Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 330-332 (Feb. 2007), p. 161-164 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This study investigated the mixed alkali effect in a series of phosphate based glasses. Theseglasses were of the composition 0.5P2O5-0.2CaO-0.3-xNa2O-xK2O where x=0 to 0.3 in steps of 0.05.This study considered density measurements using Archimedes’s principle, thermal characterisation usingdifferential scanning calorimetry, phase analysis following crystallisation using X-ray powder diffraction(XRD), and degradation studies combined with ion release. The results showed that these mixed alkaliglasses showed a linear decrease in density, with the ternary single alkali glass with 0.3mol K2O showinga 3% reduction in density as compared to that with 0.3mol Na2O which correlated well with thedifference in ionic diameter and atomic weight of both cations. These glasses also showed intermediateglass transition temperature (Tg) values, compared to those of the ternary single alkali glasses having thesame alkali oxide content, and the minimum Tg value was recorded for equimolar amounts of both alkalioxides. However, they did not show any significant change in the degradation rate compared to the glasswith 0.3mol Na2O with the exception of the 0.25mol K2O glass. The single alkali glass with 0.3mol K2Oshowed a significant increase in the degradation rate by an approximate one order of magnitude. For themixed alkali glasses with low molar concentration of K2O, only sodium phosphate-rich phases[NaCa(PO3)3 and Na4Ca(PO3)6] were detected from XRD; at high molar concentrations however,potassium phosphate-rich phases [KCa(PO3)3 and KPO3] were detected. At equimolar concentration ofboth alkali cations, KCa(PO3)3 and Na4Ca(PO3)6 were identified. K+, Ca2+, and P3O93- release followedthe degradation behaviour where the highly degrading glasses with 0.25 and 0.3mol K2O released thehighest amount of these ions; however, there was no definite trend in the remaining glass compositions
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Composite coatings, consisting of calcium phosphate (CaP) ceramics and phosphate-based glass (P-glass), were obtained on a strong ZrO2 porous scaffold to improve biocompatibility by combining mechanical properties and biological activity. Powder mixtures of hydroxyapatite (HA) and P-glass in varying composition and content were dip-coated on a ZrO2 porous scaffold and heat-treated above 800°C for 2 h in air. During thermal treatment, substantial reaction and crystallization occurred, resulting in coating phases of HA, tricalcium phosphate (TCP), dicalcium phosphate (DCP), and surrounding glass. The CaP-glass coating layer was highly dense and uniform and adhered firmly to the ZrO2 scaffold. The adhesion strength of the coating layer as tested on a nonporous disk increased with increasing glass addition and decreasing CaO content in glass. The highest strength was about 40 MPa, an improvement of twice as high as that of pure HA coating. The osteoblastic cells grew and spread actively through the coated scaffolds. The differentiation of cells on the CaP coatings was much higher than that on ZrO2 substrate and comparable to or slightly higher than that on pure HA coating.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Ceramic Society 87 (2004), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) powders were synthesized by a sol–gel method for usage as bone filler and drug carrier. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol–water-based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of FHA powders. With heat treatment above 400°C, a characteristic apatite phase was observed for all the sol–gel powders. However, the crystallization temperature decreased with increasing fluoride addition. The tricalcium phosphate (TCP) phase formed in the pure HA powder above 800°C was attenuated in the FHA powders, confirming an enhanced phase stability of the FHA powders. Increasing the F− addition improved crystallinity and increased the crystallite size, as was determined from X-ray diffraction (XRD) analyses. The lattice parameters of the heat-treated powders varied corresponding to the fluoride addition, i.e., a gradual decrease in the a-axis, while little change in the c-axis was observed with increasing fluoride addition, indicating a nearly complete substitution of fluoride within the apatite lattice. However, little difference was observed with heat-treatment temperatures (400°–1000°C). The powders substituted with fluoride exhibited reduced dissolution rates in an in vitro solution as compared with the pure HA powder, suggesting the possibility of tailoring bioactivity with fluoride substitution.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Inc
    Journal of the American Ceramic Society 88 (2005), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Small amounts (1–5 vol%) of ammonium hydroxide (NH4OH) were added to the ethanol–water-based hydroxyapatite (HA) sol–gel solution. After aging the sol, a Ti substrate was dip-coated and heat-treated at 500°C for 1 h in air. The sol properties were monitored in terms of pH, viscosity, and structure changes with aging time; also, the coating phase and structure on Ti were investigated. During aging, the viscosity of the sol increased while the pH decreased, confirming the polymerization and gelation of the sol. The addition of NH4OH altered the sol properties significantly. Increase in the NH4OH concentration increased the pH and viscosity of the sol considerably, especially at short aging period, followed by a saturation with further aging. The Fourier transformed-infrared analysis also confirmed a gradual structure change of the sol with NH4OH addition. Such changes in pH, viscosity, and structure bands of the sol driven by the NH4OH addition were attributed to the improved polymerization and gelation of the sol. The improved gelation shortened the aging time needed for crystallization of the apatite coating, i.e., increase in the NH4OH addition improved the crystallization of the coatings. Within 24 h aging time, the coatings on Ti containing over 3.5 vol% NH4OH showed characteristic HA phase and structure bands, at which period no apatite peaks were observed on the HA coating obtained without NH4OH addition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 254-256 (Dec. 2003), p. 423-426 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 254-256 (Dec. 2003), p. 1103-1106 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 284-286 (Apr. 2005), p. 597-602 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Calcium phosphate-based glasses (PG) are of interest as both scaffold and delivery materials for tissue rebuilding because of their chemical similarity to bone. Since it is essential that these materials exhibit local and systemic biocompatibility and do not adversely affect host tissues, the present study was undertaken to examine the effects of PG containing different amounts of Ca on human T lymphocytes in vitro. This was carried out by measuring the effects of extracts of thePG on the direct and mitogen-induced activation of T cells from human peripheral blood, as well as assessing CD4 and CD8, surface antigens which define T-helper and T-suppressor cells, respectively. The results showed that DNA synthesis by resting T lymphocytes was unaffected by all the PG. However, extracts of the PG containing 24 mol% of Ca caused a very marked inhibition of mitogen-induced T cell activation. This PG also reduced both the resting CD4+ and CD8+ T cells, as well as activated CD8+ cells. In contrast, high Ca-PG significantly augmented DNA synthesis by mitogen-activated T cells. These experiments show that PG containing differing levels of Ca can have pronounced and differential effects on the activation and function of T lymphocytes in vitro
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 118-119 (Mar. 1996), p. 109-122 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...