TBC coatings deposited by EB-PVD for various applications.

  19. Microwave method for synthesis of micro- and nanostructures with controllable composition during gyrotron discharge

    NASA Astrophysics Data System (ADS)

    Batanov, German M.; Borzosekov, Valentin D.; Golberg, Dmitri; Iskhakova, Ludmila D.; Kolik, Leonid V.; Konchekov, Evgeny M.; Kharchev, Nikolai K.; Letunov, Alexander A.; Malakhov, Dmitry V.; Milovich, Filipp O.; Obraztsova, Ekaterina A.; Petrov, Alexander E.; Ryabikina, Irina G.; Sarksian, Karen A.; Stepakhin, Vladimir D.; Skvortsova, Nina N.

    2016-01-01

    We introduce an approach toward the synthesis of micro- and nanostructures under nonequilibrium microwave discharges within metal-dielectric powder mixtures induced by powerful microwave gyrotron radiation. A new plasma-chemical reactor capable of sustaining a discharge regime with an afterglow phase of an order of magnitude longer than the gyrotron pulse duration was constructed for these experiments. In the nonequilibrium conditions of such a discharge, plasma-induced exothermic chemical reactions leading to the synthesis of various compounds were initiated. The synthesized structures were deposited on the reactor walls and on the impurity particles within the reactor. This method was tested under gyrotron-initiated discharges within various metal-dielectric powder mixtures of titanium-boron, molybdenum-boron, titanium-silicon-boron, molybdenum-boron nitride, molybdenum-tungsten-boron nitride, and so on. Depending on the powder mixture composition, reactor atmosphere, and other parameters, micro- and nanosized particles of boron nitride, titanium diboride, molybdenum boride, titanium boride, molybdenum, and molybdenum oxide, were synthesized, detected, and analyzed.

  20. Tribological evaluation of diamond coating on pure titanium in comparison with plasma nitrided titanium and uncoated titanium

    SciTech Connect

    Yan, B.; Loh, N.L.; Fu, Y.; Sun, C.Q.; Hing, P.

    1999-12-01

    Titanium alloys are characterized by poor tribological properties, and the traditional use of titanium alloys has been restricted to nontribological applications. The deposition of a well adherent diamond coating is a promising way to solve this problem. In this study, the tribological properties of diamond-coated titanium were studied using a pin-on-disk tribometer, and the results were compared with those of pure titanium and plasma nitrided titanium. The tribological behavior of pure titanium was characterized by high coefficient of friction and rapid wear of materials. Plasma nitriding improved the wear resistance only under low normal load; however, this hardened layer was not efficient in improving the wear resistance and the friction properties under high normal load. Diamond coating on pure titanium improved the wear resistance of titanium significantly. Surface profilometry measurement indicated that little or no wear of the diamond coating occurred under the test conditions loads. The roughness of the diamond coating was critical because it controlled the amount of abrasive damage on the counterface. Reducing the surface roughness by polishing led to the reductions in both the friction and wear of the counterface.

  1. Understanding the wetting properties of nanostructured selenium coatings: the role of nanostructured surface roughness and air-pocket formation

    PubMed Central

    Tran, Phong A; Webster, Thomas J

    2013-01-01

    Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these influence interactions with biological elements, such as proteins, bacteria, and cells. In this study, the wetting phenomenon of titanium substrates coated with selenium nanoparticles was studied using experimental and mathematical modeling tools. Importantly, these selenium-coated titanium substrates were previously reported to increase select protein adsorption (such as vitronectin and fibronectin), to decrease bacteria growth, and increase bone cell growth. Increased selenium nanoparticle coating density resulted in higher contact angles but remained within the hydrophilic regime. This trend was found in disagreement with the Wenzel model, which is widely used to understand the wetting properties of rough surfaces. The trend also did not fit well with the Cassie–Baxter model, which was developed to understand the wetting properties of composite surfaces. A modified wetting model was thus proposed in this study, to understand the contributing factors of material properties to the hydrophilicity/hydrophobicity of these nanostructured selenium-coated surfaces. The analysis and model created in this study can be useful in designing and/or understanding the wetting behavior of numerous biomedical materials and in turn, biological events (such as protein adsorption as well as bacteria and mammalian cell functions). PMID:23737667

  2. ATOMIC LAYER DEPOSITION OF TITANIUM OXIDE THIN FILMS ONNANOPOROUS ALUMINA TEMPLATES FOR MEDICAL APPLICATIONS

    SciTech Connect

    Brigmon, R.

    2009-05-05

    Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of the nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Both the 20 nm and 100 nm titanium oxide-coated nanoporous alumina membranes did not exhibit statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. In addition, 20 nm pore size titanium oxide-coated nanoporous alumina membranes exposed to ultraviolet light demonstrated activity against Escherichia coli and Staphylococcus aureus bacteria. Nanostructured materials prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for 'smart' drug delivery devices, orthopedic implants, or self-sterilizing medical devices.

  3. Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

    NASA Astrophysics Data System (ADS)

    Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

    2016-05-01

    Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

  4. Femtosecond laser-induced periodic surface structures on steel and titanium alloy for tribological applications

    NASA Astrophysics Data System (ADS)

    Bonse, J.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Höhm, S.; Rosenfeld, A.; Krüger, J.

    2014-10-01

    Laser-induced periodic surface structures (LIPSS, ripples) were generated on stainless steel (100Cr6) and titanium alloy (Ti6Al4V) surfaces upon irradiation with multiple femtosecond laser pulses (pulse duration 30 fs, central wavelength 790 nm). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of large surface areas (5 × 5 mm2) covered homogeneously by the nanostructures. The irradiated surface regions were subjected to white light interference microscopy and scanning electron microscopy revealing spatial periods around 600 nm. The tribological performance of the nanostructured surface was characterized by reciprocal sliding against a ball of hardened steel in paraffin oil and in commercial engine oil as lubricants, followed by subsequent inspection of the wear tracks. For specific conditions, on the titanium alloy a significant reduction of the friction coefficient by a factor of more than two was observed on the laser-irradiated (LIPSS-covered) surface when compared to the non-irradiated one, indicating the potential benefit of laser surface structuring for tribological applications.

  5. Chemically enabled nanostructure fabrication

    NASA Astrophysics Data System (ADS)

    Huo, Fengwei

    The first part of the dissertation explored ways of chemically synthesizing new nanoparticles and biologically guided assembly of nanoparticle building blocks. Chapter two focuses on synthesizing three-layer composite magnetic nanoparticles with a gold shell which can be easily functionalized with other biomolecules. The three-layer magnetic nanoparticles, when functionalized with oligonucleotides, exhibit the surface chemistry, optical properties, and cooperative DNA binding properties of gold nanoparticle probes, while maintaining the magnetic properties of the Fe3O4 inner shell. Chapter three describes a new method for synthesizing nanoparticles asymmetrically functionalized with oligonucleotides and the use of these novel building blocks to create satellite structures. This synthetic capability allows one to introduce valency into such structures and then use that valency to direct particle assembly events. The second part of the thesis explored approaches of nanostructure fabrication on substrates. Chapter four focuses on the development of a new scanning probe contact printing method, polymer pen lithography (PPL), which combines the advantages of muCp and DPN to achieve high-throughput, flexible molecular printing. PPL uses a soft elastomeric tip array, rather than tips mounted on individual cantilevers, to deliver inks to a surface in a "direct write" manner. Arrays with as many as ˜11 million pyramid-shaped pens can be brought into contact with substrates and readily leveled optically in order to insure uniform pattern development. Chapter five describes gel pen lithography, which uses a gel to fabricate pen array. Gel pen lithography is a low-cost, high-throughput nanolithography method especially useful for biomaterials patterning and aqueous solution patterning which makes it a supplement to DPN and PPL. Chapter 6 shows a novel form of optical nanolithography, Beam Pen Lithography (BPL), which uses an array of NSOM pens to do nanoscale optical

  6. Modification of implant material surface properties by means of oxide nano-structured coatings deposition

    NASA Astrophysics Data System (ADS)

    Safonov, Vladimir; Zykova, Anna; Smolik, Jerzy; Rogowska, Renata; Lukyanchenko, Vladimir; Kolesnikov, Dmitrii

    2014-08-01

    The deposition of functional coatings on the metal surface of artificial joints is an effective way of enhancing joint tribological characteristics. It is well-known that nanostructured oxide coatings have specific properties advantageous for future implant applications. In the present study, we measured the high hardness parameters, the adhesion strength and the low friction coefficient of the oxide magnetron sputtered coatings. The corrosion test results show that the oxide coating deposition had improved the corrosion resistance by a factor of ten for both stainless steel and titanium alloy substrates. Moreover, the hydrophilic nature of coated surfaces in comparison with the metal ones was investigated in the tensiometric tests. The surfaces with nanostructured oxide coatings demonstrated improved biocompatibility for in vitro and in vivo tests, attributed to the high dielectric constants and the high values of the surface free energy parameters.

  7. The Roles of Titanium Surface Micro/Nanotopography and Wettability on the Differential Response of Human Osteoblast Lineage Cells

    PubMed Central

    Gittens, Rolando A.; Olivares-Navarrete, Rene; Cheng, Alice; Anderson, David M.; McLachlan, Taylor; Stephan, Ingrid; Geis-Gerstorfer, Jürgen; Sandhage, Kenneth H.; Fedorov, Andrei G.; Rupp, Frank; Boyan, Barbara D.; Tannenbaum, Rina; Schwartz, Zvi

    2013-01-01

    Surface micro and nanostructural modifications of dental and orthopaedic implants have shown promising in vitro, in vivo, and clinical results. Surface wettability has also been suggested to play an important role in osteoblast differentiation and osseointegration. However, the available techniques to measure surface wettability are not reliable on clinically-relevant, rough surfaces. Furthermore, how the differentiation state of osteoblast lineage cells impacts their response to micro/nanostructured surfaces, and the role of wettability on this response, remains unclear. In the current study, surface wettability analyses (optical sessile drop analysis, ESEM analysis, and the Wilhelmy technique) indicated hydrophobic static responses for deposited water droplets on microrough and micro/nanostructured specimens, while hydrophilic responses were observed with dynamic analyses of micro/nanostructured specimens. The maturation and local factor production of human immature osteoblast-like MG63 cells was synergistically influenced by nanostructures superimposed onto microrough titanium (Ti) surfaces. In contrast, human mesenchymal stem cells (MSCs) cultured on micro/nanostructured surfaces in the absence of exogenous soluble factors, exhibited less robust osteoblastic differentiation and local factor production compared to cultures on unmodified microroughened Ti. Our results support previous observations using Ti6Al4V surfaces showing that recognition of surface nanostructures and subsequent cell response is dependent on the differentiation state of osteoblast lineage cells. The results also indicate that this effect may be partly modulated by surface wettability. These findings support the conclusion that the successful osseointegration of an implant depends on contributions from osteoblast lineage cells at different stages of osteoblast commitment. PMID:23232211

  8. Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

    NASA Astrophysics Data System (ADS)

    Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

    2013-02-01

    The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

  9. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

    PubMed

    Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

    2015-01-01

    Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. PMID:25278442

  10. Synthesis and thermal stability studies of a series of metastable Dion–Jacobson double-layered neodymium-niobate perovskites

    SciTech Connect

    Josepha, Elisha A.; Farooq, Sara; Mitchell, Cinnamon M.; Wiley, John B.

