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  • 1
    Electronic Resource
    Electronic Resource
    Stability of hydroxylapatite plasma-sprayed coated Ti−6AI−4V under cyclic bending in simulated physiological solutions (1994)
    Springer
    Journal of materials science 5 (1994), S. 457-462 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The aim of this research was to study the stability of plasma-sprayed eoated metal systems and to evaluate their susceptibility to the occurrence of corrosion fatigue. Hydroxylapatite plasma-sprayed coated samples of Ti−6AI−4V were studied under cyclic bending. During fatigue testing samples were immersed in a simulated physiological solution and mechanical and electrochemical degradation were monitored. Applied loads were intended to crack the ceramic coating and not the metal substrate. Electrochemical impedance spectroscopy was used to further characterize the electrochemical behaviour. No increase in tendency to corrode was detected in open-circuit corrosion fatigue testing. It appears as if the coating cracking does not increase metal substrate corrosion susceptibility. The coating integrity has been seriously affected, with marked decrease in thickness, due to the synergistic effect of load and presence of simulated body fluids environment. Impedance results, however, show a general tendency to an increase in corrosion kinetics after corrosion fatigue testing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058983
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro growth and differentiation of osteoblast-like human bone marrow cells on glass reinforced hydroxyapatite plasma-sprayed coatings (1999)
    Springer
    Journal of materials science 10 (1999), S. 567-576 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Human osteoblastic bone marrow cells were cultured for periods of up to 28 days in control conditions and on the surface of a glass reinforced hydroxyapatite composite (HA/G1) and commercial hydroxyapatite (HA) plasma-sprayed coatings, in the “as-received” condition and after immersion treatment in culture medium for 21 days. Cultures were characterized for total protein content and alkaline phosphatase activity. Scanning electron microscope analyses were performed on control cultures, seeded materials and materials incubated in the absence of cells. Culture media were analyzed for total and ionized calcium and phosphorus concentrations throughout the incubation period. Immersion of HA/G1 and HA coatings in culture medium resulted in significant alterations to the levels of calcium and phosphorus in the medium, leading to surface modifications. However, seeded material samples showed significant differences in the pattern of variation of the levels of these species. Cell proliferation was observed in the “as-received” HA/G1 composite, but cell mediated formation of mineral deposits was not proved. In contrast, “as-received” HA hardly supported cell growth. Previously immersed material samples showed cell proliferation and evidence of biological formation of mineral deposits. However, the HA/G1 composite presented better surface characteristics for cell growth as the behavior of bone marrow cells was closer to that observed in control cultures. © 1999 Kluwer Academic Publishers
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008924516146
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  • 3
    Electronic Resource
    Electronic Resource
    Liquid phase sintering of hydroxyapatite by phosphate and silicate glass additions: structure and properties of the composites (1995)
    Springer
    Journal of materials science 6 (1995), S. 348-352 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Phosphate- and silicate-based glasses were added to hydroxyapatite in order to improve its mechanical properties and to fabricate composites with different degrees of bioactivity. A strong chemical bonding was obtained between hydroxyapatite and the phosphate-based glasses leading to samples approaching theoretical density, according to density measurements and scanning electron microscopy. Bioglass® additions led to the formation of a complex calcium phosphate silicate which hampered the reinforcement process. The fracture toughness of the hydroxyapatite-glass composites was shown to be within the 1.1–1.2 MPam1/2 range, which is double that determined for sintered hydroxyapatite. A 2 μm thick apatite layer was observed on the surface of the hydroxyapatite-glass composites after 48 h immersion in a simulated human blood plasma, whereas only a few apatite crystals were detected on sintered hydroxyapatite after 7 days immersion. From the results obtained we anticipate that the composites might show a higher rate of bone bonding, leading to enhanced bioactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120303
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallinity and structural changes in HA plasma-sprayed coatings induced by cyclic loading in physiological media (1996)
