Library

X
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
    Structural measurements on evaporated a-Si/SiOx superlattices (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1274-1277 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The structure of evaporated a-Si/SiOx superlattices has been investigated by transmission electron microscopy, Raman scattering, and optical absorption spectroscopy. The layers are smooth and regular, but all three measurements show effects of bond distortions or defects within 1–2 nm of the Si/SiOx interfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339680
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Fluoride Analysis of Apatite Crystals with a Central Planar OCP Inclusion: Concerning the Role of F− Ions on Apatite/OCP/Apatite Structure Formation (1996)
    Springer
    Calcified tissue international 59 (1996), S. 377-384 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Fluoride — Octacalcium phosphate — Apatite — Fluoridation — Enamel mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. To study the roles of F− ions in the formation of apatite crystals embedding octacalcium phosphate (OCP) lamella in the center of apatite (Ap), a range of the Ap/OCP/Ap lamellar-mixed crystals were synthesized under various concentrations of fluoride ion (F−) from 0.1–1.0 ppm at pH 6.5 and 37°C. The products were analyzed for the F− incorporation, F− distribution, and the amount of OCP and Ap by chemical analysis, X-ray diffraction (XRD), electron probe microanalysis (EPMA), and nuclear magnetic resonance (NMR) techniques. The F− content and the amount of apatite in the crystalline product increased with an increase in the F− concentration in solution, whereas the amount of OCP and the yield of total product decreased. EPMA indicated that F− ions are distributed in the crystals almost homogeneously. The combined analysis suggested that a low-substituted fluoridated hydroxyapatite (FHAp) grew on a small amount of F−-containing OCP or on a surface-reaction layer of OCP, which has accumulated a small amount of F−. The roles of F− ions were hypothesized as the reduction of the growth rate and/or the critical thickness in the a*-axis direction of OCP, the enhancement of hydrolysis of OCP, and the activation of the growth of FHAp, resulting in thinner OCP lamella and thicker apatite lamella in the a*-axis direction with an increase in F− concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900143
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    High-resolution electron microscopy of octacalcium phosphate and its hydrolysis products (1984)
    Springer
    Calcified tissue international 36 (1984), S. 219-232 
    Details
    ISSN: 1432-0827
    Keywords: Octacalcium phosphate ; Hydroxyapatite ; Hydrolysis ; Lattice imaging ; Crystallographic disorder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The hydrolysis and dehydration products of synthetic octacalcium phosphate (OCP) were studied using X-ray diffraction, infrared spectroscopy, chemical analysis, and high-resolution electron microscopy (HREM). A “collapsed OCP” phase, identified by a characteristic 16.5 Å reflection in its X-ray diffraction pattern, was observed when OCP was dehydrated. High resolution electron microscopy of the hydrolyzed and partially hydrolyzed reaction products also revealed local contrast features with an approximate 16.5 Å periodicity. These features were consistent with a collapse of the OCP crystal structure and subsequent formation of epitaxial intergrowths of OCP and hydroxyapatite. Chemical analysis and X-ray diffraction of these samples were similar to previously reported calcium-deficient apatites. The hydrolysis of OCP to form calcium-deficient apatities is a reaction pathway which may be of importance in understanding the crystallographic changes occurring during the early stages of bone, calculus, and dental enamel formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405321
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    High resolution electron microscopy of nonstoichiometric apatite crystals (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 224 (1989), S. 265-276 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The application of high resolution electron microscopy, computer image processing, and image simulation techniques to the investigation of synthetic nonstoichiometric apatites has provided new details of apatite crystal growth mechanisms. Under certain precipitation conditions, calcium-deficient apatites with distinct octacalcium phosphate (OCP)-apatite intergrowths have been observed. Apatite crystals with unit-cell thick overgrowths of OCP on their surfaces confirmed the stepwise hydrolysis crystal growth mechanism initially proposed by Brown (Nature 196:1048-1050). However, many crystals also contained a central two-dimensional OCP inclusion one to two unit cells thick, embedded in an apatite matrix. Similar planar defects have been observed in dental enamel, dentin, and bone apatite crystals. We have developed a modified version of Brown's stepwise OCP hydrolysis apatite crystal growth mechanism to explain the formation of crystals with OCP central planar defects. The mechanism involves the nucleation of an OCP seed that grows until it reaches a critical size, rh, before OCP hydrolysis occurs. Apatite subsequently grows epitaxially on the OCP seed, thereby embedding it in the center of an apatite crystal. Apatite growth is facilitated by partial screw dislocations emanating from the planar defect.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092240217
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Crystallographic structure and surface morphology of sintered carbonated apatites (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 541-553 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Densely sintered synthetic hydroxyapatite (HA) is used as an implant material because of its excellent tissue biocompatibility. In order to maximize the biological potential of this calcium phosphate, we have investigated the incorporation of carbonate into HA to make a material which more closely resembles the mineral found in bones and teeth. The aim of the present study was to determine the conditions under which sintered carbonated apatites of specific carbonate content could be produced. The apatites were prepared by heating compressed pellets of precipitated carbonated apatite under a carbon dioxide/steam or nitrogen/steam atmosphere between 825 and 1050°C. The products were analyzed chemically and the surfaces examined by x-ray diffraction, infrared spectroscopy, reflected light microscopy, and scanning electron microscopy. The results showed that carbonate loss during sintering could be reliably predicted, making it possible to produce materials with specific carbonate content, and with specific physical and chemical composition.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820220609
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Quantitative analysis of early in vivo tissue response to synthetic apatite implants (1988)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 22 (1988), S. 137-148 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Studies have shown synthetic calcium phosphates such as hydroxyapatite and beta tricalcium phosphate to be biocompatible in vivo. However, few studies have quantitated histological responses to the implants.The aim of this study was to develop a method for the quantitative assessment of tissue biocompatibility to ceramic materials in vivo and to use this method to compare noncarbonated and carbonated apatite implants. Synthetic sintered apatites of 0, 3, and 6% carbonate by weight were prepared and cut into implants 4 × 4 × 1 mm. These were placed 2 mm into the medial aspect of rat fermurs. Following sacrifice at 4 weeks, the femurs were fixed in formalin, demineralized in formic acid, and embedded in glycol methacrylate. Sections were cut on an ultramicrotome set at 1.5 μm and stained with toluidine blue. A point counting technique using standard stereological grids and a low-power microscope was used to measure areas of new bone formation. The width of the connective tissue zone adjacent to muscle was measured using an image analyzer. All implants were well accepted by the host tissues judging from criteria of minimal inflammation and degree of fixation. Results showed an increase in new bone formed in the marrow cavity with increasing carbonate content. This may improve stability of the implant in the host bone, particularly during the initial healing period. A technique which should enable quantitative histological evaluation of different ceramic materials has been developed. The use of this method indicates that further studies are warranted to investigate carbonated apatite as an implant material.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820220206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...