    2014-08-15

    The Dion–Jacobson double-layered perovskite, RbNdNb{sub 2}O{sub 7}, is used as a precursor to synthesize the series ANdNb{sub 2}O{sub 7} (A=H, Li, Na, K, NH{sub 4}, Ag), and (MCl)NdNb{sub 2}O{sub 7} (M=Mn, Fe, Cu) through ion-exchange reactions ≤400 °C. Thermal stability studies indicated that most of these compounds are metastable. A combination of X-ray powder diffraction and differential thermal analysis were used to determine various low temperature decomposition pathways; these pathways were very dependent on the interlayer species. Overall the ANdNb{sub 2}O{sub 7} series was found to be less stable than the corresponding lanthanides, ALaNb{sub 2}O{sub 7}. - Graphical abstract: A new series of topochemically-prepared metastable neodymium-containing layered perovskites are studied. - Highlights: • A series of new layered neodymium containing perovskites were synthesized by ion exchange. • Products were studied by variable temperature X-ray diffraction and thermal analysis. • Most of the series are metastable showing exothermic transitions on decomposition. • The Nd compounds are less stable due to the smaller size of the Nd relative to La.

  11. Cathodic processes of neodymium(iii) in LiF-NdF3-Nd2O3 melts.

    PubMed

    Huang, Chao; Liu, Xiaolong; Gao, Yuan; Liu, Shizhe; Li, Bing

    2016-08-15

    In this paper, cyclic voltammetry and square wave voltammetry are applied to characterize the cathode processes of neodymium ions on a W electrode in LiF-NdF3 melts with or without the metal Nd. The results indicate that neodymium ions in the LiF-NdF3 (2 wt%) melt are reduced in two steps, i.e. Nd(3+) → Nd(2+) and Nd(2+) → Nd(0), corresponding to starting reduction potentials of 0.35 V vs. Li(+)/Li and 0.1 V vs. Li(+)/Li, respectively. The Nd(3+) → Nd(2+) process is controlled by mass transfer and the Nd(2+) → Nd(0) process is controlled by both an interfacial step and mass transfer. But in the LiF-NdF3 melt with excess metal Nd equilibrium, the kinetics of the above two processes are controlled by mass transfer. After potentiostatic electrolysis at 0.35 V in the LiF-NdF3-Nd2O3 melt NdF2 is formed on the Mo cathode, and metallic Nd is obtained by potentiostatic electrolysis at 0.1 V in the LiF-NdF3-Nd2O3-Nd melt, which validates the above electrochemical reduction results. PMID:27197114

  12. Neodymium-YAG laser iridotomy in the treatment and prevention of angle closure glaucoma. A review of 373 eyes.

    PubMed

    Tomey, K F; Traverso, C E; Shammas, I V

    1987-04-01

    The records of 271 consecutive patients (373 eyes) who underwent neodymium-YAG laser iridotomy at our institution over a period of 12 months were reviewed. The majority of eyes (60.5%) were treated for chronic primary angle closure glaucoma, 23.3% had prophylactic iridotomy for occludable angles, 7.8% were treated for acute angle closure glaucoma, 3.2% required iridotomy for the relief of iris bombé secondary to anterior uveitis, and the rest (5.2%) were treated for miscellaneous causes of secondary angle closure. Laser iridotomy, with or without medical treatment, obviated further surgical treatment in most categories of eyes. Visual acuity remained unchanged or improved in the great majority (92%) of cases over the period of follow-up (range, two to 12 months; median, four months). Visual deterioration in 8% of eyes was attributed to the usual causes, such as normal cataract progression, but none was believed to be related to the laser treatment. This article discusses the advantages of the neodymium-YAG laser (over argon) for performing iridotomies. PMID:3566599

  13. Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

    PubMed

    Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Suh, Sangwon; Shigetomi, Yosuke; Oshita, Yuko

    2014-01-01

    This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows. PMID:24387330

  14. A nanostructured electrochromic supercapacitor.

    PubMed

    Wei, Di; Scherer, Maik R J; Bower, Chris; Andrew, Piers; Ryhänen, Tapani; Steiner, Ullrich

    2012-04-11

    We report the first successful application of an ordered bicontinuous double-gyroid vanadium pentoxide network in an electrochromic supercapacitor. The freestanding vanadia network was fabricated by electrodeposition into a voided block copolymer template that had self-assembled into the double-gyroid morphology. The highly ordered structure with 11.0 nm wide struts and a high specific surface to bulk volume ratio of 161.4 μm(-1) is ideal for fast and efficient lithium ion intercalation/extraction and faradaic surface reactions, which are essential for high energy and high power density electrochemical energy storage devices. Supercapacitors made from such gyroid-structured vanadia electrodes exhibit a high specific capacitance of 155 F g(-1) and show a strong electrochromic color change from green/gray to yellow, indicating the capacitor's charge condition. The nanostructuring approach and utilizing an electrode material that has intrinsic electrochemical color-change properties are concepts that can be readily extended to other electrochromic intercalation compounds. PMID:22390702

  15. Phonon engineering for nanostructures.

    SciTech Connect

    Aubry, Sylvie; Friedmann, Thomas Aquinas; Sullivan, John Patrick; Peebles, Diane Elaine; Hurley, David H.; Shinde, Subhash L.; Piekos, Edward Stanley; Emerson, John Allen

    2010-01-01

    Understanding the physics of phonon transport at small length scales is increasingly important for basic research in nanoelectronics, optoelectronics, nanomechanics, and thermoelectrics. We conducted several studies to develop an understanding of phonon behavior in very small structures. This report describes the modeling, experimental, and fabrication activities used to explore phonon transport across and along material interfaces and through nanopatterned structures. Toward the understanding of phonon transport across interfaces, we computed the Kapitza conductance for {Sigma}29(001) and {Sigma}3(111) interfaces in silicon, fabricated the interfaces in single-crystal silicon substrates, and used picosecond laser pulses to image the thermal waves crossing the interfaces. Toward the understanding of phonon transport along interfaces, we designed and fabricated a unique differential test structure that can measure the proportion of specular to diffuse thermal phonon scattering from silicon surfaces. Phonon-scale simulation of the test ligaments, as well as continuum scale modeling of the complete experiment, confirmed its sensitivity to surface scattering. To further our understanding of phonon transport through nanostructures, we fabricated microscale-patterned structures in diamond thin films.

  16. The nanostructure problem

    SciTech Connect

    Billinge, S.

    2010-03-22

    Diffraction techniques are making progress in tackling the difficult problem of solving the structures of nanoparticles and nanoscale materials. The great gift of x-ray crystallography has made us almost complacent in our ability to locate the three-dimensional coordinates of atoms in a crystal with a precision of around 10{sup -4} nm. However, the powerful methods of crystallography break down for structures in which order only extends over a few nanometers. In fact, as we near the one hundred year mark since the birth of crystallography, we face a resilient frontier in condensed matter physics: our inability to routinely and robustly determine the structure of complex nanostructured and amorphous materials. Knowing the structure and arrangement of atoms in a solid is so fundamental to understanding its properties that the topic routinely occupies the early chapters of every solid-state physics textbook. Yet what has become clear with the emergence of nanotechnology is that diffraction data alone may not be enough to uniquely solve the structure of nanomaterials. As part of a growing effort to incorporate the results of other techniques to constrain x-ray refinements - a method called 'complex modeling' which is a simple but elegant approach for combining information from spectroscopy with diffraction data to solve the structure of several amorphous and nanostructured materials. Crystallography just works, so we rarely question how and why this is so, yet understanding the physics of diffraction can be very helpful as we consider the nanostructure problem. The relationship between the electron density distribution in three dimensions (i.e., the crystal structure) and an x-ray diffraction pattern is well established: the measured intensity distribution in reciprocal space is the square of the Fourier transform of the autocorrelation function <{rho}(r){rho}(r+r')> of the electron density distribution {rho}(r). The fact that we get the autocorrelation function

  17. Ultrahard magnetic nanostructures

    SciTech Connect

    Sahota, PK; Liu, Y; Skomski, R; Manchanda, P; Zhang, R; Franchin, M; Fangohr, H; Hadjipanayis, GC; Kashyap, A; Sellmyer, DJ

    2012-04-01

    The performance of hard-magnetic nanostructures is investigated by analyzing the size and geometry dependence of thin-film hysteresis loops. Compared to bulk magnets, weight and volume are much less important, but we find that the energy product remains the main figure of merit down to very small features sizes. However, hysteresis loops are much easier to control on small length scales, as epitomized by Fe-Co-Pt thin films with magnetizations of up to 1.78 T and coercivities of up to 2.52 T. Our numerical and analytical calculations show that the feature size and geometry have a big effect on the hysteresis loop. Layered soft regions, especially if they have a free surface, are more harmful to coercivity and energy product than spherical inclusions. In hard-soft nanocomposites, an additional complication is provided by the physical properties of the hard phases. For a given soft phase, the performance of a hard-soft composite is determined by the parameter (M-s - M-h)/K-h. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679453

  18. Ultrahard magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Sahota, P. K.; Liu, Y.; Skomski, R.; Manchanda, P.; Zhang, R.; Franchin, M.; Fangohr, H.; Hadjipanayis, G. C.; Kashyap, A.; Sellmyer, D. J.

    2012-04-01

    The performance of hard-magnetic nanostructures is investigated by analyzing the size and geometry dependence of thin-film hysteresis loops. Compared to bulk magnets, weight and volume are much less important, but we find that the energy product remains the main figure of merit down to very small features sizes. However, hysteresis loops are much easier to control on small length scales, as epitomized by Fe-Co-Pt thin films with magnetizations of up to 1.78 T and coercivities of up to 2.52 T. Our numerical and analytical calculations show that the feature size and geometry have a big effect on the hysteresis loop. Layered soft regions, especially if they have a free surface, are more harmful to coercivity and energy product than spherical inclusions. In hard-soft nanocomposites, an additional complication is provided by the physical properties of the hard phases. For a given soft phase, the performance of a hard-soft composite is determined by the parameter (Ms - Mh)/Kh.