    Springer
    Journal of materials science 7 (1996), S. 407-411 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In this study hydroxyapatite plasma-sprayed Ti-6Al-4V was characterized by X-ray diffraction (XRD) after being cyclically loaded, while immersed in two different testing environments: Hank's balanced salt solution (HBSS) and an isotonic saline solution (0.15 m NaCl). An original method was developed to test these systems under cyclic bending, while immersed in the testing solution. The crystallinity of the coating was calculated, before and after testing. Crystallinity changes were related to coating dissolution rates, measured by atomic absorption spectroscopy (AAS) and by a photocolourimetric method using ascorbic acid. Structural changes induced either by the plasma-spraying procedure or due to corrosion-fatigue tests, namely a preferential dissolution of the coating's amorphous phase, were also found in X-ray diffraction patterns. Long-term immersion tests, without any applied load, were carried out for assessing cyclic loading effects. An immersion for 2 years in static conditions was found to be equivalent to a cyclic test of 27.8 h in the same solution, as measured by the changes on the coating structure and by the amount of coating material lost to the solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122009
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  • 5
    Electronic Resource
    Electronic Resource
    In vitro calcium phosphate formation on SiO2-Na2O-CaO-P2O5 glass reinforced hydroxyapatite composite: a study by XPS analysis (1996)
    Springer
    Journal of materials science 7 (1996), S. 181-185 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: In-vitro apatite layer formation on the surface of a newly developed glass reinforced hydroxyapatite composite was characterized using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDXA). After 1 week soaking in an acellular simulated body fluid the composite surface was entirely covered by a Ca, P-layer, suggesting a bioactive behaviour. XPS binding energy results revealed that this surface layer was a carbonated and non-stoichiometric apatite with Ca/P ratio of 1.3. This apatite layer was composed of very fine needle-like crystallites. Comparative studies on a commercially available hydroxyapatite showed that a similar apatite layer was also formed on its surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121258
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  • 6
    Electronic Resource
    Electronic Resource
    Reinforcement of hydroxyapatite by adding P2O5-CaO glasses with Na2O, K2O and MgO (1996)
    Springer
    Journal of materials science 7 (1996), S. 187-189 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Commercial hydroxyapatite was reinforced by adding small amounts (2 and 4 wt%) of P2O5-based glasses during its sintering process. The composites prepared had a chemical composition closely related to the mineral part of bone tissues in terms of trace elements usually detected, such as Na, K and Mg. X-ray diffraction analysis (XRD) showed that the glass reinforced-HA composites were composed of a HA matrix and variable amounts of tricalcium phosphate phase, depending on sintering temperature and glass composition. These composites were shown to have much higher biaxial bending strength than sintered HA, 107 MPa for Ha/2% of 35P2O5-35CaO-10Na2O-10K2O-10MgO glass composite and 28 MPa for sintered HA. The presence of β-tricalcium phosphate in the microstructure of the composites is an important factor in the reinforcement process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121259
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  • 7
    Electronic Resource
    Electronic Resource
    Flow cytometry for assessing biocompatibility (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 649-656 
    Details
    ISSN: 0021-9304
    Keywords: flow cytometry ; cell culture ; biocompatibility ; biomaterials ; implants ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Flow cytometry (FCM) was examined as a possible procedure for measuring in vitro the biocompatibility of implant materials for orthopedic and dental surgery. The human osteoblast-like cell line MG63 was grown on hydroxyapatite (HA) and P2O5 glass-reinforced HA composite discs and compared with the same cells grown on polystyrene culture dishes. While morphological observation at the light and electron microscopic levels showed no major deleterious effects, FCM indicated that cell size was somewhat reduced, particularly by growth on the HA composite. Moreover, this material also appeared to delay the progression of the cells from the G0/G1 into the S phase of the cell cycle. In addition to this low level of inhibition of cell growth relative to control cultures, FCM analysis also demonstrated that the glass-reinforced HA caused some down-regulation of the expression of osteocalcin and fibronectin, two antigens which play a vital part in the integrity and function of bone and soft connective tissue, respectively. These results thus show, first, that although HA and the HA composite used in these experiments were generally biocompatible, they nevertheless had certain suboptimal effects on the cells; and second, that FCM could be a highly useful procedure for effectively screening and evaluating important biological responses to implant materials. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 649-656, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Glass-reinforced hydroxyapatite: A comprehensive study of the effect of glass composition on the crystallography of the composite (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 39 (1998), S. 244-251 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Glass-reinforced HA composites were produced using phosphate-based glasses, and a structure refinement was carried out to determine the effect of the glass on the structure of the residual HA. Quantitative phase analysis showed that the glass causes some of the HA to decompose to β-TCP and, at higher temperatures, to α-TCP. It also was indicated that when three phases were present, the formation of the α-TCP arose from decomposition of the β-TCP and not from further decomposition of HA to α-TCP. The unit cell dimensions showed a decrease in the a axis and an increase in the c axis, giving an overall unit cell decrease in volume. There also was a significant effect based on the amount of glass added. The changes found in the composite containing the 4 wt % glass were attributed to the loss of carbonate and loss of hydroxyl. This was expected to cause shrinkage in the unit cell; however this was not seen, and therefore the major changes in the unit cell were attributed to the ions from the glass taking an interstitial role in the HA structure, thus not allowing the unit cell to shrink as much as expected. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 244-251, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Pretreatments of improve the adhesion of electrodeposits on aluminium (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 519-528 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Aluminium is generally regarded as a metal that is difficult to plate. By using a pretreatment sequence, which includes immersion in a zincate solution, it is possible to electroplate aluminium successfully, although adhesion levels are not always very high. Zincate solutions modified by the addition of various ions have been shown to promote adhesion. Using one such solution, an investigation has been carried out as to how, by modifying the pretreatment sequence, the adhesion on electrodeposits on aluminium can be improved. Such modifications included varying the etch procedures and using the so-called double dip technique. Some of the factors giving rise to the improved adhesion of electrodeposits have been investigated by SEM, AES, SIMS, ESCA, EPMA and AAS.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740170720
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  • 10
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    Present Status and Future Perspectives of the NEXT Experiment (2014)
    J. J. Gómez Cadenas, V. Álvarez, F. I. G. Borges, S. Cárcel, J. Castel, S. Cebrián, A. Cervera, C. A. N. Conde, T. Dafni, T. H. V. T. Dias, J. Díaz, M. Egorov, R. Esteve, P. Evtoukhovitch, L. M. P. Fernandes, P. Ferrario, A. L. Ferreira, E. D. C. Freitas, V. M. Gehman, A. Gil, A. Goldschmidt, H. Gómez, D. González-Díaz, R. M. Gutiérrez, J. Hauptman, J. A. Hernando Morata, D. C. Herrera, F. J. Iguaz, I. G. Irastorza, M. A. Jinete, L. Labarga, A. Laing, I. Liubarsky, J. A. M. Lopes, D. Lorca, M. Losada, G. Luzón, A. Marí, J. Martín-Albo, A. Martínez, T. Miller, A. Moiseenko, F. Monrabal, M. Monserrate, C. M. B. Monteiro, F. J. Mora, L. M. Moutinho, J. Muñoz Vidal, H. Natal da Luz, G. Navarro, M. Nebot-Guinot, D. Nygren, C. A. B. Oliveira, R. Palma, Javier Pérez, J. L. Pérez-Aparicio, J. Renner, L. Ripoll, A. Rodríguez, J. Rodríguez, F. P. Santos, J. M. F. dos Santos, L. Seguí, L. Serra, D. Shuman, A. Simón, C. Sofka, M. Sorel, J. F. Toledo, A. Tomás, J. Torrent, Z. Tsamalaidze, J. F. C. A. Veloso, J. A. Villar, R. Webb, J. White, and N. Yahlali
    Hindawi
    Details
    Publication Date: 2014-03-19
    Description: NEXT is an experiment dedicated to neutrinoless double beta decay searches in xenon. The detector is a TPC, holding 100 kg of high-pressure xenon enriched in the 136Xe isotope. It is under construction in the Laboratorio Subterráneo de Canfranc in Spain, and it will begin operations in 2015. The NEXT detector concept provides an energy resolutionbetter than 1% FWHM and a topological signal that can be used to reduce the background. Furthermore, the NEXT technology can be extrapolated to a 1 ton-scale experiment.
    Print ISSN: 1687-7357
    Electronic ISSN: 1687-7365
    Topics: Physics
    Published by Hindawi
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