  19. Optics of anisotropic nanostructures

    NASA Astrophysics Data System (ADS)

    Rokushima, Katsu; Antoš, Roman; Mistrík, Jan; Višňovský, Štefan; Yamaguchi, Tomuo

    2006-07-01

    The analytical formalism of Rokushima and Yamakita [J. Opt. Soc. Am. 73, 901-908 (1983)] treating the Fraunhofer diffraction in planar multilayered anisotropic gratings proved to be a useful introduction to new fundamental and practical situations encountered in laterally structured periodic (both isotropic and anisotropic) multilayer media. These are employed in the spectroscopic ellipsometry for modeling surface roughness and in-depth profiles, as well as in the design of various frequency-selective elements including photonic crystals. The subject forms the basis for the solution of inverse problems in scatterometry of periodic nanostructures including magnetic and magneto-optic recording media. It has no principal limitations as for the frequencies and period to radiation wavelength ratios and may include matter wave diffraction. The aim of the paper is to make this formalism easily accessible to a broader community of students and non-specialists. Many aspects of traditional electromagnetic optics are covered as special cases from a modern and more general point of view, e.g., plane wave propagation in isotropic media, reflection and refraction at interfaces, Fabry-Perot resonator, optics of thin films and multilayers, slab dielectric waveguides, crystal optics, acousto-, electro-, and magneto-optics, diffraction gratings, etc. The formalism is illustrated on a model simulating the diffraction on a ferromagnetic wire grating.

  20. Gold-nickel-titanium brazing alloy

    DOEpatents

    Mizuhara, Howard

    1995-01-03

    A brazing alloy in accordance with this invention has the following composition, by weight: 91 to 99 gold, 0.5 to 7% nickel; 0.10 to 2% titanium. Alternatively, with palladium present, the composition is as follows, by weight: 83 to 96% gold; 3 to 10% palladium; 0.5 to 5% nickel; 0.10 to 2% titanium.

  1. Gold-nickel-titanium brazing alloy

    DOEpatents

    Mizuhara, Howard

    1990-07-03

    A brazing alloy in accordance with this invention has the following composition, by weight: 91 to 99% gold, 0.5 to 7% nickel; 0.10 to 2% titanium. Alternatively, with palladium present, the composition is as follows, by weight: 83 to 96% gold; 3 to 10% palladium; 0.5 to 5% nickel; 0.10 to 2% titanium.

  2. Bonding titanium to Rene 41 alloy

    NASA Technical Reports Server (NTRS)

    Scott, R. W.

    1972-01-01

    Pair of intermediate materials joined by electron beam welding method welds titanium to Rene 41 alloy. Bond is necessary for combining into one structure high strength-to-density ratio titanium fan blades and temperature resistant nickel-base alloy turbine-buckets in VTOL aircraft lift-fan rotor.

  3. [Dental welding titanium and its clinical usage].

    PubMed

    Li, H; Xiao, M; Zhao, Y

    1998-09-01

    Due to its excellent biocompatibility, desirable chemical and mechanical properties, Titanium has been used for implant denture, RPD and FPD, where welding techniques were indispensable. This paper introduces 5 useful modern ways to weld Titanium and their clinical usage. They are: laser, plasma welding, TIG, infraned brazing and Hruska electrowelding. PMID:12553259

  4. Fungal leaching of titanium from rock.

    NASA Technical Reports Server (NTRS)

    Silverman, M. P.; Munoz, E. F.

    1971-01-01

    Penicillium simplicissimum is found to solubilize up to 80% of the titanium in granitic rocks but less than 2% of the titanium in basaltic rocks. These findings were made in investigating the interactions of microorganisms with rocks and minerals of the biosphere in studies aimed at developing experiments for the detection of extraterrestrial life.

  5. Titanium carbon nitride coating. Final report

    SciTech Connect

    Nance, S.D.

    1992-04-01

    The purpose of this investigation was to determine the advantages of titanium carbon nitride (TiCN) coated tools. Cutting tests were conducted comparing TiCN coating directly against titanium nitride (TiN) coated and uncoated T-15 CPM end mills.

  6. Titanium carbide bipolar plate for electrochemical devices

    DOEpatents

    LaConti, Anthony B.; Griffith, Arthur E.; Cropley, Cecelia C.; Kosek, John A.

    2000-07-04

    A corrosion resistant, electrically conductive, non-porous bipolar plate is made from titanium carbide for use in an eletrochemical device. The process involves blending titanium carbide powder with a suitable binder material, and molding the mixture, at an elevated temperature and pressure.

  7. Mineral resource of the month: titanium

    USGS Publications Warehouse

    Gambogi, Joseph

    2011-01-01

    Titanium is hip - at least when it comes to airplanes and jewelry. Known for its high strength-to weight ratio and its resistance to corrosion, titanium and its alloys can also be found in everything from knee replacements to eyeglass frames to baseball bats to fighter planes.

  8. Generation of acoustic waves by focused infrared neodymium-laser radiation

    NASA Astrophysics Data System (ADS)

    Ward, Barry

    1991-02-01

    When the radiation from a sufficiently powerful pulsed laser is focused into the transparent gaseous, liquid or solid media, dielectric breakdown may occur around the beam waist giving rise to a short-lived high-temperature plasma which quickly heats the surrounding material. As a consequence of various energy-coupling mechanisms, this phenomenon causes the emission of one or more high-frequency ultrasonic acoustic waves whose speeds of propagation are dependent upon the physical properties of the host medium. In the high-speed photographic studies described, the 1.06 micron near-infrared radiation from an 8-ns, 10-mJ Q-switched Nd:YAG laser is focused in or onto a variety of fluid and solid materials. The rapid variations in density around the resulting plasma events are visualized using a Mach-Zehnder interferometer with a sub-nanosecond dye-laser light source and a video-imaging system. Calculations of the corresponding transient pressure distributions are then enacted from the digitally-recorded interferograms using a semi-automatic procedure under the control of a personal computer. Measurements of position, displacement, and velocity are also carried out using the same optical apparatus in schlieren and focused shadowgraph high-speed photographic measurements. The experimental work outlined in the following chapters is divided into three broad fields of interest. In the first of these, a study of the laser-generation of spherical shock waves in atmospheric air is carried out. In the second, the neodymium-laser beam is focused onto different solid-fluid interfaces resulting in the formation of bulk longitudinal and shear waves and surface acoustic waves. The interactions of these waves with various obstacles and defects are investigated with reference to their application to non-destructive testing. In the third and most important field, a detailed study of the dynamics of laser-induced cavitation bubbles in water is carried out. With regard to the associated

  9. Rare earth elements and neodymium isotopes in world river sediments revisited

    NASA Astrophysics Data System (ADS)

    Bayon, G.; Toucanne, S.; Skonieczny, C.; André, L.; Bermell, S.; Cheron, S.; Dennielou, B.; Etoubleau, J.; Freslon, N.; Gauchery, T.; Germain, Y.; Jorry, S. J.; Ménot, G.; Monin, L.; Ponzevera, E.; Rouget, M.-L.; Tachikawa, K.; Barrat, J. A.

    2015-12-01

    Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ΔεNd(clay-silt) < |1|. A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts

  10. A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Piotrowski, Alexander M.; Galy, Albert; McCave, I. Nicholas

    2012-08-01

    The use of neodymium (Nd) isotopes to reconstruct past water mass mixing relies upon the quasi-conservative behaviour of this tracer, whereas recent studies in the modern oceans have suggested that boundary exchange, involving the addition of Nd from ocean margin sediments, may be an important process in the Nd cycle. Here we suggest that the relative importance of water mass advection versus boundary exchange can be assessed where the deep western boundary current in the Indian Ocean flows past the Madagascan continental margin; a potential source of highly unradiogenic Nd. Foraminiferal coatings and bulk sediment reductive leachates are used to reconstruct bottom water Nd isotopic composition (εNd) in 8 Holocene age coretops, with excellent agreement between the two methods. These data record spatial variability of ∼4 εNd units along the flow path of Circumpolar Deep Water; εNd≈-8.8 in the deep southern inflow upstream of Madagascar, which evolves towards εNd≈-11.5 offshore northern Madagascar, whereas εNd≈-7.3 where deep water re-circulates in the eastern Mascarene Basin. This variability is attributed to boundary exchange and, together with measurements of detrital sediment εNd, an isotope mass balance suggests a deep water residence time for Nd of ≤400 yr along the Madagascan margin. Considering deglacial changes, a core in the deep inflow upstream of Madagascar records εNd changes that agree with previous reconstructions of the Circumpolar Deep Water composition in the Southern Ocean, consistent with a control by water mass advection and perhaps indicating a longer residence time for Nd in the open ocean away from local sediment inputs. In contrast, sites along the Madagascan margin record offset εNd values and reduced glacial-interglacial variability, underlining the importance of detecting boundary exchange before inferring water mass source changes from Nd isotope records. The extent of Madagascan boundary exchange appears to be unchanged

  11. Formation, structural and optical characterization of neodymium doped-zinc soda lime silica based glass

    NASA Astrophysics Data System (ADS)

    Zamratul, M. I. M.; Zaidan, A. W.; Khamirul, A. M.; Nurzilla, M.; Halim, S. A.

    New glass system of neodymium - doped zinc soda lime silica glass has been synthesized for the first time by melt-quenching of glass waste soda lime silica (SLS) with zinc oxide (ZnO) as precursor glass and Nd2O3 as dopant. In order to examine the effect of Nd3+ on the structural and optical properties, the prepared sample of structure [(ZnO)0.5(SLS)0.5](Nd2O3)x (x = 0, 1, 2, 3, 4 and 5 wt%) was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy (UV-Vis) and the photoluminescence (PL). XRD pattern justifies the amorphous nature of synthesized glasses. FTIR spectroscopy has been used to observe the structural evolution of ZnO4 and SiO4 groups. The UV-Vis-NIR absorption spectra reveals seven peaks centered at excitation of electron from ground state 4I9/2 to 4D3/2 + 4D5/2 (∼360 nm), 2G9/2 + 2D3/2 + 2P3/2(∼470 nm), 2K13/2 + 4G7/2 + 4G9/2 (∼523 nm), 4G5/2 + 2G7/2 (∼583 nm), 4F9/2 (∼678 nm), 4S3/2 + 4F7/2 (∼748 nm) and 4F5/2 + 2H9/2 (∼801 nm). PL spectra under the excitation of 800 nm display four emission bands centered at 531 nm, 598 nm, 637 nm and 671 nm corresponding to 4G7/2 → 4I9/2, (4G7/2 → 4I11/2, 4G5/2 → 4I9/2), (4G5/2 → 4I11/2) and (4G7/2 → 4I13/2, 4G5/2 → 4I11/2) respectively.

  12. Coupled isotopic systematics of surface cerium and neodymium in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Tazoe, H.; Obata, H.; Gamo, T.

    2011-04-01

    Trace metals are known to be essential elements in marine ecosystems. Radiogenic isotopes of neodymium (Nd) have been used as tracers in many recent oceanic trace metal studies, although, among rare earth elements, cerium (Ce) isotopes might be an interesting complementary tracer for particle reactive and lithogenic metals such as manganese. This study determined the 138Ce/142Ce ratios in surface waters of the Pacific Ocean and its surrounding marginal seas: the Sulu Sea, the South China Sea, the East China Sea, and the South Australian Basin. The 138Ce/142Ce and 143Nd/144Nd data are discussed in terms of the sources of rare earth elements and elemental fractionation between Ce and Nd in the marine environment. In the Western North Pacific Central Water, East China Sea, and South China Sea, isotopic compositions of Ce (ɛCe = +0.7 to 1.4) are most affected by radiogenic Ce of continental origin. In contrast, less radiogenic isotopic compositions of Ce (ɛCe = -0.4 to +0.3) in the Pacific Equatorial Water were observed locally near volcanic islands such as New Guinea Island, suggesting the influence of mantle-derived Ce. Compared with Nd, the isotopic composition of Ce showed a heterogeneous distribution in a given surface water mass, reflecting the importance of local sources. Variations of isotopic compositions and concentrations of Ce in the western Equatorial Pacific and the East China Sea suggest that lithogenic Ce is supplied and scavenged by particle-dissolved interaction near the margins. Radiogenic Ce in the Western North Pacific Central Water, which is more continental-like than Nd isotopes, suggests direct input by atmospheric dust into the North Pacific Ocean. The isotopic distribution of Ce is sensitive to aeolian supply to the surface waters of the open ocean. This unique feature indicates that the 138Ce/142Ce ratio can be a useful chemical tracer for lithogenic trace elements such as iron and manganese, which have short oceanic residence time.

  13. Extraction of seawater-derived neodymium from different phases of deep sea sediments by selective leaching

    NASA Astrophysics Data System (ADS)

    Blaser, P.; Lippold, J. A.; Frank, N.; Gutjahr, M.; Böhm, E.

    2014-12-01

    In order to deduce reliable information about the interaction of the oceans with the climate system as a whole in the past, the reconstruction of water mass circulation is crucial. The analysis of seawater-derived neodymium isotopes (143Nd/144Nd, expressed as ɛNd) in marine sediments provides a unique proxy for deep water provenance in particular in the Atlantic [1]. The ɛNd signature and thus the mixing proportion of the local bottom water masses is archived in authigenic phases in the sediment. Obtaining seawater ɛNd from authigenic accretions bound to foraminiferal tests has lately become the preferred since most reliable method [2]. Attempts have also been made to extract the Nd-rich authigenic metal fraction by leaching it off the bulk sediment and thereby use this proxy with less effort, in the highest possible resolution and in sediments where foraminifera are not sufficiently present. However, often other sedimentary components are also leached in the process and contaminate the extracted Nd [3,4]. In this project several core-top and older sediments across the Atlantic have been leached in ten consecutive steps with either dilute buffered acetic acid or an acid-reductive solution. The leachates were analysed on their elemental and Nd isotope compositions, as well as rare earth element (REE) distributions. By graduating the total leaching procedure into smaller stages the results display which processes take place in the course of sediment leaching in the laboratory and which components of the sediment are most reactive. Thus, they help to better evaluate the quality of sediment leaches for ɛNd analysis. Clearly, organic calcite acts as a fast reacting buffer and at the point where its amount is sufficiently reduced the leaching of other components commences and the Nd concentration peaks. Corruption of the extracted ɛNd signal by non-authigenic sources in many cases occured early in the leaching sequence, indicating that only very cautious leaching

  14. Europium, Samarium, and Neodymium Isotopic Fractions in Metal-Poor Stars

    NASA Astrophysics Data System (ADS)

    Roederer, Ian U.; Lawler, James E.; Sneden, Christopher; Cowan, John J.; Sobeck, Jennifer S.; Pilachowski, Catherine A.

    2008-03-01

    We have derived isotopic fractions of europium (Eu), samarium (Sm), and neodymium (Nd) in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions were measured from new very high resolution (R~120,000), high signal-to-noise (S/N~160-1000) spectra obtained with the 2dCoudé spectrograph of McDonald Observatory's 2.7 m Smith telescope. Synthetic spectra were generated using recent high-precision laboratory measurements of hyperfine and isotopic subcomponents of several transitions of these elements and matched quantitatively to the observed spectra. We interpret our isotopic fractions by the nucleosynthesis predictions of the stellar model, which models s-process nucleosynthesis in the physical conditions expected in a low-mass, thermally-pulsing star on the AGB, and the classical method, which assumes that s-process nucleosynthesis can be approximated by a steady neutron flux impinging upon Fe-peak seed nuclei. These two approaches predict the relative contributions to the Solar System n-capture abundances from the s- and r-processes and, by extension, the relative contributions of these two process to material in metal-poor stars. Our Eu isotopic fraction in HD 175305 is consistent with an r-process origin by the classical method and is consistent with both an r-process and s-process origin by the stellar model. Our Sm isotopic fraction in HD 175305 is consistent with a predominantly r-process origin by both methods, and our Sm isotopic fraction in HD 196944 is consistent with a pure s-process origin by both methods as well. Our Nd isotopic fractions in both stars are consistent with either r-process and s-process origins by both methods. The Eu and Sm isotopic fraction estimates argue for an r-process origin for the rare-earth elements in HD 175305 and an s-process origin for them in HD 196944, in excellent agreement with previous studies of the elemental abundance distributions in these stars. This study for the

  15. Hafnium and neodymium isotope composition of seawater and filtered particles from the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Frank, M.; Haley, B. A.; Rickli, J.; Venchiarutti, C.

    2009-12-01

    Radiogenic hafnium (Hf) and neodymium (Nd) isotopes have been used as tracers for past continental weathering regimes and ocean circulation. To date, however, there are only very few data available on dissolved Hf isotope compositions in present-day seawater and there is a complete lack of particulate data. During expedition ANTXXIV/3 (February to April 2008) we collected particulate samples (> 0.8 µm), which were obtained by filtrations of 270-700 liters of water. The samples were separated from the filters, completely dissolved, and purified for Nd and Hf isotope determination by TIMS and MC-ICPMS, respectively. In addition, we collected filtered (0.45 µm) seawater samples (20-120 liters) to determine the dissolved isotopic composition of Hf and Nd. The Hf isotope composition of the particulate fraction in the Drake Passage ranged from 0 to -28 ɛHf and is thus similar to that observed in core top sediments from the entire Southern Ocean in a previous study. The most unradiogenic and isotopically homogenous Hf isotope compositions in our study were found near the Antarctic Peninsula. Most of the stations north of the Southern Antarctic Circumpolar Front (SACC) show a large variation in ɛHf between 0 and -23 within the water column of one station and between the stations. The locations at which these Hf isotope compositions were measured are mostly far away from the potential source areas. Nd, in contrast, was nearly absent throughout the entire sample set and the only measurable ɛNd data ranged from 0 to -7, which is in good agreement with the sediment data in that area. The dissolved seawater isotopic compositions of both Hf and Nd show only minor variance (ɛHf = 4.2 to 4.7 and ɛNd = -8.8 to -7.6, respectively). These patterns in Hf isotopes and the nearly complete absence of Nd indicates that the particulate fraction does not contain a lot of terrigeneous material but is almost entirely dominated by biogenic opal. The homogenous and relatively radiogenic

  16. Osteointegration of PLGA implants with nanostructured or microsized β-TCP particles in a minipig model.

    PubMed

    Kulkova, Julia; Moritz, Niko; Suokas, Esa O; Strandberg, Niko; Leino, Kari A; Laitio, Timo T; Aro, Hannu T

    2014-12-01

    Bioresorbable suture anchors and interference screws have certain benefits over equivalent titanium-alloy implants. However, there is a need for compositional improvement of currently used bioresorbable implants. We hypothesized that implants made of poly(l-lactide-co-glycolide) (PLGA) compounded with nanostructured particles of beta-tricalcium phosphate (β-TCP) would induce stronger osteointegration than implants made of PLGA compounded with microsized β-TCP particles. The experimental nanostructured self-reinforced PLGA (85L:15G)/β-TCP composite was made by high-energy ball-milling. Self-reinforced microsized PLGA (95L:5G)/β-TCP composite was prepared by melt-compounding. The composites were characterized by gas chromatography, Ubbelohde viscometry, scanning electron microscopy, laser diffractometry, and standard mechanical tests. Four groups of implants were prepared for the controlled laboratory study employing a minipig animal model. Implants in the first two groups were prepared from nanostructured and microsized PLGA/β-TCP composites respectively. Microroughened titanium-alloy (Ti6Al4V) implants served as positive intra-animal control, and pure PLGA implants as negative control. Cone-shaped implants were inserted in a random order unilaterally in the anterior cortex of the femoral shaft. Eight weeks after surgery, the mechanical strength of osteointegration of the implants was measured by a push-out test. The quality of new bone surrounding the implant was assessed by microcomputed tomography and histology. Implants made of nanostructured PLGA/β-TCP composite did not show improved mechanical osteointegration compared with the implants made of microsized PLGA/β-TCP composite. In the intra-animal comparison, the push-out force of two PLGA/β-TCP composites was 35-60% of that obtained with Ti6Al4V implants. The implant materials did not result in distinct differences in quality of new bone surrounding the implant. PMID:25241283

  17. Fabrication of nanostructure by physical vapor deposition with glancing angle deposition technique and its applications

    NASA Astrophysics Data System (ADS)

    Horprathum, M.; Eiamchai, P.; Kaewkhao, J.; Chananonnawathorn, C.; Patthanasettakul, V.; Limwichean, S.; Nuntawong, N.; Chindaudom, P.

    2014-09-01

    A nanostructural thin film is one of the highly exploiting research areas particularly in applications in sensor, photocatalytic, and solar-cell technologies. In the past two decades, the integration of glancing-angle deposition (GLAD) technique to physical vapor deposition (PVD) process has gained significant attention for well-controlled multidimensional nanomorphologies because of fast, simple, cost-effective, and mass-production capability. The performance and functional properties of the coated thin films generally depend upon their nanostructural compositions, i.e., large aspect ratio, controllable porosity, and shape. Such structural platforms make the fabricated thin films very practical for several realistic applications. We therefore present morphological and nanostructural properties of various deposited materials, which included metals, i.e., silver (Ag), and oxide compounds, i.e., tungsten oxide (WO3), titanium dioxide (TiO2), and indium tin oxide (ITO). Different PVD techniques based on DC magnetron sputtering and electron-beam evaporation, both with the integrated GLAD component, were discussed. We further explore engineered nanostructures which enable controls of optical, electrical, and mechanical properties. These improvements led to several practical applications in surface-enhanced Raman, smart windows, gas sensors, self-cleaning materials and transparent conductive oxides (TCO).

  18. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    SciTech Connect

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-07

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst.

  19. Fabrication of nanostructure by physical vapor deposition with glancing angle deposition technique and its applications

    SciTech Connect

    Horprathum, M. Eiamchai, P. Patthanasettakul, V.; Limwichean, S.; Nuntawong, N.; Chindaudom, P.; Kaewkhao, J.; Chananonnawathorn, C.

    2014-09-25

    A nanostructural thin film is one of the highly exploiting research areas particularly in applications in sensor, photocatalytic, and solar-cell technologies. In the past two decades, the integration of glancing-angle deposition (GLAD) technique to physical vapor deposition (PVD) process has gained significant attention for well-controlled multidimensional nanomorphologies because of fast, simple, cost-effective, and mass-production capability. The performance and functional properties of the coated thin films generally depend upon their nanostructural compositions, i.e., large aspect ratio, controllable porosity, and shape. Such structural platforms make the fabricated thin films very practical for several realistic applications. We therefore present morphological and nanostructural properties of various deposited materials, which included metals, i.e., silver (Ag), and oxide compounds, i.e., tungsten oxide (WO{sub 3}), titanium dioxide (TiO{sub 2}), and indium tin oxide (ITO). Different PVD techniques based on DC magnetron sputtering and electron-beam evaporation, both with the integrated GLAD component, were discussed. We further explore engineered nanostructures which enable controls of optical, electrical, and mechanical properties. These improvements led to several practical applications in surface-enhanced Raman, smart windows, gas sensors, self-cleaning materials and transparent conductive oxides (TCO)

  20. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    Sputtered coatings of the refractory metal carbides are of great interest for applications where hard wear-resistant materials are desired. The usefulness of sputtered refractory carbides is often limited, in practice, by spalling or interfacial separation. In this work improvements in the adherence of refractory carbides on iron, nickel and titanium based alloys were obtained by using oxidation, reactive sputtering or sputtered interlayers to alter the coating-substrate interfacial region. X-ray photoelectron spectroscopy and argon ion etching were used to characterize the interfacial regions, and an attempt was made to correlate adherence as measured in wear tests with the chemical nature of the interface.

  1. Weld-brazing of titanium

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1974-01-01

    A joining process, designated weld-brazing, which combines resistance spotwelding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and align the parts and to establish a suitable faying surface gap for brazing; it contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vacuum furnace and in a retort containing an inert gas environment.

  2. Harms titanium mesh cage fracture

    PubMed Central

    Klezl, Zdenek; Bookland, Markus J.; Wolinsky, Jean-Paul; Rezek, Zdenek; Gokaslan, Ziya L.

    2007-01-01

    Interbody fusion has become a mainstay of surgical management for lumbar fractures, tumors, spondylosis, spondylolisthesis and deformities. Over the years, it has undergone a number of metamorphoses, as novel instrumentation and approaches have arisen to reduce complications and enhance outcomes. Interbody fusion procedures are common and successful, complications are rare and most often do not involve the interbody device itself. We present here a patient who underwent an anterior L4 corpectomy with Harms cage placement and who later developed a fracture of the lumbar titanium mesh cage (TMC). This report details the presentation and management of this rare complication, as well as discusses the biomechanics underlying this rare instrumentation failure. PMID:17497187

  3. The present status of dental titanium casting

    NASA Astrophysics Data System (ADS)

    Okabe, Toru; Ohkubo, Chikahiro; Watanabe, Ikuya; Okuno, Osamu; Takada, Yukyo

    1998-09-01

    Experimentation in all aspects of titanium casting at universities and industries throughout the world for the last 20 years has made titanium and titanium-alloy casting nearly feasible for fabricating sound cast dental prostheses, including crowns, inlays, and partial and complete dentures. Titanium casting in dentistry has now almost reached the stage where it can seriously be considered as a new method to compete with dental casting using conventional noble and base-metal alloys. More than anything else, the strength of titanium’s appeal lies in its excellent biocompatibility, coupled with its comparatively low price and abundant supply. Research efforts to overcome some problems associated with this method, including studies on the development of new titanium alloys suitable for dental use, will continue at many research sites internationally.

  4. Stress-corrosion cracking of titanium alloys.

    NASA Technical Reports Server (NTRS)

    Blackburn, M. J.; Feeney, J. A.; Beck, T. R.

    1973-01-01

    In the light of research material published up to May 1970, the current understanding of the experimental variables involved in the stress-corrosion cracking (SCC) behavior of titanium and its alloys is reviewed. Following a brief summary of the metallurgy and electrochemistry of titanium alloys, the mechanical, electrochemical, and metallurgical parameters influencing SCC behavior are explored with emphasis on crack growth kinetics. Macro- and microfeatures of fractures are examined, and it is shown that many transgranular SCC failures exhibit morphological and crystallographic features similar to mechanical cleavage failures. Current SCC models are reviewed with respect to their ability to explain the observed SCC behavior of titanium and its alloys. Possible methods for eliminating or minimizing stress corrosion hazards in titanium or titanium alloy components are described.

  5. Microstructural investigation of thermally treated titanium subhydrides

    SciTech Connect

    Wang, P.S.; Wittberg, T.N.; Wolf, J.D.

    1984-09-05

    The ignition of titanium subhydride/potassium perchlorate pyrotechnic blends is influenced by the diffusion of oxygen into the titanium subhydride fuel. The following work is a preliminary study of the microstructural changes that take place during the dehydriding of titanium subhydride. Samples of TiH/sub 1/ /sub 63/ were dehydrided at temperatures between 625 and 775/sup 0/C. In the partially dehydrided samples, evidence of three different phases - ..cap alpha.. Ti (hexagonal), ..beta.. Ti (cubic), and ..gamma.. TiH/sub 2/ (cubic) - was seen. Microstructural examination of a TiH/sub 1/ /sub 15/ sample that had a layered structure is also reported. A furnace constructed for hydriding titanium foils is also described. Titanium subhydride foils having the stoichiometries TiH/sub 1/ /sub 53/ and TiH/sub 0/ /sub 87/ were prepared using this furnace.

  6. Surface characteristics of and in vitro behavior of osteoblast-like cells on titanium with nanotopography prepared by high-energy shot peening

    PubMed Central

    Deng, Zhennan; Yin, Baodi; Li, Weihong; Liu, Jinsong; Yang, Jingyuan; Zheng, Tieli; Zhang, Dafeng; Yu, Haiyang; Liu, Xiaoguang; Ma, Jianfeng

    2014-01-01

    Background and methods Commercial pure titanium with nanotopography was prepared via a high-energy shot-peening (HESP) technique. The surface characteristics were evaluated, and the preliminary cell responses to the nanotopographical surface were investigated. Results The nanotopographical surface layer on titanium was successfully processed by HESP. The average nanoscale grains were approximately 60 nm in diameter and they were nonhomogeneously distributed on the surface. MG-63 cells with an osteogenic phenotype were well adhered and well spread on the nanostructured surface. Compared to the original polished control, the nanotopographical surface highly improved the adhesion, viability, and differentiation of MG-63 cells. Conclusion Titanium with nanotopography achieved by HESP has good cytocompatibility and shows promise for dental implant applications. PMID:25489244

  7. From the subtropics to the equator in the Southwest Pacific: Continental material fluxes quantified using neodymium data along modeled thermocline water pathways

    NASA Astrophysics Data System (ADS)

    Grenier, Mélanie; Jeandel, Catherine; Cravatte, Sophie

    2014-06-01

    The southwestern tropical Pacific, part of a major pathway for waters feeding the Equatorial Undercurrent, is a region of important geochemical enrichment through land-ocean boundary exchange. Here we develop an original method based on the coupling between dynamical modeling and geochemical tracer data to identify regions of enrichment along the water pathways from the subtropics to the equator, and to allow a refined quantification of continental material fluxes. Neodymium data are interpreted with the help of modeled Lagrangian trajectories of an Ocean General Circulation Model. We reveal that upper and lower thermocline waters have different pathways together with different geochemical evolutions. The upper thermocline waters entering the Solomon Sea mainly originate from the central subtropical gyre, enter the Coral Sea in the North Vanuatu Jet and likely receive radiogenic neodymium from the basaltic island margins encountered along their route. The lower thermocline waters entering the Solomon Sea mainly originate from northeast of New Zealand and enter the Coral Sea in the North Caledonian Jet. Depletion of their neodymium content likely occurs when flowing along the Australian and Papua coasts. Downstream from the Solomon Sea, waters flowing along the Papua New Guinea margins near the Sepik river mouth become surprisingly depleted in their neodymium content in the upper thermocline while enriched in the lower thermocline. This coupled approach is proposed as strong support to interpret the origin of the equatorial Pacific natural fertilization through a better understanding of the circulation, important objectives of the international GEOTRACES and SPICE programs, respectively.

  8. Key Physical Mechanisms in Nanostructured Solar Cells

    SciTech Connect

    Dr Stephan Bremner

    2010-07-21

    The objective of the project was to study both theoretically and experimentally the excitation, recombination and transport properties required for nanostructured solar cells to deliver energy conversion efficiencies well in excess of conventional limits. These objectives were met by concentrating on three key areas, namely, investigation of physical mechanisms present in nanostructured solar cells, characterization of loss mechanisms in nanostructured solar cells and determining the properties required of nanostructured solar cells in order to achieve high efficiency and the design implications.

  9. Gallium nitride nanostructures: Synthesis, characterization and applications

    NASA Astrophysics Data System (ADS)

    Kente, Thobeka; Mhlanga, Sabelo Dalton

    2016-06-01

    GaN nanostructures have been extensively studied due to their important properties and applications in many fields. The recent synthesis and uses of these nanostructures have been reviewed. The different synthesis methods such as catalyst-assisted and catalyst-free methods to make GaN nanostructures and different reaction conditions have been also reviewed. This review covers the synthesis, growth mechanism, crystalline structure, properties, applications, structural and optical characterization of GaN nanostructures.

  10. Corrosion behavior and mechanical properties of bioactive sol-gel coatings on titanium implants.

    PubMed

    Catauro, M; Bollino, F; Papale, F; Giovanardi, R; Veronesi, P

    2014-10-01

    Organic-inorganic hybrid coatings based on zirconia and poly (ε-caprolactone) (PCL) were prepared by means of sol-gel dip-coating technique and used to coat titanium grade 4 implants (Ti-4) in order to improve their wear and corrosion resistance. The coating chemical composition has been analysed by ATR-FTIR. The influence of the PCL amount has been investigated on the microstructure, mechanical properties of the coatings and their ability to inhibit the corrosion of titanium. SEM analysis has shown that all coatings have a nanostructured nature and that the films with high PCL content are crack-free. Mechanical properties of the coatings have been studied using scratch and nano-indentation tests. The results have shown that the Young's modulus of the coatings decreases in presence of large amounts of the organic phase, and that PCL content affects also the adhesion of the coatings to the underlying Ti-4 substrate. However, the presence of cracks on the PCL-free coatings affects severely the mechanical response of the samples at high loads. The electrochemical behavior and corrosion resistance of the coated and uncoated substrate has been investigated by polarization tests. The results have shown that both the coatings with or without PCL don't affect significantly the already excellent passivation properties of titanium. PMID:25175226

  11. Method of fabrication of anchored nanostructure materials

    DOEpatents

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2013-11-26

    Methods for fabricating anchored nanostructure materials are described. The methods include heating a nano-catalyst under a protective atmosphere to a temperature ranging from about 450.degree. C. to about 1500.degree. C. and contacting the heated nano-catalysts with an organic vapor to affix carbon nanostructures to the nano-catalysts and form the anchored nanostructure material.

  12. PREFACE: Self-organized nanostructures

    NASA Astrophysics Data System (ADS)

    Rousset, Sylvie; Ortega, Enrique

    2006-04-01

    In order to fabricate ordered arrays of nanostructures, two different strategies might be considered. The `top-down' approach consists of pushing the limit of lithography techniques down to the nanometre scale. However, beyond 10 nm lithography techniques will inevitably face major intrinsic limitations. An alternative method for elaborating ultimate-size nanostructures is based on the reverse `bottom-up' approach, i.e. building up nanostructures (and eventually assemble them to form functional circuits) from individual atoms or molecules. Scanning probe microscopies, including scanning tunnelling microscopy (STM) invented in 1982, have made it possible to create (and visualize) individual structures atom by atom. However, such individual atomic manipulation is not suitable for industrial applications. Self-assembly or self-organization of nanostructures on solid surfaces is a bottom-up approach that allows one to fabricate and assemble nanostructure arrays in a one-step process. For applications, such as high density magnetic storage, self-assembly appears to be the simplest alternative to lithography for massive, parallel fabrication of nanostructure arrays with regular sizes and spacings. These are also necessary for investigating the physical properties of individual nanostructures by means of averaging techniques, i.e. all those using light or particle beams. The state-of-the-art and the current developments in the field of self-organization and physical properties of assembled nanostructures are reviewed in this issue of Journal of Physics: Condensed Matter. The papers have been selected from among the invited and oral presentations of the recent summer workshop held in Cargese (Corsica, France, 17-23 July 2005). All authors are world-renowned in the field. The workshop has been funded by the Marie Curie Actions: Marie Curie Conferences and Training Courses series named `NanosciencesTech' supported by the VI Framework Programme of the European Community, by

  13. Interfacing nanostructures to biological cells

    DOEpatents

    Chen, Xing; Bertozzi, Carolyn R.; Zettl, Alexander K.

    2012-09-04

    Disclosed herein are methods and materials by which nanostructures such as carbon nanotubes, nanorods, etc. are bound to lectins and/or polysaccharides and prepared for administration to cells. Also disclosed are complexes comprising glycosylated nanostructures, which bind selectively to cells expressing glycosylated surface molecules recognized by the lectin. Exemplified is a complex comprising a carbon nanotube functionalized with a lipid-like alkane, linked to a polymer bearing repeated .alpha.-N-acetylgalactosamine sugar groups. This complex is shown to selectively adhere to the surface of living cells, without toxicity. In the exemplified embodiment, adherence is mediated by a multivalent lectin, which binds both to the cells and the .alpha.-N-acetylgalactosamine groups on the nanostructure.

  14. Nanostructures for protein drug delivery.

    PubMed

    Pachioni-Vasconcelos, Juliana de Almeida; Lopes, André Moreni; Apolinário, Alexsandra Conceição; Valenzuela-Oses, Johanna Karina; Costa, Juliana Souza Ribeiro; Nascimento, Laura de Oliveira; Pessoa, Adalberto; Barbosa, Leandro Ramos Souza; Rangel-Yagui, Carlota de Oliveira

    2016-02-01

    Use of nanoscale devices as carriers for drugs and imaging agents has been extensively investigated and successful examples can already be found in therapy. In parallel, recombinant DNA technology together with molecular biology has opened up numerous possibilities for the large-scale production of many proteins of pharmaceutical interest, reflecting in the exponentially growing number of drugs of biotechnological origin. When we consider protein drugs, however, there are specific criteria to take into account to select adequate nanostructured systems as drug carriers. In this review, we highlight the main features, advantages, drawbacks and recent developments of nanostructures for protein encapsulation, such as nanoemulsions, liposomes, polymersomes, single-protein nanocapsules and hydrogel nanoparticles. We also discuss the importance of nanoparticle stabilization, as well as future opportunities and challenges in nanostructures for protein drug delivery. PMID:26580477

  15. Titanium in Engine Valve Systems

    NASA Astrophysics Data System (ADS)

    Allison, J. E.; Sherman, A. M.; Bapna, M. R.

    1987-03-01

    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a twoto-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance. When properly manufactured, titanium valves have been shown to withstand very stringent durability testing, indicating the technical feasibility of this approach to fuel economy improvement.

  16. Characterisation of titanium-titanium boride composites processed by powder metallurgy techniques

    SciTech Connect

    Selva Kumar, M.; Chandrasekar, P.; Chandramohan, P.; Mohanraj, M.

    2012-11-15

    In this work, a detailed characterisation of titanium-titanium boride composites processed by three powder metallurgy techniques, namely, hot isostatic pressing, spark plasma sintering and vacuum sintering, was conducted. Two composites with different volume percents of titanium boride reinforcement were used for the investigation. One was titanium with 20% titanium boride, and the other was titanium with 40% titanium boride (by volume). Characterisation was performed using X-ray diffraction, electron probe micro analysis - energy dispersive spectroscopy and wavelength dispersive spectroscopy, image analysis and scanning electron microscopy. The characterisation results confirm the completion of the titanium boride reaction. The results reveal the presence of titanium boride reinforcement in different morphologies such as needle-shaped whiskers, short agglomerated whiskers and fine plates. The paper also discusses how mechanical properties such as microhardness, elastic modulus and Poisson's ratio are influenced by the processing techniques as well as the volume fraction of the titanium boride reinforcement. - Highlights: Black-Right-Pointing-Pointer Ti-TiB composites were processed by HIP, SPS and vacuum sintering. Black-Right-Pointing-Pointer The completion of Ti-TiB{sub 2} reaction was confirmed by XRD, SEM and EPMA studies. Black-Right-Pointing-Pointer Hardness and elastic properties of Ti-TiB composites were discussed. Black-Right-Pointing-Pointer Processing techniques were compared with respect to their microstructure.

  17. Adhesive-Bonded Tab Attaches Thermocouples to Titanium

    NASA Technical Reports Server (NTRS)

    Cook, C. F.

    1982-01-01

    Mechanical strength of titanium-alloy structures that support thermocouples is preserved by first spotwelding thermocouples to titanium tabs and then attaching tabs to titanium with a thermosetting adhesive. In contrast to spot welding, a technique previously used for thermocouples, fatigue strength of the titanium is unaffected by adhesive bonding. Technique is also gentler than soldering or attaching thermocouples with a tap screw.

  18. Nanostructured Substrates for Optical Sensing

    PubMed Central

    Kemling, Jonathan W.; Qavi, Abraham J.; Bailey, Ryan C.

    2011-01-01

    Sensors that change color have the advantages of versatility, ease of use, high sensitivity, and low cost. The recent development of optically based chemical sensing platforms has increasingly employed substrates manufactured with advanced processing or fabrication techniques to provide precise control over shape and morphology of the sensor micro- and nano-structure. New sensors have resulted with improved capabilities for a number of sensing applications, including the detection of biomolecules and environmental monitoring. This perspective focuses on recent optical sensor devices that utilize nanostructured substrates. PMID:22174955

  19. Vortex ice in nanostructured superconductors

    SciTech Connect

    Reichhardt, Charles; Reichhardt, Cynthia J; Libal, Andras J

    2008-01-01

    We demonstrate using numerical simulations of nanostructured superconductors that it is possible to realize vortex ice states that are analogous to square and kagome ice. The system can be brought into a state that obeys either global or local ice rules by applying an external current according to an annealing protocol. We explore the breakdown of the ice rules due to disorder in the nanostructure array and show that in square ice, topological defects appear along grain boundaries, while in kagome ice, individual defects appear. We argue that the vortex system offers significant advantages over other artificial ice systems.

  20. Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: A radiocarbon and neodymium isotope perspective

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Crocket, Kirsty C.; Flierdt, Tina; Robinson, Laura F.; Adkins, Jess F.

    2014-11-01

    The last deglaciation was characterized by a series of millennial-scale climate events that have been linked to deep ocean variability. While often implied in interpretations, few direct constraints exist on circulation changes at mid-depths. Here we provide new constraints on the variability of deglacial mid-depth circulation using combined radiocarbon and neodymium isotopes in 24 North Atlantic deep-sea corals. Their aragonite skeletons have been dated by uranium-series, providing absolute ages and the resolution to record centennial-scale changes, while transects spanning the lifetime of a single coral allow subcentennial tracer reconstruction. Our results reveal that rapid fluctuations of water mass sourcing and radiocarbon affected the mid-depth water column (1.7-2.5 km) on timescales of less than 100 years during the latter half of Heinrich Stadial 1. The neodymium isotopic variability (-14.5 to -11.0) ranges from the composition of the modern northern-sourced waters towards more radiogenic compositions, suggesting the presence of a greater southern-sourced component at some times. However, in detail, simple two-component mixing between well-ventilated northern-sourced and radiocarbon-depleted southern-sourced water masses cannot explain all our data. Instead, corals from ~15.0 ka and ~15.8 ka may record variability between southern-sourced intermediate waters and radiocarbon-depleted northern-sourced waters, unless there was a major shift in the neodymium isotopic composition of the northern end-member. In order to explain the rapid shift towards the most depleted radiocarbon values at ~15.4 ka, we suggest a different mixing scenario involving either radiocarbon-depleted deep water from the Greenland-Iceland-Norwegian Seas or a southern-sourced deep water mass. Since these mid-depth changes preceded the Bolling-Allerod warming and were apparently unaccompanied by changes in the deep Atlantic, they may indicate an important role for the intermediate ocean in

  1. Laser hydrothermal reductive ablation of titanium monoxide: Hydrated TiO particles with modified Ti/O surface

    NASA Astrophysics Data System (ADS)

    Blazevska-Gilev, Jadranka; Jandová, Věra; Kupčík, Jaroslav; Bastl, Zdeněk; Šubrt, Jan; Bezdička, Petr; Pola, Josef

    2013-01-01

    IR laser- and UV laser-induced ablation of titanium monoxide (TM) in hydrogen (50 Torr) is compared to the same process induced in vacuum and shown to result in deposition of hydrated surface modified nanostructured titanium suboxide films. Complementary analyses of the films deposited in vacuum and in hydrogen by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and electron microscopy allowed to determine different features of both films and propose a mechanism of surface modification of ejected particles, which involves hydrothermal reduction of TM and subsequent reactions of evolved water. The films exert good adhesion to metal and quartz surfaces and are hydrophobic in spite of having their surface coated with adsorbed water.

  2. Titanium (IV) sol-gel chemistry in varied gravity environments

    NASA Astrophysics Data System (ADS)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    . The test systems and experimental results obtained will be presented. 1. Okubo, T., Tsuchida, A., Okuda, T., Fujitsuna, K., Ishikawa, M., Morita, T., Tada, T. , Kinetic Analyses of Colloidal Crystallization in Microgravity -Aircraft Experiments. . Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999. 153: p. 515-524. 2. Okubo, T., Tsuchida, A., Kobayashi, K., Kuno, A., Morita, T., Fujishima, M., Kohno, Y., Kinetic Study of the Formation Reaction of Colloidal Silica Spheres in Microgravity Using Aircraft. Colloid Polymer Science, 1999. 277(5): p. 474-478. 3. Pienaar, C.L., Chiffoleau, G. J. A., Follens, L. R. A., Martens, J. A., Kirschhock, C. E. A., Steinberg, T. A., Effect of Gravity on the Gelation of Silica Sols. Chem. Mater., 2007. 19(4): p. 660-664. 4. Smith, D.D., et al., Effect of Microgravity on the Growth of Silica Nanostructures. Langmuir, 2000. 16(26): p. 10055-10060. 5. Zhang, X., Johnson, D.P., Manerbino, A.R., Moore, J.J., Schowengerdt, F. , Recent Mi-crogravity Results in the Synthesis of Porous Materials. AIP Conference Proceedings (Space Technology and Applications International Forum-1999, Pt. 1), 1999. 458: p. 88-93. 6. Dunbar, P.B., Bendzko, N.J.,, 1H and 13C NMR observation of the reaction of acetic acid with titanium isopropoxide. Materials Chemistry and Physics, 1999. 59: p. 26-35. 7. Krunks, M., Oja, I., T˜nsuaadu, K., Es-Souni, M., Gruselle, M., Niinistü,. L, Thermoanalytical study of acetylacetonate-modified titanium (iv) isopropoxide as precursor for TiO2 films. Journal of Thermal Analysis and Calorimetry, 2005: p. 483-488. 8. Moran, P.D., Bowmaker, G. A., Cooney, R. P., Vibrational Spectra and Molecular Associa-tion of Titanium Tetraisopropoxide. Inorg. Chem., 1998. 37(1): p. 2741-2748. 9. Somogyvari, A., Serpone, N.,, Evidence for five-coordination in titanium(1V) complexes. A nuclear magnetic resonance investigation. Canadian Journal of Chemistry, 1977. 56: p. 316-319.

  3. Titanium Coating of the Boston Keratoprosthesis

    PubMed Central

    Salvador-Culla, Borja; Jeong, Kyung Jae; Kolovou, Paraskevi Evi; Chiang, Homer H.; Chodosh, James; Dohlman, Claes H.; Kohane, Daniel S.

    2016-01-01

    Purpose We tested the feasibility of using titanium to enhance adhesion of the Boston Keratoprosthesis (B-KPro), ultimately to decrease the risk of implant-associated complications. Methods Cylindrical rods were made of poly(methyl methacrylate) (PMMA), PMMA coated with titanium dioxide (TiO2) over a layer of polydopamine (PMMATiO2), smooth (Ti) and sandblasted (TiSB) titanium, and titanium treated with oxygen plasma (Tiox and TiSBox). Topography and surface chemistry were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Adhesion force between rods and porcine corneas was measured ex vivo. Titanium sleeves, smooth and sandblasted, were inserted around the stem of the B-KPro and implanted in rabbits. Tissue adhesion to the stem was assessed and compared to an unmodified B-Kpro after 1 month. Results X-ray photoelectron spectroscopy demonstrated successful deposition of TiO2 on polydopamine-coated PMMA. Oxygen plasma treatment did not change the XPS spectra of titanium rods (Ti and TiSB), although it increased their hydrophilicity. The materials did not show cell toxicity. After 14 days of incubation, PMMATiO2, smooth titanium treated with oxygen plasma (Tiox), and sandblasted titanium rods (TiSB, TiSBox) showed significantly higher adhesion forces than PMMA ex vivo. In vivo, the use of a TiSB sleeve around the stem of the B-KPro induced a significant increase in tissue adhesion compared to a Ti sleeve or bare PMMA. Conclusions Sandblasted titanium sleeves greatly enhanced adherence of the B-KPro to the rabbit cornea. This approach may improve adhesion with the donor cornea in humans as well. Translational Relevance This approach may improve adhesion with donor corneas in humans. PMID:27152247

  4. Reactivity of neodymium carriers in deep sea sediments: Implications for boundary exchange and paleoceanography

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Piotrowski, Alexander M.; Galy, Albert; Clegg, Josephine A.

    2013-05-01

    The dissolved neodymium (Nd) isotopic distribution in the deep oceans is determined by continental weathering inputs, water mass advection, and boundary exchange between particulate and dissolved fractions. Reconstructions of past Nd isotopic variability may therefore provide evidence on temporal changes in continental weathering inputs and/or ocean circulation patterns over a range of timescales. However, such an approach is limited by uncertainty in the mechanisms and importance of the boundary exchange process, and the challenge in reliably recovering past seawater Nd isotopic composition (ɛNd) from deep sea sediments. This study addresses these questions by investigating the processes involved in particulate-solution interactions and their impact on Nd isotopes. A better understanding of boundary exchange also has wider implications for the oceanic cycling and budgets of other particle-reactive elements. Sequential acid-reductive leaching experiments at pH ˜2-5 on deep sea sediments from the western Indian Ocean enable us to investigate natural boundary exchange processes over a timescale appropriate to laboratory experiments. We provide evidence that both the dissolution of solid phases and exchange processes influence the ɛNd of leachates, which suggests that both processes may contribute to boundary exchange. We use major element and rare earth element (REE) data to investigate the pools of Nd that are accessed and demonstrate that sediment leachate ɛNd values cannot always be explained by admixture between an authigenic component and the bulk detrital component. For example, in core WIND 24B, acid-reductive leaching generates ɛNd values between -11 and -6 as a function of solution/solid ratios and leaching times, whereas the authigenic components have ɛNd ≈ -11 and the bulk detrital component has ɛNd ≈ -15. We infer that leaching in the Mascarene Basin accesses authigenic components and a minor radiogenic volcanic component that is more reactive

  5. Dating scheelite stages: A strontium, neodymium, lead approach from the Felbertal tungsten deposit, Central Alps, Austria

    NASA Astrophysics Data System (ADS)

    Eichhorn, Roland; Höll, Rudolf; Jagout, Emil; Schärer, Urs

    1997-12-01

    New Sm-Nd, Rb-Sr, and Pb-Pb isotope data of scheelites and their host rocks from the Felbertal scheelite deposit (Central Tauern Window, Eastern Alps, Austria) are presented. The oldest stage 1 scheelites are rarely preserved. They plot together with recrystallized stage 2 scheelite porphyroblasts on a Sm-Nd isochron of 581 ± 105 Ma. This Sm-Nd age is regarded as the time of the primary tungsten mineralization. Our interpretation is enhanced by a (within error limits) similar age of 517 ± 114 Ma derived from a 207Pb/ 206Pb scheelite isochron and a date of 517 ± 130 Ma obtained from two co-genetic relics (a clinopyroxene and a tschermakitic amphibole) within a metapyroxenite. The stage 2 scheelite blastesis was possibly triggered by an still unassured Ordovician "Caledonian" metamorphism and further promoted by a Carboniferous granitoid intrusion and a Variscan metamorphism without an isotopic reset. Both yellowish-fluorescent, Mo-bearing stage 1 and stage 2 scheelites were formed under oxidizing, alkaline conditions, which obviously did not promote REE fractionation and did not disturb the original Sm-Nd isotopic system. This evidently was not the case during younger remobilizations in Late Variscan and Alpine metamorphic times when stage 3 (319 ± 34 Ma) and stage 4 (29 ± 17 Ma) scheelites formed. Both stages consist of bluish-fluorescent, Mopoor to Mo-free scheelites that reveal significant REE depletion and fractionation, probably due to repeated corrosion and re-precipitation under more reducing neutral to slightly acidic conditions. The source and mechanism of deposition of the primary tungsten mineralization are deduced from five facts: (1) the radiogenic strontium isotopic data of stage 1 scheelites ( 87Sr/86Sr = 0.726-0.730 ) occurring together with normal crustal neodymium isotopic compositions ( ɛCHURt + 1 = -3.8 to -7.3), (2) unusually high U concentrations up to 74 ppm in stage 1 scheelites, (3) a sudden 87Sr increase between the formation of

  6. Neodymium and carbon isotopic fingerprints of warm Pliocene circulation throughout the deep Atlantic

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Scher, H. D.; Dowsett, H. J.; Robinson, M. M.

    2013-12-01

    The mid-Piacenzian age of the Pliocene is the most recent interval in Earth's history to sustain global warmth within the range predicted for the 21st century. To understand this interval, the USGS PRISM Project has developed a reconstruction of global conditions at 3.264-3.025 Ma, which includes a significant North Atlantic warm SST anomaly coupled with increased evaporation. Warm anomalies are also detected in the deep ocean as far as 46°S, suggesting that enhanced meridional overturning circulation may have been responsible for more southerly penetration of North Atlantic Deep Water (NADW). However, deep temperature proxies are not diagnostic of water mass, and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy synthesis of Atlantic deep ocean circulation during the PRISM interval, using the neodymium isotopic composition (ɛNd) of fossil fish teeth as a proxy for water mass source and the δ13C of benthic foraminifera as a proxy for water mass age. This reconstruction utilizes both new and previously published data from 11 DSDP and ODP sites in the North Atlantic (Site 610) and along depth transects from equatorial Ceara Rise, southern mid-latitude Walvis Ridge, and south Atlantic Meteor Rise/Agulhas Ridge. Published data from ferromanganese crusts constrain Pliocene Antarctic deep waters at ~ ɛNd = -8, distinct from the less radiogenic ɛNd = -11.5 that characterizes Pliocene northern component water (NCW). These values fingerprint northern and southern sources throughout the Atlantic basin. Pliocene fish teeth from Site 610 (2400 m water depth) and from four Ceara Rise sites (3000-4300 m) preserve distinctly North Atlantic ɛNd. When averaged across the PRISM interval, mean values for these five sites range from ɛNd = -10.97 to -10.25, and the Pliocene depth transect closely mirrors the structure of the modern column, indicating

  7. Carbon and Neodymium Isotopic Fingerprints of Atlantic Deep Ocean Circulation During the Warm Pliocene

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Scher, H.; Robinson, M. M.; Dowsett, H. J.; Bell, D. B.

    2012-12-01

    Earth's future climate may resemble the mid-Piacenzian Age of the Pliocene, a time when global temperatures were sustained within the range predicted for the coming century. Surface and deep water temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm surface temperature anomaly in the mid-Piacenzian (3.264 - 3.025 Ma), accompanied by increased evaporation. The anomaly is detected in deep waters at 46°S, suggesting enhanced meridional overturning circulation and more southerly penetration of North Atlantic Deep Water (NADW) during the PRISM interval. However deep water temperature proxies are not diagnostic of water mass and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy investigation of Atlantic deep ocean circulation during the warm mid-Piacenzian, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic composition of fossil fish teeth (ɛNd) as a proxy for water mass source and mixing. This reconstruction utilizes both new and previously published data from DSDP and ODP cores along equatorial (Ceara Rise), southern mid-latitude (Walvis Ridge), and south Atlantic (Meteor Rise/Agulhas Ridge) depth transects. Additional end-member sites in the regions of modern north Atlantic and Southern Ocean deep water formation provide a Pliocene baseline for comparison. δ13C throughout the Atlantic basin is remarkably homogenous during the PRISM interval. δ13C values of Cibicidoides spp. and C. wuellerstorfi largely range between 0‰ and 1‰ at North Atlantic, shallow equatorial, southern mid-latitude, and south Atlantic sites with water depths from 2000-4700 m; both depth and latitudinal gradients are generally small (~0.3‰). However, equatorial

  8. Titanium-potassium heat pipe corrosion studies

    SciTech Connect

    Lundberg, L.B.

    1984-07-01

    An experimental study of the susceptibility of wickless titanium/potassium heat pipes to corrosive attack has been conducted in vacuo at 800/sup 0/K for 6511h and at 900/sup 0/K for 4797h without failure or degradation. Some movement of carbon, nitrogen and oxygen was observed in the titanium container tube, but no evidence of attack could be detected in metallographic cross sections of samples taken along the length of the heat pipes. The lack of observable attack of titanium by potassium under these conditions refutes previous reports of Ti-K incompatibility.

  9. Stress corrosion cracking of titanium alloys

    NASA Technical Reports Server (NTRS)

    Statler, G. R.; Spretnak, J. W.; Beck, F. H.; Fontana, M. G.

    1974-01-01

    The effect of hydrogen on the properties of metals, including titanium and its alloys, was investigated. The basic theories of stress corrosion of titanium alloys are reviewed along with the literature concerned with the effect of absorbed hydrogen on the mechanical properties of metals. Finally, the basic modes of metal fracture and their importance to this study is considered. The experimental work was designed to determine the effects of hydrogen concentration on the critical strain at which plastic instability along pure shear directions occurs. The materials used were titanium alloys Ti-8Al-lMo-lV and Ti-5Al-2.5Sn.

  10. Ultraviolet laser treatment of titanium surface

    NASA Astrophysics Data System (ADS)

    Balchev, Ivaylo; Minkovski, Nikolai; Dimitrov, Krasimir; Shipochka, Maria; Barbucha, Robert

    2016-02-01

    Interaction of a third harmonic of DPSS laser, wavelength 355 nm and pulse duration of 30 ns with titanium wafers was studied. It was investigated the structure of laser ablated titanium surface, depending on the laser beam scanning speed, and laser pulse frequency. The titanium surface modification was studied by scanning electron microscopy (SEM) and XPS (X- ray Photoelectron Spectroscopy). Nanosecond irradiation with ultraviolet light of Ti plate led to the formation of high porous granular structures consisting of agglomerated micro- and submicro- particles.

  11. Oxygen-Barrier Coating for Titanium

    NASA Technical Reports Server (NTRS)

    Clark, Ronald K.; Unnam, Jalaiah

    1987-01-01

    Oxygen-barrier coating for titanium developed to provide effective and low-cost means for protecting titanium alloys from oxygen in environment when alloys used in high-temperature mechanical or structural applications. Provides protective surface layer, which reduces extent of surface oxidation of alloy and forms barrier to diffusion of oxygen, limiting contamination of substrate alloy by oxygen. Consists of submicron layer of aluminum deposited on surface of titanium by electron-beam evaporation, with submicron layer of dioxide sputtered onto aluminum to form coat.

  12. Conductance fluctuations in nanostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Ningjia

    1997-12-01

    In this Ph.D thesis the conductance fluctuations of different physical origins in semi-conductor nanostructures were studied using both diagrammatic analytical methods and large scale numerical techniques. In the "mixed" transport regime where both mesoscopic and ballistic features play a role, for the first time I have analytically calculated the non-universal conductance fluctuations. This mixed regime is reached when impurities are distributed near the walls of a quantum wire, leaving the center region ballistic. I have discovered that the existence of a ballistic region destroys the universal conductance fluctuations. The crossover behavior of the fluctuation amplitude from the usual quasi-1D situation to that of the mixed regime is clearly revealed, and the role of various length scales are identified. My analytical predictions were confirmed by a direct numerical simulation by evaluating the Landauer formula. In another direction, I have made several studies of conductance or resistance oscillations and fluctuations in systems with artificial impurities in the ballistic regime. My calculation gave explanations of all the experimental results concerning the classical focusing peaks of the resistance versus magnetic field, the weak localization peak in a Sinai billiard system, the formation of a chaotic billiard, and predicted certain transport features which were indeed found experimentally. I have further extended the calculation to study the Hall resistance in a four-terminal quantum dot in which there is an antidot array. From my numerical data I analyzed the classical paths of electron motion and its quantum oscillations. The results compare well with recent experimental studies on similar systems. Since these billiard systems could provide quantum chaotic dynamics, I have made a detailed study of the consequence of such dynamics. In particular I have investigated the resonant transmission of electrons in these chaotic systems, and found that the level

  13. Controlled placement and orientation of nanostructures

    DOEpatents

    Zettl, Alex K; Yuzvinsky, Thomas D; Fennimore, Adam M

    2014-04-08

    A method for controlled deposition and orientation of molecular sized nanoelectromechanical systems (NEMS) on substrates is disclosed. The method comprised: forming a thin layer of polymer coating on a substrate; exposing a selected portion of the thin layer of polymer to alter a selected portion of the thin layer of polymer; forming a suspension of nanostructures in a solvent, wherein the solvent suspends the nanostructures and activates the nanostructures in the solvent for deposition; and flowing a suspension of nanostructures across the layer of polymer in a flow direction; thereby: depositing a nanostructure in the suspension of nanostructures only to the selected portion of the thin layer of polymer coating on the substrate to form a deposited nanostructure oriented in the flow direction. By selectively employing portions of the method above, complex NEMS may be built of simpler NEMSs components.

  14. Formation of a system of microcraters on a titanium surface by femtosecond laser radiation under rapid cooling conditions

    NASA Astrophysics Data System (ADS)

    Abramov, D. V.; Arakelyan, S. M.; Makov, S. A.; Prokoshev, V. G.; Khor'kov, K. S.

    2013-08-01

    Results of structuring a titanium surface with femtosecond laser radiation are reported. Formation of an ordered system of microcraters with a diameter of about 2 μm and a step of about 3 μm is observed. The character of this process is determined by the laser-beam transverse structure. The possibility of fixing the structures formed is provided by rapid cooling (using liquid nitrogen) of the laser-irradiated region. The potential of this treatment mode for nanostructuring surfaces of materials is considered.

  15. Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

    PubMed

    Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

    2014-06-17

    In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb). PMID:24934194

  16. CONTROL OF LASER RADIATION PARAMETERS: Passive Q switching of a neodymium laser by a Cr4+ : YAG crystal switch

    NASA Astrophysics Data System (ADS)

    Il'ichev, Nikolai N.; Gulyamova, E. S.; Pashinin, Pavel P.

    1997-11-01

    Theoretical and experimental investigations were made of passive Q switching of a neodymium laser by a Cr4+ : YAG switch. Analytic expressions were derived for estimating the output energy of the TEM00 mode of a passively Q-switched laser from the known parameters of the Cr4+ : YAG switch, of the active element, and of the cavity. The adopted description makes it possible to cover the range from generation of the first spike of a free-running transient to generation of a giant pulse. An experimental study was made of the dependence of the output energy on the cavity parameters, on the material of the active element (in this investigation it was Nd :YAG and Cr, Nd : GSGG), and on the angle of rotation of the Cr4+ : YAG switch. The experimental results obtained agreed to within 30% with calculations.

  17. From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy.

    PubMed

    Sachdeva, Ashutosh; Pickering, Edward M; Lee, Hans J

    2015-12-01

    Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP). PMID:26807284

  18. From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy

    PubMed Central

    Pickering, Edward M.; Lee, Hans J.

    2015-01-01

    Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP). PMID:26807284

  19. Comparative studies between theoretical and experimental of elastic properties and irradiation effects of soda lime glasses doped with neodymium oxide

    NASA Astrophysics Data System (ADS)

    Bootjomchai, C.

    2015-05-01

    A comparative studies on the theoretical and experimental values of elastic moduli of (90 - x) RWG -(10)Na2O -(x)Nd2O3 glass system, where RWG is recycled window glass and x is 0.001, 0.01, 0.1 and 1 mol%, was investigated. The radiation effects on structural properties and elastic moduli were evaluated by measuring the ultrasonic velocities. In addition, the FTIR spectra were measured to investigate the effects of irradiation on the structure of the glass. Moreover, the theoretical bond compression model was used to confirm the obtained results from the experiments. The results show that evidently changes in the structure of the glass depend on the concentration of the neodymium oxide and gamma irradiation. Furthermore, the experimental elastic moduli are in good agreement with the theoretical values.

  20. Linker-free deposition and adhesion of Photosystem I onto nanostructured TiO2 for biohybrid photoelectrochemical cells.

    PubMed

    Shah, Vivek B; Henson, William R; Chadha, Tandeep S; Lakin, Gerard; Liu, Haijun; Blankenship, Robert E; Biswas, Pratim

    2015-02-10

    Photosystem I (PSI) from oxygenic photosynthetic organisms is an attractive sensitizer for nano-biohybrid solar cells as it has a combined light-harvesting and reaction center in one protein complex and operates at a quantum yield close to one in biological systems. Using a linker-free deposition technique enabled by an electrospray system, PSI was coupled to 1-D nanostructured titanium dioxide thin films to fabricate an electrode for a photoelectrochemical cell. After deposition, the surfactant in the PSI aggregate was dissolved in the surfactant-free electrolyte, ensuring that partly hydrophobic PSI was not resuspended and stayed in contact with titanium dioxide. A maximum current density of 4.15 mA cm(-2) was measured after 10 min of electrospray deposition, and this is the highest current density reported so far for PSI-based photoelectrochemical cells. The high current is attributed to 1D nanostructure of titanium dioxide and orientation of the PSI onto the surface, which allows easy transfer of electrons. PMID:25540979